210ENVIRONMENTAL CONTROL

150.Andreadis ST. Gene transfer to epidermal stem cells: Implications for tissue engineering. Expert Opin Biol Ther 2004;4(6):783–800.

151.Cooley J. Follicular cell implantation: An update on hair follicle cloning. Facial Plast Surg Clin North Am 2004; 12(2):219–224.

152.Belkas JS, Shoichet MS, Midha R. Peripheral nerve regeneration through guidance tubes. Neurol Res 2004;26(2):151– 160.

153.Stanec S, Stanec Z. Reconstruction of upper-extremity per- ipheral-nerve injuries with ePTFE conduits. J Reconstr Microsurg 1998;14(4):227–232.

154.Hentz VR, et al. The nerve gap dilemma: A comparison of nerves repaired end to end under tension with nerve grafts in a primate model. J Hand Surg (Am) 1993;18(3):417–425.

155.Fields RD, Le Beau JM, Longo FM, Ellisman MH. Nerve regeneration through artificial tubular implants. Prog Neurobiol 1989;33(2):87–134.

156.Heath CA, Rutkowski GE. The development of bioartificial nerve grafts for peripheral-nerve regeneration. Trends Biotechnol 1998;16(4):163–168.

157.Patrick Jr CW. et al. Muristerone A-induced nerve growth factor release from genetically engineered human dermal fibroblasts for peripheral nerve tissue engineering. Tissue Eng 2001;7(3):303–311.

Reading List

Atala A, Lanza RP. Methods of tissue engineering. San Diego: Academic Press; 2001. p 1285.

Lanza RP, Langer RS, Vacanti J. Principles of tissue engineering. San Diego: Academic Press; 2000. p 995.

Saltzman WM. Tissue engineering: Engineering principles for the design of replacement organs and tissues. Oxford, New York: Oxford University Press; 2004. p 523.

See also BIOMATERIALS: TISSUE ENGINEERING AND SCAFFOLDS; SKIN TISSUE ENGINEERING FOR REGENERATION.

ENVIRONMENTAL CONTROL

DENIS ANSON

College Misericordia

Dallas, Pennsylvania

INTRODUCTION

Electronic aids to daily living (EADLs) are devices that can be used to control electrical devices in the client’s environment (1). Before 1998 (2), these devices were generally known by the shorter term, ‘‘Environmental Control Unit’’ (ECU). Technically, this term should be reserved for furnace thermostats and similar controls. The more generic EADL applies to control of lighting and temperature, but also applies to control of radios, televisions, telephones, and other electrical and electronic devices in the environment of the client (3,4). See Fig. 1.

These systems all contain some method for the user to provide input to the EADL, some means of determining the current state of the device to be controlled (although this is often visual inspection of the device itself, since EADLs are

Figure 1. Components of an EADL system.

generally thought of as being applied to the immediate environment), and a means of exerting control over the targeted device. The degree and generalization of control differs among various EADL systems. These systems may provide a means of switching power to the target device, of controlling the features of an external device, or may subsume an external device to provide enhanced control internally.

POWER SWITCHING

The simplest EADLs only provide switching of the electrical supply for devices in a room. Although not typically considered as EADLs, the switch-adapted toys provided to severely disabled children would, formally, be included in this category of EADLs. To adapt a conventional battery powered toy, the therapist inserts a ‘‘battery interrupter’’ to allow an external switch to control the flow of power from the batteries to the workings of the toy. Power switching EADLs operate in precisely the same manner. A switch is placed in series with the device to be controlled, so that the inaccessible power switch of the device can be left in the ‘‘ON’’ position, and the device can be activated by a more accessible external switch. To provide control over appliances and lights in the immediate environment, primitive EADL systems consisted of little more than a set of electrical switches and outlets in a box that connected to devices within a room via extension cords. Control 1(5), for example, allowed the connection of eight devices to the receptacles of the control unit. Such devices are limited in their utility and safety, since extension cords pose safety hazards to people in the environment through risks of falls (tripping over the extension cords) and fires (overheated or worn cords). Because of the limitations posed by extension cords, EADL technology was driven to use remote switching technologies (Fig. 2).

