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Robot for Finishing Voluntarily Oriented Surfaces
ROBOT FOR FINISHING VOLUNTARILY ORIENTED SURFACES V.KRASNOSLOBODSEV SI pezersburg Slale Technical University. ~partmenl 01 Aulomatic Machines. St Petersburg. RMssia
Abstract. The paper deals with mobile robots to be employed for processing IItlOOIh voluntary oriented surfaces include those of vertical and ceiling type. The robots retain to the worlc.ing surfaces and move along them due to the use of vacuum. In this paper continuous and step-by-step principles of the robot movement are discussed. Various aspects of vacuum application to retain the robots to the smooth and also to damaged surfaces are analyzed. Robot orientation systems incorporating pendulum pick-up of electromechanic .a nd vacuum type are examined, as well as the robot control systems of cable and remote (infrared) type. K~y
Words. Mobile robot; vacuum; continuous and step-by-step movement; pendulum pick-Up; control systems
mobile module retaining to and moving along the working surface and incorporating tool-supply system, control and power-supply blocks (Volkov, 1982).The principal scheme of the mobile module is illustrated in Fig. 1. The power is supplied from the power-supply block 1 to the control block 2 which is connected to the drives 3.
1. INTRODUCTION
Research and development of mobile robots designed for travelling along voluntary oriented surfaces are now gaining in importance because of necessity to provide the work at large heights and at the places which are hardly to be reached by the operator. The automatic units of this type are applied to various industries, include civil works where they are served for finishing and cleaning the smooths surfaces of the high buildings. These researchers are well-performed formed in Japan, in the United States (Nakano, 1983) in France and Great Britain (Burrows, 1991). The main direction of the researchers are devoted to the problems of improvement the reliability when attaching the robot to the working surface, and to selection of such design of the units which would be of small dimensions and weight and would, there-with, accommodate multi-functional operation, thus providing the universal application. There is also more essential problem-development of simple but reliable robots travel system which permits the operation in conditions.
Toll-supply system includes the pump 4, the filter 5, the reservoir for cleaning solvent 6 and throttle 7. The power-supply block 1, the control block 2 together with tool-supply system are located on the module by means of cabling and piping. During the works the coach is to be installed near the working surface. The surface is processed as following. The operator installs the mobile module on the working surface and turns on technology and control system. The working chambers of elastic working components-suction caps 8 - start to generate vacuum and due to the atmospheric pressure the module is retained to voluntary oriented surface. The vacuum also initiates the cleaning solvent circulation. Translation of the unit is provided by wheels 9 driven by the driven 3. Friction clutch 10 is designed to fix the wheels 9 respectively to to the suction caps 8 during straight-line motion and to turn the wheels when changing the direction. The wheels rotate with opposite angular speed (in respect to the suction caps 8).
2. DEVELOPMENT AND INVESTIGATION ON THE ROBOT TRAVEL PRINCIPLES 2.1. Continuous Wheel-Tvpe Principle of the robot Travel Continuous robot travel principle is realized in actual robot designed representing small-size
528
8
3 9
o 3 8 4
? 5_.1.::::Ic-T::=
I
2
6
Fig. I . The principal scheme of the robot mobile module with continuous wheel-type travel
I
9
8
2
?
6
3 4
Fig. 3. The principal scl!eme of the robot mobile module with elearotncchanical step-by-step travel
Fig. 2. The principal scheme of the robot mobile module with vacuum step-by-step travel
529
Foto to Fig. I: the robot with continuous wheel-type rinciple travel
,. Foto to Fig. 2: the robot with vacuum step-by-step principle travel
Foto to Fig. 3: the robot with elcc:tromeclwtical step-by-step principle travel
530
The operator track of the mobile module represents rectangular-shape sweep. Tests on the sample robot (mobile module of 250x220x65 mm overall dimensions and of 2.5 kg weight) indicated that its speed when moving vertically along the straight line is as much as 0.1 mls and the productivity is 1.5 mlmin. The surface is being cleaned due to cleaning solvent effects and mechanical treatment when moving the unit. The automatic operation is accommodated by the control block. The module is stabilized respective by to the up-right plane is means of pendulum-type correction block.
