- Email: [email protected]
Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees
Materials Today: Proceedings xxx (xxxx) xxx
Contents lists available at ScienceDirect
Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr
Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees Palaiam Siddikali, PS Rama Sreekanth ⇑ School of Mechanical Engineering, VIT AP University, Amaravati, A.P. 522237, India
a r t i c l e
i n f o
Article history: Received 19 November 2019 Received in revised form 25 December 2019 Accepted 29 December 2019 Available online xxxx Keywords: Transfemoral amputee Disability Prosthetic Pneumatic Spring loaded Flexion-extension
a b s t r a c t Lower limb amputation causes many changes and associated adjustments, which not only relates the damaged limb but also to the entire body. Today, the development of prosthetic devices for transfemoral amputation witness continual growth in medical applications. In India, an estimated 2.68 crore people have movement disability according to disability census 2011. At present 230,000 transfemoral amputees are in need of prosthetic devices to be facilitated for the better living style and standards, but low cost devices are yet to touch the market. And also, the amputee must endure to function in society uncomplaining that his disability may utterly inhibit or even prohibit the performance of various activities to which he has long been habituated. When compared to other disabilities, above knee amputation deprive a human to perform his activities and earn livelihood becomes an arduous task. Regardless of the developments in technology, above-knee amputees still indicates significant deficiencies in walking patterns, speed in walking. In this paper, a novel modelling of a pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee system for early and late swing and stance control has been presented. This work establishes a functional knee model developed by Catia software for various activities. The proposed model contemplates user needs and provides a low cost alternative with high stability and more durability to enable flexion-extension of prosthetic leg during the gait cycle. Ó 2020 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the First International conference on Advanced Lightweight Materials and Structures.
1. Introduction Many of the people, lose their mobility because of amputation of lower-limb caused due to several reasons like trauma, diabetics, accidents, unintentional injury, and natural disasters and face many challenges physically which compromise their health condition [1]. In the global scenario, according to WHO disability and health [2018], above a billion people, nearly 15 percentage of the world’s people, have some sort of disability. Amongst, 110 million adults have substantial difficulties in functioning and 80 percent of the total disability lives in developing countries. It is expected that the people living with limb loss would be more than double by 2050. The over-all individuals number with an amputation is estimated to rise by at least 47 percent before 2020 [2]. Therefore, installation of the artificial prosthesis is an effectual means to regain gait. Prosthetic knee joints available in
⇑ Corresponding author. E-mail address: [email protected] (PS Rama Sreekanth).
the market, depending on its functionality and price are categorized into three grades. The knee joint system known as an intelligent limb prosthetic is a high-grade device, which adjusts the knee automatically by controlling its moment, in comparison with the knee joint angle and speed of walking of the unaffected limb and makes the gait movement nearer to the healthy population. In the mid-grade knee joint system the speed of swing movement and knee angle can be adjusted by mechanical means. The constituted simple connecting rod structure is a low-grade system, which can only be used as a support during walking [1,3]. Based on the statistical data, there are over two million people every year seek prosthetic surgery to be performed after amputation. The prosthetic knee joint of high and mid-grade system with low cost and high reliability is preferable and have high demand in emerging countries. Several conventional prosthesis for transfemoral or above knee (AK) amputees are grounded on passive mechanisms for functioning since, they can deliver a stable movement without the use of any expensive actuators and sensors [4]. Even though there exist many knee joints commercially available from several suppliers, the price is quiet
https://doi.org/10.1016/j.matpr.2019.12.377 2214-7853/Ó 2020 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the First International conference on Advanced Lightweight Materials and Structures.
