I’ll see your Launchpad controlled arm and raise you Arduino controlled autonomy

This OWI robot arm has been hacked to add position sensors and Arduino control. [Chris Anderson] took one look at the Launchpad controlled OWI from earlier today and said “wait a minute, I’ve already posted my own version of that project”. Well, that will teach him not to tip us off about his hacks!

The position control is a really nice addition. Potentiometers added to each of the joints (shoulder, elbow, and wrist) can be read by the ADC pins on the Arduino. Just a bit of calibration will let the microcontroller board know the position of the arm at any given time. The control technique is the same as the Launchpad hack, with one glaring drawback. [Chris] is using the Adafruit motor driver shield. It uses L293D H-bridge chips, but it only has four channels. There are five motors on this arm, so the video after the break shows it moving around without any outside instruction, but you won’t see it grab onto anything since the Arduino can’t move the gripper!

Still, the position feedback makes the case for this version. Just remember to order an extra chip if you want full control.

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Experimenting with an air muscle and sensor feedback

Check out this setup that [Ruenahcmohr] is using in his air muscle experiments. The orange mesh contains an air bladder that is connected to a hose on the right side. The bladder can be filled, or emptied with two solenoid valves not seen here (but you can get a good look in the video after the break). The muscle attached to chain on the other end and is kept under constant tension by a spring. The chain bends 180 degrees around a gear which is connected to a potentiometer. This gives feedback to the ATmega32 which controlling the whole thing. This way, the slider seen above can be used to control the apparatus.

We don’t know if [Ruenahcmohr] has a use in mind for this setup, but it certainly looks promising! We’ve seen these air muscles used for haptic feedback before, but right now we’re drawing a blank when it comes to ideas. What would you use it for?

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Mixed I/O testing module

Needing to test the display interface for a multitude of different sensors [Fileark] built himself this analog and digital input/output simulator. Along the bottom is a double row of trimpots that adjust analog voltages. Each voltage is measured by the Arduino inside and its value is displayed on the graphic LCD screen to confirm that the hardware you’re testing is making correct measurements. There’s also digital I/O in two different forms. To the upper left are momentary push buttons but the DIP switch bank below that allows the same connections to be toggled on and off. It’s not an automated test bed, but if you’ve got a lot of I/O, or a lot of hardware to test this will save you some real time.

Don’t miss the demonstration video after the break.

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Analog computer does math

This analog computer can multiply, divide, square numbers, and find square roots. It has a maximum result of ten billion with an average precision of 2-3%. [Miroslav’s] build recreates something he saw in a Popular Electronics magazine. It uses a resistor network made up of three potentiometers with a digital multimeter is an integral part of the machine. To multiply a number you set the needles on the first two knobs to the numbers on which you are operating. To find the result turn the third knob until the multimeter has been zeroed out and read the value that knob is pointing to. It seems much more simple than some of the discrete logic computers we’ve seen, yet it’s just as interesting.

Web controlled watering can

Here’s a watering can and water vortex that are controlled with a webkit browser interface. The interface displays a drawing of the watering can on your browser. If you grab one of the handles on the circle around the image and move it, the can will rotate as well.

Okay, so this isn’t going to change the world and actually presents a fairly useless watering setup. But [Ben] seems to be a master of fabrication and that’s what we appreciate in this build. The watering can is solidly mounted and moves fluidly with seemingly little effort from the motor. He uses a spring to keep the rope loop taut, sourcing a castor wheel and automotive power-window motor to provide the motion. The hinged base on which the can sits has a potentiometer in it, used to measure the current position of the watering can. Remember these techniques as they’ll come in handy in your future builds.

There’s also a little bonus at the end of the video after the break. We wondered what [Ben] might use that power drill controller hack for. Looks like it makes an appearance in his water vortex work.

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Easy data input for LabVIEW

Props go to [Michael Nash] for establishing an interface between National Instrument’s labVIEW and an Arduino (an example video using a potentiometer is above). Personally, from the one time we were forced to use labVIEW, we hated every second of it.

One reason it’s so terrible, is the Data Acquisition Modules cost well into the hundreds of dollars, yet the documentation and help resources are very scarce. By using an Arduino instead of the modules, the price and difficulty decrease a considerable amount. Which begs the question why has it taken so long to get a decent (and so simple) of a setup working?

Hacking Game Boy for sound

[Gijs] cracked open his Game Boy and added some parts to give him more sound synthesis control. He uses Little Sound Dj (LSDj), a popular Game Boy program used to pump out those classic 8-bit sounds. The unit seen above and heard in the clip after the break has an added potentiometer and circuit board. He’s got a few other hacked Game Boys on his site as well, including an Arduino generating random music on the handheld.

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