ardupilot/ArduCopter/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 byte navigate()
{
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// waypoint distance from plane in meters
// ---------------------------------------
wp_distance = get_distance(&current_loc, &next_WP);
home_distance = get_distance(&current_loc, &home);
if (wp_distance < 0){
//gcs_send_text_P(SEVERITY_HIGH,PSTR("<navigate> WP error - distance < 0"));
//Serial.println(wp_distance,DEC);
//print_current_waypoints();
return 0;
}
// target_bearing is where we should be heading
// --------------------------------------------
target_bearing = get_bearing(&current_loc, &next_WP);
home_to_copter_bearing = get_bearing(&home, &current_loc);
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// nav_bearing will includes xtrac correction
// ------------------------------------------
nav_bearing = target_bearing;
return 1;
}
static bool check_missed_wp()
{
int32_t temp;
temp = target_bearing - original_target_bearing;
temp = wrap_180(temp);
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return (abs(temp) > 10000); //we pased the waypoint by 10 °
}
// ------------------------------
static void calc_XY_velocity(){
// offset calculation of GPS speed:
// used for estimations below 1.5m/s
// our GPS is about 1m per
static int32_t last_longitude = 0;
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static int32_t last_latitude = 0;
//static int16_t x_speed_old = 0;
//static int16_t y_speed_old = 0;
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// y_GPS_speed positve = Up
// x_GPS_speed positve = Right
// this speed is ~ in cm because we are using 10^7 numbers from GPS
float tmp = 1.0/dTnav;
// straightforward approach:
///*
int16_t x_estimate = (float)(g_gps->longitude - last_longitude) * tmp;
int16_t y_estimate = (float)(g_gps->latitude - last_latitude) * tmp;
// slight averaging filter
x_GPS_speed = (x_GPS_speed + x_estimate) >> 1;
y_GPS_speed = (y_GPS_speed + y_estimate) >> 1;
//*/
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/*
// Ryan Beall's forward estimator:
int16_t x_speed_new = (float)(g_gps->longitude - last_longitude) * tmp;
int16_t y_speed_new = (float)(g_gps->latitude - last_latitude) * tmp;
x_GPS_speed = x_speed_new + (x_speed_new - x_speed_old);
y_GPS_speed = y_speed_new + (y_speed_new - y_speed_old);
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x_speed_old = x_speed_new;
y_speed_old = y_speed_new;
*/
last_longitude = g_gps->longitude;
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last_latitude = g_gps->latitude;
}
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static void calc_location_error(struct Location *next_loc)
{
/*
Becuase we are using lat and lon to do our distance errors here's a quick chart:
100 = 1m
1000 = 11m = 36 feet
1800 = 19.80m = 60 feet
3000 = 33m
10000 = 111m
*/
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// X Error
long_error = (float)(next_loc->lng - current_loc.lng) * scaleLongDown; // 500 - 0 = 500 Go East
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// Y Error
lat_error = next_loc->lat - current_loc.lat; // 500 - 0 = 500 Go North
}
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/*
//static void calc_loiter3(int x_error, int y_error)
{
static int32_t gps_lat_I = 0;
static int32_t gps_lon_I = 0;
// If close to goal <1m reset the I term
if (abs(x_error) < 50)
gps_lon_I = 0;
if (abs(y_error) < 50)
gps_lat_I = 0;
gps_lon_I += x_error;
gps_lat_I += y_error;
gps_lon_I = constrain(gps_lon_I,-3000,3000);
gps_lat_I = constrain(gps_lat_I,-3000,3000);
int16_t lon_P = 1.2 * (float)x_error;
int16_t lon_I = 0.1 * (float)gps_lon_I; //.1
int16_t lon_D = 3 * x_GPS_speed ; // this controls the small bumps
int16_t lat_P = 1.2 * (float)y_error;
int16_t lat_I = 0.1 * (float)gps_lat_I;
int16_t lat_D = 3 * y_GPS_speed ;
//limit of terms
lon_I = constrain(lon_I,-3000,3000);
lat_I = constrain(lat_I,-3000,3000);
lon_D = constrain(lon_D,-500,500); //this controls the long distance dampimg
lat_D = constrain(lat_D,-500,500); //this controls the long distance dampimg
nav_lon = lon_P + lon_I - lon_D;
nav_lat = lat_P + lat_I - lat_D;
