ardupilot/libraries/AC_AttitudeControl/AC_AttitudeControl.cpp

670 lines
32 KiB
C++

// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-
#include "AC_AttitudeControl.h"
#include <AP_HAL/AP_HAL.h>
#include <AP_Math/AP_Math.h>
// table of user settable parameters
const AP_Param::GroupInfo AC_AttitudeControl::var_info[] = {
// 0, 1 were RATE_RP_MAX, RATE_Y_MAX
// @Param: SLEW_YAW
// @DisplayName: Yaw target slew rate
// @Description: Maximum rate the yaw target can be updated in Loiter, RTL, Auto flight modes
// @Units: Centi-Degrees/Sec
// @Range: 500 18000
// @Increment: 100
// @User: Advanced
AP_GROUPINFO("SLEW_YAW", 2, AC_AttitudeControl, _slew_yaw, AC_ATTITUDE_CONTROL_SLEW_YAW_DEFAULT_CDS),
// 3 was for ACCEL_RP_MAX
// @Param: ACCEL_Y_MAX
// @DisplayName: Acceleration Max for Yaw
// @Description: Maximum acceleration in yaw axis
// @Units: Centi-Degrees/Sec/Sec
// @Range: 0 72000
// @Values: 0:Disabled, 18000:Slow, 36000:Medium, 54000:Fast
// @Increment: 1000
// @User: Advanced
AP_GROUPINFO("ACCEL_Y_MAX", 4, AC_AttitudeControl, _accel_yaw_max, AC_ATTITUDE_CONTROL_ACCEL_Y_MAX_DEFAULT_CDSS),
// @Param: RATE_FF_ENAB
// @DisplayName: Rate Feedforward Enable
// @Description: Controls whether body-frame rate feedfoward is enabled or disabled
// @Values: 0:Disabled, 1:Enabled
// @User: Advanced
AP_GROUPINFO("RATE_FF_ENAB", 5, AC_AttitudeControl, _rate_bf_ff_enabled, AC_ATTITUDE_CONTROL_RATE_BF_FF_DEFAULT),
// @Param: ACCEL_R_MAX
// @DisplayName: Acceleration Max for Roll
// @Description: Maximum acceleration in roll axis
// @Units: Centi-Degrees/Sec/Sec
// @Range: 0 180000
// @Increment: 1000
// @Values: 0:Disabled, 72000:Slow, 108000:Medium, 162000:Fast
// @User: Advanced
AP_GROUPINFO("ACCEL_R_MAX", 6, AC_AttitudeControl, _accel_roll_max, AC_ATTITUDE_CONTROL_ACCEL_RP_MAX_DEFAULT_CDSS),
// @Param: ACCEL_P_MAX
// @DisplayName: Acceleration Max for Pitch
// @Description: Maximum acceleration in pitch axis
// @Units: Centi-Degrees/Sec/Sec
// @Range: 0 180000
// @Increment: 1000
// @Values: 0:Disabled, 72000:Slow, 108000:Medium, 162000:Fast
// @User: Advanced
AP_GROUPINFO("ACCEL_P_MAX", 7, AC_AttitudeControl, _accel_pitch_max, AC_ATTITUDE_CONTROL_ACCEL_RP_MAX_DEFAULT_CDSS),
// IDs 8,9,10,11 RESERVED (in use on Solo)
AP_GROUPEND
};
void AC_AttitudeControl::set_dt(float delta_sec)
{
_dt = delta_sec;
_pid_rate_roll.set_dt(_dt);
_pid_rate_pitch.set_dt(_dt);
_pid_rate_yaw.set_dt(_dt);
}
void AC_AttitudeControl::relax_bf_rate_controller()
{
// Set reference angular velocity used in angular velocity controller equal
// to the input angular velocity and reset the angular velocity integrators.
// This zeros the output of the angular velocity controller.
_ang_vel_target_rads = _ahrs.get_gyro();
_pid_rate_roll.reset_I();
_pid_rate_pitch.reset_I();
_pid_rate_yaw.reset_I();
// Write euler derivatives derived from vehicle angular velocity to
// _att_target_euler_rate_rads. This resets the state of the input shapers.
