shoes/liangjianbo/nRF5_SDK_17.0.0_9d13099/components/drivers_ext/AHRS/MahonyAHRS.c

//=============================================================================================
// MahonyAHRS.c
//=============================================================================================
//
// Madgwick's implementation of Mayhony's AHRS algorithm.
// 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
//
// Algorithm paper:
// http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=4608934&url=http%3A%2F%2Fieeexplore.ieee.org%2Fstamp%2Fstamp.jsp%3Ftp%3D%26arnumber%3D4608934
//
//=============================================================================================

//-------------------------------------------------------------------------------------------
// Header files

#include "MahonyAHRS.h"
#include <math.h>

//-------------------------------------------------------------------------------------------
// Definitions

#define sampleFreq 100
#define twoKpDef	(10.0f * 0.5f)	// 2 * proportional gain
#define twoKiDef	(2.0f * 0.0f)	// 2 * integral gain

float twoKi = twoKiDef;		// 2 * integral gain (Ki)
float twoKp = twoKpDef;		// 2 * integral gain (Ki)
float invSampleFreq = 1.0f/sampleFreq; 
float q0=1.0f, q1=0.0f, q2=0.0f, q3=0.0f;	// quaternion of sensor frame relative to auxiliary frame
float integralFBx=0, integralFBy=0, integralFBz=0;  // integral error terms scaled by Ki

float roll, pitch, yaw;
char anglesComputed;

float Mahony_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 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));
 return y;
}

#define samplePeriod 0.01f
//float twoKp=(5.0f * 0.5f);
//float twoKi=(2.0f * 0.5f);
//float integralFBx = 0.0f,  integralFBy = 0.0f, integralFBz = 0.0f; // integral error terms scaled by Ki


//¹²éîËÄÔªÊý
void quatconj(const float *Quat,float *out)
{
	out[0]= Quat[0];
	out[1]=-Quat[1];
	out[2]=-Quat[2];
	out[3]=-Quat[3];
}

float quatdianc(const float* Q,const float* P)
{
	float result;
	result=P[0]*Q[0] + P[1]*Q[1] + P[2]*Q[2] + P[3]*Q[3];
	return result;
}

void quatmultiply(const float * Q,const float * P,float *QP)
{
	QP[0]=P[0]*Q[0] - P[1]*Q[1] - P[2]*Q[2] - P[3]*Q[3];
	QP[1]=P[0]*Q[1] + P[1]*Q[0] + P[2]*Q[3] - P[3]*Q[2]; 
	QP[2]=P[0]*Q[2] + P[2]*Q[0] + P[3]*Q[1] - P[1]*Q[3];
	QP[3]=P[0]*Q[3] + P[3]*Q[0] + P[1]*Q[2] - P[2]*Q[1];	
}

void quatinv(float* Q,float *quatinvQ)
{	
	float mod;
	float temp[4];
	quatconj(Q,temp);
	mod=quatdianc(temp,temp);	
	quatinvQ[0]=temp[0]/mod;
	quatinvQ[1]=temp[1]/mod;
	quatinvQ[2]=temp[2]/mod;
	quatinvQ[3]=temp[3]/mod;
}

void quatrotate(float* sour_pion,float* Q,float *out_poin)
{
	float Quaternion_p[4];
	float temp[4];
	float temp1[4];
	float temp2[4];
	Quaternion_p[0]=0;
	Quaternion_p[1]=sour_pion[0];
	Quaternion_p[2]=sour_pion[1];
	Quaternion_p[3]=sour_pion[2];
	quatmultiply(Q,Quaternion_p,temp); 
	quatinv(Q,temp2);
	quatmultiply(temp,temp2,temp1);
	out_poin[0]=temp1[1];
	out_poin[1]=temp1[2];
	out_poin[2]=temp1[3];
} 

void accel_BConvertToN(float accel_s[3], float accel_d[3], float q[4])
{
	float temp[4];
	quatconj(q,temp);
	quatrotate(accel_s,temp,accel_d);
//	accel_d[2] -= 1;
}

void updateIMU(float gx, float gy, float gz, float ax, float ay, float az) 
{
	float recipNorm;
	float halfvx, halfvy, halfvz;
	float halfex, halfey, halfez;
	float qa, qb, qc;


	// Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
	if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) 
	{

	// Normalise accelerometer measurement
	recipNorm = invSqrt(ax * ax + ay * ay + az * az);
	ax *= recipNorm;
	ay *= recipNorm;
	az *= recipNorm;        

	// Estimated direction of gravity and vector perpendicular to magnetic flux
	halfvx = q1 * q3 - q0 * q2;
	halfvy = q0 * q1 + q2 * q3;
	halfvz = q0 * q0 - 0.5f + q3 * q3;

	// Error is sum of cross product between estimated and measured direction of gravity
	halfex = (ay * halfvz - az * halfvy);
	halfey = (az * halfvx - ax * halfvz);
	halfez = (ax * halfvy - ay * halfvx);

	// Compute and apply integral feedback if enabled
	if(twoKi > 0.0f) 
	{
	integralFBx += twoKi * halfex * samplePeriod; // integral error scaled by Ki
	integralFBy += twoKi * halfey * samplePeriod;
	integralFBz += twoKi * halfez * samplePeriod;
	gx += integralFBx; // apply integral feedback
	gy += integralFBy;
	gz += integralFBz;
	}
	else 
	{
	integralFBx = 0.0f; // prevent integral windup
	integralFBy = 0.0f;
	integralFBz = 0.0f;
	}
	
// Apply proportional feedback
	gx += twoKp * halfex;
	gy += twoKp * halfey;
	gz += twoKp * halfez;
	}

