ASTM_E_2566_-_08.pdf

Designation:E256608Standard Test Method forDetermining Visual Acuity and Field of View of On-BoardVideo Systems for Teleoperation of Robots for UrbanSearch and Rescue Applications1This standard is issued under the fixed designation E2566;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the measurement of several keyparameters of video systems for remote operations.It isinitially intended for applications of robots for Urban Searchand Rescue but is sufficiently general to be used for marine orother remote platforms.Those parameters are(1)field of viewof the camera system,(2)visual acuity at far distances withboth ambient lighting and lighting on-board the robot,(3)visual acuity at near distances,again in both light and darkenvironments,and(4),if available,visual acuity in both lightand dark environments with zoom lens capability.1.2 These tests measure only end-to-end capability,that is,they determine the resolution of the images on the displayscreen at the operator control unit since that is the importantissue for the user.1.3 This test method is intended to be used for writingprocurement specifications and for acceptance testing forrobots for urban search and rescue applications.1.4 This test method will use the Snellen fraction to reportvisual acuity;readers may wish to convert to decimal notationto improve intuitive understanding if they are more familiarwith that notation.Distances will be given in metres withEnglish units in parentheses following.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Terminology2.1 Definitions:2.1.1 field of view,nangle subtended by the largest objectthat can be imaged with the video system.2.1.2 optotype,ncharacter used on a chart for testingvisual acuity.2.1.2.1 DiscussionOptotypes are generally built on a 5 by5 grid,with the size for“standard”vision subtending a square5 min of arc on a side.This makes one grid element 1 min ofarc square.2.1.3 tumbling E,nspecific optotype that can be drawn invarious orientations(facing left,right,up,or down)and invarious sizes to create an eye chart(see Fig.1).2.1.3.1 DiscussionThis optoptype is reported in the litera-ture as being maximally distinguishable.Eye charts withTumbling Es are available commercially for use at differentdistances.2.1.4 standard vision,nability to resolve target featuressubtending 1 min of arc.2.1.5 visual acuity,nability to resolve features subtendingsome angle,as compared with“standard”vision measured atthe same distance.2.1.5.1 DiscussionAn angle subtends a feature of size hat a distance d,of size 2h at a distance of 2d,of size 3h at adistance 3d,and so on.If 2d is the“standard”measurementdistance of 6 m(20 ft),an eye chart for use at 3 m(10 ft)wouldhave characters of h high rather than 2h high and themeasurement of visual acuity would be the same.See Fig.2 foran illustration of the angle/distance relationship.2.1.6 Snellen fraction,na measure of visual acuity.2.1.6.1 DiscussionThe subject is placed a standard dis-tance from an eye chart,typically 6 m(20 ft).The subject isasked to identify the line with the smallest characters that hecan resolve.The Snellen fraction is the ratio of the distance atwhich that line would be resolved by a subject with standardvision to the standard test distance.Thus,a subject withstandard vision would have 6/6(20/20)vision.2.1.7 remote operation,nact of controlling a distant roboton a continuous or intermittent basis via tethered or radio-linked devices while being provided with sensory information(for example,visual information through cameras onboard therobot).1This test method is under the jurisdiction of ASTM Committee E54 onHomeland Security Applications and is the direct responsibility of SubcommitteeE54.08 on Operational Equipment.Current edition approved Feb.1,2008.Published March 2008.DOI:10.1520/E2566-08.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 2.1.7.1 DiscussionRemote operation includes teleopera-tion as well as forms of intermittent autonomy or assistedautonomy.3.Units for Reporting Visual Acuity3.1 The commonly used distance for measuring visualacuity is 20 ft in the United States.This leads to the“Snellenfraction”as the common measure of visual acuity:20/20,20/40,and so on.The Snellen fraction is also used in England,referred to 6 m as the standard measurement distance(6/6,6/12,etc.),while the rest of Europe generally used the decimalfraction equivalent:20/20=6/6=1.0;20/40=6/12=0.5,etc.Measurem