Sunday, March 30, 2008

Robot dogs or real dogs? You Decide


Dogs have lived among humans for millennia. In the ruins of northern Israel, the remains of a man estimated to be 12,000 years old were discovered with the left hand resting on the skull of a 4-to 5-month old puppy. All over the world among ancient human ruins, we find the remains of dogs.


Among the 4,000 species of mammals & 10,000 species of birds, humans have only been successful in taming about 10.


The most successful was the dog. Dogs drive livestock, find hunting prey, pull sleighs, search for survivors & guard homes.


Nowadays they play a big role as pets, because as a friend & family member dogs show unswerving loyalty & love.Nonetheless, a challenger to the dog has suddenly surfaced: robots.



Research has proven that in relieving the loneliness of old people, real dogs & robot dogs are nearly equally effective.


These findings by researchers at Saint Louis University in St. Louis, Missouri were published in the latest Journal of the American Medical Directors Association.


They had a real pooch called Sparky & a Sony robotic dog named AIBO play with 38 nursing home residents for eight weeks.


It took the old folks a week longer to warm up to AIBO than Sparky, but in the end they came to pet & talk to both real & robotic dogs equally.


According to survey results, the people felt about the same level of emotional bonding & relief from loneliness with each type of dog.


AIBO is the first robotic dog that emulates a real dog`s behavior. Sony began to sell it in 1999 at $2,000 apiece, recording 11,000 units in total sales. The company stopped producing it in 2006.


But there are rumors that a new model with the ability to identify its owner will be on the market soon. If artificial intelligence continues to develop at this rate, robot dogs will be able to do the same things as real dogs. Further, there will no misunderstandings, hypocrisy or betrayals, only loyalty.


Still, if you can buy these qualities any time you want, then it can`t be the real thing.


One of the best playwrights of the 20th century, Eugene O Neill, wrote about the pain of watching his pet dog`s death in an essay titled The Last Will & Testament of an Extremely Distinguished Dog. The dog`s will says, There is nothing of value I have to bequeath except my love & my faith . Whenever you visit my grave, say to yourselves ..Here lies one who loved us & whom we loved.No matter how deep my sleep I shall hear you.



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Unique LEGO USB DRIVES (check em)

Well right about now we have seen just about all variants that a USB Drive could come in, but none before scream prolificness such as these Japanese USB flash drives. Want to store some confidential files? This new line is actually compatible with standard Lego bricks, which means build a mock Lego set, add your trusty lego USB Drive too the mix, and consider it concealed forever. Now the only apparent con would be its limited 1GB of capacity, but surely bigger storage versions are sure to come. The official product page is right here


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Friday, March 21, 2008

BUILDING ROBOTS : Mousey robot finishing steps












A mechanical computer mouse has an ingenious way of translating the movement of a mouse's rubber ball into X- & Y-coordinate movement on your screen. Inside the mouse are two encoder wheels .As you move the mouse around on the desk, it rotates these wheels inside (one wheel being perpendicular to the other, with their drive shafts in contact with the ball). The encoder wheels have slits in them, & on either side of these slits are infrared emitters & infrared detectors. The detectors count the number of light pulses reaching them (through the moving slits in the encoder wheels) from the emitters, & then the on-board chip translates these pulses into X/Y coordinates that it sends to your computer screen On most mice, the emitters are clear plastic with a little dome protruding from them while the detectors are solid black. Find the clear emitters & desolder them from the PCB. You're now the proud possessor of a pair of robot eyeballs


Now Breadboarding the Robot`s Circuit


Creating Eyestalks



  • Before we start hooking up the wiring on our breadboard, we need to give our Mousey eyes some optic nerves. Our computer mouse IR emitters only have two stubby little pins coming out of their packages. Our robot is going to have eyestalks that jut from the front of its body. These will not only look cool, but we can use them to adjust Mousey's sensitivity to light by moving the stalks backward & forward & from side to side.

  • To create the stalks, cut four 6 1/2-inch pieces of 22-guage solid core hook-up wire. If you have red & black wire, cut two of each color. Solid core wire is better here than stranded wire because it'll give you much stiffer stalks that will hold the shapes you mold them into as you adjust light sensitivity.

  • Now we're going to do something strange. We're going to reverse our red & black wires. We're going to solder the red wire to the cathode (–) pins on the emitters & the black wires to the anode (+) pins. This is called reversed biasing in electronics. It's a technique that will help improve our light sensitivity even more.

  • When the wires are soldered in place, twist them together & strip some of the jacket off of the other ends (to fit into the tie points of your breadboard). The stalks are so tall because they're going to stick out of the mouse about 4 inches when installed in our actual robot, & the negative wires will need to reach our control chip in the bottom of the mouse

Hooking Up the Op Amp



  • With all of your electronic components in hand, you're ready to breadboard the circuit. Here are the steps to installing the op amp, our main control circuit

  • 1)The first thing you'll need to do is install the LM386 across the trench on your board. As always with ICs, the pin to the immediate left of the little dimple (as you hold the chip up so that the dimple is on "top" of the chip) is Pin 1. Count in a "U" shape down the left side (in this case, Pins 1–4), across the IC, & then up (Pins 5–8).

  • 2)Now you'll want to connect Pins 1 & 8 with a piece of hook-up wire. These two pins were designed (with the IC wearing its original op amp hat) as gain controllers. By connecting them together, we're boosting the gain (in other words, increasing the sensitivity of the signals coming from our computer mouse's IR emitters).

  • 3)The next components to connect are the eyestalks. Take a black wire from one of the stalks & put it in a tie-point group for Pin 2 & the other black wire in a tie point for Pin 3. Pins 2 & 3 are the op amp's input pins. Now take the two red wires for the stalks & plug both of them into the same tie-point group someplace above the 386 chip (about five to six tie-point groups above the chip). They're on their way to the upper positive power bus, but we're going to add some additional electronics before we get there.

