ardupilot/Tools/ArduTracker/navigation.pde

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: t -*-
//****************************************************************
// Function that will calculate the desired direction to fly and altitude error
//****************************************************************
void navigate()
{
// do not navigate with corrupt data
// ---------------------------------
if (gps.fix == 0)
{
gps.new_data = false;
return;
}
if(next_WP.lat == 0){
return;
}
// We only perform most nav computations if we have new gps data to work with
// --------------------------------------------------------------------------
if(gps.new_data){
gps.new_data = false;
// target_bearing is where we should be heading
// --------------------------------------------
target_bearing = get_bearing(&current_loc, &next_WP);
// nav_bearing will includes xtrac correction
// ------------------------------------------
nav_bearing = target_bearing;
// waypoint distance from plane
// ----------------------------
wp_distance = getDistance(&current_loc, &next_WP);
if (wp_distance < 0){
gcs.send_text(SEVERITY_HIGH,"<navigate> WP error - distance < 0");
//Serial.println(wp_distance,DEC);
//print_current_waypoints();
return;
}
// check if we have missed the WP
loiter_delta = (target_bearing - old_target_bearing)/100;
// reset the old value
old_target_bearing = target_bearing;
// wrap values
if (loiter_delta > 180) loiter_delta -= 360;
if (loiter_delta < -180) loiter_delta += 360;
loiter_sum += abs(loiter_delta);
calc_bearing_error();
// control mode specific updates to nav_bearing
update_navigation();
}
}
void update_navigation()
{
// wp_distance is in ACTUAL meters, not the *100 meters we get from the GPS
// ------------------------------------------------------------------------
// distance and bearing calcs only
if(control_mode == AUTO){
verify_must();
verify_may();
}else{
switch(control_mode){
case LOITER:
update_loiter();
calc_bearing_error();
break;
case RTL:
if(wp_distance <= (get(PARAM_LOITER_RADIUS)) + LOITER_RANGE) {
set_mode(LOITER);
}else{
update_crosstrack();
}
break;
}
}
}
/*
Disabled for now
void calc_distance_error()
{
//distance_estimate += (float)gps.ground_speed * .0002f * cosf(radians(bearing_error * .01f));
//distance_estimate -= DST_EST_GAIN * (float)(distance_estimate - GPS_wp_distance);
//wp_distance = max(distance_estimate,10);
}
*/
void calc_airspeed_errors()
{
if(control_mode>=AUTO && airspeed_nudge > 0) {
airspeed_error = get(PARAM_TRIM_AIRSPEED) + airspeed_nudge - airspeed;
airspeed_energy_error = (long)(((long)(get(PARAM_TRIM_AIRSPEED) + airspeed_nudge) * (long)(get(PARAM_TRIM_AIRSPEED) + airspeed_nudge)) - ((long)airspeed * (long)airspeed))/20000; //Changed 0.00005f * to / 20000 to avoid floating point calculation
} else {
airspeed_error = get(PARAM_TRIM_AIRSPEED) - airspeed;
airspeed_energy_error = (long)(((long)get(PARAM_TRIM_AIRSPEED) * (long)get(PARAM_TRIM_AIRSPEED)) - ((long)airspeed * (long)airspeed))/20000; //Changed 0.00005f * to / 20000 to avoid floating point calculation
}
}
void calc_bearing_error()
{
if(takeoff_complete == true || MAGNETOMETER == ENABLED) {
bearing_error = nav_bearing - dcm.yaw_sensor;
} else {
bearing_error = nav_bearing - gps.ground_course;
}
bearing_error = wrap_180(bearing_error);
}
void calc_altitude_error()
{
// limit climb rates
target_altitude = next_WP.alt - (long)(((float)((wp_distance -30) * offset_altitude) / (float)(wp_totalDistance - 30)));
