3T1R解耦并联机构动力学与惯量耦合特性分析

对一种3T1R解耦并联机构的动力学性能及其惯量耦合强度进行了分析。对机构进行运动学分析,给出了机构的位置正反解方程,得到动平台的雅可比矩阵,推导了机构各构件的速度、加速度;基于牛顿-欧拉法,考虑构件重力以及外负载,建立了机构逆向动力学模型,并用ADAMS软件进行了仿真验证;基于所建的逆向动力学模型,分析了加速度和动平台姿态角对支链驱动力的影响;基于关节空间的惯量矩阵,建立了惯量耦合强度评价指标,分析了其在工作空间内的分布规律,并与降耦前Quadrupteron机构的惯量耦合强度进行了对比分析。结果表明,结构降耦不仅降低了支链间的耦合强度,而且整个工作空间内惯量耦合强度的分布更为一致,提升了机构动态性能的各向同性。

Dynamics Coupling Characteristics of 3T1R Decoupled Parallel Manipulator

The dynamic performance and inertia coupling strength of a 3T1R decoupling parallel mechanism (PM) were analyzed. Firstly, the kinematics of the mechanism was established, and the forward kinematics and inverse kinematics were given to obtain the Jacobian matrix of the moving platform, where the velocity and acceleration of each link and the moving platform were derived. Based on the Newton-Euler method, the inverse dynamics model of the mechanism was established considering the gravity of the components and the external load. The driving forces of the PM were solved, which was then verified by ADAMS dynamics simulation. At the same time, the influences of acceleration and the attitude angle of the moving platform on the driving force of the branch chain were analyzed based on the established dynamics model and the analysis results can provide theoretical basis for trajectory planning of the mechanism. Finally, an inertia coupling evaluation index was proposed based on the inertia matrix in the joint space, which represented the coupling strength of the driving branches when the PM worked at different poses in the workspace. Then the distribution law of the index in workspace was studied and compared with that of the Quadrupteron mechanism before decoupling. The results showed that the decoupling of the PM not only reduced the coupling strength between the branches, but also made the distribution of the coupling strength in the workspace more consistent, which improved the isotropy of the dynamic performance of the mechanism.