scholarly journals Just noticeable differences for elbow joint torque feedback

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hubert Kim ◽  
Alan T. Asbeck
Keyword(s):  
Elbow Joint ◽  
Spatial Information ◽  
Dynamic Condition ◽  
Pressure Sensors ◽  
Static Condition ◽  
Joint Torque ◽  
Just Noticeable Difference ◽  
Joint Torques ◽  
Static Conditions ◽  
Joint Torque Feedback

AbstractJoint torque feedback is a new and promising means of kinesthetic feedback imposed by a wearable device. The torque feedback provides the wearer temporal and spatial information during a motion task. Nevertheless, little research has been conducted on quantifying the psychophysical parameters of how well humans can perceive external torques under various joint conditions. This study aims to investigate the just noticeable difference (JND) perceptual ability of the elbow joint to joint torques. The paper focuses on the ability of two primary joint proprioceptors, the Golgi-tendon organ (GTO) and muscle spindle (MS), to detect elbow torques, since touch and pressure sensors were masked. We studied 14 subjects while the arm was isometrically contracted (static condition) and was moving at a constant speed (dynamic condition). In total there were 10 joint conditions investigated, which varied the direction of the arm’s movement and the preload direction as well as torque direction. The JND torques under static conditions ranged from 0.097 Nm with no preload to 0.197 Nm with a preload of 1.28 Nm. The maximum dynamic JND torques were 0.799 Nm and 0.428 Nm, when the arm was flexing and extending at 213 degrees per second, respectively.

Development of upper cycling clothes using 3D-to-2D flattening technology and evaluation of dynamic wear comfort from the aspect of clothing pressure

2016 ◽  
Vol 28 (6) ◽  
pp. 736-749 ◽  
Author(s):  
Kaixuan Liu ◽  
Jianping Wang ◽  
Chun Zhu ◽  
Yan Hong
Keyword(s):  
Dynamic Condition ◽  
Dynamic Pressure ◽  
Static Condition ◽  
Measuring Method ◽  
3D Animation ◽  
Content Type ◽  
Wear Comfort ◽  
Clothing Pressure ◽  
Static Conditions ◽  
Dynamic Wear

Purpose Currently, the researches on garment development and wear comfort evaluation mainly focus on the static condition type and seldom involved dynamic condition. Therefore, the purpose of this paper is to develop cycling clothes’ patterns and evaluate their dynamic wear comfort. Design/methodology/approach First, the 3D-to-2D flattening technology was applied to develop garment patterns of a cycler’s jersey T-shirt. Then, 3D animation technology was used to simulate the scene of cycling. Next, a novel pressure-measuring method was proposed to measure static and dynamic clothing pressures in a virtual environment. Finally, the collected data were used for evaluating wear comfort. Findings Compared to static conditions, the dynamic wear comfort noticeably improved at the front neck, side neck, upper front chest, around back neck point and front shoulder, and the front neck. Compared to static conditions, the dynamic wear comfort visibly deteriorates at the back neck, below chest, outseam, back except around back neck point and around scapula, and the around scapula area. The dynamic pressure at back neck, below front chest and shoulder fluctuate wildly throughout the whole cycling. On the contrary, the dynamic pressure at the front neck, side neck, front upper chest and at the back cause it to tend to stability during cycling. Originality/value The 3D virtual-reality technology was applied to simulate cycling. And a novel method was proposed to measure numerical clothing pressures for evaluating the dynamic wear comfort. The proposed method can not only quantitatively evaluate the wear comfort of cycling clothes and optimize cycling clothes’ patterns, but also can be applied to other tight garment types.

scholarly journals Behavior of Elastic Therapeutic Tapes under Dynamic and Static Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Hermela Ejegu ◽  
Bipin Kumar ◽  
Priyanka Gupta
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Internal Stress ◽  
Dynamic Condition ◽  
Physical And Mechanical Properties ◽  
Static Condition ◽  
Strain Rates ◽  
Lower Strain Rate ◽  
Lower Strain ◽  
Static Conditions

The aim of this paper is to determine the relaxation behavior of the therapeutic tape under different thermomechanical conditions over different time spans and to analyze the physical and mechanical properties of selected kinesiology tapes. The relaxation test was conducted under a static condition with two extended levels (25% and 50%) for one hour and a dynamic condition for 300 cycles with different loading-unloading values, strain rates, and temperatures. For both static and dynamic conditions, at a lower strain rate and higher load and temperature, the therapeutic tapes showed higher loss of internal stress and faster losses of efficiency. Under all selected conditions, the tape’s stress has decreased rapidly.

