Design and experimental evaluation of yoked hand-clutching for a lever drive chair

Abstract

Lever-drive wheelchairs lower physical strain but are less maneuverable than push-rim wheelchairs. Here, we study a possible solution in which the user simultaneously actuates clutches mounted between the levers and wheels each stroke via a clutch handle attached to one lever; this solution is of particular interest for user groups with only one functional hand. First, to demonstrate maneuverability, we show how this "yoked clutch" allows an experienced user to maneuver a constrained space. Then, we compared the difficulty of learning a yoked clutch chair to a conventional lever-drive transmission (i.e. a one-way bearing). Twenty-two unimpaired novice adults navigated a figure-eight track during six training sessions over two weeks. Participant mean speed improved roughly 60% for both chairs, with similar exponential improvement time constants (3 days) and final speeds. However, speed improvement mostly took place overnight rather than within the session for hand-clutching, and the physiological cost index was also about 40% higher. These results indicate that while hand-clutching is no more difficult to learn than a lever-drive, it is reliant on overnight improvement. Also, its increased maneuverability comes with decreased efficiency. We discuss how the yoked clutch may be particularly well suited for individuals with stroke during inpatient rehabilitation.

There is plenty of room for motor learning at the bottom of the Fugl-Meyer: Acquisition of a novel bimanual wheelchair skill after chronic stroke using an unmasking technology

“…Participants navigated a figure eight track with a 14 m long path designated with masking tape on the floor. This was an identical protocol to previous study with younger, unimpaired participants [12]. To match practice times with that previous study (in which participants completed a fixed number of laps each session rather than a fixed training duration like this study), participants practiced for the following number of minutes each session for six training days spaced over two weeks: Session 1: 5 min 37 sec; Session 2: 4 min 22 sec; Session 3: 4 min 1 sec, Session 4: 3 min 42 sec; Session 5: 3 min 35 sec; Session 6: 3 min 21 sec.…”

“…the first trial’s performance time and α is the learning rate [14]. This same equation was also fit to a previously collected dataset acquired from young, unimpaired adults (mean age = 22.3 ± 2.8 years, N = 11) who drove the same version of LARA with the same experimental protocol [12]. Statistical comparisons were carried out with the Friedman’s test, Wilcoxon Rank Sum (WRKS) test and Wilcoxon Sign Rank (WSR) test.…”

“…Thus, for the present study, we developed a second version of LARA with a novel drive system we call “yoked hand clutching” [12] (Fig. 1).…”

“…“good”) hand that simultaneously actuates both clutches: one on the left and one on the right, which attach the push levers to their respective wheelchair wheel. Somewhat counterintuitively, users can use this system to turn in place and back up by timing the pumping motion of the two levers with clutching by the good hand [12]. …”

Using a bimanual lever-driven wheelchair for arm movement practice early after stroke: A pilot, randomized, controlled, single-blind trial

“…LARA (Lever-Actuated Rehabilitation and Ambulation) is a bimanual lever-driven wheelchair configured so that the paretic arm contributes to propulsion. 8,13 Pilot testing with a precursor device called RAE (the Resonating Arm Exerciser), which utilized the same lever configuration as LARA, showed that individuals with severe arm impairment in the chronic stage of stroke can pump a lever attached to the wheels of a wheelchair with their hemiparetic arm, rolling forward and backward, and that repeated pumping of these levers leads to therapeutic benefit. 14 We tested RAE in a home-based randomized control trial where independent training with RAE (~500 repetitions per hour) was found to be feasible and to significantly reduce arm impairment in individuals with chronic stroke, without increasing pain or tone.…”