A Cable-Driven Human Assistive System and Its Impedance Compensation by Sensor Fusion

A cable-driven actuating system is proposed in this paper. The proposed system is attractive for human assistive devices because the weight of the actuator is not imposed on the human body. Since the end-effector and the actuators are connected by cables in flexible tubes, the humans are allowed to freely move in a certain range while being assisted. However, it is a challenge to account for the variable friction in the flexible tube and the inertia and friction of the actuator in the design of control algorithms. In this paper, a hierarchical control strategy is adopted to control the proposed cable-driven assistive system. To determine the reference trajectory of the motor in real-time, a sensor fusion method based on a kinematic Kalman filter with MEMS accelerometers is applied. By the proposed control methods, the proposed cable-driven system realizes a precise force-mode actuation.