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Exploration Robots for Harsh Environments and Safety
Proceedings of Intelligence the 2nd IFAC Conference oninEmbedded Computational and Telematics Control Systems, Proceedings of Intelligence the 2nd IFAC Conference oninEmbedded Computational and Telematics Control Systems, June 22-24, 2015. Slovenia Proceedings of theMaribor, 2nd IFAC Conference on Embedded Systems, Computational and Telematics Control Proceedings of Intelligence theMaribor, 2nd IFAC Conference onin June 22-24, 2015. Slovenia Available online at Systems, www.sciencedirect.com Computational Intelligence and Telematics inEmbedded Control June 22-24, 2015. Maribor, Slovenia Computational Intelligence and Telematics in Control June 22-24, 2015. Maribor, Slovenia June 22-24, 2015. Maribor, Slovenia
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Exploration Robots for Harsh and Safety IFAC-PapersOnLine 48-10 (2015)Environments 041–045 Exploration Robots for Harsh Environments and Safety Exploration Robots for Harsh Environments and Safety Exploration Robots for Harsh Environments and Safety J. Liu*, B.-Y. Ma*, N. Fry*, A, Pickering*, S. Whitehead***, N. Somjit**, R. C. Richardson*, Exploration Robots for Harsh Environments and Safety I. D. Robertson** J. Liu*, B.-Y. Ma*, N. Fry*, A, Pickering*, S. Whitehead***, N. Somjit**, R. C. Richardson*, I. D. Robertson**
J. Fry*, Pickering*, S. N. Somjit**, R. Richardson*, I. D. University J. Liu*, Liu*, B.-Y. B.-Y. Ma*, Ma*,* N. N. Fry*,ofA, A, Pickering*, S. Whitehead***, Whitehead***, N. of Somjit**, R. C. C. Richardson*, D. Robertson** Robertson** School Mechanical Engineering, Leeds, LS2 9JT, UK (e-mail: I. University J. Liu*, B.-Y. Ma*,* N. Fry*,ofA, Pickering*, S. Whitehead***, N. Somjit**, R. C. Richardson*, I. D. Robertson** School Mechanical Engineering, of Leeds, LS2 9JT, UK (e-mail: {mn07jhwl, mnbm, el10nrf, A.D.Pickering,R.C.Richardson}@leeds.ac.uk) University of Leeds, LS2 9JT, UK (e-mail: * School of Mechanical Engineering, {mn07jhwl, mnbm,and el10nrf, A.D.Pickering,R.C.Richardson}@leeds.ac.uk) School Mechanical Engineering, University of Leeds, LS2 UK (e-mail: ** **School ofof Electronic Electrical Engineering, University of 9JT, Leeds, LS2 9JT, UK School of Mechanical Engineering, University of Leeds, LS2 UK (e-mail: {mn07jhwl, mnbm, el10nrf, A.D.Pickering,R.C.Richardson}@leeds.ac.uk) ** School of Electronic and Electrical Engineering, University of 9JT, Leeds, LS2 9JT, UK {mn07jhwl, mnbm, el10nrf, A.D.Pickering,R.C.Richardson}@leeds.ac.uk) (Tel: +44 (0) 113 343 8207; e-mail: {N.Somjit, [email protected]). {mn07jhwl, mnbm, el10nrf, A.D.Pickering,R.C.Richardson}@leeds.ac.uk) ** of Electronic and Electrical Engineering, University (Tel: +44 (0) 113 343 e-mail: {N.Somjit, [email protected]). ** School School of Electronic and8207; Electrical University of of Leeds, Leeds, LS2 LS2 9JT, 9JT, UK UK *** Scoutek Ltd., Leeds, UKEngineering, (e-mail: [email protected]) ** School of Electronic and Electrical Engineering, University of Leeds, LS2 9JT, UK (Tel: +44 (0) 113 343 8207; e-mail: {N.Somjit, [email protected]). *** (0) Scoutek Ltd.,8207; Leeds, UK (e-mail: [email protected]) (Tel: +44 113 343 e-mail: {N.Somjit, [email protected]). (Tel: +44 (0) 113 343 8207; e-mail: {N.Somjit, [email protected]). *** *** Scoutek Scoutek Ltd., Ltd., Leeds, Leeds, UK UK (e-mail: (e-mail: [email protected]) [email protected]) *** Scoutek Ltd., Leeds, UK (e-mail: [email protected]) Abstract: In this paper the development and demonstration of various robotic systems for safety Abstract: In and thisharsh paperenvironments the development and demonstration of systems various assist robotic systems for safety applications are presented. These robotic human to monitor and Abstract: In this paper the development and demonstration of various robotic systems for safety applications and harsh environments are presented. These robotic systems assist human to monitor and Abstract: In this paper the development and demonstration of various robotic systems for safety explore various types of spaces and measure physical parameters of these spaces. Each individual robot Abstract: In this paper the development and demonstration of various robotic systems for safety applications and harsh environments are These robotic systems assist human to and explore various of spaces and measure physical parameters of these spaces. Each individual robot applications andtypes harsh environments are presented. presented. These robotic systems assist human to monitor monitor and can be equipped with of 3D ceramic-packaged multi-purpose sensors/actuators, smart navigation systems, applications andtypes harsh environments are presented. These robotic systems assist human to monitor and explore various spaces and measure physical parameters of these spaces. Each individual robot can be equipped with 3D ceramic-packaged multi-purpose sensors/actuators, smart navigation systems, explore various types of spaces and measure physical parameters of these spaces. Each individual robot and be reconfigurable high-speed wireless communication networking. The targeted applications are realexplore various types of spaces and measure physical parameters of these spaces. Each individual robot can equipped with 3D ceramic-packaged multi-purpose sensors/actuators, smart navigation systems, and reconfigurable high-speed wireless communication networking. The targeted applications are realcan equipped with 3D ceramic-packaged multi-purpose sensors/actuators, smart navigation systems, timebe monitoring/rescuing in various kinds of harmful networking. environments e.g.targeted deep mines, pipe and tube can be equipped with 3D ceramic-packaged multi-purpose sensors/actuators, smart navigation systems, and reconfigurable high-speed wireless communication The applications are realtime monitoring/rescuing in various kinds of harmful environments e.g. deep mines, pipe and tube and reconfigurable high-speed wireless communication networking. The targeted applications are realsystems, dramatically reducing risk of life and economic damage. and reconfigurable high-speed wireless communication networking. The targeted applications and are realtime monitoring/rescuing in kinds harmful environments systems, dramatically reducing risk of life andof time monitoring/rescuing in various various kinds ofeconomic harmful damage. environments e.g. e.g. deep deep mines, mines, pipe pipe and tube tube time monitoring/rescuing in various kinds of harmful environments e.g. deep mines, pipe and tube systems, dramatically reducing risk of life and economic damage. Keywords: Robotic exploration, harsh environments, safety and security, co-operative robot. © 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved. systems, dramatically reducing risk of life and economic damage. Keywords: Robotic exploration, harsh environments, safety and security, co-operative robot. systems, dramatically reducing risk of life and economic damage. Keywords: safety Keywords: Robotic Robotic exploration, exploration, harsh harsh environments, environments, safety and and security, security, co-operative co-operative robot. robot. Keywords: Robotic exploration, harsh environments, and security, co-operative robot. safety of 60 mm approximate thickness for the first stone and an 1. INTRODUCTION of 60 mm approximate thickness the firsteach stone and an unknown thickness for the for second; spaced 1. INTRODUCTION of 60 mm approximate thickness for the first stone and unknown thickness for the second; each spaced of 60 mm approximate thickness for the first stone and an an INTRODUCTION 200 mm apart. This paper presents1. the design and demonstration of three approximately of 60 mm approximate thickness for the first stone and an 1. INTRODUCTION unknown thickness for approximately 200 mm apart. This paper presents design which and demonstration of three unknown thickness for the the second; second; each each spaced spaced 1.the INTRODUCTION novel compact robotic systems, can be integrated with unknown thickness for the second; each spaced approximately 200 mm apart. This paper presents the design and demonstration of three novel compact roboticthe systems, can be integrated with approximately 200 mm apart. This paper presents design which and micro-sensors demonstration of highthree The specifications for the Djedi robot required the robot to 3D ceramic-packaged, multi-purpose and approximately 200 mm apart. This paper presents the design which and micro-sensors demonstration of highthree novel compact robotic systems, can be integrated with The specifications for the Djedi robotorrequired the robot to 3D ceramic-packaged, multi-purpose and novel compact robotic systems, which can be integrated with climb the air shafts with minimal no damage to the speed ad-hoc wireless communication systems. The targeted novel compact robotic multi-purpose systems, whichmicro-sensors can be integrated with climb The specifications for the Djedi robot required the robot to 3D ceramic-packaged, and highthe air shafts with minimal or no damage to the speed ad-hoc wireless communication systems. The targeted The specifications for the Djedi robot required the robot to 3D ceramic-packaged, multi-purpose micro-sensors and highpyramid walls, yetfor retain the capacity to obtain sufficient application is wireless for real-time monitoring and exploring folded The specifications the Djedi robot required the robot to 3D ceramic-packaged, multi-purpose micro-sensors and highclimb the air shafts with minimal or no damage to the speed ad-hoc communication systems. The targeted pyramid walls, yet retain the capacity to obtain sufficient application is for real-time monitoring and exploring folded climb the air shafts with minimal or no damage to the speed ad-hoc wireless communication systems. The targeted tractive force to safely navigate the steep inclines, smooth spaces under possible harmful conditions e.g. chemical climb the air shafts with minimal or no damage to the speed ad-hoc wireless communication systems. The targeted pyramid walls, retain the to