Second generation EADL systems used various remote control technologies to activate power to electrical devices in the environment. These strategies include the use of ultrasonic pulses [e.g., TASH Ultra 4 (6)] (Fig. 4) infrared (IR) light [e.g., Infrared Remote Control (7)], and electrical signals propagated through the electrical circuitry of the home [e.g., X-10 (8) Fig. 3]. All of these switching

Figure 2. Electralink power switching module.

technologies remain in use, and some are used for much more elaborate control systems. Here we are only considering power switching, however (Fig. 4).

The most prevalent power-switching EADL control system is that produced by the X-10 Corporation. The X-10 system uses electrical signals sent over the wiring of a home to control power modules that are plugged into wall sockets in series with the device to be controlled. (In a series connection, the power module is plugged into the wall, and the remotely controlled device is plugged into the power module.) The X-10 supports up to 16 channels of control, with up to 16 modules on each, for a total of up to 256 devices controlled by a single system. The signals used to control X-10 modules will not travel through the home’s power transformer so, in single family dwellings, there is no risk of interfering with devices in a neighbor’s home. This is not necessarily true, however, in an apartment setting, where it is possible for two X-10 users to inadvertently control each other’s devices. The general set-up of early X-10 devices was to control up to 16 devices on an available channel so that such interference would not occur. In some apartments, the power within a single unit may be on different ‘‘phases’’ of the power supplied to the building. (These phases are required to provide 220-V power for some appliances.) If this is the case, the X-10

Figure 3. X-10 switching modules.

signals from a controller plugged into one phase will not cross to the second phase of the electrical wiring. A special ‘‘phase cross-over’’ is available from X-10 to overcome this problem. The X-10 modules, in addition to switching power on and off, can be used, via special lighting modules, to dim and brighten room lighting. These modules work only with incandescent lighting, but add a degree of control beyond simple switching. For permanent installations, the wall switches and receptacles of the home may be replaced with X-10 controlled units. Because X-10 modules do not prevent local control, these receptacles and switches will work like standard units, with the added advantage of remote control.

When they were introduced in the late 1970s, X-10 modules revolutionized the field of EADLs. Prior to X-10, remote switching was a difficult and expensive endeavor, restricted largely to applications for people with disabilities and to industrial applications. The X-10 system, however, was intended as a convenience for able-bodied people who did not want to walk across a room to turn on a light. Because the target audience was able to perform the task without remote switching, the technology had to be inexpensive enough that it was easier to pay the cost than get out of a chair. The X-10 made it possible for an able-bodied

212 ENVIRONMENTAL CONTROL

person to remotely control electrical devices for under $100, where most disability-related devices cost several thousand dollars.

Interestingly, the almost universal adoption of X-10 protocols by disability related EADLs did not result in sudden price drops in the disability field. In cases where simple power switching provided adequate control, many clinicians continue to adapt mass-market devices for individuals with disabilities. While this may not be a good use of clinician time, it does allow those with limited funding to gain a degree of control over their environments.

FEATURE CONTROL

As electronic systems became more pervasive in the home, simply switching of lights and coffee pots failed to meet the needs of individuals with disabilities who wanted to control the immediate environment. With wall current control, a person with a disability might be able to turn a light or television on and off, but would have no control beyond that. A person with a disability might want to be able to surf cable channels as much as an able-bodied person with a television remote control (9). When advertisements are blaring from the speakers, a person with a disability might want to be able to turn down the sound, or tune to another radio station. Because the ability to control a radio from across the room became a sales advantage when marketing to sedentary, able-bodied adults, nearly all home electronic devices are now delivered with a remote control, generally using IR signals. Most of these remote controls are not usable by a person with a disability, however, due to the small buttons and labels that require fine motor control and good sensory discrimination (Fig. 5).

