Laser Cut MultiWii Based Quadcopter

This is the second version of a small quad copter that I designed and built. It is designed so that the only power tool required to build it is a laser cutter.

You can get multicopter frames for cheap from a number of sources, but I wanted something that was more customizable and hackable. The cost to build the actual frame by itself for this quad (including glue, etc) is only about $50. The rest of the costs are probably similar to what it would cost to build a quadcopter using a commercially available frame kit. I also believe it to be more sturdy and easier/cheaper to repair than a lot of quad frames on the market. While learning to fly with version 1 of this quad, I crashed it repeatedly, several times into a tree. After several hard crashes I did break one of the motor mounts, but a little bit of wood glue and some clamps and it worked as good as new.

While I think this makes a fine first quadcopter for people (it was essentially my first), having some knowledge of building and flying RC  vehicles will help. I've tried to be thorough in both documenting the build as well as providing sources for the materials and parts.

Let me know if you have any questions, problems or suggestions.

Step 1: Materials and Tools

Parts:

Qty   Description                                                                
4 -   Brushless motors  =   $9.26x4
4 -  10A speed controls  =   $9.42x4
1 -  13" Black 14AWG silicon jacketed wire (INTL SHIPPING)  =   $1.19    
1 -  13" Red 14AWG silicon jacketed wire (INTL SHIPPING)    =  $1.19    
20 -Male and Female 2mm bullet connectors  =  $2.57x2 
1 -  3-cell 2200mAh battery (May want to buy spares) = $17.17     
2 -  8x4.5 props (May want to buy more spares) = $2.42     
2 -  8x4.5 right hand props (May want to buy more spares) =   $2.42     
Bag -O-rings or prop savers McMaster.com Item 9452K26 =    $3.13    
1 -  Multiwii control board (INTL SHIPPING)  =$49.99     
20- 1-64x0.25" sockethead screws McMaster.com Item# 92196A459 =   $6.22    
20- 1-64 nuts McMaster.com Item# 91841A038  = $8.10
100 -~4" long, 0.1" wide zip ties. Hardware store or McMaster item# 71295K62 =   $2.20
20 - ~6" long, 0.14" wide zip ties. Hardware store or Mcmaster item# 71295K63=    $3.33
2 -  Battery hold down straps =    $1.75x2
1 -  30”x24”x1/8” (3.1mm) baltic birch plywood  Rockler.com item 23490 = $9.99
1 - Bluetooth serial adapter (Optional but recommended)(INTL SHIPPING) =  $7.49
2 - Male and female XT60  Battery connectors  =  $3.29
1 - 2.4GHz Reciever (6 chan min, 8-9 chan prefered)  = $20.16
1 - NEO-6M GPS Module     = $21.99
1 - LiPo Battery charger = $44.99
1 - Battery Charging Sack =   $2.30
1 - 2.4GHz Transmitter (6 chan min, 8-9 chan prefered)  = $67.30
1oz- Super thin CA (1-3sec) or Hobby store  =  $4.79
2oz - Gap filling CA (15sec) or  Hobby store  =  $7.99
2oz - CA accelerator or Hobby store =  $4.79
2 -High contrast spray paints (2 colors) Hobby or Hardware store =~$2 x 2
1 -Masking or painters tape Hardware Store =~$3
1 -5"x3"x1/4" Latex Rubber foam sheet (must be open cell)  Hobby Store =~$4
1-Shrink tubing assortment - Hardware store  =~$2 x 2
1- JWT crimp on connector set(Optional) (INTL SHIPPING) =  $1.43

Tools
-Laser cutter (40-60W)
-Various clamps (small spring clamps, c-clamp)
-Thick scrap plastic or wood (3/8-1/2” thick, approx 2x 4” square)
-soldering iron and solder
-allen wrenches
-needle nose pliers
-Multimeter with cont. tester
-micro USB cable.
-Computer
-Android phone (optional)
-USB Bluetooth dongle (Optional)
-Servo connector crimping tool (Optional)   ($12.93)

The total is approximately $405 (+shipping) including all optional parts noted. while the primary source for parts is HobbyKing.com (both their USA and International warehouses) and they usually have decent prices I haven't done anything else to optimize the cost. It is possible that if you shop around and/or already have a lot hobby type stuff you will be able to reduce the cost significantly. For instance somebody who already does RC planes, helicopters, and/or cars as a hobby may already have a suitable battery charger and radio which would  reduce the estimated cost by $117 (~29%).

Step 2: Cutting Out the Frame

1. Cut out the QuadFrame.dxf from 3.1mm (~1/8”) Baltic Birch plywood. Note the file is scaled in millimeters because that is what my laser cutter accepts. You should be able to cut 2 full frames from a 30”x24” sheet of wood. I get this plywood locally from a wood working chain of stores called Rockler where they sell it as ⅛”. You can order it online from rockler as well. I have bought 4 sheets from them and 3 of the sheets were the same thickness, but one of them was approximately 0.3mm thinner. For that reason I think it would be best to find the plywood locally and measure the thickness before buying. The design can probably handle +/- 0.1mm without too many problems but to much more than that and it will probably make it very difficult to build. On my import 60W laser cutter I cut at 85 percent power and 25 for the speed which is more power/slower than needed, but your settings will vary. Make test cuts first.

