An adaptive foot device for increased gait and postural stability in lower limb Orthoses and exoskeletons

Abstract

Assistive devices and exoskeletons have critical importance for people with manipulative and locomotive disabilities. One of the major purposes of such devices when used for lower extremities is to help provide the postural or gait stability of the user. However, current lower extremity exoskeletons available lack the sufficient foot support area to guarantee a safe operation for the rehabilitation of patients, and normal posture/gait for users carrying heavy loads on backpack. As a result, these devices may require an intensive control effort to supply the posture or gait stability and can demand additional therapist help during rehabilitation. In this paper, we proposed a novel adaptive foot system to enhance the required stability of lower extremity exoskeletons as an add-on device. The method essentially aims to automatically extend the support area behind the heel during walking. The proposed adaptive foot system can extend passively during stance and retract during the toe rocker phase, which allows increased support areas during stance and prevent collisions to the level ground during swing. It is practical to implement and can be employed without necessitating an actuation power. The proposed wearable system will particularly be valuable in rehabilitation for enhancing the stability where safety of patients is particularly critical. It is also anticipated that the system can be a complementary device for current exoskeletons or humanoid robots to enhance their stability. A detailed description and numerical analysis of the stability in sagittal plane is presented for postural and gait cases in this paper. Experiments have been also conducted to prove the effectiveness of the adaptive wearable device for postural and gait stability.

A review on the mechanical design elements of ankle rehabilitation robot

“…Even though almost all of these features are considered and installed in the existing robots, at present, they still require constant supervision of physiotherapists and often require additional external support or sophisticated procedure. 44,96 Dynamic characteristic of the robot is one of the major challenges. 94 At present, no device comes close to matching the flexibility of human therapist in assisting patient's movement or the intelligence of human therapist in providing mechanical input based on a real-time assessment of patient's feedback.…”

“…Even though almost all of these features are considered and installed in the existing robots, at present, they still require constant supervision of physiotherapists and often require additional external support or sophisticated procedure. 44,96…”

Design and Simulation Study of the Translational-knee Lower Extremity Exoskeleton

“…And at present, the effectiveness is proved through experiments by most researchers. A novel adaptive foot system to enhance the required stability of lower extremity exoskeletons as an add-on device was proposed by Jungwon Yoon et al [9]. And Experiments have been conducted to prove the effectiveness of the adaptive wearable device for postural and gait stability.…”

Fuzzy logic control for active ankle foot orthosis

“…PID controller is used to control the actuation [8]. Gait analysis is made by placing a dorsiflexion assist spring on a more flexible AFO to lift the foot [9][10][11]. A custom made powered AFO is designed using artificial pneumatic muscles [12].…”