Adaptive cruise control functionality ppt

Adaptive cruise control

1. Adaptive Cruise Control

2. INTRODUCTION:- What is Adaptive Cruise Control? Adaptive Cruise Control (ACC) is an automotive feature that allows a vehicle's cruise control system to adapt the vehicle's speed to the traffic environment. A Sensor system attached to the front of the vehicle is used to detect whether slower moving vehicles are in the ACC vehicle's path. Introduced in 1970’s in USA. This system is now available in luxury cars like Mercedes S-class, Jaguar XJ, Volvo trucks etc … 2

3. DEFINITIONS:- Adaptive Cruise Control (ACC) – An enhancement to a conventional cruise control system which allows the ACC vehicle to follow a forward vehicle at an appropriate distance. ACC vehicle – the subject vehicle equipped with the ACC system. Active brake control – a function which causes application of the brakes without driver application of the brake pedal. Clearance – distance from the forward vehicle's trailing surface to the ACC vehicle's leading surface. 3

4. SENSOR OPTIONS Currently four means of object detection are technically feasible and applicable in a vehicle environment . They are: RADAR LIDAR VISION SENSORS ULTRASONIC SENSOR 4

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6. 6 A Brief History Early 1970s become the beginning of the creation of radar in the field of automotive. One of them, in 1970 a company called VDO introduce a radar 10 GHz installed at car. They introduce a radar in the rooftop of the car. 4 years later AEG-Telefunken company introduce radar 35 GHz, and the next year SEL company (Standard Electric Lorenz) introduce radar with the frequency of the 16 GHz. 10 GHz automotive radar system built by VDO in the early 1970s 35 GHz automotive radar system built by AEG-Telefunken in 1974 16 GHz automotive radar system built by Standard Electric Lorenz (SEL) in 1975

7. Configuration schematic of DISTRONIC PLUS, where orange is a 77 GHz LRR-sensor and green is a 24 GHz SRR-sensor (Source: Daimler AG, Stuttgart, Germany). At the first time, radar used to detect the objects (car, truck, motorcycle, pedestrians) at a relatively close. But with technology development, radar can also used to detect objects on a great distance . 7

8. 8 Pr : The Received Power. Pt : The Transmitted Power. L sys : System Losses. R : Distance to the target. : Gr,Gt : Gain from receiver and transmitter. : Related to wavelength.   8

9. RADAR CROSS SECTION Mazda 6 Mono-static RCS Radar cross-section ( RCS ) is a measure of how detectable an object is with a radar . A larger RCS indicates that an object is more easily detected. 9 Typically characterized as multiple separate scattering centers - Single RCS

10. 10 Distance Measurement Method Direct Propagation (Doppler Effect) There are two primary methods of measuring distance using radar. The first is known as the direct propagation method and measures the delay associated with reception of the reflected signal which can be correlated to the distance of the reflecting object as a function of the speed of light and the period or rather, the time delay in the transmission and receiving of the waves. ;  

11. - FMCW (Frequency Modulated Continous Wave) The second method is known as the indirect propagation method or the Frequency Modulated Continuous Wave (FMCW) method. For indirect propagation, a modulated frequency is sent and received, the difference in the frequency can be used to directly determine the distance as well as the relative speed of the object. 11

12. 12 Radar Application in a Car

13. 13 Long Range Radar – LRR 55 dBm transmit power 10 – 250 m Range Range Resolution: 0.25 m Narrow Beam Looking Ahead: ACC Short Range Radar – SRR -9 dBm /Hz transmit power 15cm – 30m Range Range Resolution: 3.75 cm Parking Aid, Close Proximity to Vehicle Medium Range Radar – MRR -9 dBm /Hz transmit power 77-81 GHz Band with 600 MHz BW 1-100 m Range Range Resolution: 0.25 m Medium Distance: CTA

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15. Specifications 15

16. 16 Radar Cruise Control (Making long highway drives easier and less tiring by maintaining a distance with the vehicle ahead). While staying within a preset speed range, the system maintains an appropriate distance between vehicles, helping make long highway drives less tiring. The system operates at all speeds, enabling to follow the vehicle ahead in low speed. This, in turn, helps reduce driver fatigue even in traffic congestion . This system has three conditions:

17. PRINCIPLE :- How does it work? If a slower moving vehicle is detected, the ACC system will slow the vehicle down and control the clearance, or time gap, between the ACC vehicle and the forward vehicle. If the system detects that the forward vehicle is no longer in the ACC vehicle's path, the ACC system will accelerate the vehicle back to its set cruise control speed. This operation allows the ACC vehicle to autonomously slow down and speed up with traffic without intervention from the driver. The method by which the ACC vehicle's speed is controlled is via engine throttle control and limited brake operation. 17

18. 18 [1] Cruise control at preset speeds The vehicle will drive at a constant preset speed. [2] Control of deceleration cruising and follow-up cruising Millimeter-wave radar determines the distance between vehicles. By adjusting speed within a preset range depending on the speed of the preceding vehicle, the system maintains a safe distance while ensuring follow-up and deceleration cruising.

