一种非对称式压电驱动微夹持器

针对微管类(直径0~300μm)零件的夹持需求,基于有限元分析设计了一种非对称式压电驱动的微夹持器.该微夹持器采用柔性铰链实现压电陶瓷输出位移的传递和放大.采用平行四杆机构实现夹钳末端的平行移动.通过检测柔性铰链处应变的方法,间接地测量夹持力和位移信息.微夹持器的实验特性显示位移的放大倍率为5.6倍,夹持器末端夹钳可以实现平行移动.力和位移标定实验中显示夹持力的分辨力在2.41 m N,位移的分辨力在0.22μm,且力/位移与应变具有很好的线性关系.采用增量式PID的控制算法对系统进行力/位移的闭环控制.以微型玻璃管(直径150μm)夹持为例,系统的阶跃响应实验显示,系统的力/位移控制可以实现无超调.实验结果表明增量式PID控制算法可以实现对本微夹持器力/位移的准确、稳定控制.

An Asymmetric Micro-Gripper Actuated by Piezoelectric Ceramics

To satisfy the requirement of clamping micro-tube（ diameter of 0—300 μm）,an asymmetric micro-gripper actuated by piezoelectric ceramics（ PZT） was designed by finite element analysis（ FEA）.The micro-gripper realized the transfer and amplification of displacement from the output of PZT through the flexure hinges. Parallel four-bar linkage was used to realize parallel clamping. The clamping force and displacement of the gripper were measured indirectly by detecting the flexible hinges’ strain. The experiment results indicate that the magnification of displacement is 5. 6 times and the end of the clamp can realize parallel clamping. Calibration experiments of force and displacement indicate that the resolution of the clamping force is 2. 41 m N,the resolution of the displacement is 0. 22 μm and it has a good linear relationship between the force / displacement and strain. Incremental PID control algorithm was used to realize closed-loop control of the force / displacement. The experiment of clamping micro-glass tube（ 150μm diameter） was implemented. The step response of the system had no overshoot basically. Experiment results prove that incremental PID control algorithm is valid for the control of the clamping force and displacement of the micro-gripper and can realize accurate and stable control of the micro-gripper.