A review of cuspidal serial and parallel manipulators

TL;DR

This paper reviews cuspidal robots, which can change configurations without passing through singularities, highlighting their design challenges and recent industrial examples, aiming to improve understanding and trajectory planning.

Contribution

It provides a comprehensive review of cuspidal robots, including serial and parallel types, and discusses their fundamental properties, identification issues, and implications for robot design and control.

Findings

Cuspidal robots can transition between configurations without singularities.

Identification of all cuspidal robots remains an open research problem.

Recent industrial robots may be cuspidal but are often unrecognized.

Abstract

Cuspidal robots can move from one inverse or direct kinematic solution to another without ever passing through a singularity. These robots have remained unknown because almost all industrial robots do not have this feature. However, in fact, industrial robots are the exceptions. Some robots appeared recently in the industrial market can be shown to be cuspidal but, surprisingly, almost nobody knows it and robot users meet difficulties in planning trajectories with these robots. This paper proposes a review on the fundamental and application aspects of cuspidal robots. It addresses the important issues raised by these robots for the design and planning of trajectories. The identification of all cuspidal robots is still an open issue. This paper recalls in details the case of serial robots with three joints but it also addresses robots with more complex architectures such as 6-revolute-jointed robot and parallel robots. We hope that this paper will help disseminate more widely knowledge on cuspidal robots.