connect the clutch 7 runner to the stock. The clutch 7 provides cylinder housing fixation respectively to the cap 2 when move the unit along the straight line and to release the said components and to connect the runner to the cylinder housing when changing the robot direction. The special feature of this design is application of the only one vacuum linear motor for both straight-line movement and rotation of the robot. The robot operation is similar to the previously discussed electromechanical robot. The robot is installed on the working surface by the operator, the control system 4 turns on and initiates the vacuum pump 5 and vacuum-distribution block 3. Vacuum is generated under the caps 1 and 2 and robot is retained to the surfaces due to the force of atmospheric pressure, while the cleaning solvent 6 starts the circulation along the working surface. This movement is provided so that one of the suction caps is immobile and the other moves in respect to it with the step value equal to that of the stock stroke. Then the cap which was immobile begins the rectilinear motion and the other one is fixed at the surface at the end point of the stock stroke. In order to realize such motion the vacuum distribution block 3 performs 3 levels of the pressure: Po- atmospheric pressure level, PIaverage vacuum pressure, P2 - high vacuum pressure, e.g. Po > PI > P2'
Dynamic model of the mobile module is determined when solving 2d order Lagrange equation in combination with dynamic equation of electric drive. The analysis of wheel-type electromechanical robot test results showed that such design has its own advantages: high maneU\'erability, smooth travelling (which is especially important for welding), well-performed mathematical module describing and simulating the operating the operation of the unit. Along with the advantages the disadvantages are always presented. Among them there should be mentioned low driving forces , significant slipping affections when increase the speed, caused by ingress of the moisture which has no time to volatility, high weight.
Operator drives the robot applying these pressures one after another to the appropriate cap planes this providing the robot traveling.The clutch 7 is engaged to rotate the robot around the axis 2 also by means of vacuum. Rotation of the robot is realized by linear vacuum motor 9.
In order to eliminate these disadvantages the sample robot with vacuum step-type drive was developed and tested. 2.2. Step-bv-Step Principle of Robot Traveling
The robot steady motion is given by the equations of mechanic and gasostatic. Resulted from the researching is the sample vacuum (step-type) robot of the overall dimensions 60xlOOx500 mm, 1,6 kg weight and 40 kg (maximum) effective load Average speed is 0,1 mls, productivity 0,6 m2 Imin.
The following requirements were placed for the unit design when develop this principle: - vacuum shall be used to retain the module to the surface and to provide cleaning solvent circulation, vacuum shall be served also as working medium for driving the robot instead of electric motor, thus all the disadvantages of the latter are eliminated.
The major advantage of this robot in comparison with that of wheel-type is more simple design and stability higher driving forces.
There is developed mobile model of the robot, its schematic diagram is shown in Fig. 2. The design incorporates the two vacuum suction caps I and 2 interconnected by means of the piping passed through the vacuum-distribution block 3 governed by the control system 4, vacuum pump 5 and cleaning solvent reservoir 6. The vacuum drive serves to move the suction caps along the surface. The drive is made as linear vacuum motor 9 of the stock connected to the cap I and the cylinder housing is connected to the cap via the clutch 7. Flexible link, such as rope 8, is employed to
The main disadvantage of this robot is the necessity to increase the pump productivity and vacuum pressures, since vacuum is served as the working medium to retain and to drive the robot. This robot also does not permit simple remote control. These disadvantages can be eliminated if employ the combined design keeping, there with all the advantages.
531
2.3.
moves forwarcl-back-ward translation of the unit.
