mirror of https://github.com/ArduPilot/ardupilot
IMU: re-work the IMU library to take advantage of the ADC Ch6() call
This changes the IMU code to read 6 synchronised ADC channels at one time, giving us matching values, and exposing the exact averaging time to callers
This commit is contained in:
Andrew Tridgell
parent
8a31af801f
commit
bb35fdec10
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@ -77,6 +77,7 @@ AP_IMU_Oilpan::_init_gyro(void (*callback)(unsigned long t))
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float prev[3] = {0,0,0};
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float total_change;
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float max_offset;
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uint16_t adc_values[6];
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// cold start
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tc_temp = _adc->Ch(_gyro_temp_ch);
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@ -88,8 +89,7 @@ AP_IMU_Oilpan::_init_gyro(void (*callback)(unsigned long t))
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digitalWrite(C_LED_PIN, HIGH);
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callback(20);
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for (int i = 0; i < 6; i++)
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adc_in = _adc->Ch(_sensors[i]);
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_adc->Ch6(_sensors, adc_values);
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digitalWrite(A_LED_PIN, HIGH);
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digitalWrite(C_LED_PIN, LOW);
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@ -100,16 +100,23 @@ AP_IMU_Oilpan::_init_gyro(void (*callback)(unsigned long t))
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_sensor_cal[j] = 500; // Just a large value to load prev[j] the first time
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do {
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// get 6 sensor values
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_adc->Ch6(_sensors, adc_values);
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for (int j = 0; j <= 2; j++){
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prev[j] = _sensor_cal[j];
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adc_in = _adc->Ch(_sensors[j]);
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adc_in = adc_values[j];
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adc_in -= _sensor_compensation(j, tc_temp);
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_sensor_cal[j] = adc_in;
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}
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for(int i = 0; i < 50; i++){
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// get 6 sensor values
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_adc->Ch6(_sensors, adc_values);
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for (int j = 0; j < 3; j++){
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adc_in = _adc->Ch(_sensors[j]);
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adc_in = adc_values[j];
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// Subtract temp compensated typical gyro bias
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adc_in -= _sensor_compensation(j, tc_temp);
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// filter
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@ -159,6 +166,7 @@ AP_IMU_Oilpan::_init_accel(void (*callback)(unsigned long t))
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float prev[6] = {0,0,0};
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float total_change;
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float max_offset;
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uint16_t adc_values[6];
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// cold start
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callback(500);
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@ -168,9 +176,11 @@ AP_IMU_Oilpan::_init_accel(void (*callback)(unsigned long t))
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for (int j=3; j<=5; j++) _sensor_cal[j] = 500; // Just a large value to load prev[j] the first time
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do {
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_adc->Ch6(_sensors, adc_values);
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for (int j = 3; j <= 5; j++){
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prev[j] = _sensor_cal[j];
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adc_in = _adc->Ch(_sensors[j]);
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adc_in = adc_values[j];
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adc_in -= _sensor_compensation(j, 0); // temperature ignored
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_sensor_cal[j] = adc_in;
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}
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@ -179,8 +189,10 @@ AP_IMU_Oilpan::_init_accel(void (*callback)(unsigned long t))
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callback(20);
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_adc->Ch6(_sensors, adc_values);
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for (int j = 3; j < 6; j++){
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adc_in = _adc->Ch(_sensors[j]);
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adc_in = adc_values[j];
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adc_in -= _sensor_compensation(j, 0); // temperature ignored
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_sensor_cal[j] = _sensor_cal[j] * 0.9 + adc_in * 0.1;
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}
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@ -222,7 +234,7 @@ AP_IMU_Oilpan::_sensor_compensation(uint8_t channel, int temperature) const
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// do gyro temperature compensation
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if (channel < 3) {
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return 1658;
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return 1658.0;
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/*
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return _gyro_temp_curve[channel][0] +
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_gyro_temp_curve[channel][1] * temperature +
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@ -231,17 +243,17 @@ AP_IMU_Oilpan::_sensor_compensation(uint8_t channel, int temperature) const
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}
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// do fixed-offset accelerometer compensation
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return 2041; // Average raw value from a 20 board sample
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return 2041.0; // Average raw value from a 20 board sample
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}
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float
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AP_IMU_Oilpan::_sensor_in(uint8_t channel, int temperature)
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AP_IMU_Oilpan::_sensor_in(uint8_t channel, uint16_t adc_value, int temperature)
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{
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float adc_in;
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// get the compensated sensor value
