eel 4906.001 - engineering design1, jamal haque ph.d. performance autoshift system (p.a.s.s.) 1
TRANSCRIPT
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
1: Performance AutoShift System
➢ This product is a new form of automatic shifting system
➢ Works with mechanical derailleur systems and off the shelf drivetrains
➢ Requires limited to no retrofitting of a bicycles preexisting components
2
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Goal
➢ Create a product that can be used in higher performance cycling, specifically cross country mountain biking where frequent, well timed shifting is important
➢ Minimize cost
3
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Audience
➢ Consumers looking for a relatively inexpensive alternative to high priced electronic shifting systems such as Shimano Di2 or Campagnolo EPS
➢ Those wanting the added benefit of automatic shifting
4
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
2: Project Driving Requirements
➢ Power, speed and cadence based shifting.➢ Eliminate unwanted shifting that may reduce
ride performance or potentially damage the bicycle drive train or shifting system.
➢ Simple data recording for maximum and average speed, maximum and average cadence, total distance, total time.
➢ Programmable optimum cadence range, gearshift indexing, etc.
➢ Optional user selected shifting.
5
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
User Interface Requirements➢ A user instruction manual should be made to
assist the user with installation and use. This document should also include a list for trouble shooting and solutions to problems.
➢ The control unit is to be mounted on the handlebar stem or on the handlebars.
➢ The control unit must have a clearly visible screen to display useful data to the user
6
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
User Interface Requirements cont.
➢ The system is to have a user controlled on handlebar multiple button input device, which will be used in the initial system setup and for information display selection.
➢ The user must also be able to manually change gears with on handlebar shift buttons that are accessible while the user has their hands on the handlebar grips.
➢ The system should be easy to learn.
7
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Performance Requirements➢ Change to selected gear in less than 0.25
seconds➢ Operate in a temperature range of -30°C to 50°C➢ The motor must be able to pull at a force of at
least 36.7 N.➢ The total weight of the system should less than
1.4 kg, with a goal weigh of less than 0.7 kg.➢ The system should be able have presets of both
specific derailleur gear indexes and rider preferences.
8
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Capacity Requirements➢ Recorded data is to be stored on a removable
flash card. The flash card should have a minimum storage capacity of 512Mb.
➢ Battery must be able to last at least 2 hours and have a capacity of 2Ah
9
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Monitoring Requirements➢ Detect errors of input/output and display on the
on the screen.➢ Report the current gear, current and average
speed, current and average cadence, total distance and time.
10
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Maintenance Requirements➢ The control unit, motor unit and remote controls
are to be modular and individually replaceable➢ The motor unit parts are to bar easily
replaceable or able to be rebuilt ➢ Cables and housing are to be off the shelf
bicycle cables
11
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Out of Scope➢ Modification of the control unit so that it can
interface with mobile based applications.➢ Modification of the microcontroller storage so
that data is stored for later manipulation in a map/workout generating software
13
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
3: High Level System➢ Intended to integrate into a bicycles existing
drivetrain➢ It will work with the derailleur, chain and
cassette that are already installed on the bicycle ➢ The controls and control unit are simply
mounted to the handlebars ➢ The sensors are fastened to their specified
locations and the motor unit is attached to the bicycles bottle cage mounts or some alternative location on the bicycle frame.
14
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
High Level System Diagram
15
Control Unit
User InputControls
Sensors:Cadence
SpeedPower
Etc.
DisplayMotorUnit
Derailleur
Performance AutoShift System
Cassette
Chain
Existing Bicycle Drive Train
Shift Cable
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Power/Data Schematic
16
Control Unit
Sensors:Cadence
SpeedPowerEtc..
DisplayMotorUnit
User InputControls
VoltageRegulator Groun
d7.2 V+3.3/5 V+InputOutput
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Assumptions➢ Implemented with regularly accessible cycling
components that can be purchased by the general public➢ Components include the derailleur, gear cable and
housing (Bowden cables), and handlebars.➢ Designing the system basic to advanced
programming techniques will be implemented ➢ The sophistication of the system will depend on the
limitations of the team to program the microcontroller in the control unit of the system
➢ User will be able to determine a cadence that is appropriate for their riding style.
17
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Assumptions cont.➢ User must also understand that the systems
automatic shifting is limited to its preprogrammed shifting characteristics➢ Extreme shifting scenarios will require the user to
manually select the gear shifting time.➢ A user that is installing this system should have
access to tools regularly available in a bicycle shop and most households ➢ Allen keys, screwdrivers, socket wrenches, cable
cutters and a bicycle work stand ➢ A user should also have knowledge of how to
correctly adjust a bicycle for the system to function properly.
18
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Assumptions cont.➢ Cost to design and implement this product must
be affordable to design and build ➢ The target maximum cost per team member is
approximately $150➢ The design, test, implementation and
completion of this project must also follow the project schedule ➢ Must be completed before the end of second semester
of the Senior Design course.
19
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Constraints➢ Programming languages
➢ C++➢ C➢ Assembly Language
➢ The system requires a specialized Lithium Polymer charger to safely charge.
➢ Access to mountain bike trail is needed for testing
➢ The system must not exceed the limitations of the motor.
