Jean-Louis Naudin did a cool loiter comparison test of the Cheerson CX-20 (Quanum NOVA) Phantom clone with APM running ArduCopter 3.1.2 vs the DJI Phantom.  Not bad!

Needless to say, newer copters with Pixhawk and more recent ArduCopter code do even better ;-)

Views: 4835

Comment by Euan Ramsay on June 2, 2014 at 11:55pm

This does put the DJI on the back foot a little - an out-the-box quad that can hover/fly as well as the phantom, can carry the same loads, yet has more autonomous programs and is considerably cheaper.

Lift the compass/gps module a little, run compass mot etc, and it will improve yet further I recon.

Having said that, the test is not optimal - one has a camera onboard, the other doesn't. But its still a good demo.

Comment by Quadzimodo on June 3, 2014 at 12:25am
DJI are certainly on notice, as are everyone else hoping to gain or simply maintain a footing in what is soon to become a highly competitive market segment.
Comment by UAS_Pilot on June 3, 2014 at 7:52am

One thing I noticed in the video is the DJI kept slowly losing altitude and Jean even had to fix it once. DJI is not impressing me and it never did. I prefer the APM and PixHawk systems over DJI any day...

Comment by Angelo DP on June 3, 2014 at 10:24am

Can we say this is only a GPS module comparison ???

Angelo

Comment by Pedals2Paddles on June 3, 2014 at 10:34am

The compass on that craft is not integrated with the GPS module.  The compass is in that little tower, the GPS is inside next to the flight controller.  I'm not sure anything would be gained by altering the GPS mounting.  It isn't really sensitive like the compass is.

Also, the altitude hold is based more on barometer and accelerometer than GPS.  So no, it is not "only a GPS module comparison".

Comment by Jack Crossfire on June 3, 2014 at 12:42pm

Randomly pointing the camera in different directions definitely helps, though they both looked awful.  GPS IIF sucks.

Comment by Julien Dubois on June 3, 2014 at 1:53pm

Unfortunatelly, his comparison is incomplete and sorely lacking in technical analysis.

It would be interesting to compare them dynamically, as static GPS performances is different than the dynamic ones.

Some relevant things to check/compare:

- HDOP and NbSats during high angles input (eg in Alt_Hold or Hybrid mode)

- Altitude stability: is there any altitude drop when you go forward and release pitch (or pull stick back).

- Maneuverability

- Payload

- Autonomy

- ...

Comment by Al Ros on June 3, 2014 at 4:23pm

Hmm

I have been away from APM since last summers firmware and I just finished testing Loiter in firmware 3.1.5 on APM 2.5 compared to naza. Basically APM takes a more aggressive approach to position hold. So It does seem more "accurate", but NAZA is much more smooth and deliberate. Both are good understanding that their approach is a bit different. I am sure I can play with gains to smooth out APM also.

The real Problem I am having with APM loiter that I would like input on is with moving the stick while in loiter to reposition the quad. I have to say again NAZA takes a smooth approach to this as well. so that it smoothly glides to a stop and stays there. The faster you move the quad, the longer the stopping distance. It sort of models momentum.

My APM is doing something strange. It comes to a stop in "waves". When you let go the stick, it will brake more aggressively, then levels while still moving and then oscillates in a lower amplitude until it stops. It makes it unpredictable. I could not find a setting that would allow me to adjust the aggressiveness of the stop - can you point me to one?

Lastly with NAZA when you are on the sticks in loitre mode, it feels like you are in complete control just as if you are in stabilize mode with alt hold. But with AMP I am finding that it is sluggish and delayed so that you can get into pilot induced oscillation and overreaction . Again I really want My APM to work well - so please don't interpret my comparisons as any way bashing it (I have owned several of each hardware versions and have the pixhawk on order). I am looking for help to get it to fly well.

Al


Developer
Comment by Randy on June 3, 2014 at 5:34pm

@Al Ros, re moving around in Loiter, you'll probably appreciate the "Hybrid" mode that is coming in AC3.2.

Comment by F1P on June 3, 2014 at 8:26pm

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