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AC_PosControl: add accel feedforward

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also add limit_vector_length and sqrt_controller helper functions
enforce angle limits
rename accel-feedforward to accel-desired
remove freeze_ff_xy
remove unused VEL_XY_MAX_FROM_POS_ERR
remove xy mode
remove jerk limiting code including setters
limit_vector_length uses is_positive
Also modify formatting
This commit is contained in:
Leonard Hall 2017-11-16 21:29:02 +09:00 committed by Randy Mackay
parent 9aa6415e1c
commit 74bb7616a7
2 changed files with 120 additions and 172 deletions
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252
libraries/AC_AttitudeControl/AC_PosControl.cpp
View File

@ -196,14 +196,12 @@ AC_PosControl::AC_PosControl(const AP_AHRS_View& ahrs, const AP_InertialNav& ina
_accel_z_cms(POSCONTROL_ACCEL_Z),
_accel_last_z_cms(0.0f),
_accel_cms(POSCONTROL_ACCEL_XY),
_jerk_cmsss(POSCONTROL_JERK_LIMIT_CMSSS),
_leash(POSCONTROL_LEASH_LENGTH_MIN),
_leash_down_z(POSCONTROL_LEASH_LENGTH_MIN),
_leash_up_z(POSCONTROL_LEASH_LENGTH_MIN),
_roll_target(0.0f),
_pitch_target(0.0f),
_distance_to_target(0.0f),
_accel_target_jerk_limited(0.0f,0.0f),
_accel_target_filter(POSCONTROL_ACCEL_FILTER_HZ)
{
AP_Param::setup_object_defaults(this, var_info);
@ -212,11 +210,9 @@ AC_PosControl::AC_PosControl(const AP_AHRS_View& ahrs, const AP_InertialNav& ina
_flags.recalc_leash_z = true;
_flags.recalc_leash_xy = true;
_flags.reset_desired_vel_to_pos = true;
_flags.reset_rate_to_accel_xy = true;
_flags.reset_accel_to_lean_xy = true;
_flags.reset_rate_to_accel_z = true;
_flags.reset_accel_to_throttle = true;
_flags.freeze_ff_xy = true;
_flags.freeze_ff_z = true;
_flags.use_desvel_ff_z = true;
_limit.pos_up = true;
@ -384,7 +380,7 @@ void AC_PosControl::relax_alt_hold_controllers(float throttle_setting)
_flags.use_desvel_ff_z = false;
_vel_target.z = _inav.get_velocity_z();
_vel_last.z = _inav.get_velocity_z();
_accel_feedforward.z = 0.0f;
_accel_desired.z = 0.0f;
_accel_last_z_cms = 0.0f;
_accel_target.z = -(_ahrs.get_accel_ef_blended().z + GRAVITY_MSS) * 100.0f;
_flags.reset_accel_to_throttle = true;
@ -567,13 +563,13 @@ void AC_PosControl::rate_to_accel_z()
// feed forward desired acceleration calculation
if (_dt > 0.0f) {
if (!_flags.freeze_ff_z) {
_accel_feedforward.z = (_vel_target.z - _vel_last.z)/_dt;
_accel_desired.z = (_vel_target.z - _vel_last.z)/_dt;
} else {
// stop the feed forward being calculated during a known discontinuity
_flags.freeze_ff_z = false;
}
} else {
_accel_feedforward.z = 0.0f;
_accel_desired.z = 0.0f;
}
// store this iteration's velocities for the next iteration
@ -594,7 +590,7 @@ void AC_PosControl::rate_to_accel_z()
p = _p_vel_z.kP() * _vel_error.z;
// consolidate and constrain target acceleration
_accel_target.z = _accel_feedforward.z + p;
_accel_target.z = _accel_desired.z + p;
// set target for accel based throttle controller
accel_to_throttle(_accel_target.z);
@ -700,11 +696,6 @@ void AC_PosControl::shift_pos_xy_target(float x_cm, float y_cm)
// move pos controller target
_pos_target.x += x_cm;
_pos_target.y += y_cm;
// disable feed forward
if (!is_zero(x_cm) || !is_zero(y_cm)) {
freeze_ff_xy();
}
}
/// set_target_to_stopping_point_xy - sets horizontal target to reasonable stopping position in cm from home
