Design Review: RoboSiM Robotic Surveillance in Motion
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Transcript of Design Review: RoboSiM Robotic Surveillance in Motion
Design Review: RoboSiMRobotic Surveillance in Motion
Bryan McDonnelMichael MizeRyan TaylorMiles Whittaker
Outline
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
RoboSiM Overview
Robotic surveillance vehicle
Navigate to a target
Avoid obstacles Survey target
location by recording audio
Project Specific Success Criteria
Demonstrate an ability to: Display the current status of the robot on
an 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.
Block Diagram
Component Selection 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
Component Selection GPS Module:
Skytraq VENUS Accurate▪ < 2.5m CEP
Configurable update rate▪ Up to 10 Hz
Form factor▪ Breakout board▪ SMA connector
Component Selection 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
Packaging Design RP5 Chassis
Tank treads Small
Motors 6” per second
nominal Forward-mounted
microphone Forward and side-
mounted ultrasonic sensors
Packaging Design
Top View
Packaging Design
Theory of Operation
1. Obtain data from SD card and note current location
2. Validate SD card coordinates and initialize systems
3. Start motors and travel to destination while continuously sampling sensors
Navigate around objects using compass and sensors
4. At destination, sample microphone using ADC
5. Return to starting location
Theory of Operation/Schematics Five Key Functional Blocks
Object Detection Navigation Motor Control & Power Audio Capture Display and Storage
Block Diagram
Microcontroller
MicrocontrollerReset
PICKIT-2
Microcontroller
Audio
Power - Battery
Regulators designed to accept 8 – 11 V input
8.4V NiMH AA rechargeable battery pack used as input 2200 mAh
Buck regulators used to produce 7.2V and 3.3V output
Motors draw 2.45 A each at stall
Power
Motor Control
Navigation
Digital compass and GPS used GPS runs at 10 Hz, Digital compass
at 20 Hz Dead reckoning between GPS samples
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
Object Detection
Three ultrasonic sensors attached to chassis Front-, left-, and right-facing
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
Audio
PCB Layout: Overview
Low-Power
High-Power
PCB Layout: Power Supply
7.2V Supply
3.3V Supply
PCB Layout: Power Supply
75mil traces
High Current(up to 5.1A)
Routed to shorten current loops
(both regulators)
1
3
2 4 5
PCB Layout: Power Supply
Routed to shorten current loops
(both regulators)
1 32
4 5
PCB Layout: Power Supply
Redundant caps
to prevent brownout
during motor load
changes
Additional caps
PCB Layout: Power Supply
H-Bridge Controllers
PCB Layout: Motor Control
H-Bridge Controllers
75mil traces
High Current(up to 5.1A)
PCB Layout: Motor Control
Data & Power Traces
Separated
Data
Power
PCB Layout: Motor Control
Planned ThermalRelief Plane
PCB Layout: Motor Control
PIC24H Microcontroller
PCB Layout: Microcontroller
PCB Layout: Microcontroller
four decoupling capsplaced close to pins
PCB Layout: Microcontroller
Two caps under board
to better utilize space
PCB Layout: Microcontroller
Unconnected pins
configured as outputs
and left floating
PCB Layout: Peripherals
Mic & Audio Amplifier
Ultrasonic SensorInputs
Reset Circuit
SD Card & LCD Headers
GPS, Digital Compass, & PICKIT Headers
AnalogDigital
PCB Layout: Peripherals
Separation of
analog & digital
interfaces
AnalogDigital
PCB Layout: Peripherals
Analog and switching lines cross
at right
angles (2 cases)
AnalogDigital
PCB Layout: Peripherals
Peripherals connected
through headers to preserve
board area & minimize
traces(9 headers)
AnalogDigital
Software Design
Navigation Haversine Formula▪ Used to calculate great-circle distances
Only need three points▪ Robot position:▪ Target position:▪ North pole:
( , )r rR ( , )t tT ( , )n nN
Software Design
2 2sin sin sin sin2 2
r th
2 arcsinc r h
n r n t r t
r = Radius of Earth
Software Design
t r t r
m
Completion Timeline
Week Date Task Notes
9 12-Mar Final Schematic/Layout
10 19-Mar Software Development Spring Break
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-AprTesting Complete, Demonstration
Questions?