Education in Motion / Blog / July 2019 / Power Wheelchair Drive Controls, Part 2: Non-Proportional

Power Wheelchair Drive Controls, Part 2: Non-Proportional

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In Part 1 of this series on power wheelchair drive controls, we reviewed the difference between the two overarching types of drive controls: proportional and non-proportional. If you have not had a chance to read that post, I highly recommend spending a few minutes reading it before continuing on with this post, because it provides a good foundation for understanding drive controls.

Even though proportional drive controls are by far considered to be the most common type of drive controls used to drive power wheelchairs, I believe it is important that we look at non-proportional controls first. Why? Because non-proportional drive controls offer the most basic and simplistic option for activation in terms of motor function, cognition, and overall experience.

As with any type of equipment, it is vital that the proper device be matched to meet specific needs of an individual. When it comes to choosing between a proportional and a non-proportional drive system for an individual, many of the strengths or benefits one type can provide a user could be considered a negative to another, thus preventing the client from being successful with using a power wheelchair independently for mobility.

What are the features and potential benefits of a non-proportional drive control?

Functions similarly to the power switch on a vacuum cleaner. Once a non-proportional drive control is activated, it is completely on and when it is released, it is completely off.
Pre-programmed speed. Once the device is on, no matter how much pressure is applied to it, it will only go at the pre-programmed speed.
In general, non-proportional drive controls require less coordination and motor control to activate than a proportional control device. One of the reasons for this goes back to the previous point; precise movements are not needed to control the speed.
In order to utilize a non-proportional drive control such as a switch, a user only needs to be able to move a body part in two directions (one to activate the switch and one to move off of it).
If a client does not have the fine motor control to move a proportional device, but does have the ability to move multiple body parts in two directions, various switches assigned to different directions or functions can be mounted near those body parts to capitalize on those abilities to increase successful driving in all directions.
A non-proportional drive control can be used as an excellent tool for training an individual who has never driven a power wheelchair to build foundational skills, but might transition to using a proportional drive system prior to ordering his/her personal wheelchair.
Applying the concept of cause and effect to learn how to start and stop a wheelchair with a non-proportional switch is simple.
Teaching directions via non-proportional switches is another potential benefit to using a non-proportional device. For example, each switch can be programmed individually to drive the chair in a single direction at the pre-programmed speed. The switches can be introduced one-by-one as the user masters each direction.

Switches are arguably the most common type of non-proportional drive control options. In fact, historically switches were only available in non-proportional options, but technology has changed in recent years. Be sure to stay tuned to the final post in this series to learn more about proportional switches.

A person using non-proportional drive controls

When it comes to drive control options, there are two primary types of switches used either as standalone devices or incorporated into a drive control device used to drive a power wheelchair. The two types are mechanical and electronic. In an Education in Motion post last year, Robert Norton, ATP, reviewed the primary differences between mechanical and electronic switches in terms of functionality and provided examples of each. After reading this post, please take the time to further your knowledge by reading Robert's post.

With all of that said, we have wrapped up our discussion on non-proportional drive control options. Next, we will talk about proportional controls.