Robots, computer algebra and eight connected components

TL;DR

This paper advances computer algebra methods to analyze kinematic singularities in robotics, specifically computing connected components and roadmaps for parametric robot models, confirming that generic robots in a certain family have eight connected components.

Contribution

It introduces a novel algorithm for solving parametric polynomial systems and applies it to analyze the kinematic singularities of a family of industrial robots.

Findings

Number of connected components is eight for generic robots in the family.

Algorithm effectively partitions parameter space for connectivity analysis.

Practical experiments validate the computer-aided proof approach.

Abstract

Answering connectivity queries in semi-algebraic sets is a long-standing and challenging computational issue with applications in robotics, in particular for the analysis of kinematic singularities. One task there is to compute the number of connected components of the complementary of the singularities of the kinematic map. Another task is to design a continuous path joining two given points lying in the same connected component of such a set. In this paper, we push forward the current capabilities of computer algebra to obtain computer-aided proofs of the analysis of the kinematic singularities of various robots used in industry. We first show how to combine mathematical reasoning with easy symbolic computations to study the kinematic singularities of an infinite family (depending on paramaters) modelled by the UR-series produced by the company ``Universal Robots''. Next, we compute roadmaps (which are curves used to answer connectivity queries) for this family of robots. We design an algorithm for ``solving'' positive dimensional polynomial system depending on parameters. The meaning of solving here means partitioning the parameter's space into semi-algebraic components over which the number of connected components of the semi-algebraic set defined by the input system is invariant. Practical experiments confirm our computer-aided proof and show that such an algorithm can already be used to analyze the kinematic singularities of the UR-series family. The number of connected components of the complementary of the kinematic singularities of generic robots in this family is $8$.