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Introduction

We are Group Antinomi. This hovercraft is built for the Summer 2014 Introduction to Engineering Competition. VG 100, Introduction to Engineering, is a main course for freshman in Joint Institute (JI), Shanghai Jiao Tong University. (Figure 1 and Figure 2 attached here are pictures taken on our campus.) VG100 asks students to build our own designs for two projects in a semester, and it aims to tell us how to cooperate with each other in a team.

There are two settled tracks for the hovercraft race. The competition consists of two parts, one is Time Trial (TT), which will test the time for running one lap, and the other one is Tournament, in which two groups compete at the same time running both tracks in two laps. Of course, the faster will win.

The requirement for the hovercraft in the competition is listed as the following [3].

  • Lifting Height: <2cm
  • Maximum: Mass 800g
  • Maximum Size: 30cm*30cm*30cm
  • Power Supply: Less than two batteries, each V ≤ 12V
  • Motor Specification: < 12 V
  • Central Control Circuit: Arduino Series
  • Remote Control: Mandatory

The attached Figure 3 is the concept diagram of our design.

We use Bluetooth connected to a Wii gamepad to control the direction. We build a skirt to introduce air flow under the hovercraft in order to reduce the friction force between the bottom of the hovercraft and the ground. For a faster speed, the thrusting power and lifting power are provided by two ducted fans. The attached Figure 4 is the assembled hovercraft built by our group. Our hovercraft ran 34 second for a lap in Time Trial and ranked Top 8 Team out of 19 teams in our section.

In this manual we attach a video of our hovercraft in Tournament Part of the competition.

Reference:

[1] Available: http://www.stutrip.com/schools/shanghaijiaotongda...

[2] Available: http://baike.sogou.com/v53009316.htm

[3] Available: Project 1 Regulation [PDF]. Available: Sakai. VG100_Shane_SU2014. http://202.120.46.147/access/content/group/80ea62...

Materials needed are shown in the image Material List, and their images are shown in Step 15: Appendix.

Step 1: Circuit Diagram

Step 2: Cut Acrylic Base (Main Board)

  • Use software AutoCad to draw the outlines needed to cut.
  • Cut Acrylic board by an automatic Acrylic laser cutter according to the outlines drawn. (You only need to upload your CAD file on the cutter, and it will cut your board according to your instructions.)

Images showing outlines drawn by CAD and the Acrylic base are attached.

NOTE: Determine the shape of your hovercraft while drawing the outlines. Circle is not preferred because a perfect round hovercraft can be hard to control (it tends to rotate around its axis). Small holes on the main board are for screws, so make sure they have proper sizes that screws can fit in (3mm in diameter recommended).

Step 3: Cut Fan Bolster and Rudder Components

  • Do similarly as is said in Step 2.

Images showing outlines drawn by CAD and the Fan Bolster and Rudder Components are attached.

NOTE: Bayonet joints on the components are for jointing each other together (see Steps 5 and 6), so make sure that they have proper width. Here in our case, width of 3mm is appropriate, because the Acrylic board we use here is 3mm. Small holes on the components are for screws.

Step 4: Make Cushion

    Cut polyfoam into a cushion that holds air inside with a polyfoam cutter (A knife is also accepted.)

    • A qualified cushion should
    1. Fit perfectly with the Acrylic base in its shape
    2. Have a hollow compartment to hold air inside
    3. Be perfectly smooth and flat underneath to let air out of the compartment evenly while pushed.

    Shape of a qualified cushion is shown in images.

    • Wrap the polyfoam cushion with ducted tape to make it perfectly smooth underneath (and also cooler). The ducted tape used is glutinous inside and would not be hard to wrap if cut into slices of proper shape and stuck onto the cushion slice by slice.

    NOTE: Do ensure the cushion is smooth and flat underneath because it determines whether your hovercraft can move smoothly and straightly.

    Step 5: Assemble the Rudder

    After laser cutting, we get components for our rudder. There are bayonet joints cut for the basic assembling work.

    • Plug the three rectangular boards to the horizontal rectangular base of the rudder. Remember not to shove the bayonet joint cut, because Acrylic board is crisp.
    • Carefully align the bayonet joints and plug the top holder of the rudder to the vertical components.
    • Fix the cross component (this is sold together with the servo) on the rotating axis of the servo. Make sure that while the servo rotates to the middle, the cross is an ‘X’, not a ‘+’.
    • Align the four screw holes on the rudder base with the holes on the cross component of the servo. Use four tapping screws (also sold with the servo) to joint the rudder and servo together.

    NOTE: The bayonet joints are strong enough to bear the air pressure during the competition. There is no need of screws to joint the components of the rudder.

    Step 6: Assemble the Holder to the Thrusting Duct Fan

    Similar to the previous step, here we have used Acrylic board laser cutting to make the bolster of the thrusting fan.

    • For one side of the bolster, assemble the two pieces of rectangular Acrylic board together with a small horizontal board, using screws to fix it.
    • Then repeat the previous sub-step once to make the other side of the holder.
    • For each side of the holder, use a plastic right angle stand to joint the end of the rectangular part made in the previous step and the top of the main board. Also, use screws to fix them.

    NOTE: The joint structure with the help of screws is strong enough for the speed during the competition.

    Step 7: Connect Duct Fan With Digital Electronic Governor

    In this step, we are going to setup Digital Electronic Governor on Duct Fan to control the rotational speed .

    • Carefully connect the red wire of Duct Fans to the red port and the black wire of Duct Fan to the black port on the digital electronic governors.
    • Initialize the digital electronic governor after the fans and the digital electronic governor are connected.

