colloborative-gps-ins-nav(1).rar_ins_nav_Possibility

<html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta charset="utf-8"> <meta name="generator" content="pdf2htmlEX"> <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"> <link rel="stylesheet" href="https://static.pudn.com/base/css/base.min.css"> <link rel="stylesheet" href="https://static.pudn.com/base/css/fancy.min.css"> <link rel="stylesheet" href="https://static.pudn.com/prod/directory_preview_static/625b1a8abe9ad24cfafdda5d/raw.css"> <script src="https://static.pudn.com/base/js/compatibility.min.js"></script> <script src="https://static.pudn.com/base/js/pdf2htmlEX.min.js"></script> <script> try{ pdf2htmlEX.defaultViewer = new pdf2htmlEX.Viewer({}); }catch(e){} </script> <title></title> </head> <body> <div id="sidebar" style="display: none"> <div id="outline"> </div> </div> <div id="pf1" class="pf w0 h0" data-page-no="1"><div class="pc pc1 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/625b1a8abe9ad24cfafdda5d/bg1.jpg"><div class="t m0 x1 h2 y1 ff1 fs0 fc0 sc0 ls0 ws0">CollaborativeGPS/INSNavigationinUrban</div><div class="t m0 x2 h3 y2 ff1 fs1 fc0 sc0 ls0 ws0">Environment</div><div class="t m0 x3 h4 y3 ff2 fs2 fc0 sc0 ls0 ws0">F.BerefeltB.BobergJ.NygårdsP.Strömbäck</div><div class="t m0 x4 h4 y4 ff2 fs2 fc0 sc0 ls0 ws0">S.-L. Wirkander</div><div class="t m0 x5 h5 y5 ff3 fs2 fc0 sc0 ls0 ws0">SwedishDefenceResearchAgency(FOI)</div><div class="t m0 x6 h6 y6 ff4 fs3 fc0 sc0 ls0 ws0">Biography</div><div class="t m0 x6 h7 y7 ff5 fs4 fc0 sc0 ls0 ws0">F.Berefeltisaresearcherwiththedivisionof</div><div class="t m0 x6 h7 y8 ff6 fs4 fc0 sc0 ls0 ws0">DefenceAnalysisatFOI.Hisresearchinterests</div><div class="t m0 x7 h7 y9 ff6 fs4 fc0 sc0 ls0 ws0">includemathematicalanalysisanmodeling.He</div><div class="t m0 x7 h7 ya ff6 fs4 fc0 sc0 ls0 ws0">holdsaB.A.fromtheUniversityofStockholm</div><div class="t m0 x7 h7 yb ff6 fs4 fc0 sc0 ls0 ws0">andaM.Sc.inmathematicalphysicsfromthe</div><div class="t m0 x7 h7 yc ff6 fs4 fc0 sc0 ls0 ws0">RoyalInstituteofTechnologyinStockholm.</div><div class="t m0 x6 h7 yd ff5 fs4 fc0 sc0 ls0 ws0">B.BobergisaResearchOﬃcerwiththedi</div><div class="t m0 x7 h7 ye ff6 fs4 fc0 sc0 ls0 ws0">visionofSystemsTechnologyatFOI.Hisre</div><div class="t m0 x7 h7 yf ff6 fs4 fc0 sc0 ls0 ws0">searchinterestsconsistinnavigation,estima</div><div class="t m0 x7 h7 y10 ff6 fs4 fc0 sc0 ls0 ws0">tion,androbotics.HeholdsaM.Sc.degreein</div><div class="t m0 x8 h7 y11 ff6 fs4 fc0 sc0 ls0 ws0">AppliedPhysicsandE.E.andaD.Eng.degree</div><div class="t m0 x8 h7 y12 ff6 fs4 fc0 sc0 ls0 ws0">inroboticsfromLinköpingInstituteofTechnol</div><div class="t m0 x9 h7 y13 ff6 fs4 fc0 sc0 ls0 ws0">ogy.</div><div class="t m0 x7 h7 y14 ff5 fs4 fc0 sc0 ls0 ws0">J.NygårdsisaResearchOﬃcerwiththedivision</div><div class="t m0 x7 h7 y15 ff6 fs4 fc0 sc0 ls0 ws0">ofGuidanceSystemsatFOI.HeisalsoAssistant</div><div class="t m0 x8 h7 y16 ff6 fs4 fc0 sc0 ls0 ws0">ProfessorattheRobotics/AutonomousMechan</div><div class="t m0 x8 h7 y17 ff6 fs4 fc0 sc0 ls0 ws0">icalSystemsgroupatLinköpingUniversity.His</div><div class="t m0 x8 h7 y18 ff6 fs4 fc0 sc0 ls0 ws0">resarchinterstsincluderobotics,estimation,and</div><div class="t m0 x8 h7 y19 ff6 fs4 fc0 sc0 ls0 ws0">tracking.HeholdsaM.Sc.degreeinM.E.and</div><div class="t m0 x9 h7 y1a ff6 fs4 fc0 sc0 ls19 ws0">aPh.D.inautonomousrobotsfromLinköping</div><div class="t m0 x9 h7 y1b ff6 fs4 fc0 sc0 ls0 ws0">InstituteofTechnology.