Step 3: Assembling Frame

2. After you have all the pieces cut out, assemble the 2 arm assemblies as shown and use tape to hold them together. Don’t glue anything yet.

    Note: Pay attention to the orientation comments shown in the pictures.

Step 4: Assembling the Frame (cont.)

3. Put the top and bottom pieces on. Use scrap wood or plastic and clamps to hold them on tightly. Alternately you can make a more effective clamp by drilling holes your scrap wood/plastic and putting a long bolt through the scrap plastic pieces and the center hole in the frame as shown. Don’t over tighten you clamp, but you want to make sure it is tight enough to keep the arm pieces in alignment.

Step 5: Assembling the Frame (cont.)

4. With center of the frame clamped, use a couple small spring clamps near a leg piece and glue the leg to the arm sides as shown. Use the super thin CA first, then come back through with the gap filling CA and put fillets along each seam. You can use CA accelerator to harden the gap filling CA faster and keep it from running out of place. Avoid getting glue into the 4  small slots in the legs. If you get glue in those slots it will be much easier to blow it out while it is still wet, than to chip it out after it is hard.  Repeat this step for each of the other 3 legs.

Step 6: Assembling the Frame (cont.)

5. Next clamp and glue each of the stiffeners (the pieces with the ovals cut out) using the super thin and gap filling CA like you did for the legs. Again avoid getting glue in the small slots. It maybe be necessary to reposition or remove your tape at this point.

Step 7: Assembling the Frame (cont.)

6. Lastly use the same method of clamping and gluing to glue each of the motor mounts into place.

Step 8: Assembling the Frame (cont.)

7. Remove the clamp from the center of the frame and remove the the bottom piece. Verify that the top piece is fully pressed onto the arms and the bottom of each arm is flush with the bottom of the other arm where they cross, you may want to use small spring clamps to help with that.  Glue the seams where the arms slot together with super thin CA followed by the gap filling CA. Next glue all the seams where the top piece meets the arms.

Step 9: Assembling the Frame (cont.)

8. Install the battery straps in the bottom piece as shown.  It will be easier now before gluing the bottom piece in than it will be to fish them through later.

Step 10: Assembling the Frame (cont.)

9. Now re-install the bottom piece and glue all the seams where it meets the arms like we glued everything else. You can use the frame clamp we used earlier to help clamp the bottom piece on, except just use the washer without the scrap plastic piece on the bottom so that it doesn't crush the battery strap and we still have room to glue.

Step 11: Assembling the Frame (cont.)

10. Next, assemble the electronics shelf on the top piece as shown without gluing anything yet. Pay close attention to the alignment of the pieces. Install the diagonal cross piece as shown. When the pieces are installed correctly you actually have a choice of installing the cross piece 2 different ways which gives you more flexibility later. In the pictures I actually made a mistake and can only install the cross piece one way, not that it really matters too much. It is very important that both the cross piece and the top piece don’t get glued into place. They need to be removable. When all the pieces of the electronics shelf are installed correctly, go ahead and glue the shelf to the rest of the quad (remembering not to glue the top piece or cross piece).

Step 12: Painting the Frame

11. Now the frame is complete and ready to give it a high contrast, two color paint job. This is an optional but highly recommended step. When you are flying the quad it is very hard to tell which direction is forward unless you have painted it with two different colors. I happened to have orange and blue spray paint so that is what I used. You can choose any 2 colors you want, but the more different they look the better. 
12. First with the cross piece installed in the electronics shelf, use a marker or pencil to put an arrow on it pointing towards the end of the cross piece with the slot cut out of it as shown. That will be the front of the quad. It will be pointing in between two of the arms.

Step 13: Painting (cont.)

13. Use masking tape and paper to mask off everything except the two arms that your arrow is pointing in between (ie your front arms). Paint those two front arms with one of your colors.

Step 14:

14. After the paint dries, remove the tape and paper from the back half of the frame. Now mask off the front arms. Also mask off the battery straps to avoid getting paint on them. Now paint the rest of the frame with your other color. When the paint has dried, remove your masking tape and paper.

I didn't take pictures of it for some reason, but also completely wrap the battery straps in tape so they don't get paint on the velcro.

Step 15:

You can spend as much or as little time masking and painting as you want. As you can see I went for a quick and dirty but functional paint job rather than a nice looking one.

Now the frame is complete and we can move on to the next step.

Step 16: Power Distribution and Wiring

1. From each speed controller, measure and cut 1.75” off each red and black power input wires off.
2. Solder a female 2mm bullet connector onto one end of each of the 1.75” pieces of Red wire
3. Solder a male 2mm bullet connector onto one end of each the 1.75” pieces of Black wire
4. Solder a male 2mm bullet connector onto the red power input wire of each of the speed controllers.
5. Solder a female 2mm bullet connector onto the black power input wire of each of the speed controllers.

Step 17: Power Distribution and Wiring (cont.)

6. Solder a female 2mm bullet connector onto each of the 3 motor output wires for each of the speed controllers.
7. While we are soldering, go ahead and solder a male 2mm Bullet connector onto each of the 3 motor wires for each of the motors.