@ -797,12 +788,11 @@ void AC_PosControl::init_xy_controller(bool reset_I)
if (reset_I) {
// reset last velocity if this controller has just been engaged or dt is zero
lean_angles_to_accel(_accel_target.x, _accel_target.y);
_pid_vel_xy.set_integrator(_accel_target);
_pid_vel_xy.set_integrator(_accel_target-_accel_desired);
}
// flag reset required in rate to accel step
_flags.reset_desired_vel_to_pos = true;
_flags.reset_rate_to_accel_xy = true;
_flags.reset_accel_to_lean_xy = true;
// initialise ekf xy reset handler
@ -810,7 +800,7 @@ void AC_PosControl::init_xy_controller(bool reset_I)
}
/// update_xy_controller - run the horizontal position controller - should be called at 100hz or higher
void AC_PosControl::update_xy_controller(xy_mode mode, float ekfNavVelGainScaler, bool use_althold_lean_angle)
void AC_PosControl::update_xy_controller(float ekfNavVelGainScaler, bool use_althold_lean_angle)
{
// compute dt
uint32_t now = AP_HAL::millis();
@ -832,7 +822,7 @@ void AC_PosControl::update_xy_controller(xy_mode mode, float ekfNavVelGainScaler
desired_vel_to_pos(dt);
// run position controller's position error to desired velocity step
pos_to_rate_xy(mode, dt, ekfNavVelGainScaler);
pos_to_rate_xy(dt, ekfNavVelGainScaler);
// run position controller's velocity to acceleration step
rate_to_accel_xy(dt, ekfNavVelGainScaler);
@ -860,7 +850,6 @@ void AC_PosControl::init_vel_controller_xyz()
// flag reset required in rate to accel step
_flags.reset_desired_vel_to_pos = true;
_flags.reset_rate_to_accel_xy = true;
_flags.reset_accel_to_lean_xy = true;
// set target position
@ -901,10 +890,11 @@ void AC_PosControl::update_vel_controller_xy(float ekfNavVelGainScaler)
calc_leash_length_xy();
// apply desired velocity request to position target
// TODO: this will need to be removed and added to the calling function.
desired_vel_to_pos(dt);
// run position controller's position error to desired velocity step
pos_to_rate_xy(XY_MODE_POS_LIMITED_AND_VEL_FF, dt, ekfNavVelGainScaler);
pos_to_rate_xy(dt, ekfNavVelGainScaler);
// run velocity to acceleration step
rate_to_accel_xy(dt, ekfNavVelGainScaler);
@ -952,6 +942,23 @@ void AC_PosControl::calc_leash_length_xy()
}
}
/// move velocity target using desired acceleration
void AC_PosControl::desired_accel_to_vel(float nav_dt)
{
// range check nav_dt
if (nav_dt < 0) {
return;
}
// update target velocity
if (_flags.reset_desired_vel_to_pos) {
_flags.reset_desired_vel_to_pos = false;
} else {
_vel_desired.x += _accel_desired.x * nav_dt;
_vel_desired.y += _accel_desired.y * nav_dt;
}
}
/// desired_vel_to_pos - move position target using desired velocities
void AC_PosControl::desired_vel_to_pos(float nav_dt)
{
@ -974,10 +981,9 @@ void AC_PosControl::desired_vel_to_pos(float nav_dt)
/// when use_desired_rate is set to true:
/// desired velocity (_vel_desired) is combined into final target velocity and
/// velocity due to position error is reduce to a maximum of 1m/s
void AC_PosControl::pos_to_rate_xy(xy_mode mode, float dt, float ekfNavVelGainScaler)
void AC_PosControl::pos_to_rate_xy(float dt, float ekfNavVelGainScaler)
{
Vector3f curr_pos = _inav.get_position();
float linear_distance; // the distance we swap between linear and sqrt velocity response
