In my case this does not involve a loss of wifi.
All of my flying is done in controller mode.
Finally today I observed what happens. The Breeze was hovering at just under 50 feet for maybe 30 seconds when it started gaining altitude again. I looked at my screen and noticed the altimiter had reset to 0 and was again climbing!!! The breeze thought it was too close to the ground and may have been attempting to reach normal hover height, RTH, or even the last known altitude. I didn't let it go so I don't know where it would have stopped or if it would.
Once it starts to ascend I have to hold the left stick down to get it to descend because as far as it's concerned I am asking the Breeze to descend through zero! The altimeter on screen actually starts reading in negative feet!
Fortunately the Yuneec programmers allowed a manual override of the Breeze so it can go all the way back down to negative 40+ feet where the ground is in this case.. Near the ground I finally give it some stick up as it seems to want to descend too low. Finally the IR ground sensor allows it to hover a couple feet off the ground but the altimeter never resets until it lands. If I command it to land the altimeter corrects itself as soon as it touches down.
Very strange. I assume the altimeter is based on GPS above a certain height so I don't know what could cause it to lose its altitude like that as the GPS doesn't lose its satellite locks. Or... is the altimiter barometric?
In any case, it still works I just have watch for the unrequested ascent.
I suppose in any automatic mode other than direct control I would have to be ready to request landing if it started it's random ascent. I'm not sure if it would land properly in any of the automatic modes once the altimeter reset to zero at 50 feet or so. It might try a controlled landing at 50 feet! I would like to think it relies on the IR sensor for landing but I don't know.
Thank you for your detailed observations.
All of my flying is done in controller mode.
I also prefer flying with the controller. The video feed has less lag while using it as the phone doesn’t have to compute touch position of virtual sticks. The only drawback is that no telemetry is stored when using the Controller task mode.
I looked at my screen and noticed the altimiter had reset to 0 and was again climbing!!!
Great job catching the altitude glitch.
Once it starts to ascend I have to hold the left stick down to get it to descend because as far as it's concerned I am asking the Breeze to descend through zero!
Partially true. Any descent requires the throttle to be positioned below neutral. Descending below “0” is not a problem as it is just a reference set at takeoff. Try flying from an elevated takeoff point and fly down to your subject. It makes no difference to the Breeze, but as you state it will display negative altitude
Finally the IR ground sensor allows it to hover a couple feet off the ground but the altimeter never resets until it lands. If I command it to land the altimeter corrects itself as soon as it touches down.
The IRS has a range of about 5 meters and detects the altitude above a surface (will not reset the barometric telemetry). This should prevent the Breeze from contacting the ground. Mine always stops about 18 to 24 inches and will go no lower. The barometric telemetry does reset to zero upon landing.
I assume the altimeter is based on GPS above a certain height so I don't know what could cause it to lose its altitude like that as the GPS doesn't lose its satellite locks. Or... is the altimiter barometric?
You guessed it! The reading for altitude you see on the screen is the barometric altitude. It is relative and is set to zero at takeoff. For the first 5 meters the IR sensor is also involved to help keep a steady altitude. GPS is not used in altitude calculation it is too inaccurate.
I would like to think it relies on the IR sensor for landing but I don't know.
The IR should slow the descent as the Breeze nears the ground. The accelerometers in the IMU actually tell the Breeze when it is on the ground. When the descent rate is zero for long enough the motors are disarmed.
I suspect there is dust clogging the barometer. It is on the A9 board in the front portion of the aircraft. The other possibility is an electrical glitch to the barometer IC resulting in it resetting the altitude reference. If the latter is the case it should only rise to the set hover height (maximum of 4 meters). Once the reset to zero occurs, does it ever show a gain in altitude or does it stay at zero and only display negative altitude during a descent?