Design optimisation for a novel underactuated robotic finger by genetic algorithms

Abstract

This paper presents a novel design of the robotic finger as a development of the Otto bock hand design, especially in the index finger of the hand. Namely, make it composed from three phalanges instead of a single one. In addition, in order to improve the grasping dexterity, a four-bar mechanism for each phalanx was used. This results in finding the optimum dimensions of the linkages to drive the robotic finger. To achieve such aim, a Genetic Algorithm (G.A) was employed. Two criteria were chosen for finding the optimal solution; Grasping force criterion and Squeezing force criterion. The optimisation criteria are based on the force analysis equations that derived to calculate the contact forces during power grasping action. The prosthetic finger was built from PLA (Polylactic Acid) plastic using a 3D printer and tested experimentally through a special measuring mechanism provided with a sensory system. The experimental and the theoretical results of the normal force of the finger were in good agreement.