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Communication through head movements

Communication through head movements

Juha Pieviläinenjuha.pievilainen@iki.fi

Alternative communication & access to information seminar 2003

Department of Computer Sciences

University of Tampere

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• Software

Content

• Tracking technologies

• Introduction

• Devices

• References

• Interaction style

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Introduction

”Computer users who cannot use a conventional hand-operated computer mouse and/or keyboard, may use a head operated mouse or keyboard in order to control their computer and, by using an on-screen keyboard, to type information.”

[5] A Head Operated Joystick – Experience with use, G. Evans and P. Blenkhorn, CSUN 99, available at

http://www.csun.edu/cod/conf/1999/proceedings/session0019.htm

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Introduction

Navigating virtual environments and more often playing games require a way to control field of vision. Keyboards, mice and joysticks might do the job, but they really are NOT natural way to change ones field of vision, turning ones head is.

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Tracking technologies

• mechanical• magnetic• sourceless, non-inertial• optical• acoustic (ultrasound)• inertial

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Technologies - mechanical

Description Strengths WeaknessesMeasure change in position by physically connecting the remote object to a point of reference with jointed linkages

Accurate

Low lag

No line of sight or magnetic interference problems

Good for tracking small volumes accurately

Intuitive, due to tethering

Subject to mechanical part wear-out

[2] Review of Virtual Environment Interface Technology, C. Youngblut, R.E. Johnson, et al., Institute for Defence Analyses, available at http://www.hitl.washington.edu/scivw/scivw-ftp/publications/IDA-pdf/

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Technologies - magnetic

Description Strengths WeaknessesUse sets of coils (in a transmitter) that are pulsed to produve magnetic fields. Magnetic sensors (in receiver) determine the strenght and angles of the fields. Pulsed magnetic field may be AC or DC

Inexpencive

Accurate

No line of sight problems

Good noise immunity

Map whole body motion

Large ranges – size of small room

Ferromagnetic and/or metal conductive surfaces cause field distortion. Electromagnetic interference from radios.

Accurace diminishes with distance

High latencies due to filtering

[2] Review of Virtual Environment Interface Technology, C. Youngblut, R.E. Johnson, et al., Institute for Defence Analyses, available at http://www.hitl.washington.edu/scivw/scivw-ftp/publications/IDA-pdf/

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Technologies – sourceless, non-inertial

Description Strengths WeaknessesUse passive magnetic sensors, referenced to the earth’s magnetic field, to provide measurement of roll, pitch, and yaw, and as a derivative, angular acceleration and velocity

Inexpensive

Transmitter not necessary

Portable

Only 3 DOF

Difficult to mark movement between magnetic hemispheres

[2] Review of Virtual Environment Interface Technology, C. Youngblut, R.E. Johnson, et al., Institute for Defence Analyses, available at http://www.hitl.washington.edu/scivw/scivw-ftp/publications/IDA-pdf/

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Technologies - opticalDescription Strengths Weaknesses

Use a variety of detectors, from ordinary video cameras to LEDs, to detect either ambient light or light emitted under control of the position tracker. Infrared light is often used to prevent interference with other activities

High availability

Can work over large area

Fast

No magnetic interference problems

High accuracy

Line of sight necessary

Limited by intensity and coherence of light sources

Weight

Expensive

[2] Review of Virtual Environment Interface Technology, C. Youngblut, R.E. Johnson, et al., Institute for Defence Analyses, available at http://www.hitl.washington.edu/scivw/scivw-ftp/publications/IDA-pdf/

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Technologies – acoustic (ultrasound)

Description Strengths WeaknessesUse three microphones and three emitters to compute the distance between a source and receiver via triangulation. use ultrasonic frequencies (above 20 kHz) so that the emitters will not be heard

Inexpensive

No magnetic interference problems

Lightweight

Ultrasonic noise interference

Low accuracy since speed of sound in air varies with environmental conditions

Echoes cause reception of ”ghost” pulses

Line of sight necessary

[2] Review of Virtual Environment Interface Technology, C. Youngblut, R.E. Johnson, et al., Institute for Defence Analyses, available at http://www.hitl.washington.edu/scivw/scivw-ftp/publications/IDA-pdf/