Step 18: Power Distribution and Wiring (cont.)

8. Put heat shrink tubing on all of the connectors you just soldered (including the motor wires).

Step 19: Power Distribution and Wiring (cont.)

9. Cut a 13” length of both red and black 14AWG high strand count, silicon jacketed wire.
10. Measure 2.75” from one end of the red wire and put a mark, measure 2.75” from the first mark and put a 2nd mark, measure another 2.75” and put a 3rd mark.

Step 20: Power Distribution and Wiring (cont.)

11. Using an exacto knife, carefully cut off an ~1/4” strip of insulation roughly centered on the marks you made in the previous step. You need to be very careful to not cut into the wire. You don’t need to remove the insulation all the way around the wire, just about half the diameter.
12.  Stretch the black wire out next to red wire and cut the insulation off at the same intervals as you did on the red wire.

Step 21: Power Distribution and Wiring (cont.)

13. On to the short end of the the black wire (the end that has the notch of insulation removed 2.75” away), solder one of the black 1.75” wires that were cut off of the speed controllers then cover the connection with heat shrink tubing.

Step 22: Power Distribution and Wiring (cont.)

14. Next solder another black speed controller wire to the first spot of exposed wire from the short end. Cover the connection with heat shrink.

Step 23: Power Distribution and Wiring (cont.)

15. Repeat soldering and heat shrinking the remaining black speed controller wires to the black power distribution wire.
16. Repeat the previous steps with the red power distribution wire and speed controller wires.

Step 24: Power Distribution and Wiring (cont.)

17. With the front of the quad facing you, put the connectors that are soldered on the end of the power distribution wires through the oval hole on the front left arm. Then feed the power distribution wires through each arm moving clockwise, leaving a set of connectors in each arm. This can be a little tricky but there is enough room for both wires. Needle nose pliers can help to guide the connectors through the holes.

Step 25: Power Distribution and Wiring (cont.)

18. Solder a male battery connector onto the long ends of the power distribution wires. Pay attention to the polarity shown on the side of the battery connector. Don’t forget to put heat shrink onto the wires first that can be slid down after soldering.

Step 26: Power Distribution and Wiring (cont.)

19. Go ahead and install the battery now because we will need it in the next step (Don’t plug it in). The straps need to be pulled pretty tight but when you have it secure the battery shouldn’t move easily if you try to push it back and forth.

Step 27: Radio Setup

1. There are a few things we need change on the radio. Turn the transmitter on and press the list button. Use the scroll wheel to scroll down to “REVERSE” and press the scroll wheel down to select it. Scroll to “AILE”, click the scroll wheel to activate this item, scroll to “R” (for reverse) and click the scroll wheel again to select it. Scroll to “RUDD” and change it to “R” the same way. The rest of the channels should all be “N”.  Scroll to the “◄” line and click on it to go back to the previous menu.
Note: If you use a different radio, you may have to reverse different channels. You will find out when we do the motor testing in a later step.

Step 28: Radio Setup (cont.)

2. You should be on the “SETUP LIST ½” menu. Scroll down till you go to “SETUP LIST 2/2 and select the “FUNC. LIST” item by clicking on it.  On the “FUNCTION LIST” menu scroll to “FLAPS” and click on it. Scroll down to “NORM, underneath “FLAP” and click on it, use the scroll wheel to adjust it until it looks like “↓100”, click again to save it. Scroll down to “LAND” underneath “FLAP” and adjust it so it looks like “↑100”. Leave the “NORM” and “LAND” settings underneath “ELEV” set to zeros. Scroll to the “◄” line and click on it to go back to the previous menu.

Step 29: Radio Setup (cont.)

3. You should be on the “FUNCTION LIST” menu. Scroll down to “TRAVEL ADJ” and click it. Scroll down to “THRO” and click on it. Move the throttle stick (left stick) all the way up then adjust it so that it looks like “↑118%”, click again to save it. Scroll to “AILE” and click it. Hold the aileron (right stick) to the left and adjust the number until it looks like “←118%”, then move the stick to the right and adjust it so it looks like “→118%”, then click to save it. Repeat those steps to adjust “ELEV” and “RUDD” to be 118% in both directions. You can turn off the transmitter now.

Step 30: Speed Controller and Motor Installation and Setup

4. Plug the power connection of each speed controller into the power distribution plugs in each arm.
5. Zip tie each speed controller onto a leg with the motor wires coming over the top of of the leg.

Step 31: Speed Controller and Motor Installation and Setup (cont.)

6. Using four 1-64x0.25” bolts and nuts attach a motor to each arm as shown.
On my first rev of this quad, after several pretty hard crashes, the heads of the two side attachment bolts pulled through the motor mount. To fix it on that quad I used thick copper wire as shown. I went back to nuts on this quad, but you can use that attachment method if you want.

Step 32: Speed Controller and Motor Installation and Setup (cont.)

7. Plug in all the motors

Step 33: Speed Controller and Motor Installation and Setup (cont.)

8. Before we zip tie all the wires in place we need to setup the speed controllers and check for correct motor rotation direction.

