Main Robot - Day 1

Today we started building the robot that would navigate the final course. It consists of a front steering system (Figure 1) with rear wheel drive. The drivetrain consists of three engines, driving one single drive shaft (Figure 2) that gears into an open differential (Figure 3) which allows each wheel to spin independently for better turning.

Figure 1

Figure 2

Figure 3

Since the open differential is bad if the wheels start to slip (like on the sand) we might switch to a TORSEN differential system which has the good properties of an open differential (better turning) along with the fact that it is a completely mechanical system and transfers torque to the non-slipping wheel if one wheel starts slipping (property of a locking differential). The amount of torque transferred is a function of the torque bias ratio (TBR). A TBR of 3:1, for example, would mean that one side of the differential could handle 75% of the torque, while the other side only needed to handle 25% of the torque.

From wikipedia: "When the traction difference exceeds the TBR, the slower output side of the differential receives the tractive torque of the faster wheel multiplied by the TBR; any extra torque remaining from applied torque contributes to the angular acceleration of the faster output side of the differential."