Akira Heya
Comparison with attitude estimation filter IMU : MPU9250
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MPU9250.h
00001 //------------------------------------------------------------------------------ 00002 // Attitude measurement using IMU(MPU-9250) 00003 //------------------------------------------------------------------------------ 00004 #ifndef MPU9250_H 00005 #define MPU9250_H 00006 00007 #include "mbed.h" 00008 #include "math.h" 00009 00010 //Magnetometer Registers 00011 #define AK8963_ADDRESS 0x0C<<1 00012 #define WHO_AM_I_AK8963 0x00 // should return 0x48 00013 #define INFO 0x01 00014 #define AK8963_ST1 0x02 // data ready status bit 0 00015 #define AK8963_XOUT_L 0x03 // data 00016 #define AK8963_XOUT_H 0x04 00017 #define AK8963_YOUT_L 0x05 00018 #define AK8963_YOUT_H 0x06 00019 #define AK8963_ZOUT_L 0x07 00020 #define AK8963_ZOUT_H 0x08 00021 #define AK8963_ST2 0x09 // Data overflow bit 3 and data read error status bit 2 00022 #define AK8963_CNTL 0x0A // Power down (0000), single-measurement (0001), self-test (1000) and Fuse ROM (1111) modes on bits 3:0 00023 #define AK8963_ASTC 0x0C // Self test control 00024 #define AK8963_I2CDIS 0x0F // I2C disable 00025 #define AK8963_ASAX 0x10 // Fuse ROM x-axis sensitivity adjustment value 00026 #define AK8963_ASAY 0x11 // Fuse ROM y-axis sensitivity adjustment value 00027 #define AK8963_ASAZ 0x12 // Fuse ROM z-axis sensitivity adjustment value 00028 00029 #define SELF_TEST_X_GYRO 0x00 00030 #define SELF_TEST_Y_GYRO 0x01 00031 #define SELF_TEST_Z_GYRO 0x02 00032 00033 /* 00034 #define X_FINE_GAIN 0x03 // [7:0] fine gain 00035 #define Y_FINE_GAIN 0x04 00036 #define Z_FINE_GAIN 0x05 00037 #define XA_OFFSET_H 0x06 // User-defined trim values for accelerometer 00038 #define XA_OFFSET_L_TC 0x07 00039 #define YA_OFFSET_H 0x08 00040 #define YA_OFFSET_L_TC 0x09 00041 #define ZA_OFFSET_H 0x0A 00042 #define ZA_OFFSET_L_TC 0x0B 00043 */ 00044 00045 #define SELF_TEST_X_ACCEL 0x0D 00046 #define SELF_TEST_Y_ACCEL 0x0E 00047 #define SELF_TEST_Z_ACCEL 0x0F 00048 00049 #define SELF_TEST_A 0x10 00050 00051 #define XG_OFFSET_H 0x13 // User-defined trim values for gyroscope 00052 #define XG_OFFSET_L 0x14 00053 #define YG_OFFSET_H 0x15 00054 #define YG_OFFSET_L 0x16 00055 #define ZG_OFFSET_H 0x17 00056 #define ZG_OFFSET_L 0x18 00057 #define SMPLRT_DIV 0x19 00058 #define CONFIG 0x1A 00059 #define GYRO_CONFIG 0x1B 00060 #define ACCEL_CONFIG 0x1C 00061 #define ACCEL_CONFIG2 0x1D 00062 #define LP_ACCEL_ODR 0x1E 00063 #define WOM_THR 0x1F 00064 00065 #define MOT_DUR 0x20 // Duration counter threshold for motion interrupt generation, 1 kHz rate, LSB = 1 ms 00066 #define ZMOT_THR 0x21 // Zero-motion detection threshold bits [7:0] 00067 #define ZRMOT_DUR 0x22 // Duration counter threshold for zero motion interrupt generation, 16 Hz rate, LSB = 64 ms 00068 00069 #define FIFO_EN 0x23 00070 #define I2C_MST_CTRL 0x24 00071 #define I2C_SLV0_ADDR 0x25 00072 #define I2C_SLV0_REG 0x26 00073 #define I2C_SLV0_CTRL 0x27 00074 #define I2C_SLV1_ADDR 0x28 00075 #define I2C_SLV1_REG 0x29 00076 #define I2C_SLV1_CTRL 0x2A 00077 #define I2C_SLV2_ADDR 0x2B 00078 #define I2C_SLV2_REG 0x2C 00079 #define I2C_SLV2_CTRL 0x2D 00080 #define I2C_SLV3_ADDR 0x2E 00081 #define I2C_SLV3_REG 0x2F 00082 #define I2C_SLV3_CTRL 0x30 00083 #define I2C_SLV4_ADDR 0x31 00084 #define I2C_SLV4_REG 0x32 00085 #define I2C_SLV4_DO 0x33 00086 #define I2C_SLV4_CTRL 0x34 00087 #define I2C_SLV4_DI 0x35 00088 #define I2C_MST_STATUS 0x36 00089 #define INT_PIN_CFG 0x37 00090 #define INT_ENABLE 0x38 00091 #define DMP_INT_STATUS 0x39 // Check DMP interrupt 00092 #define INT_STATUS 0x3A 00093 #define ACCEL_XOUT_H 0x3B 00094 #define ACCEL_XOUT_L 0x3C 00095 #define ACCEL_YOUT_H 0x3D 00096 #define ACCEL_YOUT_L 0x3E 00097 #define ACCEL_ZOUT_H 0x3F 00098 #define ACCEL_ZOUT_L 0x40 00099 #define TEMP_OUT_H 0x41 00100 #define TEMP_OUT_L 0x42 00101 #define GYRO_XOUT_H 0x43 00102 #define GYRO_XOUT_L 0x44 00103 #define GYRO_YOUT_H 0x45 00104 #define GYRO_YOUT_L 0x46 00105 #define GYRO_ZOUT_H 0x47 00106 #define GYRO_ZOUT_L 0x48 00107 #define EXT_SENS_DATA_00 0x49 00108 #define EXT_SENS_DATA_01 0x4A 00109 #define EXT_SENS_DATA_02 0x4B 00110 #define EXT_SENS_DATA_03 0x4C 00111 #define EXT_SENS_DATA_04 0x4D 00112 #define EXT_SENS_DATA_05 0x4E 00113 #define EXT_SENS_DATA_06 0x4F 00114 #define EXT_SENS_DATA_07 0x50 00115 #define EXT_SENS_DATA_08 0x51 00116 #define EXT_SENS_DATA_09 0x52 00117 #define EXT_SENS_DATA_10 0x53 00118 #define EXT_SENS_DATA_11 0x54 00119 #define EXT_SENS_DATA_12 0x55 00120 #define EXT_SENS_DATA_13 0x56 00121 #define EXT_SENS_DATA_14 0x57 00122 #define EXT_SENS_DATA_15 0x58 00123 #define EXT_SENS_DATA_16 0x59 00124 #define EXT_SENS_DATA_17 0x5A 00125 #define EXT_SENS_DATA_18 0x5B 00126 #define EXT_SENS_DATA_19 0x5C 00127 #define EXT_SENS_DATA_20 0x5D 00128 #define EXT_SENS_DATA_21 0x5E 00129 #define EXT_SENS_DATA_22 0x5F 00130 #define EXT_SENS_DATA_23 0x60 00131 #define MOT_DETECT_STATUS 0x61 00132 #define I2C_SLV0_DO 0x63 00133 #define I2C_SLV1_DO 0x64 00134 #define I2C_SLV2_DO 0x65 00135 #define I2C_SLV3_DO 0x66 00136 #define I2C_MST_DELAY_CTRL 0x67 00137 #define SIGNAL_PATH_RESET 0x68 00138 #define MOT_DETECT_CTRL 0x69 00139 #define USER_CTRL 0x6A // Bit 7 enable DMP, bit 3 reset DMP 00140 #define PWR_MGMT_1 0x6B // Device defaults to the SLEEP mode 00141 #define PWR_MGMT_2 0x6C 00142 #define DMP_BANK 0x6D // Activates a specific bank in the DMP 00143 #define DMP_RW_PNT 0x6E // Set read/write pointer to a specific start address in specified DMP bank 00144 #define DMP_REG 0x6F // Register in DMP from which to read or to which to write 00145 #define DMP_REG_1 0x70 00146 #define DMP_REG_2 0x71 00147 #define FIFO_COUNTH 0x72 00148 #define FIFO_COUNTL 0x73 00149 #define FIFO_R_W 0x74 00150 #define WHO_AM_I_MPU9250 0x75 // Should return 0x71 00151 #define XA_OFFSET_H 0x77 00152 #define XA_OFFSET_L 0x78 00153 #define YA_OFFSET_H 0x7A 00154 #define YA_OFFSET_L 0x7B 00155 #define ZA_OFFSET_H 0x7D 00156 #define ZA_OFFSET_L 0x7E 00157 00158 // Seven-bit device address is 110100 for ADO = 0 and 110101 for ADO = 1 00159 //mbed uses the eight-bit device address, so shift seven-bit addresses left by one! 00160 #define ADO 0 00161 #if ADO 00162 #define MPU9250_ADDRESS 0x69<<1 // Device address when ADO = 1 00163 #else 00164 #define MPU9250_ADDRESS 0x68<<1 // Device address when ADO = 0 00165 #endif 00166 00167 // Set initial input parameters 00168 enum Ascale { 00169 AFS_2G = 0, 00170 AFS_4G, 00171 AFS_8G, 00172 AFS_16G 00173 }; 00174 00175 enum Gscale { 00176 GFS_250DPS = 0, 00177 GFS_500DPS, 00178 GFS_1000DPS, 00179 GFS_2000DPS 00180 }; 00181 00182 enum Mscale { 00183 MFS_14BITS = 0, // 0.6 mG per LSB 00184 MFS_16BITS // 0.15 mG per LSB 00185 }; 00186 00187 uint8_t Ascale = AFS_2G; // AFS_2G, AFS_4G, AFS_8G, AFS_16G 00188 uint8_t Gscale = GFS_250DPS; // GFS_250DPS, GFS_500DPS, GFS_1000DPS, GFS_2000DPS 00189 uint8_t Mscale = MFS_16BITS; // MFS_14BITS or MFS_16BITS, 14-bit or 16-bit magnetometer resolution 00190 uint8_t Mmode = 0x06; // Either 8 Hz 0x02) or 100 Hz (0x06) magnetometer data ODR 00191 float aRes, gRes, mRes; // scale resolutions per LSB for the sensors 00192 00193 //Set up I2C, (SDA,SCL) 00194 I2C i2c(p9, p10); 00195 00196 // Pin definitions 00197 int16_t accelCount[3]; // Stores the 16-bit signed accelerometer sensor output 00198 int16_t gyroCount[3]; // Stores the 16-bit signed gyro sensor output 00199 int16_t magCount[3]; // Stores the 16-bit signed magnetometer sensor output 00200 float magCalibration[3] = {0, 0, 0}, magbias[3] = {0, 0, 0}; // Factory mag calibration and mag bias 00201 float gyroBias[3] = {0, 0, 0}, accelBias[3] = {0, 0, 0}; // Bias corrections for gyro and accelerometer 00202 float ax, ay, az, gx, gy, gz, mx, my, mz; // variables to hold latest sensor data values 00203 float th_ax, th_ay, th_az; 00204 float th_ax_LPF, th_ay_LPF, th_az_LPF; 00205 float pre_th_ax, pre_th_ay, pre_th_az; 00206 float th_gx, th_gy, th_gz; 00207 float pre_gx, pre_gy, pre_gz; 00208 float th_x, th_y, th_z, th_x_d, th_y_d, th_z_d; 00209 int16_t tempCount; // Stores the real internal chip temperature in degrees Celsius 00210 float temperature; 00211 float SelfTest[6]; 00212 00213 float delt_t = 0.0f; // used to display output rate 00214 float sum_dt = 0.0f; // 00215 float dt0_ekf, dt1_ekf, dt0_mwf, dt1_mwf; 00216 00217 // parameters for 6 DoF sensor fusion calculations 00218 float PI = 3.14159265358979323846f; 00219 float GyroMeasError = PI * (60.0f / 180.0f); // gyroscope measurement error in rads/s (start at 60 deg/s), then reduce after ~10 s to 3 00220 float beta = sqrt(3.0f / 4.0f) * GyroMeasError; // compute beta 00221 float GyroMeasDrift = PI * (1.0f / 180.0f); // gyroscope measurement drift in rad/s/s (start at 0.0 deg/s/s) 00222 float zeta = sqrt(3.0f / 4.0f) * GyroMeasDrift; // compute zeta, the other free parameter in the Madgwick scheme usually set to a small or zero value 00223 #define Kp 2.0f * 5.0f // these are the free parameters in the Mahony filter and fusion scheme, Kp for proportional feedback, Ki for integral 00224 #define Ki 0.0f 00225 00226 float pitch, yaw, roll; 00227 float pre_pitch, pre_roll; 00228 float lastUpdate = 0.0f, firstUpdate = 0.0f, Now = 0.0f; // used to calculate integration interval // used to calculate integration interval 00229 float q[4] = {1.0f, 0.0f, 0.0f, 0.0f}; // vector to hold quaternion 00230 float q1 = 1.0f; 00231 float q2 = 0.0f; 00232 float q3 = 0.0f; 00233 float q4 = 0.0f; 00234 float eInt[3] = {0.0f, 0.0f, 0.0f}; // vector to hold integral error for Mahony method 00235 00236 class MPU9250 { 00237 00238 protected: 00239 00240 public: 00241 //=================================================================================================================== 00242 //====== Set of useful function to access acceleratio, gyroscope, and temperature data 00243 //=================================================================================================================== 00244 00245 void