Bike Rack Availability Tracking System Group 26: Sam Luo, Jason Pao, Jason Wang

Introduction What is the project? System that allows bike commuters to find a place to electronically park their bike through an electronic bike lock that attaches to bike racks Inspiration for the project: Seeing cluttered bike racks outside of ECEB

Objective Goals for this project include: Find a way to display available bike racks through a common user interface Creating a safe, easily activatable electronic bike lock that is available to anyone who owns a RFID device Solutions this project can accomplish: Shortens the time bike commuters spend on identifying a safe location to park their bike Decreases the cost of owning a bike by removing the need to buy a lock Provides a safe lock for commuters to use due to the secure nature of U-locks

Physical Lock Design

Original Design: Block Diagram

Changes: Pressure Sensor What was its purpose? Detect whether or not a user properly inserted the U-portion of the lock Why was it changed? Swapped for contact switch Exact amount of pressure exerted by the U-portion is irrelevant Only needs to detect whether or not it is properly inserted

Changes: DC Motor + H-bridge What was its purpose? Keep the lock unlocked or locked Why was it changed? Swapped for servo motor Horribly inefficient power consumption and fine tuning Don’t need many rotations

Final Design: Block Diagram

Design: Microcontroller Software Flow Chart

Design: Microcontroller PWM Output What was it required to do? Maintain pulse width of 0.5ms for 90 degrees (locked) and 2.2ms for 180 degrees (unlocked) Verification: Output locked and unlock state, hold oscilloscope parallel to PWM output, verify pulse widths Horizontal Cell Width: 2ms

Design: Contact Switch What was it required to do? Allow current to go through if pressed Verification: Hook up the contact switch in series with an LED, power source, and resistor. LED must light up if switch is pressed

Design: NFC Controller (PN532) What was it required to do? Identify a smartphone or RFID equivalent card if held within 1.5 inches of the antenna Consistently create a unique ID for each new RFID card read Verification: Hold two different RFID cards within 1.5 inches of the antenna. Unique ID for each card should be consistent every time the cards are read

Design: Server Flow Chart What was it required to do? Proper I 2 C master functionality Store data through a wifi connection Verification: Parse UID and send back verification bit Display and verify server data on PHP server interface

Design: Smartphone UI What was it required to do? Query the server data relevant at the time of the query request Display the data properly after queried data is retrieved Verification: Queried in 5 minute intervals, lock status must update properly

Challenges: Power Circuit What was it required to do? Boost converter: output a step-up voltage of 5V +/- 0.7V Charging circuit: keep the rechargeable battery above 2.5V Verification: Circuit had correct voltage mean but too large of a voltage ripple Dimensions: 3.2 x 1.65 x 0.8 inches

Conclusion What was accomplished: Available locks and lock status are viewable through an Android application Electronic lock uniquely identifies RFID cards and smartphones Electronic lock securely locks and unlocks What didn’t work? Voltage ripple was not controlled well due to poor boost converter design Solar panel charging circuit failed to sustain voltage level

Future Work What improvements can we make to this project? Redesign the power system and components to be more efficient and sustainable Move server to the cloud through IoT chips Real-time update of info and map visualization of nearby racks Create a catchy name The acronym for Bike Rack Availability Tracking System (BRATS) isn’t very attractive!

Credits We would like to thank: ECE 445 Staff TA: Iain Brearton Dave Switzer from the Machine Shop Mark Smart from the Electronics Services Shop

Questions?