The EADL systems designed to provide access to the home environment of a person with a disability must provide more than on/off control of home electronics. They must also provide control of the features of home electronic devices. Because of this need, EADL systems frequently have hybrid capabilities. They will incorporate a means of directly switching power to remote devices, often using

Figure 5. Imperium 200H provides infrared remote control of entertainment systems, power switching, and hospital bed control.

X-10 technology. This allows control of devices such as lights, fans, and coffee pots, as well as electrical door openers and other specialty devices (10). They will also typically incorporate some form of IR remote control, which will allow them to mimic the signals of standard remote control devices. This control will be provided either by programming in the standard sequences for all commercially available VCRs, televisions, and satellite decoders, or through teaching systems, where the EADL learns the codes beamed at it by the conventional remote. Preprogrammed control codes allow a simple set-up process to enable the EADL to control various devices, but only those devices whose codes existed prior to the manufacture of the EADL. The advantage of the learning approach is that it can learn any codes, even those that have not yet been invented. The disadvantage is that the controls must be taught, requiring more set-up and configuration time for the user and caregivers. In addition, there are cases where the internal IR switching speed of the EADL differs enough from that of the device to be controlled that some signals cannot be reproduced reliably.

Infrared remote control, as adopted by most entertainment systems controllers, is limited to approximate line of sight control. Unless the controller is aimed in the general direction of the device to be controlled (most have wide dispersion patterns), the signals will not be received. This means that an EADL cannot directly control, via IR, any device not located in the same room. However, IR repeaters, such as the X-10 Powermid (11) can overcome this limitation by using radio signals to send the control signals received in one room to a transmitter in the room of the device to be controlled. With a collection of repeaters, a person would be able to control any infrared device in the home from anywhere else in the home.

One problem that is shared by EADL users and ablebodied consumers is the proliferation of remote control devices. Many homes now are plagued with a remote control for the television, the cable–satellite receiver, the DVD player/VHS recorder (either one or two devices), the home stereo/multimedia center, and other devices, all in the same room. Universal remote controls allow switching from controlling one device to another, but are often cumbersome to control. Some hope is on the horizon for improved control of home audiovisual devices with less difficulty. In November of 1999, a consortium of eight home electronics manufacturers released a set of guidelines for home electronics called HAVi (12). The HAVi specification will allow compliant home electronics to communicate so that any HAVi remote control can operate the features of all of the HAVi devices sharing the standard. A single remote control can control all of the audiovisual devices in the home, through a single interface. Such standards are effective to the extent that they are actually implemented. As of the summer of 2004, the HAVi site lists six products, from two manufacturers, that actually use the HAVi standard.

The Infrared Data Association (13) (IrDA) is performing similar specifications work focusing purely on IR controls. The IrDA standard will allow an IR remote control to operate features of computers, home audiovisual equipment, and appliances equipped with IR controls through a

single standard protocol. In addition to allowing a single remote control to control a wide range of devices, IrDA standards will allow other IrDA devices, such as PDAs, personal computers, and augmentative communications systems to control home electronics. Having a single standard for home electronics will simplify the design of EADL systems for people with disabilities.

A more recent standard, V2 (14), offers a much greater level of control. If fully implemented, V2 would allow a single EADL device to control the all of the features of all electronic devices in its vicinity, from the volume of the radio through the setting of the thermostat in the hall, to the ‘‘Push to Walk’’ button on the cross-walk. Using a V2 EADL, a person with a disability could move from environment to environment, and be able to control the V2 enabled devices in any location.

One interesting aspect of feature control by EADLs is the relationship between EADLs and computers. Some EADL systems, such as the Quartet Simplicity (15), include features to allow the user to control a personal computer through the EADL. In general, this is little more than a passthrough of the control system of the EADL to a computer access system. Other EADLs, such as the PROXi (16), are designed to accept control inputs from a personal computer. The goal in both cases is to use the same input method to control a personal computer as to control the EADL. In general, the control demands of an EADL system are much less stringent than those for a computer. An input method that is adequate for EADL control may be very tedious for general computer controls. On the other hand, system that allows fluid control of a computer will not be strained by the need to also control an EADL. The

‘‘proper’’ source of control will probably have to be decided on a case-by-case basis.

