Hi,
I have a 450 quad with APM 2.6 and Arducopter 3.2.1. It is fitted with a LIDAR-lite module as an altimeter. The LIDAR module is interfaced with an Arduino Nano, which in turn outputs an analog voltage proportional to altitude (PWM/RC network) to the APM. The Arduino also outputs to a tricolour LED for checking and calibration. The device produces a reliable and accurate sonar altitude reading when the quad is connected to Mission Planner. The sonar altitude limits are set to 20cm to 4m. The quad has excellent vibration performance.
When I set it in AltHold mode the performance is worse than I would expect. The attached log graph shows an AltHold run for about 3 minutes. AltHold was engaged at about 1.8m at the point the DSAlt moves off the baseline, and disengaged at the point "Stabilize" is marked. During that time the throttle on the radio was not touched.
The SAlt and BarAlt initially are near identical suggesting the LIDAR/Arduino is working well. The BarAlt then diverges slightly. I expect this is simply some zero drift as the SAlt more accurately portrays the actual altitude profile. However, the quad drifts about 1.5m either side of the original set point. In addition the DSAlt increases in 7 steps to almost twice the starting value, with no throttle changes.
Could anyone give me pointers as to how to solve a) the poor performance in AltHold and b) the unstable DSAlt please?
I am a newbie to forums so apologies if I have missed an existing post on this, but I did look quite hard!
Duncan
Replies
Hi Steven,
Apols for the delayed reply. I have not really made any progress on this, and specifically I can't find out why the DSAlt is resetting itself.
Cala was asking about power supplies. My Lidar unit is powered via a standard 78 series voltage regulator with appropriate capacitors either side of the IC (essentially a BEC).
If you have a Lightware you are lucky, perhaps Laserdevelopment user can help you He have a big contribution to this forum and is the developer of that RF , I have the old Lidar Lite, that was discontinued as soon as I recived :(
PD: sorry, I can't erase the duplicate answer if any moderate can do please? forum is not working well here.
@Cala - it's time you had an SF11/C of your own to test. Your contributions especially in agricultural uses of drones are very valuable and we want to support that market sector. I've PM'd you with the contact details to get a free unit.
:D :D :D :D THAAAAAANNNNNKKKKSSSSS!!!!!!!!!!!!!!!!
Hi I have a lightware SF11/c lidar connected via Serial4. It's powered via a separate BEC. With lowering the gain, do you main RNGFND_GAIN ?
Hi Duncan did you ever solve this issue? I'm having the same issue I think.
Hello Steven, I'm in the same way too, I have a new Lidar having same issue, I've connected by pwm and powered on the same esc-bec rail; some weeks ago I asked this and Randy recommends to try lowering the gain, I'm in winter with rainy days here and I couldn't try yet, keep in contact if you can solve it, I share if I can.
How do you power your Lidar?