This research work contributes to an active vision system for an gas pipe inspection robot moving inside of the pipe. The robot must be able to know what shape of the pipes where the robot is moving. The shapes of the pipe include straight, L or T. Also, when it is moving in the straight section, the robot must detect the relative angle with respect to its principal axis. The authors propose to use a laser spot array and TV camera for the vision sensor, which can find the three dimensional position of each spot on the surface of the pipe by means of triangulation. The shape of the pipe inside can be reconstructed by the information of the camera. A method is also presented to distinguish the shape whether it is straight or not.

This paper describes a new mechanism, communication system, and vision system of an internal pipe inspection robot. To date, inspection robots have had such limitations as their ability to turn in a T-shaped pipe or move in a plug valve. The new mechanism based on our dual magnetic wheels, resembling a crawler, not only overcomes the limitation but enables the robot to climb over sharp obstacles like sleeve and dresser joints. Another drawback of earlier robots is that the friction between the pipe and the cables for communication and power supply makes it difficult to move a long distance. A fiber optic communication system can reduce the friction. The new vision system has been significantly miniaturized, enabling it to clearly view and inspect the welded section underneath the robot while gazing ahead for navigation. An experimental inspection robot has been successfully made to confirm the efficiency of the approach.

This paper describes an efficient algorithm of path planning for an internal gas pipe inspection robot. Since the purpose of this robot is to move in pipes to detect injures and scratches, the path should cover all pipes in a given map. The problem to find a path along which the robot can investigate all pipes at least so that the total distance is minimum is called 'Chinese Postman Problem'. Usually this problem is NP-complete. If all values of pipes are non-negative, the numerical programming is applied for finding the optimal path. However this is still too complicated to apply for searching the path. Motivated by this motivation, a method to find the optimal path based on the A* algorithm is proposed, which is treated more easily than the numerical programming. Finally some numerical simulation results are presented.