flow deck v2 not working outdoor

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zhanghaijason
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Posts: 52
Joined: Fri Jul 28, 2017 9:07 pm

flow deck v2 not working outdoor

Post by zhanghaijason »

Hello,
I have a flow deck v2 which works well indoor. But When I use it outside even with just a little wind, it will just fly up and down. I uploaded two videos : https://drive.google.com/file/d/18oo_-h ... sp=sharing .Seems the distance sensor on flow deck is not working properly outdoor. Another possible reason I can see is the delay from the Crazyflie Client. The client shows the orientation of CF changing for 3 or 4 seconds even after I laned it. I am wondering do anyone know that possible reason? Thanks.

kimberly
Bitcraze
Posts: 470
Joined: Fri Jul 06, 2018 11:13 am

Re: flow deck v2 not working outdoor

Post by kimberly »

Hi!

That is indeed strange behavior. Have you tried it on a different surface? Grass tend to reflect sunlight and since the distance sensor works on IR light, it might be effected.

It is probably not the delay from the cfclient, as all the control with the distance sensor in the loop is all done fully onboard. It might be that your crazyflie is sometimes losing connection, but you will need to check the link quality. But I would guess it is more due to the surface though.

Let us know if you find out more! You can also post a plot of the distance sensor and state estimation of the z position here as well if you manage to make one.

zhanghaijason
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Posts: 52
Joined: Fri Jul 28, 2017 9:07 pm

Re: flow deck v2 not working outdoor

Post by zhanghaijason »

kimberly wrote:
Mon Apr 27, 2020 8:30 am
Hi!

That is indeed strange behavior. Have you tried it on a different surface? Grass tend to reflect sunlight and since the distance sensor works on IR light, it might be effected.

It is probably not the delay from the cfclient, as all the control with the distance sensor in the loop is all done fully onboard. It might be that your crazyflie is sometimes losing connection, but you will need to check the link quality. But I would guess it is more due to the surface though.

Let us know if you find out more! You can also post a plot of the distance sensor and state estimation of the z position here as well if you manage to make one.
Hi Kimberly,
I tried on flat concrete surface outdoor. It did the same. And I use the client plotter to view the zranger. I can see that it can reflect the height correctly indoor. But when outside on the concrete surface, I can see the zranger output vibrates, it vibrates between 800-5000 when I use my hand to hold it in the air.

kimberly
Bitcraze
Posts: 470
Joined: Fri Jul 06, 2018 11:13 am

Re: flow deck v2 not working outdoor

Post by kimberly »

Oke, then I'm afraid that the infrared light of sunlight is indeed affecting the sensor's readings....

The strange thing is, is that you are saying that you also see readings in the 5000 mm. This is checked before sending it to the kalman filter here:https://github.com/bitcraze/crazyflie-f ... er2.c#L139

So I guess it also received values underneath this threshold of 5000. You can try to get set even lower.

Have you tried different distance modes in the initialization ? (https://github.com/bitcraze/crazyflie-f ... er2.c#L123). now it is set on medium, but there are more to consider (see here)

zhanghaijason
Member
Posts: 52
Joined: Fri Jul 28, 2017 9:07 pm

Re: flow deck v2 not working outdoor

Post by zhanghaijason »

kimberly wrote:
Mon May 04, 2020 9:35 am
Oke, then I'm afraid that the infrared light of sunlight is indeed affecting the sensor's readings....

The strange thing is, is that you are saying that you also see readings in the 5000 mm. This is checked before sending it to the kalman filter here:https://github.com/bitcraze/crazyflie-f ... er2.c#L139

So I guess it also received values underneath this threshold of 5000. You can try to get set even lower.

Have you tried different distance modes in the initialization ? (https://github.com/bitcraze/crazyflie-f ... er2.c#L123). now it is set on medium, but there are more to consider (see here)
Hi Kimberly,
I didn't try other mode. I will. And I have one more question, what is the unit of the output of the flow sensor dx day, are they mm/s?

kimberly
Bitcraze
Posts: 470
Joined: Fri Jul 06, 2018 11:13 am

Re: flow deck v2 not working outdoor

Post by kimberly »

The motion sensor outputs as the shift in 'pixels per frame'. Here is a nice overview on how the flow is translated to velocity (important for the kalman filter's measurement model : https://www.bitcraze.io/documentation/r ... /#flowdeck

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