Grasshopper Knee Joint - Torque Analysis of Actuators Using Ionic Polymer Metal Composites (IPMC)

Abstract

Biomimetic is the field of engineering which involves analyzing the biological beings and incorporating their designs and systems for manufacturing mechanical systems. An Ionic Polymer metal composite (IPMC) is a smart material that displays a significant bending and tip force after the application of a low voltage. It is light-weighted, flexible, easily actuated, multi-directional applicable and requires simple manufacturing. In this paper, a two-link biomimetic knee joint mechanism of a grass hopper is presented. Secondly, an IPMC pair of strips is proposed as a link that enables the actuating force which is modeled on the basis of the grass hopper's leg. Thirdly, dynamic model is developed for the proposed mechanism through Lagrangian mechanics. Fourthly, power series is utilized for the solution of the non-linear transcendental model. Wolfram mathematica is employed for the simulation of the model. Finally, the effect of torque is analyzed by varying the actuating torque. It is concluded that actuating torque is directly proportional to the angles moved and inversely proportional to the potential energies of the linkage. Furthermore, a stiffer and more vibrant linkage is observed as per simulation results. These results are validated theoretically. Our simulation results indicate that the proposed IPMC has the potential for utilization in small biomimetic applications like insects robots joints activation, underwater fish fins, surgical grippers, synthetic ventricular muscles and human catheter system for endoscopic surgery and diagnostics etc.