Control and guidance of a pipe inspection crawler (PIC)

Abstract

Inspection robots are used in many fields of industry. One application is monitoring the inside of the pipes and channels, recognizing and solving problems through the interior of pipes or channels. This ability is necessary especially when one should inspect an underground pipe. In addition, many sensors are used on these robots to improve the quality of inspection, such as vision and nondestructive testing apparatuses. In this work, an inspection robot (PIC) with ability to move inside horizontal and vertical pipes has been designed and manufactured in robotic and automation laboratory of Tarbiat Modares University. Furthermore, different units are installed on this robot, and their functions are examined. Control and guidance of robot in the pipes or channels are discussed. Experiments are arranged to evaluate the mobility of the robot passing through vertical and elbowed pipes. The robot consists of a two DOF camera for monitoring and an ultrasonic unit for measuring the pipe wall thickness. The ultrasonic probe can tough the interior of the pipe in different angle as operator wish. Moreover, the robot outer diameter can be varied and adapted to the pipe inside, to regulate the contact pressure needed between the robot and the pipe. All are being controlled by the operator through a joystick while receiving the video signal of the camera on a monitor. The control system hardware is a microcontroller based with PWM output and A/D converter. The applied forced by the robot are tuned by measuring the current of the motors consume. In addition, the position and velocity of motors are measured by encoders.