obtain sufficient application is real-time monitoring and exploring folded toyet safely the steep inclines, smooth spaces under possible harmful conditions e.g. chemical pyramid walls, yet retain the capacity capacity tofrom obtain application is for for real-time monitoring folded surfaces force and counter thenavigate resultant forces the sufficient on-board leakages, pressure level, temperature andand gasexploring concentration in tractive pyramid walls, yet retain the capacity tofrom obtain sufficient application is for real-time monitoring and exploring folded tractive force to safely navigate the steep inclines, smooth spaces under possible harmful conditions e.g. chemical surfaces and counter the resultant forces the on-board leakages, pressure level, temperature and gas concentration in tractive force to safely navigate the steep inclines, smooth spaces under possible harmful conditions e.g. chemical drill. Building upon the testing of three prototypes using harsh environments as well as for security andconcentration archaeological tractive force to safely navigate the steep inclines, smooth spaces under possible harmful conditions e.g. chemical surfaces and counter the resultant forces from the on-board leakages, pressure level, temperature and gas in Building uponofthe the testing offorces three prototypes using harsh environments as well as for security andconcentration archaeological surfaces and counter resultant from the the on-board leakages, pressure level, temperature and gas in drill. different variations an inch worm mechanism, latest applications; decreasing the risk of life and economic surfaces and counter the forces from the the on-board leakages, pressure level, temperature and gas concentration in different drill. Building upon testing of prototypes using harsh as as security and archaeological variations an resultant inch worm mechanism, latest applications; decreasing risk of life economic drill. Building uponofthe the testing of three three prototypes using harsh environments environments as well wellthe as for for security and and archaeological design of the Djedi robot had two independently driven damage. drill. Building uponofthe testing of three prototypes using harsh environments as wellthe as for security and archaeological different an inch mechanism, the latest applications; ofvariations the Djedi robot hadworm two independently damage. different variations an same inch worm mechanism, thedriven latest applications; decreasing decreasing the risk risk of of life life and and economic economic design pinion carriages onof the rack, with one carriage for different variations of an inch worm mechanism, the latest applications; decreasing the risk of life and economic design of the Djedi robot had two independently driven damage. 2. DJEDI ROBOT: A PYRAMID EXPLORATION ROVER pinion carriages on the same rack, with one carriage for design of the Djedi robot had two independently driven damage. driving the robot through the shafts and the other for driving 2. DJEDI ROBOT: A PYRAMID EXPLORATION ROVER design of Djedi robot two with independently driven damage. pinion carriages on rack, for driving the the robot the had shafts the one othercarriage for driving carriages on the the same same rack,and with one carriage for 2. DJEDI ROVER the on-board drill.through The Great ROBOT: Pyramid A ofPYRAMID Giza is theEXPLORATION last remaining wonder of pinion pinion carriages on the same rack, with one carriage for 2. DJEDI ROBOT: A PYRAMID EXPLORATION ROVER driving the robot through the shafts and the other for driving the on-board drill.through the shafts and the other for driving The Great Pyramid of Giza is the last remaining wonder of driving the robot 2. DJEDI ROBOT: A PYRAMID EXPLORATION ROVER the ancient world. of TheGiza pyramid contains three wonder chambers, driving the robot through the shafts and the other for driving the on-board drill. The Great Pyramid is the last remaining of the ancient world. The pyramid three chambers, drill. the shaft walls and provide the necessary The Great the Pyramid Giza is the contains last remaining wonder of the To on-board brace against including king’sof and queen’s chamber. Airshafts have the on-board drill. the shaft walls and provide the necessary The Great the Pyramid of Giza is the contains last remaining wonder of To the ancient world. The pyramid three chambers, bracetoagainst including king’s and queen’s chamber. Airshafts have the ancient world. The pyramid contains three chambers, traction climb and provide stability during drilling, custom been discovered in both chambers, however the queen’s shaft To brace against the shaft walls and provide the necessary the ancient world. The pyramid contains three chambers, including the king’s and queen’s chamber. Airshafts have traction toagainst climbwere and provide stability during drilling, custom been discovered in both chambers, however the queen’s shaft To brace the shaft walls and provide the necessary including the king’s and queen’s chamber. Airshafts have linear actuators created with a silicon rubber brace pad has no obvious purpose nor does ithowever breach the outer face of To brace againstwere the provide shaft walls and provide the brace necessary including the king’s and chamber. have traction to and stability during drilling, custom been discovered in chambers, theAirshafts queen’s shaft actuators created with acontact silicon rubber pad has no obvious purpose norqueen’s does ithowever breach the outer face of linear traction toatclimb climb and The provide stability during drilling, custom beenpyramid discovered in both both chambers, queen’s shaft mounted the end. points of between the brace the structure, unlike the king’s chamber. Exploration tractionactuators toatclimb and The provide stability duringrubber drilling, been discovered in both chambers, however queen’s shaft mounted linear were created with aacontact silicon brace pad has no obvious purpose nor does it the outer face thethe end. points of inchworm thecustom brace the pyramid structure, unlike the king’s Exploration actuators were created with siliconbetween rubber brace pad hasthe nonorthern obvious purpose nor airshafts does it breach breach the the outer face of of linear actuators and wall from each step during the of and southern tochamber. answer mysteries linear actuators were created with a silicon rubber brace pad mounted at the end. The points of contact between the brace has no obvious purpose nor does it breach the outer face of the pyramid structure, unlike the king’s chamber. Exploration actuators and the wall from each inchworm step during the of the northern and southern airshafts to answer the mysteries mounted at the end. The points of contact between the brace the pyramid structure, unlike the king’s chamber. Exploration shaft ascent does not move (Figure 2), also the applied force of its purpose and construction required the use of specialised mounted at thethe end. Thefrom points of contact the brace actuators and wall each step during the the pyramid structure, unlike airshafts therequired king’s chamber. Exploration of the northern and southern to answer the mysteries shaft ascent (Figure 2), alsobetween the applied force of its purpose construction use of anddoes thetonot wall fromsurface. each inchworm inchworm step during the the northern and southern airshafts to the answer thespecialised mysteries is perpendicular themove wall These features combined mobile roboticand tools, such as the Djedi Pyramid Explorer actuators actuators and the wall from each inchworm step during the shaft ascent does not move (Figure 2), also the applied force of the northern and southern airshafts to answer the mysteries its purpose and construction required the use of specialised is perpendicular to the wall surface. These features combined mobile robotic tools, such as the Djedi Pyramid Explorer shaft ascent does not move (Figure 2), also the applied force of its purpose and construction required the use of specialised with the soft silicon pads resulted in a large reduction to the Robot (Figure 1) which in May 2010 performed a video shaft ascent does not move (Figure 2), also the applied force of its purpose and construction required the use of specialised is perpendicular to the wall surface. features combined mobile robotic tools, such as the Djedi Pyramid Explorer with thedamaging soft silicon resulted inThese aThe large reduction towere the Robot (Figure 1) which performed a ofvideo is perpendicular tothe thepads wallshaft surface. These features combined mobile robotic tools, suchin asMay the 2010 Djedi Pyramid Explorer risk of air walls. four wheels survey successfully, by climbing the full length the is perpendicular to the wall surface. These features combined mobile robotic tools, such as the Djedi Pyramid Explorer with the soft silicon pads resulted in a large reduction to the Robot (Figure 1) May performed of theserved air shaft walls. four wheels survey successfully, by in climbing the full length aa ofvideo the risk withunpowered thedamaging soft silicon pads resulted inallow aThe large reduction towere the Robot (Figure 1) which which in May 2010 2010 performed video left and only to Djedi to climb the southern air shaft. with the soft silicon pads resulted in a large reduction to the Robot (Figure 1) which in May 2010 performed a video risk of damaging the air shaft walls. The four wheels were survey by and served onlywalls. to allow Djedi to climbwere the southern air shaft. risk unpowered of damaging the air shaft The four wheels survey successfully, successfully, by climbing climbing the the full full length length of of the the left vertical step and to prevent dragging on the shaft floor. risk of damaging the air shaft walls. The four wheels were left unpowered and served only to allow Djedi to climb the survey successfully, by climbing the full length of the vertical southern air shaft. step andand to prevent on theDjedi shaft to floor. left unpowered served dragging only to allow climb the southern air shaft. left unpowered and served dragging only