MPU-9250 Roll/Pitch + sEMG ADC

[dymnz]

sEMG ADC

teensy3.2 ADC is 3.3v tolerant

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MPU angle

• Gesture detection and data fusion based on MPU9250 sensor
  • Kalman filter
  • Pitch only
• Code available: Arduino sketches for MPU9250 9DoF with AHRS sensor fusion
  • Ask if appropriate to use

[dymnz]

Calibration value:

    magBias[0] = 126.0  * mRes * magCalibration[0]; // save mag biases in G for main program
    magBias[1] = 33.0   * mRes * magCalibration[1];
    magBias[2] = -86.0  * mRes * magCalibration[2];
    magScale[0] = 1.0286195;
    magScale[1] = 0.983897;
    magScale[2] = 0.98867315;

Fusion rate ~400Hz, Gyro rate 200 Hz (writeByte(MPU9250_ADDRESS, SMPLRT_DIV, 0x04);). Yaw drifts

https://github.com/kriswiner/MPU9250/issues/25#issuecomment-299027763

3) insufficient fusion rate--> fusion rate needs to be minimum 4-5x of gyro sample rate, 200 Hz gyro rate means >1 kHz fusion rate

Changed Gyro rate to 100 Hz, Fusion rate ~600Hz. Yaw slow to settle (>10s). May need >1kHz fusion rate @ 200Hz gyro

[dymnz]

Not needed for separate FLX/EXT PRO/SUP test

[dymnz]

float GyroMeasError = PI * (10.0f / 180.0f);

• sEMGx4 + MPUx3 report gyro@250Hz:

  • Fusion rate / report rate: 2500Hz
  • Initial filter settle time: ~15sec

• sEMGx4 + MPUx3 report gyro@200Hz: <- Default value, currently using

  • Fusion rate / report rate: 2660Hz
  • Initial filter settle time: ~10sec

• sEMGx4 + MPUx3 report gyro@100Hz:

  • Fusion rate / report rate: 2880Hz
  • Initial filter settle time: ~10sec

[dymnz]

Issue

• Check MPU update rate, jagged angle info for exp_21