Calibrations

[hueman]

I've seen a video showing a guy 'calibrating' his H's compass?
I've since seen that there are various calibrations one can do.
Are these necessary for a new H?
Or when are they necessary?

 

[Eagle's Eye Video]

Compass calibration is recommended before the first flight, as your current location is likely not close to the location of a new unit (China) or a refurbished unit (who knows where).

I would then see how the bird performs... if there is a lot of drifting, for example, this could indicate a need for calibrating the accelerometer. If the gimbal exhibits behavior, such as not giving a level horizon that could be evidence that a gimbal calibration is needed.

 

[AeroJ]

Yep, after the initial one before maiden flight only do it if you have moved more than 100 miles from your last location, if the controller asks you to, if it won't fly straight, or if you notice a lot of error 32 in your flight logs...

 

[hueman]

Well, i flew my TH straight out of the box, flies perfectly, no apparent problem with compass, gimbal or anything else.
I saw no documentation recommending this nor how to do it, with the standard supplied docs. Only happened upon it by chance on a YouTube vid.
So if everythings ok, needn't i fix what ain't broke or should i do it anyway?
Thanks.

 

[AeroJ]

So if everythings ok, needn't i fix what ain't broke or should i do it anyway?

Looks like you were lucky I'd do it anyway.

 

[Eagle's Eye Video]

So if everythings ok, needn't i fix what ain't broke or should i do it anyway?
Thanks.

Review the procedures stickied in the "How To:" section... note that it is considered by many, to be the best practice to remove the camera before compass calibration.

 

[PatR]

When we first open the box a Typhoon H there is a little cardboard box with several items in it. One of them is the SD card and adapter inside a small Baggie. On the Baggie there is a label stating the SD card contains important information, which include instructional videos. One of the videos is dedicated to compass calibrating. The instructions are always present and have been since the H was first released but many fail to review them as they quickly pop the card into the camera and start recording, format the card, or unwittingly delete those videos. Yuneec also posted them on YouTube a little before the original release took place, along with other sites commonly viewed by new owners. Those that take the time to read all the labels, cards, and instruction sheets that arrive in the box of a new H might consider saving the card videos to a permanent file on their computers.

The compass is, IMO, one of the two most important sensors in the aircraft. The other is the accelerometers. The greatest cause of multirotor fly aways across all brands has been due to compass failures in one manner or another. The most common failure mode initiates with the “toilet bowl” effect, which amplifies over time until the aircraft crashes.

As the aircraft uses magnetic north as the zero position to establish rotational reference the compass is quite important. We can see the system calculate rotational reference when we connect the H to the GUI and view the change in degrees as we rotate the aircraft. Compass position reference also needs to closely align with GPS heading reference else a directional conflict may impact directional control. Compass and GPS heading information is recorded in flight telemetry, as are entries for various calibration modes.

Should people elect to avoid calibrating the compass they risk loss of their aircraft. Failure to calibrate the compass and accelerometers is a good way to learn you voided the warranty should you believe crash repairs are merited under warranty coverage. Bear in mind Yuneec always requests all the telemetry from the ST-16 before authorizing a warranty repair.

 

[Mrgs1]

That's another problem if your in UK it's only six months warranty which goes quick if your not flying it much, unlike you US guys.

 

[Mrgs1]

Review the procedures stickied in the "How To:" section... note that it is considered by many, to be the best practice to remove the camera before compass calibration.

I mentioned removing camera assembly and was shot down on another forum and Facebook page, I was told it had to have camera attached, in the videos it did seem to Bob around a lot, the reason they said it would incorrect when gimbal was reattached, I took it with a pinch of salt.

 

[hueman]

Wow. Thanks all, you've probably saved me eventually crashing!

 

[PatR]

Remove the camera when calibrating the compass. Yes, there are a couple degrees of difference in the final calibrations with and without the camera but that delta is small, meaning any errors in deviation will also be small. The gimbal does not have its own compass, using the aircraft’s compass zero reference for the nose center position.