Use a marker to write either “CW” (for clockwise) or “CCW” (for counter-clockwise) on each motor mount like it shows in the picture. Also go ahead and write the numbers shown onto the motor mounts which will make it easier to connect to the control board later.

Step 34: Speed Controller and Motor Installation and Setup (cont.)

9. Plug a speed controller lead into channel 1 of the receiver. Follow the instructions that came with the radio to bind the receiver to the transmitter. The receiver will get power from the BEC in the speed controller for binding.

After binding the receiver and transmitter, one at a time perform the following steps for each speed controller:
a. Start with the battery unplugged
b. Plug the speed controller into the receiver’s channel 1
c. Turn the transmitter on and then put the throttle stick all the way up.
d. Plug the battery connector in
e. After the speed controller beeps twice, move the throttle stick all the way down.
f. The speed controller will beep three times, then there will be a long beep indicating the throttle range has been saved.
g. After the long beep, move the throttle stick up a little bit until the motor spins a little bit, then move it back to all the way down.
h. If the direction the motor spins doesn’t match the “CW” or “CCW” marks you made for that motor in the previous step, unplug the battery, unplug two of the motor wires from the speed control and swap them.
i. Plug the battery back in and check motor rotation again.

The other three speed controllers that aren’t being programmed will be beeping every ~2 seconds because they aren’t hooked up to a receiver. If you can’t hear the speed controller you are trying to program you can unplug the power input from the other speed controllers until you need to program them.

Step 35: Speed Controller and Motor Installation and Setup (cont.)

10. Zip tie the wires to the stiffener and motor mount for each arm.

Step 36: Making the Telemetry Cable

The flight controller board comes with a variety of cables and wires. One of them is a 6 wire cable that plugs into the serial port we need to use for the bluetooth telemetry module. But the bluetooth module comes with a completely different type of connector.

There are two good ways of dealing with that, one is to cut the end off of the 6 wire cable, remove the CTS wire (blue) and one of the ground wires (black). Then cut off the ends of the cable that came with the bluetooth module and use solder and heat shrink to splice them together.

The other way is to use an exacto knife to gently lift the plastic tabs on one end of the 6 wire cable and remove each wire. From the other end of the cable lift the plastic tabs to remove the CTS (blue) and one of the black wires. Then crimp new JWT pins on and insert them into the JWT connector housing in the correct order. The JWT connector sets are fairly cheap (listed in the parts list) but it is fairly difficult to crimp the pins on unless you have the right crimping tool (listed in the tools list) which costs ~$14. It can be done with needle nosed pliers but it takes some practice. If you do go the crimping route, crimp the JWT pins on top of the smaller pins that are already  on the ends of the wires when you removed them from the original white housings. The wires are fine and crimping on top of the old pins will make it harder for them to pull out.

Whichever way you make this cable, splicing or crimping, the TX and RX wires need to be swapped so that the TX wire of the flight control board goes to the RX pin of the bluetooth modules and the RX wire goes to the TX pin.

Hopefully the pictures help explain this better.

Step 37: Making the GPS Cable

The GPS module comes with a cable that has a similar connector as what plugs into the flight controller board, but doesn’t have the right number of pins on the housing as what we need. To fix that, take the housing off one end of the cable that came with the GPS by using an exacto knife to gently bend the little plastic tabs up then pull the wires out. Use the same technique to removing the housing from one end of the 8 pin cable that came with the flight controller board. Insert the loose pins from the GPS cable into the 8 pin housing as shown.

Step 38: Install and Connect the Flight Control Board

1. Print out and trace template onto the latex mounting foam and cut it out with an exacto knife or scissors. I’m not really sure if it is safe to laser cut this type of foam (but I know it smells really bad). One requirement of the foam is that it be porous so that it doesn’t interfere with the barometer on the flight controller. I recommend that you get this from a local hobby store so you can check it out before you buy it. If you can breath through it then it is good to go.

Step 39: Install and Connect the Flight Control Board (cont.)

2. Set the flight controller (with the GPS and Telemetry cables already plugged into it) onto the foam pad you cut out as shown and then press the flight controller and the foam together down into the shelf. The foam is cut so that the sides should fold around the board and isolate it from vibrations on both the sides and the bottom.

The is an arrow on the board the would normally indicate the direction of forward flight, but in our case it is pointing 45 degrees off of forward. Don’t worry about this, it is fixed in the software.

You can go ahead and fold the triangular flap over the top of the flight controller board and install the cross piece as shown.

Step 40: Install and Connect the Flight Control Board (cont.)

3. Each speed controller supplies 5V on the red wire, called a battery eliminator circuit or BEC, normally used to power the receiver.  It seems like opinions vary online if it is ok to have multiple BEC tied together, but I think it is a bad idea. This speed controllers BEC is rated for 2A, but if you try to power all the electronics off of one speed controller’s BEC it gets really hot. Lastly there is a problem with this flight control board that makes it so the some of the boards serial ports won’t get power unless the board is supplied with power to the external power connector, rather than from the speed controller headers.