Serial.printf("%d, %d, %d, %d, %d, %d\n",
lon_P, lat_P,
lon_I, lat_I,
lon_D, lat_D);
}
*/
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#define NAV_ERR_MAX 800
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static void calc_loiter(int x_error, int y_error)
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{
int16_t lon_PI = g.pi_loiter_lon.get_pi(x_error, dTnav);
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int16_t lon_D = g.loiter_d * x_actual_speed ; // this controls the small bumps
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int16_t lat_PI = g.pi_loiter_lat.get_pi(y_error, dTnav);
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int16_t lat_D = g.loiter_d * y_actual_speed ;
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//limit of terms
lon_D = constrain(lon_D,-500,500);
lat_D = constrain(lat_D,-500,500);
nav_lon = constrain(lon_PI - lon_D, -2500, 2500);
nav_lat = constrain(lat_PI - lat_D, -2500, 2500);
}
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static void calc_loiter1(int x_error, int y_error)
{
// East/West
x_error = constrain(x_error, -NAV_ERR_MAX, NAV_ERR_MAX); //800
int16_t x_target_speed = g.pi_loiter_lon.get_p(x_error);
int16_t x_iterm = g.pi_loiter_lon.get_i(x_error, dTnav);
x_rate_error = x_target_speed - x_actual_speed;
nav_lon_p = x_rate_error * g.loiter_d;
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nav_lon_p = constrain(nav_lon_p, -1200, 1200);
nav_lon = nav_lon_p + x_iterm;
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nav_lon = constrain(nav_lon, -2500, 2500);
// North/South
y_error = constrain(y_error, -NAV_ERR_MAX, NAV_ERR_MAX);
int16_t y_target_speed = g.pi_loiter_lat.get_p(y_error);
int16_t y_iterm = g.pi_loiter_lat.get_i(y_error, dTnav);
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y_rate_error = y_target_speed - y_actual_speed;
nav_lat_p = y_rate_error * g.loiter_d;
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nav_lat_p = constrain(nav_lat_p, -1200, 1200);
nav_lat = nav_lat_p + y_iterm;
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nav_lat = constrain(nav_lat, -2500, 2500);
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/*
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int8_t ttt = 1.0/dTnav;
int16_t t2 = g.pi_nav_lat.get_integrator();
// 1 2 3 4 5 6 7 8 9 10
Serial.printf("%d, %d, %d, %d, %d, %d, %d, %d, %d, %d\n",
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wp_distance, //1
y_error, //2
y_GPS_speed, //3
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y_actual_speed, //4 ;
y_target_speed, //5
y_rate_error, //6
nav_lat_p, //7
nav_lat, //8
y_iterm, //9
t2); //10
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//*/
/*
int16_t t1 = g.pi_nav_lon.get_integrator(); // X
Serial.printf("%d, %1.4f, %d, %d, %d, %d, %d, %d, %d, %d\n",
wp_distance, //1
dTnav, //2
x_error, //3
x_GPS_speed, //4
x_actual_speed, //5
x_target_speed, //6
x_rate_error, //7
nav_lat, //8
x_iterm, //9
t1); //10
//*/
}
//wp_distance,ttt, y_error, y_GPS_speed, y_actual_speed, y_target_speed, y_rate_error, nav_lat, y_iterm, t2
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#define ERR_GAIN .01
// called at 50hz
static void estimate_velocity()
{
// we need to extimate velocity when below GPS threshold of 1.5m/s
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//if(g_gps->ground_speed < 120){
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// some smoothing to prevent bumpy rides
x_actual_speed = (x_actual_speed * 15 + x_GPS_speed) / 16;
y_actual_speed = (y_actual_speed * 15 + y_GPS_speed) / 16;
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// integration of nav_p angle
//x_actual_speed += (nav_lon_p >>2);
//y_actual_speed += (nav_lat_p >>2);
// this is just what worked best in SIM
//x_actual_speed = (x_actual_speed * 2 + x_GPS_speed * 1) / 4;
//y_actual_speed = (y_actual_speed * 2 + y_GPS_speed * 1) / 4;
//}else{
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// less smoothing needed since the GPS already filters
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// x_actual_speed = (x_actual_speed * 3 + x_GPS_speed) / 4;
