| This project aims to investigate and propose several motion-control methodologies, so that a fast and high precision linear motion down to submicron level can be achieved. Under this goal, a high precision position encoder based on laser interferometric method, a resolution increasing circuit with the fusion algorithm for encoder improvement, and a prototype of high precision linear motion system based on a permanent magnet linear motor haves been developed.;This project develops a high precision low cost linear motion sensor based on the optical interferometer with a 3×3 fiber coupler. The simulation results and the experimental measurements from a prototype linear motion sensor have demonstrated that a successful linear motion sensing system with low cost, long measurement range, and high accuracy can be achieved by using the novel optical interferometric method.;Optical linear incremental encoder is widely employed in high precision linear motion control because of its high accuracy characteristic. However, the maximum measurement speed of this incremental encoder is usually limited by the clock frequency boundary in the decoder circuitry. The speed limitation of linear incremental encoder has been overcome by developing a novel enhancement circuit. This circuit is responsible for improving the measurement speed of the encoder. The velocity information from the optical linear incremental encoder and the velocity output of the novel circuit are combined by the data fusion algorithm, so that an accurate position sensing system with higher measurement speed range can be developed. The feasibility of the idea is verified by experiments.;Developing a high precision linear motion system with a direct-drive linear motor is a difficult task because this motion system usually suffers from many non-linear characteristics, such as friction, ripple-force, variation of parameter. A high precision motion control algorithm with a modified disturbance compensator and the internal model reference control is proposed and implemented. Satisfactory experimental results have been obtained. The proposed controller is capable of achieving high speed and high accuracy (with position error less than 0.1μm). The response speed to the position command and the external disturbance is much faster when modified disturbance compensator is adopted. |
