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AC_PosControl: lean_angles_to_accel added for smooth initialisation

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init_xy_controller also added to capture initialisation all in one place
This commit is contained in:
Randy Mackay 2014-05-06 17:32:30 +09:00
parent b38c484874
commit 0819e05896
2 changed files with 95 additions and 30 deletions
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111
libraries/AC_AttitudeControl/AC_PosControl.cpp
View File

@ -64,6 +64,8 @@ AC_PosControl::AC_PosControl(const AP_AHRS& ahrs, const AP_InertialNav& inav,
_flags.recalc_leash_xy = true;
_flags.recalc_leash_z = true;
_flags.keep_xy_I_terms = false;
_flags.reset_desired_vel_to_pos = true;
_flags.reset_rate_to_accel_xy = true;
_flags.reset_rate_to_accel_z = true;
_flags.reset_accel_to_throttle = true;
}
@ -404,6 +406,13 @@ void AC_PosControl::set_pos_target(const Vector3f& position)
//_pitch_target = constrain_int32(_ahrs.pitch_sensor,-_attitude_control.lean_angle_max(),_attitude_control.lean_angle_max());
}
/// set_xy_target in cm from home
void AC_PosControl::set_xy_target(float x, float y)
{
_pos_target.x = x;
_pos_target.y = y;
}
/// set_target_to_stopping_point_xy - sets horizontal target to reasonable stopping position in cm from home
void AC_PosControl::set_target_to_stopping_point_xy()
{
@ -427,11 +436,17 @@ void AC_PosControl::get_stopping_point_xy(Vector3f &stopping_point) const
float stopping_dist; // the distance within the vehicle can stop
float kP = _p_pos_xy.kP();
// add velocity error to current velocity
if (is_active_xy()) {
curr_vel.x += _vel_error.x;
curr_vel.y += _vel_error.y;
}
// calculate current velocity
float vel_total = pythagorous2(curr_vel.x, curr_vel.y);
// avoid divide by zero by using current position if the velocity is below 10cm/s, kP is very low or acceleration is zero
if (vel_total < 10.0f || kP <= 0.0f || _accel_cms <= 0.0f) {
if (kP <= 0.0f || _accel_cms <= 0.0f) {
stopping_point.x = curr_pos.x;
stopping_point.y = curr_pos.y;
return;
@ -462,20 +477,51 @@ float AC_PosControl::get_distance_to_target() const
return _distance_to_target;
}
// is_active_xy - returns true if the xy position controller has been run very recently
bool AC_PosControl::is_active_xy() const
{
return ((hal.scheduler->millis() - _last_update_xy_ms) <= POSCONTROL_ACTIVE_TIMEOUT_MS);
}
/// init_xy_controller - initialise the xy controller
void AC_PosControl::init_xy_controller()
{
// reset xy controller to first step
_xy_step = 0;
// set roll, pitch lean angle targets to current attitude
_roll_target = _ahrs.roll_sensor;
_pitch_target = _ahrs.pitch_sensor;
// initialise I terms
if (!_flags.keep_xy_I_terms) {
reset_I_xy();
} else {
// reset keep_xy_I_term flag in case it has been set
_flags.keep_xy_I_terms = false;
}
// reset last velocity if this controller has just been engaged or dt is zero
lean_angles_to_accel(_accel_target.x, _accel_target.y);
_pid_rate_lat.set_integrator(_accel_target.x);
_pid_rate_lon.set_integrator(_accel_target.y);
// flag reset required in rate to accel step
_flags.reset_desired_vel_to_pos = true;
_flags.reset_rate_to_accel_xy = true;
// update update time
_last_update_xy_ms = hal.scheduler->millis();
}
/// update_xy_controller - run the horizontal position controller - should be called at 100hz or higher
void AC_PosControl::update_xy_controller(bool use_desired_velocity)
{
// catch if we've just been started
uint32_t now = hal.scheduler->millis();
if ((now - _last_update_xy_ms) >= POSCONTROL_ACTIVE_TIMEOUT_MS) {
_last_update_xy_ms = now;
if (!_flags.keep_xy_I_terms) {
reset_I_xy();
}
_xy_step = 0;
init_xy_controller();
}
// reset keep_xy_I_term flag in case it has been set
_flags.keep_xy_I_terms = false;
// check if xy leash needs to be recalculated
calc_leash_length_xy();
@ -532,24 +578,18 @@ void AC_PosControl::calc_leash_length_xy()
/// desired_vel_to_pos - move position target using desired velocities
void AC_PosControl::desired_vel_to_pos(float nav_dt)
{
Vector2f target_vel_adj;
float vel_desired_total;
// range check nav_dt
if( nav_dt < 0 ) {
return;
}
// constrain and scale the desired velocity
vel_desired_total = pythagorous2(_vel_desired.x, _vel_desired.y);
if (vel_desired_total > _speed_cms && vel_desired_total > 0.0f) {
_vel_desired.x = _speed_cms * _vel_desired.x/vel_desired_total;
_vel_desired.y = _speed_cms * _vel_desired.y/vel_desired_total;
}
// update target position
_pos_target.x += _vel_desired.x * nav_dt;
_pos_target.y += _vel_desired.y * nav_dt;
if (_flags.reset_desired_vel_to_pos) {
_flags.reset_desired_vel_to_pos = false;
} else {
_pos_target.x += _vel_desired.x * nav_dt;
_pos_target.y += _vel_desired.y * nav_dt;
}
}
/// pos_to_rate_xy - horizontal position error to velocity controller
@ -630,14 +670,20 @@ void AC_PosControl::rate_to_accel_xy(float dt)
float accel_total; // total acceleration in cm/s/s
float lat_i, lon_i;
// reset last velocity if this controller has just been engaged or dt is zero
if (dt == 0.0) {
_accel_target.x = 0;
_accel_target.y = 0;
} else {
// feed forward desired acceleration calculation
// reset last velocity target to current target
if (_flags.reset_rate_to_accel_xy) {
_vel_last.x = _vel_target.x;
_vel_last.y = _vel_target.y;
_flags.reset_rate_to_accel_xy = false;
}
// feed forward desired acceleration calculation
if (dt > 0.0f) {
_accel_target.x = (_vel_target.x - _vel_last.x)/dt;
_accel_target.y = (_vel_target.y - _vel_last.y)/dt;
} else {
_accel_target.x = 0.0f;
_accel_target.y = 0.0f;
}
// store this iteration's velocities for the next iteration
@ -667,7 +713,7 @@ void AC_PosControl::rate_to_accel_xy(float dt)
// scale desired acceleration if it's beyond acceptable limit
// To-Do: move this check down to the accel_to_lean_angle method?
accel_total = pythagorous2(_accel_target.x, _accel_target.y);
if (accel_total > POSCONTROL_ACCEL_XY_MAX) {
if (accel_total > POSCONTROL_ACCEL_XY_MAX && accel_total > 0.0f) {
_accel_target.x = POSCONTROL_ACCEL_XY_MAX * _accel_target.x/accel_total;
_accel_target.y = POSCONTROL_ACCEL_XY_MAX * _accel_target.y/accel_total;
_limit.accel_xy = true; // unused
@ -695,14 +741,19 @@ void AC_PosControl::accel_to_lean_angles()
_pitch_target = constrain_float(fast_atan(-accel_forward/(GRAVITY_MSS * 100))*(18000/M_PI),-lean_angle_max, lean_angle_max);
}
// get_lean_angles_to_accel - convert roll, pitch lean angles to lat/lon frame accelerations in cm/s/s
void AC_PosControl::lean_angles_to_accel(float& accel_x_cmss, float& accel_y_cmss)
{
// rotate our roll, pitch angles into lat/lon frame
accel_x_cmss = (GRAVITY_MSS * 100) * (-(_ahrs.cos_yaw() * _ahrs.sin_pitch() / max(_ahrs.cos_pitch(),0.5)) - _ahrs.sin_yaw() * _ahrs.sin_roll() / max(_ahrs.cos_roll(),0.5));
accel_y_cmss = (GRAVITY_MSS * 100) * (-(_ahrs.sin_yaw() * _ahrs.sin_pitch() / max(_ahrs.cos_pitch(),0.5)) + _ahrs.cos_yaw() * _ahrs.sin_roll() / max(_ahrs.cos_roll(),0.5));
}
/// reset_I_xy - clears I terms from loiter PID controller
void AC_PosControl::reset_I_xy()
{
_pid_rate_lon.reset_I();
_pid_rate_lat.reset_I();
// set last velocity to current velocity
_vel_last = _inav.get_velocity();
}
/// calc_leash_length - calculates the horizontal leash length given a maximum speed, acceleration and position kP gain

