void AC_AttitudeControl::update_ang_vel_target_from_att_error()
{
// Compute the roll angular velocity demand from the roll angle error
if (_att_ctrl_use_accel_limit && _accel_roll_max > 0.0f) {
_ang_vel_target_rads.x = sqrt_controller(_att_error_rot_vec_rad.x, _p_angle_roll.kP(), constrain_float(get_accel_roll_max_radss()/2.0f, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MIN_RADSS, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MAX_RADSS));
}else{
_ang_vel_target_rads.x = _p_angle_roll.kP() * _att_error_rot_vec_rad.x;
}
// Compute the pitch angular velocity demand from the roll angle error
if (_att_ctrl_use_accel_limit && _accel_pitch_max > 0.0f) {
_ang_vel_target_rads.y = sqrt_controller(_att_error_rot_vec_rad.y, _p_angle_pitch.kP(), constrain_float(get_accel_pitch_max_radss()/2.0f, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MIN_RADSS, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MAX_RADSS));
}else{
_ang_vel_target_rads.y = _p_angle_pitch.kP() * _att_error_rot_vec_rad.y;
}
// Compute the yaw angular velocity demand from the roll angle error
if (_att_ctrl_use_accel_limit && _accel_yaw_max > 0.0f) {
_ang_vel_target_rads.z = sqrt_controller(_att_error_rot_vec_rad.z, _p_angle_yaw.kP(), constrain_float(get_accel_yaw_max_radss()/2.0f, AC_ATTITUDE_ACCEL_Y_CONTROLLER_MIN_RADSS, AC_ATTITUDE_ACCEL_Y_CONTROLLER_MAX_RADSS));
}else{
_ang_vel_target_rads.z = _p_angle_yaw.kP() * _att_error_rot_vec_rad.z;
}
// Add feedforward term that attempts to ensure that the copter yaws about the reference
// Z axis, rather than the vehicle body Z axis.
// NOTE: This is a small-angle approximation.
_ang_vel_target_rads.x += _att_error_rot_vec_rad.y * _ahrs.get_gyro().z;
_ang_vel_target_rads.y += -_att_error_rot_vec_rad.x * _ahrs.get_gyro().z;
}
// update_rate_bf_targets - converts body-frame angle error to body-frame rate targets for roll, pitch and yaw axis
// targets rates in centi-degrees taken from _angle_bf_error
// results in centi-degrees/sec put into _rate_bf_target
void AC_AttitudeControl::update_rate_bf_targets()
{
// stab roll calculation
// constrain roll rate request
if (_flags.limit_angle_to_rate_request) {
_rate_bf_target.x = sqrt_controller(_angle_bf_error.x, _p_angle_roll.kP(), constrain_float(_accel_roll_max/2.0f, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MIN, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MAX));
}else{
_rate_bf_target.x = _p_angle_roll.kP() * _angle_bf_error.x;
}
// stab pitch calculation
// constrain pitch rate request
if (_flags.limit_angle_to_rate_request) {
_rate_bf_target.y = sqrt_controller(_angle_bf_error.y, _p_angle_pitch.kP(), constrain_float(_accel_pitch_max/2.0f, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MIN, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MAX));
}else{
_rate_bf_target.y = _p_angle_pitch.kP() * _angle_bf_error.y;
}
// stab yaw calculation
// constrain yaw rate request
if (_flags.limit_angle_to_rate_request) {
_rate_bf_target.z = sqrt_controller(_angle_bf_error.z, _p_angle_yaw.kP(), constrain_float(_accel_yaw_max/2.0f, AC_ATTITUDE_ACCEL_Y_CONTROLLER_MIN, AC_ATTITUDE_ACCEL_Y_CONTROLLER_MAX));
}else{
_rate_bf_target.z = _p_angle_yaw.kP() * _angle_bf_error.z;
}
// include roll and pitch rate required to account for precession of the desired attitude about the body frame yaw axes
_rate_bf_target.x += _angle_bf_error.y * _ahrs.get_gyro_for_control().z;
_rate_bf_target.y += -_angle_bf_error.x * _ahrs.get_gyro_for_control().z;
}
// Update rate_target_ang_vel using attitude_error_rot_vec_rad
Vector3f AC_AttitudeControl::update_ang_vel_target_from_att_error(Vector3f attitude_error_rot_vec_rad)
