ardupilot/ArduCopter/control_poshold.cpp

669 lines
37 KiB
C++

/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
#include "Copter.h"
#if POSHOLD_ENABLED == ENABLED
/*
* Init and run calls for PosHold flight mode
* PosHold tries to improve upon regular loiter by mixing the pilot input with the loiter controller
*/
#define POSHOLD_SPEED_0 10 // speed below which it is always safe to switch to loiter
// 400hz loop update rate
#define POSHOLD_BRAKE_TIME_ESTIMATE_MAX (600*4) // max number of cycles the brake will be applied before we switch to loiter
#define POSHOLD_BRAKE_TO_LOITER_TIMER (150*4) // Number of cycles to transition from brake mode to loiter mode. Must be lower than POSHOLD_LOITER_STAB_TIMER
#define POSHOLD_WIND_COMP_START_TIMER (150*4) // Number of cycles to start wind compensation update after loiter is engaged
#define POSHOLD_CONTROLLER_TO_PILOT_MIX_TIMER (50*4) // Set it from 100 to 200, the number of centiseconds loiter and manual commands are mixed to make a smooth transition.
#define POSHOLD_SMOOTH_RATE_FACTOR 0.0125f // filter applied to pilot's roll/pitch input as it returns to center. A lower number will cause the roll/pitch to return to zero more slowly if the brake_rate is also low.
#define POSHOLD_WIND_COMP_TIMER_10HZ 40 // counter value used to reduce wind compensation to 10hz
#define LOOP_RATE_FACTOR 4 // used to adapt PosHold params to loop_rate
#define TC_WIND_COMP 0.0025f // Time constant for poshold_update_wind_comp_estimate()
// definitions that are independent of main loop rate
#define POSHOLD_STICK_RELEASE_SMOOTH_ANGLE 1800 // max angle required (in centi-degrees) after which the smooth stick release effect is applied
#define POSHOLD_WIND_COMP_ESTIMATE_SPEED_MAX 10 // wind compensation estimates will only run when velocity is at or below this speed in cm/s
// mission state enumeration
enum poshold_rp_mode {
POSHOLD_PILOT_OVERRIDE=0, // pilot is controlling this axis (i.e. roll or pitch)
POSHOLD_BRAKE, // this axis is braking towards zero
POSHOLD_BRAKE_READY_TO_LOITER, // this axis has completed braking and is ready to enter loiter mode (both modes must be this value before moving to next stage)
POSHOLD_BRAKE_TO_LOITER, // both vehicle's axis (roll and pitch) are transitioning from braking to loiter mode (braking and loiter controls are mixed)
POSHOLD_LOITER, // both vehicle axis are holding position
POSHOLD_CONTROLLER_TO_PILOT_OVERRIDE // pilot has input controls on this axis and this axis is transitioning to pilot override (other axis will transition to brake if no pilot input)
};
static struct {
poshold_rp_mode roll_mode : 3; // roll mode: pilot override, brake or loiter
poshold_rp_mode pitch_mode : 3; // pitch mode: pilot override, brake or loiter
uint8_t braking_time_updated_roll : 1; // true once we have re-estimated the braking time. This is done once as the vehicle begins to flatten out after braking
uint8_t braking_time_updated_pitch : 1; // true once we have re-estimated the braking time. This is done once as the vehicle begins to flatten out after braking
uint8_t loiter_reset_I : 1; // true the very first time PosHold enters loiter, thereafter we trust the i terms loiter has
// pilot input related variables
float pilot_roll; // pilot requested roll angle (filtered to slow returns to zero)
float pilot_pitch; // pilot requested roll angle (filtered to slow returns to zero)
// braking related variables
float brake_gain; // gain used during conversion of vehicle's velocity to lean angle during braking (calculated from brake_rate)
int16_t brake_roll; // target roll angle during braking periods
int16_t brake_pitch; // target pitch angle during braking periods
int16_t brake_timeout_roll; // number of cycles allowed for the braking to complete, this timeout will be updated at half-braking
int16_t brake_timeout_pitch; // number of cycles allowed for the braking to complete, this timeout will be updated at half-braking
int16_t brake_angle_max_roll; // maximum lean angle achieved during braking. Used to determine when the vehicle has begun to flatten out so that we can re-estimate the braking time