  • 4)We found in our experiments using the IR emitters from mice that they're not as sensitive to light as they could be. In Junkbots, Bugbots, & Bots on Wheels, Dave Hrynkiw includes a sensitivity-boosting subcircuit that BEAM uber-hacker Wilf Rigter (wilf.solarbotics.net) came up with for Herbie-based bots. We decided to add these components, which are nothing more than an LED & a 1kW resistor. Adding this booster on the breadboard simply involves plugging the negative (cathode) lead of an LED into the same 5-point group on the board where you have the two red leads for the eyes plugged in, & then jumping the trench & plugging the positive LED lead into the corresponding 5-point group on the other side of the trench. In that same 5-point group, plug in one lead from your 1kW resistor & then plug the remaining lead into the positive tie point of your upper power bus.

  • 5)Now to finish up this part of our circuit, all we have to do is connect the power pin of the LM386 (Pin 6) to our upper positive power bus, & the ground (Pin 4) to the lower negative bus.

Connecting the Motors & Power


After you've checked all of the preceding steps to make sure that all components have been properly installed on the board, you're ready to connect the motors & power



  • 1>Connect the positive wire from one motor to Pin 5 of the LM386 chip. On many motors, the positive terminal is marked in some way, often with a dimple or with a plus sign (+). Our Solarbotics RM1 motors have silver dimples next to the positive terminals. (Er...& they have a red wire attached to the positive terminal & a black wire attached to the negative terminal. That's always a solid clue.) Connect the negative motor wire from this first motor to Pin 4 on the relay.

  • 2>Connect the negative wire from the other motor to Pin 5 of the LM386 chip. Then connect the positive wire to Pin 13 on the relay. (Notice that the polarities are reversed from step 1.)

  • 3>Everything should be hooked up by now & we should be ready to power our circuit. Because the robot itself will use a 9V battery, that's the power you should deliver to the board. You can use the 9V battery snap you bought for this project

 


Freeforming Mousey's Control Circuit


Now that we have a light-hungry robot brain, we need to install it in our mouse body so that it can motor around to feed (add your own zombie/Night of the Living Dead sound effects here). Obviously, all of the hook-ups will be the same as on the breadboard, but here we'll want to switch to a lighter-gauge &/or a stranded wire. The 22-guage solid core wire used in most breadboard jumper kits is too stiff for most of the connections we'll need to make inside of our mouse case. It makes it too hard to close the lid & puts unwanted stress on our solder joins. Either try a stranded 22-guage wire or a 24-guage (stranded or solid) wire. We used a 22-guage stranded wired


 


Installing the Battery & Relay


1>Using two-way tape, Velcro tape, or poster putty, install the battery where you want it to go.


2>Before you install the relay, you might as well solder what you can to it while it's still outside of the mouse case.


3>Solder the emitter pin of your NPN transistor (that's the right-most pin looking at the transistor with the flat side facing you) to the top-left coil pin on the relay


4>There are a few more relay hook-ups we can do "out of body." First, solder a short positive (red) wire from the top pin on the right side of the relay to the bottom pin on the right side.


5>Now you're ready to glue the relay in place & solder its remaining connections.


6>Solder the negative wire from the left motor onto the middle pin on the left side. Again, use black wire if you have it. Then solder the negative wire from the right motor onto the right middle pin on the relay


Before we move away from the relay/switch/motor area, we have a few more things we need to do.


Solder about 2 inches of positive wire to each of the positive motor terminals (if the motor doesn't have wires already).


Solder the stripped ends of these two wires together side-by-side.


Finally, solder a third positive wire, about 3 inches long, onto the soldered end of the two motor wires you created in steps 1 & 2 . What we're doing here is making the two positive motor wires into one positive wire that we'll attach to the output pin on our control chip.


Installing Our LM386 Control Chip


Find the spot in your mouse case where you decided to install the LM386. You'll want to position it in dead bug mode (with its pins in the air). It doesn't matter how the chip is oriented. Ours has pins 1 & 8 facing towards the robot's rear.


Before you glue in your chip, go ahead & bend Pins 1 & 8 toward each other & solder them together.


2>Glue your LM386 IC in place.


3>Now find the negative wires from the transistor (attached in step 3 of "Installing the Battery & Relay"), the relay (attached in step 4 of "Installing the Battery & Relay"), & the timer cap (attached in step 1 of "Connecting the Switch Components"). Solder all of these negative wires together, side by side. Here we're joining all of the negative wires together on their way to the control circuit & to power.


4>Solder the negative wire from the battery snap onto the 3-wire negative junction you joined previously in step 3.


5>Solder a short piece of negative wire (about 1 inch) to Pin 4 of the 386. Then solder this wire to the uber-negative wire junction created in steps 3 & 4.


6>Solder the positive wire from the relay (attached in step 4 of "Installing the Battery & Relay") to Pin 6 on the chip (our output pin). Solder the motor junction wire to Pin 5 on the IC.


Installing the Eyestalks


As you install the eyestalks, following the steps listed here, refer to Figure 8.18 for some visual cues.


The first thing we want to do is make holes in our mouse top to thread the eyestalks through. The two buttons on most computer mice are separate pieces of plastic that snap onto the mouse's top half & rock a little forward & backward (so that they can engage the actual switches on the PCB underneath). You'll probably want to glue these two pieces onto the rest of the top so that you have a solid upper half. When the glue is dry, mark where you want to sink your eyestalk holes, & drill out just enough of a hole (using your Dremel tool & a drill bit) to feed your eyestalk wires through. We installed our eyestalks about 1/2 inch from the front edge of the mouse case.


Thread the eyestalks through the holes so that about 1 3/4 inches of wire & sensor remains outside of the case. On the inside, clip the two positive wires so that they just reach each other on the underside of the top & overlap each other a bit. Solder them together.


Run the negative wires along the top of the case & bend them down wherever your IC is located (ours is in the back of the mouse's bottom half). Don't solder them to the IC just yet. We want to keep the two mouse halves unconnected until the end.


Cut a short piece of red wire (about 1 inch) & strip the ends. On one end, solder on the 1kW resistor of our sensitivity booster subcircuit. On the other end of the resistor, solder on the anode side of the LED (with its leads splayed out). We want this wire/resistor/LED combo to fit from the middle pole of our toggle switch to the junction of the two positive eyestalk wires we soldered together previously in step 2.


