DJI Naza GPS installation on F450 Flamewheel
The DJI Naza GPS arrived today from Queensland, ordered from Quinton Marais (info@multiwiicopter.com). I must say his postage time is quick. I ordered it Wednesday night and it arrived at work in Melbourne Friday morning, just in time for the weekend.
The unit comes with a little 2 inch mounting pole that I guess helps elevate the GPS and Magnetometer from surrounding interference. Somewhere in the manual it talks about sensitivity to both vibration and magnetic field. I reckon the vibration would be worse when mounted on the supplied pole so I've gone with directly to the arm. I used some doubled sided foam tape to hold it on the arm.
A quick test in the backyard and it took maybe a minute from coldstart to acquire a full GPS lock. You can tell that by the colour and sequence of the flashing VU. When the controller is set to GPS mode, and before satellites are acquired, the VU will blink RED, RED, RED, GREEN. As more and more satellites are acquired, the number of RED flashes decreases until the VU flashes GREEN about once every two seconds.
No test flight to report yet.
** Update 6th July.
I've since moved the GPS onto the stick, faced it forward, entered the X,Y & Z co-ordinates and calibrated the magnetometer. It works much better now.
http://fangin.com/blog/2012/06/26/dji-naza-gps-xyz-co-ordinates/
Unpacking the Naza Controller
After 3 years of using a couple of MultiWii Paris boards (Version 2 & 4) on a whole variety of quads and tricopters (http://bit.ly/JZ1iDA) and tricopters, I've bought my first commercially made multirotor controller. The DJI Naza controller (http://bit.ly/JZ1S4r) along with an F450 Flamewheel frame. It's tempting to retrofit a couple of old Quads with the Naza to compare the performance between the MWC and Naza but I'm too keen to see the DJI controller and frame flying as one unit.
What comes in the little red box.
- The Main Control unit (MC). It's smaller than I expected with inputs at one end and outputs at the other
- The Versatile Unit (VU). Basically a voltage monitor, regulator and USB interface to programming the board.
- The USB cable. I was a little disappointed it uses a micro USB connection instead of the fairly standard mini USB connection. It just means I'm less likely to have a spare cable on hand if I misplace the DJI supplied one. I guarantee if you were at the flying field and needed a 'mini' USB cable that almost every product comes with and seem to be multiplying in my desk draw, someone would have one in their camera bag or portable hard disk....
- 3-PIN Servo cable (female to female) for connecting your receiver to the Naza controller. By the time you connect the four standard controls, plus mode switch, plus X1, X2 & X3 you'll use them all up.
- 3M Gummed paper for sticking the controller to your multirotor. It's not very thick. Not sure if I'll use the supplied stuff or my own.
Configuring the Naza.
- The first thing to do is download and install the DJI Naza Assistant Software. Registration and activation by email is required so the DJI overlords can keep track of everyone that has the privilege of using their hardware.
- While waiting a few seconds for the activation email I soldered an XT-60 connector to the VU and hooked up a 3S 2200 Lipo.
- I'll be using 'Quad-rotor X4' config.
- Receiver Type = "Tradition(al)"
- Calibration was pretty straightforward by banging the sticks to all possible end-points. At one point I did get a flashing red box saying "Config Error" but after a power cycle it went away.
- I've assigned Sticks monitor (X1 & X2) to my slidey switches on the LHS and RHS of my Futaba 10C Tx. From what I understand these channels can be used for inflight gain adjustment. I'm not convinced I'll use that much but we'll see.
That's about as far as I've got. Think I might start putting the frame together.
Spider quad build
The motors, ESCs, and control board (FelyuTech FY-91Q) board are all mounted. Now I just need to connect them all.
Just mucking around with this control board while waiting for the DJI Naza to arrive.
How to connect 4 ESCs to one LiPo battery (Make a power distribution board)
The first time I built a power distribution / wiring harness for a tri / quadcopter was back in December 2010 (http://fangin.com/blog/2010/12/07/tricopter-build-wiring-harness/) and I chose the most direct solution which was to solder all the cables together. I say "most direct solution" because in hindsight, it's not the simplest solution. The drawbacks of this solution include;
- It's more difficult to layout all the wires and get the lengths planned up front.
- Twisting the wire together and soldering 4 or 5 wires at one junction gets messy.
- I tried to link all the wires at one point (http://fangin.com/blog/wp-content/uploads/2010/12/1000000286-Large.jpg) to go into the battery which made it difficult to get the wire into the XT60 connector.
A neater, simpler and all round better solution is a power distribution board where a central, double sided PCB board (copper on both sides) is located centrally in relation to the ESCs / motors and all the wires connect back to this PCB.
What you'll need.
- PCB - Double sided.
- Cutters
- Red / Black Wire
- Solder / Soldering iron
- 20mm heatshrink tube.
- Cut a small board approximately 35 x 15 mm of the double sided PCB.
- Prepare the wires and board by soldering the ends of each wire and the board where the wires will go. You may want to consider orienting the wire to suit the layout of your multirotor. For example an X-Quad you may want to have four wires coming off the board in an X layout.