{
Vector3f rate_target_ang_vel;
// Compute the roll angular velocity demand from the roll angle error
if (_use_ff_and_input_shaping) {
rate_target_ang_vel.x = sqrt_controller(attitude_error_rot_vec_rad.x, _p_angle_roll.kP(), constrain_float(get_accel_roll_max_radss()/2.0f, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MIN_RADSS, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MAX_RADSS), _dt);
}else{
rate_target_ang_vel.x = _p_angle_roll.kP() * attitude_error_rot_vec_rad.x;
}
// Compute the pitch angular velocity demand from the roll angle error
if (_use_ff_and_input_shaping) {
rate_target_ang_vel.y = sqrt_controller(attitude_error_rot_vec_rad.y, _p_angle_pitch.kP(), constrain_float(get_accel_pitch_max_radss()/2.0f, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MIN_RADSS, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MAX_RADSS), _dt);
}else{
rate_target_ang_vel.y = _p_angle_pitch.kP() * attitude_error_rot_vec_rad.y;
}
// Compute the yaw angular velocity demand from the roll angle error
if (_use_ff_and_input_shaping) {
rate_target_ang_vel.z = sqrt_controller(attitude_error_rot_vec_rad.z, _p_angle_yaw.kP(), constrain_float(get_accel_yaw_max_radss()/2.0f, AC_ATTITUDE_ACCEL_Y_CONTROLLER_MIN_RADSS, AC_ATTITUDE_ACCEL_Y_CONTROLLER_MAX_RADSS), _dt);
}else{
rate_target_ang_vel.z = _p_angle_yaw.kP() * attitude_error_rot_vec_rad.z;
}
return rate_target_ang_vel;
}
void AC_AttitudeControl::update_ang_vel_target_from_att_error()
{
// Compute the roll angular velocity demand from the roll angle error
if (_att_ctrl_use_accel_limit && _accel_roll_max > 0.0f) {
_ang_vel_target_rads.x = sqrt_controller(_att_error_rot_vec_rad.x, _p_angle_roll.kP(), constrain_float(get_accel_roll_max_radss()/2.0f, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MIN_RADSS, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MAX_RADSS));
}else{
_ang_vel_target_rads.x = _p_angle_roll.kP() * _att_error_rot_vec_rad.x;
}
// Compute the pitch angular velocity demand from the roll angle error
if (_att_ctrl_use_accel_limit && _accel_pitch_max > 0.0f) {
_ang_vel_target_rads.y = sqrt_controller(_att_error_rot_vec_rad.y, _p_angle_pitch.kP(), constrain_float(get_accel_pitch_max_radss()/2.0f, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MIN_RADSS, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MAX_RADSS));
}else{
_ang_vel_target_rads.y = _p_angle_pitch.kP() * _att_error_rot_vec_rad.y;
}
// Compute the yaw angular velocity demand from the roll angle error
if (_att_ctrl_use_accel_limit && _accel_yaw_max > 0.0f) {
_ang_vel_target_rads.z = sqrt_controller(_att_error_rot_vec_rad.z, _p_angle_yaw.kP(), constrain_float(get_accel_yaw_max_radss()/2.0f, AC_ATTITUDE_ACCEL_Y_CONTROLLER_MIN_RADSS, AC_ATTITUDE_ACCEL_Y_CONTROLLER_MAX_RADSS));
}else{
_ang_vel_target_rads.z = _p_angle_yaw.kP() * _att_error_rot_vec_rad.z;
}
// Account for precession of desired attitude about the body frame yaw axis
_ang_vel_target_rads.x += _att_error_rot_vec_rad.y * _ahrs.get_gyro().z;
_ang_vel_target_rads.y += -_att_error_rot_vec_rad.x * _ahrs.get_gyro().z;
}
// calculates the velocity correction from an angle error. The angular velocity has acceleration and
// deceleration limits including basic jerk limiting using smoothing_gain
float AC_AttitudeControl::input_shaping_angle(float error_angle, float smoothing_gain, float accel_max, float target_ang_vel, float dt)
{
// Calculate the velocity as error approaches zero with acceleration limited by accel_max_radss
float ang_vel = sqrt_controller(error_angle, smoothing_gain, accel_max, dt);
// Acceleration is limited directly to smooth the beginning of the curve.