to allow Djedi to climb the Producedair from soft limestone of varying surface roughness, vertical step and to prevent on the shaft floor. southern shaft. vertical step and to prevent dragging on the shaft floor. Produced from soft limestone of varying surface roughness, The usestepofand3Dto prevent printingdragging technology was used almost vertical on the shaft floor. the air shafts are approximately 210 mm x 210 mm and spans Produced from soft limestone of varying surface roughness, The use offor3D printing technology was usedEnabling almost the air shafts are approximately 210 mm x 210 mm and spans exclusively the manufacture of the carriages. Produced from soft limestone of varying surface roughness, through different configurations for the northern and southern The use of printing technology was used almost Produced from soft limestone of roughness, the air shafts are 210 mm xx surface 210 mm and spans exclusively theof manufacture of with the carriages. The use offor3D 3D printing was usedEnabling almost through different configurations forvarying the and southern the air The shafts are approximately approximately 210 mmnorthern 210 mm and spans rapid productions chassistechnology parts complex features, The use of 3D printing technology was used almost shaft. southern shaft begins running horizontally for exclusively for the manufacture of the carriages. Enabling the air shafts are approximately 210 mm x 210 mm and spans through different configurations for the northern and southern rapid productions of chassis parts with complex features, exclusively for the manufacture of the carriages. Enabling shaft. The southern shaft begins running horizontally for which allowed forofmanufacture increasingly compact carriages to be through different configurations for theincline northern exclusively for the of the carriages. Enabling approximately 2m before rising at an of and 40° southern from the rapid productions chassis parts with complex features, through different configurations for the northern and southern shaft. The southern shaft begins running horizontally for allowed forof increasingly compact carriagesstep to and be rapid productions chassis parts with complex features, approximately 2 m before at an incline of 40° from the reduced in weight and size and therefore increase shaft. The spanning southern shaftrising begins running horizontally for which rapid productions of chassis parts with complex features, horizontal, approximately a further 62 m in length which allowed for increasingly compact carriages to be shaft. The spanning southern shaftrising begins running horizontally for reduced approximately 2 m before at an incline of 40° from the in weight and size and therefore increase step and which allowed for increasingly compact carriages to be horizontal, approximately a further 62 m in length drill length of the robot. approximately 2 mentrance. before rising at an incline of 40° from the which allowed for increasingly compact carriages to be from the chamber Additional obstacles exist within reduced in weight and size and therefore increase step and approximately 2 mentrance. before rising at an of 40° from the drill horizontal, spanning approximately aa incline further 62 m in length length the robot. reduced in of weight and size and therefore increase step and from the chamber Additional obstacles exist within horizontal, spanning approximately further 62 m in length reduced in weight and size and therefore increase step and the shafts such as a lateral step at about 30 m or the 40 mm drill length of the robot. horizontal, spanning approximately a further m length from the chamber Additional obstacles exist within length of thethe robot. the shafts such as entrance. amlateral at about 30shaft m62orare thein 40 mm drill Embedded into carriage chassis are eleven composite from thestep chamber entrance. Additional obstacles exist within drill length of thethe robot. vertical at 59 and atstep the top of the the main from the chamber entrance. Additional obstacles exist within the shafts such as a lateral step at about 30 m or the 40 mm Embedded into carriagesnake chassis eleven composite vertical step at 59 m and at the top of the shaft are the main cameras with an additional arm are camera attachment to the shafts such as a lateral step at about 30 m or the 40 mm objectives, which consists of two limestone blocking stones Embedded into the carriage chassis are eleven composite the shafts such as a lateral step at about 30 m or the 40 mm vertical step at 59 m and at the top of the shaft are the main cameras with an additional snake arm camera attachment to Embedded into the carriage chassis are eleven composite objectives, two blocking vertical stepwhich at 59 consists m and atofthe toplimestone of the shaft are thestones main Embedded into the carriage chassis are eleven composite with vertical stepwhich at 59 consists m and at the top of the shaft are the main cameras objectives, with an an additional additional snake snake arm arm camera camera attachment attachment to to objectives, consists of of two two limestone limestone blocking blocking stones stones 41 cameras cameras with an additional snake arm camera attachment to Copyright © which 2015 IFAC objectives, which consists of two limestone blocking stones Copyright © 2015 IFAC 41
2405-8963 Copyright©©2015, 2015IFAC IFAC (International Federation of Automatic Control) 41 Hosting by Elsevier Ltd. All rights reserved. Copyright 2015responsibility IFAC 41 Control. Peer review© of International Federation of Automatic Copyright ©under 2015 IFAC 41 10.1016/j.ifacol.2015.08.105
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replace the drill. Each camera is strategically positioned to provide a full field of view for all sides of the air shafts and vital components of the Djedi robot for visual monitoring. The findings from the climb revealed red ochre markings or hieratic characters previously unseen for thousands of years (Richardson, R 2013).
tunnel, using dual-tracked mobility system to move in parallel (as shown in Figure 3). When the situation requires the robot to be inserted into boreholes or navigate obstacles, it can transform into a snakelike configuration (as shown in Figure 4). The Minebot is designed to be deployable and retrievable through a 9.1m long, 41 mm diameter borehole into tunnels and to operate at long ranges in tunnels of approximately 200m long on a slight incline over rough terrain. Table 1. Minebot measurements Weight Fully deployed size Snake-like size Maximum speed
2.7 kg 33 x 335 x 455 mm 33 x 1199.5 x 31 mm 11.4 mm/s
Fig. 1. Djedi Southern Shaft Rover.
Fig. 2. Rendered images of the Djedi rover during different stages of the inchworm locomotion. Fig. 3. Fully deployed configuration of the Minebot. 3. MINEBOT: A DUAL-TRACK RECONFIGURABLE ROBOT The subterranean environments such as mines and tunnels are remote, inaccessible, and dangerous for human entry. Inherent dangers in environments motivate the use of robotic technology for addressing such challenges (Morris, A 2006). In order to inspect subterranean environment, it is common to drill small boreholes from the surface into what is expected to be the exploration area. The idea is to insert a small robot through the borehole, lower the robot into the subterranean space, and explore the area. However, there are still many challenges in terms of limited diameter of borehole and lack of illumination posed by boreholes exploration.
Fig. 4. Snake-like configuration of the Minebot. Provided with some approximate environmental specifications, the locomotion and deployment systems of the Minebot were developed. The diameter of the borehole was a fixed variable supplied from a portable borehole drilling device used to gain entry into the mine. Considering the small diameter of the borehole and its length, a limit of 35mm diameter for the entire Minebot during the deployment phase was agreed upon. This allowed for a value of torque to be calculated to compensate for the robots mass on an incline and frictional drag forces from the tether. Without the ability to replicate the Djedi robots ability to brace on two sections
In response to these challenges, a dual-tracked reconfigurable robot with on-board camera and Cree LED light, named Minebot, was developed at the University of Leeds. The Minebot is an imaging mobile system that can be lowered down through narrow passages, such as boreholes, for subterranean exploration. It can establish a remote, subterranean presence without unnecessary risk to humans. The Minebot is capable of reconfiguring to move inside the
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of wall, the Minebot replies on the weight to produce the required traction to travel the long distances.
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heights of over 7 times its height, and produce enough torque to climb up stairs angled up to 42°.
Extraction of the Minebot was also considered as essential for the mission brief. This resulted in the need for a high torque reversible joint capable of changing between the fully deployed state and the snake-like configuration with no assistance.
A variety of robotic methods have been developed for stair climbing, such as a rack and pinion arm to lift itself up each step (Wende, G 2004), a tri-wheeled design that interlocks with the stairs (Hirose, S 2001), a multilink mechanism with six driven wheels (Michaud, S 2002 ) or various humanoid designs. While these have all been shown to climb stairs they all rely on the robot being larger than an individual step. A tracked design with two separate sections and an actuated link joint was developed. Liu et al. (2005) analysed fundamental kinematics and dynamics for a tracked robot to climb stairs. The process is split into Riser Climbing, Riser Crossing, and Nose Line Climbing. A tall angled front is often used to aid riser climbing (Tao, Ou and Feng et al. 2012) but cannot be used in this case due to the height restriction. The two sections allow the robot to ascend the stairs without the Riser Climbing stage (Figure 5).
