ardupilot/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.cpp

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#include "AC_AttitudeControl_Heli.h"
#include <AP_HAL/AP_HAL.h>
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// table of user settable parameters
const AP_Param::GroupInfo AC_AttitudeControl_Heli::var_info[] = {
// parameters from parent vehicle
AP_NESTEDGROUPINFO(AC_AttitudeControl, 0),
// @Param: HOVR_ROL_TRM
// @DisplayName: Hover Roll Trim
// @Description: Trim the hover roll angle to counter tail rotor thrust in a hover
// @Units: cdeg
// @Increment: 10
// @Range: 0 1000
// @User: Advanced
AP_GROUPINFO("HOVR_ROL_TRM", 1, AC_AttitudeControl_Heli, _hover_roll_trim, AC_ATTITUDE_HELI_HOVER_ROLL_TRIM_DEFAULT),
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// @Param: RAT_RLL_P
// @DisplayName: Roll axis rate controller P gain
// @Description: Roll axis rate controller P gain. Corrects in proportion to the difference between the desired roll rate vs actual roll rate
// @Range: 0.0 0.35
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// @Increment: 0.005
// @User: Standard
// @Param: RAT_RLL_I
// @DisplayName: Roll axis rate controller I gain
// @Description: Roll axis rate controller I gain. Corrects long-term difference in desired roll rate vs actual roll rate
// @Range: 0.0 0.6
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// @Increment: 0.01
// @User: Standard
// @Param: RAT_RLL_IMAX
// @DisplayName: Roll axis rate controller I gain maximum
// @Description: Roll axis rate controller I gain maximum. Constrains the maximum that the I term will output
// @Range: 0 1
// @Increment: 0.01
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// @User: Standard
// @Param: RAT_RLL_ILMI
// @DisplayName: Roll axis rate controller I-term leak minimum
// @Description: Point below which I-term will not leak down
// @Range: 0 1
// @User: Advanced
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// @Param: RAT_RLL_D
// @DisplayName: Roll axis rate controller D gain
// @Description: Roll axis rate controller D gain. Compensates for short-term change in desired roll rate vs actual roll rate
// @Range: 0.0 0.03
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// @Increment: 0.001
// @User: Standard
// @Param: RAT_RLL_FF
// @DisplayName: Roll axis rate controller feed forward
// @Description: Roll axis rate controller feed forward
// @Range: 0.05 0.5
// @Increment: 0.001
// @User: Standard
// @Param: RAT_RLL_FLTT
// @DisplayName: Roll axis rate controller target frequency in Hz
// @Description: Roll axis rate controller target frequency in Hz
// @Range: 5 50
// @Increment: 1
// @Units: Hz
// @User: Standard
// @Param: RAT_RLL_FLTE
// @DisplayName: Roll axis rate controller error frequency in Hz
// @Description: Roll axis rate controller error frequency in Hz
// @Range: 5 50
// @Increment: 1
// @Units: Hz
// @User: Standard
// @Param: RAT_RLL_FLTD
// @DisplayName: Roll axis rate controller derivative frequency in Hz
// @Description: Roll axis rate controller derivative frequency in Hz
// @Range: 0 50
// @Increment: 1
// @Units: Hz
// @User: Standard
// @Param: RAT_RLL_SMAX
// @DisplayName: Roll 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
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AP_SUBGROUPINFO(_pid_rate_roll, "RAT_RLL_", 2, AC_AttitudeControl_Heli, AC_HELI_PID),
// @Param: RAT_PIT_P
// @DisplayName: Pitch axis rate controller P gain
// @Description: Pitch axis rate controller P gain. Corrects in proportion to the difference between the desired pitch rate vs actual pitch rate
// @Range: 0.0 0.35
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// @Increment: 0.005
// @User: Standard
// @Param: RAT_PIT_I
// @DisplayName: Pitch axis rate controller I gain
// @Description: Pitch axis rate controller I gain. Corrects long-term difference in desired pitch rate vs actual pitch rate
// @Range: 0.0 0.6
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// @Increment: 0.01
// @User: Standard
// @Param: RAT_PIT_IMAX
// @DisplayName: Pitch axis rate controller I gain maximum