int16_t brake_angle_max_pitch; // maximum lean angle achieved during braking Used to determine when the vehicle has begun to flatten out so that we can re-estimate the braking time
int16_t brake_to_loiter_timer; // cycles to mix brake and loiter controls in POSHOLD_BRAKE_TO_LOITER
// loiter related variables
int16_t controller_to_pilot_timer_roll; // cycles to mix controller and pilot controls in POSHOLD_CONTROLLER_TO_PILOT
int16_t controller_to_pilot_timer_pitch; // cycles to mix controller and pilot controls in POSHOLD_CONTROLLER_TO_PILOT
int16_t controller_final_roll; // final roll angle from controller as we exit brake or loiter mode (used for mixing with pilot input)
int16_t controller_final_pitch; // final pitch angle from controller as we exit brake or loiter mode (used for mixing with pilot input)
// wind compensation related variables
Vector2f wind_comp_ef; // wind compensation in earth frame, filtered lean angles from position controller
int16_t wind_comp_roll; // roll angle to compensate for wind
int16_t wind_comp_pitch; // pitch angle to compensate for wind
uint16_t wind_comp_start_timer; // counter to delay start of wind compensation for a short time after loiter is engaged
int8_t wind_comp_timer; // counter to reduce wind comp roll/pitch lean angle calcs to 10hz
// final output
int16_t roll; // final roll angle sent to attitude controller
int16_t pitch; // final pitch angle sent to attitude controller
} poshold;
// poshold_init - initialise PosHold controller
bool Copter::poshold_init(bool ignore_checks)
{
// fail to initialise PosHold mode if no GPS lock
if (!position_ok() && !ignore_checks) {
return false;
}
// initialize vertical speeds and acceleration
pos_control.set_speed_z(-g.pilot_velocity_z_max, g.pilot_velocity_z_max);
pos_control.set_accel_z(g.pilot_accel_z);
// initialise position and desired velocity
if (!pos_control.is_active_z()) {
pos_control.set_alt_target_to_current_alt();
pos_control.set_desired_velocity_z(inertial_nav.get_velocity_z());
}
// initialise lean angles to current attitude
poshold.pilot_roll = 0;
poshold.pilot_pitch = 0;
// compute brake_gain
poshold.brake_gain = (15.0f * (float)g.poshold_brake_rate + 95.0f) / 100.0f;
if (ap.land_complete) {
// if landed begin in loiter mode
poshold.roll_mode = POSHOLD_LOITER;
poshold.pitch_mode = POSHOLD_LOITER;
// set target to current position
// only init here as we can switch to PosHold in flight with a velocity <> 0 that will be used as _last_vel in PosControl and never updated again as we inhibit Reset_I
wp_nav.init_loiter_target();
}else{
// if not landed start in pilot override to avoid hard twitch
poshold.roll_mode = POSHOLD_PILOT_OVERRIDE;
poshold.pitch_mode = POSHOLD_PILOT_OVERRIDE;
}
// loiter's I terms should be reset the first time only
poshold.loiter_reset_I = true;
// initialise wind_comp each time PosHold is switched on
poshold.wind_comp_ef.zero();
poshold.wind_comp_roll = 0;
poshold.wind_comp_pitch = 0;
poshold.wind_comp_timer = 0;
return true;
}
// poshold_run - runs the PosHold controller
// should be called at 100hz or more
void Copter::poshold_run()
{
float target_roll, target_pitch; // pilot's roll and pitch angle inputs
float target_yaw_rate = 0; // pilot desired yaw rate in centi-degrees/sec
float target_climb_rate = 0; // pilot desired climb rate in centimeters/sec
float takeoff_climb_rate = 0.0f; // takeoff induced climb rate
float brake_to_loiter_mix; // mix of brake and loiter controls. 0 = fully brake controls, 1 = fully loiter controls
float controller_to_pilot_roll_mix; // mix of controller and pilot controls. 0 = fully last controller controls, 1 = fully pilot controls
float controller_to_pilot_pitch_mix; // mix of controller and pilot controls. 0 = fully last controller controls, 1 = fully pilot controls
float vel_fw, vel_right; // vehicle's current velocity in body-frame forward and right directions
const Vector3f& vel = inertial_nav.get_velocity();
// initialize vertical speeds and acceleration
pos_control.set_speed_z(-g.pilot_velocity_z_max, g.pilot_velocity_z_max);
