			Home About us Contact

Angular Displacement (angular + displacement)

Distribution by Scientific Domains

Life Sciences	44%
Engineering	33%

Selected Abstracts

Northern fowl mite orientation in a thermal gradient and evidence for idiothetic course control

PHYSIOLOGICAL ENTOMOLOGY, Issue 3 2005
Jeb P. Owen
Abstract., The northern fowl mite, Ornithonyssus sylviarum, is an ectoparasite of birds and a poultry pest. The ability of northern fowl mites to orientate to a heat source is investigated with individual mites video-recorded in two-dimensional arenas and exposed to spatial or temporal heat gradients. Recorded tracks are digitally analysed for variation in linear velocity, mean direction of movement, and patterns in angular displacement. Mean direction of movement in a spatial gradient is significantly associated with the position of the heat source for 24/29 mites tested (P < 0.05), whereas most control (no heat) mean bearings are randomly distributed (16/25; P > 0.1). Angular displacement that orientates a mite towards the heat source is positively correlated with the preceding deviation from that direction (P < 0.01). Angular displacement away from the heat source is random. The temporal heat gradient is such that no spatial reference to the heat source exists within the plane of the arena. Mites in an ambient (27 °C) to heated (30 °C) transition have angular displacement distributions similar to control mites (ambient to ambient transition). However, mites in a heated to ambient transition execute angular displacements approximately 25° greater than mites in the other treatments (P < 0.03). Mites compare the shift in temperature over time and alter their direction of movement by a programmed (idiothetic) response to a decrease in temperature, rather than through detection of the spatial position of the gradient (allothetic). [source]

Position-dependent disturbance rejection using spatial-based adaptive feedback linearization repetitive control

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 12 2009
Cheng-Lun Chen
Abstract In this paper, we propose a new design of spatial-based repetitive control for a class of rotary motion systems operating at variable speeds. The open-loop system in spatial domain is obtained by reformulating a nonlinear time-invariant system with respect to angular displacement. A two-degree-of-freedom control structure (comprising two control modules) is then proposed to robustly stabilize the open-loop system and improve the tracking performance. The first control module applies adaptive feedback linearization with projected parametric update and concentrates on robust stabilization of the closed-loop system. The second control module introduces a spatial-based repetitive controller cascaded with a loop-shaping filter, which not only further reduces the tracking error, but also improves parametric adaptation. The overall control system is robust to model uncertainties of the system and capable of rejecting position-dependent disturbances under varying process speeds. Stability proof for the overall system is given. A design example with simulation is provided to demonstrate the applicability of the proposed design. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Stiffness characteristics and kinematics analysis of two-link elastic underactuated manipulators

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 4 2002
Jian S. Dai
This article investigates the stiffness characteristics of two-link underactuated manipulators, examines the effect on the torque resulting in the passive joint, and develops a stiffness model in analysing the behaviors of the manipulators. The kinematic analysis leads to the trajectory of the end-effector, which is associated with the stiffness coupled between the active and passive joints and with the constraint forces, and the kinematic coupling is shown in the angular displacement and in the resulting torque. The stiffness characteristics are illustrated in the directional stiffness mapping, which gives a quantitative measure of stiffness with respect to displacement direction. © 2002 Wiley Periodicals, Inc. [source]

OSCILLATING VANE GEOMETRY FOR SOFT SOLID GELS AND FOAMS

JOURNAL OF TEXTURE STUDIES, Issue 6 2002
C. SERVAIS
ABSTRACT Several relationships between the torque and the stress exist for the vane geometry, but only a few equations have been proposed for the relationship between angular displacement and strain. In this study, an expression based on the infinite gap approximation for concentric cylinders is used and well-defined reference data are compared to oscillating vane data to validate the assumptions used. Gelatin gels are used for their property to stick to the wall and carrageenan gels are used to show that wall slip does not occur with oscillating vanes in serrated cup geometries. Shaving foams are used as a model low density, time and shear stable foam, which resists irreversible damage when loaded between serrated parallel plates. Results show that the assumptions used for the determination of stress and strain with the vane provide material viscoelastic properties that are not significantly different from reference values as obtained with concentric cylinders and parallel plates. [source]

Northern fowl mite orientation in a thermal gradient and evidence for idiothetic course control

Mental rotation delays the heart beat: Probing the central processing bottleneck

PSYCHOPHYSIOLOGY, Issue 5 2003
J. Richard Jennings
Abstract We tested the hypothesis that mental rotation would delay response-related processing as indicated by transient slowing of the heart beat. Thirty college-age subjects (half female) were presented with normal and mirror image letters rotated at 0, 60, 120, and 180°. Three letters were assigned to a right-hand response; a separate three to a left-hand response. Responses were only required for letters in one orientation, mirror or normal. Continuous measures of interbeat interval (IBI) of the heart, respiration, and muscle tension were collected. Performance results were largely consistent with prior findings. Greater angular displacement of the stimuli was associated with greater lengthening of IBI immediately after the stimulus. IBI was influenced equally by angle of rotation in respond and inhibit trials. The lengthening of IBI was interpreted as due to a delay in response selection and execution due to mental rotation. [source]

Geared robot manipulators with a jointed unit: Kinematic analysis and its application

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 10 2001
Dar-Zen Chen
An efficient and systematic methodology for the kinematic analysis of geared robot manipulators (GRMs) with a jointed unit is presented. It is shown that, by decomposing mechanical transmission lines of a GRM into serially connected jointed and disjointed units, kinematic relation between local inputs and local outputs of admissible jointed units can be systematically formulated. Accordingly, angular displacements of input links with respect to their associated primary links can be symbolically expressed in terms of joint angles by a unit-by-unit evaluation procedure. This unit-by-unit evaluation procedure provides better kinematic insights into how input torques are transmitted to various joints. It is also shown that an actuator in a GRM with a jointed unit can drive nonconsecutive joints by proper design of its gear train. A 3 degrees of freedom GRM with a jointed unit is used as an illustrative example. © 2001 John Wiley & Sons, Inc. [source]

Measurement of varus,valgus and internal,external rotational knee laxities in vivo,Part II: relationship with anterior,posterior and general joint laxity in males and females

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 8 2007
Sandra J. Shultz
Abstract We examined sex differences in general joint laxity (GJL), and anterior,posterior displacement (ANT,POST), varus,valgus rotation (VR,VL), and internal,external rotation (INT,EXT) knee laxities, and determined whether greater ANT and GJL predicted greater VR,VL and INT,EXT. Twenty subjects were measured for GJL, and scored on a scale of 0,9. ANT and POST were measured using a standard knee arthrometer at 133 N. VR,VL and INT,EXT were measured using a custom joint laxity testing device, defined as the angular displacements (deg) of the tibia relative to the femur produced by 0,10 Nm of varus,valgus torques, and 0,5 Nm of internal,external torques, respectively. INT,EXT were measured during both non-weight-bearing (NWB) and weight-bearing (WB,=,40% body weight) conditions while VR,VL were measured NWB. All laxity measures were greater for females compared to males except for POST. ANT and GJL positively predicted 62.5% of the variance in VR,VL and 41.8% of the variance in WB INT,EXT. ANT was the sole predictor of INT,EXT in NWB, explaining 42.3% of the variance. These findings suggest that subjects who score higher on clinical measures of GJL and ANT are also likely to have greater VR,VL and INT,EXT knee laxities. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:989,996, 2007 [source]