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Accelerometer Tolerance is now calibrated before Gyro Drift.

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This commit is contained in:
Aubrey Hesselgren
2025-07-21 16:39:32 -07:00
committed by Sam Lantinga
parent 07ef532681
commit 6bfc54508c
3 changed files with 187 additions and 71 deletions
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100
test/gamepadutils.c
View File

@@ -1031,8 +1031,10 @@ struct GyroDisplay
int estimated_sensor_rate_hz; /*hz - our estimation of the actual polling rate by observing packets received*/
float euler_displacement_angles[3]; /* pitch, yaw, roll */
Quaternion gyro_quaternion; /* Rotation since startup/reset, comprised of each gyro speed packet times sensor delta time. */
float drift_calibration_progress_frac; /* [0..1] */
EGyroCalibrationPhase current_calibration_phase;
float calibration_phase_progress_fraction; /* [0..1] */
float accelerometer_noise_sq; /* Distance between last noise and new noise. Used to indicate motion.*/
float accelerometer_noise_tolerance_sq; /* Maximum amount of noise detected during the Noise Profiling Phase */
GamepadButton *reset_gyro_button;
GamepadButton *calibrate_gyro_button;
@@ -1049,6 +1051,10 @@ GyroDisplay *CreateGyroDisplay(SDL_Renderer *renderer)
ctx->gyro_quaternion = quat_identity;
ctx->reported_sensor_rate_hz = 0;
ctx->next_reported_sensor_time = 0;
ctx->current_calibration_phase = GYRO_CALIBRATION_PHASE_OFF;
ctx->calibration_phase_progress_fraction = 0.0f; /* [0..1] */
ctx->accelerometer_noise_sq = 0.0f;
ctx->accelerometer_noise_tolerance_sq = ACCELEROMETER_NOISE_THRESHOLD; /* Will be overwritten but this avoids divide by zero. */
ctx->reset_gyro_button = CreateGamepadButton(renderer, "Reset View");
ctx->calibrate_gyro_button = CreateGamepadButton(renderer, "Recalibrate Drift");
}
@@ -1362,17 +1368,7 @@ static void RenderGamepadElementHighlight(GamepadDisplay *ctx, int element, cons
}
}
bool BHasCachedGyroDriftSolution(GyroDisplay *ctx)
{
if (!ctx) {
return false;
}
return (ctx->gyro_drift_solution[0] != 0.0f ||
ctx->gyro_drift_solution[1] != 0.0f ||
ctx->gyro_drift_solution[2] != 0.0f);
}
void SetGamepadDisplayIMUValues(GyroDisplay *ctx, float *gyro_drift_solution, float *euler_displacement_angles, Quaternion *gyro_quaternion, int reported_senor_rate_hz, int estimated_sensor_rate_hz, float drift_calibration_progress_frac, float accelerometer_noise_sq)
void SetGamepadDisplayIMUValues(GyroDisplay *ctx, float *gyro_drift_solution, float *euler_displacement_angles, Quaternion *gyro_quaternion, int reported_senor_rate_hz, int estimated_sensor_rate_hz, EGyroCalibrationPhase calibration_phase, float drift_calibration_progress_frac, float accelerometer_noise_sq, float accelerometer_noise_tolerance_sq)
{
if (!ctx) {
return;
@@ -1391,8 +1387,10 @@ void SetGamepadDisplayIMUValues(GyroDisplay *ctx, float *gyro_drift_solution, fl
SDL_memcpy(ctx->gyro_drift_solution, gyro_drift_solution, sizeof(ctx->gyro_drift_solution));
SDL_memcpy(ctx->euler_displacement_angles, euler_displacement_angles, sizeof(ctx->euler_displacement_angles));
ctx->gyro_quaternion = *gyro_quaternion;
ctx->drift_calibration_progress_frac = drift_calibration_progress_frac;
