all about mobile robots
|The first autonomous sumo robot that I've designed was four wheel differential drive robot. This robot was mainly built from scratch in my free time.
Steering mechanism - Differential drive system
Differential steering system is commonly used in mobile robotics. It relies on the velocity difference between the right and left pairs of wheels. If the right and left DC motors turn in the same direction at the same speed, the robot moves forward or backward. As shown in Fig. 1 in case of speed difference between them, the robot is steering in the direction of the slower driving wheels. This system allows a robot to pivot in its place when right and left wheels turn with the same speed, but in the opposite directions.
Fig. 1. The chosen moving possibilities for differential steering system.In sumo robot competition there are three key tasks. The first one is to scan the surface to detect white line at the ring edge. The second is opponent detection and finally the last one is to push him out of the ring. The first task is typically accomplished by infrared reflective sensors. In this design I used 4 TCRT1000 infrared sensors placed at the corners of robot platform as shown in Fig. 2. Four Sharp GP2D12 distance measuring sensors are used to detect the opponent (Fig. 3.)
Fig. 2. White line sensor - reflective optical sensor with transistor output
Fig. 3. Distance measuring sensor - GP2D12 Sharp