validatorOccupancyMap

State validator based on 2-D grid map

Description

The validatorOccupancyMap object validates states and discretized motions based on the value in a 2-D occupancy map. If the state location in the map is occupied or unknown, validatorOccupancyMap considers the state invalid. Only free space is considered valid.

Creation

Syntax

Description

validator = validatorOccupancyMap creates a 2-D occupancy map validator associated with an SE2 state space with default settings.

validator = validatorOccupancyMap(stateSpace) creates a validator in the given state space definition derived from nav.StateSpace.

validator = validatorOccupancyMap(stateSpace,Name,Value) specifies the Map or XYIndices properties using Name,Value pair arguments.

Properties

StateSpace — State space for validating states

stateSpaceSE2 (default) | subclass of nav.StateSpace

State space for validating states, specified as a subclass of nav.StateSpace. Provided state space objects include:

• stateSpaceSE2

• stateSpaceDubins

• stateSpaceReedsShepp

Map — Map used for validating states

binaryOccupancyMap(10,10) (default) | binaryOccupancyMap object | occupancyMap object

Map used for validating states, specified as a binaryOccupancyMap or occupancyMap object.

ValidationDistance — Interval for checking state validity

Inf (default) | positive numeric scalar

Interval for sampling between states and checking state validity, specified as a positive numeric scalar.

XYIndices — State variable mapping for xy-coordinates

[1 2] (default) | [xIdx yIdx]

State variable mapping for xy-coordinates in state vector, specified as a two-element vector, [xIdx yIdx]. For example, if a state vector is given as [r p y x y z], the xy-coordinates are [4 5].

Object Functions

copy	Create deep copy of state validator object
isStateValid	Check if state is valid
isMotionValid	Check if path between states is valid

Examples

Validate Path Through Occupancy Map Environment

This example shows how to validate paths through an environment.

Load example maps. Use the simple map to create a binary occupancy map.

load exampleMaps.mat
map = occupancyMap(simpleMap);
show(map)

Specify a coarse path through the map.

path = [2 2 pi/2; 10 15 0; 17 8 -pi/2];
hold on
plot(path(:,1),path(:,2),"--o")

Create a state validator using the stateSpaceSE2 definition. Specify the map and the distance for interpolating and validating path segments.

validator = validatorOccupancyMap(stateSpaceSE2);
validator.Map = map;
validator.ValidationDistance = 0.1;

Check the points of the path are valid states. All three points are in free space, so are considered valid.

isValid = isStateValid(validator,path)

isValid = 3x1 logical array

   1
   1
   1

Check the motion between each sequential path states. The isMotionValid function interpolates along the path between states. If a path segment is invalid, plot the last valid point along the path.

startStates = [path(1,:);path(2,:)];
endStates = [path(2,:);path(3,:)];
    for i = 1:2
        [isPathValid, lastValid] = isMotionValid(validator,startStates(i,:),endStates(i,:));
        if ~isPathValid
            plot(lastValid(1),lastValid(2),'or')
        end
    end
hold off

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

Specify the Map and XYIndices properties when you create the object. For example:

validator = validatorOccupancyMap('Map',occMap,'XYIndices',[4 5])

As of MATLAB^® R2022a, default map behavior during code generation has changed, which may result in backwards compatibility issues. Maps such as validatorOccupancyMap now support fixed-size code generation (DynamicMemoryAllocation="off").

1. Maps that are either default-constructed or constructed with compile-time constant size information (or matrices that are of compile-time constant size) produce fixed-size maps.

2. To restore the previous behavior, use the coder.ignoreConst (MATLAB Coder) function when specifying size inputs, or coder.varsize (MATLAB Coder) matrix variable name specified as a string scalar or character vector, prior to constructing the map.

Version History

Introduced in R2019b