Transcript Team3phase2(march31)

College of Engineering and Applied Science
Capstone Design Project:
MOUNTAIN BIKE ANTI-LOCK BRAKE SYSTEM
Electrical Engineering 595
Spring Semester 2004
Design Group #3
Design Group #3 Team Members
Mark Adamak
BSEE and BSME
Nick Bertrand
BSEE
Eric Graves
BSEE and CS minor
Presentation Mgr
Ph: (262) 548-0331
[email protected]
Project Archiver
Ph: (414) 727-4912
[email protected]
Fearless Leader
Ph: (414)232-0792;
[email protected]
Design Group #3 Team Members (Cont.)
David Mapes
BSEE
Richard Roh
BSEE and BioChem
Researcher
Ph: (414) 324-5816
[email protected]
Report Manager
Ph: (262) 853-1475;
[email protected]
3
The Mountain Bike ABS Control System Description
•
Antilock brake system for a dual rotor, hydraulic disc brake assembly
•
The ABS system will take actions to avoid the locking of brakes during rapid
deceleration and low friction conditions
•
Enables steering control in an aggressive braking situation
•
Rider will have the ability to manually over-ride the ABS action
•
Small display will inform the rider of the status of the system
4
Product Level Standard Requirements
Market
– Estimated Annual Volume:
5000 units
– Estimated Market Size:
100 %
– Minimum List Price:
$250.00
– Maximum Product Cost:
$150.00 need to
– Maximum Prototype Cost:
$500.00 need to calculate
– Market Demography:
18-32 male and female
– Market Competitors:
Avid, Shamano
– Market Industry:
Competition/Recreational
sports equipment
5
Product Level Standard Requirements
Power
– Primary DC; 12V DC sealed cell lead acid battery
• Output Voltage Range:
10-14 VDC
• Instantaneous Maximum Available Power:
50 Watts
• Charge Capacity:
4.0 A-hr
– Secondary AC; 12V battery charger
• Primary Input Voltage Range:
115-125 VAC
• Output Voltage To Battery:
14 VDC
• Output Current To Battery:
0.5 A
• Output Power:
15 Watts
6
Product Level Standard Requirements
Mechanical
– Maximum Product Volume:
0.1 cubic meters
– Maximum Product Mass:
5.0 kg
– Number of Printed Circuit Boards:
4
– Total Printed Circuit Board Area:
400 square centimeters
– Impact Shock Force:
4 G’s
– Moisture Resistance:
Weather Resistant
– Maximum Total Part Count:
250 change this
– Unique Parts:
200
– Maximum Parts and Material Costs:
$100.00
– Maximum Test and Assembly Cost:
$50.00
7
Product Level Standard Requirements
Environmental
– Operating Temperature Range:
12 – 49 C
– Operating Humidity Range:
0 – 100%
– Storage Temperature Range:
0 – 50 C
– Storage Humidity Range:
0 – 80%
– Storage Duration:
2 years
– Charging Battery Temperature Range:
0 – 60 C
8
Product Level Standard Requirements
Life Cycle
– Estimated Product Lifetime:
5 years
– Service Strategy:
Factory Repair
– Product Life MTBF:
2 years
– Full Warranty Period:
90 days
– Product Disposal:
Recycle
9
Product Level Performance Requirements
Product Goal
– Improved Breaking Ability
• Increase stopping performance by decreasing the straight line stopping
distance of an average sized rider (140-200 lbs) by 10% or more
– Internal Design Tolerances
• Max breaking fluid pressure of 800 psi
• Nominal breaking fluid pressure of 500 psi
10
Product Level Performance Requirements
User Control
– Power switch
• User turns power onto the unit when use is desired
– ABS Override
• User has control over ABS action on both front and rear wheels,
user can disable ABS action if it is desired that either wheels lock
• A switch for both front and rear wheels will Display informs rider of
• Applied Power
• Battery Charge
• ABS Activity
11
Product Level Performance Requirements
System Monitoring
– Wheel Rotation
• System monitors wheel rotation to determine if wheels are locked or not
– Break Activity
• System monitors whether the breaks are being applied or not
12
Block Ownership Key
Eric Graves
Power Supply
Richard Roh
Block Connection Key
David Mapes
120 VAC
Nick Bertrand
+12 VDC
Mark Adamak
+5 VDC
Note: Colored outline
represents person who
will assist primary owner
of block
Data
System
Sensors
Microcontroller
ABS Actuator
User Control
And
Feed Back
13
Block Ownership Key
Eric Graves
Power Supply
Richard Roh
Block Connection Key
David Mapes
120 VAC
Nick Bertrand
+12 VDC
Mark Adamak
+5 VDC
Note: Colored outline
represents person who
will assist primary owner
of block
Data
System
Sensors
Microcontroller
ABS Actuator
User Control
And
Feed Back
14
Block Level Standard Requirements
Power

Voltage Supply:
• Nominal Vcc:
Vcc = 5.0VDC
• Max Vcc:
Vcc = 6.0VDC
• Min Vcc:
Vcc = 4.75VDC
• Steady State Voltage Supply Ripple: Δvcc ≤ 250mV

Max Current Draw:
Icc = 30mA

Max Power Dissipation:
P = 0.5W
15
Block Level Standard Requirements
Mechanical
•
Microcontroller Package:
40 pin DIP
•
Location:
Resides in main printed circuit board
•
I/O:
At least 20 I/O pins
•
Weight:
0.05 kg
•
Maximum Total Part Count:
10
•
Unique Parts:
5
•
Maximum Parts and Material Costs:
$100
•
Maximum Test And Assembly Cost:
$2
16
Block Level Performance Requirements
Microcontroller
– Control
• Program monitors motion of wheel and determines if they become locked
• Determines if ABS Activity is desired by user
• Sends ABS activate signal to ABS actuation circuit
17
Selected Microcontroller
Atmel AVR ATMega16-16PC 8-bit RISC microcontroller
General Description
•
16K x 8 program memory
•
1K x 8 RAM
•
8 MHz max internal clock
•
32 I/O pins – Four 8-bit ports
•
40 pin DIP package
18
Selected Microcontroller
Atmel AVR ATMega16-16PC 8-bit RISC microcontroller
Valued Features
•
16 bit Timer/Counter
•
Input Capture Register that can capture the
Timer/Counter value at a given external (edge
triggered) event on the Input Capture Pin (ICP1)
•
The Input Capture unit includes a digital filtering
unit (Noise Canceller) for reducing the chance of
capturing noise spikes.