	// Integrate rate of change of quaternion
	gx *= (0.5f * samplePeriod);  // pre-multiply common factors
	gy *= (0.5f * samplePeriod);
	gz *= (0.5f * samplePeriod);
	qa = q0;
	qb = q1;
	qc = q2;
	q0 += (-qb * gx - qc * gy - q3 * gz);
	q1 += (qa * gx + qc * gz - q3 * gy);
	q2 += (qa * gy - qb * gz + q3 * gx);
	q3 += (qa * gz + qb * gy - qc * gx); 

	// Normalise quaternion
	recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
	q0 *= recipNorm;
	q1 *= recipNorm;
	q2 *= recipNorm;
	q3 *= recipNorm;
}


void Mahony_update(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz)
{
	float recipNorm;
	float q0q0, q0q1, q0q2, q0q3, q1q1, q1q2, q1q3, q2q2, q2q3, q3q3;
	float hx, hy, bx, bz;
	float halfvx, halfvy, halfvz, halfwx, halfwy, halfwz;
	float halfex, halfey, halfez;
	float qa, qb, qc;
	// Convert gyroscope degrees/sec to radians/sec
//	gx *= 0.0174533f;
//	gy *= 0.0174533f;
//	gz *= 0.0174533f;

	// Compute feedback only if accelerometer measurement valid
	// (avoids NaN in accelerometer normalisation)
	if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {

		// Normalise accelerometer measurement
		recipNorm = Mahony_invSqrt(ax * ax + ay * ay + az * az);
		ax *= recipNorm;
		ay *= recipNorm;
		az *= recipNorm;

		// Normalise magnetometer measurement
		recipNorm = Mahony_invSqrt(mx * mx + my * my + mz * mz);
		mx *= recipNorm;
		my *= recipNorm;
		mz *= recipNorm;

		// Auxiliary variables to avoid repeated arithmetic
		q0q0 = q0 * q0;
		q0q1 = q0 * q1;
		q0q2 = q0 * q2;
		q0q3 = q0 * q3;
		q1q1 = q1 * q1;
		q1q2 = q1 * q2;
		q1q3 = q1 * q3;
		q2q2 = q2 * q2;
		q2q3 = q2 * q3;
		q3q3 = q3 * q3;

		// Reference direction of Earth's magnetic field
		hx = 2.0f * (mx * (0.5f - q2q2 - q3q3) + my * (q1q2 - q0q3) + mz * (q1q3 + q0q2));
		hy = 2.0f * (mx * (q1q2 + q0q3) + my * (0.5f - q1q1 - q3q3) + mz * (q2q3 - q0q1));
		bx = sqrtf(hx * hx + hy * hy);
		bz = 2.0f * (mx * (q1q3 - q0q2) + my * (q2q3 + q0q1) + mz * (0.5f - q1q1 - q2q2));

		// Estimated direction of gravity and magnetic field
		halfvx = q1q3 - q0q2;
		halfvy = q0q1 + q2q3;
		halfvz = q0q0 - 0.5f + q3q3;
		halfwx = bx * (0.5f - q2q2 - q3q3) + bz * (q1q3 - q0q2);
		halfwy = bx * (q1q2 - q0q3) + bz * (q0q1 + q2q3);
		halfwz = bx * (q0q2 + q1q3) + bz * (0.5f - q1q1 - q2q2);

		// Error is sum of cross product between estimated direction
		// and measured direction of field vectors
		halfex = (ay * halfvz - az * halfvy) + (my * halfwz - mz * halfwy);
		halfey = (az * halfvx - ax * halfvz) + (mz * halfwx - mx * halfwz);
		halfez = (ax * halfvy - ay * halfvx) + (mx * halfwy - my * halfwx);

		// Compute and apply integral feedback if enabled
		if(twoKi > 0.0f) {
			// integral error scaled by Ki
			integralFBx += twoKi * halfex * invSampleFreq;
			integralFBy += twoKi * halfey * invSampleFreq;
			integralFBz += twoKi * halfez * invSampleFreq;
			gx += integralFBx;	// apply integral feedback
			gy += integralFBy;
			gz += integralFBz;
		} else {
			integralFBx = 0.0f;	// prevent integral windup
			integralFBy = 0.0f;
			integralFBz = 0.0f;
		}

		// Apply proportional feedback
		gx += twoKpDef * halfex;
		gy += twoKpDef * halfey;
		gz += twoKpDef * halfez;
	}

	// Integrate rate of change of quaternion
	gx *= (0.5f * invSampleFreq);		// pre-multiply common factors
	gy *= (0.5f * invSampleFreq);
	gz *= (0.5f * invSampleFreq);
	qa = q0;
	qb = q1;
	qc = q2;
	q0 += (-qb * gx - qc * gy - q3 * gz);
	q1 += (qa * gx + qc * gz - q3 * gy);
	q2 += (qa * gy - qb * gz + q3 * gx);
	q3 += (qa * gz + qb * gy - qc * gx);

	// Normalise quaternion
	recipNorm = Mahony_invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
	q0 *= recipNorm;
	q1 *= recipNorm;
	q2 *= recipNorm;
	q3 *= recipNorm;
	anglesComputed = 0;
}

float roll, pitch, yaw;
char anglesComputed;
void Mahony_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;
}
float getRoll() {
	if (!anglesComputed) Mahony_computeAngles();
	return roll * 57.29578f;
}
float getPitch() {
	if (!anglesComputed) Mahony_computeAngles();
	return pitch * 57.29578f;
}
float getYaw() {
	if (!anglesComputed) Mahony_computeAngles();
	return yaw * 57.29578f + 180.0f;
}
//============================================================================================
// END OF CODE
//============================================================================================