14
libraries/AC_AttitudeControl/AC_PosControl.h
View File

@ -136,6 +136,9 @@ public:
/// xy position controller
///
/// init_xy_controller - initialise the xy controller
void init_xy_controller();
/// set_accel_xy - set horizontal acceleration in cm/s/s
/// leash length will be recalculated the next time update_xy_controller() is called
void set_accel_xy(float accel_cmss);
@ -156,6 +159,9 @@ public:
/// set_pos_target in cm from home
void set_pos_target(const Vector3f& position);
/// set_xy_target in cm from home
void set_xy_target(float x, float y);
/// get_desired_velocity - returns xy desired velocity (i.e. feed forward) in cm/s in lat and lon direction
const Vector2f& get_desired_velocity() { return _vel_desired; }
@ -167,6 +173,9 @@ public:
/// trigger_xy - used to notify the position controller than an update has been made to the position or desired velocity so that the position controller will run as soon as possible after the update
void trigger_xy() { _flags.force_recalc_xy = true; }
// is_active_xy - returns true if the xy position controller has been run very recently
bool is_active_xy() const;
/// update_xy_controller - run the horizontal position controller - should be called at 100hz or higher
/// when use_desired_velocity is true the desired velocity (i.e. feed forward) is incorporated at the pos_to_rate step
void update_xy_controller(bool use_desired_velocity);
@ -201,6 +210,9 @@ public:
const Vector3f& get_vel_target() const { return _vel_target; }
const Vector3f& get_accel_target() const { return _accel_target; }
// lean_angles_to_accel - convert roll, pitch lean angles to lat/lon frame accelerations in cm/s/s
void lean_angles_to_accel(float& accel_x_cmss, float& accel_y_cmss);
static const struct AP_Param::GroupInfo var_info[];
private:
@ -212,6 +224,8 @@ private:
uint8_t force_recalc_xy : 1; // 1 if we want the xy position controller to run at it's next possible time. set by loiter and wp controllers after they have updated the target position.
uint8_t slow_cpu : 1; // 1 if we are running on a slow_cpu machine. xy position control is broken up into multiple steps
uint8_t keep_xy_I_terms : 1; // 1 if we are to keep I terms when the position controller is next run. Reset automatically back to zero in update_xy_controller.
uint8_t reset_desired_vel_to_pos: 1; // 1 if we should reset the rate_to_accel_xy step
uint8_t reset_rate_to_accel_xy : 1; // 1 if we should reset the rate_to_accel_xy step
uint8_t reset_rate_to_accel_z : 1; // 1 if we should reset the rate_to_accel_z step
uint8_t reset_accel_to_throttle : 1; // 1 if we should reset the accel_to_throttle step of the z-axis controller
} _flags;