Jingzhou (James) Yang

• Ph.D.
• Professor at Texas Tech University

Interactive autonomous driving is an evolving research domain that demands an autonomous vehicle (AV) to exhibit adaptability to new environments, cognizance of surrounding traffic conditions, and proficient decision-making ability in complex human-dominated scenarios to guarantee safe navigation and promote social compatibility. This paper reviews...

This paper predicts the optimal motion for a repetitive lifting task considering muscle fatigue. The Denavit-Hartenberg (DH) representation is employed to characterize the two-dimensional (2D) digital human model with 10 degrees of freedom (DOFs). Two joint-based muscle fatigue models, i.e., a three-compartment controller (3CC) muscle fatigue model...

div class="section abstract"> Nonlinearities in mechanical systems pose significant challenges for efficiently solving multi-body dynamics (MBD) problems. Although simulations of traditional mechanisms with perfect joints can be performed efficiently, joints in practical applications are often characterized by clearances, leading to reduced simulat...

Introduction Compartment based models of muscle fatigue have been particularly successful in accurately modeling isometric (static) tasks or actions. However, dynamic actions, which make up most everyday movements, are governed by different central and peripheral processes, and must therefore be modeled in a manner accounting for the differences in...

This study presents a comprehensive finite element model for the human wrist, constructed from a CT scan of a 68-year-old male (type I wrist). This model intricately captures the bone and soft tissue geometries to study the biomechanics of wrist axial loading through tendon-driven simulations and grasping biomechanics using metacarpal loads. Valida...

Estimating muscle forces is crucial for understanding joint dynamics and improving rehabilitation strategies, particularly for patients with neurological disorders who suffer from impaired muscle function. Muscle forces are directly proportional to muscle activations, which can be obtained using electromyography (EMG). EMG-driven modeling estimates...

Human motion has been analyzed for decades based on experimentally collected subject data, serving various purposes, from enhancing athletic performance to assisting patients’ recovery in rehabilitation and many individuals can benefit significantly from study advancements. Human motion prediction, is a more challenging task because no experimental...

This study presents a linear finite element model for the human wrist, constructed from a CT scan of a 68-year-old male (type I wrist). This model intricately captures the bones, soft tissues, and ligaments to study the biomechanics of static grasping by applying pressure loads on the five metacarpals. The results show radial transmission of the lo...

Manual tasks like grasping and aiming require complex coordination between sensory capabilities and motor control. In the presence of obstacles, humans often overestimate the risk associated with collision due to the uncertainty of external stimuli. We present a quantification of the risk factor in multiple manual tasks on the premise that humans c...

The piano is one of the most popular instruments to learn among young musicians due to its versatility. As with any other physical activity, fluid piano performance requires practice to improve technique and reduce the injury risk in long playing sessions. One expert and one intermediate piano player performed three piano playing tasks at three dif...

This study presents a control strategy employing a hybrid backstepping and sliding mode control (BSMC) approach for automated platoons. The control scheme integrates an exponential spacing policy tailored to varying driving conditions and vehicle constraints. We introduce an interval type-2 fuzzy logic system (IT2FLS) to approximate the unknown non...

This paper assessed the weighted vest load arrangement and data normalization method effects on ground reaction forces (GRF), joint kinematics, and joint kinetics during the landing portion of the countermovement jump. Vertical GRF and sagittal kinematic data were obtained from 12 males and 12 females during countermovement jump-landings in 4 diffe...

Skateboarding, once regarded primarily as a means of transportation and entertainment for youth, has become a recognized professional sport, gaining global popularity. With its recent inclusion in the Olympics, a growing imperative exists to comprehensively understand biomechanics explaining skateboarding performance. This literature review seeks t...

In this study, the fatigue progression and optimal motion trajectory during repetitive lifting task is predicted by using a 10 degrees of freedom (DOFs) two-dimensional (2D) digital human model and a three-compartment controller (3CC) fatigue model. The numerical analysis is further validated by conducting an experiment under similar conditions. Th...

