Modelling and parameter design of a 3-DOF compliant platform driven by magnetostrictive actuators

Precision platforms composed of smart-material-based actuators and compliant mechanisms show advantages of high accuracy and fast response. This research focuses on a 3-degree-of-freedom compliant platform driven by magnetostrictive actuators. A parameterized physical model is established for the platform with consideration of three kinds of coupling effects. The magneto-mechanical coupling of the magnetostrictive actuator is described by a modified Jiles-Atherton model. The structural coupling of the platform is characterized in the process of stiffness matrix modelling and coordinate system transformation of the compliant components. The coupling between the magnetostrictive actuator and the compliant structure is considered in the overall actuation model. Parameter design is performed based on the numerical simulation of the proposed model. Due to the coupling effect, the dimensions of the compliant amplifier affect both the amplification ratio and the actuation stroke of the actuator. Thus, a combined optimization is essential to obtain the optimal design. The influences of the key dimensions on platform stiffness and actuation performances are demonstrated. With optimized key dimensions, the parasitic displacements can be effectively reduced at very little cost of the moving strokes. Open-loop experiments are taken to verify the accuracy of the proposed physical model, and closed-loop experiments are performed to demonstrate the platform performance on precision positioning. The main errors are caused by the friction in a sliding pair and the inertia of the loads.