Go ahead & connect the sensitivity booster from the middle switch pole to the positive solder join of the eyestalk wires.


Our LED/resistor combo is really only in our circuit to add a voltage bias, or in other words, to tweak the sensor output voltage so that it's more in line with what the chip's input is expecting. This will result in the motors turning on & off more gracefully, leading to smoother mouse motion. One cool side benefit to the booster is that it can double as a "power-on" indicator, so we want it showing through the top of the mouse case. Consequently, we're going to have to drill a hole in the top for the dome of the LED to poke through. With the booster circuit in place, you can see where that should be. Gently bend the LED out of the way (so that you don't drill into the top of it!) & sink your hole. Then poke the light up through it. Use a piece of electrical tape to hold the LED in place inside the hole you just cut.


Make the FINAL ROBOT CONNECTIONS


We almost got bot! All we have to do now is make the final connections between power, the switch, & the control chip, & to install our front whisker.


Solder the negative eyestalk wires to Pins 2 & 3 on the LM386.


Solder the positive (red) wire from the battery snap to the (normally open) outside pole of the toggle switch.


Solder a short red wire (about 1 inch) from the center pole of the switch to Pin 6 of the IC.


Connect your bumper plastic to the bumper switch. We simply used a couple of layers of cellophane tape. You want to install it so that it's connected to the left side of the switch front, so that it crosses over the face of the switch & across the little cylinder that's the switch button itself



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Making a Robot : Building the Body (Mousey bot)




For our mousebot, we used an old Kensington Mouse-in-a-Box Scroll model. It's big enough to fit all of our robot components inside of it.Making sure there's enough room in the case is something you're going to have to be certain of before you unholster your Dremel tool & start unhooking your mouse. Unscrew the mouse case & eyeball the placement of all of the robot parts. The main thing you need to be certain of is that the 9V battery & the two DC motors fit inside the case for our robot.


You should be able to unhook the mouse cable (from its plug-type connector), pop out the scroll wheel (if it has one), & then pry out the PCB. Set all of these parts aside while you work on the mouse case itself.


After all above parts removed, what you should have left is the plastic mounts for the two encoder wheels (which are used to translate movement of the mouse ball to cursor movement on your screen), mounts for the scroll wheel , & the screw post(s) (which attaches the case top to the bottom). Using your Dremel tool (& a cut-off wheel), remove every thing but not the screw post



After you have the bottom part of the mouse body cleared out, flip over the top of the mouse case & have a look. It too is likely to have a lot of plastic structure you don't need. Zip all of it off with the Dremel


Robot Motor & Switch Placement


Then we have to make sure that you install your motors perpendicular to the centerline of the body so that the bot can move in a straight line.



  • After we figured out where the battery will sit, & where the motors for robot should be installed, you're ready to cut the openings for the motors.

  • You then keep cutting & test fitting your motors until they can rest comfortably in the case with the lid closed. We will use the drive shafts/gears of the motor themselves as our wheels. To do this, we need to angle the motors coming out of the mouse body so that they're at about a 60-degree angle.


  • After you're confident you have the right motor placement, you can use superglue (or epoxy, if you prefer) to glue your motors in place

  • The next thing we need to do is to make an opening in the case bottom for our bump switch. Our mousebot is going to have one giant "whisker" across its front that, when bumped, triggers its mousey, scuttle-away behavior. We'll actually use one of the tiny switches found in our computer mouse for this bump switch. All you need to do is find one of the button switches on the mouse's PCB & desolder it

  • The last mechanical item we need to attend to in the bottom half of the body is putting tires on the motors. This simply involves getting a rubber band the same width as the sprockets on the drive shafts, measuring out the necessary lengths (by wrapping a piece of the band around the sprocket, marking it, & cutting it), & then gluing the tires in place.


Installing our Robot`s Control Switch



Most switches come with two nuts on the bushing. You simply take one nut off, stick the bushing through the hole you've made in the top, & then tighten down the second nut on the outside of the case to attach your switch




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Making a Robot : The Parts List (Mousey bot)



Mousey the Junkbot requires the following parts



  • (2) light sensors (taken from mouse)

  • (1) SP/ST toggle switch (Solarbotics Part #SWT2)

  • (1) junked computer mouse (or new el cheapo one)

  • (2) small DC motors (highly recommended: Solarbotics Part #RM1)

  • (1) double-pole/double-throw (DP/DT) 5V relay (Solarbotics Part #RE1)

  • (1) LM386 audio operational amplifier (Solarbotics Part #LM386)

  • (1) SP/ST touch switch (taken from mouse)

  • (1) 9V battery snap

  • (1) 9V battery

  • (1) 2N3904 or PN2222 NPN-type transistor (Solarbotics Part #TR3904/TR2222)

  • (1) 1kW 20kW resistor

  • (1) 1kW resistor

  • (1) 10mF to 100mF electrolytic capacitor

  • (1) Light-Emitting Diode (LED)

  • (2) spools of 22- to 24-guage stranded hook-up wire (one black, one red)

  • (4) 6 1/2-inch pieces of 22-guage solid hook-up wire (two red, two black)

  • (1) wide rubber band (or flexible LEGO tubing)

  • (1) small piece of scrap plastic (about 1/4 inch x 2 1/2 inch)

  • (1) small piece of Velcro or two-way tape (optional)

The Essential robot Tools & Supplies List


To construct Mousey robot, you'll need these tools:



  • Rotary (Dremel) tool (required)

  • Cut-off wheel for Dremel tool (a piercing or jeweler's saw works well too)

  • Needlenose pliers

  • Screwdriver set

  • Soldering iron & related soldering tools & supplies

  • Breadboard & hook-up wire

  • Superglue

  • Hobby knife

  • Wire cutters

 


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Building robots : 5 Essential Supplies



Before Building Robots you'll also need to lay in a few supplies...


