Integration Design

How did we combine all components at each stage?

Iteration One

     For our first iteration, we wanted to use a preliminary Android app to control the servo used to move the primary locking mechanism of a sketch model lock. We integrated the mechanical and electrical systems by attaching a servo horn to the rotating circle of our sketch model (See Mechanical, Iteration 1), which created linear actuation. As the servo turned, the rotating circle would move linearly to change the position of the notch used to secure the U-bar. In order to control the servo, we used an already existing Android app, which came with the ble module. It allowed us to send letters to our Arduino. Our code for our microcontroller was written so that when it received a “U”, it would move the servo to the position needed for the U-bar to come up and therefore be unlocked. When the microcontroller received a “L”, it would move the servo so that the U-bar would be constrained within the system. So, from this iteration, we knew we could control a locking mechanism via a servo controlled via an Android app, which helped us continue to develop future iterations.

Iteration Two

      For our second iteration, we wanted to create a mechanical system that could be controlled via Bluetooth Low Energy and our own Android app. We also aimed to enclose all components, electrical and mechanical, in a lock box which would be used with a chain to lock your bike. To control the mechanical system electronically, we again used a servo to move a gear that was part of a rack and pinion mechanism (See Mechanical Iteration 2). Rather than send a letter to control our lock like in the first iteration, we created our own Android app that allowed you to simply tap a button to control whether you wanted to bike to lock or unlock (See Software Iteration 2). After pressing this button to unlock, the microcontroller again moved the servo to a position which allowed the U-bar to be released. Then, when the button was pressed again, the microcontroller moved the servo to a position that constrained the the U-bar, causing it to lock.
      For this stage of integration, we also started to implement RSSI control of the lock. So, whenever the phone was in close proximity, the system would automatically unlock. Then, when you moved away, the system would automatically lock. But, the RSSI wasn’t always accurate or consistent, so we continued improving it for next integration.      Through this round of integration, we noticed that our integrated lock box system was too large using an Arduino Uno, a larger battery pack, and too many wires. We noted this for the next integration and redesigned our system.

Case of Box with Components inside

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Iteration Three

     For our third integration, we aimed to make a smaller, simpler locking mechanism that could be easily controlled with refined electrical and software systems. We changed the mechanical system so that locking was controlled entirely by a spring-loaded mechanism, and so the servo was only needed to unlock. To unlock, the servo pushes the spring out of the way of the tunnel needed to move the cable in and out of the lock (see Mechanical Sprint 3). The servo was controlled in the same way as it was in the previous two iterations.

Video of Box lock working

Final Iteration

      For the final iteration of our bike lock we wanted to refine the design we created in the previous iteration. We were pleased with the locking mechanism and wanted to focus on the integration with electrical system and create a compact case. We really wanted to create a compact box that efficiently utilized each space. We also wanted to keep the user in mind for the design of the box. The final prototype has a very curved shape on one side which fits into the palm of someones hand making it easy to hold. In the end we were pleased with producing a concept of a smart bike lock. Although this lock may not be strong, it can certainly be improved upon to create a more durable lock.

Final Video

This is showing the components of the lock working. It is apart to show the components of the bike lock.

Video of Components fitting into box

Components of our Project

Mechanical Design

Learn about how the lock was made and its design process.

Electrical Design

What are the electrical componetnts of our design? What is powering everything?

Software Design

What is our firmware? How do things work on the software side of things?