A geometric approach for inverse kinematics of a 4-link redundant In-Vivo robot for biopsy

•A geometric approach for inverse kinematic solutions of redundant manipulators.•A model for a 4-link redundant manipulator of an In-Vivo biopsy robot was developed.•Simulations were carried out in MATLAB using the developed approach.•Experiments were conducted on a 4 scaled model of the In-Vivo robot.•Simulation results were validated against the experimental results.

The presence of a large number of degrees of freedom enables redundant manipulators to have some desirable features like reaching difficult areas and avoiding obstacles. These manipulators in the form of In-Vivo robots will enhance the dexterity and capacity of a surgeon to explore the internal cavity when inserted in the existing tool channel of the endoscope to take a biopsy from the stomach. This paper presents a simple geometric approach, to solve the problem of multiple inverse kinematic solutions of redundant manipulators, to find a single optimum solution and to easily switch from one solution to another depending upon the path and the environment. A simulation model of this approach has been developed and experiments have been conducted on the In-Vivo robot to judge its effectiveness.