Preliminary design review 30 january 2007
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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

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Preliminary design review 30 january 2007 l.jpg

Preliminary Design Review30 January 2007

Black Box Car System (BBCS)

ctrl + z:

Benjamin Baker, Lisa Furnish,

Chris Klepac, Benjamin Mauser,

Zachary Miers

Motivation l.jpg

  • 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 l.jpg
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 l.jpg

Performance Requirements

Block diagram main l.jpg
Block Diagram: Main



Black Box

User interface



Block diagram black box l.jpg
Block Diagram:Black Box




Main Processor













Implementation microcontroller l.jpg

  • 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 microcontroller8 l.jpg

  • 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 l.jpg

  • 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 video10 l.jpg

  • 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 video11 l.jpg

  • Disadvantages

    • Operating range isn’t ideal for a full automotive design (32-104 F °)

    • Minimum focus is 20 cm (~8 in)

Implementation video compression l.jpg
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 compression13 l.jpg
Implementation:Video Compression

Implementation video compression14 l.jpg
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 compression15 l.jpg
Implementation:Video Compression

  • Suppliers:

    • STMicroelectronics

    • Motorola

    • BeyondLogic

    • Digi-Key

Implementation memory l.jpg

  • 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 memory17 l.jpg

  • Slow large capacity memory for image data storage

    • Flash

      • Advantages

        • Robust

        • Cheap

      • Disadvantages

        • Slow access speed

      • Requirements

        • Compact Flash interface

Implementation communication l.jpg

  • Ideal Solution

    • I2C

    • USB 2.0 / 1.0

  • Fallback

    • Several I/O ports

Implementation accelerometer l.jpg

  • 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 accelerometer20 l.jpg

  • Accelerometer - LIS3LV02DQ

  • Advantages

    • 3 axes (crash from above?)

    • I2C/SPI output interfaces directly with Microcontroller

    • Factory calibrated with offsets loaded on startup

    • Variable sampling frequency

Implementation accelerometer21 l.jpg

  • Disadvantages

    • 2.5 V operation (increasing complexity with power supply)

    • Configurable to +/- 2 or 6 gs

    • Might trigger too easily

Implementation power l.jpg

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 power24 l.jpg

  • Supply Types Available:

    • Linear Voltage Regulators

    • Switching Converters

  • Ideal Setup:

    • 12V-1A, buck-boost

    • 5V-5A, buck

    • 3.3V-5A, buck

Implementation power25 l.jpg

  • 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 power26 l.jpg

  • The result for a 12V-1A Supply:

Implementation power27 l.jpg

  • Suppliers:

    • National Semiconductor

    • Texas Instruments

    • STMicroelectronics

    • Analog Devices

    • Many, many others

Implementation user interface l.jpg
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 l.jpg

  • 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 l.jpg
Contingency Plan

  • No video altogether

    • Instead, base system around inputs of speed, acceleration, braking, blinkers, lights, etc. directly from car

Extensions l.jpg

  • Other sensors

    • Speed

    • Lights, blinkers, brakes

    • GPS

  • Four video sources instead of one

  • 25fps, 30 second video loop

Testing l.jpg

  • 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 l.jpg
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