if (accel_max > 0) {
float delta_ang_vel = accel_max * dt;
return constrain_float(ang_vel, target_ang_vel-delta_ang_vel, target_ang_vel+delta_ang_vel);
} else {
return ang_vel;
}
}
/// run horizontal position controller correcting position and velocity
/// converts position (_pos_target) to target velocity (_vel_target)
/// desired velocity (_vel_desired) is combined into final target velocity
/// converts desired velocities in lat/lon directions to accelerations in lat/lon frame
/// converts desired accelerations provided in lat/lon frame to roll/pitch angles
void AC_PosControl::run_xy_controller(float dt)
{
float ekfGndSpdLimit, ekfNavVelGainScaler;
AP::ahrs_navekf().getEkfControlLimits(ekfGndSpdLimit, ekfNavVelGainScaler);
Vector3f curr_pos = _inav.get_position();
float kP = ekfNavVelGainScaler * _p_pos_xy.kP(); // scale gains to compensate for noisy optical flow measurement in the EKF
// avoid divide by zero
if (kP <= 0.0f) {
_vel_target.x = 0.0f;
_vel_target.y = 0.0f;
}else{
// calculate distance error
_pos_error.x = _pos_target.x - curr_pos.x;
_pos_error.y = _pos_target.y - curr_pos.y;
// Constrain _pos_error and target position
// Constrain the maximum length of _vel_target to the maximum position correction velocity
// TODO: replace the leash length with a user definable maximum position correction
if (limit_vector_length(_pos_error.x, _pos_error.y, _leash))
{
_pos_target.x = curr_pos.x + _pos_error.x;
_pos_target.y = curr_pos.y + _pos_error.y;
}
_vel_target = sqrt_controller(_pos_error, kP, _accel_cms);
}
// add velocity feed-forward
_vel_target.x += _vel_desired.x;
_vel_target.y += _vel_desired.y;
// the following section converts desired velocities in lat/lon directions to accelerations in lat/lon frame
Vector2f accel_target, vel_xy_p, vel_xy_i, vel_xy_d;
// check if vehicle velocity is being overridden
if (_flags.vehicle_horiz_vel_override) {
_flags.vehicle_horiz_vel_override = false;
} else {
_vehicle_horiz_vel.x = _inav.get_velocity().x;
_vehicle_horiz_vel.y = _inav.get_velocity().y;
}
// calculate velocity error
_vel_error.x = _vel_target.x - _vehicle_horiz_vel.x;
_vel_error.y = _vel_target.y - _vehicle_horiz_vel.y;
// TODO: constrain velocity error and velocity target
// call pi controller
_pid_vel_xy.set_input(_vel_error);
// get p
vel_xy_p = _pid_vel_xy.get_p();
// update i term if we have not hit the accel or throttle limits OR the i term will reduce
// TODO: move limit handling into the PI and PID controller
if (!_limit.accel_xy && !_motors.limit.throttle_upper) {
vel_xy_i = _pid_vel_xy.get_i();
} else {
vel_xy_i = _pid_vel_xy.get_i_shrink();
}
// get d
vel_xy_d = _pid_vel_xy.get_d();
// acceleration to correct for velocity error and scale PID output to compensate for optical flow measurement induced EKF noise
accel_target.x = (vel_xy_p.x + vel_xy_i.x + vel_xy_d.x) * ekfNavVelGainScaler;
accel_target.y = (vel_xy_p.y + vel_xy_i.y + vel_xy_d.y) * ekfNavVelGainScaler;
// reset accel to current desired acceleration
if (_flags.reset_accel_to_lean_xy) {
_accel_target_filter.reset(Vector2f(accel_target.x, accel_target.y));
_flags.reset_accel_to_lean_xy = false;
}
// filter correction acceleration
_accel_target_filter.set_cutoff_frequency(MIN(_accel_xy_filt_hz, 5.0f*ekfNavVelGainScaler));
_accel_target_filter.apply(accel_target, dt);
// pass the correction acceleration to the target acceleration output
_accel_target.x = _accel_target_filter.get().x;
_accel_target.y = _accel_target_filter.get().y;
// Add feed forward into the target acceleration output
_accel_target.x += _accel_desired.x;
_accel_target.y += _accel_desired.y;
// the following section converts desired accelerations provided in lat/lon frame to roll/pitch angles
