feature: Add dummy mode

ardriver/xreal/xrealsrc/FusionAhrs.c

@@ -0,0 +1,510 @@
+/**
+ * @file FusionAhrs.c
+ * @author Seb Madgwick
+ * @brief AHRS algorithm to combine gyroscope, accelerometer, and magnetometer
+ * measurements into a single measurement of orientation relative to the Earth.
+ */
+
+//------------------------------------------------------------------------------
+// Includes
+
+#include <float.h>
+#include "FusionAhrs.h"
+#include <math.h>
+
+//------------------------------------------------------------------------------
+// Definitions
+
+/**
+ * @brief Initial gain used during the initialisation.
+ */
+#define INITIAL_GAIN (10.0f)
+
+/**
+ * @brief Initialisation period in seconds.
+ */
+#define INITIALISATION_PERIOD (3.0f)
+
+//------------------------------------------------------------------------------
+// Function declarations
+
+static inline FusionVector HalfGravity(const FusionAhrs *const ahrs);
+
+static inline FusionVector HalfMagnetic(const FusionAhrs *const ahrs);
+
+static inline FusionVector Feedback(const FusionVector sensor, const FusionVector reference);
+
+static inline int Clamp(const int value, const int min, const int max);
+
+//------------------------------------------------------------------------------
+// Functions
+
+/**
+ * @brief Initialises the AHRS algorithm structure.
+ * @param ahrs AHRS algorithm structure.
+ */
+void FusionAhrsInitialise(FusionAhrs *const ahrs) {
+    const FusionAhrsSettings settings = {
+            .convention = FusionConventionNwu,
+            .gain = 0.5f,
+            .gyroscopeRange = 0.0f,
+            .accelerationRejection = 90.0f,
+            .magneticRejection = 90.0f,
+            .recoveryTriggerPeriod = 0,
+    };
+    FusionAhrsSetSettings(ahrs, &settings);
+    FusionAhrsReset(ahrs);
+}
+
+/**
+ * @brief Resets the AHRS algorithm. This is equivalent to reinitialising the
+ * algorithm while maintaining the current settings.
+ * @param ahrs AHRS algorithm structure.
+ */
+void FusionAhrsReset(FusionAhrs *const ahrs) {
+    ahrs->quaternion = FUSION_IDENTITY_QUATERNION;
+    ahrs->accelerometer = FUSION_VECTOR_ZERO;
+    ahrs->initialising = true;
+    ahrs->rampedGain = INITIAL_GAIN;
+    ahrs->angularRateRecovery = false;
+    ahrs->halfAccelerometerFeedback = FUSION_VECTOR_ZERO;
+    ahrs->halfMagnetometerFeedback = FUSION_VECTOR_ZERO;
+    ahrs->accelerometerIgnored = false;
+    ahrs->accelerationRecoveryTrigger = 0;
+    ahrs->accelerationRecoveryTimeout = ahrs->settings.recoveryTriggerPeriod;
+    ahrs->magnetometerIgnored = false;
+    ahrs->magneticRecoveryTrigger = 0;
+    ahrs->magneticRecoveryTimeout = ahrs->settings.recoveryTriggerPeriod;
+}
+
+/**
+ * @brief Sets the AHRS algorithm settings.
+ * @param ahrs AHRS algorithm structure.
+ * @param settings Settings.
