大力矩纵扭复合型超声波电机的理论及实验研究

首先提出了纵扭复合型超声波电机的设计理论。同时 ,指出纵振动系统设计精度低是导致纵扭复合型超声波电机难以实现模态简并的主要原因。通过实验研究 ,分析了纵、扭转振动在各自谐振点附近的振动特点 ,得出谐振 -非谐振点运行的纵扭复合型USM能输出较大力矩的原因。     

一种基于摆长反复小幅改变的面内摆动抑制方法

针对空间绳网捕获后系统的摆动问题,借鉴秋千激荡原理的逆向思维,提出了一种在最大摆角处收紧系绳、平衡位置处释放系绳的的面内摆动抑制控制方法。从理论上说明了地面恒重力场下此方法的抑制机理,研究了摆长改变大小和速率对抑制摆动有效性的影响。建立了恒重力场下的摆动抑制实验系统,实验和仿真都表明此方法对地面恒重力场下的面内摆动有很好的抑制效果。根据绳系系统在空间轨道动力学环境下动力学方程,得出将上述方法用于抑制空间绳系系统摆动的条件即只要保证释放系绳的平衡位置满足θ’ >0即可,最后对空间绳系系统摆动抑制进行仿真分析,证实了此方法的有效性。     

A novel two-degree-of-freedom spherical ultrasonic motor using three travelling-wave type annular stators

In order to promote the tolerance and controllability of the multi-degree-of-freedom(M-DOF) ultrasonic motor, a novel two-degree-of-freedom(2-DOF) spherical ultrasonic motor using three traveling-wave type annular stators was put forward. Firstly,the structure and working principle of this motor were introduced, especially a spiral spring as the preload applied component was designed for adaptive adjustment. Then, the friction drive model of 2-DOF spherical motor was built up from spatial geometric relation between three annular stators and the spherical rotor which was used to analyze the mechanical characteristics of the motor.The optimal control strategy for minimum norm solution of three stators’ angular velocity was proposed, using Moore-Penrose generalized inverse matrix. Finally, a 2-DOF prototype was fabricated and tested, which ran stably and controllably. The maximum no-load velocity and stall torque are 92 r/min and 90 m N·m, respectively. The 2-DOF spherical ultrasonic motor has compact structure, easy assembly, good performance and stable operation.     

超声波电动机定子振动能量回收转换特性

为了向密封、恶劣等极端环境中工作的微型机器人提供驱动力矩和电能,根据行波型超声波电机定子孤极频率反馈跟踪原理,研制能量回馈型超声波电机.与传统超声波电机相比,该电机不仅具有驱动功能,还具有将定子振动能量回收并转换成电能的功能.根据能量回馈型超声波电机驱动原理改进了超声波电动机压电陶瓷的极化分区模式,将超声波电机定子压电陶瓷极化分成3个区,即：激振区、能量采集区和传感区（孤极）.利用定子能量采集区压电陶瓷的正压电效应采集回收超声波电动机定子的机械振动能量.根据铁摩辛柯梁理论和压电本构方程建立超声波电动机定子振动能量采集回收的理论分析模型,研究能量采集区压电陶瓷负载阻抗的匹配问题.利用该模型仿真分析了电机激励频率、激振电压、外接负载电阻等对能量采集区压电陶瓷输出电压、输出电流和输出功率的影响规律,通过实验验证了仿真结果的正确性.