19
Hardware Development
Chip programming, prototyping and
debugging of the controller was done on
Atmel’s AVR STK 500 development
board
Simulate I/O via 8 push buttons and 8
LED on the development board
Connect actual I/O via pin-header
connectors
20
Software Development
I chose to use a C compiler called WinAVR for the software
development. It is an open source compiler form
www.avrfreaks.net.
This compiler was chosen because of it cost (free) and because of
it’s simplicity and diversity of use.
21
22
Digital Signal:
Sensors
2 Bits, one for each
enable/disable user
control switch
Digital signal:
Wheel rotation data,
sends 32 pulses per
revolution
4 bits
2 bits
User
Microcontroller
Interface
4 bits
5 bits
2 bits
Digital Signal:
5 Bit communication bus
between ABS actuator
and microcontroller
Digital Signal:
Digital Signal:
ABS
Actuator
Future feature,
Error signals from
ABS actuator.
4 Bit bus to
accommodate
expandable user
feed back.
23
Wheel Lock Determination Algorithm Description
This algorithm is predicated if the brake lever is being squeezed.
1.
Determine the delta time between each input pulse coming from a
particular wheel
2.
Compute a rolling average of the time between each pulse. The rolling
average will span 8 pulses.
3.
Compare the current delta time with the rolling average of delta times.
I.
Rider and bike are considered within normal operation
parameters if current delta time is within 10% of rolling average
II.
If current delta time is greater than 10% of rolling average, then
the wheels will be considered locked up.
i.
The rational is that a 10% change in the time between
pulses, and hence speed of the bike, in ¼ of the rotation of
the wheel is physically impossible.
The percentage of current delta time compared to rolling average may need to
be altered or set on a function based on speed. The exact percentage will
become more clear after field testing.
24
Program Flow Chart
Start
Collect First 8 Times
Between Input Pulses
Collect and Compute
Current Sample Time
Compute Rolling Average
Of 8 Most Recent Sample Times
NO
Current Sample Greater
Then 10% Change
in Speed
Convert Rolling Average
Value to Bike Speed
(100-10 mph)
Speed of Bike?
YES
Less than 10 mph
ABS Actuate
YES
Current Sample Greater
Then 20% Change
in Speed
NO
Block Ownership Key
Eric Graves
Power Supply
Richard Roh
Block Connection Key
David Mapes
120 VAC
Nick Bertrand
+12 VDC
Mark Adamak
+5 VDC
Note: Colored outline
represents person who
will assist primary owner
of block
Data
System
Sensors
Microcontroller
ABS Actuator
User Control
And
Feed Back
26
Power Supply Standard
Requirement Battery Charger
Minimum
Maximum
Allocation %
Production Cost (USD)
50
100
28
Prototype Cost (USD)
60
125
36
Min Operation Voltage Range (VAC)
115
Max Power Consumption (W)
15.6
Shipping Volume (cc)
274
35
Product Mass (Kg)
3
33
27
Maximum
Allocation %
Max number or printed circuit boards
1
25
Max Total PCB Area
4
10
Power Supply Standard
Requirement Battery Charger
Minimum
Energy Source Connection
AC, UL listed NEMA plug, UL
compliant AC line cord
Max Shock Force (G’s)
5
Max Shock Repetition
500
Package Moisture Resistance
Enclosed in sealed plastic case
28
Power Supply Standard
Requirement Battery Charger
Minimu
m
Maximum
Oper Ambient Temp Range( C )
0
37.7
Oper Humidity Range %Rh
2
80
Oper Altitude Range (M)
0
8000
Storage Temp Range (C)
0
37.7
Storage Humidity Range % Rh
2
80
Storage Altitude Range (m)
0
8000
Allocation %
29
Power Supply Standard
Requirement Battery Charger
Minimu
m
Maximum
Storage duration ( years)
10
Total parts count
18
Unique parts
16
Material cost (USD)
52
Assembly/Test cost (USD)
15
Allocation %
30
Power Supply Standard Requirement
Battery Charger
Minimum
Maximum
Service Strategy
Dispose
Product Life, MTBF (years)
8
Full Warranty Period (days)
90
Product Disposal
Allocation %
Landfill
31
Battery Charger EMC and Safety Standards
• Electromagnetic Compatibility Standards
EN 61204 –3:2000, Low voltage power supplies with DC output
• UL Listings UL 2202 These requirements cover conductive and inductive
charging system equipment intended to be supplied by a branch circuit of 600
volts or less for recharging the storage batteries in over-the-road electric vehicles
(EV). This equipment is connected to the vehicle by means of a flexible cord and
an electric vehicle connector and are intended for installation in accordance with
the National Electrical Code, NFPA 70. The equipment is located on- or off-board
the vehicle. Off-board equipment is for indoor or outdoor use.
