一种上肢康复机器人机械臂重力平衡方法

A method of mechanical arm gravity balance for upper limb rehabilitation robot

目的针对现有上肢康复机器人机械臂质量较大且其自体质量无法忽略等问题,基于重力平衡原理提出一种上肢康复机器人机械臂重力平衡方法。方法通过角度传感器检测肩关节屈/伸角度,将经过滤波的模拟量信号传送到单片机,单片机计算得到目标力矩,并作为控制参数发送到驱动器,驱动器驱动电机进入力矩模式并输出力矩,平衡上肢康复机器人机械臂重力。结果实验所用机械臂长度L_1=300 mm、L_2=300 mm,关节运动角度0°～140°,机械臂自体质量M_1=3.0 kg、M_2=4.4 kg;电机可提供最大力矩27 N·m、最大电流0.766 A;满足实验需求。在肩关节屈/伸角度范围为30°～120°的机械臂上选取7组角度进行实验。实验证明,在30°～75°内实际输出力矩大于理论输出力矩,机械臂保持平衡且有向上运动的趋势;在90°～120°内,实际输出力矩略小于理论力矩,机械臂保持平衡且有向下运动的趋势。结论实验证明,笔者设计能很好地实现机械臂重力平衡。

Objective To study a method for gravity balance of robotic arm of upper limb rehabilitation robot based on gravity balance principle for mechanical arm in upper limb rehabilitation robot with big quality and self-body mass. Methods The angle sensor was used to detect the shoulder ’s buckling/extension angle, and the filtered analog signal was transmitted to microcontrollersm(MCU). The MCU calculated target torque and sent it to driver as a control parameter. The drive run motor into torque mode and output torque to balance gravity. Results The length of arm used in experiment was L,= 300 mm and L2 =300 mm, joint movement angle was 0°-140°, the self-body mass of arm was M1= 3.0 kg and M2=4.4 kg;the motor provided maximum torque of 27 N·m and maximum current of 0.766 A, which met the design requirement of experiment. Seven groups of angle with arm joint flexion/extension angle of 30°-120° were tested. The actual output torque was greater than theory output torque in 30°-75°, and the mechanical arm remained balanced and showed upward trend, while that was contrary in the range of 90°-120°, and the mechanical arm remained balanced and showed downward trend. Conclusion It is demonstrated that the method can balance the mechanical arm gravity well.