Research on static decoupling algorithm for piezoelectric six axis force/torque sensor based on LSSVR fusion algorithm

Six axis force/torque sensors with characteristics of high precision, high reliability, and high dynamic, have become one of the major bottlenecks restricting the development of the robot. Aiming at the existing decoupling problem of piezoelectric six axis force/torque sensor with four point support structure, this paper presents the research and application on static decoupling method. Firstly, initial experimental data for decoupling of piezoelectric six axis force/torque sensor is obtained by making a calibration experiment. And then, experimental data are analyzed according to evaluate indicator. The linear decoupling algorithm based on the least square (LS) method is performed. Fusion decoupling algorithm based on Least Square Support Vector Machine Regression (LSSVR) is adopted to optimize multi-dimensional nonlinear characteristics of sensor output. The mapping relation between input and output of the sensor is identified. After LSSVM fusion algorithm decoupling, the maximum nonlinear error and cross coupling error are 0.89%, and 0.1%, respectively. The results show that the decoupling of LSSVR fusion algorithm can reduce the nonlinear error and cross coupling error of the fabricated piezoelectric six axis force/torque sensor. It has important significance to improve the measurement accuracy of robot force feedback with piezoelectric six axis force/torque sensors.