Weight tossing is a complex motion that combines multiple manual material handling tasks. The combined motion reduces labor time but comes at the cost of increased physical strain. After the pandemic, workplace injuries have been emerging as a hot potato. The industry spent an astronomical budget on improving workplace safety. It is critical to inv...

This paper presents developing and validating an algorithm-based protocol to build subject-specific musculoskeletal models using X-ray images and motion capture data. The MATLAB algorithm used bilateral X-ray images to determine the deviation angle of each vertebra in the frontal and sagittal planes and motion capture data to define the rest of the...

A novel physics-based human-robot interaction method is proposed and applied to drag the wounded warfighter in the overhead direction in this study. This method predicts the rescue motion using a full-body skeletal model and forward dynamics in OpenSim. The ground reaction force (GRF) is calculated by the contact models in OpenSim, and external for...

Patients with neuromuscular disease fail to produce necessary muscle force and have trouble maintaining joint moment required to perform activities of daily living. Measuring muscle forces in patients with neuromuscular disease is important but challenging. EMG can be used to obtain muscle activation values. EMG-driven modeling with surface electro...

In this study, the dynamic behavior of the vehicle scissor door mechanism with mixed clearance joints is investigated using a novel hybrid nonlinear continuous contact force model. This hybrid contact model is composed of elastic and damping forces, developed based on the improved Winkler elastic foundation model and the Flores model, respectively....

Recently, intelligent control approaches through reinforcement learning have achieved robust performance. The practical complication of reinforcement learning in approximating complex functions is resolved through the introduction of deep learning into the framework. We developed such a deep reinforcement learning-based optimal vehicle cruise contr...

Metabolic energy expenditure (MEE) is an important metric in human performance. Digital human modeling applications can benefit from accurate estimation of MEE during simulated movements. Existing approaches for estimating MEE in a simulated movement are either limited to specific scenarios or involve substantial computational complexity. Our goal...

The durability of commercial vehicles is heavily dependent on the design of their suspension systems’ hard points. The design optimization of hard points involves a large number of design parameters. However, traditional surrogate model-assisted multi-objective optimization (MOO) methods face challenges for high-dimensional problems due to the expe...

Background Understanding wrist biomechanics is important to appreciate and treat the wrist joint. Numerical methods, specifically, finite element method (FEM), have been used to overcome experimental methods' limitations. Due to the complexity of the wrist and difficulty in modeling, there is heterogeneity and lack of consistent methodology in the...

Recent developments in minimally invasive medicine have been fomenting the development of smaller and controllable devices. However, one of the major challenges toward decreasing invasiveness of medical procedures is miniaturizing actuators to milli- or microscale while maintaining reliability. This is the context in which magnetic actuation surfac...

In this study, a 3D asymmetric lifting motion is predicted by using a hybrid predictive model to prevent potential musculoskeletal lower back injuries for asymmetric lifting tasks. The hybrid model has two modules: a skeletal module and an OpenSim musculoskeletal module. The skeletal module consists of a dynamic joint strength based 40 degrees of f...

Driver behavior models have been used as input to self-coaching, accident prevention studies, and developing driver-assisting systems. In recent years, driver behavior recognition has revolutionized autonomous vehicles (AVs) and traffic management studies. This comprehensive survey provides an up-todate review of the different driver behavior model...

Cerebrovascular accidents like a stroke can affect the lower limb as well as upper extremity joints (i.e., shoulder, elbow, or wrist) and hinder the ability to produce necessary torque for activities of daily living. In such cases, muscles’ ability to generate forces reduces, thus affecting the joint’s torque production. Understanding how muscles g...

With the advancement of powerful computational equipment, more detailed finite element models have been developed for the various spine segments. In this study, five detailed finite element models of the cervical spine are developed and validated. The geometric boundaries of the vertebrae are determined from CT scans of five female subjects. The mo...

This study developed an integral coupled sliding mode control (ICSMC) for an automated platoon with exponential spacing policy (ESP) and bidirectional information flow topology. A highly nonlinear and unknown third-order vehicle model was used to represent the actual driving scenario. An adaptive interval type-2 fuzzy logic system (IT2FLS) was appl...

