We are RELIVE from UM-Shanghai Jiao Tong University Joint Institute, numbered group 14 in this semester’s VG100. We are writing this page to introduce our first project—a Warzone Tower Defense.

Shanghai Jiao Tong University (SJTU) is one of the prestigious universities in Shanghai and our Joint Institute is an energetic and creative institute in SJTU. Vg100 is a special course focusing on cultivating students’ basic knowledges and skills in engineering, which is peculiar to JI. We are taught how to think, act and communicate in an engineering way. Students learn to cooperate, innovate, and propose about their own projects.

There are five members in our group with different characters. Our group features high efficiency and timely assignment distribution. We have a great passion for exploring the principles of operation rather than just ask for what to do. Another important feature of our group is that we are the most environmentally friendly group in this game since we use many materials that are recycled, saving energy and resources.

For this semester, we were required to do the project Warzone Defense Tower and have a game with the other groups. In this project, we had to build both a robotic car (serve as a bug) and a paper defense tower. The warzone defense tower has to obey certain rules and is graded according to our performance on the game day. We did quite a great job in building the bug (the car) and got a good mark for it but it was a pity that we made a buff on the game day due to the breakdown of one electronic component. But we are still satisfied with our general performance.

The following introductions can instruct you to finish a similar project as the tower defense. Enjoy your engineering process!

Here is a brief introduction of the game rules.

Rules for the bug:

1. Place a light sensor in the front of the car.

2. Go straight along the path.

3. Stop at a white line for 2-4 seconds.

4. Stop once the light sensor is irradiated in the race area except the white line.

5. Maintain a speed at 0.2-0.3m/s.

6. Stop before reaching the “wall” next to the edge of the tower.

Rules for the tower:

1. Build the bearing structure only with printed paper (A4 80g).

2. Stick no more than 3 layers of paper together.

3. Build the tower at least 60cm in height.

4. Put all electronic components on the top of the tower.

5. Stick with only white wood glue.

Rules for the game:

1. Three rounds in the game.

2. Bugs coming from any three of the four direction of the tower.

3. Five minutes’ adjustment between the rounds.

4. No touching the bug during the game.

And now we get starting!

Step 1: Design Concept

the graphs shown above are concept diagrams of our design.

the bug:

The core of the “bug” (intelligent car) is an Arduino Uno micro-controller. We compile some codes into the Arduino so that the “bug” can react to operations.

There’s a light sensor on the front shelter of the “bug”, which can receive light intensity and return corresponding data to the Arduino. After processing the data, the “bug” may stop or keep going.

Notice that there are three color sensors attached to the “bug” using infrared ray to recognize “white” and “black”. The single one on the right is used to detect two white lines near the midpoint of the path and at the end of the path. The two sensors in the middle detect the straight white line through the whole path so that the “bug” can keep going straight.

Two motors provide driving force to the bug. They are directly controlled by one single motor driver to have the same rate. Two couplers are used to connect the wheels with motors.

The video link: http://v.youku.com/v_show/id_XMTc3NzIwMjg4OA==.ht...

the tower:

The tower is made of printed paper. We made many triangular prisms to build it since triangle is the firmest structure.

The servos at the top of the tower control the laser to point at different directions. The one at the bottom rotates as a parallel plane to the ground while the upper one rotates as a vertical plane to the ground.

Step 2: Material Lists

The pictures shown above will show you the material lists and quantities, purchasing source and prize.The first 2 pictures are for the bug and the latter 2 are for the tower.

Step 3: Designing Circuit Diagram

For the bug:

1. All the red wires in the picture are fire wires and black wires are ground wires.

2. Bread board: connect the 5V port and ground port to the bread board to provide energy for the sensors.

3. Tracking sensors (TCRT5000): connect their fire wires & ground wires with the bread board to gain energy, and connect their signal wires (white wires) to the Arduino to output the signal.

4. Light sensor (BH1750FVI): the same as the tracking sensors.

5. Driving board (L298N): connect the signal wires (white wires) on the right side to the Arduino, and signal wires on the upside and the bottom to the motors to control the speed and direction of the motors (PS: do not forget to connect its ground wire back to the Arduino to make it a closed circuit.).