Please cite this article as: P. Siddikali and P. Rama Sreekanth, Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.377
2
P. Siddikali, PS Rama Sreekanth / Materials Today: Proceedings xxx (xxxx) xxx
high with low cost to performance ratio [5]. The objective of this paper, is to design a novel pneumatic controlled biomimetic articulated passive prosthetic spring loaded knee system which is cost effective, by adopting suitable materials [6] and fully passive and will be suitable for transfemoral amputees. 2. Dynamics of human walking For dynamic control model formulation, the human knee joint movement phases such a stance phase with approximately, 60% and swing phase with 40% of a gait cycle [7] can be observed in Fig. 1. Further, the description of the gait cycle can be classified into six events: heel contact event (HC), foot flat event (FF), midstance event (MST), heel-off event (HO), toe-off event (TO) and midswing event (MSW). The beginning of HC event is accomplished when the foot makes contact with the ground, bending of hip joint and stretching of knee joint occurs which causes thigh to absorb the impact. During FF event slow movement of thigh takes place with knee flexion angle of 15–20°. The thigh moves from 10° of flexion to extension in MST event, there after the knee reaches to its maximum flexion and extension of knee takes place, at this stage one single leg supports the entire body weight, which causes the body to move from force absorption state to force propulsion state. In the HO event, the heel leaves the ground and in the TO event, the extension of thigh becomes less when toes leave the ground. In MSW event, the knee flexes up to 55° and extend to 30° [8–10]. 2.1. Pneumatic knee spring loaded system 2.1.1. Characteristics and indications In the past decades, efforts have been made to provide an automatic lock and brake system to the proshtetic knee, which can provide stability with minimal stumbling during stance phase [11]. The stability of the leg can be obtained by proper alignment of the knee axis behind the hip and ankle axes [12]. Pneumatic knee system is used in conjunction with the knee unit. The forced air in the pneumatic system provides resistance to knee motion by adjusting the screws, through a port or opening in the control unit to attain compatibility with the amputee’s gait. Pneumatic system has the advantage of being cadence responsive, and are considered more efficient than other basic knee units. Usually, a pneumatic passive knee increases mobility for decreased stability which in turn plays a role in helping the amputee to find a suitable balance for muscular coordination. Since the refinement of the lives of people with above-knee disability is a constant focus.
In general, a rigid lower-limb prosthesis model comprises of socket, knee system, pylon, and a foot. 2.1.2. Conventional knee joint prosthetic design The existing prosthetic knee joint designs with the passive pneumatic controlled spring loaded knee joint with their advantages and limitations [13] can be observed in Table 1. Manual locking knee system design provides a manual locking of prosthetic knee in the stance position during a walk and can be unlocked by just cable pulling while sitting posture which provides less strength and it is not useful for kneeling posture, because its maximum angle of flexion is 140°. A friction brake weight-activation stance control knee system, prevents from buckling and bending when the amputated person put body load on the prosthesis, but lack of locking system for flexion extension with an angle of 160°. Polycentric knee/four-bar knee system is most preferable, though has complex mechanism, provides flexion stability at variable speeds, but due to more moving parts its maintenance is unavoidable and has low strength which is inconvenient for people of all ages. Pneumatic/hydraulic prosthetic knee design are fitted with cylinders filled with air/fluid respectively, which provides fast movement and control of the knee flexion. The weight and bulkiness of. pneumatic/hydraulic prosthetic knee system makes it unaffordable by the people [14,15]. Microprocessor based knees comprises of microcontroller, which calculates the acting forces on knee joint, provides stability, speed and internal adjustments, which costs high also consumes electricity and stores in a backup unit, thus it is unfavourable for long time activities. In all the knee joint types, which have been discussed does not provide strength if cost is less and higher strength increases the cost, also its repair and maintenance cost is high, making it unaffordable by the people of all class. In order to address the above issues, a novel design with fully passive prosthetic knee has been proposed, which comprises of pneumatic piston-cylinder arrangement along with a unit at the bottom of the knee frame, that provides additional support with high stability to the pneumatic arrangement, thereby stance and swing movement of the leg with flexion angle from 0° to 160° can be easily accomplished and finds application for disabled people by birth, physically injured, and for the disabled elderly diabetic patients. 3. Modeling of pneumatic controlled biomimetic articulated passive prosthetic spring loaded system 3.1. Structural design of pneumatic controlled passive knee joint Fig. 2 Illustrates a complete assembled prosthetic knee model. In general, the model comprises of the commercial products such as suction socket [16], the pylon, and the silicone SACH foot. This paper focuses only on modeling of the passive prosthetic knee joint with advanced features for transfemoral amputees, which will cover the areas of the thigh, and the shank. There are two parts in the design, an upper part which comprises of knee frame, knee ball and pneumatic system and the lower part includes bottom barrel spring loaded unit. 3.2. Architecture of the mechanism
Fig. 1. Human gait cycle events & phases.
