Part 2 ● A comprehensive framework to assess drive control needs

With ‘Purpose’, you want to discover the motivation of the user to control an electric wheelchair. Together with the user, ask the question: What can you not do in the current set-up that you would like to be able to do?

It’s crucial to ask this question. The benefits of powered mobility are widely studies and proven. By using an electric wheelchair people experience greater participation in activities such as education, work, a whole range of social activities, and sports. The increased mobility enhances quality of life and well-being. 

However, 40% of electric wheelchair users experience difficulties executing basic power wheelchair tasks such as controlling the joystick and manoeuvring backward. One of the reasons is the lacking fit between the person’s abilities and their electric wheelchair equipment.

So, the motivation for the alternative control might be overcoming these difficulties in executing basic tasks like rolling forwards and backward, maneuvering sideways, turning the wheelchair on or off, changing the speed, etc. But it is not limited to that. Maybe the wheelchair user wants to have better control over the wheelchair’s auxiliary functions ( e.g. light or horn)… Or maybe they want to be able to engage in social activities and sports.

When the purpose is clear, you assess the user’s cognitive abilities. Cognition is the term for the mental processes that take place in the brain, including thinking, attention, language, learning, memory, and perception. It’s a combination of a whole lot of things. 

Cognitive abilities are important to decide whether the users might best use a proportional or non-proportional control. 

Proportional controls are always the preferred input method, whenever possible. It works like a gas pedal in a car. The further you move the joystick away from the centre position, the faster the wheelchair will move. The most common proportional control is the traditional hand joystick, but there’s a wide variety of alternatives. 

A proportional control can be placed anywhere, as long as the user has the control to access at least three directions of movement (forward/reverse, left/right) or ideally four, for full access. Using a proportional control, however, requires cognitive and motor skills. The user must be able to grasp the concept of mobility.

A proportional control is the preferred input. It works like a gas pedal and requires cognitive and motor skills.

Individuals who do not have the ability to operate proportional controls must use a combination of switches with or without scanning control. These switches produce an action, which is either on or off in typically 4 or sometimes 8 directions of movement. 

Approach is about the optimal placement of the drive control on the electric wheelchair. How will a user physically reach the control and use it comfortably? Three different factors determine the approach of the drive control: Vision, core stability, and joint flexion or extension.

In part 3 of this blog series, we discuss these factors and different drive control solutions for complex mobility problems more in-depth. Once you’ve identified the user’s body part that gives the most consistent access for independent control, you can start comparing different solutions on the market. 

In short, three factors to determine drive control placement

• Vision: Ideally, you need vision to find the control system and safely navigate your surroundings, spot obstacles and estimate distances
• Core stability: The ability to maintain a stable and balanced position during movement and activities
• Joint flexion or extension: The ability to flex your shoulder and to extend your wrist and elbow (in case of a hand joystick in medial position)

Building block four is operation. We place it after approach but in reality this is assessed simultaneously. Operation is the force the user has got to operate the control. Often, you will start from the existing control and try out the next available solution. But the PT can also help you with manual muscle testing to assess the possibilities.

Assessing the force the user has, is key because there is a wide variety of joysticks available on the market. Many people are familiar with standard joysticks, mini joysticks and heavy duty joysticks but are not always aware of the options in between. 

There are solutions available all the way down to only 5 grams of force required, for people with reduced muscle strength and movements. And on the other end of the spectrum there are solutions of up to 650 grams of force, for people with very spastic movements.

The last building block – Learning – focuses on electric wheelchair driving skills. Because of the coordination it requires, navigating an electric wheelchair and avoiding collisions is often a daunting task for new wheelchair users. It takes time and practice to become a competent driver. 

By practicing in a safe environment, the user acquires functional skills without facing the risks of learning to drive in the real world. Plenty of evidence points out that training in simulated situations enhances wheelchair skill performance. Simulations allow the learner to conveniently encounter challenges they might otherwise only encounter infrequently and that might be spread over multiple locations.

There are several options to practice wheelchair driving skills:

• VR applications – For example, i-Drive System by Stealth

• Gaming joysticks – For example, HID Joystick compatible with PC, XBOX, Adaptive Controller by mo-vis

There are also more standardized ways to train and follow up on the progress: 

• Wheelchair Skills Program – A standardized way to monitor and revise wheelchair skills

• ALP tool - Assessment of Learning Powered Mobility Use, developed by Nilsson & Durkin

After a careful selection of the drive control, you want to assess its overall performance and more importantly, the impact on the user’s life. As mentioned, electric wheelchairs can have a positive impact on well-being, self-esteem, activity, and participation. However, electric wheelchairs aren’t the ultimate remedy. Tasks can remain too difficult or incur safety issues.

Hence it’s important to measure the outcomes of using a special drive control. Even more so because a study in 2022 shows the prevalence of formal wheelchair skills training is still low. To evaluate the outcome you can use the Wheelchair Skills Training Program (WSP) – in set time frames – or ask about the following:

• Injury rate
• Confidence with wheelchair use
• Mobility-related participation (Life Space Assessment)