Wideband force control system based on friction free and noise free observation

In this paper, a new force sensing technique is proposed to achieve a friction free and wideband force control of a ball screw system. A periodic signal is inserted into the control system for friction reduction. A combination of a high-order disturbance observer and a Kalman-filter is constructed to perform the force sensing operation. The high-order disturbance observer is designed to obtain force estimation with the cancellation of oscillatory disturbance caused by additional periodic signal. The force sensing bandwidth is improved owing to the effective noise suppression in the estimated force by Kalman-filter. Additionally, all of the control algorithms are implemented in a Field Programmable Gate Array (FPGA) with a fast sampling rate that also enables the ability to widen the bandwidth of the force control system. The effectiveness of the proposed method is verified by experimental results.