Attakorn Suwananthawong and Dulyachot Cholaseuk, "A STUDY ON ERGONOMIC EGG-SHAPED FOUR-BAR LINKAGE PROPULSION MECHANISM FOR MANUAL WHEELCHAIRS" , 29 June 2020.
Most manual wheelchair users use conventional push-rim wheelchairs. Although manual push-rim wheelchairs help promotes a good lifestyle, the non-ergonomic, high muscular demand of non-continuous push motions can trigger severe upper extremity injuries. In this study, a new four-bar linkage propulsion mechanism is introduced. The mechanism was designed to provide continuous propulsion while allowing the wrist movement to follow the ergonomic egg-shaped path. A prototype was built and tested. User opinions
indicated that they experienced a more comfortable ride than in the conventional push-rim wheelchair. Overall, the use of the four-bar linkage mechanism causes less strain to muscles and should reduce fatigue during prolonged usages.