Model of a Transmission Line

Transmission lines are the kind of thing that seems to confuse beginners. After all, the fact that short-circuits can have infinite impedance and open-circuits can behave like a short is not intuitive at all!. That’s why we like [Tinselkoala]’s latest video that shows a nice model of a transmission line. It helps to understand the line as inductors and capacitors in series-parallel connection.

Any pair of wires used to transmit electrical power have tiny amounts of inductance and capacitance. This is not a problem with DC or low-frequency AC, but when the frequency is sufficiently high, weird things start to happen. The energy tends to escape as radio waves, and current reflects from discontinuities such as connectors and cable joints.  For this reason, transmission lines for high frequency signals use specialized construction to minimize those effects and reduce power losses.

[Tinselkoala] has built a model of a transmission line using coils and capacitors to simulate the inductance and capacitance of the line, with LED’s placed between the coils. He feeds the system with the signal generator with frequencies from 10 kHz to 1 MHz. In his words, they act as simple “visual voltmeters” to show the peaks and nodes of the standing waves of voltage in the line.

It is relatively simple to build your own version if you want to experiment with this fascinating subject. You will only need some magnet wire, capacitors, resistors and LED’s. If the subject sounds interesting to you,  here you can find an excellent introduction to transmission lines.

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Rusty ARM

You’ve probably heard that Rust is a systems programming language that has quite the following growing. It purports to be fast like C, but has features like guaranteed memory and thread safety, generics, and it prevents segmentation faults. Sounds like just the thing for an embedded system, right? [Jorge Aparicio] was frustrated because his CPU of choice, an STM32 ARM Cortex-M didn’t have native support for Rust.

Apparently, you can easily bind C functions into a Rust program but that wasn’t what he was after. So he set out to build pure Rust programs that could access the device’s hardware and he documented the effort.

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Pneumatic Rotary Vane Joints Lend A Gentle Helping Hand

Festo has released a video showing the workings of their BionicCobot, a pneumatic robot arm developed for lending a helping hand to humans at a workstation. Since it works intimately with humans, it has to be safe, producing no harmful movements, and reacting when encountering an obstacle such as an arm containing delicate human bone. This it does using pneumatics and rotary vanes.

Rotary vane in action
Rotary vane in action

The arm has seven degrees of freedom, three in the shoulder, one in the elbow, another in the lower arm, and two in the wrist. But you won’t find any electric motor or gears. Instead each contains a rotary vane. Compressed air pushes on both sides of the vane. If the air pressure is the same on both sides of the vane then it doesn’t rotate. But with more pressure on one side than the other, the vane rotates. This is much like in a human arm, where two muscles work together to bend the arm, one muscle contracts while the other relaxes. Together they’re referred to as an antagonistic pair. In addition, each joint has a circuit board with two pressure sensors for monitoring the joint.

Using pneumatics, if an obstacle is encountered, the pressure can be released, making it instantly safe. And air being compressible, the joint can behave like a spring, further adding to the safeness. By controlling the pressure, the spring can be made more or less tense.

You can see it in action in the video below the break, along with more details such as how they use ROS, the popular, open system Robot Operating System which we’ve seen here a lot before, along with their Festo valve bank, one of which our own [James Hobson] used for his slick elysium exoskeleton. The video also covers how they handled running the hoses, the kinematics and the UI software.

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Electromechanical Lunar Lander

One of the smash hits of the 1970s arcade was Atari’s Lunar Lander. A landing craft in orbit around a moon would descend slowly towards the surface, and through attitude and thrust controls the player had the aim of bringing it safely in to land. Many a quarter would have been poured into the slot by eager gamers wanting to demonstrate their suitability for astronaut service.

It was to this game that [Chris Fenton] turned when he was looking for inspiration for the 2016 NYCResistor Interactive show, and the result was a Lunar Lander game with a difference, one in which the gameplay was enacted through a physical lander and lunar surface. In this case the moon in question is a papier-mâché-covered inflatable ball, and the lander is a 3D-printed model on the end of a lead screw. Control is provided by an Arduino, with a rough facsimile of the original control panel and a set of microswitches on the model to detect a crash or a safe landing.

The result is a surprisingly playable game, as can be seen from the video below the break.

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Hackaday Prize Entry: Analyzing and Controlling Hand Tremors

For the millions of people suffering from Parkinson’s and other causes of hand tremor, there is new hope in the form of [mohammedzeeshan77]’s entry into the Hackaday Prize: a glove that analyzes and controls the tremors.

The glove uses an accelerometer and a pair of flex sensors to determine the position of the hand as it oscillates. A Particle Photon crunches the raw data to come up with the frequency and amplitude of the tremors and uploads it to the cloud for retrieval and analysis by medical staff.

Hand tremors can vary in frequency and severity depending on the cause. Some are barely perceptible movements, and others are life-disrupting shakes. By analyzing the frequency and amplitude of these tremors, doctors can better understand a patient’s condition.

The best part of this glove is that it also provides immediate relief to the wearer by stabilizing the hand. A rapidly spinning super precision gyroscope counteracts the tremor oscillations as it tries to maintain its position. The last time we saw innovation like this, it came with a set of attachments.

Hands-On the Hot New WeMos ESP-32 Breakout

Just two weeks ago our favorite supplier of cheap ESP8266 boards, WeMos, released the long-awaited LOLIN32 ESP-32 board, and it’s almost a killer. Hackaday regular [deshipu] tipped us off, and we placed an order within minutes; if WeMos is making a dirt-cheap ESP32 development board, we’re on board! It came in the mail yesterday. (They’re out of stock now, more expected soon.)

If you’ve been following the chip’s development, you’ll know that the first spin of ESP-32s had some silicon bugs (PDF) that might matter to you if you’re working with deep sleep modes, switching between particular clock frequencies, or using the brown-out-reset function. Do the snazzy new, $8, development boards include silicon version 0 or 1? Read on to find out!

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Friday Hack Chat: Chip Gracey from Parallax

Learn the ins and outs of multi-core microcontrollers as Chip Gracey leads this week’s Hack Chat on Friday 5/5 at noon PDT. Chip founded Parallax and has now been working for more than a decade on the Propeller 2 design, a microcontroller which has 8 and 16 core options.

When it comes to embedded development, most people think of a single process running. Doing more than one task at a time is an illusion provided by interrupts that stop one part of your program to spend a few cycles on another part before returning. The Propeller 2 has true parallel processing; each core can run its own part of the program. From the embedded engineer’s perspective that makes multiple real-time operations possible. Where things get really interesting is how those cores work together.

Here’s your chance to hear about multi-core embedded first hand, from both the silicon design side and the firmware developer side. Join us for a Parallax Hack Chat this Friday at noon PDT.

Here’s How To Take Part:

join-hack-chatOur Hack Chats are live community events on the Hackaday.io Hack Chat group messaging.

Log into Hackaday.io, visit that page, and look for the ‘Join this Project’ Button. Once you’re part of the project, the button will change to ‘Team Messaging’, which takes you directly to the Hack Chat.

You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.