In this study, a hybrid predictive model is used to predict 3D asymmetric lifting motion and assess potential musculoskeletal lower back injuries for asymmetric lifting tasks. The hybrid model has two modules: a skeletal module and an OpenSim musculoskeletal module. The skeletal module consists of a dynamic joint strength based 40 degrees of freedo...

People with neuromuscular deficits may show balance issues that put them in a higher risk of fall as compared to healthy people. To reduce the risk of fall, balance-board (BB)-based rehabilitation intervention has been widely used. However, despite the extensive use of BB-based interventions, the mechanisms responsible for rehabilitation remain unc...

Cerebrovascular accidents like a stroke can affect lower limb as well as upper extremity joints (i.e., shoulder, elbow or wrist) and hinder the ability to produce necessary torque for activities of daily living. In such cases, muscles’ ability to generate force reduces, thus affecting the joint’s torque production. Understanding how muscles generat...

Exoskeleton technology has gained great interests in several fields including robotics, medicine, rehabilitation, ergonomics, and military. Especially, upper-limb exoskeletons are developed aiming to increase worker’s physical ability such as stability, force and power production and reduce biomechanical loads, working fatigue, which relieves overe...

This study developed an integral coupled sliding mode control (ICSMC) for an automated platoon with exponential spacing policy (ESP) and bidirectional information flow topology. A highly nonlinear and unknown third-order vehicle model was used to represent the actual driving scenario. An adaptive interval type-2 fuzzy logic system (IT2FLS) was appl...

In this article, an adaptive approximation-based multi-objective hybrid optimization method, integrating a multi-objective decision-making method, adaptive approximation method and hybrid optimization method, is developed. In particular, a multi-objective decision-making method developed by combining a weight strategy inspired by grey relational an...

Manual material handling is common in daily life and is the main cause of low back pain. Therefore, it is critical to establish a lifting limit for workers. However, it is not practical to obtain each individual’s maximum lifting weight through experiments. The existing simulation models in the literature have only considered static joint strength...

Lifting is a main task for manual material handling (MMH), and it is also associated with lower back pain. There are many studies in the literature on predicting lifting strategies, optimizing lifting motions, and reducing lower back injury risks. This survey focuses on optimization-based biomechanical lifting models for MMH. The models can be clas...

In this study, the three-compartment controller fatigue model is integrated with an inverse dynamics optimization routine to predict the optimal posture, joint fatigue, and endurance time for a box carrying task. The two-dimensional human model employed has 10 degrees of freedom. For the box carrying task, the feet are fixed on the ground, and the...

The three-compartment-controller with enhanced recovery (3CC-r) model of fatigue has been validated, in multiple stages and by different methods, for sustained (SIC) and intermittent isometric contractions (IIC). It has also been validated using a common methodology for both contraction types simultaneously to derive sex-specific representative mod...

This article investigates the headway and optimal velocity tracking of autonomous vehicles (AVs), considering their predictive driving for the stability and integrity of spatial vehicle formation in the platoon. First, the human-like anticipation car-following model is used for modeling the autonomous system. Second, an adaptive radial basis fun...

A previously developed joint-space metabolic energy expenditure (MEE) model includes subject-specific parameters and was validated using level walking gait data. In this work, we determine how well this joint-space model performs during various walking grades (-8%, 0%, and 8%) at 0.8 m·s ⁻¹ and 1.3 m·s ⁻¹ using published gait data in the literature...

Flexible materials embedded with hard magnetic particles have recently gained widespread recognition as small-scale actuators due to their capacity to be a rapid and precise shape-shifting material. Strontium ferrite (SrFe 12 O 19 ) particles have been shown as a great candidate for such applications, since it is an inert hard magnetic material tha...

The slamming acoustic of a vehicle door is objectively not associated to the inherent character of the automobile, however, it is associated to the inherent structure of the vehicle door, which is a vital subjective performance to evaluate the vehicle. Although it has been recognized that static indicators may engender an inferior design result in...