Solder— Solder can be called the "glue" which holds our digital robotic world together. It's a conductive metal alloy (mostly a combination of tin and lead or tin and silver) combined with a compound called flux. Solder melts under quite low temperatures (120–400 deg) and quickly cools to form a strong, durable bond between electrical components and whatever metal surface they've been soldered to (each other, a circuit board's metallic "pads," wires, and so forth). The flux in solder is a special material used to help "prepare" the metal surfaces for bonding with the solder. Solder comes in different forms, but solder wire is what you'll be using when building robots . It usually comes in spools.


Superglue— Cyanoacrylate, mercifully more widely referred to as superglue, is an extremely strong and quick-setting bonding agent.


Flux paste— The paste, sold in little jars, when smeared onto the stubborn areas, will prepare the way for a good solder robot joint.


Wire— You'll want to have spools of wire on hand for use when breadboarding robotic circuits, hooking up motors, & other robot`s wiring jobs.


Two-part epoxy— Two-part epoxy resin is a quick-setting resin that bonds metal, glass, plastic, wood, fiberglass, & other materials.


 



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Wednesday, March 19, 2008

BUILDING ROBOTS: Professional electronic Tools



Specialty tools that will make building robots a little bit smoother


Parts picker-upper— This gizmo is sometimes called a three-claw parts holder, but I've always called it a parts picker-upper ('cause that's what it does). Electronic and robot parts are often small, and inevitably, they fall into crevices and other hard-to-reach places. The parts picker-upper is a pen-sized device that has a plunger on one end of it. Press it, and three little metal claws come out of the other end and allow you to reach and grab onto your lost robotic part. It's a little robot end effector!


Miter box and hacksaw— A miter box is a cutting jig that allows you to accurately cut wood, plastics, and metal at precise angles (45 degrees left, 90 degrees, 45 degrees right, and so forth). If you're going to be doing any bot construction where precision angles are required, a miter box is a necessity.


Heat gun or micro-torch— In all of our robot-building projects, we'll be using an awesome material called heat-shrink tubing. This is a plastic material that shrinks when you apply heat to it. It's a perfect way of adding back the type of insulating wire jacket that you use wire strippers to remove. It's also a great way of adding traction to robo-critter wire legs and bump-sensing "whiskers." The heat to shrink the tubing can't effectively be supplied by most household hair dryers.


Bench vise— For bending parts, whacking parts, and holding parts in place while you work on them, nothing beats a bench vise. You can get an all-purpose one at your local hardware or home store for about $20–$30.


Magnifying glass (or magnifying lamp)— Trying to read the parts information on electronic components can be maddening. I find having a magnifying glass close by can be very helpful. If you really want to go all out, you can get a swivel-arm lamp with a magnifying lens built into it. Having one of these on your desk can be a great help when soldering robot circuits


Rotary tool— For multipurpose tools, nothing beats a rotary multitool (more commonly known by the brand name Dremel). This device serves as a drill, cutter, sander, buffer, grinder, and numerous other tools. Dremels come in several sizes. I don't recommend the cordless Mini-Mite. It is underpowered for many applications. Full-size Dremels, such as the 9.6-volt (V) MultiPro, have a speed dial with variable RPMs (revolutions per minute), making them versatile for different types of applications. The regular Dremels also have nifty accessories available (such as a drill press and a router attachment).


 



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BUILDING ROBOTS: essential tools to make life easy




You can build most of the commercial robot kits with nothing more than the tools just discussed. The following tools, however, will make your robot building easier & more enjoyable


Digital multimeter (DMM)— A digital multimeter is an indispensable piece of electronic test equipment. As the name implies, it is designed to test ("meter") a number of different electronic components & events. Learning to use one of these gadgets can be a lifesaver when trying to figure out whether or not a component is dead


Third hand— It won't take you long while soldering electronics to realize you don't have enough hands available to hold the iron or need a robot arm!!!, the spool of the solder, & the components you are joining. You can only employ a parent, spouse, or child so many times before they'll mutiny. The answer is a device called a third hand (also sometimes called a helping hand). It sits on a sturdy base & has a number of adjustable "arms" with "alligator clips" on the ends. Some also have a magnifying glass, which can be helpful in the robot building process.


Metal file set— Inevitably, builders need to shave material here & there to make parts fit. The easiest & neatest way to do this is with a file set. You can get a cheap set for under $10.


Heat sink— A heat sink is a device that shunts heat away from an electronic component. Your computer has one or more heat sinks inside of it to keep damaging heat away from your processor & other components. In electronics, a heat sink tool is a little aluminum clip that you attach to components (on the component lead between the component & where you're soldering) to keep them relatively cool while you solder.


Battery recharger— Because most robots live on battery power (as does most every other portable electronics device in our lives), buying disposable batteries can get very expensive.


Hot glue gun— God bless this tool. A hot glue gun can quickly "weld" just about anything to just about anything else. Sticks of glue are fed into the gun, heated, & squeezed out the other end.



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BUILDING ROBOTS: essential toolkit to make your first robot




Must-Have Tools When Building a First robot


You shouldn't even think about building the robots without having the following tools in your work area.Making your First Robot Can be a daunting task & these tools will make ur life easier.


Small screwdriver set— Most small robots use both flat-head & Phillips-head machine screws in their construction. The screwdrivers you likely have in your home toolkit will probably be too large. You'll want to get yourself a set of precision screwdrivers (also sometimes called fine or electronics screwdrivers). You can get a set for only a few dollars


Needlenose pliers— This type of pliers is a godsend for any type of electronics work. The nose tapers to nearly a point, allowing you to get it into tight spaces. Needlenose pliers are also great for twisting wire pairs together & bending electronic component leads.


Diagonal cutters— Diagonal cutters have a cutting head that's curved. This enables you to get the pliers tight against a printed circuit board (PCB) to cleanly snip off the component leads of electronic parts (after you've soldered the components to the PCB).


Wire cutters/strippers— This nifty tool is for cutting the plastic insulating jackets off of wires without cutting into the wire itself. Along its jaws is a series of teeth marked with the gauge sizes of common wire. To strip off the jacket, you just put the wire inside the appropriate tooth for your wire gauge, press down, & pull the plastic jacket away from the wire. The tool also has a cutting blade for slicing wires, some crimping teeth (for attaching connectors to wires), & usually, blades for shearing off common bolt sizes.


