Robot-aided rehabilitation training allows patients to receive a more effective and stable rehabilitation
process. Exoskeleton devices are superior to the endpoint manipulators and cable suspension
devices on the aspect that they can train and measure the angle and torque on each joint of impaired
limbs. For robotic devices, physical safety should be guaranteed since the robot-assisted training
relies on high human-robot interaction especially for exoskeletons. Traditional robotic devices mainly introduce the
stiffness actuator, while the high levels of kinetic energy of robots will induce unsafe. For guaranteeing the safety of patients,
compliant actuator such as the series elastic actuator (SEA) and variable stiffness actuator (VSA) design has been
involved into these devices. The added compliance can make robots intrinsically safe and realize the energy-efficient actuation.
The VSA used a variable stiffness elastic component instead of a constant stiffness elastic component, and VSAs
is deemed to a kind of SEAs. A closed-loop interaction control method was used for SEAs to generate low impedance. By
comparison, the VSA realizes adaptable compliance properties with inherent mechanical design. Thus, for SEAs, an additional
mechanism is needed to adjust the output stiffness. In this paper, two kinds of compliant exoskeleton devices designed
with the SEA and VSA respectively are introduced. The mechanical design and control method for each device are
introduced; especially the design for guaranteeing patients’ safety.
Keywords: Compliant actuator, control method, home-based rehabilitation device, mechanical design, series elastic actuator,
variable stiffness actuator.
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