float kP = ekfNavVelGainScaler * _p_pos_xy.kP(); // scale gains to compensate for noisy optical flow measurement in the EKF
// avoid divide by zero
@ -989,75 +995,29 @@ void AC_PosControl::pos_to_rate_xy(xy_mode mode, float dt, float ekfNavVelGainSc
_pos_error.x = _pos_target.x - curr_pos.x;
_pos_error.y = _pos_target.y - curr_pos.y;
// constrain target position to within reasonable distance of current location
// 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;
}
_distance_to_target = norm(_pos_error.x, _pos_error.y);
if (_distance_to_target > _leash && _distance_to_target > 0.0f) {
_pos_target.x = curr_pos.x + _leash * _pos_error.x/_distance_to_target;
_pos_target.y = curr_pos.y + _leash * _pos_error.y/_distance_to_target;
// re-calculate distance error
_pos_error.x = _pos_target.x - curr_pos.x;
_pos_error.y = _pos_target.y - curr_pos.y;
_distance_to_target = _leash;
}
// calculate the distance at which we swap between linear and sqrt velocity response
linear_distance = _accel_cms/(2.0f*kP*kP);
if (_distance_to_target > 2.0f*linear_distance) {
// velocity response grows with the square root of the distance
float vel_sqrt = safe_sqrt(2.0f*_accel_cms*(_distance_to_target-linear_distance));
_vel_target.x = vel_sqrt * _pos_error.x/_distance_to_target;
_vel_target.y = vel_sqrt * _pos_error.y/_distance_to_target;
}else{
// velocity response grows linearly with the distance
_vel_target.x = kP * _pos_error.x;
_vel_target.y = kP * _pos_error.y;
}
if (mode == XY_MODE_POS_LIMITED_AND_VEL_FF) {
// this mode is for loiter - rate-limiting the position correction
// allows the pilot to always override the position correction in
// the event of a disturbance
// scale velocity within limit
float vel_total = norm(_vel_target.x, _vel_target.y);
if (vel_total > POSCONTROL_VEL_XY_MAX_FROM_POS_ERR) {
_vel_target.x = POSCONTROL_VEL_XY_MAX_FROM_POS_ERR * _vel_target.x/vel_total;
_vel_target.y = POSCONTROL_VEL_XY_MAX_FROM_POS_ERR * _vel_target.y/vel_total;
}
// add velocity feed-forward
_vel_target.x += _vel_desired.x;
_vel_target.y += _vel_desired.y;
} else {
if (mode == XY_MODE_POS_AND_VEL_FF) {
// add velocity feed-forward
_vel_target.x += _vel_desired.x;
_vel_target.y += _vel_desired.y;
}
// scale velocity within speed limit
float vel_total = norm(_vel_target.x, _vel_target.y);
if (vel_total > _speed_cms) {
_vel_target.x = _speed_cms * _vel_target.x/vel_total;
_vel_target.y = _speed_cms * _vel_target.y/vel_total;
}
}
_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;
}
/// rate_to_accel_xy - horizontal desired rate to desired acceleration
/// converts desired velocities in lat/lon directions to accelerations in lat/lon frame
void AC_PosControl::rate_to_accel_xy(float dt, float ekfNavVelGainScaler)
{
Vector2f vel_xy_p, vel_xy_i, vel_xy_d;
// reset last velocity target to current target
if (_flags.reset_rate_to_accel_xy) {
_vel_last.x = _vel_target.x;
_vel_last.y = _vel_target.y;
_flags.reset_rate_to_accel_xy = false;
}
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) {
@ -1067,27 +1027,10 @@ void AC_PosControl::rate_to_accel_xy(float dt, float ekfNavVelGainScaler)
_vehicle_horiz_vel.y = _inav.get_velocity().y;
}
// feed forward desired acceleration calculation
if (dt > 0.0f) {
if (!_flags.freeze_ff_xy) {
_accel_feedforward.x = (_vel_target.x - _vel_last.x)/dt;