Iron stand with sponge— This gizmo looks like a big steel spring mounted to a base. When you're not using the soldering iron, you holster it in the stand for safekeeping. The sponge in the tray at the base of the stand is used for cleaning the crud off of your iron. A clean iron tip is critical to properly melting the solder. The sponge is always kept moist while you're working.


Soldering iron— For "welding" all of the electronic components & wires on your robots, you're going to need a soldering iron. The iron is used on a material called solder, an alloy (usually tin & lead) that melts at a relatively low temperature, & is used to join electrical components. You can get a soldering iron for under $10, but if you think you might have a future in electronics & robot building, spend a little bit more & get a decent one.


Desoldering pump— Even master solderers mess up once in awhile. &, truth be told, soldering is not an instantaneous skill to master not while building robots.


Breadboard— A breadboard is a cool gizmo used for making robots that lets you test out your electronic circuits to see if everything is working properly before you submit your components to the soldering iron.


Jumper kit— A jumper kit is an essential accessory for your breadboard. It's basically a collection of prestripped wires in different lengths & colors that are sized for use on a breadboard.


Besides the preceding tools, you'll also want to have obvious items, such as regular household pliers, an adjustable wrench, marking pens (Sharpies are best), scissors, a metal ruler, electrical tape, & a hobby Knife Before You start building your first robot



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Saturday, March 15, 2008

Ubercool Tachikoma Robot Gets Unboxed



AkihabaraNews, reports of a Bandia’s metal “Ghost In The Shell” Tachikoma desktop USB robot which is able to read your e-mail, create/process applications and even allows for mini games. Tachikoma robot can be plugged into any USB port and will react in numerous ways (eyes, lights, and speaker) due to included companion software with this cool robot. Its available right now from GeekStuff4U for just about 133.00€ (or 205 USD). Check out the video of the robot for a closer look.


VIDEO


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Newest ThinkGeek’s Video Players Incredibly Small



These cool new video players are roughly the size of a credit card, and offer full video play back on their on their itty bitty screens.Both video players go for $99.99, theres a black (Neon M3) version with heat-sensitive back-lit buttons and a 2.4-inch screen, and a stainless (ICE) model with a relatively larger “2.8-inches” screen.


Additional features of these video players include an FM tuner, MicroSD capable, 2GB of memory, photo viewer and a “game” mode. They can also play videos for 3 to 4 hours on a charge, while audio only mode will give you 6 to 8 hours, check out the official product page…



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USB Mixtape (cool retro usb drive )


The nostalgia from this USB drive is undeniable. Let’s be real, I think everyone born before 85 had at least one. Even I experimented with the tapes, as a matter of fact the very first Hip-Hop album I purchased was on tape, Too Short’s ‘Gettin It’, but enough of the reminisce and back to the drive. It has a puny capacity of 64 MB, which might fit an entire album and it is packaged neatly in a gift box designed to look like an authentic mix tape, complete with blank label tabs and all. Unfortunately that the long and short of if, it has a cool factor so it gets an honorable mention but that’s where the props stop. You can catch it at design house SUCK UK


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Vstone’s “Black Ox” Robot ( a robot bully!!!)


Vstone’s recently unveiled “Black Ox” Robot, he stands a at 1.5 feet and has 20 movable parts, but wait till you see what this mean Robot is made of.In the video after the break watch him ice grill, chunk em’, and stomp his invisible foes out. Stay tuned for official release date and price.

Tagline for this Robot



Are you an asshole, tyrant, and a bully? Have you been searching for the perfect companion to your desk that shares your temperament? Well look no further then….!! any comments on this unique robot bully?


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Real Transformer ROBOTS production started!!!



Real transformers (Large robots) are now currently under construction. British scientists have just announced that today they will be taking the first steps in this astonishing cool robotics(but completely irrelevent) project. The £4.6million (roughly $9 million USD) experiment will attempt to build swarms of tiny robots, each the size of a sugar cube, that navigate around on their own and connect together to form larger, intelligent machines. Researchers say the first swarm of autonomous, intelligent, shape-changing robots could be in use within just five year.


Now they have also disclosed that the transformers robots will used for medicine, in space exploration and for search and rescue missions using robots, but we know better then that don’t we ? Prepare to be surveilled by arbitrary Robots laying about, sorta like that commercial for the Samsung u700



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Friday, March 14, 2008

FRICTION concepts in Automation


Friction
Calculating friction is often a black art. There are many situations which are hard to factor in such as surface tension, humidity, etc. But there are several sure ways to find a reasonable value to help you build your robot. The first thing you should look at is what is called the coefficient of friction. This is a dimensionless property which can be looked up for any two materials. What does this number mean? Well suppose you are standing on ice with rubber shoes and you want to calculate the pushing force required to slide across the ice.

force of friction = weight * u.rubber-ice

Just multiple the force being applied perpendicular to the contacting materials (your weight) and multiply that by the coefficient of friction of ice against rubber. This would be the force required to counter friction to slide across the ice.

Understanding friction is also useful when designing robot pincers. If the friction is miscalculated, your robot victims would be able to escape! Now we cant have that . . . So here is how you do it. A robot pincer squeezes from both sides. So this is your force. The typical human however wants to fall down out of your robot pincers by gravity.

Now all you need to do is squeeze hard enough so that the force of friction is greater than the force of gravity.

force_squeeze * u.pincer-human_neck > human_weight

You probably won't find a reliable coefficient of friction for robot pincers rubbing up against a human neck, but using higher friction pincer material will help.

Actually, finding the coefficient of friction can be a little more complicated. There are actually two coeffiecients. It turns out that friction is related to the rubbing velocity of the materials. Ever notice how it is easier to push a heavy object across the ground after it is already moving?

The static coefficient of friction is when the materials are stationary.
The kinetic coefficient of friction is when the materials are already in motion against each other. What makes it a black art is that there is never any exact clear boundary between the two values.