For all of those reasons we will power the electronics as follows:
a. Use an exacto knife to gently lift the little plastic tab from the red wire on three of the speed controllers servo connectors and remove the red wires. Cover the removed red wire connectors with heat shrink.
b. Plug one of the BEC lines that were removed from the speed controllers servo connector in the Ext. power supply pin indicated in the picture.
c. Another one of the BEC lines that were removed from the speed controller will be plugged into the receiver to supply power to it.
d. The last BEC line that was removed wont be plugged into anything right now. It can be used later to power LEDs, an FPV camera or transmitter, etc.
e. The fourth speed controller’s BEC that is left in the servo connector will be used to power the camera’s tilt and roll servos for later expansion.
f. Remove the jumper indicated in the picture so that the remaining BEC line plugged into the speed controller headers it doesn't try and power the rest of the board.

Step 41: Install and Connect the Flight Control Board (cont.)

4. Next we need to connect the receiver signal wires and ground to the to the flight controller board as shown. The flight controller board comes with a 3 pin servo cable and a bunch of single pin cables. We will use the 3 pin cable to connect the first 3 channels to the FC and this use 3 single wires to connect the next 3. We are only connecting the signal pins for each channel (with the receiver laying flat, the top row of pins) to the flight controller. A 4th single wire cable will be connected to ground. Alternately you can use another 3 pin servo cable instead of the 3 individual wires to make the wiring a little cleaner.

Zip tie the receiver to the electronics shelf cross member.

NOTE: If you use a different receiver, specifically one that names the pins (THROT, AILE, etc) the channels might be in a different order. If that is the case this you won’t be able to use the 3 pin cable as is and you will either have to swap pins around in the 3 pin connector or use more of the single pin wires.

Step 42: Install and Connect the Flight Control Board (cont.)

5. Connect the four servo connectors from the speed controllers to the flight controller board as shown. The number you marked next to each motor in a previous step correspond to the number shown in the picture and marked on the board.

6. We will leave bluetooth and GPS unplugged for right now, so we can move on to the software installation.

Step 43: Firmware Installation

I describe how to setup the quad using windows based software. It looks like you should be able to use a Mac or linux based computer but you will have figure it out on your own.

1. Download the Arduino software  and unzip it to a directory you will be able to find it.
http://arduino.cc/en/Main/Software

2. Download and unzip the Multiwii software attached to this step that I have configured to work with this quadcopter.

Step 44: Firmware Installation (cont.)

3. Plug a micro USB cable into the flight controller (FC). You don’t need to have any external power applied to the board, it will get the power it needs right now from the USB.

NOTE: If you have the bluetooth module already plugged into the “RX0” port on the FC, unplug it for right now. 

Windows 7 will install the driver automatically.

If you are running Windows XP follow these directions from the Arduino web site (http://arduino.cc/en/Guide/Windows):
“On Windows XP, the Add New Hardware wizard will open:
 -When asked Can Windows connect to Windows Update to search for software? select No, not this time. Click next.
- Select Install from a list or specified location (Advanced) and click next.
- Make sure that Search for the best driver in these locations is checked; uncheck Search removable media; check Include this location in the search and browse to the drivers/FTDI USB Drivers directory of the Arduino distribution. (The latest version of the drivers can be found on the FTDI website.) Click next.
- The wizard will search for the driver and then tell you that a "USB Serial Converter" was found. Click finish.
- The new hardware wizard will appear again. Go through the same steps and select the same options and location to search. - --- This time, a "USB Serial Port" will be found.
- You can check that the drivers have been installed by opening the Windows Device Mananger (in the Hardware tab of System control panel). Look for a "USB Serial Port" in the Ports section; that's the Arduino board.”

Step 45: Firmware Installation (cont.)

4. After you have the driver installed, go to where you unzipped the Arduino software and double click the “Arduino.exe” program. That will open up a blank sketch (a window where you could type in a arduino program from scratch, doesn’t really matter).

5. Under “File”, select “Open”, find the folder you unzipped the Multiwii software to (which will contain to folders MultiWii and MultiWiiConf), open the MultiWii folder and then select the “MultiWii” sketch. You will now have the MultiWii sketch and the blank sketch open, you can close the blank sketch now.

Step 46: Firmware Installation (cont.)

6. This is kind of an optional step, but in order for the flight controller's on-board digital compass to be accurate, you need to set the magnetic declination for your geographic location. First, go to  http://magnetic-declination.com/. It should give you the Magnetic Declination for your location in degrees and minutes. For example, my declination is “15° 54’ EAST and Declination: POSITIVE.” We need to convert that into decimal format using the formula: degrees + (minutes/60). So for me it is 15+(54/60)=15.9
Click on the “config.h” tab at the top of the multiwii sketch. You might have to maximize the arduino window to see all of the tabs. Scroll down to line 703 (the line number you are on is shown at the bottom left corner of the arduino software).
Where is says:
    #define MAG_DECLINIATION  15.9f
Change the “15.9f” to your declination that you looked up and calculated. If your declination was NEGATIVE then add a “-” in front of your number. Put the the “f” after your number.
Then click FILE->SAVE to save your changes.

Step 47: Firmware Installation (cont.)

