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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.h>
// table of user settable parameters
const AP_Param::GroupInfo AC_AttitudeControl_Heli::var_info[] PROGMEM = {
// @Param: RATE_RP_MAX
// @DisplayName: Angle Rate Roll-Pitch max
// @Description: maximum rotation rate in roll/pitch axis requested by angle controller used in stabilize, loiter, rtl, auto flight modes
// @Units: Centi-Degrees/Sec
// @Range: 9000 36000
// @Increment: 500
// @User: Advanced
AP_GROUPINFO("RATE_RP_MAX", 0, AC_AttitudeControl_Heli, _angle_rate_rp_max, AC_ATTITUDE_CONTROL_RATE_RP_MAX_DEFAULT),
// @Param: RATE_Y_MAX
// @DisplayName: Angle Rate Yaw max
// @Description: maximum rotation rate in roll/pitch axis requested by angle controller used in stabilize, loiter, rtl, auto flight modes
// @Units: Centi-Degrees/Sec
// @Range: 4500 18000
// @Increment: 500
// @User: Advanced
AP_GROUPINFO("RATE_Y_MAX", 1, AC_AttitudeControl_Heli, _angle_rate_y_max, AC_ATTITUDE_CONTROL_RATE_Y_MAX_DEFAULT),
// @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_Heli, _slew_yaw, AC_ATTITUDE_CONTROL_SLEW_YAW_DEFAULT),
// @Param: ACCEL_RP_MAX
// @DisplayName: Acceleration Max for Roll/Pitch
// @Description: Maximum acceleration in roll/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_RP_MAX", 3, AC_AttitudeControl_Heli, _accel_rp_max, AC_ATTITUDE_CONTROL_ACCEL_RP_MAX_DEFAULT),
// @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_Heli, _accel_y_max, AC_ATTITUDE_CONTROL_ACCEL_Y_MAX_DEFAULT),
// @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_Heli, _rate_bf_ff_enabled, AC_ATTITUDE_CONTROL_RATE_BF_FF_DEFAULT),
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)
{
// store roll and pitch passthroughs
_passthrough_roll = roll_passthrough;
_passthrough_pitch = pitch_passthrough;
// 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)
_rate_bf_desired.x = _ahrs.get_gyro().x * AC_ATTITUDE_CONTROL_DEGX100;
_rate_bf_desired.y = _ahrs.get_gyro().y * AC_ATTITUDE_CONTROL_DEGX100;
// accel limit desired yaw rate
if (_accel_y_max > 0.0f) {
float rate_change_limit = _accel_y_max * _dt;
float rate_change = yaw_rate_bf - _rate_bf_desired.z;
rate_change = constrain_float(rate_change, -rate_change_limit, rate_change_limit);
_rate_bf_desired.z += rate_change;
} else {
_rate_bf_desired.z = yaw_rate_bf;
}
integrate_bf_rate_error_to_angle_errors();
_angle_bf_error.x = 0;
_angle_bf_error.y = 0;
// update our earth-frame angle targets
Vector3f angle_ef_error;
if (frame_conversion_bf_to_ef(_angle_bf_error, angle_ef_error)) {
_angle_ef_target.x = wrap_180_cd_float(angle_ef_error.x + _ahrs.roll_sensor);
_angle_ef_target.y = wrap_180_cd_float(angle_ef_error.y + _ahrs.pitch_sensor);
_angle_ef_target.z = wrap_360_cd_float(angle_ef_error.z + _ahrs.yaw_sensor);
}
// handle flipping over pitch axis
if (_angle_ef_target.y > 9000.0f) {
_angle_ef_target.x = wrap_180_cd_float(_angle_ef_target.x + 18000.0f);
_angle_ef_target.y = wrap_180_cd_float(18000.0f - _angle_ef_target.x);
_angle_ef_target.z = wrap_360_cd_float(_angle_ef_target.z + 18000.0f);
}
if (_angle_ef_target.y < -9000.0f) {
_angle_ef_target.x = wrap_180_cd_float(_angle_ef_target.x + 18000.0f);
_angle_ef_target.y = wrap_180_cd_float(-18000.0f - _angle_ef_target.x);
_angle_ef_target.z = wrap_360_cd_float(_angle_ef_target.z + 18000.0f);
}
// convert body-frame angle errors to body-frame rate targets
update_rate_bf_targets();
// set body-frame roll/pitch rate target to current desired rates which are the vehicle's actual rates
_rate_bf_target.x = _rate_bf_desired.x;
_rate_bf_target.y = _rate_bf_desired.y;
// add desired target to yaw
_rate_bf_target.z += _rate_bf_desired.z;
}
//
// 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);
_motors.set_pitch(_passthrough_pitch);
} else {
rate_bf_to_motor_roll_pitch(_rate_bf_target.x, _rate_bf_target.y);
}
_motors.set_yaw(rate_bf_to_motor_yaw(_rate_bf_target.z));
}
//
// 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 centi-degrees / second
void AC_AttitudeControl_Heli::rate_bf_to_motor_roll_pitch(float rate_roll_target_cds, float rate_pitch_target_cds)