ang_vel_to_euler_rate(Vector3f(_ahrs.roll,_ahrs.pitch,_ahrs.yaw), _ang_vel_target_rads, _att_target_euler_rate_rads);
}
void AC_AttitudeControl::shift_ef_yaw_target(float yaw_shift_cd)
{
_att_target_euler_rad.z = wrap_2PI(_att_target_euler_rad.z + radians(yaw_shift_cd*0.01f));
}
void AC_AttitudeControl::input_euler_angle_roll_pitch_euler_rate_yaw_smooth(float euler_roll_angle_cd, float euler_pitch_angle_cd, float euler_yaw_rate_cds, float smoothing_gain)
{
// Convert from centidegrees on public interface to radians
float euler_roll_angle_rad = radians(euler_roll_angle_cd*0.01f);
float euler_pitch_angle_rad = radians(euler_pitch_angle_cd*0.01f);
float euler_yaw_rate_rads = radians(euler_yaw_rate_cds*0.01f);
// Sanity check smoothing gain
smoothing_gain = constrain_float(smoothing_gain,1.0f,50.0f);
// Add roll trim to compensate tail rotor thrust in heli (will return zero on multirotors)
euler_roll_angle_rad += get_roll_trim_rad();
Vector3f att_error_euler_rad;
if ((get_accel_roll_max_radss() > 0.0f) && _rate_bf_ff_enabled) {
// When roll acceleration limiting and feedforward are enabled, the sqrt controller is used to compute an euler roll-axis
// angular velocity that will cause the euler roll angle to smoothly stop at the input angle with limited deceleration
// and an exponential decay specified by smoothing_gain at the end.
float euler_rate_desired_rads = sqrt_controller(euler_roll_angle_rad-_att_target_euler_rad.x, smoothing_gain, get_accel_roll_max_radss());
// Acceleration is limited directly to smooth the beginning of the curve.
float rate_change_limit_rads = get_accel_roll_max_radss() * _dt;
_att_target_euler_rate_rads.x = constrain_float(euler_rate_desired_rads, _att_target_euler_rate_rads.x-rate_change_limit_rads, _att_target_euler_rate_rads.x+rate_change_limit_rads);
// The output rate is used to update the attitude target euler angles and is fed forward into the rate controller.
update_att_target_and_error_roll(_att_target_euler_rate_rads.x, att_error_euler_rad, AC_ATTITUDE_RATE_STAB_ROLL_OVERSHOOT_ANGLE_MAX_RAD);
} else {
// When acceleration limiting and feedforward are not enabled, the target roll euler angle is simply set to the
// input value and the feedforward rate is zeroed.
_att_target_euler_rad.x = euler_roll_angle_rad;
att_error_euler_rad.x = wrap_PI(_att_target_euler_rad.x - _ahrs.roll);
_att_target_euler_rate_rads.x = 0;
}
_att_target_euler_rad.x = constrain_float(_att_target_euler_rad.x, -get_tilt_limit_rad(), get_tilt_limit_rad());
if ((get_accel_pitch_max_radss() > 0.0f) && _rate_bf_ff_enabled) {
// When pitch acceleration limiting and feedforward are enabled, the sqrt controller is used to compute an euler pitch-axis
// angular velocity that will cause the euler pitch angle to smoothly stop at the input angle with limited deceleration
// and an exponential decay specified by smoothing_gain at the end.
float euler_rate_desired_rads = sqrt_controller(euler_pitch_angle_rad-_att_target_euler_rad.y, smoothing_gain, get_accel_pitch_max_radss());
// Acceleration is limited directly to smooth the beginning of the curve.
float rate_change_limit_rads = get_accel_pitch_max_radss() * _dt;
_att_target_euler_rate_rads.y = constrain_float(euler_rate_desired_rads, _att_target_euler_rate_rads.y-rate_change_limit_rads, _att_target_euler_rate_rads.y+rate_change_limit_rads);
// The output rate is used to update the attitude target euler angles and is fed forward into the rate controller.
update_att_target_and_error_pitch(_att_target_euler_rate_rads.y, att_error_euler_rad, AC_ATTITUDE_RATE_STAB_ROLL_OVERSHOOT_ANGLE_MAX_RAD);
} else {
_att_target_euler_rad.y = euler_pitch_angle_rad;
att_error_euler_rad.y = wrap_PI(_att_target_euler_rad.y - _ahrs.pitch);
_att_target_euler_rate_rads.y = 0;
}
_att_target_euler_rad.y = constrain_float(_att_target_euler_rad.y, -get_tilt_limit_rad(), get_tilt_limit_rad());
if (get_accel_yaw_max_radss() > 0.0f) {
// When yaw acceleration limiting is enabled, the yaw input shaper constrains angular acceleration about the yaw axis, slewing
// the output rate towards the input rate.
float rate_change_limit_rads = get_accel_yaw_max_radss() * _dt;
_att_target_euler_rate_rads.z += constrain_float(euler_yaw_rate_rads - _att_target_euler_rate_rads.z, -rate_change_limit_rads, rate_change_limit_rads);
// The output rate is used to update the attitude target euler angles and is fed forward into the rate controller.
update_att_target_and_error_yaw(_att_target_euler_rate_rads.z, att_error_euler_rad, AC_ATTITUDE_RATE_STAB_YAW_OVERSHOOT_ANGLE_MAX_RAD);
} else {
// When yaw acceleration limiting is disabled, the attitude target is simply rotated using the input rate and the input rate
// is fed forward into the rate controller.
