Task Specified Control of a Compliant Parallel Arm Mechanism

Small deflecting flexible parallel arm mechanisms are common in instrument design and often used for precision measurements. Large deflecting parallel arm mechanisms are found usage in MEMS as a suspension of comb drives. In this study control of a compliant parallel arm mechanism for specific tasks are investigated. Compliant parallel arm mechanism consists of two large deflecting initially straight cantilever beams and a rigid coupler and actuated by a magnetic force drive. The kinematic synthesis of mechanism has been studied using mathematically exact nonlinear Elastica theory. Mechanism dynamic response is obtained under time varying magnetic force input. Nonlinear equation of motion is solved numerically using Runge-Kutta methods. Simulation results have been obtained by including translational inertia of rigid coupler and damping forces. Load deflection characteristic of flexible beams are represented by polynomial curve fits obtained from nonlinear inextensible exact beam theory are used as the nonlinear lumped system stiffness. Compliant parallel arm mechanism might be used for different purposes either in macro scale or micro scale depending on specified task. It might be used as an indexing mechanism or a dwell mechanism if the rigid coupler could be positioned at specified points at specified times. Conventional controllers such as PID controllers are designed to achieve position control for specific trajectory. Trajectory simulation results for the compliant parallel arm mechanism are presented using linear and nonlinear spring stiffness.