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//
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adc_in = _adc->Ch(_sensors[channel]) - _sensor_compensation(channel, temperature);
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adc_in = adc_value - _sensor_compensation(channel, temperature);
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// adjust for sensor sign and apply calibration offset
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//
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@ -265,18 +277,21 @@ bool
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AP_IMU_Oilpan::update(void)
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{
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int tc_temp = _adc->Ch(_gyro_temp_ch);
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uint16_t adc_values[6];
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_ticks = _adc->Ch6(_sensors, adc_values);
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// convert corrected gyro readings to delta acceleration
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//
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_gyro.x = ToRad(_gyro_gain_x) * _sensor_in(0, tc_temp);
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_gyro.y = ToRad(_gyro_gain_y) * _sensor_in(1, tc_temp);
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_gyro.z = ToRad(_gyro_gain_z) * _sensor_in(2, tc_temp);
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_gyro.x = _gyro_gain_x * _sensor_in(0, adc_values[0], tc_temp);
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_gyro.y = _gyro_gain_y * _sensor_in(1, adc_values[1], tc_temp);
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_gyro.z = _gyro_gain_z * _sensor_in(2, adc_values[2], tc_temp);
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// convert corrected accelerometer readings to acceleration
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//
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_accel.x = _accel_scale * _sensor_in(3, tc_temp);
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_accel.y = _accel_scale * _sensor_in(4, tc_temp);
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_accel.z = _accel_scale * _sensor_in(5, tc_temp);
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_accel.x = _accel_scale * _sensor_in(3, adc_values[3], tc_temp);
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_accel.y = _accel_scale * _sensor_in(4, adc_values[4], tc_temp);
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_accel.z = _accel_scale * _sensor_in(5, adc_values[5], tc_temp);
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_accel_filtered.x = _accel_filtered.x * .98 + _accel.x * .02;
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_accel_filtered.y = _accel_filtered.y * .98 + _accel.y * .02;
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@ -68,8 +68,8 @@ private:
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virtual void _init_accel(void (*callback)(unsigned long t)); ///< no-save implementation
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virtual void _init_gyro(void (*callback)(unsigned long t)); ///< no-save implementation
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float _sensor_in(uint8_t channel, uint16_t adc_value, int temperature);
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float _sensor_compensation(uint8_t channel, int temp) const;
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float _sensor_in(uint8_t channel, int temperature);
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// constants
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static const uint8_t _sensors[6]; ///< ADC channel mappings for the sensors
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@ -83,14 +83,15 @@ private:
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//
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static const float _gravity = 423.8; ///< 1G in the raw data coming from the accelerometer
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// Value based on actual sample data from 20 boards
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static const float _accel_scale = 9.80665 / 423.8; ///< would like to use _gravity here, but cannot
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// IDG500 Sensitivity (from datasheet) => 2.0mV/degree/s, 0.8mV/ADC step => 0.8/3.33 = 0.4
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// Tested values : 0.4026, ?, 0.4192
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//
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static const float _gyro_gain_x = 0.4; // X axis Gyro gain
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static const float _gyro_gain_y = 0.41; // Y axis Gyro gain
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static const float _gyro_gain_z = 0.41; // Z axis Gyro gain
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static const float _gyro_gain_x = ToRad(0.4); // X axis Gyro gain
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static const float _gyro_gain_y = ToRad(0.41); // Y axis Gyro gain
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static const float _gyro_gain_z = ToRad(0.41); // Z axis Gyro gain
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// Maximum possible value returned by an offset-corrected sensor channel
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//
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@ -70,12 +70,19 @@ public:
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///
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Vector3f get_accel(void) { return _accel; }
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/// Fetch the current accelerometer values
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///
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/// @returns vector of current accelerations in m/s/s
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///
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Vector3f get_accel_filtered(void) { return _accel_filtered; }
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/// return the number of seconds that the last update represents
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///
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/// @returns number of seconds
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///
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float get_delta_time(void) { return _ticks * (2.5/1000.0); }
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/// A count of bad sensor readings
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///
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/// @todo This should be renamed, as there's no guarantee that sensors
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@ -90,6 +97,10 @@ protected:
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/// Most recent gyro reading obtained by ::update
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Vector3f _gyro;
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/// number of 2.5ms ticks that the accel and gyro values
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/// were calculated from
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uint16_t _ticks;
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};
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#endif
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