DJI Naza F450 Gain Settings – Flips and rolls
The settings I've been using up until this point were;
Basic Gain: Pitch: 150, Roll 150, Yaw 100, Vertical 120
Attitude Gain: Pitch 70, Roll 70
The problem I found with these settings was under heavy acceleration, the quad would oscillate. The same oscillation would occur with high yaw application and when descending from height. After some forum reading I decided to enable "Remote Adjust" by assigning X1 to the Basic Gains and X2 to the Attitude Gains. The oscillation on descent was apparently due to too low gain on Attitude settings.
By using "Remote Adjust", the gain settings can be changed in-flight and the affects judged immediately. I found increasing the Basic Gains to max the quad would start oscillating even just in a hover. Backing it off a few notches would stabilise the quad and give quite good response to input. Dialling the gains all the way down meant the response was much softer and smoother which meant response to input is slowed somewhat. Without knowing what the actual values were at the time, I settled on gains that seem to be a good mix between control authority and smooth flight. There was still some vibration but I'll work on that.
I think I'll keep the Remote Adjust capability setup on the Quad. Being able to dial back the gain for some slow smooth input for photos and video and then dial it up for some hot-dogging is a great feature. All without having to stop and plug in the laptop.
The gain settings I settled on are;
Basic Gain: Pitch: 104, Roll 104, Yaw 69, Vertical 83
Attitude Gain: Pitch 150, Roll 150
Stabilise Filter Example – Telstra Tower
On the left is the original footage from the DJI Naza F450 GoPro. On the right is the "stabilised" version. By uploading the original to YouTube, applying the stabilise, then downloading the MP4 and running it back through YouTube you're able to see a side by side comparison.
The stabilised filter has some funny side effects where it appears as though the video is suddenly zoomed in and out. The blurriness of the RHS probably isn't a fair representation because that side has been uploaded, compressed, and downloaded.
The process does crop the video slightly and uses the edges as a buffer to remove the sudden movements from side to side or up and down.
The videos are in pretty good time sync but you may notice the RHS looks like it's behind the LHS. This lag is due to the smoothing effect of the filter and sudden movements take a little bit more time to catch-up with the RHS.
I've since changed the mount that the GoPro uses and without any post-processing the video is quite smooth. It will be interesting to see how smooth a video would look from the new mount after applying the stabilise filter.
Overall for this type of video, the stabilise filter does a pretty good job.
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.
DJI Naza F450 Flamewheel Assembly
I can hardly call it a build log. The DJI Naza with the ARF F450 kit goes together in no time at all. The most time consuming part would have to be soldering the ESCs to the main board and that isn't very difficult with the well marked and laid out bottom board. The solder joints to the ESCs are bare and exposed so to prevent any inadvertent shorts, I used hot glue to insulate the connections.
- The kit comes with a couple of wires for you to solder your favourite type of battery connector to the main board with. Before insulating those connections, I also soldered the connections from the Versatile Unit (VU) to the same points.
- ESCs are cable tied directly to the frame. Just connect the three motor wires up any which way and test them for the righ direction later. You've got a 50/50 chance of getting it right.
- I mounted the Naza dead centre in the middle of the bottom board with the supplied foam tape. I ran the wires to the receiver through one of the holes and mounted the receiver on the bottom side of the bottom board. This was purely to reduce the clutter of the wires.
- I mounted the VU also on the bottom side of the bottom board. the idea here is that the VU LED displays important infomation by varying the colour and frequency of the flashing light. By mounting the VU there, as long as the quad is above eye-level and right way up, the light should be visible to the pilot.
- I didn't balance the props. I probably should but I stuck them straight on and I get great results anyway.
- Programming is fairly straightforward with the DJI Assistant software. One thing to take note of, initially I experimented with the X1 & X2 remote gain settings by assigning them to channels 6 & 7 on my Tx. I mistakenly increased the gains to maximum and on the first couple of flights, I was a bit disappointed with the vertical hold. It tended to drift up or down and compared to all the youtube videos I've watched, it was very disappointing. After checking the gain settings, I set them the same as "stockfoodpics" from youtube because he's using exactly the same equipment as me and getting great results with video from his GoPro camera. The settings are "Basic: 150 150? 100 120 & Atti: 70 70 "
