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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.
According to the need of clamping of microtubes (0 ~ 300μm in diameter), an asymmetric piezoelectric microgripper is designed based on the finite element analysis.The microgripper adopts flexible hinge to realize the piezoelectric ceramic output displacement The parallel four-bar mechanism is adopted to realize the parallel movement of the end of the clamp.The measurement of the holding force and the displacement information is indirectly measured by the method of detecting the strain at the flexible hinge.Experimental characteristics of the microgripper show that the magnification of the displacement is 5.6 times, the clamp end clamp can move in parallel. Force and displacement calibration experiments show that the resolution of the clamping force is 2.41 mN, the resolution of the displacement is 0.22μm, and the force / displacement and strain have good Linear relationship.The incremental PID control algorithm is used to control the force / displacement of the system in closed-loop mode.Taking micro-glass tube (diameter 150μm) as an example, the system step response experiment shows that the system’s force / displacement control can be realized No overshoot.The experimental results show that the incremental PID control algorithm can achieve accurate and stable control of the force / displacement of the microgripper.