scholarly journals MRI-VisAct: a Bowden-cable-driven MRI-compatible series viscoelastic actuator

2017 ◽  
Vol 40 (8) ◽  
pp. 2440-2453 ◽  
Author(s):  
Yusuf Mert Senturk ◽  
Volkan Patoglu
Keyword(s):  
Magnetic Field ◽  
Degrees Of Freedom ◽  
Low Cost ◽  
Torque Control ◽  
Robotic Rehabilitation ◽  
Safety Hazards ◽  
Fibre Optics ◽  
Mri Environment ◽  
Robotic Devices ◽  
Magnetic Resonance Imaging Mri

The presence of strong magnetic fields in the magnetic resonance imaging (MRI) environment limits the integration of robotic rehabilitation systems in the MRI process. The tendency to improve imaging quality by the amplification of magnetic field strength further tightens the bidirectional compatibility constraints on MRI-compatible rehabilitation devices. We present the design, control and characterization of MRI-VisAct– a low-cost, Bowden-cable-actuated rotary series viscoelastic actuator that satisfies the bidirectional compatibility requirements to the maximum extent. Components of MRI-VisAct that are placed in the magnet room are built using nonconductive, diamagnetic MRI-compatible materials, while ferromagnetic or paramagnetic components are placed in the control room, located outside the MRI room. Power and data transmission are achieved through Bowden cables and fibre optics, respectively. This arrangement ensures that neuroimaging artefacts are minimized, while eliminating safety hazards, and device performance is not affected by the magnetic field. MRI-VisAct works under closed-loop torque control enabled through series viscoelastic actuation. MRI-VisAct is fully customizable; it can serve as a building block of higher-degrees-of-freedom MRI-compatible robotic devices.

scholarly journals B0-Shimming Methodology for Affordable and Compact Low-Field Magnetic Resonance Imaging Magnets

2021 ◽  
Vol 9 ◽  
Author(s):  
Konstantin Wenzel ◽  
Hazem Alhamwey ◽  
Tom O’Reilly ◽  
Layla Tabea Riemann ◽  
Berk Silemek ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Field ◽  
Magnetic Resonance ◽  
Point Of Care ◽  
Low Cost ◽  
Field Measurements ◽  
Target Volume ◽  
Resonance Imaging ◽  
Low Field ◽  
Magnetic Resonance Imaging Mri

Low-field (B0 < 0.2 T) magnetic resonance imaging (MRI) is emerging as a low cost, point-of-care alternative to provide access to diagnostic imaging technology even in resource scarce environments. MRI magnets can be constructed based on permanent neodymium-iron-boron (NdFeB) magnets in discretized arrangements, leading to substantially lower mass and costs. A challenge with these designs is, however, a good B0 field homogeneity, which is needed to produce high quality images free of distortions. In this work, we describe an iterative approach to build a low-field MR magnet based on a B0-shimming methodology using genetic algorithms. The methodology is tested by constructing a small bore (inner bore diameter = 130 mm) desktop MR magnet (<15 kg) at a field strength of B0 = 0.1 T and a target volume of 4 cm in diameter. The configuration consists of a base magnet and shim inserts, which can be placed iteratively without modifying the base magnet assembly and without changing the inner dimensions of the bore or the outer dimensions of the MR magnet. Applying the shims, B0 field inhomogeneity could be reduced by a factor 8 from 5,448 to 682 ppm in the target central slice of the magnet. Further improvements of these results can be achieved in a second or third iteration, using more sensitive magnetic field probes (e.g., nuclear magnetic resonance based magnetic field measurements). The presented methodology is scalable to bigger magnet designs. The MR magnet can be reproduced with off-the-shelf components and a 3D printer and no special tools are needed for construction. All design files and code to reproduce the results will be made available as open source hardware.

scholarly journals A domestic robotic rehabilitation device for assessment of wrist function for outpatients

2020 ◽  
Vol 7 ◽  
pp. 205566832096123
Author(s):  
Matthias Panny ◽  
Andreas Mayr ◽  
Marco Nagiller ◽  
Yeongmi Kim
Keyword(s):  
Range Of Motion ◽  
Home Environment ◽  
Degrees Of Freedom ◽  
Low Cost ◽  
Joint Stiffness ◽  
Torsional Stiffness ◽  
Preliminary Evaluation ◽  
Robotic Rehabilitation ◽  
Flexion Extension ◽  
Wrist Function

