Capstone Spring 2009
Preliminary Design Review
HAMSter
Cole Bendixen
Erik Larson
Electrical and Computer Engineering
Electrical Engineering
Erich Hanke
Quang Than
Electrical Engineering
Electrical Engineering
HAMSter Project Overview
Mobile Servo Powered
Cart

Stereo-Vision Obstacle
Detection

Autonomous Navigation

FPGA Hardware /
Software Control

IR Sensor “Failsafe”
Collision Avoidance

2
HAMSter Purpose
To create an autonomous platform that can be
used as a mounting point for various sensors and
monitors to test remote locations without human
control.
To advance hardware stereo-vision algorithms.
Cart Control Systems
GPS
Used for long range directional control
Polled GPS to periodically calculate a destination
vector
Hard coded destination

RF Transceivers
Beacon at destination point
Medium/Short range destination proximity sensor
Overrides GPS when active
Implementation based on time
Could be achieved through stereo vision

Stereo Vision
2-NTSC cameras input 30fps image streams
Image processing detects obstacles
Use of parallax to determine distance

IR
Provides short range obstacle detection
Highest sensor interrupt level – acts as failsafe to
avoid collision

30 cm
Sensor Interrupt Levels
Highest Priority
Polled
IR Proximity Sensor
GPS
Frame Ready To Processes
RF Beacon Detector
Computer Stereo-Vision
Lowest Priority
Code Flow Diagram
Software
Processing
Driver
Interface
Image
Processing
Wheel
Translation
Control
Hardware Filter
Servo Control
Board
Frame Grabber
Mobile Cart
Green = Hardware Implementation
Blue = Software Implementation
10
Yellow = Hardware/Software interface
Stereo Vision
Based upon the
phenomena of parallax,
where an observation at
two locations along a
baseline of a common
object appears to cause an
offset of the object. This
offset can be used to
determine relative distance
to the object.

Camera One
d1
Camera Two
d2
11
Point Spread Function
Simple PSF is applied to the image to
enhance edges.
Parameterized sweeper size and intensity.
Post convolution threshold filter applied.

HDL IMAGE CO-PROCESSOR
PPC HARDCORE PROCESSOR
PPC REG
INTERFACE
CONTROL
REGISTERS
IMAGE PROCESSING
DATA
BUILDER
CONV
IMAGE
SRAM
CONTROL
DATA
BREAKER
DVI CONTROLLER
DVI
SIGNAL
GENERATOR
PLL
RAM BLOCK
PowerPC 440
1,100 DMIPS

Up to 550MHz

Out of Order Processing

Branch Prediction

256MB DDR2 200MHz

I/O Control

Interrupt Enabled Inputs
IR
Sensors
Object Array stored in Block RAM

Polled Inputs
GPS
via COM0
Transceiver

Outputs
Servo
Control Board via COM1
Path Determination
Initial direction of destination is determined
using the GPS/transceiver data.
Objects are then realized in software.
Movement vector is determined based on
direction and relative position of objects.
IR sensors are then used to update path model
due to “invisible objects.”

GPS Direction Determination
Given our current position (in the grid coordinate
system) from the GPS, we calculate our
north/south and east/west displacement from the
destination position and use that to calculate a
destination direction vector.
We then calculate the deviation of our current
direction from the destination direction and rotate
the robot the required amount to correct this
difference.

Transceiver Direction Determination
The transceiver will determine a direction and
distance of the destination transceiver.
We then calculate the deviation of our current
direction from the destination direction and rotate
the robot the required amount to correct this
difference, just as with GPS.
Transceiver is necessary because the GPS is
only accurate to ~3m.

Object Realization
To realize objects we will create a matrix
representing the relative visible area in the
direction of the destination.
Object input in the form of a distance and
deflection will then be used to populate this matrix
with objects.

Movement Vector Determination
First we determine acceptable directions to travel
based on object positions.

We then evaluate a vector in each valid direction
space.

The length of movement vectors will place the robot
just past the nearest object.

We then compare the valid vectors and choose the one
that places the robot closest to the destination.

Instructions are then given to the servos to correct
direction and move forward the determined distance.

IR Recognition of 'Invisible' Objects
IR interrupts cause immediate motion halt.
Object is populated into matrix using IR sensor
determined direction and distance.
Path is then re-evaluated using updated object
matrix.
Motion continues.

Power Systems
Battery 1
Battery 2
FPGA
GPS
Opto-Isolator
Servo-Control Board
ADC
Servo Motors
Camera
IR Sensor
Goals

CDR
Robot
that will move to a specified GPS location.
Milestone1
Object
recognition hardware completed.
Milestone2
Robot
that will move to a specified GPS location avoiding
'visible' objects.
Expo
Robot
that will move to a destination object, via GPS and
transceiver, and avoid objects using video imaging and IR
sensors.
Budget
Item Name / Description
Unit
Price
Xilinx ML507 Virtex 5-FX XC5VFX70T-2FF1136C
$1,406.00
1
$1,406.00
DONATION
Agilent 1692A Logic Analyzer Mictor Probe
$1,150.00
1
$1,150.00
DONATION
Servo-Continuous Rotation HSR-8498HB HMI Robot Servo CNT
$79.99
8
$639.92
DONATION
Servo- Positional HSR-8498HB HMI Robot Servo
$59.99
2
$119.98
DONATION
NiMH Battery Pack: Powerizer 7.2V 4200mAh with 12AWG wire
$29.99
3
$89.97
$89.97
12 Channel Lassen IQ GPS Receiver with DGPS
$59.95
1
$59.95
$59.95
Antenna GPS Ultra-Compact Embedded HFL for Lassen IQ
$18.95
1
$18.95
$18.95
$9.95
6
$59.70
$59.70
CMOS Camera Module 640x480 --SEN-08773
$34.95
4
$139.80
$139.80
Linx Transceiver
$17.15
2
$34.30
$34.30
$2.08
2
$4.16
$4.16
Cart Frame Aluminum / wheels / screws
$80.00
1
$80.00
$80.00
Miscellaneous wires and parts
$60.00
1
$60.00
$60.00
PCB Layout
$33.00
3
$99.00
$99.00
$3,961.73
$645.83
Sharp GP2Y0A21YK0F Distance Sensor
Transceiver Antenna
Quantity
Total $
Sub-Total
After Donations
Schedule
Division Of Labor
Erich H.
Cole B.
Quang T.
Erik L.
Hardware
Cart Construction
x
Servos
x
x
Servo Controller
x
x
GPS
x
x
Video Processing
x
Object Recognition
x
x
x
x
IR Sensors
x
Transceiver
Power System
x
x
x
x
x
Software
Servo Control Code
x
GPS data processing
x
x
x
x
Pathing code
x
IR interrupt processing
x
Transceiver data processing
x
Documentation
Preliminary user's manual
x
Final Technical Documentation
x
x
x
x
User's Manual
x
x
x
x
RISKS
ADC interface to the FPGA – Loading images
into memory
Wheels operating at same speeds
Inaccurate calculation of cart speed to judge
distance traveled
Interfacing to the RF transceiver (signal
magnitude not direction)
Cart frame parasitic to GPS or RF signals
