Stiffness analysis of a planar parallel manipulator with variable platforms

Abstract

This work investigates the stiffness characteristics of a planar parallel manipulator with variable platforms. The stiffness model is established with shape variables of the base and mobile platforms based on the Jacobian matrix. By virtue of a nondimensionalization of the inhomogeneous stiffness matrix, two homogeneous submatrices are obtained. Upon which, two kinds of performance indices are derived to evaluate the manipulator’s stiffness behaviors, one for translation and the other for rotation. Stiffness performance of the considered manipulator with three types of platforms, namely variable base platform, variable mobile platform and both variable base and mobile platforms, is analyzed. To validate the stiffness models, the established analytical models are compared with the FEA based evaluations. In order to find the configurations with the best global stiffness performance, stiffness optimization with consideration of shape variables is conducted with the particle swarm optimization algorithm. Finally, a case study of platforms’ shape changing in stiffness adjustment is presented.

Keywords:

• Parallel manipulator
• stiffness analysis
• variable platforms
• stiffness optimization
• particle swarm optimization

Disclosure statement

The authors declare that they have no conflict of interest.

Additional information

Funding

The authors acknowledge the financial support by the Chongqing Science and Technology Commission of China (cstc2020jcyj-msxmX0281 & cstc2020jcyj-msxmX0242), the Innovative Research Group of Chongqing Municipal Education Commission (CXQT19026) and the National Natural Science Foundation of China (Nos. 51805060 & 51905060).