基于并联机床刚体动力学的最优控制方法研究

利用牛顿-欧拉法建立了六自由度并联机床的包括控制轴和动平台的惯性力、离心力、科氏力、重力以及粘性阻尼力等作用力的刚体动力学模型。定义加速度策略为刀具在加工过程中加速度的大小和形式。根据动力学模型，针对特定的轨迹，研究了不同加速度策略对驱动力性质的影响规律，并且得到了最佳加速度策略。为了使伺服电机的输出最为平稳，建立了以机床在轨迹中用最大速度匀速运动时的速度为优化参数的目标函数，在给定的加工速度范围内找出最优速度使输出功率变化最小，从而为控制提供了理论依据。

Investigation of the Optimal Control Method Based on the Rigid Dynamic Model of PKM

As for the 6-DOF Parallel Kinematic Machine (PKM), the gravity, inertial force, eccentricity and Coriolis' force of the legs and the moving platform, and the viscous friction at the universal and sphere joints affect the dynamic characteristics of the PKM greatly. This paper establishes an inverse dynamic model in which all the factors listed above are considered by using the Newton-Euler approach. The acceleration strategy is defined as the magnitude and mode of acceleration. When the trajectory is specified, the effect of different acceleration strategy on the driving forces of the six legs is proved to be immense, and the optimal strategy is suggested. In order to obtain the minimum change ratio of the deferent power of the servomotor, the optimal velocity is gained by creating a new criterion on determining the best control method.