Smart knee prosthesis kinematics estimation and validation in a robotic knee simulator

In this work we present the smart knee prosthesis designed for in-vivo kinematics measurement and its validation in two knee simulators, i.e. a robotic knee simulator to provide realistic condition, and a manual simulator with more degrees of freedom. The sensor configuration including three magnetic sensors was designed, and the machine learning techniques were used to translate the magnetic measurements to knee rotations. First the concurrent flexion-extension and internal-external rotations were estimated via linear and nonlinear estimators, and technically validated in a manual knee simulator against motion capture system. Then the flexion-extension estimation was validated in a robotic knee simulator providing the realistic sagittal kinematics of treadmill and over-ground walking. The obtained results showed the high accuracy and precision of the estimates

Accurate angle estimation in smart knee prostheses via magnetic implantable and skin-mounted sensors

In this work we investigated how to measure concurrently flexion-extension and internal-external rotations in a smart knee prosthesis. A configuration of magnetic sensors and magnets were designed and embedded in knee prostheses in which each sensor measures a mixture of information related to both rotations. Using correlation analyses, angle estimators were designed to separate the flexion-extension and internal-external rotations information. The estimators were validated in a mechanical knee simulator towards a reference system. The effect of imposed abduction-adduction was also analyzed on the estimations performances. To reduce the power consumption of the internal system, we reduced the sampling rate and duty cycled the sensors and compensated the lack of information with skin-mounted sensors on four subjects. The fusion between implantable and skin-mounted sensors drastically improved the flexion-extension angle estimation, but not the internal-external estimation

Smart Knee Prosthesis for Orthopedic Surgery: the implantable and wearable Measurement System

Recent advances in remote powering and telemetry permitted the use of sensors inside body. A few studies have been already done on smart knee prostheses, but all focused on monitoring the in-vivo contact forces and moments. A smart design, compatible with mechanical structure of commercially-available knee prostheses, that provides force and accurate kinematics feedback was suggested with all electronics housed in the polyethylene insert (PE). The current work addresses the designed kinematics and force measurement system of that smart implant and its validation in a robotic knee simulator

An Implantable System for Angle Measurement in Prosthetic Knee

In this work we designed and tested an in-vivo measurement system of prosthetic knee joint angles. The system included a small permanent magnet in the femoral part and three magneto resistance sensors placed in the polyethylene part. The sensor configuration was defined based on sensitivity analysis, signal to noise ratio, saturation of sensors and movements constraints. A mapping algorithm was designed to estimate the orientation of the femoral part in sagittal and coronal plane. For validation the prosthesis was placed in a mechanical simulator equipped with reflective markers tracked by optical motion capture

Real Time Emotional Control for Anti-Swing and Positioning Control of SIMO Overhead Traveling Crane

Jamali MR, Arami A, Hosseini B, Moshiri B, Lukas C. Real Time Emotional Control for Anti-Swing and Positioning Control of SIMO Overhead Traveling Crane. International Journal of Innovative Computing, Information, and Control. 2008;4(9):2333-2344

Direct characterization of gas adsorption and phase transition of a metal organic framework using in-situ Raman spectroscopy

Adsorbents are widely used in gas separation and storage processes. Performance improvements are largely achieved through the continual development of new materials with unique sorption properties. Adsorption characterization techniques, therefore, play a central role in material research and development. Here, in-situ Raman spectroscopy is presented as a multi-purpose laboratory tool for analyzing adsorption performance. In contrast to conventional laboratory techniques requiring macroscopic samples, adsorption analysis via Raman spectroscopy can be performed on samples of less than 1 mg. Furthermore, simultaneous Raman multi-phase measurements of the adsorbent structure as well as the free and bound adsorbate, are shown to provide molecular insights into the operation of functional adsorbents at conditions representative of industrial applications, which are often not attainable in conventional crystallography. Firstly, a Raman-based method is demonstrated for directly quantifying absolute adsorption capacity within individual particles. The technique is validated for Raman measurements of carbon dioxide on silica gel and compared to gravimetric and volumetric analyses. Secondly, Raman spectroscopy is applied to study a novel functional material, ZIF-7, and directly probe its pressure-regulated gate-opening mechanism, which was only observed through indirect means. These Raman measurements confirm that the sharp increase in capacity corresponds to a structural transition in the material and reveal that multiple adsorption sites contribute to the overall capacity. The Raman methods presented here can be applied to a wide range of adsorbent-adsorbate systems and present a basis for further studies into the kinetics of sorption processes

Cryogenic Solid Solubility Measurements for HFC-32 + CO2 Binary Mixtures at Temperatures Between (132 and 217) K

Accurate phase equilibrium data for mixtures of eco-friendly but mildly-flammable refrigerants with inert components like CO2 will help the refrigeration industry safely employ working fluids with 80 % less global warming potential than those of many widely-used refrigerants. In this work, a visual high-pressure measurement setup was used to measure solid–fluid equilibrium (SFE) of HFC-32 + CO2 binary systems at temperatures between (132 and 217) K. The experimental data show a eutectic composition of around 11 mol % CO2 with a eutectic temperature of 131.9 K at solid–liquid–vapour (SLVE) condition. Measured SLVE and solid–liquid equilibrium data were used to tune a thermodynamic model implemented in the ThermoFAST software package by adjusting the binary interaction parameter (BIP) in the Peng–Robinson equation of state. The tuned model represents the measured melting points for binary mixtures with a root mean square deviation (RMSD) of 3.2 K, which is 60 % less than achieved with the default BIP. An RMSD of 0.5 K was obtained using the tuned model for the mixtures with CO2 fractions over 28 mol % relative to an RMSD of 3.4 K obtained with the default model. The new property data and improved model presented in this work will help avoid solid deposition risk in cryogenic applications of the HFC-32 + CO2 binary system and promote wider applications of more environmentally-friendly refrigerant mixtures