Predefined Paths

There are several predefined paths that can be provided as a demand path for Altair Driver.

CONSTANT RADIUS

[FEEDFORWARD_STEERING]
TAG = 'FEEDFORWARD'
LOOK_AHEAD_TIME = 0.5
PATH = 'PREDEFINED' 
BLOCK = ‘PATH'
INTEGRATION_STEP_SIZE = 0.01 

[PATH]
TYPE = 'CONSTANT_RADIUS'
RADIUS = 40
INITIAL_STRAIGHT = 10
ENTRY_ANGLE = 0.39
The vehicle follows the path as shown in the figure below:
Figure 1.


[CONSTANT RADIUS]
TYPE Attr - string REQUIRED

<CONSTANT_RADIUS>

RADIUS Attr - real REQUIRED

Radius of the circle.

INITIAL_STRAIGHT Attr - real REQUIRED

Length of the initial straight before entering the turn.

TURN Attr - string OPTIONAL
LEFT
Vehicle turns to the left.
RIGHT (Default)
Vehicle turns to the right.
ENTRY_ANGLE Attr - real OPTIONAL

If provided, a transient length is added after the straight where the curvature is increased linearly to the final curvature before entering the constant radius path.

Entry angle defines the angle with respect to the straight section at which the vehicle enters into the Constant Radius path. The greater the entry angle, the longer the transient section.

SLALOM

[FEEDFORWARD_STEERING]
TAG = 'FEEDFORWARD'
LOOK_AHEAD_TIME = 0.5
PATH = 'PREDEFINED' 
BLOCK = ‘PATH'
INTEGRATION_STEP_SIZE = 0.01

[PATH]
TYPE = 'SLALOM'
NUMBER_OF_CONES = 3
DESIRED_CG_LATERAL_DISP = 3
CONE_SPACING = 50
RECOVERY_LENGTH = 20
INITIAL_STRAIGHT = 20
Figure 2.


[SLALOM]
TYPE Attr - String REQUIRED

<SLALOM>

NUMBER_OF_CONES Attr - int REQUIRED

Number of cones.

DESIRED_CG_LATERAL_DISP Attr - real REQUIRED

Desired CG lateral displacement.

CONE_SPACING Attr - real REQUIRED

Distance between adjacent cones.

INITIAL_STRAIGHT Attr - real REQUIRED

Straight section before entering slalom.

RECOVERY_LENGTH Attr - real REQUIRED

Straight section after completing slalom.

ATTACK_DIRECTION Attr - String OPTIONAL
  • First cone if attacked from the specified direction.
  • Default is RIGHT.

SINGLE LANE CHANGE

[FEEDFORWARD_STEERING]
TAG = 'FEEDFORWARD'
LOOK_AHEAD_TIME = 0.5
PATH = 'PREDEFINED' 
BLOCK = 'PATH'
INTEGRATION_STEP_SIZE = 0.01 

[PATH]
TYPE = 'SLC'
LATERAL_OFFSET = 3
SECTION_1 = 20
SECTION_2 = 20
SECTION_3 = 50
TURN_DIRECTION = 'LEFT'
ENTRY_ANGLE = 0.04963         
MAX_CURVATURE = 1.42857e-02         
Figure 3.


[SINGLE LANE CHANGE]
TYPE Attr - String REQUIRED

<SLC>

LATERAL_OFFSET Attr - int REQUIRED

Lateral distance between two lanes.

SECTION_1 Attr - real REQUIRED

First lane distance in longitudinal direction.

SECTION_2 Attr - real REQUIRED

Distance between lanes in longitudinal direction.

SECTION_3 Attr - real REQUIRED

Second lane distance in longitudinal direction.

TURN_DIRECTION Attr - real OPTIONAL
LEFT
Vehicle turns to the left.
RIGHT
(Default) Vehicle turns to the right.
ENTRY_ANGLE Attr - real OPTIONAL

If provided, it enables path easements around the lane corners.

ENTRY_ANGLE is the angle with respect to straight lane section at which path easement section goes to maximum curvature and continues before reducing the curvature to zero on next lane.

Used for first and second lane corners.
MAX_CURVATURE Attr - real

OPTIONAL

If provided, it enables path easements around the lane corners.

MAX_CURVATURE is the maximum curvature of the path easement section at the lane corners.

Used for first and second lane corners.

DOUBLE LANE CHANGE

[FEEDFORWARD_STEERING]
TAG = 'FEEDFORWARD'
LOOK_AHEAD_TIME = 0.5
PATH = 'PREDEFINED' 
BLOCK = ‘PATH'
INTEGRATION_STEP_SIZE = 0.01 
[PATH]
TYPE = 'DLC'
SECTION_1 = 20
SECTION_2 = 20
SECTION_3 = 20
SECTION_4 = 20
SECTION_5 = 50
TURN_DIRECTION = 'LEFT'
ENTRY_ANGLE_1 = 0.04963         
MAX_CURVATURE_1 = 1.42857e-02         
ENTRY_ANGLE_2 = 0.04963         
MAX_CURVATURE_2 = 1.42857e-02     
Figure 4.


[DOUBLE LANE CHANGE]
TYPE Attr - String REQUIRED

<DLC>

LATERAL_OFFSET Attr - int REQUIRED

Lateral distance between two lanes.

SECTION_1 Attr - real REQUIRED

First lane distance in longitudinal direction.

SECTION_2 Attr - real REQUIRED

Distance between first and second lane in longitudinal direction.

SECTION_3 Attr - real REQUIRED

Second lane distance in longitudinal direction.

SECTION_4 Attr - real REQUIRED

Distance between second and third lane in longitudinal direction.

SECTION_5 Attr - real REQUIRED

Third lane distance in longitudinal direction.

TURN_DIRECTION Attr - real OPTIONAL
LEFT
Vehicle turns to the left.
RIGHT
(Default) Vehicle turns to the right.
ENTRY_ANGLE_1 Attr - real OPTIONAL

If provided, it enables path easements around the lane corners.

ENTRY_ANGLE_1 is the angle with respect to straight lane section at which the path easement section goes to maximum curvature and continues before reducing the curvature to zero on next lane.

Used for first and second lane corners.
MAX_CURVATURE_1 Attr - real

OPTIONAL

If provided, it enables path easements around the lane corners.

MAX_CURVATURE_1 is the maximum curvature of the path easement section at the lane corners.

Used for first and second lane corners.
ENTRY_ANGLE_2 Attr - real OPTIONAL

If provided, it enables path easements around the lane corners.

ENTRY_ANGLE_2 is the angle with respect to straight lane section at which the path easement section goes to maximum curvature and continues before reducing the curvature to zero on next lane.

Used for third and fourth lane corners.
MAX_CURVATURE_2 Attr - real

OPTIONAL

If provided, it enables path easements around the lane corners.

MAX_CURVATURE_2 is the maximum curvature of the path easement section at the lane corners.

Used for third and fourth lane corners.