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M DR Presentation. Friday December 7, 2012. Reviewed by: Prof. Bardin & Prof. Gao. Paulo Leal, Kevin Okiah, Chris Finn & Tim Mirabito. Outline. PDR Recap MDR Goals/Progress Design Choices CDR Goals Demos Cost Breakdown Questions?. PDR Recap. Project Goal
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MDR Presentation Friday December 7, 2012 Reviewed by: Prof. Bardin & Prof. Gao Paulo Leal, Kevin Okiah, Chris Finn & Tim Mirabito
Outline • PDR Recap • MDR Goals/Progress • Design Choices • CDR Goals • Demos • Cost Breakdown • Questions?
PDR Recap • Project Goal Give people a means to monitor and control the electrical devices within their households. • Motivation • Energy conservation has a significant social & economic impact. • It is hard to conserve energy because • Limited quantitative data • Limited social awareness • Limited residential control
Tim’s MDR Goals/Progress • Understand Watt Meter Design • Draw schematics of Kill-a-watt subsystems • Communicate With Xbee • Route current and voltage signals to Xbee • Proprietary Design • Transformer less power supply
Design Choice: P4400 Watt Meter Back Side PCB Front Side PCB
Design Choice: P4400 Watt Meter watt meter analog board schematic showing the input and output from the wall socket, as well as the probe points for the current sense resistor
Design Choice: P4400 Watt Meter watt meter transformer less power supply schematic showing the input from the analog board and the output connections to the microchips
Design Choice: P4400 Watt Meter watt meter LM2902 quad op amp schematic showing the input from the analog board and power supply followed by the output connections to the microcontroller
Design Choice: Proprietary Design transformer less power supply design schematic for a 15V and 50mA output. The top right graph shows the simulated 15V voltage output and the bottom right graph shows the simulated 50mA current output.
Design Choice: Proprietary Design Initial PCB layout for the transformer less power supply design schematic with a 15V and 50mA output.
Design Choice: Proprietary Design Utilization of instrumentation amplifier chosen for high CMRR. This is essential to provide greater precision for measuring differential voltage across a current shunt resistor. This chip has an CMRR of 120dB.
Design Choice: Proprietary Design Using the current design of the XBee Explorer as a foundation, the final implementation of the watt meter PCB will have a subsystem with pin out headers for easy insertion of an XBee module
Tim’s CDR Goals • Complete proprietary design of watt meter subsystems • Integrate relay and XBee layouts into proprietary design • Complete schematic and PCB layouts for a fully functioning system
Paulo’s Goals/Progress • Networking Circuit • Setup XBee Network • Transmit data wirelessly from model A to B • Relay Circuit • Design
Design Choice: XBee Wireless Radios • XBee Series 1 • Indoor Range: 100ft. • More than enough for average room • RF Data Rate: 250Kbps • Sufficient for our application • Frequency: 2.4 GHz • Channel hopping to avoid Wi-Fi interference • AES encryption • Secure wireless data transmissions • Analog to Digital converter • Digitalize analog inputs from watt meter
Design Choice: Transmission Frequency • One of the problems encountered in the transmission of data between the XBee and Raspberry pi was generating the necessary current from the Kill-a-Watt device. • In the initial approach to this solution we use a 10000uF capacitor biased at 5V to yield a 50mA current. Based on the following formula, we calculated the discharge time to be approximately 17 ms, which would simulate the period of a sine wave at 60Hz. Where Vo = 5V R = 100 ohm and C = 10000uF
Design Choice: Switching Mechanism • PowerSwitchTail for 110-120vac • Provide single pole switching at 20 amps • 5300vrms isolation • Driving voltage as little as 3vdc @ 3ma
Design Choice: Relay Circuit • Xbee • Triggering mechanism • Decoupling Capacitors • C1 – remove lower frequency • noise coming from the wall power supply • C2 – remove higher-frequency noise • coming from Voltage regulator • NPN Transistor • Provides 5V of direct current to relay
Paulo’s CDR Goals • Integrate relay and XBee layouts into proprietary design • Develop tablet/phone app (SDK interface)
Christopher’s MDR Goals/Progress • Setup web server • Setup database • Receive input from XBee • Parse input • Store input in database • Allow connection from user interface to database • Over LAN • Over internet • Relay circuit control
Design Choice: Raspberry Pi • 700 MHz ARM computer • Runs custom Debian Linux • Utilize Linux packages • SD Card for storage • Ethernet Port • Utilized for connection to HomePlug • 2 USB ports • Utilized for data input from XBee module • Low cost • Small profile
Design Choice: Software • Apache service • MySQL database • Efficient & lots of resources • Avahi-daemon • Sets Raspberry Pi hostname (solves dynamic IP problem) • PHP • Enable user interface to query database • Python • pySerial module for receiving XBee input data from USB & for sending commands to XBee • MySQLdb module for insertion of input data
Design Choice: STUNT • Web server must be accessible from behind router • Network Address Translation(NAT) makes this tricky… • Solution: Simple Traversal of UDP Through NATs and TCP too (STUNT) • allows applications running behind a NAT to determine external IP and port-binding properties, allowing applications to establish TCP sessions between two NAT'ed hosts
Design Choice: HomePlug Communication • Communicate via Raspberry Pi Ethernet port • Package communication data in Ethernet packets • Implement SSL for secure end to end communication Secure SSL Channel via Ethernet cable via Electric line
Christopher’s CDR Goals • Implement MySQL structure • Transition from Ethernet internet connection to wireless • Receive commands from user interface • Create function to form & send XBee command packets • Will be used for initialization of XBee modules & for controlling the relay circuit • Setup STUNT
Kevin’s MDR Goals/Progress • Develop a Basic user interface prototype that is functional across all operating system • Come up with a plotting functionality • Demonstrate plotting data by successfully querying from the database • Function to take in user input and manipulate the data as specified • Function to assimilate new devices to the system • Function to receive and send relay Signal
Design Choice: Browser Based User Interface • Cross Platform Network Interface
Design Choice: Browser Based User Interface Plotting functions • FLOT • AwesomeChartJS
Design Choice: Browser Based User Interface Programing Languages • HTML5 • CSS • JavaScript • PHP
User Interface CDR Goals • Develop a function to take in user input and manipulate the data as specified then plot the data • Develop a function to assimilate new devices to the system • Develop a functionto receive and send relay signals