1 Autonomous Parallel Parking Alex 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

6 Remote Design

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)

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 Following

11 Algorithms – Parking Minimum parking spot size 2 car lengths Algorithm iterates if can not fit in spot in one motion

12 Algorithms – Parking (Basic Algorithm)

13 Algorithms – Parking Space Exit

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

16 Sensor Experiment Data (1)  IR Sensor L Figure : Experiment 1  : Angle of incidence L: Sensing Distance Test Surface

17 Sensor Experiment Data (2)  IR Sensor L Figure : Experiment 2  : Max viewing angle L: Sensing Distance

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 ComponentEstimated Maximum Power Consumption DC Motor2.7W Servo Motor2W Curb and Vehicle Collision Sensors0.30W x 4 = 1.2W Parking Space Sensor0.30W Track Sensors.2W x 5 = 1W Vehicle Speed Sensor.2W Wireless Receiver164mW HC-121W Misc ICs and LEDs~.2W x 10 = 2W TOTAL10.6W 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 SN 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

22 Drive Electronics Design

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

24 Receiver Design

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

26 Sensor Conditioning Design

27 Costs ComponentRetail PriceActual Price Vehicle Assembly$50 Track Sensors (5 total)$3.25$0 Collision Detection (4 total)$48.80 Parking Space Detection$13.23 Wireless Kit$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

29 Current Vehicle Status Front Track Sensors ComparatorsHCS12H-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!