Valve Index Controllers

Valve Index Controllers
Basic Info
VR/AR	Virtual Reality
Type	VR Controllers
Subtype	Finger Tracking Controllers, SteamVR Controllers
Platform	SteamVR
Creator	Valve Corporation
Developer	Valve
Manufacturer	Valve
Announcement Date	2019
Release Date	June 2019
Price	$279 (pair)
Website	https://www.valvesoftware.com/en/index
Versions	Valve Index Controllers (Knuckles)
Requires	SteamVR Base Station(s), compatible PC VR headset
Predecessor	HTC Vive Controllers
Successor	None announced
System
Operating System	SteamVR
Chipset	Custom controller SoC
CPU	Embedded
GPU	N/A
Storage
Storage	N/A
Memory	N/A
SD Card Slot	No
Display
Display	N/A (controller)
Subpixel Layout	N/A
Peak Brightness	N/A
Resolution	N/A
Pixel Density	N/A
Refresh Rate	N/A
Persistence	N/A
Image
Field of View	N/A
Horizontal FoV	N/A
Vertical FoV	N/A
Average Pixel Density	N/A
Peak Pixel Density	N/A
Foveated Rendering	N/A
Optics
Optics	N/A
Ocularity	N/A
IPD Range	N/A
Adjustable Diopter	N/A
Passthrough	N/A
Tracking
Tracking	SteamVR Tracking 2.0
Tracking Frequency	High-speed
Base Stations	Required (SteamVR Base Stations)
Eye Tracking	N/A
Face Tracking	N/A
Hand Tracking	No (finger tracking)
Body Tracking	N/A
Rotational Tracking	Yes
Positional Tracking	Yes
Update Rate	High-frequency
Tracking Volume	Base station dependent
Play Space	Room-scale
Latency	Low latency
Audio
Audio	N/A
Microphone	N/A
3.5mm Audio Jack	N/A
Camera	N/A
Connectivity
Connectivity	Wireless (to Base Stations)
Ports	USB Type-C (charging)
Wired Video	N/A
Wireless Video	N/A
WiFi	N/A
Bluetooth	N/A
Power	Rechargeable battery
Battery Capacity	Internal
Battery Life	~7 hours
Charge Time	USB-C charging
Device
Dimensions	Ergonomic controller form
Weight	~210g each
Material	Plastic housing with hand strap
Headstrap	N/A
Haptics	Yes (vibration)
Color	Black
Sensors	87 sensors (capacitive, force, IR, optical, IMU)
Input	Buttons, trigger, thumbstick, trackpad, grip force, finger tracking
Compliance	SteamVR compatible

The Valve Index Controllers, commonly known as Knuckles, are a pair of advanced virtual reality controllers developed by Valve Corporation, released in June 2019 alongside the Valve Index headset at $279 for the pair. Distinguished by their revolutionary finger tracking capabilities, the Index Controllers use 87 sensors per controller—combining capacitive touch, force sensors, infrared, optical, and inertial measurement—to track individual finger positions, hand gestures, grip pressure, and throwing motions in real-time. The unique strap design allows users to wear the controllers rather than grip them, enabling natural open-hand interactions like releasing objects, throwing, and making gestures without dropping the controller. Each controller features an A button, B button, system button, analog trigger with finger sensing, thumbstick, trackpad with force sensing, and grip force sensor, all calibrated continuously to match the user's hand size and changing skin capacitance. Compatible with any VR headset supporting SteamVR Tracking (including Valve Index, HTC Vive, and HTC Vive Pro), the controllers offer approximately 7 hours of battery life and represent the gold standard for VR input fidelity. The finger tracking enables deeper immersion through a wide range of gestures and expressions, from pointing and waving to making a fist or giving a thumbs-up, fundamentally changing how users interact in virtual environments.

History and Development

Valve VR Origins

Company background:

Valve + HTC partnership
Original Vive development
SteamVR ecosystem
VR platform investment

Knuckles Development

Controller evolution:

Prototype development
"Knuckles" codename
Developer feedback
Iterative design

June 2019 Release

Commercial launch:

Valve Index bundle
Standalone availability
$279 pair price
Global availability

SteamVR Standard

Platform position:

Premium VR controllers
Finger tracking pioneer
SteamVR ecosystem
Third-party headset compatible

Design Philosophy

Finger Tracking Priority

Input innovation:

Individual finger detection
Gesture recognition
Natural interaction
Expressive capability

Worn Not Held

Strap design:

Hand strap system
Open hand capability
No grip required
Natural release/throw

Comprehensive Sensing

Multi-sensor approach:

87 sensors per controller
Multiple sensing methods
High accuracy
Continuous calibration

Ergonomic Comfort

Extended use design:

Adjustable straps
Hand relaxation
Comfortable weight
Long session ready

Sensor Technology

87 Sensors Per Controller

Sensor count:

Total: 87 sensors each
Multiple sensor types
Comprehensive coverage
Redundant detection

Capacitive Sensors

Touch detection:

Finger proximity sensing
Grip area coverage
Before-contact detection
Capacitance measurement

Force Sensors

Pressure detection:

Grip force measurement
Trackpad force sensing
Pressure sensitivity
Intent determination

Infrared Sensors

Non-contact sensing:

Trigger finger detection
Pre-contact sensing
Proximity awareness
Fine tracking

Optical Sensors

Visual tracking:

