考虑含间隙关节的漂浮基空间机械臂动力学输出特性研究

Dynamic Characteristics of Free-floating Space Manipulator with Joint Clearance

研究关节间隙对漂浮基空间机械臂动力学特性的影响对设计空间站机械臂具有重要意义。采用Lankarani-Nikravesh接触力表达式建立了考虑摩擦的含间隙关节模型;应用Lagrange方程和含间隙关节模型建立了含间隙的漂浮基空间机械臂动力学模型。数值模拟分析了间隙关节数量和不同间隙尺寸对漂浮基空间机械臂动力学输出特性的影响,并定量分析了间隙对漂浮基空间机械臂动力学输出的影响程度。结果表明,两个含间隙关节的耦合作用导致关节接触碰撞力剧烈变化,引起漂浮基空间机械臂的动力学输出更加剧烈;关节的间隙尺寸值越大,漂浮基空间机械臂动力学输出的波动幅值越大,但波动频率会随着间隙值的增大而减小,降低了空间机械臂的运动精度。该研究可为解决多个含间隙关节的漂浮基空间机械臂的高精度轨迹控制问题提供重要的理论依据。

The influence of joint clearance on the dynamic characteristics of the free-floating space manipulator is of great significance to the design of the space station manipulator.The joint model with clearance and friction is established by the Lankarani-Nikravesh contact force expression and the dynamic model of free-floating space manipulator with clearance is derived by using the Lagrange equation.The dynamic output characteristics is analyzed by numerical simulation in consideration of the number of joints with clearance and different clearance sizes and the influence of the clearance on the dynamic output characteristics of the free-floating manipulator is studied quantitatively.The results show that the coupling effect of the double joints with clearance leads to the dramatic change of the contact forces,which causes the dynamic output of the free-floating space manipulator to be more intense.The dynamic output of the free-floating space manipulator fluctuates more violently with the larger clearance size,but the fluctuation frequency decreases,which seriously reduces the motion accuracy of space manipulator.This study provides the important basis for the high precision trajectory control of free-floating space manipulator with multiple joints with clearance.