+ */
+void FusionAhrsSetSettings(FusionAhrs *const ahrs, const FusionAhrsSettings *const settings) {
+    ahrs->settings.convention = settings->convention;
+    ahrs->settings.gain = settings->gain;
+    ahrs->settings.gyroscopeRange = settings->gyroscopeRange == 0.0f ? FLT_MAX : 0.98f * settings->gyroscopeRange;
+    ahrs->settings.accelerationRejection = settings->accelerationRejection == 0.0f ? FLT_MAX : powf(0.5f * sinf(FusionDegreesToRadians(settings->accelerationRejection)), 2);
+    ahrs->settings.magneticRejection = settings->magneticRejection == 0.0f ? FLT_MAX : powf(0.5f * sinf(FusionDegreesToRadians(settings->magneticRejection)), 2);
+    ahrs->settings.recoveryTriggerPeriod = settings->recoveryTriggerPeriod;
+    ahrs->accelerationRecoveryTimeout = ahrs->settings.recoveryTriggerPeriod;
+    ahrs->magneticRecoveryTimeout = ahrs->settings.recoveryTriggerPeriod;
+    if ((settings->gain == 0.0f) || (settings->recoveryTriggerPeriod == 0)) { // disable acceleration and magnetic rejection features if gain is zero
+        ahrs->settings.accelerationRejection = FLT_MAX;
+        ahrs->settings.magneticRejection = FLT_MAX;
+    }
+    if (ahrs->initialising == false) {
+        ahrs->rampedGain = ahrs->settings.gain;
+    }
+    ahrs->rampedGainStep = (INITIAL_GAIN - ahrs->settings.gain) / INITIALISATION_PERIOD;
+}
+
+/**
+ * @brief Updates the AHRS algorithm using the gyroscope, accelerometer, and
+ * magnetometer measurements.
+ * @param ahrs AHRS algorithm structure.
+ * @param gyroscope Gyroscope measurement in degrees per second.
+ * @param accelerometer Accelerometer measurement in g.
+ * @param magnetometer Magnetometer measurement in arbitrary units.
+ * @param deltaTime Delta time in seconds.
+ */
+void FusionAhrsUpdate(FusionAhrs *const ahrs, const FusionVector gyroscope, const FusionVector accelerometer, const FusionVector magnetometer, const float deltaTime) {
+#define Q ahrs->quaternion.element
+
+    // Store accelerometer
+    ahrs->accelerometer = accelerometer;
+
+    // Reinitialise if gyroscope range exceeded
+    if ((fabsf(gyroscope.axis.x) > ahrs->settings.gyroscopeRange) || (fabsf(gyroscope.axis.y) > ahrs->settings.gyroscopeRange) || (fabsf(gyroscope.axis.z) > ahrs->settings.gyroscopeRange)) {
+        const FusionQuaternion quaternion = ahrs->quaternion;
+        FusionAhrsReset(ahrs);
+        ahrs->quaternion = quaternion;
+        ahrs->angularRateRecovery = true;
+    }
+
+    // Ramp down gain during initialisation
+    if (ahrs->initialising) {
+        ahrs->rampedGain -= ahrs->rampedGainStep * deltaTime;
+        if ((ahrs->rampedGain < ahrs->settings.gain) || (ahrs->settings.gain == 0.0f)) {
+            ahrs->rampedGain = ahrs->settings.gain;
+            ahrs->initialising = false;
+            ahrs->angularRateRecovery = false;
+        }
+    }
+
+    // Calculate direction of gravity indicated by algorithm
+    const FusionVector halfGravity = HalfGravity(ahrs);
+
+    // Calculate accelerometer feedback
+    FusionVector halfAccelerometerFeedback = FUSION_VECTOR_ZERO;
+    ahrs->accelerometerIgnored = true;
+    if (FusionVectorIsZero(accelerometer) == false) {
+
+        // Calculate accelerometer feedback scaled by 0.5
+        ahrs->halfAccelerometerFeedback = Feedback(FusionVectorNormalise(accelerometer), halfGravity);
+
+        // Don't ignore accelerometer if acceleration error below threshold
+        if (ahrs->initialising || ((FusionVectorMagnitudeSquared(ahrs->halfAccelerometerFeedback) <= ahrs->settings.accelerationRejection))) {
+            ahrs->accelerometerIgnored = false;
+            ahrs->accelerationRecoveryTrigger -= 9;
+        } else {
+            ahrs->accelerationRecoveryTrigger += 1;
+        }
+
+        // Don't ignore accelerometer during acceleration recovery
+        if (ahrs->accelerationRecoveryTrigger > ahrs->accelerationRecoveryTimeout) {
+            ahrs->accelerationRecoveryTimeout = 0;
+            ahrs->accelerometerIgnored = false;