scholarly journals Upper-Limb Isometric Force Feasible Set: Evaluation of Joint Torque-Based Models

Biomechanics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 102-117
Author(s):  
Nasser Rezzoug ◽  
Vincent Hernandez ◽  
Philippe Gorce
Keyword(s):  
Upper Limb ◽  
Isometric Force ◽  
Joint Torque ◽  
Force Distribution ◽  
Prediction Errors ◽  
Feasible Set ◽  
Joint Torques ◽  
Motor Abilities ◽  
Capacity Evaluation ◽  
Measured Force

A force capacity evaluation for a given posture may provide better understanding of human motor abilities for applications in sport sciences, rehabilitation and ergonomics. From data on posture and maximum isometric joint torques, the upper-limb force feasible set of the hand was predicted by four models called force ellipsoid, scaled force ellipsoid, force polytope and scaled force polytope, which were compared with a measured force polytope. The volume, shape and force prediction errors were assessed. The scaled ellipsoid underestimated the maximal mean force, and the scaled polytope overestimated it. The scaled force ellipsoid underestimated the volume of the measured force distribution, whereas that of the scaled polytope was not significantly different from the measured distribution but exhibited larger variability. All the models characterized well the elongated shape of the measured force distribution. The angles between the main axes of the modelled ellipsoids and polytopes and that of the measured polytope were compared. The values ranged from 7.3° to 14.3°. Over the entire surface of the force ellipsoid, 39.7% of the points had prediction errors less than 50 N; 33.6% had errors between 50 and 100 N; and 26.8% had errors greater than 100N. For the force polytope, the percentages were 56.2%, 28.3% and 15.4%, respectively.

scholarly journals Postural Control Disturbances Induced by Virtual Reality in Stroke Patients

2021 ◽  
Vol 11 (4) ◽  
pp. 1510
Author(s):  
Charles Morizio ◽  
Maxime Billot ◽  
Jean-Christophe Daviet ◽  
Stéphane Baudry ◽  
Christophe Barbanchon ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Postural Control ◽  
Virtual Environments ◽  
Center Of Pressure ◽  
Dynamic Condition ◽  
Static Condition ◽  
Stroke Patients ◽  
Post Stroke ◽  
Subacute Stroke

People who survive a stroke are often left with long-term neurologic deficits that induce, among other impairments, balance disorders. While virtual reality (VR) is growing in popularity for postural control rehabilitation in post-stroke patients, studies on the effect of challenging virtual environments, simulating common daily situations on postural control in post-stroke patients, are scarce. This study is a first step to document the postural response of stroke patients to different challenging virtual environments. Five subacute stroke patients and fifteen age-matched healthy adults were included. All participants underwent posturographic tests in control conditions (open and closed eyes) and virtual environment without (one static condition) and with avatars (four dynamic conditions) using a head-mounted device for VR. In dynamic environments, we modulated the density of the virtual crowd (dense and light crowd) and the avoidance space with the avatars (near or far). Center of pressure velocity was collected by trial throughout randomized 30-s periods. Results showed that more challenging conditions (dynamic condition) induced greater postural disturbances in stroke patients than in healthy counterparts. Our study suggests that virtual reality environments should be adjusted in light of obtaining more or less challenging conditions.

scholarly journals Joint torque and velocity optimization for a redundant leg of quadruped robot

2017 ◽  
Vol 14 (5) ◽  
pp. 172988141773189 ◽  
Author(s):  
Taihui Zhang ◽  
Honglei An ◽  
Hongxu Ma
Keyword(s):  
Angular Velocity ◽  
Sagittal Plane ◽  
Load Capacity ◽  
Optimization Criterion ◽  
Quadruped Robot ◽  
Joint Torque ◽  
Quadratic Program ◽  
Hydraulic Actuator ◽  
Joint Torques ◽  
Physical Limitations

Hydraulic actuated quadruped robot similar to BigDog has two primary performance requirements, load capacity and walking speed, so that it is necessary to balance joint torque and joint velocity when designing the dimension of single leg and controlling its motion. On the one hand, because there are three joints per leg on sagittal plane, it is necessary to firstly optimize the distribution of torque and angular velocity of every joint on the basis of their different requirements. On the other hand, because the performance of hydraulic actuator is limited, it is significant to keep the joint torque and angular velocity in actuator physical limitations. Therefore, it is essential to balance the joint torque and angular velocity which have negative correlation under the condition of constant power of the hydraulic actuator. The main purpose of this article is to optimize the distribution of joint torques and velocity of a redundant single leg with joint physical limitations. Firstly, a modified optimization criterion combining joint torques with angular velocity that takes both support phase and flight phase into account is proposed, and then the modified optimization criterion is converted into a normal quadratic programming problem. A kind of recurrent neural network is used to solve the quadratic program problem. This method avoids tremendous matrix inversion and fits for time-varying system. The achieved optimized distribution of joint torques and velocity is useful for aiding mechanical design and the following motion control. Simulation results presented in this article confirm the efficiency of this optimization algorithm.