The novelty which has been adopted in this design makes it unique from the existing systems with adjustable features for flexion and extension of the knee joint. The proposed system provides incredible stance stability, ease in walking and to tolerate core conditions by identifying different flexion angles of knee joint and force vector with respect to ground reaction to provide default stance, active stance flexion and self-regulating swing control
Please cite this article as: P. Siddikali and P. Rama Sreekanth, Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.377
3
P. Siddikali, PS Rama Sreekanth / Materials Today: Proceedings xxx (xxxx) xxx Table 1 Various prosthetic knee designs for transfemoral amputees. Knee Type
Schematic
Features Tuning for sitting
Locking system
Flexion Angle (Degrees)
Manual Locking Knee
Y
Y
0–140
Stance Control Knee
Y
N
0–150
Polycentric Knee
N
N
0–160
Pneumatic/Hydraulic Knee
N
N
0–160
Micro Processor Knee
N
N
0–130
Pneumatic Controlled Spring loaded Passive prosthetic Knee (proposed model)
Y
Y
0–160
during gait. Fig. 3 shows the various components of the system and Fig. 4 depicts the design flow of modelling process. 3.2.1. Pneumatic system While an amputee is walking, the stump recovery should be defined for the smooth kinematics, otherwise the amputee feels
falling forward or backward because of the limiting angle of the knee. So, here a pneumatic controlled bio mimetic articulated spring loaded system is attached between the knee frame and knee ball to avoid early stump recovery by adjusting the screws provided in the pneumatic system for easy flexion extension. The pneumatic system is fixed to the bottom of the knee frame with
Please cite this article as: P. Siddikali and P. Rama Sreekanth, Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.377
4
P. Siddikali, PS Rama Sreekanth / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 2. Detailed drafting of knee joint in multiple views.
a stud and bearing support, with side holding screws to provide proper swing during forward and backward moment, thereby the extended tip at the bottom of the system touches the spring loaded tough cap of bottom barrel mechanism to ease the movement in gait. 3.2.2. Bottom barrel mechanism The bottom barrel mechanism contains an outer barrel, an inner barrel, a spiral spring with tough cap. During gait cycle the spiral spring is compressed by the force of pneumatic tip, thus causes knee flexion when the leg is above the ground. While in stance phase, whenever the leg touches the ground, the energy stored in the compressed spring is released by pushing the pneumatic tip to its initial position. The entire bottom barrel mechanism with loaded spring chamber can be detachable and the pylon can be fixed firmly with the help of screw provided, such that extension and shortening of the pylon for the required height of the amputee
leg is possible. Thus providing a high stability and minimizing the metabolic energy expenditure of the user. 3.3. Flexion angles of pneumatic controlled spring-loaded knee system The proposed model of the bio mimic articulated passive pneumatic controlled spring loaded knee system at different flexion angles can be seen in Fig. 5. which resembles the human knee joint movement. The prototype gives more degrees of freedom for smooth motion of knee whilst maintaining joint integrity. At the flexion angle of 0°, the pneumatic piston extends to make upright posture, such that stance position can be attained as shown in Fig. 5(a). When the knee ball bends at 90°, the piston get compressed and swing inside the knee frame thereby the spiral spring with tough cap in the bottom barrel mechanism also gets compressed and stores the energy, this accomplishes the activity like chair sitting and stair climbing by proper adjustment of screws
Please cite this article as: P. Siddikali and P. Rama Sreekanth, Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.377
P. Siddikali, PS Rama Sreekanth / Materials Today: Proceedings xxx (xxxx) xxx
5
Fig. 3. Components of pneumatic passive prosthetic knee.
provided in the pneumatic system as shown in the Fig. 5(b). Further when the knee ball bends at 160° as shown in the Fig. 5(c), the pneumatic piston reaches to its extreme which in turn compress the spring to its maximum in bottom barrel mechanism, thus the activities like kneeling and sitting on floor can also be achieved. During walk, both flexion and extension of the knee occurs thereby the energy which is stored in the different angles of flexion can be released by the spiral spring by regaining its initial position thereby pushing the pneumatic system backward and causes the piston to attain stance posture again, in this way the repetition of gait cycle takes place to restore ideal knee kinematics to properly amble the amputee at various postures, which in turn reduces the metabolic cost.
