Adaptive Cruise Control by Gurulingesh R. 03329008 Kanwal Rekhi School of Information Technology Indian Institute of Technology Bombay

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

Motivation

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

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.

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…

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…

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

Precedence Graph showing communication relation b Wheel S IR S f Speed Set Throttle S Brake S c d e Throttle A Brake A Curr_Thr Pos Curr_Br Pos

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

Block Diagram

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

Task Graph

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.

Flow Chart

Flow Chart (cont…)

State Diagram

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

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

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

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

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. 1028-1033 . 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. 412-420. 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. 53-57. 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.