// limit acceleration using maximum lean angles
float angle_max = MIN(_attitude_control.get_althold_lean_angle_max(), get_lean_angle_max_cd());
float accel_max = MIN(GRAVITY_MSS * 100.0f * tanf(ToRad(angle_max * 0.01f)), POSCONTROL_ACCEL_XY_MAX);
_limit.accel_xy = limit_vector_length(_accel_target.x, _accel_target.y, accel_max);
// update angle targets that will be passed to stabilize controller
accel_to_lean_angles(_accel_target.x, _accel_target.y, _roll_target, _pitch_target);
}
// angle_ef_roll_pitch_rate_ef_yaw_smooth - attempts to maintain a roll and pitch angle and yaw rate (all earth frame) while smoothing the attitude based on the feel parameter
// smoothing_gain : a number from 1 to 50 with 1 being sluggish and 50 being very crisp
void AC_AttitudeControl::angle_ef_roll_pitch_rate_ef_yaw_smooth(float roll_angle_ef, float pitch_angle_ef, float yaw_rate_ef, float smoothing_gain)
{
float rate_ef_desired;
float rate_change_limit;
Vector3f angle_ef_error; // earth frame angle errors
// sanity check smoothing gain
smoothing_gain = constrain_float(smoothing_gain,1.0f,50.0f);
// if accel limiting and feed forward enabled
if ((_accel_roll_max > 0.0f) && _rate_bf_ff_enabled) {
rate_change_limit = _accel_roll_max * _dt;
// calculate earth-frame feed forward roll rate using linear response when close to the target, sqrt response when we're further away
rate_ef_desired = sqrt_controller(roll_angle_ef-_angle_ef_target.x, smoothing_gain, _accel_roll_max);
// apply acceleration limit to feed forward roll rate
_rate_ef_desired.x = constrain_float(rate_ef_desired, _rate_ef_desired.x-rate_change_limit, _rate_ef_desired.x+rate_change_limit);
// update earth-frame roll angle target using desired roll rate
update_ef_roll_angle_and_error(_rate_ef_desired.x, angle_ef_error, AC_ATTITUDE_RATE_STAB_ROLL_OVERSHOOT_ANGLE_MAX);
} else {
// target roll and pitch to desired input roll and pitch
_angle_ef_target.x = roll_angle_ef;
angle_ef_error.x = wrap_180_cd_float(_angle_ef_target.x - _ahrs.roll_sensor);
// set roll and pitch feed forward to zero
_rate_ef_desired.x = 0;
}
// constrain earth-frame angle targets
_angle_ef_target.x = constrain_float(_angle_ef_target.x, -_aparm.angle_max, _aparm.angle_max);
// if accel limiting and feed forward enabled
if ((_accel_pitch_max > 0.0f) && _rate_bf_ff_enabled) {
rate_change_limit = _accel_pitch_max * _dt;
// calculate earth-frame feed forward pitch rate using linear response when close to the target, sqrt response when we're further away
rate_ef_desired = sqrt_controller(pitch_angle_ef-_angle_ef_target.y, smoothing_gain, _accel_pitch_max);
// apply acceleration limit to feed forward pitch rate
_rate_ef_desired.y = constrain_float(rate_ef_desired, _rate_ef_desired.y-rate_change_limit, _rate_ef_desired.y+rate_change_limit);
// update earth-frame pitch angle target using desired pitch rate
update_ef_pitch_angle_and_error(_rate_ef_desired.y, angle_ef_error, AC_ATTITUDE_RATE_STAB_PITCH_OVERSHOOT_ANGLE_MAX);
} else {
// target roll and pitch to desired input roll and pitch
_angle_ef_target.y = pitch_angle_ef;
angle_ef_error.y = wrap_180_cd_float(_angle_ef_target.y - _ahrs.pitch_sensor);
// set roll and pitch feed forward to zero
_rate_ef_desired.y = 0;
}
// constrain earth-frame angle targets
_angle_ef_target.y = constrain_float(_angle_ef_target.y, -_aparm.angle_max, _aparm.angle_max);
if (_accel_yaw_max > 0.0f) {
// set earth-frame feed forward rate for yaw
rate_change_limit = _accel_yaw_max * _dt;
// update yaw rate target with acceleration limit
_rate_ef_desired.z += constrain_float(yaw_rate_ef - _rate_ef_desired.z, -rate_change_limit, rate_change_limit);
// calculate yaw target angle and angle error
