Baby Quadruped Robot, Learning To Walk

Cheap Quadruped Robot

We’ve all seen videos of those crazy Boston Dynamics running quadruped robots that can reach up to 28 mph. Those things are amazing and it’s almost impossible to imagine how to even start building one. [Max] loves his robots and wanted to build a quadruped but, being a robot hobbyist, didn’t have the serious cash needed to make an extravagant robot like those of Boston Dynamics. Instead he started bridging the gap by designing a quadruped robot that is a little bit slower and tons cheaper.

quadruped-joint[Max] designed all of the mechanical parts himself. After weighing the advantages and disadvantages of different materials, he decided that the frame would be made from 5mm acrylic sheet. The main body of the robot has acrylic ribs that are spaced apart by threaded rods. Twelve RC servos make up all of the joints, 3 in each leg. Notice in this photo how there is one servo that immediately rotates another servo. To support the other side of the rotating servo, [Max] epoxied on a T-nut, stuck in a short length of threaded rod which is then supported in the frame by a ball bearing. Simple and effective! The upper portions of the legs are also made from acrylic sheet and the lower legs are from a cheap camera tripod. Rubber feet ensure a slip resistant stance.

All of the servos are controlled by an Arduino Mega. [Max] is currently writing a sketch that will perform the complex math and determine coordinated servo motions for movements us humans take for granted, like ‘walk forward’. As you can see in the videos, [Max's] robot won’t be catching the Boston Dynamics’ Cheetah any time soon but he is off to a great start.

Future plans for this project include bluetooth control and integrating the ultrasonic sensor proactively installed in the ‘head’ of the robot. Check out the videos after the break. [Max] is looking for some feedback on his project. We here at HaD think this needs a great name. Let’s hear some suggestions in the comments…

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Shocking Idea: Prank Stun Baton

Stun Baton

[Christopher] has put together a Prank Stun Baton to annoy his friends. It delivers a slight shock to the person on the business end of the device. Oddly, it’s powered solely by static electricity, there is no battery here and the resulting injury is no worse than touching a door knob after scooting your socks around on some shag carpet.

The design is super simple and is effectively just a rudimentary capacitor. The main housing is a PVC pipe that acts as a dielectric in the ‘cap’ system. Two separate pieces of tin foil are wrapped around the inside and outside of the PVC pipe. These layers of tin foil provide a conductive path up to the a couple of screws stuck in the end of the baton. A ping-pong ball and some foam act as an insulator between the PVC and the screws.

To charge the baton it only has to be brought close to a source of static electricity, a tube TV will do the trick. Rubbing it with a piece of wool will also work. When this is done an electrostatic field is stored in the PVC between the two pieces of tin foil, one side takes on a positive charge and the other a negative charge creating an electric potential between the two screws at the end of the baton. When something (with a low-enough resistance) shorts the screws, the stored energy on the positive screw tries to go to the negative screw, shocking the unsuspecting victim.

Need something a little more powerful? You may want to check out this other stun baton.

Robot Arm You Can Build At Home

DIY Robot Arm

[jjshortcut] has created an easy to make robot arm that has 6 degrees of freedom. There is not much to it, the frame is made out of 4mm thick hardboard, hobby servos provide the power and a handful of hardware holds it together. The frame has been successfully cut out on both a laser cutter and a cnc router, making this design even more obtainable for any aspiring roboticist.

To control the robot arms movements [jjshortcut] plans to use a standard Arduino. There are certainly plenty of servo motor shields available but he still decided to design his own. In addition to the standard motor power and servo connections, a header for an infrared receiver was added for potential future communication options.

DIY Robot Arm GripperLike any project, there were some hiccups along the way. First, several revisions of the gripper were necessary to get the correct tooth profile that resulted in smooth and tight movement. Also, while making the shield the spacing between banks of headers came out one header too close! On this first board [jjshortcut] just bent the pins so they would fit into the Arduino. You can’t let some minor snafu prevent forward momentum of a project!

[jjshortcut] has done the hard part; the design. He has made all his mechanical and electronic files available… so go and build one! Check out the video after the break.

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DIY Vacuum Former On The Cheap

DIY Vacuum Former

Vacuum Forming is a process used to mold plastic into a desired shape. A thin sheet of plastic is heated to a soft state and then air pressure is used to press the plastic down around or into a mold. Vacuum forming can be used to make a variety of items, anything from product packaging to bath tubs.

