ardupilot/ArduPlane/navigation.pde

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
//****************************************************************
// Function that will calculate the desired direction to fly and distance
//****************************************************************
static void navigate()
{
// do not navigate with corrupt data
// ---------------------------------
if (g_gps->fix == 0)
{
g_gps->new_data = false;
return;
}
if(next_WP.lat == 0){
return;
}
// waypoint distance from plane
// ----------------------------
wp_distance = get_distance(&current_loc, &next_WP);
if (wp_distance < 0){
gcs_send_text_P(SEVERITY_HIGH,PSTR("<navigate> WP error - distance < 0"));
//Serial.println(wp_distance,DEC);
return;
}
// 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;
// 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);
// control mode specific updates to nav_bearing
// --------------------------------------------
update_navigation();
}
#if 0
// Disabled for now
void calc_distance_error()
{
distance_estimate += (float)g_gps->ground_speed * .0002 * cos(radians(bearing_error * .01));
distance_estimate -= DST_EST_GAIN * (float)(distance_estimate - GPS_wp_distance);
wp_distance = max(distance_estimate,10);
}
#endif
static void calc_airspeed_errors()
{
// XXX excess casting here
if(control_mode>=AUTO && airspeed_nudge > 0) {
airspeed_error = g.airspeed_cruise + airspeed_nudge - airspeed;
airspeed_energy_error = (long)(((long)(g.airspeed_cruise + airspeed_nudge) * (long)(g.airspeed_cruise + airspeed_nudge)) - ((long)airspeed * (long)airspeed))/20000; //Changed 0.00005f * to / 20000 to avoid floating point calculation
} else {
airspeed_error = g.airspeed_cruise - airspeed;
airspeed_energy_error = (long)(((long)g.airspeed_cruise * (long)g.airspeed_cruise) - ((long)airspeed * (long)airspeed))/20000; //Changed 0.00005f * to / 20000 to avoid floating point calculation
}
}
static void calc_bearing_error()
{/*
if(takeoff_complete == true || g.compass_enabled == true) {
bearing_error = nav_bearing - dcm.yaw_sensor;
} else {
*/
// TODO: we need to use the Yaw gyro for in between GPS reads,
// maybe as an offset from a saved gryo value.
bearing_error = nav_bearing - g_gps->ground_course;
// }
bearing_error = wrap_180(bearing_error);
}
static void calc_altitude_error()
{
if(control_mode == AUTO && offset_altitude != 0) {
// limit climb rates
target_altitude = next_WP.alt - ((float)((wp_distance -30) * offset_altitude) / (float)(wp_totalDistance - 30));
// stay within a certain range
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);
}
} else if (non_nav_command_ID != MAV_CMD_CONDITION_CHANGE_ALT) {
target_altitude = next_WP.alt;
}
/*
// Disabled for now
#if AIRSPEED_SENSOR == 1
long altitude_estimate; // for smoothing GPS output
// special thanks to Ryan Beall for this one
float pitch_angle = pitch_sensor - g.pitch_trim; // pitch_angle = pitch sensor - angle of attack of your plane at level *100 (50 = .5°)
pitch_angle = constrain(pitch_angle, -2000, 2000);
float scale = sin(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;
}
static long wrap_360(long error)
{
if (error > 36000) error -= 36000;
if (error < 0) error += 36000;
return error;
}
static long wrap_180(long error)
{
if (error > 18000) error -= 36000;
if (error < -18000) error += 36000;
return error;
}
static void update_loiter()
{
float power;
if(wp_distance <= g.loiter_radius){
power = float(wp_distance) / float(g.loiter_radius);
power = constrain(power, 0.5, 1);
nav_bearing += (int)(9000.0 * (2.0 + power));
}else if(wp_distance < (g.loiter_radius + LOITER_RANGE)){
power = -((float)(wp_distance - g.loiter_radius - LOITER_RANGE) / LOITER_RANGE);
power = constrain(power, 0.5, 1); //power = constrain(power, 0, 1);
nav_bearing -= power * 9000;
}else{
update_crosstrack();
loiter_time = millis(); // keep start time for loiter updating till we get within LOITER_RANGE of orbit
}
/*
if (wp_distance < g.loiter_radius){
nav_bearing += 9000;
}else{
nav_bearing -= 100 * M_PI / 180 * asin(g.loiter_radius / wp_distance);
}
update_crosstrack();
*/
nav_bearing = wrap_360(nav_bearing);
}
static void update_crosstrack(void)
{
// Crosstrack Error
// ----------------
if (abs(wrap_180(target_bearing - crosstrack_bearing)) < 4500) { // If we are too far off or too close we don't do track following
crosstrack_error = sin(radians((target_bearing - crosstrack_bearing) / (float)100)) * (float)wp_distance; // Meters we are off track line
nav_bearing += constrain(crosstrack_error * g.crosstrack_gain, -g.crosstrack_entry_angle.get(), g.crosstrack_entry_angle.get());
nav_bearing = wrap_360(nav_bearing);
}
}
static void reset_crosstrack()
{
crosstrack_bearing = get_bearing(&current_loc, &next_WP); // Used for track following
}
static long get_distance(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 sqrt(sq(dlat) + sq(dlong)) * .01113195;
}
static 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 + atan2(-off_y, off_x) * 5729.57795;
if (bearing < 0) bearing += 36000;
return bearing;
}