_att_target_euler_rate_rads.z = euler_yaw_rate_rads;
update_att_target_and_error_yaw(_att_target_euler_rate_rads.z, att_error_euler_rad, AC_ATTITUDE_RATE_STAB_YAW_OVERSHOOT_ANGLE_MAX_RAD);
}
// Convert 321-intrinsic euler angle errors to a body-frame rotation vector
// NOTE: This results in an approximation of the attitude error based on a linearization about the current attitude
euler_rate_to_ang_vel(Vector3f(_ahrs.roll,_ahrs.pitch,_ahrs.yaw), att_error_euler_rad, _att_error_rot_vec_rad);
// Compute the angular velocity target from the attitude error
update_ang_vel_target_from_att_error();
// Convert euler angle derivative of desired attitude into a body-frame angular velocity vector for feedforward
if (_rate_bf_ff_enabled) {
euler_rate_to_ang_vel(Vector3f(_ahrs.roll,_ahrs.pitch,_ahrs.yaw), _att_target_euler_rate_rads, _att_target_ang_vel_rads);
} else {
euler_rate_to_ang_vel(Vector3f(_ahrs.roll,_ahrs.pitch,_ahrs.yaw), Vector3f(0,0,_att_target_euler_rate_rads.z), _att_target_ang_vel_rads);
}
// NOTE: Rotation of _att_target_ang_vel_rads from desired body frame to estimated body frame is possibly omitted here
// Add the angular velocity feedforward
_ang_vel_target_rads += _att_target_ang_vel_rads;
}
void AC_AttitudeControl::input_euler_angle_roll_pitch_euler_rate_yaw(float euler_roll_angle_cd, float euler_pitch_angle_cd, float euler_yaw_rate_cds)
{
// Convert from centidegrees on public interface to radians
float euler_roll_angle_rad = radians(euler_roll_angle_cd*0.01f);
float euler_pitch_angle_rad = radians(euler_pitch_angle_cd*0.01f);
float euler_yaw_rate_rads = radians(euler_yaw_rate_cds*0.01f);
Vector3f att_error_euler_rad;
// Add roll trim to compensate tail rotor thrust in heli (will return zero on multirotors)
euler_roll_angle_rad += get_roll_trim_rad();
// Set roll/pitch attitude targets from input.
_att_target_euler_rad.x = constrain_float(euler_roll_angle_rad, -get_tilt_limit_rad(), get_tilt_limit_rad());
_att_target_euler_rad.y = constrain_float(euler_pitch_angle_rad, -get_tilt_limit_rad(), get_tilt_limit_rad());
// Update roll/pitch attitude error.
att_error_euler_rad.x = wrap_PI(_att_target_euler_rad.x - _ahrs.roll);
att_error_euler_rad.y = wrap_PI(_att_target_euler_rad.y - _ahrs.pitch);
// Zero the roll and pitch feed-forward rate.
_att_target_euler_rate_rads.x = 0;
_att_target_euler_rate_rads.y = 0;
if (get_accel_yaw_max_radss() > 0.0f) {
// When yaw acceleration limiting is enabled, the yaw input shaper constrains angular acceleration about the yaw axis, slewing
// the output rate towards the input rate.
float rate_change_limit_rads = get_accel_yaw_max_radss() * _dt;
_att_target_euler_rate_rads.z += constrain_float(euler_yaw_rate_rads - _att_target_euler_rate_rads.z, -rate_change_limit_rads, rate_change_limit_rads);
// The output rate is used to update the attitude target euler angles and is fed forward into the rate controller.
update_att_target_and_error_yaw(_att_target_euler_rate_rads.z, att_error_euler_rad, AC_ATTITUDE_RATE_STAB_YAW_OVERSHOOT_ANGLE_MAX_RAD);
} else {
// When yaw acceleration limiting is disabled, the attitude target is simply rotated using the input rate and the input rate
// is fed forward into the rate controller.
_att_target_euler_rate_rads.z = euler_yaw_rate_rads;
update_att_target_and_error_yaw(_att_target_euler_rate_rads.z, att_error_euler_rad, AC_ATTITUDE_RATE_STAB_YAW_OVERSHOOT_ANGLE_MAX_RAD);
}
// Convert 321-intrinsic euler angle errors to a body-frame rotation vector
// NOTE: This results in an approximation of the attitude error based on a linearization about the current attitude
euler_rate_to_ang_vel(Vector3f(_ahrs.roll,_ahrs.pitch,_ahrs.yaw), att_error_euler_rad, _att_error_rot_vec_rad);
// Compute the angular velocity target from the attitude error
update_ang_vel_target_from_att_error();
// Convert euler angle derivatives of desired attitude into a body-frame angular velocity vector for feedforward
// NOTE: This should be done about the desired attitude instead of about the vehicle attitude
euler_rate_to_ang_vel(Vector3f(_ahrs.roll,_ahrs.pitch,_ahrs.yaw), _att_target_euler_rate_rads, _att_target_ang_vel_rads);
// NOTE: A rotation of _att_target_ang_vel_rads from desired body frame to estimated body frame is possibly omitted here
// Add the angular velocity feedforward
_ang_vel_target_rads += _att_target_ang_vel_rads;
}
void AC_AttitudeControl::input_euler_angle_roll_pitch_yaw(float euler_roll_angle_cd, float euler_pitch_angle_cd, float euler_yaw_angle_cd, bool slew_yaw)
{
// Convert from centidegrees on public interface to radians
float euler_roll_angle_rad = radians(euler_roll_angle_cd*0.01f);
float euler_pitch_angle_rad = radians(euler_pitch_angle_cd*0.01f);
float euler_yaw_angle_rad = radians(euler_yaw_angle_cd*0.01f);
Vector3f att_error_euler_rad;
// Add roll trim to compensate tail rotor thrust in heli (will return zero on multirotors)
euler_roll_angle_rad += get_roll_trim_rad();
// Set attitude targets from input.