pos_control.set_accel_z(g.pilot_accel_z);
// if not auto armed or motor interlock not enabled set throttle to zero and exit immediately
if (!motors.armed() || !ap.auto_armed || !motors.get_interlock()) {
motors.set_desired_spool_state(AP_Motors::DESIRED_SPIN_WHEN_ARMED);
wp_nav.init_loiter_target();
attitude_control.set_throttle_out_unstabilized(0,true,g.throttle_filt);
pos_control.relax_alt_hold_controllers(0.0f);
return;
}
// process pilot inputs
if (!failsafe.radio) {
// apply SIMPLE mode transform to pilot inputs
update_simple_mode();
// get pilot's desired yaw rate
target_yaw_rate = get_pilot_desired_yaw_rate(channel_yaw->get_control_in());
// get pilot desired climb rate (for alt-hold mode and take-off)
target_climb_rate = get_pilot_desired_climb_rate(channel_throttle->get_control_in());
target_climb_rate = constrain_float(target_climb_rate, -g.pilot_velocity_z_max, g.pilot_velocity_z_max);
// get takeoff adjusted pilot and takeoff climb rates
takeoff_get_climb_rates(target_climb_rate, takeoff_climb_rate);
// check for take-off
if (ap.land_complete && (takeoff_state.running || target_climb_rate > 0.0f)) {
if (!takeoff_state.running) {
takeoff_timer_start(constrain_float(g.pilot_takeoff_alt,0.0f,1000.0f));
}
// indicate we are taking off
set_land_complete(false);
// clear i term when we're taking off
set_throttle_takeoff();
}
}
// relax loiter target if we might be landed
if (ap.land_complete_maybe) {
wp_nav.loiter_soften_for_landing();
}
// if landed initialise loiter targets, set throttle to zero and exit
if (ap.land_complete) {
// set motors to spin-when-armed if throttle below deadzone, otherwise full range (but motors will only spin at min throttle)
if (target_climb_rate < 0.0f) {
motors.set_desired_spool_state(AP_Motors::DESIRED_SPIN_WHEN_ARMED);
} else {
motors.set_desired_spool_state(AP_Motors::DESIRED_THROTTLE_UNLIMITED);
}
wp_nav.init_loiter_target();
attitude_control.reset_rate_controller_I_terms();
attitude_control.set_yaw_target_to_current_heading();
attitude_control.input_euler_angle_roll_pitch_euler_rate_yaw(0, 0, 0, get_smoothing_gain());
pos_control.relax_alt_hold_controllers(0.0f); // forces throttle output to go to zero
pos_control.update_z_controller();
return;
}else{
// convert pilot input to lean angles
get_pilot_desired_lean_angles(channel_roll->get_control_in(), channel_pitch->get_control_in(), target_roll, target_pitch, aparm.angle_max);
// convert inertial nav earth-frame velocities to body-frame
// To-Do: move this to AP_Math (or perhaps we already have a function to do this)
vel_fw = vel.x*ahrs.cos_yaw() + vel.y*ahrs.sin_yaw();
vel_right = -vel.x*ahrs.sin_yaw() + vel.y*ahrs.cos_yaw();
// If not in LOITER, retrieve latest wind compensation lean angles related to current yaw
if (poshold.roll_mode != POSHOLD_LOITER || poshold.pitch_mode != POSHOLD_LOITER)
poshold_get_wind_comp_lean_angles(poshold.wind_comp_roll, poshold.wind_comp_pitch);
// Roll state machine
// Each state (aka mode) is responsible for:
// 1. dealing with pilot input
// 2. calculating the final roll output to the attitude controller
// 3. checking if the state (aka mode) should be changed and if 'yes' perform any required initialisation for the new state
switch (poshold.roll_mode) {
case POSHOLD_PILOT_OVERRIDE:
// update pilot desired roll angle using latest radio input
// this filters the input so that it returns to zero no faster than the brake-rate
poshold_update_pilot_lean_angle(poshold.pilot_roll, target_roll);
// switch to BRAKE mode for next iteration if no pilot input
if (is_zero(target_roll) && (fabsf(poshold.pilot_roll) < 2 * g.poshold_brake_rate)) {
// initialise BRAKE mode
poshold.roll_mode = POSHOLD_BRAKE; // Set brake roll mode
poshold.brake_roll = 0; // initialise braking angle to zero
poshold.brake_angle_max_roll = 0; // reset brake_angle_max so we can detect when vehicle begins to flatten out during braking
poshold.brake_timeout_roll = POSHOLD_BRAKE_TIME_ESTIMATE_MAX; // number of cycles the brake will be applied, updated during braking mode.