If you want to eventually destroy the gimbal, induce gimbal drifting issues, or cause out of level problems, just leave it on the H when you perform compass calibrations. Those that want to debate the hazards of leaving the gimbal in place when performing a compass cal need only to roll the powered up H on its back to observe the gimbal actuators failing to stabilize the camera. They should also contemplate the force loading imposed on the actuators that occurs when the gimbal is rapidly rotated around the vertical axis during a compass cal, forces the actuators are not capable of resisting. If they desire to learn more about how a gimbal works and actuator stop limits they can Google for more info.

 

[Mrgs1]

Ive watched many videos with other drones too and it seemed amazing the gimbal didn't disintegrate.

 

[PatR]

The more sensitive and accurate a gimbal is the less they can be abused and expected to survive. It's for that reason we secured UAV gimbals to prevent movement during shipment to distant locations. Lessons learned the hard, and expensive, way.

 

[hueman]

One more question, sorry if this has been answered elsewhere, can i perform these calibrations on storage charged batteries? Would rather not fully charge one only to do brief calibrations then need to discharge as the weather here is currently not suitable (again ) for flying this weekend (high winds).

 

[Mrgs1]

One more question, sorry if this has been answered elsewhere, can i perform these calibrations on storage charged batteries? Would rather not fully charge one only to do brief calibrations then need to discharge as the weather here is currently not suitable (again ) for flying this weekend.

Me personally I would do it with a full battery would like to see how it performs afterwards. But if weather is bad wait, there in storage charge nothing to lose til a window of good weather comes.

 

[Photo]

I've seen a video showing a guy 'calibrating' his H's compass?
I've since seen that there are various calibrations one can do.
Are these necessary for a new H?
Or when are they necessary?

Huerman, and DO NOT forget to stay idling on the ground for at least 14 minutes after a compas calibration, or if you haven't been flying for a week or so OR moved the H more than 100km east-west or west -east.
IMPORTANT! That to compensate for magnetic field change and sats moving on the horizon.

 

[Eagle's Eye Video]

Huerman, and DO NOT forget to stay idling on the ground for at least 14 minutes after a compas calibration, or if you haven't been flying for a week or so OR moved the H more than 100km east-west or west -east.
IMPORTANT! That to compensate for magnetic field change and sats moving on the horizon.

Just to clarify, the H does not have to have the motors running at idle, to update the GPS almanac... simply have both the ST-16 and the H powered up.

 

[Photo]

You are 100% right Eagle, I usually use a separate battery for this process.

 

[hueman]

Thanks so much guys for your valuable advice!
Hopefully I'll get it done tomorrow.
Actually after flying the new bird twice, i did notice it almost hesitating to land, not just slowing landing automatically as it does but actually almost not wanting to at all.
Guessing this could be due to calibrations?

 

[PatR]

The reduction in descent speed close to the ground is not initiated by system programming, but by a condition called “ground effect” where the column of air under the aircraft becomes compressed by the spinning rotor discs. Although the air is roiled by the props there is still a compression effect.

At high descent speed we can blow though that compression layer and have the gear impact the ground hard enough to cause the aircraft to bounce back up, a common occurrence when using Home mode for an automated landing. If we are not prepared for that we encounter the possibility of quickly applying large control inputs only a couple inches from the ground, and if those inputs were too large or incorrect for the condition the next ground arrival could end up a roll over.

Turtle mode is where the close to the ground descent speed reduction is most evident. If you are new to the H, used to systems with more sedate landing characteristics, or without lots of previous RC aircraft history it might benefit to initially descend in Rabbit but switch to Turtle about 10’ above the ground. Be advised that both descent speed and control response is reduced in Turtle mode. Although slower in response and speed it will allow the new flyer more time to plan control inputs for changing conditions.

A reason not to descend from high altitude in Turtle mode is because the descent speed in Turtle is extremely slow. If battery voltage was low at the start of a descent it’s possible to run out of battery before reaching the ground in Turtle.