A Novel Trunk Rehabilitation Robot Based Evaluation of Seated Balance Under Varying Seat Surface and Visual Conditions

Amre Eizad,Sung-Ki Lyu,Sanghun Pyo,Jungwon Yoon,Muhammad Raheel Afzal,Hosu Lee

doi:10.1109/access.2020.3036435

Abstract

Physical therapy involving the use of varying types of seating surface and visual input is recommended for individuals suffering from trunk instability. Some robots have been developed to assist in such therapy protocols, but none of them fully constrains the user's lower extremities to move with the seat, which is required to fully transfer the task of maintaining balance to the trunk. To fulfill this requirement, we have developed a robot that can provide a static, unstable or forced perturbation seating surface. The instability of seating surface is provided by having the robot follow movements in the user's center of pressure (COP) and forced perturbations are provided by moving the surface according to an operator's commands irrespective of the COP position. The system is also capable of providing visual feedback of the user's COP. This paper presents a study conducted using this novel robot aimed at evaluating the effect of the different seat modes on the balance of healthy subjects under different visual conditions (blindfold, eyes open and visual feedback). Various COP and trunk movement parameters were observed and the results indicate that the system can elicit similar responses in the unstable mode as the conventional devices, showing that it may be used as a controllable alternative to such devices for the training and objective evaluation of stroke survivors. The results under perturbation conditions showed deviations from the generally held notions about the use of visual feedback. Thus, revealing the need for further studies on the implications of using visual feedback under perturbation conditions. The observation of effects similar to conventional systems that may be beneficial for stroke survivors and the system's ability to help assess recovery progress show that the system holds promise for use as a trunk training and objective performance evaluation tool for stroke survivors.

Highlights

The human core consists of the abdominals in the front, paraspinals and gluteals in the back, the diaphragm on the top, and the pelvic floor and hip girdle musculature at the bottom [1]
We have used this robot to evaluate the effects of different seat modes and visual modes on the various center of pressure (COP) and trunk movement parameters derived from data recorded during the performance of a simple upright balance maintenance task under different trial conditions
The results indicate that the system can elicit similar responses in the unstable mode as the conventional devices, and that further studies of the implications of using the perturbation mode with the provision of visual feedback of COP position are required

Summary

Introduction

The human core consists of the abdominals in the front, paraspinals and gluteals in the back, the diaphragm on the top, and the pelvic floor and hip girdle musculature at the bottom [1] These muscles work together to stabilize the spine, pelvis, and kinetic chain during movements of the body [2]. As a consequence of diseases such as stroke, the ability of this muscle complex to maintain balance can become impaired This can have a strong negative impact on the ability of the patient to safely perform independent gait and the activities of daily living [3,4,5,6,7,8,9,10]. For stroke patients, initial therapy to develop gross trunk control is recommended in order to pave the way for recovery of other functions such as gait [11].

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