Sunrise Medical SMA Chapter Controls / Electronic interfaces / Access methods, Standard joystick

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Chapter VI:

Controls / Electronic interfaces / Access methods

The advancement of power wheelchair electronics in the past couple of decades has been quite amazing. There is a variety of access methods available to control the movement of a power wheelchair as well as the seat functions. In fact, even if only one part of your body can move with very little strength and excursion, even if only in one direction, you can make a wheelchair move in all directions, tilt, recline, and do everything else.

Access methods are usually categorized by “proportional” or “digital” controls. Many users with SMA will be candidates for proportional controls, whether a standard joystick unit or an adapted version.

With a progressive condition it is wise to consider future electronics possibilities. Some wheelchairs have “expandable controllers”, which means that alternative access methods can be added later even if the client starts with a standard joystick.

Many variables on a power wheelchair can be programmed to ensure adequate response to the user’s input. Such variables include but are not limited to: speed, power/torque, acceleration, deceleration, joystick throw, etc. Most manufacturer offer programmers on their order forms, but they are typically not ordered with the wheelchair. There are also non-programmable wheelchairs on the market but these are rarely appropriate for users with SMA. Programming capabilities vary by make and model.

Proportional control

Proportional means that the speed of the chair is proportional to the displacement of the control unit – for example, as the user moves the joystick further forward the chair will go faster and faster. In addition proportional control allows moving in any direction within the 360° radius – for example, the wheelchair moves the same direction as the joystick is pointing.

•Standard joystick.

Usually located on the side of the wheelchair, attached to the armrest, but alternative placements are possible (such as mid line mounting, often preferred for very small children). The programming variables allow many people to access driving using a regular joystick. For example, reducing “joystick throw” to 50% means that the wheelchair will respond fully when the joystick is pushed only half way.

Alternative handles can also be used; carrot, T handle, large and small balls, etc. to ease grasp on the joystick.