Collision Problem: Characteristics for a Taxonomy

2006 ◽  
Author(s):  
D. Borro ◽  
J. Hernantes ◽  
A. Garcia-Alonso ◽  
L. Matey
Keyword(s):  
Collision Problem

Wave packet study of a linear collision problem

1989 ◽  
Vol 91 (12) ◽  
pp. 7693-7704 ◽  
Author(s):  
Andreas Bringer ◽  
John Harris
Keyword(s):  
Wave Packet ◽  
Collision Problem

Pre-Impact Configuration Designing of a Robot Manipulator for Impact Minimization

2017 ◽  
Vol 9 (3) ◽  
Author(s):  
Jingchen Hu ◽  
Tianshu Wang
Keyword(s):  
Impact Force ◽  
Robot Manipulator ◽  
Analytical Formula ◽  
Joint Space ◽  
Collision Problem ◽  
Spatial Operator ◽  
Inertia Ellipsoid ◽  
The Impact ◽  
Maximum Minimum ◽  
Simple Analytical Formula

This paper studies the collision problem of a robot manipulator and presents a method to minimize the impact force by pre-impact configuration designing. First, a general dynamic model of a robot manipulator capturing a target is established by spatial operator algebra (SOA) and a simple analytical formula of the impact force is obtained. Compared with former models proposed in literatures, this model has simpler form, wider range of applications, O(n) computation complexity, and the system Jacobian matrix can be provided as a production of the configuration matrix and the joint matrix. Second, this work utilizes the impulse ellipsoid to analyze the influence of the pre-impact configuration and the impact direction on the impact force. To illustrate the inertia message of each body in the joint space, a new concept of inertia quasi-ellipsoid (IQE) is introduced. We find that the impulse ellipsoid is constituted of the inertia ellipsoids of the robot manipulator and the target, while each inertia ellipsoid is composed of a series of inertia quasi-ellipsoids. When all inertia quasi-ellipsoids exhibit maximum (minimum) coupling, the impulse ellipsoid should be the flattest (roundest). Finally, this paper provides the analytical expression of the impulse ellipsoid, and the eigenvalues and eigenvectors are used as measurements to illustrate the size and direction of the impulse ellipsoid. With this measurement, the desired pre-impact configuration and the impact direction with minimum impact force can be easily solved. The validity and efficiency of this method are verified by a PUMA robot and a spatial robot.

Interference-Free Multi-Axis NC Machining of Cylindrical Cam Using Enveloping Element

2009 ◽  
Vol 419-420 ◽  
pp. 333-336
Author(s):  
Jeng Nan Lee ◽  
Chih Wen Luo ◽  
Hung Shyong Chen
Keyword(s):  
Cutting Tool ◽  
Nc Machining ◽  
Model Material ◽  
Solid Model ◽  
End Mill ◽  
Generating Method ◽  
Collision Problem ◽  
Five Axis ◽  
Cutting Path ◽  
Cutting Simulations

To obtain the flexibility of choice of cutting tool and to compensate the wear of the cutting tool, this paper presents an interference-free toolpath generating method for multi-axis machining of a cylindrical cam. The notion of the proposed method is that the cutting tool is confined within the meshing element and the motion of the cutting tool follows the meshing element so that collision problem can be avoided. Based on the envelope theory, homogeneous coordinate transformation and differential geometry, the cutter location for multi-axis NC machining using cylindrical-end mill is derived and the cutting path sequences with the minimum lead in and lead out are planned. The cutting simulations with solid model are performed to verify the proposed toolpath generation method. It is also verified through the trial cut with model material on a five-axis machine tool.