ctx->current_calibration_phase = calibration_phase;
ctx->calibration_phase_progress_fraction = drift_calibration_progress_frac;
ctx->accelerometer_noise_sq = accelerometer_noise_sq;
ctx->accelerometer_noise_tolerance_sq = accelerometer_noise_tolerance_sq;
}
extern GamepadButton *GetGyroResetButton(GyroDisplay *ctx)
@@ -1713,7 +1711,7 @@ void RenderSensorTimingInfo(GyroDisplay *ctx, GamepadDisplay *gamepad_display)
/* Sensor timing section */
char text[128];
const float new_line_height = gamepad_display->button_height + 2.0f;
const float text_offset_x = ctx->area.x + ctx->area.w / 4.0f + 40.0f;
const float text_offset_x = ctx->area.x + ctx->area.w / 4.0f + 35.0f;
/* Anchor to bottom left of principle rect. */
float text_y_pos = ctx->area.y + ctx->area.h - new_line_height * 2;
/*
@@ -1759,7 +1757,7 @@ void RenderGyroDriftCalibrationButton(GyroDisplay *ctx, GamepadDisplay *gamepad_
float log_y = ctx->area.y + BUTTON_PADDING;
const float new_line_height = gamepad_display->button_height + 2.0f;
GamepadButton *start_calibration_button = GetGyroCalibrateButton(ctx);
bool bHasCachedDriftSolution = BHasCachedGyroDriftSolution(ctx);
/* Show the recalibration progress bar. */
float recalibrate_button_width = GetGamepadButtonLabelWidth(start_calibration_button) + 2 * BUTTON_PADDING;
@@ -1769,24 +1767,46 @@ void RenderGyroDriftCalibrationButton(GyroDisplay *ctx, GamepadDisplay *gamepad_
recalibrate_button_area.w = GetGamepadButtonLabelWidth(start_calibration_button) + 2.0f * BUTTON_PADDING;
recalibrate_button_area.h = gamepad_display->button_height + BUTTON_PADDING * 2.0f;
if (!bHasCachedDriftSolution) {
SDL_snprintf(label_text, sizeof(label_text), "Progress: %3.0f%% ", ctx->drift_calibration_progress_frac * 100.0f);
} else {
SDL_strlcpy(label_text, "Calibrate Drift", sizeof(label_text));
/* Above button */
SDL_strlcpy(label_text, "Gyro Orientation:", sizeof(label_text));
SDLTest_DrawString(ctx->renderer, recalibrate_button_area.x, recalibrate_button_area.y - new_line_height, label_text);
/* Button label vs state */
if (ctx->current_calibration_phase == GYRO_CALIBRATION_PHASE_OFF) {
SDL_strlcpy(label_text, "Start Gyro Calibration", sizeof(label_text));
} else if (ctx->current_calibration_phase == GYRO_CALIBRATION_PHASE_NOISE_PROFILING) {
SDL_snprintf(label_text, sizeof(label_text), "Noise Progress: %3.0f%% ", ctx->calibration_phase_progress_fraction * 100.0f);
} else if (ctx->current_calibration_phase == GYRO_CALIBRATION_PHASE_DRIFT_PROFILING) {
SDL_snprintf(label_text, sizeof(label_text), "Drift Progress: %3.0f%% ", ctx->calibration_phase_progress_fraction * 100.0f);
} else if (ctx->current_calibration_phase == GYRO_CALIBRATION_PHASE_COMPLETE) {
SDL_strlcpy(label_text, "Recalibrate Gyro", sizeof(label_text));
}
SetGamepadButtonLabel(start_calibration_button, label_text);
SetGamepadButtonArea(start_calibration_button, &recalibrate_button_area);
RenderGamepadButton(start_calibration_button);
/* Above button */
SDL_strlcpy(label_text, "Gyro Orientation:", sizeof(label_text));
SDLTest_DrawString(ctx->renderer, recalibrate_button_area.x, recalibrate_button_area.y - new_line_height, label_text);
