kriswiner/MPU6050

Accel Bias

PierreGogendeau opened this issue · 6 comments

PierreGogendeau commented

Hi,

I was looking at your file "MPU9250_MS5637_AHRS_t3" and there is something that I don't understand.
at the line 373 when you used this function :

accelgyrocalMPU9250(gyroBias, accelBias); // Calibrate gyro and accelerometers, load biases in bias registers

Here you store in the internal registers of the MPU9250 biais from the Gyro and Accel. Then line 478 in the main loop you substract it again :

// Now we'll calculate the accleration value into actual g's ax = (float)MPU9250Data[0]*aRes - accelBias[0]; // get actual g value, this depends on scale being set ay = (float)MPU9250Data[1]*aRes - accelBias[1]; az = (float)MPU9250Data[2]*aRes - accelBias[2];

I thought that when you store the offset value in the MPU9250, it do it by itself to substract the offset. Maybe there is something that I miss understood ?

Thanks in advance for your help

Cheers

Pierre Gogendeau

kriswiner commented
PierreGogendeau commented

Ok thank you for your very very fast answer. Have a good day.

lindig commented

I believe the bias is corrected by the chip and again in the main loop - and this is wrong. Not doing it in the main loop I can observe that the values are much closer to zero when the chip is not moving. So I suspect a bug here.

kriswiner commented
lindig commented

In MPU6050BasicExample.ino mpu.calibrateMPU6050() is called, which does write the data to the chip, and it subtracts the bias explicitly in the main loop.

kriswiner commented