mirror of https://github.com/ArduPilot/ardupilot
287 lines
12 KiB
C++
287 lines
12 KiB
C++
#include <AP_HAL/AP_HAL.h>
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#include "AC_Loiter.h"
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#include <AP_Vehicle/AP_Vehicle_Type.h>
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#include <AC_Avoidance/AC_Avoid.h>
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extern const AP_HAL::HAL& hal;
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#define LOITER_SPEED_DEFAULT 1250.0f // default loiter speed in cm/s
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#define LOITER_SPEED_MIN 20.0f // minimum loiter speed in cm/s
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#define LOITER_ACCEL_MAX_DEFAULT 500.0f // default acceleration in loiter mode
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#define LOITER_BRAKE_ACCEL_DEFAULT 250.0f // minimum acceleration in loiter mode
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#define LOITER_BRAKE_JERK_DEFAULT 500.0f // maximum jerk in cm/s/s/s in loiter mode
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#define LOITER_BRAKE_START_DELAY_DEFAULT 1.0f // delay (in seconds) before loiter braking begins after sticks are released
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#define LOITER_VEL_CORRECTION_MAX 200.0f // max speed used to correct position errors in loiter
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#define LOITER_POS_CORRECTION_MAX 200.0f // max position error in loiter
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#define LOITER_ACTIVE_TIMEOUT_MS 200 // loiter controller is considered active if it has been called within the past 200ms (0.2 seconds)
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const AP_Param::GroupInfo AC_Loiter::var_info[] = {
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// @Param: ANG_MAX
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// @DisplayName: Loiter pilot angle max
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// @Description{Copter, Sub}: Loiter maximum pilot requested lean angle. Set to zero for 2/3 of PSC_ANGLE_MAX/ANGLE_MAX. The maximum vehicle lean angle is still limited by PSC_ANGLE_MAX/ANGLE_MAX
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// @Description: Loiter maximum pilot requested lean angle. Set to zero for 2/3 of Q_P_ANGLE_MAX/Q_ANGLE_MAX. The maximum vehicle lean angle is still limited by Q_P_ANGLE_MAX/Q_ANGLE_MAX
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// @Units: deg
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// @Range: 0 45
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// @Increment: 1
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// @User: Advanced
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AP_GROUPINFO("ANG_MAX", 1, AC_Loiter, _angle_max, 0.0f),
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// @Param: SPEED
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// @DisplayName: Loiter Horizontal Maximum Speed
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// @Description: Defines the maximum speed in cm/s which the aircraft will travel horizontally while in loiter mode
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// @Units: cm/s
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// @Range: 20 3500
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// @Increment: 50
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// @User: Standard
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AP_GROUPINFO("SPEED", 2, AC_Loiter, _speed_cms, LOITER_SPEED_DEFAULT),
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// @Param: ACC_MAX
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// @DisplayName: Loiter maximum correction acceleration
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// @Description: Loiter maximum correction acceleration in cm/s/s. Higher values cause the copter to correct position errors more aggressively.
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// @Units: cm/s/s
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// @Range: 100 981
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// @Increment: 1
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// @User: Advanced
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AP_GROUPINFO("ACC_MAX", 3, AC_Loiter, _accel_cmss, LOITER_ACCEL_MAX_DEFAULT),
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// @Param: BRK_ACCEL
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// @DisplayName: Loiter braking acceleration
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// @Description: Loiter braking acceleration in cm/s/s. Higher values stop the copter more quickly when the stick is centered.
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// @Units: cm/s/s
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// @Range: 25 250
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// @Increment: 1
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// @User: Advanced
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AP_GROUPINFO("BRK_ACCEL", 4, AC_Loiter, _brake_accel_cmss, LOITER_BRAKE_ACCEL_DEFAULT),
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// @Param: BRK_JERK
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// @DisplayName: Loiter braking jerk
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// @Description: Loiter braking jerk in cm/s/s/s. Higher values will remove braking faster if the pilot moves the sticks during a braking maneuver.
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// @Units: cm/s/s/s
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// @Range: 500 5000
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// @Increment: 1
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// @User: Advanced
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AP_GROUPINFO("BRK_JERK", 5, AC_Loiter, _brake_jerk_max_cmsss, LOITER_BRAKE_JERK_DEFAULT),
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// @Param: BRK_DELAY
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// @DisplayName: Loiter brake start delay (in seconds)
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// @Description: Loiter brake start delay (in seconds)
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// @Units: s
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// @Range: 0 2
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// @Increment: 0.1
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// @User: Advanced
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AP_GROUPINFO("BRK_DELAY", 6, AC_Loiter, _brake_delay, LOITER_BRAKE_START_DELAY_DEFAULT),
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AP_GROUPEND
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};
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// Default constructor.
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// Note that the Vector/Matrix constructors already implicitly zero
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// their values.