Fig. 5. Gearbox housing within track section.
Fig. 6. High torque with slender profile joint.
(a)
4. LETTERBOT: A FOLDED BUILDING EXPLORATION ROBOT The Police and other authorities often have to search buildings without prior knowledge of what hazards may be present. Large robots currently in use require a door or window to be broken before it can enter the building. LetterBot was designed to enable quick deployment into any building without requiring tools or damage. In the majority of locked properties the only damage free way to insert a robot is through the letterbox. The standard BS EN 13724:2002 (BSI 2002) gives the minimum dimensions of the slot to be 230x30mm. This gives a very tight height constraint requiring careful actuator selection. For the robot to provide information beyond that of a pole camera it is important that it can overcome stairs as reported by Nguyen et al. (Nguyen 2000).
(b) Fig. 5: (a) Sequence for a two sectioned robot to climb stairs. (b) Version 1 mechanism. Two versions of LetterBot have now been created. The mechanism used in the first was designed to be simple and robust. A very short lever arm and a 200N linear actuator make the front section lift around a one degree of freedom revolute joint as shown in Figure 5. The second version uses
To ensure the robot is capable of ascending all regular stairs, UK building regulations (HM Government 2013) were reviewed. Giving the requirement that the robot length is ≥443mm to span two steps, it will have to overcome step 43
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an adaptation of a “little-known” gear slider mechanism, Figure 6, (Chironis et al. 1996). To aid weight optimisation and complex geometries 3D printing was used for the first design. Version 2 used a steel base plate as a thin rigid base, with aluminium modules building up the rest of the chassis.
Fig. 6. Modified gear slider mechanism. Fig. 8. Free body diagram of robot on an incline.
Continuous tracks were chosen as they can be used with a smaller diameter driving wheel than sectioned tracks. The tracks were custom designed to enable the robot to grip the noses of steps while climbing and reduce the friction when turning. When climbing the angle reduces the friction force, the contact area is also much smaller. Therefore welded on profiles were designed to mesh with the steps like teeth of a gear. They also help keep the robot perpendicular to the stairs. Using analysis by Rastan et al. (2011) the pitch was found to be optimal at 20mm. As the robot uses a differential drive system to steer, large sideways frictional forces are generated during turning which can remove the tracks. The angled profiles reduce this drag as does hinging the robot in the middle to shorten the track length in contact.
These equations are valid for the free body diagram: ܨ = ܯ . ݃. sin(ߠ ),
(1)
ܨ = ܯ . ݃. cos(ߠ ).
(2)
ܨ ≤ ܨ . ߤ .
(3)
ܨ = ܥ . ݔ . ݃. sin(ߠ ) + ߤ . ܥ . ݔ . ݃. cos(ߠ ).
(4)
The pulling force Fp exerted by the robot is limited by the frictional coefficient between the robot and the floor surface (μn) and the normal force (Fr),
In order to overcome the frictional drag from the tether (Fc), the sum of the forces due to the cable need to be considered. If the friction coefficient between the cable and floor is (μc), the cable weight is Cm and xc is the length of the tether in meters. The force required to overcome the cable frictional drag is then calculated as:
Therefore, in order to climb the incline, the required pulling force is: ܨ = ܯ . ݃. sin(ߠ ) + ܥ . ݔ . ݃. [sin(ߠ ) + ߤ . cos(ߠ )]. (5)
The most straightforward method to increase the robots capability to climb steep inclines is to increase the friction coefficient between the robot and floor (μn) and decrease the friction coefficient between tether and floor (μc).
Fig. 7. Left, LetterBot v1 folded up and looking around. Right, v2 climbing stairs. 5. CLIMBING IDEAL INCLINES For a compact exploration robot to climb an incline of angle θa, a robot of mass Mr must generate sufficient pulling force Fp to overcome gravitational force Fg, frictional drag forces Fd, and the forces required to drag the tether Fc. The gravitational force can be resolved into a two components of force, one parallel to the ground and the other perpendicular to the ground.
In the case of the Djedi robot, the tether was custom made with a thin, low friction, sheath. As a result of the inch-worm mechanism the weight of the robot was designed for minimal weight (Mr) as the four linear actuators can exert the required normal force (Fr) to overcome the opposing forces. On the other hand, the Minebot and Letterbot with the tracked configurations will rely on the mass of the robot to provide the necessary force for sufficient traction.
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6. CONCLUSIONS
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higher and/or vertically orientated letterboxes with the capacity for additional sensor packages.
The Djedi robot operated as intended and reached the top of the southern shaft. The findings from the video survey provided valuable evidence towards the purpose and construction of the pyramid. The locomotion system was successful in protecting the pyramid from damage, as no surface marks in the shaft walls were observed after repeated climbs.
REFERENCES BSI. 2002. BS EN 13724:2002 Postal services. Apertures of private letter boxes and letter plates. Requirements and test methods. BSI. Chironis, N. P. 1996. Mechanisms and mechanical devices sourcebook. 2nd ed. London: McGraw-Hill Hirose, S. 2001. Super Mechano-System: New Perspective for Versatile Robotic System. In: RUS, D. & SINGH, S. (eds.) Experimental Robotics VII. Springer Berlin Heidelberg. pp.249-258. HM Government. 2013. The Building Regulations 2010, 2013 edition. Newcastle Upon Tyne: NBS. Liu, J. et al. 2005. Analysis of stairs-climbing ability for a tracked reconfigurable modular robot. Safety, Security and Rescue Robotics, Workshop, 2005 IEEE International, 6-9 June 2005, pp.36-41. Michaud, S. et al.. 2002. SOLERO: Solar powered exploration rover. Proceedings of the 7th ESA Workshop on Advanced Space Technologies for Robotics and Automation (ASTRA2002), Noordwijk, The Netherlands: Citeseer, Morris, A., Ferguson, D., Omohundro Z., Bradley D., Silver D., Baker C., et al. 2006. Recent developments in subterranean robotics. Journal of Field Robotics, vol. 23, pp. 35-57. Nguyen, H. G. and J. P. Bott. 2000. Robotics for law enforcement: Applications beyond explosive ordnance disposal. SPIE Proc. 4232: Technologies for Law Enforcement, pp.433-454. Rastan H. 2011. Mechanical Design for Track Robot Climbing Stairs. MASc thesis, University of Ottawa, Richardson R., Whitehead S., Ng T. C., Hawass Z., Pickering A, Rhodes S., et al.. 2013. The “Djedi” Robot Exploration of the Southern Shaft of the Queen's Chamber in the Great Pyramid of Giza, Egypt. Journal of Field Robotics, vol. 30, pp. 323-348 Tao, W., Ou Y. and Feng H.. 2012. Research on Dynamics and Stability in the Stairs-climbing of a Tracked Mobile Robot. Int J Adv Robotic Sys, 9(146) Wende, G.. StairBot 2004 [online]. [Accessed 06/12/2014]. http://www.stairbot.de/en_beschreib.htm.
