scholarly journals A Reconfigurable Multiplanar In Vitro Simulator for Real-Time Absolute Motion With External and Musculotendon Forces

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Joshua T. Green ◽  
Rena F. Hale ◽  
Jerome Hausselle ◽  
Roger V. Gonzalez
Keyword(s):  
Real Time ◽  
Degrees Of Freedom ◽  
Hybrid Control ◽  
Dynamic Control ◽  
El Paso ◽  
University Of Texas ◽  
Absolute Motion ◽  
Joint Load ◽  
Accuracy And Repeatability

Advancements in computational musculoskeletal biomechanics are constrained by a lack of experimental measurement under real-time physiological loading conditions. This paper presents the design, configuration, capabilities, accuracy, and repeatability of The University of Texas at El Paso Joint Load Simulator (UTJLS) by testing four cadaver knee specimens with 47 real-time tests including heel and toe squat maneuvers with and without musculotendon forces. The UTJLS is a musculoskeletal simulator consisting of two robotic manipulators and eight musculotendon actuators. Sensors include eight tension load cells, two force/torque systems, nine absolute encoders, and eight incremental encoders. A custom control system determines command output for position, force, and hybrid control and collects data at 2000 Hz. Controller configuration performed forward-dynamic control for all knee degrees-of-freedom (DOFs) except knee flexion. Actuator placement and specimen potting techniques uniquely replicate muscle paths. Accuracy and repeatability standard deviations across specimen during squat simulations were equal or less than 8 N and 5 N for musculotendon actuators, 30 N and 13 N for ground reaction forces (GRFs), and 4.4 N·m and 1.9 N·m for ground reaction moments. The UTJLS is the first of its design type. Controller flexibility and physical design support axis constraints to match traditional testing rigs, absolute motion, and synchronous real-time simulation of multiplanar kinematics, GRFs, and musculotendon forces. System DOFs, range of motion, and speed support future testing of faster maneuvers, various joints, and kinetic chains of two connected joints.

Validation of a Novel In-Vitro Simulator for Real-Time Control of Active Shoulder Movements in Various Planes of Motion

2013 ◽  
Author(s):  
J. W. Giles ◽  
L. M. Ferreira ◽  
G. S. Athwal ◽  
J. A. Johnson
Keyword(s):  
Real Time ◽  
Degrees Of Freedom ◽  
A Priori ◽  
Axial Rotation ◽  
Open Loop ◽  
Abduction Angle ◽  
Real Time Control ◽  
Loop Control ◽  
Shoulder Motion

In-vitro simulation of active shoulder joint motion is critical to gaining an understanding of the effects of surgical procedures and implant designs. However, development of systems for the accurate simulation of active shoulder motion has lagged well behind those implemented for the lower limb and elbow, which have used principles of closed-loop joint angle control 1,4. In contrast, active shoulder motion has been confined to simulators that can hold static joint angles through the application of loads based on computer model outputs 2, or that use constant velocity of the middle deltoid while using open-loop control to apportion other muscle loads as a function of a-priori physiologic loading ratios 3. Neither of these schemes utilizes real-time feedback of kinematic data in order to follow smooth, predefined profiles. The lack of more refined shoulder simulators, based on control theory, can primarily be attributed to the complexity of shoulder motion and the number of degrees of freedom (DOFs) ( i.e. plane of abduction, abduction angle, and axial rotation) which must be controlled.

scholarly journals Real-Time in-Vitro Evaluation of Knee Kinematics Using Enriched Computed Tomography Data

10.29007/flk2 ◽  
2018 ◽  
Author(s):  
Matthias Verstraete ◽  
Nele Arnout ◽  
Patrick De Baets ◽  
Thibeau Vancouillie ◽  
Tom Van Hoof ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Real Time ◽  
Degrees Of Freedom ◽  
Knee Kinematics ◽  
In Vitro Evaluation ◽  
Golden Standard ◽  
Infrared Cameras ◽  
Real Time Information ◽  
Registration Phase

