Paper 4: A Feasibility Study on Powered Lower-Limb Prostheses

1968 ◽  
Vol 183 (10) ◽  
pp. 18-25 ◽  
Author(s):  
D. C. Witt
Keyword(s):  
Mathematical Model ◽  
Feasibility Study ◽  
Power Supply ◽  
Lower Limb ◽  
Rapid Development ◽  
Analogue Simulation ◽  
Uneven Terrain ◽  
Control Scheme ◽  
Suitable Power ◽  
Lower Limb Prostheses

The paper investigates the feasibility of externally powered lower-limb prostheses, in particular those in which walking motions would be automatically controlled. The lack of a suitable power supply is a major obstacle to the rapid development of a practical prosthesis, but a theoretical and practical study is being made of a ‘prototype walking device’, out of which, if successful, a prosthesis might evolve. The configuration of this device is outlined, with reasons for the choice, and possible actuators and sensors are discussed. A mathematical model is formulated and a control scheme is outlined which should enable the device to walk stably on small feet over uneven terrain. Results of analogue simulation of the device are summarized.

scholarly journals Reinforcement-Learning-Based Asynchronous Formation Control Scheme for Multiple Unmanned Surface Vehicles

2021 ◽  
Vol 11 (2) ◽  
pp. 546
Author(s):  
Jiajia Xie ◽  
Rui Zhou ◽  
Yuan Liu ◽  
Jun Luo ◽  
Shaorong Xie ◽  
...  
Keyword(s):  
Reinforcement Learning ◽  
Formation Control ◽  
Rapid Development ◽  
Gradient Algorithm ◽  
Robot System ◽  
Physical Relationship ◽  
Unmanned Surface Vehicles ◽  
Main Challenge ◽  
Control Scheme ◽  
Multi Robot

The high performance and efficiency of multiple unmanned surface vehicles (multi-USV) promote the further civilian and military applications of coordinated USV. As the basis of multiple USVs’ cooperative work, considerable attention has been spent on developing the decentralized formation control of the USV swarm. Formation control of multiple USV belongs to the geometric problems of a multi-robot system. The main challenge is the way to generate and maintain the formation of a multi-robot system. The rapid development of reinforcement learning provides us with a new solution to deal with these problems. In this paper, we introduce a decentralized structure of the multi-USV system and employ reinforcement learning to deal with the formation control of a multi-USV system in a leader–follower topology. Therefore, we propose an asynchronous decentralized formation control scheme based on reinforcement learning for multiple USVs. First, a simplified USV model is established. Simultaneously, the formation shape model is built to provide formation parameters and to describe the physical relationship between USVs. Second, the advantage deep deterministic policy gradient algorithm (ADDPG) is proposed. Third, formation generation policies and formation maintenance policies based on the ADDPG are proposed to form and maintain the given geometry structure of the team of USVs during movement. Moreover, three new reward functions are designed and utilized to promote policy learning. Finally, various experiments are conducted to validate the performance of the proposed formation control scheme. Simulation results and contrast experiments demonstrate the efficiency and stability of the formation control scheme.

scholarly journals Adaptive Foot in Lower-Limb Prostheses

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Thilina H. Weerakkody ◽  
Thilina Dulantha Lalitharatne ◽  
R. A. R. C. Gopura
Keyword(s):  
Lower Limb ◽  
Uneven Surface ◽  
Design Concepts ◽  
Human Foot ◽  
Future Developments ◽  
Adaptive Capabilities ◽  
Adaptive Nature ◽  
Lower Limb Amputees ◽  
Artificial Prosthesis ◽  
Lower Limb Prostheses

The human foot consists of complex sets of joints. The adaptive nature of the human foot enables it to be stable on any uneven surface. It is important to have such adaptive capabilities in the artificial prosthesis to achieve most of the essential movements for lower-limb amputees. However, many existing lower-limb prostheses lack the adaptive nature. This paper reviews lower-limb adaptive foot prostheses. In order to understand the design concepts of adaptive foot prostheses, the biomechanics of human foot have been explained. Additionally, the requirements and design challenges are investigated and presented. In this review, adaptive foot prostheses are classified according to actuation method. Furthermore, merits and demerits of present-day adaptive foot prostheses are presented based on the hardware construction. The hardware configurations of recent adaptive foot prostheses are analyzed and compared. At the end, potential future developments are highlighted.

Sign in / Sign up

Export Citation Format

Share Document