摘要
An adjustable torsional stiffness control system with a magnetic coupling that offers compliance for robotic devices to cooperate with humans is presented in this paper. Most robotic devices, such as robotic grippers or robotic arms, achieve torque control by manipulating current in actuators. As power consumption derived from the actuator current is not precise enough to represent the output torque, series elastic actuation (SEA) is instead proposed and examined in this research that involves adding an elastic component between the actuator and the load, allowing the force to be measured by calculating the deformation of this elastic component. In this paper, an axial magnetic coupling having 24 mm in diameter and 3 mm in thickness forming is adopted as the elastic component of the magnetic series elastic actuation (MSEA) system. Through the MSEA controller, the load stiffness can be controlled as a variable spring in a range of 100 to 500 mN·m/rad, producing a maximum output torque of 300 mN·m, force resolution of 0.1 mN·m and control error less than 6 mN·m. By adding the SEA component between the actuator and the load, one can control system’s output torque and output stiffness simultaneously, making the actuator more flexible and compliant.