Abstract
In order to suppress the variation of driving torque of planar link mechanisms with a single degree of freedom due to inertial and gravitational forces acting on moving links, a single coil spring with revolute pairs on its both ends is attached between moving links or a moving link and a frame. Based on inverse dynamics calculation, the optimum stiffness and fixing positions of the coil spring are determined so as to minimize the maximum driving torque with simplex method. For an example, the proposed method is applied to a 4-bar crank-rocker mechanism. It is confirmed that the arrangement between coupler link and frame or between crank and rocker links are most effective. The effective range of crank speed around its designed value is also discussed by simulations.
