Development and Application of a Terminal Rigidity Enhancement Methodology for Parallel Robots

Parallel robots are recognized as a promising solution for heavy-load and high-efficiency tasks in modern manufacturing systems. The terminal rigidity is a critical performance metric for parallel robots, significantly affecting their payload capacity and machining accuracy. However, enhancing terminal rigidity is still a challenge due to the inherent design conflict between high rigidity and lightweight structures. Aiming at this challenge, this study proposes a practical yet high-ly efficient methodology to enhance terminal rigidity without incurring a weight increase. Firstly, an intensity factor is constructed as a discriminant metric to enable a sensitivity-based classification of components. Subsequently, a rigidity enhancement methodology is developed, which entails executing a step-by-step procedure to improve the stiffness of parallel robots. Next, the methodology is applied to a novel redundantly actuated parallel machining robot to demonstrate its practical utility in engineering design. The result shows that the proposed methodology achieves a 31.3% enhancement in linear terminal rigidity, coupled with a 5.6% decrease in overall weight. Finally, experimental verification is conducted through stiffness tests on a laboratory prototype, demonstrating that the enhanced terminal rigidity meets design expectations.