OpenCV-based PID control line following vehicle with object recognition and reaction

Line following is one of the most efficient and reliable techniques for mobile robots in indoor environments. Line-following robots can autonomously detect and follow designed paths. It is now commonly applied in transportation and assistance. In related research, ensuring success in complex line following tracks (right angles, sharp curves) and complex optical environments has been a challenge. This paper designs a line following vehicle is designed based on a microcontroller (Raspberry Pi), Pi camera, and image processing by OpenCV. The image processing in line following includes the application of RGB, GRAY, and HSV color models. The vehicle movement is controlled by the PID algorithm. Besides, this system incorporates a template matching module. The template matching module uses binarization, polygon approximation, perspective transformation, Gaussian blur, and similarity comparison. The designed vehicle can complete the line following a designed map and successfully matches the correct templates. A discussion on the effect of light reflection is presented in this paper. This effect is improved by an extra algorithm in line following and expending the threshold of binarization. Also, this paper solves the problem that the vehicle may run out of the track in line following. The experiment shows a satisfying result. This study has potential implications for the design of line-following robots.