The use of rapid prototyped bodywork proved to have sufficient strength to endure the forces experienced during manoeuvring in the shaft. A noticeable drawback to the inch worm locomotion was the robots low climbing speed. Taking up to four hours to ascend the shafts, this time was acceptable when just one or two ascents are planned, but if future surveys require the use of multiple tools, then the ascent time would be a serious issue. Deployment of the Minebot through a 3m long tube of 40mm diameter has been demonstrated successfully. Further testing in lab spaces has shown the Minebot to be capable of changing its deployments states with no assistance and also able to drive effortlessly in the dual track configuration on a wooden floor. However to achieve the operational distance of 200m to fully survey the proposed mine tunnel, the Minebot will require a large increase in weight to 6kg in order to supply the necessary traction. The current weight of 2.7kg allows the Minebot to survey up to a theoretical distance of 92m. A consequence of increasing the weight to 6kg is the robots undeployed length must also be increased which will affect either the deployed length or width. This could possibly affect the robots ability to navigate and this trade-off will require further study. LetterBot has successfully been deployed through a letter box and has climbed sets of stairs while returning HD video. The mechanism is robust, simple to maintain and has proven reliable over many test deployments. Version 2’s mechanism (Figure 6) gives a greater mechanical advantage and allows the front section to be both longer and heavier, so larger steps can be negotiated. However due to its added complexity there is a trade off in reliability. 7. FUTURE WORK Whilst the Minebot has been successfully tested in lab environments, future work will involve field testing in more realistic real world environments to find its capabilities to overcome rough terrain with debris and also its effective range in the mine environment. The inclusion of debris could allow for a larger coefficient of friction between robot and floor which would result in a greater range without the increase in robot mass however the low ground clearance may play a significant role in limiting range. Building upon the experiences and techniques used in the Minebot for condensing the electronics and mechanisms into smaller spaces, these techniques can be applied to further improve the next iteration of LetterBot. At which point the LetterBot will be improved for easier deployments through
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ScienceDirect
Exploration Robots for Harsh and Safety IFAC-PapersOnLine 48-10 (2015)Environments 041–045 Exploration Robots for Harsh Environments and Safety Exploration Robots for Harsh Environments and Safety Exploration Robots for Harsh Environments and Safety J. Liu*, B.-Y. Ma*, N. Fry*, A, Pickering*, S. Whitehead***, N. Somjit**, R. C. Richardson*, Exploration Robots for Harsh Environments and Safety I. D. Robertson** J. Liu*, B.-Y. Ma*, N. Fry*, A, Pickering*, S. Whitehead***, N. Somjit**, R. C. Richardson*, I. D. Robertson**
J. Fry*, Pickering*, S. N. Somjit**, R. Richardson*, I. D. University J. Liu*, Liu*, B.-Y. B.-Y. Ma*, Ma*,* N. N. Fry*,ofA, A, Pickering*, S. Whitehead***, Whitehead***, N. of Somjit**, R. C. C. Richardson*, D. Robertson** Robertson** School Mechanical Engineering, Leeds, LS2 9JT, UK (e-mail: I. University J. Liu*, B.-Y. Ma*,* N. Fry*,ofA, Pickering*, S. Whitehead***, N. Somjit**, R. C. Richardson*, I. D. Robertson** School Mechanical Engineering, of Leeds, LS2 9JT, UK (e-mail: {mn07jhwl, mnbm, el10nrf, A.D.Pickering,R.C.Richardson}@leeds.ac.uk) University of Leeds, LS2 9JT, UK (e-mail: * School of Mechanical Engineering, {mn07jhwl, mnbm,and el10nrf, A.D.Pickering,R.C.Richardson}@leeds.ac.uk) School Mechanical Engineering, University of Leeds, LS2 UK (e-mail: ** **School ofof Electronic Electrical Engineering, University of 9JT, Leeds, LS2 9JT, UK School of Mechanical Engineering, University of Leeds, LS2 UK (e-mail: {mn07jhwl, mnbm, el10nrf, A.D.Pickering,R.C.Richardson}@leeds.ac.uk) ** School of Electronic and Electrical Engineering, University of 9JT, Leeds, LS2 9JT, UK {mn07jhwl, mnbm, el10nrf, A.D.Pickering,R.C.Richardson}@leeds.ac.uk) (Tel: +44 (0) 113 343 8207; e-mail: {N.Somjit, [email protected]). {mn07jhwl, mnbm, el10nrf, A.D.Pickering,R.C.Richardson}@leeds.ac.uk) ** of Electronic and Electrical Engineering, University (Tel: +44 (0) 113 343 e-mail: {N.Somjit, [email protected]). ** School School of Electronic and8207; Electrical University of of Leeds, Leeds, LS2 LS2 9JT, 9JT, UK UK *** Scoutek Ltd., Leeds, UKEngineering, (e-mail: [email protected]) ** School of Electronic and Electrical Engineering, University of Leeds, LS2 9JT, UK (Tel: +44 (0) 113 343 8207; e-mail: {N.Somjit, [email protected]). *** (0) Scoutek Ltd.,8207; Leeds, UK (e-mail: [email protected]) (Tel: +44 113 343 e-mail: {N.Somjit, [email protected]). (Tel: +44 (0) 113 343 8207; e-mail: {N.Somjit, [email protected]). *** *** Scoutek Scoutek Ltd., Ltd., Leeds, Leeds, UK UK (e-mail: (e-mail: [email protected]) [email protected]) *** Scoutek Ltd., Leeds, UK (e-mail: [email protected]) Abstract: In this paper the development and demonstration of various robotic systems for safety Abstract: In and thisharsh paperenvironments the development and demonstration of systems various assist robotic systems for safety applications are presented. These robotic human to monitor and Abstract: In this paper the development and demonstration of various robotic systems for safety applications and harsh environments are presented. These robotic systems assist human to monitor and Abstract: In this paper the development and demonstration of various robotic systems for safety explore various types of spaces and measure physical parameters of these spaces. Each individual robot Abstract: In this paper the development and demonstration of various robotic systems for safety applications and harsh environments are These robotic systems assist human to and explore various of spaces and measure physical parameters of these spaces. Each individual robot applications andtypes harsh environments are presented. presented. These robotic systems assist human to monitor monitor and can be equipped with of 3D ceramic-packaged multi-purpose sensors/actuators, smart navigation systems, applications andtypes harsh environments are presented. These robotic systems assist human to monitor and explore various spaces and measure physical parameters of these spaces. Each individual robot can be equipped with 3D ceramic-packaged multi-purpose sensors/actuators, smart navigation systems, explore various types of spaces and measure physical parameters of these spaces. Each individual robot and be reconfigurable high-speed wireless communication networking. The targeted applications are realexplore various types of spaces and measure physical parameters of these spaces. Each individual robot can equipped with 3D ceramic-packaged multi-purpose sensors/actuators, smart navigation systems, and reconfigurable high-speed wireless communication networking. The targeted applications are realcan equipped with 3D ceramic-packaged multi-purpose sensors/actuators, smart navigation systems, timebe monitoring/rescuing in various kinds of harmful networking. environments e.g.targeted deep mines, pipe and tube can be equipped with 3D ceramic-packaged multi-purpose sensors/actuators, smart navigation systems, and reconfigurable high-speed wireless communication The applications are realtime monitoring/rescuing in various kinds of harmful environments e.g. deep mines, pipe and tube and reconfigurable high-speed wireless communication networking. The targeted applications are realsystems, dramatically reducing risk of life and economic damage. and reconfigurable high-speed wireless communication networking. The targeted applications and are realtime monitoring/rescuing in kinds harmful environments systems, dramatically reducing risk of life andof time monitoring/rescuing in various various kinds ofeconomic harmful damage. environments e.g. e.g. deep deep mines, mines, pipe pipe and tube tube time monitoring/rescuing in various kinds of harmful environments e.g. deep mines, pipe and tube systems, dramatically reducing risk of life and economic damage. Keywords: Robotic exploration, harsh environments, safety and security, co-operative robot. © 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved. systems, dramatically reducing risk of life and economic damage. Keywords: Robotic exploration, harsh environments, safety and security, co-operative robot. systems, dramatically reducing risk of life and economic damage. Keywords: safety Keywords: Robotic Robotic exploration, exploration, harsh harsh environments, environments, safety and and security, security, co-operative co-operative robot. robot. Keywords: Robotic exploration, harsh environments, and security, co-operative robot. safety of 60 mm approximate thickness for the first stone and an 1. INTRODUCTION of 60 mm approximate thickness the firsteach stone and an unknown thickness for the for second; spaced 1. INTRODUCTION of 60 mm approximate thickness for the first stone and unknown thickness for the second; each spaced of 60 mm approximate thickness for the first stone and an an INTRODUCTION 200 mm apart. This paper presents1. the design and demonstration of three approximately of 60 mm approximate thickness for the first stone and an 1. INTRODUCTION unknown thickness for approximately 200 mm apart. This paper presents design which and demonstration of three unknown thickness for the the second; second; each each spaced spaced 1.the INTRODUCTION novel compact robotic systems, can be integrated with unknown thickness for the second; each spaced approximately 200 mm apart. This paper presents the design and demonstration of three novel compact roboticthe systems, can be integrated with approximately 200 mm apart. This paper presents design which and micro-sensors demonstration of highthree The specifications for the Djedi robot required the robot to 3D ceramic-packaged, multi-purpose and approximately 200 mm apart. This paper presents the design which and micro-sensors demonstration of highthree novel compact robotic systems, can be integrated with The specifications for the Djedi robotorrequired the robot to 3D ceramic-packaged, multi-purpose and novel compact robotic systems, which can be integrated with climb the air shafts with minimal no damage to the speed ad-hoc wireless communication systems. The targeted novel compact robotic multi-purpose systems, whichmicro-sensors can be integrated with climb The