Application of Parallel Link Manipulators in the High Speed, High Accuracy Domain

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This research focuses on the feasibility of using parallel link manipulators for high speed, high precision six axis positioning applications such as mirror pointing, surface finishing, machining, and robotic manipulation. A first phase research effort has successfully demonstrated that the Stewart Platform type of parallel link manipulator is feasible and has significant advantages over conventional serial link mechanisms. The current phase of research, comprising seven tasks, addresses the building of a prototype machine tool for finishing operations on aircraft turbine engine blades. The first research task evaluates the benefits of the "moving bearing point" platform design and determines whether it or the conventional platform concept should be adopted for further study. The "moving bearing point" design is one in which the actuator supplying force does not move as the platform moves. Task two involves building a functioning machine capable of performing the operations required for jet engine blade finishing. Task three calls for implementing the feedforward controller developed in the first phase of research. Task four focuses on experimentally measuring system performance and optimizing the controller design. Task five activity will test the system developed in the previous tasks and assess its ability to perform the finishing operations on aircraft turbine engine blades. Task six extends the system testing to other types of parts. Task seven examines another platform modification which involves the use of piezoelectric elements to achieve high precision, high frequency motion. The intent is to follow up phase two work with a phase three effort oriented toward producing commercial versions of the system developed in phase two. The impact of this work will be on the machine tool industry where innovative concepts which can reduce costs and improve quality are clearly needed.