How One Builder Made an Arduino Tortoise Bot Seven Times Bigger and Kept It Fully Operational

Arduino projects often involve small robots that roll forward and steer clear of walls using basic sensors. Maker UncleStem decided to push that familiar idea into uncharted territory by enlarging every part of a classic turtle-style design by a factor of seven. He had just wrapped up work on a matching seven-times-larger Arduino Uno board and wanted a project that could put the oversized microcontroller through its paces. A tortoise bot offered the perfect match because the original small version already relies on straightforward code and simple hardware.

Construction began with motors sourced from children’s ride-on toys. Anyone who has experimented with ordinary turtle bots knows that those tiny hobby motors can’t keep up; twenty-four-volt ones from children’s ride-ons, on the other hand, provide a lot more power. UncleStem devised a brilliant solution: bespoke shells that slide perfectly over the motors, giving the overall appearance of a scaled-up version of the originals. The laser-cut plywood required special attention, so UncleStem hired a professional to make the cuts on a large sheet of 1mm thick acrylic. Any workshop cutter would have been unable to handle such large materials.

The wheels, which came straight from the lawn equipment supplier, are actually very smooth beneath the robot’s heavy chassis. Three-dimensionally printed hubcaps round off the look, keeping the enormous concept consistent across all visible components. Control is centered on a gigantic Arduino Uno designed by UncleStem. A regular old Arduino Nano is stashed away inside the main board to conduct all of the real processing and code execution. The gigantic jumper wires were made of metal rods because there are no commercial versions available at this scale.

The motor driver board is essentially a larger L298N setup, but it’s mounted on a three-layer plywood board and powered by a 300 watt driver capable of handling big motors. There is also a small voltage regulator that reduces the power to 5 volts for the Nano. Sensors required the same level of attention, as the ultrasonic distance module is disguised behind a dummy outer shell to maintain detection range while the robot appears to have been scaled up (parked in its own small printed housing that looks just like the mini-part). Navigation works exactly like the usual turtle bot formula. The robot just continues straight ahead until it collides with something in front of it, at which point it stops and swings the sensor left, center, and right to find the widest open path before turning in that direction and continuing.
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