One of the most important features of the environment to be controlled by an EADL is not generally thought of as an electronic device. In a study of EADL users conducted in Finland (17), users reported that the feature that provided the most gain in independence was the ability to open doors independently. While doors are not electronic devices, powered door openers may be, and can be controlled through the EADL.

SUBSUMED DEVICES

Finally, modern EADLs frequently incorporate some common devices that are more easily replicated than controlled remotely. Some devices, such as the telephone, are so pervasive that an EADL system can assume that a telephone will be required. Incorporating telephone electronics into the EADL is actually less expensive, due to telephone standardization, than inventing special systems to control a conventional telephone. Other systems designed for individuals with disabilities are so difficult to control remotely that the EADL must include the entire control system. Hospital bed controls, for example, have no provisions for remote control, but should be usable by a person with a disability. Hence, some EADLs include hospital bed controls internally, so that a person who is in the bed can control its features (Fig. 6).

A telephone conversation may be considered as having several components. The user must ‘‘pick up’’ to connect to the telephone system (able-bodied individuals do this by

214 ENVIRONMENTAL CONTROL

picking up the handset). If the user is responding to an incoming call, the act of picking up initiates the connection. If the user is ‘‘originating’’ a call, the act of picking up will be followed by ‘‘dialing’’, which describes the person to whom the user wishes to speak. When a connection is made (both parties have picked up), a conversation may ensue. At the end of the conversation, the call is ‘‘terminated’’ by breaking the connection.

Many EADL systems include a built-in speakerphone, which will allow the user to originate and answer telephone calls using the electronics of the EADL as the telephone. Because of the existing standards, these systems are generally analogue, single-line telephones, electronically similar to those found in the typical home. Many business settings now use multiline sets, which are not compatible with home telephones. Other settings use digital interchanges, which are also not compatible with conventional telephones. Finally, there is a move currently to use ‘‘Voice Over Internet Protocol’’ (VOIP) to bypass telephone billing and use the internet to carry telephone conversations. Because of this, the telephone built in to a standard EADL may not meet the needs of a disabled client in an office or other setting. Before recommending an EADL as an access solution for a client, therapists should check that the EADL communication system is compatible with the telecommunications systems in that location.

Because the target consumer for an EADL will have severe restrictions in mobility, the manufacturers of many of these systems consider that a significant portion of the customer’s day will be spent in bed, and so include some sort of control system for standard hospital beds. These systems commonly allow the user to adjust head and foot height independently, extending the time the individual can be independent of assistance for positioning. As with telephone systems, different brands of hospital bed use different styles of control. It is essential that the clinician match the controls provided by the EADL with the inputs required by the bed to be controlled.

CONTROLLING EADLs

For an EADL to provide improved function to the individual with a disability, it must provide a control interface that is more usable than that of the devices it controls. The common strategies for control found in EADLs are scanning and voice command.

Scanning Control

While scanning control is not particularly useful for computer control (17), it may be quite satisfactory for control of an EADL. When controlling a computer, the user must select between hundreds of options, and perform thousands of selections per day. When controlling the environment, the user may select among dozens of options, but will probably not be making more than a hundred selections during the day. While the frequent waits for the desired action to be offered in a computer scanning input system can have a crippling effect on productivity, the difference between turning on a light now versus a few

seconds from now is of little consequence. Because of this, many EADL systems provide a scanning control system as the primary means of controlling the immediate environment.

As with computer scanning, EADL scanning may be arranged in a hierarchical pattern. At the topmost level, the system may scan between lights, telephone, bed, entertainment, and appliances. When ‘‘lights’’ are selected, the system might scan between the various lights that are under EADL control. When a single light is selected, the system may scan between ‘‘Off ’’, ‘‘Dimmer’’, ‘‘Brighter’’, and ‘‘On’’. As the number of devices to be controlled increases, the number of selections required to control a particular feature will increase, but the overall complexity of the device need not.