writeByte(uint8_t address, uint8_t subAddress, uint8_t data) 00246 { 00247 char data_write[2]; 00248 data_write[0] = subAddress; 00249 data_write[1] = data; 00250 i2c.write(address, data_write, 2, 0); 00251 } 00252 00253 char readByte(uint8_t address, uint8_t subAddress) 00254 { 00255 char data[1]; // `data` will store the register data 00256 char data_write[1]; 00257 data_write[0] = subAddress; 00258 i2c.write(address, data_write, 1, 1); // no stop 00259 i2c.read(address, data, 1, 0); 00260 return data[0]; 00261 } 00262 00263 void readBytes(uint8_t address, uint8_t subAddress, uint8_t count, uint8_t * dest) 00264 { 00265 char data[14]; 00266 char data_write[1]; 00267 data_write[0] = subAddress; 00268 i2c.write(address, data_write, 1, 1); // no stop 00269 i2c.read(address, data, count, 0); 00270 for(int ii = 0; ii < count; ii++) { 00271 dest[ii] = data[ii]; 00272 } 00273 } 00274 00275 void getMres() { 00276 switch (Mscale) 00277 { 00278 // Possible magnetometer scales (and their register bit settings) are: 00279 // 14 bit resolution (0) and 16 bit resolution (1) 00280 case MFS_14BITS: 00281 mRes = 10.0*4219.0/8190.0; // Proper scale to return milliGauss 00282 break; 00283 case MFS_16BITS: 00284 mRes = 10.0*4219.0/32760.0; // Proper scale to return milliGauss 00285 break; 00286 } 00287 } 00288 00289 void getGres() { 00290 switch (Gscale) 00291 { 00292 // Possible gyro scales (and their register bit settings) are: 00293 // 250 DPS (00), 500 DPS (01), 1000 DPS (10), and 2000 DPS (11). 00294 // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value: 00295 case GFS_250DPS: 00296 gRes = 250.0/32768.0; 00297 break; 00298 case GFS_500DPS: 00299 gRes = 500.0/32768.0; 00300 break; 00301 case GFS_1000DPS: 00302 gRes = 1000.0/32768.0; 00303 break; 00304 case GFS_2000DPS: 00305 gRes = 2000.0/32768.0; 00306 break; 00307 } 00308 } 00309 00310 void getAres() { 00311 switch (Ascale) 00312 { 00313 // Possible accelerometer scales (and their register bit settings) are: 00314 // 2 Gs (00), 4 Gs (01), 8 Gs (10), and 16 Gs (11). 00315 // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value: 00316 case AFS_2G: 00317 aRes = 2.0/32768.0; 00318 break; 00319 case AFS_4G: 00320 aRes = 4.0/32768.0; 00321 break; 00322 case AFS_8G: 00323 aRes = 8.0/32768.0; 00324 break; 00325 case AFS_16G: 00326 aRes = 16.0/32768.0; 00327 break; 00328 } 00329 } 00330 00331 00332 void readAccelData(int16_t * destination) 00333 { 00334 uint8_t rawData[6]; // x/y/z accel register data stored here 00335 readBytes(MPU9250_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array 00336 destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value 00337 destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; 00338 destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 00339 } 00340 00341 void readGyroData(int16_t * destination) 00342 { 00343 uint8_t rawData[6]; // x/y/z gyro register data stored here 00344 readBytes(MPU9250_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array 00345 destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value 00346 destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; 00347 destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 00348 } 00349 00350 void readMagData(int16_t * destination) 00351 { 00352 uint8_t rawData[7]; // x/y/z gyro register data, ST2 register stored here, must read ST2 at end of data acquisition 00353 if(readByte(AK8963_ADDRESS, AK8963_ST1) & 0x01) { // wait for magnetometer data ready bit to be set 00354 readBytes(AK8963_ADDRESS, AK8963_XOUT_L, 7, &rawData[0]); // Read the six raw data and ST2 registers sequentially into data array 00355 uint8_t c = rawData[6]; // End data read by reading ST2 register 00356 if(!(c & 0x08)) 00357 { // Check if magnetic sensor overflow set, if not then report data 00358 destination[0] = (int16_t)(((int16_t)rawData[1] << 8) | rawData[0]); // Turn the MSB and LSB into a signed 16-bit value 00359 destination[1] = (int16_t)(((int16_t)rawData[3] << 8) | rawData[2]) ; // Data stored as little Endian 00360 destination[2] = (int16_t)(((int16_t)rawData[5] << 8) | rawData[4]) ; 00361 } 00362 } 00363 } 00364 00365 int16_t readTempData() 00366 { 00367 uint8_t rawData[2]; // x/y/z gyro register data stored here 00368 readBytes(MPU9250_ADDRESS, TEMP_OUT_H, 2, &rawData[0]); // Read the two raw data registers sequentially into data array 00369 return (int16_t)(((int16_t)rawData[0]) << 8 | rawData[1]) ; // Turn the MSB and LSB into a 16-bit value 00370 } 00371 00372 00373 void resetMPU9250() 00374 { 00375 // reset device 00376 writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device 00377 wait(0.1); 00378 } 00379 00380 void initAK8963(float * destination) 00381 { 00382 // First extract the factory calibration for each magnetometer axis 00383 uint8_t rawData[3]; // x/y/z gyro calibration data stored here 00384 writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x00); // Power down magnetometer 00385 wait(0.01); 00386 writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x0F); // Enter