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ardupilot/libraries/AC_AttitudeControl/AC_PosControl.cpp

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#include <AP_HAL/AP_HAL.h>
#include "AC_PosControl.h"
#include <AP_Math/AP_Math.h>
#include <AP_Logger/AP_Logger.h>
#include <AP_Motors/AP_Motors.h> // motors library
#include <AP_Vehicle/AP_Vehicle.h>
extern const AP_HAL::HAL& hal;
#if APM_BUILD_TYPE(APM_BUILD_ArduPlane)
// default gains for Plane
# define POSCONTROL_POS_Z_P 1.0f // vertical position controller P gain default
# define POSCONTROL_VEL_Z_P 5.0f // vertical velocity controller P gain default
# define POSCONTROL_VEL_Z_IMAX 1000.0f // vertical velocity controller IMAX gain default
# define POSCONTROL_VEL_Z_FILT_HZ 5.0f // vertical velocity controller input filter
# define POSCONTROL_VEL_Z_FILT_D_HZ 5.0f // vertical velocity controller input filter for D
# define POSCONTROL_ACC_Z_P 0.3f // vertical acceleration controller P gain default
# define POSCONTROL_ACC_Z_I 1.0f // vertical acceleration controller I gain default
# define POSCONTROL_ACC_Z_D 0.0f // vertical acceleration controller D gain default
# define POSCONTROL_ACC_Z_IMAX 800 // vertical acceleration controller IMAX gain default
# define POSCONTROL_ACC_Z_FILT_HZ 10.0f // vertical acceleration controller input filter default
# define POSCONTROL_ACC_Z_DT 0.02f // vertical acceleration controller dt default
# define POSCONTROL_POS_XY_P 0.5f // horizontal position controller P gain default
# define POSCONTROL_VEL_XY_P 0.7f // horizontal velocity controller P gain default
# define POSCONTROL_VEL_XY_I 0.35f // horizontal velocity controller I gain default
# define POSCONTROL_VEL_XY_D 0.17f // horizontal velocity controller D gain default
# define POSCONTROL_VEL_XY_IMAX 1000.0f // horizontal velocity controller IMAX gain default
# define POSCONTROL_VEL_XY_FILT_HZ 5.0f // horizontal velocity controller input filter
# define POSCONTROL_VEL_XY_FILT_D_HZ 5.0f // horizontal velocity controller input filter for D
#elif APM_BUILD_TYPE(APM_BUILD_ArduSub)
// default gains for Sub
# define POSCONTROL_POS_Z_P 3.0f // vertical position controller P gain default
# define POSCONTROL_VEL_Z_P 8.0f // vertical velocity controller P gain default
# define POSCONTROL_VEL_Z_IMAX 1000.0f // vertical velocity controller IMAX gain default
# define POSCONTROL_VEL_Z_FILT_HZ 5.0f // vertical velocity controller input filter
# define POSCONTROL_VEL_Z_FILT_D_HZ 5.0f // vertical velocity controller input filter for D
# define POSCONTROL_ACC_Z_P 0.5f // vertical acceleration controller P gain default
# define POSCONTROL_ACC_Z_I 0.1f // vertical acceleration controller I gain default
# define POSCONTROL_ACC_Z_D 0.0f // vertical acceleration controller D gain default
# define POSCONTROL_ACC_Z_IMAX 100 // vertical acceleration controller IMAX gain default
# define POSCONTROL_ACC_Z_FILT_HZ 20.0f // vertical acceleration controller input filter default
# define POSCONTROL_ACC_Z_DT 0.0025f // vertical acceleration controller dt default
# define POSCONTROL_POS_XY_P 1.0f // horizontal position controller P gain default
# define POSCONTROL_VEL_XY_P 1.0f // horizontal velocity controller P gain default
# define POSCONTROL_VEL_XY_I 0.5f // horizontal velocity controller I gain default
# define POSCONTROL_VEL_XY_D 0.0f // horizontal velocity controller D gain default
# define POSCONTROL_VEL_XY_IMAX 1000.0f // horizontal velocity controller IMAX gain default
# define POSCONTROL_VEL_XY_FILT_HZ 5.0f // horizontal velocity controller input filter
# define POSCONTROL_VEL_XY_FILT_D_HZ 5.0f // horizontal velocity controller input filter for D
#else
// default gains for Copter / TradHeli
# define POSCONTROL_POS_Z_P 1.0f // vertical position controller P gain default
# define POSCONTROL_VEL_Z_P 5.0f // vertical velocity controller P gain default
# define POSCONTROL_VEL_Z_IMAX 1000.0f // vertical velocity controller IMAX gain default
# define POSCONTROL_VEL_Z_FILT_HZ 5.0f // vertical velocity controller input filter
# define POSCONTROL_VEL_Z_FILT_D_HZ 5.0f // vertical velocity controller input filter for D
# define POSCONTROL_ACC_Z_P 0.5f // vertical acceleration controller P gain default
# define POSCONTROL_ACC_Z_I 1.0f // vertical acceleration controller I gain default
# define POSCONTROL_ACC_Z_D 0.0f // vertical acceleration controller D gain default
# define POSCONTROL_ACC_Z_IMAX 800 // vertical acceleration controller IMAX gain default
# define POSCONTROL_ACC_Z_FILT_HZ 20.0f // vertical acceleration controller input filter default
# define POSCONTROL_ACC_Z_DT 0.0025f // vertical acceleration controller dt default
# define POSCONTROL_POS_XY_P 1.0f // horizontal position controller P gain default
# define POSCONTROL_VEL_XY_P 2.0f // horizontal velocity controller P gain default
# define POSCONTROL_VEL_XY_I 1.0f // horizontal velocity controller I gain default
# define POSCONTROL_VEL_XY_D 0.5f // horizontal velocity controller D gain default
# define POSCONTROL_VEL_XY_IMAX 1000.0f // horizontal velocity controller IMAX gain default
# define POSCONTROL_VEL_XY_FILT_HZ 5.0f // horizontal velocity controller input filter
# define POSCONTROL_VEL_XY_FILT_D_HZ 5.0f // horizontal velocity controller input filter for D
#endif
// vibration compensation gains
#define POSCONTROL_VIBE_COMP_P_GAIN 0.250f
#define POSCONTROL_VIBE_COMP_I_GAIN 0.125f
const AP_Param::GroupInfo AC_PosControl::var_info[] = {
// 0 was used for HOVER
// @Param: _ACC_XY_FILT
// @DisplayName: XY Acceleration filter cutoff frequency
// @Description: Lower values will slow the response of the navigation controller and reduce twitchiness
// @Units: Hz
// @Range: 0.5 5
// @Increment: 0.1
// @User: Advanced
// @Param: _POSZ_P
// @DisplayName: Position (vertical) controller P gain
// @Description: Position (vertical) controller P gain. Converts the difference between the desired altitude and actual altitude into a climb or descent rate which is passed to the throttle rate controller
// @Range: 1.000 3.000
// @User: Standard
AP_SUBGROUPINFO(_p_pos_z, "_POSZ_", 2, AC_PosControl, AC_P_1D),
// @Param: _VELZ_P
// @DisplayName: Velocity (vertical) controller P gain
// @Description: Velocity (vertical) controller P gain. Converts the difference between desired vertical speed and actual speed into a desired acceleration that is passed to the throttle acceleration controller
// @Range: 1.000 8.000
// @User: Standard
// @Param: _VELZ_I
// @DisplayName: Velocity (vertical) controller I gain
// @Description: Velocity (vertical) controller I gain. Corrects long-term difference in desired velocity to a target acceleration
// @Range: 0.02 1.00
// @Increment: 0.01
// @User: Advanced
// @Param: _VELZ_IMAX
// @DisplayName: Velocity (vertical) controller I gain maximum
// @Description: Velocity (vertical) controller I gain maximum. Constrains the target acceleration that the I gain will output
// @Range: 1.000 8.000
// @User: Standard
// @Param: _VELZ_D
// @DisplayName: Velocity (vertical) controller D gain
// @Description: Velocity (vertical) controller D gain. Corrects short-term changes in velocity
// @Range: 0.00 1.00
