Final Notes

It has been a long semester, with many trials and tribulations for Hamsterbot. This post wraps up the ideas and goals I had for Hamsterbot, and the choices made along the way.

Approach
The general approach to building Hamsterbot came in a few steps.

The first step was getting mouse movement to control the movement of Hamsterbot. The approach used was to take the distance the mouse moved in short periods of time and translate that into motion. The location of the mouse could be found through Python functions, and the cursor could be reset to the center of the screen through available Windows interfaces. One choice made at this stage was to translate change in y as translational velocity and change in x as angular velocity. It is not clear if this is the optimal way to compute movement(in fact it seems unlikely), but it was a straightforward approxmation which behaves normally for most types of movement.

The second step was how to capture the movement of the hamster ball. This was done by placing an optical mouse directly under the ball, which would then record the movement of the ball. This was a very easy solution, and it worked perfectly, except for the issues brought up by the next step.

A large issue with this was the amount of friction it caused on the hamster ball. In fact, the friction was so great that there was no hope of a hamster actually being able to rotate the ball, when situated on Hamsterbot. An excellent future solution to this problem (given sufficient supplies) would be mounting the hamster ball on a ring of ball bearings, with the mouse below this setup. Then the mouse could still easily be used to track the ball, while the ball would be able to freely rotate thanks to the bearings.

The final issue was the smoothing of Hamsterbot's motion. This consisted mainly of the jerking starting and stopping, as well as Hamsterbot's penchant for ramming into walls at full speed. The jerking was fixed by taking the average of Hamsterbot's current velocity and the velocity read from the ball, resulting in less extreme acceleration in general. This also put an end to immediate stops, replacing them with gradual deceleration. The speed issue was fixed by putting an upper and lower bound on Hamsterbot's speed. This ensured that all ball movement actually moved the robot, as well as preventing excessive speeding (and hamster injuries).

Final Comments
The Hamsterbot project was a wonderful learning experience, and a lot of fun. If I had another try, or if I were to continue on with the project, there are a few areas I'd focus my effort on.

I would have loved to install some ball bearings and actually get a hamster controlling Hamsterbot. This was one shortcoming which was dissapointing, if only because the solution is just a few appropriate parts away. Additionally, there remain some "interesting" behaviors that emerge in Hamsterbot that are not present in the simulation, which I'd be interested to determine the source of.

Overall, working on a robot like this was an amazing learning experience. The chance to integrate many of the ideas we discussed in class into a single, unified system was a great challenge, and proved very rewarding. It truly has been a pleasure.