Environmental Controls
An environmental control device is a form of electronic assistive technology which enables people with significant disabilities to independently access equipment in their environment e.g. home or hospital. There are many types of environmental control devices but they are broken down into two categories, stand-alone and computer based.
According to the Delaware Assistive Technology Initiative [2] there are currently four basic types of ECUs available. They are:
AC power. This type of system uses the electrical wiring already in your home. Each item to be controlled (lamp, radio, etc.) is plugged into a control box, which in turn is plugged into an electrical outlet. The user has an input device that communicates with each control box via the existing wiring system. A different control box is needed for each appliance. These systems are inexpensive and easy to install.
Infrared. These ECU devices send an infrared signal to the control unit, which in turn sends another infrared signal to the appliance. This type of ECU is seen in most of our TV and VCR remote controls. In order for the device to work, the remote must be aimed directly at the control box with nothing blocking its path.
Radio control. With this type of device, the remote sends radio waves to the control unit, which then sends the message to the appliance. This is the same technology that powers garage door openers. The remote and the control box can be in different rooms and still work, but the system has a range limit of 50-200 feet. Interference from another nearby control unit is also possible.
Ultrasound. This type of ECU uses high frequency sound waves as the input and output signal. The sound wave will bounce around the room until it reaches the control box and delivers its message. The control box then sends a command signal to the appliance being controlled. The input device and the control box must be in the same room to work.