PROBLEM TO BE SOLVED: To perform comprehensive travel along an irregular ground by using a driving system having comparatively low output.SOLUTION: A control part controls a drive part as follows: after advancing as long as a first distance, a shell is retreated as long as the first distance and a second distance along a first route, moved to a second position determined by advancing as long as the second distance along the first route from a retreated first position, and by advancing as long as a third distance in a direction orthogonal to the first route, and then advanced as long as the first distance along a second route parallel to the first route from the second position.SELECTED DRAWING: Figure 9COPYRIGHT: (C)2017,JPO&INPIT【課題】不整地の網羅的な走行を比較的低出力の駆動系を用いて可能とする。【解決手段】制御部は、胴体を、第1の距離を前進した後、第1の経路に沿って第1の距離および第2の距離を後退し、後退した第1の位置から、第2の距離を第1の経路に沿って進み且つ第1の経路と直角の方向に第3の距離だけ進んだ場合の第2の位置まで移動させ、第2の位置から、第1の経路と平行な第2の経路に沿って第1の距離を前進させるように駆動部を制御する。【選択図】図9