RailFollower< T > Class Template Reference

Detailed Description

template<typename T>
class delphyne::RailFollower< T >

RailFollower models an entity that follows a maliput::api::Lane as if it were on rails and neglecting all physics.

Parameters:

• See RailFollowerParams.

Continuous State:

• See RailFollowerState.

Abstract state:

• See LaneDirection.

Input Port Accessors:

• command_input(): Contains the desired acceleration. This port contains a drake::systems::BasicVector of size 1. It is optional in that it need not be connected. When it is unconnected, the modelled entity will travel at its initial velocity, which is specified in RailFollowerParams.

Output Port Accessors:

• state_output(): Contains this system's state vector. See RailFollowerState.
• lane_state_output(): Contains this system's lane direction state. See LaneDirection.
• pose_output(): Contains PoseVector X_WC, where C is the car frame and W is the world frame.
• velocity_output(): Contains FrameVelocity V_WC_W, where C is the car frame and W is the world frame. Currently the rotational component is always zero, see #5751.

Template Parameters

T	must support certain arithmetic operations; for details, see delphyne::Symbolic.

Instantiated templates for the following ScalarTypes are provided:

• double

#include <src/systems/rail_follower.h>

Inheritance diagram for RailFollower< T >:

Public Member Functions
	RailFollower (const LaneDirection &initial_lane_direction)
	The constructor. More...
	RailFollower (const LaneDirection &initial_lane_direction, const RailFollowerState< T > &initial_context_state, const RailFollowerParams< T > &initial_context_parameters)
	Constructor that initialises all variables in the system that will be placed on the context. More...
RailFollowerParams< T > &	get_mutable_parameters (drake::systems::Context< T > *context) const
	Returns a mutable reference to the parameters in the given context. More...
const drake::systems::InputPort< T > &	command_input () const
	Getter methods for input and output ports. More...
const drake::systems::OutputPort< T > &	state_output () const
const drake::systems::OutputPort< T > &	simple_car_state_output () const
const drake::systems::OutputPort< T > &	lane_state_output () const
const drake::systems::OutputPort< T > &	pose_output () const
const drake::systems::OutputPort< T > &	velocity_output () const

Static Public Attributes
static constexpr double	kLaneEndEpsilon {1e-12}
	Defines a distance that is "close enough" to the end of a lane for the modelled entity to transition to an ongoing branch. More...
static constexpr double	kTimeEpsilon {1e-12}
	Defines a time interval that is used to ensure a desired update time is always greater than (i.e., after) the current time. More...

Constructor & Destructor Documentation

RailFollower() [1/2]

RailFollower ( const LaneDirection &  initial_lane_direction )

explicit

The constructor.

Parameters

initial_lane_direction

The initial lane and direction of travel.

RailFollower() [2/2]

RailFollower	(	const LaneDirection &	initial_lane_direction,
		const RailFollowerState< T > &	initial_context_state,
		const RailFollowerParams< T > &	initial_context_parameters
	)

Constructor that initialises all variables in the system that will be placed on the context.

This includes the continuous state, parameters and non-continuous state variables.

Parameters

[in]	initial_lane_direction	The initial lane and direction of travel.
[in]	initial_context_state	The continuous state variables
[in]	initial_context_parameters	The parameters

Member Function Documentation

command_input()

const drake::systems::InputPort< T > & command_input

Getter methods for input and output ports.

get_mutable_parameters()

RailFollowerParams< T > & get_mutable_parameters

(

drake::systems::Context< T > *

context

)

const

Returns a mutable reference to the parameters in the given context.

lane_state_output()

const drake::systems::OutputPort< T > & lane_state_output

pose_output()

const drake::systems::OutputPort< T > & pose_output

simple_car_state_output()

const drake::systems::OutputPort< T > & simple_car_state_output

state_output()

const drake::systems::OutputPort< T > & state_output

velocity_output()

const drake::systems::OutputPort< T > & velocity_output

Member Data Documentation

kLaneEndEpsilon

constexpr double kLaneEndEpsilon {1e-12}

staticconstexpr

Defines a distance that is "close enough" to the end of a lane for the modelled entity to transition to an ongoing branch.

The primary constraint on the selection of this variable is the application's degree of sensitivity to position state discontinuity when the modelled entity "jumps" from its current lane to a lane in an ongoing branch. A smaller value results in a smaller spatial discontinuity. If this value is zero, the spatial discontinuity will be zero. However, it will trigger the use of kTimeEpsilon, which results in a temporal discontinuity.

kTimeEpsilon

constexpr double kTimeEpsilon {1e-12}

staticconstexpr

Defines a time interval that is used to ensure a desired update time is always greater than (i.e., after) the current time.

Despite the spatial window provided by kLaneEndEpsilon, it is still possible for the vehicle to end up precisely at the end of its current lane (e.g., it could be initialized in this state). In this scenario, the next update time will be equal to the current time. The integrator, however, requires that the next update time be strictly after the current time, which is when this constant is used. The primary constraint on the selection of this constant is the application's sensitivity to the modelled entity being "late" in its transition to an ongoing branch once it is at the end of its current lane. The smaller this value, the less "late" the transition will occur. This value cannot be zero since that will violate the integrator's need for the next update time to be strictly after the current time.

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

• rail_follower.h
• rail_follower.cc