+        } else {
+            ahrs->accelerationRecoveryTimeout = ahrs->settings.recoveryTriggerPeriod;
+        }
+        ahrs->accelerationRecoveryTrigger = Clamp(ahrs->accelerationRecoveryTrigger, 0, ahrs->settings.recoveryTriggerPeriod);
+
+        // Apply accelerometer feedback
+        if (ahrs->accelerometerIgnored == false) {
+            halfAccelerometerFeedback = ahrs->halfAccelerometerFeedback;
+        }
+    }
+
+    // Calculate magnetometer feedback
+    FusionVector halfMagnetometerFeedback = FUSION_VECTOR_ZERO;
+    ahrs->magnetometerIgnored = true;
+    if (FusionVectorIsZero(magnetometer) == false) {
+
+        // Calculate direction of magnetic field indicated by algorithm
+        const FusionVector halfMagnetic = HalfMagnetic(ahrs);
+
+        // Calculate magnetometer feedback scaled by 0.5
+        ahrs->halfMagnetometerFeedback = Feedback(FusionVectorNormalise(FusionVectorCrossProduct(halfGravity, magnetometer)), halfMagnetic);
+
+        // Don't ignore magnetometer if magnetic error below threshold
+        if (ahrs->initialising || ((FusionVectorMagnitudeSquared(ahrs->halfMagnetometerFeedback) <= ahrs->settings.magneticRejection))) {
+            ahrs->magnetometerIgnored = false;
+            ahrs->magneticRecoveryTrigger -= 9;
+        } else {
+            ahrs->magneticRecoveryTrigger += 1;
+        }
+
+        // Don't ignore magnetometer during magnetic recovery
+        if (ahrs->magneticRecoveryTrigger > ahrs->magneticRecoveryTimeout) {
+            ahrs->magneticRecoveryTimeout = 0;
+            ahrs->magnetometerIgnored = false;
+        } else {
+            ahrs->magneticRecoveryTimeout = ahrs->settings.recoveryTriggerPeriod;
+        }
+        ahrs->magneticRecoveryTrigger = Clamp(ahrs->magneticRecoveryTrigger, 0, ahrs->settings.recoveryTriggerPeriod);
+
+        // Apply magnetometer feedback
+        if (ahrs->magnetometerIgnored == false) {
+            halfMagnetometerFeedback = ahrs->halfMagnetometerFeedback;
+        }
+    }
+
+    // Convert gyroscope to radians per second scaled by 0.5
+    const FusionVector halfGyroscope = FusionVectorMultiplyScalar(gyroscope, FusionDegreesToRadians(0.5f));
+
+    // Apply feedback to gyroscope
+    const FusionVector adjustedHalfGyroscope = FusionVectorAdd(halfGyroscope, FusionVectorMultiplyScalar(FusionVectorAdd(halfAccelerometerFeedback, halfMagnetometerFeedback), ahrs->rampedGain));
+
+    // Integrate rate of change of quaternion
+    ahrs->quaternion = FusionQuaternionAdd(ahrs->quaternion, FusionQuaternionMultiplyVector(ahrs->quaternion, FusionVectorMultiplyScalar(adjustedHalfGyroscope, deltaTime)));
+
+    // Normalise quaternion
+    ahrs->quaternion = FusionQuaternionNormalise(ahrs->quaternion);
+#undef Q
+}
+
+/**
+ * @brief Returns the direction of gravity scaled by 0.5.
+ * @param ahrs AHRS algorithm structure.
+ * @return Direction of gravity scaled by 0.5.
+ */
+static inline FusionVector HalfGravity(const FusionAhrs *const ahrs) {
+#define Q ahrs->quaternion.element
+    switch (ahrs->settings.convention) {
+        case FusionConventionNwu:
+        case FusionConventionEnu: {
+            const FusionVector halfGravity = {.axis = {
+                    .x = Q.x * Q.z - Q.w * Q.y,
+                    .y = Q.y * Q.z + Q.w * Q.x,
+                    .z = Q.w * Q.w - 0.5f + Q.z * Q.z,
+            }}; // third column of transposed rotation matrix scaled by 0.5
+            return halfGravity;
+        }
+        case FusionConventionNed: {
+            const FusionVector halfGravity = {.axis = {
+                    .x = Q.w * Q.y - Q.x * Q.z,
+                    .y = -1.0f * (Q.y * Q.z + Q.w * Q.x),
+                    .z = 0.5f - Q.w * Q.w - Q.z * Q.z,
+            }}; // third column of transposed rotation matrix scaled by -0.5
+            return halfGravity;
+        }
+    }
+    return FUSION_VECTOR_ZERO; // avoid compiler warning
+#undef Q
+}
+
+/**
+ * @brief Returns the direction of the magnetic field scaled by 0.5.