// @Increment: 0.001
// @User: Advanced
// @Param: _VELZ_FF
// @DisplayName: Velocity (vertical) controller Feed Forward gain
// @Description: Velocity (vertical) controller Feed Forward gain. Produces an output that is proportional to the magnitude of the target
// @Range: 0 1
// @Increment: 0.01
// @User: Advanced
// @Param: _VELZ_FLTE
// @DisplayName: Velocity (vertical) error filter
// @Description: Velocity (vertical) error filter. This filter (in Hz) is applied to the input for P and I terms
// @Range: 0 100
// @Units: Hz
// @User: Advanced
// @Param: _VELZ_FLTD
// @DisplayName: Velocity (vertical) input filter for D term
// @Description: Velocity (vertical) input filter for D term. This filter (in Hz) is applied to the input for D terms
// @Range: 0 100
// @Units: Hz
// @User: Advanced
AP_SUBGROUPINFO(_pid_vel_z, "_VELZ_", 3, AC_PosControl, AC_PID_Basic),
// @Param: _ACCZ_P
// @DisplayName: Acceleration (vertical) controller P gain
// @Description: Acceleration (vertical) controller P gain. Converts the difference between desired vertical acceleration and actual acceleration into a motor output
// @Range: 0.200 1.500
// @Increment: 0.05
// @User: Standard
// @Param: _ACCZ_I
// @DisplayName: Acceleration (vertical) controller I gain
// @Description: Acceleration (vertical) controller I gain. Corrects long-term difference in desired vertical acceleration and actual acceleration
// @Range: 0.000 3.000
// @User: Standard
// @Param: _ACCZ_IMAX
// @DisplayName: Acceleration (vertical) controller I gain maximum
// @Description: Acceleration (vertical) controller I gain maximum. Constrains the maximum pwm that the I term will generate
// @Range: 0 1000
// @Units: d%
// @User: Standard
// @Param: _ACCZ_D
// @DisplayName: Acceleration (vertical) controller D gain
// @Description: Acceleration (vertical) controller D gain. Compensates for short-term change in desired vertical acceleration vs actual acceleration
// @Range: 0.000 0.400
// @User: Standard
// @Param: _ACCZ_FF
// @DisplayName: Acceleration (vertical) controller feed forward
// @Description: Acceleration (vertical) controller feed forward
// @Range: 0 0.5
// @Increment: 0.001
// @User: Standard
// @Param: _ACCZ_FLTT
// @DisplayName: Acceleration (vertical) controller target frequency in Hz
// @Description: Acceleration (vertical) controller target frequency in Hz
// @Range: 1 50
// @Increment: 1
// @Units: Hz
// @User: Standard
// @Param: _ACCZ_FLTE
// @DisplayName: Acceleration (vertical) controller error frequency in Hz
// @Description: Acceleration (vertical) controller error frequency in Hz
// @Range: 1 100
// @Increment: 1
// @Units: Hz
// @User: Standard
// @Param: _ACCZ_FLTD
// @DisplayName: Acceleration (vertical) controller derivative frequency in Hz
// @Description: Acceleration (vertical) controller derivative frequency in Hz
// @Range: 1 100
// @Increment: 1
// @Units: Hz
// @User: Standard
// @Param: _ACCZ_SMAX
// @DisplayName: Accel (vertical) slew rate limit
// @Description: Sets an upper limit on the slew rate produced by the combined P and D gains. If the amplitude of the control action produced by the rate feedback exceeds this value, then the D+P gain is reduced to respect the limit. This limits the amplitude of high frequency oscillations caused by an excessive gain. The limit should be set to no more than 25% of the actuators maximum slew rate to allow for load effects. Note: The gain will not be reduced to less than 10% of the nominal value. A value of zero will disable this feature.
// @Range: 0 200
// @Increment: 0.5
// @User: Advanced
AP_SUBGROUPINFO(_pid_accel_z, "_ACCZ_", 4, AC_PosControl, AC_PID),
// @Param: _POSXY_P
// @DisplayName: Position (horizontal) controller P gain
// @Description: Position controller P gain. Converts the distance (in the latitude direction) to the target location into a desired speed which is then passed to the loiter latitude rate controller
// @Range: 0.500 2.000
// @User: Standard
AP_SUBGROUPINFO(_p_pos_xy, "_POSXY_", 5, AC_PosControl, AC_P_2D),
// @Param: _VELXY_P
// @DisplayName: Velocity (horizontal) P gain
// @Description: Velocity (horizontal) P gain. Converts the difference between desired and actual velocity to a target acceleration
// @Range: 0.1 6.0
// @Increment: 0.1
// @User: Advanced
// @Param: _VELXY_I
// @DisplayName: Velocity (horizontal) I gain
// @Description: Velocity (horizontal) I gain. Corrects long-term difference between desired and actual velocity to a target acceleration
// @Range: 0.02 1.00
// @Increment: 0.01
// @User: Advanced
// @Param: _VELXY_D
// @DisplayName: Velocity (horizontal) D gain
// @Description: Velocity (horizontal) D gain. Corrects short-term changes in velocity
// @Range: 0.00 1.00
// @Increment: 0.001
// @User: Advanced
// @Param: _VELXY_IMAX
// @DisplayName: Velocity (horizontal) integrator maximum
// @Description: Velocity (horizontal) integrator maximum. Constrains the target acceleration that the I gain will output
// @Range: 0 4500
// @Increment: 10
// @Units: cm/s/s
// @User: Advanced
// @Param: _VELXY_FLTE
// @DisplayName: Velocity (horizontal) input filter
// @Description: Velocity (horizontal) input filter. This filter (in Hz) is applied to the input for P and I terms
// @Range: 0 100
// @Units: Hz
// @User: Advanced
// @Param: _VELXY_FLTD
// @DisplayName: Velocity (horizontal) input filter
// @Description: Velocity (horizontal) input filter. This filter (in Hz) is applied to the input for D term
// @Range: 0 100
// @Units: Hz
// @User: Advanced
// @Param: _VELXY_FF
// @DisplayName: Velocity (horizontal) feed forward gain
// @Description: Velocity (horizontal) feed forward gain. Converts the difference between desired velocity to a target acceleration
// @Range: 0 6
// @Increment: 0.01
// @User: Advanced
AP_SUBGROUPINFO(_pid_vel_xy, "_VELXY_", 6, AC_PosControl, AC_PID_2D),
// @Param: _ANGLE_MAX
// @DisplayName: Position Control Angle Max
// @Description: Maximum lean angle autopilot can request. Set to zero to use ANGLE_MAX parameter value
// @Units: deg
// @Range: 0 45
// @Increment: 1
// @User: Advanced
AP_GROUPINFO("_ANGLE_MAX", 7, AC_PosControl, _lean_angle_max, 0.0f),
// IDs 8,9 used for _TC_XY and _TC_Z in beta release candidate
// @Param: _JERK_XY
// @DisplayName: Jerk limit for the horizontal kinematic input shaping
// @Description: Jerk limit of the horizontal kinematic path generation used to determine how quickly the aircraft varies the acceleration target
// @Units: m/s/s/s
// @Range: 1 20
// @Increment: 1
// @User: Advanced
AP_GROUPINFO("_JERK_XY", 10, AC_PosControl, _shaping_jerk_xy, POSCONTROL_JERK_XY),
// @Param: _JERK_Z
// @DisplayName: Jerk limit for the vertical kinematic input shaping
// @Description: Jerk limit of the vertical kinematic path generation used to determine how quickly the aircraft varies the acceleration target
// @Units: m/s/s/s
// @Range: 5 50
// @Increment: 1
// @User: Advanced
AP_GROUPINFO("_JERK_Z", 11, AC_PosControl, _shaping_jerk_z, POSCONTROL_JERK_Z),
AP_GROUPEND
};
// Default constructor.
// Note that the Vector/Matrix constructors already implicitly zero
// their values.
