HereFlow Optical Flow Sensor Testing

When you say “stick with Loiter” do you mean loiter but with flow only, and no GPS?

@vosair,

Yes, Loiter should perform better than flowhold even when using optical flow.

i see, i mounted the sensor right on the middle of the chassis, i also calibrated the sensor using the flowX/bodyX, and flowY/bodyY, it diden’t work, and then i i tried to reflash the firmware and followed the same steps, it worked fine but it needed some tuning on the flow rate, and here we have a problem which is: i dont know why it diden’t work before and now it does, since it’s the same parameters, second, i was just trying to clean the desk and i picked up my quad without noticing that the cube was plugged to the pc, “boom connecter gets out from the cube” , i tried to open the cube to resolder the usb connecter, the moment i opend the cuber, an ic got damaged along with a via and a trace, now i dont know what to do, i tried to find the bottom circuit of the cube black online, but all i can find is a cube for 200 dollars

Hi~ rmackay9
indoors, I want to try HereFlow sensor upward.
parameter have FLOW_ORIENT_YAW, Can’t choose upward.
maybe can Reverse AP_OpticalFlow_HereFlow.cpp flowRate.y?
Do you have any advice for me~ Thanks

@WangLouis,

I’m afraid that we don’t support upward facing optical flow. I’ve added an issue to the to-do list here but I can’t make any promises of when it will be done.

If you’re looking to do bridge inspection (or similar) I think the best solution we have is to use the Intel T265 with Copter-4.1 and setup the GPS/Non-GPS transitions. I think this could work quite well.

@rmackay9
Thank you for your reply and suggest.
I tried to fly under the bridge, but if under bridge have water flow, optical flow & lidar data is bad.
I will try to do this issue and keep the track of issue.

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Optical Flow requires low reflectivity and good texture in order to process correctly velocity estimation. It seems that this overpass structure doesn’t offer the desired requirements.

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@WangLouis,

Thanks, I love the video. I would very much like to improve our optical flow support because I think it should work in the situation you’re testing. Realistically I think the next improvement I’ll make to optical flow support is improving our method of calibration and adding a lua script to better support automatic switching between GPS and optical flow.

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I’m also having a drifting problem with the HEREFLOW. There is a small constant drift in whichever direction the Hereflow camera is facing. For example, I have the camera side of the Hereflow pointing at the nose of the Pixhawk Cube and the drone would drift forward. Then when I flip it around 180 degrees and changed the Flow_orientation to 18000. It starts to drift backward. This is when I noticed that the OF.bodyY line is smaller than the OF.flowY. I followed the calibration process and try to change the FlowY_scaler so that OF.bodyY & OF.flowY would line-up but the number of FLowY_scaler doesn’t seem to change anything on the graph. Let me know if you want to see the logs.

Hi @proficnc
I am interested to use your HereFlow, but on your website I can not see the size of the sensor in Pixel . Can you please clarify about the Camera and sensor size in Pixel number? Is it 640x320 px or 752 x 480 pixel or maybe other size ??
Tks.

Hello WangLouis, I’ve been working with the hereflow for awhile now and I couldn’t solve the drifting problem with the Hereflow. Did you ever get the Hereflow to work correctly? I would be very appreciated if you could share me some tips

@Thi_Van,

in my experience with the flow sensors, it is very important to do the calibration properly (which requires looking at the log files) and also setting the FLOW_POS_XYZ parameters.

My hereflow works well.

I was flying over grass which I’m not sure is the best texture for it. Also I’m using TFmini Lidar. Followed the wiki and it pretty much worked out of the box.

Malc

I’m currently have a drifting problem with the HEREFLOW. There is a small constant drift in whichever direction the Hereflow camera is facing. For example, I have the camera side of the Hereflow pointing at the nose of the Pixhawk Cube and the drone would drift forward. Then when I flip it around 180 degrees and changed the Flow_orientation to 18000. It starts to drift backward. This is when I noticed that the OF.bodyY line is smaller than the OF.flowY. I followed the calibration process and try to change the FlowY_scaler so that OF.bodyY & OF.flowY would line-up but the number of FLowY_scaler doesn’t seem to change anything on the graph. Let me know if you want to see the logs.

does your hereflow work indoor (without GPS)? if so, how does it perform? My main goal is to have it fly indoor similar to those DJI Phantom. However, I’m having a drifting and yawing problem. The drift is related to which direction the camera side of the Hereflow is pointing (I explained this issue in more details on the comment above). The yawing problem is related to the position of the Hereflow relative to the center of the drone. It does not yaw relative to the center. I’ve measured and set all of those POSITION parameters but still now luck. I wonder if there has been a manufacture defect on my Hereflow.

here is what mean by the OF.bodyY is smaller than OF.flowY. No matter what value of FlowY_scaler I change to, I still get the same result.

Hi all, on my miniquad 3" i use this optical flow similar (the same?) heraflow. Works well indoor an outdoor (tested at 26m of altitude), but if i use this with TF Luna lidar (benewake), the behavior is unstable, and often leans in roll or pitch and becomes unmanageable.

This is only optical flow:

Here i post the log and pics

This is my optical flow module

https://it.aliexpress.com/item/33005508643.html?spm=a2g0o.productlist.0.0.43ae73f85kNr5K&algo_pvid=1d838233-7151-4fa3-a44d-844634163803&algo_expid=1d838233-7151-4fa3-a44d-844634163803-8&btsid=0bb0623416102088667053740ebba9&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

@bugobliterator, @rmackay9, any suggestions for the scaling issue?

I can confirm the same issue regarding scaling. Some of my hereflow have the drift issue as well.

All I can say really is that the calibration and setting of the FLOW_POS_X/Y/Z is very important and greatly affects performance. It is also important that the rangefinder provide accurate values with few glitches.

I also don’t think that FlowHold mode works well for most users and I’ve toyed with the idea of removing it. Too many users have issues with FlowHold that it causes a significant support burden and leads to unhappy users.

I’ve got it on my to-do list to add an inflight flow calibration routine that would help users get a more accurate calibration. The code is not simple though and it would also require the users at least temporarily attach a GPS.