1. ME 455- Vehicle Dynamics and Control Active Safety Control Systems: TCS, ABS, ACC Human Driver Models for Vehicle Control Design Assoc. Prof. Dr. Pinar Boyraz April 2015

2. PART I: ACC, TCS and ABS

3. Cruise Control Outline Introduction to Cruise Control CC Modeling CC Simulation Introduction to Adaptive Control ACC Modeling ACC Simulation

4. Cruise Control System Input: buttons on the steering wheel, brake, clutch, gas pedal and feedback signal Processor Sensor Output: the throttle position

5. Modeling Newton’s Second Law: Laplace Transform:

6. Transfer Function

7. Design Specification Rise time < 5 sec Overshoot < 10% Steady-State Error < 2%

8. Open-Looped System

9. Closed-Loop w/ PI Control Kp = 100Kp = 800 and Ki = 40

10. Effect of weight of the car m = 500 kg PI Control: Kp = 800 and Ki = 40 m = 2000 kg

11. Adaptive Cruise Control So-called Active Cruise Control (ACC) Traffic flow characteristics Collision-avoidance system Not to be considered as a safety feature by automakers

12. Background First laser-based system – Toyota’s Progress, a compact luxury sedan, in 1998 First radar-based system – Nissan’s Cima 41LV-2, a luxury sedan First American ACC model – Lexus’ LS 430, in 2000

13. Function Preset and maintain the car speed Measure the distance to the preceding car and the relative speed Adjust the car speed accordingly Maximum deceleration = 3.5m/s^2

14. Adaptive Cruise Control Change gear automatically Function properly in poor weather condition Cannot pick up non-moving objects Effective in the speed between 30km-180km/h

15. Two types of ACC Radar-Based System – Three overlapping radar-beams (76-77kHz) -- Detects moving object up to 120 m – work in poor weather conditions Laser-Based System (lidar) – less expensive and easier to package – light beams are narrower than water droplet and snowflakes

16. Radar-based Adaptive Cruise Control

17. Modeling in Highway Merging By R. Sengupta and Q. Xu ACC Controller Desired Range

18. Highway Merge-In Scenario 1. At 0 sec, the preceding vehicle is traveling 12.5 m/s 2. The follower vehicle w/ACC is 150 m behind the preceding vehicle and is traveling at 25 m/s 3. At 10 sec, the third vehicle cut in in between the two vehicles

19. Simulation in Highway Merging By R. Sengupta and Q. Xu

20. Acceleration Dotted Line = Desired Acceleration Solid Line = Actual Acceleration By R. Sengupta and Q. Xu

21. Implementation

22. Distance Source ACC Response CC Response (for comparison)

23. Antilock Brake System- Outline Describe the reason for an antilock brake system (ABS) Explain the theory of operation of ABS Describe the parts of two-, three-, and four-wheel ABS Explain the differences between integral and non-integral ABS Explain how ABS provides traction control and stability enhancement Explain ABS and normal brake warning light operation

24. Introduction Ability of brakes to do their job Limited by tire grip to road surface Skids could be avoided if driver could release brake pressure just before wheel locks When wheel stops turning, friction generates heat, causing tire to lose traction Slip rate of 50% means the wheel is rolling 50% slower than freely rolling tire Maximum traction occurs at ten to twenty percent slip

26. Antilock Brakes Wheel speed sensors and computer Monitor wheel speed Wheel speed sensors measure rotational speed of the wheel Wheel locks: antilock brake controller pulsates the pressure to that wheel ABS is disabled below a certain speed ABS senses failure: system reverts to conventional-only braking Pedal feel: bump followed by rapid pulsing

27. Antilock Brake System Components Include: ABS computer Known as: electronic brake control module, controller antilock brake, or electronic brake and traction control module Sensor inputs Pressure modulator valves Self-test Wheel speed sensors Variations and wiring Hydraulic control valve assembly

30. Types of Antilock Brake Systems Integral ABS Combine master cylinder, power brake booster, ABS hydraulic circuitry in single assembly Early systems used pump for pressure Reservoir is usually much larger Some systems have pressure sensitive switch Non-integral ABS ABS unit is separate from master cylinder and is in series with brake lines Two or four wheel One, three, or four-channel

32. Two-Wheel ABS Only works on rear wheels Found on SUVs and light trucks Designed to stop a fully loaded truck Rear brakes: modulated simultaneously Centrally located, single sensor Four wheel ABS Either three or four channel Four channel: sensor on each wheel Front wheels controlled separately

33. Antilock Brake System Operation During two-wheel ABS stop: isolation valve closes Action by isolation solenoid not sufficient Dump valve cycles open and closed rapidly Pressure to rear brakes is relieved and wheels are turning Dump valve closes Three- and four-channel systems Some use single combination valve

34. Antilock Brake System Operation (cont'd.) Nonintegral systems May use motor pack Malfunction occurs in ABS system Computer shuts system off When testing ABS Pedal pulsing should be felt

36. Traction Control System Traction control system (TCS) or acceleration slip regulation (ASR) ABS limits wheel spin during acceleration Computer matches traction with engine power Controller disables traction control if brakes overheat Electronic stability control Computer stabilizes vehicle in sudden evasive maneuver Compensates for understeering and oversteering

38. PART II: HUMAN DRIVER MODELING

39. Human Factors and Driver Modeling

48. Driver Modeling

55. Driver Modeling- Example: Driver Handling Simulation

59. Driver Modeling- Example: Driver Handling Simulation- m file

61. Driver Modeling- Preview and Predictive Models

63. Driver Modeling- Preview and Predictive Models- Example

68. m file

69. Driver Modeling- Longitudinal Models

71. NEXT WEEK: MATLAB SESSION ON TRACTION CONTROL and ROLLOVER PREVENTION SYSTEMS Source: