Design and Analysis of Underactuated compliant mechanisms

Abstract

Precession and accuracy are important in several mechanisms in practical use. Compliant mechanism provides a solution for such mechanical design problems. It has several other advantages over rigid body mechanism. That is why nowadays a lot of research work is going on in this field. But the main disadvantage of this kind of mechanism is its complexity to analyse and design. So, in order to make the analysis simpler pseudo rigid body model (PRBM) technique is often adopted. A mechanism is called underactuated when it has more degrees of freedom than number of inputs or actuations. For such mechanisms we have to perform the kinematic analysis along with force analysis to obtain the solutions. In this work, two underactuated partially compliant mechanisms have been discussed. In the first case, a partially compliant slider-crank mechanism without any input actuation is taken into account. The kinematic and static force equations are solved numerically to find out equilibrium position of the mechanism. Here, the input is provided by two torsional springs. The second case considered is a two-degree of freedom five bar slider mechanism with one input actuator only. Kinematic analysis along with force analysis using principle of virtual work is illustrated to find the solution. The nonlinear algebraic equations obtained are solved simultaneously based on Newton-Raphson method using a computer program in C and the graphs are plotted between input data and other parameters. In both the cases, input data is taken from references for comparison point-of-view.