Build a light following bristlebot as a way to teach science

light-following-bristlebot

[Ben Finio] designed this project as a way to get kids interested in learning about science and engineering. Is it bad that we just want to build one of our own? It’s a light following bristlebot which in itself is quite simple to build and understand. We think the platform has a lot of potential for leading to other things, like learning about microcontrollers and wireless modules to give it wireless control.

Right now it’s basically two bristlebots combined into one package. The screen capture seen above makes it hard to pick out the two toothbrush heads on either side of a battery pack. The chassis of the build is a blue mini-breadboard. The circuit that makes it follow light is the definition of simple. [Ben] uses two MOSFETs to control two vibration motors mounted on the rear corners of the chassis. The gate of each MOSFET is driven by a voltage divider which includes a photoresistor. When light on one is brighter than the other it causes the bot to turn towards to the brighter sensor. When viewing the project log above make sure to click on the tabs to see all of the available info.

This directional control seems quite good. We’ve also seen other versions which shift the weight of the bot to change direction.

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Steerable bristlebot via IR control

Looking at the size of this bristlebot the first thing we wondered is where’s the battery? All we know is that it’s a rechargeable NiMH and it must be hiding under that tiny circuit board. But [Naghi Sotoudeh] didn’t just build a mindless device that jiggles its way across a table. This vibrating robot is controllable with an infrared remote control. It uses an ATtiny45 microcontroller to monitor an IR receiver for user input. An RC5 compatible television remote control lets you send commands, driving the tiny form factor in more ways than we thought possible. Check out the video after the break to see how well the two vibrating motors work at propelling the device. They’re driven using a PWM signal with makes for better control, but it doesn’t look like there’s any protection circuitry which raises concern for the longevity of the uC.

This build was featured in a larger post over at Hizook which details the history of vibrating robots. It’s not technically a bristlebot since it doesn’t ride on top of a brush, but the concept is the same. You could give your miniature fabrication skills a try in order to replicate this, or you can build a much larger version that is also steerable.

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Bristlebot mod never rubs you the wrong way

controllable_bristlebot

[Underling] sent in his bristlebot project that aims to put a new spin on controlling bristlebot movement. We have seen several attempts at bristlebot directional control in the past, but none of these methods really fit what he wanted to do. His goal was to use a single brush rather than two, and be able to aim the bot in any direction at will.

He tried several different designs, but settled on what you see in the picture above. The large brush head is fitted with a vibrating motor on the front as well as a cell phone battery near the midsection.  These pieces are placed in the center plane of the brush as to not influence the direction of movement.  A separate servo-like motor is placed on the back of the brush, and each side of the motor’s arm is attached to a paddle that extends down the sides of the brush. When the motor is activated, one paddle is pressed in towards the bristles, while the other paddle is pulled away. This causes an immediate shift in direction, and should provide for a relatively tight turn radius. It should be noted that he also took the time to remove bristles from the center of the brush where the steering paddles are located in order to improve turning performance.

Unfortunately [Underling] does not currently have a video camera with which to show off his work, but we hope to see some action footage in the near future.

RC bristlebot shifts weight for steering

This large bristlebot has no prolem steering itself by shifting its weight. It’s easy enough to watch the video after the break and see how this works. But there’s still the same air of “I can’t believe that actually works” which we experienced with the original bristlebot.

This is not the first attempt to calm a bristlebots movements, but we don’t remember seeing one you could drive around like an RC car. [Glajten] up-sized the bot with what appears to be a small shop broom cut in half, creating a catamaran design. The vibrating motor, which might have come out of a gaming controller, rides on the back of the bot, centered between the two bristle platforms. On the front a servo motor holds the shaft of a long bolt which has extra weight at the end of it. Steering happens when the weight is offset by a turn of the servo.

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Controllable bristlebot

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[sprite_tm], whose projects we have covered in the past, took the popular bristlebot to an extreme and created a controllable version. A bristlebot consists of a small vibrating motor mounted with a battery on the head of a toothbrush. These micro-robots buzz around randomly, and he attempted to tame them. He used a platform of twin bristlebots and added an optical sensor from a laser mouse and an ATtiny13. The optical sensor is used to determine the relative motion of the robot, so that the motors can be adjusted accordingly. He also has a video of the bot using the sensor to find a mark on the floor and stay within bounds. Although it isn’t as accurate, it acts like a traditional line-following robot.

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[Lenore] Eviscerates Her Racing Snail

 

You may have walked past [Lenore's] unassuming card table at Maker Faire this year. But we’re really glad we stopped for a little chat. She went so far as to pull the working parts out of her racing snail to show them to us!

Wait, wait… racing snail? Yeah, this is a pretty neat one from a few years ago. The snail is a relatively large version of a bristlebot (incidentally, we believe bristlebots were originated by EMSL). The thing that’s missing here are the bristles. Instead of using a scrub-brush for this large version, [Lenore] discovered that velvet has a somewhat uni-directional grain. But using a piece of mouse-pad cut to the same footprint as the velvet she was able to get the flat-footed snail to move in a forward direction purely through the jiggle of a vibrating motor.

If this sparked your interest there are tons of other bristlebot variations to be found around here. One of our favorites is still this abomination which shifts weight to add steering.

Battery teardown to get at the cells inside

battery-teardown

Most of what people call batteries are actually cells. All of the common disposable alkaline batteries from AAA to D are single cells. The exception is the 9v battery which actually has six smaller cells inside of it. [Tom] took a look inside three different batteries to see what cells they’re hiding. Since he no longer uses the batteries for their intended purposes the individual cells may find a new life inside of one of his upcoming projects.

The six volt lantern battery on the left has four cells inside of it. This is no surprise since each zinc-carbon cell is rated for 1.5V. There’s not much that can be done with the internals since each cell is made of a carbon rod and zinc electrolyte ooze (rather than being sealed in their own packages).

Moving on to the rechargeable PP3 battery in the middle he finds the 8.4V unit is made up of seven 1.2V nickel-metal hydride cells. Many of them were shot, but we’d love to see one of the intact cells powering something small like a bristlebot.

The final component is an old laptop battery. Inside are an octet of Lithium Ion cells. The majority register 0V, but a few have 0.4V left on them. This is not surprising. We’ve seen power tool packs that have a few bad cells spoil the battery. It’s possible to resurrect a battery by combining good cells from two or more dead units.

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