Step-by-Step Electromechanical Robot Travel Principle
This design was developed when considering the long-term clI.-perience gained in previous YCSearching. The target was to develop an independent mobile module i.e. without flexible links (cables or hoses) with the control block and tooling-supply block located on the ground. To meet this requirement there was decided to employ remote infrared control system. Illustrated in Fig. 3 is principle scheme of this module. The robot consists of mobile module installed on voluntary oriented surfaces and accommodated with on-board control system land manual control device 2. The control device 2 is communicated \\;th the control system 11 by means of infrared rays. The mobile module consistent of the two , 'acuum camps 3 and 4 through which the vacuum pump 5 supplies the cleaning solvent 6 from reservoir 7. The essential feature of this robot is that vacuum pump 5, reservoir 7 \\;th cleaning solvent 6, control system I and power source 8 are located directly on-board the mobile module. This permit to eliminate the disadvantages of the pre-.;ous design . The robot represents independent system so it is more maneuverable and reliable that other ones. It also cancels the restrictions for cleaning soh'ent supply (up to 10 m) due to the application of vacuum. The piping overall losses are minimized because the pump is located directly close to the caps. This also in advantagewhen the pump is located directly close to the caps. This also in advantage when the vacuum pressure is limited with I atm . The unit operates as following the mobile module is to be installed on the working surface, then the vacuum pump 5 is twined on by means of device 2. Vacuum generated in suction caps 3 and 4 and the module is pressed to the working surface. Straight-line motion is realized by steps and in directed by electric drive 9. The direction of the motion can be changed due to relation around the axis of cap 4 governed by electric drive. Step-by-step motion of the robot is realized with the help the vacuum distribution among the caps 3 and 4 provided by the block 11 . In so doing the caps are subjected to vacuum in one-after-another order. The two vacuum pressures PI and Pl are applied . As the effective square of the suction caps is the same, there is fixed that cap under which the pressure p is high, at same time the other one moves along the surface \\;thout leaving it. The vacuum pressure under the caps changes synchronously with electric drive 9 as soon ass change the gear connected to the 1 atm which
thus providing the
The mathematic equations describing this robot are similar to those of the previously discussed steptype vacuum robot. So the motion and operation conditions are also the same. The full-scale model of this robot is of 80xlOOxSOO mm. the weight without tooling is 3 kg, the effective load is up to 20 kg and the average speed of linear motion is 0, I mls. This robot is,in fact, the combination of the two previously discussed units. So it combines the advantages and disadvantages of them both. But the new features the robot has got are high maneuverability, reduced vacuum losses, wider technical abilities. This gives us the hope that this robot would be very practicable in various industries.
3. ANALYSIS OF THE MEANS OF THE ROBOT RETAIN TO THE WORKING SURFACE WITH THE HELP OF VACUUM
Operation abilities of the robot and its safety are determined to a great ell.1ent by reliability of the mechanisms of the unit retaining to the working surface. Vacuum employment for this purpose represents the most universal and simple method in comparison with, for instance, permanent magnets. Vacuum application for the robots permitted to solve the two problems simultaneously: provision for robot attachment to and motion along the working surface and cleaning solvent circulation in the suction cups. There are proposed three different cap designs for robot retaining on the surface. The main requirement was reliability of attachment to the smooth surface and to the damaged one (cracks, defects). The unevenness of this type may cause uptightness of the vacuum caps and so the robot malfunctions. There with the was considered that the defects are much more smaller than the caps. The first version of the cap was the most simple. The robot motion along the damaged surface was provided due to high vacuum productivity which considerably exceeded and compensated air leakage. The cap design is simple in this case but demands high-effective vacuum pump. This cause the pump power increase and increase of its weight and dimensions which deteriorates the robot performances.
532
I 6
5
4
6 2 -'-+G--3 · Fig.4
FigS
Another decision was to employ telecamera as the primary de"ice for the the surface measurements and control. Along with the camera there was proposed to use the special computer to process the provided along the damage envelope, and in the case of step motion the cap is fixed before or after the defect.
Fig. 6.
data received from telecamera. The main idea of this method is that computer commands for the vacuum caps prevent their stops at the defects through which the air leakages. The motion is covers the section from the side of the working surface. If the section is on the smooth surface 4 vacuum is initiated through the holes 2 within the area 1 and through vacuum-piping 5. In the process the elastic plate 1 is stressed and does not deflect.