_att_target_euler_rad.x = constrain_float(euler_roll_angle_rad, -get_tilt_limit_rad(), get_tilt_limit_rad());
_att_target_euler_rad.y = constrain_float(euler_pitch_angle_rad, -get_tilt_limit_rad(), get_tilt_limit_rad());
_att_target_euler_rad.z = euler_yaw_angle_rad;
// Update attitude error.
att_error_euler_rad.x = wrap_PI(_att_target_euler_rad.x - _ahrs.roll);
att_error_euler_rad.y = wrap_PI(_att_target_euler_rad.y - _ahrs.pitch);
att_error_euler_rad.z = wrap_PI(_att_target_euler_rad.z - _ahrs.yaw);
// Constrain the yaw angle error
if (slew_yaw) {
att_error_euler_rad.z = constrain_float(att_error_euler_rad.z,-get_slew_yaw_rads(),get_slew_yaw_rads());
}
// Convert 321-intrinsic euler angle errors to a body-frame rotation vector
// NOTE: This results in an approximation of the attitude error based on a linearization about the current attitude
euler_rate_to_ang_vel(Vector3f(_ahrs.roll,_ahrs.pitch,_ahrs.yaw), att_error_euler_rad, _att_error_rot_vec_rad);
// Compute the angular velocity target from the attitude error
update_ang_vel_target_from_att_error();
// Keep euler derivative updated
ang_vel_to_euler_rate(Vector3f(_ahrs.roll,_ahrs.pitch,_ahrs.yaw), _ang_vel_target_rads, _att_target_euler_rate_rads);
}
void AC_AttitudeControl::input_euler_rate_roll_pitch_yaw(float euler_roll_rate_cds, float euler_pitch_rate_cds, float euler_yaw_rate_cds)
{
// Convert from centidegrees on public interface to radians
float euler_roll_rate_rads = radians(euler_roll_rate_cds*0.01f);
float euler_pitch_rate_rads = radians(euler_pitch_rate_cds*0.01f);
float euler_yaw_rate_rads = radians(euler_yaw_rate_cds*0.01f);
Vector3f att_error_euler_rad;
// Compute acceleration-limited euler roll rate
if (get_accel_roll_max_radss() > 0.0f) {
float rate_change_limit_rads = get_accel_roll_max_radss() * _dt;
_att_target_euler_rate_rads.x += constrain_float(euler_roll_rate_rads - _att_target_euler_rate_rads.x, -rate_change_limit_rads, rate_change_limit_rads);
} else {
_att_target_euler_rate_rads.x = euler_roll_rate_rads;
}
// Compute acceleration-limited euler pitch rate
if (get_accel_pitch_max_radss() > 0.0f) {
float rate_change_limit_rads = get_accel_pitch_max_radss() * _dt;
_att_target_euler_rate_rads.y += constrain_float(euler_pitch_rate_rads - _att_target_euler_rate_rads.y, -rate_change_limit_rads, rate_change_limit_rads);
} else {
_att_target_euler_rate_rads.y = euler_pitch_rate_rads;
}
// Compute acceleration-limited euler yaw rate
if (get_accel_yaw_max_radss() > 0.0f) {
float rate_change_limit_rads = get_accel_yaw_max_radss() * _dt;
_att_target_euler_rate_rads.z += constrain_float(euler_yaw_rate_rads - _att_target_euler_rate_rads.z, -rate_change_limit_rads, rate_change_limit_rads);
} else {
_att_target_euler_rate_rads.z = euler_yaw_rate_rads;
}
// Update the attitude target from the computed euler rates
update_att_target_and_error_roll(_att_target_euler_rate_rads.x, att_error_euler_rad, AC_ATTITUDE_RATE_STAB_ROLL_OVERSHOOT_ANGLE_MAX_RAD);
update_att_target_and_error_pitch(_att_target_euler_rate_rads.y, att_error_euler_rad, AC_ATTITUDE_RATE_STAB_PITCH_OVERSHOOT_ANGLE_MAX_RAD);
update_att_target_and_error_yaw(_att_target_euler_rate_rads.z, att_error_euler_rad, AC_ATTITUDE_RATE_STAB_YAW_OVERSHOOT_ANGLE_MAX_RAD);
// Apply tilt limit
_att_target_euler_rad.x = constrain_float(_att_target_euler_rad.x, -get_tilt_limit_rad(), get_tilt_limit_rad());
_att_target_euler_rad.y = constrain_float(_att_target_euler_rad.y, -get_tilt_limit_rad(), get_tilt_limit_rad());
// Convert 321-intrinsic euler angle errors to a body-frame rotation vector
// NOTE: This results in an approximation of the attitude error based on a linearization about the current attitude
