capsuleApproximation

Approximate collision geometries of rigid body tree with capsules

Since R2022b

Description

The capsuleApproximation object approximates the collision geometries associated with every body of a rigidBodyTree object by fitting collision capsules on each rigid body. This object enables you to query, modify, and visualize the collision capsules associated with rigid bodies of a rigid body tree.

Creation

Syntax

capapprox = capsuleApproximation(robot)

Description

capapprox = capsuleApproximation(robot) creates a capsule approximation capapprox of the input rigid body tree robot.

Input Arguments

robot — Rigid body tree robot model to approximate

rigidBodyTree object

Rigid body tree robot model to approximate with capsules, specified as a rigidBodyTree object. To use a provided robot model, see loadrobot. To import Unified Robot Description Format (URDF) models, see the importrobot function.

Properties

RigidBodyTree — Capsule-approximated rigid body tree robot model

rigidBodyTree object

Capsule-approximated rigid body tree robot model, stored as a rigidBodyTree object.

Object Functions

addCapsule	Add collision capsule to rigid body
removeCapsule	Remove collision capsule from rigid body
getCapsules	Get collision capsules of rigid body
show	Visualize capsule approximation of rigid body tree
updateGeometry	Update geometry of collision capsule of rigid body
updatePose	Update pose of collision capsule of rigid body

Examples

Create Capsule Approximation of Robot Model

Load a robot into the workspace and visualize it.

robot = loadrobot("universalUR16e");
show(robot);

Create a capsule approximation of the robot, and visualize the capsule-approximated robot model.

capsUR16 = capsuleApproximation(robot);
show(capsUR16,homeConfiguration(robot));

Create and Modify Capsule Approximation

Load a robot into the workspace and visualize it.

robotIRB = loadrobot("abbIrb120");
show(robotIRB);

Create a capsule approximation of the robot, and visualize the capsule-approximated robot model.

capsIRB = capsuleApproximation(robotIRB);
figure
show(capsIRB,homeConfiguration(capsIRB.RigidBodyTree));

Use the getCapsules function to see if the end effector, "tool0", has any collision capsules. Because tool0 is just a frame, it has no collision mesh to approximate as a collision capsule.

capsulesTool = getCapsules(capsIRB,"tool0")

capsulesTool =

  1x0 empty cell array

Add a capsule to tool0, at a position 0.15 meters along the x-axis, with a radius of 0.15 and a length of 0.

addCapsule(capsIRB,"tool0",[0.15 0],trvec2tform([0.15 0 0]))
show(capsIRB,homeConfiguration(capsIRB.RigidBodyTree));

Again check tool0 for a collision capsule, and verify the properties of the detected capsule.

capsulesTool = getCapsules(capsIRB,"tool0")

capsulesTool = 1x1 cell array
    {1x1 collisionCapsule}

capsulesTool{1}

ans = 
  collisionCapsule with properties:

    Radius: 0.1500
    Length: 0
      Pose: [4x4 double]

Remove the capsule from the base link. Then, reduce the collision capsule size of tool0, and move it -0.05 meters from the previous position along the x-axis.

removeCapsule(capsIRB,"base_link",1)
updatePose(capsIRB,"tool0",trvec2tform([-0.05 0 0]),1)
updateGeometry(capsIRB,"tool0",[.1 0.01],1)
show(capsIRB,homeConfiguration(capsIRB.RigidBodyTree));

Extended Capabilities

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

Version History

Introduced in R2022b