Introduction: Bug Tower Defense

We are Team HUAJI, from the UM-SJTU Joint Institute (JI) and this was a project made for our VG100 course. The JI was established between Shanghai Jiao Tong University and the University of Michigan in 2006. The university is located in the Minhang district of Shanghai, China, with one of the best engineer professors and instructors in the world. The bug tower defense was the first project of VG100 and it aimed to develop our group working skills and served as an introduction to engineering.

The Bug Tower Defense is a competition composed of two main sections- the tower and the bug (robotic car). The aim of the game is to kill the bugs in the shortest period of time with a laser that is placed on the top of the tower. The laser is programmed with an arduino to scan the light sensors on the bugs in order to kill them. The bugs are also designed and tested by every group.

Below are the competition regulations:


- 2.5m long

- Shelter area to prevent the bugs from getting killed in the 2-2.5m section away from the tower

- White line in the middle of the track paralleled to both sides of the path

- White line before the tower vertical to the sides of the path


- Must include a vertical board (15cm*10cm) in the front of the bug

- Light sensor must be placed in the center of the vertical board 5 cm above the ground

- Must stop when killed (scanned by laser)

- Must travel in a straight line

- Must stop for 2-4s on the white line placed before the tower and can not be killed when stopped for this duration

- Speed in range of 0.2-0.3m/s


- Made of regular A4 sized paper (80g) and white wood glue

- Maximum 3 sheets of paper stacked allowed anywhere on the tower

- Electric components must be placed on top the tower except for sensors (allowed at the bottom if necessary)

- No other materials are allowed to support the tower other than paper

- Must be at least 60cm tall

- Needs to be able to kill the bugs by turning the laser to any angle

Step 1: Prepare Materials

Step 2: Concept Diagrams

Figure 1.1 and 1.2 are concept diagrams for the bug and tower.

Step 3: Circuit Diagram for Bug

Figure 2.1 shows the circuit diagram for the bug.

Step 4: Component Fabrication for Bug

  1. Cut the acrylic board into a 15cm*20cm rectangle as the base (Board A)
  2. Cut another acrylic board into a 10cm*15cm rectangle as the front (Board B)
  3. Drill holes with 3mm diameter 1.5cm apart from each other straight along the sides of board A 5mm away the 20cm edge and 1cm away the 15cm edge (figure 3.1) (for easy adjustment in the future)

Step 5: Assembly for Bug

  1. Solder a wire on both the positive and the negative end of the motor for both motors (figure 4.1)
  2. Connect both wheels with the motors and fix with screws (figure 4.2)
  3. Slide the motors into the motor holders and screw them into two of the holes at the end of board A with screws and screw caps (figure 4.3) (make sure the two wheels are parallel)
  4. For the following steps stick the components with double-sided tape
  5. Stick the arduino UNO on top of Board A 9cm from the front of the bug and 2.5cm from the left side of the bug (figure 4.4) (the side with the wheels is the back of the bug)
  6. Stick the breadboard on top of Board A 9cm from the front of the bug and 3cm from the right side of the bug (figure 4.5)
  7. Stick the driver board on top of Board A 3cm from the back of the bug and 5cm from the right side of the bug (figure 4.6)
  8. Stick the battery on top of Board A 3cm from the front of the bug and 5cm from the right side of the bug (figure 4.7)
  9. Stick the two turning wheels on the bottom of board A opposite the motor-wheels 3cm from the front of the bug and both 5cm from the sides of the bug (figure 4.8) (make sure the wheels are parallel)
  10. Stick the board B vertically against board A with double-sided tape (15cm side against 15cm side)
  11. Stick the tracing sensors on the bottom of board A two at the center 2cm apart and one at the very left end (at the end with the vertical board and with the sensors sticking outwards)
  12. Stick the light sensor at the centre of board B pointing in front of the bug (figure 4.9)
  13. Connect all components to the arduino UNO with wires (hold wires in place with sticky tape)

Step 6: Circuit Diagram for Tower

Figure 5.1 shows the circuit diagram for the tower.

