About OpenMV Cam H7 Plus Optical Sensor, need advice

ton999 · January 2, 2021, 5:39pm

I am about to order high quality Optical Sensor, and currently consider two brands : Here optical flow sensor and OpenMV Cam H7 Plus . I have checked documentation of the OpenMV but can not find the high end model: OpenMV Cam H7 Plus. This advance model has higher Image sensor and several types of I/O connection such as I2C and Can. Anybody has experience with this advance optical sensor ? I need advice/recommendation please. Thank you…
Tony

ppoirier · January 3, 2021, 12:30am

Hello,
For opticalflow, I still recommand the px4flow with a TFMINI rangefinder as it offer better distance and accuracy. As for openMV, it depends on the use case, thisi is a great smart camera system for experiments and yes it can be used as an opticalflow as well, but it is lacking resolution for heavy lifting.

I guess you saw this:

ton999 · January 10, 2021, 1:28am

Hi @ppoirier,
Thank you for your response. The problem when using the PX4Flow vers.1.3 is, that when I use Win10 , it does not really compatible. I have problem to connect PX4Flow with Win10, even thought I have followed all instructions as in the documentation. In device manager of Win10 shows the PX4Flow but it has marking that it does not work. However when I uninstalled this PX4Flow and restart the PC, mission planner can connect to the device but in the Px4Flow tab menu there is no camera display (just nothing).
This is strange. Then when I connect with QGC, it works well… Do I miss something in MP ?

About the new OpenMV , in fact it has higher resolution than the PX4Flow . OpenMv Can 7 Plus has 5 MPixels sensor, so I really want to test it, but I don’t know whether it is compatible with Ardupilot… Any advice from experts here.?

ton999 · January 16, 2021, 10:36am

Hello @ppoirier,
Would you mind to give advice on this issues above? Appreciate for any advice…
Thank you.
Tony

ppoirier · January 16, 2021, 10:53am

Hello

Look to me like a win10 driver issue, I posted an updated link to driver on this forum but I cannot find it,

ton999 · January 16, 2021, 6:05pm

Hi @ppoirier ,
Thank you for your response. I did down load the Win10 driver according to the document. Is there any other link/source of this driver? Tks.

ton999 · February 4, 2021, 2:01pm

Hello @ppoirier,
Could you advice me about the Windows10 driver for PX4Flow sensor? I have tried many times installing the Windows driver according to document but in the Device manager of Window10 the sensors have error marks that means the driver is not correct… I strongly believe that my PX4Flow sensor hardware is in good condition…I appreciate any advice to solve this problem.
Thank you…

ppoirier · February 4, 2021, 10:10pm

That is the driver I was using … Hope it is still working

https://drive.google.com/drive/folders/1TosWTqywAntc9hdDv-vowDXzPD3Azf92?usp=sharing

ton999 · February 6, 2021, 1:56am

@ppoirier, Thank you, I will try and will let you know soon.

ton999 · February 7, 2021, 5:11pm

I have installed the driver, but still does not work. In windows10 Device Manager there is no PX4Flow device , which means Windows does not recognize the PX4Flow.
MP also does not recognize it.

Thi_Van · March 9, 2021, 8:40pm

Hi @ton999, I have also tried with the PX4flow for a while and could not figure out how to get it working. I have already installed the driver firmware and calibrated the camera by using an older version of Mission Planner, where it would show me the camera feedback. My problem with the Px4flow was it won’t receive any power when connecting through I2C. It would turn on and function properly when powered from micro USB. There were many peoples who also had the same problem on other discussion boards. I saw online somewhere saying that there is a China’s clone version of the Px4flow that flooded the market that have all of these problems. I have never gotten the Px4flow to work and haven’t seen anyone to get it to work. So good luck with that.
I am now trying to get the H7 Plus optical sensor to work too. So I’ll let you know how it performs compared to the HEREflow sensor, which is also another optical flow sensor that I did manage to get it working but there were a couple of stability issues that the H7 Plus might solve.

ton999 · March 10, 2021, 3:34am

Hi @Thi_Van,
Wow, I am very keen to know performance of H7 Plus Optical sensor and also the HereFlow optical sensor… Based on the specification, the H7 Plus has much bigger resolution than any other sensor in the market today. If you can make it work with Arducopter this is really great news… Please update me your test. Thank you…

ton999 · March 16, 2021, 11:06am

Hi @Thi_Van,
Any update on this topic?? Have you tried the H7 Plus?? or the Here Optical flow?? I am looking forward your update… .Thks.

