ohararp
/
IMUFilter_9DOF-Stick_RY
main.cpp@0:d536780893d9, 2012-06-08 (annotated)
- Committer:
- ohararp
- Date:
- Fri Jun 08 13:42:48 2012 +0000
- Revision:
- 0:d536780893d9
Example Code modified to run with Sparkfun 9DOF stick
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
ohararp | 0:d536780893d9 | 1 | #include "mbed.h" |
ohararp | 0:d536780893d9 | 2 | #include "HMC5843.h" |
ohararp | 0:d536780893d9 | 3 | #include "ADXL345.h" |
ohararp | 0:d536780893d9 | 4 | #include "ITG3200.h" |
ohararp | 0:d536780893d9 | 5 | #include "IMUfilter.h" |
ohararp | 0:d536780893d9 | 6 | |
ohararp | 0:d536780893d9 | 7 | //Gravity at Earth's surface in m/s/s |
ohararp | 0:d536780893d9 | 8 | #define g0 9.812865328 |
ohararp | 0:d536780893d9 | 9 | //Number of samples to average. |
ohararp | 0:d536780893d9 | 10 | #define SAMPLES 4 |
ohararp | 0:d536780893d9 | 11 | //Number of samples to be averaged for a null bias calculation |
ohararp | 0:d536780893d9 | 12 | //during calibration. |
ohararp | 0:d536780893d9 | 13 | #define CALIBRATION_SAMPLES 128 |
ohararp | 0:d536780893d9 | 14 | //Convert from radians to degrees. |
ohararp | 0:d536780893d9 | 15 | #define toDegrees(x) (x * 57.2957795) |
ohararp | 0:d536780893d9 | 16 | //Convert from degrees to radians. |
ohararp | 0:d536780893d9 | 17 | #define toRadians(x) (x * 0.01745329252) |
ohararp | 0:d536780893d9 | 18 | //ITG-3200 sensitivity is 14.375 LSB/(degrees/sec). |
ohararp | 0:d536780893d9 | 19 | #define GYROSCOPE_GAIN (1 / 14.375) |
ohararp | 0:d536780893d9 | 20 | //Full scale resolution on the ADXL345 is 4mg/LSB. |
ohararp | 0:d536780893d9 | 21 | #define ACCELEROMETER_GAIN (0.004 * g0) |
ohararp | 0:d536780893d9 | 22 | //Sampling gyroscope at 200Hz. |
ohararp | 0:d536780893d9 | 23 | #define GYRO_RATE 0.005 |
ohararp | 0:d536780893d9 | 24 | //Sampling accelerometer at 200Hz. |
ohararp | 0:d536780893d9 | 25 | #define ACC_RATE 0.005 |
ohararp | 0:d536780893d9 | 26 | //Updating filter at 40Hz. |
ohararp | 0:d536780893d9 | 27 | #define FILTER_RATE 0.1 |
ohararp | 0:d536780893d9 | 28 | |
ohararp | 0:d536780893d9 | 29 | DigitalOut myled(LED1); |
ohararp | 0:d536780893d9 | 30 | HMC5843 cmp(p28, p27); // sda, scl |
ohararp | 0:d536780893d9 | 31 | ADXL345 acc(p28, p27); // sda, scl |
ohararp | 0:d536780893d9 | 32 | ITG3200 gyr(p28, p27); // sda, scl |
ohararp | 0:d536780893d9 | 33 | Serial pc(USBTX, USBRX); // tx, rx |
ohararp | 0:d536780893d9 | 34 | |
ohararp | 0:d536780893d9 | 35 | // Init Tickers for IMU Filter Sampling |
ohararp | 0:d536780893d9 | 36 | Ticker accelerometerTicker; |
ohararp | 0:d536780893d9 | 37 | Ticker gyroscopeTicker; |
ohararp | 0:d536780893d9 | 38 | Ticker filterTicker; |
ohararp | 0:d536780893d9 | 39 | |
ohararp | 0:d536780893d9 | 40 | //At rest the gyroscope is centred around 0 and goes between about |
ohararp | 0:d536780893d9 | 41 | //-5 and 5 counts. As 1 degrees/sec is ~15 LSB, error is roughly |
ohararp | 0:d536780893d9 | 42 | //5/15 = 0.3 degrees/sec. |
ohararp | 0:d536780893d9 | 43 | IMUfilter imuFilter(FILTER_RATE, 0.3); |
ohararp | 0:d536780893d9 | 44 | |
ohararp | 0:d536780893d9 | 45 | //Offsets for the gyroscope. |
