This weekend I finished assembling and painting the chassis and I’m pretty happy with the results. It looks much better than the original version at least.
The motors and ultra-sonic sensors are installed and everything is looking pretty tidy so far. I made custom 3D-printed mounts for the ultra sonics so that they would sit flush with the wood and to help secure them in place.
Now I need to take a step back and figure out the plan for the rest of the electronics.
After a break of several months I’ve finally had my second attempt at a laser cut wood design and this time all the pieces did fit together! There were some gaps that needed filling so it wasn’t perfect, but it was close enough. Here’s a quick photo of the new chassis for my autonomous vehicle. I’m really pleased with the results and I can see that I’ll be doing a lot more work with laser cut wood. It looks much better than my attempts at manual wood-working!
Next steps will be to prime and paint the various parts before gluing everything in place, then I can get started on the electronics, which will be largely the same as last year.
I had some time this evening to start playing around in Sketchup to design a rough concept for the next version of my autonomous vehicle. This time around, I’ll be using laser-cut wood rather than my own woodworking skills. One design goal is to make it easier to access the motors and electronics for repairs so I’m designing “access hatches” this time, which I plan to cover with 3D printed panels.
If you haven’t already seen, Sparkfun just announced the rules for this year’s competition. It’s a shame there is no aerial course this year, but let’s face it; it was only a matter of time before there was a nasty accident.
There are still some details to be announced, such as the details around the special 150 point-earning short-cut. I’m definitely planning on entering again this year but probably need to wait until all details are available before I start designing a new bot.
Also this year there will be a battlebot competition. I’m intrigued by this but it is something I so far know nothing about so I think I’ll just be a spectator for this event.
After a crazy few weeks and weekends working on a new software release at work, I finally have some time to play with my new 3D printer and get back to work on a hobby project I’ve taken on for my local maker space. We’re putting together a Rube Goldberg machine and my section will be based around my mini Dalek robot. The plan is to have the Dalek receive a ping-pong ball from the previous section and then transport it to the next section and release it. It sounded so simple to start with but I’ve been struggling with figuring out how to attach the gripper arm and servo to the steel tube that I was using for the plunger arm.
This morning I had time to design a custom mount in Sketchup and then 3D print it. I made a mistake with aligning the mounting holes on one side but it’s close enough and works really well. Here are some photos.
My Dad told me about the Darby Digger many years ago and I just saw another mention of it today and I thought I’d share it here. The Darby Digger was a steam-driven machine for ploughing fields. It was invented around 20 years earlier than the tractor that we are familiar with today. My great grandfather, Robert Hasler, helped build it. Here’s a photo of Robert Hasler driving the Darby Digger (around 1879).
This next photo shows the Prince of Wales who came to see a later version of the Darby Digger. Robert Hasler is standing in front in this photo. Early versions of the Darby Digger actually walked on six or eight legs but later versions used wheels.
I was looking for more information online this evening about this and was amused to find that is was picked up by Make magazine back in 2006 (http://makezine.com/2006/11/01/the-darby-steamdigger/).
I was also amazed to see that someone built a fully working scale version of one version of the Darby Digger back in the 1970’s and took a video which is now available to watch on YouTube.
I can’t even begin to imagine how hard it would have been to create a machine like this, driven by steam power, in the late 1800’s.
I’ve been learning how to use Sketchup to design parts for 3D printing and have now printed my first useful part – a simple mount for an HC-SR04 ultrasonic sensor. There are plenty of designs I could have downloaded from Thingiverse, but I wanted to design my own as a learning exercise. Here’s the rendering of the design in Sketchup:
Here is the 3D printed part. This was a medium resolution print in PLA.
The ultrasonic sensor fits quite snugly, but I’d probably need to use some hot glue to secure it in place. This feels like a good first step in 3D design though.
On Black Friday, rather than spend time getting crushed in the sales, I spent the day learning how to use Inkscape to produce a design for laser cutting. The design I’m working on is a new chassis for my autonomous vehicle. I found this great video on YouTube which really showed me everything I needed to know to get started.
It was slow going to start with, but after a while I felt I was getting the hang of this. I sent my initial design off to Ponoko ($35 including shipping) and around two weeks later the end result arrived. Here’s a photo of the base and the sides. I was really pleased with the end result but unsurprisingly I made a couple of mistakes in the design, so I will have to do at least one more revision of this before I have anything usable.
Hopefully I’ll find some time over Christmas to make more progress on this.
If you’ve been following my blog then you’ll know that I’m a fan of the handy little electret mic breakout boards that combine a mic and a pre-amp so that you can interface these directly with the Arduino’s ADC (analog-to-digital converter) for an easy way to get audio into a project.
However, as much as I like these, they are not ideal for a finished project and I’ve started looking into how I can use regular microphones and plug them into an audio jack on my projects. This would involve building a pre-amp circuit into the project though, since microphones generate a tiny voltage that would not register with an ADC.
As a first step, I purchased one of SparkFun’s opamp breakouts and used this to amplify the output from a PDMIC58 mic (quite the bargain at $9.99) and then feed the output to my project.
This actually works very well and SparkFun are kind enough to make the schematic available, so it would definitely be possible to incorporate this into my project.
It seems that most mono microphones use a 1/4″ or 1/8″ TRS (Tip, Ring, Shield) jack but there are some differences in how they are wired up, and some microphones require power and some don’t, so it seems challenging at the moment to come up with a general design that will work with a wide range of microphones, and I don’t have access to any other microphones for testing.
For my purposes I may be better off making or buying a separate PCB with an audio jack and the pre-amp circuit and then connect the output to my shield. I definitely have much more to learn about microphones.
I have now made an Arduino shield version of my voice changer project. This has been quite the learning curve, learning to layout PCBs using Eagle. Having a finished board makes this project feel much more professional and complete and I’m very pleased with the results. This is my first PCB design and it was a fun project.
I’m making a small number of these boards available on Tindie for $29.99 plus shipping. I’m curious to see if there’s any interest for a board like this. Click here for the product page on Tindie, which has a demonstration video too.