You know you’ve got a good hardware platform if you can easily repurpose it with a code rewrite. And that’s what [Eric] continues to do with these little Hexbugs. This time around he’s bent the IR emitter and receiver downward to use as a reflectance sensor. This gives it the ability to follow a dark line on a light surface.
He originally patched an MSP430 into the $25 RC toy. The IR pair was intended for obstacle avoidance, which we saw in a recent links post. This hack does a great job of repurposing the avoidance system. Since the add-on hardware is mounted on a motorized turret, the single sensor pair can sweep back and forth to find the line it will follow. In one way this is better than most line followers which use multiple sensors mounted to the body. But the drawback is that this results in slower travel and won’t be winning any contests. Don’t miss the demo clip after the break.
Continue reading “Hexbug Code Rewrite Makes It A Walking Line-follower”
While they are not nearly as complex as their self-navigating brethren, building line following robots is no simple task, especially when they are this small. The creation of [Ondřej Staněk], this matchbox-sized line following robot is quite impressive.
PocketBot’s 48mm x 32mm circuit board also acts as its frame, supporting the wheels, motors, microcontroller and more. The brains of the operation is an ATmega8 microcontroller mounted on the bottom of the bot. A pair of wheels are driven independently using a set of mobile phone vibration motors that power the bot at speeds of up to 0.35 meters per second. Line detection is achieved by using three different IR sensors paired with four IR emitters located at the front end of the bot.
PocketBot also has an IR receiver on its top side, which allows [Ondřej] to control the robot, tweak its parameters, or calibrate its sensors on the fly using an IR remote or his computer.
The PocketBot might not be the absolute smallest line following bot we’ve seen, but it’s pretty darn close!
Continue reading to see PocketBot in action.
Continue reading “Matchbox-sized Line Following Robot”
[Eric Gregori] picked up this little yellow robot as a kit build. It has a single PCB inside that has a pair of IR emitters and detectors pointed downward at the front of the robot. It is able to follow a dark line on a light surface based on how the infrared beam reflects back to the detector. But it’s a one-trick pony that [Eric] wanted to make into a programmable robot.
The kit came with a schematic, which makes the process of patching into its logic quite easy. There are two motors, each with a driver circuit made up of a pair of transistors and one flyback diode. This means the motors can only move in one direction, but they also only take one logic connection to control. Instead of populating the transistor that usually connects the IR receiver to the motor driver, [Eric] soldered jumper wires from each to an MSP430 chip (the G2231 that came with his Launchpad).
As you can see in the clip after the break, the first version of the code he wrote makes the robot follow a line as it would if it had not been altered. But there’s still plenty of programming space and several free I/O pins for future improvements.
Continue reading “Making A Line-following Toy Into A Programmable Robot”
This line following tank uses analog circuitry to sense where a dark line is and adjust its course. Despite the opening paragraph on the schematic page (which looks to be leftover from a past project writeup) this circuit relies on a set of transistors for motor control. [Chris] does a great job of explaining the setup in detail; it boils down to a phototransistor detecting reflected light and flipping which motor is running based on what is detected. A couple of potentiometers are included to tune up the accuracy of the circuit. There’s a short clip of the treaded-terror making a loop around the track after the break.
This is another great way to try your hand at analog circuitry. Once you’ve built the body (tank or otherwise) and line tracking circuit it can be repurposed by swapping out the brains for your next project.
Continue reading “Line Following Tank Without A Microcontroller”
[Tim] sent in these quick little line following bots (translated). They were sent as participants in cosmobot, but due to an unfortunate dropbox mishap, they didn’t have updated firmware. They placed fifth and ninth place. As you can see in the video above, they are quite speedy. You can get the schematics and code on their project page (translated). They are hoping to make improvements to place better with the same bots next year.