Accelerometer Calibration

[PatR]

Accelerometers must be motionless and stationary to perform a calibration. A zero reference point cannot be made with the aircraft in motion, and that zero point for every axis is the most critical part of the calibration. Any Yuneec document suggesting to perform an accelerometer calibration with the aircraft in flight is simply wrong. Perform the accel calibration with the aircraft sitting on the ground or a table.

The accelerometer calibration is the most simple calibration a user can perform, they have to do nothing other than remove the gimbal lock if the camera is attached, power up a parked and generally level aircraft, tap the calibration button, and leave it alone until complete. There is no reason to make it a complicated process. Any type of calibration that is attempted in flight puts the aircraft, and possibly people, at high risk. If anything goes wrong the aircraft can crash out of control.

There’s a lot of people that ended up crashing their H’s because they moved the aircraft during the power up and self calibration process. That movement prevented the accelerometers from effectively and accurately self calibrating. Flying is moving.

 

[Loris]

I do not want to be anyone's teacher or tell someone how to calibrate the accelerometer.
I have only reported what is written in the last manual published by Yunnec, then one is free to do as he wants.

 

[PatR]

I don’t want to be a teacher either but it’s troubling when people do things that will crash their aircraft because they are misinformed and lack an understanding of how their aircraft works.

The aircraft does not hover in place because the motors are lifting equally using RPM that is equal for all the motors. It hovers because the accelerometers are being used to sense imbalances, sending that information to the flight controller to send commands to each ESC to increase or decrease power to each individual motor to compensate for the imbalance. The smallest breath of wind will cause imbalance. Hovering over ground that radiates heat unequally causes imbalance. Minor weight variations that make one part of the aircraft heavier than another cause imbalance that motor speed, higher or lower than another, is used to offset. The only time the motors spin at equal RPM is when the aircraft is sitting on the ground with the motors at idle, and even then varies slightly due component quality variables.

Sorry, but Yuneec user manuals are notorious for the abundance of information they don’t provide to the end user, and translational errors and inaccuracies. It’s up to users to be astute and use their own logic and reasoning to recognize when what they read doesn’t make sense.

 

[Loris]

I don’t want to be a teacher either but it’s troubling when people do things that will crash their aircraft because they are misinformed and lack an understanding of how their aircraft works.

The aircraft does not hover in place because the motors are lifting equally using RPM that is equal for all the motors. It hovers because the accelerometers are being used to sense imbalances, sending that information to the flight controller to send commands to each ESC to increase or decrease power to each individual motor to compensate for the imbalance. The smallest breath of wind will cause imbalance. Hovering over ground that radiates heat unequally causes imbalance. Minor weight variations that make one part of the aircraft heavier than another cause imbalance that motor speed, higher or lower than another, is used to offset. The only time the motors spin at equal RPM is when the aircraft is sitting on the ground with the motors at idle, and even then varies slightly due component quality variables.

Sorry, but Yuneec user manuals are notorious for the abundance of information they don’t provide to the end user, and translational errors and inaccuracies. It’s up to users to be astute and use their own logic and reasoning to recognize when what they read doesn’t make sense.

I agree with what you write, mine did not want to be a controversy about how it is right to calibrate the acellerometer but I was just reporting what said yuneec in his manual to those who said that this was an old release, no, this is the latest version published.
As for the errors of translation there are many, for example in the real sense section, the explanation of how to activate and deactivate, in Italian is exactly the opposite of how it is explained in English
and there are so many others, infact always i compare the translation.

 

[Eagle's Eye Video]

If there is ever conflicting information between what is found in a written manual and information found on this forum, I would suggest to go with information found here... after all we are here to proofread and correct the printed manual. What do you think we are all being paid for, anyways?

 

[DoomMeister]

If there is ever conflicting information between what is found in a written manual and information found on this forum, I would suggest to go with information found here... after all we are here to proofread and correct the printed manual. What do you think we are all being paid for, anyways?

With chips (of the bovine variety).

 

[Eagle's Eye Video]

I'll see your 5, and raise you 10...

 

[WildcatDave]

This is a copy of those sections of the manual freshly downloaded from the Yuneec website, and there is nothing that even remotely suggests doing the calibrations while airborne.

GIMBAL CAMERA CALIBRATION

STEP 1) Place the TYPHOON H on a level and stable surface. Switch on the ST16 Ground Station and the aircraft and wait till the RC and WiFi connected.

STEP 2) Make sure the tilt mode and pan mode all switched upwards, then tap the 'GPS Calibration' button and choose the 'GIMBAL CALIBRATION'.

STEP 3) The Gimbal camera will calibrate itself automatically. Wait the gimbal camera align in 3 axis and stay still, which means the gimbal calibration completes.

NOTICE: The whole calibration will take about 2-3 minutes. During the calibration process, do not touch or move the aircraft.


ACCELEROMETER CALIBRATION

STEP 1) Place the TYPHOON H on a level and stable surface. Switch on the ST16 Ground Station and the aircraft and wait till the RC and WiFi connected.

STEP 2) Make sure the FLIGHT MODE switch is in the middle position. Tap the GPS Calibration button, and choose 'ACCELEROMETER'.

STPE 3) Keep the aircraft stable during the calibration process. During calibration, the main led will blink red, green and blue slowly at first and rapidly afterwards. If calibration succeed. The copter will restart automatically. You will recognize the this when you hear the raising tone.

NOTICE: You must do the accelerometer calibration in no-wind condition.