//
AC_PosControl::AC_PosControl(AP_AHRS_View& ahrs, const AP_InertialNav& inav,
const AP_Motors& motors, AC_AttitudeControl& attitude_control, float dt) :
_ahrs(ahrs),
_inav(inav),
_motors(motors),
_attitude_control(attitude_control),
_p_pos_z(POSCONTROL_POS_Z_P, dt),
_pid_vel_z(POSCONTROL_VEL_Z_P, 0.0f, 0.0f, 0.0f, POSCONTROL_VEL_Z_IMAX, POSCONTROL_VEL_Z_FILT_HZ, POSCONTROL_VEL_Z_FILT_D_HZ, dt),
_pid_accel_z(POSCONTROL_ACC_Z_P, POSCONTROL_ACC_Z_I, POSCONTROL_ACC_Z_D, 0.0f, POSCONTROL_ACC_Z_IMAX, 0.0f, POSCONTROL_ACC_Z_FILT_HZ, 0.0f, dt),
_p_pos_xy(POSCONTROL_POS_XY_P, dt),
_pid_vel_xy(POSCONTROL_VEL_XY_P, POSCONTROL_VEL_XY_I, POSCONTROL_VEL_XY_D, 0.0f, POSCONTROL_VEL_XY_IMAX, POSCONTROL_VEL_XY_FILT_HZ, POSCONTROL_VEL_XY_FILT_D_HZ, dt),
_dt(dt),
_vel_max_down_cms(POSCONTROL_SPEED_DOWN),
_vel_max_up_cms(POSCONTROL_SPEED_UP),
_vel_max_xy_cms(POSCONTROL_SPEED),
_accel_max_z_cmss(POSCONTROL_ACCEL_Z),
_accel_max_xy_cmss(POSCONTROL_ACCEL_XY),
_jerk_max_xy_cmsss(POSCONTROL_JERK_XY * 100.0),
_jerk_max_z_cmsss(POSCONTROL_JERK_Z * 100.0)
{
AP_Param::setup_object_defaults(this, var_info);
}
///
/// 3D position shaper
///
/// input_pos_xyz - calculate a jerk limited path from the current position, velocity and acceleration to an input position.
/// The function takes the current position, velocity, and acceleration and calculates the required jerk limited adjustment to the acceleration for the next time dt.
/// The kinematic path is constrained by the maximum jerk parameter and the velocity and acceleration limits set using the function set_max_speed_accel_xy.
/// The jerk limit defines the acceleration error decay in the kinematic path as the system approaches constant acceleration.
/// The jerk limit also defines the time taken to achieve the maximum acceleration.
/// The function alters the input velocity to be the velocity that the system could reach zero acceleration in the minimum time.
void AC_PosControl::input_pos_xyz(const Vector3p& pos, float pos_offset_z, float pos_offset_z_buffer)
{
// Terrain following velocity scalar must be calculated before we remove the position offset
const float offset_z_scaler = pos_offset_z_scaler(pos_offset_z, pos_offset_z_buffer);
// remove terrain offsets for flat earth assumption
_pos_target.z -= _pos_offset_z;
_vel_desired.z -= _vel_offset_z;
_accel_desired.z -= _accel_offset_z;
// calculated increased maximum acceleration and jerk if over speed
float accel_max_z_cmss = _accel_max_z_cmss * calculate_overspeed_gain();
float jerk_max_z_cmsss = _jerk_max_z_cmsss * calculate_overspeed_gain();
update_pos_vel_accel_xy(_pos_target.xy(), _vel_desired.xy(), _accel_desired.xy(), _dt, _limit_vector.xy(), _p_pos_xy.get_error(), _pid_vel_xy.get_error());
// adjust desired altitude if motors have not hit their limits
update_pos_vel_accel(_pos_target.z, _vel_desired.z, _accel_desired.z, _dt, _limit_vector.z, _p_pos_z.get_error(), _pid_vel_z.get_error());
// calculate the horizontal and vertical velocity limits to travel directly to the destination defined by pos
float vel_max_xy_cms = 0.0f;
float vel_max_z_cms = 0.0f;
Vector3f dest_vector = (pos - _pos_target).tofloat();
if (is_positive(dest_vector.length_squared()) ) {
dest_vector.normalize();
float dest_vector_xy_length = dest_vector.xy().length();
float vel_max_cms = kinematic_limit(dest_vector, _vel_max_xy_cms, _vel_max_up_cms, _vel_max_down_cms);
vel_max_xy_cms = vel_max_cms * dest_vector_xy_length;
vel_max_z_cms = fabsf(vel_max_cms * dest_vector.z);
}
// reduce speed if we are reaching the edge of our vertical buffer
vel_max_xy_cms *= offset_z_scaler;
Vector2f vel;
Vector2f accel;
shape_pos_vel_accel_xy(pos.xy(), vel, accel, _pos_target.xy(), _vel_desired.xy(), _accel_desired.xy(),
vel_max_xy_cms, _accel_max_xy_cmss, _jerk_max_xy_cmsss, _dt, false);
float posz = pos.z;
shape_pos_vel_accel(posz, 0, 0,
_pos_target.z, _vel_desired.z, _accel_desired.z,
-vel_max_z_cms, vel_max_z_cms,
-constrain_float(accel_max_z_cmss, 0.0f, 750.0f), accel_max_z_cmss,
jerk_max_z_cmsss, _dt, false);
// update the vertical position, velocity and acceleration offsets
update_pos_offset_z(pos_offset_z);
// add terrain offsets
_pos_target.z += _pos_offset_z;
_vel_desired.z += _vel_offset_z;
_accel_desired.z += _accel_offset_z;
}
/// pos_offset_z_scaler - calculates a multiplier used to reduce the horizontal velocity to allow the z position controller to stay within the provided buffer range
float AC_PosControl::pos_offset_z_scaler(float pos_offset_z, float pos_offset_z_buffer) const
{
if (is_zero(pos_offset_z_buffer)) {
return 1.0;
}
float pos_offset_error_z = _inav.get_position_z_up_cm() - (_pos_target.z - _pos_offset_z + pos_offset_z);
return constrain_float((1.0 - (fabsf(pos_offset_error_z) - 0.5 * pos_offset_z_buffer) / (0.5 * pos_offset_z_buffer)), 0.01, 1.0);
}
///
/// Lateral position controller
///
/// set_max_speed_accel_xy - set the maximum horizontal speed in cm/s and acceleration in cm/s/s
/// This function only needs to be called if using the kinematic shaping.
/// This can be done at any time as changes in these parameters are handled smoothly
/// by the kinematic shaping.
void AC_PosControl::set_max_speed_accel_xy(float speed_cms, float accel_cmss)
{
_vel_max_xy_cms = speed_cms;
_accel_max_xy_cmss = accel_cmss;
// ensure the horizontal jerk is less than the vehicle is capable of
const float jerk_max_cmsss = MIN(_attitude_control.get_ang_vel_roll_max_rads(), _attitude_control.get_ang_vel_pitch_max_rads()) * GRAVITY_MSS * 100.0;
const float snap_max_cmssss = MIN(_attitude_control.get_accel_roll_max_radss(), _attitude_control.get_accel_pitch_max_radss()) * GRAVITY_MSS * 100.0;
// get specified jerk limit
_jerk_max_xy_cmsss = _shaping_jerk_xy * 100.0;
// limit maximum jerk based on maximum angular rate
if (is_positive(jerk_max_cmsss) && _attitude_control.get_bf_feedforward()) {
_jerk_max_xy_cmsss = MIN(_jerk_max_xy_cmsss, jerk_max_cmsss);
}
// limit maximum jerk to maximum possible average jerk based on angular acceleration
if (is_positive(snap_max_cmssss) && _attitude_control.get_bf_feedforward()) {
_jerk_max_xy_cmsss = MIN(0.5 * safe_sqrt(_accel_max_xy_cmss * snap_max_cmssss), _jerk_max_xy_cmsss);
}
}
/// set_max_speed_accel_xy - set the position controller correction velocity and acceleration limit
/// This should be done only during initialisation to avoid discontinuities
void AC_PosControl::set_correction_speed_accel_xy(float speed_cms, float accel_cmss)
{
_p_pos_xy.set_limits(speed_cms, accel_cmss, 0.0f);
}
/// init_xy_controller_stopping_point - initialise the position controller to the stopping point with zero velocity and acceleration.
