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AC_AttControl: alternative get_stopping_point_z

This commit is contained in:
Randy Mackay 2014-01-25 17:23:55 +09:00 committed by Andrew Tridgell
parent fc427967ae
commit 26b257c8ba
2 changed files with 21 additions and 8 deletions
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26
libraries/AC_AttitudeControl/AC_PosControl.cpp
View File

@ -75,6 +75,9 @@ AC_PosControl::AC_PosControl(const AP_AHRS& ahrs, const AP_InertialNav& inav,
///
/// set_speed_z - sets maximum climb and descent rates
/// To-Do: call this in the main code as part of flight mode initialisation
/// calc_leash_length_z should be called afterwards
/// speed_down should be a negative number
void AC_PosControl::set_speed_z(float speed_down, float speed_up)
{
if ((fabs(_speed_down_cms-speed_down) > 1.0f) || (fabs(_speed_up_cms-speed_up) > 1.0f)) {
@ -133,26 +136,33 @@ float AC_PosControl::get_alt_error() const
/// set_target_to_stopping_point_z - returns reasonable stopping altitude in cm above home
void AC_PosControl::set_target_to_stopping_point_z()
{
const Vector3f& curr_pos = _inav.get_position();
const Vector3f& curr_vel = _inav.get_velocity();
get_stopping_point_z(_pos_target);
}
/// get_stopping_point_z - sets stopping_point.z to a reasonable stopping altitude in cm above home
void AC_PosControl::get_stopping_point_z(Vector3f& stopping_point)
{
const float curr_pos_z = _inav.get_altitude();
const float curr_vel_z = _inav.get_velocity_z();
float linear_distance; // half the distace we swap between linear and sqrt and the distace we offset sqrt
float linear_velocity; // the velocity we swap between linear and sqrt
// calculate the velocity at which we switch from calculating the stopping point using a linear funcction to a sqrt function
linear_velocity = POSCONTROL_ALT_HOLD_ACCEL_MAX/_pi_alt_pos.kP();
if (fabs(curr_vel.z) < linear_velocity) {
if (fabs(curr_vel_z) < linear_velocity) {
// if our current velocity is below the cross-over point we use a linear function
_pos_target.z = curr_pos.z + curr_vel.z/_pi_alt_pos.kP();
stopping_point.z = curr_pos_z + curr_vel_z/_pi_alt_pos.kP();
} else {
linear_distance = POSCONTROL_ALT_HOLD_ACCEL_MAX/(2.0f*_pi_alt_pos.kP()*_pi_alt_pos.kP());
if (curr_vel.z > 0){
_pos_target.z = curr_pos.z + (linear_distance + curr_vel.z*curr_vel.z/(2.0f*POSCONTROL_ALT_HOLD_ACCEL_MAX));
if (curr_vel_z > 0){
stopping_point.z = curr_pos_z + (linear_distance + curr_vel_z*curr_vel_z/(2.0f*POSCONTROL_ALT_HOLD_ACCEL_MAX));
} else {
_pos_target.z = curr_pos.z - (linear_distance + curr_vel.z*curr_vel.z/(2.0f*POSCONTROL_ALT_HOLD_ACCEL_MAX));
stopping_point.z = curr_pos_z - (linear_distance + curr_vel_z*curr_vel_z/(2.0f*POSCONTROL_ALT_HOLD_ACCEL_MAX));
}
}
_pos_target.z = constrain_float(_pos_target.z, curr_pos.z - POSCONTROL_STOPPING_DIST_Z_MAX, curr_pos.z + POSCONTROL_STOPPING_DIST_Z_MAX);
stopping_point.z = constrain_float(stopping_point.z, curr_pos_z - POSCONTROL_STOPPING_DIST_Z_MAX, curr_pos_z + POSCONTROL_STOPPING_DIST_Z_MAX);
}
/// init_takeoff - initialises target altitude if we are taking off

3
libraries/AC_AttitudeControl/AC_PosControl.h
View File

@ -110,6 +110,9 @@ public:
/// set_target_to_stopping_point_z - sets altitude target to reasonable stopping altitude in cm above home
void set_target_to_stopping_point_z();
/// get_stopping_point_z - sets stopping_point.z to a reasonable stopping altitude in cm above home
void get_stopping_point_z(Vector3f& stopping_point);
/// init_takeoff - initialises target altitude if we are taking off
void init_takeoff();