+ * @param ahrs AHRS algorithm structure.
+ * @return Direction of the magnetic field scaled by 0.5.
+ */
+static inline FusionVector HalfMagnetic(const FusionAhrs *const ahrs) {
+#define Q ahrs->quaternion.element
+    switch (ahrs->settings.convention) {
+        case FusionConventionNwu: {
+            const FusionVector halfMagnetic = {.axis = {
+                    .x = Q.x * Q.y + Q.w * Q.z,
+                    .y = Q.w * Q.w - 0.5f + Q.y * Q.y,
+                    .z = Q.y * Q.z - Q.w * Q.x,
+            }}; // second column of transposed rotation matrix scaled by 0.5
+            return halfMagnetic;
+        }
+        case FusionConventionEnu: {
+            const FusionVector halfMagnetic = {.axis = {
+                    .x = 0.5f - Q.w * Q.w - Q.x * Q.x,
+                    .y = Q.w * Q.z - Q.x * Q.y,
+                    .z = -1.0f * (Q.x * Q.z + Q.w * Q.y),
+            }}; // first column of transposed rotation matrix scaled by -0.5
+            return halfMagnetic;
+        }
+        case FusionConventionNed: {
+            const FusionVector halfMagnetic = {.axis = {
+                    .x = -1.0f * (Q.x * Q.y + Q.w * Q.z),
+                    .y = 0.5f - Q.w * Q.w - Q.y * Q.y,
+                    .z = Q.w * Q.x - Q.y * Q.z,
+            }}; // second column of transposed rotation matrix scaled by -0.5
+            return halfMagnetic;
+        }
+    }
+    return FUSION_VECTOR_ZERO; // avoid compiler warning
+#undef Q
+}
+
+/**
+ * @brief Returns the feedback.
+ * @param sensor Sensor.
+ * @param reference Reference.
+ * @return Feedback.
+ */
+static inline FusionVector Feedback(const FusionVector sensor, const FusionVector reference) {
+    if (FusionVectorDotProduct(sensor, reference) < 0.0f) { // if error is >90 degrees
+        return FusionVectorNormalise(FusionVectorCrossProduct(sensor, reference));
+    }
+    return FusionVectorCrossProduct(sensor, reference);
+}
+
+/**
+ * @brief Returns a value limited to maximum and minimum.
+ * @param value Value.
+ * @param min Minimum value.
+ * @param max Maximum value.
+ * @return Value limited to maximum and minimum.
+ */
+static inline int Clamp(const int value, const int min, const int max) {
+    if (value < min) {
+        return min;
+    }
+    if (value > max) {
+        return max;
+    }
+    return value;
+}
+
+/**
+ * @brief Updates the AHRS algorithm using the gyroscope and accelerometer
+ * measurements only.
+ * @param ahrs AHRS algorithm structure.
+ * @param gyroscope Gyroscope measurement in degrees per second.
+ * @param accelerometer Accelerometer measurement in g.
+ * @param deltaTime Delta time in seconds.
+ */
+void FusionAhrsUpdateNoMagnetometer(FusionAhrs *const ahrs, const FusionVector gyroscope, const FusionVector accelerometer, const float deltaTime) {
+
+    // Update AHRS algorithm
+    FusionAhrsUpdate(ahrs, gyroscope, accelerometer, FUSION_VECTOR_ZERO, deltaTime);
+
+    // Zero heading during initialisation
+    if (ahrs->initialising) {
+        FusionAhrsSetHeading(ahrs, 0.0f);
+    }
+}
+
+/**
+ * @brief Updates the AHRS algorithm using the gyroscope, accelerometer, and
+ * heading measurements.
+ * @param ahrs AHRS algorithm structure.
+ * @param gyroscope Gyroscope measurement in degrees per second.
+ * @param accelerometer Accelerometer measurement in g.
+ * @param heading Heading measurement in degrees.
+ * @param deltaTime Delta time in seconds.
