Gurvan PRIEM / Mbed 2 deprecated RaptorControl

An incomplete quadcopter control programme.

Dependencies:   mbed

MPU6050/GurvIMU.cpp@0:9cb9445a11f0, 2013-07-17 (annotated)

Committer:
Gurvan
Date:
Wed Jul 17 15:58:25 2013 +0000
Revision:
0:9cb9445a11f0
Pour Zobson, fi(r)st commit.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Gurvan 0:9cb9445a11f0 1 #include "GurvIMU.h"
Gurvan 0:9cb9445a11f0 2 #include "MPU6050.h"
Gurvan 0:9cb9445a11f0 3 #include "mbed.h"
Gurvan 0:9cb9445a11f0 4
Gurvan 0:9cb9445a11f0 5 #define M_PI 3.1415926535897932384626433832795
Gurvan 0:9cb9445a11f0 6
Gurvan 0:9cb9445a11f0 7 #define twoKpDef (2.0f * 1.0f) // 2 * proportional gain
Gurvan 0:9cb9445a11f0 8 #define twoKiDef (2.0f * 0.0f) // 2 * integral gain
Gurvan 0:9cb9445a11f0 9
Gurvan 0:9cb9445a11f0 10
Gurvan 0:9cb9445a11f0 11 GurvIMU::GurvIMU()
Gurvan 0:9cb9445a11f0 12 {
Gurvan 0:9cb9445a11f0 13 //MPU
Gurvan 0:9cb9445a11f0 14 mpu = MPU6050(0x69); //0x69 = MPU6050 I2C ADDRESS
Gurvan 0:9cb9445a11f0 15
Gurvan 0:9cb9445a11f0 16 // Variable definitions
Gurvan 0:9cb9445a11f0 17 q0 = 1.0f, q1 = 0.0f, q2 = 0.0f, q3 = 0.0f; // quaternion of sensor frame relative to auxiliary frame
Gurvan 0:9cb9445a11f0 18 twoKp = twoKpDef; // 2 * proportional gain (Kp)
Gurvan 0:9cb9445a11f0 19 twoKi = twoKiDef; // 2 * integral gain (Ki)
Gurvan 0:9cb9445a11f0 20 integralFBx = 0.0f, integralFBy = 0.0f, integralFBz = 0.0f; // integral error terms scaled by Ki
Gurvan 0:9cb9445a11f0 21 cycle_nb = 0;
Gurvan 0:9cb9445a11f0 22 timer_us.start();
Gurvan 0:9cb9445a11f0 23 }
Gurvan 0:9cb9445a11f0 24
Gurvan 0:9cb9445a11f0 25 //Function definitions
Gurvan 0:9cb9445a11f0 26
Gurvan 0:9cb9445a11f0 27 void GurvIMU::getValues(float * values)
Gurvan 0:9cb9445a11f0 28 {
Gurvan 0:9cb9445a11f0 29 int16_t accgyroval[6];
Gurvan 0:9cb9445a11f0 30 mpu.getMotion6(&accgyroval[0], &accgyroval[1], &accgyroval[2], &accgyroval[3], &accgyroval[4], &accgyroval[5]);
Gurvan 0:9cb9445a11f0 31 for(int i = 0; i<3; i++) values[i] = (float) accgyroval[i];
Gurvan 0:9cb9445a11f0 32 for(int i = 3; i<6; i++) values[i] = (accgyroval[i]-offset[i]) * (M_PI / 180) / 16.4f;
Gurvan 0:9cb9445a11f0 33 }
Gurvan 0:9cb9445a11f0 34
Gurvan 0:9cb9445a11f0 35 void GurvIMU::getVerticalAcceleration(float av)
Gurvan 0:9cb9445a11f0 36 {
Gurvan 0:9cb9445a11f0 37 float values[6];
Gurvan 0:9cb9445a11f0 38 float q[4]; // quaternion
Gurvan 0:9cb9445a11f0 39 float g_x, g_y, g_z; // estimated gravity direction
