Power Wheelchair Features and Components

Wheelchair Drive Controls

There are two types of drive electronics, digital and analog. Analog controls are the most common and most people find them the easiest to use. A user with analog controls has infinite (proportional) control of speed and direction whereas a user with digital (non-proportional) controls only has only basic speed and direction control without the ability for fine adjustments. Both analog and digital electronics allow for a variety of different devices to control the wheelchair based on the user's ability.

Analog systems are always controlled by some sort of gimble or other proportional device whereas digital systems are always operated by switches or some other non-proportional device.

Drive modes are programs within either the analog or digital electronics which dictate the maximum/minimum values of the speed, power, sensitivity, acceleration etc. of the power wheelchair which are preprogrammed at the factory but can be adjusted by your local dealer. Drive modes are usually set up for different terrains and driving situations. An example may be drive mode 1 for in one's home, drive mode 2 for in a store, drive mode 3 for outdoors and drive mode 4 for situations where the user may require maximum performance from the power wheelchair.

Analog Wheelchair Control Systems The joystick is by far the most common drive control and can be mounted for either right or left hand use. The joystick usually consists of a gimble, which is the the knob the user uses to direct the chair, an on/off switch, battery gauge, maximum speed control and sometimes a drive mode switch. Joysticks are analog control devices. Variations of the joystick can be operated by other parts of the body but all the controls, other than the gimble, are then mounted on a separate device known as a display. When driving with the hand is not an option, gimbles are commonly set up to be used with the head or chin. Pictured is an Invacare PS joystick.
Wheelchair Chin Control When controlled by the chin, the gimble is mounted on a swingaway mount of some sort and positioned slightly below and forward of the chin. Chin controls work much the same as conventional joysticks in that the user simply pushes the gimble the direction they want to go and control their speed by the distance they push the gimble. The knob on the gimble can be replaced with a small cup or other shaped piece depending on the needs of the user. Pictured is an Invacare compact joystick mounted on a swing away bar.
Wheelchair RIM Control When set up to be actuated by the head, the gimble is mounted behind the head and attached to a headrest. The user pushes the headrest left to go left, right to go right and back to go forward. One drawback of this system is the user can't actually use the headrest, as a headrest, unless power to the chair is turned off. Another drawback of this set up is that, to back up the user must activate a switch to be able to move backwards. The user must activate the switch again to move forward. Normally this is not a serious drawback, but if the user is in a situation where several back and forward movements are needed to get through a doorway or enter an elevator etc., it can be quite annoying to have to activate the forward/reverse switch so often. Pictured is an Invacare head control.
Finger Wheelchair Drive Control Finger control drive systems consist of a small square box about 3" x 3" x 1 1/2" with a 2" hole in the top of it. The finger control box can be mounted just about anywhere the user can comfortably reach. To drive the chair with a finger control box, the user places one finger through the hole on the top of the box and moves the finger in the direction they want the power wheelchair to move. This system is basically the same principle as a joystick in that it's a proportional drive but instead of moving a gimble, the user moves a finger. Pictured as an ASL finger control box.
Touch Pad Wheelchair Drive Control Touch pad drives also drive the power wheelchairs with a finger and can be mounted in several places on the wheelchair depending on the ability of the user to access it. Because touch pads are also proportional analog drives, the user can determine and control the speed of the wheelchair while moving simply by a small movement of the finger. The pictured touch pad is an Easycat.
Head Wheelchair Control Systems Head controls can be also set up with digital electronics packages. When using digital electronics there are switches mounted in the headrest which the user activates to go left, right and forward. As with the analog system, the user must activate another switch to change directions from forward to reverse. The advantage of the digital headrest system is that the user does not have to hold constant pressure on the switches to drive the chair as they must do with analog systems. As with the analog system the user can't actually use the headrest, as a headrest, unless power to the chair is turned off. The disadvantage of digital headrest systems is that there is no way for the user to adjust their speed while driving. The only control the user has of speed is the selection of their drive mode. Pictured is the ASL Digital head array with the supporting hardware and electronics module.
Wafer Board Wheelchair Control Wafer boards are similar in operation to the digital head control but are designed to be used on the user's lap or a wheelchair tray. Instead of the switches being hidden in a headrest and actuated by the user's head, the switches are mounted visibly on a board and activated by the user's hand. This digital system might be an option for a user who has some control of a hand but can't maintain the constant control needed to operate a joystick.
Proximity Switch Wheelchair Control Proximity switches are the type used in the digital head control and do not require pressure to be activated. The user only needs to move some part of their body near the switch to activate it. Proximity switches can be purchased loose and mounted virtually anywhere on the wheelchair the user can reach. Normally these switches are mounted on the under side of a tray and the user simply moves their hand on the tray from switch to switch to operate the wheelchair.
Single Switch Scanner Wheelchair Control Single switch scanners are another type of drive control available with digital electronics. Wheelchair scanners use a display with multiple lights mounted on it to control and direct the wheelchair. When the wheelchair is not moving the lights on the scanner blink on and off in a predictable rotation and the user activates the switch when the light desired is lit. On the scanner pictured there are four directional lights and the user activates the switch when the forward light is lit to go forward, the rear light to go backward and the side lights to turn. Once a light is chosen and activated by the user the chair will perform as commanded until the switch is hit again cancel the movement of the power wheelchair.
Sip'n'Puff Wheelchair Drive Control Sip and puff drives are the solution for those users who aren't able to use any part of their body to operate a control device on their power wheelchair. Sip and puff systems are digital non-proportional drives and require quite a bit of practice by the user to get good at driving. In order to drive with a sip and puff system the user will either blow into a tube or suck on the tube. Not only do the wheelchair electronics distinguish between a sip and a puff it, can also recognize the strength of the sip and puff. A hard sip or puff will mean one thing to the wheelchair and a soft sip or puff will mean something else. The trick for the user is to get used to how hard to sip or puff and be consistent with those actions.