Multidisciplinary design optimization of mechanism with coordination method based on sensitivity analysis of constraints

The optimization of mechanisms is generally done in the field of mechanism itself. In this paper, a multidisciplinary design optimization (MDO) concept is applied to synthesize optimum mechanism. Two disciplines of the mechanism and the control are involved in the design optimization of mechanism. The sensitivity analysis technique of constraints is firstly proposed to coordinate complex coupled relation between disciplines. A MDO algorithm, based on genetic algorithm (GA), is proposed to get the optimum mechanism. A six-bar mechanism design problem is given to verify the coordination method and the MDO algorithm. In this study, the objective function of the mechanism is to minimize the difference of the coupler curve and a desired path. When an electric motor is connected to drive the mechanism, the angular speed of the input crank isn’t constant. So, the objective function of the control is to minimize the crank speed fluctuation by using PID feedback control. The optimized six-bar mechanism not only satisfies mechanism and control constraints but also has synthesized optimum function value.