One of the most common consequences after stroke is hemiparesis, which is weakness on the
side of the body contralateral to the stroke. For that reason, many stroke patients need a
wheelchair for mobility, especially early after the stroke, and they are taught to propel the chair
with the ipsilesional (i.e. “good”) arm and leg to compensate for the hemiparesis. On the other
hand, the current therapies for rehabilitation of the upper extremity after stroke are limited, as
most must be performed with the help of a therapist. Often the amount of arm recovery that
patients achieve is discouraging, likely due at least in part to the limited amount of arm exercise
they achieve early after stroke.
To try to improve this situation, we have developed the active-arm wheelchair, a wheelchair
that can be moved by displacing its armrest. The active-arm wheelchair consists of a mechanism
that is attached to the armrest of an existing wheelchair and that, through a system of gears and
a rack, translates the movement of the arm support into the rotation of the wheels, thus
propelling the wheelchair. The benefits of this system are: 1) it only requires the user to apply a
small, linear, reciprocating force with the arm (so there is no need to do the complicated
sequence of movements of grabbing-pushing-releasing-returning that are required to move a
typical manual wheelchair); 2) when moving with it, the user exercises the arm; and 3)
potentially, it makes the wheelchair propulsion more accurate and easier than one-sided,
compensatory, arm/leg propulsion. For these reasons, we think that, if a patient with
hemiparesis were able to propel the wheelchair using his/her impaired arm, this wheelchair
could improve rehabilitation, in terms of both promoting arm recovery and wheelchair mobility.
This thesis presents design modifications made to the active-arm chair to prepare it for clinical
testing, design of a clinical testing protocol, as well as initial testing of the protocol with
unimpaired volunteers. We installed sensors on the wheelchair and developed algorithms that
allow assessment of the use of the armrest and the trajectory of the wheelchair. We improved
the arm rest design based on therapist feedback. Further, we designed a set of activities to test
if the mobility achieved with a wheelchair only using a leg and the ipsilateral arm differed from
the mobility achieved using the same propulsion pattern plus the active-arm wheelchair.
Pilot testing with unimpaired users shows that it is possible to move the wheelchair using the
armrest, and that for some mobility tasks, the use of the armrest allows a more precise
movement than when only moving using the contralateral arm and leg. Furthermore, the use of
the armrest reduces the perceived fatigue of the leg used to propel the wheelchair.
Based on these pilot results, we hypothesize that the active-arm wheelchair has the potential to
become the mobility option of choice for rehabilitation therapy of patients with hemiparesis
after stroke. Future work will test this hypothesis in a clinical trial.