Voice Command

Like scanning, voice command may be significantly more functional in controlling an EADL than a computer. If the user is willing to learn specific voice commands for control that are selected to be highly differentiable, a voice command EADL system can be highly reliable. As the potential vocabulary increases, the likelihood of misrecognitions increases and the quality of control goes down.

As with all voice-command systems, background noise can impair the accuracy of recognition. An EADL may easily recognize the commands to turn on a radio in a quiet room, for example, but may be unable to recognize the command to turn off the radio when it is playing in the background. This problem will be exacerbated if the voice commands are to be received by a remote microphone, and when the user is not looking directly at the microphone. On the other hand, the use of a headset microphone can improve control accuracy, but at the cost of encumbering the user.

In addition to microphone type and quality, voice quality can affect the reliability of the system. For individuals with high level spinal cord injuries or other neurological deficits, voice quality can change significantly during the course of a day. A command that is easily recognized in the morning when the person is well rested may be ignored later in the day, after the user has fatigued. At this later time, the user’s tolerance for frustration is also likely to be lessened. The combined effect of vocal changes and frustration may result in the user abandoning the device if an alternative control is not provided. While voice command of EADLs has a ‘‘magical’’ quality of control, for the person whose disability affects vocal quality or endurance, it can be a sporadic and limiting magic.

Other Control Strategies

For those systems that are controlled by a computer, any access method that can be used to control the computer can provide control over the environment as well. This includes mouse emulators and expanded keyboards as well as scanning and voice input. A recent study (18) has also demonstrated the utility of switch-encoding as a means of controlling the environment for children as young as 4, or, by extension, for individuals with significant cognitive limitations. In this strategy, the user closes one or two switches in coded patterns (similar to Morse code) to

operate the features of devices in the environment. The devices can be labeled with the control patterns for those users who cannot remember the controls, or during the training phase.

The technology now exists, though it has not been applied to EADL systems, to combine head and eye tracking technologies so that a person with a disability could control devices in the environment by simply looking at them. Head-tracking technology could determine, from the user’s location, what objects were in the field of view. Eye tracking could determine the distance and fine direction of the intended object. A ‘‘heads-up’’ display might show the features of the device available for control, and provide the control interface. With such a system, a user wearing a headset might be able to turn on a light simply by looking at it and blinking. This type of control strategy, combined with the V2 control protocol, would allow a person with a disability truly ‘‘magical’’ control of the environment.

THE FUTURE OF EADLs

Recognizing that the EADL provides a bridge between the individual with a disability and the environment in which they live, EADL development is likely to occur in two directions. The interface between the individual and the EADL will be enhanced to provide better input to the EADL, and remote controls will become more pervasive so that more of the world can be controlled by the EADL.

The user’s ability to control the EADL is a function of the ability of the person to emit controlled behavior. Scanning requires the presence or absence of an action, and ignores any grading. As assistive technologists develops sensing technologies to identify gradients of movement or neural activity, the number of selections that can be made directly increases. For example, current EADLs may be controlled by eye-blink for severely disabled individuals. But in the future, EADLs could use eye-tracking technology to allow a person to look at the device in the environment to be controlled, and then blink to activate it. Electroencephalography might, eventually, allow the control of devices in the environment by simply thinking at them (19,20).

The continued development of remote control technologies will, in the future, allow EADLs to control more of the environment that is currently available. Currently, EADLs can switch power to any device that plugs into the wall or that uses batteries. Feature control, however, is very limited. Cross-walk controls, elevators, and ATM machines do not have the means of remote control today, and are often beyond the reach of a person with a significant disability. Microwave ranges, ovens, and air conditioners also have feature controls that might be, but are not, remotely controllable. If interoperability standards like V2 are accepted, the controls that are provided for sedentary, able-bodied users may provide control for the EADLs of the future. It is generally recognized that the inclusion of remote control for EADL access is not cost-effective, but if the cost of providing remote control for able-bodied users becomes low enough, such options might be made available, which will allow EADLs of the future to control them as well.

