Robot waits for no man when recharging

Yikes, that power connector certainly wasn’t designed by Apple. Ugly as it may be, it’s the charging cable for a robot and acts as a sensor that allows the robot to properly align and plug into a power receptacle.

We’re going to go off on a tangent for just a second. We often think of the Rat Things from Snowcrash when considering robot power. They were nuclear powered (or something) and instead of recharging required constant cooling. Those day’s aren’t exactly around the corner but we think they’ve been realized in the lawn mowing robots that have a little nests to recharge in. Base stations work but they require the machine to return to the same place, or to have multiple charging stations.

The point is, this specialized cable makes base stations for robots obsolete. Now a robot can plug into any outlet it can get near, a great thing for robots roving large facilities. After the break you can see a video of this process. The robot arm zeros in by scanning horizontally and vertically and measuring the magnetic field put out by the AC in the wires of the outlet. Take a look, it’s a pretty neat piece of engineering.

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Arduino traffic light

[Rockwell] sent us an update on his traffic light hacking. Dedicated readers will remember seeing this legally attained traffic signal controlled through a parallel port from back in 2005. The new update swaps the old port for USB and adds several autonomous functions which are demonstrated in the clip after the break. The update includes a nice UI and some notifications for things like email, IMs, Reddit posts, etc.

He’s given control of the hardware over to an Arduino. Instead of building the board into the project he’s included just the parts he needs; an AVR running the Arduino bootloader, a crystal and filtering caps, and an Arduino serial to USB module for connectivity. The AC load switching is handled by three relays. The relays he links to are 12VCD rated coils. We think this should have pointed to 5VDC coils as that’s the voltage that the logic circuit are running at. Be careful with switching these AC loads, this traffic light isn’t a toy.

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AC Shield will take your breath (heart beat) away.

[Ryanjmclaughlin] came up with the idea of a Arduino shield that uses TRIACs to switch four channels of AC power. The forum thread he started delves into several interesting discussions covering what it would take to convert this for use with 240v power and of course, a debate about safety.

A reader named [Victor] sent this tip to us and mentioned that this shield might significantly reduce the number of Arduino related projects we see. That’s because mixing high voltage alternating current with delicate 5v logic circuitry can be a bad idea. We’re not saying the creator of this didn’t know what he’s doing, but if you don’t you could fry up your Arduino, or your body.

Working with relays

relay

SparkFun’s latest tutorial shows you how to work with relays. A relay is an electrically operated switch. In this case, they’re using it to switch a 120V AC outlet. The article carries the standard warnings about how not to kill yourself with AC (plus some non sequitor linking throughout). As an extra precaution, they chose a GFI outlet. You probably know how a relay works, but it’s worth seeing how they implemented it. They use a transistor to prevent overloading the microcontroller’s GPIO pin. The control pin is pulled to ground to keep the relay off. A diode is placed across the relay coil to manage the power flow when it discharges. An indicator LED is included to show when the relay closes. This is a great foundation for an automation project, or maybe you just want to terrorize your cat.

Kill A Watt teardown

killawatt

Come on, folks. If we keep tearing apart everything that’s handed to us, we’ll never get nice things. SparkFun got their mitts on two Kill A Watts and proceeded to plug them into everything and then dismantled them to see how they work. The Kill A Watt keeps track of how much power is used over time. The largest load they found was their soda machine using 500W (should probably add a motion sensor to that). They plugged a meter on either side of a UPS and found out that it uses 5W just to charge. On the inside of the meter, there isn’t anything too substantial. One unlabeled IC runs the whole show.

Maker Faire 2008: Electric motorcycles


Builder [Justin Gray] brought a pair of electric motorcycles to Maker Faire last weekend. Pictured above is the R84, which has 28 LiFePo cells and an 84v AC induction drive providing 54HP. All of that is stuffed in a 2000 Yamaha R1 frame. You can buy it now for $14,000.

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