Physics-Based Seated Posture Prediction for Pregnant Women and Validation Considering Ground and Seat Pan Contacts

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Bradley Howard ◽  
Aimee Cloutier ◽  
Jingzhou (James) Yang
Keyword(s):  
Pregnant Women ◽  
Objective Function ◽  
Linear Regression Analysis ◽  
Joint Torque ◽  
Joint Torques ◽  
Design Variables ◽  
Optimization Formulation ◽  
Posture Prediction ◽  
Seated Posture ◽  
End Effectors

An understanding of human seated posture is important across many fields of scientific research. Certain demographics, such as pregnant women, have special postural limitations that need to be considered. Physics-based posture prediction is a tool in which seated postures can be quickly and thoroughly analyzed, as long the predicted postures are realistic. This paper proposes and validates an optimization formulation to predict seated posture for pregnant women considering ground and seat pan contacts. For the optimization formulation, the design variables are joint angles (posture); the cost function is dependent on joint torques. Constraints include joint limits, joint torque limits, the distances from the end-effectors to target points, and self-collision avoidance constraints. Three different joint torque cost functions have been investigated to account for the special postural characteristics of pregnant women and consider the support reaction forces (SRFs) associated with seated posture. Postures are predicted for three different reaching tasks in common reaching directions using each of the objective function formulations. The predicted postures are validated against experimental postures obtained using motion capture. A linear regression analysis was used to evaluate the validity of the predicted postures and was the criteria for comparison between the different objective functions. A 56 degree of freedom model was used for the posture prediction. Use of the objective function minimizing the maximum normalized joint torque provided an R2 value of 0.828, proving superior to either of two alternative functions.

Establishment of a resazurin-based aortic valve tissue viability assay for dynamic culture in a microphysiological system

2021 ◽  
pp. 1-12
Author(s):  
C. Dittfeld ◽  
M. Winkelkotte ◽  
S. Behrens ◽  
F. Schmieder ◽  
A. Jannasch ◽  
...  
Keyword(s):  
Aortic Valve ◽  
Dynamic Condition ◽  
Thermoplastic Polyurethane ◽  
Membrane Integrity ◽  
Tissue Viability ◽  
Preliminary Results ◽  
Dynamic Culture ◽  
Resazurin Assay ◽  
Static Conditions

BACKGROUND/AIM: Tissue pathogenesis of aortic valve (AV) stenosis is research focus in cardiac surgery. Model limitations of conventional 2D culture of human or porcine valvular interstitial/endothelial cells (VIC/VECs) isolated from aortic valve tissues but also limited ability of (small) animal models to reflect human (patho)physiological situation in AV position raise the need to establish an in vitro setup using AV tissues. Resulting aim is to approximate (patho)physiological conditions in a dynamic pulsatile Microphysiological System (MPS) to culture human and porcine AV tissue with preservation of tissue viability but also defined ECM composition. MATERIALS/METHODS: A tissue incubation chamber (TIC) was designed to implement human or porcine tissues (3×5 mm) in a dynamic pulsatile culture in conventional cell culture ambience in a MPS. Cell viability assays based on lactate dehydrogenase (LDH)-release or resazurin-conversion were tested for applicability in the system and applied for a culture period of 14 days with interval evaluation of tissue viability on every other day. Resazurin-assay setup was compared in static vs. dynamic culture using varying substance saturation settings (50–300μM), incubation times and tissue masses and was consequently adapted. RESULTS: Sterile dynamic culture of human and porcine AV tissue segments was established at a pulsatile flow rate range of 0.9–13.4μl/s. Implementation of tissues was realized by stitching the material in a thermoplastic polyurethane (TPU) –ring and insertion in the TIC-MPS-system. Culture volume of 2 ml caused LDH dilution not detectable in standard membrane integrity assay setup. Therefore, detection of resazurin-conversion of viable tissue was investigated. Optimal incubation time for viability conversion was determined at two hours at a saturated concentration of 300μM resazurin. Measurement in static conditions was shown to offer comparable results as dynamic condition but allowing optimal handling and TIC sterilization protocols for long term culture. Preliminary results revealed favourable porcine AV tissue viability over a 14 day period confirmed via resazurin-assay comparing statically cultured tissue counterparts. CONCLUSIONS: Human and porcine AV tissue can be dynamically cultured in a TIC-MPS with monitoring of tissue viability using an adapted resazurin-assay setup. Preliminary results reveal advantageous viability of porcine AV tissues after dynamic TIC-MPS culture compared to static control.

