On-Command Force and Torque Impeding Devices (OC-FTID) Using ERF
From: Medical Design Briefs - 12/2013 - page 38

An exercise exoskeleton was conceived that performs on-demand resistivity by
inducing force and torque impedance via ElectroRheological Fluid (ERF). The
resistive elements consist of pistons that are moving inside ERF-filled
cylinders or a donut-shaped cavity, and the fluid flows through the piston
when the piston is moved. Tests of the operation of ERF against load showed
the feasibility of this approach.

The technology is applicable as a compact exercise machine for astronauts'
countermeasure of microgravity, an exercise machine for sport, or as a device
for rehabilitation of patients with limb issues.

Read the entire article at:
http://www.medicaldesignbriefs.com/component/content/article/10-ntb/tech-briefs/bio-medical47/18756-npo-48393