Robotic shoe: An Ankle assistive device for gait plantar flexion assistance

Gait disorders can be attributed to a variety of factors including aging, injury, and neurological disorders. A common disorder involves the ankle push-off phase of an individual's gait, which is vital to their ability to walk and propel themselves forward. During the ankle push-off stage, plantar flexor muscles are required to provide a large amount of torque to propel the heel off the ground, thus a condition that compromises the strength of these muscles can greatly affect one's walking ability. In order to rectify these issues, Ankle-Foot Orthoses (AFO) are used to provide support to a user's ankle and assist with the force needed for heel off. This article introduces a robotic AFO which was developed with the intent of aiding during the heel-off stage. The proposed design utilizes the user's body weight to extend constant force springs positioned parallel to the calf to replicate the muscular force generated in plantar flexion. The extended spring is held in place using a ratcheting mechanism which is released with a solenoid during heel up. Similar research has been conducted in which assistive AFO's have been created, however little research has investigated the use of constant force springs in such devices. A healthy user tested the device on a treadmill and surface electromyography (sEMG) sensors were placed on the user's plantar flexor muscles to monitor potential reductions in muscular activity resulting from the assistance provided by the AFO device. The data demonstrates the robotic shoe was able to assist during the heel-off stage and reduced activation in the plantar flexor muscles was evident from the EMG data collected.