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

Loading a URDF file from a server.

import { LoadingManager } from 'three';
import URDFLoader from 'urdf-loader';

const manager = new LoadingManager();
const loader = new URDFLoader(manager);
loader.packages = {
    packageName : './package/dir/'            // The equivalent of a (list of) ROS package(s):// directory
};
loader.loadMeshCb = (path, manager, done) => { };
loader.load(
  'T12/urdf/T12.URDF',                    // The path to the URDF within the package OR absolute
  robot => { }                            // The robot is loaded!
);

Using XacroParser to process a Xacro URDF file and then parse it.

import { LoaderUtils } from 'three';
import { XacroLoader } from 'xacro-parser';
import URDFLoader from 'urdf-loader';

const url = './path/to/file.xacro';
const xacroLoader = new XacroLoader();
xacroLoader.load( url, xml => {

    const urdfLoader = new URDFLoader();
    urdfLoader.workingPath = LoaderUtils.extractUrlBase( url );
    
    const robot = urdfLoader.parse( xml );

    // robot is loaded!

} );

Limitations

• Only prismatic, continuous, revolute, and fixed joints are supported.

API

URDFOptions

List of options available on the URDFLoader class.

.packages

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",
  ...
}

.loadMeshCb

loadMeshCb = null :
    (
        pathToModel : string,
        manager : LoadingManager,
        onComplete : ( obj : Object3D ) => void
    ) => void

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.

.fetchOptions

fetchOptions = null : Object

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

.workingPath

workingPath = '' : string

The path to load geometry relative to.

Defaults to the path relative to the loaded URDF file.

.parseVisual

parseVisual = true : boolean

An optional value that can be used to enable / disable loading meshes for links from the visual nodes. Defaults to true.

.parseCollision

parseCollision = false : boolean

An optional value that can be used to enable / disable loading meshes for links from the collision nodes. Defaults to false.

URDFLoader

.constructor

constructor( manager : LoadingManager )

Constructor. Manager is used for transforming load URLs and tracking downloads.

.load

load(
    urdfpath : string,
    onComplete : (robot : URDFRobot) => void,
    onProgress? : () => void,
    onError? : (error : Error) => void
) : void

Loads and builds the specified URDF robot in THREE.js.

Takes a path to load the urdf file from, a func to call when the robot has loaded, and a set of options.

.parse

parse( urdfContent : string | Document | Element ) : URDFRobot

Parses URDF content and returns the robot model. Takes an XML string to parse and a set of options.

If the XML document has already been parsed using DOMParser then either the returned Document or root Element can be passed into this function in place of the string, as well.

Note that geometry will not necessarily be loaded when the robot is returned.

URDFJoint

extends Object3D

An object representing a robot joint.

.name

name : string

The name of the joint.

.jointType

.jointType : string

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

.limit

.limit : { lower : number, upper : number }

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

.axis

axis : Vector3

The axis described for the joint.

.angle

readonly

angle : number

The current position or angle for joint.

.ignoreLimits

ignoreLimits : boolean

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

.setAngle, .setOffset

setAngle( angle : number ) : void
setOffset( position : number ) : void

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

URDFLink

extends Object3D

.name

name : string

The name of the link.

URDFRobot

extends URDFLink

Object that describes the URDF Robot.

.robotName

robotName : string

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

.links

links : { [key] : URDFLink }

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

.joints

joints : { [key] : URDFJoint }

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

urdf-viewer Element

<!-- Register the Element -->
<script href=".../urdf-viewer-element.js"></script>
<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

angles : Object

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

Functions

setAngle

setAngle( jointName : string, angle : Number ) : void

Sets the given joint to the provided angle in radians.

.setAngles

setAngles( jointDictionary : Object ) : void

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

.redraw

redraw() : void

Dirty the renderer so the element will redraw next frame.

.recenter

recenter() : void

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 © 2019 California Institute of Technology. ALL RIGHTS RESERVED. United States Government Sponsorship Acknowledged. 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.