1. Adaptive Cruise Controlby
Gurulingesh R.
Kanwal Rekhi School of Information Technology
Indian Institute of Technology Bombay

2. Overview Motivation Adaptive Cruise Controller: An Example
Functional Model
Task Model
Architecture
Future Work
References

3. Motivation

4. Motivation (Cont…) Partitioning of system into TT and ET domains
Process Mapping
Optimization of parameters corresponding to communication protocol.
Sequence and Slots of TDMA (TTC)
Priorities of Messages (ETC)
Schedulability

5. Adaptive Cruise Control
automatically adjusts vehicle speed to maintain a driver-selected safe distance from the vehicle ahead in the same lane.
It then returns to the set speed when traffic clears.
Requirements:
The speed should be kept close to the SET speed, if there is no vehicle ahead.
Timegap should be maintained at x sec.

6. Requirements (cont…) Detect the manual intervention by Driver.
Indicate thru UI, the action being taken by ACC.
Should be activated above xkmph.
Velocity changes should be smooth in the speed control mode to make the ride comfortable.
Etc…

7. Functions Identified Computing Current speed of our vehicle
Leading Vehicle related Task
Controlling Speed of our Vehicle
Controlling the Throttle
Controlling the Brake
Detecting Manual Intervention
UI to the Driver
Periodicity of Tasks
Hard, Firm; Periodic, Aperiodic…

8. Components Needed Sensors: Actuators: Four Wheel Sensors
Brake Pedal Sensor
Accelerator Pedal Senor
IR Sensor
Throttle position Sensor
Brake Actuator position Sensor
Actuators:
Brake Actuator
Throttle Actuator

9. Precedence Graph showing communication relationb
Wheel S
IR S f
Speed Set
Throttle S
Brake S c d e
Throttle A
Brake A
Curr_Thr Pos
Curr_Br Pos

10. Src: Prof. Shashikant's Control System Lec-1 in DEP Mode
ACC System Design
(desired vehicle speed)
Control I/P
Physical Process
Sensors
Actuators
Adaptive
Cruise Cont.
Reference Input
Actual output
Sensor Noise
Actuator Noise
Sensed O/P
Desired
Disturbances
(accelerator pedal (throttle) position, brake pedal position)
(wheel speed sensor)
(air drag, grade,
friction etc)
(vehicle speed)
Src: Prof. Shashikant's Control System Lec-1 in DEP Mode

11. Block Diagram

12. Block Diagram (cont…) Three Control Loops:
Outer loop does the entire process of deciding whether to accelerate or decelerate or to maintain the same speed.
Two Inner loops are special actuation loops that control the throttle and brake control systems

13. Task Graph

14. ACC Control Algorithm Algorithm will mainly have three features:
maintain the speed set by the driver if there is no leading vehicle.
to adjust the speed of the vehicle appropriately to maintain the desired safe distance from leading vehicle
to switch back and forth between above two modes according to the situation.

15. Flow Chart

16. Flow Chart
(cont…)

17. State
Diagram

18. Src: Prof. Shashikant's Control System Lec-1 in DEP Mode
Process Model
Physical Process
Actual Output
Control I/P
Disturbances E G
1/Rw
1/M
Src: Prof. Shashikant's Control System Lec-1 in DEP Mode

19. Physical Positioning of the Components
Wheel Speed
Sensor FR
Sensor FL
Sensor RL
Sensor RR
Brake RL
Actuator
Brake RR
Brake FL
Brake FR
Brake Pedal Sensors
Accelerator Pedal Sensors
Radar/Sensor/Camera

20. NODE -OBSTACLE DETECTION
NODE-FL
NODE-RR
NODE-FR
NODE-RL
NODE -OBSTACLE DETECTION
MAIN-NODE
velRR-Sensor
RR-Actuator
velFR-Sensor
FR-Actuator
velRL-Sensor
RL-Actuator
velFL-Sensor
FL-Actuator
Brake-Pedal-Sensor
Accelerator-Pedal-Sensor

21. Future Work
Classifying tasks as TT and/or ET and as Soft, Hard or Firm.
Writing Algorithm
Allocation of Tasks
Schedulability
One or two similar application if time permits

22. Some of the References
Paul pop et. al. “Design Optimization of Multi-Cluster Embedded Systems for Real-Time Applications”, Date’04, Paris, France, February 16-20, 2004, pp
Jakob Axelsson, “A case Study in Heterogeneous Implementation of Automotive Real-Time Systems”, 6th International Workshop on Hardware/Software CoDesign, Seattle, March 15-18, 1998.
Krithi Ramamritham, “Allocation and Scheduling of Precedence-Related Periodic Tasks”, IEEE Transaction in Parallel and Distributed Systems, 1995, pp
Cecilia Ekelin, Jan jonsson, “Real Time System Constraints: Where do they Come From and where do they Go?”, In Proceedings of the Int’l Workshop on Real Time Constarints, Oct. 16, 1999, USA, pp
Kristina Ahlström, Jan Torin, “Design Method for Conceptual Design of By-Wire Control: Two Case Studies”, 7th Int’l conference on Engineering of Complex Computer Systems, June 11-13, 2001.