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Optical Sensor Calibration Fail and Vanishing Camera Image in DJI Go4

Conservative Nihilist

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Greetings fellow brethren of the M2P. I recently took delivery of a used eBay Mavic 2 Pro, and have been going through the usual calibrations of the compass, IMU, and camera gimbal, all of which went smoothly. When it came to calibrating the optical sensors, however, things didn't go quite as well.

Using DJI Assistant 2, I had the drone connected to the computer via the USB cable and immediately noticed something was wrong because while DJI Assistant 2 recognized the drone as an M2P, the usual list of firmware updates did NOT appear on screen, and there was instead an error message indicating that the firmware list could not be found. It was only when I connected the drone via DJI Go4 that I found out the latest firmware is installed, and designated with 790 as the last three digits. I then tried to carry out the sensor calibration procedure, which also failed.

Selecting the optical sensor calibration process in DJI Assistant 2, the checkerboard screen never materialized, and instead, I was presented with a 3-step tutorial on how to calibrate the optical sensors, which was the only function that became active when I tried to calibrate the optical sensors. Since there was no indication of a calibration of the optical sensors being essential, I skipped that step and decided to take the drone outside for its first test flight, which also did not go well at all.

During my indoor calibration procedures, the controller, drone, and iPhone all linked up seamlessly with a crisp camera image visible on screen, and the camera gimbal responded as expected to my turning the thumb-wheel on the controller to adjust the camera pitch up and down. When I took the drone outdoors, however, the camera image never materialized, and I was instead confronted with a black screen and a warning of a disconnect between the drone controller and the iPad. With no camera image and no telemetry, I then decided to take a short flight within visual range, just to see how the drone flies. There were no anomalies to report during that flight, but there was no camera image to see until I ended the test.

I am writing to this forum in the hopes that M2P owners with more experience than I might be able to figure out why there was no checkerboard screen image visible in DJI Assistant 2 when I attempted to calibrate the visual sensors of the drone, but more urgently than that, I am curious to find out why this drone that produced a nice crisp camera image during my indoor calibration procedures, suddenly blanked out that camera image when I went outside for a flight test. Any thoughts on what needs to be done here would be greatly appreciated. Thanks in advance for any insights that can be offered. For now, the drone is essentially grounded, but I am still optimistic that the fix to these issues will be a simple one.

I posted this same inquiry at another website, hoping to reach a wider audience of DJI Mavic 2 Pro owners whereby the reply to the above questions might appear sooner.
 
I learned recently that Mavic Pro collision avoidance sensors sometimes false-trigger, interrupting smooth flight when the sun sits close to the horizon. Since all the antique DJI drones in my hangar are devoted exclusively to flying Litchi autonomous missions whose altitudes are carefully set to be least 20 feet above all obstacles along the flight path, I routinely disable all collision avoidance sensors with the exception of downward looking landing assistance sensors on my Mavics before launching them to fly autonomous Litchi missions.

The checker-board screen that DJI Assistant 2 presents for visual sensor calibration was inexplicably replaced with a completely BLANK screen when I attempted to calibrate the myriad sensors dotting the chassis of this Mavic 2P, despite that checkerboard screen having appeared as expected for the sensor calibration that I did for my Mavic 1P recently. Being impatient to fly this drone for the first time, I simply omitted the sensor calibration and was therefore alerted as such by a sensor calibration warning message displayed on the Litchi screen throughout the drone's maiden Litchi mission completed this morning.

The Litchi flight path I created lasted just 15 minutes, and I am elated to say this Mavic 2 Pro flew smooth as silk over the soaring concentric circles I programmed it to trace in the skies while the camera focused on my humble abode occupying the hub of the wheel, as it were. The drone's landing approach stability was a source of concern due to my having disabled all the collision sensors, save for the downward looking ones, so I kept a very close watch on the pitch and throttle responses as I commenced a steep glide slope using feather light inputs on the controls. This Mavic 2 Pro handled smooth as butter with no abrupt lurches all the way to touch-down on my plywood landing pad. That precision landing was a sight for sore eyes that dispelled all my earlier worries relating to the absence of collision sensors.

Because the previous owner of this drone had already installed the latest .790 M2P firmware before shipping the drone to me, I had been concerned about such a recent firmware edition preventing the drone from linking with Litchi, as I had earlier noted with dismay for both of my M1P's before I used a freeware drone hacking facility to roll them back to MUCH earlier firmware editions that restored connectivity to Litchi. My worries of seeing a similar Litchi lockout were completely unfounded in the case of this Mavic 2Pro, which I can now confirm WILL connect seamlessly with Litchi even if the latest .790 M2P firmware is installed with all its hack-proof anti-rollback features in place.

