ardupilot/ArduPlane/navigation.pde

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
// set the nav_controller pointer to the right controller
static void set_nav_controller(void)
{
switch ((AP_Navigation::ControllerType)g.nav_controller.get()) {
case AP_Navigation::CONTROLLER_L1:
nav_controller = &L1_controller;
break;
}
}
/*
reset the total loiter angle
*/
static void loiter_angle_reset(void)
{
loiter.sum_cd = 0;
loiter.total_cd = 0;
}
/*
update the total angle we have covered in a loiter. Used to support
commands to do N circles of loiter
*/
static void loiter_angle_update(void)
{
int32_t target_bearing_cd = nav_controller->target_bearing_cd();
int32_t loiter_delta_cd;
if (loiter.sum_cd == 0) {
// use 1 cd for initial delta
loiter_delta_cd = 1;
} else {
loiter_delta_cd = target_bearing_cd - loiter.old_target_bearing_cd;
}
loiter.old_target_bearing_cd = target_bearing_cd;
loiter_delta_cd = wrap_180_cd(loiter_delta_cd);
loiter.sum_cd += loiter_delta_cd;
}
//****************************************************************
// Function that will calculate the desired direction to fly and distance
//****************************************************************
static void navigate()
{
// allow change of nav controller mid-flight
set_nav_controller();
// do not navigate with corrupt data
// ---------------------------------
if (!have_position) {
return;
}
if (next_WP_loc.lat == 0) {
return;
}
// waypoint distance from plane
// ----------------------------
wp_distance = get_distance(current_loc, next_WP_loc);
if (wp_distance < 0) {
gcs_send_text_P(SEVERITY_HIGH,PSTR("WP error - distance < 0"));
return;
}
// update total loiter angle
loiter_angle_update();
// control mode specific updates to navigation demands
// ---------------------------------------------------
update_navigation();
}
static void calc_airspeed_errors()
{
float aspeed_cm = airspeed.get_airspeed_cm();
// Normal airspeed target
target_airspeed_cm = g.airspeed_cruise_cm;
// FBW_B airspeed target
if (control_mode == FLY_BY_WIRE_B ||
control_mode == CRUISE) {
target_airspeed_cm = ((int32_t)(aparm.airspeed_max -
aparm.airspeed_min) *
channel_throttle->control_in) +
((int32_t)aparm.airspeed_min * 100);
}
// Set target to current airspeed + ground speed undershoot,
// but only when this is faster than the target airspeed commanded
// above.
if (control_mode >= FLY_BY_WIRE_B && (g.min_gndspeed_cm > 0)) {
int32_t min_gnd_target_airspeed = aspeed_cm + groundspeed_undershoot;
if (min_gnd_target_airspeed > target_airspeed_cm)
target_airspeed_cm = min_gnd_target_airspeed;
}
// Bump up the target airspeed based on throttle nudging
if (control_mode >= AUTO && airspeed_nudge_cm > 0) {
target_airspeed_cm += airspeed_nudge_cm;
}
// Apply airspeed limit
if (target_airspeed_cm > (aparm.airspeed_max * 100))
target_airspeed_cm = (aparm.airspeed_max * 100);
// use the TECS view of the target airspeed for reporting, to take
// account of the landing speed
airspeed_error_cm = SpdHgt_Controller->get_target_airspeed()*100 - aspeed_cm;
}
static void calc_gndspeed_undershoot()
{
// Use the component of ground speed in the forward direction
// This prevents flyaway if wind takes plane backwards
if (g_gps && g_gps->status() >= GPS::GPS_OK_FIX_2D) {
Vector2f gndVel = ahrs.groundspeed_vector();
const Matrix3f &rotMat = ahrs.get_dcm_matrix();
Vector2f yawVect = Vector2f(rotMat.a.x,rotMat.b.x);
yawVect.normalize();
float gndSpdFwd = yawVect * gndVel;
groundspeed_undershoot = (g.min_gndspeed_cm > 0) ? (g.min_gndspeed_cm - gndSpdFwd*100) : 0;
}
}
static void calc_altitude_error()
{
if (control_mode == FLY_BY_WIRE_B ||
control_mode == CRUISE) {
return;
}
if (nav_controller->reached_loiter_target()) {
// once we reach a loiter target then lock to the final
// altitude target
target_altitude_cm = next_WP_loc.alt;
} else if (offset_altitude_cm != 0) {
// control climb/descent rate
target_altitude_cm = next_WP_loc.alt - (offset_altitude_cm*((float)(wp_distance-30) / (float)(wp_totalDistance-30)));
// stay within the range of the start and end locations in altitude