_accel_feedforward.y = (_vel_target.y - _vel_last.y)/dt;
} else {
// stop the feed forward being calculated during a known discontinuity
_flags.freeze_ff_xy = false;
}
} else {
_accel_feedforward.x = 0.0f;
_accel_feedforward.y = 0.0f;
}
// store this iteration's velocities for the next iteration
_vel_last.x = _vel_target.x;
_vel_last.y = _vel_target.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);
@ -1096,6 +1039,7 @@ void AC_PosControl::rate_to_accel_xy(float dt, float ekfNavVelGainScaler)
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 {
@ -1105,68 +1049,49 @@ void AC_PosControl::rate_to_accel_xy(float dt, float ekfNavVelGainScaler)
// get d
vel_xy_d = _pid_vel_xy.get_d();
// combine feed forward accel with PID output from velocity error and scale PID output to compensate for optical flow measurement induced EKF noise
_accel_target.x = _accel_feedforward.x + (vel_xy_p.x + vel_xy_i.x + vel_xy_d.x) * ekfNavVelGainScaler;
_accel_target.y = _accel_feedforward.y + (vel_xy_p.y + vel_xy_i.y + vel_xy_d.y) * ekfNavVelGainScaler;
// 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;
}
/// accel_to_lean_angles - horizontal desired acceleration to lean angles
/// converts desired accelerations provided in lat/lon frame to roll/pitch angles
void AC_PosControl::accel_to_lean_angles(float dt, float ekfNavVelGainScaler, bool use_althold_lean_angle)
{
float accel_total; // total acceleration in cm/s/s
float accel_right, accel_forward;
float lean_angle_max = _attitude_control.lean_angle_max();
float accel_max = POSCONTROL_ACCEL_XY_MAX;
// limit acceleration if necessary
if (use_althold_lean_angle) {
accel_max = MIN(accel_max, GRAVITY_MSS * 100.0f * tanf(ToRad(constrain_float(_attitude_control.get_althold_lean_angle_max(),1000,8000)/100.0f)));
}
// scale desired acceleration if it's beyond acceptable limit
accel_total = norm(_accel_target.x, _accel_target.y);
if (accel_total > accel_max && accel_total > 0.0f) {
_accel_target.x = accel_max * _accel_target.x/accel_total;
_accel_target.y = accel_max * _accel_target.y/accel_total;
_limit.accel_xy = true; // unused
} else {
// reset accel limit flag
_limit.accel_xy = false;
}
// reset accel to current desired acceleration
if (_flags.reset_accel_to_lean_xy) {
_accel_target_jerk_limited.x = _accel_target.x;
_accel_target_jerk_limited.y = _accel_target.y;
_accel_target_filter.reset(Vector2f(_accel_target.x, _accel_target.y));
_flags.reset_accel_to_lean_xy = false;
}
// apply jerk limit of 17 m/s^3 - equates to a worst case of about 100 deg/sec/sec
float max_delta_accel = dt * _jerk_cmsss;
Vector2f accel_in(_accel_target.x, _accel_target.y);
Vector2f accel_change = accel_in-_accel_target_jerk_limited;
float accel_change_length = accel_change.length();
if(accel_change_length > max_delta_accel) {
accel_change *= max_delta_accel/accel_change_length;
}
_accel_target_jerk_limited += accel_change;
// lowpass filter on NE accel
_accel_target_filter.set_cutoff_frequency(MIN(_accel_xy_filt_hz, 5.0f*ekfNavVelGainScaler));
Vector2f accel_target_filtered = _accel_target_filter.apply(_accel_target_jerk_limited, dt);
// limit acceleration using maximum lean angles
float angle_max = MIN(_attitude_control.get_althold_lean_angle_max(), _attitude_control.lean_angle_max());
float accel_max = GRAVITY_MSS * 100.0f * tanf(ToRad(angle_max * 0.01f));
