The generalized interactive force calculation for the helmet mounted display with the 6URHS parallel manipulator

The method based on the dynamic model to calculate the generalized interactive force between the user's head and the 6URHS parallel manipulator is proposed to validate the feasibility of the active compliance control strategy in [2]. Firstly, the dynamics pertaining to arbitrary leg of the 6URHS parallel manipulator are investigated, and dynamic equations for the leg are derived. Secondly, the dynamic analysis for the sensor group which is a part of the leg and made up of a sensor and the upper part of the spherical joint is developed, and Newton equations for the sensor group are also presented. Thirdly, the relationship expressions about the driving torques of the 6URHS parallel manipulator and the sensor feedbacks are obtained by means of combining the dynamic equations for the legs with the sensor groups. Finally, based on the dynamic model of the 6URHS parallel manipulator and the relationship expressions above, the formula for calculating generalized interactive force is proposed; both simulation and experiment are implemented, simulation results show that the feasibility and the accuracy of the proposed method are better, and the practicability of the method and the performance of the active compliance control strategy are proved to be fine with the experimental results.