Prioritising Mechanical Multiplexer

May 4, 2021 by 17 Comments

When automating almost any moderately complex mechanical task, the actuators and drive electronics can get expensive quickly. Rather than using an actuator for every motion, mechanical multiplexing might be an option. [James Bruton] has considered using it in some of his many robotics projects, so he built a prioritizing mechanical multiplexer to demonstrate the concept.

The basic idea is to have a single actuator and dynamically switch between different outputs. For his demonstration, [James] used a motor mounted on a moving platform actuated by a lead screw that can engage a number of different output gears. Each output turns a dial, and the goal is to match the position of the dial to the position of a potentiometer. The “prioritizing” part comes in where a number of outputs need to be adjusted, and the system must choose which to do first. This quickly turns into a task scheduling problem, since there are a number of factors that can be used to determine the priority. See the video after the break to see different algorithms in action.

Instead of moving the actuator, all the outputs can connect to a single main shaft via clutches as required. Possible use cases for mechanical multiplexers include dispensing machines and production line automation. Apparently, the Armatron robotic arm sold by Radioshack in the ’80s used a similar system, controlling all its functions with a single motor.

[James] knows or two about robotics, having built many of them over the last few years. Just take a look at OpenDog and his Start Wars robots. Continue reading “Prioritising Mechanical Multiplexer” →

Robotic Gripper From A Squishy Ball

May 4, 2021 by 11 Comments

Soft robotic grippers have some interesting use cases, but the industrial options are not cheap. [James Bruton] was fascinated by the $4000 “bean bag” gripper from Empire Robotics, so he decided to build his own.

The gripper is just a flexible rubber membrane filled with small beads. When it is pushed over a object and the air is sucked out, it holds all the beads together, molded to the shape of the object. For his version [James] used a soft rubber ball filled with BBs. To create a vacuum, he connected a large 200cc syringe to the ball via a hose, and actuated it with a high torque servo.

It worked well for small, light objects but failed on heavier, smooth objects with no edges to grip onto. This could possibly be improved if the size and weight of the beads/BBs are reduced.

For some more soft robotics, check out this soft 3D printed hand, and the flexible electrically driven actuators. Continue reading “Robotic Gripper From A Squishy Ball” →

Synth Gains Plug And Play Analog MUX

May 4, 2021 by 3 Comments

High school computer engineering teacher [Andy Birch] kept losing track of I/O pins on his home-built synth, so he made a custom plug and play addressable MUX system to solve the problem. [Andy]’s synth is based on the Teensy microcontroller, and he was already using CMOS analog 8:1 multiplexer chips (CD4051) to give him more I/O pins. But I/O pin expansion means that now there are more I/O pins to forget. Did I hook up that pitch potentiometer on U3 pin 13 or was it U10 pin 2?

He proceeds to design an addressing system for each I/O card using three bits (expandable to four) supporting eight cards, with a maximum of 16 possible in the future. Since each card may not use all eight signals, each card can tell the Teensy how many signals it has. [Andy] does his address decoding on each card using OR and XOR gates. We would have considered using a single 74HC85 four-bit magnitude comparator instead. That would require only one chip instead of two, but would deprive his students of the opportunity to learn gate level address decoding.

When seeing the term “I/O card”, you may be fooled like we were into thinking this was using PCBs and some kind of motherboard. [Andy]’s I/O cards are actually solderless breadboards mounted on the back of the synth control panel. We really like his bus technique — he removes the power strip sections from several breadboards and repurposes them as address and data buses. Check out the thorough documentation that [Andy] has prepared, and let us know if you have ever designed your own plug and play method for a project in the comments below.

[Ed Note: We love us some muxes!]

I/O Cards — Note the use of Power Strip Bars as Data / Address Buses

 

Linux Fu: Mixing Bash And Python

May 4, 2021 by 24 Comments

Although bash scripts are regularly maligned, they do have a certain simplicity and ease of creation that makes them hard to resist. But sometimes you really need to do some heavy lifting in another language. I’ll talk about Python, but actually, you can use many different languages with this technique, although you might need a little adaptation, depending on your language of choice.

Of course, you don’t have to do anything special to call another program from a bash script. After all, that’s what it’s mainly used for: calling other programs. However, it isn’t very handy to have your script spread out over multiple files. They can get out of sync and if you want to send it to someone or another machine, you have to remember what to get. It is nicer to have everything in one file.

