Development of dynamic model-based controller for upper limb exoskeleton robot

In this paper, we propose and experimentally test a dynamic model-based force controller for the motion of upper limb exoskeleton robot. The system is composed of 3 degrees of freedom using an electrical actuator. This system is mainly controlled by the multi-axis force sensor signals. These are used to generate desired torques for driving the robot system. However, singularities exist when force signals in the Cartesian coordinate system are transformed to torques in the joint coordinate system. So we applied the damped least squares method. In handling loads, torque compensation regarding the weight of the object is required. Therefore, we installed the multi-axis force sensor at the robot end effector. It measures the interaction forces between the exoskeleton and the load. To compensate for the handling object, we used the static model. We performed control stability and load handling experiments to verify the effectiveness of the controller. With these experiments, we confirmed the effectiveness of the proposed controller.