A patient-specific biological command based controller for the Human-inspired robotic exoskeleton (HuREx): A case study for gait-swing assistance robot

A biological command based controller designed for the Human-inspired robotic exoskeleton (HuREx) was developed and introduced in this paper. This controller is built upon human's musculoskeletal system which could provide subject-specific parameters for the controller as well as the robot design. There are two layers in the biological command based controller: the outer position controller and the inner force controller which aim to track desired position and force respectively. Desired forces aiming to control the actuators were calculated firstly by the real-time muscle force estimation (RMFE) algorithm using kinematic inputs. Then a model based PID controller was used as the inner force controller to control the pneumatic air muscle actuators directly. The controller was tested by a gait-swing assistance robot. A gait cycle of knee joint was used as desired trajectory for position tracking. The simulation results show that the proposed biological command based controller could track both desired knee angles and desired forces.