7. Click Tools -> Board and then select “Arduino Mega 2560 or Mega ADK”
8. Click on Tools -> Serial Port and select the serial port that installed when you plugged in the FC. If you are not sure which COM Port that was then click on Tools to close the pull down menu, unplug the FC from the USB port, then click on Tools -> Serial Port again and write down all the serial ports listed. Now click on Tools to close the menu again, plug the USB cable into the FC again and go back into the Tools -> Serial Port menu. Select whatever serial port is listed now that wasn’t previously listed when you wrote them down.

9. Because I have already configured this MultiWii sketch for the quadcopter I described building, you can just click on File -> Upload. There will be a status bar at the bottom of the Arduino window that will say “Compiling” then “Uploading”. Wait until the status bar says “done Uploading”.
10. Close the Arduino software and unplug the USB cable.

Step 48: MultiWiiConf Program and Setting Up the AUX Channel

1. Plug the USB cable into the flight controller.
2. Navigate to the folder where you unzipped the MultiWii software, then open the MultiWiiConf folder. In the MultiWiiConf folder, open either the Application.windows32 or Application.windows64 folder depending on if you have the 32-bit or 64-bit version of windows installed. Now double-click on the MultiWiiConf.exe file.
3.  On the left hand side of the MultiWiiConf program, select the COM port that is connected to the FC (the same one you selected in the Arduino software) . After it connects to the FC, the list of  COM ports as well as the START and STOP buttons in the middle application will turn from red to green.
4. Click the START button and you will see a graph of the the sensor data start scrolling and all the default numbers will load in the PID settings.
5. I have found that the default PID settings work ok (but could be better) for this quad. You will probably want to tweak them a bit after getting used to the quad. Each quad is different and will work better with different PID values. When I start playing with the PID settings I am just doing it by trial and error. I am not knowledgeable enough to describe how go about tuning the PIDs in a logical fashion.

This link has some great info on tuning the PIDs: http://www.multiwii.com/wiki/index.php?title=PID

Step 49: MultiWiiConf Program and Setting Up the AUX Channel (cont.)

6. For right now all we need to change is the settings for the Aux switches. Click on the boxes under AUX1 Low and Mid for ANGLE and under AUX1 High for ANGLE, BARO and MAG as shown. Then click the “WRITE” button.

Plug in the battery to the quadcopter. After a few seconds for everything to initialize, if you flip the “Gear” switch you should see it switch between modes.

Horizon mode is a little bit more acrobatic than Angle mode. Angle mode is more stable and will be easier to learn in, so we configured it so that it is always in angle mode for right now.  The way we set it up, if we flip our gear switch up it will enable the barometer and magnetometer which will make it essentially try to maintain the current altitude and heading unless you command it to a different altitude/heading.

Later we will configure Aux2 (our Flaps switch) to turn on and off GPS HOLD or GPS HOME, but until with test the quad out in the air lets leave those off.

NOTE: The Props shouldn’t be installed on the motors
NOTE2: If you move the left stick on the radio, move it to the ~the center of the up/down range before moving it left to right. Moving the left stick down and to the right “ARMS” the quad and then the motors may start spinning if you move the throttle up.

Step 50: MultiWiiConf Program and Setting Up the AUX Channel (cont.)

7. With the quad sitting on a level surface, click the “CALIB_ACC” button. Wait a couple of seconds.

8. Click the “CALIB_MAG” button. You will be able to see the lights on the board near the cross piece start flashing. Go ahead and unplug the USB cable and rotate the quad 360º in all directions (yaw, pitch and roll). Wait until the lights on the flight control board stop flashing (about 30 seconds) then unplug the battery.

9. Close the MultiWiiConf program.

Step 51: Motor Testing

1. Turn the transmitter on and plug the battery into the quad.
NOTE: The Props shouldn’t be installed on the motors
2. Move the transmitter’s Left stick down and to the right for ~2 seconds to arm the flight controller board. Some lights should come on the flight controller board. Move the Throttle up slowly about ¼ of the way, the motors should start spinning. Don’t worry right now if all the motors don’t start spinning at the same time/speed. With the motors spinning perform these tests:
a. Tip the quad forward. The forward 2 motors should speed up.
b. Tilt the quad to the left. The left motors should speed up.
c. Rotate the quad clockwise. The front left and back right motors should speed up.

If the quad does not respond like this it indicates that the flight controller board isn’t installed in the correct orientation, the connections to speed controllers are plugged-in in the wrong order, or the connections between the receiver and the flight control board are hooked up wrong. Go back and check the wiring to make sure everything is hooked and installed correctly.
DO NOT MOVE ON UNTIL THESE TESTS PASS.

Step 52: Motor Testing (cont.)

3. Move the Throttle up slowly about ¼ of the way to get the motors spinning then conduct these tests:
a. Move the elevator stick (right stick) up. The 2 back motors should speed up.
b. Move the aileron stick (right stick) to the right. The 2 left motors should speed up.
c. Move the rudder (yaw) stick (left stick) to the right. The front right and back left motors should speed up.

If any of the tests fail, try reversing or un-reversing the channel(s) that failed on the transmitter (see the earlier step about radio setup or the radios manual for instructions).
DO NOT MOVE ON UNTIL THESE TESTS PASS.