Modeling of Knee Frame
Fixing Knee Ball on top of Knee frame
Assigning the Pneumatic actuator
Tightening up the knee ball and actuator with threaded screws for proper alignment of threaded stud barrel
4. Conclusion In this paper, for the prosthetic applications, a bio mimic pneumatic controlled passive prosthetic knee joint design has been presented. The design resembles the desirable features of a human knee joint, with flexible movement of knee ball and interlocking knee system. In the upright posture of knee extension for standing, with slight adjustment for stair climbing or sitting and further adjustment for speed walk and kneeling can be achieved at differ-
Inserting bottom inner barrel into bottom outer barrel with spiral spring and spring cap
Attaching Bottom barrel mechanism below the knee frame Fig. 4. Design Flow of pneumatic passive prosthetic knee system.
Please cite this article as: P. Siddikali and P. Rama Sreekanth, Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.377
6
P. Siddikali, PS Rama Sreekanth / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 5. Various flexion angles of pneumatic passive knee with different views at (a) 0°; (b) 90°; (c) 160°.
ent flexion angles, thus making bio-inspired knee design most suitable for artificial legs. Conventional manufacturing process can be adopted to make compact and lightweight knee joint with suitable materials to reduce the cost and to provide high stability to carry out daily activities on uneven terrains for above knee (AK) amputees. CRediT authorship contribution statement Palaiam Siddikali: Conceptualization, Methodology, Software, Validation, Writing - original draft. PS Rama Sreekanth: Visualization, Investigation, Supervision, Writing - review & editing. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References [1] R.S. Gailey, K.E. Roach, E.B. Applegate, B. Cho, B. Cunniffe, S. Licht, M. Maguire, M.S. Nash, Arch. Phys. Med. Rehabil. 83 (2002) 613–627. [2] World Health Organization, World Health (2011) 1–24. [3] B.G.A. Lambrecht, H. Kazerooni, 3353425 (2008) 115. [4] H. Bikas, P. Stavropoulos, G. Chryssolouris, (2016) 389–405. [5] H. Fu, X. Zhang, X. Wang, R. Yang, J. Li, L. Wang, N. Zhang, G. Li, T. Liu, B. Fan, (2016) 1–9. [6] I. Journal, O.F. Engineering, A. Of, F. Component, O.F.A. Prosthetic, K. Joint, 6 (2017) 301–307. [7] H. Herr, A. Wilkenfeld, Ind. Rob. 30 (2003) 42–55. [8] B.Y.W. Berger, V. Dietz, J. Quintern (1984) 109–125. [9] C. Mummolo, L. Mangialardi, J.H. Kim, J. Biomech. Eng. 135 (2013) 1–10. [10] H.L. Yu, S.N. Zhao, Z.H. Xu, J. Brazilian Soc. Mech. Sci. Eng. 33 (2011) 366–372. [11] W. Paper, (n.d.) 1–35. [12] A. Kumar, P. Swami, S. Anand, U. Singh, Appl. Math. Model. 72 (2019) 356–368. [13] A.C. Etoundi, 8 (2013) 213–225. [14] I.O.P.C. Series, M. Science, (2018). [15] Z. Haoran, H. Chenghao, L. Xinyu, G. Liang, Z. Bing, D. Haozhen, 59 (2019) 361– 372. [16] M.S. Keszler, J.T. Heckman, (2019).