32
Battery Charger Safety Devices
• UL listed AC line cord, water resistant, SJ00W (-40C) P-7K-123033 MSHA,
300 V
• UL listed NEMA plug, rated 15 A, 125 V
• Internal fast acting fuse over current fuse protection
• Diodes to protect voltage regulators and DC battery pack from accidental
polarity reversal
• Electrical isolation charging unit achieved by AC transformer
• Mechanical Interfaces
AC line cord to charger
2 pin Molex connection from charger output to battery pack
33
Performance Requirements
Battery Charger
AC Transformer Primary VAC
Minimum
110
Maximum
130
AC Transformer Secondary
25 VCT, 3A
Charging Volt Range, VDC
14.5
14.9
Charge Current, mA
300
1000
Constant Current, Standard
Rate, 10% of battery’s rated
capacity
Charge Method
Charge Temperature Range, C
Allocation
0
37
34
Standard Requirements
Battery Pack
Minimum
Maximum
Production Cost (USD)
10
Prototype Cost (USD)
18
Operating Voltage Range
VDC
Max Power Consumption (W)
Max Volume , cubic mm
14.5
Allocation
14.9
20
hxlxw
60 x 134 x 67
35
Standard Requirements
Battery Pack
Minimum
Maximum
Battery Connector to Charger
Operating Temp. Range, C
Allocation
2 position Molex
Male/female
-15
40
Max Storage Duration, years
10
Full warranty period, days
90
Service Strategy
Factory
Replacement
Product Disposal
Recycle
36
Performance Requirements
Battery
Nominal Voltage , DCV
Nominal capacity, (20 hour rate)
Minimum
Maximum
Allocate
12
3.4 Ah
Internal Resistance , mohms
60
Temperature dependency of
capacity (20 hour rate)
At 25 C, 100%
Charge Current , A
1.36 A or smaller
37
• Battery Safety Standards
UL 94HB – compliant resin at the material for the battery case
Optional flame retardant resin complying with UL94V-0 available
• Electrical Interface
LM7805 voltage regulator interfaces battery to 5 VDC bus
38
39
Charger Calculations:
•C1 and C2 chosen to smooth out input and output voltages respectively,
general guidelines is 1000 uF for every amp of
current drawn, and approximately twice the input voltage.
• Diode 1 prevents discharge of battery into the voltage regulator.
• Rl chosen so that if the battery is accidentally reverse connected the
LED will light. Rl = 12 V / 50 mA rating.
• Vo is the voltage across the + and – across the battery terminals
2.77 is the given reference voltage at pin 4
• R2 is the 10 K potentiometer, R1 chosen to be 1k
Vo can be adjusted so that is it 13.8 , in the float range.
R2
Vo  2.77 * (1  )
R1
40
• Rsc = 0.45 / Imax
Imax is the charging current. Chosen to be about 10% of rated capacity,
0.54 A was chosen with 1.2 ohm value for Rsc
• 0.45 is the current limit sense voltage
• Pin 5 provides the output power.
• All the current goes through Rsc, this resistor will develop heat. Thus,
P = V*V/Rsc, 0.45x0.45/1.2 = 0.1687 W, therefore ½ W value chosen.
• Pin 2 is an input voltage voltmeter, monitors voltage drops between Pin 5
and Pin 2. Seeks to maintain this voltage at 0.45 V.
• Pin 4 is used to set output voltage with the potentiometer.
• L200 fixes the voltage at Pin 5 so that the reference voltage at Pin 4 is
kept at 2.77. If there is too much current at output , the voltage at Pin 5 is
lowered to keep the current within limits.
41
Battery Charge Monitor
B
a
42
• Negative and positive poles of a DC power supply of 14.9 V will be hooked up
to LM3914
• The 10 K potentiometer will be adjusted until LED lights up.
• The display driver is in DOT mode where only one LED will light at a time. In this
case, LED lights up when charging battery reaches full charge status of 14.9V
• The 47K resistors on Pin 6,7 can be adjusted for changing LED brightness.
• Diode in circuit is for protection against incorrect polarity connection.
