mirror of https://github.com/ArduPilot/ardupilot
137 lines
4.3 KiB
C++
137 lines
4.3 KiB
C++
#include <AP_HAL/AP_HAL.h>
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#include <AP_Vehicle/AP_Vehicle_Type.h>
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#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
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#include "AP_Baro_SITL.h"
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extern const AP_HAL::HAL& hal;
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/*
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constructor - registers instance at top Baro driver
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*/
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AP_Baro_SITL::AP_Baro_SITL(AP_Baro &baro) :
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_has_sample(false),
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AP_Baro_Backend(baro)
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{
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_sitl = (SITL::SITL *)AP_Param::find_object("SIM_");
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if (_sitl != nullptr) {
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_instance = _frontend.register_sensor();
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#if APM_BUILD_TYPE(APM_BUILD_ArduSub)
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_frontend.set_type(_instance, AP_Baro::BARO_TYPE_WATER);
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#endif
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hal.scheduler->register_timer_process(FUNCTOR_BIND(this, &AP_Baro_SITL::_timer, void));
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}
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}
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// adjust for board temperature
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void AP_Baro_SITL::temperature_adjustment(float &p, float &T)
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{
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const float tsec = AP_HAL::millis() * 0.001f;
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const float T0 = _sitl->temp_start;
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const float T1 = _sitl->temp_flight;
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const float tconst = _sitl->temp_tconst;
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const float baro_factor = _sitl->temp_baro_factor;
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const float Tzero = 30.0f; // start baro adjustment at 30C
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T = T1 - (T1 - T0) * expf(-tsec / tconst);
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if (is_positive(baro_factor)) {
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// this produces a pressure change with temperature that
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// closely matches what has been observed with a ICM-20789
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// barometer. A typical factor is 1.2.
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p -= powf(MAX(T - Tzero, 0), baro_factor);
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}
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}
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void AP_Baro_SITL::_timer()
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{
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// 100Hz
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const uint32_t now = AP_HAL::millis();
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if ((now - _last_sample_time) < 10) {
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return;
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}
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_last_sample_time = now;
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float sim_alt = _sitl->state.altitude;
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if (_sitl->baro_disable) {
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// barometer is disabled
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return;
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}
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sim_alt += _sitl->baro_drift * now / 1000.0f;
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sim_alt += _sitl->baro_noise * rand_float();
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// add baro glitch
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sim_alt += _sitl->baro_glitch;
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// add delay
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uint32_t best_time_delta = 200; // initialise large time representing buffer entry closest to current time - delay.
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uint8_t best_index = 0; // initialise number representing the index of the entry in buffer closest to delay.
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// storing data from sensor to buffer
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if (now - _last_store_time >= 10) { // store data every 10 ms.
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_last_store_time = now;
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if (_store_index > _buffer_length - 1) { // reset buffer index if index greater than size of buffer
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_store_index = 0;
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}
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_buffer[_store_index].data = sim_alt; // add data to current index
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_buffer[_store_index].time = _last_store_time; // add time_stamp to current index
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_store_index = _store_index + 1; // increment index
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}
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// return delayed measurement
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const uint32_t delayed_time = now - _sitl->baro_delay; // get time corresponding to delay
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// find data corresponding to delayed time in buffer
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for (uint8_t i = 0; i <= _buffer_length - 1; i++) {
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// find difference between delayed time and time stamp in buffer
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uint32_t time_delta = abs(
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(int32_t)(delayed_time - _buffer[i].time));
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// if this difference is smaller than last delta, store this time
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if (time_delta < best_time_delta) {
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best_index = i;
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best_time_delta = time_delta;
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}
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}
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if (best_time_delta < 200) { // only output stored state if < 200 msec retrieval error
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sim_alt = _buffer[best_index].data;
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}
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#if !APM_BUILD_TYPE(APM_BUILD_ArduSub)
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float sigma, delta, theta;
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AP_Baro::SimpleAtmosphere(sim_alt * 0.001f, sigma, delta, theta);
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float p = SSL_AIR_PRESSURE * delta;
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float T = 303.16f * theta - C_TO_KELVIN; // Assume 30 degrees at sea level - converted to degrees Kelvin
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temperature_adjustment(p, T);
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#else
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float rho, delta, theta;
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AP_Baro::SimpleUnderWaterAtmosphere(-sim_alt * 0.001f, rho, delta, theta);
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float p = SSL_AIR_PRESSURE * delta;
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float T = 303.16f * theta - C_TO_KELVIN; // Assume 30 degrees at sea level - converted to degrees Kelvin
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#endif
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_recent_press = p;
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_recent_temp = T;
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_has_sample = true;
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}
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// Read the sensor
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void AP_Baro_SITL::update(void)
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{
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if (_sem->take_nonblocking()) {
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if (!_has_sample) {
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_sem->give();
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return;
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}
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_copy_to_frontend(_instance, _recent_press, _recent_temp);
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_has_sample = false;
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_sem->give();
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}
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}
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#endif // CONFIG_HAL_BOARD
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