Open Source Software Projects
SolidWorks to URDF Exporter
The SolidWorks to URDF exporter is a SolidWorks add-in that allows for the convenient export of SW Parts and Assemblies into a ROS URDF file. The exporter will create a ROS-like package that contains a directory for meshes, textures and robots (urdf files). For single SolidWorks parts, the part exporter, will pull the material properties and create a single link in the URDF. For assemblies, the exporter will build the links, and create a tree based on the SW assembly hierarchy. The exporter can automatically determine the proper joint type, joint transforms and axes.
Completed: Aluminum Speaker Cabinet Design
Most speaker cabinets today are constructed from Medium Density Fiberboard. This material is inexpensive, easy to shape and has good internal dampening property. However its heavy and not terribly stiff. In order to achieve reasonably well performing cabinets, the MDF pieces must be thick and internally braced. In a goal to get resonant frequencies above the audible frequencies, I'm attempting to trade dampening for lower weight and higher stiffness. The machine-ability of aluminum also allows for better joint possibilities and thus more complex panel designs, which will allow me to get away from boring box shapes.
I developed an all aluminum subwoofer enclosure. It is a single-ported enclosure designed for extended base response. Cylindrical in shape, it measures 19in wide by 33 in tall. The outer shell is 1/16in aluminum with 1/4 hollowed aluminum discs for internal bracing. It’s held together with J-B Weld. The design was first modeled in CAD, and analyzed using FEA software to check for internal resonances. The components include a 10in subwoofer driver, driven by a 400W amplifier. Because it is so large, the enclosure could eventually accommodate a larger diameter driver.
Building: Calibrated RGB Lightsource
If you had an RGB light source that could emit a wide gamut of colors with precision and accuracy what would you use it for? I intend to answer this question by building a 4000 lumen LED lighting device from Luminous Devices PT-54 LEDs. These chips are driven at 13.5A and need a precise current source without wasting much power. They need a current source capable of delivering up to 5.5V. Energy efficiency isn't the driving factor, but it should still be reasonable. After building this, I plan on calibrating this light using a colorimeter so that by varying duty cycles I can easily reproduce a wide range of brightnesses from the different LED devices.
Past: Human Following Robots
How would people react to a robot if it actually acknowledged their existence and interacted with them? Wanting to find a fun way to make an iRobot Roomba interactive with people, I searched for cheap motion tracking options. Instead of a webcam that requires computer level processing, I wanted to use an arduino and some cheap sensor options. The best solution I was able to find, was to utilize a passive infrared sensor typically used for motion detection. The sensor essentially provides an analog signal corresponding to strength of radiation in the sensor range. Since it doesn't provide direction, a servo will be used to help scan the space in front of the Roomba. Then using basic signal processing algorithms, the Roomba will move in the direction of the strongest signal.
Conceptualizing: Self Balancing Riding Wheel
Can the segway be even simpler? Pretty much all individual transportation options for short distance travel are in the $100-$500 range (roller blades to road bikes). Yet the Segway scooters cost $6000 to $8000, operate for a range of 15-20 miles and have a top speed of 12 mph or so. Therefore as the market has shown, acceptability is fairly low. This project seeks to minimize the amount of hardware needed and attempt to demonstrate whether a single wheeled version is feasible.
What remains yet to be seen is the ideal amount of computer controlled stability needed. Will the user and the computer fight one another to create a highly unstable system? Clearly a single wheeled system will require a lot of training, but so do bikes and skateboards.
Completed: Reborn 1970s Centurion roadbike
Having recently moved to Los Angeles from Pasadena, I needed a revamped mode of transportation that was inexpensive and allowed me wiz past rush-hour traffic. The last month I was living in Pasadena, I just happened upon a garage sale where I was able to pick up a very used and neglected early '70s Centurion road bike for $20. It appeared to had been used in at least 5-10 years as the seats and tires were breaking apart from age. The frame itself showed surface rust in some areas, but fortunately the frame was not bent and a large part of the valuable parts on the bike remained intact.
With the help of tools from The Bicycle Kitchen in LA, I tore the bike down to its bare frame, cleaned everything, painted the frame and reassembled the bike. Ultimately I had to buy new tires, intertubes, cables, cable housings, grip tape, and a single spoke. After all these parts, cost savings over a solid used bike on Craigslist or Ebay were negligible, but I now know this bike like the back of my hand. It is now my typical mode of transportation around the local area when I'm not walking.
Completed: Solid State Amplifier
Essentially just a hobby project, seeking to build a single channel audio amplifier with an National Semiconductor LM3886 at the center. Gives a good clean sound with plenty of bass response.
Completed: Collapsable and Hardware Free Shelf Design
I sought to design a shelf that could both be collapsable and portable, yet for aesthetic reasons contained no hardware at all. This design was to blend form and function. The key features were tenon joints which required a tongue shape cut from the horizontal members fitted into slots in the vertical pieces. Wedges then slipped through a square hole in the tongue part to hold the horizontal piece taught against the vertical pieces.
The shelf was created out of maple hardwood with purpleheart wood wedges. The entire shelf was sanded and finished with an oil based stain.