In conclusion I am delighted to finally own a Mavic 2 Pro that flies and lands with silky smooth precision despite my inability thus far to calibrate the position sensors that I'll never need to deploy anyway, given the altitude profile of my flight plans well above trees and structures. In summation therefore I can attest that all is well in the known universe at this time, while the orbital trajectories of all planets remain within acceptable tolerances. I look forward to racking up many hundreds of country miles on the flight log of this new-to-me M2P drone, with lots of video and still photographs documenting the adventures to come.
 
I suggested further checks on the other forum.
I sure appreciate your having taken a moment to address my predicament here and at the other forum, Yogi053. I am none the wiser, yet somehow I managed to reinstate the video feed. Keeping my fingers crossed having disabled all but the downward-looking sensors since none could be calibrated yet, and since I don't really need obstacle avoidance at the heights I fly drones, the video feed restored itself when I restarted the drone the next day, but this time making sure DJI Go4 was not working in the background. The maiden flight was a thing of beauty to behold, especially after that initial video feed interruption that magically resolved itself.
 
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If I were to calibrate the optical sensors using DJI Assistant and did not get the checkerboard, first thing I would try would be another cable.

The USB cable scene is a mess (even more of a mess than it was before it was 'fixed' with newer standards), so not just another cable of the same type to account for a bad cable, but another type to account for ... types. (eg Some cables are for charging only and therefore would not be a good choice for data transfer.)
 
If I were to calibrate the optical sensors using DJI Assistant and did not get the checkerboard, first thing I would try would be another cable. The USB cable scene is a mess (even more of a mess than it was before it was 'fixed' with newer standards), so not just another cable of the same type to account for a bad cable, but another type to account for ... types. (eg Some cables are for charging only and therefore would not be a good choice for data transfer.)

Wow, the cable never crossed my mind as a possible cause for the DJI Assistant 2 sensor calibration checkerboard screen to go blank. I am using a true Apple "lightning" connector to USB cable which happens to be the same cable I'd been using when my first attempt to fly the M2P drone was thwarted by a loss of connectivity between the drone and Litchi on my iPad. These Mavic Pilot forums are a treasure trove of experience and insights not covered by DJI's product description and user manuals. I thank you kindly, NASOC for this pointer that may well be the key

I suspect there might be an intermittent discontinuity in this cable that I've used for over a year now. They don't cost much so I'm hurriedly ordering a couple of spare Apple lightning to PC cables, to be ready just in case this cable I'm using fails completely. I tip my hat in gratitude once again.
 
Full disclosure: I've only done an optical calibration with DJI Assistant once. I'm just guessing that the checkerboard pattern wouldn't show until you had a proper connection, but that might not be the case at all.

But I still would have tried another cable if I had one handy. I worked with computers/software and they're fuzzier than most people might think, so shots in the dark are not uncommon.

Chris
 
Thanks to this Mavic 2 Pro, I just this morning shattered my previous distance record flown by any of my drones, which stood at 6.1 miles round trip, most of which was typically flown beyond the range of the RC controllers, whereby the drone proceeded on its Litchi-defined flight path under full GPS autopilot guidance.

To my absolute astonishment and delight, this Mavic Pro covered a whopping SEVEN country miles round trip, flying over the course of a nearby river valley, where the last vestiges of tropical rainforest remain as an endangered wildlife refuge along a narrow meandering ribbon that traces the river course. Perhaps the most surprising aspect of this flight was that the drone retained its connection with the RC controller throughout the flight, in marked contrast to all my other drones that typically lost all connectivity to the home base less than a mile out.

Holy Mackerel. This test flight has been a mind-blowing revelation for this experienced Litchi aficionado who had grown used to flying most missions with a frozen image on the iPad screen, accompanied by a sound track of that ominous Litchi warning going off every ten seconds "Warning. Disconnected!" Besides a few minor screen glitches, this M2P remained tethered to the controller at all times during the flight, as I shook my head in amazement.

My next test will certainly task the RC link of this drone because I will be sending it out on a teardrop-shaped flight path that will at its furthest point be 3.5 country miles from home base. None of my existing drones made it to the destination before RTH kicked in and the missions were aborted. Something tells me this M2P will complete that round trip and remain comfortably within signal reach the whole time. Stay tuned for more details at ten haha.
 

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Greetings fellow brethren of the M2P. I recently took delivery of a used eBay Mavic 2 Pro, and have been going through the usual calibrations of the compass, IMU, and camera gimbal, all of which went smoothly. When it came to calibrating the optical sensors, however, things didn't go quite as well.

