Abstract
Abstract This six-DOFs Motion Measurement Device (MMD) utilizes the Linapod parallel mechanism. It consists of three main parts: a slide and rail assembly, a lower plate and six connecting rods with fixed length. The slide and rail assembly contains six parallel rails surrounding and jointed to the spindle housing. Each rail has its own optical linear encoder with the scale attached to the back side of the rail and the read head mounted on the slide. The lower plate has six ball joints built into it. Through the connecting rods, each ball joint on the lower plate is connected to another one on a slide of the rail assembly, thus completing the Linapod parallel mechanism. Whenever there’s relative motion between the rail assembly and the lower plate, the rods cause the slides to move. The motions of the slides are measured by the read heads. With the read heads monitoring and feeding back the positions of the slides, the six-DOF relationship between the rail assembly and the lower plate can be solved through forward kinematic transformation. This thesis is based on the six-DOFs Motion Measurement Device Linapod parallel mechanism, and the aim is to enhance the accuracy and reliability of the MMD device with two approaches: the improvement of component design and the usage of new calibration equipment. The improved of component design aims to make this Linapod parallel mechanism more stable when subjected to temperature change or vibration. The newly designed calibration equipment allows more accurate identification of kinematic parameters. This thesis also applies this Linapod parallel mechanism onto a three axis machine tool, to close the kinematic chain from the tool to the work piece, the sensor for the detecting of the six-DOF relationship between tool and work piece. With such a device as feedback sensor for the, parts are machined and inspected to validate the accuracy improvement.