Ergonomics 4.0 is the virtualized implementation of advanced ergonomic tools enabling Industry 4.0. DHM and Digital Twin (DT) by their nature lend themselves to Ergonomics 4.0 and provide a critical element in the framework of Industry 4.0. This introduction to the special issue on Digital Human Modeling in Ergonomics 4.0 establishes a scientific f...

The slamming acoustic of a vehicle door is objectively not associated to the inherent character of the automobile however it is associated to the inherent structure of the vehicle door, which is an vital subjective performance to evaluate the vehicle. Vehicle exterior noise is the air borne noise created by this structural vibration in the slamming...

Occupational Application Digital human models have been widely used for occupational assessments to reduce potential injury risk, such as automotive assembly lines, box lifting, and in the mining industry. Human motion prediction is one of the important capabilities in digital human models, and collision avoidance is involved in human motion predic...

Hail impact on structures such as building envelopes and vehicles can cause huge economic loss every year. Numerical simulation of the hail impact process is crucial for the mitigation strategy development. However, very few research works are focused on the hail impact simulation with impact velocity that falls into the intermediate-velocity range...

Objective: In this study, a novel hybrid predictive musculoskeletal model is proposed which has both motion prediction and muscular dynamics assessment capabilities. Methods: First, a two-dimensional (2D) skeletal model with 10 degrees of freedom is used to predict a symmetric lifting motion, outputting joint angle profiles, ground reaction forc...

The sound quality produced by the door slamming event is one of the significant subjective parameters to evaluate the inherent quality of the vehicle. The vehicle door is mainly composed of fixed door panels and moving glass channels and the sound quality depends on these structural components. This paper proposes a numerical and experimental-based...

Jumping strategies differ considerably depending on athletes' physical activity demands. In general, the jumping motion is desired to have excellent performance and low injury risk. Both of these outcomes can be achieved by modifying athletes' jumping and landing mechanics. This paper presents a consecutive study on the optimization-based subject-s...

OCCUPATIONAL APPLICATIONS Digital human models have been widely used in occupational biomechanics assessments to prevent potential injury risks, such as automotive assembly lines, box lifting, patient repositioning, and the mining industry. Motion prediction is one of the important capabilities in digital human models, and collision avoidance is in...

This research study at a National Science Foundation Research Experience for Undergraduates site focuses on psychological research with applications to the real world. Two cohorts of undergraduates engaged in rigorous research projects on, e.g., driving, homeland security, relationships, human-computer interaction, language comprehension and produc...

This article presents a novel algorithm to predict the shape and the support configurations of a magnetic robot acting like a supple beam which deforms due to an imposed magnetic field. The soft magnet loosely rests on a flat horizontal surface which provides the pivoting supports to the robot to attain its deformed shape. The key difficulty in ana...

The three-compartment controller with enhanced recovery (3CC-r) model of muscle fatigue has previously been validated separately for both sustained (SIC) and intermittent isometric contractions (IIC) using different objective functions, but its performance has not yet been tested against both contraction types simultaneously using a common objectiv...

Transfer path analysis (TPA) method has been widely used in the frequency-domain applications. However, it is not suitable for transient vibration problems such as the abnormal vibration in the automotive door slamming event. In this paper, two time-domain TPA models are used for the abnormal transient vibration diagnosis in the automotive door sla...

Ergonomics 4.0 is the virtualized implementation of advanced ergonomic tools enabling Industry 4.0. DHM and Digital Twin (DT) by their nature lend themselves to Ergonomics 4.0 and provide a critical element in the framework of Industry 4.0. This introduction to the TOEHF special issue provides a comprehensive framework for Ergonomics 4.0/5.0 in the...

Tractor and earth-moving machine rollover has become one of the leading causes of occupational death in the agricultural/constructional industry. Therefore, these machines need proper protective structures to protect operators. In this study, explicit finite element (FE) analysis is adapted to predict the performance of rollover protective structur...