update_ef_yaw_angle_and_error(_rate_ef_desired.z, angle_ef_error, AC_ATTITUDE_RATE_STAB_YAW_OVERSHOOT_ANGLE_MAX);
} else {
// set yaw feed forward to zero
_rate_ef_desired.z = yaw_rate_ef;
// calculate yaw target angle and angle error
update_ef_yaw_angle_and_error(_rate_ef_desired.z, angle_ef_error, AC_ATTITUDE_RATE_STAB_YAW_OVERSHOOT_ANGLE_MAX);
}
// convert earth-frame angle errors to body-frame angle errors
frame_conversion_ef_to_bf(angle_ef_error, _angle_bf_error);
// convert body-frame angle errors to body-frame rate targets
update_rate_bf_targets();
// add body frame rate feed forward
if (_rate_bf_ff_enabled) {
// convert earth-frame feed forward rates to body-frame feed forward rates
frame_conversion_ef_to_bf(_rate_ef_desired, _rate_bf_desired);
_rate_bf_target += _rate_bf_desired;
} else {
// convert earth-frame feed forward rates to body-frame feed forward rates
frame_conversion_ef_to_bf(Vector3f(0,0,_rate_ef_desired.z), _rate_bf_desired);
_rate_bf_target += _rate_bf_desired;
}
// body-frame to motor outputs should be called separately
}
void AC_AttitudeControl::input_euler_angle_roll_pitch_euler_rate_yaw_smooth(float euler_roll_angle_cd, float euler_pitch_angle_cd, float euler_yaw_rate_cds, float smoothing_gain)
{
// Convert from centidegrees on public interface to radians
float euler_roll_angle_rad = radians(euler_roll_angle_cd*0.01f);
float euler_pitch_angle_rad = radians(euler_pitch_angle_cd*0.01f);
float euler_yaw_rate_rads = radians(euler_yaw_rate_cds*0.01f);
// Sanity check smoothing gain
smoothing_gain = constrain_float(smoothing_gain,1.0f,50.0f);
// Add roll trim to compensate tail rotor thrust in heli (will return zero on multirotors)
euler_roll_angle_rad += get_roll_trim_rad();
if ((get_accel_roll_max_radss() > 0.0f) && _rate_bf_ff_enabled) {
// When roll acceleration limiting and feedforward are enabled, the sqrt controller is used to compute an euler roll-axis
// angular velocity that will cause the euler roll angle to smoothly stop at the input angle with limited deceleration
// and an exponential decay specified by smoothing_gain at the end.
float euler_rate_desired_rads = sqrt_controller(euler_roll_angle_rad-_att_target_euler_rad.x, smoothing_gain, get_accel_roll_max_radss());
// Acceleration is limited directly to smooth the beginning of the curve.
float rate_change_limit_rads = get_accel_roll_max_radss() * _dt;
_att_target_euler_rate_rads.x = constrain_float(euler_rate_desired_rads, _att_target_euler_rate_rads.x-rate_change_limit_rads, _att_target_euler_rate_rads.x+rate_change_limit_rads);
// The output rate is used to update the attitude target euler angles and is fed forward into the rate controller.
update_att_target_roll(_att_target_euler_rate_rads.x, AC_ATTITUDE_RATE_STAB_ROLL_OVERSHOOT_ANGLE_MAX_RAD);
} else {
// When acceleration limiting and feedforward are not enabled, the target roll euler angle is simply set to the
// input value and the feedforward rate is zeroed.
_att_target_euler_rad.x = euler_roll_angle_rad;
_att_target_euler_rate_rads.x = 0;
}
_att_target_euler_rad.x = constrain_float(_att_target_euler_rad.x, -get_tilt_limit_rad(), get_tilt_limit_rad());
if ((get_accel_pitch_max_radss() > 0.0f) && _rate_bf_ff_enabled) {
// When pitch acceleration limiting and feedforward are enabled, the sqrt controller is used to compute an euler pitch-axis
// angular velocity that will cause the euler pitch angle to smoothly stop at the input angle with limited deceleration
// and an exponential decay specified by smoothing_gain at the end.
float euler_rate_desired_rads = sqrt_controller(euler_pitch_angle_rad-_att_target_euler_rad.y, smoothing_gain, get_accel_pitch_max_radss());
// Acceleration is limited directly to smooth the beginning of the curve.
float rate_change_limit_rads = get_accel_pitch_max_radss() * _dt;
_att_target_euler_rate_rads.y = constrain_float(euler_rate_desired_rads, _att_target_euler_rate_rads.y-rate_change_limit_rads, _att_target_euler_rate_rads.y+rate_change_limit_rads);
// The output rate is used to update the attitude target euler angles and is fed forward into the rate controller.
update_att_target_pitch(_att_target_euler_rate_rads.y, AC_ATTITUDE_RATE_STAB_ROLL_OVERSHOOT_ANGLE_MAX_RAD);
} else {
_att_target_euler_rad.y = euler_pitch_angle_rad;
_att_target_euler_rate_rads.y = 0;
}
_att_target_euler_rad.y = constrain_float(_att_target_euler_rad.y, -get_tilt_limit_rad(), get_tilt_limit_rad());
if (get_accel_yaw_max_radss() > 0.0f) {
// When yaw acceleration limiting is enabled, the yaw input shaper constrains angular acceleration about the yaw axis, slewing
// the output rate towards the input rate.
float rate_change_limit_rads = get_accel_yaw_max_radss() * _dt;
_att_target_euler_rate_rads.z += constrain_float(euler_yaw_rate_rads - _att_target_euler_rate_rads.z, -rate_change_limit_rads, rate_change_limit_rads);
// The output rate is used to update the attitude target euler angles and is fed forward into the rate controller.
update_att_target_yaw(_att_target_euler_rate_rads.z, AC_ATTITUDE_RATE_STAB_YAW_OVERSHOOT_ANGLE_MAX_RAD);
} else {
// When yaw acceleration limiting is disabled, the attitude target is simply rotated using the input rate and the input rate
// is fed forward into the rate controller.
_att_target_euler_rate_rads.z = euler_yaw_rate_rads;
update_att_target_yaw(_att_target_euler_rate_rads.z, AC_ATTITUDE_RATE_STAB_YAW_OVERSHOOT_ANGLE_MAX_RAD);
}
// Convert euler angle derivative of desired attitude into a body-frame angular velocity vector for feedforward
if (_rate_bf_ff_enabled) {
euler_rate_to_ang_vel(_att_target_euler_rad, _att_target_euler_rate_rads, _att_target_ang_vel_rads);
} else {
euler_rate_to_ang_vel(_att_target_euler_rad, Vector3f(0,0,_att_target_euler_rate_rads.z), _att_target_ang_vel_rads);
}
// Call attitude controller
attitude_controller_run_euler(_att_target_euler_rad, _att_target_ang_vel_rads);
}
// angle_ef_roll_pitch_rate_ef_yaw_smooth - attempts to maintain a roll and pitch angle and yaw rate (all earth frame) while smoothing the attitude based on the feel parameter
// smoothing_gain : a number from 1 to 50 with 1 being sluggish and 50 being very crisp此函数通过目标角度计算出所需要的角速度，并更新了误差值
void AC_AttitudeControl::angle_ef_roll_pitch_rate_ef_yaw_smooth(float roll_angle_ef, float pitch_angle_ef, float yaw_rate_ef, float smoothing_gain)
{
float rate_ef_desired;//地面坐标系下的速度
float rate_change_limit;
Vector3f angle_ef_error; // earth frame angle errors地面坐标系下角度误差
// sanity check smoothing gain
smoothing_gain = constrain_float(smoothing_gain,1.0f,50.0f);//把smoothing_gain约束在1到5之间，1的话反应迟钝，50反应迅速，反应慢的话在有风的情况下可能导致坠机
// if accel limiting and feed forward enabled
if ((_accel_roll_max > 0.0f) && _rate_bf_ff_enabled) {//如果roll角加速度(地面坐标系）最大值大于0且允许速度前馈？
rate_change_limit = _accel_roll_max * _dt;//_dt时间间隔，以秒为单位，此函数代表roll在单位时间内改变速率的最大值？即角加速度最大值？
// calculate earth-frame feed forward roll rate using linear response when close to the target, sqrt response when we're further away
//计算需要的速度
rate_ef_desired = sqrt_controller(roll_angle_ef-_angle_ef_target.x, smoothing_gain, _accel_roll_max);//target为实时目标点，不断更新，而遥控器的信号也是不断更新