In this version weight and mass characteristics are better, but the robot capabilities are limited. The limitation is that in the case of going through crack or defect the unit will stop and this will cause special control by the operator.
In the case when the section covers the crack 6, the considerable pressure drop is created at the hole 2 which is of the small diameter. Under these conditions the elastic plate 1 deflects being thus scud against the walls of the section and overlapping the hole 2 and vacuum-piping 5. As takes place the section is automatically separated from the other sections which are on smooth surface and in which vacuum pressure is not changed. Due to these measure the unit is still attached to the surface.
The third version is the suction cap designed so that it can retain to the damaged surfaces. To realize the version another three design versions were proposed : multi-section suction cap with independent supply of each section with compressed air from its own ejector (see Fig. 4); multi-sectional suction cap with the outlet valves and supply from the only one vacuum pump (see Fig. 5); suction cap with self-adjusting vacuum pressure due to Bemulli gaseous dynamic effect (see Fig. 6).
The vacuum cap with automatic control on vacuum pressure (see Fig. 6) is operated in ordinary way on the smooth surface. But if the surface I is cracked (crack 2) the accelerated air flow passes through the clearance between disk 3 made as Venturi profile and the surface I. The flow acceleration is achieved because of minimizing the surface.The flow acceleration causes, as per Bemullie equation, pressure decrease on the surface of disk 3 and of the surface I and thus results in their mutual attraction under the attraction disk 3 moves along the guidelines 4 draw the jacket of the cap 6 \\;th it through elastic bellow 5. That is why the jacket 6 is sung against the surface land retains the unit. The
Design of the multi sectional suction cap (see Fig. 4) with independent vacuum supply of each section I from its own ejector 2 provided with compressed air permits, for example, to attach to the crack 3 on the surface 4. In so doing, however the section on the crack is unlighted, the other sections operate as usual because they are kept tight. The design shown in Fig. 5 permits to simplify the unit due to employment of hermetic outlet valves. The valve represents elastic plate I with holes 2 it
533
Abstract. The paper deals with mobile robots to be employed for processing IItlOOIh voluntary oriented surfaces include those of vertical and ceiling type. The robots retain to the worlc.ing surfaces and move along them due to the use of vacuum. In this paper continuous and step-by-step principles of the robot movement are discussed. Various aspects of vacuum application to retain the robots to the smooth and also to damaged surfaces are analyzed. Robot orientation systems incorporating pendulum pick-up of electromechanic .a nd vacuum type are examined, as well as the robot control systems of cable and remote (infrared) type. K~y
Words. Mobile robot; vacuum; continuous and step-by-step movement; pendulum pick-Up; control systems
mobile module retaining to and moving along the working surface and incorporating tool-supply system, control and power-supply blocks (Volkov, 1982).The principal scheme of the mobile module is illustrated in Fig. 1. The power is supplied from the power-supply block 1 to the control block 2 which is connected to the drives 3.
1. INTRODUCTION
Research and development of mobile robots designed for travelling along voluntary oriented surfaces are now gaining in importance because of necessity to provide the work at large heights and at the places which are hardly to be reached by the operator. The automatic units of this type are applied to various industries, include civil works where they are served for finishing and cleaning the smooths surfaces of the high buildings. These researchers are well-performed formed in Japan, in the United States (Nakano, 1983) in France and Great Britain (Burrows, 1991). The main direction of the researchers are devoted to the problems of improvement the reliability when attaching the robot to the working surface, and to selection of such design of the units which would be of small dimensions and weight and would, there-with, accommodate multi-functional operation, thus providing the universal application. There is also more essential problem-development of simple but reliable robots travel system which permits the operation in conditions.
