A Combined Inverse Kinematics Algorithm Using FABRIK with Optimization

TL;DR

This paper introduces a hybrid inverse kinematics algorithm combining FABRIK and SQP to improve convergence stability and success rates in real-time manipulator motion planning.

Contribution

A novel combined algorithm that uses FABRIK outputs as initial seeds for SQP, enhancing stability and efficiency in high-error inverse kinematics scenarios.

Findings

Achieves higher success rates than FABRIK alone.

Faster solution times in inverse kinematics problems.

Generates smooth trajectories with minimal pose error.

Abstract

Forward and backward reaching inverse kinematics (FABRIK) is a heuristic inverse kinematics solver that is gradually applied to manipulators with the advantages of fast convergence and generating more realistic configurations. However, under the high error constraint, FABRIK exhibits unstable convergence behavior, which is unsatisfactory for the real-time motion planning of manipulators. In this paper, a novel inverse kinematics algorithm that combines FABRIK and the sequential quadratic programming (SQP) algorithm is presented, in which the joint angles deduced by FABRIK will be taken as the initial seed of the SQP algorithm to avoid getting stuck in local minima. The combined algorithm is evaluated with experiments, in which our algorithm can achieve higher success rates and faster solution times than FABRIK under the high error constraint. Furthermore, the combined algorithm can generate continuous trajectories for the UR5 and KUKA LBR IIWA 14 R820 manipulators in path tracking with no pose error and permitted position error of the end-effector.