/// This function should be used when the expected kinematic path assumes a stationary initial condition but does not specify a specific starting position.
/// The starting position can be retrieved by getting the position target using get_pos_target_cm() after calling this function.
void AC_PosControl::init_xy_controller_stopping_point()
{
init_xy_controller();
get_stopping_point_xy_cm(_pos_target.xy());
_vel_desired.xy().zero();
_accel_desired.xy().zero();
_pid_vel_xy.set_integrator(_accel_target);
}
// relax_velocity_controller_xy - initialise the position controller to the current position and velocity with decaying acceleration.
/// This function decays the output acceleration by 95% every half second to achieve a smooth transition to zero requested acceleration.
void AC_PosControl::relax_velocity_controller_xy()
{
init_xy_controller();
// decay resultant acceleration and therefore current attitude target to zero
float decay = 1.0 - _dt / (_dt + POSCONTROL_RELAX_TC);
_accel_target.xy() *= decay;
_pid_vel_xy.set_integrator(_accel_target - _accel_desired);
}
/// reduce response for landing
void AC_PosControl::soften_for_landing_xy()
{
// decay position error to zero
_pos_target.xy() += (_inav.get_position_xy_cm().topostype() - _pos_target.xy()) * (_dt / (_dt + POSCONTROL_RELAX_TC));
// Prevent I term build up in xy velocity controller.
// Note that this flag is reset on each loop in update_xy_controller()
set_externally_limited_xy();
}
/// init_xy_controller - initialise the position controller to the current position, velocity, acceleration and attitude.
/// This function is the default initialisation for any position control that provides position, velocity and acceleration.
void AC_PosControl::init_xy_controller()
{
// set roll, pitch lean angle targets to current attitude
const Vector3f &att_target_euler_cd = _attitude_control.get_att_target_euler_cd();
_roll_target = att_target_euler_cd.x;
_pitch_target = att_target_euler_cd.y;
_yaw_target = att_target_euler_cd.z; // todo: this should be thrust vector heading, not yaw.
_yaw_rate_target = 0.0f;
_angle_max_override_cd = 0.0;
_pos_target.xy() = _inav.get_position_xy_cm().topostype();
const Vector2f &curr_vel = _inav.get_velocity_xy_cms();
_vel_desired.xy() = curr_vel;
_vel_target.xy() = curr_vel;
// Set desired accel to zero because raw acceleration is prone to noise
_accel_desired.xy().zero();
lean_angles_to_accel_xy(_accel_target.x, _accel_target.y);
// limit acceleration using maximum lean angles
float angle_max = MIN(_attitude_control.get_althold_lean_angle_max_cd(), get_lean_angle_max_cd());
float accel_max = angle_to_accel(angle_max * 0.01) * 100.0;
_accel_target.xy().limit_length(accel_max);
// initialise I terms from lean angles
_pid_vel_xy.reset_filter();
// initialise the I term to _accel_target - _accel_desired
// _accel_desired is zero and can be removed from the equation
_pid_vel_xy.set_integrator(_accel_target);
// initialise ekf xy reset handler
init_ekf_xy_reset();
// initialise z_controller time out
_last_update_xy_us = AP_HAL::micros64();
}
/// input_accel_xy - calculate a jerk limited path from the current position, velocity and acceleration to an input acceleration.
/// The function takes the current position, velocity, and acceleration and calculates the required jerk limited adjustment to the acceleration for the next time dt.
/// The kinematic path is constrained by the maximum acceleration and jerk set using the function set_max_speed_accel_xy.
/// The jerk limit defines the acceleration error decay in the kinematic path as the system approaches constant acceleration.
/// The jerk limit also defines the time taken to achieve the maximum acceleration.
void AC_PosControl::input_accel_xy(const Vector3f& accel)
{
// check for ekf xy position reset
handle_ekf_xy_reset();
update_pos_vel_accel_xy(_pos_target.xy(), _vel_desired.xy(), _accel_desired.xy(), _dt, _limit_vector.xy(), _p_pos_xy.get_error(), _pid_vel_xy.get_error());
shape_accel_xy(accel, _accel_desired, _jerk_max_xy_cmsss, _dt);
}
/// input_vel_accel_xy - calculate a jerk limited path from the current position, velocity and acceleration to an input velocity and acceleration.
/// The vel is projected forwards in time based on a time step of dt and acceleration accel.
/// The function takes the current position, velocity, and acceleration and calculates the required jerk limited adjustment to the acceleration for the next time dt.
/// The kinematic path is constrained by the maximum acceleration and jerk set using the function set_max_speed_accel_xy.
/// The parameter limit_output specifies if the velocity and acceleration limits are applied to the sum of commanded and correction values or just correction.
void AC_PosControl::input_vel_accel_xy(Vector2f& vel, const Vector2f& accel, bool limit_output)
{
update_pos_vel_accel_xy(_pos_target.xy(), _vel_desired.xy(), _accel_desired.xy(), _dt, _limit_vector.xy(), _p_pos_xy.get_error(), _pid_vel_xy.get_error());
shape_vel_accel_xy(vel, accel, _vel_desired.xy(), _accel_desired.xy(),
_accel_max_xy_cmss, _jerk_max_xy_cmsss, _dt, limit_output);
update_vel_accel_xy(vel, accel, _dt, Vector2f(), Vector2f());
}
/// input_pos_vel_accel_xy - calculate a jerk limited path from the current position, velocity and acceleration to an input position velocity and acceleration.
/// The pos and vel are projected forwards in time based on a time step of dt and acceleration accel.
/// The function takes the current position, velocity, and acceleration and calculates the required jerk limited adjustment to the acceleration for the next time dt.
/// The function alters the pos and vel to be the kinematic path based on accel
/// The parameter limit_output specifies if the velocity and acceleration limits are applied to the sum of commanded and correction values or just correction.
void AC_PosControl::input_pos_vel_accel_xy(Vector2p& pos, Vector2f& vel, const Vector2f& accel, bool limit_output)
{
update_pos_vel_accel_xy(_pos_target.xy(), _vel_desired.xy(), _accel_desired.xy(), _dt, _limit_vector.xy(), _p_pos_xy.get_error(), _pid_vel_xy.get_error());
shape_pos_vel_accel_xy(pos, vel, accel, _pos_target.xy(), _vel_desired.xy(), _accel_desired.xy(),
_vel_max_xy_cms, _accel_max_xy_cmss, _jerk_max_xy_cmsss, _dt, limit_output);
update_pos_vel_accel_xy(pos, vel, accel, _dt, Vector2f(), Vector2f(), Vector2f());
}
/// stop_pos_xy_stabilisation - sets the target to the current position to remove any position corrections from the system
void AC_PosControl::stop_pos_xy_stabilisation()
{
_pos_target.xy() = _inav.get_position_xy_cm().topostype();
}
/// stop_vel_xy_stabilisation - sets the target to the current position and velocity to the current velocity to remove any position and velocity corrections from the system
void AC_PosControl::stop_vel_xy_stabilisation()
{
_pos_target.xy() = _inav.get_position_xy_cm().topostype();
const Vector2f &curr_vel = _inav.get_velocity_xy_cms();
_vel_desired.xy() = curr_vel;
// with zero position error _vel_target = _vel_desired
_vel_target.xy() = curr_vel;
// initialise I terms from lean angles
_pid_vel_xy.reset_filter();
_pid_vel_xy.reset_I();
}
// is_active_xy - returns true if the xy position controller has been run in the previous 5 loop times
bool AC_PosControl::is_active_xy() const
{
return ((AP_HAL::micros64() - _last_update_xy_us) <= _dt * 5000000.0);
}
/// update_xy_controller - runs the horizontal position controller correcting position, velocity and acceleration errors.