specifications for the Djedi robot required the robot to 3D ceramic-packaged, and highthe air shafts with minimal or no damage to the speed ad-hoc wireless communication systems. The targeted The specifications for the Djedi robot required the robot to 3D ceramic-packaged, multi-purpose micro-sensors and highpyramid walls, yetfor retain the capacity to obtain sufficient application is wireless for real-time monitoring and exploring folded The specifications the Djedi robot required the robot to 3D ceramic-packaged, multi-purpose micro-sensors and highclimb the air shafts with minimal or no damage to the speed ad-hoc communication systems. The targeted pyramid walls, yet retain the capacity to obtain sufficient application is for real-time monitoring and exploring folded climb the air shafts with minimal or no damage to the speed ad-hoc wireless communication systems. The targeted tractive force to safely navigate the steep inclines, smooth spaces under possible harmful conditions e.g. chemical climb the air shafts with minimal or no damage to the speed ad-hoc wireless communication systems. The targeted pyramid walls, retain the to obtain sufficient application is real-time monitoring and exploring folded toyet safely the steep inclines, smooth spaces under possible harmful conditions e.g. chemical pyramid walls, yet retain the capacity capacity tofrom obtain application is for for real-time monitoring folded surfaces force and counter thenavigate resultant forces the sufficient on-board leakages, pressure level, temperature andand gasexploring concentration in tractive pyramid walls, yet retain the capacity tofrom obtain sufficient application is for real-time monitoring and exploring folded tractive force to safely navigate the steep inclines, smooth spaces under possible harmful conditions e.g. chemical surfaces and counter the resultant forces the on-board leakages, pressure level, temperature and gas concentration in tractive force to safely navigate the steep inclines, smooth spaces under possible harmful conditions e.g. chemical drill. Building upon the testing of three prototypes using harsh environments as well as for security andconcentration archaeological tractive force to safely navigate the steep inclines, smooth spaces under possible harmful conditions e.g. chemical surfaces and counter the resultant forces from the on-board leakages, pressure level, temperature and gas in Building uponofthe the testing offorces three prototypes using harsh environments as well as for security andconcentration archaeological surfaces and counter resultant from the the on-board leakages, pressure level, temperature and gas in drill. different variations an inch worm mechanism, latest applications; decreasing the risk of life and economic surfaces and counter the forces from the the on-board leakages, pressure level, temperature and gas concentration in different drill. Building upon testing of prototypes using harsh as as security and archaeological variations an resultant inch worm mechanism, latest applications; decreasing risk of life economic drill. Building uponofthe the testing of three three prototypes using harsh environments environments as well wellthe as for for security and and archaeological design of the Djedi robot had two independently driven damage. drill. Building uponofthe testing of three prototypes using harsh environments as wellthe as for security and archaeological different an inch mechanism, the latest applications; ofvariations the Djedi robot hadworm two independently damage. different variations an same inch worm mechanism, thedriven latest applications; decreasing decreasing the risk risk of of life life and and economic economic design pinion carriages onof the rack, with one carriage for different variations of an inch worm mechanism, the latest applications; decreasing the risk of life and economic design of the Djedi robot had two independently driven damage. 2. DJEDI ROBOT: A PYRAMID EXPLORATION ROVER pinion carriages on the same rack, with one carriage for design of the Djedi robot had two independently driven damage. driving the robot through the shafts and the other for driving 2. DJEDI ROBOT: A PYRAMID EXPLORATION ROVER design of Djedi robot two with independently driven damage. pinion carriages on rack, for driving the the robot the had shafts the one othercarriage for driving carriages on the the same same rack,and with one carriage for 2. DJEDI ROVER the on-board drill.through The Great ROBOT: Pyramid A ofPYRAMID Giza is theEXPLORATION last remaining wonder of pinion pinion carriages on the same rack, with one carriage for 2. DJEDI ROBOT: A PYRAMID EXPLORATION ROVER driving the robot through the shafts and the other for driving the on-board drill.through the shafts and the other for driving The Great Pyramid of Giza is the last remaining wonder of driving the robot 2. DJEDI ROBOT: A PYRAMID EXPLORATION ROVER the ancient world. of TheGiza pyramid contains three wonder chambers, driving the robot through the shafts and the other for driving the on-board drill. The Great Pyramid is the last remaining of the ancient world. The pyramid three chambers, drill. the shaft walls and provide the necessary The Great the Pyramid Giza is the contains last remaining wonder of the To on-board brace against including king’sof and queen’s chamber. Airshafts have the on-board drill. the shaft walls and provide the necessary The Great the Pyramid of Giza is the contains last remaining wonder of To the ancient world. The pyramid three chambers, bracetoagainst including king’s and queen’s chamber. Airshafts have the ancient world. The pyramid contains three chambers, traction climb and provide stability during drilling, custom been discovered in both chambers, however the queen’s shaft To brace against the shaft walls and provide the necessary the ancient world. The pyramid contains three chambers, including the king’s and queen’s chamber. Airshafts have traction toagainst climbwere and provide stability during drilling, custom been discovered in both chambers, however the queen’s shaft To brace the shaft walls and provide the necessary including the king’s and queen’s chamber. Airshafts have linear actuators created with a silicon rubber brace pad has no obvious purpose nor does ithowever breach the outer face of To brace againstwere the provide shaft walls and provide the brace necessary including the king’s and chamber. have traction to and stability during drilling, custom been discovered in chambers, theAirshafts queen’s shaft actuators created with acontact silicon rubber pad has no obvious purpose norqueen’s does ithowever breach the outer face of linear traction toatclimb climb and The provide stability during drilling, custom beenpyramid discovered in both both chambers, queen’s shaft mounted the end. points of between the brace the structure, unlike the king’s chamber. Exploration tractionactuators toatclimb and The provide stability duringrubber drilling, been discovered in both chambers, however queen’s shaft mounted linear were created with aacontact silicon brace pad has no obvious purpose nor does it the outer face thethe end. points of inchworm thecustom brace the pyramid structure, unlike the king’s Exploration actuators were created with siliconbetween rubber brace pad hasthe nonorthern obvious purpose nor airshafts does it breach breach the the outer face of of linear actuators and wall from each step during the of and southern tochamber. answer mysteries linear actuators were created with a silicon rubber brace pad mounted at the end. The points of contact between the brace has no obvious purpose nor does it breach the outer face of the pyramid structure, unlike the king’s chamber. Exploration actuators and the wall from each inchworm step during the of the northern and southern airshafts to answer the mysteries mounted at the end. The points of contact between the brace the pyramid structure, unlike the king’s chamber. Exploration shaft ascent does not move (Figure 2), also the applied force of its purpose and construction required the use of specialised mounted at thethe end. Thefrom points of contact the brace actuators and wall each step during the the pyramid structure, unlike airshafts therequired king’s chamber. Exploration of the northern and southern to answer the mysteries shaft ascent (Figure 2), alsobetween the applied force of its purpose construction use of anddoes thetonot wall fromsurface. each inchworm inchworm step during the the northern and southern airshafts to the answer thespecialised mysteries is perpendicular themove wall These features combined mobile roboticand tools, such as the Djedi Pyramid Explorer actuators actuators and the wall from each inchworm step during the shaft ascent does not move (Figure 2), also the applied force of the northern and southern airshafts to answer the mysteries its purpose and construction required the use of specialised is perpendicular to the wall surface. These features combined mobile robotic tools, such as the Djedi Pyramid Explorer shaft ascent does not move (Figure 2), also the applied force of its purpose and construction required the use of specialised with the soft silicon pads resulted in a large reduction to the Robot (Figure 1) which in May 2010 performed a video shaft ascent does not move (Figure 2), also the applied force of its purpose and construction required the use of specialised is perpendicular to the wall surface. features combined mobile robotic tools, such as the Djedi Pyramid Explorer with thedamaging soft silicon resulted inThese aThe large reduction towere the Robot (Figure 1) which performed a ofvideo is perpendicular tothe thepads wallshaft surface. These features combined mobile robotic tools, suchin asMay the 2010 Djedi Pyramid Explorer risk of air walls. four wheels survey successfully, by climbing the full length the is perpendicular to the wall surface. These features combined mobile robotic tools, such as the Djedi Pyramid Explorer with the soft silicon pads resulted in a large reduction to the Robot (Figure 1) May performed of theserved air shaft walls. four wheels survey successfully, by in climbing the full length aa ofvideo the risk withunpowered thedamaging soft silicon pads resulted inallow aThe large reduction towere the Robot (Figure 1) which which in May 2010 2010 performed video left and only to Djedi to climb the southern air shaft. with the soft silicon pads resulted in a large reduction to the Robot (Figure 1) which in May 2010 performed a video risk of damaging the air shaft walls. The four wheels were survey by and served onlywalls. to allow Djedi to climbwere the southern air shaft. risk unpowered of damaging the air shaft The four wheels survey