Actuator- and Control-Less Ankle Exoskeleton for Push-Off Assistance During Treadmill Walking: a Proof-Of-Concept...

Area of Science:

• Biomechanics
• Robotics
• Rehabilitation Engineering

Background:

• The AN-EXTRA-Push is a novel tethered ankle exoskeleton previously designed with active electromechanical brake control.
• It functioned by utilizing posterior leg movement during treadmill walking to stretch an elastic tendon.

Purpose of the Study:

• To assess the feasibility of a modified, control-less AN-EXTRA-Push exoskeleton.
• To evaluate its impact on ankle joint biomechanics in healthy and hemiparetic individuals.

Main Methods:

• A case study involved one healthy and one hemiparetic subject walking on a split-belt treadmill.
• The AN-EXTRA-Push was modified with a permanently attached elastic tendon, eliminating active control.
• Four conditions were tested: unassisted and three assistance levels, with varying speeds for the healthy subject.

Main Results:

• In healthy subjects, passive assistance reduced biological ankle torque but increased exoskeleton torque, augmenting total power generation.
• Exoskeleton torque and power output increased with higher walking speeds.
• In the hemiparetic subject, the device added torque and power without altering biological joint power or torque.

Conclusions:

• The control-less AN-EXTRA-Push is feasible for augmenting ankle power during walking.
• Preliminary findings suggest this passive exoskeleton design warrants further investigation for rehabilitation applications.