43
44
• Robust value chosen for C1, should be 1000 uF for every current draw.
• Maximum current capacity of battery pack is 3.6 Ah. Capacitor voltage should
be about twice the input voltage.
• The 0.1 uF capacitor eliminates high frequency pulses.
45
Design Block 1: Detailed Block Diagram for Power Supply
Recharger
Display Driver
Molex quick
connects
LM3914
Battery Charge
Indicator
Seal Lead Acid Battery
Nominal Voltage 12V
Nominal Capacity 3.4Ah
Battery Low Signal
Transformer 115/25
3A
Full Bridge Rectifier
Filter Capacitor
UL AC Cord
5VDC Bus
LM7805
Filter Capacitor
115VAC NEMA
15A
12 VDC Bus
46
Block Ownership Key
Eric Graves
Power Supply
Richard Roh
Block Connection Key
David Mapes
120 VAC
Nick Bertrand
+12 VDC
Mark Adamak
+5 VDC
Note: Colored outline
represents person who
will assist primary owner
of block
Data
System
Sensors
Microcontroller
ABS Actuator
User Control
And
Feed Back
47
Block Overview
Hall Effect Sensor
–
Interfaces with the microprocessor
–
Mounted on the frame of the bike near both steel brake rotors
– Uses the changing magnetic field to convert the rotation of the wheels into a
digital signal for the microprocessor
Brake Engagement Sensor
– Interfaces with the microprocessor
– Mounted on both of the brake levers which are on the handle bars
– Used to let the microprocessor know that the rider is actively slowing down vs.
coasting to a stop
48
Product Level Standard Requirements
– Operating Temperature Range:
12 – 49 °C
– Operating Humidity Range:
0 – 100 %
– Storage Temperature Range:
– 10 – 50 °C
– Storage Humidity Range:
0 – 80 %
– Storage Duration:
2 years
– Parts Count:
≤ 20
– P.C.B. size:
50 cm²
– Total Mass:
0.15 Kg
– Prototype Cost:
≤ $100
49
Proto / Production Build Expense
Component
Part #
55075-0002-A-ND
296-1668-5ND
296-9542-5ND
450-1103ND
Description
Mfg.
Qty.
2
Price
($)
21.20
Price Break
($) / 5000
9.25
Proto
Total Cost
42.40
Sensor Hall
Effect
IC DUAL
D-TYPE FLIPFLOP 14-DIP
Hamblin
Texas Inst.
4
0.50
0.13
2.00
IC QUAD OP
Texas Inst.
AMP 14-DIP
Mom-NO Micro Alcoswitch
Pushbutton
1
0.43
0.11
0.43
2
3.56
2.63
7.12
Prototype cost
≈ $51.75
Production cost ≈ $24.39
50
Product Level Performance Requirements
– A Hall Effect sensors will be used to determine wheel rotation
 Maximum frequency < 15KHz
– Pushbutton switches will be mounted to the brake levers to determine if the
brakes are engaged.
 Logic High – brakes not engaged
 Logic low – brakes engaged
– Maximum input current ≤ 250mA
– 4 synchronous outputs to the microprocessor
 (2) – Hall Effect
 (2) – Switches
– Outputs
 Vol range
 VoH range
0 – 1.5 Volts
3.5 – 5.5 Volts
51
Detailed Sensor Block
Four signal lines
Microprocessor
Synchronize
Signal
Synchronize
Signal
Hall Effect Sensor
Brake Engagement
Sensor
Input Protection
System
Clock
Input Protection
52
12VDC
5VDC
Design Considerations for Sensors
- Normally open micro-pushbutton switch
- Max Frequency (26 inch mountain bike tire)
• 689.5 pulses/sec or 689.5Hz
• 1 pulse every 1.45ms
- Output Signals
• Output high > min input high (microprocessor)
• Output low < max input low (microprocessor)
53
Component selection
Hall effect sensor: Hamblin part # 55075-00-02-A
Description:
•Rotary position sensor
•Stainless steel construction
•3 wire device
Reason:
•Rugged construction
•Self adjusting magnetic range
•Rotary orientation not critical
•Electronic protection against severe environments
•Compact design
Micro-pushbutton switch: Burgess part # V4LS-9110037
Description:
•Plastic construction
•Normally open operation
•2 wire device
54
DC Drive Analysis
Device
Hall Effect
Sensor
Brake
exerted
Output Input
Type Type
OD
Std
DC Drive Device Parameters
Vil Vih Iil (-) Iih
Vol Voh Iol
Ioh (-) Vhyst Checked
max min Max max max min max Min
N/A N/A N/A N/A N/A 1.5V 3.5V .8uA 6.89 N/A
Yes
mA
N/A N/A N/A N/A N/A 1.5V 3.5V .8uA X
N/A
Yes
55
Implementation Rotary Sensor
56
 Mounting Bracket
Implementation – Brake Handle Sensor
Two state output
Brakes not engaged – Logic high
Brakes engaged
– Logic low
57
Calculations
– 26 inch mountain bike tire (32 pulses per revolution)
r = 13 in.
Circumference = 2*pi*r = 81.68 in.
1 mile = 63360 in.
63360in.
