1
Autonomous Parallel ParkingAlex Braun & Sergey Katsev
2
Overview
• Objectives• User Interface• Algorithms• Utilized Hardware• Hardware Design• Current Status
3
Objectives/Performance Specs
•Follow a reflective track•Receive user commands over a wireless interface•Leave track and parallel park•Leave parking space and reacquire track
•Minimum parking space 2 car lengths•Travel speed .5 – 1 foot per second•Capable of following any turns greater than vehicle turning radius
4
Implementation•Vehicle:
–1:12 Scale model of a Lincoln Navigator–Chassis and drive motor from original RC car–Steering implemented with Futaba S3003 Servo motor
•Power–9.6V rechargeable NiCad battery pack–Voltage regulators used to provide 5V power to electronics and isolate power planes
5
User Interface
•Remote control used to issue user commands•Vehicle responds with actions and LED status lights•Remote uses 9V battery
7
User Interface• Status lights will indicate:
– Current operating mode:•Manual•Automatic
– Looking for track– Following track– Looking for Space– Parking– Parked
•Error
– Waiting for user parking override•“Turn Signal”
8
Sensor Layout•IR arrows show direction of beam
•Wireless interface used for remote control user commands (more later)
C1
C3
FRONT OF VEHICLE
REAR OF VEHICLE
T1 T2 T3
T4 T5
C2
C4
S1
Wireless
Analog IRsensor
Digital IRSensor
IR TrackSensor
RF Wireless
9
Algorithms – Track Following
•Front sensors used to determine when to turn•Two turning angles•Rear sensors used when acquiring the track and as a backup if all front sensors are lost
10
Algorithms – Track FollowingAll five track sensors are on track.
Moveforward
Scan FrontSensors
Turn 10 degreesaway from lost
sensor
Turn 20 degreesaway from lost
sensor
Two on track
Oneon track
Noneon track
Reverse, setvehicle to low
speed
Scan RearSensors
At least one on track
Noneon track
ERROR
Set vehicle tohigh speed
All threeon track
11
Algorithms – Parking •Minimum parking spot size 2 car lengths•Algorithm iterates if can not fit in spot in one motion
B4
B2
FRONT
BACK
B4
B2FR O N T
B A C K
12
Begin ParkingAlgorithm
Turn wheels max.towards curb
Reverse
Rear curb?
Stop, turn wheelsmax. away from
curb
No
Reverse
Check RearMiddle Vehicle
Collision
Monitor RearCurb
Detection
No
Check FrontCurb
Detection
No
No
ParkedSuccessfully
Reverse at halfspeed
Yes
Curb equaldistances?
Yes
No
Yes
Algorithms – Parking(Basic Algorithm)
13
Algorithms – Parking Space Exit
Reverse
Detect RearObstacle
Has maximumbackup distancebeen reached?
No
No
Stop, Turnwheels away
from curb.
Yes
Yes
PullForward
Detect FrontCorner
Collision
Detect Track (FrontTrack Sensor Return)
No
No
Successfully ExitedParking Space
Yes
Turn WheelsTowards Curb
Yes
DetectCurb
Yes
Back Up
No
Begin ExitingParking Space
14
Utilized Hardware
•Processing:–Onboard HCS12
•Sensors–Track Sensors
•Fairchild QRE00034 Infrared Reflective Sensor•Used with a comparator to provided digital input to the HCS12
15
Utilized Hardware
– Speed Sensor•Fairchild QRE00034 Infrared Reflective
Sensor•Used with a comparator and a shaft
encoder to produce a timer interrupt every quarter revolution of the rear wheels
18
Utilized Hardware
•Collision Detection–Sharp GP2D120 Infrared Distance Sensors–Analog value fed to HCS12 through ADC
•Parking Space Detection
–Sharp GP2D150A Infrared Distance Sensor–Provides digital detection at ~15cm
19
Component Estimated Maximum Power Consumption
DC Motor 2.7W
Servo Motor 2W
Curb and Vehicle Collision Sensors 0.30W x 4 = 1.2W
Parking Space Sensor 0.30W
Track Sensors .2W x 5 = 1W
Vehicle Speed Sensor .2W
Wireless Receiver 164mW
HC-12 1W
Misc ICs and LEDs ~ .2W x 10 = 2W
TOTAL 10.6W
Power Consumption
20
Hardware
•Ribbon cable used to connect HC12 to PCBs•PCBs stacked to maximize available board space•Final product will (hopefully) fit inside original vehicle cover
21
Hardware – Drive Electronics
•Motor draws 1.6A max.•Texas Instruments SN754410 Quad Half H-Bridge used.•1A sustained load capacity, 2A peak load (per half H-bridge)•Two H-bridges used in parallel H-bridge functional schematic
23
Hardware – Wireless Interface
•Ming 4-bit Tx/Rx•300MHz AM•Uses Holtek Encoder and Decoder chips•Remote contains 74LS922 Key matrix decoder with debounce protection
25
Hardware – Sensor Input Conditioning
•Two quad binary comparator circuits•Threshold set at 4.0V, established experimentally•Separate voltage regulator•Will contain HC12 inputs for all digital sensors
27
Costs
Component Retail Price Actual Price
Vehicle Assembly $50 $50
Track Sensors (5 total) $3.25 $0
Collision Detection (4 total) $48.80 $48.80
Parking Space Detection $13.23 $13.23
Wireless Kit $30.00 $30.00
Servomotor $9.80 $0
H-Bridge $1.35 $0
HCS12 $160 $0
Misc $70 $50
TOTAL $386.03 $192.03
28
Current Vehicle Status
8/17/2004 8/24/2004 8/31/2004 9/7/2004 9/14/2004 9/21/2004 9/28/2004 10/5/2004 10/12/2004 10/19/2004 10/26/2004
Major system design - AB SK
Determine and acquire components - AB SK
Build vehicle assembly - SK
Interface track sensors w ith microcontroller - AB SK
Interfacing microcontroller w ith vehicle - AB SK
Track tracking - AB
Speed controller - AB SK
Track re-acquisition - AB SK
Parking space detection - AB
Interface collision sensors w ith microcontroller - AB SK
Parking algorithm - AB
User Interface - SK
Testing/Debugging - AB SK
Project Write-up - AB SK
Project Website - AB SK
Completed Remaining
29
Current Vehicle Status
Front Track Sensors
Comparators HCS12 H-Bridge
Receiver
Rear track sensors
DC Motor
Steering Servo
30
Difficulties• Speed Controller – “Pseudo” Shaft
Encoder • Heat Dissipation – May have to
place a second voltage regulator in parallel for drive electronics
• HCS12 operates differently in DBUG12 mode than it does in LoadEE mode, so tracing code is practically impossible
31
Testing Methodology• Unit testing of both software and
hardware units• Unit integration and system-wide
testing• Extensive operation to ensure
proper burn-in
• For code: “Desk Checks” by the person who didn’t write the code
32
Track Following Demo
33
Questions?
• Thank you!