Step 7: Paper Folding for Tower

  1. Draw three vertical lines 6.8cm apart from each other and the long edge of the paper (figure 6.1) (should end up having three even rectangles and another very thin rectangle with 7mm width)
  2. Fold the paper from step 1 along each line in the same direcion
  3. Brush the smallest rectangle with glue and stick it closely to the edge of the furthest rectangle (figure 6.2) (should end up with an equilateral triangle prism and make sure the side with glue is on the inside layer)
  4. Repeat steps 1 to 3 eleven more times (end up with 12 triangle prisms)
  5. Fold a paper from the shorter edge in a zig-zag every 1cm (figure 6.3)
  6. Glue a piece of paper on both sides of the wave-like paper from step 5 (figure 6.4) (don't use too much glue, only brush some against the pointy ends of the wave-like paper)
  7. Repeat steps 5 to 6 twice more
  8. Cut a paper into a strip with 10.5cm width (figure 6.5)
  9. Fold the paper into a hexagonal prism with 6.8cm sides and glue into shape (figure 6.6, 6.7) (use the remaining part for gluing)
  10. Repeat step 9 three more times
  11. Roll a paper vertically into a cylinder with 6cm diameter and glue into shape
  12. Repeat step 11 three more times
  13. Glue the short sides of two pieces of paper together by 5mm (figure 6.8) (should end up with a paper with length around 70cm)
  14. Cut the paper from step 13 into a strip with width 10.5cm (figure 6.8)
  15. Glue the strip from step 14 into a cylinder (figure 6.9)
  16. Cut paper into hexagon with 7.3cm sides and cut out small triangles 5mm deep at every edge (figure 6.10)

Step 8: Assembly for Tower

  1. Place 6 of the triangle prisms together into a hexagonal prism (figure 7.1)
  2. Hold the triangle prisms in place with the hexagon strip (figure 7.2) (make sure the hexagonal prism is tight by adjusting the size of the strip)
  3. Stick the hexagon paper on both ends of the hexagonal prism (figure 7.3)
  4. Repeat steps 1 to 3
  5. Stick the two hexagonal prisms together end to end (figure 7.4)
  6. Stick two of the wave paper onto the bottom of the tower from step 5 as the base and one wave paper on the top of the tower as the stand (figure 7.5) (make sure the tower is at the center of the A4 paper)
  7. Stick the 4 paper cylinders around the bottom of the tower on the base from step 6 and make sure the cylinders are making contact with the tower (figure 7.6) (the cylinders need to be even spread into the 4 corners of the tower)
  8. Wrap the four cylinders together with the paper strip (make sure they are tight together by adjusting the size of the strip)
  9. Connect arduino UNO with the extension board (figure 7.7)
  10. Stick the laser pointer on top of the step motor with sticky tape (make sure the laser is straight and in the center of the step motor)
  11. Stick the step motor on top of the extension board from step 10 with double sided tape
  12. Stick the arduino UNO from step 11 to top of the tower with sticky tape
  13. Connect wires to the 4 motion sensors (make sure the wires are long enough to stretch from the extension board to the bottom of the tower)
  14. Stick the 4 motion sensors onto the paper strip on the bottom of the tower between the cylinders on all 4 directions with sticky tape (make sure the motion sensors are all at the center between the cylinders and at the same height with each other)
  15. Connect wires from all components to the extension board Stick the battery on the top of the tower closely next to the arduino UNO with sticky tape
  16. Stick the battery on the top of the tower closely next to the arduino UNO with sticky tape

  17. Trim the wave paper on the top of the tower to the shape of the tower (figure 7.8) (make sure all components are not hanging out of the paper)

Step 9: Final View and Video

Below is a link to a video of the Bug Tower Defense. Enjoy!