 775.7rev per mile
81.68in
 775.7 rev  100mile  1hour  1 min  32  689.5






sec
 mile  1hour  60 min  60 sec  1rev 
– Pull-up Resistors
Rp (max) 
Vcc  Voh(min)
Ioh  Iih
Rp (min) 
Vcc  Vol (max)
Iol (max)  Iil
58
Verification:
Sensors will be verified in lab using standard lab equipment:
•Power supplies
•Signal generator to generate clock pulse
•Oscilloscope for recording data
•Multimeter
•simulated wheel rotation
59
Block Ownership Key
Eric Graves
Power Supply
Richard Roh
Block Connection Key
David Mapes
120 VAC
Nick Bertrand
+12 VDC
Mark Adamak
+5 VDC
Note: Colored outline
represents person who
will assist primary owner
of block
Data
System
Sensors
Microcontroller
ABS Actuator
User Control
And
Feed Back
60
Block #4: User Interface
By: Nick Bertrand
61
User Interface: Block Description
•
The purpose of this block is three-fold:
- Monitor the status of the ABS including the battery voltage
- Turning the entire system on/off
- Overriding the system when it is on
•
Battery voltage displayed in the form of bar of LED’s
- LM3914 heart of the operation
•
System status displayed in the form of individual LED’s:
- One coresponding to the front brake actuation
- One corresponds to rear brake actuation
•
On/Off Switch :
- Turning the entire system on/off
- Overriding the system when it is on
•
Battery voltage displayed in the form of bar of LED’s
- LM3914 heart of the operation
62
User Interface: Standard Requirements
•
20% of the total volume of the shipping container
•
Will only contain 25% of the total boards in the design ( = 1 board)
•
Will only be 3.33% of the total mass for the product (< 1.5 Kg)
•
Will require 10% of the total cost of all parts and materials (< $40)
•
Max Parts Count: < 35 parts
•
•
•
•
•
•
Max Unique Parts Count: < 20 unique
Parts/Mat $ Allocation: < $30
Asm/Test $ Allocation: < $10
Portion of total design cost: < $30
Operating Temperature Range: 0O to 70O C
Operating Humidity Range ( same as storage range): 0 - 100% RH
63
User Interface: Performance Requirements
•
Nominal Input Power Sources: 12VDC
•
Optical Indicators, Displays: Bar of LED’s (low-battery indicator)
•
Max viewing distance: 2 meters
•
Viewing environment: Outdoors
•
User Controls: On/Off Switch & Override Switch
•
Operational Modes: On/Off, Override
64
User Interface
Detailed Block Diagram for User Interface
Bar of LEDs
(microcurrent)
ABS Override Switch
Override Signal
ABS Online Indicators
ABS Actuate Indicators
(LEDs)
Battery Indicator
Circuitry
12V DC Supply
Microprocessor
On/Off Switch
Battery Pack
65
Switching Overview
•
Override switch
- Pair of push-buttons mounted to handle bars
- Water/Dirt Resistant
- Rated for up to 6A
- Momentary circuitry
- Normally Open
•
On/Off switch
- Rocker switch mounted near battery
- Water/Dirt Resistant
- Also rated to withstand up to 6A
66
Push Button Schematic
1kΩ resistance was placed
between the output and ground
in order to prevent a false
high output due to the length of
the cable and the input high
current coming out of the buffer
input
The output will be connected to a
schmidt trigger input buffer to
ensure there are no false voltage
readings and to sharpen the
transition from high to low.
67
Voltage Indicator Considerations
•
Two main concerns
- cost
- power consumption
•
Optimizing for power consumption
- This is achieved by pulsing the LED at a low frequency and low
duty cycle and conserving battery current in the OFF cycle by
turning the display circuitry off.
68
Voltage Indicator Considerations
•
LCD (Liquid Crystal Display)
- High Cost: Time/Price
- May cook in sunlight and turn completely black over time.
•
LED’s (Light Emitting Diodes) were chosen
•
The LED display driver will be choreographed by a simple timer
In order to conserve power
It will be on an appropriate duty cycle goes high for one second
low for 120 seconds.
69
Timer Design Details
•
Vcc goes from 4.5-18V
•
Supply current 3-12mA
•
Output current 200mA
•
Power dissipation 600mW
•
Operating Temp 0-700 C
•
Timer circuitry
- Lowers the duty cycle and
therefore power consumption
of the design.
70
Timer Design Details
The duty cycle agreed upon:
1 second on for every 120
seconds it is off
To obtain this timing pulse
100kΩ resistor was chosen
for R1 and C1's value was
calculated.
To calculate the value of R1 when
the value of C1 is known the formula
is R1 = T / C1.
Since T = 1 second , the capacitor’s
value turned out to be 100μF
71
Timer Design Details
When power is first connected to
the LM555 timer, the capacitor C1
is uncharged
In Astable mode of
operation, pins 2 and 6 are
tied together to cause the
timer to retrigger itself
Output high time (seconds):
T1 = 0.693(R1+R2)C1
Output low time (seconds):
T2 = 0.693(R1 x C1)
Output frequency =
1.44 / [(R1+2R2)C1]
72
Using this graph right off the data sheet for
the LM555 timer, a value 0.1 μF was the
capacitance chosen due to the fact that
it offered the most conservatively valued
resistance for this applications frequency.
