ardupilot/ArduPlane/tailsitter.cpp

344 lines
14 KiB
C++

/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
control code for tailsitters. Enabled by setting Q_FRAME_CLASS=10
or by setting Q_TAILSIT_MOTMX nonzero and Q_FRAME_CLASS and Q_FRAME_TYPE
to a configuration supported by AP_MotorsMatrix
*/
#include <math.h>
#include "Plane.h"
/*
return true when flying a tailsitter
*/
bool QuadPlane::is_tailsitter(void) const
{
return available()
&& ((frame_class == AP_Motors::MOTOR_FRAME_TAILSITTER) || (tailsitter.motor_mask != 0))
&& (tilt.tilt_type != TILT_TYPE_BICOPTER);
}
/*
return true when flying a control surface only tailsitter tailsitter
*/
bool QuadPlane::is_contol_surface_tailsitter(void) const
{
return frame_class == AP_Motors::MOTOR_FRAME_TAILSITTER
&& ( is_zero(tailsitter.vectored_hover_gain) || !SRV_Channels::function_assigned(SRV_Channel::k_tiltMotorLeft));
}
/*
check if we are flying as a tailsitter
*/
bool QuadPlane::tailsitter_active(void)
{
if (!is_tailsitter()) {
return false;
}
if (in_vtol_mode()) {
return true;
}
// check if we are in ANGLE_WAIT fixed wing transition
if (transition_state == TRANSITION_ANGLE_WAIT_FW) {
return true;
}
return false;
}
/*
run output for tailsitters
*/
void QuadPlane::tailsitter_output(void)
{
if (!is_tailsitter() || motor_test.running) {
// if motor test is running we don't want to overwrite it with output_motor_mask or motors_output
return;
}
float tilt_left = 0.0f;
float tilt_right = 0.0f;
// handle forward flight modes and transition to VTOL modes
if (!tailsitter_active() || in_tailsitter_vtol_transition()) {
// get FW controller throttle demand and mask of motors enabled during forward flight
float throttle = SRV_Channels::get_output_scaled(SRV_Channel::k_throttle);
if (hal.util->get_soft_armed() && in_tailsitter_vtol_transition() && !throttle_wait && is_flying()) {
/*
during transitions to vtol mode set the throttle to
hover thrust, center the rudder and set the altitude controller
integrator to the same throttle level
*/
throttle = motors->get_throttle_hover() * 100;
SRV_Channels::set_output_scaled(SRV_Channel::k_rudder, 0);
pos_control->get_accel_z_pid().set_integrator(throttle*10);
// override AP_MotorsTailsitter throttles during back transition
SRV_Channels::set_output_scaled(SRV_Channel::k_throttle, throttle);
SRV_Channels::set_output_scaled(SRV_Channel::k_throttleLeft, throttle);
SRV_Channels::set_output_scaled(SRV_Channel::k_throttleRight, throttle);
}
if (!assisted_flight) {
// set AP_MotorsMatrix throttles for forward flight
motors->output_motor_mask(throttle * 0.01f, tailsitter.motor_mask, plane.rudder_dt);
// in forward flight: set motor tilt servos and throttles using FW controller
if (tailsitter.vectored_forward_gain > 0) {
// thrust vectoring in fixed wing flight
float aileron = SRV_Channels::get_output_scaled(SRV_Channel::k_aileron);
float elevator = SRV_Channels::get_output_scaled(SRV_Channel::k_elevator);
tilt_left = (elevator + aileron) * tailsitter.vectored_forward_gain;
tilt_right = (elevator - aileron) * tailsitter.vectored_forward_gain;
}
SRV_Channels::set_output_scaled(SRV_Channel::k_tiltMotorLeft, tilt_left);
SRV_Channels::set_output_scaled(SRV_Channel::k_tiltMotorRight, tilt_right);
return;
}
}
// handle Copter controller
// the MultiCopter rate controller has already been run in an earlier call
// to motors_output() from quadplane.update(), unless we are in assisted flight
if (assisted_flight && tailsitter_transition_fw_complete()) {
hold_stabilize(SRV_Channels::get_output_scaled(SRV_Channel::k_throttle) * 0.01f);
motors_output(true);
if ((options & OPTION_TAILSIT_Q_ASSIST_MOTORS_ONLY) != 0) {
// only use motors for Q assist, control surfaces remain under plane control
// zero copter I terms and use plane
attitude_control->reset_rate_controller_I_terms();
// output tilt motors
if (tailsitter.vectored_hover_gain > 0) {