// @Description: Pitch axis rate controller I gain maximum. Constrains the maximum that the I term will output
// @Range: 0 1
// @Increment: 0.01
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// @User: Standard
// @Param: RAT_PIT_ILMI
// @DisplayName: Pitch axis rate controller I-term leak minimum
// @Description: Point below which I-term will not leak down
// @Range: 0 1
// @User: Advanced
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// @Param: RAT_PIT_D
// @DisplayName: Pitch axis rate controller D gain
// @Description: Pitch axis rate controller D gain. Compensates for short-term change in desired pitch rate vs actual pitch rate
// @Range: 0.0 0.03
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// @Increment: 0.001
// @User: Standard
// @Param: RAT_PIT_FF
// @DisplayName: Pitch axis rate controller feed forward
// @Description: Pitch axis rate controller feed forward
// @Range: 0.05 0.5
// @Increment: 0.001
// @User: Standard
// @Param: RAT_PIT_FLTT
// @DisplayName: Pitch axis rate controller target frequency in Hz
// @Description: Pitch axis rate controller target frequency in Hz
// @Range: 5 50
// @Increment: 1
// @Units: Hz
// @User: Standard
// @Param: RAT_PIT_FLTE
// @DisplayName: Pitch axis rate controller error frequency in Hz
// @Description: Pitch axis rate controller error frequency in Hz
// @Range: 5 50
// @Increment: 1
// @Units: Hz
// @User: Standard
// @Param: RAT_PIT_FLTD
// @DisplayName: Pitch axis rate controller derivative frequency in Hz
// @Description: Pitch axis rate controller derivative frequency in Hz
// @Range: 0 50
// @Increment: 1
// @Units: Hz
// @User: Standard
// @Param: RAT_PIT_SMAX
// @DisplayName: Pitch 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
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AP_SUBGROUPINFO(_pid_rate_pitch, "RAT_PIT_", 3, AC_AttitudeControl_Heli, AC_HELI_PID),
// @Param: RAT_YAW_P
// @DisplayName: Yaw axis rate controller P gain
// @Description: Yaw axis rate controller P gain. Corrects in proportion to the difference between the desired yaw rate vs actual yaw rate
// @Range: 0.180 0.60
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// @Increment: 0.005
// @User: Standard
// @Param: RAT_YAW_I
// @DisplayName: Yaw axis rate controller I gain
// @Description: Yaw axis rate controller I gain. Corrects long-term difference in desired yaw rate vs actual yaw rate
// @Range: 0.01 0.2
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// @Increment: 0.01
// @User: Standard
// @Param: RAT_YAW_IMAX
// @DisplayName: Yaw axis rate controller I gain maximum
// @Description: Yaw axis rate controller I gain maximum. Constrains the maximum that the I term will output
// @Range: 0 1
// @Increment: 0.01
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// @User: Standard
// @Param: RAT_YAW_ILMI
// @DisplayName: Yaw axis rate controller I-term leak minimum
// @Description: Point below which I-term will not leak down
// @Range: 0 1
// @User: Advanced
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// @Param: RAT_YAW_D
// @DisplayName: Yaw axis rate controller D gain
// @Description: Yaw axis rate controller D gain. Compensates for short-term change in desired yaw rate vs actual yaw rate
// @Range: 0.000 0.02
// @Increment: 0.001
// @User: Standard
// @Param: RAT_YAW_FF
// @DisplayName: Yaw axis rate controller feed forward
// @Description: Yaw axis rate controller feed forward
// @Range: 0 0.5
// @Increment: 0.001
// @User: Standard
// @Param: RAT_YAW_FLTT
// @DisplayName: Yaw axis rate controller target frequency in Hz
// @Description: Yaw axis rate controller target frequency in Hz
// @Range: 5 50
// @Increment: 1
// @Units: Hz
// @User: Standard
// @Param: RAT_YAW_FLTE
// @DisplayName: Yaw axis rate controller error frequency in Hz
// @Description: Yaw axis rate controller error frequency in Hz
// @Range: 5 50
// @Increment: 1
// @Units: Hz
// @User: Standard
// @Param: RAT_YAW_FLTD
// @DisplayName: Yaw axis rate controller derivative frequency in Hz
// @Description: Yaw axis rate controller derivative frequency in Hz
// @Range: 0 50
// @Increment: 1
// @Units: Hz
// @User: Standard
// @Param: RAT_YAW_SMAX
// @DisplayName: Yaw 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
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AP_SUBGROUPINFO(_pid_rate_yaw, "RAT_YAW_", 4, AC_AttitudeControl_Heli, AC_HELI_PID),
// @Param: PIRO_COMP
// @DisplayName: Piro Comp Enable
// @Description: Pirouette compensation enabled
// @Values: 0:Disabled,1:Enabled
// @User: Advanced
AP_GROUPINFO("PIRO_COMP", 5, AC_AttitudeControl_Heli, _piro_comp_enabled, 0),
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AP_GROUPEND
};
// passthrough_bf_roll_pitch_rate_yaw - passthrough the pilots roll and pitch inputs directly to swashplate for flybar acro mode
void AC_AttitudeControl_Heli::passthrough_bf_roll_pitch_rate_yaw(float roll_passthrough, float pitch_passthrough, float yaw_rate_bf_cds)
{
// convert from centidegrees on public interface to radians
float yaw_rate_bf_rads = radians(yaw_rate_bf_cds * 0.01f);
// store roll, pitch and passthroughs
// NOTE: this abuses yaw_rate_bf_rads
_passthrough_roll = roll_passthrough;
_passthrough_pitch = pitch_passthrough;
_passthrough_yaw = degrees(yaw_rate_bf_rads) * 100.0f;
// set rate controller to use pass through
_flags_heli.flybar_passthrough = true;
// set bf rate targets to current body frame rates (i.e. relax and be ready for vehicle to switch out of acro)
_ang_vel_target.x = _ahrs.get_gyro().x;
_ang_vel_target.y = _ahrs.get_gyro().y;
// accel limit desired yaw rate
if (get_accel_yaw_max_radss() > 0.0f) {
float rate_change_limit_rads = get_accel_yaw_max_radss() * _dt;
float rate_change_rads = yaw_rate_bf_rads - _ang_vel_target.z;
rate_change_rads = constrain_float(rate_change_rads, -rate_change_limit_rads, rate_change_limit_rads);
_ang_vel_target.z += rate_change_rads;
} else {
_ang_vel_target.z = yaw_rate_bf_rads;
}
integrate_bf_rate_error_to_angle_errors();
_att_error_rot_vec_rad.x = 0;
_att_error_rot_vec_rad.y = 0;
// update our earth-frame angle targets
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Vector3f att_error_euler_rad;
// convert angle error rotation vector into 321-intrinsic euler angle difference
// NOTE: this results an an approximation linearized about the vehicle's attitude
if (ang_vel_to_euler_rate(Vector3f(_ahrs.roll, _ahrs.pitch, _ahrs.yaw), _att_error_rot_vec_rad, att_error_euler_rad)) {
_euler_angle_target.x = wrap_PI(att_error_euler_rad.x + _ahrs.roll);
_euler_angle_target.y = wrap_PI(att_error_euler_rad.y + _ahrs.pitch);
_euler_angle_target.z = wrap_2PI(att_error_euler_rad.z + _ahrs.yaw);
}
// handle flipping over pitch axis
if (_euler_angle_target.y > M_PI / 2.0f) {
_euler_angle_target.x = wrap_PI(_euler_angle_target.x + M_PI);
_euler_angle_target.y = wrap_PI(M_PI - _euler_angle_target.x);
_euler_angle_target.z = wrap_2PI(_euler_angle_target.z + M_PI);
}
if (_euler_angle_target.y < -M_PI / 2.0f) {
_euler_angle_target.x = wrap_PI(_euler_angle_target.x + M_PI);
_euler_angle_target.y = wrap_PI(-M_PI - _euler_angle_target.x);
_euler_angle_target.z = wrap_2PI(_euler_angle_target.z + M_PI);
}
// convert body-frame angle errors to body-frame rate targets
_ang_vel_body = update_ang_vel_target_from_att_error(_att_error_rot_vec_rad);
// set body-frame roll/pitch rate target to current desired rates which are the vehicle's actual rates
_ang_vel_body.x = _ang_vel_target.x;
_ang_vel_body.y = _ang_vel_target.y;
// add desired target to yaw
_ang_vel_body.z += _ang_vel_target.z;
_thrust_error_angle = _att_error_rot_vec_rad.xy().length();
}
void AC_AttitudeControl_Heli::integrate_bf_rate_error_to_angle_errors()
{
// Integrate the angular velocity error into the attitude error
_att_error_rot_vec_rad += (_ang_vel_target - _ahrs.get_gyro()) * _dt;
// Constrain attitude error
_att_error_rot_vec_rad.x = constrain_float(_att_error_rot_vec_rad.x, -AC_ATTITUDE_HELI_ACRO_OVERSHOOT_ANGLE_RAD, AC_ATTITUDE_HELI_ACRO_OVERSHOOT_ANGLE_RAD);
_att_error_rot_vec_rad.y = constrain_float(_att_error_rot_vec_rad.y, -AC_ATTITUDE_HELI_ACRO_OVERSHOOT_ANGLE_RAD, AC_ATTITUDE_HELI_ACRO_OVERSHOOT_ANGLE_RAD);
_att_error_rot_vec_rad.z = constrain_float(_att_error_rot_vec_rad.z, -AC_ATTITUDE_HELI_ACRO_OVERSHOOT_ANGLE_RAD, AC_ATTITUDE_HELI_ACRO_OVERSHOOT_ANGLE_RAD);
}
// subclass non-passthrough too, for external gyro, no flybar
void AC_AttitudeControl_Heli::input_rate_bf_roll_pitch_yaw(float roll_rate_bf_cds, float pitch_rate_bf_cds, float yaw_rate_bf_cds)
{
_passthrough_yaw = yaw_rate_bf_cds;
AC_AttitudeControl::input_rate_bf_roll_pitch_yaw(roll_rate_bf_cds, pitch_rate_bf_cds, yaw_rate_bf_cds);
}
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//
// rate controller (body-frame) methods
//
// rate_controller_run - run lowest level rate controller and send outputs to the motors
// should be called at 100hz or more
void AC_AttitudeControl_Heli::rate_controller_run()
{
_ang_vel_body += _sysid_ang_vel_body;
Vector3f gyro_latest = _ahrs.get_gyro_latest();
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// call rate controllers and send output to motors object
// if using a flybar passthrough roll and pitch directly to motors
if (_flags_heli.flybar_passthrough) {
_motors.set_roll(_passthrough_roll / 4500.0f);
_motors.set_pitch(_passthrough_pitch / 4500.0f);
} else {
rate_bf_to_motor_roll_pitch(gyro_latest, _ang_vel_body.x, _ang_vel_body.y);
}
if (_flags_heli.tail_passthrough) {
_motors.set_yaw(_passthrough_yaw / 4500.0f);
} else {
_motors.set_yaw(rate_target_to_motor_yaw(gyro_latest.z, _ang_vel_body.z));
}
_sysid_ang_vel_body.zero();
_actuator_sysid.zero();
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}
// Update Alt_Hold angle maximum
void AC_AttitudeControl_Heli::update_althold_lean_angle_max(float throttle_in)
{
float althold_lean_angle_max = acosf(constrain_float(throttle_in / AC_ATTITUDE_HELI_ANGLE_LIMIT_THROTTLE_MAX, 0.0f, 1.0f));
_althold_lean_angle_max = _althold_lean_angle_max + (_dt / (_dt + _angle_limit_tc)) * (althold_lean_angle_max - _althold_lean_angle_max);
}
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//
// private methods
//
//
// body-frame rate controller
//
// rate_bf_to_motor_roll_pitch - ask the rate controller to calculate the motor outputs to achieve the target rate in radians/second
void AC_AttitudeControl_Heli::rate_bf_to_motor_roll_pitch(const Vector3f &rate_rads, float rate_roll_target_rads, float rate_pitch_target_rads)
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{
if (_flags_heli.leaky_i) {
_pid_rate_roll.update_leaky_i(AC_ATTITUDE_HELI_RATE_INTEGRATOR_LEAK_RATE);
}
float roll_pid = _pid_rate_roll.update_all(rate_roll_target_rads, rate_rads.x, _dt, _motors.limit.roll) + _actuator_sysid.x;
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if (_flags_heli.leaky_i) {
_pid_rate_pitch.update_leaky_i(AC_ATTITUDE_HELI_RATE_INTEGRATOR_LEAK_RATE);
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}
float pitch_pid = _pid_rate_pitch.update_all(rate_pitch_target_rads, rate_rads.y, _dt, _motors.limit.pitch) + _actuator_sysid.y;
// use pid library to calculate ff
float roll_ff = _pid_rate_roll.get_ff();
float pitch_ff = _pid_rate_pitch.get_ff();
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// add feed forward and final output
float roll_out = roll_pid + roll_ff;
float pitch_out = pitch_pid + pitch_ff;
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// constrain output
roll_out = constrain_float(roll_out, -AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX, AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX);
pitch_out = constrain_float(pitch_out, -AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX, AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX);
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// output to motors
_motors.set_roll(roll_out);
_motors.set_pitch(pitch_out);
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// Piro-Comp, or Pirouette Compensation is a pre-compensation calculation, which basically rotates the Roll and Pitch Rate I-terms as the
// helicopter rotates in yaw. Much of the built-up I-term is needed to tip the disk into the incoming wind. Fast yawing can create an instability
// as the built-up I-term in one axis must be reduced, while the other increases. This helps solve that by rotating the I-terms before the error occurs.