const float flAbsoluteMaxAccelerationG = 0.125f;
bool bExtremeNoise = ctx->accelerometer_noise_sq > (flAbsoluteMaxAccelerationG * flAbsoluteMaxAccelerationG);
/* Explicit warning message if we detect too much movement */
if (ctx->current_calibration_phase == GYRO_CALIBRATION_PHASE_OFF) {
if (!bHasCachedDriftSolution) {
if (bExtremeNoise)
{
SDL_strlcpy(label_text, "GamePad Must Be Still", sizeof(label_text));
SDLTest_DrawString(ctx->renderer, recalibrate_button_area.x, recalibrate_button_area.y + recalibrate_button_area.h + new_line_height, label_text);
SDL_strlcpy(label_text, "Place GamePad On Table", sizeof(label_text));
SDLTest_DrawString(ctx->renderer, recalibrate_button_area.x, recalibrate_button_area.y + recalibrate_button_area.h + new_line_height * 2, label_text);
}
}
float flNoiseFraction = SDL_clamp(SDL_sqrtf(ctx->accelerometer_noise_sq) / ACCELEROMETER_NOISE_THRESHOLD, 0.0f, 1.0f);
bool bTooMuchNoise = (flNoiseFraction == 1.0f);
if (ctx->current_calibration_phase == GYRO_CALIBRATION_PHASE_NOISE_PROFILING
|| ctx->current_calibration_phase == GYRO_CALIBRATION_PHASE_DRIFT_PROFILING)
{
float flAbsoluteNoiseFraction = SDL_clamp(ctx->accelerometer_noise_sq / (flAbsoluteMaxAccelerationG * flAbsoluteMaxAccelerationG), 0.0f, 1.0f);
float flAbsoluteToleranceFraction = SDL_clamp(ctx->accelerometer_noise_tolerance_sq / (flAbsoluteMaxAccelerationG * flAbsoluteMaxAccelerationG), 0.0f, 1.0f);
float flRelativeNoiseFraction = SDL_clamp(ctx->accelerometer_noise_sq / ctx->accelerometer_noise_tolerance_sq, 0.0f, 1.0f);
bool bTooMuchNoise = (flAbsoluteNoiseFraction == 1.0f);
float noise_bar_height = gamepad_display->button_height;
SDL_FRect noise_bar_rect;
@@ -1795,21 +1815,35 @@ void RenderGyroDriftCalibrationButton(GyroDisplay *ctx, GamepadDisplay *gamepad_
noise_bar_rect.w = recalibrate_button_area.w;
noise_bar_rect.h = noise_bar_height;
//SDL_strlcpy(label_text, "Place GamePad On Table", sizeof(label_text));
SDL_snprintf(label_text, sizeof(label_text), "Noise Tolerance: %3.3fG ", SDL_sqrtf(ctx->accelerometer_noise_tolerance_sq) );
SDLTest_DrawString(ctx->renderer, recalibrate_button_area.x, recalibrate_button_area.y + recalibrate_button_area.h + new_line_height * 2, label_text);
/* Adjust the noise bar rectangle based on the accelerometer noise value */
float noise_bar_fill_width = flNoiseFraction * noise_bar_rect.w; /* Scale the width based on the noise value */
float noise_bar_fill_width = flAbsoluteNoiseFraction * noise_bar_rect.w; /* Scale the width based on the noise value */
SDL_FRect noise_bar_fill_rect;
noise_bar_fill_rect.x = noise_bar_rect.x + (noise_bar_rect.w - noise_bar_fill_width) * 0.5f;
noise_bar_fill_rect.y = noise_bar_rect.y;
noise_bar_fill_rect.w = noise_bar_fill_width;
noise_bar_fill_rect.h = noise_bar_height;
/* Set the color based on the noise value */
Uint8 red = (Uint8)(flNoiseFraction * 255.0f);
Uint8 green = (Uint8)((1.0f - flNoiseFraction) * 255.0f);
/* Set the color based on the noise value vs the tolerance */
Uint8 red = (Uint8)(flRelativeNoiseFraction * 255.0f);
Uint8 green = (Uint8)((1.0f - flRelativeNoiseFraction) * 255.0f);
SDL_SetRenderDrawColor(ctx->renderer, red, green, 0, 255); /* red when high noise, green when low noise */