euler_rate_to_ang_vel(Vector3f(_ahrs.roll,_ahrs.pitch,_ahrs.yaw), att_error_euler_rad, _att_error_rot_vec_rad);
// Compute the angular velocity target from the attitude error
update_ang_vel_target_from_att_error();
// Convert euler angle derivatives of desired attitude into a body-frame angular velocity vector for feedforward
euler_rate_to_ang_vel(Vector3f(_ahrs.roll,_ahrs.pitch,_ahrs.yaw), _att_target_euler_rate_rads, _att_target_ang_vel_rads);
// NOTE: Rotation of _att_target_ang_vel_rads from desired body frame to estimated body frame is possibly omitted here
// Add the angular velocity feedforward
_ang_vel_target_rads += _att_target_ang_vel_rads;
}
void AC_AttitudeControl::input_rate_bf_roll_pitch_yaw(float roll_rate_bf_cds, float pitch_rate_bf_cds, float yaw_rate_bf_cds)
{
// Convert from centidegrees on public interface to radians
float roll_rate_bf_rads = radians(roll_rate_bf_cds*0.01f);
float pitch_rate_bf_rads = radians(pitch_rate_bf_cds*0.01f);
float yaw_rate_bf_rads = radians(yaw_rate_bf_cds*0.01f);
// Compute acceleration-limited body-frame roll rate
if (get_accel_roll_max_radss() > 0.0f) {
float rate_change_limit_rads = get_accel_roll_max_radss() * _dt;
_att_target_ang_vel_rads.x += constrain_float(roll_rate_bf_rads - _att_target_ang_vel_rads.x, -rate_change_limit_rads, rate_change_limit_rads);
} else {
_att_target_ang_vel_rads.x = roll_rate_bf_rads;
}
// Compute acceleration-limited body-frame pitch rate
if (get_accel_pitch_max_radss() > 0.0f) {
float rate_change_limit_rads = get_accel_pitch_max_radss() * _dt;
_att_target_ang_vel_rads.y += constrain_float(pitch_rate_bf_rads - _att_target_ang_vel_rads.y, -rate_change_limit_rads, rate_change_limit_rads);
} else {
_att_target_ang_vel_rads.y = pitch_rate_bf_rads;
}
// Compute acceleration-limited body-frame yaw rate
if (get_accel_yaw_max_radss() > 0.0f) {
float rate_change_limit_rads = get_accel_yaw_max_radss() * _dt;
_att_target_ang_vel_rads.z += constrain_float(yaw_rate_bf_rads - _att_target_ang_vel_rads.z, -rate_change_limit_rads, rate_change_limit_rads);
} else {
_att_target_ang_vel_rads.z = yaw_rate_bf_rads;
}
// Compute quaternion target attitude
Quaternion att_target_quat;
att_target_quat.from_euler(_att_target_euler_rad.x,_att_target_euler_rad.y,_att_target_euler_rad.z);
// Rotate quaternion target attitude using computed rate
att_target_quat.rotate(_att_target_ang_vel_rads*_dt);
att_target_quat.normalize();
// Call quaternion attitude controller
input_att_quat_bf_ang_vel(att_target_quat, _att_target_ang_vel_rads);
}
void AC_AttitudeControl::input_att_quat_bf_ang_vel(const Quaternion& att_target_quat, const Vector3f& att_target_ang_vel_rads)
{
// Update euler attitude target and angular velocity targets
att_target_quat.to_euler(_att_target_euler_rad.x,_att_target_euler_rad.y,_att_target_euler_rad.z);
_att_target_ang_vel_rads = att_target_ang_vel_rads;
ang_vel_to_euler_rate(Vector3f(_ahrs.roll,_ahrs.pitch,_ahrs.yaw), att_target_ang_vel_rads, _att_target_euler_rate_rads);
// Retrieve quaternion vehicle attitude
// TODO add _ahrs.get_quaternion()
Quaternion att_vehicle_quat;
att_vehicle_quat.from_rotation_matrix(_ahrs.get_dcm_matrix());
// Compute attitude error
(att_vehicle_quat.inverse()*att_target_quat).to_axis_angle(_att_error_rot_vec_rad);
// Compute the angular velocity target from the attitude error
update_ang_vel_target_from_att_error();
// Add the angular velocity feedforward
// NOTE: Rotation of _att_target_ang_vel_rads from desired body frame to estimated body frame is possibly omitted here
_ang_vel_target_rads += _att_target_ang_vel_rads;
}
void AC_AttitudeControl::rate_controller_run()
{
_motors.set_roll(rate_bf_to_motor_roll(_ang_vel_target_rads.x));
_motors.set_pitch(rate_bf_to_motor_pitch(_ang_vel_target_rads.y));
_motors.set_yaw(rate_bf_to_motor_yaw(_ang_vel_target_rads.z));
}
void AC_AttitudeControl::euler_rate_to_ang_vel(const Vector3f& euler_rad, const Vector3f& euler_rate_rads, Vector3f& ang_vel_rads)
{
float sin_theta = sinf(euler_rad.y);
float cos_theta = cosf(euler_rad.y);
float sin_phi = sinf(euler_rad.x);
float cos_phi = cosf(euler_rad.x);
ang_vel_rads.x = euler_rate_rads.x - sin_theta * euler_rate_rads.z;
ang_vel_rads.y = cos_phi * euler_rate_rads.y + sin_phi * cos_theta * euler_rate_rads.z;
ang_vel_rads.z = -sin_phi * euler_rate_rads.y + cos_theta * cos_phi * euler_rate_rads.z;
}
bool AC_AttitudeControl::ang_vel_to_euler_rate(const Vector3f& euler_rad, const Vector3f& ang_vel_rads, Vector3f& euler_rate_rads)
{
float sin_theta = sinf(euler_rad.y);
float cos_theta = cosf(euler_rad.y);
float sin_phi = sinf(euler_rad.x);
float cos_phi = cosf(euler_rad.x);
// When the vehicle pitches all the way up or all the way down, the euler angles become discontinuous. In this case, we just return false.
if (is_zero(cos_theta)) {
return false;
}
euler_rate_rads.x = ang_vel_rads.x + sin_phi * (sin_theta/cos_theta) * ang_vel_rads.y + cos_phi * (sin_theta/cos_theta) * ang_vel_rads.z;
euler_rate_rads.y = cos_phi * ang_vel_rads.y - sin_phi * ang_vel_rads.z;
euler_rate_rads.z = (sin_phi / cos_theta) * ang_vel_rads.y + (cos_phi / cos_theta) * ang_vel_rads.z;
return true;
}
void AC_AttitudeControl::update_att_target_and_error_roll(float euler_roll_rate_rads, Vector3f &att_error_euler_rad, float overshoot_max_rad)
{
// Compute constrained angle error
att_error_euler_rad.x = wrap_PI(_att_target_euler_rad.x - _ahrs.roll);
att_error_euler_rad.x = constrain_float(att_error_euler_rad.x, -overshoot_max_rad, overshoot_max_rad);
// Update attitude target from constrained angle error
_att_target_euler_rad.x = att_error_euler_rad.x + _ahrs.roll;
// Increment the attitude target
_att_target_euler_rad.x += euler_roll_rate_rads * _dt;
_att_target_euler_rad.x = wrap_PI(_att_target_euler_rad.x);
}
void AC_AttitudeControl::update_att_target_and_error_pitch(float euler_pitch_rate_rads, Vector3f &att_error_euler_rad, float overshoot_max_rad)
{
// Compute constrained angle error
att_error_euler_rad.y = wrap_PI(_att_target_euler_rad.y - _ahrs.pitch);
att_error_euler_rad.y = constrain_float(att_error_euler_rad.y, -overshoot_max_rad, overshoot_max_rad);
// Update attitude target from constrained angle error
_att_target_euler_rad.y = att_error_euler_rad.y + _ahrs.pitch;
// Increment the attitude target
_att_target_euler_rad.y += euler_pitch_rate_rads * _dt;
_att_target_euler_rad.y = wrap_PI(_att_target_euler_rad.y);
}
void AC_AttitudeControl::update_att_target_and_error_yaw(float euler_yaw_rate_rads, Vector3f &att_error_euler_rad, float overshoot_max_rad)
{
// Compute constrained angle error
att_error_euler_rad.z = wrap_PI(_att_target_euler_rad.z - _ahrs.yaw);
att_error_euler_rad.z = constrain_float(att_error_euler_rad.z, -overshoot_max_rad, overshoot_max_rad);
// Update attitude target from constrained angle error
_att_target_euler_rad.z = att_error_euler_rad.z + _ahrs.yaw;
// Increment the attitude target
_att_target_euler_rad.z += euler_yaw_rate_rads * _dt;
_att_target_euler_rad.z = wrap_2PI(_att_target_euler_rad.z);
}
void AC_AttitudeControl::integrate_bf_rate_error_to_angle_errors()
{
// Integrate the angular velocity error into the attitude error
_att_error_rot_vec_rad += (_att_target_ang_vel_rads - _ahrs.get_gyro()) * _dt;
// Constrain attitude error
_att_error_rot_vec_rad.x = constrain_float(_att_error_rot_vec_rad.x, -AC_ATTITUDE_RATE_STAB_ACRO_OVERSHOOT_ANGLE_MAX_RAD, AC_ATTITUDE_RATE_STAB_ACRO_OVERSHOOT_ANGLE_MAX_RAD);
_att_error_rot_vec_rad.y = constrain_float(_att_error_rot_vec_rad.y, -AC_ATTITUDE_RATE_STAB_ACRO_OVERSHOOT_ANGLE_MAX_RAD, AC_ATTITUDE_RATE_STAB_ACRO_OVERSHOOT_ANGLE_MAX_RAD);
_att_error_rot_vec_rad.z = constrain_float(_att_error_rot_vec_rad.z, -AC_ATTITUDE_RATE_STAB_ACRO_OVERSHOOT_ANGLE_MAX_RAD, AC_ATTITUDE_RATE_STAB_ACRO_OVERSHOOT_ANGLE_MAX_RAD);
}
void AC_AttitudeControl::update_ang_vel_target_from_att_error()
{
// Compute the roll angular velocity demand from the roll angle error
if (_att_ctrl_use_accel_limit && _accel_roll_max > 0.0f) {
_ang_vel_target_rads.x = sqrt_controller(_att_error_rot_vec_rad.x, _p_angle_roll.kP(), constrain_float(get_accel_roll_max_radss()/2.0f, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MIN_RADSS, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MAX_RADSS));
}else{
_ang_vel_target_rads.x = _p_angle_roll.kP() * _att_error_rot_vec_rad.x;
}
// Compute the pitch angular velocity demand from the roll angle error
if (_att_ctrl_use_accel_limit && _accel_pitch_max > 0.0f) {
_ang_vel_target_rads.y = sqrt_controller(_att_error_rot_vec_rad.y, _p_angle_pitch.kP(), constrain_float(get_accel_pitch_max_radss()/2.0f, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MIN_RADSS, AC_ATTITUDE_ACCEL_RP_CONTROLLER_MAX_RADSS));
}else{
_ang_vel_target_rads.y = _p_angle_pitch.kP() * _att_error_rot_vec_rad.y;
}
// Compute the yaw angular velocity demand from the roll angle error
if (_att_ctrl_use_accel_limit && _accel_yaw_max > 0.0f) {
_ang_vel_target_rads.z = sqrt_controller(_att_error_rot_vec_rad.z, _p_angle_yaw.kP(), constrain_float(get_accel_yaw_max_radss()/2.0f, AC_ATTITUDE_ACCEL_Y_CONTROLLER_MIN_RADSS, AC_ATTITUDE_ACCEL_Y_CONTROLLER_MAX_RADSS));
}else{
_ang_vel_target_rads.z = _p_angle_yaw.kP() * _att_error_rot_vec_rad.z;
}
// Account for precession of desired attitude about the body frame yaw axis
_ang_vel_target_rads.x += _att_error_rot_vec_rad.y * _ahrs.get_gyro().z;
_ang_vel_target_rads.y += -_att_error_rot_vec_rad.x * _ahrs.get_gyro().z;
}
float AC_AttitudeControl::rate_bf_to_motor_roll(float rate_target_rads)
{
float current_rate_rads = _ahrs.get_gyro().x;
float rate_error_rads = rate_target_rads - current_rate_rads;
// For legacy reasons, we convert to centi-degrees before inputting to the PID
_pid_rate_roll.set_input_filter_d(degrees(rate_error_rads)*100.0f);
_pid_rate_roll.set_desired_rate(degrees(rate_target_rads)*100.0f);
float integrator = _pid_rate_roll.get_integrator();
// Ensure that integrator can only be reduced if the output is saturated
if (!_motors.limit.roll_pitch || ((integrator > 0 && rate_error_rads < 0) || (integrator < 0 && rate_error_rads > 0))) {
integrator = _pid_rate_roll.get_i();
}
// Compute output
float output = _pid_rate_roll.get_p() + integrator + _pid_rate_roll.get_d();
// Constrain output
return constrain_float(output, -AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX, AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX);
}
float AC_AttitudeControl::rate_bf_to_motor_pitch(float rate_target_rads)
{
float current_rate_rads = _ahrs.get_gyro().y;
float rate_error_rads = rate_target_rads - current_rate_rads;
// For legacy reasons, we convert to centi-degrees before inputting to the PID
_pid_rate_pitch.set_input_filter_d(degrees(rate_error_rads)*100.0f);
_pid_rate_pitch.set_desired_rate(degrees(rate_target_rads)*100.0f);
float integrator = _pid_rate_pitch.get_integrator();
// Ensure that integrator can only be reduced if the output is saturated
if (!_motors.limit.roll_pitch || ((integrator > 0 && rate_error_rads < 0) || (integrator < 0 && rate_error_rads > 0))) {
integrator = _pid_rate_pitch.get_i();
}
// Compute output
