System Level. Total Costs 3 fully powered and steering, 4 idler modules Prototyping Costs (1 fully...
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Transcript of System Level. Total Costs 3 fully powered and steering, 4 idler modules Prototyping Costs (1 fully...
System Level
Total Costs
• 3 fully powered and steering, 4 idler modules• Prototyping Costs (1 fully powered and steering, tested
on bench):– Power Electronics = 183.50– Control System = 279.19– Mechanical = 221.90– TOTAL = 684.59
• Production Costs:– Power Electronics = 382.34– Control System = 128.59– Mechanical = 657.04– PCB Setup Cost = 200.00– TOTAL = 1367.97
• TOTAL = $2052.56
Mechanical
High Performance Motor Module
High Performance Motor Module
Low Performance Motor Module
http://robots.mit.edu/publications/papers/2000_09_Yu,_Dub_Skw.pdf
http://robots.mit.edu/publications/papers/2000_09_Yu,_Dub_Skw.pdf Airtrax.com
100 kg Stress Study
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Maxonmotorusa.com
RE-30
www.superdroidrobots.com
www.superdroidrobots.com
Power Electronics
Knowing the requirements for the motor from the mechanical subsystem such as required torque and motor speed, a compatible motor is the Maxon RE-30 60 Watt DC Motor (310007).
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Datasheet for Maxon RE-30http://www.maxonmotorusa.com/files/catalog/2005/pdf/05_080_e.pdf
Operating Voltage = 24VMax Continuous Current = 3.81 ATerminal Resistance = .611 OhmsTerminal Inductance = .00012 H
Speed Constant = 369 rpm/V
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RLf 2
kHzf
f
L
Rf
PWM
PWM
PWM
1.8
)00012(.2
)611(.102
10
Using the formula from “Robot DNA Series - Building Robot Drive Trains” by Dennis Clark and Michael Owings to determine PWM frequency for this motor,
Where >> is a factor of at least 10.
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Lf
EMFUIpp
PWM2
)00012)(.000,10(2
)369/(24 RPMIpp
Using a formula from Maxon Precision Motors Inc. to calculate the current ripple seen on the DC bus:
Where U is the supply voltage and the EMF is the speed constant divided by the speed.
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The motor will have the feature of a power-off electronic brake through the use of a DPDT relay.
Tit le
S ize D o c u m e n t N u m b e r R e v
D a t e : S h e e t o f
<D o c > <R e v C o d e >
<Tit le >
A
1 1Tu e s d a y , O c t o b e r 1 0 , 2 0 0 6
1 2
U 1 A
7 4 0 4
H-Bridge
Battery
DC-DC
Motor
Diagram of Motor with Safety RelayWhen power is applied the relay will allow the motor to be powered by the H-Bridge. Without power the relay contacts will be wired such that the motor terminals are shorted.
Omron G2R Relay example:
Contact specifications on Omron G2R DPDT Relayhttp://www.components.omron.com
$5-$10 depending on mounting and options (LEDs)
Coil Specification on Omron G2R DPDT Relay21.8 mA @ 24 VDC Current Draw
http://www.components.omron.com
H-Bridge frequency needs to be at least 8 kHz, however higher frequencies help reduce current ripple and increase efficiency.Examples of compatible H-Bridges:
Freescale Semiconductor H-BridgeSection of Datasheet, page 1/32
http://www.freescale.com/files/analog/doc/data_sheet/MC33887.pdf
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STMicroelectronics Dual Full Bridge DriverSection of datasheet, page 1/13http://www.st.com/stonline/products/literature/ds/1773.pdf
STMicroelectronics Dual Full Bridge DriverSection of datasheet, page 7/13
http://www.st.com/stonline/products/literature/ds/1773.pdf
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National Semiconductor LMD18200Section of datasheet, page 1/14
http://cache.national.com/ds/LM/LMD18200.pdf
Allegro Full-Bridge Power MOSFET Controllerhttp://www.allegromicro.com/sf/3940/
Available from Digikey; <$5
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Infineon N-Channel MOSFEThttp://rocky.digikey.com/WebLib/Infineon/Web%20Data/IPP14N03LA_Rev1.2.pdf
Available from Digikey; ~$1
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Estimated Power Systems Loads
Potential Deep Cycle Batteries; PVX-340T costs $105.http://store.solar-electric.com/cosuagmba.html
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Potential battery datasheet giving 1 hour rate of discharge13.2 Ah at 1 hour
http://www.vision-batt.com/newpdf/D/CP12180D.pdf
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Table from datasheet (page 2/2) giving voltage sag levels at different drain currentshttp://www.vision-batt.com/newpdf/D/CP12180D.pdf
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Control Power Distribution Board Functional Decomposition
Amp DUAC Connectorhttp://catalog.tycoelectronics.com/TE/bin/TE.Connect?C=1&PN=794657-4&M=BYPN&LG=1&I=13
<$19A Current (MAX)
Parvus PC104 Power Supplyhttp://www.parvus.com/products/Transportation/Board-LevelOEM/PRV-0617/
Tenergy Sc 3500 mAh high capacity High Drain (10C) NiMH Rechargeable batteries“Up to 35 Amps 10C high drain current rate”~$5.00 per cellhttp://www.all-battery.com/To power some of the feedback devices a voltage other than the control voltage may be needed. This can be obtained by common DC-DC converters which regulate the voltage to a desired level.
