Analysis and Test on Step Surmounting Performance of a W-shaped Track Robot

The step surmounting performance of a mobile robot is an important performance measure for obstaclenavigation. In this paper, a W-shaped track robot is taken as a research object and the step-climbing performance is analyzed theoretically. It is simulated by the RecurDyn software and is tested on a terrain simulation platform using a NDI dynamic measuring machine. In the independent step climbing process, the robot's front track sections of W-shaped track climb up the nosing of the step firstly and then the rear ones climb. Once the robot's position of center of gravity climbs over the nosing, the robot will climb up easily. According to different riser heights and positions of center of gravity, there are two situations for the climb of the rear tracks: (1) if the gravity center has been over the nosing when the rear tracks touch the nosing, then the robot’s rear tracks will climb the steps softly without any impact; (2) and if not, then the robot's front tracks will rise and, then fall causing an impact. It is very easy for the robot to climb the step with a slope because of the guiding role of the slope. The robot can easily climb up the steps which are less than 240mm high, and the maximum tested step height is 320mm, but there should be a lower step in front of the step, and the robot's gravity center should be adjusted to a very low and forward position. In short, the W-shaped track mobile robot has a good performance for the overcoming of structured terrains.