Design and Calibration of a Six-axis Force/torque Sensor with Large Measurement Range Used for the Space Manipulator

Multi-axis force/torque sensor is a key component for space robot force control and teleoperation. The special environment of space, however, brings huge challenges to the design of multi-axis force/torque sensor. In this paper, a six-axis force/torque sensor, which could be used as a component for the large manipulator in the space station, is developed. In order to obtain the large measurement range of force/torques, an elastic body based on cross-beam with anti-overloading capability is designed, and the size is optimized by using FEA to guarantee both high stiffness and sensitivity of the six-axis force/torque sensor. Different from the conventional method, the signal acquisition module which includes a high signal-to-noise ratio amplifier circuit is integrated in the sensor so as to be more reliable. Then, a novel calibration system is designed to provide large and accurate force/torque source. According to the particularity of the sensor's coupling errors, two decoupling algorithms are proposed in this paper to achieve high precision and flexible usage. The online decoupling algorithm is based on calculating decoupling matrices in partitioned space, while the offline algorithm is based on an optimized BP Neural Network using GA. Experimental results show that the designed six-axis force/torque sensor works well with high precision and reliability.