Please cite this article as: P. Siddikali and P. Rama Sreekanth, Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.377
Contents lists available at ScienceDirect
Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr
Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees Palaiam Siddikali, PS Rama Sreekanth ⇑ School of Mechanical Engineering, VIT AP University, Amaravati, A.P. 522237, India
a r t i c l e
i n f o
Article history: Received 19 November 2019 Received in revised form 25 December 2019 Accepted 29 December 2019 Available online xxxx Keywords: Transfemoral amputee Disability Prosthetic Pneumatic Spring loaded Flexion-extension
a b s t r a c t Lower limb amputation causes many changes and associated adjustments, which not only relates the damaged limb but also to the entire body. Today, the development of prosthetic devices for transfemoral amputation witness continual growth in medical applications. In India, an estimated 2.68 crore people have movement disability according to disability census 2011. At present 230,000 transfemoral amputees are in need of prosthetic devices to be facilitated for the better living style and standards, but low cost devices are yet to touch the market. And also, the amputee must endure to function in society uncomplaining that his disability may utterly inhibit or even prohibit the performance of various activities to which he has long been habituated. When compared to other disabilities, above knee amputation deprive a human to perform his activities and earn livelihood becomes an arduous task. Regardless of the developments in technology, above-knee amputees still indicates significant deficiencies in walking patterns, speed in walking. In this paper, a novel modelling of a pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee system for early and late swing and stance control has been presented. This work establishes a functional knee model developed by Catia software for various activities. The proposed model contemplates user needs and provides a low cost alternative with high stability and more durability to enable flexion-extension of prosthetic leg during the gait cycle. Ó 2020 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the First International conference on Advanced Lightweight Materials and Structures.
1. Introduction Many of the people, lose their mobility because of amputation of lower-limb caused due to several reasons like trauma, diabetics, accidents, unintentional injury, and natural disasters and face many challenges physically which compromise their health condition [1]. In the global scenario, according to WHO disability and health [2018], above a billion people, nearly 15 percentage of the world’s people, have some sort of disability. Amongst, 110 million adults have substantial difficulties in functioning and 80 percent of the total disability lives in developing countries. It is expected that the people living with limb loss would be more than double by 2050. The over-all individuals number with an amputation is estimated to rise by at least 47 percent before 2020 [2]. Therefore, installation of the artificial prosthesis is an effectual means to regain gait. Prosthetic knee joints available in
⇑ Corresponding author. E-mail address: [email protected] (PS Rama Sreekanth).
the market, depending on its functionality and price are categorized into three grades. The knee joint system known as an intelligent limb prosthetic is a high-grade device, which adjusts the knee automatically by controlling its moment, in comparison with the knee joint angle and speed of walking of the unaffected limb and makes the gait movement nearer to the healthy population. In the mid-grade knee joint system the speed of swing movement and knee angle can be adjusted by mechanical means. The constituted simple connecting rod structure is a low-grade system, which can only be used as a support during walking [1,3]. Based on the statistical data, there are over two million people every year seek prosthetic surgery to be performed after amputation. The prosthetic knee joint of high and mid-grade system with low cost and high reliability is preferable and have high demand in emerging countries. Several conventional prosthesis for transfemoral or above knee (AK) amputees are grounded on passive mechanisms for functioning since, they can deliver a stable movement without the use of any expensive actuators and sensors [4]. Even though there exist many knee joints commercially available from several suppliers, the price is quiet
https://doi.org/10.1016/j.matpr.2019.12.377 2214-7853/Ó 2020 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the First International conference on Advanced Lightweight Materials and Structures.
