Zhiyu Sheng

University of Pittsburgh | Pitt · Mechanical Engineering and Materials Science

Objective To implement and validate a 3D volume imaging sequence and 3D strain estimation procedure for enhanced biaxial mechanical testing of excised ventricular myocardium. Methods One right- and one left-ventricular excised porcine myocardium specimens were tested using dual-loading protocol quasi-static biaxial mechanical testing. During biaxi...

Objective: Quantification of the skeletal muscle response can help better understand the fundamentals of the musculoskeletal system and can serve as a diagnostic measure or recovery assessment tool during rehabilitation for neurological injuries. Surface electromyography (EMG) is commonly used to measure muscle activity, but it is limited to detec...

Row-Column-addressed Arrays (RCAs), which have recently become commercially available, transmit along the rows and receive along columns of a 2D array in order to produce 3D volume images with low channel count. Imaging of the inherently three-dimensional, layered, and fibrous structure of muscular tissues in 3D using an RCA can improve evaluations...

Ultrasound thermal strain imaging (US-TSI) has been known for the capability of tissue characterization according to distinct sound speed change in different tissues when temperature increases. US-TSI for detecting lipids in atherosclerosis plaques and fatty livers has previously been reported while some practical challenges were not fully addresse...

Ultrasound-based state assessment of the human muscle during rehabilitation and its integration into a hybrid exoskeleton comprising an functional electrical stimulation (FES) system and a powered orthosis are emerging research areas. This article presents results from the first experimental demonstration of a hybrid knee exoskeleton that uses ultr...

Purpose of Review This paper aims to review the currently available ultrasound imaging technologies in musculoskeletal studies by showcasing recent representative works in the field. Brief comments on the technical characteristics and potential advancement of these technologies are provided. Recent Findings Other than the conventional brightness-m...

No PDF available ABSTRACT Assessment of skeletal muscle function is an active research area in rehabilitation and sports medicine. An effective assessment methodology can be used to evaluate muscle recovery or response to treatments or interventions, and for early diagnosis of skeletal muscle diseases when combined with corresponding biomarkers. Th...

No PDF available ABSTRACT Neuromuscular electrical stimulation (NMES) artificially activates skeletal muscle contraction by sending electrical pulses either to nerves or muscle belly. NMES has been used in various applications in rehabilitation and sports medicine. However, muscle function assessment has been limited to electrical activity measurem...

In this paper, a switched control method for a class of wearable robotic systems that prioritizes the use of human skeletal muscles in an assistive rigid powered exoskeleton is derived. A general N-degree-of-freedom (N-DOF) human-robot model is proposed to consider the challenges induced by the wearable system that include uncertainties and nonline...

A hybrid neuroprosthesis system is a promising rehabilitation technology to restore lower limb function in persons with paraplegia. The technology combines functional electrical stimulation (FES) and a powered lower limb exoskeleton to produce movements for walking and standing. The main control challenge in the hybrid neuroprosthesis is to achieve...

Neuroprosthetic devices that use transcutaneous neuromuscular electrical stimulation (NMES) are potential interventions to restore skeletal muscle function in people with neurological disorders. As commonly noted, how to assess the NMES-induced muscle fatigue is a critical problem. This is because the capability of fatigue assessment is a necessary...

The quick onset of muscle fatigue is a critical issue when applying neuromuscular electrical stimulation (NMES) to generate muscle contractions for functional limb movements, which were lost/impaired due to a neurological disorder or an injury. For in situ assessment of the effect of NMES-induced muscle fatigue, a novel noninvasive sensor modality...

Ankle dorsiflexion produced by Tibialis Anterior (TA) muscle contraction plays a significant role during human walking and standing balance. The weakened function or dysfunction of the TA muscle often impedes activities of daily living (ADL). Powered ankle exoskeleton is a prevalent technique to treat this pathology, and its intelligent and effecti...

Robotic devices and functional electrical stimulation (FES) are utilized to provide rehabilitation therapy to persons with incomplete spinal cord injury. The goal of the therapy is to improve their weakened voluntary muscle strength. A variety of control strategies used in these therapies need a measure of participant's volitional strength. This in...

Objective: This paper investigates an ultrasound imaging-based non-invasive methodology to quantitatively assess changes in muscle contractility due to the fatigue induced by neuromuscular electrical stimulation (NMES). Methods: Knee extension experiments on human participants were conducted to record synchronized isometric knee force data and u...

Functional electrical stimulation (FES) has been successful in activating paralyzed or paretic muscles to restore limb functions of individuals with impaired gait function. However, when activating the limb joint motion through externally stimulating muscle, rapid onset of muscle fatigue becomes a critical issue that results in injury. To overcome...

In this paper, a robust iterative learning switching controller that uses optimal virtual constraint is designed for a hybrid walking exoskeleton that uses functional electrical stimulation and a powered exoskeleton. The synthesis of iterative learning control with sliding-mode control improves tracking performance and accuracy. The motivation for...

This paper proposes an efficient way of determining analytically the Wrench Closure Workspace (WCW) of spatial redundant cable-driven parallel mechanisms (CDPM). The method builds upon the boundary surface equations obtained from the null space of the structure matrix of CDPM. The set of feasible solutions is obtained that satisfies positive tensio...

This paper proposes an efficient way of determining analytically the Wrench Closure Workspace (WCW) of spatial redundant cable-driven parallel mechanisms (CDPM). The method builds upon the boundary surface equations obtained from the null space of the structure matrix of CDPM. The set of feasible solutions is obtained that satisfies positive tensio...