Gyroscope

Editor’s Draft,

This version:
https://w3c.github.io/gyroscope/
Latest published version:
http://www.w3.org/TR/gyroscope/
Version History:
https://github.com/w3c/gyroscope/commits/gh-pages/index.bs
Feedback:
public-device-apis@w3.org with subject line “[gyroscope] … message topic …” (archives)
Issue Tracking:
GitHub
Editors:
Anssi Kostiainen (Intel Corporation)
Mikhail Pozdnyakov (Intel Corporation)
Bug Reports:
via the w3c/gyroscope repository on GitHub
Test Suite:
web-platform-tests on GitHub

Abstract

This specification defines a concrete sensor interface to monitor the rate of rotation around the device’s local three primary axes.

Status of this document

This is a public copy of the editors’ draft. It is provided for discussion only and may change at any moment. Its publication here does not imply endorsement of its contents by W3C. Don’t cite this document other than as work in progress.

If you wish to make comments regarding this document, please send them to public-device-apis@w3.org (subscribe, archives). When sending e-mail, please put the text “gyroscope” in the subject, preferably like this: “[gyroscope] …summary of comment…”. All comments are welcome.

This document was produced by the Device and Sensors Working Group.

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

This document is governed by the 1 March 2017 W3C Process Document.

1. Introduction

The Gyroscope API extends the Generic Sensor API [GENERIC-SENSOR] to provide information about the angular velocity around the device’s local X, Y and Z axis in terms of radian per seconds units.

2. Examples

let sensor = new Gyroscope();
sensor.start();
    
sensor.onchange = () => {
    console.log("Angular velocity around the X-axis " + sensor.x);
    console.log("Angular velocity around the Y-axis " + sensor.y);
    console.log("Angular velocity around the Z-axis " + sensor.z);
};

sensor.onerror = event => console.log(event.error.name, event.error.message);

3. Security and Privacy Considerations

There are no specific security and privacy considerations beyond those described in the Generic Sensor API [GENERIC-SENSOR].

4. Model

The gyroscope’s associated Sensor subclass is the Gyroscope class.

Gyroscope has a default sensor, which is the device’s main gyroscope sensor.

A latest reading per sensor of gyroscope type includes three entries whose keys are "x", "y", "z" and whose values contain current angular velocity about the corresponding axes.

The angular velocity is the rate at which the device rotates about a specified axis. Its unit is the radian per second (rad/s) [SI].

The sign of the current angular velocity depends on the rotation direction and it must be according to the right-hand convention, such that positive rotation around an axis is clockwise when viewed along the positive direction of the axis (see figure below).

Device’s local coordinate system and rotation.

5. API

5.1. The Gyroscope Interface

[Constructor(optional SensorOptions sensorOptions)]
interface Gyroscope : Sensor {
  readonly attribute unrestricted double? x;
  readonly attribute unrestricted double? y;
  readonly attribute unrestricted double? z;
};

To Construct a Gyroscope Object the user agent must invoke the construct a Sensor object abstract operation.

5.1.1. Gyroscope.x

The x attribute of the Gyroscope interface represents the current angular velocity around X-axis. In other words, this attribute returns latest reading["x"].

5.1.2. Gyroscope.y

The y attribute of the Gyroscope interface represents the current angular velocity around Y-axis. In other words, this attribute returns latest reading["y"].

5.1.3. Gyroscope.z

The z attribute of the Gyroscope interface represents the current angular velocity around Z-axis. In other words, this attribute returns latest reading["z"].

6. Acknowledgements

Tobie Langel for the work on Generic Sensor API.

7. Conformance

Conformance requirements are expressed with a combination of descriptive assertions and RFC 2119 terminology. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this document are to be interpreted as described in RFC 2119. However, for readability, these words do not appear in all uppercase letters in this specification.

All of the text of this specification is normative except sections explicitly marked as non-normative, examples, and notes. [RFC2119]

A conformant user agent must implement all the requirements listed in this specification that are applicable to user agents.

The IDL fragments in this specification must be interpreted as required for conforming IDL fragments, as described in the Web IDL specification. [WEBIDL]

Index

Terms defined by this specification

Terms defined by reference

References

Normative References

[GENERIC-SENSOR]
Tobie Langel; Rick Waldron. Generic Sensor API. URL: https://www.w3.org/TR/generic-sensor/
[INFRA]
Anne van Kesteren; Domenic Denicola. Infra Standard. Living Standard. URL: https://infra.spec.whatwg.org/
[RFC2119]
S. Bradner. Key words for use in RFCs to Indicate Requirement Levels. March 1997. Best Current Practice. URL: https://tools.ietf.org/html/rfc2119
[WEBIDL]
Cameron McCormack; Boris Zbarsky; Tobie Langel. Web IDL. URL: https://www.w3.org/TR/WebIDL-1/

Informative References

[SI]
SI Brochure: The International System of Units (SI), 8th edition. 2014. URL: http://www.bipm.org/en/publications/si-brochure/

IDL Index

[Constructor(optional SensorOptions sensorOptions)]
interface Gyroscope : Sensor {
  readonly attribute unrestricted double? x;
  readonly attribute unrestricted double? y;
  readonly attribute unrestricted double? z;
};