双层预紧式六维力传感器及其静态标定

Dual Layers Pre-stressed Six-axis Force Sensor and Its Static Calibration

针对基于传统Stewart结构六维力传感器在解耦、刚度等方面性能的不足,设计并研制一种双层预紧式六维力传感器,并对其进行静态标定试验研究。所设计的六维力传感器采用球窝锥头式球面副代替传统球副,有效地减小了球副的摩擦力矩,另外测量分支只承受压力,消除了力在换向时对接触球面的冲击,提高了整体刚度。基于螺旋理论推导出传感器所施加外力与测量分支轴向力之间的映射关系,进而说明预紧式六维力传感器的测量原理。采用最小二乘线性化标定方法对传感器进行静态解耦和测量误差分析,推导出传感器的标定矩阵和误差矩阵。研制出双层预紧式六维力传感器样机,并进行静态标定试验。经过标定试验,该传感器各方向最大非线性度误差低于满量程的1.17%,最大耦合误差低于满量程的1.82%。试验结果表明双层预紧式六维力传感器具有很高的测量精度,可用于工业生产中对六维力测量要求较高的场合。

According to the deficiency of performance of the traditional six-axis force sensor based on Stewart platform structure on decoupling and stiffness, a pre-stressed six-axis force sensor with dual layers is designed and developed, and the static calibration of the sensor is carried out. The proposed six-axis force sensor uses cone-socket type spherical joint instead of the traditional one, which reduces the friction torque of spherical pair effectively and eliminates the commutation impact force for the measuring limbs compressed all the time, so the overall stiffness is improved. Based on screw theory, the mapping of the applied external force and the axial force of measuring limbs of the sensor is derived, and then the measuring principle of the pre-stressed six-axis force sensor is described. Analysis of static decoupling and measurement error of the sensor is conducted by using linear least squares calibration method, and the calibration matrix and error matrix are deduced. The prototype of the dual layers pre-stressed six-axis force sensor was manufactured and the static calibration is performed. The experimental result shows that the maximum nonlinearity error in all the directions of the sensor prototype is less than 1.17%, and the maximum interference error is less than 1.82%, which indicates that the developed six-axis force/torque sensor possesses high measurement accuracy, and can be used for the industrial production which requires higher six-axis force measurement.