+ */
+void FusionAhrsUpdateExternalHeading(FusionAhrs *const ahrs, const FusionVector gyroscope, const FusionVector accelerometer, const float heading, const float deltaTime) {
+#define Q ahrs->quaternion.element
+
+    // Calculate roll
+    const float roll = atan2f(Q.w * Q.x + Q.y * Q.z, 0.5f - Q.y * Q.y - Q.x * Q.x);
+
+    // Calculate magnetometer
+    const float headingRadians = FusionDegreesToRadians(heading);
+    const float sinHeadingRadians = sinf(headingRadians);
+    const FusionVector magnetometer = {.axis = {
+            .x = cosf(headingRadians),
+            .y = -1.0f * cosf(roll) * sinHeadingRadians,
+            .z = sinHeadingRadians * sinf(roll),
+    }};
+
+    // Update AHRS algorithm
+    FusionAhrsUpdate(ahrs, gyroscope, accelerometer, magnetometer, deltaTime);
+#undef Q
+}
+
+/**
+ * @brief Returns the quaternion describing the sensor relative to the Earth.
+ * @param ahrs AHRS algorithm structure.
+ * @return Quaternion describing the sensor relative to the Earth.
+ */
+FusionQuaternion FusionAhrsGetQuaternion(const FusionAhrs *const ahrs) {
+    return ahrs->quaternion;
+}
+
+/**
+ * @brief Sets the quaternion describing the sensor relative to the Earth.
+ * @param ahrs AHRS algorithm structure.
+ * @param quaternion Quaternion describing the sensor relative to the Earth.
+ */
+void FusionAhrsSetQuaternion(FusionAhrs *const ahrs, const FusionQuaternion quaternion) {
+    ahrs->quaternion = quaternion;
+}
+
+/**
+ * @brief Returns the direction of gravity in the sensor coordinate frame.
+ * @param ahrs AHRS algorithm structure.
+ * @return Direction of gravity in the sensor coordinate frame.
+ */
+FusionVector FusionAhrsGetGravity(const FusionAhrs *const ahrs) {
+#define Q ahrs->quaternion.element
+    const FusionVector gravity = {.axis = {
+            .x = 2.0f * (Q.x * Q.z - Q.w * Q.y),
+            .y = 2.0f * (Q.y * Q.z + Q.w * Q.x),
+            .z = 2.0f * (Q.w * Q.w - 0.5f + Q.z * Q.z),
+    }}; // third column of transposed rotation matrix
+    return gravity;
+#undef Q
+}
+
+/**
+ * @brief Returns the linear acceleration measurement equal to the accelerometer
+ * measurement with gravity removed.
+ * @param ahrs AHRS algorithm structure.
+ * @return Linear acceleration measurement in g.
+ */
+FusionVector FusionAhrsGetLinearAcceleration(const FusionAhrs *const ahrs) {
+    switch (ahrs->settings.convention) {
+        case FusionConventionNwu:
+        case FusionConventionEnu: {
+            return FusionVectorSubtract(ahrs->accelerometer, FusionAhrsGetGravity(ahrs));
+        }
+        case FusionConventionNed: {
+            return FusionVectorAdd(ahrs->accelerometer, FusionAhrsGetGravity(ahrs));
+        }
+    }
+    return FUSION_VECTOR_ZERO; // avoid compiler warning
+}
+
+/**
+ * @brief Returns the Earth acceleration measurement equal to accelerometer
+ * measurement in the Earth coordinate frame with gravity removed.
+ * @param ahrs AHRS algorithm structure.
+ * @return Earth acceleration measurement in g.
