diff --git a/src/control/MadgwickAHRS.cpp b/src/control/MadgwickAHRS.cpp index bb8c451..c4ee1a1 100755 --- a/src/control/MadgwickAHRS.cpp +++ b/src/control/MadgwickAHRS.cpp @@ -1,47 +1,51 @@ -//===================================================================================================== +//============================================================================================= // MadgwickAHRS.c -//===================================================================================================== +//============================================================================================= // // Implementation of Madgwick's IMU and AHRS algorithms. -// See: http://www.x-io.co.uk/node/8#open_source_ahrs_and_imu_algorithms +// See: http://www.x-io.co.uk/open-source-imu-and-ahrs-algorithms/ +// +// From the x-io website "Open-source resources available on this website are +// provided under the GNU General Public Licence unless an alternative licence +// is provided in source." // // Date Author Notes // 29/09/2011 SOH Madgwick Initial release // 02/10/2011 SOH Madgwick Optimised for reduced CPU load // 19/02/2012 SOH Madgwick Magnetometer measurement is normalised // -//===================================================================================================== +//============================================================================================= -//--------------------------------------------------------------------------------------------------- +//------------------------------------------------------------------------------------------- // Header files #include "MadgwickAHRS.h" #include -//--------------------------------------------------------------------------------------------------- +//------------------------------------------------------------------------------------------- // Definitions -#define sampleFreq 512.0f // sample frequency in Hz -#define betaDef 0.1f // 2 * proportional gain +#define sampleFreqDef 512.0f // sample frequency in Hz +#define betaDef 0.1f // 2 * proportional gain -//--------------------------------------------------------------------------------------------------- -// Variable definitions -volatile float beta = betaDef; // 2 * proportional gain (Kp) -volatile float q0 = 1.0f, q1 = 0.0f, q2 = 0.0f, q3 = 0.0f; // quaternion of sensor frame relative to auxiliary frame - -//--------------------------------------------------------------------------------------------------- -// Function declarations - -float invSqrt(float x); - -//==================================================================================================== +//============================================================================================ // Functions -//--------------------------------------------------------------------------------------------------- +//------------------------------------------------------------------------------------------- // AHRS algorithm update -void MadgwickAHRSupdate(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz) { +Madgwick::Madgwick() { + beta = betaDef; + q0 = 1.0f; + q1 = 0.0f; + q2 = 0.0f; + q3 = 0.0f; + invSampleFreq = 1.0f / sampleFreqDef; + anglesComputed = 0; +} + +void Madgwick::update(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz) { float recipNorm; float s0, s1, s2, s3; float qDot1, qDot2, qDot3, qDot4; @@ -50,10 +54,15 @@ void MadgwickAHRSupdate(float gx, float gy, float gz, float ax, float ay, float // Use IMU algorithm if magnetometer measurement invalid (avoids NaN in magnetometer normalisation) if((mx == 0.0f) && (my == 0.0f) && (mz == 0.0f)) { - MadgwickAHRSupdateIMU(gx, gy, gz, ax, ay, az); + updateIMU(gx, gy, gz, ax, ay, az); return; } + // Convert gyroscope degrees/sec to radians/sec + gx *= 0.0174533f; + gy *= 0.0174533f; + gz *= 0.0174533f; + // Rate of change of quaternion from gyroscope qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz); qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy); @@ -67,7 +76,7 @@ void MadgwickAHRSupdate(float