A Portable and Automated Postural Perturbation System for Balance Assessment, Training, and Neuromuscular System Identification

Abstract

Background:To date, a postural perturbation system capable of generating position-, velocity-, and force-controlled perturbations while being portable and suitable for use during various postural scenarios does not exist. Therefore, the purpose of the present study was to design, develop, and test a portable and automated postural perturbation system (PAPPS) that can be used to measure and train postural reactions during sitting, standing, and treadmill walking. Method of Approach:The core component of the PAPPS was a linear actuator that provides horizontal perturbations. The actuator could generate arbitrary displacement, velocity, or force perturbations as a function of time. In addition, the PAPPS was able to measure the actuator's displacement, velocity, and load, which could be used to study postural perturbation responses. The height at which the PAPPS was delivering the perturbations could be easily adjusted to allow for different subject/patient anthropometrics and a wide range of postural scenarios such as sitting, standing, and treadmill walking. The PAPPS generated a peak displacement of 0.6 m, a peak velocity of 0.5 m/s, and a peak force of 600 N, which is more than sufficient to elicit high intensity postural perturbations.Multiple and nested safety circuits have been implemented into the PAPPS to ensure the safety of the subjects/patients during experiments and/or training.To evaluate the accuracy and repeatability of the PAPPS during position-, velocityand force-controlled perturbations, experiments were conducted using sinusoidal, impulse and ramp profiles as a function of time. Highly sensitive displacement and force sensors that were external to the PAPPS were used to determine the accuracy and repeatability of the proposed device. In addition, a case study was performed to demonstrate the A Portable and Automated Postural Perturbation System for Balance Assessment, Training, and Neuromuscular System Identification MED_08_1012_final Vette 3 performance of the PAPPS during pseudorandom sinusoidal perturbations that were applied to a healthy individual during sitting. Results and Conclusions: The accuracy and repeatability tests suggest that the PAPPS can generate reliable and high-precision displacement, velocity, and force perturbations.Potential applications of this system include, but are not limited to: (1) studies of postural response to various perturbation types and profiles in diverse subject populations during sitting, standing, and treadmill walking, and (2) training of postural balance in diverse patient populations during sitting, standing, and treadmill walking.

A Cost-Effective Inertial Measurement System for Tracking Movement and Triggering Kinesthetic Feedback in Lower-Limb Prosthesis Users

“…For the sinusoidal movement profile, the velocity and acceleration will again follow sinusoidal profiles. For each of the tested velocities per axis, the average root-mean-square error (RMSE) was computed following previous protocols [ 34 , 35 ], but with slight adjustments for gait as shown in Table 1 .…”

Low-intensity functional electrical stimulation can increase multidirectional trunk stiffness in able-bodied individuals during sitting

“…Independent of FES condition (natural or FES-supported), each subject was instructed prior to each trial to sit in an upright relaxed posture, and this as naturally as possible. One of the subject's hands held an emergency safety button that, when pressed, shut down the power of the custom-made perturbation system (PAPPS) [33] applying the horizontal forces to the subject (Fig. 1A).…”

Effects of Trunk Impairments on Manual Wheelchair Propulsion Among Individuals with a Spinal Cord Injury: A Brief Overview and Future Challenges

“…In both of these approaches, a loss of balance is technically anticipated in the event that the COP would travel outside the boundaries of the base of support (BOS). Alternatively, a portable and automated postural perturbation system, 45 recently developed, will allow one to compute "reactive" multidirectional dynamic seated postural stability. As there is a need for additional reliable and valid measures of sensorimotor trunk impairment among individuals with SCI, these new approaches should be explored.…”