Study on accurate positioning method and its visual measurement technology of cantilever roadheader underground

In order to solve posture measurement problem of Boom-type Roadheader under low illumination and high dust underground environment in coal mine,this paper put forward a accurate positioning measurement method using camera which acquire image data included features of laser points and laser beam. Based on monocular vision positioning principle of three line,an explosion-proof industrial camera was used to acquire tunnel images and process according to the feature of laser. Combining the advantage of Hough transform and least squares method,the characteristics of points and beams of two laser alignment which amounted on Boom-type Roadheader was extracted,then body posture was calculated through space matrix transformation space. It is found that the combination of Hough transform and least square method can effectively eliminate the isolated points in the complex background such as stray light,dust and water mist,and improve the detection accuracy of laser point and laser line. In order to verify the effectiveness of the proposed method,the pose measurement experiments were carried out on a laboratory cantilever tunneling machine test platform and a coal mine underground industrial site. Laboratory experiments showed that combining the Hough transform and the least squares method for feature extraction to obtain the fuselage position error within 20 mm,the attitude error is within 0.3°,the error meets the accuracy requirements and is smaller than the pose obtained by using the traditional Hough transform for feature extraction；the industrial test underground in coal mine shows that the measurement error of the fuselage is within 40 mm,which meets the requirement of roadway driving accuracy.