SDL_RenderFillRect(ctx->renderer, &noise_bar_fill_rect); /* draw the filled rectangle */
float tolerance_bar_fill_width = flAbsoluteToleranceFraction * noise_bar_rect.w; /* Scale the width based on the noise value */
SDL_FRect tolerance_bar_rect;
tolerance_bar_rect.x = noise_bar_rect.x + (noise_bar_rect.w - tolerance_bar_fill_width) * 0.5f;
tolerance_bar_rect.y = noise_bar_rect.y;
tolerance_bar_rect.w = tolerance_bar_fill_width;
tolerance_bar_rect.h = noise_bar_height;
SDL_SetRenderDrawColor(ctx->renderer, 128, 128, 0, 255);
SDL_RenderRect(ctx->renderer, &tolerance_bar_rect); /* draw the tolerance rectangle */
SDL_SetRenderDrawColor(ctx->renderer, 100, 100, 100, 255); /* gray box */
SDL_RenderRect(ctx->renderer, &noise_bar_rect); /* draw the outline rectangle */
@@ -1828,7 +1862,7 @@ void RenderGyroDriftCalibrationButton(GyroDisplay *ctx, GamepadDisplay *gamepad_
progress_bar_rect.h = BUTTON_PADDING * 0.5f;
/* Adjust the drift bar rectangle based on the drift calibration progress fraction */
float drift_bar_fill_width = bTooMuchNoise ? 1.0f : ctx->drift_calibration_progress_frac * progress_bar_rect.w;
float drift_bar_fill_width = bTooMuchNoise ? 1.0f : ctx->calibration_phase_progress_fraction * progress_bar_rect.w;
SDL_FRect progress_bar_fill;
progress_bar_fill.x = progress_bar_rect.x;
progress_bar_fill.y = progress_bar_rect.y;
@@ -1947,14 +1981,14 @@ void RenderGyroDisplay(GyroDisplay *ctx, GamepadDisplay *gamepadElements, SDL_Ga
SDL_GetRenderDrawColor(ctx->renderer, &r, &g, &b, &a);
RenderSensorTimingInfo(ctx, gamepadElements);
RenderGyroDriftCalibrationButton(ctx, gamepadElements);
bool bHasCachedDriftSolution = BHasCachedGyroDriftSolution(ctx);
if (bHasCachedDriftSolution) {
/* Render Gyro calibration phases */
if (ctx->current_calibration_phase == GYRO_CALIBRATION_PHASE_COMPLETE) {
float bottom = RenderEulerReadout(ctx, gamepadElements);
RenderGyroGizmo(ctx, gamepad, bottom);
}
SDL_SetRenderDrawColor(ctx->renderer, r, g, b, a);
}

18
test/gamepadutils.h
View File

@@ -142,16 +142,26 @@ extern void RenderGamepadButton(GamepadButton *ctx);
extern void DestroyGamepadButton(GamepadButton *ctx);
/* Gyro element Display */
/* If you want to calbirate against a known rotation (i.e. a turn table test) Increase ACCELEROMETER_NOISE_THRESHOLD to about 5, or drift correction will be constantly reset.*/
#define ACCELEROMETER_NOISE_THRESHOLD 0.5f
/* This is used as the initial noise tolernace threshold. It's set very close to zero to avoid divide by zero while we're evaluating the noise profile. Each controller may have a very different noise profile.*/
#define ACCELEROMETER_NOISE_THRESHOLD 1e-6f
/* Gyro Calibration Phases */
typedef enum
{
GYRO_CALIBRATION_PHASE_OFF, /* Calibration has not yet been evaluated - signal to the user to put the controller on a flat surface before beginning the calibration process */
GYRO_CALIBRATION_PHASE_NOISE_PROFILING, /* Find the max accelerometer noise for a fixed period */
GYRO_CALIBRATION_PHASE_DRIFT_PROFILING, /* Find the drift while the accelerometer is below the accelerometer noise tolerance */
GYRO_CALIBRATION_PHASE_COMPLETE, /* Calibration has finished */
} EGyroCalibrationPhase;
typedef struct Quaternion Quaternion;