ohararp | 0:d536780893d9 | 46 | //The readings we take when the gyroscope is stationary won't be 0, so we'll |
ohararp | 0:d536780893d9 | 47 | //average a set of readings we do get when the gyroscope is stationary and |
ohararp | 0:d536780893d9 | 48 | //take those away from subsequent readings to ensure the gyroscope is offset |
ohararp | 0:d536780893d9 | 49 | //or "biased" to 0. |
ohararp | 0:d536780893d9 | 50 | double w_xBias; |
ohararp | 0:d536780893d9 | 51 | double w_yBias; |
ohararp | 0:d536780893d9 | 52 | double w_zBias; |
ohararp | 0:d536780893d9 | 53 | |
ohararp | 0:d536780893d9 | 54 | //Offsets for the acc. |
ohararp | 0:d536780893d9 | 55 | //Same as with the gyroscope. |
ohararp | 0:d536780893d9 | 56 | double a_xBias; |
ohararp | 0:d536780893d9 | 57 | double a_yBias; |
ohararp | 0:d536780893d9 | 58 | double a_zBias; |
ohararp | 0:d536780893d9 | 59 | |
ohararp | 0:d536780893d9 | 60 | //Accumulators used for oversampling and then averaging. |
ohararp | 0:d536780893d9 | 61 | volatile double a_xAccumulator = 0; |
ohararp | 0:d536780893d9 | 62 | volatile double a_yAccumulator = 0; |
ohararp | 0:d536780893d9 | 63 | volatile double a_zAccumulator = 0; |
ohararp | 0:d536780893d9 | 64 | volatile double w_xAccumulator = 0; |
ohararp | 0:d536780893d9 | 65 | volatile double w_yAccumulator = 0; |
ohararp | 0:d536780893d9 | 66 | volatile double w_zAccumulator = 0; |
ohararp | 0:d536780893d9 | 67 | |
ohararp | 0:d536780893d9 | 68 | //Accelerometer and gyroscope readings for x, y, z axes. |
ohararp | 0:d536780893d9 | 69 | volatile double a_x; |
ohararp | 0:d536780893d9 | 70 | volatile double a_y; |
ohararp | 0:d536780893d9 | 71 | volatile double a_z; |
ohararp | 0:d536780893d9 | 72 | volatile double w_x; |
ohararp | 0:d536780893d9 | 73 | volatile double w_y; |
ohararp | 0:d536780893d9 | 74 | volatile double w_z; |
ohararp | 0:d536780893d9 | 75 | |
ohararp | 0:d536780893d9 | 76 | //Buffer for accelerometer readings. |
ohararp | 0:d536780893d9 | 77 | int readings[3]; |
ohararp | 0:d536780893d9 | 78 | //Number of accelerometer samples we're on. |
ohararp | 0:d536780893d9 | 79 | int accelerometerSamples = 0; |
ohararp | 0:d536780893d9 | 80 | //Number of gyroscope samples we're on. |
ohararp | 0:d536780893d9 | 81 | int gyroscopeSamples = 0; |
ohararp | 0:d536780893d9 | 82 | |
ohararp | 0:d536780893d9 | 83 | void initializeAccelerometer(void) { |
ohararp | 0:d536780893d9 | 84 | // Get Acc Id |
ohararp | 0:d536780893d9 | 85 | pc.printf("Acc Id=%x \n", acc.getDeviceID()); |
ohararp | 0:d536780893d9 | 86 | //Go into standby mode to configure the device. |
ohararp | 0:d536780893d9 | 87 | acc.setPowerControl(0x00); |
ohararp | 0:d536780893d9 | 88 | //Full resolution, +/-16g, 4mg/LSB. |
ohararp | 0:d536780893d9 | 89 | acc.setDataFormatControl(0x0B); |
ohararp | 0:d536780893d9 | 90 | //200Hz data rate. |
ohararp | 0:d536780893d9 | 91 | acc.setDataRate(ADXL345_200HZ); |
ohararp | 0:d536780893d9 | 92 | //Measurement mode. |
ohararp | 0:d536780893d9 | 93 | acc.setPowerControl(0x08); |
ohararp | 0:d536780893d9 | 94 | //See http://www.analog.com/static/imported-files/application_notes/AN-1077.pdf |
ohararp | 0:d536780893d9 | 95 | wait_ms(22); |
ohararp | 0:d536780893d9 | 96 | } |