</div><div class="t m0 x8 h7 y1c ff5 fs4 fc0 sc0 ls0 ws0">P.StrömbäckreceivedhisM.Sc.inE.E.fromthe</div><div class="t m0 x8 h7 y1d ff6 fs4 fc0 sc0 ls0 ws0">RoyalInstituteofTechnologyinStockholm.He</div><div class="t m0 x8 h7 y1e ff6 fs4 fc0 sc0 ls0 ws0">iscurrentlyconductingresearchinrobustnav</div><div class="t m0 x9 h7 y1f ff6 fs4 fc0 sc0 ls0 ws0">igationatthedivisionofSystemsTechnology,</div><div class="t m0 x8 h7 y20 ff6 fs4 fc0 sc0 ls1e ws0">FOI.</div><div class="t m0 x8 h7 y21 ff5 fs4 fc0 sc0 ls0 ws0">S.-L.WirkanderisaResearchOﬃcerwiththe</div><div class="t m0 xa h7 y22 ff6 fs4 fc0 sc0 ls0 ws0">divisionofSystemsTechnologyatFOI.Hisre</div><div class="t m0 xa h7 y23 ff6 fs4 fc0 sc0 ls0 ws0">sarchinterestsincludecontroltheoryandnavi</div><div class="t m0 xa h7 y24 ff6 fs4 fc0 sc0 ls0 ws0">gation.HeholdsaM.Sc.degreefromChalmers</div><div class="t m0 xa h7 y25 ff6 fs4 fc0 sc0 ls0 ws0">UniversityofTechnology,Gothenburg,aM.A.</div><div class="t m0 xa h7 y26 ff6 fs4 fc0 sc0 ls0 ws0">fromtheUniversityofStockholm,andaM.E.</div><div class="t m0 xa h7 y27 ff6 fs4 fc0 sc0 ls0 ws0">fromColumbiaUniversity,NewYork.</div><div class="t m0 xa h6 y28 ff4 fs3 fc0 sc0 ls0 ws0">Abstract</div><div class="t m0 xb h7 y29 ff6 fs4 fc0 sc0 ls0 ws0">The Swedish Defence Research Agency is currently</div><div class="t m0 xb h7 y2a ff6 fs4 fc0 sc0 ls0 ws0">conductingresearchaimingatthecreationofaNet</div><div class="t m0 xb h7 y2b ff6 fs4 fc0 sc0 ls0 ws0">work Based Defence (NBD). This research includes</div><div class="t m0 xb h7 y2c ff6 fs4 fc0 sc0 ls0 ws0">areas such as GPS/INS navigation and collaboration</div><div class="t m0 xb h7 y2d ff6 fs4 fc0 sc0 ls0 ws0">of Unmanned Ground Vehicles (UGV:s).</div><div class="t m0 xc h7 y2e ff6 fs4 fc0 sc0 ls0 ws0">A large problem with navigation systems that use</div><div class="t m0 xb h7 y2f ff6 fs4 fc0 sc0 ls0 ws0">GPS is that, due to the possibility of satellite out</div><div class="t m0 xb h7 y30 ff6 fs4 fc0 sc0 ls0 ws0">ages, there are many occasions when the GPS re</div><div class="t m0 xb h7 y31 ff6 fs4 fc0 sc0 ls0 ws0">ceiver fails to deliver enough information to support</div><div class="t m0 xb h7 y32 ff6 fs4 fc0 sc0 ls0 ws0">an error free navigation. In this paper, techniques</div><div class="t m0 xb h7 y33 ff6 fs4 fc0 sc0 ls0 ws0">will be presented to increase position accuracy and</div><div class="t m0 xb h7 y34 ff6 fs4 fc0 sc0 ls0 ws0">navigation robustness in an urban environment by</div><div class="t m0 xb h7 y35 ff6 fs4 fc0 sc0 ls0 ws0">means of collaborative navigation.</div><div class="t m0 xc h7 y36 ff6 fs4 fc0 sc0 ls0 ws0">When a vehicle is navigating in an urban environ</div><div class="t m0 xb h7 y37 ff6 fs4 fc0 sc0 ls0 ws0">ment, lines of sight (LOS) to satellites will often be</div><div class="t m0 xb h7 y38 ff6 fs4 fc0 sc0 ls0 ws0">blocked. However, two vehicles at diﬀerent locations</div><div class="t m0 xb h7 y39 ff6 fs4 fc0 sc0 ls0 ws0">can have diﬀerent sets of visible satellites, and by</div><div class="t m0 xb h7 y3a ff6 fs4 fc0 sc0 ls0 ws0">collaboration the satellite information can be shared</div><div class="t m0 xb h7 y3b ff6 fs4 fc0 sc0 ls0 ws0">between the vehicles, which results in better navi</div><div class="t m0 xb h7 y3c ff6 fs4 fc0 sc0 ls0 ws0">gational performance. The three collaborative tech</div><div class="t m0 xb h7 y3d ff6 fs4 fc0 sc0 ls0 ws0">niques investigated in this paper are based on com</div><div class="t m0 xb h7 y3e ff6 fs4 fc0 sc0 ls0 ws0">munication between the two vehicles, as well as mea</div><div class="c xd y3f w2 h8"><div class="t m0 xe h9 y40 ff7 fs5 fc0 sc0 ls0 ws0">1114</div></div><div class="c xf y41 w3 ha"><div class="t m0 x10 h9 y42 ff8 fs5 fc0 sc0 ls0 ws0">ION NTM 2004, 26-28 January 2004, San Diego, CA</div></div></div><div class="pi" data-data='{"ctm":[1.568627,0.000000,0.000000,1.568627,0.000000,0.000000]}'></div></div> </body> </html>