SRV_Channels::set_output_scaled(SRV_Channel::k_tiltMotorLeft, SRV_Channels::get_output_scaled(SRV_Channel::k_tiltMotorLeft) * tailsitter.vectored_hover_gain);
SRV_Channels::set_output_scaled(SRV_Channel::k_tiltMotorRight, SRV_Channels::get_output_scaled(SRV_Channel::k_tiltMotorRight) * tailsitter.vectored_hover_gain);
}
// skip remainder of the function that overwrites plane control surface outputs with copter
return;
}
} else {
motors_output(false);
}
// In full Q assist it is better to use cotper I and zero plane
plane.pitchController.reset_I();
plane.rollController.reset_I();
// pull in copter control outputs
SRV_Channels::set_output_scaled(SRV_Channel::k_aileron, (motors->get_yaw())*-SERVO_MAX);
SRV_Channels::set_output_scaled(SRV_Channel::k_elevator, (motors->get_pitch())*SERVO_MAX);
SRV_Channels::set_output_scaled(SRV_Channel::k_rudder, (motors->get_roll())*SERVO_MAX);
SRV_Channels::set_output_scaled(SRV_Channel::k_throttle, (motors->get_throttle()) * 100);
if (hal.util->get_soft_armed()) {
// scale surfaces for throttle
tailsitter_speed_scaling();
}
if (tailsitter.vectored_hover_gain > 0) {
// thrust vectoring VTOL modes
tilt_left = SRV_Channels::get_output_scaled(SRV_Channel::k_tiltMotorLeft);
tilt_right = SRV_Channels::get_output_scaled(SRV_Channel::k_tiltMotorRight);
/*
apply extra elevator when at high pitch errors, using a
power law. This allows the motors to point straight up for
takeoff without integrator windup
*/
float des_pitch_cd = attitude_control->get_att_target_euler_cd().y;
int32_t pitch_error_cd = (des_pitch_cd - ahrs_view->pitch_sensor) * 0.5;
float extra_pitch = constrain_float(pitch_error_cd, -SERVO_MAX, SERVO_MAX) / SERVO_MAX;
float extra_sign = extra_pitch > 0?1:-1;
float extra_elevator = 0;
if (!is_zero(extra_pitch) && in_vtol_mode()) {
extra_elevator = extra_sign * powf(fabsf(extra_pitch), tailsitter.vectored_hover_power) * SERVO_MAX;
}
tilt_left = extra_elevator + tilt_left * tailsitter.vectored_hover_gain;
tilt_right = extra_elevator + tilt_right * tailsitter.vectored_hover_gain;
if (fabsf(tilt_left) >= SERVO_MAX || fabsf(tilt_right) >= SERVO_MAX) {
// prevent integrator windup
motors->limit.roll = 1;
motors->limit.pitch = 1;
motors->limit.yaw = 1;
}
SRV_Channels::set_output_scaled(SRV_Channel::k_tiltMotorLeft, tilt_left);
SRV_Channels::set_output_scaled(SRV_Channel::k_tiltMotorRight, tilt_right);
}
if (tailsitter.input_mask_chan > 0 &&
tailsitter.input_mask > 0 &&
RC_Channels::get_radio_in(tailsitter.input_mask_chan-1) > 1700) {
// the user is learning to prop-hang
if (tailsitter.input_mask & TAILSITTER_MASK_AILERON) {
SRV_Channels::set_output_scaled(SRV_Channel::k_aileron, plane.channel_roll->get_control_in_zero_dz());
}
if (tailsitter.input_mask & TAILSITTER_MASK_ELEVATOR) {
SRV_Channels::set_output_scaled(SRV_Channel::k_elevator, plane.channel_pitch->get_control_in_zero_dz());
}
if (tailsitter.input_mask & TAILSITTER_MASK_THROTTLE) {
SRV_Channels::set_output_scaled(SRV_Channel::k_throttle, plane.get_throttle_input(true));
}
if (tailsitter.input_mask & TAILSITTER_MASK_RUDDER) {
SRV_Channels::set_output_scaled(SRV_Channel::k_rudder, plane.channel_rudder->get_control_in_zero_dz());
}
}
}
/*
return true when we have completed enough of a transition to switch to fixed wing control
*/
bool QuadPlane::tailsitter_transition_fw_complete(void)
{
if (plane.fly_inverted()) {
// transition immediately
return true;
}
int32_t roll_cd = labs(ahrs_view->roll_sensor);
if (roll_cd > 9000) {
roll_cd = 18000 - roll_cd;
}
if (labs(ahrs_view->pitch_sensor) > tailsitter.transition_angle*100 ||
roll_cd > tailsitter.transition_angle*100 ||
AP_HAL::millis() - transition_start_ms > uint32_t(transition_time_ms)) {
return true;
}
// still waiting
return false;
}
/*
return true when we have completed enough of a transition to switch to VTOL control
*/
bool QuadPlane::tailsitter_transition_vtol_complete(void) const
{
if (plane.fly_inverted()) {
// transition immediately
return true;
}
