Know Your Speed on Rollerblades

[Anurag] is a computer engineering student with a knack for rollerblading. Rollerblades are not a transportation device that are often fitted with speedometers, so [Anurag] took that more as a challenge and designed this Arduino-powered computer to give him more information on his rollerblade rides.

The device uses an Arduino as the brain, and counts wheel revolutions (along with doing a little bit of math) in order to calculate the speed of the rider. The only problem with using this method is that the wheels aren’t on the ground at all times, and slow down slightly¬†when the rider’s foot is off the ground. To make sure he gets accurate data, the Arduino uses an ultrasonic rangefinder to determine the distance to the ground and deduce when it should be taking speed measurements.

In addition to speed, the device can also calculate humidity and temperature, and could be configured to measure any number of things. It outputs its results to a small screen, but it could easily be upgraded with Bluetooth for easy data logging. If speed is truly your goal, you might want to have a look at these motorized rollerblades too.

17 thoughts on “Know Your Speed on Rollerblades

  1. I like it. Makes me think of Snow Crash for some reason.

    V2 should ditch the display and use addressable LED strips along the arms of your jacket that light up relative to speed. Maybe throw in a cheap ISM band RX/TX radio pair to clean up the wiring. Measure the delta of the speed to turn the strips all red to indicate that you’re stopping. Then add toe-controlled tact switches to flash the strips like a turn signal. Lots of fun to be had here.

  2. Rather than going for the ultrasound to detect if to measure speed, it may be easier to measure both skates (at least one foot is on the ground unless you’re doing lots of jumps) and then pick the highest speed of the two.

    1. Id say pick the average, im not at all home in the physics of rollerblading, but i would assume there are moments when the wheels spin up as you push off & then lift the rollerblade into the air, causing the wheels to spin faster (then the wheels of the other rollerblade on the ground) for a short period.

  3. A company used to make a skate speedometer. Lots of issues to sort out if you want to do it well.
    I had thought of working with a small processor block (long before the Arduino or Raspberry) but the first thing would have been to do some wheel spin speed charts for both skates to check for sweet parts of the cycles to use for measurement and allow for averaging strides when they are reasonably consistent. There is also the issue of recognizing gliding time and braking time that can really mess things up if the measurement wheel is on the skate with the brake.
    Another issue is recalibration as the wheel wears. One friend who used a wheel rev counter to log distance used to skate on a known distance occasionally to recalculate his conversion factor for his spread sheet.

    With new technology, I just use my hiking GPS.

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