Step 53: Installing the Props and Final Steps

1. Each prop will need an adaptor to adapt the 5mm hole in the prop to the 3mm motor shaft. Each pack of props comes with several adaptors in different sizes. Select the one that fits the tightest on the motor shaft.
2. The props are labeled either 8045 or 8045R for 8”x4.5” and 8”x4.5” Right hand rotation. The 8045 props are for the motors labeled “CCW” and the 8045R props are for the “CW” motors.
3. Put an adapter on each motor shaft then slide a prop on it. Some of the props I have used are a little loose on the adapter (can wobble back and forth a little). If that is the case, put a little CA on the inside of the prop hole before sliding it onto the adapter and motor shaft then let it dry. Don’t use so much glue that it drips down into the motor.
4. Hook an o-ring on one of the button head screws sticking out of the motor shaft, stretch the o-ring over the prop, and hook it on the button head screw on the opposite side. Repeat for the other motors and props.

Step 54: Installing the Props and Final Steps (cont.)

5. Zip tie the wires going to the flight controller board into bundles as neatly as possible.
6. Zip tie the electronics crossmember to the electronics shelf
7. Zip tie the bluetooth module to the side of the electronics shelf and plug it in
8. Zip tie the GPS to the electronics shelf top piece. Plug in the GPS cable. Zip tie the top piece to the electronics shelf.

Step 55: Taking It for a Spin

1. If you are an experienced pilot of model helicopters, planes, or multi-rotor craft, you shouldn’t have any problems flying this quad.

If you are not an experience pilot, find someone who is to supervise you.

For your first flights I recommend finding someplace with soft grass, lots of space, not many people, and no power lines overhead. Usually you can find a park to meet these requirements.

It should be obvious, but even though the props are plastic they are spinning at thousands of RPMs and are perfectly capable of cutting off fingers or toes. If you fly near people and you make any kind of mistake you may severely hurt somebody. This quad may also damage property (houses, cars, etc). I make no claims that even if this quad is built exactly as described that it a safe object to have flying through the air. It is up to you to assess the situation and decide if it is safe to the fly this quad. BE CAREFUL!!!

Step 56: Taking It for a Spin (cont.)

2. With that out of the way, when you have found a safe place to fly, follow these steps:
a. Turn on the transmitter and make sure your throttle is down and your AUX1/Gear switch is in the down position
b. Plug the battery into the quad copter and place it on level ground. There will probably be a light flashing on the board while it is searching for GPS signals. You don’t have to worry about that right now.
c. Leave the right stick centered and move the left stick to the bottom left to make sure that the quad isn’t armed yet. Slowly raise the throttle up and make sure the motors don’t start spinning.
d. Before we fly it for the first time we are going to cal the gyro, accelerometer, and magnetometer using the transmitter sticks. You can download and print this reference on what the different stick movements do in MulitWii V2.2 https://multiwii.googlecode.com/svn/branches/Hamburger/MultiWii-StickConfiguration-22_v0-577215664.pdf

Move the Right stick straight down and the left stick down and to the left to cal the gyro, then release the sticks. The lights on the board should blink faster for a few seconds then go back to being off or blinking slowly. Next move the right stick straight down and the left stick up and to the left to cal the accelerometer, then release the sticks. The lights should again flash fast(er) for a few seconds then stop. Now cal the magnetometer by moving the right stick straight down and the left stick up and to right then release the sticks. The lights will start flashing fast for 30 seconds, during that time while they are flashing rotate the quad by hand 360º in all directions.

Step 57: Taking It for a Spin (cont.)

e. Now you are really ready to fly. Leave the right stick centered and move the left stick down and to the right to arm the flight controller. The light on the board should change to be solidly on.
f. The basics are, the right stick moves forward and back, left and right (Pitch and Roll respectively). The left stick moves the quad up and down and rotates the quad in place (Yaw). After that it is a matter of doing it and learning. Remember to make small movements with the sticks. The quad will leave the ground at about half throttle and it has the ability to climb pretty fast.

One thing that people new to flying helicopters and multicopters have a tendency to do is give it to much throttle, be surprised that it is climbing to fast and cut the throttle too much causing it to drop to the ground. Try to keep it less than 10 feet off the ground until you are used to flying it.

Once you have a little experience keeping it in the air, try flipping the AUX channel switch up to engage the altitude and heading hold. 

If you find that the quad constantly wants to drift a certain direction, you can adjust the trims on the transmitter to get it to level out. If it is drifting a lot you can try re-calibrating the accelerometer again on a flat, level surface. 

Step 58: Bluetooth Configuration and Tweaking of the Quadcopter Settings

The steps after this one are mostly for if you have an android based device.

If you don't have an android device but you have a laptop with built-in bluetooth or a bluetooth dongle you can still connect to the quad. I don't have the knowledge to describe the exact process to setup a bluetooth serial port on every laptop and I had to fiddle with it a lot to get it working, but you can probably find more info on the web for your specific operating system.