/// Position and velocity errors are converted to velocity and acceleration targets using PID objects
/// Desired velocity and accelerations are added to these corrections as they are calculated
/// Kinematically consistent target position and desired velocity and accelerations should be provided before calling this function
void AC_PosControl::update_xy_controller()
{
// check for ekf xy position reset
handle_ekf_xy_reset();
// Check for position control time out
if (!is_active_xy()) {
init_xy_controller();
if (has_good_timing()) {
// call internal error because initialisation has not been done
INTERNAL_ERROR(AP_InternalError::error_t::flow_of_control);
}
}
_last_update_xy_us = AP_HAL::micros64();
float ahrsGndSpdLimit, ahrsControlScaleXY;
AP::ahrs().getControlLimits(ahrsGndSpdLimit, ahrsControlScaleXY);
// Position Controller
const Vector3f &curr_pos = _inav.get_position_neu_cm();
Vector2f vel_target = _p_pos_xy.update_all(_pos_target.x, _pos_target.y, curr_pos);
// add velocity feed-forward scaled to compensate for optical flow measurement induced EKF noise
vel_target *= ahrsControlScaleXY;
_vel_target.xy() = vel_target;
_vel_target.xy() += _vel_desired.xy();
// Velocity Controller
const Vector2f &curr_vel = _inav.get_velocity_xy_cms();
Vector2f accel_target = _pid_vel_xy.update_all(_vel_target.xy(), curr_vel, _limit_vector.xy());
// acceleration to correct for velocity error and scale PID output to compensate for optical flow measurement induced EKF noise
accel_target *= ahrsControlScaleXY;
// pass the correction acceleration to the target acceleration output
_accel_target.xy() = accel_target;
// Add feed forward into the target acceleration output
_accel_target.xy() += _accel_desired.xy();
// Acceleration Controller
// limit acceleration using maximum lean angles
float angle_max = MIN(_attitude_control.get_althold_lean_angle_max_cd(), get_lean_angle_max_cd());
float accel_max = angle_to_accel(angle_max * 0.01) * 100;
// Define the limit vector before we constrain _accel_target
_limit_vector.xy() = _accel_target.xy();
if (!limit_accel_xy(_vel_desired.xy(), _accel_target.xy(), accel_max)) {
// _accel_target was not limited so we can zero the xy limit vector
_limit_vector.xy().zero();
}
// update angle targets that will be passed to stabilize controller
accel_to_lean_angles(_accel_target.x, _accel_target.y, _roll_target, _pitch_target);
calculate_yaw_and_rate_yaw();
}
///
/// Vertical position controller
///
/// set_max_speed_accel_z - set the maximum vertical speed in cm/s and acceleration in cm/s/s
/// speed_down can be positive or negative but will always be interpreted as a descent speed.
/// This function only needs to be called if using the kinematic shaping.
/// This can be done at any time as changes in these parameters are handled smoothly
/// by the kinematic shaping.
void AC_PosControl::set_max_speed_accel_z(float speed_down, float speed_up, float accel_cmss)
{
// ensure speed_down is always negative
speed_down = -fabsf(speed_down);
// sanity check and update
if (is_negative(speed_down)) {
_vel_max_down_cms = speed_down;
}
if (is_positive(speed_up)) {
_vel_max_up_cms = speed_up;
}
if (is_positive(accel_cmss)) {
_accel_max_z_cmss = accel_cmss;
}
// ensure the vertical Jerk is not limited by the filters in the Z accel PID object
_jerk_max_z_cmsss = _shaping_jerk_z * 100.0;
if (is_positive(_pid_accel_z.filt_T_hz())) {
_jerk_max_z_cmsss = MIN(_jerk_max_z_cmsss, MIN(GRAVITY_MSS * 100.0, _accel_max_z_cmss) * (M_2PI * _pid_accel_z.filt_T_hz()) / 5.0);
}
if (is_positive(_pid_accel_z.filt_E_hz())) {
_jerk_max_z_cmsss = MIN(_jerk_max_z_cmsss, MIN(GRAVITY_MSS * 100.0, _accel_max_z_cmss) * (M_2PI * _pid_accel_z.filt_E_hz()) / 5.0);
}
}
/// set_correction_speed_accel_z - set the position controller correction velocity and acceleration limit
/// speed_down can be positive or negative but will always be interpreted as a descent speed.
/// This should be done only during initialisation to avoid discontinuities
void AC_PosControl::set_correction_speed_accel_z(float speed_down, float speed_up, float accel_cmss)
{
// define maximum position error and maximum first and second differential limits
_p_pos_z.set_limits(-fabsf(speed_down), speed_up, accel_cmss, 0.0f);
}
/// init_z_controller - initialise the position controller to the current position, velocity, acceleration and attitude.
/// This function is the default initialisation for any position control that provides position, velocity and acceleration.
/// This function does not allow any negative velocity or acceleration
void AC_PosControl::init_z_controller_no_descent()
{
// Initialise the position controller to the current throttle, position, velocity and acceleration.
init_z_controller();
// remove all descent if present
_vel_desired.z = MAX(0.0, _vel_desired.z);
_vel_target.z = MAX(0.0, _vel_target.z);
_accel_desired.z = MAX(0.0, _accel_desired.z);
_accel_target.z = MAX(0.0, _accel_target.z);
}
/// init_z_controller_stopping_point - initialise the position controller to the stopping point with zero velocity and acceleration.
/// This function should be used when the expected kinematic path assumes a stationary initial condition but does not specify a specific starting position.
/// The starting position can be retrieved by getting the position target using get_pos_target_cm() after calling this function.
void AC_PosControl::init_z_controller_stopping_point()
{
// Initialise the position controller to the current throttle, position, velocity and acceleration.
init_z_controller();
get_stopping_point_z_cm(_pos_target.z);
_vel_desired.z = 0.0f;
_accel_desired.z = 0.0f;
}
// relax_z_controller - initialise the position controller to the current position and velocity with decaying acceleration.
/// This function decays the output acceleration by 95% every half second to achieve a smooth transition to zero requested acceleration.
void AC_PosControl::relax_z_controller(float throttle_setting)
{
// Initialise the position controller to the current position, velocity and acceleration.
init_z_controller();
// init_z_controller has set the accel PID I term to generate the current throttle set point
// Use relax_integrator to decay the throttle set point to throttle_setting
_pid_accel_z.relax_integrator((throttle_setting - _motors.get_throttle_hover()) * 1000.0f, POSCONTROL_RELAX_TC);
}
/// init_z_controller - initialise the position controller to the current position, velocity, acceleration and attitude.
/// This function is the default initialisation for any position control that provides position, velocity and acceleration.
/// This function is private and contains all the shared z axis initialisation functions
void AC_PosControl::init_z_controller()
{
_pos_target.z = _inav.get_position_z_up_cm();
const float curr_vel_z = _inav.get_velocity_z_up_cms();
_vel_desired.z = curr_vel_z;
// with zero position error _vel_target = _vel_desired
_vel_target.z = curr_vel_z;
// Reset I term of velocity PID
_pid_vel_z.reset_filter();
_pid_vel_z.set_integrator(0.0f);
_accel_desired.z = constrain_float(get_z_accel_cmss(), -_accel_max_z_cmss, _accel_max_z_cmss);
// with zero position error _accel_target = _accel_desired
_accel_target.z = _accel_desired.z;
_pid_accel_z.reset_filter();
// initialise vertical offsets
_pos_offset_target_z = 0.0;
_pos_offset_z = 0.0;
_vel_offset_z = 0.0;
_accel_offset_z = 0.0;
// Set accel PID I term based on the current throttle
// Remove the expected P term due to _accel_desired.z being constrained to _accel_max_z_cmss
// Remove the expected FF term due to non-zero _accel_target.z
_pid_accel_z.set_integrator((_attitude_control.get_throttle_in() - _motors.get_throttle_hover()) * 1000.0f
- _pid_accel_z.kP() * (_accel_target.z - get_z_accel_cmss())
- _pid_accel_z.ff() * _accel_target.z);
// initialise ekf z reset handler
init_ekf_z_reset();
// initialise z_controller time out
_last_update_z_us = AP_HAL::micros64();
}
/// input_vel_accel_z - calculate a jerk limited path from the current position, velocity and acceleration to an input velocity and acceleration.
