Stator-free RPM Sensor With Wireless Communication--A Study Of Design And Implementation

In modern industrial monitoring and measuring systems for rotating machineries, Revolutions Per Minute (RPM) of rotating body is one of the most critical and important physical quantities. RPM sensors play an important role in a wide range of application fields. This thesis presents an analysis for stator-free RPM sensor with wireless communication based on Micro Electro Mechanical Systems (MEMS) accelerometers. In comparison to all other existing sensors that are based on two coupled parts: stator and rotor, such as conventional electro-magnetic RPM sensors and photo-electric RPM sensors, this new stator-free sensing principle has the advantage of flexible installation and robustness and reliability.This thesis first focuses on the operating principle design of the stator-free RPM sensor, and the general-purpose error modeling method of accelerometer and the stator-free RPM sensor which was implemented in Matlab. The hardware and software design were respectively conducted in Pads and AVR32 Studio 2.0. Besides the stator-free RPM sensor, a general-purpose embedded microcontroller platform with wireless communication based on AVR32 is also discussed. Sensor calibration is described, and a reference laser RPM sensor with higher precision was also designed and implemented for the calibration purpose.The innovation of this thesis: Firstly, the general-purpose error modeling method of accelerometer which was implemented in Matlab was proposed. Secondly, the stator-free RPM sensing principle was designed and implemented in prototype.Real environment experiment has been conducted to further verify and strength the arguments put forward in the analysis. Experimental results presented in this thesis show the system features and the precision and noise level of RPM readings in different rotating speed. One most interesting property of this sensor is that it gives higher accuracy for higher RPM. The conclusions present suitable improvement methods in the future.