adaptive cruise control(1)
TRANSCRIPT
-
8/3/2019 Adaptive Cruise Control(1)
1/43
Adaptive Cruise Control
Advisor(s):
Prof. Krithi Ramamritham
Prof. S. RameshProf. Kavi Arya
Gurulingesh R.
KReSIT, IIT Bombay
-
8/3/2019 Adaptive Cruise Control(1)
2/43
Overview
Introduction
Components
Design Implementation
Results and Observations
Further Work
References
Demo/Video
-
8/3/2019 Adaptive Cruise Control(1)
3/43
Goals of the Project
Study the ACC application and to identify
Components
Algorithms Real-Time Issues
Real-Time approach to Design
Setup a basic platform
-
8/3/2019 Adaptive Cruise Control(1)
4/43
Introduction to ACC
Extension ofCruiseControl.
Operates either in
DistanceControlstate
SpeedControlstate
Des_Dist = Host_Vel * Timegap + where
Host_Vel is Host Vehicle velocity
TimeGap is set by the driver
for additional safety
-
8/3/2019 Adaptive Cruise Control(1)
5/43
Requirements
Functional: Detect leading vehicle.
Maintain desired speed.
Maintain desired timegap.
Communicate actions to User Interface
Non-Functional (timing constraints):
Response Time
Data update rate and so on
ISO Limitations:
mean dec 3.0 m/s2 (over 2 s),
acceleration 2 m/s2
-
8/3/2019 Adaptive Cruise Control(1)
6/43
Overview
Introduction
Components
Design
Implementation
Results and Observations
Further Work
References
-
8/3/2019 Adaptive Cruise Control(1)
7/43
Components of ACC
CONTROL
UNIT
SENSOR
FUSIONSENSOR
RADAR
TARGET
DETECTION
TARGET
TRACKING
USER
INTERFACE
BAC
TAC TA
BA
Sensors:
Four Wheel
Sensors, Brake
Pedal Sensor,
Throttle Pedal
Senor, Radar
Actuators:
Brake Actuator,
Throttle Actuator.
Controllers:
High level & Low
level controller.
Communication
Medium
-
8/3/2019 Adaptive Cruise Control(1)
8/43
Overview
Introduction
Components
Design
Implementation
Results and Observations
Further Work
References
-
8/3/2019 Adaptive Cruise Control(1)
9/43
Functionality and Data Flow
-
8/3/2019 Adaptive Cruise Control(1)
10/43
Controller State Diagram
State Variab
les1. Current speed
2. Cruise Status
3. Brake
4. Throttle
5. Leading Vehicle
6. Driver Intervention
Possible Events:Curr-speed > 25 km/h
Radar contact found
Driver intervention
Lead-distance > safe-dist and so on.
-
8/3/2019 Adaptive Cruise Control(1)
11/43
State Switching Issue
When to switch state?S-to-D: Curr_Dist < TimeGap * Host_Vel +
D-to-S: (Host_Vel > Des_Vel) ||
(Curr_Dist TimeGap * Host_Vel + )
Chattering
S-to-D: Curr_Dist < TimeGap * Host_Vel + - hyst
D-to-S: (Host_Vel > Des_Vel) ||
(Curr_Dist TimeGap * Host_Vel + + hyst
&& RoD 0
&& RoD 0)
where RoD is Rate of change of Distance
-
8/3/2019 Adaptive Cruise Control(1)
12/43
Task and Data Items
Tasks:
WheelTi(1i4), SpeedT, RadarT, DriverT, SwitchT,
ExceptionT, AdjLaneT, FrictionT, AdaptT, ModeSwT.
Data Items:
WheelSpeed[wi], HostVel, LeadVel, LeadDist, RoadType,
LeftLane[vi, di], RightLane[vi, di], DesAcc, DesSpeed.
