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Position Sensors (position + sensor)

Distribution by Scientific Domains

Engineering	75%

Selected Abstracts

Kinematic Calibration and Pose Measurement of a Medical Parallel Manipulator by Optical Position Sensors

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 4 2003
Shaoping Bai
In the applications of parallel manipulators, kinematic calibration is required to eliminate the errors resulting from the manufacturing and assembly of both base and tools. In this paper, a calibration method of base and tool transformation is developed by virtue of optical position sensors. An error model for calibration is constructed using differential geometry method. The pose error is obtained based on pose measurement results of OPTOTRAK 3020, a commercial 3D position measurement system. An iterative least squares procedure is used to identify the error parameters in the base and tool transformations. Simulation and experiment results are presented to demonstrate the effectiveness of the method for transformation matrices calibration. © 2003 Wiley Periodicals, Inc. [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]

Kinematic Calibration and Pose Measurement of a Medical Parallel Manipulator by Optical Position Sensors

Nonweight-bearing anterior knee laxity is related to anterior tibial translation during transition from nonweight bearing to weight bearing

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2006
Sandra J. Shultz
Abstract We examined the relationship between anterior knee laxity (AKL), evaluated while the knee was nonweight bearing, and anterior translation of the tibia relative to the femur (ATT), evaluated when the knee transitioned from nonweight-bearing to weight-bearing conditions in response to an applied compressive load at the foot. Twenty subjects with normal knees (10 M, 10 F; 25.2,±,4.1 years, 169.8,±,11.5 cm, 71.6,±,16.9 kg) underwent measurements of AKL and ATT of the right knee on 2 days. AKL was measured at 133N with the KT-2000Ô. ATT was measured with the Vermont Knee Laxity Device and electromagnetic position sensors attached to the patella and the anteromedial aspect of the proximal tibia. Three trials for each measure were averaged and analyzed. Measurement consistency was high for both AKL (ICC,=,0.97; SEM,=,0.44 mm) and ATT (ICC,=,0.88; SEM,=,0.84 mm). Linear regression revealed that AKL predicted 35.5% of the variance in ATT (p,=,0.006), with a prediction equation of YATT,=,3.20,+,0.543(XAKL). Our findings suggest that increased AKL is associated with increased ATT as the knee transitions from nonweight-bearing to weight-bearing conditions. The potential for increased knee joint laxity to disrupt normal knee biomechanics during activities such as landing from a jump, or the foot strike phase of gait deserves further study. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:516,523, 2006 [source]