What You Should Know About Wheelchair "Swing-Away" Joystick Mounts

What You Should Know About Wheelchair “Swing-Away” Joystick Mounts

A mounting arm for the joystick with an articulating (hinged) joint that makes it possible to swing the control away and back. Most models have a tension mechanism for locking the arm into the forward position. These items can be obtained from the wheelchair manufacturer or a number of aftermarket sources. Depending on the source, there are slight differences in design. These devices are primarily used to allow powered-wheelchair users to get closer to and under tables, desks, workstations, etc.

Because of the great flexibility in aftermarket products, “joy-sticks” can be mounted just about anywhere desired on a wheelchair. There are two types of mounts – bolted-on (permanent and usually slimmer) and quick-release (requiring a release-device or lever including suction-cups).

The most complex part in configuring a custom, joystick controller can be in determining and implementing the mounting. The layout of the buttons, comfortable placement of the hands and obstructions determine the dimensions of the control panel and the placement of the controller box. Because the mounting depth is determined by the length of the joystick's shaft, different models of joysticks have different distances between the top of the mounting-plate and the bottom of the ball-top meaning some joysticks should be installed much closer to the surface.

The main goals are to place the joystick at a height suited to the “play-style” of the user and to have the joystick-body hidden securely under a smooth surface. Many users like to rest the side of their palm on the panel while using the joystick at a specific, relative height. If you feel like you need a more detailed analysis of the “mounting-depth”, you should get a feel of the actual joy-stick, itself, to determine how deep it should be placed.

In the United States, there are at least five after-market manufacturers of joystick-mounts ranging in price from $ 20.00 to $ 300.00, custom-mounted.

PROS

• Makes it possible to move the joystick “out-of-the-way” to get closer to tables, desks, and workstations and under counters.

• Increases functionality, comfort and independence.

CONS

• The position locking mechanism or the moving parts may loosen after some time, making the joystick-box “wobbly” and difficult to lock and/or hold in place, on rare occasions.

• User may not be able to manage the device, independently.

• This device is, often, an optional upgrade to the wheelchair and will add extra expense.

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What You Should Know About Wheelchair Seat-Depth

What You Should Know About Wheelchair Seat-Depth

Wheelchair seat-depth is measured from the front to the back of the seat. To determine the existing size, you need to measure the distance from the front edge of the seat to the back where the seat meets the back-upright. This will give you a depth dimension of the existing seat.

Measuring to the back-rest upholstery may result in an incorrect measurement. Most back-upholstery is stretched and hung between two, free-standing, swinging supports (like a hammock), so measuring from the center of the seat to the center of the back-upholstery will result in a longer and incorrect dimension, as well. Some wheelchairs have add-on backs. Many of these mount forward of the back-uprights thus making unusable any seat surface located behind the add-on back.

To determine the appropriate seat depth for a user- the user should be placed in the best possible seated position that can be obtained. A measurement is taken from the back of the pelvis (furthest back part of the buttocks), forward to the back of the knee. Make sure that each leg is measured separately. There are more leg-length discrepancies (differences in leg-lengths) than you may think. From the measured length, for clearance, deduct 2".

If you have decided on an add-on back, you will need to allow for this. If the chosen back takes up seat space in front of the back uprights, you will have to add that amount back into the formula. If not, you will be scratching your head wondering why the seat appears so short on the finished product.

With no add-on back: (measured length) - (2" clearance) = depth

For chairs with an add-on back: (measured length) – (2” clearance) + (overlap-of-back on seat) = depth

Source listing of add-on wheelchair back-suppliers =  

                                                          www.usatechguide.org/techguide.php?vmode=1&catid=205

If there is a leg-length discrepancy (differences in leg length), custom upholstery, seat pans, or inserts can be ordered from the wheelchair manufacturer (sometimes) or from aftermarket suppliers. Many cushion manufacturers will also custom make their products to accommodate these differences.

PROS

• A proper wheelchair seat-depth will afford the user increased pressure reduction.

• It will also enhance comfort and will promote improved sitting posture.

• With as shallow a seat as possible will assure a shorter wheelchair frame (in a manual wheelchair) which

   will result in a lighter chair, decreased turning radius, and easier transporting and storage.

• A longer depth will serve to distribute pressure over a greater area (the surface area of the seat) thus

  reducing pressure in any given place. (This does not hold true if the user is sitting in the knees-up

  position with only the “sitting-bones” making seat contact. The pressure will still remain on these bones

  no matter how deep the seat is. If the thighs do not make contact with the seat, they will not aid in an

  even pressure distribution.)

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CONS

• An excessively long seat will push against the back of the leg or in the area of the popliteal crease (fold

  on the back of the knee) causing the user to be pushed forward on the seat and into a sacral (slouched)

  position. If left unresolved in patients with insensate (no sensation or feeling) lower extremities, this

  situation may also result in tissue trauma (sores, wounds) to the back of the leg.

• An overly-deep seat will not allow the user to sit all the way back against the wheelchair-back.

• If the user is forced forward on the seat, most of the weight will be located forward on the wheelchair

  making the chair harder to push.

• Long seats will also add weight to the chair.

• Excessively short wheelchair seat-depths will result in increased pressure to the seating area resulting in

   less surface area. This may increase the risk of tissue trauma.

• The amount of support offered by the seat will also diminish possibly causing poor posture.

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What You Should Know About Wheelchair Controllers

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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