EE/CS118 Final Project 2002

Conclusions

View of the EE118 Final Competition, from above.

Our robot performed very well at the final competition. We were pleased with the results and felt that all of the time and energy we had put into constructing "The Assaulted" was well worth it. Below we describe everything that went right and wrong during the design and construction process, as well as a few bits of wisdom for future students of the class.

• What went right
• What went wrong
• Bits of Wisdom

What went right

We attributed most of our robot's success to the simplification of its design, as mentioned in the Introduction section. In particular, we felt that the following were most important to our robot performing as well as it did:

• Continuous Shooting: One thing we noticed about the other robots in the competition was that they were not able to shoot all of the balls that they were able to hold in the 2 minute period. By shooting continuously, we were able to unload all of our balls, putting us at a significant advantage (since even with a low shooting percentage, we still had a good chance of making as many baskets as the other robots...this is known as the "Casey Jacobsen shooting principle").

• Tailoring our robot for the field: By doing this we were able to minimize the movement of our robot around the field, giving us more time to shoot. We never had to worry about whether or not we were oriented in the right position when shooting as we had constructed our robot in such a way that we could not be oriented in an incorrect position (assuming that we found the center correctly during the initial stage of turning).

• Lack of movement: Because we were only required to move our shooting turret, we were able to line up for each shot in a very small amount of time. This allowed us to use "Kishan's Theorem" to continuously shoot without worrying about whether or not we were ready to shoot (as mentioned above). Additionally, using the rotating turret scheme allowed us to have hard stops so that we did not have to worry about aligning the entire robot with the correct basket before shooting each ball.

What went wrong

Happily, we did not have any serious problems with our robot on the night of the competition. However, during the construction process we did run into a few snags, as described below:

• Failing Sensors: Our sensors did not work as we wanted them to and we ended up spending several hours trying to debug our sensor circuits before finally scrapping our original implementation and moving on to a new design. Even after we implemented our new design, we still did not get the performance we would have liked. However, we figured that it would be easier to work with circuits that were "mostly right" and compensate for them in software, since software behavior is more deterministic than analog circuitry.

• Grounding Issues: We initially had several problems with how we were connecting the grounds of our high current devices (ie. motors and solenoids) with those of our low current devices (ie. sensors and digital circuitry). We ultimately determined that sharing grounds was a bad idea as it lead to noise being shared by our sensors and actuators, resulting in unexplainable behavior (ie. things got jeepered).

• Purchasing of materials: We ended up purchasing many more components than we actually needed during the construction process, and, as a result, we ended up spending more than we would have liked to on this project. We did not have a clear idea of what kinds of parts we needed (especially when it came to the motors and solenoids) until we began to put the project together. We wasted a little bit of money as a result.

Bits of Wisdom

We feel that it would be helpful for future students of the class to know the following lil' bits of information before starting on their final projects:

• Using the Machine Shop: It is extremely important to reserve spots on the machines (especially the laser cam and the mills) long before you plan on using them (ie. 4-5 days). Otherwise you will find yourself standing in line to use the machines all day long, and never getting to actually use them. Sign ups are available online. Additionally, if you have friends in the class who are members of other teams, try to coordinate using the laser cam at the same time as they are so that you can split the cost of the machine shop fees ($10 a day).

• Design Philosophy: It is best to keep everything simple. Try to optimize the robot's performance at a very specific task (ie. shooting balls from only one location on the playing field, and not at any location on the playing field).

• Software Maintenance: We only had one team member work on and maintain the software. As a result, we never had any of the software maintenance/sharing issues that many of the other groups had. While it may not necessarily be the best idea to have only one person working on the software, it is important to devise some scheme so that redundant code does not get added and important code does not get deleted.