FABRIK-Based Inverse Kinematics For Multi-Section Continuum Robots

Continuum robots are flexible manipulators capable of working in a complex workspace. In this regard, they are widely used in medicine and industry. However, existing methods of solving the inverse kinematics problem based on Jacobian inverse have high computational cost and singularity problems. In its turn, methods based on the geometric approach cannot find a solution for some points. This paper presents a novel approach for solving the inverse kinematics issue for multi-section continuum robots based on the Forward And Backward Reaching Inverse Kinematics (FABRIK) algorithm. The approach enables to reach the target point, controlling the robot tip orientation. During forward reaching, the bending sections of the robot are replaced by chords, connected together by spherical joints. During backward reaching, the arcs are restored from the chords and then the end-points and their orientations are updated. We also present a solution of the forward and inverse kinematics for a single-section robot, which is necessary for arcs restoration during backward reaching. To minimize the angular error, the last link of the robot is adjusted. The results of the simulation proved that the algorithm is able to reach 98.5±1.3% of the robot workspace and of 92.7±4.6% dexterity. The mean operating time of the algorithm is 1.45±1.32 ms per section. The results and possible modifications are also discussed.