An automatic riveting method for robots based on the improved EDCircles algorithm

Because of many advantages, such as single-sided riveting and no welding, blind rivet nuts are widely used to fasten various metal sheets and pipes. However, fixing the blind rivet nut to the base material is mainly accomplished by manual riveting and robot riveting based on teaching-playback. In order to realize automatic riveting without teaching, this paper proposes a robot automatic riveting method based on machine vision. Firstly, with the help of the light source that increases the difference between the foreground and the background, a binarization method based on morphology is designed to remove lots of useless information in the image. Then, an improved EDCircles algorithm based on the geometric properties of circular arcs is proposed to detect circles in the binary image, which also realizes the detection of the head circles of the nut. Finally, in order to obtain the precise position of the nut, an optimization method for the inner circle of the nut is designed. Experimental results show that this method has a high nut detection rate, good positioning accuracy and efficiency, which indicates that it can be used in practical applications.