Transcript The Design of an Electronic Bicycle Monitor (EBM)

The Design of an Electronic Bicycle
Monitor (EBM)
Team P118:
Gary Berglund
Andrew Gardner
Emrys Maier
Ammar Mohammad
Background
Electric Bicycle
Components
•
•
•
•
Bicycle
Battery
Controller
Motor
2
Relevance
• Current interface
•
•
Battery
Speed
• Available systems
•
•
Commercial ‘off the shelf’
Phone apps
• Electric Bicycle Monitor (EBM)
•
•
•
Integration
Weight
Power efficient
• Used to track trips and monitor bicycle electronic
systems
3
Requirements
Requirement
Range
Accuracy
Speed
0 to 99.9 mph
0.05 mph
Odometer
0 to 99999.9 mi
0.05 mi
Trip distance
0 to 999.9 mi
0.05 mi
Trip max speed
0 to 99.9 mph
0.05 mph
Trip average speed
0 to 99.9 mph
0.05 mph
Trip peak current
0 to 50 A
100 mA
Time and date
100 years
1 min
GPS position
Earth
5m
Battery voltage
35 to 41 V
10 mV
Battery current
0 to 50 A
0.1 A
Battery charge used
20 Ah
0.1 Ah
Battery power delivered
? Wh
? Wh
Record GPS track data
0 to 2 GB
1 record per second
4
System Block Diagram
Caption for visual aid(s)
5
User Display
Hardware Milestone: 1
Software Milestone: 0
Requirements from top level:
• Display bicycle status
Requirements from other subsystems:
• None
Solution Method Decision Matrix
Two Row LCD
Graphics LCD
Make / Model
Fordata FDCC4002B
Innolux AT043TN24
Display type
Text
Graphics
Resolution
2 X 40 characters
480 x 272 x 24 bpp
Display area
6” X .65”
3.74” X 2.12”
Cost
$20.42
$32.99
Wiring connection
16 pins
40 pins
Bus needed
8 bit parallel data
24 bit parallel data
Touch interface
No
Yes
6
User Display (Hardware)
Hardware Milestone: 1
Software Milestone: 0
Solution being implemented: Graphics LCD
Needs from other subsystems:
• Power supply
• 3.3V @ 25mA (82.5mW) main logic
• 27.9V @ 22mA (613.8mW) back light
• Total max power: 696.3mW
• MCU
• Integrated graphics driver
• Four wire connection for touch sensing
7
User Display (Software)
Hardware Milestone: 1
Software Milestone: 0
Solution being implemented: Graphics LCD
Software status:
• Need software flow chart for GUI
8
Removable Memory
Hardware Milestone: 1
Software Milestone: 0
Requirements from top level:
• Logged Lat/Long for post processing
• Using Google Maps or similar program to view route
Requirements from other subsystems:
• None
Solution Method Decision Matrix
USB 1.1 drive
Secure digital card
Power consumption
110mW idle mode
2.5mW suspend mode
660µW idle mode
Connection
MiniUSB port
SD card connector
Cost
<$5
<$5
9
Removable Memory
Hardware Milestone: 1
Software Milestone: 0
Solution being implemented: Secure Digital
Needs from other subsystems:
• MCU
• SPI bus
• Power supply
• 3.3V @ 200µA (660µW) Standby
• 3.3V @ 100mA (330mW) Active
10
Removable Memory
Hardware Milestone: 1
Software Milestone: 0
Solution being implemented: Secure Digital
Software status:
• Need software flow chart for SD functions
11
Case
Hardware Milestone: 1
Software Milestone: N/A
Requirements from top level:
• Handlebar mounted
• Water resistant
Requirements from other subsystems:
• None
Solution Method Decision Matrix
DATEC-MOBIL S
A9073109
Garmin Nuvi
Cost
$35.09
$0.00*
Dimensions
5.98” X 3.26” X 1.31”
5.4” X 3.4” X .5”
4.3” LCD window
No, must be modify
Yes
12
Case (Hardware)
Hardware Milestone: 1
Software Milestone: N/A
Solution being implemented: Garmin Nuvi
Needs from other subsystems:
• All subsystems
• Physical constraint
• PCB Mounting hole coordinates match case
• Power supply
• Power button & USB connector coordinates match case
13
Case (Software)
Hardware Milestone: 1
Software Milestone: N/A
Solution being implemented: Garmin Nuvi
Software status:
• N/A
14
Battery Voltage Sensor
Hardware Milestone: 1
Software Milestone: 0
Solution being implemented: Offset Differential Amplifier
Requirements from top level:
• Range of 35 to 41V
Requirements from other subsystems:
• MCU
• Output 0 to 3.3V
• Linear relationship to battery
voltage
Needs from other subsystems:
• PSU
• 3.3V, Ground
• MCU
• ADC input
15
Battery Voltage Sensor
Hardware Milestone: 1
Software Milestone: 0
Solution Method Decision Matrix
Voltage Divider
Offset Differential
Amplifier
Range
0V to 41V
35V to 41V
Accuracy
40.04 mV
5.86 mV
Components
2
9
