Transcript PACE LITES PRESENTATION

PACE LITES
PRESENTATION
Advisor: Professor Sahakian
Andrew Dai
Lenore Kaplan
Benjamin Mattson
Nikhil Sethi
1
PACE global vehicle


PACE is a global
collaborative project
aimed at designing a new
vehicle for the emerging
market
Universities across the
world are assigned
different sub-systems
2
Northwestern is designing the
electrical sub-system
Goals
 Safety
 Minimize
weight
 Efficiency
Front and Rear
End Collision
Avoidance
Wireless
Communication
Network
Modular
Multiplexing
System
Provides
additional
safety features
Communicates
relevant
information
Minimizes
weight and
increases
efficiency
Sonar
technology
Zigbee
Standard
Radios
Microcontrollers
MOSFETS
3
Sonar design utilizes transducers
located inside the bumpers



Powerful range finder
Drivers receive alerts of
objects quickly approaching
Onboard processing
An overhead view of the wave propagations from the
front and rear of the vehicle.
Each transducer will be
housed within the bumper,
keeping a smooth surface
across bumper face.
4
Design detects objects at short and
long ranges
Specs:
 3 Ultrasonic transducers
 Center transducer short, wide
range
 Outside transducers long,
narrow range
 Senscomp 6500 ranging
module board
 Basic stamp microcontroller
An overhead view of the range covered
by each transducer. Short range is
emphasized with parking, long range is
focused on collision avoidance.
5
The sonar works in tandem with the
microcontroller in a multi-step process
The sonar system is controlled by the microcontroller,
which is integrated into the vehicle’s engine control unit
(shown in yellow).
The microcontroller runs the ranging module, which supplies
source voltage to the transducers.
Step 1: Begin the sequence
- Microcontroller (MC)
tells sonar receiver
board to send 400 volt
pulse to relay circuits
- MC connects first relay
circuit
-MC starts timer
The microcontroller readout (highlighted in yellow) allows the driver to monitor the
sequence from beginning to end.
Step 2: Transducer emits wave pulses
- 400v arrives at transducer
- Creates current in metal casing
- Causes diaphragm to flex
- Flex creates ultrasonic wave
Step 3: Reflected waves indicate object is
present
-Wave encounters object
-Small portion reflects
-Reflection returns to
transducer, causes slight flex
-Flex induces voltage
Step 4: The microcontroller receives
detection signal and ends sequence
-Return pulse travels
down original line to
RB
-RB tells MC an object
has reflected wave
-MC stops timer,
records time
Step 5: The microcontroller runs code to
decipher time to collision
The prototype functions both attached
and independent of the vehicle
Intervehicle communication allows
increased awareness between vehicles


Zigbee wireless system allows
inter-car communication
System can warn others of
weather, incoming traffic,
construction
Car
Computer
LCD Display
XBee
Module
XBee
Module
Car
Computer
LCD Display
13
The Zigbee standard offers benefits in
range, and power


Alternate technologies
 Wifi – 300ft range
 Bluetooth – 3ft range
Specs
 Digi Xbee PRO modules
 <$25
 <1W
 5000ft range
14
Wireless prototype works on a
modular basis

Components
 XBee modules
 ARM processor
 Blackbox input
 Host machine
15
Communicating between Xbees and
providing readable output
Converting output from
sonar for transmission
Describing Zones to user


Zone
Number
1
Encoded
Output
1000
Range
(in)
0”-12”
2
1100
12”-20”
3
1110
36”-120”
4
1111
120”+
16
Testing the range and efficiency of the
wireless system



Tested RSSI (dBm)
Transmitted 64bits
Was able to operate at a range
of 1 foot to 120 feet.
1
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
90 105 110 115 120
0
-10
-20
-30
-40
-50
-60
-70
-80
-52 -50
-56
-62
-68
-68
-73 -75
-79
-75 -74
-79
-90
-100
-84
-80
-84
-85 -85 -87
-88
-90 -88
RSSI vs Distance
17
Prototyping enabled us to test for
feasibility, range, robustness
Goals
 Feasibility
 Testing
•
•
•
•
Cost
Range
Power
Interference
18
Our prototype showcases a combined
sonar and wireless system
Coaxial
Cables
12V Battery
5V
Regulator
Digi Xbee Module
BASIC stamp
microcontroller
SensComp 6500
Ranging Module
BJT
Switches
Digi Xbee Module
Gateway
Board
Laptop
400V
SS
Relays
Environmental
Grade Sonar
Transducers
19
The prototype proves feasibility
20
Multiplexing Overview
21
Front of car
Back of car
LEDs
Input controls
Locks
Sensor
Microcontroller
(input)
Microcontroller
(output)
LEDs
22
Multiplexing allows large minimization
of vehicle’s wires



MOSFETs
 Handles lots of current (60 A)
 No moving parts
Wire Gauge
 Less power loss for 8 gauge
 Easier assembly
PIC microcontroller
 Programmable communication
 40 I/O
23
Multiplexing connects all components
in a modular fashion
Multiplexing will:
 Lower



wire cost
power loss
Connect all electrical
components in PACE car
24
Multiplexing Reduces Installation
Time and Cost


Less wires mean less
assembly time
Boothroyd Dewhurst
DFMA provides methods
of predicting assembly
time
Example

Assembling Wires in wire
loom
Time Saved by Shortening
Wires (per wire)
25
20
Seconds

15
10
5
0
With Multiplexing
Traditional Wiring Harness
t n = 6.4 + 3.8N w + (.5 + .4Nw )L w
25
Parts for the virtual build
26
Next Steps



Design sonar and wireless circuit boards
specifically for PACE design
Create user interface
Multiplexing



Program so that components are plug and play
Universal connections
Testing

Sonar Arrays
27
Questions and Comments
28