Continue reading “Linux Fu: Mixing Bash And Python” →

New Contest: Reinvented Retro

May 4, 2021 by 22 Comments

There are so many ways to make things look awesome by pulling inspiration from great retro hardware. And combining today’s futuristic functionality with yesterday’s lines, colors, and kitsch is the quick path to a winning combination. So why not give it a try and show us what you got? That’s the gist of Hackaday’s Reinvented Retro Contest which begins right now and runs through June.

The is a very cool Roku

This smart TV should help get you thinking in a retro-modern way. You’d never know it wasn’t stock… except when it starts streaming The Falcon and the Winter Soldier via the Roku hidden inside. Fit and finish on this one is spectacular and that woodgrain remote is a piece of artwork!

So what will it be? Keurig in a 1960’s Perculator? Desk lamp in a rotary telephone? GHz oscilloscope where a CRT used to live? Perhaps a Raspberry Pi laptop in a 1990’s form-factor? You get to decide what “Retro” means, just make sure you thoroughly show off the build!

Digi-Key is sponsoring this contest and there are $200 shopping sprees from their warehouse up for grabs for each of three top winners. Make a project page over on Hackaday.io and use the “Submit project to…” dropdown in the left side bar to enter it in the Reinventing Retro Contest.

Feel What The Temperature Is Like Outside Without Leaving Your Bed

May 4, 2021 by 17 Comments

Your smartphone might be able to tell you what the weather is like outside, but you’d have to go outside yourself to really feel it. To do this from the comfort of your own bed, [Sagarrabanana] built a clock that lets you really feel the temperature. Video below with English subtitles.

It is basically a box with a solenoid inside to knock out the time, and a Peltier plate on top. Give the box two knocks, which are detected by a piezo element,  and it will tell you the current time down to 15 minute increments in “bell tower” format. Give it three knocks, and the ESP8266 will fetch the ambient outside temperature from a cloud service and cool or heat the Peltier element to that temperature, using a H-bridge motor driver module. The code and design files are available on GitHub if you want to build your own.

All the components are housed inside an attractive 3D printed box with a machined wood top. Although we think this is a very interesting idea, we can’t help but suspect that it might be counterproductive for getting you out of bed on those cold winter mornings.

While alarm clocks are falling out of favor, they are still a popular build for hackers. We’ve covered one that looks like it came from a fallout shelter, and another with a very cool looking VFD display. Continue reading “Feel What The Temperature Is Like Outside Without Leaving Your Bed” →

TypeMatrix EZ-Reach 2030 Is Better Than Your Laptop Keyboard

May 4, 2021 by 38 Comments

Maybe you’re not ready to take the leap into a full-on ergonomic split keyboard. That’s okay, that’s cool, that’s understandable. They’re weird! Especially ones like my Kinesis Advantage with the key bowls and such. But maybe your poor pinkies are starting to get tired and you’re ready to start using your thumbs for more than just the space bar. Or you want to be able to type ‘c’ properly, with your middle finger.

In that case, the TypeMatrix could be the keyboard for you. Or maybe for travel you, because it’s designed as a quasi-ergonomic, orthonormal layout travel keyboard to pair with your laptop, and as such it sits directly over a laptop keyboard without blocking the track pad. (How do people use those things, anyway?)

Of course, you could use this as a desktop keyboard as well, although it’s unfortunate that Control and Shift are stuck on the pinkies. More about that later.

First Impressions

When I saw this keyboard on eBay, I was attracted by two things: the layout, and the dedicated Dvorak light. (And, let’s be honest — the price was right.) I’ve always found myself generally turned off by chocolate bar-style ortholinear keebs because they’re so incredibly cramped, but this one seemed a more acceptable because of the slight split.

The first thing I noticed was the fantastic number pad integration. The different colored keycaps are a nice touch, because the gray makes the number pad stand out, and the red Delete is easy to find since Num Lock is squatting in the upper right corner. Why does Delete always feel like an afterthought on compact keebs? I also like the location of the arrows, and it makes me think of the AlphaSmart NEO layout. Unfortunately, it comes at the cost of burying the right hand Enter down in no-man’s land where you can’t exactly hit it blindly with great accuracy right away. If only you could swap Shift and Enter without messing up the number pad!

Continue reading “TypeMatrix EZ-Reach 2030 Is Better Than Your Laptop Keyboard” →