This electric turtle bot instructable describes a fairly simple turtle-style robot meant to be laser cut out of acrylic (although other materials such as aluminum, MDF, or polycarbonate should work just as well). This frame is also optionally for sale, which should appeal to those that would like a mechanical robotics platform to play with, but don’t have access to machine tools. The build instructions include a detailed bill of materials which should come in handy.

As displayed in the video after the break, the robot uses a sonar sensor to navigate. This sensor is set up on a servo in order to scan the terrain, and, depending on how it’s programmed, hopefully avoid obstacles. As of when the video was taken, the little robot appears to sense an obstacle then scan with the servo left and right to see what the best way to turn is.

If this little turtle robot doesn’t have enough power for your taste, check out this autonomous ATV sentry.

[ESylin] built an autonomous rover that roams the vacant halls of his school. On the hood of the vehicle he’s mounted two Maxbotix sonar sensors that do a great job of keeping the vehicle centered in the hallway. It will follow a wall around a corner (favoring its left side because of the left-facing sensor) and it will stop to correct itself if it gets off course. That’s because when you’re not driving a dsPIC33 is, with a Traxxas XL-5 speed controller and a hobby servo for steering. But this little guy hasn’t lost all his pep. Manual control and be switched on from from an R/C controller so you can burn up the floor tiles. Take a look at the demo after the break, with the manual control demo shown at about 4:10.

The Intelligent Ground Vehicle Competition (IGVC) is the precursor to the DARPA Grand Challenge, and in many ways it is just as difficult. We have the pleasure of being at the competition this year with the Tennessee Technological University Autonomous Robotics Team. The teams at the competition pull off some amazing home-brew robotics, so we’ve decided to do a short section on some exemplary robotic hacking each day of the competition.

Today’s robot comes from the York College of Pennsylvania. The robot, dubbed “Green Lightning”, features an impressive set of custom made hardware.

We interviewed the team, and got a pretty thorough rundown of their robot with pictures after the jump.

The spinal cord of the robot is this custom built beauty.

It consists of six layers, each with a specific function. The boards were designed by the team and fabricated by Sunstone Circuits.  Each layer except for the top has its own teensy++ unit, programmed in C, providing an SPI interface to the hardware it’s designed to connect to. The first layer has an Arduino Mega programmed in C on it. The layers communicate with the Mega through an SPI bus running at 500Kbaud. The Mega processes the information and then communicates to a computer through a 1Mbaud usb serial connection.

The remaining five layers are each designed to interface with a specific section of the robot’s hardware. The second layer communicates with a Wheel Commander from Nubotics, simplifying the robot’s motion controls.The third layer  is the interface to the robot’s emergency stop. The rules require that there be a visible hardware e-stop on the back of the robot and a wireless remote e-stop. They solved their wireless e-stop problem with a zig-bee module that connects to the robot through this layer.

The fourth, fifth, and sixth layers all connect to the robot’s sensor groups. The fourth layer is the interface to their gps, mounted at the top of the robot. Most gps units communicate with simple serial and it’s pretty elegant that they managed to save a usb port by adding a board. The robot has nine Sharp 2Y0A710 distance sensors acting as a short-range bumper for obstacle avoidance which all connect to the fifth layer. The final layer is the interface for 10 long range sonar sensors located at compass points around the robot.

The robot also has two USB Web Cams for line and object detection mounted on the mast.  The AI and computer side hardware interface is programmed in a mix of C and Java. The AI follows a reactive model instead of a mapping/planning one which has been proven to be very effective in this competition for many teams.

The frame, track, and drive train were custom built by the team as well.

Here you can see the back of the robot where the drive train, Wheel Commander, and two SaberTooth motor drivers are.

A side shot shows their track system. They modeled it in SolidWorks first and then fabricated everything including the belt in house.

In the end the robot cost them around $5,200 after discounts which is pretty impressive considering its capabilities and that some of the robots at this competition easily break $50,000 dollars. It’s a prime example of what good engineering and home-brew magic can accomplish. We’ll finish with a shot of their manual control system.

We ask, who wouldn’t want a rotating motion and distance tracking radar? Sure in today’s day and age anyone could purchase a wide-angle sonar or IR solution that achieves the same goal, but [LuckyLarry] took it old school and made his own rotating radar. He used an Arduino, servo, and ultrasonic sensor as a base to gather data, and the open source programming language Processing to draw the data on the screen. He says it’s a little inaccurate currently, but will try out some other sensors in the future.

Reader [Joshua] sent in his latest project. using a sonar rangefinder, an Arduino, and some clever programming, he’s made is computer react to his distance from it. As you can see in the video after the jump, he has programmed it to change text size and background color depending on his distance from the screen. While he admits that his implementation doesn’t seem immediately useful, there’s lots of potential  there. We can actually think of several uses. What would you use it for?

[Lynne] had this crazy idea to build a piece of clothing that would give you feedback about your surroundings using sonar. She started with a carefully selected thrift store jacket. She wanted something that looked good and also provided plenty of places to hide electronics. She used the LilyPad system, with a vibration pad and a sonar range finder. When the system detects an object within a certain distance directly in front of the wearer, it warns them with some vibration. Not only is it practical, it looks pretty cool too. Did we mention she designs clothing?

She notes, in the comments section, that while it can detect an obstacle, it cannot detect a void. How could she detect a drop in the floor or a step down?

The simple bat detector uses frequency division to lower the bat’s chirping to a frequency we can hear. For example, if a bat is calling at 91kHz the system will divide it by 16 and put out 5.7kHz. The system is digital, so all amplitude is lost. You’ll just hear clicks like a Geiger counter. Being digital has its advantages though. Unlike similar analog devices that have to be tuned to a small frequency range, the simple bat detector can detect a much wider window.

[Tony] has supplied step by step directions on how to assemble the simple bat detector, along with plans for two different models. He not only encourages people to build there own, but seems to really enjoy seeing their work. He’s posted several images of other people’s builds (pictured above) on his site.

[suneth] has taken this idea in a slightly different direction with his Ultrasonic Batgoggles. Built for a school project in Arts, Media, and Engineering, they actually block your vision so you can try to use echolocation to navigate. You don’t hear the echoes, the processor deciphers that for you. You hear a beep that varies in speed based on the distance you are from an object. On the plus side, you will look totally awesome wandering around trying not to bash your nose on stuff.

[via only hacks]