BangBangTrajectory2D Class Reference

Inheritance diagram for BangBangTrajectory2D:

Collaboration diagram for BangBangTrajectory2D:

Public Member Functions
	BangBangTrajectory2D ()=default
	BangBangTrajectory2D (const Point &initial_pos, const Point &final_pos, const Vector &initial_vel, const KinematicConstraints &constraints)
void	generate (const Point &initial_pos, const Point &final_pos, const Vector &initial_vel, double max_vel, double max_accel, double max_decel)
Point	getPosition (double t_sec) const override
Vector	getVelocity (double t_sec) const override
Vector	getAcceleration (double t_sec) const override
double	getTotalTime () const override
std::vector< Rectangle >	getBoundingBoxes () const override
Public Member Functions inherited from Trajectory< Point, Vector, Vector >
Point	getDestination () const

Static Public Member Functions
static std::shared_ptr< Trajectory2D >	generator (const Point &initial_pos, const Point &final_pos, const Vector &initial_vel, const KinematicConstraints &constraints)

Constructor & Destructor Documentation

BangBangTrajectory2D() [1/2]

BangBangTrajectory2D ( )

default

Default constructor. Creates an empty trajectory.

BangBangTrajectory2D() [2/2]

BangBangTrajectory2D	(	const Point &	initial_pos,
		const Point &	final_pos,
		const Vector &	initial_vel,
		const KinematicConstraints &	constraints
	)

Generate a 2D trajectory from the initial position to the final position with the given initial velocity and kinematic constraints.

Parameters

initial_pos	Starting position of the trajectory
final_pos	Destination. Where the trajectory should end at
initial_vel	The initial velocity of the trajectory
constraints	Kinematic constraints of the new generated trajectory

Member Function Documentation

generate()

void generate	(	const Point &	initial_pos,
		const Point &	final_pos,
		const Vector &	initial_vel,
		double	max_vel,
		double	max_accel,
		double	max_decel
	)

Generate a 2D trajectory from the initial position to the final position with the given initial velocity and kinematic constraints.

Note

that calling generate will overwrite the existing trajectory.

Parameters

initial_pos	Starting position of the trajectory
final_pos	Destination. Where the trajectory should end at
initial_vel	The initial velocity of the trajectory
max_vel	The max velocity (in 2D) that the trajectory can reach at any given point
max_accel	The max acceleration (in 2D) that the trajectory can reach at any given point
max_decel	The max deceleration (in 2D) that the trajectory can reach at any given point

The following implementation is based on section IV of the paper "Trajectory generation for four wheeled omnidirectional vehicles"

A 2D trajectories is represented as 2x 1D trajectories (one for x and one for y) which take the same amount of time to reach the destination.

The max velocity, acceleration, and deceleration are assumed to be the kinematic constraints in 2D space, as opposed to the constraints for individual x and y components. To find the components of these constraints for each axis which will give us two trajectories with (almost) equal durations, we will use binary search over the components of the given kinematic constraints.

We will start with alpha = PI/4 (45 deg) which will have the x and y components equivalent to each other. Depending on which 1D trajectory takes longer to reach the destination, we will either increase or decrease alpha by increment (= PI/(8*2^i) where i is the iteration of binary search we're at). This will result in the component which is taking longer to reach the destination to get a larger component of the kinematic constraints relative to the other component which reaches the destination faster.

generator()

std::shared_ptr< Trajectory2D > generator ( const Point &  initial_pos, const Point &  final_pos, const Vector &  initial_vel, const KinematicConstraints &  constraints  )

static

Static function for generating a BangBangTrajectory2D pointer with Trajectory2D interface

Parameters

initial_pos	Where the trajectory should start at
final_pos	Where the trajectory should end at
initial_vel	The initial velocity of the trajectory
constraints	The kinematic constraints of the trajectory

Returns

A shared pointer to a BangBangTrajectory2D

getAcceleration()

Vector getAcceleration ( double  t_sec ) const

overridevirtual

Get the acceleration at time t

Parameters

t_sec

The time elapsed since the start of the trajectory in seconds

Returns

The acceleration at time t

Implements Trajectory< Point, Vector, Vector >.

getBoundingBoxes()

std::vector< Rectangle > getBoundingBoxes ( ) const

overridevirtual

Get the bounding box of the trajectory

Returns

bounding box which bounds the trajectory

Implements Trajectory2D.

getPosition()

Point getPosition ( double  t_sec ) const

overridevirtual

Get the position at time t

Parameters

t_sec

The time elapsed since the start of the trajectory in seconds

Returns

The position at time t

Implements Trajectory< Point, Vector, Vector >.

getTotalTime()

double getTotalTime ( ) const

overridevirtual

Get the total duration of the trajectory until it reaches the destination

Returns

The total duration for the trajectory in seconds

Implements Trajectory< Point, Vector, Vector >.

getVelocity()

Vector getVelocity ( double  t_sec ) const

overridevirtual

Get the velocity at time t

Parameters

t_sec

The time elapsed since the start of the trajectory in seconds

Returns

The velocity at time t

Implements Trajectory< Point, Vector, Vector >.

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

• src/software/ai/navigator/trajectory/bang_bang_trajectory_2d.h
• src/software/ai/navigator/trajectory/bang_bang_trajectory_2d.cpp