Introduction Available robot-assisted stroke rehabilitation systems are often limited in their utilization in the home environment, due to several barriers such as high cost, absence of therapists, tedious training tasks, or encumbering interfaces. This paper presents a low-cost robotic rehabilitation and assessment device for restoring wrist function, offering wrist exercises incorporating pronation-supination and flexion-extension movements. Furthermore, the device is designed for the assessment of joint stiffness of the wrist, and range of motion in two degrees of freedom. Methods: Mechanical/electrical design of the device as well as the control system is described. A preliminary evaluation focused on the measurement of the torsional stiffness of the limb is presented. It is evaluated by reconstructing the known stiffness values of torsional springs by measuring the motor current required to displace them. Results The device demonstrates the ability to determine the stiffness of an object with low-cost hardware. Use case scenarios of the device for training and assessment of the wrist are presented, allowing for a range of motion of [Formula: see text] and [Formula: see text], for pronation-supination and flexion-extension respectively. Conclusion The device shows potential to help objectively quantify the stiffness of the wrist movement, which consecutively could be used to represent and quantify the degree of impairment of patients after stroke in a more objective manner. Further clinical study is necessary to examine this.

scholarly journals Reconstruction of Relative Phase of Self-Transmitting Devices by Using Multiprobe Solutions and Non-Convex Optimization

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2459
Author(s):  
Rubén Tena Sánchez ◽  
Fernando Rodríguez Varela ◽  
Lars J. Foged ◽  
Manuel Sierra Castañer
Keyword(s):  
Iterative Algorithm ◽  
Degrees Of Freedom ◽  
Relative Phase ◽  
Low Cost ◽  
Initial Guess ◽  
Noise Model ◽  
Medium Size ◽  
Phase Reconstruction ◽  
Linear Combinations ◽  
Iterative Optimization Algorithm

Phase reconstruction is in general a non-trivial problem when it comes to devices where the reference is not accessible. A non-convex iterative optimization algorithm is proposed in this paper in order to reconstruct the phase in reference-less spherical multiprobe measurement systems based on a rotating arch of probes. The algorithm is based on the reconstruction of the phases of self-transmitting devices in multiprobe systems by taking advantage of the on-axis top probe of the arch. One of the limitations of the top probe solution is that when rotating the measurement system arch, the relative phase between probes is lost. This paper proposes a solution to this problem by developing an optimization iterative algorithm that uses partial knowledge of relative phase between probes. The iterative algorithm is based on linear combinations of signals when the relative phase is known. Phase substitution and modal filtering are implemented in order to avoid local minima and make the algorithm converge. Several noise-free examples are presented and the results of the iterative algorithm analyzed. The number of linear combinations used is far below the square of the degrees of freedom of the non-linear problem, which is compensated by a proper initial guess. With respect to noisy measurements, the top probe method will introduce uncertainties for different azimuth and elevation positions of the arch. This is modelled by considering the real noise model of a low-cost receiver and the results demonstrate the good accuracy of the method. Numerical results on antenna measurements are also presented. Due to the numerical complexity of the algorithm, it is limited to electrically small- or medium-size problems.

scholarly journals Towards One-Dollar Robots: An Integrated Design and Fabrication Strategy for Electromechanical Systems

Robotica ◽  
2020 ◽  
pp. 1-17
Author(s):  
Wenzhong Yan ◽  
Ankur Mehta
Keyword(s):  
Low Cost ◽  
Integrated Design ◽  
Single Layer ◽  
Constant Current ◽  
Electromechanical Systems ◽  
Robot Controller ◽  
Electrical Oscillation ◽  
Robotic Devices ◽  
Sewing Threads ◽  
Polyester Film

SUMMARY To improve the accessibility of robotics, we propose a design and fabrication strategy to build low-cost electromechanical systems for robotic devices. Our method, based on origami-inspired cut-and-fold and E-textiles techniques, aims at minimizing the resources for robot creation. Specifically, we explore techniques to create robots with the resources restricted to single-layer sheets (e.g., polyester film) and conductive sewing threads. To demonstrate our strategy’s feasibility, these techniques are successfully integrated into an electromechanical oscillator (about 0.40 USD), which can generate electrical oscillation under constant-current power and potentially be used as a simple robot controller in lieu of additional external electronics.

scholarly journals Model forB1Imaging in MRI Using the Rotating RF Field

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Adnan Trakic ◽  
Jin Jin ◽  
Ewald Weber ◽  
Stuart Crozier
Keyword(s):  
Degrees Of Freedom ◽  
Acoustic Noise ◽  
Bloch Equation ◽  
Gradient Coil ◽  
Imaging Method ◽  
Nonuniform Field ◽  
Rf Coil ◽  
Image Encoding ◽  
Magnetic Resonance Imaging Mri ◽  
Space Requirements

Conventionally, magnetic resonance imaging (MRI) is performed by pulsing gradient coils, which invariably leads to strong acoustic noise, patient safety concerns due to induced currents, and costly power/space requirements. This modeling study investigates a new silent, gradient coil-free MR imaging method, in which a radiofrequency (RF) coil and its nonuniform field (B1+) are mechanically rotated about the patient. The advantage of the rotatingB1+field is that, for the first time, it provides a large number of degrees of freedom to aid a successfulB1+image encoding process. The mathematical modeling was performed using flip angle modulation as part of a finite-difference-based Bloch equation solver. Preliminary results suggest that representative MR images with intensity deviations of <5% from the original image can be obtained using rotating RF field approach. This method may open up new avenues towards anatomical and functional imaging in medicine.

