The development of an in-pipe microrobot applying the motion of an earthworm

An in-pipe microrobot, which was developed by modelling the walking motion of an earthworm, is described in this paper. The robot is composed of three locomotive units; a unit corresponds to a segment of an earthworm and is composed of two metal plates connected with a flexible microactuator (FMA) and four linkages with a projection. The robot moves the linkages as the legs and walks when the FMAs are actuated by the air pressure. The maximum walking speed, 2.2 mm/sec, and the maximum traction load, 0.22 N, were obtained from the driving experiments in a pipe 20 mm in diameter. The walking speed was also theoretically analyzed by taking account of the delay of shrinking of FMA, and the results agreed well with the measured values