➢ The system must not exceed the limitations of the battery.
➢ The system must not exceed the limitations microcontroller
20
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Dependencies➢ Maximum speed of the motor under load of the
derailleur must be known before the control unit can be accurately programmed to control the shifting.
➢ The sensors need to be calibrated before measurements can be taken and interpreted into useful data.
➢ The external user interface needs to be built before any advanced field-testing can be made.
➢ The chain, rear cogs and front chain rings must be in acceptable condition and not over worn. If this is not maintained the system will not shift correctly even if the bicycle is reverted to the original shifting system.
24
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Dependencies cont.➢ The cables must be maintained, lubricated and
in good condition.➢ The motor gear unit should be lubricated to
reduce additional loss in efficiency from unwanted friction.
➢ The battery must maintain a voltage high enough to not adversely affect the systems voltage regulators and microcontrollers minimum voltage level.
25
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
User Scenarios➢ This product is for a user that wants the benefits
of electronic shifting without the need to purchase a bicycle component set that costs thousands of dollars.
➢ With the benefit of electronically controlled shifting it also has the advantage of automatic shifting to the best gear ratio for the best performance.
➢ P.A.S.S. eliminates the need for a separate cycling computer to provide ride feedback.
➢ There is no need to buy any additional parts because the system can be implemented to any standard bicycle drivetrain.
26
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
4: Project Technical Trades➢ Technical trade study plan addresses design
drivers and component alternatives, and an appropriate closure plan has been provided for studies that remain open➢ These is where you capture things that the team is
trading, i.e.., Bluetooth interface over wires or other interfaces. At PDR all these trades needs to be closed and results have to be presented.
➢ Please documents these trades in your action register and track them
27
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Project Technical Trades➢ Scrapped Lidar triangulation for terrain noting
premeditative shifting isn’t necessary➢ Moved from stepper/servo to a brushed motor
with a worm drive to eliminate stiction and increase battery life ➢ Servos need current to hold position➢ Worm drive allows us to turn the motor off after it’s in
position➢ Moved from Arduino to Teensy for a smaller
design➢ Implemented a potentiometer to eliminate the
need for a positional marker we initially used the stepper for
28
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
5: Project Testing: Cable Pulling Sys
29
Requirements to be Tested:1. Worm drive system must overcome 36.7 Ns of pull force from the derailleur and calculate maximum motor speed with full load2. Motor must oppose stiction (pull-back) without consuming too much power3. Change to selected gear in less than 0.25 seconds
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Project Testing: Cable Pulling Sys
1. Worm drive system must overcome 36.7 Ns of pull force from the derailleur and calculate maximum motor speed with full load▪ A test will be implemented with the load of the
derailleur opposing the worm drive
30
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Project Testing: Cable Pulling Sys
2. Motor must overcome stiction (pull-back) without consuming too much power.
➢ The stiction should be eliminated by having an appropriate worm drive. This will be tested along with the load-baring tests.
➢ Hand calculations and autocad designs will be implemented to find “safe” ranges for each of the variables and hardware will be ordered for testing with a static load.
3. Change to selected gear in less than 0.25 seconds➢ The range-time limit can be adjusted with different pitches,
diameters, and lengths of the worm drive. This will be approximated and then tested with a few variations of worm-drives.
31
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Project Testing: Power Meter
Requirements to be Tested:1. Must calculate torque2. Must use torque to calculate required gear ratio
32
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Project Testing: Power Meter
33
1. Torque must be calculated• Inside the pedals there must be strain gages• Testing the strain can be done using strain gages,
a DAQ, and LabVIEW program mapping each pedal with respective force.
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Project Testing: Power Meter
2. Must use torque to calculate required gear ratio• After torque calculations are complete it must be compared with the
gear ratio for the bike, this will be calibrated for an ideal shift. This may have to be done by riding the bike with the power meter and noting a comfortable gear ratio for each speed and cadence.
34
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
6: Project Risk
➢ Inherent Risks:
➢ No water resistivity
➢ Fragility
➢ Out of initial scope; requires additional time
35
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Project Risk
➢ Programmatic Risks:
➢ Budget: ➢ Power meter parts could be more costly than
expected
➢ Temperature may affect the strain reading
36
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Project Risk
➢ Implementation Risks:
➢ Funding➢ Not enough income➢ Part time jobs
➢ Management➢ Behind on schedule➢ Lack of communication
➢ Developmental➢ Compatibility between devices and
components
37
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Probability (Likelihood)
1
0Consequence
ScheduleIncompletePremature
x
x
High Risk – Severe disruption expected to performance, cost, and / or schedule even with risk mitigation plans in place.
Moderate Risk –Expected disruption to performance, cost, and / or schedule can be overcome by implementing risk mitigation plans.
Low Risk – Little disruption expected to performance, cost, and / or schedule.
Risk of Schedule
x
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Probability (Likelihood)
0Consequence
Performance
x
Risk of Performance
x
xExceeds
Expectations Nonfunctioning
1
EEL 4906.001 - Engineering Design1, Jamal Haque Ph.D.
Probability (Likelihood)
0Consequence
x
x
Cost> $500< $150
x