用于机器人手指的SOI基板微压阻式力传感器

Micro Piezoresistive Force Sensor on SOI Substrate for Robot Fingers

压阻式力传感器常被用作工业机器人手指接触力传感器,为准确测量微小力与力矩,设计并测试了一种用于六自由度微力测量的微压阻式力传感器。该传感器由传力支柱、软半球盖、力-力矩传感结构和Wheatstone电桥四部分构成。采用有限元方法分析了各方向上施加力时应力的分布情况,由此确定了压敏电阻的位置分布。采用光刻、掺杂、深反应离子刻蚀和键合等微细加工工艺制备微压阻式力传感器的力-力矩传感结构(2 mm×2 mm×0.5 mm)。测试结果表明:传感器的量程为0~875 mN,z方向上的力Fz灵敏度为0.14 mV/mN,y方向上的力矩My灵敏度为1.76 mV/N·μm,x方向上的力矩Mx灵敏度为1.66 mV/N·μm,力-力矩传感结构相互间的串扰≤5%,并且施加的力与输出电压呈线性关系。该传感器具有体积小、灵敏度高和可靠稳定的特点。

Piezoresistive force sensor is often used as finger contact force sensor for industrial robots.To accurately measure small forces and moments,a micro piezoresistive force sensor for six-degree-of-freedom micro-force measurement was designed and tested.The sensor is composed of four parts:force transmission pillar,soft hemispherical cover,force-torque sensing structure and Wheatstone bridge.The finite element method was used to analyze the stress distribution when the forces were applied in all directions,and thus the position distribution of the varistors was determined.The force-torque sensing structure(2 mm×2 mm×0.5 mm)of the micro piezoresistive force sensor was prepared by using photolithography,doping,deep reactive ion etching,bonding and other microfabrication techniques.The results show that the range of the sensor is 0-875 mN,the sensitivity of force in the z direction(Fz)is 0.14 mV/mN,the sensitivity of torque in the y direction(My)is 1.76 mV/N·μm,and the sensitivity of torque in the x direction(Mx)is 1.66 mV/N·μm,the crosstalk between the force-torque sensing structures is≤5%,and the applied force has a linear relationship with the output voltage.The sensor has the characteristics of small size,high sensitivity,reliability and stability.