The basics are:
1. Install or turn on your bluetooth adapter
2. Plug the battery into the quad and the red light on the bluetooth module will start flashing
3. Attempt to discover near by bluetooth devices on your laptop
4. After it finds your bluetooth module it will probably ask for a pin number before pairing to the device, use "1234"
5. During the pairing it may ask you what services to use, select bluetooth serial
6. When you have it set up right you will have a new serial comm port available.
7. Open the MultiWiiConf program like you did in a previous step but this time select the new com port that was installed above. When it connects properly, the red light on the bluetooth module should stop flashing and should be on.
8. You should now be able to adjust all the settings from the multiwiiconf program without having to plug a usb cable into the quad.

NOTE. The bluetooth serial port only will work to configure the quad, you can't install firmware over the bluetooth connection.

Step 59: Bluetooth Configuration and Tweaking of the Quadcopter Settings (cont.)

On an android device, I recommend searching the google play store for a program called MultiWii EZ-GUI and installing it.

First plug the quadcopter battery in and make sure the bluetooth module has a flashing light on it.  Start the MultiWii EZ-GUI and swipe over a couple of screens and then press the Config button to bring configuration screen. Click on the "Select MultiWii BT" button. A pop-up menu will open, click on "Scan for devices". It should find your quad's bluetooth module (mine was called  "HB01", click on that. The pop-up menu will close and now there will be some numbers next to the word "MAC:" under the bluetooth select button. Press your device's back button to get out of the configuration screen.

 Click on the "MW CONNECT" button at the top of the screen. The first time you connect it will pop up with a box requiring a pin number, put in "1234".

After a couple of seconds "Connected" should flash at the bottom of the screen and the red light on bluetooth module should stop flashing and stay on solid.

You can now monitor and tweak your quad from your phone/device.

Step 60:

Step 61: Using the GPS Hold Function

I don't recommend using the GPS until you have either a laptop or android device connected to your quad so you can verify your home/current position before enabling the GPS.

For your first test using the GPS, assign the "GPS HOLD" function to your AUX2 switch on the AUX screen of the MultiWii EZ-GUI and click "SAVE TO EEPROM". Toggle your flaps switch and pay attention to the position of the switch when the "GPS HOLD" function turns green meaning that the hold function is enabled. For now, put the switch to the other direction to disable it.

Press your devices back button to get out of the AUX screen and then swipe back to the main screen. Click on the "GPS" button. On the GPS info screen, verify that there is a "1" next to where it says "Fix", if not wait awhile longer for the GPS to get a lock. Now go ahead and start flying your quad and get it 10-20ft off the ground. First enable the BARO and MAG functions by flipping the AUX1 switch verify that it is flying stable without having to adjust the throttle stick to maintain altitude, then flip the AUX2 switch. It should try and hold its current position without you having to move the right stick. Because there is a certain amount of error in the GPS position it may drift around a bit, sometimes by 10-20ft, but in general it should stay close to the position it was in when you flipped the aux2 switch.  

Step 62: Using the GPS Home Function

Using the instructions in the previous step, change the function assigned to the AUX2 switch from the "GPSHOLD" function to the the "GPSHOME" function.

Navigate back to the main screen, then click on the "GPS" button to view info about the GPS. In addition to making sure "Fix: 1" like we did last time, pay attention to the the "Distance From Home:" and "Heading to Home:" fields. When you arm your quadcopter (by moving the throttle stick down and to the right) it sets your home position to the your current location, so if you arm you the quad copter the distance to home number should go to/remain zero. Now fly your quad ~50-100ft away and land it. Make sure you have a clear path between you and the quad with no obstacles. Check the GPS info screen and verify distance to home and heading to home numbers look reasonable. Take off, get the quad flying level at ~10-20ft above the ground and enable the AUX1 switch. Wait a little while to make sure the quad seems to be flying without having to make a throttle adjustments. Then flip the AUX2 switch to command it to return to home. It should start flying back to where you initially armed the quadcopter.

Step 63: Links to More Info

http://www.multiwii.com/wiki/index.php?title=PID
http://www.hobbyking.com/hobbyking/store/uploads/998673411X846863X49.pdf
http://www.hobbyking.com/hobbyking/store/uploads/998673411X846863X42.pdf
http://www.hobbyking.com/hobbyking/store/uploads/174005127X620007X13.pdf
http://www.hobbyking.com/hobbyking/store/uploads/684736734X7478X34.pdf
http://arduino.cc/en/Main/Software
https://code.google.com/p/multiwii/downloads/list
https://multiwii.googlecode.com/svn/branches/Hamburger/MultiWii-StickConfiguration-22_v0-577215664.pdf

Step 64: Conclusion

So that is the quad. I have flown this one or the previous version for hours and I think it is a fun little quad.

I have designed a servo stabilized camera mount that attaches to this quad and I may post an instructable for that in the future if I can figure out how to dampen the vibration enough that the video from that camera is at all watchable. 

Other future enhancements that are possible: FPV, long range telemetry using 933mhz serial dongles, carbon fiber props, battery voltage monitoring, etc. Pretty much anything you can think of. As built the quad weighs 1lb, 7oz. Experimenting the camera mount I have loaded it down to 2lb, 1oz and it still seemed to fly pretty good, although you will need to tune the PID settings for that amount of weight.