Introduction: Naval Battle: a Robot Car Grabbing Balls to the Territory


Hello everyone, we are team scavenger (22) from UM-SJTU Joint Institute in this VG100 Fall term. JI is founded by Shanghai Jiao Tong University (SJTU) and the University of Michigan (UM) in 2006. Now it is an international academy in Min Hang District, Shanghai, China.

One of our favorite pictures are the lab in 428 in the JI building. One can find almost everything in this lab, such as the electric drill, the screws and so on. What a good place to do experiments!

The project one in VG100 is called the naval battle. It cultivates our knowledge of how a robot can be created. Every team should design their robot car to grab the eight ping pong balls and four wooden balls to the opposite cite. Within three minutes, a team should try their best to move as many balls as they can to score a high mark.

Our score on Game Day isn’t very good as our battery meets with some problems before the game. We only scored five points and didn’t enter the tournament.

picture 1 group logo picture 2 our robot car picture 3 group members picture 4 JI building picture 5 vg100 lab

Step 1: Step1: Competition Regulations

The field is a 2000mm*1500mm which is divided into two parts with a board which is 70mm in height and 18mm in width to separate. The ping pang ball has a diameter of 40mm and the wooden ball has a diameter of 70mm. Moreover, the middle wall doesn’t touch the ground and is 50mm above it so the ping pang ball can go under the wall while the wooden ball can’t. So, team should try other ways to get the big ball to the other side of the field.

All robots should have a size within 350mm*350mm and the limit height of 200mm while the robots can be changeable with only one condition at the beginning that meets the rule.

Picture 1 the size of the field Picture 2 detailed picture of the wall

Picture 3 whole field Picture 4 real picture

In the first 3-minute round, a big ball counts as 4 points and a small ball counts as 1 point. If the big ball gets out of the field, the team will lose 5 points while the small ball with a loss of 2 point.

The top eight highest score team in the first round can take part in the second round. In the second round, every two teams of the eight teams will play with each other. The match is 3 minutes. At the end of 3 minutes, team with the higher points win the game. If two sides’ points are equal, then the team which has more big balls win. If the number of big balls still equals, there will be one extra minute.

Picture 5 Competitive Part
Time Trials Video Website

Step 2: Step2: Concept Diagram

The centre controller is our Arduino Mega2560. We use PS2 to send infrared ray to the PS2 receiver, then the receiver gives signal current to the Arduino Mega so that the motors and the servo motors can move.

The motors are powered by 12V lithium battery and driven by L298N. Then L298N is linked to Arduino to receive control and power. Once we use PS2 to give signals to the Arduino, then L298N can result in the change speed of the wheels so that the car can go straight or turn right and left.

The servo motors are given electricity extrenally for the voltage of them are much higher than arduino can supply.However, the rotation of them are controlled by Arduino. If we touch the buttom on PS2 once, then the servo motor can change a certain angles to let the balls go across the board.

The special thing about our car is that we have a box in the back of our car. We can use our robot arm to put the big balls in it and then hold to the ground to make the car lean to let the balls go down to the other side.

Step 3: Step3: Materials List

Tools required:

1.Screwdriver 2. Nipper pliers 3. Electric drill 4. Saw 5. Scotch tape 6. Hot melt glue 7. Electric soldering iron 8. Scissors 9. Black tape 10. 502 glue

Materials list:

1.robot arm


3.servo motor

4.arduino mega


6.battery for Arduino

7. battery 12V

8.acrylic board


10.adapter lines




The materials' prices and hyperlinks are recorded in the excel.

Step 4: Step4: Circuit Diagram

Motors are controlled by L298N and the L298N is linked to Arduino and powered by 12V battery (not drawn in the circuit)

Every digital servo has three lines, one signal line is connected to Arduino’s digital output, one firing line is connected to RC battery, one ground is both connected to RC battery and Arduino’s GND

Arduino is powered by dry batteries, remember don’t use high voltage battery in case Arduino is broken

PS2 isn’t drawn in the picture for there are too many lines, all ps2 controller’s lines are connected to arduino

Step 5: Step5: Component Fabrication

buy the components of the robot arm from Taobao

use screwdriver and nipper pliers to combine sever motors, frames and all components together

use the saw to cut the acrylic board into several rectangles

use the hot melt glue to connect rectangles together

one is a basket to hold big balls one is a baffle to move small balls

cut one 20cm*25cm acrylic board for the base

drill four holes of 4mm diameter on both right corners of the base

drill two holes of 4mm diameter in the front of the base

drill six holes of 3mm diameter in the center of the base for the arm

Step 6: Step6: Assembly

(1)move all the materials together

(2)use screws and nuts to attach the motors to the base

(3)put all the electronic components on the base as the floor figure

(4)connect the electric lines of the motors to the L298N

(5)connect the firing lines and ground electrodes of three servo motors to the RC battery

(6)connect the PS2 receiver to the Arduino mega

(7)connect all the signal lines and ground electrodes of the servo motors (electrodes both attached to battery and Arduino) to the mega 2560

(8)give the power to the Arduino

(9)use screws and nuts to fix the robot arm and the base together

(10)use hot melt glue to attach the basket and baffle to the head and the end of the car (not shown in the picture)

Step 7: Step7: Problems We Meet

1.The voltage of the battery is low so it can't give enough power to the servo motors. Then when the servo motors catch the big balls, it can't get the balls above the board. In this situation, you should charge your batteries or change a new battery which fits your servo motor.

2.Arduino has its own linited voltage like 5V. When you give power above 5V, the arduino may stop work if it has protection pattern or it may be broken down.

3.Since PS2 is connected to the controller by infrared ray, when there have many PS2s in the lab, the signals may be mixed. So you should find a place quiet to test your robot car.

Step 8: Step8: Final System View

For more information, you can send e-mails to

Expect you to have fun playing this robot car!