Electrochemical Kinetic of a Low Carbon Steel in Seawater at Different Flow Speed

2015 ◽  
Vol 1766 ◽  
pp. 73-80
Author(s):  
A. Carmona ◽  
R. Orozco-Cruz ◽  
E. Mejía-Sánchez ◽  
A. Contreras ◽  
R. Galván-Martínez
Keyword(s):  
Turbulent Flow ◽  
Rotation Speed ◽  
Electrochemical Impedance ◽  
Static Condition ◽  
Flow Speed ◽  
Localized Corrosion ◽  
Low Carbon ◽  
Flow Conditions ◽  
Static Conditions ◽  
Turbulent Flow Conditions

ABSTRACTAn electrochemical impedance spectroscopy (EIS) corrosion study of API X70 steel was carried out in synthetic seawater with different rotation speeds using a rotating cylinder electrode (RCE) to control the hydrodynamic conditions at room temperature, atmospheric pressure and 24 h of exposure time. A superficial analysis through a scanning electron microscope (SEM) was used to analyze the corrosion type. The rotation speed used was 0 rpm (static condition), 1000, 3000 and 5000 rpm (turbulent flow). The results show that the turbulent flow conditions affect directly the corrosion rate (CR) of the steel, because all values of the CR under turbulent flow conditions are higher than the CR values at static conditions. In addition, it is important to point out that at turbulent flow conditions, the CR increased as the rotation speed also increased. The morphology of the corrosion in all experiments was localized corrosion.

scholarly journals Lower Extremity Motor Impairments in Ambulatory Chronic Hemiparetic Stroke: Evidence for Lower Extremity Weakness and Abnormal Muscle and Joint Torque Coupling Patterns

2017 ◽  
Vol 31 (9) ◽  
pp. 814-826 ◽  
Author(s):  
Natalia Sánchez ◽  
Ana Maria Acosta ◽  
Roberto Lopez-Rosado ◽  
Arno H. A. Stienen ◽  
Julius P. A. Dewald
Keyword(s):  
Lower Extremity ◽  
Degrees Of Freedom ◽  
Joint Torque ◽  
Motor Impairments ◽  
Lower Extremity Weakness ◽  
Joint Torques ◽  
Hemiparetic Stroke ◽  
Chronic Hemiparetic Stroke ◽  
Hip Extension ◽  
Flexion And Extension

Although global movement abnormalities in the lower extremity poststroke have been studied, the expression of specific motor impairments such as weakness and abnormal muscle and joint torque coupling patterns have received less attention. We characterized changes in strength, muscle coactivation and associated joint torque couples in the paretic and nonparetic extremity of 15 participants with chronic poststroke hemiparesis (age 59.6 ± 15.2 years) compared with 8 age-matched controls. Participants performed isometric maximum torques in hip abduction, adduction, flexion and extension, knee flexion and extension, ankle dorsi- and plantarflexion and submaximal torques in hip extension and ankle plantarflexion. Surface electromyograms (EMGs) of 10 lower extremity muscles were measured. Relative weakness (paretic extremity compared with the nonparetic extremity) was measured in poststroke participants. Differences in EMGs and joint torques associated with maximum voluntary torques were tested using linear mixed effects models. Results indicate significant poststroke torque weakness in all degrees of freedom except hip extension and adduction, adductor coactivation during extensor tasks, in addition to synergistic muscle coactivation patterns. This was more pronounced in the paretic extremity compared with the nonparetic extremity and with controls. Results also indicated significant interjoint torque couples during maximum and submaximal hip extension in both extremities of poststroke participants and in controls only during maximal hip extension. Additionally, significant interjoint torque couples were identified only in the paretic extremity during ankle plantarflexion. A better understanding of these motor impairments is expected to lead to more effective interventions for poststroke gait and posture.

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