// y_actual_speed = (y_actual_speed * 3 + y_GPS_speed) / 4;
//}
}
// this calculation rotates our World frame of reference to the copter's frame of reference
// We use the DCM's matrix to precalculate these trig values at 50hz
static void calc_loiter_pitch_roll()
{
//Serial.printf("ys %ld, cx %1.4f, _cx %1.4f | sy %1.4f, _sy %1.4f\n", dcm.yaw_sensor, cos_yaw_x, _cos_yaw_x, sin_yaw_y, _sin_yaw_y);
// rotate the vector
nav_roll = (float)nav_lon * sin_yaw_y - (float)nav_lat * cos_yaw_x;
nav_pitch = (float)nav_lon * cos_yaw_x + (float)nav_lat * sin_yaw_y;
// flip pitch because forward is negative
nav_pitch = -nav_pitch;
}
static int16_t calc_desired_speed(int16_t max_speed)
{
/*
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|< WP Radius
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0 1 2 3 4 5 6 7 8m
...|...|...|...|...|...|...|...|
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100 | 200 300 400cm/s
| +|+
|< we should slow to 1.5 m/s as we hit the target
*/
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// max_speed is default 600 or 6m/s
// (wp_distance * .5) = 1/2 of the distance converted to speed
// wp_distance is always in m/s and not cm/s - I know it's stupid that way
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// for example 4m from target = 200cm/s speed
// we choose the lowest speed based on disance
max_speed = min(max_speed, wp_distance);
// go at least 100cm/s
max_speed = max(max_speed, WAYPOINT_SPEED_MIN);
// limit the ramp up of the speed
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// waypoint_speed_gov is reset to 0 at each new WP command
if(max_speed > waypoint_speed_gov){
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waypoint_speed_gov += (int)(100.0 * dTnav); // increase at .5/ms
max_speed = waypoint_speed_gov;
}
return max_speed;
}
static void calc_nav_rate(int max_speed)
{
// push us towards the original track
update_crosstrack();
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// nav_bearing includes crosstrack
float temp = (9000l - nav_bearing) * RADX100;
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x_rate_error = (cos(temp) * max_speed) - x_actual_speed; // 413
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x_rate_error = constrain(x_rate_error, -1000, 1000);
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int16_t x_iterm = g.pi_loiter_lon.get_i(x_rate_error, dTnav);
nav_lon_p = g.pi_nav_lon.get_p(x_rate_error);
nav_lon = nav_lon_p + x_iterm;
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nav_lon = constrain(nav_lon, -3000, 3000);
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y_rate_error = (sin(temp) * max_speed) - y_actual_speed; // 413
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y_rate_error = constrain(y_rate_error, -1000, 1000); // added a rate error limit to keep pitching down to a minimum
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int16_t y_iterm = g.pi_loiter_lat.get_i(y_rate_error, dTnav);
nav_lat_p = g.pi_nav_lat.get_p(y_rate_error);
nav_lat = nav_lat_p + y_iterm;
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nav_lat = constrain(nav_lat, -3000, 3000);
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/*
Serial.printf("max_sp %d,\t x_sp %d, y_sp %d,\t x_re: %d, y_re: %d, \tnav_lon: %d, nav_lat: %d, Xi:%d, Yi:%d, \t XE %d \n",
max_speed,
x_actual_speed,
y_actual_speed,
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x_rate_error,
y_rate_error,
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nav_lon,
nav_lat,
x_iterm,
y_iterm,
crosstrack_error);
//*/
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// nav_lat and nav_lon will be rotated to the angle of the quad in calc_nav_pitch_roll()
/*Serial.printf("max_speed: %d, xspeed: %d, yspeed: %d, x_re: %d, y_re: %d, nav_lon: %ld, nav_lat: %ld ",
max_speed,
x_actual_speed,
y_actual_speed,
x_rate_error,
y_rate_error,
nav_lon,
nav_lat);*/
}
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static void update_crosstrack(void)
{
// Crosstrack Error
// ----------------
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if (abs(wrap_180(target_bearing - original_target_bearing)) < 4500) { // If we are too far off or too close we don't do track following