Fuse ROM access mode 00387 wait(0.01); 00388 readBytes(AK8963_ADDRESS, AK8963_ASAX, 3, &rawData[0]); // Read the x-, y-, and z-axis calibration values 00389 destination[0] = (float)(rawData[0] - 128)/256.0f + 1.0f; // Return x-axis sensitivity adjustment values, etc. 00390 destination[1] = (float)(rawData[1] - 128)/256.0f + 1.0f; 00391 destination[2] = (float)(rawData[2] - 128)/256.0f + 1.0f; 00392 writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x00); // Power down magnetometer 00393 wait(0.01); 00394 // Configure the magnetometer for continuous read and highest resolution 00395 // set Mscale bit 4 to 1 (0) to enable 16 (14) bit resolution in CNTL register, 00396 // and enable continuous mode data acquisition Mmode (bits [3:0]), 0010 for 8 Hz and 0110 for 100 Hz sample rates 00397 writeByte(AK8963_ADDRESS, AK8963_CNTL, Mscale << 4 | Mmode); // Set magnetometer data resolution and sample ODR 00398 wait(0.01); 00399 } 00400 00401 00402 void initMPU9250() 00403 { 00404 // Initialize MPU9250 device 00405 // wake up device 00406 writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x00); // Clear sleep mode bit (6), enable all sensors 00407 wait(0.1); // Delay 100 ms for PLL to get established on x-axis gyro; should check for PLL ready interrupt 00408 00409 // get stable time source 00410 writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x01); // Set clock source to be PLL with x-axis gyroscope reference, bits 2:0 = 001 00411 00412 // Configure Gyro and Accelerometer 00413 // Disable FSYNC and set accelerometer and gyro bandwidth to 44 and 42 Hz, respectively; 00414 // DLPF_CFG = bits 2:0 = 010; this sets the sample rate at 1 kHz for both 00415 // Maximum delay is 4.9 ms which is just over a 200 Hz maximum rate 00416 writeByte(MPU9250_ADDRESS, CONFIG, 0x03); 00417 00418 // Set sample rate = gyroscope output rate/(1 + SMPLRT_DIV) 00419 writeByte(MPU9250_ADDRESS, SMPLRT_DIV, 0x04); // Use a 200 Hz rate; the same rate set in CONFIG above 00420 00421 // Set gyroscope full scale range 00422 // Range selects FS_SEL and AFS_SEL are 0 - 3, so 2-bit values are left-shifted into positions 4:3 00423 uint8_t c = readByte(MPU9250_ADDRESS, GYRO_CONFIG); 00424 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, c & ~0xE0); // Clear self-test bits [7:5] 00425 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, c & ~0x18); // Clear AFS bits [4:3] 00426 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, c | Gscale << 3); // Set full scale range for the gyro 00427 00428 // Set accelerometer configuration 00429 c = readByte(MPU9250_ADDRESS, ACCEL_CONFIG); 00430 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, c & ~0xE0); // Clear self-test bits [7:5] 00431 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, c & ~0x18); // Clear AFS bits [4:3] 00432 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, c | Ascale << 3); // Set full scale range for the accelerometer 00433 00434 // Set accelerometer sample rate configuration 00435 // It is possible to get a 4 kHz sample rate from the accelerometer by choosing 1 for 00436 // accel_fchoice_b bit [3]; in this case the bandwidth is 1.13 kHz 00437 c = readByte(MPU9250_ADDRESS, ACCEL_CONFIG2); 00438 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG2, c & ~0x0F); // Clear accel_fchoice_b (bit 3) and A_DLPFG (bits [2:0]) 00439 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG2, c | 0x03); // Set accelerometer rate to 1 kHz and bandwidth to 41 Hz 00440 00441 // The accelerometer, gyro, and thermometer are set to 1 kHz sample rates, 00442 // but all these rates are further reduced by a factor of 5 to 200 Hz because of the SMPLRT_DIV setting 00443 00444 // Configure Interrupts and Bypass Enable 00445 // Set interrupt pin active high, push-pull, and clear on read of INT_STATUS, enable I2C_BYPASS_EN so additional chips 00446 // can join the I2C bus and all can be controlled by the Arduino as master 00447 writeByte(MPU9250_ADDRESS, INT_PIN_CFG, 0x22); 00448 writeByte(MPU9250_ADDRESS, INT_ENABLE, 0x01); // Enable data ready (bit 0) interrupt 00449 } 00450 00451 // Function which accumulates gyro and accelerometer data after device initialization. It calculates the average 00452 // of the at-rest readings and then loads the resulting offsets into accelerometer and gyro bias registers. 