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Positioning Accuracy (positioning + accuracy)

Distribution by Scientific Domains

Engineering	50%

Selected Abstracts

Motorization of a surgical microscope for intra-operative navigation and intuitive control

THE INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY, Issue 3 2010
M. Finke
Abstract Background During surgical procedures, various medical systems, e.g. microscope or C-arm, are used. Their precise and repeatable manual positioning can be very cumbersome and interrupts the surgeon's work flow. Robotized systems can assist the surgeon but they require suitable kinematics and control. However, positioning must be fast, flexible and intuitive. Methods We describe a fully motorized surgical microscope. Hardware components as well as implemented applications are specified. The kinematic equations are described and a novel control concept is proposed. Results Our microscope combines fast manual handling with accurate, automatic positioning. Intuitive control is provided by a small remote control mounted to one of the surgical instruments. Positioning accuracy and repeatability are < 1 mm and vibrations caused by automatic movements fade away in about 1 s. Conclusion The robotic system assists the surgeon, so that he can position the microscope precisely and repeatedly without interrupting the clinical workflow. The combination of manual und automatic control guarantees fast and flexible positioning during surgical procedures. Copyright © 2010 John Wiley & Sons, Ltd. [source]

An application of dynamic positioning control using wave feed forward

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 13 2001
A. B. Aalbers
Abstract The paper presents the results of model tests for a large tanker in which wave drift force feed forward was applied in the dynamic positioning control system. The estimation method of the nonlinear (second order) wave drift forces from the measurement of relative water motions at the side of a ship hull is presented. The estimated wave drift forces are used in the DP control system, to enhance the filter process of the extended Kalman filter, and in the required thruster set-points. The EKF uses the nonlinear equations of low-frequency ship motions on the horizontal plane, which are also presented. The results of the model tests show that the use of wave drift force feed forward significantly improves the positioning accuracy in sea states with 3.5 m significant wave height or higher. Copyright © 2001 John Wiley & Sons, Ltd. [source]

A robotic assistant for stereotactic neurosurgery on small animals

THE INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY, Issue 4 2008
L. Ramrath
Abstract Background This work presents the development and performance analysis of a robotic system for stereotactic neurosurgery on small animals. The system is dedicated to the precise placement of probes in the small animal brain, thus providing an improved framework for brain research. Methods Based on an analysis of small animal stereotaxy, the mechanical design of the robotic system is presented. Details of the structure and mechanical components and a kinematic description are outlined. The calibration process of the system for arbitrary probes is described. To analyse the mechanical positioning accuracy of the system, a testbed is presented. Results Positioning performance results show that the system features a mean mechanical positioning accuracy of 32 µm and a mean positioning repeatability of 11 µm. Conclusion The system meets the requirements of targeting small functional areas within the brain of small animals and thus offers a new tool for small animal brain research. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Image-based hysteresis modeling and compensation for an AFM piezo-scanner,

ASIAN JOURNAL OF CONTROL, Issue 2 2009
Yudong Zhang
Abstract As an important component of Atomic Force Microscopes (AFM), a piezo-scanner exhibits some undesired nonlinear characteristics, among which the inherent hysteresis largely decreases positioning accuracy during scanning and nano-manipulation process. To alleviate this problem, an image-based approach is proposed in this paper to model and then compensate for the hysteresis behavior of the piezo-scanner. Specifically, some scanning images over standard samples are utilized to identify the parameters of the classical Preisach model (CPM) of hysteresis. On the basis of the obtained model, an inversion-based technique is adopted to design a compensator for the hysteresis of the piezo-scanner. The proposed algorithm presents such advantages as low cost and little complexity since no nanoscale position sensor is required to collect identification data. Some scanning and nano-imprinting results are included to demonstrate the performance of the proposed strategy. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]