[Achu Wilson] was watching TV when he saw an ad for Volkswagen’s latest Passat, which happens to come equipped with a park assist mode. This essentially allows the car to park itself with little to no user interaction. While these systems come as a pricey add-on option, he figured he could build something similar in his own home, albeit on a much smaller scale.

Digging through his parts bin he only came across a single infrared proximity sensor, so instead of building vehicle that could parallel park, he settled on constructing one that can situate itself in a traditional parking spot instead. The car is built from wood and a pair of DC motors [Achu] had on hand, both of which are controlled using an ATmega16.

As a proof of concept, it looks to work pretty well despite the fact that it only has a single fixed sensor navigate its surroundings. We imagine it would be a relatively easy task to adapt the system for parallel parking, among other things.

Continue reading to see [Achu's] self-parking car in action.

Finally [Michelle Annett] can talk about her super secret project she did at Autodesk Research.

Medusa, as [Michelle]‘s project is called, is a Microsoft Surface that has been fitted with 138 proximity sensors. This allows the Surface to sense users walking up to it, and detect users hands and arms above the table top. Multiple users can be detected at the same time, and the left and right hands of two users can be mapped to specific users.

The proximity sensors [Michelle] used are inexpensive, so we’re wondering when someone with a crazy multitouch setup will add proximity sensors to their build. We’d like to play with Medusa, even if just for a virtual game of Settlers of Catan. It seems like the perfect setup…

[Michelle] built Medusa last January during her internship at Autodesk. Now that UIST 2011 is over, she can finally talk about it. There’s also a video demonstrating the possibilities of Medusa, check it out after the break.

Thanks [Fraser] for sending this one in.

[Johannes] sent in the latest iteration of an ongoing project – Nimbus, the wall-follwing robot. Originally operating on a cardboard frame, the robot has undergone several revisions as you can see by reading through his blog. Nimbus started out as a simple, Arduino-powered robot, but the project has progressed nicely over time. The last revision simply avoided walls, using a Sharp IR proximity sensor to detect, then avoid obstacles. The most recent model sports a nice polycarbonate frame as well as two additional IR proximity sensors, allowing Nimbus to navigate quite well, following walls and avoiding obstacles with ease. It does get caught up from time to time on carpets and wires, but overall Nimbus is a great little robot. [Johannes] even added a small RGB status LED for the bottom of the bot, communicating its navigation status to the operator at all times. This is done by flashing various colors when objects have been discovered or have moved out of sight – it’s a really novel addition.

Keep reading for a video of Nimbus navigating his way around, and don’t forget to check out the Nimbus photo stream.

The GP2Y0D02 is an infrared proximity sensor with a detection field that extends 80cm. This type of sensor can be used to build collision avoidance systems for robots. We’ll demonstrate this sensor using a single resistor and a multimeter.

Sharp GP2Y0D02 fixed 80cm IR proximity detector (Digikey #425-2064-ND, $14.38). Datasheet (PDF).

The GP2Y0D02 requires a 5volt power supply (not shown). A 0.1uF bypass capacitor between power and ground (C1) is a good idea, but we didn’t use it in our demonstration. The open collector output (pin 1) pulls to ground when no object is detected, a 12K pull-up resistor (R1) holds the signal high when an object is detected.

In the demonstration we connected the output of the sensor to a multimeter. When nothing is in front of the sensor, the detector holds the output low (0.40volts). When we put a PCB in front of the sensor, the output changes to high-impedance and the pull-up resistor (R1) holds the signal high (5volts).

Why open collector?

An open collector output doesn’t toggle between high and ground, it toggles between ground and unconnected. The unconnected state, also called high impedance, exerts nothing on the output and allows the signal line to float. This is an undefined state for most microcontrollers that returns rapidly varying values, so we use a resistor (R1) to hold the signal high. The open collector output overcomes the small amount of current flowing through resistor to register the low state. Without this resistor, the output will never reach a proper high state.

Open collector outputs are useful when several sensors need to share the same microcontroller pin. Multiple sensors outputting high to the same microcontroller pin is generally considered a bad practice that can damage parts of a circuit. Multiple open collector outputs, however, can only switch to ground; a single resistor holds the signal high. In the case of multiple GP2Y0D02s, the signal will be high only when all connected sensors detect an object and switch to high impedance state.

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