00453 void calibrateMPU9250(float * dest1, float * dest2) 00454 { 00455 uint8_t data[12]; // data array to hold accelerometer and gyro x, y, z, data 00456 uint16_t ii, packet_count, fifo_count; 00457 int32_t gyro_bias[3] = {0, 0, 0}, accel_bias[3] = {0, 0, 0}; 00458 00459 // reset device, reset all registers, clear gyro and accelerometer bias registers 00460 writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device 00461 wait(0.1); 00462 00463 // get stable time source 00464 // Set clock source to be PLL with x-axis gyroscope reference, bits 2:0 = 001 00465 writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x01); 00466 writeByte(MPU9250_ADDRESS, PWR_MGMT_2, 0x00); 00467 wait(0.2); 00468 00469 // Configure device for bias calculation 00470 writeByte(MPU9250_ADDRESS, INT_ENABLE, 0x00); // Disable all interrupts 00471 writeByte(MPU9250_ADDRESS, FIFO_EN, 0x00); // Disable FIFO 00472 writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x00); // Turn on internal clock source 00473 writeByte(MPU9250_ADDRESS, I2C_MST_CTRL, 0x00); // Disable I2C master 00474 writeByte(MPU9250_ADDRESS, USER_CTRL, 0x00); // Disable FIFO and I2C master modes 00475 writeByte(MPU9250_ADDRESS, USER_CTRL, 0x0C); // Reset FIFO and DMP 00476 wait(0.015); 00477 00478 // Configure MPU9250 gyro and accelerometer for bias calculation 00479 writeByte(MPU9250_ADDRESS, CONFIG, 0x01); // Set low-pass filter to 188 Hz 00480 writeByte(MPU9250_ADDRESS, SMPLRT_DIV, 0x00); // Set sample rate to 1 kHz 00481 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 0x00); // Set gyro full-scale to 250 degrees per second, maximum sensitivity 00482 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, 0x00); // Set accelerometer full-scale to 2 g, maximum sensitivity 00483 00484 uint16_t gyrosensitivity = 131; // = 131 LSB/degrees/sec 00485 uint16_t accelsensitivity = 16384; // = 16384 LSB/g 00486 00487 // Configure FIFO to capture accelerometer and gyro data for bias calculation 00488 writeByte(MPU9250_ADDRESS, USER_CTRL, 0x40); // Enable FIFO 00489 writeByte(MPU9250_ADDRESS, FIFO_EN, 0x78); // Enable gyro and accelerometer sensors for FIFO (max size 512 bytes in MPU-9250) 00490 wait(0.04); // accumulate 40 samples in 80 milliseconds = 480 bytes 00491 00492 // At end of sample accumulation, turn off FIFO sensor read 00493 writeByte(MPU9250_ADDRESS, FIFO_EN, 0x00); // Disable gyro and accelerometer sensors for FIFO 00494 readBytes(MPU9250_ADDRESS, FIFO_COUNTH, 2, &data[0]); // read FIFO sample count 00495 fifo_count = ((uint16_t)data[0] << 8) | data[1]; 00496 packet_count = fifo_count/12;// How many sets of full gyro and accelerometer data for averaging 00497 00498 for (ii = 0; ii < packet_count; ii++) 00499 { 00500 int16_t accel_temp[3] = {0, 0, 0}, gyro_temp[3] = {0, 0, 0}; 00501 readBytes(MPU9250_ADDRESS, FIFO_R_W, 12, &data[0]); // read data for averaging 00502 accel_temp[0] = (int16_t) (((int16_t)data[0] << 8) | data[1] ) ; // Form signed 16-bit integer for each sample in FIFO 00503 accel_temp[1] = (int16_t) (((int16_t)data[2] << 8) | data[3] ) ; 00504 accel_temp[2] = (int16_t) (((int16_t)data[4] << 8) | data[5] ) ; 00505 gyro_temp[0] = (int16_t) (((int16_t)data[6] << 8) | data[7] ) ; 00506 gyro_temp[1] = (int16_t) (((int16_t)data[8] << 8) | data[9] ) ; 00507 gyro_temp[2] = (int16_t) (((int16_t)data[10] << 8) | data[11]) ; 00508 00509 accel_bias[0] += (int32_t) accel_temp[0]; // Sum individual signed 16-bit biases to get accumulated signed 32-bit biases 00510 accel_bias[1] += (int32_t) accel_temp[1]; 00511 accel_bias[2] += (int32_t) accel_temp[2]; 00512 gyro_bias[0] += (int32_t) gyro_temp[0]; 00513 gyro_bias[1] += (int32_t) gyro_temp[1]; 00514 gyro_bias[2] += (int32_t) gyro_temp[2]; 00515 } 00516 00517 accel_bias[0] /= (int32_t) packet_count; // Normalize sums to get average count biases 00518 accel_bias[1] /= (int32_t) packet_count; 00519 accel_bias[2] /= (int32_t) packet_count; 00520 gyro_bias[0] /= (int32_t) packet_count; 00521 gyro_bias[1] /= (int32_t) packet_count; 00522 gyro_bias[2] /= (int32_t) packet_count; 00523 00524 if(accel_bias[2] > 0L) {accel_bias[2] -= (int32_t) accelsensitivity;} // Remove gravity from the z-axis accelerometer bias calculation 00525 else {accel_bias[2] += (int32_t) accelsensitivity;} 00526 00527 // Construct the gyro biases for push to the hardware gyro bias registers, which are reset to zero upon device startup 00528 data[0] = (-gyro_bias[0]/4 >> 8) & 0xFF; // Divide by 4 to get 32.9 LSB per deg/s to conform to expected bias input format 00529 data[1] = (-gyro_bias[0]/4) & 0xFF; // Biases are additive, so change sign on calculated average gyro biases 00530 data[2] = (-gyro_bias[1]/4 >> 8) & 0xFF; 00531 data[3] = (-gyro_bias[1]/4) & 0xFF; 00532 data[4] = (-gyro_bias[2]/4 >> 8) & 0xFF; 00533 data[5] = (-gyro_bias[2]/4) & 0xFF; 00534 00535 /// Push gyro biases to hardware registers 00536 /* writeByte(MPU9250_ADDRESS, XG_OFFSET_H, data[0]); 00537 writeByte(MPU9250_ADDRESS, XG_OFFSET_L, data[1]); 00538 writeByte(MPU9250_ADDRESS, YG_OFFSET_H, data[2]); 00539 writeByte(MPU9250_ADDRESS, YG_OFFSET_L, data[3]); 00540 writeByte(MPU9250_ADDRESS, ZG_OFFSET_H, data[4]); 00541 writeByte(MPU9250_ADDRESS, ZG_OFFSET_L, data[5]); 00542 */ 00543 dest1[0] = (float) gyro_bias[0]/(float) gyrosensitivity; // construct gyro bias in deg/s for later manual subtraction 00544 dest1[1] = (float) gyro_bias[1]/(float) gyrosensitivity; 00545 dest1[2] = (float) gyro_bias[2]/(float) gyrosensitivity; 00546 00547 // Construct the accelerometer biases for push to the hardware accelerometer bias registers. These registers contain 00548 // factory trim values which must be added to the calculated accelerometer biases; on boot up these registers will hold 00549 // non-zero values. In addition, bit 0 of the lower byte must be preserved since it is used for temperature 00550 // compensation calculations. Accelerometer bias registers expect bias input as 2048 LSB per g, so that 00551 // the accelerometer biases calculated above must be divided by 8. 