Design of Lane Keeping Assist

-Model based design of controller of Lane Keeping Assistance
-State machine built using Stateflow

1. S245408 Waiyuntian Lou S253778 Huanyu Su Under the instruction of: Prof. Massimiliana Carello Lane Keeping Assist (LKA) Academic Year 2018-2019 14/12/2018

2. Chapter 1 Introduction 2 -LKA is a feature that take step to keep the vehicle stay in its lane. If it detect that the vehicle is drifting out of the lane, it may gently steer the vehicle back into it. What is Lane Keeping Asist system (LKA/LKAS) According to NHTSA, about 80% of the accidents are caused by the drivers. 20% of traffic accidents are caused by departure of vehicle from its lanes. Up to 26% of all relevant accidents with injuries and fatalities can be prevented by lane keeping support. Why?

3. Chapter 1 Introduction 3 The LKA system is a auxiliary function, not a autonomous function. The driver should always touch the steering wheel. Drivers with hands-off is a misuse. The activation condition of LKA system is at least 60km/h. The curvature should be at least 250m. UN/ECE Regulations [ 1] Regulation No 79 of the Economic Commission for Europe of the United Nations (UN/ECE) — Uniform provisions concerning the approval of vehicles with regard to steering equipment [2] Regulation No 130 of the Economic Commission for Europe of the United Nations (UN/ECE) — Uniform provisions concerning the approval of motor vehicles with regard to the Lane Departure Warning System (LDWS).

4. Reference 4 [1] Guo Hongqiang , Chen Hui , Chen Jiayu . Design of Lane-based Lane Maintenance System Based on EPS[J]. Automotive Technology, 2018(08): 33-38. [2]Yu Lijiao . Design and experimental verification of lane-based auxiliary control algorithm based on EPS [D]. Jilin University, 2016. Structure of LKA control system [1] Baharom M B, Hussain K, Day A J. Design of full electric power steering with enhanced performance over that of hydraulic power-assisted steering[J]. Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering, 2013, 227(3):390-399. [2] Zhang Hailin . Lane keeping system based on electric steering [D]. Tsinghua University, 2012. [3]Cheng Shuliang . Modeling and simulation analysis of electric power steering system [D]. Chongqing University, 2016 EPS model [1]Prof. Nicola Amati. Chassis A notes. High speed cornering simplified approach [2]Yu Lijiao . Design and experimental verification of lane-based auxiliary control algorithm based on EPS [D]. Jilin University, 2016. 2 d.o.f . vehicle model

5. Reference 5 [1 ] Carlo Novara. Automatic control. Lecture 21 Lane Keeping [2] Zhang Hailin . Lane keeping system based on electric steering [D]. Tsinghua University, 2012. Driver model [ 1] Ziegler, J.G & Nichols, N. B. (1942).  "Optimum settings for automatic controllers’’  Transactions of the ASME. 64: 759–768. [2] Nyquist , H. (1932).  "Regeneration Theory".  Bell System Tech. J. USA: American Tel. & Tel. 11 (1): 126–147 Design of PID controller

6. System structure design Chapter 2

7. Chapter 2 System structure 7 It is the information acquisition system, includes various sensors and image processing modules Sensing layer Including the information processing, the lane departure warning algorithm, the driver operation state identification algorithm and the lane keeping active control algorithm. Decision layer U ses the steering system or the braking system to control the vehicle motion Execution layer

8. Chapter 2 Sensing layer 8 Steering wheel angle sensor Steering torque sensor Steering A cceleration sensors Yaw rate sensor Wheel speed sensors Dynamic of the vehicle Camera is commonly used. Lane information & car’s relative position

9. Chapter 2 Execution layer 9 A udible Visual Tactile Execution for warning Electric Power Steering (EPS). Electric Stability Program (ESP). Execution for steering

10. Control algorithm design Chapter 3

11. Chapter 3 Decision layer 11

12. Chapter 3 State D ecision Strategy 12 Shutdown Standby Intervention Target: define s ystem state α----Activation condition coefficient β----Intervention condition coefficient In order to identify the system state, we introduce 2 auxiliary coefficients.

13. Chapter 3 State D ecision Strategy 13 Determine when the LKA system should intervene the vehicle control. Reduce false warning. Avoid collisions between LKA system and the driver. T his strategy is important

14. Chapter 3 Criteria for activation 14 Switch state (ON/OFF) The clarity of the lane marking. Lane change (Ex. Turning light is on) 3 criteria should be taken into consideration The target is to define the value of coefficient α

15. Chapter 3 Criteria of intervention 15 The target is to define β For intervention: The system control the vehicle until the vehicle steer back to lane centre.   The criteria for intervention and for exit are different. TLC -----a time interval estimated according to the Time to Line Crossing algorithm . Which indicate that if the car maintains the current dynamic condition, after TLC seconds the left/right front wheel will touch the lane marking.

16. Chapter 3 Control loop 16

17. Chapter 3 Path error controller 17

18. Chapter 3 Path error controller 18 Target road centerline function Y target =0 Predicted driver model θ target depends on predicted lateral displacement(the predicted lateral displacement of vehicle a certain time)

19. Chapter 3 EPS module 19

20. Chapter 3 EPS module 20 EPS model(Electric motor + steering system) EPS PID controller

21. Chapter 3 EPS model 21 States: Current of electric motor I e Angle of motor θ e Rotation speed of motor Inputs: Voltage of electric motor U Equivalent self aligning torque T sa State space equation of EPS model

22. Chapter 3 EPS controller 22 e

23. Chapter 3 Path error controller 23

24. Chapter 3 2d.o.f car model 24 Simplest 2 d.o.f car model Neglecting self-aligning torque and aerodynamics

25. Simulation and results Chapter 4

26. Chapter 4 Simulation and results

27. Chapter 4 Simulation and results 27 V=60km/h T ϵ [1,2] Apply a steering angle to the steering wheel

28. Chapter 4 Simulation and results 28

29. Chapter 4 Simulation and results www.islide.cc 「 让 PPT 设计简单起来！」 29

30. Conclusion www.islide.cc 「 让 PPT 设计简单起来！」 30 LKA&SAE level State decision strategy&Stateflow P ath error controller EPS model&EPS controller Vehicle model CarSim verification