// It does assume that the rotor aerodynamics and mechanics are essentially symmetrical about the main shaft, which is a generally valid assumption.
if (_piro_comp_enabled) {
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// used to hold current I-terms while doing piro comp:
const float piro_roll_i = _pid_rate_roll.get_i();
const float piro_pitch_i = _pid_rate_pitch.get_i();
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Vector2f yawratevector;
yawratevector.x = cosf(-rate_rads.z * _dt);
yawratevector.y = sinf(-rate_rads.z * _dt);
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yawratevector.normalize();
_pid_rate_roll.set_integrator(piro_roll_i * yawratevector.x - piro_pitch_i * yawratevector.y);
_pid_rate_pitch.set_integrator(piro_pitch_i * yawratevector.x + piro_roll_i * yawratevector.y);
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}
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}
// rate_bf_to_motor_yaw - ask the rate controller to calculate the motor outputs to achieve the target rate in radians/second
float AC_AttitudeControl_Heli::rate_target_to_motor_yaw(float rate_yaw_actual_rads, float rate_target_rads)
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{
if (!((AP_MotorsHeli&)_motors).rotor_runup_complete()) {
_pid_rate_yaw.update_leaky_i(AC_ATTITUDE_HELI_RATE_INTEGRATOR_LEAK_RATE);
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}
float pid = _pid_rate_yaw.update_all(rate_target_rads, rate_yaw_actual_rads, _dt, _motors.limit.yaw) + _actuator_sysid.z;
// use pid library to calculate ff
float vff = _pid_rate_yaw.get_ff()*_feedforward_scalar;
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// add feed forward
float yaw_out = pid + vff;
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// constrain output
yaw_out = constrain_float(yaw_out, -AC_ATTITUDE_RATE_YAW_CONTROLLER_OUT_MAX, AC_ATTITUDE_RATE_YAW_CONTROLLER_OUT_MAX);
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// output to motors
return yaw_out;
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}
//
// throttle functions
//
void AC_AttitudeControl_Heli::set_throttle_out(float throttle_in, bool apply_angle_boost, float filter_cutoff)
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{
_throttle_in = throttle_in;
update_althold_lean_angle_max(throttle_in);
_motors.set_throttle_filter_cutoff(filter_cutoff);
_motors.set_throttle(throttle_in);
// Clear angle_boost for logging purposes
_angle_boost = 0.0f;
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}
// Command an euler roll and pitch angle and an euler yaw rate with angular velocity feedforward and smoothing
void AC_AttitudeControl_Heli::input_euler_angle_roll_pitch_euler_rate_yaw(float euler_roll_angle_cd, float euler_pitch_angle_cd, float euler_yaw_rate_cds)
{
if (_inverted_flight) {
euler_roll_angle_cd = wrap_180_cd(euler_roll_angle_cd + 18000);
}
AC_AttitudeControl::input_euler_angle_roll_pitch_euler_rate_yaw(euler_roll_angle_cd, euler_pitch_angle_cd, euler_yaw_rate_cds);
}
// Command an euler roll, pitch and yaw angle with angular velocity feedforward and smoothing
void AC_AttitudeControl_Heli::input_euler_angle_roll_pitch_yaw(float euler_roll_angle_cd, float euler_pitch_angle_cd, float euler_yaw_angle_cd, bool slew_yaw)
{
if (_inverted_flight) {
euler_roll_angle_cd = wrap_180_cd(euler_roll_angle_cd + 18000);
}
AC_AttitudeControl::input_euler_angle_roll_pitch_yaw(euler_roll_angle_cd, euler_pitch_angle_cd, euler_yaw_angle_cd, slew_yaw);
}