- Solder the wires to the board. Turn the board over and repeat for the other polarity wires.
- At this point you're almost ready to seal the board up with some heatshrink tube. Before you do! Use a continuity test on a multimeter to ensure 1) All the ground wires are connected and 2) There is no connection between the positive and ground planes.
- If you're worried about wires moving or foreign objects getting into the heatshrink, smother both sides of the board with glue from a hot glue gun. That will help keep the wires in the right place and prevent a short circuit between the two polarities should something conductive work it's way into the housing.
- Now you can solder your favourite connectors at the end of each pair of wires. In the photo shown below I've used XT60 connectors on a harness made for a tricopter.
QuadCopter by the Moonlight
This photograph wastaken by Nick Sage at our Christmas club meeting at the LDMFA field. It shows my MWC Quad hovering with the moon partially covered by cloud in the back ground.
Tuning for auto-level – MWC Quad
According to the instructions on multiwiicopter.com the mid and endpoints need to be set properly to ensure auto-level works properly. I hadn't bothered much with this except to make sure the throttle travel was low enough to arm the PARIS board. This is probably why I've spent so much time stuffing around with trimming flights trying to get the perfect autolevel hover. After so many trimming flights, I thought it would be good to go back to basics and start from the ground up. Especially since I've just finished assembly of the new Scarab Quadcopter, now is a good time to get things right.
Setting the low point to 1095, the midpoint to 1500 and the high point to 1905 is achieved via sub trim and end point adjustment (on my Futaba 10CAP). The first step is to get the midpoint right at 1500. For this example, I'll assume a working connection between your PC running Multiwiiconf software and the Paris board.
- Center all the transmitter sticks and trims.
- Read the values from the MWC software. They should be close to 1500.
- On the Futaba 10CAP, hold down MODE, then Sub Trim and adjust all 4 channels to as close as possible to 1500.
- Then use the END POINT function on all four channels to high and low point to 1905 and 1095 respectively. Using the elevator as an example, pull full back on the elevator stick and read the value in the MWC software. Hold the stick there while adjusting END POINT so the readout shows 1095. The push the elevator stick on the tx to the other extreme and use END POINT to adjust the readout in MWC to 1905.
- Repeat the process for the other three channels.
- Go fly and see what happens. In my case I'm getting a bit too much oscillation when I activate auto-level that I'm sure can be solved with some PID tuning. I also seem to get the occasional glitch where it seems two motors drop RPM just enough to cause a small drop in altitude. I'm not sure if it's actually a drop in RPM or vibration as I reckon I can perceive a slight amount of vibration. Come to think of it, those two booms are the ones missing one of the four screws in the boom holder because the shafts thread was stripped or non-existent. I do have two spares that came with the kit so it looks like I'll have to go back, disassemble and replace those shafts.
MWC Quadcopter – Cramming in the ESCs
These photos show the frame starting to come together. The bottom of the CF plate shows each of the four ESCs are held in place by 2mm cable ties. There's not a lot of room left on the top of the board after the ESCs and power distribution cable is laid down. On top of this will come the three leads from each motor to plug into the ESC. If you were thinking of using any gauge wire heavier than 20AWG, you might want to think again because even just space will become an issue.
The next plate above is prepared with nylon mounts to host both the MWC control board and above that will be another quad frame plate that is likely to host my GoPro camera. I haven't decided yet whether to put the camera up on the top plate or out in front on an extended arm. Up top under a dome would be better balanced and protected, but out on the arm might have a better view clear of the props. Undoubtedly I'll end up trying both but seeing as I don't have the extended arm, and it costs more money, I'll see how it goes up top first.
Quadcopter Scarab – Power Distribution lead
These photos show the power distribution lead made as per the instructions that come with the Scarab 12 - Quad-X Euro frame. The wire is 20 AWG from HobbyKing. About 15mm of the silicon jacket is stripped from the end of five wires per polarity (red & black). Then the bare wire of each group of five is twisted together. Some 5mm heatshrink helped keep the leads together while being soldered. The result fitted nicely into the terminals of an XT60 connector. I used four micro-deans at the other end to connect to the ESC and one JST connector to hookup some strip LEDs.
QuadCopter SCARAB – Motor Mount Retainer
These photos show the retaining screw cut to 7mm and how it penetrates one quadrant of the 12mm aluminium tube divided up by the motor mount. Cut to the right length, it doesn't intrude far enough to cause concern with rubbing on the wire from the ESC to the motor which is routed internally along the tube.
QuadCopter SCARAB 12 – Assembly part 2
The frame looks well laid out, light weight and just plain good looking. 20AWG is used to connect to the 2213N 800Kv Brushless Motors with just enough left hanging out the end to connect the four speed controllers ( TURNIGY Plush 12amp (2A BEC) BESC ). The only thing I'm unsure about so far is the sorta sharp edges of the aluminium booms and how that might rub against the wires.
