A Method for Improving the Precision of TLPMA Mover Position Detection

Abstract

This paper discusses a complex method for determining the position of the working unit of a tubular linear motor with permanent magnets, which has become very widespread in recent years. Unlike traditional electric drive systems that convert rotary motion into translational motion by means of intermediate mechanisms, direct linear drive systems are devoid of many of the significant disadvantages associated with mechanical transmissions. One serious scientific problem associated with this type of motor is the search for methods for accurately determining the current position of the working unit on the stator that are capable of operating under limited resources of typical microcontrollers, while providing sufficient positioning accuracy. This article proposes a method for determining the position of the working unit using several Hall sensors located on the stator with a shift of 60° (relative to the stator magnetic field), as well as inexpensive analog accelerometers (accelerometers). The proposed method is based on the use of large correction tables created during the calibration process for each stator instance, as well as the use of oversampling methods to increase the effective ADC bit depth. The use of the method made it possible to achieve positioning accuracy within 1 µm, without exceeding the computing resources of a typical microcontroller.