Let A CPR Robot Save The Day

Four highschool students in Lyon France are building a CPR robot, with the aim of removing the endurance problem faced by those delivering this form of essential first aid.

By every after action report, CPR is an emotionally and physically exhausting way to save a life. When someone’s heart stops beating their breathing stops too. After that there’s a very small window in which to keep just enough oxygen in the blood to prevent brain damage and organ failure. A person has to precisely position their hands and press, repeatedly, with enough force to break someone’s sternum in order to keep their heart pumping; sometimes for over fifteen minutes waiting for rescue to arrive. On top of that, depending on which school of thought they learned the technique, they may be required to also force air into the patients lungs.

While this pushes the boundary of human endurance, a robot would not have the same issue. In fact, many of the existing problems are solved. CPAP Machines can force air into lungs all day long. A motor and a mechanism could position and provide the mechanical pumping motion to keep the blood flowing. Sensors could tell when the heart takes back over. The machine is currently a proof-of-concept built from plywood, and off-the-shelf parts. Yet it can maintain the 30 compression – 2 breath cycle indefinitely on a CPR Dummy.

It’s an interesting idea; while defibrillators do exist, they don’t always get the heart going in time. We wonder if someone more medically inclined can weigh in on this interesting idea.

source https://hackaday.com/2019/11/30/let-a-cpr-robot-save-the-day/

Multi Material 3D Printing Makes Soft Robot

When you zoom in on a fractal you find it is made of more fractals. Perhaps that helped inspire the Harvard 3D printers that have various arrays of mixing nozzles. In the video below you can see some of the interesting things you can do with an array of mixing nozzles. The coolest, we think, is a little multi-legged robot that uses vacuum to ambulate across the bench. The paper, however, is behind a paywall.

There are really two ideas here. Mixing nozzles are nothing new. Usually, you use them to mimic a printer with two hot ends. That is, you print one material at a time and purge the old filament out when switching to the new filament. This is often simpler than using two heads because with a two head arrangement, both the heads have to be at the same height, you must know the precise offset between the heads, and you generally lose some print space since the right head can’t cross the left head and vice versa. Add more heads, and you multiply those problems. We’ve also seen mixing nozzles provide different colors.

The printers in the video, can lay down filament of different types and achieves very rapid change overs. According to the authors:

… exploit(s) the diode-like behaviour that arises when multiple visco-elastic materials converge at a junction to enable seamless, high-frequency switching between up to eight different materials…

This should be within reach of existing hobby-level mixing hot ends, although perhaps it requires different materials than we currently use.

In addition to the robot, there is a folding origami-like structure that uses both rigid and flexible plastic. The only thing that struck us is that while the array of nozzles makes fast prints with repetitive structure, it didn’t seem possible to turn them off. So the things you could print with, say, an 8-head nozzle would be very limited by the spacing between the nozzles since all the nozzles print together.

Still, this could be a good research project for anyone with a mixing hotend. The capability is even available on tiny printers. If you want to mix four filaments, there’s always the diamond. If you get results — positive or negative — experimenting with this technique, write it up, hit us with a tip, and we’ll pass it along.

source https://hackaday.com/2019/11/30/multi-material-3d-printing-makes-soft-robot/

Circuit Simulation in Python

Using SPICE to simulate an electrical circuit is a common enough practice in engineering that “SPICEing a circuit” is a perfectly valid phrase in the lexicon. SPICE as a software tool has been around since the 70s, and its open source nature means there are more SPICE tools around now to count. It also means it is straightforward enough to use with other software as well, like integrating LTspice with Python for some interesting signal processing circuit simulation.

[Michael]’s latest project involves simulating filters in LTspice (a SPICE derivative) and then using Python/NumPy to both provide the input signal for the filter and process the output data from it. Basically, it allows you to “plug in” a graphical analog circuit of any design into a Python script and manipulate it easily, in any way needed. SPICE programs aren’t without their clumsiness, and being able to write your own tools for manipulating circuits is a powerful tool.

This project is definitely worth a look if you have any interest in signal processing (digital or analog) or even if you have never heard of SPICE before and want an easier way of simulating a circuit before prototyping one on a breadboard.

source https://hackaday.com/2019/11/30/circuit-simulation-in-python/