float output = _pid_rate_pitch.get_p() + integrator + _pid_rate_pitch.get_d();
// Constrain output
return constrain_float(output, -AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX, AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX);
}
float AC_AttitudeControl::rate_bf_to_motor_yaw(float rate_target_rads)
{
float current_rate_rads = _ahrs.get_gyro().z;
float rate_error_rads = rate_target_rads - current_rate_rads;
// For legacy reasons, we convert to centi-degrees before inputting to the PID
_pid_rate_yaw.set_input_filter_all(degrees(rate_error_rads)*100.0f);
_pid_rate_yaw.set_desired_rate(degrees(rate_target_rads)*100.0f);
float integrator = _pid_rate_yaw.get_integrator();
// Ensure that integrator can only be reduced if the output is saturated
if (!_motors.limit.yaw || ((integrator > 0 && rate_error_rads < 0) || (integrator < 0 && rate_error_rads > 0))) {
integrator = _pid_rate_yaw.get_i();
}
// Compute output
float output = _pid_rate_yaw.get_p() + integrator + _pid_rate_yaw.get_d();
// Constrain output
return constrain_float(output, -AC_ATTITUDE_RATE_YAW_CONTROLLER_OUT_MAX, AC_ATTITUDE_RATE_YAW_CONTROLLER_OUT_MAX);
}
void AC_AttitudeControl::accel_limiting(bool enable_limits)
{
if (enable_limits) {
// If enabling limits, reload from eeprom or set to defaults
if (is_zero(_accel_roll_max)) {
_accel_roll_max.load();
}
if (is_zero(_accel_pitch_max)) {
_accel_pitch_max.load();
}
if (is_zero(_accel_yaw_max)) {
_accel_yaw_max.load();
}
} else {
_accel_roll_max = 0.0f;
_accel_pitch_max = 0.0f;
_accel_yaw_max = 0.0f;
}
}
void AC_AttitudeControl::set_throttle_out(float throttle_in, bool apply_angle_boost, float filter_cutoff)
{
_throttle_in_filt.apply(throttle_in, _dt);
_motors.set_stabilizing(true);
_motors.set_throttle_filter_cutoff(filter_cutoff);
if (apply_angle_boost) {
_motors.set_throttle(get_boosted_throttle(throttle_in));
}else{
_motors.set_throttle(throttle_in);
// Clear angle_boost for logging purposes
_angle_boost = 0;
}
}
void AC_AttitudeControl::set_throttle_out_unstabilized(float throttle_in, bool reset_attitude_control, float filter_cutoff)
{
_throttle_in_filt.apply(throttle_in, _dt);
if (reset_attitude_control) {
relax_bf_rate_controller();
set_yaw_target_to_current_heading();
}
_motors.set_throttle_filter_cutoff(filter_cutoff);
_motors.set_stabilizing(false);
_motors.set_throttle(throttle_in);
_angle_boost = 0;
}
float AC_AttitudeControl::sqrt_controller(float error, float p, float second_ord_lim)
{
if (second_ord_lim < 0.0f || is_zero(second_ord_lim) || is_zero(p)) {
return error*p;
}
float linear_dist = second_ord_lim/sq(p);
if (error > linear_dist) {
return safe_sqrt(2.0f*second_ord_lim*(error-(linear_dist/2.0f)));
} else if (error < -linear_dist) {
return -safe_sqrt(2.0f*second_ord_lim*(-error-(linear_dist/2.0f)));
} else {
return error*p;
}
}
float AC_AttitudeControl::max_rate_step_bf_roll()
{
float alpha = _pid_rate_roll.get_filt_alpha();
float alpha_remaining = 1-alpha;
return AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX/((alpha_remaining*alpha_remaining*alpha_remaining*alpha*_pid_rate_roll.kD())/_dt + _pid_rate_roll.kP());
}
float AC_AttitudeControl::max_rate_step_bf_pitch()
{
float alpha = _pid_rate_pitch.get_filt_alpha();
float alpha_remaining = 1-alpha;
return AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX/((alpha_remaining*alpha_remaining*alpha_remaining*alpha*_pid_rate_pitch.kD())/_dt + _pid_rate_pitch.kP());
}
float AC_AttitudeControl::max_rate_step_bf_yaw()
{
float alpha = _pid_rate_yaw.get_filt_alpha();
float alpha_remaining = 1-alpha;
return AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX/((alpha_remaining*alpha_remaining*alpha_remaining*alpha*_pid_rate_yaw.kD())/_dt + _pid_rate_yaw.kP());
}