03-18-2022 04:50 PM
Hello. I experience a very high level of noise from BMI270 gyro. My settings are:
0x7C PWR_CONF: 0x03; > low power mode;
0x42 GYR_CONF : 0x27 > ODR= 50 Hz;
0x43 GYR_RANGE: 0x04 > +/- 125 dps, 262 LSB/dps.
While still, I get rms noise about 50 LSB. It gives 0.2 dps - correct? Seems high but my application can tolerate it.
But when I move the bench with IMU fastened on it slowly over the table (without noticeable rotation) I get noise peaks about 1000...1500 LSB = 4...5 dps, it makes the data useless. My first idea was it is high frequency vibrations from friction between the table and my improvised bench, but when I mounted IMU on a dampfer (0.5 kg weight on 2cm elastic foam) - nothing changed.
And, near the same amount of noise when I tap by fingers on the table near the standstill IMU. But in this case there is definitely no vibration about 4 dps amplitude.
I tried OSR4 mode - seems even worse.
I'm not very experienced in those gyro/ accelerometer matters - do I do/understand something wrong?
The gyro data is needed mainly to calculate the tilt over the short time, to distinct acceleration from the gravity.
I'm completely clueless what can cause such a noise, any ideas will be very appreciated.
04-06-2022 05:08 PM
Hello, I'm sorry I can't help you, because I have a similar problem. When I solve it, I will reply and inform you at the first time!
04-08-2022 11:33 AM
Hello SterlingMinsha , thank you in advance. Meanwhile, I tried another, better damper with 3 Hz resonance frequency (instead of previous 11 Hz).
Also, I found Cross Axis Sensetivity being about 2% instead of 0.2% in datasheet, onto Y axis so Gyroscope Data Post Processing described in part 4.6 of datasheet would not help, as I understand. Also, I found a too big influence of a static tilt around X and Z axis onto Y axis gyro readings, about ten times more than I estimate in thery. All that I tried to compensate in software, adjusting coefficients experimentally.
Now results are substantially better, but I still have about 0.5 deg error (random) of angular position (angular speed integrated) after a couple of seconds of a pretty slow movement and that is still too much for me.
Also I discovered errors are about 2 times less when I suspend the experimental bench on strings instead of moving on the table. In the last case there is no vibrations from friction and movements are smoother.
I would appretiate very much any data what precision of angular position and speed was achieved in reality, for slow movements. My goal is to achieve about 5 cm/sec velosity error after couple of seconds of movement at about 10 cm/sec and 10 deg/sec, little vibrations. And I got doubt if it is possible for BMI270.
05-06-2022 04:28 AM
Hi Anatol,
It needs to be tested with a professional testing platform, not directly on the table.