DJI Naza GPS X,Y,Z co-ordinates
The shots below show my settings in the DJI Naza Assistant software for the X, Y & Z co-ordinates and what that translates to on the Quad. The first time I flew with the GPS, I didn't bother to set any parameters and GPS mode wasn't very good. As soon as I activated it, the quad would bank left and drift quickly until I re-engaged attitude mode.
I made three changes before the next flight. 1. Mount the GPS on the stick provided, 2. Point the arrow on the GPS towards the front and 3. Enter the co-ordinates in the software configuration. After another test flight, the GPS holds position pretty well. What I don't know is what had the most effect (the mount, direction or co-ordinates). I'm hoping it's the co-ordinates in the software because I'd prefer not to use the stick mount because it makes it bulkier to pack and more prone to damage on a hard landing. I think I'll try going back to double sided foam tape and mount it directly to an arm.
The pictures below show these settings X = -4cm, Y=4cm and Z=-9cm and what they look like in the real world.
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EagleTree Logger V4 on the DJI Naza F450
The first full flight with the EagleTree Logger v4 running on the DJI Naza F450 with GPS. The first 140 seconds show little activity while I plug things in and wait for GPS lock. When I eventually takeoff with a 4S 2200 Nano-tech LiPo, the voltage drops to 15.4 Volts and within 40 seconds drops down to 14.8 Volts as you'd expect from a 4S battery. It seems to hold the voltage fairly well throughout the flight keeping in mind it was fairly sedate backyard hovering with the GoPro onboard and recording. The voltage seems to start decling quickly after about 500 seconds where there's a few spikes in current and corresponding drops in voltage where I did a few short sharp rapid ascents with the throttle wide open. At about 670 seconds, the voltage drops too far and the second level protection kicks in where the Naza automatically descends. For my liking, it descends too rapidly but I'm not sure if that might be the result of setting the second level voltage protection level too low so there's nothing left in the pack to land safely. I wonder if I up the Voltage level, will the descent be more controlled when the Naza takes over.
I got about 2,000 mA out of the 2,200 pack which seems fairly good. The quad is loaded up with a GoPro, Naza GPS, Eagletree logger and Eagletree GPS so it's carrying a little more weight than usual. 8.5 minutes hover time seems pretty good I reckon. Average current draw with the 8" props is around 13 amps with a peak at 24.5. The 30Amp ESCs should be more than comfortable to handle that load.
This was the second flight with the DJI Naza GPS and all went well. There's been many rumours floating around the forums that the GPS doesn't work so well in the Southern Hemisphere (SH) and after my first flight I was worried they were right. During that flight, whenver I activated GPS mode the Quad would veer off to the left and never recover. After entering the X,Y,Z co-ordinates in the software configuration and mounting the GPS on the stick, it works great. At most the drift was maybe 1 meter but most of the time it seemed to hold position withing bout 30-50cm.
Next mission - Test the Return to Home (RTH) feature. I'll need a bit more space than the backyard though because it's supposed to ascend 20 meters, return to base, then land. Need to make sure there's no trees in the way. At the moment, the only way I have to trigger failsafe mode is to switch off my transmitter. That could be a bit nerve racking. In all my years of RC flying, I've never deliberately (or accidentally) switched off my Tx in mid-flight. I might have to make sure to have the video camera recording that one.
How to mount a GoPro to a DJI Naza F450
I'm not saying it's the best way, it's just how I do it and it seems to work well. Velcro on the bottom of the GoPro, velcro on the part of the F450 frame that sticks out the front then wrap a length of velcro around the entire camera. The "shutter" button can still be easily operated through the velcro.
Simple, light and works. I used to use the protective case but what's the worst that could happen. If I write it off, I'd have to replace it with a new version 2 GoPro. Damn. 🙂
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 test flight
It was looking good with the FY-91Q control board until the Spider Quad dropped out of the sky (well maybe only about 1 foot off the ground). Looks like the 3mm Bunnings ply maybe wasn't up to the task. Easy fix though, I'll mount the motors directly to the aluminium c-channel. The wooden mounts are superfluous anyway.
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.
Proof the foamy quadcopter flies
Today was the first flight outside the confines of the garage. It was quite windy at the local oval making it fairly difficult to maintain stable flight. It's not meant to fly nicely, it's meant to look weird and fly weird and that's exactly what it does.