/// The vel is projected forwards in time based on a time step of dt and acceleration accel.
/// The function takes the current position, velocity, and acceleration and calculates the required jerk limited adjustment to the acceleration for the next time dt.
/// The function alters the vel to be the kinematic path based on accel
void AC_PosControl::input_accel_z(float accel)
{
// calculated increased maximum jerk if over speed
float jerk_max_z_cmsss = _jerk_max_z_cmsss * calculate_overspeed_gain();
// adjust desired alt if motors have not hit their limits
update_pos_vel_accel(_pos_target.z, _vel_desired.z, _accel_desired.z, _dt, _limit_vector.z, _p_pos_z.get_error(), _pid_vel_z.get_error());
shape_accel(accel, _accel_desired.z, jerk_max_z_cmsss, _dt);
}
/// input_accel_z - calculate a jerk limited path from the current position, velocity and acceleration to an input acceleration.
/// The function takes the current position, velocity, and acceleration and calculates the required jerk limited adjustment to the acceleration for the next time dt.
/// The kinematic path is constrained by the maximum acceleration and jerk set using the function set_max_speed_accel_z.
/// The parameter limit_output specifies if the velocity and acceleration limits are applied to the sum of commanded and correction values or just correction.
void AC_PosControl::input_vel_accel_z(float &vel, float accel, bool ignore_descent_limit, bool limit_output)
{
if (ignore_descent_limit) {
// turn off limits in the negative z direction
_limit_vector.z = MAX(_limit_vector.z, 0.0f);
}
// calculated increased maximum acceleration and jerk if over speed
float accel_max_z_cmss = _accel_max_z_cmss * calculate_overspeed_gain();
float jerk_max_z_cmsss = _jerk_max_z_cmsss * calculate_overspeed_gain();
// adjust desired alt if motors have not hit their limits
update_pos_vel_accel(_pos_target.z, _vel_desired.z, _accel_desired.z, _dt, _limit_vector.z, _p_pos_z.get_error(), _pid_vel_z.get_error());
shape_vel_accel(vel, accel,
_vel_desired.z, _accel_desired.z,
-constrain_float(accel_max_z_cmss, 0.0f, 750.0f), accel_max_z_cmss,
jerk_max_z_cmsss, _dt, limit_output);
update_vel_accel(vel, accel, _dt, 0.0, 0.0);
}
/// set_pos_target_z_from_climb_rate_cm - adjusts target up or down using a commanded climb rate in cm/s
/// using the default position control kinematic path.
/// The zero target altitude is varied to follow pos_offset_z
void AC_PosControl::set_pos_target_z_from_climb_rate_cm(float vel)
{
// remove terrain offsets for flat earth assumption
_pos_target.z -= _pos_offset_z;
_vel_desired.z -= _vel_offset_z;
_accel_desired.z -= _accel_offset_z;
float vel_temp = vel;
input_vel_accel_z(vel_temp, 0, false);
// update the vertical position, velocity and acceleration offsets
update_pos_offset_z(_pos_offset_target_z);
// add terrain offsets
_pos_target.z += _pos_offset_z;
_vel_desired.z += _vel_offset_z;
_accel_desired.z += _accel_offset_z;
}
/// land_at_climb_rate_cm - adjusts target up or down using a commanded climb rate in cm/s
/// using the default position control kinematic path.
/// ignore_descent_limit turns off output saturation handling to aid in landing detection. ignore_descent_limit should be false unless landing.
void AC_PosControl::land_at_climb_rate_cm(float vel, bool ignore_descent_limit)
{
input_vel_accel_z(vel, 0, ignore_descent_limit);
}
/// input_pos_vel_accel_z - calculate a jerk limited path from the current position, velocity and acceleration to an input position velocity and acceleration.
/// The pos and vel are projected forwards in time based on a time step of dt and acceleration accel.
/// The function takes the current position, velocity, and acceleration and calculates the required jerk limited adjustment to the acceleration for the next time dt.
/// The function alters the pos and vel to be the kinematic path based on accel
/// The parameter limit_output specifies if the velocity and acceleration limits are applied to the sum of commanded and correction values or just correction.
void AC_PosControl::input_pos_vel_accel_z(float &pos, float &vel, float accel, bool limit_output)
{
// calculated increased maximum acceleration and jerk if over speed
float accel_max_z_cmss = _accel_max_z_cmss * calculate_overspeed_gain();
float jerk_max_z_cmsss = _jerk_max_z_cmsss * calculate_overspeed_gain();
// adjust desired altitude if motors have not hit their limits
update_pos_vel_accel(_pos_target.z, _vel_desired.z, _accel_desired.z, _dt, _limit_vector.z, _p_pos_z.get_error(), _pid_vel_z.get_error());
shape_pos_vel_accel(pos, vel, accel,
_pos_target.z, _vel_desired.z, _accel_desired.z,
_vel_max_down_cms, _vel_max_up_cms,
-constrain_float(accel_max_z_cmss, 0.0f, 750.0f), accel_max_z_cmss,
jerk_max_z_cmsss, _dt, limit_output);
postype_t posp = pos;
update_pos_vel_accel(posp, vel, accel, _dt, 0.0, 0.0, 0.0);
pos = posp;
}
/// set_alt_target_with_slew - adjusts target up or down using a commanded altitude in cm
/// using the default position control kinematic path.
void AC_PosControl::set_alt_target_with_slew(float pos)
{
float zero = 0;
input_pos_vel_accel_z(pos, zero, 0);
}
/// update_pos_offset_z - updates the vertical offsets used by terrain following
void AC_PosControl::update_pos_offset_z(float pos_offset_z)
{
postype_t p_offset_z = _pos_offset_z;
update_pos_vel_accel(p_offset_z, _vel_offset_z, _accel_offset_z, _dt, MIN(_limit_vector.z, 0.0f), _p_pos_z.get_error(), _pid_vel_z.get_error());
_pos_offset_z = p_offset_z;
// input shape the terrain offset
shape_pos_vel_accel(pos_offset_z, 0.0f, 0.0f,
_pos_offset_z, _vel_offset_z, _accel_offset_z,
get_max_speed_down_cms(), get_max_speed_up_cms(),
-get_max_accel_z_cmss(), get_max_accel_z_cmss(),
_jerk_max_z_cmsss, _dt, false);
}
// is_active_z - returns true if the z position controller has been run in the previous 5 loop times
bool AC_PosControl::is_active_z() const
{
return ((AP_HAL::micros64() - _last_update_z_us) <= _dt * 5000000.0);
}
/// update_z_controller - runs the vertical position controller correcting position, velocity and acceleration errors.