<div id="pf2" class="pf w0 h0" data-page-no="2"><div class="pc pc2 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/625b1a8abe9ad24cfafdda5d/bg2.jpg"><div class="t m0 x6 h7 y43 ff6 fs4 fc0 sc0 ls0 ws0">surements of their relative range or range vectors. In</div><div class="t m0 x6 h7 y44 ff6 fs4 fc0 sc0 ls0 ws0">many ways the techniques are similar to using pseu</div><div class="t m0 x6 h7 y45 ff6 fs4 fc0 sc0 ls0 ws0">dolites, but with the important diﬀerence that here</div><div class="t m0 x6 h7 y46 ff6 fs4 fc0 sc0 ls0 ws0">the pseudolites are mobile and also navigating.</div><div class="t m0 x11 h7 y47 ff6 fs4 fc0 sc0 ls0 ws0">The case with two collaborating vehicles is con</div><div class="t m0 x6 h7 y48 ff6 fs4 fc0 sc0 ls0 ws0">sidered. Both vehicles are equipped with comple</div><div class="t m0 x6 h7 y49 ff6 fs4 fc0 sc0 ls0 ws0">mentary GPS/INS navigation tools using extended</div><div class="t m0 x6 h7 y4a ff6 fs4 fc0 sc0 ls0 ws0">tightly coupled Kalman ﬁlters. When the vehicles</div><div class="t m0 x6 h7 y4b ff6 fs4 fc0 sc0 ls0 ws0">are not collaborating with each other, their observa</div><div class="t m0 x6 h7 y4c ff6 fs4 fc0 sc0 ls0 ws0">tions consist of acceleration and angular velocity mea</div><div class="t m0 x6 h7 y4d ff6 fs4 fc0 sc0 ls0 ws0">surements for the INS, together with pseudoranges as</div><div class="t m0 x6 h7 y4e ff6 fs4 fc0 sc0 ls0 ws0">measured by the GPS receiver.</div><div class="t m0 x11 h7 y4f ff6 fs4 fc0 sc0 ls0 ws0">An alternate method for aquiring accurate and</div><div class="t m0 x6 h7 y50 ff6 fs4 fc0 sc0 ls0 ws0">robust navigation of a single vehicle in urban envi</div><div class="t m0 x6 h7 y51 ff6 fs4 fc0 sc0 ls0 ws0">ronments is Simultaneous Localization and Mapping</div><div class="t m0 x6 h7 y52 ff6 fs4 fc0 sc0 ls0 ws0">(SLAM). In SLAM, a range measuring device (e.g.</div><div class="t m0 x6 h7 y53 ff6 fs4 fc0 sc0 ls0 ws0">a laser range ﬁnder) is used to extract features from</div><div class="t m0 x6 h7 y54 ff6 fs4 fc0 sc0 ls0 ws0">the environment. Accurate navigation will be accom</div><div class="t m0 x6 h7 y55 ff6 fs4 fc0 sc0 ls0 ws0">plished as long as the features are correctly associ</div><div class="t m0 x6 h7 y56 ff6 fs4 fc0 sc0 ls0 ws0">ated. A comparison between this technique and the</div><div class="t m0 x6 h7 y57 ff6 fs4 fc0 sc0 ls0 ws0">collaborative GPS/INS methods mentioned above is</div><div class="t m0 x6 h7 y58 ff6 fs4 fc0 sc0 ls0 ws0">also done in this paper.</div><div class="t m0 x11 h7 y59 ff6 fs4 fc0 sc0 ls0 ws0">Simulations for a carefully chosen urban scenario</div><div class="t m0 x6 h7 y5a ff6 fs4 fc0 sc0 ls0 ws0">are performed. The results indicate increased accu</div><div class="t m0 x6 h7 y5b ff6 fs4 fc0 sc0 ls0 ws0">racy when using the investigated algorithms.</div><div class="t m0 x11 h7 y5c ff6 fs4 fc0 sc0 ls0 ws0">Collaborative navigation opens up for cheap navi</div><div class="t m0 x6 h7 y5d ff6 fs4 fc0 sc0 ls0 ws0">gational platforms where several relatively simple ve</div><div class="t m0 x6 h7 y5e ff6 fs4 fc0 sc0 ls0 ws0">hicles can achieve the same performance as expensive</div><div class="t m0 x6 h7 y5f ff6 fs4 fc0 sc0 ls0 ws0">and complex platforms.