successfully, successfully, by climbing climbing the the full full length length of of the the left vertical step and to prevent dragging on the shaft floor. risk of damaging the air shaft walls. The four wheels were left unpowered and served only to allow Djedi to climb the survey successfully, by climbing the full length of the vertical southern air shaft. step andand to prevent on theDjedi shaft to floor. left unpowered served dragging only to allow climb the southern air shaft. left unpowered and served dragging only to allow Djedi to climb the Producedair from soft limestone of varying surface roughness, vertical step and to prevent on the shaft floor. southern shaft. vertical step and to prevent dragging on the shaft floor. Produced from soft limestone of varying surface roughness, The usestepofand3Dto prevent printingdragging technology was used almost vertical on the shaft floor. the air shafts are approximately 210 mm x 210 mm and spans Produced from soft limestone of varying surface roughness, The use offor3D printing technology was usedEnabling almost the air shafts are approximately 210 mm x 210 mm and spans exclusively the manufacture of the carriages. Produced from soft limestone of varying surface roughness, through different configurations for the northern and southern The use of printing technology was used almost Produced from soft limestone of roughness, the air shafts are 210 mm xx surface 210 mm and spans exclusively theof manufacture of with the carriages. The use offor3D 3D printing was usedEnabling almost through different configurations forvarying the and southern the air The shafts are approximately approximately 210 mmnorthern 210 mm and spans rapid productions chassistechnology parts complex features, The use of 3D printing technology was used almost shaft. southern shaft begins running horizontally for exclusively for the manufacture of the carriages. Enabling the air shafts are approximately 210 mm x 210 mm and spans through different configurations for the northern and southern rapid productions of chassis parts with complex features, exclusively for the manufacture of the carriages. Enabling shaft. The southern shaft begins running horizontally for which allowed forofmanufacture increasingly compact carriages to be through different configurations for theincline northern exclusively for the of the carriages. Enabling approximately 2m before rising at an of and 40° southern from the rapid productions chassis parts with complex features, through different configurations for the northern and southern shaft. The southern shaft begins running horizontally for allowed forof increasingly compact carriagesstep to and be rapid productions chassis parts with complex features, approximately 2 m before at an incline of 40° from the reduced in weight and size and therefore increase shaft. The spanning southern shaftrising begins running horizontally for which rapid productions of chassis parts with complex features, horizontal, approximately a further 62 m in length which allowed for increasingly compact carriages to be shaft. The spanning southern shaftrising begins running horizontally for reduced approximately 2 m before at an incline of 40° from the in weight and size and therefore increase step and which allowed for increasingly compact carriages to be horizontal, approximately a further 62 m in length drill length of the robot. approximately 2 mentrance. before rising at an incline of 40° from the which allowed for increasingly compact carriages to be from the chamber Additional obstacles exist within reduced in weight and size and therefore increase step and approximately 2 mentrance. before rising at an of 40° from the drill horizontal, spanning approximately aa incline further 62 m in length length the robot. reduced in of weight and size and therefore increase step and from the chamber Additional obstacles exist within horizontal, spanning approximately further 62 m in length reduced in weight and size and therefore increase step and the shafts such as a lateral step at about 30 m or the 40 mm drill length of the robot. horizontal, spanning approximately a further m length from the chamber Additional obstacles exist within length of thethe robot. the shafts such as entrance. amlateral at about 30shaft m62orare thein 40 mm drill Embedded into carriage chassis are eleven composite from thestep chamber entrance. Additional obstacles exist within drill length of thethe robot. vertical at 59 and atstep the top of the the main from the chamber entrance. Additional obstacles exist within the shafts such as a lateral step at about 30 m or the 40 mm Embedded into carriagesnake chassis eleven composite vertical step at 59 m and at the top of the shaft are the main cameras with an additional arm are camera attachment to the shafts such as a lateral step at about 30 m or the 40 mm objectives, which consists of two limestone blocking stones Embedded into the carriage chassis are eleven composite the shafts such as a lateral step at about 30 m or the 40 mm vertical step at 59 m and at the top of the shaft are the main cameras with an additional snake arm camera attachment to Embedded into the carriage chassis are eleven composite objectives, two blocking vertical stepwhich at 59 consists m and atofthe toplimestone of the shaft are thestones main Embedded into the carriage chassis are eleven composite with vertical stepwhich at 59 consists m and at the top of the shaft are the main cameras objectives, with an an additional additional snake snake arm arm camera camera attachment attachment to to objectives, consists of of two two limestone limestone blocking blocking stones stones 41 cameras cameras with an additional snake arm camera attachment to Copyright © which 2015 IFAC objectives, which consists of two limestone blocking stones Copyright © 2015 IFAC 41
2405-8963 Copyright©©2015, 2015IFAC IFAC (International Federation of Automatic Control) 41 Hosting by Elsevier Ltd. All rights reserved. Copyright 2015responsibility IFAC 41 Control. Peer review© of International Federation of Automatic Copyright ©under 2015 IFAC 41 10.1016/j.ifacol.2015.08.105
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replace the drill. Each camera is strategically positioned to provide a full field of view for all sides of the air shafts and vital components of the Djedi robot for visual monitoring. The findings from the climb revealed red ochre markings or hieratic characters previously unseen for thousands of years (Richardson, R 2013).
tunnel, using dual-tracked mobility system to move in parallel (as shown in Figure 3). When the situation requires the robot to be inserted into boreholes or navigate obstacles, it can transform into a snakelike configuration (as shown in Figure 4). The Minebot is designed to be deployable and retrievable through a 9.1m long, 41 mm diameter borehole into tunnels and to operate at long ranges in tunnels of approximately 200m long on a slight incline over rough terrain. Table 1. Minebot measurements Weight Fully deployed size Snake-like size Maximum speed
2.7 kg 33 x 335 x 455 mm 33 x 1199.5 x 31 mm 11.4 mm/s
Fig. 1. Djedi Southern Shaft Rover.
Fig. 2. Rendered images of the Djedi rover during different stages of the inchworm locomotion. Fig. 3. Fully deployed configuration of the Minebot. 3. MINEBOT: A DUAL-TRACK RECONFIGURABLE ROBOT The subterranean environments such as mines and tunnels are remote, inaccessible, and dangerous for human entry. Inherent dangers in environments motivate the use of robotic technology for addressing such challenges (Morris, A 2006). In order to inspect subterranean environment, it is common to drill small boreholes from the surface into what is expected to be the exploration area. The idea is to insert a small robot through the borehole, lower the robot into the subterranean space, and explore the area. However, there are still many challenges in terms of limited diameter of borehole and lack of illumination posed by boreholes exploration.
Fig. 4. Snake-like configuration of the Minebot. Provided with some approximate environmental specifications, the locomotion and deployment systems of the Minebot were developed. The diameter of the borehole was a fixed variable supplied from a portable borehole drilling device used to gain entry into the mine. Considering the small diameter of the borehole and its length, a limit of 35mm diameter for the entire Minebot during the deployment phase was agreed upon. This allowed for a value of torque to be calculated to compensate for the robots mass on an incline and frictional drag forces from the tether. Without the ability to replicate the Djedi robots ability to brace on two sections
In response to these challenges, a dual-tracked reconfigurable robot with on-board camera and Cree LED light, named Minebot, was developed at the University of Leeds. The Minebot is an imaging mobile system that can be lowered down through narrow passages, such as boreholes, for subterranean exploration. It can establish a remote, subterranean presence without unnecessary risk to humans. The Minebot is capable of reconfiguring to move inside the
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of wall, the Minebot replies on the weight to produce the required traction to travel the long distances.
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heights of over 7 times its height, and produce enough torque to climb up stairs angled up to 42°.
Extraction of the Minebot was also considered as essential for the mission brief. This resulted in the need for a high torque reversible joint capable of changing between the fully deployed state and the snake-like configuration with no assistance.
A variety of robotic methods have been developed for stair climbing, such as a rack and pinion arm to lift itself up each step (Wende, G 2004), a tri-wheeled design that interlocks with the stairs (Hirose, S 2001), a multilink mechanism with six driven wheels (Michaud, S 2002 ) or various humanoid designs. While these have all been shown to climb stairs they all rely on the robot being larger than an individual step. A tracked design with two separate sections and an actuated link joint was developed. Liu et al. (2005) analysed fundamental kinematics and dynamics for a tracked robot to climb stairs. The process is split into Riser Climbing, Riser Crossing, and Nose Line Climbing. A tall angled front is often used to aid riser climbing (Tao, Ou and Feng et al. 2012) but cannot be used in this case due to the height restriction. The two sections allow the robot to ascend the stairs without the Riser Climbing stage (Figure 5).
Fig. 5. Gearbox housing within track section.
Fig. 6. High torque with slender profile joint.
