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 (!have_position) {
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("WP error - distance < 0"));
return;
}
// target_bearing is where we should be heading
// --------------------------------------------
target_bearing_cd = get_bearing_cd(&current_loc, &next_WP);
// nav_bearing will includes xtrac correction
// ------------------------------------------
nav_bearing_cd = target_bearing_cd;
// check if we have missed the WP
loiter_delta = (target_bearing_cd - old_target_bearing_cd)/100;
// reset the old value
old_target_bearing_cd = target_bearing_cd;
// 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 * .0002f * cosf(radians(bearing_error_cd * .01f));
distance_estimate -= DST_EST_GAIN * (float)(distance_estimate - GPS_wp_distance);
wp_distance = max(distance_estimate,10);
}
#endif
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) {
target_airspeed_cm = ((int)(g.flybywire_airspeed_max -
g.flybywire_airspeed_min) *
g.channel_throttle.servo_out) +
((int)g.flybywire_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 > (g.flybywire_airspeed_max * 100))
target_airspeed_cm = (g.flybywire_airspeed_max * 100);
airspeed_error_cm = target_airspeed_cm - aspeed_cm;
airspeed_energy_error = ((target_airspeed_cm * target_airspeed_cm) - (aspeed_cm*aspeed_cm))*0.00005;
}
static void calc_gndspeed_undershoot()
{
// Function is overkill, but here in case we want to add filtering
// later
if (g_gps && g_gps->status() == GPS::GPS_OK) {
groundspeed_undershoot = (g.min_gndspeed_cm > 0) ? (g.min_gndspeed_cm - g_gps->ground_speed) : 0;
}
}
static void calc_bearing_error()
{
bearing_error_cd = nav_bearing_cd - ahrs.yaw_sensor;
bearing_error_cd = wrap_180_cd(bearing_error_cd);
}
static void calc_altitude_error()
{
if(control_mode == AUTO && offset_altitude_cm != 0) {
// limit climb rates
target_altitude_cm = next_WP.alt - ((float)((wp_distance -30) * offset_altitude_cm) / (float)(wp_totalDistance - 30));
// stay within a certain range
if(prev_WP.alt > next_WP.alt) {
target_altitude_cm = constrain_int32(target_altitude_cm, next_WP.alt, prev_WP.alt);
}else{
target_altitude_cm = constrain_int32(target_altitude_cm, prev_WP.alt, next_WP.alt);
}
} else if (non_nav_command_ID != MAV_CMD_CONDITION_CHANGE_ALT) {
target_altitude_cm = next_WP.alt;
}
altitude_error_cm = target_altitude_cm - adjusted_altitude_cm();
}
static int32_t wrap_360_cd(int32_t error)
{
if (error > 36000) error -= 36000;
if (error < 0) error += 36000;
return error;
}
static int32_t wrap_180_cd(int32_t error)
{
if (error > 18000) error -= 36000;
if (error < -18000) error += 36000;
return error;
}
static void update_loiter()
{
float power;
if(wp_distance <= (uint32_t)max(g.loiter_radius,0)) {
power = float(wp_distance) / float(g.loiter_radius);
power = constrain(power, 0.5, 1);
nav_bearing_cd += 9000.0 * (2.0 + power);
} else if(wp_distance < (uint32_t)max((g.loiter_radius + LOITER_RANGE),0)) {
power = -((float)(wp_distance - g.loiter_radius - LOITER_RANGE) / LOITER_RANGE);
power = constrain(power, 0.5, 1); //power = constrain(power, 0, 1);
nav_bearing_cd -= power * 9000;
} else{
update_crosstrack();
loiter_time_ms = 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 * asinf(g.loiter_radius / wp_distance);
* }
*
* update_crosstrack();
*/
nav_bearing_cd = wrap_360_cd(nav_bearing_cd);
}
static void update_crosstrack(void)
{
// if we are using a compass for navigation, then adjust the
// heading to account for wind
if (g.crosstrack_use_wind && compass.use_for_yaw()) {
Vector3f wind = ahrs.wind_estimate();
Vector2f wind2d = Vector2f(wind.x, wind.y);
float speed;
if (ahrs.airspeed_estimate(&speed)) {
Vector2f nav_vector = Vector2f(cosf(radians(nav_bearing_cd*0.01)), sinf(radians(nav_bearing_cd*0.01))) * speed;
Vector2f nav_adjusted = nav_vector - wind2d;
nav_bearing_cd = degrees(atan2f(nav_adjusted.y, nav_adjusted.x)) * 100;
}
}
// Crosstrack Error
// ----------------
// If we are too far off or too close we don't do track following
if (wp_totalDistance >= (uint32_t)max(g.crosstrack_min_distance,0) &&
abs(wrap_180_cd(target_bearing_cd - crosstrack_bearing_cd)) < 4500) {
// Meters we are off track line
crosstrack_error = sinf(radians((target_bearing_cd - crosstrack_bearing_cd) * 0.01)) * wp_distance;
nav_bearing_cd += constrain_int32(crosstrack_error * g.crosstrack_gain, -g.crosstrack_entry_angle.get(), g.crosstrack_entry_angle.get());
nav_bearing_cd = wrap_360_cd(nav_bearing_cd);
}
}
static void reset_crosstrack()
{
crosstrack_bearing_cd = get_bearing_cd(&prev_WP, &next_WP); // Used for track following
}