Lecture2 - Kinematics

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1、ECE497:IntroductiontoMobileRoboticsLecture2Dr.CarlottaA.BerrySpring06-07QuoteoftheWeek“Inthefifties,itwaspredictedthatin5yearsrobotswouldbeeverywhere.Inthesixties,itwaspredictedthatin10yearsrobotswouldbeeverywhere.Intheseventies,itwaspredictedthatin2

2、0yearsrobotswouldbeeverywhere.Intheeighties,itwaspredictedthatin40yearsrobotswouldbeeverywhere...”MarvinMinskyECE497:IntroductiontoMobileRobotics-C.A.BerryLocomotion&Kinematics2KinematicsChapter3MobileRobotKinematics(3.1)MobileRobotKinematicsisthedy

3、namicmodelofhowamobilerobotbehavesKinematicsisadescriptionofmechanicalbehavioroftherobotfordesignandcontrolMobileRobotKinematicsisusedfor:PositionestimationMotionestimationECE497:IntroductiontoMobileRobotics-C.A.BerryLocomotion&Kinematics4MobileR

4、obotKinematics,2RobotsmoveunboundedwithrespecttotheirenvironmentThereisnodirectwaytomeasurerobotpositionPositionmustbeintegratedovertimeTheintegrationleadstoinaccuraciesinpositionandmotionestimationEachwheelcontributestotherobot’smotionandimpose

5、sconstraintsonrobot’smotionAlloftheconstraintsmustbeexpressedwithrespecttothereferenceframeECE497:IntroductiontoMobileRobotics-C.A.BerryLocomotion&Kinematics5RobotReferenceFrame(3.2.1)Therobot’sreferenceframeisthreeYIdimensionalincludingpositionont

6、heplaneandtheorientation,{X,Y}RR,YRTheaxes{X,Y}defineinertialglobalII,referenceframewithorigin,OXRTheangulardifferencebetweentheglobalandreferenceframesisyPPointPontherobotchassisintheXIglobalreferenceframeisspecifiedbyOxcoordinates(x,y)Robotpo

7、sitionTxyIECE497:IntroductiontoMobileRobotics-C.A.BerryLocomotion&Kinematics6RelativePositioning:OdometryandKinematicsGivenwheelvelocitiesatanygiventime,computeposition/orientationforanyfuturetimeAdvantagesSelf-containedCangetpositionsanywhe

8、realongcurvedpathsAlwaysprovidesan“estimate”ofpositionDisadvantagesRequiresaccuratemeasurementofwheelvelocitiesovertime,includingmeasuringaccelerationanddecelerationPositionerrorgrowsovertimeECE497:IntroductiontoMobileRobotics-C.A.BerryLocomotion