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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 void navigate()
{
// waypoint distance from plane in cm
// ---------------------------------------
wp_distance = get_distance_cm(&filtered_loc, &next_WP);
home_distance = get_distance_cm(&filtered_loc, &home);
// target_bearing is where we should be heading
// --------------------------------------------
target_bearing = get_bearing_cd(&filtered_loc, &next_WP);
home_to_copter_bearing = get_bearing_cd(&home, &current_loc);
}
static bool check_missed_wp()
{
int32_t temp;
temp = target_bearing - original_target_bearing;
temp = wrap_180(temp);
return (labs(temp) > 9000); // we passed the waypoint by 100 degrees
}
// ------------------------------
static void calc_XY_velocity(){
static int32_t last_longitude = 0;
static int32_t last_latitude = 0;
// called after GPS read
// offset calculation of GPS speed:
// used for estimations below 1.5m/s
// y_GPS_speed positve = Up
// x_GPS_speed positve = Right
// initialise last_longitude and last_latitude
if( last_longitude == 0 && last_latitude == 0 ) {
last_longitude = g_gps->longitude;
last_latitude = g_gps->latitude;
}
// this speed is ~ in cm because we are using 10^7 numbers from GPS
float tmp = 1.0/dTnav;
x_actual_speed = (float)(g_gps->longitude - last_longitude) * scaleLongDown * tmp;
y_actual_speed = (float)(g_gps->latitude - last_latitude) * tmp;
last_longitude = g_gps->longitude;
last_latitude = g_gps->latitude;
#if INERTIAL_NAV == ENABLED
// inertial_nav
xy_error_correction();
filtered_loc.lng = xLeadFilter.get_position(g_gps->longitude, accels_velocity.x);
filtered_loc.lat = yLeadFilter.get_position(g_gps->latitude, accels_velocity.y);
#else
filtered_loc.lng = xLeadFilter.get_position(g_gps->longitude, x_actual_speed, g_gps->get_lag());
filtered_loc.lat = yLeadFilter.get_position(g_gps->latitude, y_actual_speed, g_gps->get_lag());
#endif
}
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
*/
// X Error
long_error = (float)(next_loc->lng - current_loc.lng) * scaleLongDown; // 500 - 0 = 500 Go East
// Y Error
lat_error = next_loc->lat - current_loc.lat; // 500 - 0 = 500 Go North
}
#define NAV_ERR_MAX 600
#define NAV_RATE_ERR_MAX 250
static void calc_loiter(int16_t x_error, int16_t y_error)
{
int32_t p,i,d; // used to capture pid values for logging
int32_t output;
int32_t x_target_speed, y_target_speed;
// East / West
x_target_speed = g.pi_loiter_lon.get_p(x_error); // calculate desired speed from lon error
#if LOGGING_ENABLED == ENABLED
// log output if PID logging is on and we are tuning the yaw
if( g.log_bitmask & MASK_LOG_PID && (g.radio_tuning == CH6_LOITER_KP || g.radio_tuning == CH6_LOITER_KI) ) {
Log_Write_PID(CH6_LOITER_KP, x_error, x_target_speed, 0, 0, x_target_speed, tuning_value);
}
#endif
// calculate rate error
#if INERTIAL_NAV == ENABLED
x_rate_error = x_target_speed - accels_velocity.x; // calc the speed error
#else
x_rate_error = x_target_speed - x_actual_speed; // calc the speed error
#endif
p = g.pid_loiter_rate_lon.get_p(x_rate_error);
i = g.pid_loiter_rate_lon.get_i(x_rate_error + x_error, dTnav);
d = g.pid_loiter_rate_lon.get_d(x_error, dTnav);
d = constrain(d, -2000, 2000);
// get rid of noise
if(abs(x_actual_speed) < 50) {
d = 0;
}
output = p + i + d;
nav_lon = constrain(output, -32000, 32000); // constraint to remove chance of overflow when adding int32_t to int16_t
#if LOGGING_ENABLED == ENABLED
// log output if PID logging is on and we are tuning the yaw
if( g.log_bitmask & MASK_LOG_PID && (g.radio_tuning == CH6_LOITER_RATE_KP || g.radio_tuning == CH6_LOITER_RATE_KI || g.radio_tuning == CH6_LOITER_RATE_KD) ) {
Log_Write_PID(CH6_LOITER_RATE_KP, x_rate_error, p, i, d, nav_lon, tuning_value);
}
#endif
// North / South
y_target_speed = g.pi_loiter_lat.get_p(y_error); // calculate desired speed from lat error
#if LOGGING_ENABLED == ENABLED
// log output if PID logging is on and we are tuning the yaw
if( g.log_bitmask & MASK_LOG_PID && (g.radio_tuning == CH6_LOITER_KP || g.radio_tuning == CH6_LOITER_KI) ) {
Log_Write_PID(CH6_LOITER_KP+100, y_error, y_target_speed, 0, 0, y_target_speed, tuning_value);
}
#endif
// calculate rate error
#if INERTIAL_NAV == ENABLED
y_rate_error = y_target_speed - accels_velocity.y; // calc the speed error
#else
y_rate_error = y_target_speed - y_actual_speed; // calc the speed error
#endif
p = g.pid_loiter_rate_lat.get_p(y_rate_error);
i = g.pid_loiter_rate_lat.get_i(y_rate_error + y_error, dTnav);
d = g.pid_loiter_rate_lat.get_d(y_error, dTnav);
d = constrain(d, -2000, 2000);
// get rid of noise
if(abs(y_actual_speed) < 50) {
d = 0;
}
output = p + i + d;
nav_lat = constrain(output, -32000, 32000); // constraint to remove chance of overflow when adding int32_t to int16_t