typedef struct GyroDisplay GyroDisplay;
extern void InitCirclePoints3D();
extern GyroDisplay *CreateGyroDisplay(SDL_Renderer *renderer);
extern void SetGyroDisplayArea(GyroDisplay *ctx, const SDL_FRect *area);
extern bool BHasCachedGyroDriftSolution(GyroDisplay *ctx);
extern void SetGamepadDisplayIMUValues(GyroDisplay *ctx, float *gyro_drift_solution, float *euler_displacement_angles, Quaternion *gyro_quaternion, int reported_senor_rate_hz, int estimated_sensor_rate_hz, float drift_calibration_progress_frac, float accelerometer_noise_sq);
extern void SetGamepadDisplayIMUValues(GyroDisplay *ctx, float *gyro_drift_solution, float *euler_displacement_angles, Quaternion *gyro_quaternion, int reported_senor_rate_hz, int estimated_sensor_rate_hz, EGyroCalibrationPhase calibration_phase, float drift_calibration_progress_frac, float accelerometer_noise_sq, float accelerometer_noise_tolerance_sq);
extern GamepadButton *GetGyroResetButton(GyroDisplay *ctx);
extern GamepadButton *GetGyroCalibrateButton(GyroDisplay *ctx);
extern void RenderGyroDisplay(GyroDisplay *ctx, GamepadDisplay *gamepadElements, SDL_Gamepad *gamepad);

134
test/testcontroller.c
View File

@@ -156,23 +156,39 @@ typedef struct
float gyro_data[3]; /* Degrees per second, i.e. 100.0f means 100 degrees per second */
float last_accel_data[3];/* Needed to detect motion (and inhibit drift calibration) */
float accelerometer_length_squared;
float accelerometer_length_squared; /* The current length squared from last packet to this packet */
float accelerometer_tolerance_squared; /* In phase one of calibration we calculate this as the largest accelerometer_length_squared over the time period */
float gyro_drift_accumulator[3];
bool is_calibrating_drift; /* Starts on, but can be turned back on by the user to restart the drift calibration. */
EGyroCalibrationPhase calibration_phase; /* [ GYRO_CALIBRATION_PHASE_OFF, GYRO_CALIBRATION_PHASE_NOISE_PROFILING, GYRO_CALIBRATION_PHASE_DRIFT_PROFILING,GYRO_CALIBRATION_PHASE_COMPLETE ] */
Uint64 calibration_phase_start_time_ticks_ns; /* Set each time a calibration phase begins so that we can a real time number for evaluation of drift. Previously we would use a fixed number of packets but given that gyro polling rates vary wildly this made the duration very different. */
int gyro_drift_sample_count;
float gyro_drift_solution[3]; /* Non zero if calibration is complete. */
Quaternion integrated_rotation; /* Used to help test whether the time stamps and gyro degrees per second are set up correctly by the HID implementation */
} IMUState;
/* Reset the Drift calculation state */
void StartGyroDriftCalibration(IMUState *imustate)
/* First stage of calibration - get the noise profile of the accelerometer */
void BeginNoiseCalibrationPhase(IMUState *imustate)
{
imustate->is_calibrating_drift = true;
imustate->accelerometer_tolerance_squared = ACCELEROMETER_NOISE_THRESHOLD;
imustate->calibration_phase = GYRO_CALIBRATION_PHASE_NOISE_PROFILING;
imustate->calibration_phase_start_time_ticks_ns = SDL_GetTicksNS();
}
/* Reset the Drift calculation state */
void BeginDriftCalibrationPhase(IMUState *imustate)
{
imustate->calibration_phase = GYRO_CALIBRATION_PHASE_DRIFT_PROFILING;