Please cite this article as: P. Siddikali and P. Rama Sreekanth, Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.377
2
P. Siddikali, PS Rama Sreekanth / Materials Today: Proceedings xxx (xxxx) xxx
high with low cost to performance ratio [5]. The objective of this paper, is to design a novel pneumatic controlled biomimetic articulated passive prosthetic spring loaded knee system which is cost effective, by adopting suitable materials [6] and fully passive and will be suitable for transfemoral amputees. 2. Dynamics of human walking For dynamic control model formulation, the human knee joint movement phases such a stance phase with approximately, 60% and swing phase with 40% of a gait cycle [7] can be observed in Fig. 1. Further, the description of the gait cycle can be classified into six events: heel contact event (HC), foot flat event (FF), midstance event (MST), heel-off event (HO), toe-off event (TO) and midswing event (MSW). The beginning of HC event is accomplished when the foot makes contact with the ground, bending of hip joint and stretching of knee joint occurs which causes thigh to absorb the impact. During FF event slow movement of thigh takes place with knee flexion angle of 15–20°. The thigh moves from 10° of flexion to extension in MST event, there after the knee reaches to its maximum flexion and extension of knee takes place, at this stage one single leg supports the entire body weight, which causes the body to move from force absorption state to force propulsion state. In the HO event, the heel leaves the ground and in the TO event, the extension of thigh becomes less when toes leave the ground. In MSW event, the knee flexes up to 55° and extend to 30° [8–10]. 2.1. Pneumatic knee spring loaded system 2.1.1. Characteristics and indications In the past decades, efforts have been made to provide an automatic lock and brake system to the proshtetic knee, which can provide stability with minimal stumbling during stance phase [11]. The stability of the leg can be obtained by proper alignment of the knee axis behind the hip and ankle axes [12]. Pneumatic knee system is used in conjunction with the knee unit. The forced air in the pneumatic system provides resistance to knee motion by adjusting the screws, through a port or opening in the control unit to attain compatibility with the amputee’s gait. Pneumatic system has the advantage of being cadence responsive, and are considered more efficient than other basic knee units. Usually, a pneumatic passive knee increases mobility for decreased stability which in turn plays a role in helping the amputee to find a suitable balance for muscular coordination. Since the refinement of the lives of people with above-knee disability is a constant focus.
In general, a rigid lower-limb prosthesis model comprises of socket, knee system, pylon, and a foot. 2.1.2. Conventional knee joint prosthetic design The existing prosthetic knee joint designs with the passive pneumatic controlled spring loaded knee joint with their advantages and limitations [13] can be observed in Table 1. Manual locking knee system design provides a manual locking of prosthetic knee in the stance position during a walk and can be unlocked by just cable pulling while sitting posture which provides less strength and it is not useful for kneeling posture, because its maximum angle of flexion is 140°. A friction brake weight-activation stance control knee system, prevents from buckling and bending when the amputated person put body load on the prosthesis, but lack of locking system for flexion extension with an angle of 160°. Polycentric knee/four-bar knee system is most preferable, though has complex mechanism, provides flexion stability at variable speeds, but due to more moving parts its maintenance is unavoidable and has low strength which is inconvenient for people of all ages. Pneumatic/hydraulic prosthetic knee design are fitted with cylinders filled with air/fluid respectively, which provides fast movement and control of the knee flexion. The weight and bulkiness of. pneumatic/hydraulic prosthetic knee system makes it unaffordable by the people [14,15]. Microprocessor based knees comprises of microcontroller, which calculates the acting forces on knee joint, provides stability, speed and internal adjustments, which costs high also consumes electricity and stores in a backup unit, thus it is unfavourable for long time activities. In all the knee joint types, which have been discussed does not provide strength if cost is less and higher strength increases the cost, also its repair and maintenance cost is high, making it unaffordable by the people of all class. In order to address the above issues, a novel design with fully passive prosthetic knee has been proposed, which comprises of pneumatic piston-cylinder arrangement along with a unit at the bottom of the knee frame, that provides additional support with high stability to the pneumatic arrangement, thereby stance and swing movement of the leg with flexion angle from 0° to 160° can be easily accomplished and finds application for disabled people by birth, physically injured, and for the disabled elderly diabetic patients. 3. Modeling of pneumatic controlled biomimetic articulated passive prosthetic spring loaded system 3.1. Structural design of pneumatic controlled passive knee joint Fig. 2 Illustrates a complete assembled prosthetic knee model. In general, the model comprises of the commercial products such as suction socket [16], the pylon, and the silicone SACH foot. This paper focuses only on modeling of the passive prosthetic knee joint with advanced features for transfemoral amputees, which will cover the areas of the thigh, and the shank. There are two parts in the design, an upper part which comprises of knee frame, knee ball and pneumatic system and the lower part includes bottom barrel spring loaded unit. 3.2. Architecture of the mechanism
Fig. 1. Human gait cycle events & phases.