Gurvan 0:9cb9445a11f0 40 getQ(q);
Gurvan 0:9cb9445a11f0 41
Gurvan 0:9cb9445a11f0 42 g_x = 2 * (q[1]*q[3] - q[0]*q[2]);
Gurvan 0:9cb9445a11f0 43 g_y = 2 * (q[0]*q[1] + q[2]*q[3]);
Gurvan 0:9cb9445a11f0 44 g_z = q[0]*q[0] - q[1]*q[1] - q[2]*q[2] + q[3]*q[3];
Gurvan 0:9cb9445a11f0 45
Gurvan 0:9cb9445a11f0 46 getValues(values);
Gurvan 0:9cb9445a11f0 47 av = g_x*values[0]+g_y*values[1]+g_z*values[2]-offset[2];
Gurvan 0:9cb9445a11f0 48 }
Gurvan 0:9cb9445a11f0 49
Gurvan 0:9cb9445a11f0 50
Gurvan 0:9cb9445a11f0 51 void GurvIMU::getOffset(void)
Gurvan 0:9cb9445a11f0 52 {
Gurvan 0:9cb9445a11f0 53 int sample_nb = 50;
Gurvan 0:9cb9445a11f0 54 float values[6];
Gurvan 0:9cb9445a11f0 55 for(int i=0; i<6 ; i++) offset[i] = 0;
Gurvan 0:9cb9445a11f0 56 for(int i=0; i<sample_nb; i++) {
Gurvan 0:9cb9445a11f0 57 getValues(values);
Gurvan 0:9cb9445a11f0 58 for(int j=0; j<6; j++) offset[j]+=values[j];
Gurvan 0:9cb9445a11f0 59 }
Gurvan 0:9cb9445a11f0 60 for(int j=0; j<6; j++) offset[j]/=sample_nb;
Gurvan 0:9cb9445a11f0 61 }
Gurvan 0:9cb9445a11f0 62
Gurvan 0:9cb9445a11f0 63
Gurvan 0:9cb9445a11f0 64 void GurvIMU::AHRS_update(float gx, float gy, float gz, float ax, float ay, float az)
Gurvan 0:9cb9445a11f0 65 {
Gurvan 0:9cb9445a11f0 66 float recipNorm;
Gurvan 0:9cb9445a11f0 67 float halfvx, halfvy, halfvz;
Gurvan 0:9cb9445a11f0 68 float halfex, halfey, halfez;
Gurvan 0:9cb9445a11f0 69 float qa, qb, qc;
Gurvan 0:9cb9445a11f0 70
Gurvan 0:9cb9445a11f0 71 dt_us=timer_us.read_us();
Gurvan 0:9cb9445a11f0 72 sample_freq = 1.0 / ((dt_us) / 1000000.0);
Gurvan 0:9cb9445a11f0 73 timer_us.reset();
Gurvan 0:9cb9445a11f0 74
Gurvan 0:9cb9445a11f0 75 // Compute feedback only if accelerometer measurement valid (avoids NaN in accelerometer normalisation)
Gurvan 0:9cb9445a11f0 76 if(!((ax == 0.0f) && (ay == 0.0f) && (az == 0.0f))) {
Gurvan 0:9cb9445a11f0 77
Gurvan 0:9cb9445a11f0 78 // Normalise accelerometer measurement
Gurvan 0:9cb9445a11f0 79 recipNorm = invSqrt(ax * ax + ay * ay + az * az);
Gurvan 0:9cb9445a11f0 80 ax *= recipNorm;
Gurvan 0:9cb9445a11f0 81 ay *= recipNorm;
Gurvan 0:9cb9445a11f0 82 az *= recipNorm;
Gurvan 0:9cb9445a11f0 83
Gurvan 0:9cb9445a11f0 84 // Estimated direction of gravity
Gurvan 0:9cb9445a11f0 85 halfvx = q1 * q3 - q0 * q2;
Gurvan 0:9cb9445a11f0 86 halfvy = q0 * q1 + q2 * q3;
Gurvan 0:9cb9445a11f0 87 halfvz = q0 * q0 - 0.5f + q3 * q3;
Gurvan 0:9cb9445a11f0 88
