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()
{
// waypoint distance from plane
// ----------------------------
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);
return 1;
}
static bool check_missed_wp()
{
int32_t temp = target_bearing - original_target_bearing;
temp = wrap_180(temp);
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;
static int32_t last_latutude = 0;
if(g_gps->ground_speed > 150){
// Derive X/Y speed from GPS
// this is far more accurate when traveling about 1.5m/s
float temp = g_gps->ground_course * RADX100;
x_GPS_speed = sin(temp) * (float)g_gps->ground_speed;
y_GPS_speed = cos(temp) * (float)g_gps->ground_speed;
}else{
// this speed is ~ in cm because we are using 10^7 numbers from GPS
int16_t x_diff = (last_longitude - g_gps->longitude);
int16_t y_diff = (last_latutude - g_gps->latitude);
if(x_diff == 0)
x_GPS_speed = x_GPS_speed /2;
else
x_GPS_speed = x_diff;
if(y_diff == 0)
y_GPS_speed = y_GPS_speed /2;
else
y_GPS_speed = y_diff;
}
last_longitude = g_gps->longitude;
last_latutude = g_gps->latitude;
//Serial.printf("GS: %d \tx:%d \ty:%d\n", g_gps->ground_speed, x_GPS_speed, y_GPS_speed);
}
// long_error, lat_error
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
pitch_max = 22° (2200)
*/
// X ROLL
long_error = (float)(next_loc->lng - current_loc.lng) * scaleLongDown; // 500 - 0 = 500 roll EAST
// Y PITCH
lat_error = next_loc->lat - current_loc.lat; // 0 - 500 = -500 pitch NORTH
}
#define NAV_ERR_MAX 800
static void calc_loiter(int x_error, int y_error)
{
x_error = constrain(x_error, -NAV_ERR_MAX, NAV_ERR_MAX);
y_error = constrain(y_error, -NAV_ERR_MAX, NAV_ERR_MAX);
int16_t x_target_speed = g.pi_loiter_lon.get_p(x_error);
int16_t y_target_speed = g.pi_loiter_lat.get_p(y_error);
int16_t x_iterm = g.pi_loiter_lon.get_i(x_error, dTnav);
int16_t y_iterm = g.pi_loiter_lat.get_i(y_error, dTnav);
y_rate_error = y_target_speed - y_actual_speed; // 413
y_rate_error = constrain(y_rate_error, -1000, 1000); // added a rate error limit to keep pitching down to a minimum
nav_lat = g.pi_nav_lat.get_pi(y_rate_error, dTnav);
nav_lat = constrain(nav_lat, -3500, 3500);
nav_lat += y_iterm;
x_rate_error = x_target_speed - x_actual_speed;
x_rate_error = constrain(x_rate_error, -1000, 1000);
nav_lon = g.pi_nav_lon.get_pi(x_rate_error, dTnav);
nav_lon = constrain(nav_lon, -3500, 3500);
nav_lon += x_iterm;
/*Serial.printf("WP_dist: %d, loiter x_actual_speed %d,\tx_rate_error: %d,\tnav_lon: %d,\ty_actual_speed %d,\ty_rate_error: %d,\tnav_lat: %d,\n",
wp_distance,
x_actual_speed,
x_rate_error,
nav_lon,
y_actual_speed,
y_rate_error,
nav_lat);
//*/
}
#define ERR_GAIN .01
// called at 50hz
static void esitmate_velocity()
{
// for now we assume copter is pointing due north
// use roll to calculate the x velocity
//float scale = sin((float)nav_lon * RADX100)); // guess our X location based tilt of copter
// we need to extimate velocity when below GPS threshold of 1.5m/s
if(g_gps->ground_speed < 150){
// calc the cos of the error to tell how fast we are moving towards the target in cm
//if(g.optflow_enabled && current_loc.alt < 500){
// optflow wont be enabled on 1280's
// #ifdef OPTFLOW_ENABLED
//x_actual_speed = optflow.vlon * 10;
//y_actual_speed = optflow.vlat * 10;
// #endif
//}else{
// this area will have future IMU based velocity navigation,
// ignore these sketches.