{
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, rate_pitch_error; // simply target_rate - current_rate
float roll_out, pitch_out;
const Vector3f& gyro = _ahrs.get_gyro(); // get current rates
// calculate error
rate_roll_error = rate_roll_target_cds - gyro.x * AC_ATTITUDE_CONTROL_DEGX100;
rate_pitch_error = rate_pitch_target_cds - gyro.y * AC_ATTITUDE_CONTROL_DEGX100;
// call p and d controllers
roll_pd = _pid_rate_roll.get_p(rate_roll_error) + _pid_rate_roll.get_d(rate_roll_error, _dt);
pitch_pd = _pid_rate_pitch.get_p(rate_pitch_error) + _pid_rate_pitch.get_d(rate_pitch_error, _dt);
// 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<0)||(roll_i<0&&rate_roll_error>0))){
if (((AP_MotorsHeli&)_motors).has_flybar()) { // Mechanical Flybars get regular integral for rate auto trim
if (rate_roll_target_cds > -50 && rate_roll_target_cds < 50){ // Frozen at high rates
roll_i = _pid_rate_roll.get_i(rate_roll_error, _dt);
}
}else{
if (_flags_heli.leaky_i){
roll_i = ((AC_HELI_PID&)_pid_rate_roll).get_leaky_i(rate_roll_error, _dt, AC_ATTITUDE_HELI_RATE_INTEGRATOR_LEAK_RATE);
}else{
roll_i = _pid_rate_roll.get_i(rate_roll_error, _dt);
}
}
}
// 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<0)||(pitch_i<0&&rate_pitch_error>0))){
if (((AP_MotorsHeli&)_motors).has_flybar()) { // Mechanical Flybars get regular integral for rate auto trim
if (rate_pitch_target_cds > -50 && rate_pitch_target_cds < 50){ // Frozen at high rates
pitch_i = _pid_rate_pitch.get_i(rate_pitch_error, _dt);
}
}else{
if (_flags_heli.leaky_i) {
pitch_i = ((AC_HELI_PID&)_pid_rate_pitch).get_leaky_i(rate_pitch_error, _dt, AC_ATTITUDE_HELI_RATE_INTEGRATOR_LEAK_RATE);
}else{
pitch_i = _pid_rate_pitch.get_i(rate_pitch_error, _dt);
}
}
}
roll_ff = roll_feedforward_filter.apply(((AC_HELI_PID&)_pid_rate_roll).get_ff(rate_roll_target_cds));
pitch_ff = pitch_feedforward_filter.apply(((AC_HELI_PID&)_pid_rate_pitch).get_ff(rate_pitch_target_cds));
// add feed forward and final output
roll_out = roll_pd + roll_i + roll_ff;
pitch_out = pitch_pd + pitch_i + pitch_ff;
// constrain output and update limit flags
if ((float)fabs(roll_out) > AC_ATTITUDE_RATE_RP_CONTROLLER_OUT_MAX) {
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 ((float)fabs(pitch_out) > 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);
_flags_heli.limit_pitch = true;
}else{
_flags_heli.limit_pitch = false;
}
// output to motors
_motors.set_roll(roll_out);
_motors.set_pitch(pitch_out);
/*
#if HELI_CC_COMP == ENABLED
static LowPassFilterFloat rate_dynamics_filter; // Rate Dynamics filter
#endif
#if HELI_CC_COMP == ENABLED
rate_dynamics_filter.set_cutoff_frequency(0.01f, 4.0f);
#endif
#if AC_ATTITUDE_HELI_CC_COMP == ENABLED
// Do cross-coupling compensation for low rpm helis
// Credit: Jolyon Saunders
// Note: This is not widely tested at this time. Will not be used by default yet.
float cc_axis_ratio = 2.0f; // Ratio of compensation on pitch vs roll axes. Number >1 means pitch is affected more than roll
float cc_kp = 0.0002f; // Compensation p term. Setting this to zero gives h_phang only, while increasing it will increase the p term of correction
float cc_kd = 0.127f; // Compensation d term, scaled. This accounts for flexing of the blades, dampers etc. Originally was (motors.ext_gyro_gain * 0.0001)
float cc_angle, cc_total_output;
uint32_t cc_roll_d, cc_pitch_d, cc_sum_d;
int32_t cc_scaled_roll;
int32_t cc_roll_output; // Used to temporarily hold output while rotation is being calculated
int32_t cc_pitch_output; // Used to temporarily hold output while rotation is being calculated
static int32_t last_roll_output = 0;
static int32_t last_pitch_output = 0;
cc_scaled_roll = roll_output / cc_axis_ratio; // apply axis ratio to roll
cc_total_output = safe_sqrt(cc_scaled_roll * cc_scaled_roll + pitch_output * pitch_output) * cc_kp;
// find the delta component
cc_roll_d = (roll_output - last_roll_output) / cc_axis_ratio;
cc_pitch_d = pitch_output - last_pitch_output;
cc_sum_d = safe_sqrt(cc_roll_d * cc_roll_d + cc_pitch_d * cc_pitch_d);
// do the magic.