poshold.braking_time_updated_roll = false; // flag the braking time can be re-estimated
}
// final lean angle should be pilot input plus wind compensation
poshold.roll = poshold.pilot_roll + poshold.wind_comp_roll;
break;
case POSHOLD_BRAKE:
case POSHOLD_BRAKE_READY_TO_LOITER:
// calculate brake_roll angle to counter-act velocity
poshold_update_brake_angle_from_velocity(poshold.brake_roll, vel_right);
// update braking time estimate
if (!poshold.braking_time_updated_roll) {
// check if brake angle is increasing
if (abs(poshold.brake_roll) >= poshold.brake_angle_max_roll) {
poshold.brake_angle_max_roll = abs(poshold.brake_roll);
} else {
// braking angle has started decreasing so re-estimate braking time
poshold.brake_timeout_roll = 1+(uint16_t)(LOOP_RATE_FACTOR*15L*(int32_t)(abs(poshold.brake_roll))/(10L*(int32_t)g.poshold_brake_rate)); // the 1.2 (12/10) factor has to be tuned in flight, here it means 120% of the "normal" time.
poshold.braking_time_updated_roll = true;
}
}
// if velocity is very low reduce braking time to 0.5seconds
if ((fabsf(vel_right) <= POSHOLD_SPEED_0) && (poshold.brake_timeout_roll > 50*LOOP_RATE_FACTOR)) {
poshold.brake_timeout_roll = 50*LOOP_RATE_FACTOR;
}
// reduce braking timer
if (poshold.brake_timeout_roll > 0) {
poshold.brake_timeout_roll--;
} else {
// indicate that we are ready to move to Loiter.
// Loiter will only actually be engaged once both roll_mode and pitch_mode are changed to POSHOLD_BRAKE_READY_TO_LOITER
// logic for engaging loiter is handled below the roll and pitch mode switch statements
poshold.roll_mode = POSHOLD_BRAKE_READY_TO_LOITER;
}
// final lean angle is braking angle + wind compensation angle
poshold.roll = poshold.brake_roll + poshold.wind_comp_roll;
// check for pilot input
if (!is_zero(target_roll)) {
// init transition to pilot override
poshold_roll_controller_to_pilot_override();
}
break;
case POSHOLD_BRAKE_TO_LOITER:
case POSHOLD_LOITER:
// these modes are combined roll-pitch modes and are handled below
break;
case POSHOLD_CONTROLLER_TO_PILOT_OVERRIDE:
// update pilot desired roll angle using latest radio input
// this filters the input so that it returns to zero no faster than the brake-rate
poshold_update_pilot_lean_angle(poshold.pilot_roll, target_roll);
// count-down loiter to pilot timer
if (poshold.controller_to_pilot_timer_roll > 0) {
poshold.controller_to_pilot_timer_roll--;
} else {
// when timer runs out switch to full pilot override for next iteration
poshold.roll_mode = POSHOLD_PILOT_OVERRIDE;
}
// calculate controller_to_pilot mix ratio
controller_to_pilot_roll_mix = (float)poshold.controller_to_pilot_timer_roll / (float)POSHOLD_CONTROLLER_TO_PILOT_MIX_TIMER;
// mix final loiter lean angle and pilot desired lean angles
poshold.roll = poshold_mix_controls(controller_to_pilot_roll_mix, poshold.controller_final_roll, poshold.pilot_roll + poshold.wind_comp_roll);
break;
}
// Pitch state machine
// Each state (aka mode) is responsible for:
// 1. dealing with pilot input
// 2. calculating the final pitch output to the attitude contpitcher
// 3. checking if the state (aka mode) should be changed and if 'yes' perform any required initialisation for the new state
switch (poshold.pitch_mode) {
case POSHOLD_PILOT_OVERRIDE:
// update pilot desired pitch angle using latest radio input
// this filters the input so that it returns to zero no faster than the brake-rate
poshold_update_pilot_lean_angle(poshold.pilot_pitch, target_pitch);
// switch to BRAKE mode for next iteration if no pilot input
if (is_zero(target_pitch) && (fabsf(poshold.pilot_pitch) < 2 * g.poshold_brake_rate)) {
// initialise BRAKE mode
poshold.pitch_mode = POSHOLD_BRAKE; // set brake pitch mode
poshold.brake_pitch = 0; // initialise braking angle to zero
poshold.brake_angle_max_pitch = 0; // reset brake_angle_max so we can detect when vehicle begins to flatten out during braking
poshold.brake_timeout_pitch = POSHOLD_BRAKE_TIME_ESTIMATE_MAX; // number of cycles the brake will be applied, updated during braking mode.
