Environmental Control Units Explained


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Living with a severe disability can be devastating. The loss of independence and control of one's environment can lead to low self-esteem and depression. Using an environmental control unit to increase independence and control can improve a person's self esteem by allowing them to participate in every day living, school, work, and leisure activities. This increased independence can reduce the need for a paid attendant, cut down on demands of the family, and provide some much-needed privacy for the individual with a disability. An Environmental Control Unit (ECU) is any piece of equipment that allows an individual with a disability to control aspects of their environment that are operated by electricity (i.e. lights, TV, telephone, etc.).

An ECU is made up of three basic components: an input device, a control unit and an appliance. The input device controls the ECU by sending a signal to the control unit through direct selection (keypad, keyboard, joystick, etc.), switches, or voice control. The control unit is the central processing unit or the brain. It receives the input (signal) and translates the information into an output (command). The appliance receives the output signal and performs the desired command, such as turn on/off. An appliance that can be operated with an ECU is any piece of electronic equipment that needs no additional labor. Appliances such as TV's, radios, lights, VCR's, motorized drapes, and motorized hospital beds are good examples for use with an ECU.  They are all simple to operate with commands such as on/off or up/down.  Other appliances such as a washing machine require additional labor.  To operate this appliance the user needs to be able to put clothes in the washer, set the dials and then remove the clothes when the cycle has finished.

Environmental Control Units can be divided into two types: computer based, and stand-alone. A computer-based system consists of a software program and the necessary peripherals that allow a computer to function as an ECU. The advantages to using this type of system are the relatively low cost (the software plus a personal computer is cheaper than most stand-alone units) and a predetermined access method if the user already accesses the computer. Disadvantages include the need to have the computer running at all times, the need for visual and/or physical access to the computer from various positions, and the lack of transportability of the system. The system can be made more transportable by using a laptop computer instead of a personal computer.

Stand-alone ECUs contain their own electronics and do not utilize a computer to function. Many of these units can be activated by a switch, which acts as the interface between the user and the unit. The switch can be a single switch (button, leaf, etc.) or a dual switch (sip and puff, rocker, etc.). The switch is used to activate a scan of the menu items or commands. The scan can be automatic or directed. Automatic scanning is when the user activates the switch to start the scan and the menu items continue to scan until the user activates the switch to make a selection. This can be done with a single or dual switch. Directed scanning involves multiple activations of the switch to move through the menu until the desired command is located and activated. This can also be done with a single or dual switch.

Some ECUs can be activated by voice commands. These systems are user dependent, which means that the user trains the unit to his or her voice and that user is the only person who can use the system. The ECU creates a bank of voice models from the training. It then compares the voice commands to the bank of models, and when it finds a match, executes the designated action. An advantage to using voice commands to control the ECU is that the user need not have a consistent physical movement. However, they do need to have a consistent voice pattern. Even with a consistent voice pattern, recognition accuracy is less than 100 percent and the accuracy decreases even more in a noisy environment. The user also needs to have adequate memory skills to remember the command sequence unless he or she has visual access to a display.