/// Position and velocity errors are converted to velocity and acceleration targets using PID objects
/// Desired velocity and accelerations are added to these corrections as they are calculated
/// Kinematically consistent target position and desired velocity and accelerations should be provided before calling this function
void AC_PosControl::update_z_controller()
{
// check for ekf z-axis position reset
handle_ekf_z_reset();
// Check for z_controller time out
if (!is_active_z()) {
init_z_controller();
if (has_good_timing()) {
// call internal error because initialisation has not been done
INTERNAL_ERROR(AP_InternalError::error_t::flow_of_control);
}
}
_last_update_z_us = AP_HAL::micros64();
// calculate the target velocity correction
float pos_target_zf = _pos_target.z;
_vel_target.z = _p_pos_z.update_all(pos_target_zf, _inav.get_position_z_up_cm());
_vel_target.z *= AP::ahrs().getControlScaleZ();
_pos_target.z = pos_target_zf;
// add feed forward component
_vel_target.z += _vel_desired.z;
// Velocity Controller
const float curr_vel_z = _inav.get_velocity_z_up_cms();
_accel_target.z = _pid_vel_z.update_all(_vel_target.z, curr_vel_z, _motors.limit.throttle_lower, _motors.limit.throttle_upper);
_accel_target.z *= AP::ahrs().getControlScaleZ();
// add feed forward component
_accel_target.z += _accel_desired.z;
// Acceleration Controller
// Calculate vertical acceleration
const float z_accel_meas = get_z_accel_cmss();
// ensure imax is always large enough to overpower hover throttle
if (_motors.get_throttle_hover() * 1000.0f > _pid_accel_z.imax()) {
_pid_accel_z.imax(_motors.get_throttle_hover() * 1000.0f);
}
float thr_out;
if (_vibe_comp_enabled) {
thr_out = get_throttle_with_vibration_override();
} else {
thr_out = _pid_accel_z.update_all(_accel_target.z, z_accel_meas, (_motors.limit.throttle_lower || _motors.limit.throttle_upper)) * 0.001f;
thr_out += _pid_accel_z.get_ff() * 0.001f;
}
thr_out += _motors.get_throttle_hover();
// Actuator commands
// send throttle to attitude controller with angle boost
_attitude_control.set_throttle_out(thr_out, true, POSCONTROL_THROTTLE_CUTOFF_FREQ_HZ);
// Check for vertical controller health
// _speed_down_cms is checked to be non-zero when set
float error_ratio = _pid_vel_z.get_error() / _vel_max_down_cms;
_vel_z_control_ratio += _dt * 0.1f * (0.5 - error_ratio);
_vel_z_control_ratio = constrain_float(_vel_z_control_ratio, 0.0f, 2.0f);
// set vertical component of the limit vector
if (_motors.limit.throttle_upper) {
_limit_vector.z = 1.0f;
} else if (_motors.limit.throttle_lower) {
_limit_vector.z = -1.0f;
} else {
_limit_vector.z = 0.0f;
}
}
///
/// Accessors
///
/// get_lean_angle_max_cd - returns the maximum lean angle the autopilot may request
float AC_PosControl::get_lean_angle_max_cd() const
{
if (is_positive(_angle_max_override_cd)) {
return _angle_max_override_cd;
}
if (!is_positive(_lean_angle_max)) {
return _attitude_control.lean_angle_max_cd();
}
return _lean_angle_max * 100.0f;
}
/// set position, velocity and acceleration targets
void AC_PosControl::set_pos_vel_accel(const Vector3p& pos, const Vector3f& vel, const Vector3f& accel)
{
_pos_target = pos;
_vel_desired = vel;
_accel_desired = accel;
}
/// set position, velocity and acceleration targets
void AC_PosControl::set_pos_vel_accel_xy(const Vector2p& pos, const Vector2f& vel, const Vector2f& accel)
{
_pos_target.xy() = pos;
_vel_desired.xy() = vel;
_accel_desired.xy() = accel;
}
// get_lean_angles_to_accel - convert roll, pitch lean target angles to lat/lon frame accelerations in cm/s/s
Vector3f AC_PosControl::lean_angles_to_accel(const Vector3f& att_target_euler) const
{
// rotate our roll, pitch angles into lat/lon frame
const float sin_roll = sinf(att_target_euler.x);
const float cos_roll = cosf(att_target_euler.x);
const float sin_pitch = sinf(att_target_euler.y);
const float cos_pitch = cosf(att_target_euler.y);
const float sin_yaw = sinf(att_target_euler.z);
const float cos_yaw = cosf(att_target_euler.z);
return Vector3f{
(GRAVITY_MSS * 100) * (-cos_yaw * sin_pitch * cos_roll - sin_yaw * sin_roll) / MAX(cos_roll * cos_pitch, 0.1f),
(GRAVITY_MSS * 100) * (-sin_yaw * sin_pitch * cos_roll + cos_yaw * sin_roll) / MAX(cos_roll * cos_pitch, 0.1f),
(GRAVITY_MSS * 100)
};
}
// returns the NED target acceleration vector for attitude control
Vector3f AC_PosControl::get_thrust_vector() const
{
Vector3f accel_target = get_accel_target_cmss();
accel_target.z = -GRAVITY_MSS * 100.0f;
return accel_target;
}
/// get_stopping_point_xy_cm - calculates stopping point in NEU cm based on current position, velocity, vehicle acceleration
/// function does not change the z axis
void AC_PosControl::get_stopping_point_xy_cm(Vector2p &stopping_point) const
{
stopping_point = _inav.get_position_xy_cm().topostype();
float kP = _p_pos_xy.kP();
Vector2f curr_vel = _inav.get_velocity_xy_cms();
// calculate current velocity
float vel_total = curr_vel.length();
if (!is_positive(vel_total)) {
return;
}
const float stopping_dist = stopping_distance(constrain_float(vel_total, 0.0, _vel_max_xy_cms), kP, _accel_max_xy_cmss);
if (!is_positive(stopping_dist)) {
return;
}
// convert the stopping distance into a stopping point using velocity vector
const float t = stopping_dist / vel_total;
stopping_point += (curr_vel * t).topostype();
}
/// get_stopping_point_z_cm - calculates stopping point in NEU cm based on current position, velocity, vehicle acceleration
void AC_PosControl::get_stopping_point_z_cm(postype_t &stopping_point) const
{
const float curr_pos_z = _inav.get_position_z_up_cm();
// avoid divide by zero by using current position if kP is very low or acceleration is zero
if (!is_positive(_p_pos_z.kP()) || !is_positive(_accel_max_z_cmss)) {
stopping_point = curr_pos_z;
return;
}
stopping_point = curr_pos_z + constrain_float(stopping_distance(_inav.get_velocity_z_up_cms(), _p_pos_z.kP(), _accel_max_z_cmss), - POSCONTROL_STOPPING_DIST_DOWN_MAX, POSCONTROL_STOPPING_DIST_UP_MAX);
}
/// get_bearing_to_target_cd - get bearing to target position in centi-degrees
int32_t AC_PosControl::get_bearing_to_target_cd() const
{
return get_bearing_cd(_inav.get_position_xy_cm(), _pos_target.tofloat().xy());
}
///
/// System methods
///
// get throttle using vibration-resistant calculation (uses feed forward with manually calculated gain)
float AC_PosControl::get_throttle_with_vibration_override()
{
const float thr_per_accelz_cmss = _motors.get_throttle_hover() / (GRAVITY_MSS * 100.0f);
// during vibration compensation use feed forward with manually calculated gain
// ToDo: clear pid_info P, I and D terms for logging
if (!(_motors.limit.throttle_lower || _motors.limit.throttle_upper) || ((is_positive(_pid_accel_z.get_i()) && is_negative(_pid_vel_z.get_error())) || (is_negative(_pid_accel_z.get_i()) && is_positive(_pid_vel_z.get_error())))) {
_pid_accel_z.set_integrator(_pid_accel_z.get_i() + _dt * thr_per_accelz_cmss * 1000.0f * _pid_vel_z.get_error() * _pid_vel_z.kP() * POSCONTROL_VIBE_COMP_I_GAIN);
}
return POSCONTROL_VIBE_COMP_P_GAIN * thr_per_accelz_cmss * _accel_target.z + _pid_accel_z.get_i() * 0.001f;
}
/// standby_xyz_reset - resets I terms and removes position error
/// This function will let Loiter and Alt Hold continue to operate
/// in the event that the flight controller is in control of the
/// aircraft when in standby.
void AC_PosControl::standby_xyz_reset()
{
// Set _pid_accel_z integrator to zero.
_pid_accel_z.set_integrator(0.0f);
// Set the target position to the current pos.
_pos_target = _inav.get_position_neu_cm().topostype();
// Set _pid_vel_xy integrator and derivative to zero.