ohararp | 0:d536780893d9 | 97 | |
ohararp | 0:d536780893d9 | 98 | void sampleAccelerometer(void) { |
ohararp | 0:d536780893d9 | 99 | //Have we taken enough samples? |
ohararp | 0:d536780893d9 | 100 | if (accelerometerSamples == SAMPLES) { |
ohararp | 0:d536780893d9 | 101 | |
ohararp | 0:d536780893d9 | 102 | //Average the samples, remove the bias, and calculate the acceleration |
ohararp | 0:d536780893d9 | 103 | //in m/s/s. |
ohararp | 0:d536780893d9 | 104 | a_x = ((a_xAccumulator / SAMPLES) - a_xBias) * ACCELEROMETER_GAIN; |
ohararp | 0:d536780893d9 | 105 | a_y = ((a_yAccumulator / SAMPLES) - a_yBias) * ACCELEROMETER_GAIN; |
ohararp | 0:d536780893d9 | 106 | a_z = ((a_zAccumulator / SAMPLES) - a_zBias) * ACCELEROMETER_GAIN; |
ohararp | 0:d536780893d9 | 107 | |
ohararp | 0:d536780893d9 | 108 | a_xAccumulator = 0; |
ohararp | 0:d536780893d9 | 109 | a_yAccumulator = 0; |
ohararp | 0:d536780893d9 | 110 | a_zAccumulator = 0; |
ohararp | 0:d536780893d9 | 111 | accelerometerSamples = 0; |
ohararp | 0:d536780893d9 | 112 | |
ohararp | 0:d536780893d9 | 113 | } else { |
ohararp | 0:d536780893d9 | 114 | //Take another sample. |
ohararp | 0:d536780893d9 | 115 | acc.getOutput(readings); |
ohararp | 0:d536780893d9 | 116 | |
ohararp | 0:d536780893d9 | 117 | a_xAccumulator += (int16_t) readings[0]; |
ohararp | 0:d536780893d9 | 118 | a_yAccumulator += (int16_t) readings[1]; |
ohararp | 0:d536780893d9 | 119 | a_zAccumulator += (int16_t) readings[2]; |
ohararp | 0:d536780893d9 | 120 | |
ohararp | 0:d536780893d9 | 121 | accelerometerSamples++; |
ohararp | 0:d536780893d9 | 122 | } |
ohararp | 0:d536780893d9 | 123 | } |
ohararp | 0:d536780893d9 | 124 | |
ohararp | 0:d536780893d9 | 125 | void calibrateAccelerometer(void) { |
ohararp | 0:d536780893d9 | 126 | a_xAccumulator = 0; |
ohararp | 0:d536780893d9 | 127 | a_yAccumulator = 0; |
ohararp | 0:d536780893d9 | 128 | a_zAccumulator = 0; |
ohararp | 0:d536780893d9 | 129 | |
ohararp | 0:d536780893d9 | 130 | //Take a number of readings and average them |
ohararp | 0:d536780893d9 | 131 | //to calculate the zero g offset. |
ohararp | 0:d536780893d9 | 132 | for (int i = 0; i < CALIBRATION_SAMPLES; i++) { |
ohararp | 0:d536780893d9 | 133 | |
ohararp | 0:d536780893d9 | 134 | acc.getOutput(readings); |
ohararp | 0:d536780893d9 | 135 | |
ohararp | 0:d536780893d9 | 136 | a_xAccumulator += (int16_t) readings[0]; |
ohararp | 0:d536780893d9 | 137 | a_yAccumulator += (int16_t) readings[1]; |
ohararp | 0:d536780893d9 | 138 | a_zAccumulator += (int16_t) readings[2]; |
ohararp | 0:d536780893d9 | 139 | |
ohararp | 0:d536780893d9 | 140 | wait(ACC_RATE); |
ohararp | 0:d536780893d9 | 141 | |
ohararp | 0:d536780893d9 | 142 | } |
ohararp | 0:d536780893d9 | 143 | |
ohararp | 0:d536780893d9 | 144 | a_xAccumulator /= CALIBRATION_SAMPLES; |
ohararp | 0:d536780893d9 | 145 | a_yAccumulator /= CALIBRATION_SAMPLES; |
ohararp | 0:d536780893d9 | 146 | a_zAccumulator /= CALIBRATION_SAMPLES; |
ohararp | 0:d536780893d9 | 147 | |
ohararp | 0:d536780893d9 | 148 | //At 4mg/LSB, 250 LSBs is 1g. |
ohararp | 0:d536780893d9 | 149 | a_xBias = a_xAccumulator; |
ohararp | 0:d536780893d9 | 150 | a_yBias = a_yAccumulator; |
