Orthosis with a controllable plantar height for fall prevention using a compact magnetorheological fluid brake

In this study, a compact magnetorheological (MR) fluid brake embedded in an orthosis was designed and fabricated to maintain plantar height for use in lateral fall prevention, and its performance and the fall prevention effect of the orthosis were evaluated. The results of the brake design and fabrication indicated that the MR fluid brake has the advantage of being compact, lightweight, and power-saving at 88.4 mm long, 128 g, using two AA batteries. Performance tests of the brake indicated that it was able to generate sufficient force (125 N) to maintain plantar height. Furthermore, through the assessments of lateral fall, the center of gravity and center of pressure inclination angle of a subject wearing the orthosis without the MR brake was determined to be 4.0°, as opposed to 4.4° with the MR fluid brake in the ON state. Therefore, the moment of force acting on the subject to prevent fall was larger, making them more stable when the MR fluid brake was in the ON state.