Digital Force Control in Rehabilitation Robotics
Robots can successfully be applied in rehabilitation of the disabled. Force sensors are used to control the contacts between the robotic arms and the patients’ body parts either during the teaching-in of the robot, or during its operation. The use of certified standard industrial robots inserted into an outer force control loop results low sampling frequency, and the experiments call the attention for the corresponding destabilizing digital effects. The stability of the force based teaching-in method is analysed with application for upper limb motion therapy. The stability limits are presented in the parameter space of the sampling time, control gains and mechanical parameters of the sensor. The least force error is calculated in closed form. Real parameter case study and experiments confirm the analytical predictions.
KeywordsForce Control Force Error Stability Chart Emergency Stop Rehabilitation Robotic
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