Toll-supply system includes the pump 4, the filter 5, the reservoir for cleaning solvent 6 and throttle 7. The power-supply block 1, the control block 2 together with tool-supply system are located on the module by means of cabling and piping. During the works the coach is to be installed near the working surface. The surface is processed as following. The operator installs the mobile module on the working surface and turns on technology and control system. The working chambers of elastic working components-suction caps 8 - start to generate vacuum and due to the atmospheric pressure the module is retained to voluntary oriented surface. The vacuum also initiates the cleaning solvent circulation. Translation of the unit is provided by wheels 9 driven by the driven 3. Friction clutch 10 is designed to fix the wheels 9 respectively to to the suction caps 8 during straight-line motion and to turn the wheels when changing the direction. The wheels rotate with opposite angular speed (in respect to the suction caps 8).
2. DEVELOPMENT AND INVESTIGATION ON THE ROBOT TRAVEL PRINCIPLES 2.1. Continuous Wheel-Tvpe Principle of the robot Travel Continuous robot travel principle is realized in actual robot designed representing small-size
528
8
3 9
o 3 8 4
? 5_.1.::::Ic-T::=
I
2
6
Fig. I . The principal scheme of the robot mobile module with continuous wheel-type travel
I
9
8
2
?
6
3 4
Fig. 3. The principal scl!eme of the robot mobile module with elearotncchanical step-by-step travel
Fig. 2. The principal scheme of the robot mobile module with vacuum step-by-step travel
529
Foto to Fig. I: the robot with continuous wheel-type rinciple travel
,. Foto to Fig. 2: the robot with vacuum step-by-step principle travel
Foto to Fig. 3: the robot with elcc:tromeclwtical step-by-step principle travel
530
The operator track of the mobile module represents rectangular-shape sweep. Tests on the sample robot (mobile module of 250x220x65 mm overall dimensions and of 2.5 kg weight) indicated that its speed when moving vertically along the straight line is as much as 0.1 mls and the productivity is 1.5 mlmin. The surface is being cleaned due to cleaning solvent effects and mechanical treatment when moving the unit. The automatic operation is accommodated by the control block. The module is stabilized respective by to the up-right plane is means of pendulum-type correction block.
connect the clutch 7 runner to the stock. The clutch 7 provides cylinder housing fixation respectively to the cap 2 when move the unit along the straight line and to release the said components and to connect the runner to the cylinder housing when changing the robot direction. The special feature of this design is application of the only one vacuum linear motor for both straight-line movement and rotation of the robot. The robot operation is similar to the previously discussed electromechanical robot. The robot is installed on the working surface by the operator, the control system 4 turns on and initiates the vacuum pump 5 and vacuum-distribution block 3. Vacuum is generated under the caps 1 and 2 and robot is retained to the surfaces due to the force of atmospheric pressure, while the cleaning solvent 6 starts the circulation along the working surface. This movement is provided so that one of the suction caps is immobile and the other moves in respect to it with the step value equal to that of the stock stroke. Then the cap which was immobile begins the rectilinear motion and the other one is fixed at the surface at the end point of the stock stroke. In order to realize such motion the vacuum distribution block 3 performs 3 levels of the pressure: Po- atmospheric pressure level, PIaverage vacuum pressure, P2 - high vacuum pressure, e.g. Po > PI > P2'
Dynamic model of the mobile module is determined when solving 2d order Lagrange equation in combination with dynamic equation of electric drive. The analysis of wheel-type electromechanical robot test results showed that such design has its own advantages: high maneU\'erability, smooth travelling (which is especially important for welding), well-performed mathematical module describing and simulating the operating the operation of the unit. Along with the advantages the disadvantages are always presented. Among them there should be mentioned low driving forces , significant slipping affections when increase the speed, caused by ingress of the moisture which has no time to volatility, high weight.
Operator drives the robot applying these pressures one after another to the appropriate cap planes this providing the robot traveling.The clutch 7 is engaged to rotate the robot around the axis 2 also by means of vacuum. Rotation of the robot is realized by linear vacuum motor 9.