float temp = (target_bearing - original_target_bearing) * RADX100;
crosstrack_error = sin(temp) * (wp_distance * g.crosstrack_gain); // Meters we are off track line
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nav_bearing = target_bearing + constrain(crosstrack_error, -3000, 3000);
nav_bearing = wrap_360(nav_bearing);
}else{
nav_bearing = target_bearing;
}
}
static int32_t get_altitude_error()
{
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// Next_WP alt is our target alt
// It changes based on climb rate
// until it reaches the target_altitude
return next_WP.alt - current_loc.alt;
}
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static void clear_new_altitude()
{
alt_change_flag = REACHED_ALT;
}
static void set_new_altitude(int32_t _new_alt)
{
// just to be clear
next_WP.alt = current_loc.alt;
// for calculating the delta time
alt_change_timer = millis();
// save the target altitude
target_altitude = _new_alt;
// reset our altitude integrator
alt_change = 0;
// save the original altitude
original_altitude = current_loc.alt;
// to decide if we have reached the target altitude
if(target_altitude > original_altitude){
// we are below, going up
alt_change_flag = ASCENDING;
//Serial.printf("go up\n");
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}else if(target_altitude < original_altitude){
// we are above, going down
alt_change_flag = DESCENDING;
//Serial.printf("go down\n");
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}else{
// No Change
alt_change_flag = REACHED_ALT;
//Serial.printf("reached alt\n");
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}
//Serial.printf("new alt: %d Org alt: %d\n", target_altitude, original_altitude);
}
static int32_t get_new_altitude()
{
// returns a new next_WP.alt
if(alt_change_flag == ASCENDING){
// we are below, going up
if(current_loc.alt >= target_altitude){
alt_change_flag = REACHED_ALT;
}
// we shouldn't command past our target
if(next_WP.alt >= target_altitude){
return target_altitude;
}
}else if (alt_change_flag == DESCENDING){
// we are above, going down
if(current_loc.alt <= target_altitude)
alt_change_flag = REACHED_ALT;
// we shouldn't command past our target
if(next_WP.alt <= target_altitude){
return target_altitude;
}
}
// if we have reached our target altitude, return the target alt
if(alt_change_flag == REACHED_ALT){
return target_altitude;
}
int32_t diff = abs(next_WP.alt - target_altitude);
int8_t _scale = 3;
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if (next_WP.alt < target_altitude){
// we are below the target alt
if(diff < 200){
_scale = 5;
} else {
_scale = 4;
}
}else {
// we are above the target, going down
if(diff < 600){
_scale = 4;
}
if(diff < 300){
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_scale = 5;
}
}
int32_t change = (millis() - alt_change_timer) >> _scale;
if(alt_change_flag == ASCENDING){
alt_change += change;
}else{
alt_change -= change;
}
// for generating delta time
alt_change_timer = millis();
return original_altitude + alt_change;
}
static int32_t wrap_360(int32_t error)
{
if (error > 36000) error -= 36000;
if (error < 0) error += 36000;
return error;
}
static int32_t wrap_180(int32_t error)
{
if (error > 18000) error -= 36000;
if (error < -18000) error += 36000;
return error;
}
/*
//static int32_t 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;
}
*/
// distance is returned in meters
static int32_t get_distance(struct Location *loc1, struct Location *loc2)
{
float dlat = (float)(loc2->lat - loc1->lat);
float dlong = ((float)(loc2->lng - loc1->lng)) * scaleLongDown;
dlong = sqrt(sq(dlat) + sq(dlong)) * 1.113195;
return dlong;
}
/*
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//static int32_t get_alt_distance(struct Location *loc1, struct Location *loc2)
{
return abs(loc1->alt - loc2->alt);
}
*/
static int32_t get_bearing(struct Location *loc1, struct Location *loc2)
{
int32_t off_x = loc2->lng - loc1->lng;
int32_t off_y = (loc2->lat - loc1->lat) * scaleLongUp;
int32_t bearing = 9000 + atan2(-off_y, off_x) * 5729.57795;
if (bearing < 0) bearing += 36000;
return bearing;
}