void ActuatorOutputSubmarine::special_cmd(SPECIAL_COMMAND cmd)
{
switch(cmd) {
case (SUB_POWER_ON):
power_on();
break;
case (SUB_STARTUP_SEQUENCE):
SubmarineSingleton::get_instance().set_target_yaw(get_yaw());
SubmarineSingleton::get_instance().set_target_depth(get_depth());
startup_sequence();
break;
case (SUB_MISSION_STARTUP_SEQUENCE):
mission_startup_sequence();
break;
case (SUB_POWER_OFF):
power_off();
break;
default:
break;
}
}
// update L1 control for waypoint navigation
void AP_L1_Control::update_waypoint(const struct Location &prev_WP, const struct Location &next_WP, float dist_min)
{
struct Location _current_loc;
float Nu;
float xtrackVel;
float ltrackVel;
uint32_t now = AP_HAL::micros();
float dt = (now - _last_update_waypoint_us) * 1.0e-6f;
if (dt > 0.1) {
dt = 0.1;
_L1_xtrack_i = 0.0f;
}
_last_update_waypoint_us = now;
// Calculate L1 gain required for specified damping
float K_L1 = 4.0f * _L1_damping * _L1_damping;
// Get current position and velocity
if (_ahrs.get_position(_current_loc) == false) {
// if no GPS loc available, maintain last nav/target_bearing
_data_is_stale = true;
return;
}
Vector2f _groundspeed_vector = _ahrs.groundspeed_vector();
// update _target_bearing_cd
_target_bearing_cd = get_bearing_cd(_current_loc, next_WP);
//Calculate groundspeed
float groundSpeed = _groundspeed_vector.length();
if (groundSpeed < 0.1f) {
// use a small ground speed vector in the right direction,
// allowing us to use the compass heading at zero GPS velocity
groundSpeed = 0.1f;
_groundspeed_vector = Vector2f(cosf(get_yaw()), sinf(get_yaw())) * groundSpeed;
}
// Calculate time varying control parameters
// Calculate the L1 length required for specified period
// 0.3183099 = 1/1/pipi
_L1_dist = MAX(0.3183099f * _L1_damping * _L1_period * groundSpeed, dist_min);
// Calculate the NE position of WP B relative to WP A
Vector2f AB = location_diff(prev_WP, next_WP);
float AB_length = AB.length();
// Check for AB zero length and track directly to the destination
// if too small
if (AB.length() < 1.0e-6f) {
AB = location_diff(_current_loc, next_WP);
if (AB.length() < 1.0e-6f) {
AB = Vector2f(cosf(get_yaw()), sinf(get_yaw()));
}
}
AB.normalize();
// Calculate the NE position of the aircraft relative to WP A
Vector2f A_air = location_diff(prev_WP, _current_loc);
// calculate distance to target track, for reporting
_crosstrack_error = A_air % AB;
//Determine if the aircraft is behind a +-135 degree degree arc centred on WP A
//and further than L1 distance from WP A. Then use WP A as the L1 reference point
//Otherwise do normal L1 guidance
float WP_A_dist = A_air.length();
float alongTrackDist = A_air * AB;
if (WP_A_dist > _L1_dist && alongTrackDist/MAX(WP_A_dist, 1.0f) < -0.7071f)
{
//Calc Nu to fly To WP A
Vector2f A_air_unit = (A_air).normalized(); // Unit vector from WP A to aircraft
xtrackVel = _groundspeed_vector % (-A_air_unit); // Velocity across line
ltrackVel = _groundspeed_vector * (-A_air_unit); // Velocity along line
Nu = atan2f(xtrackVel,ltrackVel);
_nav_bearing = atan2f(-A_air_unit.y , -A_air_unit.x); // bearing (radians) from AC to L1 point
} else if (alongTrackDist > AB_length + groundSpeed*3) {
// we have passed point B by 3 seconds. Head towards B
// Calc Nu to fly To WP B
Vector2f B_air = location_diff(next_WP, _current_loc);
Vector2f B_air_unit = (B_air).normalized(); // Unit vector from WP B to aircraft
xtrackVel = _groundspeed_vector % (-B_air_unit); // Velocity across line
ltrackVel = _groundspeed_vector * (-B_air_unit); // Velocity along line
Nu = atan2f(xtrackVel,ltrackVel);
_nav_bearing = atan2f(-B_air_unit.y , -B_air_unit.x); // bearing (radians) from AC to L1 point
} else { //Calc Nu to fly along AB line
//Calculate Nu2 angle (angle of velocity vector relative to line connecting waypoints)
xtrackVel = _groundspeed_vector % AB; // Velocity cross track
ltrackVel = _groundspeed_vector * AB; // Velocity along track
float Nu2 = atan2f(xtrackVel,ltrackVel);
//Calculate Nu1 angle (Angle to L1 reference point)
float sine_Nu1 = _crosstrack_error/MAX(_L1_dist, 0.1f);
//Limit sine of Nu1 to provide a controlled track capture angle of 45 deg
sine_Nu1 = constrain_float(sine_Nu1, -0.7071f, 0.7071f);
float Nu1 = asinf(sine_Nu1);
// compute integral error component to converge to a crosstrack of zero when traveling
// straight but reset it when disabled or if it changes. That allows for much easier
// tuning by having it re-converge each time it changes.
if (_L1_xtrack_i_gain <= 0 || !is_equal(_L1_xtrack_i_gain.get(), _L1_xtrack_i_gain_prev)) {
_L1_xtrack_i = 0;
_L1_xtrack_i_gain_prev = _L1_xtrack_i_gain;
} else if (fabsf(Nu1) < radians(5)) {
_L1_xtrack_i += Nu1 * _L1_xtrack_i_gain * dt;
// an AHRS_TRIM_X=0.1 will drift to about 0.08 so 0.1 is a good worst-case to clip at
_L1_xtrack_i = constrain_float(_L1_xtrack_i, -0.1f, 0.1f);
}
// to converge to zero we must push Nu1 harder
Nu1 += _L1_xtrack_i;
Nu = Nu1 + Nu2;
_nav_bearing = atan2f(AB.y, AB.x) + Nu1; // bearing (radians) from AC to L1 point
}
_prevent_indecision(Nu);
_last_Nu = Nu;
//Limit Nu to +-(pi/2)
Nu = constrain_float(Nu, -1.5708f, +1.5708f);
_latAccDem = K_L1 * groundSpeed * groundSpeed / _L1_dist * sinf(Nu);
// Waypoint capture status is always false during waypoint following
_WPcircle = false;
_bearing_error = Nu; // bearing error angle (radians), +ve to left of track
_data_is_stale = false; // status are correctly updated with current waypoint data
}