#if LOGGING_ENABLED == ENABLED
// log output if PID logging is on and we are tuning the yaw
if( g.log_bitmask & MASK_LOG_PID && (g.radio_tuning == CH6_LOITER_RATE_KP || g.radio_tuning == CH6_LOITER_RATE_KI || g.radio_tuning == CH6_LOITER_RATE_KD) ) {
Log_Write_PID(CH6_LOITER_RATE_KP+100, y_rate_error, p, i, d, nav_lat, tuning_value);
}
#endif
// copy over I term to Nav_Rate
g.pid_nav_lon.set_integrator(g.pid_loiter_rate_lon.get_integrator());
g.pid_nav_lat.set_integrator(g.pid_loiter_rate_lat.get_integrator());
}
static void calc_nav_rate(int16_t max_speed)
{
float temp, temp_x, temp_y;
// push us towards the original track
update_crosstrack();
int16_t cross_speed = crosstrack_error * -g.crosstrack_gain; // scale down crosstrack_error in cm
cross_speed = constrain(cross_speed, -150, 150);
// rotate by 90 to deal with trig functions
temp = (9000l - target_bearing) * RADX100;
temp_x = cos(temp);
temp_y = sin(temp);
// rotate desired spped vector:
int32_t x_target_speed = max_speed * temp_x - cross_speed * temp_y;
int32_t y_target_speed = cross_speed * temp_x + max_speed * temp_y;
// East / West
// calculate rate error
#if INERTIAL_NAV == ENABLED
x_rate_error = x_target_speed - accels_velocity.x;
#else
x_rate_error = x_target_speed - x_actual_speed;
#endif
x_rate_error = constrain(x_rate_error, -500, 500);
nav_lon = g.pid_nav_lon.get_pid(x_rate_error, dTnav);
int32_t tilt = (x_target_speed * x_target_speed * (int32_t)g.tilt_comp) / 10000;
if(x_target_speed < 0) tilt = -tilt;
nav_lon += tilt;
// North / South
// calculate rate error
#if INERTIAL_NAV == ENABLED
y_rate_error = y_target_speed - accels_velocity.y;
#else
y_rate_error = y_target_speed - y_actual_speed;
#endif
y_rate_error = constrain(y_rate_error, -500, 500); // added a rate error limit to keep pitching down to a minimum
nav_lat = g.pid_nav_lat.get_pid(y_rate_error, dTnav);
tilt = (y_target_speed * y_target_speed * (int32_t)g.tilt_comp) / 10000;
if(y_target_speed < 0) tilt = -tilt;
nav_lat += tilt;
// copy over I term to Loiter_Rate
g.pid_loiter_rate_lon.set_integrator(g.pid_nav_lon.get_integrator());
g.pid_loiter_rate_lat.set_integrator(g.pid_nav_lat.get_integrator());
}
// 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
auto_roll = (float)nav_lon * sin_yaw_y - (float)nav_lat * cos_yaw_x;
auto_pitch = (float)nav_lon * cos_yaw_x + (float)nav_lat * sin_yaw_y;
// flip pitch because forward is negative
auto_pitch = -auto_pitch;
}
static int16_t get_desired_speed(int16_t max_speed)
{
/*
Based on Equation by Bill Premerlani & Robert Lefebvre
(sq(V2)-sq(V1))/2 = A(X2-X1)
derives to:
V1 = sqrt(sq(V2) - 2*A*(X2-X1))
*/
if(fast_corner) {
// don't slow down
}else{
if(wp_distance < 20000){ // limit the size of numbers we're dealing with to avoide overflow
// go slower
int32_t temp = 2 * 100 * (int32_t)(wp_distance - g.waypoint_radius * 100);
int32_t s_min = WAYPOINT_SPEED_MIN;
temp += s_min * s_min;
max_speed = sqrt((float)temp);
max_speed = min(max_speed, g.waypoint_speed_max);
}
}
max_speed = min(max_speed, max_speed_old + (100 * dTnav));// limit going faster
max_speed = max(max_speed, WAYPOINT_SPEED_MIN); // don't go too slow
max_speed_old = max_speed;
return max_speed;
}
static void reset_desired_speed()
{
max_speed_old = 0;
}
static int16_t get_desired_climb_rate()
{
if(alt_change_flag == ASCENDING) {
return constrain(altitude_error / 4, 100, 180); // 180cm /s up, minimum is 100cm/s
}else if(alt_change_flag == DESCENDING) {
return constrain(altitude_error / 6, -100, -10); // -100cm /s down, max is -10cms
}else{
return 0;
}
}
static void update_crosstrack(void)
{
// Crosstrack Error
// ----------------
// 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; // Meters we are off track line
}
static int32_t get_altitude_error()
{
// 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;
}
static void clear_new_altitude()
{
alt_change_flag = REACHED_ALT;
}
static void force_new_altitude(int32_t new_alt)
{
next_WP.alt = new_alt;
alt_change_flag = REACHED_ALT;
}
static void set_new_altitude(int32_t new_alt)
{
next_WP.alt = new_alt;
if(next_WP.alt > current_loc.alt + 20) {
// we are below, going up
alt_change_flag = ASCENDING;
}else if(next_WP.alt < current_loc.alt - 20) {
// we are above, going down
alt_change_flag = DESCENDING;
}else{
// No Change
alt_change_flag = REACHED_ALT;
}
}
static void verify_altitude()
{
if(alt_change_flag == ASCENDING) {
// we are below, going up
if(current_loc.alt > next_WP.alt - 50) {
alt_change_flag = REACHED_ALT;
}
}else if (alt_change_flag == DESCENDING) {
// we are above, going down
if(current_loc.alt <= next_WP.alt + 50)
alt_change_flag = REACHED_ALT;
}
}
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;
}
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