Here is a quick coefficient of friction lookup reference of some common materials you may use:

Material 1
Aluminum
Aluminum
Plexiglass
Plexiglass
Polystyrene
Polystyrene
Polythene
Rubber
Rubber
Rubber
Rubber
Teflon
Teflon
Wood
Wood
Wood
Wood
Wood
Wood
Material 2
Aluminum
Steel
Plexiglass
Steel
Polystyrene
Steel
Steel
Asphalt (dry)
Asphalt (wet)
Concrete (dry)
Concrete (wet)
Steel
Teflon
Wood (clean)
Wood (wet)
Metals (clean)
Metals (wet)
Brick
Concrete
Static
1.05 - 1.35
0.61
0.8
0.4 - 0.5
0.5
0.3 - 0.35
0.2
0.5 - 0.8
0.25 - 0.75
0.6 - 0.85
0.45 - 0.75
0.04
0.04
0.25 - 0.5
0.2
0.2 - 0.6
0.2
0.6
0.62
Kinetic
1.4
0.47
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-


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Safety factors in robotic automation

Safety Factor

If you are unsure of various perhaps uncalculatable factors, always add what is called a factor of safety. For example, suppose you guess a beer can weighs between 1 to 2 pounds. A factor of safety would say, 'design the system to handle 2.5 pounds, just in case.'

So what should your factor be? Guess. I would recommend 1.2, but its really up to you. What does this number mean? Suppose your calculations say you need a motor rated at least 100Nm, then multiple that by 1.2 to get 120Nm as your minimum motor force. The factor of safety is not an exact science, obviously. If you expect to have high fatigue from shock or overuse, high friction, or bending, make the factor of safety higher.

So why not make my safety factor really high? Well, you can, but motors with higher torques are also more expensive Thicker robot materials can cost you more too. So why not a small safety factor? Well, if friction is much higher in your robot than you expected, your robot just won't work very well.

There is a more scientific method to the safety factor, called statistical analysis. This involves building then actually testing your robot part under various circumstances until it breaks. Then statistically (through a histogram) you can determine the optimal properties so it will NEVER break. However this involves building and breaking a part many times - too much effort for a single robot. This method is common for car and cell phone manufacturers. Did you know they statistically determine how many times you can drop a cell phone at any particular angle to make it user proof?


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ROBOTIC pulley automation concepts

Pulleys

Calculating pulley forces is very simple. A pulley is a simple moment arm. The force being applied on the rope multiplied by the pulley radius is the torque being applied. But now notice that there are two forces countering each other. This is like two opposite moments, so you would subtract them. Remember, don't be confused by the device itself. Even if the pulley were square, the calculation would still be exactly the same. Can you see the moment arm in this example?



Moment = Torque = Force_A * Pulley_Radius - Force_B * Pulley_Radius

or Torque = Pulley_Radius * (Force_A - Force_B)

You should also note Force C, the force required to hold the pulley up.
Force C is always Force_A + Force_B + pulley_weight.


Crowbar - Mechanical Advantage Moment Balancing
Another example of a moment would be a crow bar. What you have is a beam, a pivot point in the center, and a weight on each end. Now suppose you have two exact same weights. Now move one of those weights real close to the pivot point. What will happen? The weight that did not move would go down. Although the force remained the same, the distance decreased, therefore resulting in a smaller moment.

Although this example looks very different from the rest, it is actually exactly the same.

Both sides of the crowbar create a moment about the pivot point (the triangle tip). So your equation is this:

Moment Side A = Moment Side B

Force_A * Length_2 = Force_B * Length_1

Now if you knew any three variables out of the four, you can use simple algebra to calculate the fourth one.

For example, suppose this was a see-saw at a childrens' playground. Now you have a 40 pound child sitting on one end, and you plan to catapult him into the next playground. Now this child is sitting exactly 4 feet from the pivot point. Your plan is to jump on it with your weight of 200 pounds. What is the closest distance to the pivot point you can stand on the see-saw and still lift the child into the air?

filling in the equation:
40 lbs * 4 ft = 200 lbs * distance

solving:
40 * 4 / 200 = distance = .8 feet



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ROBOT Automation-Moment Arms concept


ROBOTIC concepts on Moment Arms
Moment arms will probably be the most useful for you. The basic equation is moment equals force times the distance of the beam the force is being applied perpendicularly at.

Moment = Force * distance

Here is the first example. What you see is an object of some length. It is fixed rigidly at one end. And the other has some force being applied to it. This force can be something hanging on it, something pushing it, a hammer hitting it, a gear moving it, gravity/weight, etc. Does not really matter.


All you do is measure the distance and multiply that by the force that is being applied. You should always know the expected force being applied to your robot, or you are taking a risk of buying an actuator that is too weak or too big and strong. If the robot is lifting a beer can, know the weight of the can. If the robot is climbing, know the estimated weight of the robot. Even rudimentary calculations can help you better understand the force requirements of your robot.
Now suppose your robot is lifting a beer with an arm. A moment about the shoulder is being created by both the weight of the can, but also the weight of the robot arm itself. How do you calculate this? You would add the moments created by each together.

Moment = can_weight * arm_length + arm_weight * 1/2 * arm_length

Notice that for the arm length we only use half the value. Why? Because weight is distributed throughout the entire arm. Theoretically all you are doing is adding up all of the force across the arm, and applying it to the center of mass of the robot arm. The center of mass is the exact point where an object can be perfectly balanced. I estimated the center of mass to be the midpoint (1/2 length) of your robot arm. However it may not be. You can easily find the center of mass of any object by balancing it on your finger and then measuring that distance with a ruler.

Now suppose you have calculated the moment. What do you do with this number?
This is actually the torque being applied. So when you look for a motor to power the shoulder of your robot, just reference this calculated value as your minimum required torque.

The concept of the moment arm can be applied for many different situations. Sometimes the moment arm can be hidden


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Introduction to ROBOTIC concepts,Statics

Introduction to ROBOTIC Mechanical Engineering Theory, Statics
Want to optimize your Robot parameters mathematically? Want to verify that an expensive motor you are about to purchase has enough torque? This is a math tutorial for robot chassis construction. This tutorial is useful if you would like to mathematically either prove your robot will work, or optimize it so that it would work better. Better yet, I have one of those degree thingies in Mechanical Engineering so this tutorial should be extra useful . . .

