On the optimal design of parallel robots taking into account their deformations and natural frequencies

TL;DR

This paper evaluates the effectiveness of simplified stiffness and vibration models in the optimal design of parallel robots, emphasizing the importance of comprehensive models to prevent excessive deformations and ensure rigidity.

Contribution

It demonstrates that simplified models may lead to suboptimal designs and advocates for using complete stiffness and vibration models in robot optimization.

Findings

Simplified models can produce robots with excessive deformations.

Complete models improve the rigidity and performance of the robot.

Using full models prevents designs with long, flexible legs.

Abstract

This paper discusses the utility of using simple stiffness and vibrations models, based on the Jacobian matrix of a manipulator and only the rigidity of the actuators, whenever its geometry is optimised. In many works, these simplified models are used to propose optimal design of robots. However, the elasticity of the drive system is often negligible in comparison with the elasticity of the elements, especially in applications where high dynamic performances are needed. Therefore, the use of such a simplified model may lead to the creation of robots with long legs, which will be submitted to large bending and twisting deformations. This paper presents an example of manipulator for which it is preferable to use a complete stiffness or vibration model to obtain the most suitable design and shows that the use of simplified models can lead to mechanisms with poorer rigidity.