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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
• 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:
– Four Wheel Sensors– Brake Pedal Sensor– Accelerator Pedal Senor– IR Sensor– Throttle position Sensor– Brake Actuator position Sensor
• Actuators:– Brake Actuator– Throttle Actuator
g
a
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
Precedence Graph showing communication relation
Src: Prof. Shashikant's Control System Lec-1 in DEP Mode
ACC System Design
(desired vehicle speed)(desired vehicle speed)
Control I/PControl I/PPhysical Physical ProcessProcess
SensorsSensors
ActuatorsActuators
AdaptiveAdaptive
Cruise Cont.Cruise Cont.
Reference InputReference Input
Actual outputActual output
Sensor NoiseSensor Noise
Actuator NoiseActuator Noise
Sensed O/PSensed O/P
DesiredDesired
Control I/PControl I/P
DisturbancesDisturbances(accelerator pedal (throttle) position, brake pedal position)(accelerator pedal (throttle) position, brake pedal position)
(wheel speed sensor)(wheel speed sensor)
(air drag, grade,(air drag, grade,
friction etc)friction etc)
(vehicle speed)(vehicle speed)
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 Physical ProcessProcess
Actual OutputActual Output
Control I/PControl I/P
DisturbancesDisturbances
EE 1/M1/MGG 1/R1/Rww
Physical Positioning of the Components
Wheel SpeedSensor FR
Wheel SpeedSensor FL
Wheel SpeedSensor RL
Wheel SpeedSensor RR
Brake RLActuator
Brake RRActuator
Brake FLActuator
Brake FRActuator
Brake Pedal Sensors
Accelerator Pedal Sensors
Radar/Sensor/Camera
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.