My approach will be talking about the most common calculation uses of mechanical forces for robots. I will offer specific application examples, the theory, equations, and some pretty graphs to help you understand.


Theory: Statics
Statics is concerned about how a mechanical system would act if everything is perfectly motionless and rigid. It is the most fundamental of all calculations, and mathematically is no more complicated then highschool algebra. All you need to understand is how to build an equation from the mechanical parts you use.

Remember in elementary you learned (or should have learned) that for every force there is an equal & opposite force? For example, if I were to stand straight, then push you forcefully, I would end up forcefully pushing myself back at an equal amount. If you push a wall, the wall is pushing you back. Why is this important? Easy. If an object weighs 10 pounds, your actuator needs to be able to lift at least 10 pounds. This sounds numbingly simple, right?

Now suppose you add in friction of joints, efficiency rates, multiple actuators, & unevenly distributed weight across an oddly shaped object. Obviously the problem can balloon to something quite complex. This is what I will talk about, all directly relating to robotics & in simplified form.



Friction
Calculating friction is often a black art. There are many situations which are hard to factor in such as surface tension, humidity, etc. But there are several sure ways to find a reasonable value to help you build your robot. The first thing you should look at is what is called the coefficient of friction. This is a dimensionless property which can be looked up for any two materials. What does this number mean? Well suppose you are standing on ice with rubber shoes and you want to calculate the pushing force required to slide across the ice.

force of friction = weight * u.rubber-ice

Just multiple the force being applied perpendicular to the contacting materials (your weight) and multiply that by the coefficient of friction of ice against rubber. This would be the force required to counter friction to slide across the ice.

Understanding friction is also useful when designing robot pincers. If the friction is miscalculated, your robot victims would be able to escape! Now we cant have that . . . So here is how you do it. A robot pincer squeezes from both sides. So this is your force. The typical human however wants to fall down out of your robot pincers by gravity.

Now all you need to do is squeeze hard enough so that the force of friction is greater than the force of gravity.

force_squeeze * u.pincer-human_neck > human_weight

You probably won't find a reliable coefficient of friction for robot pincers rubbing up against a human neck, but using higher friction pincer material will help.

Actually, finding the coefficient of friction can be a little more complicated. There are actually two coeffiecients. It turns out that friction is related to the rubbing velocity of the materials. Ever notice how it is easier to push a heavy object across the ground after it is already moving?

The static coefficient of friction is when the materials are stationary.
The kinetic coefficient of friction is when the materials are already in motion against each other. What makes it a black art is that there is never any exact clear boundary between the two values.

Here is a quick coefficient of friction lookup reference of some common materials you may use:

Material 1
Aluminum
Aluminum
Plexiglass
Plexiglass
Polystyrene
Polystyrene
Polythene
Rubber
Rubber
Rubber
Rubber
Teflon
Teflon
Wood
Wood
Wood
Wood
Wood
Wood
Material 2
Aluminum
Steel
Plexiglass
Steel
Polystyrene
Steel
Steel
Asphalt (dry)
Asphalt (wet)
Concrete (dry)
Concrete (wet)
Steel
Teflon
Wood (clean)
Wood (wet)
Metals (clean)
Metals (wet)
Brick
Concrete
Static
1.05 - 1.35
0.61
0.8
0.4 - 0.5
0.5
0.3 - 0.35
0.2
0.5 - 0.8
0.25 - 0.75
0.6 - 0.85
0.45 - 0.75
0.04
0.04
0.25 - 0.5
0.2
0.2 - 0.6
0.2
0.6
0.62
Kinetic
1.4
0.47
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-


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Build GRID Solving Robot tutorial


GRID solving Robot is useful for various robotics competitions. Here we have built a basic Grid solving robot using the iBOT by using 5 line sensors as shown in the image. The basic principle used for grid following is detecting the intersection and taking a turn accordingly. Here we have programmed the Robot for moving in a diagonal way from one end of the grid to another. As shown in the figure the five sensors connected of which the center one is for following the line and the sensors on the immediate left and right of the center sensor are for keeping the robot on the straight path. The extreme left and right sensors of robot are used for junction detection.


Here when a junction is detected robot takes a single wheel turn, thus aligning the robot on to the right angled path. Since we want the robot to travel diagonally we have programmed it to take alternate right and left turns at the junctions. A small amount of delay is included after each turn of robot to prevent false input to be taken by robot while turning. On experimenting with a lower speed (45rpm) motor the robot was more prone to such false signals and was not taking proper turns. Also the time taken for the robot to align back to the straight line was more because of which the robot missed to detect junction at some occasions. To avoid such situations while using low rpm motors the size of the Grid should be increased.

Here we have used 100rpm motors, which suited ideally for our program. Motors with higher rpm may cause problem as the junction can be missed due to speed.

The sensors are connected as shown.

The GRID Arena is as shown. The size of each block is 10 inch x 10 inch.


We also experimented with various other combinations for sensor placements. The external left and right sensors can be aligned in the same line as the wheel. in such a case we need to take a differential turn. The placement of other three sensors will remain the same. The placement of the external sensors should be as shown below



PROGRAM FOR GRID FOLLOWER for Robot USING iBOT

/* Center sensor is connected at P1_4

Right sensor is connected at P1_1

Left sensor is connected at P1_2

Extreme Right sensor is connected at P1_0

Extreme Left sensor is connected at P1_3

Left Motor connected at P2_0 and P2_1

Right Motor connected at P2_2 and P2_3*/

___________________________________________________________________

#include

#include

#define ert P1_0

#define rt P1_1

#define lt P1_2

#define elt P1_3

#define cnt P1_4

#define fwd 0×0A

#define rev 0×05

#define lft 0×08

#define rht 0×02

void main()

{

int i=0;

P1=0xFF; //intialize P1 as input port

P2=0X00; //intialize P2 as output port

while(1)