cc_angle = cc_kd * cc_sum_d * cc_total_output - cc_total_output * motors.get_phase_angle();
// smooth angle variations, apply constraints
cc_angle = rate_dynamics_filter.apply(cc_angle);
cc_angle = constrain_float(cc_angle, -90.0f, 0.0f);
cc_angle = radians(cc_angle);
// Make swash rate vector
Vector2f swashratevector;
swashratevector.x = cosf(cc_angle);
swashratevector.y = sinf(cc_angle);
swashratevector.normalize();
// rotate the output
cc_roll_output = roll_output;
cc_pitch_output = pitch_output;
roll_output = - (cc_pitch_output * swashratevector.y - cc_roll_output * swashratevector.x);
pitch_output = cc_pitch_output * swashratevector.x + cc_roll_output * swashratevector.y;
// make current outputs old, for next iteration
last_roll_output = cc_roll_output;
last_pitch_output = cc_pitch_output;
# endif // HELI_CC_COMP
#if AC_ATTITUDE_HELI_PIRO_COMP == ENABLED
if (control_mode <= ACRO){
int32_t piro_roll_i, piro_pitch_i; // used to hold i term while doing prio comp
piro_roll_i = roll_i;
piro_pitch_i = pitch_i;
Vector2f yawratevector;
yawratevector.x = cos(-omega.z/100);
yawratevector.y = sin(-omega.z/100);
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;
g.pid_rate_pitch.set_integrator(pitch_i);
g.pid_rate_roll.set_integrator(roll_i);
}
#endif //HELI_PIRO_COMP
*/
}
// rate_bf_to_motor_yaw - ask the rate controller to calculate the motor outputs to achieve the target rate in centi-degrees / second
float AC_AttitudeControl_Heli::rate_bf_to_motor_yaw(float rate_target_cds)
{
float pd,i,ff; // used to capture pid values for logging
float current_rate; // this iteration's rate
float rate_error; // simply target_rate - current_rate
float yaw_out;
// get current rate
// To-Do: make getting gyro rates more efficient?
current_rate = (_ahrs.get_gyro().z * AC_ATTITUDE_CONTROL_DEGX100);
// calculate error and call pid controller
rate_error = rate_target_cds - current_rate;
pd = _pid_rate_yaw.get_p(rate_error) + _pid_rate_yaw.get_d(rate_error, _dt);
// 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<0)||(i<0&&rate_error>0))) {
if (((AP_MotorsHeli&)_motors).motor_runup_complete()) {
i = _pid_rate_yaw.get_i(rate_error, _dt);
} else {
i = ((AC_HELI_PID&)_pid_rate_yaw).get_leaky_i(rate_error, _dt, AC_ATTITUDE_HELI_RATE_INTEGRATOR_LEAK_RATE); // If motor is not running use leaky I-term to avoid excessive build-up
}
}
ff = yaw_feedforward_filter.apply(((AC_HELI_PID&)_pid_rate_yaw).get_ff(rate_target_cds));
// add feed forward
yaw_out = pd + i + ff;
// constrain output and update limit flag
if ((float)fabs(yaw_out) > AC_ATTITUDE_RATE_YAW_CONTROLLER_OUT_MAX) {
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;
}
// output to motors
return yaw_out;
}
//
// throttle functions
//
// get_angle_boost - returns a throttle including compensation for roll/pitch angle
// throttle value should be 0 ~ 1000
int16_t AC_AttitudeControl_Heli::get_angle_boost(int16_t throttle_pwm)
{
// no angle boost for trad helis
_angle_boost = 0;
return throttle_pwm;
}
// update_feedforward_filter_rate - Sets LPF cutoff frequency
void AC_AttitudeControl_Heli::update_feedforward_filter_rates(float time_step)
{
pitch_feedforward_filter.set_cutoff_frequency(time_step, AC_ATTITUDE_HELI_RATE_FF_FILTER);
roll_feedforward_filter.set_cutoff_frequency(time_step, AC_ATTITUDE_HELI_RATE_FF_FILTER);
yaw_feedforward_filter.set_cutoff_frequency(time_step, AC_ATTITUDE_HELI_RATE_FF_FILTER);
}
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