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單片機(jī)源程序如下:
- #define sampleFreq 512.0f
- #define twoKpDef (2.0f*0.5f)
- #define twoKiDef (2.0f*0.5f)
- volatile float twoKp=twoKpDef;
- volatile float twoKi=twoKiDef;
- volatile float q0=1.0f,q1=1.0f,q2=1.0f,q3=1.0f;
- volatile float integralFBx=0.0f,integralFBy=0.0f,integralFBz=0.0f;
- //---------------------------------------------------------------------------------------------------
- // Fast inverse square-root
- // See: http://en.wikipedia.org/wiki/Fast_inverse_square_root
- 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;
- }
- //---------------------------------------------------------------------------------------------------
- // IMU algorithm update
- void MahonyAHRSupdateIMU(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 * (1.0f / sampleFreq);// integral error scaled by Ki
- integralFBy += twoKi * halfey * (1.0f / sampleFreq);
- integralFBz += twoKi * halfez * (1.0f / sampleFreq);
- 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 * (1.0f / sampleFreq));// pre-multiply common factors
- gy *= (0.5f * (1.0f / sampleFreq));
- gz *= (0.5f * (1.0f / sampleFreq));
- 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;
- }
- //---------------------------------------------------------------------------------------------------
- //
- typedef struct{
- float roll;
- float pitch;
- float yaw;}T_float_angle;
- T_float_angle Att_Angle; //×Ë쬽Ç
- /*gx,gy,gzíóÂYòÇ¡ax,ay,az¼óËù¶è¡￠￠*/
- void MahonyAHRSupdate(float gx, float gy, float gz, float ax, float ay, float az, float mx, float my, float mz,T_float_angle *angle ) {
- 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;
- // Use IMU algorithm if magnetometer measurement invalid (avoids NaN in magnetometer normalisation)
- if((mx == 0.0f) && (my == 0.0f) && (mz == 0.0f)) {
- MahonyAHRSupdateIMU(gx, gy, gz, ax, ay, az);
- return;
- }
- // 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;
- // Normalise magnetometer measurement
- recipNorm = 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 = sqrt(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) {
- integralFBx += twoKi * halfex * (1.0f / sampleFreq); // integral error scaled by Ki
- integralFBy += twoKi * halfey * (1.0f / sampleFreq);
- integralFBz += twoKi * halfez * (1.0f / sampleFreq);
- 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 * (1.0f / sampleFreq)); // pre-multiply common factors
- gy *= (0.5f * (1.0f / sampleFreq));
- gz *= (0.5f * (1.0f / sampleFreq));
- 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;
- }
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