Improved Reel Mechanism to Wind a Cable Uniformly in Spherical Trailer

Cabled communication is considered to be more useful than wireless communication for rescue robots used in post-disaster environments. The cable can not only provide good signal communication but also contribute to assist to retrieve the robot. However, at the same time, the cable could hinder the mobility of the robot. Additionally, robots for inspection usually lack in payload capacity and have no space for reel mechanisms, because they are generally small. Therefore, we have developed a spherical-trailer-type cable reel mechanism, which is composed of a spherical trailer and a cable reel mechanism with a device to oscillate the cable to the reel. Through experiments and studies, we have identified a problem on the oscillating device that the cable wouldn´t be winded uniformly to the reel. We proposed two kinds of improved method to wind the cable uniformly to the reel. They are structural shape optimizations of spatial cams. This paper describes the cable reel mechanism, improved mechanisms, and experiments to test their performances.