ardupilot/libraries/AC_AttitudeControl/AC_AttitudeControl_Heli.cpp

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-
#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: PIRO_COMP
// @DisplayName: Piro Comp Enable
// @Description: Pirouette compensation enabled
// @Values: 0:Disabled 1:Enabled
// @User: Advanced
AP_GROUPINFO("PIRO_COMP", 0, AC_AttitudeControl_Heli, _piro_comp_enabled, 0),
// @Param: HOVR_ROL_TRM
// @DisplayName: Hover Roll Trim
// @Description: Trim the hover roll angle to counter tail rotor thrust in a hover
// @Units: Centi-Degrees
// @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. Converts the difference between desired roll rate and actual roll rate into a motor speed output
// @Range: 0.08 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: 0.01 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 motor output that the I gain will output
// @Range: 0 1
// @Increment: 0.01
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// @User: Standard
// @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: 0.001 0.03
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// @Increment: 0.001
// @User: Standard
// @Param: RAT_RLL_FILT
// @DisplayName: Roll axis rate conroller input frequency in Hz
// @Description: Roll axis rate conroller input frequency in Hz
// @Units: Hz
// @Range: 1 20
// @Increment: 1
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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. Converts the difference between desired pitch rate and actual pitch rate into a motor speed output
// @Range: 0.08 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: 0.01 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 motor output that the I gain will output
// @Range: 0 1
// @Increment: 0.01
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// @User: Standard
// @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: 0.001 0.03
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// @Increment: 0.001
// @User: Standard
// @Param: RAT_PIT_FILT
// @DisplayName: Pitch axis rate conroller input frequency in Hz
// @Description: Pitch axis rate conroller input frequency in Hz
// @Units: Hz
// @Range: 1 20
// @Increment: 1
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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. Converts the difference between desired yaw rate and actual yaw rate into a motor speed output
// @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 0.06
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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 motor output that the I gain will output
// @Range: 0 1
// @Increment: 0.01
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// @User: Standard
// @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_FILT
// @DisplayName: Yaw axis rate conroller input frequency in Hz
// @Description: Yaw axis rate conroller input frequency in Hz
// @Units: Hz
// @Range: 1 20
// @Increment: 1
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AP_SUBGROUPINFO(_pid_rate_yaw, "RAT_YAW_", 4, AC_AttitudeControl_Heli, AC_HELI_PID),
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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)
_attitude_target_ang_vel.x = _ahrs.get_gyro().x;
_attitude_target_ang_vel.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 - _attitude_target_ang_vel.z;
rate_change_rads = constrain_float(rate_change_rads, -rate_change_limit_rads, rate_change_limit_rads);
_attitude_target_ang_vel.z += rate_change_rads;
} else {
_attitude_target_ang_vel.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)) {
_attitude_target_euler_angle.x = wrap_PI(att_error_euler_rad.x + _ahrs.roll);
_attitude_target_euler_angle.y = wrap_PI(att_error_euler_rad.y + _ahrs.pitch);
_attitude_target_euler_angle.z = wrap_2PI(att_error_euler_rad.z + _ahrs.yaw);
}
// handle flipping over pitch axis
if (_attitude_target_euler_angle.y > M_PI/2.0f) {
_attitude_target_euler_angle.x = wrap_PI(_attitude_target_euler_angle.x + M_PI);
_attitude_target_euler_angle.y = wrap_PI(M_PI - _attitude_target_euler_angle.x);
_attitude_target_euler_angle.z = wrap_2PI(_attitude_target_euler_angle.z + M_PI);
}
if (_attitude_target_euler_angle.y < -M_PI/2.0f) {
_attitude_target_euler_angle.x = wrap_PI(_attitude_target_euler_angle.x + M_PI);
_attitude_target_euler_angle.y = wrap_PI(-M_PI - _attitude_target_euler_angle.x);
_attitude_target_euler_angle.z = wrap_2PI(_attitude_target_euler_angle.z + M_PI);
}
// convert body-frame angle errors to body-frame rate targets
_rate_target_ang_vel = 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
_rate_target_ang_vel.x = _attitude_target_ang_vel.x;
_rate_target_ang_vel.y = _attitude_target_ang_vel.y;
// add desired target to yaw
_rate_target_ang_vel.z += _attitude_target_ang_vel.z;
_thrust_error_angle = norm(_att_error_rot_vec_rad.x, _att_error_rot_vec_rad.y);
}
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 += (_attitude_target_ang_vel - _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()
{
// 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(_rate_target_ang_vel.x, _rate_target_ang_vel.y);
}
if (_flags_heli.tail_passthrough) {
_motors.set_yaw(_passthrough_yaw/4500.0f);
} else {
_motors.set_yaw(rate_target_to_motor_yaw(_rate_target_ang_vel.z));
}
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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 = acos(constrain_float(_throttle_in/AC_ATTITUDE_CONTROL_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(float rate_roll_target_rads, float rate_pitch_target_rads)
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{
float roll_pd, roll_i, roll_ff; // used to capture pid values
float pitch_pd, pitch_i, pitch_ff; // used to capture pid values
float rate_roll_error_rads, rate_pitch_error_rads; // simply target_rate - current_rate
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float roll_out, pitch_out;
const Vector3f& gyro = _ahrs.get_gyro(); // get current rates
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// calculate error