Approximate Cost
$2
$5
16
Battery Voltage Sensor
Hardware Milestone: 1
Software Milestone: 0
Solution being implemented: Housekeeping
Software status:
• A 10-bit ADC will be read every 1 ms and
saved into a variable for the display to use
17
Battery Current Sensor
Hardware Milestone: 1
Software Milestone: 0
Solution being implemented: Hall Effect Sensor
Requirements from top level:
• Range of 0A to 30A
Requirements from other subsystems:
• MCU
• Output 0V to 3.3V to ADC
• Linear relationship to measured
current
Needs from other subsystems:
• PSU
• 3.3V, Ground
• MCU
• ADC input
18
Battery Current Sensor
Hardware Milestone: 1
Software Milestone: 0
Solution Method Decision Matrix
Shunt Resistor (1 mΩ)
Hall Effect Sensor
ACS759
Range
0 A to 31.6 A
(power limited)
0 A to 50 A
Accuracy
30.86 mA
48.83 mA
Approximate Cost
$5
$10
Power Consumption
1 W (max)
123 mW
19
Battery Current Sensor
Hardware Milestone: 1
Software Milestone: 0
Solution being implemented: Housekeeping
Software status:
• A 10-bit ADC will be read every 1 ms and
saved into a variable for the display to use
20
Wheel Speed Sensor
Hardware Milestone: 1
Software Milestone: 0
Solution being implemented: Hall Effect Sensor
Requirements from top level:
• Range of 0 to 30 mph
Requirements from other subsystems:
• MCU
• Output pulse when magnet
passes the sensor
Needs from other subsystems:
• PSU
• 3.3V, Ground
• MCU
• Interrupt capable input
21
Wheel Speed Sensor
Hardware Milestone: 1
Software Milestone: 0
Solution Method Decision Matrix
Dirty operation
Hall Effect Sensor
IR Reflection Sensor
Yes
No
22
Wheel Speed Sensor
Hardware Milestone: 1
Software Milestone: 0
Solution being implemented: Interrupt
Software status:
• When a pulse is received, the wheel speed
timer value is recorded and the timer is
reset.
• The recorded timer value is used to
calculate the current velocity of the bike.
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Power Management System
Hardware Milestone: 0
Software Milestone: 0
Requirements:
• Interface with the existing bicycle battery voltage (35-40V typical)
• Provide stable, well-regulated power to each EBM subsystem
• Automatic shutdown at low voltage level (35V)
Additional Aspirations:
• Avoid wasting battery power with high efficiency design
• Minimize complexity
Objectives:
1.
2.
3.
4.
5.
6.
7.
Identify all voltage/current needs from subsystems
Identify subsystem I/O software requirements
Develop “Power Budget” and battery charge life
Research specific solutions and identify component candidates
Design and model hardware schematic
Alpha test under laboratory conditions
Integrate into EBM subsystems and measure performance
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Power Management System
Software Milestone: 0
Hardware Milestone: 0
Solution Method Decision Matrix
Voltage Divider
Linear Regulator
DC-DC Buck Converter
Efficiency
Horrible (scales)
Poor (~60-70%)
Excellent (~90%)
Regulation
Horrible
Excellent
Good
Part Count
Excellent
Excellent
Horrible
Design Complexity
Easy
Easy
Difficult
Biggest Drawback
No regulation
Inefficiency
Switching Noise
• Specific power supply parts have not yet been selected pending
other subsystem part selection
25
Power Management System
Software Milestone: 0
Hardware Milestone: 0
Solution being implemented: A mix of DC-DC Buck Converters and LDO Linear Regulators
Requirements from top level:
Needs from other subsystems:
• Step down 35-40V main battery voltage to • MCU: Low voltage shutdown command
first subsystem voltage level
• Subsystem power budget numbers
Requirements from other subsystems, “Power Budget”:
MCU (PIC)
Screen
Screen Backlight
GPS module
Voltage Sensor
Current Sensor
Wheel Speed Sensor
Internal Memory
External Memory Module
V_nom
V
3.3
3.3
27.9
3.3
-
I_min I_nom I_max P_min
mA
mA
mA
mW
100
17
25
20
22
558
12
20
100
39.6
-
P_nom
mW
330
56.1
66
-
P_max
mW
82.5
613.8
330
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GPS
Hardware Milestone: 1
Software Milestone: 0
Solution Method Decision Matrix
A2200-A
EM-506
TTFF
35s
15-35s
Antenna
External
Internal
Number of channel
48
48
Power consumption
135.3mW
+ 40 mW
170mW
Price
$13.60
+ $11.95 for antenna