Next, since an on/off time in seconds was
going to be 120 combined, this value was
used in the graph to determine
the appropriate resistor combination to use.
73
The output of this timer circuit is then connected to the gate of a Mosfet
power transistor. Source is connected directly to the battery with the drain
connected directly to the LM3914 in order to supply it with Vcc. Without
Vcc, the chip is off.
74
The battery we chose in this design
will dwindle down to 9.6V in only 30
minutes if loaded with a continuous
current of 3.40 A.
Accurate monitoring of the battery
is crucial. That is why such a vivid
display was chosen.
75
• LM3914 LED DOT DISPLAY DRIVER
• Regulated and programmable current
source outputs
• This feature allows operation from 3V
• Problem with the design is the fact
that an unloaded battery can easily
generate 12V between the terminals
• You may be deceived when you view
this
76
•
This design is far superior to the comparator it has 10 built in
comparators offering a clearer understanding of the voltage remaining
in the supply
•
To display the voltage with a comparator would require more
than one comparator and possibly an external voltage reference
lowering the reliability and applying an additional cost
•
This design is far superior to the comparator it has 10 built in
comparators offering a clearer understanding of the voltage remaining
in the supply
77
Block Ownership Key
Eric Graves
Power Supply
Richard Roh
Block Connection Key
David Mapes
120 VAC
Nick Bertrand
+12 VDC
Mark Adamak
+5 VDC
Note: Colored outline
represents person who
will assist primary owner
of block
Data
System
Sensors
Microcontroller
ABS Actuator
User Control
And
Feed Back
78
Block #5: Actuator/ Valve Control System
By: Mark Adamak
79
The Actuator/Valve Control System Description…
•
Upon command from the control logic , the actuator/valve control system
will release and add pressure to locked brakes causing shorter stopping
distance and better control of mountain bike
•
Comprised of a digital control circuit, power circuit and mechanical
actuation system
•
Will have separate and independently operating front and rear tire control
modules
•
Will use both 5VDC and 12VDC buses
80
Block 5: Actuator/Valve Control Standard Requirements
Market
•
Maximum Block Production Cost:
$45
•
Maximum Block Prototype Cost:
$100.00
Power
•
From Primary DC; nominal 12V DC sealed cell lead acid battery
• From 10-14VDC; maximum draw of 2.75Amps (max 33W usage)
• From 5VDC +/- .250V; maximum draw of 0.250mA (max 1.3125W usage)
81
Block 5: Actuator/Valve Control Standard Requirements
Mechanical
•
Maximum Product Volume:
3100 cubic cm
•
Maximum Product Mass:
2.0 kg ( 4.41lbs)
•
Number of Printed Circuit Boards:
1
•
Total Printed Circuit Board Area:
•
Impact Shock Force:
4 G’s
•
Moisture Resistance:
Weather Resistant
•
Maximum Total Part Count:
50
•
Unique Parts:
40
3097.5 square centimeters
82
Block 5: Actuator/Valve Control Performance
Requirements
•
Designed system will attach to pre-manufactured Hayes hydraulic brake
unit
•
Block components must be attached to bike frame in a low risk location
•
When active, actuator will oscillate pressure removal and addition @ approximately
3-10Hz ( A period of 100 to 333 mS)
•
Components must be able to handle pressure differentials up to 800psi,
depending where in the system the components are located
•
Actuator must be capable of Actuating a system up to 500psi
•
Actuator must allow for “pressure failure”
Note: Mechanical actuator will be only for demonstration of control system. No
real optimization was done for the mechanical part of design
83
Block 5: Detailed Block Diagram for ABS Actuator
12 VDC BUS
Front Brake Unit
5 SIGNAL LINES FROM
MICROPROCESSOR
3 - Control Signals
ABS Control Logic
Input Protection
Buffer
(Diodes and
op-amps)
Actuator Control
Logic
(Lattice 44 pin
Mach 4 PLD)
Actuator Control
Power Circuit (FETs)
2/12 VDC Signal
Snap-Tite
Wattmizer
Valves
Clock Circuit
(LM555)
1/12 VDC Signal
Linear Actuator
(If needed)
Rear Brake Unit
3 - Control Signals
ABS Actuator Control
Power Circuit (FETs)
2/12 VDC Signal
5 VDC BUS
Snap-Tite
Wattmizer
Valves
1/12 VDC Signal
Linear Actuator
(If needed)
84
Block 5: Mechanical Operational Description
While hydraulic brakes are activated and microprocessor commands the ABS unit to turn on
in the front brake unit…
1)
Normally open valve closes, separating hand grip brake from brake calipers
2)
After short delay, the normally closed valve will open to actuator cylinder
which will force the piston to the back of the cylinder, relieving pressure
from the brake calipers
3)
After another short delay motor driven cam will drive the piston back to the
top of the actuator cylinder returning pressure to the brake calipers
4)
Normally closed valve will close separating actuator cylinder from brake
calipers
5)
Normally open valve will open, reconnecting hand grip brake to brake calipers
85
Block 5: Mechanical Operational Description (Cont.)
