MATLAB EXPO 2018

MATLAB EXPO2018Simulink and ADAMS Co Simulation for ABS & ESC testing andValidation with Physical TestL GaneshDeshmukh ChandrakantDr. Balarama KrishnaCAE DynamicsMahindra Research Valley1

Agenda:-1 Introduction2 Objective3 Vehicle & Controller Modelling4 Progressive braking test5 Sine with Dwell test6 Conclusion2

Introduction: Vehicle development process warrants changes in vehicle parameters like GVW,spring rate and damper characteristics for weight reduction and performanceimprovement initiatives. In such scenarios, virtual vehicle model with ABS will ensure the impact ofvehicle level changes on ABS and braking performance before making physicalprototype. The physical test can be reduced significantly to accelerate thedevelopment process Co-simulation model is useful to study the vehicle level changes and its impact onABS controller upfront3

Objective : Methodology is established for ADAMS-Simulink co-simulation To improve simulation accuracy for road load simulations of brake events byimplementing the ABS controller Simulink model in the Adams/Car full vehiclemodel, called coupled simulation and abbreviated as co-simulation. The co-simulation results are validated by measurements performed at MRV.4

Vehicle Modeling : Adams Model Consist offollowing subsystems' Front and rear suspensions Steering system Brake system Tires Chassis Front and rear anti rollbars Adams Input andOutput PlantsS.No1234S.No1234567891011Plant InputsFront left Pressure inputFront Right Pressure inputRear left Pressure inputRear right Pressure inputPlant OutputsFront left wheel velocityFront Right wheel velocityRear left wheel velocityRear right wheel velocityCylinder Pressure OutputChassis Velocity VxChassis Velocity VyChassis Velocity VzChassis Roll rateChassis Pitch RateChassis Yaw Rate12Steering wheel angleVehicle ModelSubsystemBrake systemSubsystemBrake systemChassissubsystemSteeringsystem5

Controller Modeling : Simulink ABS controller model has theblocks of Wheel speed sensors, Electroniccontrol unit, Hydraulic control unit andbrake system. Controller model received from Supplier Adams Model : This models need vehiclespeed, wheel speeds and master cylinderpressure as input from the Adams model.The control logic modulates the brakecaliper pressure for each wheel based on thethreshold slip control algorithm and sendback the caliper pressure to the vehicleMBD model.6

Solvers exchange: Simulink acts as a master solver in this simulation and the two solvers exchangeinformation at certain time stepsAdams outputsAdams mulation Procedure7

Co-Simulation Setup:Adams Simulink block8

Co-Simulation Setup for ABS :Adams Simulink blockInputs from ADAMS/car1. Front Left Wheel Speed2. Front Right Wheel Speed3. Rear Left Wheel Speed4. Rear Right Wheel Speed5. Vehicle Speed (Vx,Vy & Vz)6. Master Cylinder PressureOutputs from Simulink ABS1. Front Left Caliper controlled Pressure2. Front Right Caliper controlled Pressure3. Rear Left Caliper controlled Pressure4. Rear Right Caliper controlled PressureABS inputs9

Co-Simulation Setup for ABS ESC :Adams Simulink blockInputs from ADAMS/car1. Front Left Wheel Speed2. Front Right Wheel Speed3. Rear Left Wheel Speed4. Rear Right Wheel Speed5. Vehicle Speed (Vx,Vy & Vz)6. Master Cylinder Pressure7. Steering wheel8. Yaw RateESC inputsOutputs from Simulink ABS1. Front Left Caliper controlled Pressure2. Front Right Caliper controlled Pressure3. Rear Left Caliper controlled Pressure4. Rear Right Caliper controlled PressureABS inputs10

Anti Lock Braking System Introduction: ABS prevents locking of wheels during braking ABS modulates the brake line pressure independent of the pedal force, to bringthe wheel speed back to the slip level range that is necessary for optimal brakingperformance. ABS allows the driver to maintain steering control while braking and shortenbraking distances on slippery surfaces like wet or icy surfaces.11

Progressive Braking Inputs for simulation: Progressive Braking physical test was conducted in MRV The following Progressive Braking Simulation inputs are measured from testInitial vehicle velocity:120kmphPedal ratio 3Input @ pedal: Pedal force Vs timeMax pedal force 55kgfBooster input force Max pedal force * Pedal ratio12

Progressive Braking Inputs for simulation:-With ABSWith out ABS13

Progressive Braking Simulation Results :-Results14

Progressive Braking Simulation Results:-Vehicle stopping distance(m) Vehicle stopping distanceTime (s)14m lesser stopping distance is achieved in Progressive braking with ABS vehicle15

Time (s)Right Rear speed (RPM)Time (s)Left Rear speed (RPM)Left front speed (RPM) Wheel speedsRight front speed (RPM)Progressive Braking Simulation Results:-Time (s)Time (s)16

Progressive Braking Simulation Results:-Vehicle SpeedTime (s)ABS is activated same time inTesting and SimulationRight Front pressure (kmph)Vehicle speed (kmph) Vehicle Speed and Pressure ModulationPressure ModulationTime (s)17

Electronic Stability Control (ESC) : System of sensors, actuators, and computers to enhance vehicle directional stabilityprevent loss of control due to oversteer or understeer If the stability control software in the ABS control module detects a difference inthe normal rotational speeds between the left and right wheels when turning, itimmediately reduces engine power and applies counter braking at individual wheelsas needed until steering control and vehicle stability are regained18

Sine with Dwell simulation Inputs:-Initial vehicle velocity: 80 kmphSteering wheel angle : 270 deg19

Sine with Dwell with and with out ESC Animation:-With ESCWith out ESC20

Sine with Dwell simulation :-Results21

Sine with Dwell simulation Results: Yaw Rate measurement22

Sine with Dwell simulation Results:-Vehicle Lateral displacement (m) Vehicle lateral Displacement(mm) measurementTime(s)Higher lateral displacement is achieved in Vehicle with ESC model23

Sine with Dwell simulation Results: Modulation pressuresESC is applied brakes at front left means vehicle is in oversteer condition while taking right turn24

Sine with Dwell simulation Results: Lateral Acceleration and Vehicle speed25

Conclusion: Co-simulation methodology is established using Adams/Car and Matlab Simulinkfor ABS and ESC Achieved good CAE correlation with test results for Progressive braking ESC Validation is work in progress26

Thank You!!!27

Annexure: Lateral Stability Criteria Test Measurements: “Lateral stability” is defined as the ratio of vehicle yaw rate at a specified time tothe first local peak yaw rate generated by the 0.7 Hz Sine with Dwell steering reversal28

Annexure:- The responsiveness criterion will be used to measure the ability of a vehicle torespond to the driver’s inputs during an ESC intervention29

Anti Lock Braking System Introduction:- ABS prevents locking of wheels during braking ABS modulates the brake line pressure independent of the pedal force, to bring the wheel speed back to the slip level range that is necessary for optimal braking performance. ABS allows the driver to maintain steering control while braking and shorten