Jumping biomechanics may differ between individuals participating in various sports. Jumping motion can be divided into different phases for research purposes when seeking to understand performance, injury risk, or both. Experimental-based methods are used to study different jumping situations for their capabilities of testing other conditions inte...

This paper presents Part 2 of the assisted spatial sit-to-stand (STS) computational motion prediction to investigate the effect of a unilateral grab-rail bar placed on the right-hand side on STS for injured virtual individuals (computational digital human model-DHM) with either right or left knee injury based on the validated model in Part 1 [3]. I...

Currently available suspension kinematics and compliance (K&C) model is mainly used for qualitative analysis rather than quantitative analysis. In order to reproduce actual suspension K&C characteristic, all the suspension components need to take into account as much details as possible. Suspension stiffness non-linearity, suspension components fri...

Increasing concerns on the compromise between the vehicle ride comfort and roll stability call for the continuous developments of the vehicle suspension systems. This paper devotes a theoretical study in developing a dual-chamber pneumatically interconnected suspension (DCPIS) system to enhance the vehicle ride comfort while maintaining good anti-r...

Box delivery is a complicated task and it is challenging to predict the box delivery motion associated with the box weight, delivering speed, and location. This paper presents a single task-based inverse dynamics optimization method for determining the planar symmetric optimal box delivery motion (multi-task jobs). The design variables are cubic B-...

In this study, the three-dimensional (3D) asymmetric maximum weight lifting is predicted using an inverse-dynamics-based optimization method considering dynamic joint torque limits. The dynamic joint torque limits are functions of joint angles and angular velocities, and imposed on the hip, knee, ankle, wrist, elbow, shoulder, and lumbar spine join...

Hand-grip function while lifting objects is essential for performing everyday tasks. The Box and Block Test (BBT) has been used to assess hand-grip function and dexterity, but only light objects have been used. The purpose of this study was to investigate effects of block surface, shape, age, and sex on hand dexterity during the movement of heavy b...

Box delivery is a complicated manual material handling task which needs to consider the box weight, delivering speed, stability, and location. This paper presents a subtask-based inverse dynamic optimization formulation for determining the two-dimensional (2D) symmetric optimal box delivery motion. For the subtask-based formulation, the delivery ta...

Symmetric lifting is a common manual material handling strategy in daily life and is the main cause of low back pain. In the literature, symmetric lifting is mainly simulated by using two-dimensional (2D) models because of their simplicity and low computational cost. In practice, however, symmetric lifting can generate asymmetric kinetics especiall...

In this study, a 40 degrees of freedom (DOFs) spatial skeletal model was employed to predict the symmetric maximum weight lifting motion. The lifting problem was formulated as a multi-objective optimization (MOO) problem to minimize the dynamic effort and maximize the box weight. An inverse-dynamics-based optimization approach was used to determine...

Background The ankle-strategy model, where the human body is modeled as a single inverted pendulum hinged at the ankle, has been used for decades to study the dynamics and the stability of the human upright posture (UP). However, the contribution of the hip joints is critical whenever postural disturbances are considered. To account for hip contrib...

Sit-to-stand (STS) motion is a key determinant of functional independence for the senior people. This paper extends a predictive dynamics formulation previously reported to predict the assisted STS motion, i.e., the motion with a mechanical assistance, unilateral grab-rail bar which is placed on the right side of the virtual-individuals with a vert...

Cycling is a widely popular exercise that is known to provide great health benefits. However, it has been questioned if cycling is responsible for genital numbness or Erectile Dysfunction (ED) due to compression of the perineum between the rider and the bicycle saddle. This study compares the perineal pressure distribution between three saddles (IS...

Human hands play a key role in almost all activities of daily living (ADLs) because it is an incredibly versatile tool capable of complex motion. For individuals who have had a complete loss of the hand, the ability to perform ADLs is impaired. Effective prosthetics accurately simulate the movements of a human hand by providing a high number of deg...