In order to eliminate these disadvantages the sample robot with vacuum step-type drive was developed and tested. 2.2. Step-bv-Step Principle of Robot Traveling
The robot steady motion is given by the equations of mechanic and gasostatic. Resulted from the researching is the sample vacuum (step-type) robot of the overall dimensions 60xlOOx500 mm, 1,6 kg weight and 40 kg (maximum) effective load Average speed is 0,1 mls, productivity 0,6 m2 Imin.
The following requirements were placed for the unit design when develop this principle: - vacuum shall be used to retain the module to the surface and to provide cleaning solvent circulation, vacuum shall be served also as working medium for driving the robot instead of electric motor, thus all the disadvantages of the latter are eliminated.
The major advantage of this robot in comparison with that of wheel-type is more simple design and stability higher driving forces.
There is developed mobile model of the robot, its schematic diagram is shown in Fig. 2. The design incorporates the two vacuum suction caps I and 2 interconnected by means of the piping passed through the vacuum-distribution block 3 governed by the control system 4, vacuum pump 5 and cleaning solvent reservoir 6. The vacuum drive serves to move the suction caps along the surface. The drive is made as linear vacuum motor 9 of the stock connected to the cap I and the cylinder housing is connected to the cap via the clutch 7. Flexible link, such as rope 8, is employed to
The main disadvantage of this robot is the necessity to increase the pump productivity and vacuum pressures, since vacuum is served as the working medium to retain and to drive the robot. This robot also does not permit simple remote control. These disadvantages can be eliminated if employ the combined design keeping, there with all the advantages.
531
2.3.
moves forwarcl-back-ward translation of the unit.
Step-by-Step Electromechanical Robot Travel Principle
This design was developed when considering the long-term clI.-perience gained in previous YCSearching. The target was to develop an independent mobile module i.e. without flexible links (cables or hoses) with the control block and tooling-supply block located on the ground. To meet this requirement there was decided to employ remote infrared control system. Illustrated in Fig. 3 is principle scheme of this module. The robot consists of mobile module installed on voluntary oriented surfaces and accommodated with on-board control system land manual control device 2. The control device 2 is communicated \\;th the control system 11 by means of infrared rays. The mobile module consistent of the two , 'acuum camps 3 and 4 through which the vacuum pump 5 supplies the cleaning solvent 6 from reservoir 7. The essential feature of this robot is that vacuum pump 5, reservoir 7 \\;th cleaning solvent 6, control system I and power source 8 are located directly on-board the mobile module. This permit to eliminate the disadvantages of the pre-.;ous design . The robot represents independent system so it is more maneuverable and reliable that other ones. It also cancels the restrictions for cleaning soh'ent supply (up to 10 m) due to the application of vacuum. The piping overall losses are minimized because the pump is located directly close to the caps. This also in advantagewhen the pump is located directly close to the caps. This also in advantage when the vacuum pressure is limited with I atm . The unit operates as following the mobile module is to be installed on the working surface, then the vacuum pump 5 is twined on by means of device 2. Vacuum generated in suction caps 3 and 4 and the module is pressed to the working surface. Straight-line motion is realized by steps and in directed by electric drive 9. The direction of the motion can be changed due to relation around the axis of cap 4 governed by electric drive. Step-by-step motion of the robot is realized with the help the vacuum distribution among the caps 3 and 4 provided by the block 11 . In so doing the caps are subjected to vacuum in one-after-another order. The two vacuum pressures PI and Pl are applied . As the effective square of the suction caps is the same, there is fixed that cap under which the pressure p is high, at same time the other one moves along the surface \\;thout leaving it. The vacuum pressure under the caps changes synchronously with electric drive 9 as soon ass change the gear connected to the 1 atm which
thus providing the
The mathematic equations describing this robot are similar to those of the previously discussed steptype vacuum robot. So the motion and operation conditions are also the same. The full-scale model of this robot is of 80xlOOxSOO mm. the weight without tooling is 3 kg, the effective load is up to 20 kg and the average speed of linear motion is 0, I mls. This robot is,in fact, the combination of the two previously discussed units. So it combines the advantages and disadvantages of them both. But the new features the robot has got are high maneuverability, reduced vacuum losses, wider technical abilities. This gives us the hope that this robot would be very practicable in various industries.