{

if (cnt==0 && rt==1 && lt==1 && elt==1 && ert==1)

/*if center sensor is on black line and other sensors on white area*/

{

P2=fwd;

}

if (rt==0 && lt==1 && elt==1 && ert==1)

/*if right sensor is on black line and other sensors on white area continue to turn right till the center sensor is on black line*/

{

while(cnt==1)

{

P2=rht;

}

}

if (rt==1 && lt==0 && elt==1 && ert==1)

/*if left sensor is on black line and other sensors on white area continue to turn left till the center sensor is on black line*/

{

while(cnt==1)

{

P2=lft;

}

}

if (rt==0 && lt==0 && elt==0 && ert==1&& cnt==0)

/*if all other sensors except for extreme right sensor are on black line (i.e if the Bot is not aligned) align the iBOT such that all sensors come on black line ( i.e. move the Bot left)*/

{

while(ert==1)

{

P2=lft;

}

}

if (rt==0 && lt==0 && elt==1 && ert==0 && cnt==0)

/*if all other sensors except for extreme left sensor are on black line (i.e if the Bot is not aligned) align the iBOT such that all sensors come on black line ( i.e. move the Bot right)*/

{

while(elt==1)

{

P2=rht;

}

}

if (rt==0 && lt==0 && elt==0 && ert==0 && cnt==0)

/*if all sensors are on black i.e a junction is reached

increment a variable ‘i’ too determine the turning direction*/

{

i++;

/*if ‘i’ is even turn left until center sensor senses black line and other sensors sense white background*/

if (i%2==0)

{

if (elt==1 && ert==1 && cnt==0 && rt==1 && lt==1)

{

P2=fwd;

}

else

{

P2=lft;

DELAY(500);

}

}

if (i%2!=0)

/*if ‘i’ is odd turn right until center sensor senses black line and other sensors sense white background*/

{

if (elt==1 && ert==1 && cnt==0 && rt==1 && lt==1)

{

P2=fwd;

}

else

{

P2=rht;

DELAY(500);

}

}

}

}

}


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Stepper motors Tutorial (figures) 2

To increase the precision we can employ a sequence as shown which is known as half stepping. In this before we de-energize the first coil we energize the second coil. So the rotor finds itself being pulled by two forces and it settles in between the two positions


A B A` B`
1 0 0 0
1 0 0 1
0 0 0 1
0 0 1 1
0 0 1 0
0 1 1 0
0 1 0 0
1 1 0 0

For bipolar motors we need to reverse the direction of the current flowing through the coil. So we apply the following sequence.

A B A` B`
0 0 1 1
0 1 1 0
1 1 0 0
1 0 0 1

Similar to unipolar we can also apply the half stepping sequence
Bipolar v/s Unipolar

Unipolar
Simple driving circuit because no current reversal
Size comparatively larger for same specification as bipolar

Bipolar
Smaller size
Higher torque
Complex driving circuit because current has to be reversed.

Drivers for stepper motors:
For unipolar motors we can use darlington pair array ICs like the ULN200x series since we don’t have to reverse the current.


But for bipolar motors we need to use an h-bridge which can source as well as sink current.


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Stepper motors tutorial (figures) 1


The most common problem we face when we use normal DC motors is that we don’t have precise control over how much it rotates. To rotate DC motors through a particular number of degrees what we can do is either calibrate it for a delay based operation i.e. if I switch it on for n seconds it moves 360 degrees; or what we can do is attach n encoder to the shaft which gives us a feedback on how much the motor shaft has rotated so that we can stop it when it rotates through the desired angle. Home made encoders give good results but don’t have such a high resolution and high resolution encoders are costly.

In such cases where we need to control the rotary position of the motor we can use stepper motors. Stepper motors have a tendency to make beginners feel uncomfortable about using them. But lets hope this air of discomfort about using stepper motors disappears once we are done through this article.

Stepper motors are motors available in round, square, rectangular shapes with 4 or more wires coming out of them.As the names suggests a stepper rotates in steps of a particular degree. As compared to DC motors which have continuous movement steppers actually rotate in specified degree of steps. There are steppers available from 0.9 degree step to 6 degrees.

Like all motors stepper motors also have a stator and a rotor. Based on the type of stepper construction the stepper can be of the following types, permanent magnet, variable reluctance and hybrid. As hobbyists and robotics enthusiasts we would limit our discussion to the permanent magnet type because that’s the type that’s easily and cheaply available. Depending upon the arrangement of coils in the stepper motor they can be classified as unipolar or bipolar. Usually the easily or more commonly available stepper motors are the unipolar ones with 5-6 wires. The bipolar has 4 wires.

Well I guess we are now ready to take a look at how Stepper motors actually work.

In the permanent magnet stepper motor the rotor is a permanent magnet and the stator is a set of coils which are energized one after another. In the unipolar motors the direction of current in the coil doesn’t reverse (so UNI) while in the bipolar the current through the coil flows in both the directions (so BI).
In both types of stepper motors there are two coils wound on the stator poles, which gives us 4 wires. The difference is that in unipolar motors there is a center tap from each of the coil winding. These center taps are either brought out individually (which will give us 4+2 = 6 wires) or are shorted together and brought out (which gives us 4+1 = 5 wires)

To rotate a stepper motor we need to energize the coils of the stepper in a specific sequence.
Let’s take a look at unipolar stepper motors first. The first step is to connect the common terminals to the supply voltage. Then we ground the coils in the sequence as shown. This sequence is called as wave drive.

A B A` B`
1 0 0 0
0 0 0 1
0 0 1 0
0 1 0 0

Note:
Usually the steppers motors available in the market are ex-stock i.e. pulled out from old printers, floppy drives, etc. and since there is no standard color code for representing the coils of the motors, how do we identify the terminals??
For this we use the most useful and versatile tool in electronics, the multimeter. Keep checking the resistances in between pairs of wires till u determine which is A A`, B B`. (when you try to check the resistance between A and B the meter will go out of range. Resistance between A and A` will be in the range of few ohms to a couple of hundred ohms. ...
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