</div><div class="t m0 x6 h6 y60 ff4 fs3 fc0 sc0 ls0 ws0">1 Introduction</div><div class="t m0 x6 h7 y61 ff6 fs4 fc0 sc0 ls0 ws0">One of the main problems with navigation systems</div><div class="t m0 x6 h7 y62 ff6 fs4 fc0 sc0 ls0 ws0">based on GNSS (Global Navigation Satellite System)</div><div class="t m0 x6 h7 y63 ff6 fs4 fc0 sc0 ls0 ws0">is the degradation of their performance when some</div><div class="t m0 x6 h7 y64 ff6 fs4 fc0 sc0 ls0 ws0">or all of the satellites are occluded by for example</div><div class="t m0 x6 h7 y65 ff6 fs4 fc0 sc0 ls0 ws0">buildings, vegetation, or jamming. An aiding sys</div><div class="t m0 x6 h7 y66 ff6 fs4 fc0 sc0 ls0 ws0">tem consisting of a digital map or other information</div><div class="t m0 x6 h7 y67 ff6 fs4 fc0 sc0 ls0 ws0">about the environment will be of little use in such</div><div class="t m0 x6 h7 y68 ff6 fs4 fc0 sc0 ls0 ws0">occluded areas if warfare has been in progress for a</div><div class="t m0 x6 h7 y69 ff6 fs4 fc0 sc0 ls0 ws0">long time so that maps and other information will</div><div class="t m0 x6 h7 y6a ff6 fs4 fc0 sc0 ls0 ws0">not correspond to reality.</div><div class="t m0 x11 h7 y6b ff6 fs4 fc0 sc0 ls0 ws0">Future wars will most likely take place in urban</div><div class="t m0 x6 h7 y6c ff6 fs4 fc0 sc0 ls0 ws0">areas with buildings, where satellite navigation with</div><div class="t m0 x6 h7 y6d ff6 fs4 fc0 sc0 ls0 ws0">GNSS will be greatly aggravated by signal shadow</div><div class="t m0 xb h7 y6e ff6 fs4 fc0 sc0 ls0 ws0">ing and multipath. Use of GPS-aided navigation</div><div class="t m0 xb h7 y6f ff6 fs4 fc0 sc0 ls0 ws0">along a street with tall surrounding buildings often</div><div class="t m0 xb h7 y70 ff6 fs4 fc0 sc0 ls0 ws0">means that only satellites along that street can be</div><div class="t m0 xb h7 y71 ff6 fs4 fc0 sc0 ls0 ws0">used, which can result in large or even unlimited er</div><div class="t m0 xb h7 y72 ff6 fs4 fc0 sc0 ls0 ws0">rors. Therefore there is a need to develop new and</div><div class="t m0 xb h7 y73 ff6 fs4 fc0 sc0 ls0 ws0">improved navigation algorithms for use in urban en</div><div class="t m0 xb h7 y74 ff6 fs4 fc0 sc0 ls0 ws0">vironments. In this work, some such methods are</div><div class="t m0 xb h7 y75 ff6 fs4 fc0 sc0 ls0 ws0">investigated. Beyond what is required for a tradi</div><div class="t m0 xb h7 y76 ff6 fs4 fc0 sc0 ls0 ws0">tional navigation system for a sole navigation plat</div><div class="t m0 xb h7 y77 ff6 fs4 fc0 sc0 ls0 ws0">form, these methods also require communication and</div><div class="t m0 xb h7 y78 ff6 fs4 fc0 sc0 ls0 ws0">the possibility to measure the relative range or range</div><div class="t m0 xb h7 y79 ff6 fs4 fc0 sc0 ls0 ws0">vectors to other platforms in the neighborhood.</div><div class="t m0 xc h7 y7a ff6 fs4 fc0 sc0 ls0 ws0">A group of unmanned ground vehicles (UGV:s) can</div><div class="t m0 xb h7 y7b ff6 fs4 fc0 sc0 ls0 ws0">be used to solve the task of searching through an ur</div><div class="t m0 xb h7 y7c ff6 fs4 fc0 sc0 ls0 ws0">ban environment by diﬀerent role casting. One of</div><div class="t m0 xb h7 y7d ff6 fs4 fc0 sc0 ls0 ws0">the UGV:s then ought to position itself in an open</div><div class="t m0 xb h7 y7e ff6 fs4 fc0 sc0 ls0 ws0">area with good satellite availability, e.g. in a street</div><div class="t m0 xb h7 y7f ff6 fs4 fc0 sc0 ls0 ws0">crossing or in a wide street. It is then possible for the</div><div class="t m0 xb h7 y80 ff6 fs4 fc0 sc0 ls0 ws0">other UGV:s to explore a narrow alley as long as they</div><div class="t m0 xb h7 y81 ff6 fs4 fc0 sc0 ls0 ws0">have line of sight and communication and can mea</div><div class="t m0 xb h7 y82 ff6 fs4 fc0 sc0 ls0 ws0">sure the range or range vector to the ﬁrst UGV, thus</div><div class="t m0 xb h7 y83 ff6 fs4 fc0 sc0 ls0 ws0">getting aiding information. Here it is assumed that</div><div class="t m0 xb h7 y84 ff6 fs4 fc0 sc0 ls0 ws0">the conditions for range measurements to be possible</div><div class="t m0 xb h7 y85 ff6 fs4 fc0 sc0 ls0 ws0">and communication between the vehicles established</div><div class="t m0 xb h7 y86 ff6 fs4 fc0 sc0 ls0 ws0">are one and the same, viz. existence of