Flight distance : 2196855
I purchased a P4Pro two weeks ago (my fourth DJI UAV), updated all firmware, made sure all stickers and foam shipping insert were removed from gimbal, performed a very careful cold IMU calibration per my established practice on a perfectly level mable countertop in my kitchen, and then calibrated the gimbal (twice) using the same level marble countertop. I then tested the gimbal calibration at home by power cycling the P4Pro with no props attached, picking up the P4Pro in my hands and observed live video on my iPad Air 2 while moving it left, right, forward, backwards, tilted it left up to 45 degrees, tilted it right up to 45 degrees, moved it forward and backwards while tilted - and the gimbal remained perfectly level through all these non-flight tests! Excellent - now time for real flight testing in the field.|
All the following flight testing of P4Pro was performed in P mode with 16+ GPS satellites locked in and with Obstacle Avoidance turned ON. HD flight mode was set to CUSTOM, 2.4 GHz, Channel 19, at lowest video transmission rate (slider all the way to the left).
I powered up the P4Pro, calibrated the compass, adjusted the focus point, started the video recording and noted the following repeatable issues with regard to gimbal horizon:
1) Horizon was perfectly level while hovering, rotating while hovering, and moving less than 10-15 mph forward or backward. EXCELLENT!
2) Horizon tilted 5-15 degrees (high point on left of screen, low point on right of screen) as forward speed increased above 15 mph and got progressively worse as speed increased up to 36 mph. Magnitude of tilt appeared directly related to speed of aircraft. I stopped aircraft 4 times, and horizon leveled out every time to within a 1 degree of perfectly horizontal - sometimes this took 5-10 seconds, twice it took over 45 seconds to return to level. This tilted horizon while flying left is DISAPPOINTING and UNACCEPTABLE.
3) When flying to the left, the horizon tilted severely to the left (high point on right side of screen, low point on left side of screen) approx. 15-25 degrees. After stopping and returning to stationary hover, gimbal horizon returned to level after 20 seconds. The tilted gimbal horizon when flying left was VERY DISAPPOINTING and UNACCEPTABLE.
4) When flying backwards at various speeds up to 34 mph, the gimbal horizon remained perfectly level. This was SURPRISING (considering amount of tilt when flying forwards), but welcome and definitely VERY ACCEPTABLE.
5) When flying to the right at various speeds up to 34 mph, the gimbal horizon tilted to the right about 5 degrees. With aircraft at stationary hover, gimbal horizon returned to level after about 20 seconds.
6) On an extended long-distance flight over unpopulated and very flat farmland and grazing land at a constant seed of 34-38 mph, the gimbal horizon was again tilted 15-20 degrees to the right. I was able to use the gimbal adjustment while maintaining forward speed and acheived a stable, level gimbal horizon at a gimbal adjustment of 3.1, which is HUGE adjustment. However, any time I slowed down or stopped, the gimbal would tilt the other direction and I would have to reduce gimbal adjustment to zero to get a level horizon while in stationary hover.
7) On return flight of 20,000 feet (in opposite direction, of course), I once again had to apply about a 2.9-3.2 gimbal adjustment to achieve a stable, level gimbal horizon at a constant speed of 34-36 mph. But, as before, the gimbal horizon would tilt the opposite direction whenever I slowed down, and when I stopped I would again have to set the gimbal adjustment back to zero to get a level horizon.
This tilting gimbal horizon (after careful IMU calibration and gimbal calibration on level marble surface) when in forward flight, flying left and flying right is UNACCEPTABLE and cannot be easily compensated by adjusting gimbal BECAUSE the magnitude of the horizon tilt and the amount of gimbal adjustment required is a function of P4Pro horizontal speed (i.e., a single adjustment setting will not produce a level gimbal horizon at all horizontal velocities, which is an unworkable situation).
Since P4Pro is perfectly level when in a stationary hover, when turning 360 degrees, and when flying backwards, this variable tilting of the gimbal horizon proportional to horizontal speed when flying forwards or sideways appears to be a bug in the software controlling flight and gimbal positioning rather than an IMU or gimbal calibration issue.
I am hopeful a firmware update is forthcoming that will address this issue. If not, I will have to return my P4Pro to Best Buy for a refund before my 30-day exchange period expires and then repurchase another one when this forum indicates this gimbal horizon issue has been resolved by new firmware.
What are other P4Pro owners experiencing with regard to gimbal tilt as a function of horzontal velocity during forward and sideways flight? Does your calibrated gimbal horizon surprisingly remain level during reverse flight like mine did? Please provide your testing results in this thread as the more information we can provide DJI, the quicker they may be able to diagnose and resolve this bug.