Gurvan 0:9cb9445a11f0 89 // Error is sum of cross product between estimated and measured direction of gravity
Gurvan 0:9cb9445a11f0 90 halfex = (ay * halfvz - az * halfvy);
Gurvan 0:9cb9445a11f0 91 halfey = (az * halfvx - ax * halfvz);
Gurvan 0:9cb9445a11f0 92 halfez = (ax * halfvy - ay * halfvx);
Gurvan 0:9cb9445a11f0 93
Gurvan 0:9cb9445a11f0 94 // Compute and apply integral feedback if enabled
Gurvan 0:9cb9445a11f0 95 if(twoKi > 0.0f) {
Gurvan 0:9cb9445a11f0 96 integralFBx += twoKi * halfex * (1.0f / sample_freq); // integral error scaled by Ki
Gurvan 0:9cb9445a11f0 97 integralFBy += twoKi * halfey * (1.0f / sample_freq);
Gurvan 0:9cb9445a11f0 98 integralFBz += twoKi * halfez * (1.0f / sample_freq);
Gurvan 0:9cb9445a11f0 99 gx += integralFBx; // apply integral feedback
Gurvan 0:9cb9445a11f0 100 gy += integralFBy;
Gurvan 0:9cb9445a11f0 101 gz += integralFBz;
Gurvan 0:9cb9445a11f0 102 }
Gurvan 0:9cb9445a11f0 103 else {
Gurvan 0:9cb9445a11f0 104 integralFBx = 0.0f; // prevent integral windup
Gurvan 0:9cb9445a11f0 105 integralFBy = 0.0f;
Gurvan 0:9cb9445a11f0 106 integralFBz = 0.0f;
Gurvan 0:9cb9445a11f0 107 }
Gurvan 0:9cb9445a11f0 108
Gurvan 0:9cb9445a11f0 109 // Apply proportional feedback
Gurvan 0:9cb9445a11f0 110 gx += twoKp * halfex;
Gurvan 0:9cb9445a11f0 111 gy += twoKp * halfey;
Gurvan 0:9cb9445a11f0 112 gz += twoKp * halfez;
Gurvan 0:9cb9445a11f0 113 }
Gurvan 0:9cb9445a11f0 114
Gurvan 0:9cb9445a11f0 115 // Integrate rate of change of quaternion
Gurvan 0:9cb9445a11f0 116 gx *= (0.5f * (1.0f / sample_freq)); // pre-multiply common factors
Gurvan 0:9cb9445a11f0 117 gy *= (0.5f * (1.0f / sample_freq));
Gurvan 0:9cb9445a11f0 118 gz *= (0.5f * (1.0f / sample_freq));
Gurvan 0:9cb9445a11f0 119 qa = q0;
Gurvan 0:9cb9445a11f0 120 qb = q1;
Gurvan 0:9cb9445a11f0 121 qc = q2;
Gurvan 0:9cb9445a11f0 122 q0 += (-qb * gx - qc * gy - q3 * gz);
Gurvan 0:9cb9445a11f0 123 q1 += (qa * gx + qc * gz - q3 * gy);
Gurvan 0:9cb9445a11f0 124 q2 += (qa * gy - qb * gz + q3 * gx);
Gurvan 0:9cb9445a11f0 125 q3 += (qa * gz + qb * gy - qc * gx);
Gurvan 0:9cb9445a11f0 126
Gurvan 0:9cb9445a11f0 127 // Normalise quaternion
Gurvan 0:9cb9445a11f0 128 recipNorm = invSqrt(q0 * q0 + q1 * q1 + q2 * q2 + q3 * q3);
Gurvan 0:9cb9445a11f0 129 q0 *= recipNorm;
Gurvan 0:9cb9445a11f0 130 q1 *= recipNorm;
Gurvan 0:9cb9445a11f0 131 q2 *= recipNorm;
Gurvan 0:9cb9445a11f0 132 q3 *= recipNorm;
Gurvan 0:9cb9445a11f0 133 }
Gurvan 0:9cb9445a11f0 134