An application of high-temperature superconductors YBCO to magnetic separation

2017 ◽  
Vol 31 (25) ◽  
pp. 1745001 ◽  
Author(s):  
Qiudong Guo ◽  
Peng Zhang ◽  
Lin Bo ◽  
Guibin Zeng ◽  
Dengqian Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Magnetic Separation ◽  
High Magnetic Field ◽  
Low Cost ◽  
Rapid Development ◽  
High Temperature Superconductors ◽  
New Approach ◽  
Industrial Areas ◽  
Ybco Tape

With the rapid development of manufacturing technology of high temperature superconductive YB[Formula: see text]Cu3O[Formula: see text] YBCO materials and decreasing in cost of production, YBCO is marching into industrial areas with its good performances as source of high-magnetic field and rather low cost in reaching superconductivity. Based on analysis of the performance of high temperature superconductors YBCO and development of technology in superconductive magnetic separation both home and abroad, we propose a new approach of taking YBCO tape to make a solenoid as the source of a high magnetic field of magnetic separatior of ores. The paper also looks into the future of the YBCO high temperature superconductive magnetic separation from the perspective of technology and cost, as well as its applications in other industries.

scholarly journals Soft Spherical Tensegrity Robot Design Using Rod-Centered Actuation and Control

2016 ◽  
Author(s):  
Lee-Huang Chen ◽  
Kyunam Kim ◽  
Ellande Tang ◽  
Kevin Li ◽  
Richard House ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Low Cost ◽  
Space Exploration ◽  
Robot Design ◽  
The Novel ◽  
Flexible Design ◽  
Spherical Robot ◽  
Potential Benefits ◽  
And Performance ◽  
And Control

This paper presents the design, analysis and testing of a fully actuated modular spherical tensegrity robot for co-robotic and space exploration applications. Robots built from tensegrity structures (composed of pure tensile and compression elements) have many potential benefits including high robustness through redundancy, many degrees of freedom in movement and flexible design. However to fully take advantage of these properties a significant fraction of the tensile elements should be active, leading to a potential increase in complexity, messy cable and power routing systems and increased design difficulty. Here we describe an elegant solution to a fully actuated tensegrity robot: The TT-3 (version 3) tensegrity robot, developed at UC Berkeley, in collaboration with NASA Ames, is a lightweight, low cost, modular, and rapidly prototyped spherical tensegrity robot. This robot is based on a ball-shaped six-bar tensegrity structure and features a unique modular rod-centered distributed actuation and control architecture. This paper presents the novel mechanism design, architecture and simulations of TT-3, the first untethered, fully actuated cable-driven six-bar tensegrity spherical robot ever built and tested for mobility. Furthermore, this paper discusses the controls and preliminary testing performed to observe the system’s behavior and performance.

Robot-assisted MRI-guided prostatic interventions

Robotica ◽  
2009 ◽  
Vol 28 (2) ◽  
pp. 215-234 ◽  
Author(s):  
Andrew A. Goldenberg ◽  
John Trachtenberg ◽  
Yang Yi ◽  
Robert Weersink ◽  
Marshall S. Sussman ◽  
...  
Keyword(s):  
Thermal Ablation ◽  
Pulse Sequences ◽  
Robot Assisted ◽  
Surgical Ablation ◽  
Image Guided ◽  
Surgical Tool ◽  
Mri Environment ◽  
Focal Ablation ◽  
Mri Guided ◽  
Magnetic Resonance Imaging Mri

SUMMARYThis paper reports on recent progress made toward the development of a new magnetic resonance imaging (MRI)-compatible robot-assisted surgical system for closed-bore image-guided prostatic interventions: thermal ablation, radioactive seed implants (brachytherapy), and biopsy. Each type of intervention will be performed with a different image-guided, robot-based surgical tool mounted on the same MRI-guided robot through a modular trocar. The first stage of this development addresses only laser-based focal ablation. The robot mechanical structure, modular surgical trocar, control architecture, and current stage of performance evaluation in the MRI environment are presented. The robot actuators are ultrasonic motors. A methodology of using such motors in the MRI environment is presented. The robot prototype with surgical ablation tool is undergoing tests on phantoms in the MRI bore. The tests cover MRI compatibility, image visualization, robot accuracy, and thermal mapping. To date, (i) the images are artifact- and noise-free for certain scanning pulse sequences; (ii) the robot tip positioning error is less than 1.2 mm even at positions closer than 0.3 m from the MRI isocenter; (iii) penetration toward the target is image-monitored in near-real time; and (iv) thermal ablation and temperature mapping are achieved using a laser delivered on an optical fiber and MRI, respectively.

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