(a)
4. LETTERBOT: A FOLDED BUILDING EXPLORATION ROBOT The Police and other authorities often have to search buildings without prior knowledge of what hazards may be present. Large robots currently in use require a door or window to be broken before it can enter the building. LetterBot was designed to enable quick deployment into any building without requiring tools or damage. In the majority of locked properties the only damage free way to insert a robot is through the letterbox. The standard BS EN 13724:2002 (BSI 2002) gives the minimum dimensions of the slot to be 230x30mm. This gives a very tight height constraint requiring careful actuator selection. For the robot to provide information beyond that of a pole camera it is important that it can overcome stairs as reported by Nguyen et al. (Nguyen 2000).
(b) Fig. 5: (a) Sequence for a two sectioned robot to climb stairs. (b) Version 1 mechanism. Two versions of LetterBot have now been created. The mechanism used in the first was designed to be simple and robust. A very short lever arm and a 200N linear actuator make the front section lift around a one degree of freedom revolute joint as shown in Figure 5. The second version uses
To ensure the robot is capable of ascending all regular stairs, UK building regulations (HM Government 2013) were reviewed. Giving the requirement that the robot length is ≥443mm to span two steps, it will have to overcome step 43
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an adaptation of a “little-known” gear slider mechanism, Figure 6, (Chironis et al. 1996). To aid weight optimisation and complex geometries 3D printing was used for the first design. Version 2 used a steel base plate as a thin rigid base, with aluminium modules building up the rest of the chassis.
Fig. 6. Modified gear slider mechanism. Fig. 8. Free body diagram of robot on an incline.
Continuous tracks were chosen as they can be used with a smaller diameter driving wheel than sectioned tracks. The tracks were custom designed to enable the robot to grip the noses of steps while climbing and reduce the friction when turning. When climbing the angle reduces the friction force, the contact area is also much smaller. Therefore welded on profiles were designed to mesh with the steps like teeth of a gear. They also help keep the robot perpendicular to the stairs. Using analysis by Rastan et al. (2011) the pitch was found to be optimal at 20mm. As the robot uses a differential drive system to steer, large sideways frictional forces are generated during turning which can remove the tracks. The angled profiles reduce this drag as does hinging the robot in the middle to shorten the track length in contact.
These equations are valid for the free body diagram: ܨ = ܯ . ݃. sin(ߠ ),
(1)
ܨ = ܯ . ݃. cos(ߠ ).
(2)
ܨ ≤ ܨ . ߤ .
(3)
ܨ = ܥ . ݔ . ݃. sin(ߠ ) + ߤ . ܥ . ݔ . ݃. cos(ߠ ).
(4)
The pulling force Fp exerted by the robot is limited by the frictional coefficient between the robot and the floor surface (μn) and the normal force (Fr),
In order to overcome the frictional drag from the tether (Fc), the sum of the forces due to the cable need to be considered. If the friction coefficient between the cable and floor is (μc), the cable weight is Cm and xc is the length of the tether in meters. The force required to overcome the cable frictional drag is then calculated as:
Therefore, in order to climb the incline, the required pulling force is: ܨ = ܯ . ݃. sin(ߠ ) + ܥ . ݔ . ݃. [sin(ߠ ) + ߤ . cos(ߠ )]. (5)
The most straightforward method to increase the robots capability to climb steep inclines is to increase the friction coefficient between the robot and floor (μn) and decrease the friction coefficient between tether and floor (μc).
Fig. 7. Left, LetterBot v1 folded up and looking around. Right, v2 climbing stairs. 5. CLIMBING IDEAL INCLINES For a compact exploration robot to climb an incline of angle θa, a robot of mass Mr must generate sufficient pulling force Fp to overcome gravitational force Fg, frictional drag forces Fd, and the forces required to drag the tether Fc. The gravitational force can be resolved into a two components of force, one parallel to the ground and the other perpendicular to the ground.
In the case of the Djedi robot, the tether was custom made with a thin, low friction, sheath. As a result of the inch-worm mechanism the weight of the robot was designed for minimal weight (Mr) as the four linear actuators can exert the required normal force (Fr) to overcome the opposing forces. On the other hand, the Minebot and Letterbot with the tracked configurations will rely on the mass of the robot to provide the necessary force for sufficient traction.
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6. CONCLUSIONS
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higher and/or vertically orientated letterboxes with the capacity for additional sensor packages.
The Djedi robot operated as intended and reached the top of the southern shaft. The findings from the video survey provided valuable evidence towards the purpose and construction of the pyramid. The locomotion system was successful in protecting the pyramid from damage, as no surface marks in the shaft walls were observed after repeated climbs.
REFERENCES BSI. 2002. BS EN 13724:2002 Postal services. Apertures of private letter boxes and letter plates. Requirements and test methods. BSI. Chironis, N. P. 1996. Mechanisms and mechanical devices sourcebook. 2nd ed. London: McGraw-Hill Hirose, S. 2001. Super Mechano-System: New Perspective for Versatile Robotic System. In: RUS, D. & SINGH, S. (eds.) Experimental Robotics VII. Springer Berlin Heidelberg. pp.249-258. HM Government. 2013. The Building Regulations 2010, 2013 edition. Newcastle Upon Tyne: NBS. Liu, J. et al. 2005. Analysis of stairs-climbing ability for a tracked reconfigurable modular robot. Safety, Security and Rescue Robotics, Workshop, 2005 IEEE International, 6-9 June 2005, pp.36-41. Michaud, S. et al.. 2002. SOLERO: Solar powered exploration rover. Proceedings of the 7th ESA Workshop on Advanced Space Technologies for Robotics and Automation (ASTRA2002), Noordwijk, The Netherlands: Citeseer, Morris, A., Ferguson, D., Omohundro Z., Bradley D., Silver D., Baker C., et al. 2006. Recent developments in subterranean robotics. Journal of Field Robotics, vol. 23, pp. 35-57. Nguyen, H. G. and J. P. Bott. 2000. Robotics for law enforcement: Applications beyond explosive ordnance disposal. SPIE Proc. 4232: Technologies for Law Enforcement, pp.433-454. Rastan H. 2011. Mechanical Design for Track Robot Climbing Stairs. MASc thesis, University of Ottawa, Richardson R., Whitehead S., Ng T. C., Hawass Z., Pickering A, Rhodes S., et al.. 2013. The “Djedi” Robot Exploration of the Southern Shaft of the Queen's Chamber in the Great Pyramid of Giza, Egypt. Journal of Field Robotics, vol. 30, pp. 323-348 Tao, W., Ou Y. and Feng H.. 2012. Research on Dynamics and Stability in the Stairs-climbing of a Tracked Mobile Robot. Int J Adv Robotic Sys, 9(146) Wende, G.. StairBot 2004 [online]. [Accessed 06/12/2014]. http://www.stairbot.de/en_beschreib.htm.
The use of rapid prototyped bodywork proved to have sufficient strength to endure the forces experienced during manoeuvring in the shaft. A noticeable drawback to the inch worm locomotion was the robots low climbing speed. Taking up to four hours to ascend the shafts, this time was acceptable when just one or two ascents are planned, but if future surveys require the use of multiple tools, then the ascent time would be a serious issue. Deployment of the Minebot through a 3m long tube of 40mm diameter has been demonstrated successfully. Further testing in lab spaces has shown the Minebot to be capable of changing its deployments states with no assistance and also able to drive effortlessly in the dual track configuration on a wooden floor. However to achieve the operational distance of 200m to fully survey the proposed mine tunnel, the Minebot will require a large increase in weight to 6kg in order to supply the necessary traction. The current weight of 2.7kg allows the Minebot to survey up to a theoretical distance of 92m. A consequence of increasing the weight to 6kg is the robots undeployed length must also be increased which will affect either the deployed length or width. This could possibly affect the robots ability to navigate and this trade-off will require further study. LetterBot has successfully been deployed through a letter box and has climbed sets of stairs while returning HD video. The mechanism is robust, simple to maintain and has proven reliable over many test deployments. Version 2’s mechanism (Figure 6) gives a greater mechanical advantage and allows the front section to be both longer and heavier, so larger steps can be negotiated. However due to its added complexity there is a trade off in reliability. 7. FUTURE WORK Whilst the Minebot has been successfully tested in lab environments, future work will involve field testing in more realistic real world environments to find its capabilities to overcome rough terrain with debris and also its effective range in the mine environment. The inclusion of debris could allow for a larger coefficient of friction between robot and floor which would result in a greater range without the increase in robot mass however the low ground clearance may play a significant role in limiting range. Building upon the experiences and techniques used in the Minebot for condensing the electronics and mechanisms into smaller spaces, these techniques can be applied to further improve the next iteration of LetterBot. At which point the LetterBot will be improved for easier deployments through
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