Research Of Measuring And Monitoring System For Rotational Speed Based On Image Processing Technique

The measurement of engine speed was often involved in rotating machinery, and its accuracy and real-time performance were required. Speed detection and control were also accounted for a large proportion in the real-time control of industrial process. It has a critical influence on the stability of the system. Generator speed is an important sign to determine generator running condition. Traditional speed measurement methods include mechanical method, magnetic approach, vibration velocity measurement and photoelectric method. However, these methods are all based on microcontroller and sensors. So, the user interface is not friendly enough, and the tachymeter which using these measurements does not facilitate to communicate with the computer and also has restrictions on the number of computer communication port.Using the software methods, base upon digital image processing, A Non-contact method is put forward to measure the rotational speed, which uses the rectangular rotating markers, its color is very different from background color, and an USB camera is used to capture the sign image. By this technique, for obtaining the average speed, only its two adjacent frames captured when it is in uniform rotation are needed. The rotation angle is calculated by detecting the vector slope angle.And the precision of rotation angle measurement directly impacts on the precision of rotation speed. Therefore, give priority to the method of rotation speed measurement in this paper. To measure rotation angle, we studied the relationship of rotate objects in the spatial coordinates and then established speed measurement model. The measurement of small angle using modern science and technology is not a problem, but this is based on sophisticated mechanical structures and these angles are no directional. USB camera and personal computer were used to image capturing and processing in this paper. Vector method is used to strike a rotation angle between the two frames, it will be possible to achieve measure the angle intelligently because the mechanical structure is not needed and also it can reduce the mistakes generated by man-made operations. It will be applied with a broad application prospects as long as the scene illumination conditions is provided.VC++6.0 is used to complete the image capturing, processing, feature vector extraction, data analysis and output. The efficiency and scalability is promoted. It's applicable to ordinary computer measurement and control.The errors using traditional contact method caused by mechanical abrasion, slipping and vibration are avoided using this non-contact method in this paper. This non-contact method can be applied to the accurate measurement of rotational speed and angle measurement in the field of Electronic testing and industrial control, it has the advantages of no polluting, no invasive. With the development of CCD technology, the impact of such constraints will become increasingly smaller. The accurate measurement results will be got between 1200r/m to 1500r/m. The experiments show that the method can be used to measure the rotational speed with reasonable accuracy. Besides, it has more advantageous in anti-jamming ability, high performance-price ratio and simple system structure.