urdf-loader

javascript urdf-loader

Utilities for loading URDF files into THREE.js and a Web Component that loads and renders the model.

Demo here!

Use

<script src=".../URDFLoader.js"></script>
<script>
  const manager = new THREE.LoadingManager();
  const loader = new URDFLoader(manager);
  loader.load(
    'T12/urdf/T12.URDF',                    // The path to the URDF within the package OR absolute
    robot => { },                           // The robot is loaded!
    {
        packages:     {
            packageName : '.../package/dir/'            // The equivalent of a (list of) ROS package(s):// directory
        },
        loadMeshCb: (path, manager, done) => { },       // Callback for each mesh for custom mesh processing and loading code
    }
   );
</script>

Limitations

• Only prismatic, continuous, revolute, and fixed joints are supported.
• Collision tags are not parsed.

URDFLoader API

constructor(manager)

Constructor

manager : THREE.LoadingManager

THREE.LoadingManager. Used for transforming load URLs.

load(urdfpath, onComplete, options)

Loads and builds the specified URDF robot in THREE.js

urdfpath : String

required

The path to the URDF file relative to the specified package directory.

onComplete(robot) : Function

required

Callback that is called once the urdf robots have been loaded. The loaded robot is passed to the function.

See URDFRobot documentation.

options : Object

optional

options.packages : String | Object

The path representing the package:// directory(s) to load package:// relative files.

If the argument is a string, then it is used to replace the package:// prefix when loading geometry.

To specify multiple packages an object syntax is used defining the package name to the package path:

{
  "package1": ".../path/to/package1",
  "package2": ".../path/to/package2",
  ...
}

options.loadMeshCb(pathToModel, manager, onComplete) : Function

An optional function that can be used to override the default mesh loading functionality. The default loader is specified at URDFLoader.defaultMeshLoader.

pathToModel is the url to load the model from.

manager is the THREE.js LoadingManager used by the URDFLoader.

onComplete is called with the mesh once the geometry has been loaded.

options.fetchOptions : Object

An optional object with the set of options to pass to the fetch function call used to load the URDF file.

workingPath : String

The path to load geometry relative to.

Defaults to the path relative to the loaded URDF file.

parse(urdfContent, options) : THREE.Object3D

Parses URDF content and returns the robot model.

urdfContent : String

required

The xml content of a URDF file.

onComplete(robot) : Function

optional

Called immediately with the generated robot. This is the same object that is returned from the function.

Note that the link geometry will not necessarily have finished being processed when this is called.

See URDFRobot documentation.

options : Object

See load.

URDFJoint : THREE.Object3D

An object representing a robot joint.

name : String

The name of the joint.

jointType : String

The type of joint. Can only be the URDF types of joints.

limit : Object

An object containing the lower and upper constraints for the joint.

axis : THREE.Vector3

The axis described for the joint.

angle : Number

readonly

The current position or angle for joint.

ignoreLimits : Boolean

Whether or not to ignore the joint limits when setting a the joint position.

setAngle(angle) | setOffset(position)

angle | position : Number

The position off of the starting position to rotate or move the joint to.

URDFLink : THREE.Object3D

name

The name of the link.

URDFRobot : URDFLink

Object that describes the URDF Robot.

robotName : String

The name of the robot described in the <robot> tag.

links : Object

A dictionary of linkName : URDFLink with all links in the robot.

joints : Object

A dictionary of jointName : URDFJoint with all joints in the robot.

urdf-viewer Element

<!-- Register the Element -->
<script href=".../urdf-viewer-element.js" />
<script>customElements.define('urdf-viewer', URDFViewer)</script>

<body>
  <urdf-viewer package=".../package/dir/" urdf="T12/urdf/T12.URDF" up="Z+" display-shadow ambient-color="red"></urdf-viewer>
</body>

Attributes

package

Corresponds to the package parameter in URDFLoader.load. Supported are:

1. Single package:

   <!-- 1. Example for single package named `default_package` -->
   <urdf-viewer package=".../path/to/default_package" ...></urdf-viewer>
   

   Fallback within 1: If the target package within the package:// relative files do not match the default path it is assumed that the default path is the parent folder that contains the target package(s).

   <!-- 1. Example for single package named `default_package` with fallback: -->
   <urdf-viewer package=".../path/to/parent" ...></urdf-viewer>
   <!-- since `parent` does not match `default_package`
        the path ".../path/to/parent/default_package" is assumed -->
   

2. Serialized package map:

   E.g. if the meshes of a URDF are distributed over mutliple packages.

   <!-- 2. Example for serialized package map that contains `package1` and `package2` -->
   <urdf-viewer package="package1:.../path/to/package1, package2:.../path/to/package1" ...></urdf-viewer>
   

urdf

Corresponds to the urdfpath parameter in URDFLoader.load.

The element uses fetch options { mode: 'cors', credentials: 'same-origin' } to load the urdf file.

ignore-limits

Whether or not hte display should ignore the joint limits specified in the model when updating angles.

up

The axis to associate with "up" in THREE.js. Values can be [+-][XYZ].

display-shadow

Whether or not the render the shadow under the robot.

ambient-color

The color of the ambient light specified with css colors.

auto-redraw

Automatically redraw the model every frame instead of waiting to be dirtied.

no-auto-recenter

Recenter the camera only after loading the model.

Properties

All of the above attributes have corresponding camel case properties.

angles

Sets or gets the angles of the robot as a dictionary of joint-name to radian pairs.

Functions

setAngle(jointName, angle)

Sets the given joint to the provided angle in radians.

setAngles(jointDictionary)

Sets all joint names specified as keys to radian angle value.

redraw()

Dirty the renderer so the element will redraw next frame.

recenter()

Recenter the camera to the model and redraw.

Events

'urdf-change'

Fires when the URDF has changed and a new one is starting to load.

'ignore-limits-change'

Fires when the ignore-limits attribute changes.

'urdf-processed'

Fires when the URDF has finished loading and getting processed.

'geometry-loaded'

Fires when all the geometry has been fully loaded.

Running the Example

Install Node.js and NPM.

Run npm install.

Run npm start.

Visit localhost:9080/javascript/example/ to view the page.

LICENSE

The software is available under the Apache V2.0 license.

Copyright © 2018 California Institute of Technology. ALL RIGHTS RESERVED. United States Government Sponsorship Acknowledged. Any commercial use must be negotiated with with Office of Technology Transfer at the California Institute of Technology. This software may be subject to U.S. export control laws. By accepting this software, the user agrees to comply with all applicable U.S. export laws and regulations. User has the responsibility to obtain export licenses, or other export authority as may be required before exporting such information to foreign countries or providing access to foreign persons. Neither the name of Caltech nor its operating division, the Jet Propulsion Laboratory, nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.