+ */
+FusionVector FusionAhrsGetEarthAcceleration(const FusionAhrs *const ahrs) {
+#define Q ahrs->quaternion.element
+#define A ahrs->accelerometer.axis
+
+    // Calculate accelerometer measurement in the Earth coordinate frame
+    const float qwqw = Q.w * Q.w; // calculate common terms to avoid repeated operations
+    const float qwqx = Q.w * Q.x;
+    const float qwqy = Q.w * Q.y;
+    const float qwqz = Q.w * Q.z;
+    const float qxqy = Q.x * Q.y;
+    const float qxqz = Q.x * Q.z;
+    const float qyqz = Q.y * Q.z;
+    FusionVector accelerometer = {.axis = {
+            .x = 2.0f * ((qwqw - 0.5f + Q.x * Q.x) * A.x + (qxqy - qwqz) * A.y + (qxqz + qwqy) * A.z),
+            .y = 2.0f * ((qxqy + qwqz) * A.x + (qwqw - 0.5f + Q.y * Q.y) * A.y + (qyqz - qwqx) * A.z),
+            .z = 2.0f * ((qxqz - qwqy) * A.x + (qyqz + qwqx) * A.y + (qwqw - 0.5f + Q.z * Q.z) * A.z),
+    }}; // rotation matrix multiplied with the accelerometer
+
+    // Remove gravity from accelerometer measurement
+    switch (ahrs->settings.convention) {
+        case FusionConventionNwu:
+        case FusionConventionEnu:
+            accelerometer.axis.z -= 1.0f;
+            break;
+        case FusionConventionNed:
+            accelerometer.axis.z += 1.0f;
+            break;
+    }
+    return accelerometer;
+#undef Q
+#undef A
+}
+
+/**
+ * @brief Returns the AHRS algorithm internal states.
+ * @param ahrs AHRS algorithm structure.
+ * @return AHRS algorithm internal states.
+ */
+FusionAhrsInternalStates FusionAhrsGetInternalStates(const FusionAhrs *const ahrs) {
+    const FusionAhrsInternalStates internalStates = {
+            .accelerationError = FusionRadiansToDegrees(FusionAsin(2.0f * FusionVectorMagnitude(ahrs->halfAccelerometerFeedback))),
+            .accelerometerIgnored = ahrs->accelerometerIgnored,
+            .accelerationRecoveryTrigger = ahrs->settings.recoveryTriggerPeriod == 0 ? 0.0f : (float) ahrs->accelerationRecoveryTrigger / (float) ahrs->settings.recoveryTriggerPeriod,
+            .magneticError = FusionRadiansToDegrees(FusionAsin(2.0f * FusionVectorMagnitude(ahrs->halfMagnetometerFeedback))),
+            .magnetometerIgnored = ahrs->magnetometerIgnored,
+            .magneticRecoveryTrigger = ahrs->settings.recoveryTriggerPeriod == 0 ? 0.0f : (float) ahrs->magneticRecoveryTrigger / (float) ahrs->settings.recoveryTriggerPeriod,
+    };
+    return internalStates;
+}
+
+/**
+ * @brief Returns the AHRS algorithm flags.
+ * @param ahrs AHRS algorithm structure.
+ * @return AHRS algorithm flags.
+ */
+FusionAhrsFlags FusionAhrsGetFlags(const FusionAhrs *const ahrs) {
+    const FusionAhrsFlags flags = {
+            .initialising = ahrs->initialising,
+            .angularRateRecovery = ahrs->angularRateRecovery,
+            .accelerationRecovery = ahrs->accelerationRecoveryTrigger > ahrs->accelerationRecoveryTimeout,
+            .magneticRecovery= ahrs->magneticRecoveryTrigger > ahrs->magneticRecoveryTimeout,
+    };
+    return flags;
+}
+
+/**
+ * @brief Sets the heading of the orientation measurement provided by the AHRS
+ * algorithm. This function can be used to reset drift in heading when the AHRS
+ * algorithm is being used without a magnetometer.
+ * @param ahrs AHRS algorithm structure.
+ * @param heading Heading angle in degrees.
+ */
+void FusionAhrsSetHeading(FusionAhrs *const ahrs, const float heading) {
+#define Q ahrs->quaternion.element
+    const float yaw = atan2f(Q.w * Q.z + Q.x * Q.y, 0.5f - Q.y * Q.y - Q.z * Q.z);
+    const float halfYawMinusHeading = 0.5f * (yaw - FusionDegreesToRadians(heading));
+    const FusionQuaternion rotation = {.element = {
+            .w = cosf(halfYawMinusHeading),
+            .x = 0.0f,
+            .y = 0.0f,
+            .z = -1.0f * sinf(halfYawMinusHeading),
+    }};
+    ahrs->quaternion = FusionQuaternionMultiply(rotation, ahrs->quaternion);
+#undef Q
+}
+
+//------------------------------------------------------------------------------
+// End of file