BIBLIOGRAPHY

Cited References

1.Assistive Technology Partners. 2002. Direct Access Electronic Aids. Available at http://www.uchsc.edu/atp/library/fastfacts/Direct%20Access%20Electronic%20Aids.htm. Accessed July 26 2004.

2.MacNeil V. 1998. Electronic Aids to Daily Living. Team Rehabilitation Report, 53–56.

3.Center for Assistive Technology. Environmental Control Units. 2004. Available at http://cat.buffalo.edu/newsletters/ ecu.php. Accessed 26 July 2004.

4.Cook AM, Hussey SM. Assistive technologies: Principles and practice. 2nd ed. Philadelphia: Mosby International; 2002.

5.Prentke Romich Company, 1022 Heyl Road, Wooster, OH 44691. Phone: (800) 262-1984. Available at http://www.prentrom.com/index.html.

6.Tash Inc., 3512 Mayland Ct., Richmond VA 23233 Phone: 1-(800) 463-5685 or (804) 747-5020. Available at http://www. tashinc.com/index.html.

7.DU-IT Control Systems Group, Inc., 8765 Township Road #513, Shreve, OH 44676, Phone: (216) 567-2906.

8.SmarthHome, Inc., 16542 Millikan Avenue, Irvine, CA 92606-5027, Phone: (949) 221-9200 x109.

9.Butterfield T. 2004. Environmental Control Units. Available at http://www.birf.info/artman/publish/article_418.shtml. Accessed 26 July 2004.

10.Quartet Technology. 2004. Quartet Technology, Inc.-News. Available at http://www.qtiusa.com/ProdOverview.asp?ProdTypeID ¼1. Accessed at 29 July 2004.

11.asiHome, 36 Gumbletown Rd., CS1, Paupack, PA 18451, Phone: 800-263-8608. Available at http://www.asihome. com/cgi-bin/ASIstore.pl?user_action¼detail&catalogno¼ X10PEX01.

12.HAVi, Inc., 40994 Encyclopedia Circle, Fremont, CA 94538 USA. Phone: (510) 979-1394. Available at http://www.havi. org/.

13.IrDA Corporate Office, P.O. Box 3883, Walnut Creek, CA 94598. Phone: (925) 943-6546. Available at http://www.irda. org/index.cfm.

14.InterNational Committee for Information Technology Standards. What exactly is V2 - and How Does It Work? Available at http://www.myurc.com/whatis.htm. Accessed at 30 July 2004.

15.Quartet Technology, Inc., 87 Progress Avenue, Tyngsboro, Massachusetts 01879, phone: 1-(978) 649-4328.

16.Madentec, Ltd., 4664 99 St., Edmonton, Alberta, Canada T6E 5H5, phone: (877) 623-3682. Available at http://madentec. com.

17.Anson DK. Alternative Computer Access: A Guide to Selection. Philadelphia: F. A. Davis; 1997.

18.Anson D, Ames C, Fulton L, Margolis M, Miller M. 2004. Patterns For Life: A Study of Young Children’s Ability to Use Patterned Switch Closures for Environmental Control. Available at http://atri.misericordia.edu/Papers/Patterns. php. Accessed 4 Oct 2004.

19.Howard T. Beyond the Big Barrier. Available at http:// www.cs.man.ac.uk/aig/staff/toby/writing/PCW/bci.html. Accessed 11 Oct 2004.

20.Wolpaw JR. 2004. Brain-Computer Interfaces For Communication And Control. Available at http://www.nichd.nih.gov/ about/ncmrr/symposium/wolpaw_abstract.htm. Accessed 11 Oct 2004.

See also COMMUNICATIVE DISORDERS, COMPUTER APPLICATIONS FOR;

MOBILITY AIDS.