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//
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AC_Loiter::AC_Loiter(const AP_InertialNav& inav, const AP_AHRS_View& ahrs, AC_PosControl& pos_control, const AC_AttitudeControl& attitude_control) :
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_inav(inav),
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_ahrs(ahrs),
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_pos_control(pos_control),
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_attitude_control(attitude_control)
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{
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AP_Param::setup_object_defaults(this, var_info);
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}
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/// init_target to a position in cm from ekf origin
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void AC_Loiter::init_target(const Vector2f& position)
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{
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sanity_check_params();
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// initialise position controller speed and acceleration
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_pos_control.set_correction_speed_accel_xy(LOITER_VEL_CORRECTION_MAX, _accel_cmss);
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_pos_control.set_pos_error_max_xy_cm(LOITER_POS_CORRECTION_MAX);
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// initialise position controller
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_pos_control.init_xy_controller_stopping_point();
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// initialise desired acceleration and angles to zero to remain on station
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_predicted_accel.zero();
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_desired_accel.zero();
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_predicted_euler_angle.zero();
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_brake_accel = 0.0f;
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// set target position
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_pos_control.set_pos_desired_xy_cm(position);
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}
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/// initialize's position and feed-forward velocity from current pos and velocity
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void AC_Loiter::init_target()
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{
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sanity_check_params();
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// initialise position controller speed and acceleration
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_pos_control.set_correction_speed_accel_xy(LOITER_VEL_CORRECTION_MAX, _accel_cmss);
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_pos_control.set_pos_error_max_xy_cm(LOITER_POS_CORRECTION_MAX);
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// initialise position controller and move target accelerations smoothly towards zero
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_pos_control.relax_velocity_controller_xy();
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// initialise predicted acceleration and angles from the position controller
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_predicted_accel = _pos_control.get_accel_target_cmss().xy();
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_predicted_euler_angle.x = radians(_pos_control.get_roll_cd()*0.01f);
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_predicted_euler_angle.y = radians(_pos_control.get_pitch_cd()*0.01f);
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_brake_accel = 0.0f;
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}
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/// reduce response for landing
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void AC_Loiter::soften_for_landing()
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{
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_pos_control.soften_for_landing_xy();
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}
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/// set pilot desired acceleration in centi-degrees
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// dt should be the time (in seconds) since the last call to this function
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void AC_Loiter::set_pilot_desired_acceleration(float euler_roll_angle_cd, float euler_pitch_angle_cd)
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{
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const float dt = _attitude_control.get_dt();
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// Convert from centidegrees on public interface to radians
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const float euler_roll_angle = radians(euler_roll_angle_cd * 0.01f);
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const float euler_pitch_angle = radians(euler_pitch_angle_cd * 0.01f);
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// convert our desired attitude to an acceleration vector assuming we are not accelerating vertically
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const Vector3f desired_euler {euler_roll_angle, euler_pitch_angle, _ahrs.yaw};
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const Vector3f desired_accel = _pos_control.lean_angles_to_accel(desired_euler);
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_desired_accel.x = desired_accel.x;
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_desired_accel.y = desired_accel.y;
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// difference between where we think we should be and where we want to be
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Vector2f angle_error(wrap_PI(euler_roll_angle - _predicted_euler_angle.x), wrap_PI(euler_pitch_angle - _predicted_euler_angle.y));
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// calculate the angular velocity that we would expect given our desired and predicted attitude
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_attitude_control.input_shaping_rate_predictor(angle_error, _predicted_euler_rate, dt);
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// update our predicted attitude based on our predicted angular velocity
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_predicted_euler_angle += _predicted_euler_rate * dt;
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// convert our predicted attitude to an acceleration vector assuming we are not accelerating vertically
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const Vector3f predicted_euler {_predicted_euler_angle.x, _predicted_euler_angle.y, _ahrs.yaw};
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const Vector3f predicted_accel = _pos_control.lean_angles_to_accel(predicted_euler);
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_predicted_accel.x = predicted_accel.x;
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_predicted_accel.y = predicted_accel.y;
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}
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/// get vector to stopping point based on a horizontal position and velocity
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void AC_Loiter::get_stopping_point_xy(Vector2f& stopping_point) const
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{
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Vector2p stop;
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_pos_control.get_stopping_point_xy_cm(stop);
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stopping_point = stop.tofloat();
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}
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/// get maximum lean angle when using loiter
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float AC_Loiter::get_angle_max_cd() const
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{
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if (!is_positive(_angle_max)) {
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return MIN(_attitude_control.lean_angle_max_cd(), _pos_control.get_lean_angle_max_cd()) * (2.0f/3.0f);
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}
