NSF Award
8760911
A critical need exists for small, universally applicable, high speed, high accuracy assembly mechanisms for assembly of microelectronics and other similar objects. High speed micropositioners are difficult to design, expensive to build, and difficult to maintain in satisfactory working order. The Stewart platform has potential for application as a six degree of freedom micropositioner. It has been successfully applied in low speed, low accuracy applications. It provides exceptional mechanical stiffness and is easy and cost effective to manufacture. No research has been done in the application of the Stewart platform as a high speed, high accuracy manufacturing or assembly machine. This realm of operation develops significant nonlinear inertial terms in the mass dynamics, which render control difficult. This project examines kinematic synthesis techniques to decouple and linearize the mass dynamics. A state variable model of the mechanism is being developed which is based upon the linearized equations of motion. Control is simulated for high speed, high accuracy motion. The simulation reflects commercially available components. The influence of extra, redundant legs in eliminating backlash and enhancing stability are also studied. The Stewart platform also has potential to simultaneously act as a positioner and actively reject externally applied vibration loads. The feasibility of this is also being developed.
