Title :
Variable Stiffness Actuator applied to an active ankle prosthesis: Principle, energy-efficiency, and control
Author :
Everarts, Christophe ; Dehez, Bruno ; Ronsse, Renaud
Author_Institution :
Centre for Res. in Mechatron., Univ. catholique de Louvain, Louvain-la-Neuve, Belgium
Abstract :
Series elastic actuators are very popular in rehabilitation robotics. Among other advantages, elastic elements between the actuator and the load permit to store and release energy during the task completion, such that the energy balance is improved and the motor power peak is decreased. In rhythmic tasks like walking, this reduces to design the spring stiffness such that it works at resonance. To comply with different gaits and cadences, it is therefore necessary to design Variable Stiffness Actuators (VSA). This paper proposes three contributions: (i) we apply a particular concept of VSA to an active ankle prosthesis; (ii) we discuss the relevance of using VSA to change the stiffness also within the gait cycle; and (iii) we elaborate some control strategies for this device. Our guideline is to track a mechanical design and a controller maximizing energy efficiency. We establish that a promising approach is simply to control the amount of energy stored in the elastic element.
Keywords :
design engineering; elasticity; energy conservation; gait analysis; medical robotics; prosthetics; springs (mechanical); VSA; active ankle prosthesis; control strategies; elastic actuators; elastic elements; energy balance; energy efficiency maximization; gait cycle; mechanical design; rehabilitation robotics; spring stiffness design reduction; task completion; variable stiffness actuator; Actuators; DC motors; Legged locomotion; Prosthetics; Springs; Torque; Voltage control;
Conference_Titel :
Intelligent Robots and Systems (IROS), 2012 IEEE/RSJ International Conference on
Conference_Location :
Vilamoura
Print_ISBN :
978-1-4673-1737-5
DOI :
10.1109/IROS.2012.6385789