Development of Rough Terrain Mobile Robot Using Connected Crawler -Derivation of Sub-optimal Number of Crawler Stages

Abstract

The application fields of autonomous mobile robots recently extend from indoor uses to outdoor uses. Rescue systems and planetary explorations are typical examples for such outdoor mobile robots. In such field, it is required to have both of rapid movement and adaptive function to rough terrain, while general wheel mechanisms are not suitable for such rough environments. To move in these environments, the robots need to be flexible to various environments. There are many researches concerning rough terrain mobile robots for rescue and planetary exploration. In such field, the robots require high mobile ability on rough terrain. When we design such kinds of robot, it become very important to choose the mechanism as a mobile platform. Several types of mechanisms have been proposed as a mobile platform: Crawler type, wheel type, leg type, and their combinations. Wheel type mechanism is the simplest mechanism and can be controlled easily, but in terms of moving on rough terrains, its performance is obviously inferior to the other two mechanisms. If we adopt wheel type and try to get enough mobility on slight obstacles, we have to utilize pretty large wheels. The leg mechanism is able to adapt various kinds of environment, but, its weak points are low energy efficiency and complicated mechanism and control, that imply high cost and product liability problems. Those might be high barrier to develop them as a consumer product. The crawler mechanism shows the high mobile ability on various terrains; moreover it is simple mechanism and easy to control. Therefore a lot of rough terrain mobile robots adopt a crawler mechanism. However conventional single track mechanism has also mobility limitations; the limitation is determined by attacking angle, radius of sprockets, and length of crawler. In order to