What measurement technique for absolute angle & position with slow moving objects

Other Hardware Sensors
1

I would like to monitor the movement of an extremely slow object. The x,y,z-position is not really relevant to me, I am more interested in the angle. I have come across the MPU6050 that is explained here: https://howtomechatronics.com/tutorials/arduino/arduino-and-mpu6050-accelerometer-and-gyroscope-tutorial/

but even though it has a motion processor that corrects drift I think this is not going to work as my object cannot move for several hours up to 1-2 days.

Thus, I was thinking about a magnetometer as this one: QMC5883L-TR as a suitable IC.

What measurement technique do you think is suitable for me? I can find the appropriate modules then.

Thank you!

2

What angle?

3

Absolute angle in degree / °. There are gyroscopes that measure °/sec but I am not interested in tracking the movement precisely. The object changes veeeeery slowly. I would rather monitor it's absolute orientation/angle. I hope that clarifies my question.

4

An accelerometer can be used to measure pitch and roll, the two tilt angles relative to vertical.

To measure yaw (rotation about vertical from magnetic North) a calibrated magnetometer is required.

A 9DOF sensor and associated 3D fusion code combines the gyro, magnetometer and accelerometer to measure all three angles.

5

thank you jremington! that will help me a lot.

6

If it’s moving very slowly an accelerometer is not going to give any sensible data .

You need to specify a bit better - how big , how slow , is it outdoors , in a room , constrained to a fixed space , how accurate ??

7

If there's an axis / shaft about which it rotates an encoder might be possible.

If not a 3D accelerometer could work (assuming little vibration, only slow, smooth
motion). You'd low pass filter heavily too to reduce noise variations. Basically this
measures the gravity vector so you can determine angle from vertical.

However all MEMS mechanical sensors (accelerometer, gyro) are relatively limited in
accuracy and quite noisy.

MEMS gyro is useless for this application as it only measures speed of rotation (they
are technically "rate gyros").

Magnetometer precision is the worst of all, don't expect much accuracy from these.

8

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