Characteristics of piezoelectric locomotive mechanism for an in-pipe micro inspection machine

The characteristics of a new piezoelectric linear step locomotive mechanism for an in-pipe micro inspection machine are described. The micro inspection machine, with diameter of 5.5 mm and weight of 1 g, moves in not only straight but curved pipes. The micro inspection machine is composed of mainly four units; a shell-body which is made of thin plated metal of 60 /spl mu/m thickness, two eddy current sensors which detect the micro cracks of the in-pipe wall, a locomotive mechanism and a radiator. The locomotive mechanism is composed of three parts; three clamping members which elastically contact the pipe wall to hold the weight of the micro inspection machine and one stacked PZT actuator and a mass block. The walking speed of 10 mm/sec was obtained from the driving experiment in a pipe 8 mm in diameter. The relationship between the moving speed and the driving frequency was analyzed.