Connecting i2c device on voxl2
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@Alex-Kushleyev Yes Alex Noted.
We were flying okish since last few days and we had another crash similar to last one. While we are seeing into our propulsion system design (motor propeller and battery), Aircraft this time flipped midair and the reason is absolutely unknown. I just wanted to eliminate if PWM outputs were given correctly to motors from M0065 in below shown flight while it crashed towards the end? I just wanted to check if PWM outputs were all above 1100 and none of the motor was commanded below the same. My VOXL2_IO_MIN and MAX are 1100 and 2000 respectively. Just eliminating any software problem over here once again. Let me know if you can help
Log : https://review.px4.io/plot_app?log=d9d7feb3-9e5a-469f-ac95-a4914a243fbe
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@Aaky ,
I took a look at the log, the case seems a bit complicated. It seems the issue starts 6:38:500 when there is a sudden jerk that appears in Roll Rate, see here :
As a a result, the vehicle tries to counter act and responds in actuator outputs (negative roll command to counteract the positive roll rate spike)
This causes a sudden change in requested motor commands:
After that the vehicle starts oscillating and motor outputs are saturated. To me, it is unclear where the spike in the roll angular rate comes from after very low-noise fligiht. It is almost if something suddenly got loose, snapped, or hit the flight board, causing that angular rate spike. If the flight board became loose, it would have been impossible to stabilize the vehicle after that.
Since you are using 3rd party ESCs, we do not have motor feedback, so we cannot tell if the motors performed well, but it does not look like the motors stopped, as the vehicle appears to start oscillating back and forth in roll initially. Also, if one or more motors simply stopped, we would have a smooth tumble - instead we are seeing a high roll rate impulse that seems to case oscillations and then the crash.
I would suggest to inspect the vehicle and look for potential sources of that initial roll rate jerk that may have caused the oscillations and then crash.
Alex
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Even though it is not clear what the initial roll rate spike came from, it seems that it served as an impulse test of the attitude controller and the vehicle started oscillating. If nothing actually came loose during the flight, this may suggest that your attitude controller is not stable and given an large disturbance it can become unstable. There are many unknown variables, but you may need to increase your D gain in your attitude controller to dampen the response. However, still, it is still not clear where the original roll rate impulse came from here..
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@Alex-Kushleyev Thanks for your analysis Alex. This is somewhat a mystery for us as well. Actually in terms of motor saturation, I feel motor saturation started first at timestamp 6:38:560 onwards motors had started to struggle leading to roll failure. We are suspecting if propeller broke in flight, since it was not in our visual sight flying 200 meters away. We flew with another set of propeller at very high speed again and things were all normal this time. There isn't any concrete answer to this just speculations as of now.
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@Aaky Yes, it seems something "mechanical" happened right before the flip. a broken prop may cause impact on the frame and detected by the gyro as that spike. I am glad the vehicle is flying normally again! Regular inspection of the vehicle components is recommended
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A Alex Kushleyev referenced this topic on
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@Alex-Kushleyev Definitely Thanks for the support.
On a seperate note, I have one more query. I have a gimbal which expects PX4's Attitude to be fed into it for better attitude control of gimbal (Typically every good gimbal expects Autopilot's attitude to be fed into it). So for this my gimbal has UART port which can capture mavlink packets been broadcasted by autopilot and act accordingly. Can we do this integration using VOXL's ESC UART port to broadcast mavlink packets into my gimbal's UART port in the same way like any Pixhawk Cube based Autopilot running PX4 can output mavlink packets over telem port?
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@Alex-Kushleyev Alex, Along with above query I wanted to consult one more point with you. With new updated M0065 firmware supporting OneShot and we using this ESC from Tmotor F45A. Are they both fully compatible? I suppose this ESC even supports Dshot but not sure about OneShot. Actually we are been facing hard time with vibrations on our aircraft. We tried different dampeners, referred sentinel dampeners, tried different propellers like 9 to 11 inch but vibrations aren't going away so just wanted to check if our ESC is fully compatible with Oneshot first. Just FYI we had extremely less vibration when we flew for the first time with our custom drone with older M0065 firmware (voxl2_io_firmware_m0065_v1_35_58c82813.bin) and 11 inch propeller but now when we are trying to replicate the same setup we are facing extreme vibrations. I also read you comment over here about Oneshot increasing the update rate possibly picking up more gyro noise. I checked by going back on older firmware and older px4 branch but no luck over there as well. Anywhich way even with Oneshot aircraft is able to fly solid but only problem is vibrations going high. Let me know your thoughts.
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@Aaky , i will be back to office on Wednesday and will follow up with replies to your questions.
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@Alex-Kushleyev No problem Alex.
In the meantime @Eric-Katzfey if you can provide me some insights on my following query ?@Aaky said in Connecting i2c device on voxl2:
I have one more query. I have a gimbal which expects PX4's Attitude to be fed into it for better attitude control of gimbal (Typically every good gimbal expects Autopilot's attitude to be fed into it). So for this my gimbal has UART port which can capture mavlink packets been broadcasted by autopilot and act accordingly. Can we do this integration using VOXL's ESC UART port to broadcast mavlink packets into my gimbal's UART port in the same way like any Pixhawk Cube based Autopilot running PX4 can output mavlink packets over telem port?
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@Aaky If you are running PX4 on VOXL2 then you cannot use the DSP UARTs outside of PX4. And within PX4 all data is transferred as topics, not mavlink. To do what you want you need a UART on the apps processor side (available on certain add on boards) and have voxl-mavlink-server route the appropriate mavlink messages to it.
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@Eric-Katzfey Okay. So normal Telem ports as they are available on Pixhawk Autopilot running vanilla PX4 arent available on VOXL-PX4? The application processor side integration sounds complex to my architecture since I already have one Add-on board sitting over VOXL providing USB connection for my Doodle labs radio. Any other feasible option?
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D Denver Bennett referenced this topic on
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@Aaky Correct. VOXL2 uses UDP for it's Mavlink telemetry, not UART TELEM ports like on a microcontroller based autopilot. But, voxl-mavlink-server should be able to route Mavlink messages over an apps processor based UART such that it would be similar to a TELEM port. Which add-on board is it? Is it something custom or one of our boards?
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@Eric-Katzfey Thanks for the information. The add on board is Microhard modem B2B board without any Microhard radio in it acting just as USB port provider for my doodle labs modem. How can I get UART port if I am using this board?
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@Eric-Katzfey Eric, Say I connect UART from this expansion board, What all changes I need to do in voxl-mavlink-server in order to broadcast PX4 attitude mavlink packets to my gimbal? I understand this UART is meant for external flight controller communication so will it work straight out of the box?
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@Aaky That is not a standard configuration that we test with so likely will not work out of the box. But it shouldn't be too hard to adapt voxl-mavlink-server to your use case. And if you make changes that you think would benefit other users we would gladly accept a Pull Request with the updates.
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@Aaky Yes, you could use the UART exposed on that M0125 expansion board.
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@Aaky The Microhard board does not expose an apps processor UART but you could use a USB to UART adapter to connect to the Gimbal via one of the USB ports.
