Application of the Stewart Platform in the High Speed High Accuracy Domain

迫切需要用于组装微电子和其他类似物体的小型、普遍适用、高速、高精度的组装机构。高速微位移器设计困难，制造成本高，而且很难维持在令人满意的工作状态。Stewart平台具有作为六自由度微位置器的应用潜力。它已成功应用于低速、低精度的应用场合。它提供了卓越的机械硬度，并且易于制造且成本效益高。关于Stewart平台作为高速、高精度制造或装配机器的应用还没有进行过研究。这一操作领域在质量动力学中产生了显著的非线性惯性项，这使得控制变得困难。本项目研究运动学综合技术，以解耦和线性化质量动力学。基于线性化的运动方程，建立了机构的状态变量模型。对高速、高精度运动的控制进行了仿真。该模拟反映了商业上可用的组件。研究了多余支腿对消除侧隙和提高稳定性的影响。斯图尔特平台还具有同时充当定位器和主动抵抗外部施加的振动载荷的潜力。这一点的可行性也在开发中。

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.