if(prev_WP.alt > next_WP.alt){
target_altitude = constrain(target_altitude, next_WP.alt, prev_WP.alt);
}else{
target_altitude = constrain(target_altitude, prev_WP.alt, next_WP.alt);
}
/*
// Disabled for now
#if AIRSPEED_SENSOR == 1
// special thanks to Ryan Beall for this one
float pitch_angle = pitch_sensor - AOA; // pitch_angle = pitch sensor - angle of attack of your plane at level *100 (50 = .5°)
pitch_angle = constrain(pitch_angle, -2000, 2000);
float scale = sinf(radians(pitch_angle * .01));
altitude_estimate += (float)airspeed * .0002 * scale;
altitude_estimate -= ALT_EST_GAIN * (float)(altitude_estimate - current_loc.alt);
// compute altitude error for throttle control
altitude_error = target_altitude - altitude_estimate;
#else
altitude_error = target_altitude - current_loc.alt;
#endif
*/
altitude_error = target_altitude - current_loc.alt;
}
long wrap_360(long error)
{
if (error > 36000) error -= 36000;
if (error < 0) error += 36000;
return error;
}
long wrap_180(long error)
{
if (error > 18000) error -= 36000;
if (error < -18000) error += 36000;
return error;
}
void update_loiter()
{
float power;
if (wp_distance <= get(PARAM_LOITER_RADIUS)){
power = float(wp_distance) / float(get(PARAM_LOITER_RADIUS));
nav_bearing += (int)(9000.0 * (2.0 + power));
} else if (wp_distance < (get(PARAM_LOITER_RADIUS) + LOITER_RANGE)){
power = -((float)(wp_distance - get(PARAM_LOITER_RADIUS) - LOITER_RANGE) / LOITER_RANGE);
power = constrain(power, 0, 1);
nav_bearing -= power * 9000;
} else {
update_crosstrack();
}
nav_bearing = wrap_360(nav_bearing);
/* loiter_delta = (target_bearing - old_target_bearing)/100;
// reset the old value
old_target_bearing = target_bearing;
// wrap values
if (loiter_delta > 170) loiter_delta -= 360;
if (loiter_delta < -170) loiter_delta += 360;
loiter_sum += loiter_delta;
*/
}
void update_crosstrack(void)
{
// Crosstrack Error
// ----------------
if (abs(target_bearing - crosstrack_bearing) < 4500) { // If we are too far off or too close we don't do track following
crosstrack_error = sinf(radians((target_bearing - crosstrack_bearing)/100)) * wp_distance; // Meters we are off track line
nav_bearing += constrain(crosstrack_error * get(PARAM_XTRACK_GAIN), -get(PARAM_XTRACK_ANGLE), get(PARAM_XTRACK_ANGLE));
nav_bearing = wrap_360(nav_bearing);
}
}
void reset_crosstrack()
{
crosstrack_bearing = get_bearing(&current_loc, &next_WP); // Used for track following
}
long get_altitude_above_home(void)
{
// This is the altitude above the home location
// The GPS gives us altitude at Sea Level
// if you slope soar, you should see a negative number sometimes
// -------------------------------------------------------------
return current_loc.alt - home.alt;
}
long getDistance(struct Location *loc1, struct Location *loc2)
{
if(loc1->lat == 0 || loc1->lng == 0)
return -1;
if(loc2->lat == 0 || loc2->lng == 0)
return -1;
float dlat = (float)(loc2->lat - loc1->lat);
float dlong = ((float)(loc2->lng - loc1->lng)) * scaleLongDown;
return sqrtf(sq(dlat) + sq(dlong)) * .01113195f;
}
long get_alt_distance(struct Location *loc1, struct Location *loc2)
{
return abs(loc1->alt - loc2->alt);
}
long get_bearing(struct Location *loc1, struct Location *loc2)
{
long off_x = loc2->lng - loc1->lng;
long off_y = (loc2->lat - loc1->lat) * scaleLongUp;
long bearing = 9000 + atan2f(-off_y, off_x) * 5729.57795f;
if (bearing < 0) bearing += 36000;
return bearing;
}