The novelty which has been adopted in this design makes it unique from the existing systems with adjustable features for flexion and extension of the knee joint. The proposed system provides incredible stance stability, ease in walking and to tolerate core conditions by identifying different flexion angles of knee joint and force vector with respect to ground reaction to provide default stance, active stance flexion and self-regulating swing control
Please cite this article as: P. Siddikali and P. Rama Sreekanth, Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.377
3
P. Siddikali, PS Rama Sreekanth / Materials Today: Proceedings xxx (xxxx) xxx Table 1 Various prosthetic knee designs for transfemoral amputees. Knee Type
Schematic
Features Tuning for sitting
Locking system
Flexion Angle (Degrees)
Manual Locking Knee
Y
Y
0–140
Stance Control Knee
Y
N
0–150
Polycentric Knee
N
N
0–160
Pneumatic/Hydraulic Knee
N
N
0–160
Micro Processor Knee
N
N
0–130
Pneumatic Controlled Spring loaded Passive prosthetic Knee (proposed model)
Y
Y
0–160
during gait. Fig. 3 shows the various components of the system and Fig. 4 depicts the design flow of modelling process. 3.2.1. Pneumatic system While an amputee is walking, the stump recovery should be defined for the smooth kinematics, otherwise the amputee feels
falling forward or backward because of the limiting angle of the knee. So, here a pneumatic controlled bio mimetic articulated spring loaded system is attached between the knee frame and knee ball to avoid early stump recovery by adjusting the screws provided in the pneumatic system for easy flexion extension. The pneumatic system is fixed to the bottom of the knee frame with
Please cite this article as: P. Siddikali and P. Rama Sreekanth, Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.377
4
P. Siddikali, PS Rama Sreekanth / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 2. Detailed drafting of knee joint in multiple views.
a stud and bearing support, with side holding screws to provide proper swing during forward and backward moment, thereby the extended tip at the bottom of the system touches the spring loaded tough cap of bottom barrel mechanism to ease the movement in gait. 3.2.2. Bottom barrel mechanism The bottom barrel mechanism contains an outer barrel, an inner barrel, a spiral spring with tough cap. During gait cycle the spiral spring is compressed by the force of pneumatic tip, thus causes knee flexion when the leg is above the ground. While in stance phase, whenever the leg touches the ground, the energy stored in the compressed spring is released by pushing the pneumatic tip to its initial position. The entire bottom barrel mechanism with loaded spring chamber can be detachable and the pylon can be fixed firmly with the help of screw provided, such that extension and shortening of the pylon for the required height of the amputee
leg is possible. Thus providing a high stability and minimizing the metabolic energy expenditure of the user. 3.3. Flexion angles of pneumatic controlled spring-loaded knee system The proposed model of the bio mimic articulated passive pneumatic controlled spring loaded knee system at different flexion angles can be seen in Fig. 5. which resembles the human knee joint movement. The prototype gives more degrees of freedom for smooth motion of knee whilst maintaining joint integrity. At the flexion angle of 0°, the pneumatic piston extends to make upright posture, such that stance position can be attained as shown in Fig. 5(a). When the knee ball bends at 90°, the piston get compressed and swing inside the knee frame thereby the spiral spring with tough cap in the bottom barrel mechanism also gets compressed and stores the energy, this accomplishes the activity like chair sitting and stair climbing by proper adjustment of screws
Please cite this article as: P. Siddikali and P. Rama Sreekanth, Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.377
P. Siddikali, PS Rama Sreekanth / Materials Today: Proceedings xxx (xxxx) xxx
5
Fig. 3. Components of pneumatic passive prosthetic knee.
provided in the pneumatic system as shown in the Fig. 5(b). Further when the knee ball bends at 160° as shown in the Fig. 5(c), the pneumatic piston reaches to its extreme which in turn compress the spring to its maximum in bottom barrel mechanism, thus the activities like kneeling and sitting on floor can also be achieved. During walk, both flexion and extension of the knee occurs thereby the energy which is stored in the different angles of flexion can be released by the spiral spring by regaining its initial position thereby pushing the pneumatic system backward and causes the piston to attain stance posture again, in this way the repetition of gait cycle takes place to restore ideal knee kinematics to properly amble the amputee at various postures, which in turn reduces the metabolic cost.