LOS. Figures</div><div class="t m0 xb h7 y87 ff6 fs4 fc0 sc0 ls0 ws0">4 and 5 illustate two UGV:s with the task to recon</div><div class="t m0 xb h7 y88 ff6 fs4 fc0 sc0 ls0 ws0">noitre an urban environment. They have diﬀerent</div><div class="t m0 xb h7 y89 ff6 fs4 fc0 sc0 ls0 ws0">satellites in their respective line of sight. By means</div><div class="t m0 xb h7 y8a ff6 fs4 fc0 sc0 ls0 ws0">of new navigation strategies, based on collaboration,</div><div class="t m0 xb h7 y8b ff6 fs4 fc0 sc0 ls0 ws0">communication, and relative distances, the position</div><div class="t m0 xb h7 y8c ff6 fs4 fc0 sc0 ls0 ws0">errors for both vehicles can be reduced.</div><div class="t m0 xc h7 y8d ff6 fs4 fc0 sc0 ls0 ws0">In this work mainly two separate navigation meth</div><div class="t m0 xb h7 y8e ff6 fs4 fc0 sc0 ls0 ws0">ods, SLAM/INS and GPS/INS are investigated for</div><div class="t m0 xb h7 y8f ff6 fs4 fc0 sc0 ls0 ws0">the case of navigating a sole navigation platform.</div><div class="t m0 xb h7 y90 ff6 fs4 fc0 sc0 ls0 ws0">The methods are compared and discussed to inves</div><div class="t m0 xb h7 y91 ff6 fs4 fc0 sc0 ls0 ws0">tigate the advantages and possibility of combining</div><div class="t m0 xb h7 y92 ff6 fs4 fc0 sc0 ls0 ws0">them in a centralized manner to a single method. The</div><div class="t m0 xb h7 y93 ff6 fs4 fc0 sc0 ls0 ws0">SLAM/INS is mainly based on laser range measure</div><div class="t m0 xb h7 y94 ff6 fs4 fc0 sc0 ls0 ws0">ments of the surrounding environment and performes</div><div class="t m0 xb h7 y95 ff6 fs4 fc0 sc0 ls0 ws0">well in an environment with many and apparent geo</div><div class="t m0 xb h7 y96 ff6 fs4 fc0 sc0 ls0 ws0">metrical features, e.g. walls. The unaided GPS/INS</div><div class="t m0 xb h7 y97 ff6 fs4 fc0 sc0 ls0 ws0">method on the other hand performs the best on open</div><div class="t m0 xb h7 y98 ff6 fs4 fc0 sc0 ls0 ws0">plains outside cities.</div><div class="t m0 xc h7 y99 ff6 fs4 fc0 sc0 ls0 ws0">In [2], collaboration is investigated for a scenario</div><div class="t m0 xb h7 y9a ff6 fs4 fc0 sc0 ls0 ws0">with two robots and two landmarks. The position</div><div class="t m0 xb h7 y9b ff6 fs4 fc0 sc0 ls0 ws0">and orientation uncertainty are investigated for a</div><div class="c xd y3f w2 h8"><div class="t m0 xe h9 y40 ff7 fs5 fc0 sc0 ls0 ws0">1115</div></div><div class="c xf y41 w3 ha"><div class="t m0 x10 h9 y42 ff7 fs5 fc0 sc0 ls0 ws0">ION NTM 2004, 26-28 January 2004, San Diego, CA</div></div></div><div class="pi" data-data='{"ctm":[1.568627,0.000000,0.000000,1.568627,0.000000,0.000000]}'></div></div>

<div id="pf3" class="pf w0 h0" data-page-no="3"><div class="pc pc3 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/625b1a8abe9ad24cfafdda5d/bg3.jpg"><div class="t m0 x6 h7 y43 ff6 fs4 fc0 sc0 ls0 ws0">case with no interruption of LOS and with communi</div><div class="t m0 x6 h7 y44 ff6 fs4 fc0 sc0 ls0 ws0">cation at all time, where both vehicle and landmark</div><div class="t m0 x6 h7 y45 ff6 fs4 fc0 sc0 ls0 ws0">states are estimated in a centralized EKF.</div><div class="t m0 x11 h7 y46 ff6 fs4 fc0 sc0 ls0 ws0">Diﬀerent group formations using bearing measure</div><div class="t m0 x6 h7 y9c ff6 fs4 fc0 sc0 ls0 ws0">ments only will result in diﬀerent navigation perfor</div><div class="t m0 x6 h7 y9d ff6 fs4 fc0 sc0 ls0 ws0">mance, [1].</div><div class="t m0 x11 h7 y9e ff6 fs4 fc0 sc0 ls0 ws0">[4] presents a probabilistic algorithm for collabo</div><div class="t m0 x6 h7 y9f ff6 fs4 fc0 sc0 ls0 ws0">rative mobile robot localization, where relative loca</div><div class="t m0 x6 h7 ya0 ff6 fs4 fc0 sc0 ls0 ws0">tions are estimated on the basis of bearing and range</div><div class="t m0 x6 h7 ya1 ff6 fs4 fc0 sc0 ls0 ws0">information. In [5], the focus is on coordination of</div><div class="t m0 x6 h7 ya2 ff6 fs4 fc0 sc0 ls0 ws0">multiple robots and in particular minimizing explo</div><div class="t m0 x6 h7 ya3 ff6 fs4 fc0 sc0 ls0 ws0">ration time in an unknown environment.