mirror of https://github.com/ArduPilot/ardupilot
79 lines
2.7 KiB
C++
79 lines
2.7 KiB
C++
/*
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SITL handling
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This simulates an analog airspeed sensor
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Andrew Tridgell November 2011
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*/
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#include <AP_HAL/AP_HAL.h>
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#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
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#include "AP_HAL_SITL.h"
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#include "AP_HAL_SITL_Namespace.h"
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#include "HAL_SITL_Class.h"
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#include "SITL_State.h"
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#include <SITL/SITL.h>
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#include <AP_Math/AP_Math.h>
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extern const AP_HAL::HAL& hal;
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using namespace HALSITL;
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/*
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convert airspeed in m/s to an airspeed sensor value
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*/
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void SITL_State::_update_airspeed(float airspeed)
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{
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const float airspeed_ratio = 1.9936f;
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const float airspeed_offset = 2013.0f;
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// Check sensor failure
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airspeed = is_zero(_sitl->arspd_fail) ? airspeed : _sitl->arspd_fail;
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// Add noise
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airspeed = airspeed + (_sitl->arspd_noise * rand_float());
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const float airspeed_pressure = (airspeed * airspeed) / airspeed_ratio;
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float airspeed_raw = airspeed_pressure + airspeed_offset;
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if (airspeed_raw / 4 > 0xFFFF) {
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airspeed_pin_value = 0xFFFF;
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return;
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}
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// add delay
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const uint32_t now = AP_HAL::millis();
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uint32_t best_time_delta_wind = 200; // initialise large time representing buffer entry closest to current time - delay.
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uint8_t best_index_wind = 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_wind >= 10) { // store data every 10 ms.
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last_store_time_wind = now;
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if (store_index_wind > wind_buffer_length - 1) { // reset buffer index if index greater than size of buffer
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store_index_wind = 0;
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}
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buffer_wind[store_index_wind].data = airspeed_raw; // add data to current index
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buffer_wind[store_index_wind].time = last_store_time_wind; // add time to current index
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store_index_wind = store_index_wind + 1; // increment index
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}
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// return delayed measurement
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delayed_time_wind = now - _sitl->wind_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 <= wind_buffer_length - 1; i++) {
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// find difference between delayed time and time stamp in buffer
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time_delta_wind = abs(
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(int32_t)(delayed_time_wind - buffer_wind[i].time));
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// if this difference is smaller than last delta, store this time
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if (time_delta_wind < best_time_delta_wind) {
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best_index_wind = i;
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best_time_delta_wind = time_delta_wind;
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}
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}
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if (best_time_delta_wind < 200) { // only output stored state if < 200 msec retrieval error
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airspeed_raw = buffer_wind[best_index_wind].data;
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}
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airspeed_pin_value = airspeed_raw / 4;
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}
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#endif
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