3. ANALYSIS OF THE MEANS OF THE ROBOT RETAIN TO THE WORKING SURFACE WITH THE HELP OF VACUUM
Operation abilities of the robot and its safety are determined to a great ell.1ent by reliability of the mechanisms of the unit retaining to the working surface. Vacuum employment for this purpose represents the most universal and simple method in comparison with, for instance, permanent magnets. Vacuum application for the robots permitted to solve the two problems simultaneously: provision for robot attachment to and motion along the working surface and cleaning solvent circulation in the suction cups. There are proposed three different cap designs for robot retaining on the surface. The main requirement was reliability of attachment to the smooth surface and to the damaged one (cracks, defects). The unevenness of this type may cause uptightness of the vacuum caps and so the robot malfunctions. There with the was considered that the defects are much more smaller than the caps. The first version of the cap was the most simple. The robot motion along the damaged surface was provided due to high vacuum productivity which considerably exceeded and compensated air leakage. The cap design is simple in this case but demands high-effective vacuum pump. This cause the pump power increase and increase of its weight and dimensions which deteriorates the robot performances.
532
I 6
5
4
6 2 -'-+G--3 · Fig.4
FigS
Another decision was to employ telecamera as the primary de"ice for the the surface measurements and control. Along with the camera there was proposed to use the special computer to process the provided along the damage envelope, and in the case of step motion the cap is fixed before or after the defect.
Fig. 6.
data received from telecamera. The main idea of this method is that computer commands for the vacuum caps prevent their stops at the defects through which the air leakages. The motion is covers the section from the side of the working surface. If the section is on the smooth surface 4 vacuum is initiated through the holes 2 within the area 1 and through vacuum-piping 5. In the process the elastic plate 1 is stressed and does not deflect.
In this version weight and mass characteristics are better, but the robot capabilities are limited. The limitation is that in the case of going through crack or defect the unit will stop and this will cause special control by the operator.
In the case when the section covers the crack 6, the considerable pressure drop is created at the hole 2 which is of the small diameter. Under these conditions the elastic plate 1 deflects being thus scud against the walls of the section and overlapping the hole 2 and vacuum-piping 5. As takes place the section is automatically separated from the other sections which are on smooth surface and in which vacuum pressure is not changed. Due to these measure the unit is still attached to the surface.
The third version is the suction cap designed so that it can retain to the damaged surfaces. To realize the version another three design versions were proposed : multi-section suction cap with independent supply of each section with compressed air from its own ejector (see Fig. 4); multi-sectional suction cap with the outlet valves and supply from the only one vacuum pump (see Fig. 5); suction cap with self-adjusting vacuum pressure due to Bemulli gaseous dynamic effect (see Fig. 6).
The vacuum cap with automatic control on vacuum pressure (see Fig. 6) is operated in ordinary way on the smooth surface. But if the surface I is cracked (crack 2) the accelerated air flow passes through the clearance between disk 3 made as Venturi profile and the surface I. The flow acceleration is achieved because of minimizing the surface.The flow acceleration causes, as per Bemullie equation, pressure decrease on the surface of disk 3 and of the surface I and thus results in their mutual attraction under the attraction disk 3 moves along the guidelines 4 draw the jacket of the cap 6 \\;th it through elastic bellow 5. That is why the jacket 6 is sung against the surface land retains the unit. The
Design of the multi sectional suction cap (see Fig. 4) with independent vacuum supply of each section I from its own ejector 2 provided with compressed air permits, for example, to attach to the crack 3 on the surface 4. In so doing, however the section on the crack is unlighted, the other sections operate as usual because they are kept tight. The design shown in Fig. 5 permits to simplify the unit due to employment of hermetic outlet valves. The valve represents elastic plate I with holes 2 it
533