ohararp | 0:d536780893d9 | 151 | a_zBias = (a_zAccumulator - 250); |
ohararp | 0:d536780893d9 | 152 | |
ohararp | 0:d536780893d9 | 153 | a_xAccumulator = 0; |
ohararp | 0:d536780893d9 | 154 | a_yAccumulator = 0; |
ohararp | 0:d536780893d9 | 155 | a_zAccumulator = 0; |
ohararp | 0:d536780893d9 | 156 | } |
ohararp | 0:d536780893d9 | 157 | |
ohararp | 0:d536780893d9 | 158 | void initializeGyroscope(void) { |
ohararp | 0:d536780893d9 | 159 | //Get Gyro ID |
ohararp | 0:d536780893d9 | 160 | pc.printf("Gyro Id=%x \n", gyr.getWhoAmI()); |
ohararp | 0:d536780893d9 | 161 | //Low pass filter bandwidth of 42Hz. |
ohararp | 0:d536780893d9 | 162 | gyr.setLpBandwidth(LPFBW_42HZ); |
ohararp | 0:d536780893d9 | 163 | //Internal sample rate of 200Hz. (1kHz / 5). |
ohararp | 0:d536780893d9 | 164 | gyr.setSampleRateDivider(4); |
ohararp | 0:d536780893d9 | 165 | } |
ohararp | 0:d536780893d9 | 166 | |
ohararp | 0:d536780893d9 | 167 | void calibrateGyroscope(void) { |
ohararp | 0:d536780893d9 | 168 | w_xAccumulator = 0; |
ohararp | 0:d536780893d9 | 169 | w_yAccumulator = 0; |
ohararp | 0:d536780893d9 | 170 | w_zAccumulator = 0; |
ohararp | 0:d536780893d9 | 171 | |
ohararp | 0:d536780893d9 | 172 | //Take a number of readings and average them |
ohararp | 0:d536780893d9 | 173 | //to calculate the gyroscope bias offset. |
ohararp | 0:d536780893d9 | 174 | for (int i = 0; i < CALIBRATION_SAMPLES; i++) { |
ohararp | 0:d536780893d9 | 175 | |
ohararp | 0:d536780893d9 | 176 | w_xAccumulator += gyr.getGyroX(); |
ohararp | 0:d536780893d9 | 177 | w_yAccumulator += gyr.getGyroY(); |
ohararp | 0:d536780893d9 | 178 | w_zAccumulator += gyr.getGyroZ(); |
ohararp | 0:d536780893d9 | 179 | wait(GYRO_RATE); |
ohararp | 0:d536780893d9 | 180 | |
ohararp | 0:d536780893d9 | 181 | } |
ohararp | 0:d536780893d9 | 182 | |
ohararp | 0:d536780893d9 | 183 | //Average the samples. |
ohararp | 0:d536780893d9 | 184 | w_xAccumulator /= CALIBRATION_SAMPLES; |
ohararp | 0:d536780893d9 | 185 | w_yAccumulator /= CALIBRATION_SAMPLES; |
ohararp | 0:d536780893d9 | 186 | w_zAccumulator /= CALIBRATION_SAMPLES; |
ohararp | 0:d536780893d9 | 187 | |
ohararp | 0:d536780893d9 | 188 | w_xBias = w_xAccumulator; |
ohararp | 0:d536780893d9 | 189 | w_yBias = w_yAccumulator; |
ohararp | 0:d536780893d9 | 190 | w_zBias = w_zAccumulator; |
ohararp | 0:d536780893d9 | 191 | |
ohararp | 0:d536780893d9 | 192 | w_xAccumulator = 0; |
ohararp | 0:d536780893d9 | 193 | w_yAccumulator = 0; |
ohararp | 0:d536780893d9 | 194 | w_zAccumulator = 0; |
ohararp | 0:d536780893d9 | 195 | } |
ohararp | 0:d536780893d9 | 196 | |
ohararp | 0:d536780893d9 | 197 | void sampleGyroscope(void) { |
ohararp | 0:d536780893d9 | 198 | //Have we taken enough samples? |
ohararp | 0:d536780893d9 | 199 | if (gyroscopeSamples == SAMPLES) { |
ohararp | 0:d536780893d9 | 200 | //Average the samples, remove the bias, and calculate the angular |
ohararp | 0:d536780893d9 | 201 | //velocity in rad/s. |
ohararp | 0:d536780893d9 | 202 | w_x = toRadians(((w_xAccumulator / SAMPLES) - w_xBias) * GYROSCOPE_GAIN); |
ohararp | 0:d536780893d9 | 203 | w_y = toRadians(((w_yAccumulator / SAMPLES) - w_yBias) * GYROSCOPE_GAIN); |