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Example Control Power Batteryhttp://rocky.digikey.com/WebLib/B&B%20Battery/Web%20Data/BP7-12.pdf
Typically used in UPS applications, $16 from DigikeyPage 1 of datasheet
DC-DC Converter capable of 3.3V, 5V, and 12V outputs from a wide input voltage rangeSection of datasheet, page 1/12
http://cache.national.com/ds/LM/LM2825.pdf
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For speed feedback an encoder with quadrature output is needed for accurate speed and direction signals.
US Digital Encoder with Quadrature output, 5V input400-1200 pulses per revolution, ~30$
Lower cost versions available ($20) via “Low cost push-on hub” http://www.usdigital.com/data-sheets/E4%20Data%20Sheet.pdf
With a resolution of 400 pulses per revolution, the maximum error in position feedback will be:
9.
)360(400
1
error
error
Increasing the number of pulses to 1200 decreases the error by a factor of 3.On a 7” diameter wheel, that corresponds to .055” of accuracy
Potential RTD: Honeywell HRTS-5760-B-T-0-12Section of datasheet, page 1/3
http://catalog.micro.honeywell.com/AUTHOR/images/honeywell/temp/HRTS.pdf
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Control System
Comm Protocol Pugh Chart
Controls Subsystem
Microchip PIC 18F2431 Microprocessor
Motor Control Graphical User Interface
The MC-GUI graphical user interface allows users to configure the motor and a wide range of system parameters for a selected motor type, including speed, rotation direction, current, heatsink temperature, fault status and much more. Available at no cost, this Windows® based software program supports Microchip’s motor control demonstration boards to provide a complete solution that helps reduce design time.
Data Monitor and Control Interface Software
A
(Baseline) B C D E
MicrocontrollerBASIC
Stamp II
Atmel AVR
(ATmega8)
Motorola Coldfire
MCF5307
89C4051(8051
Architecture)
PIC18F2431
Clock Speed 0 -1 1 1 1
PWM capabilities 0 1 1 1 1
Cost 0 0 -1 -1 1
Power Consumption 0 1 1 1 -1
I/O Ports 0 1 1 1 1
Flash Memory 0 1 0 1 1
I2C capability 0 0 1 0 1
H-Bridge Technology 0 0 0 0 1
Ease of Programability 0 1 1 1 1
Commercial Portability 0 1 1 0 1
Sum 0 5 6 5 8
Rank 5 3 2 3 1
Figure – Control Subsystem Concept Screening
A (Baseline
) B C D E
Microcontroller WeightBASIC
Stamp II
Atmel AVR
(ATmega8)
Motorola Coldfire MCF530
7
89C4051(8051
Architecture)
PIC18F2431
Clock Speed 0.05 3 2 4 4 4
PWM capabilities 0.15 3 4 4 4 4
Cost 0.2 3 3 2 2 2
Power Consumption 0.05 3 4 4 4 4
I/O Ports 0.1 3 4 4 4 4
Flash Memory 0.05 3 4 3 4 4
I2C capability 0.15 3 3 4 3 4
H-Bridge Technology 0.15 3 3 3 3 4
Ease of Programability 0.05 3 4 4 4 4
Commercial Portability 0.05 3 4 4 3 4
Total 3 3.4 3.4 3.25 3.6
Rank 5 2 2 4 1
Continue? No No No No Yes
Figure – Control Subsystem Concept Selection
Figure – Microcontroller Comparison Chart
b
damping
V
Scope
R
Resistance
K
Kt
K
Ke
1s
Integrator1
1s
Integrator
1/J
Inertia
1/L
Inductance
Add1
Add
id/dt(i)
d/dt(theta)d2/dt2(theta)
Figure – PM DC Motor Simulation
Figure – Open Loop Response of the Simulated PM DC MotorX axis = time (s)
Y axis = voltage (V)
Resourceshttp://www.microchip.com/ParamChartSearch/chart.aspx?branchID=55&mid=10&lang=en&pageId=74
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1335&dDocName=en010271
http://ww1.microchip.com/downloads/en/DeviceDoc/39616b.pdf (Datasheet)
Safety