Estimation of surgical tool-tip tracking error distribution in coordinate reference frame involving pivot calibration uncertainty

Zhe Min; Hongliang Ren; Max Q.-H. Meng

doi:10.1049/htl.2017.0065

Robot-assisted Ultrasound-guided Tracking of Anatomical Structures for the Application of Focused Ultrasound

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2020-3032 ◽

2020 ◽

Vol 6 (3) ◽

pp. 123-126

Author(s):

Michael Unger ◽

Johann Berger ◽

Bjoern Gerold ◽

Andreas Melzer

Keyword(s):

Focused Ultrasound ◽

Varicose Veins ◽

Tracking System ◽

Tracking Error ◽

Uterine Fibroids ◽

High Intensity Focused Ultrasound ◽

Robot Assisted ◽

Anatomical Structures ◽

Surgical Tool ◽

Custom Made

AbstractHigh intensity focused ultrasound is used as a surgical tool to treat completely non-invasively several diseases. Examples of clinical applications are uterine fibroids, prostate cancer, thyroid nodules, and varicose veins. Precise targeting is key for improving the treatment outcome. A method for an automated, robot-assisted tracking system was developed and evaluated. A wireless ultrasound scanner was used to acquire images of the target, in this case, a blood vessel. The active contour approach by Chan and Vese was used to segment and track while moving the scanner along the target structure with a collaborative robotic arm. The performance was assessed using a custom made Agar phantom. The mean tracking error, which is defined as the remaining distance of the lesion to the images’ centre line, was 0.27 mm ± 0.18 mm.

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Tracking error minimization in multi-loop control of UPS inverters using the reference frame transformation

2017 8th Power Electronics, Drive Systems & Technologies Conference (PEDSTC) ◽

10.1109/pedstc.2017.7910343 ◽

2017 ◽

Author(s):

Reza Razi ◽

Mohammad Monfared ◽

Alireza Hadizadeh

Keyword(s):

Reference Frame ◽

Tracking Error ◽

Error Minimization ◽

Loop Control ◽

Reference Frame Transformation ◽

Frame Transformation

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Non-Target Structural Displacement Measurement Using Reference Frame-Based Deepflow

Sensors ◽

10.3390/s19132992 ◽

2019 ◽

Vol 19 (13) ◽

pp. 2992 ◽

Cited By ~ 4

Author(s):

Jongbin Won ◽

Jong-Woong Park ◽

Kyoohong Park ◽

Hyungchul Yoon ◽

Do-Soo Moon

Keyword(s):

Reference Frame ◽

Tracking Error ◽

Displacement Measurement ◽

Displacement Sensor ◽

Feature Points ◽

Points Of Interest ◽

Cantilevered Beam ◽

Error Accumulation ◽

Reference Laser ◽

Point Detection

Displacement is crucial for structural health monitoring, although it is very challenging to measure under field conditions. Most existing displacement measurement methods are costly, labor-intensive, and insufficiently accurate for measuring small dynamic displacements. Computer vision (CV)-based methods incorporate optical devices with advanced image processing algorithms to accurately, cost-effectively, and remotely measure structural displacement with easy installation. However, non-target-based CV methods are still limited by insufficient feature points, incorrect feature point detection, occlusion, and drift induced by tracking error accumulation. This paper presents a reference frame-based Deepflow algorithm integrated with masking and signal filtering for non-target-based displacement measurements. The proposed method allows the user to select points of interest for images with a low gradient for displacement tracking and directly calculate displacement without drift accumulated by measurement error. The proposed method is experimentally validated on a cantilevered beam under ambient and occluded test conditions. The accuracy of the proposed method is compared with that of a reference laser displacement sensor for validation. The significant advantage of the proposed method is its flexibility in extracting structural displacement in any region on structures that do not have distinct natural features.

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An Improved Control Strategy for a Four-Leg Grid-Forming Power Converter under Unbalanced Load Conditions

Advances in Power Electronics ◽

10.1155/2016/9123747 ◽

2016 ◽

Vol 2016 ◽

pp. 1-14 ◽

Cited By ~ 9

Author(s):

Mohammad Reza Miveh ◽

Mohd Fadli Rahmat ◽

Mohd Wazir Mustafa ◽

Ali Asghar Ghadimi ◽

Alireza Rezvani

Keyword(s):

Reference Frame ◽

Control Strategy ◽

Tracking Error ◽

Power Converter ◽

Current Control ◽

Voltage Source ◽

Current Loop ◽

Voltage Controller ◽

Unbalanced Load ◽

Load Conditions

This paper proposes an improved multiloop control strategy for a three-phase four-leg voltage source inverter (VSI) operating with highly unbalanced loads in an autonomous distribution network. The main objective is to balance the output voltages of the four-leg inverter under unbalanced load conditions. The proposed control strategy consists of a proportional-integral (PI) voltage controller and a proportional current loop in each phase. The voltage controller and the current control loop are, respectively, used to regulate the instantaneous output voltage and generate the pulse width modulation (PWM) voltage command with zero steady-state tracking error and fast transient response. A voltage decoupling feedforward path is also used to enhance the system robustness. Since the outer voltage loop operates in the synchronous reference frame, tuning and stability analysis of the PI controller is far from being straightforward. In order to cope with this challenge, the stationary reference frame equivalent of the voltage controller in the rotating frame is derived. Subsequently, a systematic design based on a frequency response approach is provided. Simulation results are also carried out using the DIgSILENT PowerFactory software to verify the effectiveness of the suggested control strategy.

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Practical Realization of a Reference System for Earth Dynamics by Satellite Methods

International Astronomical Union Colloquium ◽

10.1017/s0252921100051150 ◽

1975 ◽

Vol 26 ◽

pp. 341-380 ◽

Cited By ~ 5

Author(s):

R. J. Anderle ◽

M. C. Tanenbaum

Keyword(s):

Reference Frame ◽

Polar Motion ◽

Pole Position ◽

Control Points ◽

Significant Information ◽

Crustal Motion ◽

Average Reference ◽

Future Data ◽

Existing Data

AbstractObservations of artificial earth satellites provide a means of establishing an.origin, orientation, scale and control points for a coordinate system. Neither existing data nor future data are likely to provide significant information on the .001 angle between the axis of angular momentum and axis of rotation. Existing data have provided data to about .01 accuracy on the pole position and to possibly a meter on the origin of the system and for control points. The longitude origin is essentially arbitrary. While these accuracies permit acquisition of useful data on tides and polar motion through dynamio analyses, they are inadequate for determination of crustal motion or significant improvement in polar motion. The limitations arise from gravity, drag and radiation forces on the satellites as well as from instrument errors. Improvements in laser equipment and the launch of the dense LAGEOS satellite in an orbit high enough to suppress significant gravity and drag errors will permit determination of crustal motion and more accurate, higher frequency, polar motion. However, the reference frame for the results is likely to be an average reference frame defined by the observing stations, resulting in significant corrections to be determined for effects of changes in station configuration and data losses.

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