[James Bruton] is well known for making robots using electric motors but he’s decided to try his hand at using pneumatics in order to make a fighting robot. The pneumatic cylinders will be used to give it two powerful punching arms. In true [James Bruton] fashion, he’s started with some experiments first, using the pneumatic cylinders from foot pumps. The cylinders he’s tried so far are taken out of single cylinder foot pumps from Halfords Essentials, costing only £6.29, around $8.11 US. That’s far cheaper than a commercial pneumatic cylinder, and perfectly adequate for this first step.
He did have to hack the cylinder a little though, besides removing it from its mounting and moving it to a DIY frame. Normally when you step down on a foot pump’s lever, you compress the cylinder, forcing air out the hose and into whatever you’re inflating. But he wanted to push air in the other direction, into the hose and into the cylinder. That would make the cylinder expand and thereby extend a robot fighting arm. And preferably that would be done rapidly and forcefully. However, a check valve at the hose outlet prevented air from entering the cylinder from the hose. So he removed the check valve. Now all he needed was a way to forcefully, and rapidly, push air into the hose.
For that he bought a solenoid activated valve on eBay, and a compressor with a 24 liter reservoir and a decent air flow rate of 180 liters per minute. The compressor added £110 ($142) to the cost of his project but that was still cheaper than the batteries he normally buys for his electric motor robots.
After working his usual CAD and 3D printing magic, he came up with an arm for the cylinder and a body that could fit two more valve activated cylinders to act as a working shoulder. A little more 3D printing and electronics, and he had 3 switches, one for each valve and cylinder. He then had the very successful results his experiment. You can see the entire R&D process in the video below, along with demonstrations of the resulting punching robot arm. We think it’s fairly intimidating for a first step.
To many, the Enigma machine is an enigma. But it’s really quite simple. The following is a step-by-step explanation of how it works, from the basics to the full machine.
Possibly the greatest dedicated cipher machine in human history the Enigma machine is a typewriter-sized machine, with keyboard included, that the Germans used to encrypt and decrypt messages during World War II. It’s also one of the machines that the Polish Cipher Bureau and those at Britain’s Bletchley Park figured out how to decipher, or break. Most recently the story of how it was broken was the topic of the movie The Imitation Game.
[Martin], of the YouTube channel [WinterGatan], recently uploaded a video tour of the Phonoliszt Violina, an orchestrion, or a machine that plays music that sounds as though an orchestra is playing. The interesting thing about this one is that it plays the violin. At the time of its construction, people weren’t even certain such a thing would be possible and so when [Ludwig Hupfeld] first built one around 1910, it was considered the eighth wonder of the world.
The particular one shown in the video is at the Speelklok Museum in Utrecht, the Netherlands. The bow is a rotating cylinder with 1300 horsehairs. To get the sound of a single violin, it actually uses three of them. Rather than the bow being moved to press against the strings, the violins tilt forward to make their strings contact the rotating bow. Only one string is used per violin, hence the reason that three violins are needed. The volume is controlled by making the bow rotate faster for more volume, and slower for less. Mechanical fingers press against the strings with cork to more closely imitate the human fingertip.
The machine consists of both the mechanical violin and piano under the guidance of two paper rolls, with one roll playing at a time. See and hear it in action in the video below.
In The Martian we saw what kind of hacking was needed to stay alive for a relatively short while on Mars, but what if you were trying to live there permanently? Mars’ hostile environment would affect your house, your transportation, even how you communicate. So here’s a fun thought experiment about how you’d live on Mars as part of a larger community.
Not Your Normal House
Radiation on Mars comes from solar particle events (SPE) and galactic cosmic radiation (GCR). Mars One, the organization planning one-way trips to Mars talks about covering their habitats in several meters of regolith, a fancy word for the miscellaneous rocky material covering the bedrock. Five meters provides the same protection as the Earth’s atmosphere — around 1,000 g/cm2 of shielding. A paper from the NASA Langley Research Center says that the largest reduction comes from the top 15 to 20 cm of regolith. And so our Mars house will have an underlying structure but the radiation protection will come from somewhere between 20 cm to a few meters of regolith. Effectively, people will be living underground.
On Earth, producing water and air for your house is not something you think of doing, let alone disposing of exhaled CO2. But Mars houses will need systems for this and more.
The battle’s are done and the results are in — [AltaPowderDog]’s, aka [Carter Hurd], cardboard and foam armor, lightweight Krave robot beat its metal cousins in 2016 and fared well in 2017. How did a cardboard Krave cereal box and foam board robot do that you ask? The cardboard and foam outer structure was sliced, smashed and generally eaten while the delicate electronics, motors and wheels remained buried safely inside.
We covered the making of his 2016 version but didn’t follow-up with how it fared in that year’s Illinois Bot Brawl competition. As you can see in the exciting first video below, despite suffering repeated severe damage to its armor, it won first place in the 1 lb Antweight category!
Battery and RC receiver
Wheels, motors and speed controller
Finished Krave robot
For 2017 he made another one but managed to halve the weight — and so he made two of them! By starting them both within a twelve-inch by twelve-inch area, they were allowed to fight as a team. How did he make it lighter? Partly it was done by doing away with the ability to lift the metal lip in front, the wheels were reduced from four to two, and a smaller servo was used for opening and closing the mouth. The full build video is shown below along with a video of the 2017 battles wherein he won seventh place.
The suspension that makes it all possible is the rocker-bogie. It’s the same suspension we’ve all seen used by the various rovers ambling around on Mars. The whole frame is made of PVC pipes with some connecting metal bars, and each wheel has its own twelve-volt DC motor. Motor control is done simply with a module that combines the 2.4 GHz receiver with motor controllers. When you watch the video below, note where only one hole is drilled through the PVC for making connections instead of two holes. Where there’s only one hole, the two sections of PVC are free to rotate independently of each other. Turning the robot is done by rotating the wheels on one side in one direction and the wheels on the other side in the opposite direction. This is called a differential drive or tank drive, and we’ve highlighted it before for use in making hamster-drive type BB-8 droids.
In true [Matthias] fashion he uses just the one motor both for moving the machine along and for pushing the dominos in place. Not satisfied with that efficient use of parts, the rubber band belts that transfer rotation from the motor shaft to the wheels (bearings) double as the rubber surfaces for those wheels. One of many joys from watching [Matthias] work is seeing how he forms wood into shapes that most people would have trouble sculpting from clay. In this case he does this when he needs parts for reaching over his domino magazine to hold a guide rail in place, and of course the parts are well-rounded and clean-looking.
You might also ask, where did he get all the wooden blocks for dominos? He made them of course, all 300 or so.
Be sure to check out the video below of both the build, and of it in action.