imustate->calibration_phase_start_time_ticks_ns = SDL_GetTicksNS();
imustate->gyro_drift_sample_count = 0;
SDL_zeroa(imustate->gyro_drift_solution);
SDL_zeroa(imustate->gyro_drift_accumulator);
}
/* Initial/full reset of state */
void ResetIMUState(IMUState *imustate)
{
imustate->gyro_packet_number = 0;
@@ -180,10 +196,13 @@ void ResetIMUState(IMUState *imustate)
imustate->starting_time_stamp_ns = SDL_GetTicksNS();
imustate->integrated_rotation = quat_identity;
imustate->accelerometer_length_squared = 0.0f;
imustate->accelerometer_tolerance_squared = ACCELEROMETER_NOISE_THRESHOLD;
imustate->calibration_phase = GYRO_CALIBRATION_PHASE_OFF;
imustate->calibration_phase_start_time_ticks_ns = SDL_GetTicksNS();
imustate->integrated_rotation = quat_identity;
SDL_zeroa(imustate->last_accel_data);
SDL_zeroa(imustate->gyro_drift_solution);
StartGyroDriftCalibration(imustate);
SDL_zeroa(imustate->gyro_drift_accumulator);
}
void ResetGyroOrientation(IMUState *imustate)
@@ -191,8 +210,40 @@ void ResetGyroOrientation(IMUState *imustate)
imustate->integrated_rotation = quat_identity;
}
/* More samples = more accurate drift correction, but also more time to calibrate.*/
#define SDL_GAMEPAD_IMU_MIN_GYRO_DRIFT_SAMPLE_COUNT 1024
/* More time = more accurate drift correction*/
#define SDL_GAMEPAD_IMU_NOISE_SETTLING_PERIOD_NS (1 * SDL_NS_PER_SECOND)
#define SDL_GAMEPAD_IMU_NOISE_EVALUATION_PERIOD_NS (4 * SDL_NS_PER_SECOND)
#define SDL_GAMEPAD_IMU_NOISE_PROFILING_PHASE_DURATION_NS (SDL_GAMEPAD_IMU_NOISE_SETTLING_PERIOD_NS + SDL_GAMEPAD_IMU_NOISE_EVALUATION_PERIOD_NS)
#define SDL_GAMEPAD_IMU_CALIBRATION_PHASE_DURATION_NS (5 * SDL_NS_PER_SECOND)
/*
* Find the maximum accelerometer noise over the duration of the GYRO_CALIBRATION_PHASE_NOISE_PROFILING phase.
*/
void CalibrationPhase_NoiseProfiling(IMUState *imustate)
{
/* If we have really large movement (i.e. greater than a fraction of G), then we want to start noise evaluation over. The frontend will warn the user to put down the controller. */
const float flAbsoluteMaxAccelerationG = 0.125f;
if (imustate->accelerometer_length_squared > (flAbsoluteMaxAccelerationG * flAbsoluteMaxAccelerationG) ) {
BeginNoiseCalibrationPhase(imustate);
return;
}
Uint64 now = SDL_GetTicksNS();
Uint64 delta_ns = now - imustate->calibration_phase_start_time_ticks_ns;
/* Nuanced behavior - give the evaluation system some time to settle after placing the controller down before _actually_ evaluating, as the accelerometer could still be "ringing" after the user has placed it down, resulting in exaggerated tolerances */
if (delta_ns > SDL_GAMEPAD_IMU_NOISE_SETTLING_PERIOD_NS) {
/* Get the largest noise spike in the period of evaluation */
if (imustate->accelerometer_length_squared > imustate->accelerometer_tolerance_squared) {
imustate->accelerometer_tolerance_squared = imustate->accelerometer_length_squared;
}
}
/* Switch phase if we go over the time limit */
if (delta_ns >= SDL_GAMEPAD_IMU_NOISE_PROFILING_PHASE_DURATION_NS) {
BeginDriftCalibrationPhase(imustate);
}
}
/*
* Average drift _per packet_ as opposed to _per second_
@@ -200,36 +251,22 @@ void ResetGyroOrientation(IMUState *imustate)
*/