00552 00553 int32_t accel_bias_reg[3] = {0, 0, 0}; // A place to hold the factory accelerometer trim biases 00554 readBytes(MPU9250_ADDRESS, XA_OFFSET_H, 2, &data[0]); // Read factory accelerometer trim values 00555 accel_bias_reg[0] = (int16_t) ((int16_t)data[0] << 8) | data[1]; 00556 readBytes(MPU9250_ADDRESS, YA_OFFSET_H, 2, &data[0]); 00557 accel_bias_reg[1] = (int16_t) ((int16_t)data[0] << 8) | data[1]; 00558 readBytes(MPU9250_ADDRESS, ZA_OFFSET_H, 2, &data[0]); 00559 accel_bias_reg[2] = (int16_t) ((int16_t)data[0] << 8) | data[1]; 00560 00561 uint32_t mask = 1uL; // Define mask for temperature compensation bit 0 of lower byte of accelerometer bias registers 00562 uint8_t mask_bit[3] = {0, 0, 0}; // Define array to hold mask bit for each accelerometer bias axis 00563 00564 for(ii = 0; ii < 3; ii++) 00565 { 00566 if(accel_bias_reg[ii] & mask) mask_bit[ii] = 0x01; // If temperature compensation bit is set, record that fact in mask_bit 00567 } 00568 00569 // Construct total accelerometer bias, including calculated average accelerometer bias from above 00570 accel_bias_reg[0] -= (accel_bias[0]/8); // Subtract calculated averaged accelerometer bias scaled to 2048 LSB/g (16 g full scale) 00571 accel_bias_reg[1] -= (accel_bias[1]/8); 00572 accel_bias_reg[2] -= (accel_bias[2]/8); 00573 00574 data[0] = (accel_bias_reg[0] >> 8) & 0xFF; 00575 data[1] = (accel_bias_reg[0]) & 0xFF; 00576 data[1] = data[1] | mask_bit[0]; // preserve temperature compensation bit when writing back to accelerometer bias registers 00577 data[2] = (accel_bias_reg[1] >> 8) & 0xFF; 00578 data[3] = (accel_bias_reg[1]) & 0xFF; 00579 data[3] = data[3] | mask_bit[1]; // preserve temperature compensation bit when writing back to accelerometer bias registers 00580 data[4] = (accel_bias_reg[2] >> 8) & 0xFF; 00581 data[5] = (accel_bias_reg[2]) & 0xFF; 00582 data[5] = data[5] | mask_bit[2]; // preserve temperature compensation bit when writing back to accelerometer bias registers 00583 00584 // Apparently this is not working for the acceleration biases in the MPU-9250 00585 // Are we handling the temperature correction bit properly? 00586 // Push accelerometer biases to hardware registers 00587 /* writeByte(MPU9250_ADDRESS, XA_OFFSET_H, data[0]); 00588 writeByte(MPU9250_ADDRESS, XA_OFFSET_L, data[1]); 00589 writeByte(MPU9250_ADDRESS, YA_OFFSET_H, data[2]); 00590 writeByte(MPU9250_ADDRESS, YA_OFFSET_L, data[3]); 00591 writeByte(MPU9250_ADDRESS, ZA_OFFSET_H, data[4]); 00592 writeByte(MPU9250_ADDRESS, ZA_OFFSET_L, data[5]); 00593 */ 00594 // Output scaled accelerometer biases for manual subtraction in the main program 00595 dest2[0] = (float)accel_bias[0]/(float)accelsensitivity; 00596 dest2[1] = (float)accel_bias[1]/(float)accelsensitivity; 00597 dest2[2] = (float)accel_bias[2]/(float)accelsensitivity; 00598 } 00599 00600 00601 // Accelerometer and gyroscope self test; check calibration wrt factory settings 00602 void MPU9250SelfTest(float * destination) // Should return percent deviation from factory trim values, +/- 14 or less deviation is a pass 00603 { 00604 uint8_t rawData[6] = {0, 0, 0, 0, 0, 0}; 00605 uint8_t selfTest[6]; 00606 int16_t gAvg[3], aAvg[3], aSTAvg[3], gSTAvg[3]; 00607 float factoryTrim[6]; 00608 uint8_t FS = 0; 00609 00610 writeByte(MPU9250_ADDRESS, SMPLRT_DIV, 0x00); // Set gyro sample rate to 1 kHz 00611 writeByte(MPU9250_ADDRESS, CONFIG, 0x02); // Set gyro sample rate to 1 kHz and DLPF to 92 Hz 00612 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 1<<FS); // Set full scale range for the gyro to 250 dps 00613 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG2, 0x02); // Set accelerometer rate to 1 kHz and bandwidth to 92 Hz 00614 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, 1<<FS); // Set full scale range for the accelerometer to 2 g 00615 00616 for( int ii = 0; ii < 200; ii++) { // get average current values of gyro and acclerometer 00617 00618 readBytes(MPU9250_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array 00619 aAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value 00620 aAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; 00621 aAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 00622 00623 readBytes(MPU9250_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array 00624 gAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value 00625 gAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; 00626 gAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 00627 } 00628 00629 for (int ii =0; ii < 3; ii++) 00630 { 00631 // Get average of 200 values and store as average current readings 00632 aAvg[ii] /= 200; 00633 gAvg[ii] /= 200; 00634 } 00635 00636 // Configure the accelerometer for self-test 00637 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, 0xE0); // Enable self test on all three axes and set accelerometer range to +/- 2 g 00638 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 0xE0); // Enable self test on all three axes and set gyro range to +/- 250 degrees/s 00639 //delay(25); // Delay a while to let the device stabilize 00640 00641 for( int ii = 0; ii < 200; ii++) 00642 { 00643 // get average self-test values of gyro and acclerometer 00644 readBytes(MPU9250_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array 00645 aSTAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value 00646 aSTAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; 00647 aSTAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 00648 00649 readBytes(MPU9250_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array 00650 gSTAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value 00651 gSTAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; 00652 gSTAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 00653 } 00654 00655 for (int ii =0; ii < 3; ii++) 00656 { 00657 // Get average of 200 values and store as average self-test readings 00658 aSTAvg[ii] /= 200; 00659 gSTAvg[ii] /= 200; 00660 } 00661 00662 // Configure the gyro and accelerometer for normal operation 00663 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, 0x00); 00664 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 0x00); 00665 //delay(25); // Delay a while to let the device stabilize 00666 00667 // Retrieve accelerometer and gyro factory Self-Test Code from USR_Reg 00668 selfTest[0] = readByte(MPU9250_ADDRESS, SELF_TEST_X_ACCEL); // X-axis accel self-test results 00669 selfTest[1] = readByte(MPU9250_ADDRESS, SELF_TEST_Y_ACCEL); // Y-axis accel self-test results 00670 selfTest[2] = readByte(MPU9250_ADDRESS, SELF_TEST_Z_ACCEL); // Z-axis accel self-test results 00671 selfTest[3] = readByte(MPU9250_ADDRESS, SELF_TEST_X_GYRO); // X-axis gyro self-test results 00672 selfTest[4] = readByte(MPU9250_ADDRESS, SELF_TEST_Y_GYRO); // Y-axis gyro self-test results 00673 selfTest[5] = readByte(MPU9250_ADDRESS, SELF_TEST_Z_GYRO); // Z-axis gyro self-test results 00674 00675 // Retrieve factory self-test value from self-test code reads 00676 factoryTrim[0] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[0] - 1.0) )); // FT[Xa] factory trim calculation 00677 factoryTrim[1] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[1] - 1.0) )); // FT[Ya] factory trim calculation 00678 factoryTrim[2] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[2] - 1.0) )); // FT[Za] factory trim calculation 00679 factoryTrim[3] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[3] - 1.0) )); // FT[Xg] factory trim calculation 00680 factoryTrim[4] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[4] - 1.0) )); // FT[Yg] factory trim calculation 00681 factoryTrim[5] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[5] - 1.0) )); // FT[Zg] factory trim calculation 00682 00683 // Report results as a ratio of (STR - FT)/FT; the change from Factory Trim of the Self-Test Response 00684 // To get percent, must multiply by 100 00685 for (int i = 0; i < 3; i++) 00686 { 00687 destination[i] = 100.0*((float)(aSTAvg[i] - aAvg[i]))/factoryTrim[i]; // Report percent differences 00688 destination[i+3] = 100.0*((float)(gSTAvg[i] - gAvg[i]))/factoryTrim[i+3]; // Report percent differences 00689 } 00690 00691 } 00692 00693 void MadgwickFilterUpdate_6axis(float ax, float ay, float az, float wx, float wy, float wz) 00694 { 00695 // Local system variables 00696 float norm; // vector norm 00697 float SEqDot_omega_1, SEqDot_omega_2, SEqDot_omega_3, SEqDot_omega_4; // quaternion derrivative from gyroscopes elements 00698 float f_1, f_2, f_3; // objective function elements 00699 float J_11or24, J_12or23, J_13or22, J_14or21, J_32, J_33; // objective function Jacobian elements 00700 float SEqHatDot_1, SEqHatDot_2, SEqHatDot_3, SEqHatDot_4; // estimated direction of the gyroscope error 00701 00702 // Axulirary variables to avoid reapeated calcualtions 00703 float halfSEq_1 = 0.5f * q1; 00704 float halfSEq_2 = 0.5f * q2; 00705 float halfSEq_3 = 0.5f * q3; 00706 float halfSEq_4 = 0.5f * q4; 00707 float twoSEq_1 = 2.0f * q1; 00708 float twoSEq_2 = 2.0f * q2; 00709 float twoSEq_3 = 2.0f * q3; 00710 00711 // Normalise the accelerometer measurement 00712 norm = sqrt(ax * ax + ay * ay + az * az); 00713 ax /= norm; 00714 ay /= norm; 00715 az /= norm; 00716 00717 // Compute the objective function and Jacobian 00718 f_1 = twoSEq_2 * q4 - twoSEq_1 * q3 - ax; 00719 f_2 = twoSEq_1 * q2 + twoSEq_3 * q4 - ay; 00720 f_3 = 1.0f - twoSEq_2 * q2 - twoSEq_3 * q3 - az; 00721 J_11or24 = twoSEq_3; // J_11 negated in matrix multiplication 00722 J_12or23 = 2.0f * q4; 00723 J_13or22 = twoSEq_1; // J_12 negated in matrix multiplication 00724 J_14or21 = twoSEq_2; 00725 J_32 = 2.0f * J_14or21; // negated in matrix multiplication 00726 J_33 = 2.0f * J_11or24; // negated in matrix multiplication 00727 00728 // Compute the gradient (matrix multiplication) 00729 SEqHatDot_1 = J_14or21 * f_2 - J_11or24 * f_1; 00730 SEqHatDot_2 = J_12or23 * f_1 + J_13or22 * f_2 - J_32 * f_3; 00731 SEqHatDot_3 = J_12or23 * f_2 - J_33 * f_3 - J_13or22 * f_1; 00732 SEqHatDot_4 = J_14or21 * f_1 + J_11or24 * f_2; 00733 00734 // Normalise the gradient 00735 norm = sqrt(SEqHatDot_1 * SEqHatDot_1 + SEqHatDot_2 * SEqHatDot_2 + SEqHatDot_3 * SEqHatDot_3 + SEqHatDot_4 * SEqHatDot_4); 00736 SEqHatDot_1 /= norm; 00737 SEqHatDot_2 /= norm; 00738 SEqHatDot_3 /= norm; 00739 SEqHatDot_4 /= norm; 00740 00741 // Compute the quaternion derrivative measured by gyroscopes 00742 SEqDot_omega_1 = -halfSEq_2 * wx - halfSEq_3 * wy - halfSEq_4 * wz; 00743 SEqDot_omega_2 = halfSEq_1 * wx + halfSEq_3 * wz - halfSEq_4 * wy; 00744 SEqDot_omega_3 = halfSEq_1 * wy - halfSEq_2 * wz + halfSEq_4 * wx; 00745 SEqDot_omega_4 = halfSEq_1 * wz + halfSEq_2 * wy - halfSEq_3 * wx; 00746 00747 // Compute then integrate the estimated quaternion derrivative 00748 q1 += (SEqDot_omega_1 - (beta * SEqHatDot_1)) * delt_t; 00749 q2 += (SEqDot_omega_2 - (beta * SEqHatDot_2)) * delt_t; 00750 q3 += (SEqDot_omega_3 - (beta * SEqHatDot_3)) * delt_t; 00751 q4 += (SEqDot_omega_4 - (beta * SEqHatDot_4)) * delt_t; 00752 00753 // Normalise quaternion 00754 norm = sqrt(q1 * q1 + q2 * q2 + q3 * q3 + q4 * q4); 00755 q1 /= norm; 00756 q2 /= norm; 00757 q3 /= norm; 00758 q4 /= norm; 00759 00760 } 00761 00762 00763 00764 // Similar to Madgwick scheme but uses proportional and integral filtering on the error between estimated reference vectors and 00765 // measured ones. 00766 /* 00767 void MahonyQuaternionUpdate(float ax, float ay, float az, float gx, float gy, float gz, float mx, float my, float mz) 00768 { 00769 float q1 = q[0], q2 = q[1], q3 = q[2], q4 = q[3]; // short name local variable for readability 00770 float norm; 00771 float hx, hy, bx, bz; 00772 float vx, vy, vz, wx, wy, wz; 00773 float ex, ey, ez; 00774 float pa, pb, pc; 00775 00776 // Auxiliary variables to avoid repeated arithmetic 00777 float q1q1 = q1 * q1; 00778 float q1q2 = q1 * q2; 00779 float q1q3 = q1 * q3; 00780 float q1q4 = q1 * q4; 00781 float q2q2 = q2 * q2; 00782 float q2q3 = q2 * q3; 00783 float q2q4 = q2 * q4; 00784 float q3q3 = q3 * q3; 00785 float q3q4 = q3 * q4; 00786 float q4q4 = q4 * q4; 00787 00788 // Normalise accelerometer measurement 00789 norm = sqrt(ax * ax + ay * ay + az * az); 00790 if (norm == 0.0f) return; // handle NaN 00791 norm = 1.0f / norm; // use reciprocal for division 00792 ax *= norm; 00793 ay *= norm; 00794 az *= norm; 00795 00796 // Normalise magnetometer measurement 00797 norm = sqrt(mx * mx + my * my + mz * mz); 00798 if (norm == 0.0f) return; // handle NaN 00799 norm = 1.0f / norm; // use reciprocal for division 00800 mx *= norm; 00801 my *= norm; 00802 mz *= norm; 00803 00804 // Reference direction of Earth's magnetic field 00805 hx = 2.0f * mx * (0.5f - q3q3 - q4q4) + 2.0f * my * (q2q3 - q1q4) + 2.0f * mz * (q2q4 + q1q3); 00806 hy = 2.0f * mx * (q2q3 + q1q4) + 2.0f * my * (0.5f - q2q2 - q4q4) + 2.0f * mz * (q3q4 - q1q2); 00807 bx = sqrt((hx * hx) + (hy * hy)); 00808 bz = 2.0f * mx * (q2q4 - q1q3) + 2.0f * my * (q3q4 + q1q2) + 2.0f * mz * (0.5f - q2q2 - q3q3); 00809 00810 // Estimated direction of gravity and magnetic field 00811 vx = 2.0f * (q2q4 - q1q3); 00812 vy = 2.0f * (q1q2 + q3q4); 00813 vz = q1q1 - q2q2 - q3q3 + q4q4; 00814 wx = 2.0f * bx * (0.5f - q3q3 - q4q4) + 2.0f * bz * (q2q4 - q1q3); 00815 wy = 2.0f * bx * (q2q3 - q1q4) + 2.0f * bz * (q1q2 + q3q4); 00816 wz = 2.0f * bx * (q1q3 + q2q4) + 2.0f * bz * (0.5f - q2q2 - q3q3); 00817 00818 // Error is cross product between estimated direction and measured direction of gravity 00819 ex = (ay * vz - az * vy) + (my * wz - mz * wy); 00820 ey = (az * vx - ax * vz) + (mz * wx - mx * wz); 00821 ez = (ax * vy - ay * vx) + (mx * wy - my * wx); 00822 if (Ki > 0.0f) 00823 { 00824 eInt[0] += ex; // accumulate integral error 00825 eInt[1] += ey; 00826 eInt[2] += ez; 00827 } 00828 else 00829 { 00830 eInt[0] = 0.0f; // prevent integral wind up 00831 eInt[1] = 0.0f; 00832 eInt[2] = 0.0f; 00833 } 00834 00835 // Apply feedback terms 00836 gx = gx + Kp * ex + Ki * eInt[0]; 00837 gy = gy + Kp * ey + Ki * eInt[1]; 00838 gz = gz + Kp * ez + Ki * eInt[2]; 00839 00840 // Integrate rate of change of quaternion 00841 pa = q2; 00842 pb = q3; 00843 pc = q4; 00844 q1 = q1 + (-q2 * gx - q3 * gy - q4 * gz) * (0.5f * delt_t); 00845 q2 = pa + (q1 * gx + pb * gz - pc * gy) * (0.5f * delt_t); 00846 q3 = pb + (q1 * gy - pa * gz + pc * gx) * (0.5f * delt_t); 00847 q4 = pc + (q1 * gz + pa * gy - pb * gx) * (0.5f * delt_t); 00848 00849 // Normalise quaternion 00850 norm = sqrt(q1 * q1 + q2 * q2 + q3 * q3 + q4 * q4); 00851 norm = 1.0f / norm; 00852 q[0] = q1 * norm; 00853 q[1] = q2 * norm; 00854 q[2] = q3 * norm; 00855 q[3] = q4 * norm; 00856 00857 } 00858 */ 00859 }; 00860 #endif
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