if (prev_WP_loc.alt > next_WP_loc.alt) {
target_altitude_cm = constrain_int32(target_altitude_cm, next_WP_loc.alt, prev_WP_loc.alt);
} else {
target_altitude_cm = constrain_int32(target_altitude_cm, prev_WP_loc.alt, next_WP_loc.alt);
}
} else if (mission.get_current_do_cmd().id != MAV_CMD_CONDITION_CHANGE_ALT) {
target_altitude_cm = next_WP_loc.alt;
}
altitude_error_cm = target_altitude_cm - adjusted_altitude_cm();
}
static void update_loiter()
{
nav_controller->update_loiter(next_WP_loc, abs(g.loiter_radius), loiter.direction);
}
/*
handle CRUISE mode, locking heading to GPS course when we have
sufficient ground speed, and no aileron or rudder input
*/
static void update_cruise()
{
if (!cruise_state.locked_heading &&
channel_roll->control_in == 0 &&
channel_rudder->control_in == 0 &&
g_gps && g_gps->status() >= GPS::GPS_OK_FIX_2D &&
g_gps->ground_speed_cm >= 300 &&
cruise_state.lock_timer_ms == 0) {
// user wants to lock the heading - start the timer
cruise_state.lock_timer_ms = hal.scheduler->millis();
}
if (cruise_state.lock_timer_ms != 0 &&
(hal.scheduler->millis() - cruise_state.lock_timer_ms) > 500) {
// lock the heading after 0.5 seconds of zero heading input
// from user
cruise_state.locked_heading = true;
cruise_state.lock_timer_ms = 0;
cruise_state.locked_heading_cd = g_gps->ground_course_cd;
prev_WP_loc = current_loc;
}
if (cruise_state.locked_heading) {
next_WP_loc = prev_WP_loc;
// always look 1km ahead
location_update(next_WP_loc,
cruise_state.locked_heading_cd*0.01f,
get_distance(prev_WP_loc, current_loc) + 1000);
nav_controller->update_waypoint(prev_WP_loc, next_WP_loc);
}
}
/*
handle speed and height control in FBWB or CRUISE mode.
In this mode the elevator is used to change target altitude. The
throttle is used to change target airspeed or throttle
*/
static void update_fbwb_speed_height(void)
{
static float last_elevator_input;
float elevator_input;
elevator_input = channel_pitch->control_in / 4500.0f;
if (g.flybywire_elev_reverse) {
elevator_input = -elevator_input;
}
target_altitude_cm += g.flybywire_climb_rate * elevator_input * delta_us_fast_loop * 0.0001f;
if (elevator_input == 0.0f && last_elevator_input != 0.0f) {
// the user has just released the elevator, lock in
// the current altitude
target_altitude_cm = current_loc.alt;
}
// check for FBWB altitude limit
if (g.FBWB_min_altitude_cm != 0 && target_altitude_cm < home.alt + g.FBWB_min_altitude_cm) {
target_altitude_cm = home.alt + g.FBWB_min_altitude_cm;
}
altitude_error_cm = target_altitude_cm - adjusted_altitude_cm();
last_elevator_input = elevator_input;
calc_throttle();
calc_nav_pitch();
}
static void setup_glide_slope(void)
{
// establish the distance we are travelling to the next waypoint,
// for calculating out rate of change of altitude
wp_totalDistance = get_distance(current_loc, next_WP_loc);
wp_distance = wp_totalDistance;
/*
work out if we will gradually change altitude, or try to get to
the new altitude as quickly as possible.
*/
switch (control_mode) {
case RTL:
case GUIDED:
/* glide down slowly if above target altitude, but ascend more
rapidly if below it. See
https://github.com/diydrones/ardupilot/issues/39
*/
if (current_loc.alt > next_WP_loc.alt) {
offset_altitude_cm = next_WP_loc.alt - current_loc.alt;
} else {
offset_altitude_cm = 0;
}
break;
case AUTO:
// we only do glide slide handling in AUTO when above 40m or
// when descending. The 40 meter threshold is arbitrary, and
// is basically to prevent situations where we try to slowly
// gain height at low altitudes, potentially hitting
// obstacles.
if (relative_altitude() > 40 || next_WP_loc.alt < prev_WP_loc.alt) {
offset_altitude_cm = next_WP_loc.alt - prev_WP_loc.alt;
} else {
offset_altitude_cm = 0;
}
break;
default:
offset_altitude_cm = 0;
break;
}
}
/*
return relative altitude in meters (relative to home)
*/
static float relative_altitude(void)
{
return (current_loc.alt - home.alt) * 0.01f;
}
/*
return relative altitude in centimeters, absolute value
*/
static int32_t relative_altitude_abs_cm(void)
{
return labs(current_loc.alt - home.alt);
}