Sensor fusion for linear motors, an approach for low-cost measurements
Bas J. de Kruif, B. van Wermeskerken, Theo J.A. de Vries, Maarten J. Korsten · University of Twente Research Information · 2002
A new measurement setup for a linear motor is investigated. It is custom to use an optical ruler as a measurement device for a linear motor. The high position measurement accuracy that is obtained with this ruler, is required to get an accurate estimate of the velocity to be used in the velocity feedback loop. The accuracy is not required for the position feedback loop. An optical ruler is an expensive measurement device and because the accuracy is higher than needed for the position measurement, it could be advantageous to use a cheaper sensory system to measure the position and to use auxiliary sensors to get a good estimate of the velocity. The permanent magnets that are inherently present in a synchronous PM motor can be used as a coding such that no external ruler is necessary. Hall sensors are used to measure the magnetic eld of these magnets and determine the position based on this magnetic eld. The velocity estimate derived from this measurement does not meet the specications and therefore an acceleration sensor is added. The acceleration sensor in combination with the position sensors estimate the velocity with an accuracy that meets the specications for a considerably smaller price than the optical ruler. 1