Preliminary Design Review 30 January 2007 Black Box Car System (BBCS) ctrl + z: Benjamin Baker, Lisa Furnish, Chris Klepac, Benjamin Mauser, Zachary Miers

Motivation

 Car accidents   Provide proof of who was at fault Provide information about force of crash  Other traffic incidents  Capture information about what really occurred if ticketed for speeding, following, etc.

Concept of Operations: Goals     Provide visual information of car’s surroundings for period of time before accident Use accelerometer to determine if accident has occurred   If programmed acceleration level occurs, BBCS knows a crash has occurred Force reading will be saved in conjunction with visual data Removable storage  Crash video can be viewed on home computer Autonomous   In event of accident, data automatically saved Powered by vehicle

CONOPS: Requirements Performance Requirements Video requirements Data storage User interface - Camera outside of vehicle 5-20 seconds video recording loop 1-5 frames per second Video loop written to RAM In event of accident, data from each camera written to Flash memory Ability to view video of crash on home computer LED indicator if data has been stored Ability to manually store/erase data

Camera User interface

Block Diagram: Main

Accelerometer Black Box Reset Storage

Reset IC Accelerometer Camera Power

Block Diagram: Black Box

Main Processor IC LED or LCD Camera IC RAM Flash Storage Computer

Implementation:

     Microcontroller Flash-based, 16/32-bit    ARM Microchip PIC MSP430 Re-programmable On-board ADC, UART, I²C, Timer/counter Interface to sensors, Flash data log USB 1.0/2.0 capable

Implementation: Microcontroller   One main processor to act as a central processor to control all coprocessors  Video processors, memory, accelerometer, etc.

Our design will use one processor for each camera module  This will allow us to more easily implement several video sources if extended

Implementation: Video    We’re looking to use either a CCD or CMOS camera as our video sensor.

Ideally we would like to use a camera with USB output and onboard compression.

Using a webcam oriented device, we’re hoping to eliminate any need to program USB drivers. With a corresponding USB microcontroller, this might be possible.

Implementation: Video   Camera – STVS6522 Advantages       Only needs a 5V supply Large range on input voltage (4.1-5.6) Adjustable Frame Rate Black and White or Color images USB 2.0 compliant Field of depth is infinite with a fixed focus

Implementation: Video  Disadvantages   Operating range isn’t ideal for a full automotive design (32-104 F ° ) Minimum focus is 20 cm (~8 in)

Implementation:

Video Compression We assume we are getting raw video from an un-compressed CMOS camera Estimated needs:  Moving JPEG conversion  Real time video compression (at least fast enough to convert the first frame by the time the second frame is taken)

Implementation: Video Compression Raw CCD Data Buffered Storage IC for Video Processing I2C or USB to main IC Storage for video processing

Implementation: Video Compression   Video Conversion Types  Digital Camera Coprocessor  IC Programmed to do video compression Ideal Setup:    CMOS Digital Camera coprocessor for digital still and web cameras Real time video conversion with 50:1 compression ratio I2C or USB data output

Implementation: Video Compression  Suppliers:     STMicroelectronics Motorola BeyondLogic Digi-Key

Implementation: Memory  Fast re-writeable memory to buffer image data.

 SRAM    Advantages   Programming simplicity Control simplicity Disadvantages   Expensive Limited size Requirements   Capable of handling 5 frames/sec video input Low power consumption

Implementation: Memory  Slow large capacity memory for image data storage  Flash  Advantages   Robust Cheap   Disadvantages  Slow access speed Requirements  Compact Flash interface

Implementation: Communication  Ideal Solution  I2C  USB 2.0 / 1.0

 Fallback  Several I/O ports

Implementation: Accelerometer    We’re looking at using a MEMS based accelerometer to detect a crash.

The accelerometer is the central trigger for the system.

The entire black box is in a looping state until the accelerometer interrupts and sets the system into its crash procedure.

Implementation: Accelerometer   Accelerometer - LIS3LV02DQ Advantages     3 axes (crash from above?) I 2 C/SPI output interfaces directly with Microcontroller Factory calibrated with offsets loaded on startup Variable sampling frequency

Implementation: Accelerometer  Disadvantages    2.5 V operation (increasing complexity with power supply) Configurable to +/- 2 or 6 gs Might trigger too easily

Implementation: Power We assume we are getting power from a car battery that varies from 8-16V.  Estimated needs:  One 12V-1A converter for cameras and sensors  One 5V-5A and a 3.3V-5A converter for processors, memory, and other circuitry

Implementation: Power Car Battery(8V-16V) 12V-1A Converter 5V-5A Converter 3.3V-5A Converter Cameras, Sensors, Etc.

Processors, Memory, Other Circuitry 3.3V Processors and Circuitry

Implementation: Power   Supply Types Available:   Linear Voltage Regulators Switching Converters Ideal Setup:    12V-1A, buck-boost 5V-5A, buck 3.3V-5A, buck

Implementation: Power  Designing the Supply   Hard way: Design it by hand, go through plenty of equations, and have a less efficient converter than one you can buy for cheap.

Easy way: Go to National Semiconductor, go to the Power Webench, type in your input voltage and your output voltage and current and it designs it for you.

 Implementation: Power The result for a 12V-1A Supply:

Implementation: Power  Suppliers:      National Semiconductor Texas Instruments STMicroelectronics Analog Devices Many, many others

Implementation: User Interface  Ideal Solution  Plug into computer and all video sources show up and start to run  On-station displays (LCD or LED on box)  Fallback  Data display in Windows Application (Excel, Visual Basic, etc.)  Data dump to HyperTerminal convert video using program then view video sources

Implementation: Enclosure   Ideal Solution  Custom Plexiglas enclosure    Weatherproof Transparent (for Expo) Strong and Shock resistant (protect equipment in the event of collision) Fallback Solution    Generic electronics enclosure Locking metal box Some foam to lessen shock

Contingency Plan

 No video altogether  Instead, base system around inputs of speed, acceleration, braking, blinkers, lights, etc. directly from car

Extensions

   Other sensors    Speed Lights, blinkers, brakes GPS Four video sources instead of one 25fps, 30 second video loop

Testing

 Skateboard with system attached to it     Push skateboard into wall (collision) Kick skateboard (side collision) Drop basketball on top of car (falling rocks) Hold bacon behind car (Cop with false ticket)

Division of Labor

         Video: Chris Klepac Compression: Zach Miers Power: Ben Baker Accelerometer: Chris Klepac Microcontroller and misc. sensors: Lisa Furnish & Zach Miers Enclosure: Ben Mauser User Interface: Ben Mauser Documentation: All PCB Design: Chris Klepac & Ben Mauser

Schedule

Questions