_limit.accel_xy = limit_vector_length(_accel_target.x, _accel_target.y, accel_max);
// rotate accelerations into body forward-right frame
accel_forward = accel_target_filtered.x*_ahrs.cos_yaw() + accel_target_filtered.y*_ahrs.sin_yaw();
accel_right = -accel_target_filtered.x*_ahrs.sin_yaw() + accel_target_filtered.y*_ahrs.cos_yaw();
accel_forward = _accel_target.x*_ahrs.cos_yaw() + _accel_target.y*_ahrs.sin_yaw();
accel_right = -_accel_target.x*_ahrs.sin_yaw() + _accel_target.y*_ahrs.cos_yaw();
// update angle targets that will be passed to stabilize controller
_pitch_target = constrain_float(atanf(-accel_forward/(GRAVITY_MSS * 100))*(18000/M_PI),-lean_angle_max, lean_angle_max);
_pitch_target = atanf(-accel_forward/(GRAVITY_MSS * 100))*(18000/M_PI);
float cos_pitch_target = cosf(_pitch_target*M_PI/18000);
_roll_target = constrain_float(atanf(accel_right*cos_pitch_target/(GRAVITY_MSS * 100))*(18000/M_PI), -lean_angle_max, lean_angle_max);
_roll_target = atanf(accel_right*cos_pitch_target/(GRAVITY_MSS * 100))*(18000/M_PI);
}
// get_lean_angles_to_accel - convert roll, pitch lean angles to lat/lon frame accelerations in cm/s/s
@ -1246,3 +1171,34 @@ void AC_PosControl::check_for_ekf_z_reset()
_ekf_z_reset_ms = reset_ms;
}
}
/// limit vector to a given length, returns true if vector was limited
bool AC_PosControl::limit_vector_length(float& vector_x, float& vector_y, float max_length)
{
float vector_length = norm(vector_x, vector_y);
if ((vector_length > max_length) && is_positive(max_length)) {
vector_x *= (max_length / vector_length);
vector_y *= (max_length / vector_length);
return true;
}
return false;
}
/// Proportional controller with piecewise sqrt sections to constrain second derivative
Vector3f AC_PosControl::sqrt_controller(const Vector3f& error, float p, float second_ord_lim)
{
if (second_ord_lim < 0.0f || is_zero(second_ord_lim) || is_zero(p)) {
return Vector3f(error.x*p, error.y*p, error.z);
}
float linear_dist = second_ord_lim/sq(p);
float error_length = norm(error.x, error.y);
if (error_length > linear_dist) {
float first_order_scale = safe_sqrt(2.0f*second_ord_lim*(error_length-(linear_dist/2.0f)))/error_length;
return Vector3f(error.x*first_order_scale, error.y*first_order_scale, error.z);
} else {
return Vector3f(error.x*p, error.y*p, error.z);
}
}

40
libraries/AC_AttitudeControl/AC_PosControl.h
View File

@ -19,12 +19,10 @@
#define POSCONTROL_ACCEL_XY_MAX 980.0f // max horizontal acceleration in cm/s/s that the position velocity controller will ask from the lower accel controller
#define POSCONTROL_STOPPING_DIST_UP_MAX 300.0f // max stopping distance (in cm) vertically while climbing
#define POSCONTROL_STOPPING_DIST_DOWN_MAX 200.0f // max stopping distance (in cm) vertically while descending
#define POSCONTROL_JERK_LIMIT_CMSSS 1700.0f // default jerk limit on horizontal acceleration (unit: m/s/s/s)
#define POSCONTROL_SPEED 500.0f // default horizontal speed in cm/s
#define POSCONTROL_SPEED_DOWN -150.0f // default descent rate in cm/s
#define POSCONTROL_SPEED_UP 250.0f // default climb rate in cm/s
#define POSCONTROL_VEL_XY_MAX_FROM_POS_ERR 200.0f // max speed output from pos_to_vel controller when feed forward is used
#define POSCONTROL_ACCEL_Z 250.0f // default vertical acceleration in cm/s/s.
