static float pid_controller_differentiate(differentiator_t* diff, float input, float dt)
{
float output = 0.0f;
if( dt<0.000001f )
{
output=0.0f;
}
else
{
output = maths_clip(diff->gain * (input - diff->previous) / dt, diff->clip);
}
diff->previous = input;
return output;
}
void simulation_update(simulation_model_t *sim)
{
int32_t i;
quat_t qtmp1, qvel_bf, qed;
const quat_t front = {.s = 0.0f, .v = {1.0f, 0.0f, 0.0f}};
const quat_t up = {.s = 0.0f, .v = {UPVECTOR_X, UPVECTOR_Y, UPVECTOR_Z}};
uint32_t now = time_keeper_get_micros();
sim->dt = (now - sim->last_update) / 1000000.0f;
if (sim->dt > 0.1f)
{
sim->dt = 0.1f;
}
sim->last_update = now;
// compute torques and forces based on servo commands
forces_from_servos_diag_quad(sim);
// integrate torques to get simulated gyro rates (with some damping)
sim->rates_bf[0] = maths_clip((1.0f - 0.1f * sim->dt) * sim->rates_bf[0] + sim->dt * sim->torques_bf[0] / sim->vehicle_config.roll_pitch_momentum, 10.0f);
sim->rates_bf[1] = maths_clip((1.0f - 0.1f * sim->dt) * sim->rates_bf[1] + sim->dt * sim->torques_bf[1] / sim->vehicle_config.roll_pitch_momentum, 10.0f);
sim->rates_bf[2] = maths_clip((1.0f - 0.1f * sim->dt) * sim->rates_bf[2] + sim->dt * sim->torques_bf[2] / sim->vehicle_config.yaw_momentum, 10.0f);
for (i = 0; i < 3; i++)
{
qtmp1.v[i] = 0.5f * sim->rates_bf[i];
}
qtmp1.s = 0;
// apply step rotation
qed = quaternions_multiply(sim->ahrs.qe,qtmp1);
// TODO: correct this formulas when using the right scales
sim->ahrs.qe.s = sim->ahrs.qe.s + qed.s * sim->dt;
sim->ahrs.qe.v[0] += qed.v[0] * sim->dt;
sim->ahrs.qe.v[1] += qed.v[1] * sim->dt;
sim->ahrs.qe.v[2] += qed.v[2] * sim->dt;
sim->ahrs.qe = quaternions_normalise(sim->ahrs.qe);
sim->ahrs.up_vec = quaternions_global_to_local(sim->ahrs.qe, up);
sim->ahrs.north_vec = quaternions_global_to_local(sim->ahrs.qe, front);
// velocity and position integration
// check altitude - if it is lower than 0, clamp everything (this is in NED, assuming negative altitude)
if (sim->local_position.pos[Z] >0)
{
sim->vel[Z] = 0.0f;
sim->local_position.pos[Z] = 0.0f;
// simulate "acceleration" caused by contact force with ground, compensating gravity
for (i = 0; i < 3; i++)
{
sim->lin_forces_bf[i] = sim->ahrs.up_vec.v[i] * sim->vehicle_config.total_mass * sim->vehicle_config.sim_gravity;
}
// slow down... (will make velocity slightly inconsistent until next update cycle, but shouldn't matter much)
for (i = 0; i < 3; i++)
{
sim->vel_bf[i] = 0.95f * sim->vel_bf[i];
}
//upright
sim->rates_bf[0] = sim->ahrs.up_vec.v[1];
sim->rates_bf[1] = - sim->ahrs.up_vec.v[0];
sim->rates_bf[2] = 0;
}
sim->ahrs.qe = quaternions_normalise(sim->ahrs.qe);
sim->ahrs.up_vec = quaternions_global_to_local(sim->ahrs.qe, up);
sim->ahrs.north_vec = quaternions_global_to_local(sim->ahrs.qe, front);
for (i = 0; i < 3; i++)
{
qtmp1.v[i] = sim->vel[i];
}
qtmp1.s = 0.0f;
qvel_bf = quaternions_global_to_local(sim->ahrs.qe, qtmp1);
float acc_bf[3];
for (i = 0; i < 3; i++)
{
sim->vel_bf[i] = qvel_bf.v[i];
// following the convention in the IMU, this is the acceleration due to force, as measured
sim->ahrs.linear_acc[i] = sim->lin_forces_bf[i] / sim->vehicle_config.total_mass;
// this is the "clean" acceleration without gravity
acc_bf[i] = sim->ahrs.linear_acc[i] - sim->ahrs.up_vec.v[i] * sim->vehicle_config.sim_gravity;
sim->vel_bf[i] = sim->vel_bf[i] + acc_bf[i] * sim->dt;
}
// calculate velocity in global frame
// vel = qe *vel_bf * qe - 1
qvel_bf.s = 0.0f; qvel_bf.v[0] = sim->vel_bf[0]; qvel_bf.v[1] = sim->vel_bf[1]; qvel_bf.v[2] = sim->vel_bf[2];
qtmp1 = quaternions_local_to_global(sim->ahrs.qe, qvel_bf);
sim->vel[0] = qtmp1.v[0]; sim->vel[1] = qtmp1.v[1]; sim->vel[2] = qtmp1.v[2];
for (i = 0; i < 3; i++)
{
sim->local_position.pos[i] = sim->local_position.pos[i] + sim->vel[i] * sim->dt;
}
// fill in simulated IMU values
for (i = 0;i < 3; i++)
{
sim->imu->raw_gyro.data[sim->imu->calib_gyro.axis[i]] = (sim->rates_bf[i] * sim->calib_gyro.scale_factor[i] + sim->calib_gyro.bias[i]) * sim->calib_gyro.orientation[i];
sim->imu->raw_accelero.data[sim->imu->calib_accelero.axis[i]] = ((sim->lin_forces_bf[i] / sim->vehicle_config.total_mass / sim->vehicle_config.sim_gravity) * sim->calib_accelero.scale_factor[i] + sim->calib_accelero.bias[i]) * sim->calib_accelero.orientation[i];
sim->imu->raw_compass.data[sim->imu->calib_compass.axis[i]] = ((sim->ahrs.north_vec.v[i] ) * sim->calib_compass.scale_factor[i] + sim->calib_compass.bias[i])* sim->calib_compass.orientation[i];