</div><div class="t m0 x11 h7 ya4 ff6 fs4 fc0 sc0 ls0 ws0">In [9, 3], navigation in urban canyons with a high</div><div class="t m0 x6 h7 ya5 ff6 fs4 fc0 sc0 ls0 ws0">sensitivity GPS receiver is investigated. Low cost</div><div class="t m0 x6 h7 ya6 ff6 fs4 fc0 sc0 ls0 ws0">rate gyro and multpath models are shown to improve</div><div class="t m0 x6 h7 ya7 ff6 fs4 fc0 sc0 ls0 ws0">accruacy.</div><div class="t m0 x11 h7 ya8 ff6 fs4 fc0 sc0 ls0 ws0">The rest of the paper is organized as follows: in Sec</div><div class="t m0 x6 h7 ya9 ff6 fs4 fc0 sc0 ls0 ws0">tion 2, the main features of an integrated GPS/INS</div><div class="t m0 x6 h7 yaa ff6 fs4 fc0 sc0 ls0 ws0">system are described, and in Section 4 the same is</div><div class="t m0 x6 h7 yab ff6 fs4 fc0 sc0 ls0 ws0">done for a system consisting of a Simultaneous Lo</div><div class="t m0 x6 h7 yac ff6 fs4 fc0 sc0 ls0 ws0">calization And Map building algorithm (SLAM), in</div><div class="t m0 x6 h7 yad ff6 fs4 fc0 sc0 ls0 ws0">tegrated with an INS system. Section 3 introduces</div><div class="t m0 x6 h7 yae ff6 fs4 fc0 sc0 ls0 ws0">three collaboration methods with the purpose of aid</div><div class="t m0 x6 h7 yaf ff6 fs4 fc0 sc0 ls0 ws0">ing a vehicle in an urban environment, called “Vir</div><div class="t m0 x6 h7 yb0 ff6 fs4 fc0 sc0 ls0 ws0">tual Satellite” (VS), “Relative Vector” (RV), and</div><div class="t m0 x7 h7 yb1 ff6 fs4 fc0 sc0 ls0 ws0">“Shared Pseudoranges” (SP). In Section 5, a scenario</div><div class="t m0 x6 h7 yb2 ff6 fs4 fc0 sc0 ls0 ws0">is described for a simulation, the results of which are</div><div class="t m0 x6 h7 yb3 ff6 fs4 fc0 sc0 ls0 ws0">presented and analyzed in Section 6. The paper is</div><div class="t m0 x6 h7 yb4 ff6 fs4 fc0 sc0 ls0 ws0">ﬁnished by conclusions and a list of possible future</div><div class="t m0 x6 h7 yb5 ff6 fs4 fc0 sc0 ls0 ws0">works in Sections 7 and 8, respectively.</div><div class="t m0 x6 h6 yb6 ff4 fs3 fc0 sc0 ls0 ws0">2 GPS/INS</div><div class="t m0 x6 h5 yb7 ff9 fs2 fc0 sc0 ls0 ws0">2.1 GPS</div><div class="t m0 x6 h7 yb8 ff6 fs4 fc0 sc0 ls0 ws0">The vehicle V in Figure 1, equipped with a GPS</div><div class="t m0 x6 h7 yb9 ff6 fs4 fc0 sc0 ls0 ws0">receiver, is situated at the position given by the po</div><div class="t m0 x6 h7 yba ff6 fs4 fc0 sc0 ls0 ws0">sition vector x. S is a set containing the satellite</div><div class="t m0 x6 h7 ybb ff6 fs4 fc0 sc0 ls0 ws0">numbers of all the satellites that can be “seen” by V</div><div class="t m0 x6 h7 ybc ff6 fs4 fc0 sc0 ls0 ws0">at a given point in time. The relative vector from V</div><div class="t m0 x6 h7 ybd ff6 fs4 fc0 sc0 ls0 ws0">to a satellite with number i is thus x</div><div class="t m0 x12 hb ybe ffc fs6 fc0 sc0 ls0 ws0">i</div><div class="t m0 x13 h7 ybf ff6 fs4 fc0 sc0 ls0 ws0">.</div><div class="t m0 x11 h7 yc0 ff6 fs4 fc0 sc0 ls0 ws0">The set of pseudoranges consists of measurements</div><div class="t m0 x6 hc yc1 ffa fs4 fc0 sc0 ls0 ws0">ρ</div><div class="t m0 x14 hb yc2 ffc fs6 fc0 sc0 ls0 ws0">i</div><div class="t m0 x15 h7 yc3 ff6 fs4 fc0 sc0 ls0 ws0">of the magnitudes of these relative vectors for all</div><div class="t m0 x6 h7 yc4 ffa fs4 fc0 sc0 ls0 ws0">i ∈ S. They give rise to the equations</div><div class="t m0 x16 hc yc5 ffa fs4 fc0 sc0 ls0 ws0">ρ</div><div class="t m0 x17 hb yc6 ffc fs6 fc0 sc0 ls0 ws0">i</div><div class="t m0 x18 h7 yc7 