6)
After N.O. valve reopens, operation will switch to the rear brake unit
Steps 1 through 6 will be repeated until the microprocessor stops commanding to keep
the ABS unit on.
7) When the rider releases the brake the normally closed valve will open for a for half
the period of brake actuation second to release any excess pressure stored in the top of
the actuator cylinder back to the hydraulic line
8)
The unit will then wait until the microprocessor commands the ABS unit on
again
Note: Operations 1-6 should take between .1 to .33 seconds (3 to 10 Hz)
Clearing in operation 7 should take between .05 to .165 seconds
86
87
Block 5: Part1, Actuator/Valve Components
•
2 Snap-tite 2W14W-1NB-E1D5 N.O. wattmizer solenoid valves will be used (one
each in front and rear units)
•
2 Snap-tite 2W13W-1NB-E1D5 N.C. wattmizer solenoid valves will be used (one
each in front and rear units)
•
2 Igarashi 12-24VDC Motors will be used
88
SNAP – TITE WATTMIZER VALVES
Valve:
Part Number:
Maximum Operating Press Diff:
Orifice Diameters:
Response Time:
Power Consumption:
Port Size:
Housing:
Seal Material:
Leakage:
Coil Type:
Standard Voltages:
Media Temperature Limitations:
Weight:
Leadwire:
Agency Approvals:
Wattmizer N.O
Wattmizer N.C
2W14W-1NB-E1D5
2W13W-1NB-E1D5
750 psi
800 psi
1/32"
1/32"
6 to 10 mSec
6 to 10 mSec
.65W
.65W
1/8"
1/8"
Strap Housing
Strap Housing
EPDM
EPDM
Bubble tight (1 x 10-5 cc/sec.)
Bubble tight (1 x 10-5 cc/sec.)
Continuous Rating
Continuous Rating
12VDC
12VDC
(-40 to +180)deg F
(-40 to +180) deg F
2 and 3/4 oz
2 and 3/4 oz
20AWG
20AWG
UL recognition
UL recognition
89
Igarashi Surplus Reversible DC Motor
Voltage:
12-24VDC motor
No load current (@12VDC):
approx 0.4A
Full load current (@12VDC):
approx 1.5A
Diameter:
1.46" diameter x 2.5" long
Electrical connection:
Solder-lug terminals.
Speeds:
2000- 6000 RPM
90
Block 5: Actuator/Valve Components
2 machined blocks will be used. From simple ideal equations…
•
Spring chamber will have a mechanical advantage of 2.5 on moment
arm. Spring rated to minimum 17.9lbs of force
•
Spring in actuator cylinder rated to minimum 9lbs of force
•
Cam at caster will have a mechanical advantage of 1.75 on moment
arm. Cam must exert a minimum of 5 lbs of force upon moment arm
91
92
Block 5: Part 2, The Actuator Power Circuit
•
The front and back units power circuit will each be comprised of 3 FET
switches that connect and disconnect the minimum 12VDC battery power
source to each valve or switch
•
FET switches must be capable of interfacing with the Tri-State CMOS
output pins of Lattice MACH 4 (LV) 64/32 PLD
•
FET switches must be chosen to handle current loads of wattmizer valves
(max 0.5A) and of the DC motor (.4 to 1.5Amps)
•
FET switches should have overcurrent protection
•
Must switch at least 10 times faster than highest considered ABS
actuating frequency ( .1 sec period/10 = .010 sec or 10msec)
•
Must be low cost and low weight
93
Block 5: Part 2, The Actuator Power Circuit
•
The Microchip TC1411NEPA Non-inverting 1Amp high speed MosFET
Driver was chosen to interface the PLD to both the snap-tite wattmizer
N.O and N.C. valves (4 chips total)
•
The Microchip TC4424EPA Non-inverting 3 Amp Dual high speed Power
MOSFET driver was chosen to interface to the Igarashi DC motor. (2
chips total)
94
The Microchip TC1411NEPA PDIP
• 20V for Vdd max power supply needed
• 730mW power dissapation
• Vih: min 2.0Vdc
• Vil: max 0.8Vdc
• Iin: min -10.0uA; max 10.0uA
• Voutput: Vdd - 0.025V
•Iout: max 1Amp
•Rise Time: 35nsec max
•Fall Time: 35nsec max
•Overcurrent protection
95
The Microchip TC4424EPA PDIP
• 4.5V to 18V for Vdd max power supply needed
• Vih: min 2.8Vdc
• Vil: max 0.8Vdc
• Iin: min -10.0uA; max 10.0uA
• Voutput: Vdd - 0.025V
•Iout: max 3Amp
•Rise Time: 35nsec max
•Fall Time: 35nsec max
•Overcurrent protection
96
Example of Front Actuator Wiring Circuit
97
Block 5: Part3, The Actuator Digital Control Circuit
•
The digital control circuit, when commanded by the microprocessor, must
create the proper signals under different conditions to actuate the ABS
unit correctly
•
The Lattice MACH 4 (LV) 64/32 PLD will be used as the main digital
circuit
•
The PLD must be interfaced with the micro controller to obtain the proper
signals
•
The PLD must be capable of providing the proper voltage and current for
the FET drive switches that will be used.
