Contributions to the modeling of the incremental optical encoder and speed estimation methods for motion control
No Thumbnail Available
University College Cork
This work studies the incremental optical encoder sensor and its impact on motor motion. The small-signal model of the sensor combined with the chosen speed estimation method is derived, experimentally validated and compared with existing models. A novel experimental setup emulates the encoder behaviour. Therefore, the sensor is isolated from the rest of the system (motor and driver) that unavoidably biases the dynamic study. The small-signal model demonstrates that the phase lag of the encoder increases as the speed and the resolution decreases. This increment of the delay adversely reduces the phase margin of the motion control-loop. In addition, a simple lead compensator is proposed and implemented on a DSP to recover correct performance of the motor (smooth rotation) previously degraded by the encoder. The coefficients of the proposed lead compensator adapt to the specific commanded speed automatically. As part of this thesis an improvement of the elapsed time (ET) method, that expands the use of this method to all speed ranges, is proposed. The Improved-ET speed estimation method has a good balance between static error and dynamic behaviour.
Small-signal modeling , Incremental optical encoder , Speed estimation methods , Motion control
Vazquez-Gutierrez, Y. 2019. Contributions to the modeling of the incremental optical encoder and speed estimation methods for motion control. PhD Thesis, University College Cork.