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DEV-922 Mag sensitivity fix #281

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DEV-922 Mag sensitivity fix #281

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34 changes: 26 additions & 8 deletions ShimmerDriver/src/main/java/com/shimmerresearch/verisense/sensors/SensorLSM6DSV.java
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@
import com.shimmerresearch.driverUtilities.ChannelDetails.CHANNEL_TYPE;
import com.shimmerresearch.sensors.AbstractSensor;
import com.shimmerresearch.sensors.ActionSetting;
import com.shimmerresearch.sensors.lisxmdl.SensorLIS2MDL;

/**
* Second-generation Verisense IMU: LSM6DSV (accelerometer + gyroscope) with the
Expand All @@ -38,10 +39,16 @@
* tagged FIFO ([TAG_CNT][X][Y][Z]) interleaving the three streams; the byte-level
* extraction + per-stream timestamping lives in
* {@code VerisenseDevice.parseDataBlockDataLsm6dsv(...)}. This class provides the
* channel definitions, configuration and calibration. Calibration matches the
* firmware/SDK nominal model: value = raw / sensitivity (identity alignment,
* zero offset) where sensitivity = 32768/(FS*9.80665) for accel, 32768/FS for
* gyro and 1/0.15 for mag.
* channel definitions, configuration and calibration.
* <p>
* Sensitivities: 32768/(FS*9.80665) LSB per m/s^2 for accel, the ST angular-rate
* spec of 4.375 mdps/LSB at +-125 dps for gyro, and 667 LSB/Gauss for the LIS2MDL
* mag - the last taken from {@link SensorLIS2MDL} rather than duplicated here, so
* calibrated magnetometer output is in GAUSS, consistent with every other Shimmer
* magnetometer and with the per-unit calibration the device stores.
* <p>
* Alignment is left as identity here and corrected by the file parser per hardware
* revision; offsets are zero.
*
* @author Mark Nolan
*/
Expand Down Expand Up @@ -230,8 +237,10 @@ public static final class DatabaseConfigHandle {
CompatibilityInfoForMaps.listOfCompatibleVersionInfoLSM6DSV);

// ----------------- Calibration Start -----------------------
// Identity alignment + zero offset so calibrated = raw / sensitivity, matching
// the firmware/SDK nominal model (and the validated standalone decoder).
// Identity alignment is a placeholder, NOT the real sensor->ASM map: the file
// parser overrides it per hardware revision at parse time (see
// CalibrationFileManager.applyGen2DefaultAlignment in the VerisenseDriver repo).
// Correcting it here as well would give two sources of truth for the same values.
public static final double[][] DEFAULT_OFFSET_VECTOR_LSM6DSV = {{0},{0},{0}};
public static final double[][] DEFAULT_ALIGNMENT_MATRIX_LSM6DSV = {{1,0,0},{0,1,0},{0,0,1}};

Expand All @@ -251,8 +260,17 @@ public static final class DatabaseConfigHandle {
public static final double[][] SENS_GYRO_1000DPS = {{28.571428571,0,0},{0,28.571428571,0},{0,0,28.571428571}};
public static final double[][] SENS_GYRO_2000DPS = {{14.285714286,0,0},{0,14.285714286,0},{0,0,14.285714286}};

// Mag sensitivity (LSB per uT) = 1/0.15
public static final double[][] SENS_MAG = {{6.666667,0,0},{0,6.666667,0},{0,0,6.666667}};
// Mag sensitivity: taken from the LIS2MDL's own sensor class rather than
// re-declared here, because it is a property of the chip (1.5 mGauss/LSB) and not
// of the LSM6DSV sensor hub the samples arrive through. 667 LSB/Gauss, matching
// the firmware calibration seed (SC_LIS2MDL_MAG_SENS), the web SDK catalog, and
// every other Shimmer magnetometer (LSM303DLHC etc. are all LSB/Gauss).
//
// This was previously a local copy of 6.666667 = 1/0.15 LSB/uT, which made
// gen-2 magnetometer output 100x larger than every other Shimmer device for the
// same field, and 100x out of step with the per-unit calibration the device
// stores. Reference the shared constant so the two cannot diverge again.
public static final double[][] SENS_MAG = SensorLIS2MDL.DefaultSensitivityMatrixMagShimmer3r;

public CalibDetailsKinematic calibDetailsAccel2g = new CalibDetailsKinematic(
LSM6DSV_ACCEL_RANGE.RANGE_2G.configValue, LSM6DSV_ACCEL_RANGE.RANGE_2G.label,
Expand Down
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