@ -50,13 +48,6 @@ public:
AC_PosControl(const AP_AHRS_View& ahrs, const AP_InertialNav& inav,
const AP_Motors& motors, AC_AttitudeControl& attitude_control);
// xy_mode - specifies behavior of xy position controller
enum xy_mode {
XY_MODE_POS_ONLY = 0, // position correction only (i.e. no velocity feed-forward)
XY_MODE_POS_LIMITED_AND_VEL_FF, // for loiter - rate-limiting the position correction, velocity feed-forward
XY_MODE_POS_AND_VEL_FF // for velocity controller - unlimited position correction, velocity feed-forward
};
///
/// initialisation functions
///
@ -185,10 +176,6 @@ public:
void set_speed_xy(float speed_cms);
float get_speed_xy() const { return _speed_cms; }
/// set_jerk_xy - set max horizontal jerk in cm/s/s/s
void set_jerk_xy(float jerk_cmsss) { _jerk_cmsss = jerk_cmsss; }
void set_jerk_xy_to_default() { _jerk_cmsss = POSCONTROL_JERK_LIMIT_CMSSS; }
/// set_limit_accel_xy - mark that accel has been limited
/// this prevents integrator buildup
void set_limit_accel_xy(void) { _limit.accel_xy = true; }
@ -218,6 +205,9 @@ public:
// clear desired velocity feed-forward in z axis
void clear_desired_velocity_ff_z() { _flags.use_desvel_ff_z = false; }
// set desired acceleration in cm/s in xy axis
void set_desired_accel_xy(float accel_lat_cms, float accel_lon_cms) { _accel_desired.x = accel_lat_cms; _accel_desired.y = accel_lon_cms; }
/// set_desired_velocity_xy - sets desired velocity in cm/s in lat and lon directions
/// when update_xy_controller is next called the position target is moved based on the desired velocity and
/// the desired velocities are fed forward into the rate_to_accel step
@ -225,7 +215,7 @@ public:
/// set_desired_velocity - sets desired velocity in cm/s in all 3 axis
/// when update_vel_controller_xyz is next called the position target is moved based on the desired velocity
void set_desired_velocity(const Vector3f &des_vel) { _vel_desired = des_vel; freeze_ff_xy(); }
void set_desired_velocity(const Vector3f &des_vel) { _vel_desired = des_vel; }
// overrides the velocity process variable for one timestep
void override_vehicle_velocity_xy(const Vector2f& vel_xy) { _vehicle_horiz_vel = vel_xy; _flags.vehicle_horiz_vel_override = true; }
@ -233,15 +223,12 @@ public:
/// freeze_ff_z - used to stop the feed forward being calculated during a known discontinuity
void freeze_ff_z() { _flags.freeze_ff_z = true; }
/// freeze_ff_xy - used to stop the feed forward being calculated during a known discontinuity
void freeze_ff_xy() { _flags.freeze_ff_xy = true; }
// is_active_xy - returns true if the xy position controller has been run very recently
bool is_active_xy() const;
/// update_xy_controller - run the horizontal position controller - should be called at 100hz or higher
/// when use_desired_velocity is true the desired velocity (i.e. feed forward) is incorporated at the pos_to_rate step
void update_xy_controller(xy_mode mode, float ekfNavVelGainScaler, bool use_althold_lean_angle);
void update_xy_controller(float ekfNavVelGainScaler, bool use_althold_lean_angle);
/// set_target_to_stopping_point_xy - sets horizontal target to reasonable stopping position in cm from home
void set_target_to_stopping_point_xy();
@ -309,11 +296,9 @@ protected:
uint16_t recalc_leash_z : 1; // 1 if we should recalculate the z axis leash length
uint16_t recalc_leash_xy : 1; // 1 if we should recalculate the xy axis leash length
uint16_t reset_desired_vel_to_pos : 1; // 1 if we should reset the rate_to_accel_xy step
uint16_t reset_rate_to_accel_xy : 1; // 1 if we should reset the rate_to_accel_xy step
uint16_t reset_accel_to_lean_xy : 1; // 1 if we should reset the accel to lean angle step