$39.99
27
GPS
Hardware Milestone: 1
Software Milestone: 0
Solution being implemented:
• Getting position and time information
Requirements from top level:
• Record latitude, longitude, and time
• Save them to the SD card through the
MCU
• Use the saved data to show the path
of the trip
Requirements from other subsystems:
• None
Needs from other subsystems:
• Power System:
• 5 V @ 34 mA (170 mW)
• MCU:
• I2C bus to send the data every one
second
• External memory:
• Place to save the data
28
Microcontroller
Hardware Milestone: 1
Software Milestone: 0
Solution Method Decision Matrix
PIC24FJ256DA206
PIC24FJ256DA210
Pins
64
100
ADC
16
24
SPI, I2C
3
3
Program Memory
128/256
128/256
EPMP
NO
Yes
Power consumption
2.6 mW
2.6 mW
Price
$7.20
$8.14
29
Microcontroller
Hardware Milestone: 1
Software Milestone: 0
Solution being implemented: Microcontroller
Requirements from top level:
• Analog to digital Converter (2
channel)
• SPI bus for SD card
• EPMP bus for Graphical LCD
• Pulse counter for speed
Requirements from other subsystems:
• Current sensor:
• Analog reading of battery current
• Voltage sensor:
• Analog reading of battery voltage
• GPS:
• Position and time information
• LCD screen:
• X and Y axis of the touched place
Needs from other subsystems:
• Power System:
• 3.3V @ 800µA (2.6mW) running
mode
• 3.3V @ 22µA (72µW) Idle or sleep
mode
30
Testing
Will be divided into three aspects:
• Power system, voltage and current sensor:
• Power supply along with multimeter will be used
Measuring the voltage and current to check requirement and accuracy
• Wheels speed sensor:
• Regular bike will be used
Checking number of pulses per revolution
• GPS, LCD, and MCU:
• No external component needed
Checking the results using software application
GPS using google map
LCD and MCU using the programming software (MPLAB X?)
Heartbeat LED testing will be used after adding any component to the design
31
Project Management
Meeting:
• Bi-weekly with Dr. Gibbs
• Weekly with group members
Documentation
• Shared folder to organized documents
• Documents naming convention for convenient access
Tasks:
•
Divided into multiply subsystem
•
Each subsystem include: choosing components, designing circuit schematics, PCB,
and programming
•
Overlapping responsibility to ensure general knowledge about other subsystem
32
Project Timeline (Preliminary)
“Wrap Up” Plan (very early)
Tasks
Complete block diagram
Update tasks/wrap up plan
Select slideshow format/develop slides for Preliminary_v1
Merge Slideshow
A3: SDP Plan - Prelim - v1 due by 12 noon
Weigh component options (decide uC, V&I sensor, PSU parts, display, memory, GPS)
SDPPv1 Plan, and revised powerpoint slides due by 12 noon
SDPPv2 Plan due by unknown
Power Supply
Identify voltage and current requirements
Select controller
Program interface to MCU
Alpha Testing
Display
Identify communication standard
Power requirements
Schematic interface
Alpha Testing
External Sensors
Voltage Sensor
7-Apr 9-Apr 9-Apr 14-Apr 14-Apr 16-Apr
GRB
ATG
All
GRB
ATG
ATG
ATG
ATG
all
all
all
ATG
ATG
ATG
GRB
GRB
GRB
GRB
GRB
GRB
EEM EEM
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Weekly Goals
Powerpoint Slide Assignments
Topic
Intro
Design Overview
Project Management
Budget
Conclusion
#
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Slide
Title Slide
Introduction / relevance / background
Requirements / specifications (Overall)
System Block Diagram
Mechanics
Display / Touch input
Removable storage
Battery voltage sensor
Battery current sensor
Wheel position sensor
PSU requirements
PSU options
PSU choice
GPS
MCU / internal memory
Test methods
Management Plan
Timeline
Weekly Goals
Budget
Conclusion
Est. Time (mins)
0
1
1
2
1
1
1
0.5
0.5
0.5
0.5
0.5
0.5
1
1
1
1
0.5
0.5
0.5
0.5
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Student
Emrys
Emrys
Emrys
Richard
Richard
Richard
Richard
Emrys
Emrys
Emrys
Andy
Andy
Andy
Ammar
Ammar
Ammar
Ammar
Andy
Andy
Andy
Andy
34
Budget
• Currently unknown, but relevant at every
step in the design process
• Safely assumed at less than $1000 in
components
• No upper limit specified by sponsor
• Will factor into component selection
35
Conclusion/Questions
36