19. 19 [3] Acceleration speed control Sensors (a camera and millimeter-wave radar) detect vehicles moving in and out of the lane ahead. This helps ensure smooth acceleration. [4] Stop maintenance control (when all-speed cruise control is available in system) The system slows or stops your vehicle when the preceding vehicle slows or stops. When the preceding vehicle speeds up, the system makes your vehicle accelerate accordingly, until it resumes the preset speed. Stop Sensor Go Sensor

20. 20 60 mph set speed 60 mph → 50 mph 50 mph 50 mph → 60 mph set speed 50 mph Adaptive Cruise Control

21. Adaptive Cruise Control (ACC) NO VEHICLE AHEAD 65 MPH 55 MPH VEHICLE DETECTED AHEAD 65 MPH to 55 MPH 55 MPH 55 MPH 55 MPH Driving at a Set Speed Vehicles Not in Lane Rejected 1. Constant Speed Driving 2. Deceleration Control Speed Reduced From 65 MPH to 55 MPH 3. Tracking Control Minimum Set Following Distance Maintained Set Following Distance

22. 55 MPH to 65 MPH 55 MPH VEHICLE CHANGES LANES 55 MPH to 45 MPH 65 MPH to 45 MPH 45 MPH to 65 MPH 6. Changing Lanes 45 MPH Driver Changes Lanes & Uses Turn Signal – Speed Increased to 65 MPH 4. Acceleration Control Speed Increased from 55 MPH Back to 65 MPH 5. Deceleration Control Speed Reduced From 55 MPH to 45 MPH Using Throttle, Engine Brake and Tractor Foundation Brakes VEHICLE CUTS IN AND SLOWS 55 MPH New Lead Vehicle detected, significantly inside set following distance Vehicle ahead out of lane & disregarded, no lead vehicle assigned

23. 65 MPH to 55 MPH 9. Disengagement Driver Actuates Brake Pedal to Disengage 7. Roll Control 65 MPH to 50 MPH ACC Yaw Rate Sensor Senses Excessive Lateral “G” Forces and Throttles Engine Down 65 MPH to 50 MPH 8. Bend Adjustment Lead Vehicle Non-Lead Vehicle ACC Yaw Rate Sensor adjusts detection zone for turn

24. Sequence t0 Object tracked Avoidance maneuver not possible time t2 t3 t4 Engine Torque Limitation Brake Activation Potential rear end collision detected Hard braking required to prevent collision t1 System Reactions: Crash prevented or mitigated Warning Tone and Lamp Haptic Warning Collision warning: Haptic (short brake pulse) Automatic braking to assist driver in collision mitigation Distance Alert: Visual and Audible

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26. Front Sensing: ZF’s Next Gen Camera+ Radar Integrated System 26 Radar - ZF AC1000T (77Ghz) Object Detection & AEBS: Vehicles: Cars, Trucks, Buses, Motorcycles VRU’s; Adults, Children (fully visible) Bicycles Collision avoidance up to 85 mph on moving objects and up to 50 mph on stationary objects Digital beam forming for speed-adaptive Field-Of-View Triple-Mode radar beam adjusts to vehicle speed Image Processing Module Camera - ZF S-CAM 4 Industry Only Dual Lens Front camera High resolution imager of 1280 x 1080 pixels with EyeQ4 chip Viewing angles of 52° and 150° to cover long distance and close up ranges Ability to detect pedestrians, cyclists, traffic sign, static and dynamic vehicles Tracks lanes and a variety of objects up to 140m Second lens enables redundancy for L2+ automated driving due to multiple optical paths Dedicated Image Processing Module (IPM) Built on Industry leading MobilEye EyeQ4 Chips Enables the Dual Lens capability of S-CAM 4 Separate IPM also ensures scalability of the system without modifying the camera module Can be used to connect more sensors in future for a better surround view

