下肢康复训练机器人髋关节机构的振动分析

Research on the Vibration Characteristics of the Hip Training Part of the Rehabilitation Robot

对研发的康复训练机器人髋关节机构进行了建模分析,探讨机构的振动特性,对后续设置相关机构的工作频率和和对振动主动控制提供了理论依据。方法以康复机器人对患者进行被动节律性训练为工作状态,建立振动力学模型和动力学方程,对康复机器人髋关节机构的运动特点和振动性能进行理论分析,通过仿真曲线展示了幅值和相位差的变化特点。结果康复训练机器人髋关节机构的固有频率与接触部件的等效质量等参数有关。当阻尼大于特定值时,训练机构位移振幅随着工作频率上升而下降,不会发生共振;当阻尼小于特定值时,训练机构位移振幅随着工作频率增加先上升后下降,存在共振现象,阻尼的存在将显著降低位移振幅。结论在小阻尼情况下髋关节机构才会发生共振,当要利用机器人髋关节机构的振动进行振动康复治疗时,应该尽量降低阻尼,并使得工作频率接近固有频率,反之则要增大阻尼和远离固有频率。由于阻尼的存在,训练机构的运动与电推杆滑块的运动存在相位差。

Objective The study focuses on the discussion about the vibration characteristic of the rehabilitation robot hip joint based on a mathematical model, which provides the theory for working frequency setting and vibration active control. Methods The vibration mechanics model and the dynamic equations are established on the patients doing passive rhythmic training on robot at first. Then the movement characteristics and vibration pe^ormance of the structure are analyzed theoretically. The characteristics of the amplitude and phase are showed by the simulation curves. Results The natural frequency of the robot hip joint is related to parameters such as equivalent mass of touch parts. The displacement amplitude decreases as the working frequency increases when the damping is greater than a specific value. The displacement amplitude increases followed by decreases when the damping is smaller than the specific value. For the last status, the resonance phenomenon can occur and the damping can decrease the displacement amplitude significantly. Conclusion The robot hip joint structure produces resonance phenomenon when the damping is small. If the vibration of hip joint is used for rehabilitation, the damping should be decreased and the working frequency should be close to the notural frequency. Otherwise, the damping should be increased and the working frequency should, be far away from the natural frequency. Due to the damping, there is a phase difference between the robot hip joint structure movement and the vibration source.