-
8/3/2019 Adaptive Cruise Control(1)
13/43
Issues
1. Dynamically varying data
Prepare for the Worst
Over-Sampling
Dist
Time
-
8/3/2019 Adaptive Cruise Control(1)
14/43
Issues (cont)
2. When to Update
Unnecessary Updates
-
8/3/2019 Adaptive Cruise Control(1)
15/43
Issues (cont)
3. All Tasks and Data throughout the
system operation??
Poor CPU utilization
Not modular
Scheduling Overhead
AdaptT when lead car is near
AdjLaneT, TimeLeftT when car is far
-
8/3/2019 Adaptive Cruise Control(1)
16/43
Approach
Mode-Change System Exclusive modes of operation
Mode change leads to:
Addition of a task Change in frequency of execution
Deletion of a task
Data Repository (Neera Sharma)
updates in response to changes in the data
items (on-demand update).
-
8/3/2019 Adaptive Cruise Control(1)
17/43
Approach (cont)
Mode-Change System Dynamically varying data
All Tasks and Data throughout the system
operation
Data Repository
Dynamically varying data Derived Data Items
-
8/3/2019 Adaptive Cruise Control(1)
18/43
Issues
With mode-changes: How many modes
What triggers mode change
When to switch mode
Chattering
Mode-change delay
Schedulability
With Data Repository
How many levels
When to update
-
8/3/2019 Adaptive Cruise Control(1)
19/43
Solution to mode-change
How many?
Two: Safety-Critical(SC), Non-Safety Critical(NC)
When to switch? Finish task execution.
Mode-change delay
Boundedby longest periodicity task.
Schedulability
Static checking.
-
8/3/2019 Adaptive Cruise Control(1)
20/43
Solution to mode-change
What triggers modechange?LeadDist RoD Mode
FAR DECR-FAST SC
FAR INCR-FAST NC
FAR DECR-SLOW NC
FAR INCR-SLOW NC
CLOSE ---- SC
FOLLOW ---- RETAINLeadDist & RoD
LeadDist OR
RoDO
R
-
8/3/2019 Adaptive Cruise Control(1)
21/43
Solution to mode-change
Chattering
In SC Mode:
(Safe_Dist+
< Curr_Dist Follow_Dist-
) ||(Follow_Dist+ < Curr_Dist Radar_Dist && RoD = DECR-FAST) ||
(Follow_Dist- < Curr_Dist Follow_Dist+ && Curr_Mode = SC)
In NC Mode:
(Follow_Dist+ < Curr_Dist Radar_Dist && RoD DECR-FAST) ||
(Follow_Dist- < Curr_Dist Follow_Dist+ && Curr_Mode = NC)
-
8/3/2019 Adaptive Cruise Control(1)
22/43
Solution to Data Repository
How many levels
Example:
First-Level: Raw data from radar, wheel sensor, etc
Second-Level: Host Velocity, Lead Distance, etc
-
8/3/2019 Adaptive Cruise Control(1)
23/43
Solution to Data Repository
When to update
First-Level: Continous
Second-Level: On-Demand based on R(d)
-
8/3/2019 Adaptive Cruise Control(1)
24/43
Scheduling
Mode-Change approach
All Tasks are identified in advance.
All tasks are periodic. RMS
Data Repository approach
Aperiodic tasks.
Guarantee to aperiodic tasks.
CBS
-
8/3/2019 Adaptive Cruise Control(1)
25/43
Overview
Introduction
Components
Design Implementation
Results and Observations
Further Work
References
-
8/3/2019 Adaptive Cruise Control(1)
26/43
Implementation
Hardware
Ultra-sonic Distance Meter (UDM)
Purpose: leading vehicle
distance
Range: 1.3m
Accuracy: 2.5cm
Sampling Rate: 1 per sec
Shaft Encoder (ENC)
Purpose: Host Velocity
Resolution: 1 cm per step
Communication (PC Robot)
Printer Port Ver 1: Leader and Follower
Hardware Expert: SachitanandMalewar
-
8/3/2019 Adaptive Cruise Control(1)
27/43
Follower Version-2
Front view Side View
UDM
Range: 2m, Accuracy: 1cm, Sampling Rate: 10 per sec
Shaft Encoder
Resolution: 0.4cm
-
8/3/2019 Adaptive Cruise Control(1)
28/43
Software Implementation
Two-Level Repository Approach
CBS Scheduling
-
8/3/2019 Adaptive Cruise Control(1)
29/43
Software Implementation
Mode-Change Approach
Same task structure with:
dummy tasks in each mode.