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28. Adaptive Cruise Control 28 ACC ACC Request Type Steering Angle Driver Present Accelerator Pedal Wheel Speed Gear Position DRP Status Valve Actuation

29. Forward vehicle – any one of the vehicles in front of and moving in the same direction and traveling on the same roadway as the ACC vehicle. Set speed – the desired cruise control travel speed set by the driver and is the maximum desired speed of the vehicle while under ACC control. Target vehicle – one of the forward vehicles in the path of the ACC vehicle that is closest to the ACC vehicle. Time gap – the time interval between the ACC vehicle and the target vehicle. The 'time gap' is related to the 'clearance' and vehicle speed by: time gap = clearance / ACC vehicle speed 29

30. Different STATES (MODES) in ACC System- ACC off mode ACC standby mode ACC active mode. This consists of the following 2 modes- ACC speed control mode ACC time gap control mode

31. COMPONENTS OF AN ACC SYSTEM:- 1) ACC Module – The primary function of the ACC module is to process the radar information and determine if a forward vehicle is present. 2) Engine Control Module – The primary function of the Engine Control Module is to receive information from the ACC module and Instrument Cluster and control the vehicle's speed based on this information. 3) Brake Control Module – The primary function of the Brake Control Module is to determine vehicle speed via each wheel and to decelerate the vehicle by applying the brakes when requested by the ACC Module. 4) Instrument Cluster – The primary function of the Instrument Cluster is to process the Cruise Switches and send their information to the ACC and Engine Control Modules. 5) CAN – The Controller Area Network (CAN) is an automotive standard network that utilizes a 2 wire bus to transmit and receive data. Each node on the network has the capability to transmit 0 to 8 bytes of data in a message frame .

32. 6) Cruise Switches – The Cruise Switches are mounted on the steering wheel and have several buttons which allow the driver to command operation of the ACC system. The switches include: On : place system in the 'ACC standby' state Off : cancel ACC operation and place system in the 'ACC off' state Set + : activate ACC and establish set speed or accelerate Set - : decelerate Res : resume to set speed Coast: To decelerate or cancel the ACC system Cruise control switch Mounted on steering wheel

33. 7) Brake Switches (BS) – There are two brake switches, Brake Switch 1 (BS1) and Brake Switch 2 (BS2). When either brake switch is activated, Cruise Control operation is deactivated and the system enters 'ACC standby' state. 8) Brake Lights – When the Brake Control Module applies the brakes in response to an ACC request, it will illuminate the brake lights to warn vehicles behind the ACC vehicle that it is decelerating. 9) Sensors/Radars – Currently 4 types of radars are available. They are- LIDAR (Light Detection and Ranging) RADAR ( Radio Detection and Ranging) VISION SENSORS ULTRASONIC SENSOR

34. FUSION SENSOR- The new sensor system introduced by Fujitsu Ten Ltd. and Honda through their PATH program includes millimeter wave radar linked to a 640x480 pixel stereo camera with a 40 degree viewing angle. These two parts work together to track the car from the non-moving objects. While RADAR target is the car’s rear bumper, the stereo camera is constantly captures all objects in its field of view. 34

35. CONTROL SYSTEM INTERFACES:-

36. PHYSICAL LAYOUT OF ACC SYSTEM:-

37. ADVANTAGES:- The driver is relieved from the task of careful acceleration, deceleration and braking in congested traffics. A highly responsive traffic system that adjusts itself to avoid accidents can be developed. Since the braking and acceleration are done in a systematic way, the fuel efficiency of the vehicle is increased. 37

38. DISADVANTAGES:- A cheap version is not yet realized. A high market penetration is required if a society of intelligent vehicles is to be formed. Encourages the driver to become careless. It can lead to severe accidents if the system is malfunctioning. The ACC systems yet evolved enable vehicles to co-operate with each other vehicles and hence do not respond directly to traffic signals. 38

39. WABCO-ZF CMS Timeline 2018 2019 2022+ 2016 2013 2007 OnGuard ACTIVE Version 2.3 OnGuard ACTIVE Version 3.2 OnGuardMax Flash-able software improved to provide driver with less false alerts Full Braking on Moving and Stopped vehicles Improved algorithm allows for higher speeds to complete stops on stationary objects OnGuard ACTIVE Version 1.7 OnGuard Gen 2 OnGuard Partial Braking on moving vehicles Warning only on stationary vehicles Innovative advanced feature set addressing the needs of the market Partial Braking on Stationary objects

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