if (labs(plane.ahrs.pitch_sensor) > tailsitter.transition_angle*100 ||
labs(plane.ahrs.roll_sensor) > tailsitter.transition_angle*100 ||
AP_HAL::millis() - transition_start_ms > 2000) {
return true;
}
// still waiting
attitude_control->reset_rate_controller_I_terms();
return false;
}
// handle different tailsitter input types
void QuadPlane::tailsitter_check_input(void)
{
if (tailsitter_active() &&
(tailsitter.input_type & TAILSITTER_INPUT_PLANE)) {
// the user has asked for body frame controls when tailsitter
// is active. We switch around the control_in value for the
// channels to do this, as that ensures the value is
// consistent throughout the code
int16_t roll_in = plane.channel_roll->get_control_in();
int16_t yaw_in = plane.channel_rudder->get_control_in();
plane.channel_roll->set_control_in(yaw_in);
plane.channel_rudder->set_control_in(-roll_in);
}
}
/*
return true if we are a tailsitter transitioning to VTOL flight
*/
bool QuadPlane::in_tailsitter_vtol_transition(void) const
{
return is_tailsitter() && in_vtol_mode() && transition_state == TRANSITION_ANGLE_WAIT_VTOL;
}
/*
account for speed scaling of control surfaces in VTOL modes
*/
void QuadPlane::tailsitter_speed_scaling(void)
{
const float hover_throttle = motors->get_throttle_hover();
const float throttle = motors->get_throttle();
float spd_scaler = 1.0f;
if (tailsitter.gain_scaling_mask & TAILSITTER_GSCL_ATT_THR) {
// reduce gains when flying at high speed in Q modes:
// critical parameter: violent oscillations if too high
// sudden loss of attitude control if too low
const float min_scale = tailsitter.gain_scaling_min;
float tthr = 1.25f * hover_throttle;
// reduce control surface throws at large tilt
// angles (assuming high airspeed)
// ramp down from 1 to max_atten at tilt angles over trans_angle
// (angles here are represented by their cosines)
// Note that the cosf call will be necessary if trans_angle becomes a parameter
// but the C language spec does not guarantee that trig functions can be used
// in constant expressions, even though gcc currently allows it.
constexpr float c_trans_angle = 0.9238795; // cosf(.125f * M_PI)
// alpha = (1 - max_atten) / (c_trans_angle - cosf(radians(90)));
const float alpha = (1 - min_scale) / c_trans_angle;
const float beta = 1 - alpha * c_trans_angle;
const float c_tilt = ahrs_view->get_rotation_body_to_ned().c.z;
if (c_tilt < c_trans_angle) {
spd_scaler = constrain_float(beta + alpha * c_tilt, min_scale, 1.0f);
// reduce throttle attenuation threshold too
tthr = 0.5f * hover_throttle;
}
// if throttle is above hover thrust, apply additional attenuation
if (throttle > tthr) {
const float throttle_atten = 1 - (throttle - tthr) / (1 - tthr);
spd_scaler *= throttle_atten;
spd_scaler = constrain_float(spd_scaler, min_scale, 1.0f);
}
// limit positive and negative slew rates of applied speed scaling
constexpr float posTC = 2.0f; // seconds
constexpr float negTC = 1.0f; // seconds
const float posdelta = plane.G_Dt / posTC;
const float negdelta = plane.G_Dt / negTC;
spd_scaler = constrain_float(spd_scaler, last_spd_scaler - negdelta, last_spd_scaler + posdelta);
last_spd_scaler = spd_scaler;
}
// if gain attenuation isn't active and boost is enabled
if ((spd_scaler >= 1.0f) && (tailsitter.gain_scaling_mask & TAILSITTER_GSCL_BOOST)) {
// boost gains at low throttle
if (is_zero(throttle)) {
spd_scaler = tailsitter.throttle_scale_max;
} else {
spd_scaler = constrain_float(hover_throttle / throttle, 1.0f, tailsitter.throttle_scale_max);
}
}
const SRV_Channel::Aux_servo_function_t functions[] = {
SRV_Channel::Aux_servo_function_t::k_aileron,
SRV_Channel::Aux_servo_function_t::k_elevator,
SRV_Channel::Aux_servo_function_t::k_rudder};
for (uint8_t i=0; i<ARRAY_SIZE(functions); i++) {
int32_t v = SRV_Channels::get_output_scaled(functions[i]);
v *= spd_scaler;
v = constrain_int32(v, -SERVO_MAX, SERVO_MAX);
SRV_Channels::set_output_scaled(functions[i], v);
}
}