SteamVR tracking
Motion detection
Velocity calculation
Base station communication

IMU

Motion sensing:

Accelerometer
Gyroscope
Orientation tracking
Movement detection

Finger Tracking

Five-Finger Detection

Individual tracking:

Thumb position
Index finger position
Middle finger detection
Ring finger detection
Pinky finger detection

Tracking Methods

Detection approach:

Grip area: Capacitive sensors (3 fingers)
Trigger: IR + capacitive (index)
Thumbstick/Trackpad: Capacitive (thumb)
Multiple data sources

Continuous Calibration

Adaptation:

Real-time hand size adjustment
Skin capacitance compensation
User-specific tuning
Automatic optimization

Gesture Recognition

Expression capability:

Pointing
Thumbs up/down
Fist
Open hand
Wave
Peace sign
Custom gestures

Hand Strap System

Three-Point Adjustment

Fit customization:

Strap length adjustment
Tension adjustment
Angle adjustment
Wide hand range

Open Hand Capability

Release interaction:

Full hand opening
Object release
Throwing motion
Natural gestures

Comfort Design

Extended wear:

Hand relaxation
Reduced fatigue
Secure fit
Break-friendly

Input Controls

Buttons

Button inputs:

A Button: Primary action
B Button: Secondary action
System Button: Menu/dashboard
Traditional input

Analog Trigger

Trigger features:

Full analog range
Finger presence detection
Hair trigger sensitivity
Force sensing

Thumbstick

Stick input:

Full analog control
Click input
Directional control
Standard VR input

Trackpad

Touch surface:

Touch-sensitive pad
Force sensing
Click input
Swipe gestures

Grip Force

Squeeze detection:

Variable grip pressure
Force measurement
Object interaction
Squeeze gestures

SteamVR Tracking

Tracking System

Position detection:

SteamVR Tracking 2.0 compatible
SteamVR Tracking 1.0 compatible
Lighthouse base stations
Sub-millimeter accuracy

Compatible Base Stations

Tracking hardware:

SteamVR Base Station 2.0
SteamVR Base Station 1.0
HTC Vive Base Stations
Valve Index Base Stations

Headset Compatibility

Valve Index

Primary pairing:

Native compatibility
Optimal experience
Bundle option
Designed together

HTC Vive

Original Vive:

Full compatibility
Upgrade path
Base station sharing
Enhanced input

HTC Vive Pro

Pro series:

Full compatibility
Premium pairing
Professional use
Enterprise compatible

Other SteamVR Headsets

Extended compatibility:

Any SteamVR Tracking headset
Pimax headsets
Third-party support
Open ecosystem

Battery

Battery Life

Power specifications:

Runtime: ~7 hours
Extended gaming
Session-friendly
Rechargeable

Charging

Power management:

USB Type-C
Fast charging
Both controllers simultaneously
Convenient refueling

Physical Specifications

Weight

Controller mass:

Weight: ~210g each
Comfortable wear
Balanced design
Extended sessions

Ergonomics

Comfort design:

Contoured grip
Natural hand position
Strap support
Fatigue reduction

Software Support

SteamVR Integration

Platform support:

Native SteamVR
Finger tracking API
Skeletal input
Developer access

Game Compatibility

Software support:

Index-native titles
Legacy Vive controller emulation
Growing library
Developer adoption

Skeletal Input API

Finger data:

Per-finger position
Curl values
Splay values
Developer access

Comparison with VR Controllers

Feature	Valve Index	Quest Touch Pro	Vive Controllers	PS VR2 Sense
Finger Tracking	Yes (5 fingers)	Limited	No	Finger touch sensing
Sensors	87	Multiple	Limited	Capacitive + haptic
Grip Force	Yes	No	No	Adaptive triggers
Hand Strap	Yes (worn)	No (held)	No (held)	No (held)
Tracking	SteamVR	Inside-out	SteamVR	Inside-out
Trackpad	Yes	No	Yes	No
Battery	~7 hours	~7 hours	~6 hours	~7 hours
Price	$279 pair	$299 pair	$130 pair	$549 (with headset)

Strengths and Limitations

Strengths

87 sensors per controller (industry-leading)
Individual 5-finger tracking
Worn design (open hand capability)
Grip force sensing
Throwing motion detection
Continuous auto-calibration
SteamVR Tracking precision
~7 hours battery life
Trackpad + thumbstick (dual input)
Cross-headset compatibility (SteamVR)
Ergonomic strap system

Limitations

$279 premium price
Requires Base Station(s)
Not standalone compatible
PC VR only
SteamVR ecosystem dependent
Strap adjustment learning curve
Some durability concerns (thumbstick drift reports)
Hand strap fit varies by user
Not compatible with inside-out tracking headsets

Technical Specifications Summary

Specification	Details
Type	Finger tracking VR controllers
Sensors	87 per controller
Finger Tracking	5-finger individual tracking
Inputs	A, B, System, Trigger, Thumbstick, Trackpad, Grip
Force Sensing	Grip and trackpad
Tracking	SteamVR Tracking 1.0/2.0
Battery Life	~7 hours
Weight	~210g each
Charging	USB Type-C
Compatibility	Valve Index, HTC Vive, Vive Pro, SteamVR headsets
Price	$279 (pair)

References