ff6 fs4 fc0 sc0 ls0 ws0">= |x − x</div><div class="t m0 x19 hb yc8 ffc fs6 fc0 sc0 ls0 ws0">i</div><div class="t m0 x1a h7 yc7 ffd fs4 fc0 sc0 ls0 ws0">| + b + v</div><div class="t m0 x1b hb yc8 ffc fs6 fc0 sc0 ls0 ws0">i</div><div class="t m0 x1c h7 yc7 ffa fs4 fc0 sc0 ls0 ws0">, i ∈ S, (1)</div><div class="c x0 yc9 w4 hd"><div class="t m0 x1d he yca ff6 fs7 fc0 sc0 ls0 ws0">PSfrag replacements</div></div><div class="t m0 x1e hf ycb ffb fs7 fc0 sc0 ls0 ws0">x</div><div class="t m0 x1f h10 ycc ffc fs8 fc0 sc0 ls0 ws0">i</div><div class="t m0 x20 h11 ycb ffa fs7 fc0 sc0 ls0 ws0">, i ∈ S</div><div class="t m0 x21 hf ycd ffb fs7 fc0 sc0 ls0 ws0">x</div><div class="t m0 x22 h10 yce ffc fs8 fc0 sc0 ls0 ws0">j</div><div class="t m0 x23 h11 ycf ffa fs7 fc0 sc0 ls0 ws0">, i ∈ S</div><div class="c x0 yc9 w4 hd"><div class="t m0 x24 h12 yd0 ffb fs9 fc0 sc0 ls0 ws0">R</div><div class="t m0 x25 h13 yd1 ffc fsa fc0 sc0 ls0 ws0">j</div><div class="t m0 x26 h12 yd2 ffb fs9 fc0 sc0 ls0 ws0">R</div><div class="t m0 x27 h13 yd3 ffc fsa fc0 sc0 ls0 ws0">i</div></div><div class="t m0 x28 h11 yd4 ffa fs7 fc0 sc0 ls0 ws0">V</div><div class="t m0 x29 hf yd5 ffb fs7 fc0 sc0 ls0 ws0">x</div><div class="t m0 x28 h11 yd6 ffd fs7 fc0 sc0 ls0 ws0">······························</div><div class="t m0 xb he yd7 ff6 fs7 fc0 sc0 ls0 ws0">Figure 1: Vehicle V with two of its satellites in</div><div class="t m0 xb he yd8 ff6 fs7 fc0 sc0 ls0 ws0">Line-of-Sight.</div><div class="t m0 xb he yd9 ff6 fs7 fc0 sc0 ls0 ws0">where b is the clock bias, which has to be introduced</div><div class="t m0 xb he yda ff6 fs7 fc0 sc0 ls0 ws0">as an unknown, because of limited quality of the time</div><div class="t m0 xb he ydb ff6 fs7 fc0 sc0 ls0 ws0">measurement on the receiver side. v</div><div class="t m0 x2a h10 ydc ffc fs8 fc0 sc0 ls0 ws0">i</div><div class="t m0 x2b he ydd ff6 fs7 fc0 sc0 ls0 ws0">is an error term</div><div class="t m0 xb he yde ff6 fs7 fc0 sc0 ls0 ws0">with known statistics.</div><div class="t m0 xc he ydf ff6 fs7 fc0 sc0 ls0 ws0">If there are at least four satellites in S , approxi</div><div class="t m0 xb he ye0 ff6 fs7 fc0 sc0 ls0 ws0">mate values of b and the three components of x can</div><div class="t m0 xb he ye1 ff6 fs7 fc0 sc0 ls0 ws0">be calculated at the given instant (“position ﬁx”).</div><div class="t m0 xb h14 ye2 ff9 fsb fc0 sc0 ls0 ws0">2.2 INS</div><div class="t m0 xb he ye3 ff6 fs7 fc0 sc0 ls0 ws0">The common process model for all the navigation</div><div class="t m0 xb he ye4 ff6 fs7 fc0 sc0 ls0 ws0">methods that are to be compared consists of the dif</div><div class="t m0 xb he ye5 ff6 fs7 fc0 sc0 ls0 ws0">ferential equations for a mechanical system, whose</div><div class="t m0 xb he ye6 ff6 fs7 fc0 sc0 ls0 ws0">position and orientation at any moment are described</div><div class="t m0 xb he ye7 ff6 fs7 fc0 sc0 ls0 ws0">by the state equations (the navigation equations)</div><div class="t m0 x2c h11 ye8 ffa fs7 fc0 sc0 ls0 ws0">d</div><div class="t m0 x2d h11 ye9 ffa fs7 fc0 sc0 ls0 ws0">dt</div><div class="t m0 x2e h15 yea ffe fs7 fc0 sc0 ls0 ws0">˙x</div><div class="t m0 x2f h10 yeb ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x30 he yec ff6 fs7 fc0 sc0 ls0 ws0">= −2Ú</div><div class="t m0 x31 h10 yed ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x31 h10 yee ffc fs8 fc0 sc0 ls0 ws0">ie</div><div class="t m0 x32 h15 yec ffe fs7 fc0 sc0 ls0 ws0">˙x</div><div class="t m0 x33 h10 yef ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x34 h11 yec ffd fs7 fc0 sc0 ls0 ws0">− Ú</div><div class="t m0 x35 h10 yed ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x35 h10 yee ffc fs8 fc0 sc0 ls0 ws0">ie</div><div