| At present, most tilt sensors have the shortcomings of instable performance, low degree of visualization and so on. So an omni-directional tilt sensor (ODTS) based on machine vision is designed and realized in view of automatic, objective, non-contacting characteristics of machine vision system. The ODTS that combines machine vision with tilt measurements can get tilt angle and tilt directional angle of measurement plane in real time and it is applied to the embedded platform successfully. Above all, it has advantages such as real-time and reliability, high visualization, high detection accuracy, etc. Tilt sensor is usually applied to the platform leveling system, so the ODTS is applied to the vehicular radar hydraulic leveling control system in this paper. The six-leg supporting platform based on the model of cylindrical and the highest point leveling control algorithm are proposed. The matlab simulation results show that the leveling algorithm can effectively avoid the occurrence of false legs and the leveling time is short relatively.In this paper, the main researches include the followings:(1) The compositions and advantages of machine vision system are analyzed. By applying the machine vision to tilt angle and tilt directional measurement of plane, the design thought of the ODTS is proposed.(2) The hardware configurations and the function of each composition are introduced. It is concluded that the performance evaluation of the ODTS depends on measurement accuracy and measurement speed by analyzing of the performance evaluation indexes of vision measurement system.(3) By analyzing the different shape of the mercury region in the image when the measurement plane is horizontal or tilt, the detection algorithm and calculation formulae of the tilt angle and tilt directional angle are proposed in this paper. The algorithm called area algorithm is proposed to overcome the shortcoming of low detection efficiency using the existing algorithm. The area algorithm measures the tilt angle by analyzing the area relationship of the mercury region and the translucent region of the image in the tilt state. The experimental results show that the new algorithm improves significantly in the measurement speed.(4) The static characteristics of the ODTS including range, sensitivity, and precision are analyzed. The mathematical model of step response of the second-order system is used to obtain the dynamic characteristics and transfer function of the ODTS.(5) By the analysis of experimental error, the method of least squares polynomial curve fitting is applied to compensate the error of measurement tilt angle and improve the measurement accuracy. By the research of different fitting effects under the different orders of polynomial, the order of polynomial is determined successfully.(6) The video image is captured by the interface of V412. By analyzing the memory distribution of YUV422—the image format captured by the camera, the format conversion from YUV422to RGB is realized. Finally the detection algorithms of the tilt angle and tilt directional angle are applied to the embedded platform and the measurement results are displayed on LCD real-timely.(7) The compositions of hydraulic leveling control system are introducedo The transfer function of each composition and the closed-loop transfer function of leveling control system are determined. The six-leg supporting platform based on the model of cylindrical is proposed. And the highest point leveling control algorithm proposed in this paper is applied to the vehicular radar hydraulic leveling control system. The matlab simulation results show that the leveling algorithm can effectively avoid the occurrence of false legs and the leveling time is short relatively.The experimental results show the ODTS proposed in this paper can measure the tilt angle and tilt directional angle real-timely, and it has the wide application prospects. |
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