poshold.braking_time_updated_pitch = false; // flag the braking time can be re-estimated
}
// final lean angle should be pilot input plus wind compensation
poshold.pitch = poshold.pilot_pitch + poshold.wind_comp_pitch;
break;
case POSHOLD_BRAKE:
case POSHOLD_BRAKE_READY_TO_LOITER:
// calculate brake_pitch angle to counter-act velocity
poshold_update_brake_angle_from_velocity(poshold.brake_pitch, -vel_fw);
// update braking time estimate
if (!poshold.braking_time_updated_pitch) {
// check if brake angle is increasing
if (abs(poshold.brake_pitch) >= poshold.brake_angle_max_pitch) {
poshold.brake_angle_max_pitch = abs(poshold.brake_pitch);
} else {
// braking angle has started decreasing so re-estimate braking time
poshold.brake_timeout_pitch = 1+(uint16_t)(LOOP_RATE_FACTOR*15L*(int32_t)(abs(poshold.brake_pitch))/(10L*(int32_t)g.poshold_brake_rate)); // the 1.2 (12/10) factor has to be tuned in flight, here it means 120% of the "normal" time.
poshold.braking_time_updated_pitch = true;
}
}
// if velocity is very low reduce braking time to 0.5seconds
if ((fabsf(vel_fw) <= POSHOLD_SPEED_0) && (poshold.brake_timeout_pitch > 50*LOOP_RATE_FACTOR)) {
poshold.brake_timeout_pitch = 50*LOOP_RATE_FACTOR;
}
// reduce braking timer
if (poshold.brake_timeout_pitch > 0) {
poshold.brake_timeout_pitch--;
} else {
// indicate that we are ready to move to Loiter.
// Loiter will only actually be engaged once both pitch_mode and pitch_mode are changed to POSHOLD_BRAKE_READY_TO_LOITER
// logic for engaging loiter is handled below the pitch and pitch mode switch statements
poshold.pitch_mode = POSHOLD_BRAKE_READY_TO_LOITER;
}
// final lean angle is braking angle + wind compensation angle
poshold.pitch = poshold.brake_pitch + poshold.wind_comp_pitch;
// check for pilot input
if (!is_zero(target_pitch)) {
// init transition to pilot override
poshold_pitch_controller_to_pilot_override();
}
break;
case POSHOLD_BRAKE_TO_LOITER:
case POSHOLD_LOITER:
// these modes are combined pitch-pitch modes and are handled below
break;
case POSHOLD_CONTROLLER_TO_PILOT_OVERRIDE:
// update pilot desired pitch angle using latest radio input
// this filters the input so that it returns to zero no faster than the brake-rate
poshold_update_pilot_lean_angle(poshold.pilot_pitch, target_pitch);
// count-down loiter to pilot timer
if (poshold.controller_to_pilot_timer_pitch > 0) {
poshold.controller_to_pilot_timer_pitch--;
} else {
// when timer runs out switch to full pilot override for next iteration
poshold.pitch_mode = POSHOLD_PILOT_OVERRIDE;
}
// calculate controller_to_pilot mix ratio
controller_to_pilot_pitch_mix = (float)poshold.controller_to_pilot_timer_pitch / (float)POSHOLD_CONTROLLER_TO_PILOT_MIX_TIMER;
// mix final loiter lean angle and pilot desired lean angles
poshold.pitch = poshold_mix_controls(controller_to_pilot_pitch_mix, poshold.controller_final_pitch, poshold.pilot_pitch + poshold.wind_comp_pitch);
break;
}
// set motors to full range
motors.set_desired_spool_state(AP_Motors::DESIRED_THROTTLE_UNLIMITED);
//
// Shared roll & pitch states (POSHOLD_BRAKE_TO_LOITER and POSHOLD_LOITER)
//
// switch into LOITER mode when both roll and pitch are ready
if (poshold.roll_mode == POSHOLD_BRAKE_READY_TO_LOITER && poshold.pitch_mode == POSHOLD_BRAKE_READY_TO_LOITER) {
poshold.roll_mode = POSHOLD_BRAKE_TO_LOITER;
poshold.pitch_mode = POSHOLD_BRAKE_TO_LOITER;
poshold.brake_to_loiter_timer = POSHOLD_BRAKE_TO_LOITER_TIMER;
// init loiter controller
wp_nav.init_loiter_target(inertial_nav.get_position(), poshold.loiter_reset_I); // (false) to avoid I_term reset. In original code, velocity(0,0,0) was used instead of current velocity: wp_nav.init_loiter_target(inertial_nav.get_position(), Vector3f(0,0,0));
