Let’s Get It Clear: Power assisted devices
The availability of lightweight batteries has meant that an increasing variety of power assisted devices are now possible for manual wheelchair users. What’s on offer?
The May 2026 issue of THIIS’ Buyer’s Guide listed a variety of after-market add-on propulsion power assist devices for manual wheelchairs. Coincidentally, the article in that issue’s Let’s Get It Clear series addressed the topic of combining medical devices, most specifically covering after-market accessories. In this month’s article we merge the two, covering the benefits of add-on power assist devices (PADs), looking at the various types that are available, and enquiring how we might know they are ‘safe’.
For many people with mobility impairments, a manual wheelchair becomes their ‘legs’. However, just as much as there’s a limit to the distance an ambulatory person can or will use their legs, there’s a limit to how much activity and distance a manual wheelchair occupant can achieve through the use of their arms and hands in propelling their manual wheelchair.
For those who are unable at all to propel a manual wheelchair, then a powered wheelchair is probably the best option. However, these days there is a middle ground of adding a small power assist system to a manual wheelchair. Small lightweight lithium-ion batteries have facilitated the proliferation of options available to the wheelchair user, just as they have for cyclists or foot-propelled scooter users.
For manual wheelchair users, PADs can be added to their chairs to aid propulsion, and these are the subject of this article. They can be front, mid, or rear mounted. Most can be occupant-controlled, and some assistant-controlled. It is noteworthy that there are also other areas where power assist can be found, include for steering, for tilt or recline of the seat, or for raising the occupant’s legs, for example.
Benefits
There’s been quite a lot of published research into the benefits of PADs, much of it pulled together in a 2022 Permobil White Paper1 entitled “A systematic review of the evidence for power assist devices”. The identified evidence-based benefits from using any type of PAD were shown to be:
- Reduced repetitive strain, contributing to reduced risk of upper extremity pain and dysfunction
- Wheelchair propulsion enabled over longer distances
- Activities requiring a higher propulsion force enabled
- Activities performed more easily and faster
- Occupant energy conservation
- Increased opportunity to navigate a wider range of environments
- Increased overall independence
Mechanical power assist
Earlier manual wheelchair adaptations to provide ‘power assistance’ to reduce the strains on the occupant’s shoulders and wrists were lever assisted propulsion units or hand propelled pedal cycle units. These options were originally more prevalent in mainland Europe, and are now readily available in the UK.
There can be a choice of Integrated Lever Wheelchairs (e.g. all-terrain models like the Mountain Trike2 use a direct-steer lever system) allowing users to drive and steer without gripping hand-rims, or Add-On Conversion Kits (e.g. Devices like NuDrive3 (Fig. 1) which can be attached in seconds to most standard manual wheelchairs to instantly convert them into a lever-drive system).
Front-mounted PADs
Most front-mounted PADs attach to the manual wheelchair frame, and lift the front casters off the ground. Most also have a tiller steering mechanism, with the outcome looking much like a mobility scooter. But not all! In Australia, in Perth, they are currently experimenting with powered front casters, as an alternative which would need to be joystick controlled.
Examples from the May issue of THIIS included various Triride4 products (e.g. Fig.2), and the Cruiser (Fig. 3) and Eco Assist from Rehasense5.
Main wheel PADs
These PADs are usually a replacement for the main wheel, and typically provide a servo assisted supplement to the manual propulsion activity through the rim of the wheel. There are variations where one or both main wheels are power-assisted.
Examples are the Alber Emotion DuoDrive (Fig. 4)6 and the Alber E-fix by Invacare.
Rear-mounted PADs
Rear-mounted PADsThe rear-mounted PADs fall into two camps, one type assists the occupant, while the other is designed for assistant control. A rear PAD typically fits under the chair, with a single rear caster or omni-directional rollers.
Examples of occupant-assist are the SMOOV One7 by Invacare, the TODO Drive8 by DASH Rehab, and the SmartDrive by Permobil9 (Fig. 5). Examples of assistant controlled add-on devices are Alber6 ViaGO by Invacare and a choice in the Powerstroll10 by Drive Medical range (Fig. 6).
Safety and usability issues
PADs, by their nature, consist of a product which is attached to a medical device as an accessory, and within the EU an accessory to a medical device is also classified as a medical device in its own right. Either way, a full risk assessment should be carried out as regards the safety to the user, whether an occupant or an assistant, or to anyone in the vicinity of the device. Also to be considered is that a PAD could also exert greater forces due to the increased mass and power from the motors being exerted on the manual wheelchair frame than for which it was originally designed.
In the EU there are safety and usability standards covering pass/fail criteria for manual wheelchairs (EN 1218311), and for powered wheelchairs (EN 1218412). At the time of writing, there’s a few new aspects of note. First, both standards are undergoing minor revisions so that they can become ‘harmonised’ standards – which means that it becomes a legal requirement that any wheelchair sold in the EU has passed the listed tests.
Second, in these revisions, the Annex in EN 12184 covering PADs has been revised to ensure that all three types of PAD can be tested to meet the requirements of EN 12184. Third, at May’s meeting of the ISO wheelchair standards working groups, it was agreed to aim to get the harmonised European standards also published as ISO standards as soon as possible.
An area still to be addressed is that of crash-testing. A chair that has passed a ISO 7176-19 crash test will probably perform very differently with a PAD attached: a front mounted PAD would need a different test rig designed, for example.
References
- https://www.permobil.com/en-us/clinical-research/research-library/permobil-white-paper-a-systematic-review-of-the-evidence-on-power-assist-devices
- https://www.mountaintrike.com/discover/lever-drive-system
- https://www.la-design.co.uk/nudrive
- https://www.trirideitalia.com/en-gb/power-device/
- https://rehasense.com/power-add-ons.html
- https://www.alber-usa.com/us/products/active-drives/e-motion/
- https://smoov.com/aa-en/
- https://dashrehab.co.uk/product/todo/
- https://hub.permobil.com/smartdrive
- https://drivemedical.co.uk/mobility/wheelchairs/wheelchair-power-packs
- EN 12183 Manual wheelchairs. Requirements and test methods
- EN 12184 Electrically powered wheelchairs, scooters and their chargers. Requirements and test methods
Further items can be found at www.beshealthcare.net. If you are interested in receiving further information on the topic, please contact 
barend@beshealthcare.net.
Dr Barend ter Haar has been involved in seating and mobility for over 30 years, including lecturing internationally and developing international seating standards
