This Digital Measuring Wheel Helps Three Modes of Operation

The thought

In terms of measuring distances or the size of an object, most individuals attain for a tape measure or ruler. The primary issues with these instruments is that they’ve a finite distance that may be measured, placing objects longer than the tape or ruler out of attain. To fight this drawback, Albert Barber has created a mission he calls the Digital Measuring Wheel that goals to allow customers to measure issues as much as 100 meters lengthy, compared to the everyday tape measure with a restrict of round 7.6 meters.

Digital elements

To construct this, Bartber selected to make use of a rotary encoder that works by sending a coded pulse on every rotational step, giving each positional and velocity information to the related Arduino Professional Mini board. Displaying all the essential data to the consumer is dealt with by a 0.96″ OLED display screen, whereas a single 1S LiPo battery pack powers your complete system. Final of all, a pair of momentary push button switches enable for consumer enter.

Designing the wheel

One massive problem in designing the digital measuring wheel was determining tips on how to preserve accuracy whereas additionally stopping harm from occurring to any elements whereas in use. Barber got here up with a mechanism that depends on a single massive, spinning wheel embedded with a collection of 48 enamel. In the meantime, the stationary inner meeting comprises the PCB, electronics, and a secondary gear on the rotary encoder with a mere 8 enamel for a ratio of 1:6. The outer wheel is held in place by a set of 4 screws and glides simply over two rings of ball bearings that scale back friction.


After receiving his custom-designed PCB, Barber set to work on soldering all the elements onto the board, together with the Arduino Professional Mini, OLED display screen, rotary encoder, buttons, and the USB charging module. From right here, one finish of the wheel’s shell was hooked up together with a set of ball bearings. The PCB was then set in place together with the wheel and one other handful of ball bearings. Lastly, the highest shell was mixed with the rest of the meeting to finish this sandwich of 3D-printed components and electronics.

This system

A lot of the magic comes from the firmware Barber wrote for the Arduino Professional Mini. It configures the board’s interrupt pins to set off each time a sign is registered from the rotary encoder and both increments or decrements a counter, relying on the course of rotation. Then after a set period of time, this worth is learn and utilized in a easy calculation to find out both the space or pace of the outer wheel, as its diameter is understood upfront in addition to the gear ratio.

Measuring objects

To measure one thing, the consumer should first choose their desired mode by double-tapping the ‘Z’ button, whereas a single press resets the worth to zero. Switching between metric items and imperial items could be accomplished by urgent the button labeled ‘M’. Due to how inches are historically written in fractions moderately than decimals, the closest worth to 1/16″ is used to keep up readability whereas taking care to not scale back decision.

To see the Digital Measuring Wheel in motion, you may watch Barber’s video right here on YouTube or learn extra in regards to the mission on Instructables.

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