class="t m0 x36 h11 yf0 ffa fs7 fc0 sc0 ls0 ws0">Ú</div><div class="t m0 x37 h10 yed ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x37 h10 yee ffc fs8 fc0 sc0 ls0 ws0">ie</div><div class="t m0 x38 hf yf0 ffb fs7 fc0 sc0 ls0 ws0">x</div><div class="t m0 x39 h10 yed ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x3a he yf0 ff6 fs7 fc0 sc0 ls0 ws0">+ C</div><div class="t m0 x23 h10 yed ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x23 h10 yee ffc fs8 fc0 sc0 ls0 ws0">b</div><div class="t m0 x3b he yf1 ff6 fs7 fc0 sc0 ls0 ws0">˜</div><div class="t m0 x3c hf yf2 ffb fs7 fc0 sc0 ls0 ws0">a</div><div class="t m0 x3d h10 yf3 ffc fs8 fc0 sc0 ls0 ws0">b</div><div class="t m0 x3e he yf4 ff6 fs7 fc0 sc0 ls0 ws0">+ g</div><div class="t m0 x3f h10 yf5 ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x40 he yf4 ffa fs7 fc0 sc0 ls0 ws0">, (2)</div><div class="t m0 x2c h11 yf6 ffa fs7 fc0 sc0 ls0 ws0">d</div><div class="t m0 x2d h11 yf7 ffa fs7 fc0 sc0 ls0 ws0">dt</div><div class="t m0 x41 hf yf8 ffb fs7 fc0 sc0 ls0 ws0">x</div><div class="t m0 x2f h10 yf9 ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x30 he yfa ff6 fs7 fc0 sc0 ls0 ws0">= ˙x</div><div class="t m0 x42 h10 yfb ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x28 he yfa ffa fs7 fc0 sc0 ls0 ws0">, (3)</div><div class="t m0 x2d h11 yfc ffa fs7 fc0 sc0 ls0 ws0">d</div><div class="t m0 x43 h11 yfd ffa fs7 fc0 sc0 ls0 ws0">dt</div><div class="t m0 x44 h11 yfe ffa fs7 fc0 sc0 ls0 ws0">C</div><div class="t m0 x2f h10 yff ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x45 h10 y100 ffc fs8 fc0 sc0 ls0 ws0">b</div><div class="t m0 x30 he y101 ff6 fs7 fc0 sc0 ls0 ws0">= C</div><div class="t m0 x46 h10 y102 ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x42 h10 y103 ffc fs8 fc0 sc0 ls0 ws0">b</div><div class="t m0 x47 h11 y101 ffa fs7 fc0 sc0 ls0 ws0">Ú</div><div class="t m0 x48 h10 y102 ffc fs8 fc0 sc0 ls0 ws0">b</div><div class="t m0 x48 h10 y103 ffc fs8 fc0 sc0 ls0 ws0">eb</div><div class="t m0 x49 he y101 ffa fs7 fc0 sc0 ls0 ws0">, (4)</div><div class="t m0 xb he y104 ff6 fs7 fc0 sc0 ls0 ws0">where x</div><div class="t m0 x26 h10 y105 ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x25 he y106 ff6 fs7 fc0 sc0 ls0 ws0">is the position vector of components in the</div><div class="t m0 xb he y107 ff6 fs7 fc0 sc0 ls0 ws0">Cartesian Earth frame (e-frame), C</div><div class="t m0 x4a h10 y108 ffc fs8 fc0 sc0 ls0 ws0">e</div><div class="t m0 x21 h10 y109 ffc fs8 fc0 sc0 ls0 ws0">b</div><div class="t m0 x23 he y10a ff6 fs7 fc0 sc0 ls0 ws0">is the trans</div><div class="t m0 xb he y10b ff6 fs7 fc0 sc0 ls0 ws0">formation matrix from the vehicle (b-)frame to the</div><div class="t m0 xb he y10c ffa fs7 fc0 sc0 ls0 ws0">e-frame.</div><div class="t m0 x4b he y10d ff6 fs7 fc0 sc0 ls0 ws0">˜</div><div class="t m0 x4b h15 y10c ffe fs7 fc0 sc0 ls0 ws0">a</div><div class="t m0 x4c h10 y10e ffc fs8 fc0 sc0 ls0 ws0">b</div><div class="t m0 x1e he y10f ff6 fs7 fc0 sc0 ls0 ws0">is the measured b-frame acceleration vec</div><div class="t m0 xb he y110 ff6 fs7 fc0 sc0 ls0 ws0">tor components and Ú</div><div class="t m0 x4d h10 y111 ffc fs8 fc0 sc0 ls0 ws0">b</div><div class="t m0 x4d h10 y112 ffc fs8 fc0 sc0 ls0 ws0">eb</div><div class="t m0 x4e he y113 ff6 fs7 fc0 sc0 ls0 ws0">is the skew-symmetric ma</div><div class="c xd y3f w2 h8"><div class="t m0 xe h9 y40 ff7 fs5 fc0 sc0 ls0 ws0">1116</div></div><div class="c xf y41 w3 ha"><div class="t m0 x10 h9 y42 ff7 fs5 fc0 sc0 ls0 ws0">ION NTM 2004, 26-28 January 2004, San Diego, CA</div></div></div><div class="pi" data-data='{"ctm":[1.568627,0.000000,0.000000,1.568627,0.000000,0.000000]}'></div></div>