ton999 · March 16, 2021, 11:33am

Hi @Thi_Van,
I am very keen to know, which one is better and More stable, between the Open MH H7 Plus and the HereFlow optical sensor…

Thi_Van · March 16, 2021, 5:05pm

To @ton999,
I haven’t received the H7 Plus yet. It’s still on delivery but I will try to get it working and give u an update. On the other hand, I’ve been working the Hereflow for a while. The problems I have with the Hereflow are positioning above a certain height and yawing is unstable (not yawing relatively with the center of the drone no matter what FLOWX/Y_Pos parameters I set it to). I am flying using EKF3 like some other peoples suggested but still not much improvement on the yawing. At one point, I think Michael Oborne said that maybe Optical Flow can’t really handle Yaw that well and they will do more updates in the future. The yawing is not that terrible but it’s not perfect. I’ll keep you updated for sure with the new optiflow.

ton999 · March 20, 2021, 10:59pm

@Thi_Van Thank you for sharing the use of Hereflow . I hope H7 plus is better , as it use better image sensor. Currently I am considering to order the CUAV PX4FlOW. I think CUAV is a reputable Company… Let see, whic one is better… Regards…

ppoirier · March 21, 2021, 1:00am

Even if the openMV Cam has higher resolution, the optical flow detection code is 128 x 128 Maximum

sensor.B64X32 : 64x32 (for use with image.find_displacement() )
sensor.B64X64 : 64x64 (for use with image.find_displacement() )
sensor.B128X64 : 128x64 (for use with image.find_displacement() )
sensor.B128X128 : 128x128 (for use with image.find_displacement() )

And with the default python script it is set to 64X32:

github.com

openmv/openmv/blob/master/scripts/examples/OpenMV/18-MAVLink/mavlink_opticalflow.py#L86


    temp = struct.pack("<b31sh",
                       0xFE,
                       temp,
                       checksum(temp, MAV_OPTICAL_FLOW_extra_crc))
    packet_sequence += 1
    uart.write(temp)
    update_led()


sensor.reset()                      # Reset and initialize the sensor.
sensor.set_pixformat(sensor.RGB565) # Set pixel format to RGB565 (or GRAYSCALE)
sensor.set_framesize(sensor.B64X32) # Set frame size to 64x32... (or 64x64)...
sensor.skip_frames(time = 2000)     # Wait for settings take effect.
clock = time.clock()                # Create a clock object to track the FPS.


# Take from the main frame buffer's RAM to allocate a second frame buffer.
# There's a lot more RAM in the frame buffer than in the MicroPython heap.
# However, after doing this you have a lot less RAM for some algorithms...
# So, be aware that it's a lot easier to get out of RAM issues now.
extra_fb = sensor.alloc_extra_fb(sensor.width(), sensor.height(), sensor.RGB565)
extra_fb.replace(sensor.snapshot())

ppoirier · March 21, 2021, 1:05am

Yep I double checked, and the PX4FLOW code we use with ArduPilot is 64X64

github.com

priseborough/px4flow/blob/klt_flow/inc/settings.h#L41


* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/


#ifndef SETTINGS_H_
#define SETTINGS_H_


#include <stdint.h>


#define ONBOARD_PARAM_NAME_LENGTH 		15
#define BOTTOM_FLOW_IMAGE_HEIGHT		64
#define BOTTOM_FLOW_IMAGE_WIDTH			64
#define BOTTOM_FLOW_SEARCH_WINDOW_SIZE 	4


/******************************************************************
 * ALL TYPE DEFINITIONS
 */


/**
 * @brief  parameter access
 */

ton999 · March 21, 2021, 3:45am

Hi @ppoirier,
Thank you for your info… So are you saying that the usage of bigger image sensor has no effect? How about changing the lense with let say 2X zoom to get better image at higher altitude (about 100 meter)? Thank you…

ppoirier · March 21, 2021, 10:25am

You can change lens but it will impact on maximum speed measurement as indicated here
https://docs.px4.io/master/en/sensor/px4flow.html#optics

And you need a 100M lidar