Improved method for precise shaft angle oscillation and angular velocity measurement (with simultaneous sampling of other analog signals using NI DAQ Cards)

This paper deals with the possibilities of simultaneous sampling of analog data acquired by sigma/delta converters (used on NI DSA cards) and the ways of synchronization with angular velocity and position values measured by IRC sensors. In the past, a measurement system with two 8 channel DSA cards was developed. This system has provided to be reliable. However, the accuracy of the shaft angle measurements was to be found of lower accuracy, but still considered adequate for the purpose of induction motor fault diagnostics. The angular position is measured with the use of an IRC sensor, where the actual absolute angle is sampled synchronously with all other channels with sampling frequency in the order of tens of kilosamples per second. During more advanced experiments, the currently used method had shown limitations (lower resolution, problems with velocity calculation). To solve this problem, a new improved method, based on a combination of commonly known angular position and velocity measurement, is proposed. The performance is evaluated by simulations. Some common methods for precise measurements of angular velocity and angular speed oscillations are briefly described, along with their advantages and disadvantages. The simulation results of the proposed method are compared with the method currently used. The possible implementation of the proposed new measurement method with the use of the existing hardware is discussed.