Mode-switch task.
All Tasks are periodic.
RMS Scheduling
Mode change after the completion of least
priority task.
Delay bounded by its periodicity.
-
8/3/2019 Adaptive Cruise Control(1)
30/43
Software Implementation
Mode-Change Approach (cont)
Task Periodicity (in seconds):
UDM_WR: 0.2 ENC_WR: 0.3
UDM_RD, UDM_VEL: 0.4
ENC_RD: 0.6
CTRL_TASK: 0.7
MODE_SW: 0.4 ( = UDM_RD)
-
8/3/2019 Adaptive Cruise Control(1)
31/43
Software Implementation
Data Logging:
RT-FIFO RTLinux Architecture
-
8/3/2019 Adaptive Cruise Control(1)
32/43
Overview
Introduction
Components
Design Implementation
Results andObservations
Further Work
References
-
8/3/2019 Adaptive Cruise Control(1)
33/43
Results & Observations
Cruise Control Operation
Set speed = 35 m/s2
Open-loop lowercontroller
Shaft encoder
error
-
8/3/2019 Adaptive Cruise Control(1)
34/43
Results & Observations
Constant Leading Distance
LeadDist = 63 cm
Timegap = 1.8 s
-
8/3/2019 Adaptive Cruise Control(1)
35/43
Results & Observations
Linear Increase-Decrease Timegap = 1.5 s
-
8/3/2019 Adaptive Cruise Control(1)
36/43
Results & Observations
Two-Level Repository
Tested for UDM_RD Task
Lead Dist = 69 cm
-
8/3/2019 Adaptive Cruise Control(1)
37/43
Overview
Introduction
Components
Design Implementation
Results and Observations
FurtherWork
References
-
8/3/2019 Adaptive Cruise Control(1)
38/43
More Experiments
Effect of mode-change delay
Improve in CPU utilization
LeadDist, RoD values
Periodicity of tasks, data update rate
Chattering b/w SC-NC Mode Switching
BETTER VEHICLE
-
8/3/2019 Adaptive Cruise Control(1)
39/43
Further Work
More experiments to evaluate the design.
Implementing two-level repository on Real-
Time Data Base.
Is printer port good enough or need forRT-
Communication (TTP/TTCAN/CAN).
Merging with Lane Changing.
Inter-Vehicle communication.
Formal modeling using UPPAAL/KRONOS.
-
8/3/2019 Adaptive Cruise Control(1)
40/43
Goals Revisited
Study the ACC application and to identify
Components
Algorithms
Real-Time Issues
Real-Time approach to Design
Setup a basic platform
-
8/3/2019 Adaptive Cruise Control(1)
41/43
References
Petros Ioannou; Cheng-Chih Chien. Autonomous IntelligentCruise Control. IEEE Trans. On Vehicular Technology,42(4):657-672, 1993.
Thomas Gustafsson; Jrgen Hansson. Dynamic on-demand
updating of data in real-time database systems.In Proceedings of ACM SAC 2004.
Gerhard Fohler; Flexibility in Statically Scheduling Real-TimeSystems. PhD Thesis, Technischen Universitat Wien Austria,
Apr. 1994.
L. Sha; R. Rajkumar; J. Lehoczky; K. Ramamritham. ModeChange Protocols forPriority-Driven Preemptive Scheduling.Technical Report: UM-CS-1989-060, University of
Massachusetts Amherst, MA, USA.
-
8/3/2019 Adaptive Cruise Control(1)
42/43
Video Clip
-
8/3/2019 Adaptive Cruise Control(1)
43/43
THANK YOU