uint16_t reset_rate_to_accel_z : 1; // 1 if we should reset the rate_to_accel_z step
uint16_t reset_accel_to_throttle : 1; // 1 if we should reset the accel_to_throttle step of the z-axis controller
uint16_t freeze_ff_xy : 1; // 1 use to freeze feed forward during step updates
uint16_t freeze_ff_z : 1; // 1 used to freeze velocity to accel feed forward for one iteration
uint16_t use_desvel_ff_z : 1; // 1 to use z-axis desired velocity as feed forward into velocity step
uint16_t vehicle_horiz_vel_override : 1; // 1 if we should use _vehicle_horiz_vel as our velocity process variable for one timestep
@ -349,6 +334,9 @@ protected:
/// xy controller private methods
///
/// move velocity target using desired acceleration
void desired_accel_to_vel(float nav_dt);
/// desired_vel_to_pos - move position target using desired velocities
void desired_vel_to_pos(float nav_dt);
@ -357,7 +345,7 @@ protected:
/// when use_desired_rate is set to true:
/// desired velocity (_vel_desired) is combined into final target velocity and
/// velocity due to position error is reduce to a maximum of 1m/s
void pos_to_rate_xy(xy_mode mode, float dt, float ekfNavVelGainScaler);
void pos_to_rate_xy(float dt, float ekfNavVelGainScaler);
/// rate_to_accel_xy - horizontal desired rate to desired acceleration
/// converts desired velocities in lat/lon directions to accelerations in lat/lon frame
@ -370,6 +358,12 @@ protected:
/// calc_leash_length - calculates the horizontal leash length given a maximum speed, acceleration and position kP gain
float calc_leash_length(float speed_cms, float accel_cms, float kP) const;
/// limit vector to a given length, returns true if vector was limited
static bool limit_vector_length(float& vector_x, float& vector_y, float max_length);
/// Proportional controller with piecewise sqrt sections to constrain second derivative
static Vector3f sqrt_controller(const Vector3f& error, float p, float second_ord_lim);
/// initialise and check for ekf position resets
void init_ekf_xy_reset();
void check_for_ekf_xy_reset();
@ -401,7 +395,6 @@ protected:
float _accel_z_cms; // max vertical acceleration in cm/s/s
float _accel_last_z_cms; // max vertical acceleration in cm/s/s
float _accel_cms; // max horizontal acceleration in cm/s/s
float _jerk_cmsss; // max horizontal jerk in cm/s/s/s
float _leash; // horizontal leash length in cm. target will never be further than this distance from the vehicle
float _leash_down_z; // vertical leash down in cm. target will never be further than this distance below the vehicle
float _leash_up_z; // vertical leash up in cm. target will never be further than this distance above the vehicle
@ -417,14 +410,13 @@ protected:
Vector3f _vel_target; // velocity target in cm/s calculated by pos_to_rate step
Vector3f _vel_error; // error between desired and actual acceleration in cm/s
Vector3f _vel_last; // previous iterations velocity in cm/s
Vector3f _accel_feedforward; // feedforward acceleration in cm/s/s
Vector3f _accel_desired; // desired acceleration in cm/s/s (feed forward)
Vector3f _accel_target; // acceleration target in cm/s/s
Vector3f _accel_error; // acceleration error in cm/s/s
Vector2f _vehicle_horiz_vel; // velocity to use if _flags.vehicle_horiz_vel_override is set
float _distance_to_target; // distance to position target - for reporting only
LowPassFilterFloat _vel_error_filter; // low-pass-filter on z-axis velocity error
Vector2f _accel_target_jerk_limited; // acceleration target jerk limited to 100deg/s/s
LowPassFilterVector2f _accel_target_filter; // acceleration target filter
// ekf reset handling