Modeling and co-simulation of actuator control for lower limb exoskeleton

This paper presents a methodology of using co-simulation to study the dynamic performance analysis of a lower limb exoskeleton (LLE). For patients who suffer permanent spinal cord injury, using the LLE is one of the most effective ways to assist their walking ability compared to the wheelchair. The robustness of the LLE performance is related to the precision of the LLE dynamic model. However, the LLE model usually dealt with difficulties in development due to its non linear characteristic. Therefore, a virtual design, modeling and simulation of control strategy for dynamic modeling of LLE by using PID control are presented in this paper. The actuator's modeling on the joint is developed by using Matlab system identification technique. The actuators are coupled with human model, and the dynamics of the LLE are analysed. The three-dimensional LLE model is designed with CATIA software and co-simulation approach is introduced by using multi-body dynamic software called ADAMS (Automatic Dynamic Analysis of Mechanical System). Then to validate the model in ADAMS, we integrate it with Matlab-Simulink control model. The results show that, the model can be used in simulation to prove the controller performance for actuator on the low-level controller. The result is significant for the development of the control systems of the LLE prototype.