Is it gimbal lock?

Other Hardware Sensors
1

Hi all,

I'am actually working with an LSM6DSO32 captor, I use kalman filter to get roll and pitch angles. But in certain position I get strange value, suddenly my angle jump for exemple I'am in -79° in pitch and -76° in roll and if I move just a little bit my captor (1- 5°) my angles jump to -0.48 in roll and pitch approach 90°, is it gimbal lock? It's seem that this phenomenon appears only in certain configuration when roll and pitch approch to certain angle
I also try to use Madgwick ahrs and I got the same result...

2

Hello
Your description points to some special cases within the trigonometric functions. The tangent function tends to jump at 90°.
grafik

3

Ok and there is a solution to this trigonometric problems? It's really strange my roll angle jump suddenly when my pitch is close to 90 or -90°, my roll jump to -80 to 2° suddenly but I moved my captor only by 3-5° max
If I go to the opposite I don't have the problem my roll doesn't move and my pitch decrease to -86° to -10° and this is the good value...

4

Hello,
check your sketch.
Insert several Serial.println at POI.
Isolate the processing part and test with manual inserted values.

5

It is most accurate to use just the accelerometer to measure roll and pitch as described here: How_to_Use_a_Three-Axis_Accelerometer_for_Tilt_Sensing-DFRobot

No filter is needed, and the one you are using may actually be causing the problem.

6

You should work with DCMs or quarternions internally, only converting to roll/pitch for humans. DCMs and quarternions don't have discontinuous behaviour.

Quarternions are usually the most convenient representation for orientation as they are 4 values with 3 DoF (degrees of freedom), whereas a DCM has 9 values with 3 DoF.

An orientation is the same as a 3D rotation, note.

Whatever you do Euler angles will display discontinuity, typically between upright and inverted - its fundamental to that represenation. This is why they are hopeless for calculations.

7

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