team lifted: critical design review andrew cober dan crowe sujan gautam anthony schubert ryan yeash
Post on 21-Dec-2015
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Overview
Project Problems and Design Modifications Hardware/Schematics Electromagnet Construction Firmware/Software Logistics and Administration Questions
Project: Magnetic Control
Use electromagnets to control the position of a magnetic objectControl x and y position
Control object through a user interfaceFirst approach: buttonsSecond approach: touchscreen
Problems Encountered
Power limitations Prefabricated Electromagnets have
undesired design Iron core laminates disappointing Buck converters unable to source
sufficient current
Design Modifications
Control object on 2D surface Construct electromagnets powerful
enough to meet specifications Use ferrite cores for lower core loss Implement H-bridge to divert current Control position of a magnetic object Apparatus made of plexiglass
Revised Goals
Effectively control the object with 1cm accuracy in 2-D plane
Touchscreen sensingTouchscreen interface
Object follows a user defined path
Revised Design
Four electromagnets mounted on a platform
Cyclone II FPGA used to control the current to the electromagnets through H-bridge
Control based on position of the objectTouchscreen
Electromagnets
I-Core solenoid 3.5”x1”x1” Ferrite core for low power loss and high
magnetic flux density 18 AWG wire to handle sufficient current
and lower resistivity 100-200 turns depending on field output
Some Calculations
Length 3.5” Number of turns 100 DC current 5 A Relative permeability
200 B 0.5 Tesla This does not take into
account the core and wire loss
Some Altera Details
HAL Hardware Abstraction LayerAn API (Application Programming Interface)
for use with Altera’s Nios II modulesAllows easy C programming
Parallel I/OGeneral purpose interface for peripheralsAllows for many possible configurations
Current Tasks
Interrupt-driven user interface Have been using HAL API to write interrupt handlers for
button inputs Will eventually use for user input
SRAM Configured Cyclone II on development board to use off-chip
SDRAM Would prefer to use off-chip SRAM
Smaller but faster Need off chip memory to use HAL
Start processing ADC input
Controller Firmware
Proportional Controller Implemented through control of
electromagnets with PWM Derivative Controller
Implemented by calculating the rate at which the object is moving
Hence PD control
Software Flow DiagramPower on
Initialize Hardware
Activate Magnets
ObjectDetected?
CenterObject
Yes
No
ObjectShifted?
Yes
No
Start UserInput
User shift? Yes
No
ShutdownSequence
Cost
Qt. Part Attained From Ea. Cost4 Iron Cores Power Lab $0.00 $0.001 Touchscreen www.touchscreens.com $170.00 $170.004 H-bridge (complete cost) Advanced Circuits, Digikey, Mouser $78.00 $312.003 FPGA PCB (complete cost) Advanced Circuits, Digikey, Mouser $116.00 $348.002 Cyclone II Dev. Board Tom Brown $0.00 $0.002 18 AWG Magnet Wire www.bulkwire.com $20.00 $40.00
Misc.Extra Resistors, Capacitors, etc Digikey $30.00Apparatus (complete cost) Home Depot $60.00Ferro-Fluid 1L $200.00
Total $1,160.00
Spent $592.16Left $1,320.84
Division of LaborAndrew Cober
Dan CroweAnthony Schubert
Ryan YeashSujan
Gautam
Mechanical R CI R R
PCB CI R
Power Control
R CI R
System Modeling
R CI R R
Control Algorithm
R R R CI
Firmware R R R
R – Responsible and CI – Consult and Inform
Everyone is informed when a task is completed or needs further assistance
Milestones
CompletedCDR: Obtained most parts, started
development of software framework, FPGA PCB design completed
Milestones Continued
Still to comeM1: Simple one dimensional control and
movement of object M2: Control x and y coordinates of the objectExpo: Path control and completion of project
Risks
Power limitations into the magnets may limit object size
Control complexity may be too difficult to implement
May have to rescale from FPGA to MSP
Possible Extensions
Addition of LCD to display object dataTouchscreen for user controlTrackball control
Wireless communication between apparatus and user interface
Implement multi-core processing on Cyclone II