    Step 8: Fix Duct Fan on Base

    There are two duct fans to fix on the base in this step.

    First, fix the lifting duct fan.

    • Plug the duct fan up-side-down into the middle hole on the base board.
    • Use hot melt glue to seal the crack between the fan and the base on both side to prevent the lifting fan from escaping while working.

    Next, fix the thrusting duct fan.

    • Align screw holes at the bottom of the plastic right angle stands (fixed on the bolster of the thrusting fan in Step 6) to screw holes on the base board.
    • Screw in two screws for each right angle stand from the other side of the base board to fix the rudder with the base.

    Note: Do not reverse the order of fixing the two fans because reversing it takes you much longer.

    Step 9: Fix Rudder on Base

    • Screw out the four screws at the bottom of the servo.
    • Align screw holes at the bottom of the servo to screw holes on the base board.
    • Screw in the screws from the other side of the base board to fix the rudder with the base.
    • Cut two pieces of box like polyfoam with one side the same size as the side of the rudder.
    • Use double-side sponge tape to fix the polyfoam on the base next to the rudder in order to prevent it from sliding while rotating.

    NOTE: You do not need to open the bottom lid of the servo while screwing out the bottom screws unless you want to know what is inside.

    Step 10: Fix Base to Cushion

    Here in this step, we are going to assemble two main parts of our hovercraft together.

    • Carefully put the main board, which has already contained propulsion duct fan, rudder and other electrical components, onto the top of the cushion.
    • Use ducted tape, each piece less than 10cm, to bond the Acrylic board and the top of the cushion. Remember that in this step we need to seal the space to prevent air from escaping, thus introducing enough air for lifting power.
    • After the previous step, the hovercraft will be like a whole mechanism.

    Step 11: Fix Arduino Uno Board and USB Host Shield

    In this step, we are going to fix the controlling center, Arduino board to our hovercraft.

    • Insert USB host shield to appropriate port on the Arduino Uno board. Just aligning the hole and plugging shield to Uno will work.
    • Use double-side sponge tape to stick the bottom of the Arduino Uno board to the top of the holder. Double-side sponge can hold the controlling part tightly in case it drops during the running.

    Note: Only about 5cm long of double-side sponge tape is enough for holding the Arduino Uno board. Be careful when you use scissors!

    Step 12: Connecting the Circuit

    Connect the circuit as the circuit diagram shows

    Step 13: Upload the Program Into Arduino UNO

    Use Arduino IDE to upload the program

    Step 14: Control the Hovercraft With Wii Remote

    Left/Right Button: Left/Right full rudder
    Rotate Left/Right: Left/Right rudder
    Button A: Start/Stop floating
    Button 1: Half speed
    Button 2: Full speed
    Button +/-: Add/Decrease floating power
    Button HOME: Reset all

    Step 15: Appendix

    Images of material are shown here. Recall the material list in Intro.

    Material available here:

    1. Acrylic Board: http://item.taobao.com/item.htm?spm=2013.1.0.0.lIT...
    2. Ducted Tape: http://detail.tmall.com/item.htm?spm=a220m.1000858...
    3. Polyfoam: http://item.taobao.com/item.htm?spm=a230r.1.14.52....
    4. Servo: http://item.taobao.com/item.htm?spm=a230r.1.14.9.s...
    5. Double-side Sponge Tape: http://detail.tmall.com/item.htm?spm=a220m.1000858...
    6. Brushless Ducted Fan (55mm): http://item.taobao.com/item.htm?spm=a230r.1.14.8.c...
    7. Brushless Ducted Fan (35mm): http://item.taobao.com/item.htm?spm=a230r.1.14.1.w...
    8. Digital Electronic Governor: http://item.taobao.com/item.htm?spm=a230r.1.14.33....
    9. T-Plug Extension Cable Wire: http://detail.m.tmall.com/item.htm?id=25570180008&...
    10. T-Plug Parallel Connector: http://detail.tmall.com/item.htm?spm=a230r.1.14.1....
    11. Arduino USB Host Shield: http://item.taobao.com/item.htm?spm=a1z10.3.w1017-...
    12. Bluetooth Adaptor: http://detail.tmall.com/item.htm?spm=a230r.1.14.34...
    13. Wii Remote Plus: http://www.amazon.com/gp/product/B0094X28J0/ref=s9...
    14. Arduino Uno Board: http://store.arduino.cc/index.php?main_page=produc...
    15. Zinc-manganese Battery: http://chaoshi.detail.tmall.com/item.htm?&spm=a230...
    16. DuPont Wire: http://www.amazon.com/Dupont-Color-Jumper-2-54mm-A...
    17. Lithium Battery: http://detail.tmall.com/item.htm?spm=a230r.1.14.1....
    18. Lithium Battery Charger: http://detail.tmall.com/item.htm?spm=a230r.1.14.9....
    19. Battery Low Voltage Alarm: http://detail.tmall.com/item.htm?spm=a230r.1.14.1....
    20. Hot Melt Glue Gun: http://detail.tmall.com/item.htm?spm=a230r.1.14.1....
    21. Hot Melt Glue Stick: http://detail.tmall.com/item.htm?spm=a220o.1000855...
    22. Screw: http://detail.tmall.com/item.htm?spm=a230r.1.14.9....
    23. Wheelnut: http://detail.tmall.com/item.htm?spm=a1z10.3.w4011...
    24. Tool Kit: http://item.taobao.com/item.htm?spm=a230r.1.14.39....
    <p>Great photos and documentation!!</p>

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