Three questions (answered)
« on: July 20, 2017, 05:39:16 pm »
Three questions
1. Is there any way to keep motors running when using a Spectrum satellite receiver when the signal is lost? Mine drop to zero when I turn off my transmitter.
2. I have a DJI Naza clone, what should be my baud rate on the "Hardware" tab?
3. My "position hold" works well but my "return to base" works with a pendulum effect.  The quad overshoots and then oscillates back and forth trying to find the base position.  I have tried your "dirty" firm ware but it didn't fix it.  It did improve the "Velocity Roam" which also results in oscillations if traveling fast.

I got these questions in a PM.  It is probably better to post questions in the forum so that others can add comments or learn from the answers.  Some people may think that they are asking a stupid question or are shy.  Don't worry about it!  Just ask nicely in an appropriate place.

1A. First of all, be aware that when it looses RC signal, it must have an automatic command that brings it down or your bird just flew away, never to return.  Some RC equipment has only one setting and that is to maintain the last transmitted stick positions.  That is the worst possible way to handle this.  There is no way for the FC to know that it is out of range and flying away.  Betters systems have failsafe settings that allow you to go to known stick positions (e.g. low throttle) if it goes out of range...  I suspect that the Spectrum sat rx doesn't do failsafe or that would be one way to set up this failsafe (using RC failsafe) that you probably would have done already.  It sounds like it does simply stop sending servo pulses when the transmitter is out of range.  That is good.  The FC uses this to go into an FC based failsafe.  The way to set up FS in the FC (that does the same thing as the receiver failsafe) and gets triggered when the RC receiver stops sending signals to the FC (like some do when the transmitter is out of range) is set up in Input -> Failsafe.  Revo class FC's that have GPS completely configured can do Landing mode here as perhaps one of the best options besides dropping out of the air.  I like to add a little yaw to the FS so that I quickly know that it is happening if I see it in FPV.  Left yaw to the RC failsafe and right yaw to the FC failsafe to be able to tell which one it is.

2A. The baud rate of 57600 is automatically set, so it doesn't matter.  DJI/Naza GPS has a fixed baud rate.

3A.  I would look into tuning the VTOL PIDS at System -> Settings -> VtolPathFollowerSettings -> *PID and *POSP.  If it works well in VR, then it may be that the Brake PID needs adjusting?  Play with them all, but set each one back to defaults before moving on to the next one.
« Last Edit: July 21, 2017, 05:11:53 pm by TheOtherCliff »

Re: Three questions (answered)
« Reply #1 on: July 21, 2017, 12:04:37 pm »
Thanks Cliff....Great to have someone with your vast knowledge of LP.
LJI S380
4 LDPower 2312 - 960KV
4 FlyColor Raptor 30A
Lemon DSM Sat
2200 4S1P Battery
9443 Props
Round WS2812 RGB


  • *
  • 6
Re: Three questions (answered)
« Reply #2 on: August 03, 2017, 04:05:29 pm »
I have a problem with the RTH + Hold (next command) that resembles the third point mentioned above
First, my position hold work well.
When the quad arrives above the zone of take-off, it then tries to stay above the zone but with energetic pendulum and oscillation movements in all direction.
If I try RTH + Land (next command), everything seems normally.

I would like to know if anyone has a solution ?
Revo+GPS V9,Tarrot Iron man 650mm, cobra 750kv, esc: rotorgeeks 30A BLHeli, batt. 4S 5500ma, props: 13-4.5, cam: mobius, poids 1.8 KG

Re: Three questions (answered)
« Reply #3 on: August 04, 2017, 05:33:53 am »
I thought/assumed that PositionHold was basically the same code as RTB-Hold, but I haven't actually checked the source.

When testing oscillations, I usually use VelocityRoam mode which is the same as PH if you leave the sticks centered in VR.

There are several things to look into:
- Try switching into PH when flying faster (like human running speed).  It sometimes just takes a bit of initial velocity to get the oscillation to start.
- Try switching into PH when faster and at different compass headings.  There is an issue with facing east west that you may be experiencing.
- A slow baud rate or changing any of the GPS settings may cause issues.
- Did you try changing the settings mentioned above in 3A to see how they affect your flight?
- Plug in battery and USB and go to Attitude -> Magnetometer and make sure that the sliders all stay within say +-3 no matter where you rotate the aircraft.
- Do you have absolutely ALL your high current (motor power) wire pairs/triples twisted from battery to motor?  Leaving them untwisted will give you green mag on the ground, but a flight load will make the mag health show that it is bad.


  • *
  • 6
Re: Three questions (answered)
« Reply #4 on: August 04, 2017, 04:12:01 pm »
I also believed that hold (next command) was similar to position hold but there seems to be a difference.
I will do some testing with velocityroam and the other three points and I will communicate the results soon.

I put a link to see the problem. The quad arrives slowly in RTH and when it arrives above the zone of takeoff, it seems to pass in mode (hold next command) and you can see the oscillation and then I take the control manually for the landing.

Thank's for your help
Revo+GPS V9,Tarrot Iron man 650mm, cobra 750kv, esc: rotorgeeks 30A BLHeli, batt. 4S 5500ma, props: 13-4.5, cam: mobius, poids 1.8 KG