_pid_vel_xy.reset_filter();
// initialise ekf xy reset handler
init_ekf_xy_reset();
}
// write PSC and/or PSCZ logs
void AC_PosControl::write_log()
{
if (is_active_xy()) {
float accel_x, accel_y;
lean_angles_to_accel_xy(accel_x, accel_y);
AP::logger().Write_PSCN(get_pos_target_cm().x, _inav.get_position_neu_cm().x,
get_vel_desired_cms().x, get_vel_target_cms().x, _inav.get_velocity_neu_cms().x,
_accel_desired.x, get_accel_target_cmss().x, accel_x);
AP::logger().Write_PSCE(get_pos_target_cm().y, _inav.get_position_neu_cm().y,
get_vel_desired_cms().y, get_vel_target_cms().y, _inav.get_velocity_neu_cms().y,
_accel_desired.y, get_accel_target_cmss().y, accel_y);
}
if (is_active_z()) {
AP::logger().Write_PSCD(-get_pos_target_cm().z, -_inav.get_position_z_up_cm(),
-get_vel_desired_cms().z, -get_vel_target_cms().z, -_inav.get_velocity_z_up_cms(),
-_accel_desired.z, -get_accel_target_cmss().z, -get_z_accel_cmss());
}
}
/// crosstrack_error - returns horizontal error to the closest point to the current track
float AC_PosControl::crosstrack_error() const
{
const Vector2f pos_error = _inav.get_position_xy_cm() - (_pos_target.xy()).tofloat();
if (is_zero(_vel_desired.xy().length_squared())) {
// crosstrack is the horizontal distance to target when stationary
return pos_error.length();
} else {
// crosstrack is the horizontal distance to the closest point to the current track
const Vector2f vel_unit = _vel_desired.xy().normalized();
const float dot_error = pos_error * vel_unit;
// todo: remove MAX of zero when safe_sqrt fixed
return safe_sqrt(MAX(pos_error.length_squared() - sq(dot_error), 0.0));
}
}
///
/// private methods
///
// get_lean_angles_to_accel - convert roll, pitch lean angles to NE frame accelerations in cm/s/s
void AC_PosControl::accel_to_lean_angles(float accel_x_cmss, float accel_y_cmss, float& roll_target, float& pitch_target) const
{
// rotate accelerations into body forward-right frame
const float accel_forward = accel_x_cmss * _ahrs.cos_yaw() + accel_y_cmss * _ahrs.sin_yaw();
const float accel_right = -accel_x_cmss * _ahrs.sin_yaw() + accel_y_cmss * _ahrs.cos_yaw();
// update angle targets that will be passed to stabilize controller
pitch_target = accel_to_angle(-accel_forward * 0.01) * 100;
float cos_pitch_target = cosf(pitch_target * M_PI / 18000.0f);
roll_target = accel_to_angle((accel_right * cos_pitch_target)*0.01) * 100;
}
// lean_angles_to_accel_xy - convert roll, pitch lean target angles to NE frame accelerations in cm/s/s
// todo: this should be based on thrust vector attitude control
void AC_PosControl::lean_angles_to_accel_xy(float& accel_x_cmss, float& accel_y_cmss) const
{
// rotate our roll, pitch angles into lat/lon frame
Vector3f att_target_euler = _attitude_control.get_att_target_euler_rad();
att_target_euler.z = _ahrs.yaw;
Vector3f accel_cmss = lean_angles_to_accel(att_target_euler);
accel_x_cmss = accel_cmss.x;
accel_y_cmss = accel_cmss.y;
}
// calculate_yaw_and_rate_yaw - update the calculated the vehicle yaw and rate of yaw.
bool AC_PosControl::calculate_yaw_and_rate_yaw()
{
// Calculate the turn rate
float turn_rate = 0.0f;
const float vel_desired_xy_len = _vel_desired.xy().length();
if (is_positive(vel_desired_xy_len)) {
const float accel_forward = (_accel_desired.x * _vel_desired.x + _accel_desired.y * _vel_desired.y) / vel_desired_xy_len;
const Vector2f accel_turn = _accel_desired.xy() - _vel_desired.xy() * accel_forward / vel_desired_xy_len;
const float accel_turn_xy_len = accel_turn.length();
turn_rate = accel_turn_xy_len / vel_desired_xy_len;
if ((accel_turn.y * _vel_desired.x - accel_turn.x * _vel_desired.y) < 0.0) {
turn_rate = -turn_rate;
}
}
// update the target yaw if velocity is greater than 5% _vel_max_xy_cms
if (vel_desired_xy_len > _vel_max_xy_cms * 0.05f) {
_yaw_target = degrees(_vel_desired.xy().angle()) * 100.0f;
_yaw_rate_target = turn_rate * degrees(100.0f);
return true;
}
return false;
}
// calculate_overspeed_gain - calculated increased maximum acceleration and jerk if over speed condition is detected
float AC_PosControl::calculate_overspeed_gain()
{
if (_vel_desired.z < _vel_max_down_cms && !is_zero(_vel_max_down_cms)) {
return POSCONTROL_OVERSPEED_GAIN_Z * _vel_desired.z / _vel_max_down_cms;
}
if (_vel_desired.z > _vel_max_up_cms && !is_zero(_vel_max_up_cms)) {
return POSCONTROL_OVERSPEED_GAIN_Z * _vel_desired.z / _vel_max_up_cms;
}
return 1.0;
}
/// initialise ekf xy position reset check
void AC_PosControl::init_ekf_xy_reset()
{
Vector2f pos_shift;
_ekf_xy_reset_ms = _ahrs.getLastPosNorthEastReset(pos_shift);
}
/// handle_ekf_xy_reset - check for ekf position reset and adjust loiter or brake target position
void AC_PosControl::handle_ekf_xy_reset()
{
// check for position shift
Vector2f pos_shift;
uint32_t reset_ms = _ahrs.getLastPosNorthEastReset(pos_shift);
if (reset_ms != _ekf_xy_reset_ms) {
_pos_target.xy() = (_inav.get_position_xy_cm() + _p_pos_xy.get_error()).topostype();
_vel_target.xy() = _inav.get_velocity_xy_cms() + _pid_vel_xy.get_error();
_ekf_xy_reset_ms = reset_ms;
}
}
/// initialise ekf z axis reset check
void AC_PosControl::init_ekf_z_reset()
{
float alt_shift;
_ekf_z_reset_ms = _ahrs.getLastPosDownReset(alt_shift);
}
/// handle_ekf_z_reset - check for ekf position reset and adjust loiter or brake target position
void AC_PosControl::handle_ekf_z_reset()
{
// check for position shift
float alt_shift;
uint32_t reset_ms = _ahrs.getLastPosDownReset(alt_shift);
if (reset_ms != 0 && reset_ms != _ekf_z_reset_ms) {
_pos_target.z = _inav.get_position_z_up_cm() + _p_pos_z.get_error();
_vel_target.z = _inav.get_velocity_z_up_cms() + _pid_vel_z.get_error();
_ekf_z_reset_ms = reset_ms;
}
}
bool AC_PosControl::pre_arm_checks(const char *param_prefix,
char *failure_msg,
const uint8_t failure_msg_len)
{
if (!is_positive(get_pos_xy_p().kP())) {
hal.util->snprintf(failure_msg, failure_msg_len, "%s_POSXY_P must be > 0", param_prefix);
return false;
}
if (!is_positive(get_pos_z_p().kP())) {
hal.util->snprintf(failure_msg, failure_msg_len, "%s_POSZ_P must be > 0", param_prefix);
return false;
}
if (!is_positive(get_vel_z_pid().kP())) {
hal.util->snprintf(failure_msg, failure_msg_len, "%s_VELZ_P must be > 0", param_prefix);
return false;
}
if (!is_positive(get_accel_z_pid().kP())) {
hal.util->snprintf(failure_msg, failure_msg_len, "%s_ACCZ_P must be > 0", param_prefix);
return false;
}
if (!is_positive(get_accel_z_pid().kI())) {
hal.util->snprintf(failure_msg, failure_msg_len, "%s_ACCZ_I must be > 0", param_prefix);
return false;
}
return true;
}
// return true if on a real vehicle or SITL with lock-step scheduling
bool AC_PosControl::has_good_timing(void) const
{
#if CONFIG_HAL_BOARD == HAL_BOARD_SITL
auto *sitl = AP::sitl();
if (sitl) {
return sitl->state.is_lock_step_scheduled;
}
#endif
// real boards are assumed to have good timing
return true;
}