6. Battery: connect its fire wires & ground wires to the driving board to provide energy for it.

For the tower:

1. All the red wires in the picture are fire wires, black wires are ground wires and orange wires are signal wires.

2. Bread board: connect the 5V port and ground port to the bread board to provide energy for the sensors.

3. Ultrasonic sensors (HC-SR04): connect their fire wires & ground wires with the bread board to gain energy, and connect their signal wires to the Arduino to output the signal.

4. Steering engine (SG90): connect their fire wires & ground wires with the bread board to gain energy, and connect their signal wires to the Arduino to control their direction and speed.

the first picture is for the bug and the second one is for the tower.

Step 4: Build the Bug Step by Step

A) assembling the bug

1. Fix two motors with motor two brackets on the base, fix them with four screws and hubs .

2. Fix the tire on the motor with 502 glue.

3. Plug the caster in the hole .

4. Adjust the caster towards the front and fix it on the bottom with formed tape, then we have our base board.

5. Fix the Arduino Uno and L298N on the base with form tape.

6. Fix the VC battery and bread board in the back of the base with tape. Place the bread board on the battery .

7. Fix the front board with binder clip .

8. Connect all the parts together with wires .

9. Get the VC battery charged and input the program.

Now we have our bug!

B) Constructing the front board.

1. Cut a 15cm*10cm PVC board as the front board.

2. Clamp the board with binder clip.

3. Cut two 1.5cm*1.5cm rectangle PVC chip and a 3cm*1.5cm rectangle PVC bar, then glue it to make a light barrier.

4. Stick the light sensor on the binder clip with 502 .

5. Stick two tracking sensor right below the binder clip and stick the last one at the right side of the front board edge.

C) Soldering the circuit and connecting

1. Solder the light sensor to four wires (refer to step3).

Notice: the connect circuit sometimes get loose, use tape to fix them if necessary.

Step 5: Build the Tower Step by Step

The main method is to do many triangle structures to support the body.

1. Divide one piece of A4 sized paper into 4 parts.

2. Fold 2 times and glue the left part and right part together, then you will get a triangle pattern.

3. Make 4 triangles that are the same sized, then glue them together with white wood glue into a bigger triangle structure .

4. Glue 4 bigger triangle structure into an even bigger one, then one of the layers of the tower is done .There are total 4*4=16 triangles used.

Then make a similar triangle again but smaller size (depend on your personal design) .

5. Glue another piece of paper to the both sides of the triangles and then these 2 parts together vertically.

6. Stick the triangles together. Wrap all of the triangles to get larger contact face between.

7. Make a small platform using 3 layers of paper together to support the mechanical part and glue it on the very top of the tower.

Now you will have an entire tower .

The steps shown below will tell you where and how to put all the materials.

The electrical part:

A) Connecting the circuits:

1. Solder the 5v wire and ground wire port of Arduino to the bread board to provide energy for devices.

1. Solder the ultrasonic sensor's signal wires to the Arduino and energy wire to bread board.

2. Repeat (2) for three times.

4. Solder the cloud terrace's signal wire to the Arduino and energy wire to bread board.

B) Assemble:

1. Attach the ultrasonic senor to the bottom of the tower (about 6.5 cm high to the ground).

1. Repeat (1) for three times, make sure that bugs on every track can be detected.

2. Place all the devices (except ultrasonic senor) on the top of the tower.

3. Attach the laser on the cloud terrace.

4. To close the circuit, connect the laser and the Arduino with the battery.

Step 6: ​Attention and Trouble Shooting


1. Attach pins to correct holes of Arduino

2. Classify wires of different function using different colors

3. Put wires in order

4. Pay attention to component breakdown

5. Fix components tightly especially wires

6. Insure battery power

7. Distribute electricity reasonable

8. Keep ultrasonic sensors vertical to the ground


1. T: The tracking senor doesn’t work.

S: Insure the power of the batteries. Sensors doesn’t work if battery power is too low.

2. T: The motor is short out.

S: Solder the wires carefully.

3. T: When sticking the triangles to make the tower, it’ hard to keep the platform parallel to the ground smooth.

S: It cannot be avoided. Sometimes it can be smoother without sticking the triangles together.

4. T: The bug can’t go straight.

S: Fix the tires. Don’t let them shake when motors are running.

5. T: Returning data of sensors are obviously wrong.

S: Tie up wires tightly to avoid inducted current.

<p>Good luck in the competition :)</p>

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