StopLine Class Reference

#include <stop_line.h>

Inheritance diagram for StopLine:

[legend]

List of all members.

Public Member Functions
result_t	control (pilot_command_t &pcmd, float topspeed=3.0)
void	reset (void)
	StopLine (Navigator *navptr, int _verbose)
	~StopLine ()
Private Member Functions
void	reset_me (void)
Private Attributes
bool	creeping
double	initial_speed
double	max_creep_distance
bool	stopping

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Detailed Description

Definition at line 15 of file stop_line.h.

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Constructor & Destructor Documentation

StopLine::StopLine	(	Navigator *	navptr,
		int	_verbose
	)

This is based on the unpublished "Control Tutorial" draft dated January 26, 2004 by Dr. Benjamin Kuypers, section 5: "The Stopping Controller". He recommends a constant deceleration instead of the simpler exponential decay. The dynamical system is:

x_dot = -k * sqrt(x)

Solving analytically with initial condition x(0) = D and v(0) = V yields these equations of motion:

x(t) = (sqrt(D) - V*t/(2*sqrt(D)))**2 (parabolic drop) v(t) = dx/dt = (V**2/2*D)*t + V (linear velocity) a(t) = dv/dt = V**2/(2*D) = A (constant deceleration)

Note that the initial velocity V is negative in these equations, because it represents motion from positive x to zero. The system stops in finite time T = -2*D/V, with x(T) = 0, and v(T) = 0.

For example, when D = 10m from stop line and V = -5m/s, the vehicle stops in 4 seconds at a constant 1.25m/s/s deceleration.

Definition at line 42 of file stop_line.cc.

StopLine::~StopLine

(

)

Definition at line 48 of file stop_line.cc.

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Member Function Documentation

Controller::result_t StopLine::control	(	pilot_command_t &	pcmd,
		float	topspeed = 3.0
	)

Set speed for steady deceleration to stop way-point

Precondition:

course->stop_waypt is goal way-point of stop

Parameters:

	pcmd	contains desired heading and speed, assuming it is not yet time to stop, updated on exit
	topspeed	velocity limit

Postcondition:

resets course->stop_waypt.id if reached.

Returns:

OK if in process of stopping; Finished if stop way-point reached.

Definition at line 63 of file stop_line.cc.

void StopLine::reset

(

void

)

[virtual]

Reimplemented from Controller.

Definition at line 156 of file stop_line.cc.

void StopLine::reset_me

(

void

)

[private, virtual]

Reimplemented from Controller.

Definition at line 163 of file stop_line.cc.

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Member Data Documentation

bool StopLine::creeping [private]

Definition at line 28 of file stop_line.h.

double StopLine::initial_speed [private]

Definition at line 29 of file stop_line.h.

double StopLine::max_creep_distance [private]

Definition at line 30 of file stop_line.h.

bool StopLine::stopping [private]

Definition at line 27 of file stop_line.h.

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The documentation for this class was generated from the following files:

• stop_line.h
• stop_line.cc