For the TC1411: Voh>2.0V, Vol<0.8 volts, Iin >-10uA and <10uA
For the TC4423: Voh>2.4V, Vol<0.8 volts, Iin >-10uA and <10uA
•
Must cause the ABS unit to switch at a frequency of between 3HZ and
10Hz (a period of .1 to .33sec)
98
Interfacing from the Microprocessor:
•
Digital Input Buffer used to separate Microprocessor from and provide any
needed input current to the PLD
•
4 signals will be sent from microprocessor: FrontOn, RearOn, BrakeFront,
BrakeRear
•
Texas Instruments LM324AN op amps will be used in this circuit
•
After testing is completed op amps may be replaced or deleted
99
Block 5: Part3, PLD VHDL and Schematic Programming
•
3 blocks were created to simplify the design: A main control logic block, a
signal generator and an output switch
•
The main design scheme was conceived from the system set up
•
The front and back wheel ABS units will act semi-independent to each
other
•
To conserve total current load from the battery, only the front or the back
ABS unit will be operating at any given point
•
A clock circuit using an LM555 timer will be set up to clock the PLD for
testing
•
In brief, the PLD will change the 4 signals from the microprocessor into 6
signals to the different actuator components
•
Due to the very fast propagation delays of the PLD (from 2 to 22
nanoseconds), glitch pulses and propagation errors should be minimal100
Lattice Mach 4 CPLD M4-64/32) Speed Grade 12-14
Input Range:
-0.5V to 6VDC
Vil (max):
0.8VDC
Vih (min/Max)
2.0-5.5VDC
Iil (max):
-10uA max
Iih (max):
10uA max
Vol (max):
0.5VDC
Voh (min):
2.4VDC
Iol (max):
-5uA to -3.2mA
Ioh (min):
5-100uA
101
Block 5: Part3, PLD Main Control Block
•
The main control block determines from the inputs to the PLD and several
internal signals what state the sequential logic is in and what state the
logic should change to
•
Including the inputs to the PLD from the micro controller, there are two
internal signals from the signal generator block, and two internal signals
from D Flip-Flop flags
•
The control block creates 7 internal signals:
- signals A, B and C tell the output switch which output pins gets
which output signal
- signals Yfront and Yrear changes the output of the D flip-flop
flags
- signals En and Cl, enable and clear the signal generator
102
Total PLD programming: Highest Hierarchy :
103
Block 5: Part3, PLD Main Control Block
•
Program written in VHDL
•
Program and state diagram complicated
104
Block 5: Part3, PLD Signal Generator
•
Signal Generator creates timed signals that are to be passed to
either the front or rear ABS unit
•
Based off a synchronous timer
•
Signals Sa, Sb, Sc, and Sd are passed to the output switch
•
Signals X and Z are sent to the control block when certain signal
cycles have finished
105
PLD Programming: Signal Generator
TC Q3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1 1
Q2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
Q1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
Q0 Sa Sb Sc Sd X Z
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Sa = (Q3 + Q2 + Q1 +Q0)
Sb = (Q3 xor A2) + /Q3Q1Q0 + Q3/Q1
Sc = Q3(/Q2 + /Q1/Q0) + /Q3Q2Q1
Sd= /Q3(Q2 + Q1 + Q0)
X= /Q3Q2Q1Q0)
Z= TC
106
Total PLD programming: Signal Generator:
107
Block 5: Part3, PLD Output Switch
State
Standby
FrontOn
WtState
RearOn
C_Front
Error
C_All
C_Rear
•
Output switch directs signals from the signal generator to the output
pins, based on the signals A, B and C from the main control block
•
Below is the truth table for the output switch
C
0
0
0
0
1
1
1
1
B
0
0
1
1
0
0
1
1
A FrontValveNO FrontValveNC FrontActuator RearValveNO
0
1 Sa
Sb
Sc
0
1
Sa
0
Sd
1
0
Sd
1
RearValveNC RearActuator
Sb
Sc
Sd
Sd
108
Total PLD programming: Output Switch:
109
Block 5: Part3, PLD Timing Diagram
110
Block 5: Part3, PLD Timing Diagram (Cont.)
As can be seen there are 32 clock pulses in a signal period
111
Block 5: Part3, PLD Timer Circuit
A timer circuit will be need to be created for testing to
create the frequency of actuation between 3 and 10
Hz…
3Hz: .333sec/32clkpulses
320Hz
=.003125sec/pulse or
10Hz: .1sec/32clkpulses= .0103125sec/pulse
or 97Hz
If Output frequency =
1.44 / [(R1+2R2)C1]
And C1= 10uF
R1= 14k Ohms
Then R2 has to be between 200Ohms and 17kOhms
112
Block 5: If Time Permits …
•
Timer and input buffer eliminated. Functions of these devices will be
transferred to Microprocessor
•
Failure or damage detection circuit
•
PLD VHDL and Schematic re encoded into Microprocessor
113
Questions?
114