Using DJI Assistant 2, I had the drone connected to the computer via the USB cable and immediately noticed something was wrong because while DJI Assistant 2 recognized the drone as an M2P, the usual list of firmware updates did NOT appear on screen, and there was instead an error message indicating that the firmware list could not be found. It was only when I connected the drone via DJI Go4 that I found out the latest firmware is installed, and designated with 790 as the last three digits. I then tried to carry out the sensor calibration procedure, which also failed.

Selecting the optical sensor calibration process in DJI Assistant 2, the checkerboard screen never materialized, and instead, I was presented with a 3-step tutorial on how to calibrate the optical sensors, which was the only function that became active when I tried to calibrate the optical sensors. Since there was no indication of a calibration of the optical sensors being essential, I skipped that step and decided to take the drone outside for its first test flight, which also did not go well at all.

During my indoor calibration procedures, the controller, drone, and iPhone all linked up seamlessly with a crisp camera image visible on screen, and the camera gimbal responded as expected to my turning the thumb-wheel on the controller to adjust the camera pitch up and down. When I took the drone outdoors, however, the camera image never materialized, and I was instead confronted with a black screen and a warning of a disconnect between the drone controller and the iPad. With no camera image and no telemetry, I then decided to take a short flight within visual range, just to see how the drone flies. There were no anomalies to report during that flight, but there was no camera image to see until I ended the test.

I am writing to this forum in the hopes that M2P owners with more experience than I might be able to figure out why there was no checkerboard screen image visible in DJI Assistant 2 when I attempted to calibrate the visual sensors of the drone, but more urgently than that, I am curious to find out why this drone that produced a nice crisp camera image during my indoor calibration procedures, suddenly blanked out that camera image when I went outside for a flight test. Any thoughts on what needs to be done here would be greatly appreciated. Thanks in advance for any insights that can be offered. For now, the drone is essentially grounded, but I am still optimistic that the fix to these issues will be a simple one.

I posted this same inquiry at another website, hoping to reach a wider audience of DJI Mavic 2 Pro owners whereby the reply to the above questions might appear sooner.
I had problems with the same thing. After much experimentation I realized it was the monitor I was using that caused the problem. So, I hooked my computer HDMI cable to my 55 inch TV and then tried calibrating the sensors again. It actually worked. So, in conclusion, It's usually a monitor issue. I know for a fact, you can't calibrate sensors on a curved monitor.
 
I had problems with the same thing. After much experimentation I realized it was the monitor I was using that caused the problem. So, I hooked my computer HDMI cable to my 55 inch TV and then tried calibrating the sensors again. It actually worked. So, in conclusion, It's usually a monitor issue. I know for a fact, you can't calibrate sensors on a curved monitor.
You've just reminded me that one of the messages I got while trying to calibrate the optical sensors using DJI Assistant 2, was a request to enter the resolution of the flat-screen TV that I use as a computer monitor. Looked it up in the NVDIA settings and entered the resolution, but even that entry did not resolve the blank screen syndrome. Having already used DJI Assistant 2 for the calibration of the sensors on my Mavic 1 Pro and Mavic 1 Pro Platinum, I am at a loss as to why I saw that request for the screen resolution, or why my entry of the requested resolution numbers had no effect.

I haven't given up just yet on my quest to calibrate all collision sensors on this M2P, even though I disable them as a routine precaution for all Litchi waypoint missions to prevent the false triggering that I noted with the MP 1Pros before I learned in this forum to disable the collision sensors on waypoint missions. This reminder about the possibility of a display screen-related anomaly is helpful and worthy of further investigation. I thank you kindly for this insight that I will certainly delve into further, if for no other reason than to eliminate the on-screen warning to complete that sensor calibration.

Just landed the drone after a 6.8-mile round trip Litchi mission that took the drone to the other side of a hill whereby I lost signal during the majority of the flight. The M2P returned at the precise instant I expected to see it, as defined by the Litchi flight time. It is always a relief when the theoretical time of arrival turns out to be accurate to such a great degree of precision.
 
Just landed the drone after a 6.8-mile round trip Litchi mission that took the drone to the other side of a hill whereby I lost signal during the majority of the flight. The M2P returned at the precise instant I expected to see it, as defined by the Litchi flight time. It is always a relief when the theoretical time of arrival turns out to be accurate to such a great degree of precision.
Just the other day I did a way point mission, I flew really low and ended up losing complete R/C connection only half way through. I Pressed RTH and it didn't respond. But when it got the the end of mission, I had RTH set to increase altitude to 350ft after the last way point. The display came back up and the drone made it home safely. It's so disturbing when the drone isn't connected to the r/c whatsoever and the drone is continuing it's mission.

By the way I tried 2 or 3 old monitors before trying my TV to get sensor calibration done. It never asked me for the resolution of the TVs or monitors though. I think I was calibrating a Mav 2 pro. Why it worked with the 55 inch TV is beyond me.
 
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