A novel one-dimensional force sensor calibration method to improve the contact force solution accuracy for legged robot

Abstract

• This method can be carried out on LHDS without disassembling the force sensor. • This method can avoid the irregular variation of calibration coefficient. • This method can simply compensate for the influence of dynamics. Abstract In this paper, aiming at the phenomenon that the calibration coefficient deviation of the one-dimensional force sensor will lead to the deviation in measuring force, a novel method is proposed to recalibrate the one-dimensional force sensors of each joint directly on the leg hydraulic driving system (LHDS) of legged robot. This method has two main contributions. One is that it not only can be carried out directly on LHDS without disassembling the force sensor but also can avoid the irregular variation of calibration coefficient caused by the installation preloading force, friction, mechanical clearance, and other factors. The other is that the method can simply compensate for the influence of dynamics in the calibration process and avoid the complicated mathematical calculation. Under eight working conditions, the experimental results show that the proposed calibration method can decrease the foot end contact force deviation rate more than 20% in the whole cycle. The novel calibration method proposed in this paper can be extended to any leg structure equipped with the same kind of one-dimensional force sensor. It has practical value in engineering.