Analytical Inverse Kinematic Solution for "Moz1" NonSRS 7-DOF Robot arm with novel arm angle

TL;DR

This work addresses the analytical inverse kinematics for the Moz1 7-DOF robot arm with wrist offsets (a NonSRS structure) by introducing a novel arm angle $\psi$ and a reduction strategy that converts general poses to a special configuration. It derives closed-form equations for the wrist joints via arm, pose, and quartic constraints, yielding all 16 possible solutions per pose and providing a real-time, deterministic C++ implementation using Eigen. The approach includes a reciprocity-based singularity analysis to identify both kinematic and algorithmic singularities and guides robust operation. Overall, the paper delivers a fast, exact IKP suitable for real-time control of redundant 7-DOF arms with offsets, expanding applicability to precise manipulation tasks in uncertain environments.

Abstract

This paper presents an analytical solution to the inverse kinematic problem(IKP) for the seven degree-of-freedom (7-DOF) Moz1 Robot Arm with offsets on wrist. We provide closed-form solutions with the novel arm angle . it allow fully self-motion and solve the problem of algorithmic singularities within the workspace. It also provides information on how the redundancy is resolved in a new arm angle representation where traditional SEW angle faied to be defined and how singularities are handled. The solution is simple, fast and exact, providing full solution space (i.e. all 16 solutions) per pose.

Figures (3)

• Figure 1: Robot MDH parameters
• Figure 2: Robot kinematic structure
• Figure 3: specific configuration