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Update states of ego bodies

Since R2020b



updateEgoPose(capsuleListObj,egoIDs,poseStruct) updates the states of the specified ego bodies in the capsule list. If a specified ego ID does not already exist, the function adds a new ego body with that ID to the list.

status = updateEgoPose(capsuleListObj,egoIDs,poseStruct) returns an indicator of whether an ego body is added, updated, or a duplicate.


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Build an ego body path and maintain obstacle states using the dynamicCapsuleList object. Visualize the states of all objects in the environment at different timestamps. Validate the path of the ego body by checking for collisions with obstacles in the environment.

Create the dynamicCapsuleList object. Extract the maximum number of steps to use as the number of time stamps for your object paths.

obsList = dynamicCapsuleList;
numSteps = obsList.MaxNumSteps;

Add Ego Body

Define an ego body by specifying the ID, geometry, and state together in a structure. The capsule geometry has a length of 3 m and radius of 1 m. Specify the state as a linear path from x = 0m to x = 100m.

egoID1 = 1;
geom = struct("Length",3,"Radius",1,"FixedTransform",eye(3));
states = linspace(0,1,obsList.MaxNumSteps)'.*[100 0 0];

egoCapsule1 = struct('ID',egoID1,'States',states,'Geometry',geom);

ylim([-20 20])

Add Obstacles

Specify states for two obstacles that are separated from the ego body by 5 m in opposite directions on the y-axis.. Assume the obstacles have the same geometry geom as the ego body.

obsState1 = states + [0 5 0];
obsState2 = states + [0 -5 0];

obsCapsule1 = struct('ID',1,'States',obsState1,'Geometry',geom);
obsCapsule2 = struct('ID',2,'States',obsState2,'Geometry',geom);


ylim([-20 20])

Update Obstacles

Alter your obstacle locations and geometry dimensions over time. Use the previously generated structure, modify the fields, and update the obstacles using the updateObstacleGeometry and updateObstaclePose object functions. Reduces the radius of the first obstacle to 0.5 m, and change the path to move it towards the ego body.

obsCapsule1.Geometry.Radius = 0.5;

obsCapsule1.States = ...
    [linspace(0,100,numSteps)' ... % x
     linspace(5,-4,numSteps)' ... % y 
     zeros(numSteps,1)]; % theta


Check for Collisions

Visualize the new paths. Show where collisions between the ego body and an obstacle, which the display highlights in red. Notice that collisions between the obstacles are not checked.

ylim([-20 20])
xlabel("X (m)")
ylabel("Y (m)")

Programmatically check for collisions by using the checkCollision object function. The function returns a vector of logical values that indicates the status of each time step. The vector is transposed for display purposes.

collisions = checkCollision(obsList)'
collisions = 1x31 logical array

   0   0   0   0   0   0   0   0   0   0   0   0   1   1   1   1   1   1   1   1   1   1   0   0   0   0   0   0   0   0   0

To validate paths with a large number of steps, use the any function on the vector of collision values.

if any(collisions)
    disp("Collision detected.")
Collision detected.

Update Ego Path

Specify a new path for the ego body. Visualize the paths again, displaying collisions.

egoCapsule1.States = ...
    [linspace(0,100,numSteps)' ... % x
    3*sin(linspace(0,2*pi,numSteps))' ... % y
    zeros(numSteps,1)]; % theta


ylim([-20 20])

Input Arguments

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Dynamic capsule list, specified as a dynamicCapsuleList or dynamicCapsuleList3D object.

IDs of ego bodies to update, specified as a vector of positive integers.

States for ego bodies, specified as a structure array or structure array, where each structure contains the fields of the structure in the Geometry field of the ego body to be updated. Each element of the structure array contains a matrix of states for each ego body. The state matrix size depends on whether you are using a dynamicCapsuleList or dynamicCapsuleList3D object.

Data Types: struct

Output Arguments

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Result of updating ego bodies, specified as N-element column vector of ones, zeros, and negative ones. N is the number of ego bodies specified in the egoIDs argument. Each value indicates whether the body is updated (1), not found (0), or a duplicate (-1). If you specify the same ego ID multiple times in the egoIDs input argument, then all entries besides the last are marked as a duplicate.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2020b