Fault-tolerant measurement mechanism research on pre-tightened four-point supported piezoelectric six-dimensional force/torque sensor

摘要

High-precision and fault-tolerant six-dimensional force/torque sensor is one of the core components of intelligent robots for force feedback perception. This paper is aiming at the fault-tolerant measurement mechanism research on piezoelectric six-dimensional force/torque sensors with four-point support structure. Based on principle of leverage and deformation consistent, the fault-tolerant measurement mechanism of the pre-tightened four-point supported piezoelectric six-dimensional force/torque sensor is revealed. The mapping mathematical models of spatial six-dimensional force and four-fulcrum quartz crystal group detection signal for the sensor without signal fault and with signal fault are constructed respectively. The static calibration system of the sensor is built to realize the fault-tolerant static calibration experiment of the four-point supported piezoelectric six-dimensional force/torque sensor prototype under unidirectional loading without signal fault and with signal fault. In order to improve the measurement precision of six-dimensional force/torque sensor for robot, a decoupling method based on Genetic Algorithm to optimize Back Propagation algorithm (GABP) for piezoelectric six-dimensional force/torque sensor is adopted to solve the nonlinear cross coupling problem of multiple-input and multiple-output. Through Maltlab software, the test data are analyzed and calculated, and the percentage coupling error matrix of the sensor is calculated. The percentage coupling error is different when the sensor is fault-free and the fault-free measurement model is different. When the sensor is fault-free, the linearity of the sensor is the best and the maximum coupling error is less than 1.5%. When the sensor has any branch fault, the overall performance of the sensor is relatively weakened and the maximum coupling error increases. When the sensor has two branch faults, the linearity of the sensor is the worst. It cannot satisfy the requirement of accurate measurement. The research content is of great significance to the development and practicality of fault-tolerant multi-point supported piezoelectric six-dimensional force/torque sensor.