A novel methodology of calculating the human-machine interactive force for a head-neck exoskeleton

Abstract

A new method based on the dynamic model of the head-neck exoskeleton (HN-EXO) is presented for calculating the external forces/torque imposed on the platform. First, force analysis is conducted on each leg of the HN-EXO, and the Newton-Euler method is adopted to establish the relationship between the driven torques and the forces at the spherical joint. Second, a dynamic analysis is performed on the sensor group, and the relationship between the forces at the spherical joint and the feedback of the sensor assembled in the joint space is established. Third, the equation between the driven torque and the feedback of the sensor is derived based on the previous work. Fourth, Newton-Euler dynamic equations are incorporated into the system to determine the relationship between the human-machine interactive force and the feedback of the sensors. Finally, an experiment is conducted, the results of which are as follows. (1) The performance of the proposed algorithm is better than the existing one in terms of effectiveness, accuracy, and stability. (2) The maximum calculating time of the new method is 4.25×10-4 s, which is one-fifth of the control cycle period. Therefore, the new algorithm can be adopted to accomplish real-time control under the frequency of 500 Hz.