Week 11 - September 19-25

Due to unforeseen illness, not much was able to be accomplished this week. However, two of the tasks assigned this week were completed.

Figure 11.1 is the new block diagram created this week. This block diagram strives to paint a clearer picture as to how each module interacts. The lines show physical connections, while the large arrows indicate wireless/Bluetooth connection. One thing to note: the rechargeable battery has line pointing to the outside block of each module. This means that every device within that module is being powered by the rechargeable battery. Though it is not shown, it is implied that there exists a charger with the battery.

Figure 11.1 - Block Diagram

The next task completed this week, was research pertaining to the drift that is often experienced when attempting autonomous drive. Most often seen in robotics applications, drift is when there is some amount of loss within the drive system of a robot. A real world example of this would be in a standard car. One would expect that if their car is driving straight along a flat, straight road that if they let go of the wheel the car would continue to move straight. However, this is not the case. Due to imperfections in the road ( gravel, cracks, divots in the pavement) if you let go of the wheel, the car will start to drift to one side. That's when you realize that your hand holding the wheel steady was the only reason that your car was driving forward in the first place. This same concept can be applied to robotics. Usually engineers need to implement some method of correction within their code to help an autonomous robot to compensate for drift.

With mechanum wheels being a special type of wheel it was unclear at first if we would need to worry about drift. Since this type of wheel creates a cross pressure towards the center of the cart it seemed like it might already compensate for any potential drift. This seems to kind of be the case. From the research conducted this week it seems that as long as the robot in question is driving on the same type of surface, then drift does not seem to be an issue. Some people did start to experience a problem with their robots drifting while strafing after the robot had been in use for a few months. This suggests that overtime, the wheels may need to have some alignments completed so that they can continue to work properly.

The team will conduct testing to verify that this is the case. We will also test the drive system on different surfaces to see how each surface affects drift. Unrelated to drift, the team plans to test the cart on varying inclines to see what, if any, the maximum incline would be for the Rover.