// at this stage, we are going to run update_loiter that will reset I_term once. From now, we ensure next time that we will enter loiter and update it, I_term won't be reset anymore
poshold.loiter_reset_I = false;
// set delay to start of wind compensation estimate updates
poshold.wind_comp_start_timer = POSHOLD_WIND_COMP_START_TIMER;
}
// roll-mode is used as the combined roll+pitch mode when in BRAKE_TO_LOITER or LOITER modes
if (poshold.roll_mode == POSHOLD_BRAKE_TO_LOITER || poshold.roll_mode == POSHOLD_LOITER) {
// force pitch mode to be same as roll_mode just to keep it consistent (it's not actually used in these states)
poshold.pitch_mode = poshold.roll_mode;
// handle combined roll+pitch mode
switch (poshold.roll_mode) {
case POSHOLD_BRAKE_TO_LOITER:
// reduce brake_to_loiter timer
if (poshold.brake_to_loiter_timer > 0) {
poshold.brake_to_loiter_timer--;
} else {
// progress to full loiter on next iteration
poshold.roll_mode = POSHOLD_LOITER;
poshold.pitch_mode = POSHOLD_LOITER;
}
// calculate percentage mix of loiter and brake control
brake_to_loiter_mix = (float)poshold.brake_to_loiter_timer / (float)POSHOLD_BRAKE_TO_LOITER_TIMER;
// calculate brake_roll and pitch angles to counter-act velocity
poshold_update_brake_angle_from_velocity(poshold.brake_roll, vel_right);
poshold_update_brake_angle_from_velocity(poshold.brake_pitch, -vel_fw);
// run loiter controller
wp_nav.update_loiter(ekfGndSpdLimit, ekfNavVelGainScaler);
// calculate final roll and pitch output by mixing loiter and brake controls
poshold.roll = poshold_mix_controls(brake_to_loiter_mix, poshold.brake_roll + poshold.wind_comp_roll, wp_nav.get_roll());
poshold.pitch = poshold_mix_controls(brake_to_loiter_mix, poshold.brake_pitch + poshold.wind_comp_pitch, wp_nav.get_pitch());
// check for pilot input
if (!is_zero(target_roll) || !is_zero(target_pitch)) {
// if roll input switch to pilot override for roll
if (!is_zero(target_roll)) {
// init transition to pilot override
poshold_roll_controller_to_pilot_override();
// switch pitch-mode to brake (but ready to go back to loiter anytime)
// no need to reset poshold.brake_pitch here as wind comp has not been updated since last brake_pitch computation
poshold.pitch_mode = POSHOLD_BRAKE_READY_TO_LOITER;
}
// if pitch input switch to pilot override for pitch
if (!is_zero(target_pitch)) {
// init transition to pilot override
poshold_pitch_controller_to_pilot_override();
if (is_zero(target_roll)) {
// switch roll-mode to brake (but ready to go back to loiter anytime)
// no need to reset poshold.brake_roll here as wind comp has not been updated since last brake_roll computation
poshold.roll_mode = POSHOLD_BRAKE_READY_TO_LOITER;
}
}
}
break;
case POSHOLD_LOITER:
// run loiter controller
wp_nav.update_loiter(ekfGndSpdLimit, ekfNavVelGainScaler);
// set roll angle based on loiter controller outputs
poshold.roll = wp_nav.get_roll();
poshold.pitch = wp_nav.get_pitch();
// update wind compensation estimate
poshold_update_wind_comp_estimate();
// check for pilot input
if (!is_zero(target_roll) || !is_zero(target_pitch)) {
// if roll input switch to pilot override for roll
if (!is_zero(target_roll)) {
// init transition to pilot override
poshold_roll_controller_to_pilot_override();
// switch pitch-mode to brake (but ready to go back to loiter anytime)
poshold.pitch_mode = POSHOLD_BRAKE_READY_TO_LOITER;
// reset brake_pitch because wind_comp is now different and should give the compensation of the whole previous loiter angle
poshold.brake_pitch = 0;
}
// if pitch input switch to pilot override for pitch
if (!is_zero(target_pitch)) {
// init transition to pilot override
poshold_pitch_controller_to_pilot_override();
// if roll not overriden switch roll-mode to brake (but be ready to go back to loiter any time)