In vitro evaluation of knee kinematics remains an essential part during pre-clinical testing of new implants and surgical procedures. To assess the kinematics, markers are rigidly attached to the bone segments and tracked using infrared cameras. Subsequently, the position of the markers relative to the bone is determined using computed tomography (CT). Although the accuracy of the aforementioned, CT-based method is not doubted, no real-time information is provided. Therefore, this paper presents a real-time method that uses a registration phase in combination with a pre-operative CT scan to determine the location of the bone relative to the markers. During this registration phase, the bone surface location is identified touching surface points with a tracked pen. The kinematic parameters obtained using this real-time method is compared to the golden standard, CT-based, method. Under optimal conditions, rotational and translational differences around 1mm and 1degree are obtained. This is in the range of the inter- and intra- observer variability in determining the landmarks used for these kinematic calculations. It is therefore concluded that the accuracy of the real-time method allows effectively evaluating the knee kinematics in six degrees of freedom.

Adaptive Hybrid Control Algorithm With Iterative Learning for Robotic In Vitro Biomechanical Testing of Spine

2012 ◽  
Author(s):  
T. F. Bonner ◽  
L. Gilbertson ◽  
R. W. Colbrunn
Keyword(s):  
Control Algorithm ◽  
Degrees Of Freedom ◽  
Hybrid Control ◽  
Dynamic Testing ◽  
Biomechanical Testing ◽  
Testing Methods ◽  
Robotic Technology ◽  
Control Schemes ◽  
Pure Moment

In spine testing, methods have been developed to apply pure moments to a single axis of the spine to elucidate the mechanical properties of the spine. The application of those concepts continues to be applied with custom loading frames, custom robotics systems, and adaptation of commercial robotic technology. With these systems and pure moment testing, spinal biomechanics variables such as the neutral zone and range of motion can be determined. As more complex testing systems with higher degrees of freedom (DOF) capabilities are developed, dynamic testing becomes a possibility. However, these more complex testing systems require more complex control schemes.

INTERVAL METHODS IN KNOWLEDGE REPRESENTATION

2004 ◽  
Vol 12 (04) ◽  
pp. 557-558
Author(s):  
VLADIK KREINOVICH
Keyword(s):  
Knowledge Representation ◽  
Computer Science ◽  
El Paso ◽  
Interval Methods ◽  
University Of Texas

This section is maintained by Vladik Kreinovich. Please send your abstracts (or copies of papers that you want to see reviewed here) to [email protected], or by regular mail to: Vladik Kreinovich, Department of Computer Science, University of Texas at El Paso, El Paso, TX 79968, USA.

scholarly journals Real-time monitoring of liver fibrosis through embedded sensors in a microphysiological system

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Hafiz Muhammad Umer Farooqi ◽  
Bohye Kang ◽  
Muhammad Asad Ullah Khalid ◽  
Abdul Rahim Chethikkattuveli Salih ◽  
Kinam Hyun ◽  
...  
Keyword(s):  
Cell Culture ◽  
Liver Fibrosis ◽  
Real Time ◽  
Hepatic Fibrosis ◽  
Transforming Growth Factor ◽  
Cell Monolayer ◽  
Embedded Sensors ◽  
Matrix Deposition ◽  
Tgf Β1

AbstractHepatic fibrosis is a foreshadowing of future adverse events like liver cirrhosis, liver failure, and cancer. Hepatic stellate cell activation is the main event of liver fibrosis, which results in excessive extracellular matrix deposition and hepatic parenchyma's disintegration. Several biochemical and molecular assays have been introduced for in vitro study of the hepatic fibrosis progression. However, they do not forecast real-time events happening to the in vitro models. Trans-epithelial electrical resistance (TEER) is used in cell culture science to measure cell monolayer barrier integrity. Herein, we explored TEER measurement's utility for monitoring fibrosis development in a dynamic cell culture microphysiological system. Immortal HepG2 cells and fibroblasts were co-cultured, and transforming growth factor β1 (TGF-β1) was used as a fibrosis stimulus to create a liver fibrosis-on-chip model. A glass chip-based embedded TEER and reactive oxygen species (ROS) sensors were employed to gauge the effect of TGF-β1 within the microphysiological system, which promotes a positive feedback response in fibrosis development. Furthermore, albumin, Urea, CYP450 measurements, and immunofluorescent microscopy were performed to correlate the following data with embedded sensors responses. We found that chip embedded electrochemical sensors could be used as a potential substitute for conventional end-point assays for studying fibrosis in microphysiological systems.

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