void FinalizeDriftSolution(IMUState *imustate)
{
if (imustate->gyro_drift_sample_count >= SDL_GAMEPAD_IMU_MIN_GYRO_DRIFT_SAMPLE_COUNT) {
if (imustate->gyro_drift_sample_count >= 0) {
imustate->gyro_drift_solution[0] = imustate->gyro_drift_accumulator[0] / (float)imustate->gyro_drift_sample_count;
imustate->gyro_drift_solution[1] = imustate->gyro_drift_accumulator[1] / (float)imustate->gyro_drift_sample_count;
imustate->gyro_drift_solution[2] = imustate->gyro_drift_accumulator[2] / (float)imustate->gyro_drift_sample_count;
}
imustate->is_calibrating_drift = false;
imustate->calibration_phase = GYRO_CALIBRATION_PHASE_COMPLETE;
ResetGyroOrientation(imustate);
}
/* Sample gyro packet in order to calculate drift*/
void SampleGyroPacketForDrift( IMUState *imustate )
void CalibrationPhase_DriftProfiling(IMUState *imustate)
{
if ( !imustate->is_calibrating_drift )
return;
/* Get the length squared difference of the last accelerometer data vs. the new one */
float accelerometer_difference[3];
accelerometer_difference[0] = imustate->accel_data[0] - imustate->last_accel_data[0];
accelerometer_difference[1] = imustate->accel_data[1] - imustate->last_accel_data[1];
accelerometer_difference[2] = imustate->accel_data[2] - imustate->last_accel_data[2];
SDL_memcpy(imustate->last_accel_data, imustate->accel_data, sizeof(imustate->last_accel_data));
imustate->accelerometer_length_squared = accelerometer_difference[0] * accelerometer_difference[0] + accelerometer_difference[1] * accelerometer_difference[1] + accelerometer_difference[2] * accelerometer_difference[2];
/* Ideal threshold will vary considerably depending on IMU. PS5 needs a low value (0.05f). Nintendo Switch needs a higher value (0.15f). */
const float flAccelerometerMovementThreshold = ACCELEROMETER_NOISE_THRESHOLD;
if (imustate->accelerometer_length_squared > flAccelerometerMovementThreshold * flAccelerometerMovementThreshold) {
if (imustate->accelerometer_length_squared > imustate->accelerometer_tolerance_squared) {
/* Reset the drift calibration if the accelerometer has moved significantly */
StartGyroDriftCalibration(imustate);
BeginDriftCalibrationPhase(imustate);
} else {
/* Sensor is stationary enough to evaluate for drift.*/
++imustate->gyro_drift_sample_count;
@@ -238,12 +275,33 @@ void SampleGyroPacketForDrift( IMUState *imustate )
imustate->gyro_drift_accumulator[1] += imustate->gyro_data[1];
imustate->gyro_drift_accumulator[2] += imustate->gyro_data[2];
if (imustate->gyro_drift_sample_count >= SDL_GAMEPAD_IMU_MIN_GYRO_DRIFT_SAMPLE_COUNT) {
/* Finish phase if we go over the time limit */
Uint64 now = SDL_GetTicksNS();
Uint64 delta_ns = now - imustate->calibration_phase_start_time_ticks_ns;
if (delta_ns >= SDL_GAMEPAD_IMU_CALIBRATION_PHASE_DURATION_NS) {
FinalizeDriftSolution(imustate);
}
}
}
/* Sample gyro packet in order to calculate drift*/
void SampleGyroPacketForDrift(IMUState *imustate)
{
/* Get the length squared difference of the last accelerometer data vs. the new one */
float accelerometer_difference[3];
accelerometer_difference[0] = imustate->accel_data[0] - imustate->last_accel_data[0];
accelerometer_difference[1] = imustate->accel_data[1] - imustate->last_accel_data[1];