if (is_zero(target_roll)) {
poshold.roll_mode = POSHOLD_BRAKE_READY_TO_LOITER;
poshold.brake_roll = 0;
}
}
}
break;
default:
// do nothing for uncombined roll and pitch modes
break;
}
}
// constrain target pitch/roll angles
poshold.roll = constrain_int16(poshold.roll, -aparm.angle_max, aparm.angle_max);
poshold.pitch = constrain_int16(poshold.pitch, -aparm.angle_max, aparm.angle_max);
// update attitude controller targets
attitude_control.input_euler_angle_roll_pitch_euler_rate_yaw(poshold.roll, poshold.pitch, target_yaw_rate, get_smoothing_gain());
// adjust climb rate using rangefinder
if (rangefinder_alt_ok()) {
// if rangefinder is ok, use surface tracking
target_climb_rate = get_surface_tracking_climb_rate(target_climb_rate, pos_control.get_alt_target(), G_Dt);
}
// update altitude target and call position controller
pos_control.set_alt_target_from_climb_rate_ff(target_climb_rate, G_Dt, false);
pos_control.add_takeoff_climb_rate(takeoff_climb_rate, G_Dt);
pos_control.update_z_controller();
}
}
// poshold_update_pilot_lean_angle - update the pilot's filtered lean angle with the latest raw input received
void Copter::poshold_update_pilot_lean_angle(float &lean_angle_filtered, float &lean_angle_raw)
{
// if raw input is large or reversing the vehicle's lean angle immediately set the fitlered angle to the new raw angle
if ((lean_angle_filtered > 0 && lean_angle_raw < 0) || (lean_angle_filtered < 0 && lean_angle_raw > 0) || (fabsf(lean_angle_raw) > POSHOLD_STICK_RELEASE_SMOOTH_ANGLE)) {
lean_angle_filtered = lean_angle_raw;
} else {
// lean_angle_raw must be pulling lean_angle_filtered towards zero, smooth the decrease
if (lean_angle_filtered > 0) {
// reduce the filtered lean angle at 5% or the brake rate (whichever is faster).
lean_angle_filtered -= MAX((float)lean_angle_filtered * POSHOLD_SMOOTH_RATE_FACTOR, MAX(1, g.poshold_brake_rate/LOOP_RATE_FACTOR));
// do not let the filtered angle fall below the pilot's input lean angle.
// the above line pulls the filtered angle down and the below line acts as a catch
lean_angle_filtered = MAX(lean_angle_filtered, lean_angle_raw);
}else{
lean_angle_filtered += MAX(-(float)lean_angle_filtered * POSHOLD_SMOOTH_RATE_FACTOR, MAX(1, g.poshold_brake_rate/LOOP_RATE_FACTOR));
lean_angle_filtered = MIN(lean_angle_filtered, lean_angle_raw);
}
}
}
// poshold_mix_controls - mixes two controls based on the mix_ratio
// mix_ratio of 1 = use first_control completely, 0 = use second_control completely, 0.5 = mix evenly
int16_t Copter::poshold_mix_controls(float mix_ratio, int16_t first_control, int16_t second_control)
{
mix_ratio = constrain_float(mix_ratio, 0.0f, 1.0f);
return (int16_t)((mix_ratio * first_control) + ((1.0f-mix_ratio)*second_control));
}
// poshold_update_brake_angle_from_velocity - updates the brake_angle based on the vehicle's velocity and brake_gain
// brake_angle is slewed with the wpnav.poshold_brake_rate and constrained by the wpnav.poshold_braking_angle_max
// velocity is assumed to be in the same direction as lean angle so for pitch you should provide the velocity backwards (i.e. -ve forward velocity)
void Copter::poshold_update_brake_angle_from_velocity(int16_t &brake_angle, float velocity)
{
float lean_angle;
int16_t brake_rate = g.poshold_brake_rate;
brake_rate /= 4;
if (brake_rate <= 0) {
brake_rate = 1;
}
// calculate velocity-only based lean angle
if (velocity >= 0) {
lean_angle = -poshold.brake_gain * velocity * (1.0f+500.0f/(velocity+60.0f));
} else {
lean_angle = -poshold.brake_gain * velocity * (1.0f+500.0f/(-velocity+60.0f));
}
// do not let lean_angle be too far from brake_angle
brake_angle = constrain_int16((int16_t)lean_angle, brake_angle - brake_rate, brake_angle + brake_rate);
