Transcript pptx - Purdue College of Engineering

Bryan McDonnel
Michael Mize
Ryan Taylor
Miles Whittaker
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Project overview
Project-specific success criteria
Block diagram
Component selection rationale
Packaging design
Schematic and theory of operation
PCB layout
Software design/development status
Project completion timeline
Questions / discussion
Robotic surveillance
vehicle
 Navigate to a target
 Avoid obstacles
 Survey target location
by recording audio
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Demonstrate an ability to:
 Display the current status of the robot on an
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external display.
Read from and write to a portable media device.
Make navigational decisions based on sensor,
GPS, and digital compass data.
Control the robot using steering and motor drive.
Capture and encode audio.
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Microcontroller: PIC24H
 Audio encoding
▪ G.711 needs 1 MIPS
▪ Capable of 40 MIPS
▪ Free libraries from Microchip
 Numerous peripherals
▪ 2 SPIs, 2 I2Cs, 2 UARTs
 Robust IDE
▪ MPLAB and development
board
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GPS Module: Skytraq
VENUS
 Accurate
▪ < 2.5m CEP
 Configurable update rate
▪ Up to 10 Hz
 Form factor
▪ Breakout board
▪ SMA connector
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Sensors: Ultrasonic
 Range
▪ 6” – 254” with 1”
resolution: (Vcc/256)/in
▪ Wide beam for general
obstacle detection
 Multiple interface
types
▪ Digital serial
▪ Analog voltage
▪ PWM
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RP5 Chassis
 Tank treads
 Small
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Motors
 6” per second nominal
Forward-mounted
microphone
 Forward and sidemounted ultrasonic
sensors
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Top View
Obtain data from SD card and note current
location
Validate SD card coordinates and initialize
systems
Start motors and travel to destination while
continuously sampling sensors
1.
2.
3.
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4.
5.
Navigate around objects using compass and sensors
At destination, sample microphone using ADC
Return to starting location
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Five Key Functional Blocks
 Object Detection
 Navigation
 Motor Control & Power
 Audio Capture
 Display and Storage
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Regulators designed to accept 8 – 11 V input
8.4V NiMH AA rechargeable battery pack
used as input
 2200 mAh
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Buck regulators used to produce 7.2V and
3.3V output
Motors draw 2.45 A each at stall
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Digital compass and GPS used
GPS runs at 10 Hz, Digital compass at 20 Hz
 Dead reckoning between GPS samples
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GPS sends NMEA* string over UART that will
be parsed to determine current location
 Algorithm described in software narrative
*National
Marine Electronics Association 0183 Standard
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Three ultrasonic sensors attached to chassis
 Front-, left-, and right-facing
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Sensors run in continuous scan mode at 20 Hz
Distance to object corresponds to 6.45 mV /
in [(Vcc/512)/in]
Sensors sampled by ADC using 12-bit
resolution
Low-Power
High-Power
3.3V Supply
7.2V Supply
High Current
(up to 5.1A)
75mil traces
Routed to shorten
current loops
(both regulators)
1
2
4
3
5
Routed to shorten
current loops
(both regulators)
4
1
2
3
5
Redundant caps
to prevent
brownout
during motor
load
changes
Additional
caps
H-Bridge Controllers
H-Bridge Controllers
High Current
(up to 5.1A)
75mil traces
Data & Power
Traces Separated
Data
Planned Thermal
Relief Plane
PIC24H Microcontroller
four decoupling caps
placed close to pins
Two caps under
board
to better utilize
space
Unconnected pins
configured as
outputs
and left floating
Analog
Digital
SD Card & LCD Headers
Mic & Audio Amplifier
Ultrasonic
Sensor
Inputs
Reset Circuit
GPS, Digital Compass,
& PICKIT Headers
Analog
Digital
Separation of
analog &
digital
interfaces
Analog
Digital
Analog and
switching
lines cross at
right angles
(2 cases)
Analog
Digital
Peripherals
connected
through
headers to
preserve board
area &
minimize
traces
(9 headers)
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Navigation
 Haversine Formula
▪ Used to calculate great-circle distances
 Only need three points
▪ Robot position: R( r ,  r )
▪ Target position: T ( t ,  t )
▪ North pole:
N ( n,  n)
 r  t 
2 
h  sin 
  sin   sin    sin  
 2 
2
2
c  2r arcsin
 h
  n r
   n  t
  r  t
r = Radius of Earth
  t  r m  
   t   r
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Week
Date
Task
Notes
9
12-Mar
Final Schematic/Layout
10
19-Mar
Software Development
11
26-Mar
PCB Assembly
12
2-Apr
PCB Assembly Complete
External Software Complete
13
9-Apr
Software Complete, Debug
Embedded Software Complete
14
16-Apr
Field Testing
15
23-Apr
Field Testing
16
30-Apr
Testing Complete, Demonstration
Spring Break