Handle driving forces are the input of the automotive sliding door dynamic system and play an important role for ensuring a smooth closing process during manual sliding door mechanism design. It is important to provide a reliable and accurate input for the manual sliding door mechanism during the design and analysis stage. This paper aims to presen...

Sit-to-stand (STS) motion is one of the most important tasks in daily life and is one of the key determinants of functional independence, especially for the senior people. The STS motion has been extensively studied in the literature, mostly through experiments. Compared to numerous experimental studies, there are limited simulations with mostly as...

This article presents an optimization formulation and experimental validation of a dynamic-joint-strength-based two-dimensional symmetric maximum weight-lifting simulation. Dynamic joint strength (the net moment capacity as a function of joint angle and angular velocity), as presented in the literature, is adopted in the optimization formulation to...

This study investigated methods for rapidly repositioning the 3D finite element (FE) representations of Individualized Avatar with Complete Anatomy (IAVCA) recently developed. Repositioning posed three distinct challenges: (1) each individualized avatar has a unique surface and FE structure; (2) user expectation is for rapid execution; and (3) the...

This paper investigates the effect of postural disturbances and sensorimotor deficits on the robustness of the upright posture (UP) for a human body model balancing on a balance board (BB). The robustness is investigated by computing the gradient field along the basin of attraction (BoA) of an asymptotically stable equilibrium point. The human mode...

Manual material handling is common in daily life and is the main cause of lower back pain. Therefore, it is critical to establish a lifting limit for workers. However, it is difficult to obtain each individual's maximum lifting weight through experiments. This study presents a multi-objective optimization (MOO) for two-dimensional maximum weight li...

Current models of localized muscular fatigue are capable of predicting performance in isometric tasks with reasonable accuracy. However, they do not account for the effect of continuously-varying task intensities on muscular recovery from a fatigued state. In this work, we propose and evaluate three continuous functions for modelling recovery to re...

Noncontact lower extremity injuries are commonly related to jumping and landing activities. This review presents an overview of relevant biomechanical variables that can be modified in training to improve jumping performance, landing mechanics, and consequently, reduce injury risks. Relevant studies from the last 2 decades in the Compendex, Pubmed,...

In mechanisms, the guide and roller form joints with clearance and the roller may make contact with the convex surface or concave surface of the guide. Correctly modeling this type of joint is critical in a mechanism's dynamic performance analysis. This paper proposes a contact kinematic model and a hybrid contact force model for the planar joint a...

This paper investigates the effects of the ankle-BB misalignment and upward ankle vertical displacement on stability and equilibrium location through bifurcation analyses performed to the ankle-hip model of balance on a balance board developed in our previous work. By using local bifurcation analyses, we have obtained the stability regions of the u...

Study Design Prospective, concurrent-cohort study. Objectives To determine the effects of volitional preemptive abdominal contraction (VPAC) on trunk control during an asymmetric lift in patients with recurrent low back pain (rLBP) and compare with matched controls. Methods Thirty-two rLBP patients and 37 healthy controls performed asymmetric lif...

Humans are daily presented with tasks that they complete with little effort of even consideration of the planning that goes into the movement. Movements such as manual manipulation tasks are completed with ease, even though the complexities and years of learned behavior are largely hidden from the person. Digital human modeling (DHM) and specifical...

Stroke is one of the leading causes of upper extremity disability around the world. Whenever a stroke happens stroke survivor’s brain commands cannot reach some muscles of upper extremities although those muscles could contract. Therefore, shoulder, elbow or wrist joint cannot perform expected motion, and this will hamper their activities of daily...

This paper describes an integrated approach to predict human leg and spine muscle forces during lifting by integration of a predictive skeletal model with OpenSim. The two-dimensional (2D) skeletal lifting motion is first predicted by using an inverse dynamics optimization method. Then, the prediction outputs, including joint angle profiles, ground...

People who have suffered a transtibial amputation show diminished ambulation and impaired quality of life. Powered ankle foot prostheses (AFP) are used to recover some mobility of transtibial amputees (TTAs). Powered AFP is an emerging technology that has great potential to improve the quality of life of TTAs with important avenues for research and...