// apply acceleration limit to feed forward roll rate限制角速度大小
_rate_ef_desired.x = constrain_float(rate_ef_desired, _rate_ef_desired.x-rate_change_limit, _rate_ef_desired.x+rate_change_limit);
// update earth-frame roll angle target using desired roll rate回传角度误差，第三个参数是什么
update_ef_roll_angle_and_error(_rate_ef_desired.x, angle_ef_error, AC_ATTITUDE_RATE_STAB_ROLL_OVERSHOOT_ANGLE_MAX);
} else {
// target roll and pitch to desired input roll and pitch
_angle_ef_target.x = roll_angle_ef;//目标角度为滚转角
angle_ef_error.x = wrap_180_cd_float(_angle_ef_target.x - _ahrs.roll_sensor);//角度误差为目标角度减去传感器的角度，限制在180度之内
// set roll and pitch feed forward to zero
_rate_ef_desired.x = 0;//所需要的滚转角速度设为0
}
// constrain earth-frame angle targets
_angle_ef_target.x = constrain_float(_angle_ef_target.x, -_aparm.angle_max, _aparm.angle_max);//约束目标角度
// if accel limiting and feed forward enabled
if ((_accel_pitch_max > 0.0f) && _rate_bf_ff_enabled) {
rate_change_limit = _accel_pitch_max * _dt;
// calculate earth-frame feed forward pitch rate using linear response when close to the target, sqrt response when we're further away
rate_ef_desired = sqrt_controller(pitch_angle_ef-_angle_ef_target.y, smoothing_gain, _accel_pitch_max);
// apply acceleration limit to feed forward pitch rate
_rate_ef_desired.y = constrain_float(rate_ef_desired, _rate_ef_desired.y-rate_change_limit, _rate_ef_desired.y+rate_change_limit);
// update earth-frame pitch angle target using desired pitch rate
update_ef_pitch_angle_and_error(_rate_ef_desired.y, angle_ef_error, AC_ATTITUDE_RATE_STAB_PITCH_OVERSHOOT_ANGLE_MAX);
} else {
// target roll and pitch to desired input roll and pitch
_angle_ef_target.y = pitch_angle_ef;
angle_ef_error.y = wrap_180_cd_float(_angle_ef_target.y - _ahrs.pitch_sensor);
// set roll and pitch feed forward to zero
_rate_ef_desired.y = 0;
}
// constrain earth-frame angle targets
_angle_ef_target.y = constrain_float(_angle_ef_target.y, -_aparm.angle_max, _aparm.angle_max);
if (_accel_yaw_max > 0.0f) {
// set earth-frame feed forward rate for yaw
rate_change_limit = _accel_yaw_max * _dt;
// update yaw rate target with acceleration limit
_rate_ef_desired.z += constrain_float(yaw_rate_ef - _rate_ef_desired.z, -rate_change_limit, rate_change_limit);
// calculate yaw target angle and angle error
update_ef_yaw_angle_and_error(_rate_ef_desired.z, angle_ef_error, AC_ATTITUDE_RATE_STAB_YAW_OVERSHOOT_ANGLE_MAX);
} else {
// set yaw feed forward to zero
_rate_ef_desired.z = yaw_rate_ef;
// calculate yaw target angle and angle error
update_ef_yaw_angle_and_error(_rate_ef_desired.z, angle_ef_error, AC_ATTITUDE_RATE_STAB_YAW_OVERSHOOT_ANGLE_MAX);
}
// convert earth-frame angle errors to body-frame angle errors
frame_conversion_ef_to_bf(angle_ef_error, _angle_bf_error);
// convert body-frame angle errors to body-frame rate targets
update_rate_bf_targets();
// add body frame rate feed forward
if (_rate_bf_ff_enabled) {
// convert earth-frame feed forward rates to body-frame feed forward rates
frame_conversion_ef_to_bf(_rate_ef_desired, _rate_bf_desired);
_rate_bf_target += _rate_bf_desired;
} else {
// convert earth-frame feed forward rates to body-frame feed forward rates
frame_conversion_ef_to_bf(Vector3f(0,0,_rate_ef_desired.z), _rate_bf_desired);
_rate_bf_target += _rate_bf_desired;
}
// body-frame to motor outputs should be called separately
}