That being said, a vacuum former is probably one of those things that would be nice to have around but may not get a lot of use. Therefore, spending any significant amount of money on one would result in a low-value situation. For some folks, building one from scratch may be the way to go. [Amalgamized] built his own low-cost vacuum former and did a great job documenting the build.

VacuumDiagramFlattenedSmallThere is a two-pronged attack to keep the costs down on this project. First, the frame is made from readily available materials that you probably have kicking around in your wood scrap bin. The sides of the frame are 3/4″ plywood and the hole-filled top is made from 1/4″ MDF. A piece of PVC pipe connects the chamber below the top piece of MDF to a shopvac. The shopvac pulls the air down through the top’s holes; think reverse air hockey table.

Attack prong #2 is that there is no dedicated heater. Binder clips secure the plastic sheets to an aluminum window frame which are then put in the oven for a few minutes between 250 and 300ºF. When the plastic starts to droop, it is quickly removed from the oven and placed over a mold. The shopvac creates a low pressure zone under the plastic and atmospheric pressure pushes the plastic down around the mold.

DIY Vacuum Former

Electronic Dice Replaces Human Influence

ChipKIT Powered Electronic Dice

[Will] likes his board games but can’t seem to keep from loosing the dice. He’s been using a dice-rolling smartphone app for a while now and decided that it was time to make a dedicated microcontroller dice roller.

The brain behind the dice roller is a chipKIT uC32 microcontroller. Seven output pins are connected to 7 appropriately-arragned LEDs in the top of the dice. There is only one more electrical component, a momentary switch, that is used to re-roll. When the button is pushed, a random number between 1 and 6 is generated and then displayed via the LEDs in true dice fashion. [Will] wrote his own code for this project and makes it available for anyone to download. The case is 3D printed and was designed in Tinkercad, the files of which are also available. The chipKIT is attached to the 3D printed base by a pair of zUNO clips. Find a short video of this thing in action after the break….

Digging the randomness of the roll but miss the realness of the dice? Check out this real dice roller. Need two electronic dice? Check these.

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Homer Robot Ensures You Don’t Miss An Episode

Homer Smart Remote

With our busy lives, who has time to pay attention to TV show schedules? [Tamberg] certainly didn’t and that is why he came up with the web-enabled TV remove he calls the Smart Homer. This miraculous device knows when ‘The Simpsons’ is being broadcast, turns on the TV and switches to the appropriate channel.

Like the real Homer, not too much is going on up in this toy’s noggin. A couple of IR emitters are mounted in place of pupils and the associated wires are run down into his body. Right between a pink donut and a Krusty burger resides an Arduino and ethernet shield. This electronic duo acts as a web server and looks out to the ‘net for an online script. The script polls an online TV Program Guide and if ‘The Simpsons’ are on at that time, it sends a signal back to the Arduino to turn the TV on.

Homer Smart Remote   Jolly Homer

DIY Auto Fish Feeder Feeds Fish Automatically

DIY Auto Fish Feeder

[Brian] has a fairly large 400 liter aquarium and loves the fish that call it home. Unfortunately, sometimes life gets in the way of keeping those fish fed on a regular basis. There are automatic fish feeders out there on the market and [Brian] gave one a try. Although it worked, it dropped one huge clump of food in at a time (rather than sprinkling it in), the food hopper held a very small amount of food and the unit drained a new set of batteries in less than a week. Fifty euros were spent on purchasing that auto feeder and in the end it wasn’t any more convenient than just feeding the fish.

Faced with a tough decision on whether or not to buy another product he may not be happy with, [Brian] decided to make his own automatic fish feeder system out of parts anyone can find lying around the house. The main housing is a small Tupperware bin, inside of which 3 pieces of plastic were glued together to make a v-shaped hopper. The fish food is loaded into the hopper and as it falls to the bottom it meets a reverse-spinning drill bit that acts like an auger, pushing the food out of the container. The drill bit is powered by a small stepper motor connected to the drill bit by an improvised coupling made from a silicone sealant cap!

The control system is an Arduino and a stepper motor driver chip. Through trial and error [Brian] figured out that 100,000 half steps of the motor dumped a good amount of food into the tank. The drill bit delivery method even sprinkles the food nicely for total fish enjoyment. To keep the food flowing at regular intervals, an AC timer unit controls how often the Arduino is powered on and subsequently feeds the fish.

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