see also the Haptic Feedback topic

• haptics community: http://haptic.mech.nwu.edu
• Eurohaptics http://www.eurohaptics.org
• Journal http://www.haptics-e.org
• Haptics symposia http://www.vr2002.org
• Design of Haptic Interfaces
• survey, with review of common actuator and sensor technologies
• http://www.cs.ubc.ca/~maclean/publics/uist01-hapticsSurv.pdf
• http://www.cc.gatech.edu/classes/AY2002/cs4470_fall/haptics.pdf
• Physical interfaces course http://www.cs.ubc.ca/~cs532/
• HAPTIC RENDERING: BEYOND VISUAL COMPUTING, Special Issue of IEEE CG&A, March/April 2004
• See http://www.computer.org/cga/CFPMar04.htm
• http://www.hitl.washington.edu/scivw/EVE/I.C.ForceTactile.html

• for generating tactile landscapes, using a 64 x 64 actuator array:
• Helpful info online: http://www.cityarts.com/langlois/teramachine.html

• double handed interaction using both palms
• using linear actuator and DC motors
• http://intron.kz.tsukuba.ac.jp/vrlab_web/feelex/feelex_e.html

• http://robotica.mecc.polimi.it/ricerche_incorso/biorobotica/MIT.htm
• A Shadow robot company project PNEUMATIC INSECT. Interesting and specific demonstration: http://www.shadow.org.uk/projects/zephyrus.shtml
• NASA JPL's Biomimetics website: http://ndeaa.jpl.nasa.gov/nasa-nde/biomimetics/bm-hub.htm
• Constantinos Mavroidis rutgers research group
• http://www1.coe.neu.edu/~mavro/
• http://robots.rutgers.edu/research.htm
• “Force Feedback using Electro-Rheological Fluid Based Compact Actuators”
• “Bio-Nano-Robotic Systems”
• “Advanced Actuators For Robotic Systems”

• robots get sensitive: http://www.bioedonline.org/news/news.cfm?art=1049

• http://www.itacti.com/english/index.htm .
• partnership of groups in UK, Lithuania, Germany, and Italy
• Project has similar aims to Lyta (perhaps less stringent requirements and better funding!).

• “Super Cilia Skin is a multi-modal interactive interface, conceived as a computationally enhanced membrane coupling tactile-kinesthetic input with tactile and visual output. An array of individual actuators (cilia) use changes in orientation to display images or physical gestures as physical or tactile information”: http://tangible.media.mit.edu/projects/Super_Cilia_Skin/Super_Cilia_Skin.htm

• vision based interface measuring both magnitude and direction of force: http://www.start.t.u.-tokyo.ac.jp/~kazuto/

• Biomotor powers propeller: http://www.trnmag.com/Stories/120600/Biomotor_powers_propeller_120600.html

• “The display component of Pins comprises a densely packed array of discrete nodes operating in harmony as a computationally deformable surface.” http://tangible.media.mit.edu/projects/pins/pins.htm
• NIST Pins down imaging system for the blind: http://www.nist.gov/public_affairs/factsheet/visualdisplay.htm

Using pneumatic pistons and springs: http://www.sial.rmit.edu.au/Projects/Aegis_Hyposurface.php

“Behind the façade’s surface, many pneumatic pistons attach to metal plates that form the wall surface. Springs are then attached to both the pistons and the static structural frame, helping to control the location of each piston by providing it with a failsafe means of returning to a known starting point or resting state. By understanding the typical way pneumatic pistons are controlled we can also understand how the wall is actuated by distributing air pressure between two different pneumatic chambers (within the body of a piston) in different combinations to allow the piston to extend, to contract, or alternatively jitter in a mode that enables it to extend and contract very rapidly. A computer was then programmed to fire each piston sequentially in order to produce a series of patterns that responded to environmental stimuli—sound being the particular stimuli used.” Sterk, Tristan d’Estrée

• NASA's Worldwide electroactive polymer actuator webhub: http://ndeaa.jpl.nasa.gov/nasa-nde/lommas/eap/EAP-web.htm
• NASA JPL's Biomimetics website: http://ndeaa.jpl.nasa.gov/nasa-nde/biomimetics/bm-hub.htm

• NASA's Worldwide electroactive polymer actuator webhub: http://ndeaa.jpl.nasa.gov/nasa-nde/lommas/eap/EAP-web.htm

Also see the Active Materials topic

These are based either on near-field ultrasound tracking, as in mimio http://www.mimio.com , or on extremely skewed video acquisition. I had in mind the latter, thinking that it might be possible to use video acquisition, with the touchable surface, say, separated from a coated translucent hard sheet of acrylic or something, so that pressure upon the material causes certain regions of the sheep to appear darker (or lighter) than others. Or, in any case, arranging things such that a pattern of light and dark is what would result from pressure upon the surface.