Design of bionic active–passive hybrid-driven prosthesis based on gait analysis and simulation of compound control method

Purpose The purpose of this paper is to design a prosthetic limb that is close to the motion characteristics of the normal human ankle joint. Methods In this study, combined with gait experiments, based on a dynamic ankle joint prosthesis, an active–passive hybrid-driven prosthesis was designed. On this basis, a real-time control algorithm based on the feedforward compensation angle outer loop is proposed. To test the effectiveness of the control method, a multi-body dynamic model and a controller model of the prosthesis were established, and a co-simulation study was carried out. Results A real-time control algorithm based on the feedforward compensation angle outer loop can effectively realize the gait angle curve measured in the gait test, and the error is less than the threshold. The co-simulation result and the test result have a high close rate, which reflects the real-time nature of the control algorithm. The use of parallel springs can improve the energy efficiency of the prosthetic system. Conclusions Based on the motion characteristics of human ankle joint prostheses, this research has completed an effective and feasible design of active and passive ankle joint prostheses. The use of control algorithms improves the controllability of the active and passive ankle joint prostheses.

On the Study of Configuration and Kinematics of a 3-DOF Generalized Spherical Parallel Mechanism for Ankle Rehabilitation

The kinematic equivalent model of the existing ankle rehabilitation robot is inconsistent with the anatomy structure of the human ankle, which will influence the rehabilitation effect . Therefore, this paper equivalent the human ankle to the UR model and proposes a novel 3-DOF generalized spherical parallel mechanism for ankle rehabilitation. The parallel mechanism has two spherical centers corresponding to the rotation center of the tibiotalar joint and subtalar joint. Via screw theory, the mobility of the parallel mechanism is analyzed, which meets the requirement of the human ankle. Its inverse kinematics is presented and singularities are identified based on the Jacobian matrix. The workspaces of the parallel mechanism are obtained by the search method and compared with the motion range of the human ankle, which shows that the parallel mechanism could meet the motion demand of ankle rehabilitation. In addition, on the basis of the motion/force transmissibility, the performance atlases are plotted in the parameter optimal design space and the optimum region is obtained according to the demands of practical application. The results show that the parallel mechanism can meet the motion requirements of ankle rehabilitation and have excellent kinematic performance in its rehabilitation range, which provides a theoretical basis for the prototype design and experiment verification.

AN REHABILITATION ROBOT DRIVEN BY PNEUMATIC ARTIFICIAL MUSCLES

Rehabilitation robots are playing an important role in restoring movement ability of hemiplegic patients. However, most of these robots adopt motors as actuators. Considering human body is a flexible organism, rigid motors lack compliance when getting in touch with patients. This paper designs an ankle rehabilitation robot by employing pneumatic muscle actuators which are soft and have similar compliance with biological muscles. Analysis of motion characteristics of human ankle is performed, and relationship between angle and torque of human ankle acquired from experiment is studied. Driving mechanism using pneumatic muscle actuators is addressed carefully and ankle-rehabilitation robot is designed. Then, dynamics of the robot is established and structure optimization of the driving mechanism is performed. Consequently, prototype is manufactured and assembled.