Gurvan 0:9cb9445a11f0 135 void GurvIMU::getQ(float * q) {
Gurvan 0:9cb9445a11f0 136 float val[6];
Gurvan 0:9cb9445a11f0 137 getValues(val);
Gurvan 0:9cb9445a11f0 138 //while(cycle_nb < 1000){
Gurvan 0:9cb9445a11f0 139 AHRS_update(val[3], val[4], val[5], val[0], val[1], val[2]);
Gurvan 0:9cb9445a11f0 140 //cycle_nb++;}
Gurvan 0:9cb9445a11f0 141
Gurvan 0:9cb9445a11f0 142 q[0] = q0;
Gurvan 0:9cb9445a11f0 143 q[1] = q1;
Gurvan 0:9cb9445a11f0 144 q[2] = q2;
Gurvan 0:9cb9445a11f0 145 q[3] = q3;
Gurvan 0:9cb9445a11f0 146
Gurvan 0:9cb9445a11f0 147 }
Gurvan 0:9cb9445a11f0 148
Gurvan 0:9cb9445a11f0 149 void GurvIMU::getYawPitchRollRad(float * ypr) {
Gurvan 0:9cb9445a11f0 150 float q[4]; // quaternion
Gurvan 0:9cb9445a11f0 151 float g_x, g_y, g_z; // estimated gravity direction
Gurvan 0:9cb9445a11f0 152 getQ(q);
Gurvan 0:9cb9445a11f0 153
Gurvan 0:9cb9445a11f0 154 g_x = 2 * (q[1]*q[3] - q[0]*q[2]);
Gurvan 0:9cb9445a11f0 155 g_y = 2 * (q[0]*q[1] + q[2]*q[3]);
Gurvan 0:9cb9445a11f0 156 g_z = q[0]*q[0] - q[1]*q[1] - q[2]*q[2] + q[3]*q[3];
Gurvan 0:9cb9445a11f0 157
Gurvan 0:9cb9445a11f0 158 ypr[0] = atan2(2 * q[1] * q[2] - 2 * q[0] * q[3], 2 * q[0]*q[0] + 2 * q[1] * q[1] - 1);
Gurvan 0:9cb9445a11f0 159 ypr[1] = atan(g_x * invSqrt(g_y*g_y + g_z*g_z));
Gurvan 0:9cb9445a11f0 160 ypr[2] = atan(g_y * invSqrt(g_x*g_x + g_z*g_z));
Gurvan 0:9cb9445a11f0 161 }
Gurvan 0:9cb9445a11f0 162
Gurvan 0:9cb9445a11f0 163 void GurvIMU::init()
Gurvan 0:9cb9445a11f0 164 {
Gurvan 0:9cb9445a11f0 165 mpu.initialize();
Gurvan 0:9cb9445a11f0 166 mpu.setI2CMasterModeEnabled(0);
Gurvan 0:9cb9445a11f0 167 mpu.setI2CBypassEnabled(0);
Gurvan 0:9cb9445a11f0 168 mpu.setFullScaleGyroRange(MPU6050_GYRO_FS_2000);
Gurvan 0:9cb9445a11f0 169 getOffset();
Gurvan 0:9cb9445a11f0 170 wait(0.005);
Gurvan 0:9cb9445a11f0 171 }
Gurvan 0:9cb9445a11f0 172
Gurvan 0:9cb9445a11f0 173
Gurvan 0:9cb9445a11f0 174 float invSqrt(float number)
Gurvan 0:9cb9445a11f0 175 {
Gurvan 0:9cb9445a11f0 176 volatile long i;
Gurvan 0:9cb9445a11f0 177 volatile float x, y;
Gurvan 0:9cb9445a11f0 178 volatile const float f = 1.5F;
Gurvan 0:9cb9445a11f0 179
Gurvan 0:9cb9445a11f0 180 x = number * 0.5F;
Gurvan 0:9cb9445a11f0 181 y = number;
Gurvan 0:9cb9445a11f0 182 i = * ( long * ) &y;
Gurvan 0:9cb9445a11f0 183 i = 0x5f375a86 - ( i >> 1 );
Gurvan 0:9cb9445a11f0 184 y = * ( float * ) &i;
Gurvan 0:9cb9445a11f0 185 y = y * ( f - ( x * y * y ) );
Gurvan 0:9cb9445a11f0 186 return y;
Gurvan 0:9cb9445a11f0 187 }