// need to take into account the wind based on loiter's iterms
// x_actual_speed += thrust * sin_roll_y; // thrust is a guess, needs to be calibrated whith CH6
// x_actual_speed -= ERR_GAIN * (float)(x_actual_speed - x_GPS_speed); // error correction
// y_actual_speed += thrust * sin_pitch_y; // thrust is a guess, needs to be calibrated whith CH6
// y_actual_speed -= ERR_GAIN * (float)(y_actual_speed - y_GPS_speed); // error correction
//}
// for now
// light filter of output
x_actual_speed = (x_actual_speed * 3 + x_GPS_speed) / 4;
y_actual_speed = (y_actual_speed * 3 + y_GPS_speed) / 4;
}else{
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 void calc_nav_rate(int max_speed)
{
/*
|< WP Radius
0 1 2 3 4 5 6 7 8m
...|...|...|...|...|...|...|...|
100 | 200 300 400cm/s
| +|+
|< we should slow to 1.5 m/s as we hit the target
*/
// max_speed is default 400 or 4m/s
// (wp_distance * 50) = 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
// for example 4m from target = 200cm/s speed
// we choose the lowest speed based on disance
max_speed = min(max_speed, (wp_distance * 50));
// limit the ramp up of the speed
// waypoint_speed_gov is reset to 0 at each new WP command
if(waypoint_speed_gov < max_speed){
waypoint_speed_gov += (int)(100.0 * dTnav); // increase at 1.5/ms
// go at least 50cm/s
max_speed = max(50, waypoint_speed_gov);
// limit with governer
max_speed = min(max_speed, waypoint_speed_gov);
}
float temp = (target_bearing - g_gps->ground_course) * RADX100;
// push us towards the original track
update_crosstrack();
// heading laterally, we want a zero speed here
x_actual_speed = -sin(temp) * (float)g_gps->ground_speed;
x_rate_error = crosstrack_error -x_actual_speed;
x_rate_error = constrain(x_rate_error, -1400, 1400);
nav_lon = constrain(g.pi_nav_lon.get_pi(x_rate_error, dTnav), -3500, 3500);
/*Serial.printf("max_sp %d,\tx_actual_sp %d,\tx_rate_err: %d, Xtrack %d, \tnav_lon: %d,\ty_actual_sp %d,\ty_rate_err: %d,\tnav_lat: %d,\n",
max_speed,
x_actual_speed,
x_rate_error,
crosstrack_error,
nav_lon,
y_actual_speed,
y_rate_error,
nav_lat);
//*/
// heading towards target
y_actual_speed = cos(temp) * (float)g_gps->ground_speed;
y_rate_error = max_speed - y_actual_speed; // 413
y_rate_error = constrain(y_rate_error, -1400, 1400); // added a rate error limit to keep pitching down to a minimum
nav_lat = constrain(g.pi_nav_lat.get_pi(y_rate_error, dTnav), -3500, 3500);
// 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);*/
}
static void update_crosstrack(void)
{
// Crosstrack Error
// ----------------
if (cross_track_test() < 4000) { // 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
crosstrack_error = constrain(crosstrack_error, -1200, 1200);
}
}
// used to generate the offset angle for testing crosstrack viability
static int32_t cross_track_test()
{
int32_t temp;
temp = target_bearing - original_target_bearing;
temp = wrap_180(temp);
return abs(temp);
}
// this calculation is different than loiter above because we are in a different Frame of Reference.
// nav_lat is pointed towards the target, where as in Loiter, nav_lat is pointed north!
static void calc_nav_pitch_roll()
{
int32_t angle = wrap_360(dcm.yaw_sensor - target_bearing);
float temp = (9000l - angle) * RADX100;
//t: 1.5465, t1: -10.9451, t2: 1.5359, t3: 1.5465
float _cos_yaw_x = cos(temp);
float _sin_yaw_y = sin(temp);
// 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;
/*Serial.printf("Yaw %d, Tbear:%d, \tangle: %d, \t_cos_yaw_x:%1.4f, _sin_yaw_y:%1.4f, nav_roll:%d, nav_pitch:%d\n",
dcm.yaw_sensor,
target_bearing,
angle,
_cos_yaw_x,
_sin_yaw_y,
nav_roll,
nav_pitch);*/
}
static int32_t get_altitude_error()
{
return next_WP.alt - current_loc.alt;
}
/*
//static int get_loiter_angle()
{
float power;
int angle;
if(wp_distance <= g.loiter_radius){
power = float(wp_distance) / float(g.loiter_radius);
power = constrain(power, 0.5, 1);
angle = 90.0 * (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);
angle = power * 90;
}
return angle;
}*/
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_crosstrack_correction(void)
{
// Crosstrack Error
// ----------------
if (cross_track_test() < 9000) { // If we are too far off or too close we don't do track following
// Meters we are off track line
float error = sin(radians((target_bearing - crosstrack_bearing) / (float)100)) * (float)wp_distance;
// take meters * 100 to get adjustment to nav_bearing
int32_t _crosstrack_correction = g.pi_crosstrack.get_pi(error, dTnav) * 100;
// constrain answer to 30° to avoid overshoot
return constrain(_crosstrack_correction, -g.crosstrack_entry_angle.get(), g.crosstrack_entry_angle.get());
}
return 0;
}
*/
/*
//static int32_t cross_track_test()
{
int32_t temp = wrap_180(target_bearing - crosstrack_bearing);
return abs(temp);
}
*/
/*
//static void reset_crosstrack()
{
crosstrack_bearing = get_bearing(&current_loc, &next_WP); // Used for track following
}
*/
/*
//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)
{
//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 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;
}