rate_roll_error_rads = rate_roll_target_rads - gyro.x;
rate_pitch_error_rads = rate_pitch_target_rads - gyro.y;
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// pass error to PID controller
_pid_rate_roll.set_input_filter_all(rate_roll_error_rads);
_pid_rate_roll.set_desired_rate(rate_roll_target_rads);
_pid_rate_pitch.set_input_filter_all(rate_pitch_error_rads);
_pid_rate_pitch.set_desired_rate(rate_pitch_target_rads);
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// call p and d controllers
roll_pd = _pid_rate_roll.get_p() + _pid_rate_roll.get_d();
pitch_pd = _pid_rate_pitch.get_p() + _pid_rate_pitch.get_d();
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// get roll i term
roll_i = _pid_rate_roll.get_integrator();
// update i term as long as we haven't breached the limits or the I term will certainly reduce
if (!_flags_heli.limit_roll || ((roll_i>0&&rate_roll_error_rads<0)||(roll_i<0&&rate_roll_error_rads>0))){
if (_flags_heli.leaky_i){
roll_i = _pid_rate_roll.get_leaky_i(AC_ATTITUDE_HELI_RATE_INTEGRATOR_LEAK_RATE);
}else{
roll_i = _pid_rate_roll.get_i();
}
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}
// get pitch i term
pitch_i = _pid_rate_pitch.get_integrator();
// update i term as long as we haven't breached the limits or the I term will certainly reduce
if (!_flags_heli.limit_pitch || ((pitch_i>0&&rate_pitch_error_rads<0)||(pitch_i<0&&rate_pitch_error_rads>0))){
if (_flags_heli.leaky_i) {
pitch_i = _pid_rate_pitch.get_leaky_i(AC_ATTITUDE_HELI_RATE_INTEGRATOR_LEAK_RATE);
}else{
pitch_i = _pid_rate_pitch.get_i();
}
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}
// For legacy reasons, we convert to centi-degrees before inputting to the feedforward
roll_ff = roll_feedforward_filter.apply(_pid_rate_roll.get_vff(rate_roll_target_rads), _dt);
pitch_ff = pitch_feedforward_filter.apply(_pid_rate_pitch.get_vff(rate_pitch_target_rads), _dt);
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// add feed forward and final output
roll_out = roll_pd + roll_i + roll_ff;
pitch_out = pitch_pd + pitch_i + pitch_ff;
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// constrain output and update limit flags
if (fabsf(roll_out) > AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX) {
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roll_out = constrain_float(roll_out,-AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX,AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX);
_flags_heli.limit_roll = true;
}else{
_flags_heli.limit_roll = false;
}
if (fabsf(pitch_out) > AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX) {
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pitch_out = constrain_float(pitch_out,-AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX,AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX);
_flags_heli.limit_pitch = true;
}else{
_flags_heli.limit_pitch = false;
}
// 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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int32_t piro_roll_i, piro_pitch_i; // used to hold I-terms while doing piro comp
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piro_roll_i = roll_i;
piro_pitch_i = pitch_i;
Vector2f yawratevector;
yawratevector.x = cosf(-_ahrs.get_gyro().z * _dt);
yawratevector.y = sinf(-_ahrs.get_gyro().z * _dt);
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yawratevector.normalize();
roll_i = piro_roll_i * yawratevector.x - piro_pitch_i * yawratevector.y;
pitch_i = piro_pitch_i * yawratevector.x + piro_roll_i * yawratevector.y;
_pid_rate_pitch.set_integrator(pitch_i);
_pid_rate_roll.set_integrator(roll_i);
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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_target_rads)
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{
float pd,i,vff; // used to capture pid values for logging
float current_rate_rads; // this iteration's rate
float rate_error_rads; // simply target_rate - current_rate
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float yaw_out;
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// get current rate
// To-Do: make getting gyro rates more efficient?
current_rate_rads = _ahrs.get_gyro().z;
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// calculate error and call pid controller
rate_error_rads = rate_target_rads - current_rate_rads;
// pass error to PID controller
_pid_rate_yaw.set_input_filter_all(rate_error_rads);
_pid_rate_yaw.set_desired_rate(rate_target_rads);
// get p and d
pd = _pid_rate_yaw.get_p() + _pid_rate_yaw.get_d();
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// get i term
i = _pid_rate_yaw.get_integrator();
// update i term as long as we haven't breached the limits or the I term will certainly reduce
if (!_flags_heli.limit_yaw || ((i>0&&rate_error_rads<0)||(i<0&&rate_error_rads>0))) {
if (((AP_MotorsHeli&)_motors).rotor_runup_complete()) {
i = _pid_rate_yaw.get_i();
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} else {
i = ((AC_HELI_PID&)_pid_rate_yaw).get_leaky_i(AC_ATTITUDE_HELI_RATE_INTEGRATOR_LEAK_RATE); // If motor is not running use leaky I-term to avoid excessive build-up
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}
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}
// For legacy reasons, we convert to centi-degrees before inputting to the feedforward
vff = yaw_velocity_feedforward_filter.apply(_pid_rate_yaw.get_vff(rate_target_rads), _dt);
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// add feed forward
yaw_out = pd + i + vff;
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// constrain output and update limit flag
if (fabsf(yaw_out) > AC_ATTITUDE_RATE_YAW_CONTROLLER_OUT_MAX) {
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yaw_out = constrain_float(yaw_out,-AC_ATTITUDE_RATE_YAW_CONTROLLER_OUT_MAX,AC_ATTITUDE_RATE_YAW_CONTROLLER_OUT_MAX);
_flags_heli.limit_yaw = true;
}else{
_flags_heli.limit_yaw = false;
}
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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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}