THE UNSOLVED MARINE COLLISION PROBLEM*

Navigation ◽  
1957 ◽  
Vol 5 (5) ◽  
pp. 219-224
Author(s):  
E. S. Quilter
Keyword(s):  
Collision Problem

scholarly journals A System of Rules for Preventing Collisions at Sea

1971 ◽  
Vol 24 (3) ◽  
pp. 417-420 ◽  
Author(s):  
J. García-Frías
Keyword(s):  
Working Party ◽  
Collision Problem ◽  
January Issue ◽  
Necessary And Sufficient ◽  
Clear Weather

The following proposed system of rules was presented to the Collision Regulations Working Party of the Institute by Admiral García-Frías and is referred to in the January issue of the Journal (24, 56–9).IT is evident that the revision of the Collision Regulations would only be effective with a system of Rules able to cope with all situations that may arise at sea. The system must include all that it is necessary and sufficient to solve the collision problem in the easiest and most effective way and consequently it must apply both in clear weather and in restricted visibility using radar; differences between these situations being defined, if necessary, in every Rule.

scholarly journals Tag count based priority scheduling algorithm for mitigating the RFID collisions

2020 ◽  
Vol 18 (1) ◽  
pp. 434
Author(s):  
Hema C ◽  
Sharmila Sankar ◽  
Sandhya M
Keyword(s):  
Radio Frequency Identification ◽  
Scheduling Algorithm ◽  
Cluster Head ◽  
Life Time ◽  
Backscatter Signal ◽  
Priority Scheduling ◽  
Dragonfly Algorithm ◽  
Redundant Data ◽  
Collision Problem ◽  
Electromagnetic Signals

<p><span>RFID (Radio Frequency IDentification) is a developing technology that employs electromagnetic signals to send the data among reader and tags to identify categorize and track the moveable items. The objective of this paper is to mitigate the reader collision problem by scheduling the readers in RFID system.  Mobile readers in the RFID network send the same frequency signal to the air to read the data from the tags. While these two signals interfere each other and Tags are unable to backscatter signal to the reader. This causes a reader collision problem. The Reader collision problem reduces the lifetime of the RFID network and generates redundant data in the RFID Network. Tag Count based Priority Scheduling algorithm is proposed, that enhances the throughput of the readers and mitigates the reader collision problem. In the cluster based RFID network, The Dragonfly algorithm performed the Cluster Head reader election and cluster construction process and then allotting the mobile readers in the cluster. This algorithm improves the energy efficiency and diminishes the reader collision problem, thereby alleviating the tag information loss and expanding the mobile RFID network life time, while compared with Priority Clustering Protocol and the Graph Coloring based TDMA algorithm.</span></p>

scholarly journals CT-Based Collision Prediction Software for External-Beam Radiation Therapy

2021 ◽  
Vol 11 ◽  
Author(s):  
Yu-Jen Wang ◽  
Jia-Sheng Yao ◽  
Feipei Lai ◽  
Jason Chia-Hsien Cheng
Keyword(s):  
Radiation Therapy ◽  
Confusion Matrix ◽  
Large Body ◽  
External Beam Radiation ◽  
True Negative ◽  
Beam Radiation ◽  
Beam Angle Optimization ◽  
Software Models ◽  
Collision Prediction ◽  
Collision Problem

PurposeBeam angle optimization is a critical issue for modern radiotherapy (RT) and is a challenging task, especially for large body sizes and noncoplanar designs. Noncoplanar RT techniques may have dosimetric advantages but increase the risk of mechanical collision. We propose a software solution to accurately predict colliding/noncolliding configurations for coplanar and noncoplanar beams.Materials and MethodsIndividualized software models for two different linear accelerators were built to simulate noncolliding gantry orientations for phantom/patient subjects. The sizes and shapes of the accelerators were delineated based on their manuals and on-site measurements. The external surfaces of the subjects were automatically contoured based on computed tomography (CT) simulations. An Alderson Radiation Therapy phantom was used to predict the accuracy of spatial collision prediction by the software. A gantry collision problem encountered by one patient during initial setup was also used to test the validity of the software. Results: In the comparison between the software estimates and on-site measurements, the noncoplanar collision angles were all predicted within a 5-degree difference in gantry position. The confusion matrix was calculated for each of the two empty accelerator models, and the accuracies were 98.7% and 97.3%. The true positive rates were 97.7% and 96.9%, while the true negative rates were 99.8% and 97.9%, respectively. For the phantom study, the collision angles were predicted within a 5-degree difference. The software successfully predicted the collision problem encountered by the breast cancer patient in the initial setup position and generated shifted coordinates that were validated to correspond to a noncolliding geometry.ConclusionThe developed software effectively and accurately predicted collisions for accelerator-only, phantom, and patient setups. This software may help prevent collisions and expand the range of spatially applicable beam angles.

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