IMPORTANT NOTE: If calibration has failed, the Main LED Status Indicator will be solid white and you must repeat the calibration process. If the calibration continues to fail, either the site of calibra- tion is unsuitable or the accelerometer is defective. Refer to your Yuneec service center.

I'm not sure which version of the manual you have. I went to their site just today and it's still version 1.2 which came out in 2016. If you have a newer version that is strange, that is not the one they have listed on their site. The one on the site still says...

STPE 3) Keep the aircraft hovering during the calibration process. During calibration, the main led will blink red, green and blue slowly at first and start the motors and take off the aircraft, then the LED will blink rapidly afterwards. When the LED blinks slowly, land and aircraft and stop the motors. If calibration succeed. The copter will restart automatically. You will recognize the this when you hear the raising tone.

Yes that is an exact copy and paste from the PDF even with the misspelling of the word STEP. Always reassuring to know that they can't even get a four-letter word spelled right on a device that is extremely complex to use and master.

 

[DoomMeister]

@WildcatDave

Most H480 pilots on this forum use this manual, which is the Yuneec Manual with user generated information that covers topics somewhat more thoroughly. You are welcome to do the accelerometer calibration which ever way you feel more comfortable with. Both methods are described in the expanded manual.

Being an Avionics technician in the Air Force, I can tell you the IMU on our aircraft (which contained the accelerometers) was not calibrated while the plane was in flight. It was calibrated on a table that was level to a very high standard and isolated from ground vibrations.

 

[PatR]

Which is exactly how just about all high end IMU’s are calibrated, resting on a calibrated spin table. It’s the only way errors can be discovered and offset. For a minor history lesson, even the now semi antiquated INS systems required about 5 minutes of zero motion after power up for self calibration.

 

[jandjfrench]

Which is exactly how just about all high end IMU’s are calibrated, resting on a calibrated spin table. It’s the only way errors can be discovered and offset. For a minor history lesson, even the now semi antiquated INS systems required about 5 minutes of zero motion after power up for self calibration.

Not being one to resist riding a dead horse I'll just say Giddy up! I've had a chance to think about this and now suspect that in case the center of lift and center of gravity are coincident on the Z axis there will be a tendency to drag the H off the X and Y axes when thrust is applied. To determine the amount of differential prop speed required to meet this I think the most accurate determination could only found by hovering with no wind. Short of hovering in an enclosure transparent to GPS signals and large enough to eliminate the effects of prop wash, setting this way seems impracticable. Calibrating by setting the H on level ground is likely to be good enough.

 

[PatR]

Good luck and enjoy the results. We all know that Yuneec never puts incorrect info in their user manuals...[emoji849]

As the H employs a version of the Pixhawk FC, we might want to review documentation developed for Pixhawk and APM based FC’s to see if any of them make a similar in flight accelerometer calibration recommendation. I can save you some time and let you know that only an in flight auto PID calibration is possible. PID’s and accelerometers are not the same thing.

 

[jandjfrench]

Good luck and enjoy the results. We all know that Yuneec never puts incorrect info in their user manuals...[emoji849]

As the H employs a version of the Pixhawk FC, we might want to review documentation developed for Pixhawk and APM based FC’s to see if any of them make a similar in flight accelerometer calibration recommendation. I can save you some time and let you know that only an in flight auto PID calibration is possible. PID’s and accelerometers are not the same thing.

I don't understand much of what you're referring to but like I said calibrating by setting the H on level ground is probably good enough. I see you're being satirical when you refer to the accuracy of the Yuneec documentation but can you cite other instances that might be helpful to me? I'd appreciate it. Thanks.

 

[PatR]

There are many places the factory H manual is insufficient or incorrect, especially where they tried translating from Chinese to English.

 

[jandjfrench]

There are many places the factory H manual is insufficient or incorrect, especially where they tried translating from Chinese to English.

Where can I find the factory H manual?

 

[DoomMeister]

The Yuneec website in the downloads section.

 

[AH-1G]

I do not want to be anyone's teacher or tell someone how to calibrate the accelerometer.
I have only reported what is written in the last manual published by Yunnec, then one is free to do as he wants.

If you go back read (misprints) and watch some of Yuneec videos, you will see they are in error.
That's why we have proof readers (experts) doing follow up in these categories.

 

[jandjfrench]

The Yuneec website in the downloads section.

There is no "factory" manual listed. In the event that PatR misspoke (misposted?) and was referring to errors in the Owners manual I'm curious as to those errors. I usually find myself being more critical than need be about about supplied documentation but I think Yuneec did a good job with the owner's manual. I've been really impressed with my Typhoon H and don't think Yuneec needs me as a defender but I found PatR's post to be overly negative and somewhat offensive.

 

[AH-1G]

not sure if this is the original.

 

[DoomMeister]

By a “factory” manual are you relating that to the likes of a service manual for a motor vehicle, home appliance, etc.?

If so, there is nothing like that released to the end user. Probably only authorized repair centers. I am sure Pat was referring to the Owner’s (User’s) Manual for the H480. It is a starting point, but is lacking in a lot of information that got added in the one I posted earlier in this thread.

Being a technician most of my working career I had access to the “factory manual” for the equipment I had to repair and maintain. So when I get incomplete and sketchy manuals that do not fully explain the equipment I buy, I too have a tendency to bad mouth the documentation.

The other Pixhawk documentation PatR was referencing can be found doing web searches. There are plenty of DIY builders on the web that share their experience.