ohararp | 0:d536780893d9 | 204 | w_z = toRadians(((w_zAccumulator / SAMPLES) - w_zBias) * GYROSCOPE_GAIN); |
ohararp | 0:d536780893d9 | 205 | |
ohararp | 0:d536780893d9 | 206 | w_xAccumulator = 0; |
ohararp | 0:d536780893d9 | 207 | w_yAccumulator = 0; |
ohararp | 0:d536780893d9 | 208 | w_zAccumulator = 0; |
ohararp | 0:d536780893d9 | 209 | gyroscopeSamples = 0; |
ohararp | 0:d536780893d9 | 210 | } else { |
ohararp | 0:d536780893d9 | 211 | //Take another sample. |
ohararp | 0:d536780893d9 | 212 | w_xAccumulator += gyr.getGyroX(); |
ohararp | 0:d536780893d9 | 213 | w_yAccumulator += gyr.getGyroY(); |
ohararp | 0:d536780893d9 | 214 | w_zAccumulator += gyr.getGyroZ(); |
ohararp | 0:d536780893d9 | 215 | gyroscopeSamples++; |
ohararp | 0:d536780893d9 | 216 | } |
ohararp | 0:d536780893d9 | 217 | } |
ohararp | 0:d536780893d9 | 218 | |
ohararp | 0:d536780893d9 | 219 | void filter(void) { |
ohararp | 0:d536780893d9 | 220 | //Update the filter variables. |
ohararp | 0:d536780893d9 | 221 | imuFilter.updateFilter(w_y, w_x, w_z, a_y, a_x, a_z); |
ohararp | 0:d536780893d9 | 222 | //Calculate the new Euler angles. |
ohararp | 0:d536780893d9 | 223 | imuFilter.computeEuler(); |
ohararp | 0:d536780893d9 | 224 | } |
ohararp | 0:d536780893d9 | 225 | |
ohararp | 0:d536780893d9 | 226 | int main() { |
ohararp | 0:d536780893d9 | 227 | pc.baud(115200); // Baudrate |
ohararp | 0:d536780893d9 | 228 | pc.printf("Starting IMU filter test...\n"); |
ohararp | 0:d536780893d9 | 229 | |
ohararp | 0:d536780893d9 | 230 | //Initialize inertial sensors. |
ohararp | 0:d536780893d9 | 231 | initializeAccelerometer(); |
ohararp | 0:d536780893d9 | 232 | calibrateAccelerometer(); |
ohararp | 0:d536780893d9 | 233 | initializeGyroscope(); |
ohararp | 0:d536780893d9 | 234 | calibrateGyroscope(); |
ohararp | 0:d536780893d9 | 235 | |
ohararp | 0:d536780893d9 | 236 | |
ohararp | 0:d536780893d9 | 237 | //Set up timers. |
ohararp | 0:d536780893d9 | 238 | //Accelerometer data rate is 200Hz, so we'll sample at this speed. |
ohararp | 0:d536780893d9 | 239 | accelerometerTicker.attach(&sampleAccelerometer, 0.005); |
ohararp | 0:d536780893d9 | 240 | //Gyroscope data rate is 200Hz, so we'll sample at this speed. |
ohararp | 0:d536780893d9 | 241 | gyroscopeTicker.attach(&sampleGyroscope, 0.005); |
ohararp | 0:d536780893d9 | 242 | //Update the filter variables at the correct rate. |
ohararp | 0:d536780893d9 | 243 | filterTicker.attach(&filter, FILTER_RATE); |
ohararp | 0:d536780893d9 | 244 | |
ohararp | 0:d536780893d9 | 245 | while (1) { |
ohararp | 0:d536780893d9 | 246 | |
ohararp | 0:d536780893d9 | 247 | wait(FILTER_RATE); |
ohararp | 0:d536780893d9 | 248 | |
ohararp | 0:d536780893d9 | 249 | pc.printf("%f,%f,%f\n",toDegrees(imuFilter.getRoll()), |
ohararp | 0:d536780893d9 | 250 | toDegrees(imuFilter.getPitch()), |
ohararp | 0:d536780893d9 | 251 | toDegrees(imuFilter.getYaw())); |
ohararp | 0:d536780893d9 | 252 | |
ohararp | 0:d536780893d9 | 253 | if (myled) { |
ohararp | 0:d536780893d9 | 254 | myled=0; |
ohararp | 0:d536780893d9 | 255 | } else { |
ohararp | 0:d536780893d9 | 256 | myled=1; |
ohararp | 0:d536780893d9 | 257 | } |
ohararp | 0:d536780893d9 | 258 | } |
ohararp | 0:d536780893d9 | 259 | } |