Modeling of Knee Frame
Fixing Knee Ball on top of Knee frame
Assigning the Pneumatic actuator
Tightening up the knee ball and actuator with threaded screws for proper alignment of threaded stud barrel
4. Conclusion In this paper, for the prosthetic applications, a bio mimic pneumatic controlled passive prosthetic knee joint design has been presented. The design resembles the desirable features of a human knee joint, with flexible movement of knee ball and interlocking knee system. In the upright posture of knee extension for standing, with slight adjustment for stair climbing or sitting and further adjustment for speed walk and kneeling can be achieved at differ-
Inserting bottom inner barrel into bottom outer barrel with spiral spring and spring cap
Attaching Bottom barrel mechanism below the knee frame Fig. 4. Design Flow of pneumatic passive prosthetic knee system.
Please cite this article as: P. Siddikali and P. Rama Sreekanth, Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.377
6
P. Siddikali, PS Rama Sreekanth / Materials Today: Proceedings xxx (xxxx) xxx
Fig. 5. Various flexion angles of pneumatic passive knee with different views at (a) 0°; (b) 90°; (c) 160°.
ent flexion angles, thus making bio-inspired knee design most suitable for artificial legs. Conventional manufacturing process can be adopted to make compact and lightweight knee joint with suitable materials to reduce the cost and to provide high stability to carry out daily activities on uneven terrains for above knee (AK) amputees. CRediT authorship contribution statement Palaiam Siddikali: Conceptualization, Methodology, Software, Validation, Writing - original draft. PS Rama Sreekanth: Visualization, Investigation, Supervision, Writing - review & editing. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References [1] R.S. Gailey, K.E. Roach, E.B. Applegate, B. Cho, B. Cunniffe, S. Licht, M. Maguire, M.S. Nash, Arch. Phys. Med. Rehabil. 83 (2002) 613–627. [2] World Health Organization, World Health (2011) 1–24. [3] B.G.A. Lambrecht, H. Kazerooni, 3353425 (2008) 115. [4] H. Bikas, P. Stavropoulos, G. Chryssolouris, (2016) 389–405. [5] H. Fu, X. Zhang, X. Wang, R. Yang, J. Li, L. Wang, N. Zhang, G. Li, T. Liu, B. Fan, (2016) 1–9. [6] I. Journal, O.F. Engineering, A. Of, F. Component, O.F.A. Prosthetic, K. Joint, 6 (2017) 301–307. [7] H. Herr, A. Wilkenfeld, Ind. Rob. 30 (2003) 42–55. [8] B.Y.W. Berger, V. Dietz, J. Quintern (1984) 109–125. [9] C. Mummolo, L. Mangialardi, J.H. Kim, J. Biomech. Eng. 135 (2013) 1–10. [10] H.L. Yu, S.N. Zhao, Z.H. Xu, J. Brazilian Soc. Mech. Sci. Eng. 33 (2011) 366–372. [11] W. Paper, (n.d.) 1–35. [12] A. Kumar, P. Swami, S. Anand, U. Singh, Appl. Math. Model. 72 (2019) 356–368. [13] A.C. Etoundi, 8 (2013) 213–225. [14] I.O.P.C. Series, M. Science, (2018). [15] Z. Haoran, H. Chenghao, L. Xinyu, G. Liang, Z. Bing, D. Haozhen, 59 (2019) 361– 372. [16] M.S. Keszler, J.T. Heckman, (2019).
Please cite this article as: P. Siddikali and P. Rama Sreekanth, Modeling of pneumatic controlled bio mimetic articulated passive prosthetic spring loaded knee mechanism for transfemoral amputees, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.12.377