Singularity Analysis of ABB's GoFa 5 Robot Arm
Axel Refalo, Ilian Bonev, Clement Gosselin
AI summary
Problem
Collaborative robots like the ABB GoFa 5 lack closed-form inverse kinematics and exhibit numerous, complex singularities that are poorly documented, creating safety risks and control ambiguities for programmers.
Approach
The authors apply Grassmann line geometry and wedge products to classify all unique singular configurations in the joint space, derive simplified sufficient conditions to avoid them, and compare singularity density against traditional robot architectures.
Key results
- Classified 12 distinct singularity types in the GoFa 5 joint space
- Mapped geometric conditions and volumes for each singularity manifold
- Derived simplified, conservative joint-angle thresholds to avoid all singularities
- Quantified and compared singularity prevalence across GoFa 5, UR5e, and A0509 architectures
Why it matters
Provides essential safety guidelines and architectural insights for cobot programmers and designers navigating complex kinematic behaviors.
Abstract
In the past decade, manipulator arms with non- traditional architectures—once found mainly in space and painting applications—have become popular as collaborative robots. Examples include ABB’s YuMi and GoFa, Kinova’s Link 6, and Fanuc’s CRX. These cobots lack closed-form inverse kinematics solutions, making it impossible to unambiguously select one configuration among the 16 (or infinitely many) that correspond to a given end-effector pose, which may create safety risks. Moreover, they exhibit far more singularities than typical manipulators, and most of them are far more complex to describe. Nevertheless, many authors argue these manipulators can provide improved dexterity and a larger workspace. In this paper, we analyze the singularities of ABB’s GoFa using Grassmann line geometry and provide straightforward, sufficient (though conservative) conditions for avoiding them. Then, while GoFa can exhibit over a dozen distinct singularities compared to only three (wrist, shoulder, and elbow) for traditional robot arms, we attempt to quantify which architecture actually possesses a greater amount of singular and near-singular configurations.