}
sim->local_position.heading = coord_conventions_get_yaw(sim->ahrs.qe);
}
void simulation_simulate_barometer(simulation_model_t *sim)
{
sim->pressure->altitude = sim->local_position.origin.altitude - sim->local_position.pos[Z];
sim->pressure->vario_vz = sim->vel[Z];
sim->pressure->last_update = time_keeper_get_millis();
sim->pressure->altitude_offset = 0;
}
void simulation_simulate_gps(simulation_model_t *sim)
{
global_position_t gpos = coord_conventions_local_to_global_position(sim->local_position);
sim->gps->altitude = gpos.altitude;
sim->gps->latitude = gpos.latitude;
sim->gps->longitude = gpos.longitude;
sim->gps->time_last_msg = time_keeper_get_millis();
sim->gps->time_last_posllh_msg = time_keeper_get_millis();
sim->gps->time_last_velned_msg = time_keeper_get_millis();
sim->gps->north_speed = sim->vel[X];
sim->gps->east_speed = sim->vel[Y];
sim->gps->vertical_speed = sim->vel[Z];
sim->gps->status = GPS_OK;
sim->gps->healthy = true;
}
static float pid_controller_integrate(integrator_t* integrator, float input, float dt)
{
integrator->accumulator = integrator->accumulator + maths_clip(dt* integrator->gain * input, integrator->clip_pre);
integrator->accumulator = maths_clip(integrator->accumulator, integrator->clip);
return integrator->accumulator;
}
void velocity_controller_copter_update(velocity_controller_copter_t* controller)
{
float velocity_command_global[3];
float errors[3];
float thrust_vector[3];
float thrust_norm;
float thrust_dir[3];
// Get the command velocity in global frame
switch( controller->velocity_command->mode )
{
case VELOCITY_COMMAND_MODE_LOCAL:
get_velocity_command_from_local_to_global( controller,
velocity_command_global );
break;
case VELOCITY_COMMAND_MODE_SEMI_LOCAL:
get_velocity_command_from_semilocal_to_global( controller,
velocity_command_global );
break;
case VELOCITY_COMMAND_MODE_GLOBAL:
velocity_command_global[X] = controller->velocity_command->xyz[X];
velocity_command_global[Y] = controller->velocity_command->xyz[Y];
velocity_command_global[Z] = controller->velocity_command->xyz[Z];
break;
default:
velocity_command_global[X] = 0.0f;
velocity_command_global[Y] = 0.0f;
velocity_command_global[Z] = 0.0f;
break;
}
// Compute errors
errors[X] = velocity_command_global[X] - controller->pos_est->vel[X];
errors[Y] = velocity_command_global[Y] - controller->pos_est->vel[Y];
errors[Z] = velocity_command_global[Z] - controller->pos_est->vel[Z]; // WARNING: it was multiplied by (-1) in stabilisation_copter.c
// Update PID
thrust_vector[X] = pid_controller_update_dt( &controller->pid[X], errors[X], controller->ahrs->dt ); // should be multiplied by mass
thrust_vector[Y] = pid_controller_update_dt( &controller->pid[Y], errors[Y], controller->ahrs->dt ); // should be multiplied by mass
// thrust_vector[Z] = - GRAVITY + pid_controller_update_dt( &controller->pid[Z], errors[Z], controller->ahrs->dt ); // should be multiplied by mass
thrust_vector[Z] = pid_controller_update_dt( &controller->pid[Z], errors[Z], controller->ahrs->dt ); // should be multiplied by mass
// Compute the norm of the thrust that should be applied
thrust_norm = vectors_norm(thrust_vector);
// Compute the direction in which thrust should be apply
thrust_dir[X] = thrust_vector[X] / thrust_norm;
thrust_dir[Y] = thrust_vector[Y] / thrust_norm;
thrust_dir[Z] = thrust_vector[Z] / thrust_norm;
// Map thrust dir to attitude
controller->attitude_command->mode = ATTITUDE_COMMAND_MODE_RPY;
controller->attitude_command->rpy[ROLL] = maths_clip(thrust_vector[Y], 1);
controller->attitude_command->rpy[PITCH] = - maths_clip(thrust_vector[X], 1);
controller->attitude_command->rpy[YAW] = 0.0f;
// Map PID output to thrust
// float max_thrust = 30.0f; // 10 Newton max thrust
// controller->thrust_command->thrust = maths_clip(thrust_norm/max_thrust, 1.0f) * 2.0f - 1;
// controller->thrust_command->thrust = maths_clip(thrust_norm, 1.0f) * 2.0f - 1;
// controller->thrust_command->thrust = - 1.0 + 2 * thrust_norm/max_thrust;
// // Map PID output to attitude
// controller->attitude_command->mode = ATTITUDE_COMMAND_MODE_RPY;
// controller->attitude_command->rpy[ROLL] = maths_clip(thrust_vector[Y], 1);
// controller->attitude_command->rpy[PITCH] = - maths_clip(thrust_vector[X], 1);
// controller->attitude_command->rpy[YAW] = 0.0f;
// Map PID output to thrust
controller->thrust_command->thrust = controller->thrust_hover_point - thrust_vector[Z];
}