Our first generation robotic lawn mower wasn’t the complete success that we hoped it would be. It started off simple enough, as a remote controlled lawn mower, using a hobby RC controller and some used wheelchair motors. With some simple steel framing, the lawn mower was durable, easy to drive, and worked surprisingly well for a remote controlled mower. Well, it was a little hard to steer in a straight line. That’s why I added a GPS. However, when I attempted to add the GPS and inertial guidance functionality to see if it would operate autonomously, it failed miserably. Although it would navigate to preset waypoints, it would only find one waypoint on the North side of lawn, and one waypoint on the South side. Obviously, this wouldn’t be sufficient to operate as an autonomous lawn mower. The goal here was not a random pattern, but a parallel path mowed lawn. Continue Reading
After setting up the Probotix Fireball V90 CNC machine, and using it to cut out a number of pieces for various projects, I decided I wanted a better way to control the router’s spindle speed. Although the Bosch Colt router that I was using had a speed dial, it was impractical to adjust it as I was cutting a project, and impossible to tell what speed it was actually running at. A setting of “7” on a 1-10 dial means nothing in terms of actual spindle RPM. Continue Reading
We were only about one month into the 2013 lawn mowing season when we decided that we had had enough. Mowing the lawn wasn’t fun. It’s hot, dirty, smelly work that is better left to someone, or something else. We decided right then and there that we needed to make a robotic lawn mower. One that could be controlled by remote control, or if we were adventurous enough, one that was fully autonomous.
We had only one requirement for this project. The robotic lawn mower would need to mow in a pattern similar to how a human would mow – with straight lines. A lawn mower that operated like a Roomba in a crazy, random pattern was not going to work. We planned to start with an existing lawn mower, modify it for remote control, and then eventually include an inertial guidance system and microprocessor to allow it to mow on its own. Continue Reading
Now that we have our first nixie tube clock built, it was time to step it up a little and make something a little more challenging. Nixie tubes, using a glow discharge instead of LCD or LED displays, have an old world charm to them, yet can be made to operate similar to a modern display. The plan here was to pair these tubes with a nice wooden clock case, made using the CNC machine. The end result is something that has a warm wooden feel to it, with a colorful numeric display which is both attractive and, when used with a GPS for accurate time setting, highly functional as well. Continue Reading
After constructing a solar panel and battery system to power a Raspberry Pi, I wanted to find a way to monitor how the battery and charger was performing. There are several ways to accomplish this task, usually involving a voltage sensor, a current sensor, or both.
A voltage-based sensor can be used to monitor the charge of the battery. Over a typical day, the battery voltage should rise as the solar panel charges the battery, and then discharge at night while the Raspberry Pi consumes power from the battery. A common technique for monitoring voltage is to use a voltage divider. If appropriate resistances are chosen for the voltage divider circuit, the drain on the battery from the sensor is negligable.
Another option is to use a current sensor. A current sensor placed off of one of the battery terminals will measure how much current is flowing into or out of the battery. Continue Reading
While browsing one of our favorite electronic supplier’s web sites, we found that Ladyada sells a really interesting looking clock that uses a vacuum florescent display with eight glowing digits. This clock proved to be an excellent soldering instruction project for a younger Rusty Nail Workshop helper.
The most interesting feature is the display, which is similar to those found on VCRs, old car radios, and microwave ovens. The vacuum florescent display was invented in 1967 in Japan and hundreds of millions are used annually around the world. They are different than an LCD in that they use a filament to emit electrons which are diffused by grids. The electrons strike a phosphor-coated plate and emit light, and can be manufactured to emit light in different colors. Continue Reading
One of my interests involves robotics, especially autonomous self-charging robotics. However, I realize most of my skills center around microprocessors, wood construction techniques, electronics, and some limited computer software skills. I knew I was missing the ability to make custom, metal and/or wood components for my various projects. Thus, the need arose for a CNC machine. If only I knew how to use one!
After some online research, I narrowed down my options to a Shapeoko or a Probotix Fireball V90. The Shapeoko is significantly cheaper and everything is made with open source license rights. The Fireball V90 uses some proprietary components, costs more, but has a stronger setup and is more capable than the Shapeoko. After considering my needs, I decided I wanted to be able to carve and cut both wood and metal, focusing on aluminum. I’ll need to dedicate space on my workbench for either of these two machines, and dust collection will be an issue for either one. I understand I will need a separate computer if I purchase the Fireball V90, and I may need separate CAD software. Continue Reading
A few of the regular readers of this blog will know that I enjoy using a Web Energy Logger to track information about my home. Not only does this device track temperatures, but I also use it to interface with a Continental Control Systems WattNode. The WattNode allows me to track my energy usage on a minute by minute basis.
Of course, once you have all of this data, you need an interesting way to display it. I originally purchased a Samsung Galaxy 7” Tab, but found the Android operating system difficult to work with. I also found the touch screen to be much less responsive than the iPhone I was using on a daily basis. So I ended up returning the Tab, and I purchased a refurbished Apple iPod Touch (4th Generation). The iPod Touch included a retina display, which was clearly a better screen than any other off-the-shelf LCD I could buy elsewhere. Continue Reading
When I first heard about the Raspberry Pi, a $35 computer that can run Linux, I was mildly impressed. My first problem was that I did not understand Linux, and my second problem was that I couldn’t figure out a need for a computer this inexpensive. Like all of my other projects, it was just a matter of time before I figured out that not only did I need to have this computer, but that I would find the perfect use for such a device.
Since I had missed the original order date for the Pi, I was either doomed to wait 10+ weeks for one to ship, or I would have to purchase one on E-bay. I debated going with a Gumstix computer instead, but finally settled on an unopened Pi being sold on E-bay. A few days later, I had a Pi to play with. Continue Reading
About a year ago, a friend mentioned how she made yogurt in a Crock-Pot slow cooker. It sounded impressive, and a good way to save on the cost of yogurt. We also figured that we could customize our yogurt recipe and eventually make something that would rival the taste of store-bought yogurt.
After researching a number of ways to make yogurt in a slow cooker, it all essentially came down to heating some milk up to about ~180 degrees fahrenheit, then cooling it down and holding it at approximately 110 degrees for six to eight hours. Since I have some experience working with Arduino microcontrollers, I figured this was a natural project to take to the next level. I also had some experience with PID control theory, so I knew I could write some software that would control a slow cooker and hit a desired set point with minimal error. Continue Reading