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return MIN(_angle_max*100.0f, _pos_control.get_lean_angle_max_cd());
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}
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/// run the loiter controller
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void AC_Loiter::update(bool avoidance_on)
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{
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calc_desired_velocity(avoidance_on);
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_pos_control.update_xy_controller();
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}
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// sanity check parameters
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void AC_Loiter::sanity_check_params()
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{
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_speed_cms.set(MAX(_speed_cms, LOITER_SPEED_MIN));
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_accel_cmss.set(MIN(_accel_cmss, GRAVITY_MSS * 100.0f * tanf(ToRad(_attitude_control.lean_angle_max_cd() * 0.01f))));
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}
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/// calc_desired_velocity - updates desired velocity (i.e. feed forward) with pilot requested acceleration and fake wind resistance
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/// updated velocity sent directly to position controller
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void AC_Loiter::calc_desired_velocity(bool avoidance_on)
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{
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float ekfGndSpdLimit, ahrsControlScaleXY;
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AP::ahrs().getControlLimits(ekfGndSpdLimit, ahrsControlScaleXY);
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const float dt = _pos_control.get_dt();
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// calculate a loiter speed limit which is the minimum of the value set by the LOITER_SPEED
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// parameter and the value set by the EKF to observe optical flow limits
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float gnd_speed_limit_cms = MIN(_speed_cms, ekfGndSpdLimit * 100.0f);
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gnd_speed_limit_cms = MAX(gnd_speed_limit_cms, LOITER_SPEED_MIN);
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float pilot_acceleration_max = angle_to_accel(get_angle_max_cd() * 0.01) * 100;
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// range check dt
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if (is_negative(dt)) {
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return;
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}
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// get loiters desired velocity from the position controller where it is being stored.
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Vector2f desired_vel = _pos_control.get_vel_desired_cms().xy();
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// update the desired velocity using our predicted acceleration
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desired_vel += _predicted_accel * dt;
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Vector2f loiter_accel_brake;
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float desired_speed = desired_vel.length();
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if (!is_zero(desired_speed)) {
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Vector2f desired_vel_norm = desired_vel / desired_speed;
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// calculate a drag acceleration based on the desired speed.
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float drag_decel = pilot_acceleration_max * desired_speed / gnd_speed_limit_cms;
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// calculate a braking acceleration if sticks are at zero
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float loiter_brake_accel = 0.0f;
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if (_desired_accel.is_zero()) {
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if ((AP_HAL::millis() - _brake_timer) > _brake_delay * 1000.0f) {
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float brake_gain = _pos_control.get_vel_xy_pid().kP() * 0.5f;
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loiter_brake_accel = constrain_float(sqrt_controller(desired_speed, brake_gain, _brake_jerk_max_cmsss, dt), 0.0f, _brake_accel_cmss);
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}
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} else {
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loiter_brake_accel = 0.0f;
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_brake_timer = AP_HAL::millis();
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}
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_brake_accel += constrain_float(loiter_brake_accel - _brake_accel, -_brake_jerk_max_cmsss * dt, _brake_jerk_max_cmsss * dt);
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loiter_accel_brake = desired_vel_norm * _brake_accel;
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// update the desired velocity using the drag and braking accelerations
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desired_speed = MAX(desired_speed - (drag_decel + _brake_accel) * dt, 0.0f);
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desired_vel = desired_vel_norm * desired_speed;
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}
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// add braking to the desired acceleration
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_desired_accel -= loiter_accel_brake;
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// Apply EKF limit to desired velocity - this limit is calculated by the EKF and adjusted as required to ensure certain sensor limits are respected (eg optical flow sensing)
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float horizSpdDem = desired_vel.length();
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if (horizSpdDem > gnd_speed_limit_cms) {
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desired_vel = desired_vel * gnd_speed_limit_cms / horizSpdDem;
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}
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#if AP_AVOIDANCE_ENABLED && !APM_BUILD_TYPE(APM_BUILD_ArduPlane)
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if (avoidance_on) {
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// Limit the velocity to prevent fence violations
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// TODO: We need to also limit the _desired_accel
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AC_Avoid *_avoid = AP::ac_avoid();
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if (_avoid != nullptr) {
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Vector3f avoidance_vel_3d{desired_vel.x, desired_vel.y, 0.0f};
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_avoid->adjust_velocity(avoidance_vel_3d, _pos_control.get_pos_xy_p().kP(), _accel_cmss, _pos_control.get_pos_z_p().kP(), _pos_control.get_max_accel_z_cmss(), dt);
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desired_vel = Vector2f{avoidance_vel_3d.x, avoidance_vel_3d.y};
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}
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}
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#endif // !APM_BUILD_ArduPlane
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// get loiters desired velocity from the position controller where it is being stored.
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Vector2p desired_pos = _pos_control.get_pos_desired_cm().xy();
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// update the desired position using our desired velocity and acceleration
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desired_pos += (desired_vel * dt).topostype();
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// send adjusted feed forward acceleration and velocity back to the Position Controller
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_pos_control.set_pos_vel_accel_xy(desired_pos, desired_vel, _desired_accel);
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}
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