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Interacting with technology
Published in Michelle Rita Grech, Tim John Horberry, Thomas Koester, HUMAN FACTORS in the MARITIME DOMAIN, 2019
Michelle Rita Grech, Tim John Horberry, Thomas Koester
The second element depends on the set of expectations that an operator has about how the display will respond to a control action. Ideally it should match the internal model the operator has, and also have movement compatibility. As a very simple example of movement compatibility, on small boats turning the tiller to the left should also move the rudder to the left.
Rehabilitation professional and user evaluation of an integrated push-pull lever drive system for wheelchair mobility
Published in Assistive Technology, 2020
Hailee R. Kulich, Sarah R. Bass, Alicia M. Koontz
An alternative to traditional pushrim propulsion is lever-driven WMDs. A lever-drive system involves a pushing or pulling action on the end of a tiller (Mandy et al., 2014). Lever-driven WMDs have been shown to be less physically demanding than pushrim propelled WMDs, as they require less vertical reaction forces to operate, reducing the forces on the upper extremities that do not contribute to motion and increasing mechanical efficiency by about 3% (Boninger et al., 2005; Flemmer & Flemmer, 2016; Mandy et al., 2014). Their increased efficiency makes them more suitable for weaker users, individuals with hemiparesis, and outdoor use (Flemmer & Flemmer, 2016; Smith et al., 2019). These systems have also been shown to decrease physical strain due to continuous motion, the use of flexor and extensor muscles, and less complex coupling of the hands during operation (Engel & Seeliger, 1986; Van der Woude et al., 1997). By utilizing a more neutral hand and arm motion, lever-drive devices may reduce the risk of carpal tunnel syndrome (Flemmer & Flemmer, 2016). Additionally, the direction of the applied force is closer to the center of the shoulder joint, reducing torque around the shoulder joints (Flemmer & Flemmer, 2016). An increase in efficiency and a decrease in strain can lower heart rate, oxygen uptake, and energy cost reducing the cardiopulmonary requirements for operating a lever drive system versus conventional pushrim manual propulsion (Lui et al., 2013).