// constrain final brake_angle
brake_angle = constrain_int16(brake_angle, -g.poshold_brake_angle_max, g.poshold_brake_angle_max);
}
// poshold_update_wind_comp_estimate - updates wind compensation estimate
// should be called at the maximum loop rate when loiter is engaged
void Copter::poshold_update_wind_comp_estimate()
{
// check wind estimate start has not been delayed
if (poshold.wind_comp_start_timer > 0) {
poshold.wind_comp_start_timer--;
return;
}
// check horizontal velocity is low
if (inertial_nav.get_velocity_xy() > POSHOLD_WIND_COMP_ESTIMATE_SPEED_MAX) {
return;
}
// get position controller accel target
// To-Do: clean this up by using accessor in loiter controller (or move entire PosHold controller to a library shared with loiter)
const Vector3f& accel_target = pos_control.get_accel_target();
// update wind compensation in earth-frame lean angles
if (is_zero(poshold.wind_comp_ef.x)) {
// if wind compensation has not been initialised set it immediately to the pos controller's desired accel in north direction
poshold.wind_comp_ef.x = accel_target.x;
} else {
// low pass filter the position controller's lean angle output
poshold.wind_comp_ef.x = (1.0f-TC_WIND_COMP)*poshold.wind_comp_ef.x + TC_WIND_COMP*accel_target.x;
}
if (is_zero(poshold.wind_comp_ef.y)) {
// if wind compensation has not been initialised set it immediately to the pos controller's desired accel in north direction
poshold.wind_comp_ef.y = accel_target.y;
} else {
// low pass filter the position controller's lean angle output
poshold.wind_comp_ef.y = (1.0f-TC_WIND_COMP)*poshold.wind_comp_ef.y + TC_WIND_COMP*accel_target.y;
}
}
// poshold_get_wind_comp_lean_angles - retrieve wind compensation angles in body frame roll and pitch angles
// should be called at the maximum loop rate
void Copter::poshold_get_wind_comp_lean_angles(int16_t &roll_angle, int16_t &pitch_angle)
{
// reduce rate to 10hz
poshold.wind_comp_timer++;
if (poshold.wind_comp_timer < POSHOLD_WIND_COMP_TIMER_10HZ) {
return;
}
poshold.wind_comp_timer = 0;
// convert earth frame desired accelerations to body frame roll and pitch lean angles
roll_angle = atanf((-poshold.wind_comp_ef.x*ahrs.sin_yaw() + poshold.wind_comp_ef.y*ahrs.cos_yaw())/981)*(18000/M_PI);
pitch_angle = atanf(-(poshold.wind_comp_ef.x*ahrs.cos_yaw() + poshold.wind_comp_ef.y*ahrs.sin_yaw())/981)*(18000/M_PI);
}
// poshold_roll_controller_to_pilot_override - initialises transition from a controller submode (brake or loiter) to a pilot override on roll axis
void Copter::poshold_roll_controller_to_pilot_override()
{
poshold.roll_mode = POSHOLD_CONTROLLER_TO_PILOT_OVERRIDE;
poshold.controller_to_pilot_timer_roll = POSHOLD_CONTROLLER_TO_PILOT_MIX_TIMER;
// initialise pilot_roll to 0, wind_comp will be updated to compensate and poshold_update_pilot_lean_angle function shall not smooth this transition at next iteration. so 0 is the right value
poshold.pilot_roll = 0;
// store final controller output for mixing with pilot input
poshold.controller_final_roll = poshold.roll;
}
// poshold_pitch_controller_to_pilot_override - initialises transition from a controller submode (brake or loiter) to a pilot override on roll axis
void Copter::poshold_pitch_controller_to_pilot_override()
{
poshold.pitch_mode = POSHOLD_CONTROLLER_TO_PILOT_OVERRIDE;
poshold.controller_to_pilot_timer_pitch = POSHOLD_CONTROLLER_TO_PILOT_MIX_TIMER;
// initialise pilot_pitch to 0, wind_comp will be updated to compensate and poshold_update_pilot_lean_angle function shall not smooth this transition at next iteration. so 0 is the right value
poshold.pilot_pitch = 0;
// store final loiter outputs for mixing with pilot input
poshold.controller_final_pitch = poshold.pitch;
}
#endif // POSHOLD_ENABLED == ENABLED