gx, float gy, float gz, float ax, float ay, float recipNorm = invSqrt(ax * ax + ay * ay + az * az); ax *= recipNorm; ay *= recipNorm; - az *= recipNorm; + az *= recipNorm; // Normalise magnetometer measurement recipNorm = invSqrt(mx * mx + my * my + mz * mz); @@ -100,7 +109,7 @@ void MadgwickAHRSupdate(float gx, float gy, float gz, float ax, float ay, float // Reference direction of Earth's magnetic field hx = mx * q0q0 - _2q0my * q3 + _2q0mz * q2 + mx * q1q1 + _2q1 * my * q2 + _2q1 * mz * q3 - mx * q2q2 - mx * q3q3; hy = _2q0mx * q3 + my * q0q0 - _2q0mz * q1 + _2q1mx * q2 - my * q1q1 + my * q2q2 + _2q2 * mz * q3 - my * q3q3; - _2bx = sqrt(hx * hx + hy * hy); + _2bx = sqrtf(hx * hx + hy * hy); _2bz = -_2q0mx * q2 + _2q0my * q1 + mz * q0q0 + _2q1mx * q3 - mz * q1q1 + _2q2 * my * q3 - mz * q2q2 + mz * q3q3; _4bx = 2.0f * _2bx; _4bz = 2.0f * _2bz; @@ -124,10 +133,10 @@ void MadgwickAHRSupdate(float gx, float gy, float gz, float ax, float ay, float } // Integrate rate of change of quaternion to yield quaternion - q0 += qDot1 * (1.0f / sampleFreq); - q1 += qDot2 * (1.0f / sampleFreq); - q2 += qDot3 * (1.0f / sampleFreq); - q3 += qDot4 * (1.0f / sampleFreq); + q0 += qDot1 * invSampleFreq; + q1 += qDot2 * invSampleFreq; + q2 += qDot3 * invSampleFreq; + q3 += qDot4 * invSampleFreq; // Normalise quaternion recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3); @@ -135,17 +144,23 @@ void MadgwickAHRSupdate(float gx, float gy, float gz, float ax, float ay, float q1 *= recipNorm; q2 *= recipNorm; q3 *= recipNorm; + anglesComputed = 0; } -//--------------------------------------------------------------------------------------------------- +//------------------------------------------------------------------------------------------- // IMU algorithm update -void MadgwickAHRSupdateIMU(float gx, float gy, float gz, float ax, float ay, float az) { +void Madgwick::updateIMU(float gx, float gy, float gz, float ax, float ay, float az) { float recipNorm; float s0, s1, s2, s3; float qDot1, qDot2, qDot3, qDot4; float _2q0, _2q1, _2q2, _2q3, _4q0, _4q1, _4q2 ,_8q1, _8q2, q0q0, q1q1, q2q2, q3q3; + // Convert gyroscope degrees/sec to radians/sec + gx *= 0.0174533f; + gy *= 0.0174533f; + gz *= 0.0174533f; + // Rate of change of quaternion from gyroscope qDot1 = 0.5f * (-q1 * gx - q2 * gy - q3 * gz); qDot2 = 0.5f * (q0 * gx + q2 * gz - q3 * gy); @@ -159,7 +174,7 @@ void MadgwickAHRSupdateIMU(float gx, float gy, float gz, float ax, float ay, flo recipNorm = invSqrt(ax * ax + ay * ay + az * az); ax *= recipNorm; ay *= recipNorm; - az *= recipNorm; + az *= recipNorm; // Auxiliary variables to avoid repeated arithmetic _2q0 = 2.0f * q0; @@ -195,10 +210,10 @@ void MadgwickAHRSupdateIMU(float gx, float gy, float gz, float ax, float ay, flo } // Integrate rate of change of quaternion to yield quaternion - q0 += qDot1 * (1.0f / sampleFreq); - q1 += qDot2 * (1.0f / sampleFreq); - q2 += qDot3 * (1.0f / sampleFreq); - q3 += qDot4 * (1.0f / sampleFreq); + q0 += qDot1 * invSampleFreq; + q1 += qDot2 * invSampleFreq; + q2 += qDot3 * invSampleFreq; + q3 += qDot4 * invSampleFreq; // Normalise quaternion recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3); @@ -206,27 +221,30 @@ void MadgwickAHRSupdateIMU(float gx, float gy, float gz, float ax, float ay, flo q1 *= recipNorm; q2 *= recipNorm; q3 *= recipNorm; + anglesComputed = 0; } -//--------------------------------------------------------------------------------------------------- +//------------------------------------------------------------------------------------------- // Fast inverse square-root // See: http://en.wikipedia.org/wiki/Fast_inverse_square_root -float invSqrt(float x) { +float Madgwick::invSqrt(float x) { float halfx = 0.5f * x; float y = x; long i = *(long*)&y; i = 0x5f3759df - (i>>1); y = *(float*)&i; y = y * (1.5f - (halfx * y * y)); + y = y * (1.5f - (halfx * y * y)); return y; } -float getPitch() -{ - return asinf(-2.0f * (q1*q3 - q0*q2)); -} +//------------------------------------------------------------------------------------------- -//==================================================================================================== -// END OF CODE -//==================================================================================================== +void Madgwick::computeAngles() +{ + roll = atan2f(q0*q1 + q2*q3, 0.5f - q1*q1 - q2*q2); + pitch = asinf(-2.0f * (q1*q3 - q0*q2)); + yaw = atan2f(q1*q2 + q0*q3, 0.5f - q2*q2 - q3*q3); + anglesComputed = 1; +} \ No newline at end of file diff --git a/src/control/MadgwickAHRS.h b/src/control/MadgwickAHRS.h index 405b971..713c395 100755 --- a/src/control/MadgwickAHRS.h +++ b/src/control/MadgwickAHRS.h @@ -1,32 +1,71 @@ -//===================================================================================================== +//============================================================================================= // MadgwickAHRS.h -//===================================================================================================== +//============================================================================================= // // Implementation of Madgwick's IMU and AHRS algorithms. -// See: http://www.x-io.co.uk/node/8#open_source_ahrs_and_imu_algorithms +// See: http://www.x-io.co.uk/open-source-imu-and-ahrs-algorithms/ +// +// From the x-io website "Open-source resources available on this website are +// provided under the GNU General Public Licence unless an alternative licence +// is provided in source." // // Date Author Notes // 29/09/2011 SOH Madgwick Initial release // 02/10/2011 SOH Madgwick Optimised for reduced CPU load // -//===================================================================================================== +//============================================================================================= #ifndef MadgwickAHRS_h #define MadgwickAHRS_h +#include -//---------------------------------------------------------------------------------------------------- +//-------------------------------------------------------------------------------------------- // Variable declaration +class Madgwick{ +private: + static float invSqrt(float x); + float beta; // algorithm gain + float q0; + float q1; + float q2; + float q3; // quaternion of sensor frame relative to auxiliary frame + float invSampleFreq; + float roll; + float pitch; + float yaw; + char anglesComputed; + void computeAngles(); -extern volatile float beta; // algorithm gain -extern volatile float q0, q1, q2, q3; // quaternion of sensor frame relative to auxiliary frame - -//--------------------------------------------------------------------------------------------------- +//------------------------------------------------------------------------------------------- // Function declarations - -void MadgwickAHRSupdate(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz); -void MadgwickAHRSupdateIMU(float gx, float gy, float gz, float ax, float ay, float az); - -float getPitch(); -#endif -//===================================================================================================== -// End of file -//===================================================================================================== +public: + Madgwick(void); + void begin(float sampleFrequency) { invSampleFreq = 1.0f / sampleFrequency; } + void update(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz); + void updateIMU(float gx, float gy, float gz, float ax, float ay, float az); + + float getRoll() { + if (!anglesComputed) computeAngles(); + return roll * 57.29578f; + } + float getPitch() { + if (!anglesComputed) computeAngles(); + return pitch * 57.29578f; + } + float getYaw() { + if (!anglesComputed) computeAngles(); + return yaw * 57.29578f + 180.0f; + } + float getRollRadians() { + if (!anglesComputed) computeAngles(); + return roll; + } + float getPitchRadians() { + if (!anglesComputed) computeAngles(); + return pitch; + } + float getYawRadians() { + if (!anglesComputed) computeAngles(); + return yaw; + } +}; +#endif \ No newline at end of file