accelerometer_difference[2] = imustate->accel_data[2] - imustate->last_accel_data[2];
SDL_memcpy(imustate->last_accel_data, imustate->accel_data, sizeof(imustate->last_accel_data));
imustate->accelerometer_length_squared = accelerometer_difference[0] * accelerometer_difference[0] + accelerometer_difference[1] * accelerometer_difference[1] + accelerometer_difference[2] * accelerometer_difference[2];
if (imustate->calibration_phase == GYRO_CALIBRATION_PHASE_NOISE_PROFILING)
CalibrationPhase_NoiseProfiling(imustate);
if (imustate->calibration_phase == GYRO_CALIBRATION_PHASE_DRIFT_PROFILING)
CalibrationPhase_DriftProfiling(imustate);
}
void ApplyDriftSolution(float *gyro_data, const float *drift_solution)
{
gyro_data[0] -= drift_solution[0];
@@ -1444,7 +1502,18 @@ static void HandleGamepadSensorEvent( SDL_Event* event )
float display_euler_angles[3];
QuaternionToYXZ(controller->imu_state->integrated_rotation, &display_euler_angles[0], &display_euler_angles[1], &display_euler_angles[2]);
float drift_calibration_progress_frac = controller->imu_state->gyro_drift_sample_count / (float)SDL_GAMEPAD_IMU_MIN_GYRO_DRIFT_SAMPLE_COUNT;
/* Show how far we are through the current phase. When off, just default to zero progress */
Uint64 now = SDL_GetTicksNS();
float duration = 0.0f;
if (controller->imu_state->calibration_phase == GYRO_CALIBRATION_PHASE_NOISE_PROFILING) {
duration = SDL_GAMEPAD_IMU_NOISE_PROFILING_PHASE_DURATION_NS;
} else if (controller->imu_state->calibration_phase == GYRO_CALIBRATION_PHASE_DRIFT_PROFILING) {
duration = SDL_GAMEPAD_IMU_CALIBRATION_PHASE_DURATION_NS;
}
Uint64 delta_ns = now - controller->imu_state->calibration_phase_start_time_ticks_ns;
float drift_calibration_progress_frac = duration > 0.0f ? ((float)delta_ns / (float)duration) : 0.0f;
int reported_polling_rate_hz = sensorTimeStampDelta_ns > 0 ? (int)(SDL_NS_PER_SECOND / sensorTimeStampDelta_ns) : 0;
/* Send the results to the frontend */
@@ -1454,8 +1523,11 @@ static void HandleGamepadSensorEvent( SDL_Event* event )
&controller->imu_state->integrated_rotation,
reported_polling_rate_hz,
controller->imu_state->imu_estimated_sensor_rate,
controller->imu_state->calibration_phase,
drift_calibration_progress_frac,
controller->imu_state->accelerometer_length_squared
controller->imu_state->accelerometer_length_squared,
controller->imu_state->accelerometer_tolerance_squared
);
/* Also show the gyro correction next to the gyro speed - this is useful in turntable tests as you can use a turntable to calibrate for drift, and that drift correction is functionally the same as the turn table speed (ignoring drift) */
@@ -2145,7 +2217,7 @@ SDL_AppResult SDLCALL SDL_AppEvent(void *appstate, SDL_Event *event)
if (GamepadButtonContains(GetGyroResetButton(gyro_elements), event->button.x, event->button.y)) {
ResetGyroOrientation(controller->imu_state);
} else if (GamepadButtonContains(GetGyroCalibrateButton(gyro_elements), event->button.x, event->button.y)) {
StartGyroDriftCalibration(controller->imu_state);
BeginNoiseCalibrationPhase(controller->imu_state);
} else if (GamepadButtonContains(setup_mapping_button, event->button.x, event->button.y)) {
SetDisplayMode(CONTROLLER_MODE_BINDING);
}