What You Should Know About Wheelchair Controllers

The powered wheelchair controller and its associated modules and components serve as the command center for use of the wheelchair and its functions. There are two types of commonly used controllers found on wheelchairs today - integral controllers and modular controllers. Integral Controllers contain all of the necessary components in one housing to accomplish the fundamental requirements of wheelchair basics and operations. Modular Controllers have separate components for the various functions and wheelchair controlling elements. Both controllers include a joystick or something very similar for system-control.

Some wheelchair models, especially the less sophisticated or inexpensive ones, allow no choice of controll-ers and come standard with an integral controller, The integral controller is used for basic mobility appli-cations when no additional or special control features are anticipated. A user who can be expected to have little or no change in functional status over a long period of time and whose powered wheelchair requires no special or sophisticated features would be a good candidate for this type of control.

The technically high-end wheelchairs will sometimes offer a wide array of controller components and con-figurations. This is accomplished by allowing the use of different types of controls and interfaces, It allows for mixing and matching of components to accommodate such function-enhancers as "sip-and-puff" controls, specialty switches, powered-seating systems and external devices such as environmental control units or communication devices.

For example, the use of a "Sip-and-Puff" system, "Head-Array" system, "Chin-Control" system, "Finger-Steering" system, "Speech-Control" system or "Tongue-Operated" system is impossible to interface with most integral controller systems. These systems will not accommodate such systems because the electronics present will not allow for such interfacing. However, with a modular system, the item can be added to the wheelchair as long as the corresponding interface module is added or is already installed. (Sip-and-Puff or Sip N' Puff (SNP) technology is a method used to send signals to a device using air pressure by "sipping" (inhaling) or "puffing" (exhaling) on a straw, tube or "wand." It is primarily used by people who do not have the use of their hands. It is commonly used to control a motorized wheelchair by quadriplegics with very high injury to their spinal column or people with similar injuries.

In the "Head-Array" system, the driver utilizes three (3) sensors placed inside a headrest for the control of a power wheelchair. Although the "Chin-Control" system" is usually considered to be different from the "head-array" control system, the chip-mounted joystick still requires some head-movement. (With this system, the chin sits in a cup-shaped, joystick- controller handle and usually controlled by neck flexors, extensions and rotations.) This system is designed for a user with good head-control. "Speech-Control" systems are usually used with higher level, spinal-cord injury patients (C1–C4). The wheel-chair is con-figured with a built-in speech recognition system that recognizes a small vocabulary of words used to control directional movement; e.g., forward, to the rear, left, right, etc. Some more advanced systems use speech recognition to recognize all spoken words so that the user may use it for navigation and communi-cation through computer systems; e.g., e-mail, documents, etc.

The only commercially available "Tongue-Operated" controller is a "tongue-touch" keypad. It was introduced in the early 1990’s based upon work done at the Georgia Institute of Technology and later, by work done at the Dana and Christopher Reeve Foundation. The system consists of nine switches built into a dental mouthpiece that fits in the roof of the mouth and activated by the touch of the tongue. It allows the user to select the drive mode. The user adjusts the wheelchair speed by touching the front-pad to go faster or the rear-pad to go slower.

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The primary and the most important trade-off on these systems is flexibility. If flexibility in functional control of the wheelchair features is required or anticipated, the modular system is the way to go. If not, the integral system should work well enough.

PROS

• Integral is less costly.

• Integral is simpler and easier to handle.

• Modular is more flexible and allows greater latitude in choosing the types of interfaces and controls.

• Devices such as environmental control units and communication systems can be operated through a modular system.

• Various types of "driving-controls" such as the use of a "Sip-and-Puff System", "Head-Array System", "Chin-Control System", "Finger-Steering System", "Speech-Control System" and "Tongue-Operated System" can be added with a modular system.

• With a modular system, if the user-function or the user’s ability changes (positively/negatively), the existing system can be modified or increased without replacing the entire wheelchair.

CONS

• Integral is less flexible and cannot be expanded, easily.

• Integral control is much larger.

• Integral is too large to center or offset-mount on the wheelchair.

• Modular is more expensive.

• Modular requires experience or training to set-up when adding features.

• Modular systems may require components and interfaces from multiple after-market sources to achieve the desired result.

• Components for a modular system must be compatible with existing electronics.

• Many compatibility issues may arise when setting-up a complex integrated system.

• Modular controllers increase the wheelchair’s level of complexity.

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