Welcome! Beneath this text on the main page are my most recent posts. Class projects are listed in the left column, while more personal projects are in the right column

Thursday, November 24, 2011

SigmaSecure (Happy Thanksgiving!)

That's right, we had a name change.  Our 2.009 electronic bike lock has made a lot of progress since I last posted.  It's sleeker, more secure, and the electronics are a lot more developed.  Plus, it's no longer just a CAD model! After several weeks of hard work, we got an actual working prototype.  Here are they key features:
  • One piece
  • Spring-loaded hinge design
  • Key-less entry
  • Wireless communication via XBee
  • Solenoid powered dead-bolt
  • Button activated
  • Backup key for mechanical override
The pictures from our technical review were taken down, but here's a Solidworks screenshot:

 I was in charge of electronics, so once we ditched RFID I decided to go with Xbee.  They turned out to be a very convenient solution with longer range capability.  By having an XBee on a low-power mode in a keyfob paired with an XBee in the lock, SigmaSecure can tell when you're nearby and unlock when you press the button. Even better, you can program XBee to signal when it is communicating with another XBee.  With this, we were able to trigger a transistor to allow our 9V battery to power the solenoid.  Since the XBee runs off about 3V, we simply used a voltage regulator to allow it to run off the 9V as well.

Next, we are looking into either using a latching solenoid or motor powered locking system to prevent some failures related to our spring-return solenoid.  Since the final presentation is only 3 weeks away, we are going to quickly make these last-minute changes so that we can end up with a polished product.

Now, back to the festivities at my girlfriends house...

Monday, November 7, 2011


With all of my class midterms behind me, I have recently been spending an excessive amount of time on 2.009: Product Engineering Processes.  Last week I helped present the 'assembly model' of my team's project.  My team is working on an automatic, electronic bike lock idea that I proposed several weeks ago.  To unlock your bike, you simply press a green button on lock, and an RFID reader senses if you're nearby.  If you are close by, which it can tell from a small wristband or keyfob device, a solenoid retracts a deadbolt and the lock swings open.  My job was to create a housing for all of the components and securely integrate them into one piece.  I did some renderings of the solid model we made, so here's one with the side cut away you can see what it would look like, along with the product contract which contains preliminary specifications for the product.

Sound cool?  I sure hope so!  Still have some concerns?  That's okay, because we still have a lot of work to do before we're finished, even though the class deadlines are approaching quickly.  Until next time!