In this paper, a soft landing control method for a vehicle robot with an inverted two-wheeled/stable traveling mode is proposed. The conventional two-wheeled vehicles have advantages such as the capability of pivot turn compared to the vehicle robots with three or four wheels. On the other hand, the two-wheeled vehicles have disadvantages such as static instability and deterioration of the translational velocity control and inverted-pendulum control due to mutual interference. Therefore, to realize a vehicle robot having the advantages of both two-wheeled vehicles and stable traveling vehicle, this paper introduces a variable compliance control for the pitch angle direction. The variable compliance control enables the soft and stable transition between a two-wheeled mode and a stable traveling mode. By the proposed method, a soft landing and stable inverted traveling motions at the transition from two-wheel mode to stable traveling mode are realized. The proposed method makes it possible to take advantage of both inverted two-wheeled vehicles and stable traveling vehicles.

This paper discusses surface roughening treatment of permalloy material 45 using Na₂SO₄-electrolyzed oxidizing water (hereinafter it is referred to as Na₂SO₄ EO water) with ultrasonic. Firstly, roughening treatment experiment on polished surface of permalloy material 45, using Na₂SO₄ EO water and H₂SO₄ solution with ultrasonic, was carried out. The results showed that when using H₂SO₄ solution, the surface of the permalloy material 45 couldn't be uniformly roughened, while when using Na₂SO₄ EO water, it could be uniformly roughened. Secondly, experiment on the relationship between the time elapsed from the creation of Na₂SO₄ EO water and roughening performance was carried out. The results showed that if the time elapsed from the creation of Na₂SO₄ EO water was within 1 week, the polished surface which had not been done heat treatment can be uniformly roughened, which the polished surface which had already been done heat treatment couldn't be uniformly roughened. Thirdly, in order to elucidate the mechanism of roughening treatment, experiment on characteristic change of Na₂SO₄ EO water and its etching action on permalloy material 45 when using ultrasonic was carried out. The results showed when irradiating ultrasonic, the dissolved oxygen concentration of Na₂SO₄ EO water became higher and the etching action also became stronger. By this study, we received the suggestion that Na₂SO₄ EO water could be applied to the surface roughening treatment of permalloy material 45.