Servers by jDrones

Cheerson CX-OF low cost optical flow sensor testing


(ppoirier) #41

Yes altitude holds by tfmini
Set ekf3 altitude source to rangefinder

(rmackay9) #42

Nicely done. Strange that EK2 didn’t work, it should.

I just want to be clear to others reading this thread that I recommend EKx_ALT_SOURCE be left at the default of 0 (for barometer). It should not be set to “1” for Rangefinder.

In @ppoirier’s test environment which is indoors with a flat floor it’s perhaps OK but in 99% of situations I do not recommend setting the altitude source to range finder. I dealt with yet another user support issue yesterday caused by a user setting this parameter to range finder. I feel like I’m constantly fighting a battle to stop people from changing this parameter because it rarely goes well.

(ppoirier) #43

Yes I agree about usage of the rangefinder as the primary altitude source is not recommended for normal flights.

I generally start tests in stabilize , doing the usual trim and PID land, check the logs, confirm rangefinder reading and stability and then use it as primary source.

Start in stabilize, takeoff and then switch to alt hold, check for stability and response. Land and takeoff in alt hold mode to confirm.

As for loiter, set ekf home , hold quad a simulate a flight , confirm that vehicle movements ate showned on map. Takeoff in AltHold , make sure vehicle is stable and switch to Loiter, get ready to switch back.

Last test I did is takeoff in guided an did different guided “fly to” and land.

(Weiyao Lu) #44

Any kind soul able to nudge me in the correct direction for downloading 3.7 Dev?
I have a few CX-OF sensors that I would love to integrate to a pixracer to offer more test results.

Thanks yall! (Happy 2019 everyone!)

(rmackay9) #45


We included CX-OF support in Copter-3.6.4 so it’s available in the stable release. I’ll update the notes above, thanks!

(Weiyao Lu) #46

awesome sir!
I’ll load it up to get it tested!

(Andrea Belloni) #47

What I described above as a strange behavior:

… when I switch from Loiter to FlowHold I see the Copter oscillate quickly in roll and pitch (like if the Roll / Pitch PID was bad tuned), then if I move the quad a little bit around (with RC) the oscillation disappear and the Copter remain stable.

should be a normal behavior from what I read in the wiki:

Because no Lidar is used in this mode, the optical flow sensor is used both to estimate the vehicle’s height above the surface and the vehicle’s speed. Soon after takeoff or after there have been large changes in the height above the surface the vehicle may wobble as it learns the new height and velocity.

Cheerson CX-OF - Flowhold - Whobble
(ppoirier) #48

Well, that is a proof that the wiki is pretty complete , thanks to @rmackay9

BTW I see you can adjust parameters

(Gino Nencioni) #49

hi @ppoirier could kindly explain me how to force the drivers to “other board”…thx in advanced!

(ppoirier) #50

In order to force the sensor on these board, you have to copy and paste line 108 to line 122

(ppoirier) #51

I think @rmackay9 is working on a PR for this

(rmackay9) #52

I must admit that I don’t actually know exactly what’s required to make it available for all boards. Perhaps it’s moving this chunk to be below the “#end

if (backend == nullptr) {
    backend = AP_OpticalFlow_CXOF::detect(*this);

(Gino Nencioni) #53

Big thx!!!
Now works fine!!!
Thx Again.

(Andras Schaffer) #55

I can confirm it does not get detected on MiniPix either.
Apparently AP_FEATURE_BOARD_DETECT is 0 on a number of ChibiOS boards. Moving detection outside of the #if AP_FEATURE_BOARD_DETECT makes it detected.

(Amit Asayag) #56

Thanks, this looks great.
Does the optical flow sensors can be use for an autonomous mission without GPS like the Zed camera?

(rmackay9) #57

@Amit, yes, but like the ZED camera there will be some position drift and that drift increases if the vehicle flies higher… so it will probably work OK if the vehicle stays below 20m and the mission isn’t too long.

(Andrea Belloni) #58

@rmackay9 This is true only with optical flow + range finder, with only optical flow in flowhold is not possible, do I understand well?

(rmackay9) #59

@anbello, with optical flow + range finder all modes should work without GPS including Auto mode. FlowHold mode will work even without the rangefinder.

(Andras Schaffer) #60

@rmackay9 Any news on EKF switching to optical flow only in case of in flight GPS failure ?

(rmackay9) #61

@Eosbandi, No progress on that issue I’m afraid. I think the first step is probably to confirm whether the issues exists when using EKF3. txs!