Icon in Gui not moving with Gyro only

[olfried]

Hi,
i have a Gyro only setup and i get moving courves in the Gui when i move the Quad.
But the icon and the horizon does not move.
Is it a bug or am i doing something wrong?

Olaf

[PatrikE]

Without Accelerometer you don't have any tilt angles to show.
Gyro only senses motion.

[olfried]

I thought a Gyro is there for measure the Angle change per time?
And does it mean that i cannot fly a copter with a WMP only?

Without Accelerometer you don't have any tilt angles to show.
Gyro only senses motion.

[PatrikE]

You can fly a copter with gyro only..
But without Accelerometer you will not have the Auto Leveling functions.

[olfried]

Ok, but i still don't understand.
If i have a "Wii Motion Plus" and NO "Nanchuk" installed, what do i measure?
I thought it is a Gyroscope which measures the change of the angle?
Why is it not shown in the GUI?
Olaf

You can fly a copter with gyro only..
But without Accelerometer you will not have the Auto Leveling functions.

[olfried]

Is there someone there who could explain me this?
I read about the Wii motion plus and about the nachchuck on the multiww page.

Is it correct that:

The WMP has three gyroscope inside.
The Nanchuk has three gyroscope and three lateral acceleration sensors built in?

I i have a WMP installed, the copter knows about it's angle movement, right?
And this is enough to fly the bird, right?

But again, why does the icon in the gui not move when i have a WMP installed? Why is it necassary to also have lateral accelerators
to show the moving copter?

Olaf

[jz1]

Like Patrik said: gyro can only tell your multicopter's processor "Hey, I am rotating at xxx degrees/s in yyy direction!", and then processor checks if you asked your copter to rotate (that is if you pushed pitch, roll or yaw lever) and if it is not rotating at desired speed in desired direction it corrects motor speeds to achieve what you want.
In other words: imagine your multicopter lays on the floor and does not move, no matter if you put it on its left side, upside down or whatever, in all these cases gyro indicates the same - no rotation. Gyro does not know its orientation, it only knows if it is rotating, how fast and in what direction.
You need accelelerometer to know your orientation as it measures (among others) the G-force.

In flight when you only use gyro if you push for example pitch forward your multicopter will tilt to front, and when you release pitch copter will not go back to previous position, neutral position of pitch and yaw in this case means "stay at the angles you are". If you use accelerometer and enable autolevel feature (and calibrate it of course) then neutral position of pitch and yaw means "stay perpendicular to g-force".

[jz1]

Forgot to answer two of your questions:

The WMP has three gyroscope inside.
The Nanchuk has three gyroscope and three lateral acceleration sensors built in?

Unfortunatelly I am not sure if Nanchuk has gyros, I am almost sure it has accelerometers.

I i have a WMP installed, the copter knows about it's angle movement, right?
And this is enough to fly the bird, right?

2 x yes, of course if you connected it properly and you see gyro indications in GUI.

[olfried]

Hey, i think i understood it now.
I thought that the accelerometer measures only the movement in x,y or z direction.
But as i understand it, it measures also the gravity when not moving, right? That's why the copter knows it's current angle in space.
Thank you very much for the explanation!
Olaf

Like Patrik said: gyro can only tell your multicopter's processor "Hey, I am rotating at xxx degrees/s in yyy direction!", and then processor checks if you asked your copter to rotate (that is if you pushed pitch, roll or yaw lever) and if it is not rotating at desired speed in desired direction it corrects motor speeds to achieve what you want.
In other words: imagine your multicopter lays on the floor and does not move, no matter if you put it on its left side, upside down or whatever, in all these cases gyro indicates the same - no rotation. Gyro does not know its orientation, it only knows if it is rotating, how fast and in what direction.
You need accelelerometer to know your orientation as it measures (among others) the G-force.

In flight when you only use gyro if you push for example pitch forward your multicopter will tilt to front, and when you release pitch copter will not go back to previous position, neutral position of pitch and yaw in this case means "stay at the angles you are". If you use accelerometer and enable autolevel feature (and calibrate it of course) then neutral position of pitch and yaw means "stay perpendicular to g-force".

[jz1]

I thought that the accelerometer measures only the movement in x,y or z direction.
But as i understand it, it measures also the gravity when not moving, right?

Actually it does not measure movement, you can assume that accelerometer in copter measures only the g-force. Imagine:
- hovering copter
- copter moving horizontally at constant speed
- copter moving horizontally and accelerating
In first two cases accelerometer readings will be exactly the same - so you can not say accelerometer measures movement. In third case measurement will be just a little bit different.
If you have an Android smartphone with accelerometer (most of them have it) I would recommend you to get an app that shows accelerometer readings and try to check it yourself.

[olfried]

But doesn't that mean, that there is no accelometer change, when i turn my Copter in the point where the acc-chip is? I mean, if i Roll, Pitch or yaw it.
There shouldn't be any G-Force to it when i just turn, right?
Olaf

[jz1]

No, if you roll or pitch it then accelerometer will notice it. If you yaw it then accelerometer will not know that you've done it, because gravity force all the time works in the same direction. 3-axis accelerometer measures force in 3 directions, for example up-down, left-right, front-back, if it lays flat then up-down shows gravity force, two others show zero, if you imagine this accelerometer yaw rotation - nothing changes.
To put it simple: imagine you stick virtual glass full of water on top of your copter so that water does not spill (that's accelerometer calibration) - accelerometer will notice situations in which water is spilled out of the glass and will know how much water spilled and on which side. Of course I assume that glass refills itself every time water is spilled.

For yaw orientation we use magnetometer (compass).

[piston11]

I'm not sure idf it will help, but mine was doing the same thing. Turned out the acc thought the copter was on its side, recalibrated acc with copter perfectly level and the horizon and compass started working again although I am using a mega 2560.