Transcript Out of Date
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 Airtrax.com http://robots.mit.edu/publications/papers/2000_09_Yu,_Dub_Skw.pdf 100 kg Stress Study Out of Date Out of Date Out of Date RE-30 Maxonmotorusa.com www.superdroidrobots.com www.superdroidrobots.com Power Electronics Knowing the requirements for the motor from the mechanical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). Out of Date Datasheet for Maxon RE-30 http://www.maxonmotorusa.com/files/catalog/2005/pdf/05_080_e.pdf Out of Date Operating Voltage = 24V Max Continuous Current = 3.81 A Terminal Resistance = .611 Ohms Terminal Inductance = .00012 H Speed Constant = 369 rpm/V Using the formula from “Robot DNA Series - Building Robot Drive Trains” by Dennis Clark and Michael Owings to determine PWM frequency for this motor, 2f L R Where >> is a factor of at least 10. Out of Date 10 R 2L 10(.611) 2 (.00012) 8.1kHz f PW M f PW M f PW M Using a formula from Maxon Precision Motors Inc. to calculate the current ripple seen on the DC bus: Out of Date Ipp U EMF 2 f PW M L Where U is the supply voltage and the EMF is the speed constant divided by the speed. Ipp 24 ( RPM / 369) 2(10,000)(.00012) Out of Date The motor will have the feature of a power-off electronic brake through the use of a DPDT relay. U1A 1 2 7404 Motor H-Bridge Diagram of Motor with Safety Relay DC-DC When 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. Battery Title <Title> Size A Date: Document Number <Doc> Tuesday , October 10, 2006 Rev <Rev Code> Sheet 1 of 1 Omron G2R Relay example: Contact specifications on Omron G2R DPDT Relay http://www.components.omron.com $5-$10 depending on mounting and options (LEDs) Coil Specification on Omron G2R DPDT Relay 21.8 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: Out of Date Freescale Semiconductor H-Bridge Section of Datasheet, page 1/32 http://www.freescale.com/files/analog/doc/data_sheet/MC33887.pdf Out of Date STMicroelectronics Dual Full Bridge Driver Section of datasheet, page 1/13 http://www.st.com/stonline/products/literature/ds/1773.pdf STMicroelectronics Dual Full Bridge Driver Section of datasheet, page 7/13 http://www.st.com/stonline/products/literature/ds/1773.pdf National Semiconductor LMD18200 Section of datasheet, page 1/14 http://cache.national.com/ds/LM/LMD18200.pdf Out of Date Allegro Full-Bridge Power MOSFET Controller http://www.allegromicro.com/sf/3940/ Available from Digikey; <$5 Out of Date Infineon N-Channel MOSFET http://rocky.digikey.com/WebLib/Infineon/Web%20Data/IPP14N03LA_Rev1.2.pdf Available from Digikey; ~$1 Estimated Power Systems Loads Out of Date Potential Deep Cycle Batteries; PVX-340T costs $105. http://store.solar-electric.com/cosuagmba.html Out of Date Potential battery datasheet giving 1 hour rate of discharge 13.2 Ah at 1 hour http://www.vision-batt.com/newpdf/D/CP12180D.pdf Out of Date Table from datasheet (page 2/2) giving voltage sag levels at different drain currents http://www.vision-batt.com/newpdf/D/CP12180D.pdf Control Power Distribution Board Functional Decomposition Amp DUAC Connector http://catalog.tycoelectronics.com/TE/bin/TE.Connect?C=1&PN=794657-4&M=BYPN&LG=1&I=13 <$1 9A Current (MAX) Parvus PC104 Power Supply http://www.parvus.com/products/Transportation/Board-LevelOEM/PRV-0617/ Out of Date Tenergy Sc 3500 mAh high capacity High Drain (10C) NiMH Rechargeable batteries “Up to 35 Amps 10C high drain current rate” ~$5.00 per cell http://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. Example Control Power Battery http://rocky.digikey.com/WebLib/B&B%20Battery/Web%20Data/BP7-12.pdf Typically used in UPS applications, $16 from Digikey Page 1 of datasheet Out of Date DC-DC Converter capable of 3.3V, 5V, and 12V outputs from a wide input voltage range Section of datasheet, page 1/12 http://cache.national.com/ds/LM/LM2825.pdf For speed feedback an encoder with quadrature output is needed for accurate speed and direction signals. US Digital Encoder with Quadrature output, 5V input 400-1200 pulses per revolution, ~30$ 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: 1 (360) 400 .9 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 Out of Date Potential RTD: Honeywell HRTS-5760-B-T-0-12 Section of datasheet, page 1/3 http://catalog.micro.honeywell.com/AUTHOR/images/honeywell/temp/HRTS.pdf 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) Microcontroller BASIC Stamp II B C D E Atmel AVR (ATmega 8) Motorola Coldfire MCF5307 89C4051 (8051 Architectur e) PIC18F2 431 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 Weight BASIC Stamp II Atmel AVR (ATmega 8) Motorola Coldfire MCF530 7 89C4051 (8051 Architectur e) PIC18F2431 Clock Speed 0.05 3 2 4 4 4 PWM capabilities 0.15 3 4 4 4 4 0.2 3 3 2 2 2 0.05 3 4 4 4 4 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 Microcontroller Cost Power Consumption I/O Ports Continue? No No No No Yes Figure – Control Subsystem Concept Selection Figure – Microcontroller Comparison Chart R Resistance V 1/L d/dt(i) K Inductance Add Ke K d2/dt2(theta) 1/J Kt Add1 Inertia 1 s i Integrator 1 s d/dt(theta) Integrator1 b damping Figure – PM DC Motor Simulation Scope Figure – Open Loop Response of the Simulated PM DC Motor X axis = time (s) Y axis = voltage (V) Resources http://www.microchip.com/ParamChartSearch/chart.aspx?branchID=55&mid=10&la ng=en&pageId=74 http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1 335&dDocName=en010271 http://ww1.microchip.com/downloads/en/DeviceDoc/39616b.pdf (Datasheet) Safety