ardupilot/libraries/AP_InertialSensor/AP_InertialSensor_SITL.cpp

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#include <AP_HAL/AP_HAL.h>
#include "AP_InertialSensor_SITL.h"
#include <SITL/SITL.h>
#include <stdio.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
const extern AP_HAL::HAL& hal;
AP_InertialSensor_SITL::AP_InertialSensor_SITL(AP_InertialSensor &imu) :
AP_InertialSensor_Backend(imu)
{
}
/*
detect the sensor
*/
AP_InertialSensor_Backend *AP_InertialSensor_SITL::detect(AP_InertialSensor &_imu)
{
AP_InertialSensor_SITL *sensor = new AP_InertialSensor_SITL(_imu);
if (sensor == nullptr) {
return nullptr;
}
if (!sensor->init_sensor()) {
delete sensor;
return nullptr;
}
return sensor;
}
bool AP_InertialSensor_SITL::init_sensor(void)
{
sitl = (SITL::SITL *)AP_Param::find_object("SIM_");
if (sitl == nullptr) {
return false;
}
// grab the used instances
for (uint8_t i=0; i<INS_SITL_INSTANCES; i++) {
gyro_instance[i] = _imu.register_gyro(gyro_sample_hz[i], i);
accel_instance[i] = _imu.register_accel(accel_sample_hz[i], i);
}
hal.scheduler->register_timer_process(FUNCTOR_BIND_MEMBER(&AP_InertialSensor_SITL::timer_update, void));
return true;
}
/*
generate an accelerometer sample
*/
void AP_InertialSensor_SITL::generate_accel(uint8_t instance)
{
// minimum noise levels are 2 bits, but averaged over many
// samples, giving around 0.01 m/s/s
float accel_noise = 0.01f;
if (sitl->motors_on) {
// add extra noise when the motors are on
accel_noise += instance==0?sitl->accel_noise:sitl->accel2_noise;
}
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// add accel bias and noise
Vector3f accel_bias = instance==0?sitl->accel_bias.get():sitl->accel2_bias.get();
float xAccel = sitl->state.xAccel + accel_noise * rand_float() + accel_bias.x;
float yAccel = sitl->state.yAccel + accel_noise * rand_float() + accel_bias.y;
float zAccel = sitl->state.zAccel + accel_noise * rand_float() + accel_bias.z;
// correct for the acceleration due to the IMU position offset and angular acceleration
// correct for the centripetal acceleration
// only apply corrections to first accelerometer
Vector3f pos_offset = sitl->imu_pos_offset;
if (!pos_offset.is_zero()) {
// calculate sensed acceleration due to lever arm effect
// Note: the % operator has been overloaded to provide a cross product
Vector3f angular_accel = Vector3f(radians(sitl->state.angAccel.x) , radians(sitl->state.angAccel.y) , radians(sitl->state.angAccel.z));
Vector3f lever_arm_accel = angular_accel % pos_offset;
// calculate sensed acceleration due to centripetal acceleration
Vector3f angular_rate = Vector3f(radians(sitl->state.rollRate), radians(sitl->state.pitchRate), radians(sitl->state.yawRate));
Vector3f centripetal_accel = angular_rate % (angular_rate % pos_offset);
// apply corrections
xAccel += lever_arm_accel.x + centripetal_accel.x;
yAccel += lever_arm_accel.y + centripetal_accel.y;
zAccel += lever_arm_accel.z + centripetal_accel.z;
}
if (fabsf(sitl->accel_fail) > 1.0e-6f) {
xAccel = sitl->accel_fail;
yAccel = sitl->accel_fail;
zAccel = sitl->accel_fail;
}
Vector3f accel = Vector3f(xAccel, yAccel, zAccel);
_rotate_and_correct_accel(accel_instance[instance], accel);
_notify_new_accel_raw_sample(accel_instance[instance], accel, AP_HAL::micros64());
}
/*
generate a gyro sample
*/
void AP_InertialSensor_SITL::generate_gyro(uint8_t instance)
{
// minimum gyro noise is less than 1 bit
float gyro_noise = ToRad(0.04f);
if (sitl->motors_on) {
// add extra noise when the motors are on
gyro_noise += ToRad(sitl->gyro_noise);
}
float p = radians(sitl->state.rollRate) + gyro_drift();
float q = radians(sitl->state.pitchRate) + gyro_drift();
float r = radians(sitl->state.yawRate) + gyro_drift();
p += gyro_noise * rand_float();
q += gyro_noise * rand_float();
r += gyro_noise * rand_float();
Vector3f gyro = Vector3f(p, q, r);
// add in gyro scaling
Vector3f scale = sitl->gyro_scale;
gyro.x *= (1 + scale.x*0.01);
gyro.y *= (1 + scale.y*0.01);
gyro.z *= (1 + scale.z*0.01);
_rotate_and_correct_gyro(gyro_instance[instance], gyro);
_notify_new_gyro_raw_sample(gyro_instance[instance], gyro, AP_HAL::micros64());
}
void AP_InertialSensor_SITL::timer_update(void)
{
uint64_t now = AP_HAL::micros64();
#if 0
// insert a 1s pause in IMU data. This triggers a pause in EK2
// processing that leads to some interesting issues
if (now > 5e6 && now < 6e6) {
return;
}
#endif
for (uint8_t i=0; i<INS_SITL_INSTANCES; i++) {
if (now >= next_accel_sample[i]) {
generate_accel(i);
while (now >= next_accel_sample[i]) {
next_accel_sample[i] += 1000000UL / accel_sample_hz[i];
}
}
if (now >= next_gyro_sample[i]) {
generate_gyro(i);
while (now >= next_gyro_sample[i]) {
next_gyro_sample[i] += 1000000UL / gyro_sample_hz[i];
}
}
}
}
float AP_InertialSensor_SITL::gyro_drift(void)
{
if (sitl->drift_speed == 0.0f ||
sitl->drift_time == 0.0f) {
return 0;
}
double period = sitl->drift_time * 2;
double minutes = fmod(AP_HAL::micros64() / 60.0e6, period);
if (minutes < period/2) {
return minutes * ToRad(sitl->drift_speed);
}
return (period - minutes) * ToRad(sitl->drift_speed);
}
bool AP_InertialSensor_SITL::update(void)
{
for (uint8_t i=0; i<INS_SITL_INSTANCES; i++) {
update_accel(accel_instance[i]);
update_gyro(gyro_instance[i]);
}
return true;
}
#endif // HAL_BOARD_SITL