【正文】 ght Turn Acceleration Deceleration Friction Limit Lateral Dynamics Based Longitudinal Dynamics Based Large Excitation Medium Excitation Small Excitation Large Excitation Small Excitation Typically, during a severe handling maneuver, vehicle experiences bined slip conditions!! Way Forward: Develop A Friction Estimator With Increased Coverage ? Pure slip methods cover almost all of the range of pure excitation ?All these methods based on pureslip assumption might not handle bined slip conditions. 23 2 2 2 2 2__2 2 2 2( ) ( ) ( 1 ) c o s ( ) ( )* * sin * c o s( ) ta n ( ) ( )xy xfr on t ri gh t fr on t ri gh tyxFF CF Fy FxCFF?? ? ? ????? ? ? ? ? ? ? ???? ? ? ?2 2 2 2 2__2 2 2 2( 1 ) c o s ( ) ( ) si n ( )( ) ( ) ta n( ) * * c o s * si nsi n( )( ) ta n ( ) ( )yxyfr on t ri gh t fr on t ri gh tyxFCFF Fy FxC?? ?????? ? ? ?? ? ? ???? ? ? ?Increase Coverage Model Based 181。 Estimation Nonlinear Least Squares Parameter Estimation ,CC???The required parameters for the estimation algorithm include: Tire load (Fz) Slip ratio (λ) Slip angle (?) (Unknown parameters being estimated) _front rightFy_front rightFy, , ,right right lef t lef tf r f rF x F x F x F x24 Integrated Friction Estimation Algorithm – Flow Diagram Pure Longitudinal Slip Pure Lateral Slip Combined Slip 181。 2%??30%??ForceSlip Method Small Slipratio Method ForceSlip Method Large Slipratio Method Yes Yes Yes Hold limlower it nonlinea r? ? ? ? ?Force Moment Method No nonlinear sat? ? ? ? ?Yes MomentSlip Method No sat???ForceSlip Method Yes Yes No Hold No Combinedslip Tire Model Based Nonlinear Least Square Parameter Estimation Algorithm No No No Yes 2%??lower threshold? ? ?Intelligent Tire ,??Path1 ? Path2? Path3? Path4 25 Path1 ? Path2? Path3? Path4 Front Left Rear Left Front Right Rear Right Motivation to Develop Advanced Chassis Control Systems for Vehicle Handling and Active Safety xyzFFF?26 AntiLock Brake System (ABS) Path1 ? Path2? Path3? Path4 The control target of ABS: Keep the wheels from locking, thus guaranteeing good controllability of the vehicle and exploiting maximally the coefficient of friction between the tire and the road Target Slip To Maximize The Brake Force Is Dependent On Road Surface Condition!! Background Braking Force Magnitudes Depend On The Tire Load ABS Module (Optimal Slip Control) (Optimal Brake Force Distribution) 27 Present ABS Control Strategy Path1 ? Path2? Path3? Path4 First part of the maneuver (about s) is used by the control system to adjust braking pressure according to tire–road adherence conditions. 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 800 . 0 50 . 10 . 1 50 . 20 . 2 50 . 30 . 3 50 . 4Norm alize d Front Ax le Brake Force [Fxf r o n t/V e hicle We ight]Normalized Rear Axle Brake Force [Fxrear/Vehicle Weight] ax= 0 . 1 g0 . 2 g0 . 3 g0 . 4 g0 . 5 g0 . 6 g0 . 7 g0 . 8 g0 . 9 g1g*ax= V e h i c le D e c e le r a t i o nOptim al Brake Force Distribution U n la d e nL a d e n ( p a y lo a d i n c r e a s e d b y 2 5 % )Payload Unladen Laden Road Surface Condition Based Target Slip Selection Tire Load Based Optimal Force Distribution Initial instants of a braking maneuver are often used by the ABS controller to detect weight distribution. Reduces Effectiveness Of The Controller v v 28 An Intelligent Tire Based Adaptive ABS Algorithm Path1 ? Path2? Path3? Path4 ?,x y zF F FIntelligent Tire Emulator Optimal Slip Selector desired?current? + ? Brake Preconditioning Module ,desired desiredxyFFeA F S M O D U L E AFS Command DYC Braking Command ABS Module Fuzzy/Sliding mode/Proportional Integral (FuzzySMCPI (FSP)) control ?bTOptimal Force Distribution Algorithm Brake Command Driver Vehicle statesVehicle Yaw Moment And Lateral Force Tracking Controller 29 Controller Performance Path1 ? Path2? Path3? Path4 Using the surface condition information from the intelligent tire makes it possible to apply a brake preconditioning algorithm amp。 allows for a considerable decrease in the stopping distance (reduction in the stopping distance scales up to %) Baseline ABS Strategy Proposed Modified ABS Strategy Test Condition: Jumpμ Straightline Braking Test Friction Estimator Performance 30 Conclusion ? This work focuses on the possibility of enhancing the performance of the ABS (Antilock Braking System)/EBD (electronic braking distribution) control system by using the additional information provided by intelligent tires. ?We expect the intelligent tire system to stimulate the development of a new generation of traction, braking and stability control systems for improving vehicle safety and performances. ? Major challenge: Meeting the power supply needs of all the electronic ponents of an intelligent tire system. Future Work ? Validate controller performance via hardwareintheloop (HIL) simulations. HIL Setup, Intelligent Transportation Laboratory Virginia Tech 31 Thank You… Questions?