Enlarging parallel robot workspace through Type-2 singularity crossing

Abstract

In order to increase the reachable workspace of parallel robots, a promising solution consists in the definition of optimal trajectories that ensure the non degeneracy of the dynamic model in the Type 2 (or parallel) singularity. However, this assumes that the control law can perfectly track the desired trajectory, which is impossible due to modelling errors. This paper proposes a robust multi-model approach allowing parallel robots to cross Type 2 singularities. The main idea is to shift near singularities to a simplified dynamic model that can never degenerate. The proposed control law is validated experimentally through a Five-bar planar parallel mechanism.

Tekil konumlardan geçen paralel robotlar için hareket planlamasında optimizasyon

“…Son olarak belirtilmelidir ki, model belirsizlikleri robotun planlanan hareketten sapmasına neden olur. Bunu önlemek için uygun bir kontrol sisteminin kullanılması gerekmektedir [17,31]. Zaman (s) f yörünge fonksiyonu…”

On the improvement of calibration accuracy of parallel robots – modeling and optimization

“…An improvement in mean positioning error from 0.873 to 0.479 was reported. Pagis et al (2015) presented a promising robust approach to enlarge work-envelope of parallel robots. The defined optimal trajectory permits crossing Type-2 singularities.…”

A Controller for Avoiding Dynamic Model Degeneracy of Parallel Robots During Type 2 Singularity Crossing

“…Then, the design of a stable controller to cross the singularity becomes problematic. This issue was partially solved in [10] by the design of a multi-model computed torque control. However, the solution proposed requires a more restrictive criterion on the designed trajectory than the dynamic criterion computed in previous studies [6,3], decreasing the total number of possible trajectories for crossing the singularity.…”