kriswiner
commented
6 years ago In order to get proper mag calibration you have to move the sensor in all deisctions in 3D space, to sample the response surface at every point in other words. Are you doing this?
On Tue, Mar 6, 2018 at 9:04 AM, RicardPalo notifications@github.com wrote:
Hello Kris, I'm finishing my university final project, which is an AGV guided by GPS. I need to get the yaw in order to have a reference point for AGV's moves. I'm using your sketchbooks, but I have many questions: a) Using your code (with some changes) I think the yaw gotten is properly. But, when I check the Mz, Mx and My plots, it doesn't look well calibrated. How can it be? I don't know what I'm doing wrong with the calibration. My plot: [image: prueba cab 2] https://user-images.githubusercontent.com/36896960/37045803-0c609018-2167-11e8-9d4f-292ef0b34571.JPG
b) My second questions is about magScale. I don't understand why it is used for? When we call for the function I use this: [magcalMPU9250(magBias, magScale);] ` void magcalMPU9250(float dest1, float dest2) {
uint16_t ii = 0, sample_count = 0; int32_t mag_bias[3] = {0, 0, 0}, mag_scale[3] = {0, 0, 0}; int16_t mag_max[3] = {-32767, -32767, -32767}, mag_min[3] = {32767, 32767, 32767}, mag_temp[3] = {0, 0, 0};
Serial.println("Mag Calibration: Wave device in a figure eight until done!");
sample_count = 128; for(ii = 0; ii < sample_count; ii++) { readMagData(mag_temp); // Read the mag data for (int jj = 0; jj < 3; jj++) { if(mag_temp[jj] > mag_max[jj]) mag_max[jj] = mag_temp[jj]; if(mag_temp[jj] < mag_min[jj]) mag_min[jj] = mag_temp[jj];
} delay(135); // at 8 Hz ODR, new mag data is available every 125 ms }
// Get hard iron correction mag_bias[0] = (mag_max[0] + mag_min[0])/2; // get average x mag bias in counts mag_bias[1] = (mag_max[1] + mag_min[1])/2; // get average y mag bias in counts mag_bias[2] = (mag_max[2] + mag_min[2])/2; // get average z mag bias in counts
dest1[0] = (float) mag_bias[0]mResmagCalibration[0]; // save mag biases in G for main program dest1[1] = (float) mag_bias[1]mResmagCalibration[1]; dest1[2] = (float) mag_bias[2]mResmagCalibration[2];
// Get soft iron correction estimate mag_scale[0] = (mag_max[0] - mag_min[0])/2; // get average x axis max chord length in counts mag_scale[1] = (mag_max[1] - mag_min[1])/2; // get average y axis max chord length in counts mag_scale[2] = (mag_max[2] - mag_min[2])/2; // get average z axis max chord length in counts float avg_rad = mag_scale[0] + mag_scale[1] + mag_scale[2];
avg_rad /= 3.0; dest2[0] = avg_rad/((float)mag_scale[0]); dest2[1] = avg_rad/((float)mag_scale[1]); dest2[2] = avg_rad/((float)mag_scale[2]);
Serial.println("Mag Calibration done!"); } ' c)For my project I need to make a function to get the yaw when is necessary, but I can't calibrate the magne each time I run the function. So first I calibrate the magne and take the magBiases. Finally I avoid the magne calibration and put the magBiases in the function which calculates the mx, my and mz. The problem is that it doesn't give a 0 to 360º, it goes from 80 to 250º approximately. Is this problem related to the calibrations issues?
Thank you sooo much, I know it's a long post...
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RicardPalo
So, if I use the magBiases gotten from this calibration, can get the same yaw without calibration, can't I?
2º
Hello Kris, I'm finishing my university final project, which is an AGV guided by GPS. I need to get the yaw in order to have a reference point for AGV's moves. I'm using your sketchbooks, but I have many questions: a) Using your code (with some changes) I think the yaw gotten is properly. But, when I check the Mz, Mx and My plots, it doesn't look well calibrated. How can it be? I don't know what I'm doing wrong with the calibration. My plot:
b) My second questions is about magScale. I don't understand why it is used for? When we call for the function I use this: [magcalMPU9250(magBias,magScale);] ` void magcalMPU9250(float dest1, float dest2) {
uint16_t ii = 0, sample_count = 0; int32_t mag_bias[3] = {0, 0, 0}, mag_scale[3] = {0, 0, 0}; int16_t mag_max[3] = {-32767, -32767, -32767}, mag_min[3] = {32767, 32767, 32767}, mag_temp[3] = {0, 0, 0};
Serial.println("Mag Calibration: Wave device in a figure eight until done!");
sample_count = 128; for(ii = 0; ii < sample_count; ii++) { readMagData(mag_temp); // Read the mag data
for (int jj = 0; jj < 3; jj++) { if(mag_temp[jj] > mag_max[jj]) mag_max[jj] = mag_temp[jj]; if(mag_temp[jj] < mag_min[jj]) mag_min[jj] = mag_temp[jj];
} delay(135); // at 8 Hz ODR, new mag data is available every 125 ms }
// Get hard iron correction mag_bias[0] = (mag_max[0] + mag_min[0])/2; // get average x mag bias in counts mag_bias[1] = (mag_max[1] + mag_min[1])/2; // get average y mag bias in counts mag_bias[2] = (mag_max[2] + mag_min[2])/2; // get average z mag bias in counts
dest1[0] = (float) mag_bias[0]mResmagCalibration[0]; // save mag biases in G for main program dest1[1] = (float) mag_bias[1]mResmagCalibration[1];
dest1[2] = (float) mag_bias[2]mResmagCalibration[2];
// Get soft iron correction estimate mag_scale[0] = (mag_max[0] - mag_min[0])/2; // get average x axis max chord length in counts mag_scale[1] = (mag_max[1] - mag_min[1])/2; // get average y axis max chord length in counts mag_scale[2] = (mag_max[2] - mag_min[2])/2; // get average z axis max chord length in counts float avg_rad = mag_scale[0] + mag_scale[1] + mag_scale[2];
avg_rad /= 3.0; dest2[0] = avg_rad/((float)mag_scale[0]); dest2[1] = avg_rad/((float)mag_scale[1]); dest2[2] = avg_rad/((float)mag_scale[2]);
Serial.println("Mag Calibration done!"); }
' c)For my project I need to make a function to get the yaw when is necessary, but I can't calibrate the magne each time I run the function. So first I calibrate the magne and take the magBiases. Finally I avoid the magne calibration and put the magBiases in the function which calculates the mx, my and mz. The problem is that it doesn't give a 0 to 360º, it goes from 80 to 250º approximately. Is this problem related to the calibrations issues?
Thank you sooo much, I know it's a long post...