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Technologies - intertial

Description Strengths WeaknessesUse accelerometers and gyroscopes. Orientation of the object is computed by jointly intergrating the outputs of the rate gyros whose outputs are proportional to angular velocity about each axis. Changes in position can be computed by double intergrating the outputs of the accelerometers using their known orientation

Unlimited range

Fast

No line of sight problems

No magnetic interference problems

Senses orientation directly

Small size

Low cost

Only 3 DOF

Drift

No accurate for slow position changes

[2] Review of Virtual Environment Interface Technology, C. Youngblut, R.E. Johnson, et al., Institute for Defence Analyses, available at http://www.hitl.washington.edu/scivw/scivw-ftp/publications/IDA-pdf/

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Technologies - StatusMechanical Inertial Acoustic

Military uses

Situations when low cost system needed

Poor static accuracy problems need to be solved

Commercial products are available

Optical MagneticMature technology

Military versions in-use

Mature technology

Military versions in-use

Need accuracy improvement before implementation of HUD makes sense

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Interaction style

Absolute pointing vs. relative pointing

similar to mouse similar to joystick

[5] A Head Operated Joystick – Experience with use, G. Evans and P. Blenkhorn, CSUN 99, available at

http://www.csun.edu/cod/conf/1999/proceedings/session0019.htm

require good head control skills

less precise control needed

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Devices – Tracker 2000

• optical head tracker• choice between

mouse and joystick mode

• 8 directions• different button types

available, physical buttons, sip/puff straw or optical switch

[1] 100 % Hands-free Computer Access – Madentec’s 2000 series, R. Marsden, P.Eng., Madentec Limited, available at http://www.madentec.com/products/comaccess/2000/whitepaper.html

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Devices – ADL-1

• mechanical head tracker

• serial connection• cost around 1200 $

[2] Review of Virtual Environment Interface Technology, C. Youngblut, R.E. Johnson, et al., Institute for Defence Analyses, available at http://www.hitl.washington.edu/scivw/scivw-ftp/publications/IDA-pdf/

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Devices – Smart-Nav

• optical head tracker• replaces mouse• price ranging

between 129 to 299 $

[3] Eye Control Technologies, Inc. webpage at http://www.naturalpoint.com

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Software – SymbolCreator

• at the moment on experimental status

• typing by selecting icons

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Software – SoftType• Text entry into all standard Windows applications • Clicking done by dwell selection • Different keyboard layouts available • Word prediction

[6] Origin Instruments Corporation webpage at http://orin.com/index.htm

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Software – SoftType

[6] Origin Instruments Corporation webpage at http://orin.com/index.htm

A more simple layout for kids

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Software – SoftType

[6] Origin Instruments Corporation webpage at http://orin.com/index.htm

Qwerty Layout with integrated Dragger toolbar and Word Prediction.

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References1. 100 % Hands-free Computer Access – Madentec’s 2000 series, R. Marsden, P.Eng., Madentec

Limited, available at http://www.madentec.com/products/comaccess/2000/whitepaper.html

2. Review of Virtual Environment Interface Technology, C. Youngblut, R.E. Johnson, et al., Institute for Defence Analyses, available at http://www.hitl.washington.edu/scivw/scivw-ftp/publications/IDA-pdf/

3. Eye Control Technologies, Inc. webpage at http://www.naturalpoint.com

4. Hands-free navigation in VR environments by teacking the head, S.B. Kang, CRL 97/1Technical Report Series, available at http://www.hpl.hp.com/techreports/Compaq-DEC/CRL-97-1.pdf

5. A Head Operated Joystick – Experience with use, G. Evans and P. Blenkhorn, CSUN 99, available at http://www.csun.edu/cod/conf/1999/proceedings/session0019.htm

6. Origin Instruments Corporation webpage at http://orin.com/index.htm

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THE END