压电自感知微夹钳

研制了不需要外部附加微位移与微力传感器、采用自感知方法来获取压电微夹钳的钳指位移与夹持力的压电自感知微夹钳。根据压电陶瓷晶片在驱动电压与外力作用下发生变形会在其表面产生电荷的思想,提出了基于积分电荷的钳指位移与夹持力的自感知方法;基于Jan G.Smits的压电悬臂梁弯曲变形理论,给出了钳指位移与夹持力的自感知表达式,即用钳指上压电陶瓷晶片表面的电荷来表达钳指位移与夹持力。设计了获取晶片表面电荷的积分电路,给出了其平衡条件为晶片电容与其绝缘电阻之积同积分电容与反馈电阻之积相等。自感知验证实验结果表明:修正后在31.59μm最大钳指位移范围内的自感知位移最大偏差为0.78μm;在35.91mN最大钳指夹持力范围内的自感知夹持力的最大偏差为0.24mN。实验结果验证了所提自感知方法是有效的。

Self-sensing piezoelectric micro-gripper

A self-sensing method was utilized to acquire the finger displacement and gripping force of a piezoelectric micro-gripper without micro-displacement and micro-force sensors. As the surface of piezoelectric ceramic wafer will generate free charges when it deforms under the external voltage and external force, a self-sensing method based on integral charges was proposed for sensing the finger displacement and gripping force. According to Jan G. Smits's piezoelectric cantilever bending deformation theory, the self-sensing formulas of the finger displacement and gripping force were derived, namely, the free charges on the surface of the piezoelectric ceramic wafer were used to represent the finger displacement and gripping force. Then an integral circuit was designed to acquire the surface free charges. The balance condition of self-sensing circuit was derived, which was that the product of the equivalent capacitance and leakage resistance of the piezoelectric crystals should be equal to that of the integrating capacitor and balancing resistor. Self-sensing experimental results indicate that the maximum error of modified self-sensing displacement is 0.78 μm for the finger displacement of 31.59 μm. The maximum error of modified self-sensing gripping force is 0.24 mN for the gripping force of 35.91 mN. Those experimental results show that the proposed self-sensing method is effective to detect the finger displacement and the gripping force.