We are G20, a team made up of freshmen from the University of Michigan-Shanghai Jiao Tong University Joint Institute (Figure1 and 3) . Our goal is to make a robot, which can carry balls over the battlefield in the game “Naval Battle”.The UM-SJTU Joint Institute (JI) was jointly established by Shanghai Jiao Tong University and the University of Michigan in 2006 (Figure 2) . It is located in Shanghai, China. The goal of this partnership is to build a world-class teaching and research institute in China for nurturing innovative leaders with global visions.
Step 1: Details About the Competition
Our sweeping car is designed for a unique course named VG100 offered in the joint institute. This course is aimed at teaching us to find out problems and solve them by ourselves as engineers. Every group consists of five members. We are required to buy components and make a car within five weeks. Our game day is in the sixth week. Our goal is to win the game.
Some basic racing rules are listed as follows:
①The game ground is divided into two parts, and the size of each part is 150cmm×100cm. There is a 7cm board in the middle and a 5cm gap between the ground and the board.
②There are eight small balls and four big balls on either of the side. Small balls are the same as those used for table tennis; big balls are wooden balls, the diameter of which is 7cm.
③To win the game, a team should throw or push all the balls to the other side of the ground. A team is also allowed to throw or push balls of the opposite side back to their side.
④The car should not be bigger than 35cm*35cm*20cm.
Step 2: Materials List
Step 3: General Concept
Our general concept of the design is to squeeze big balls over the wall using the curved aluminum board. The car is controlled by Arduino Uno and powered by model ship battery. A combination of gear motor and driver board L298N is used to drive the car. We control the car by Sony PS2. This concept is relatively easy for green hands, as it bears no mechanical arms or anything complex.
The base of the car is specially designed so that it is lower in the front, which makes it more convenient for us to fix the aluminum board. Also, we tried many times to find a suitable camber for the aluminum board—it is like a quadrant, but a little longer on the top. Otherwise, wooden balls would easily get stuck between the wall and the aluminum board. We fixed angle irons on the aluminum board to catch the balls which are at the corner of the field.
The car’s working principle decides that it must have enough momentum when pushing balls. Because of this， our programmer lets motors run at the highest speed; also, we purchased thin acrylic board and aluminum board to make the car lighter. All these guaranteed, the car, taped aluminuman, is of high flexibility while moving.
See Figure 6, 7 and 8 for reference.
Step 4: Designing Circuits and Programming
The circuit diagram above shows how PS2 is connected to Arduino (Figure 9-10).
The programming is also shown above. (Figure 11—see the original picture for high definition code)
Step 5: Constructing the Base
We used AutoCAD to draw the sketch of the base (Figure 12). The rough size is 25cm*20cm and details are marked on the picture above. Afterwards, we cut it out with laser cutting machine.
The curve in the front is designed to better fit the aluminum board. The holes at the back are for screws; small holes at the front corner are for minor adjustment when fixing the aluminum board, which means, not all of them will be used. Generally, nylon cable ties are quite useful and as strong as screws.
Step 6: Connecting Components
①connect the driver board to Arduino board (Figure 13)
②connect the Arduino board to the signal projector (Figure 14)
③connect the gear motor to the OutputA on Arduino board (Figure 15)
④connect the driver board to the model ship battery (Figure 16)
Step 7: Assembling
Due to our simple design, taped aluminuman is quite easy to assemble!
1.Fix angle irons for motors on the baseboard with nylon cable ties each side. Connect the motors to the angle irons with screws.
2.Connect the motors with the coupling and wheels and fix them with screws. Fix omni-directional wheels on the front corner. (Figure 17)
3.Fix the aluminium plate and the metal supporter to the baseboard with nylon cable ties and screws. (Figure 18 and 19)
4.Fix four screws on each side of the aluminium plate. ( Figure 20)
5.Fix the driver board, Arduino board, model ship battery, acceptor on the baseboard with tapes. (Figure 21)
Step 8: Debugging
In the first design, when the balls are in the corner of the battle field, our car fails to get the ball onto it. So we widened the aluminium plate and solved the problem.
Step 9: Final System View
Step 10: Game Day
Step 11: Conclusion
The robot, taped aluminuman, managed to push half of the balls over the wall and ranked 10th on the game day. At first, a wire accidentally fell off and made us waste some of the gaming time, which is quite unexpected, and we failed to find the cause of this incident in three minutes. Even so, the robot still showed its great performance with a motor off.
The main problem, poor contact, was caused by our negligence. Simply wrapping the wire terminal in tape would solve the problem, but we overlooked these details. Additionally, the wires were in a mess, which partly led to our inefficiency while looking for the root of the problem during gaming time.
However, regardless of these problems, other groups spoke highly of our robot. The operating principle is simple, the cost is extremely low, and the robot can deal with balls at the corner perfectly. We are still proud of our design, and we have learnt a lot from the exciting game.
Step 12: Appendix
Video links to each round on the game day