RazErblades

Formerly known as Deathblades, but that was too \m/etal.

Alright, alright. So I’ve finally caved into peer pressure and miniaturized the tech from RazEr’s motor even more such that they fit in a set of 100mm skate wheels.

Now, there have been many electric skate products in history. But they’ve all been either…

  • Unwieldy and large, such as having power units attached to the back of a conventional skate boot, or an right angle drive sticking out of the boot footprint, or even worse…
  • Cable (flexshaft) or shaft driven from a backpack or waistpack-like structure, which really seems like a bad idea in terms of ergonomics, and I can’t imagine as being very efficient.
  • Wire controlled, which brings with it risks of entanglement and tripping

Therefore, RazErblades are designed as an experiment to address those shortcomings which, in my opinion, have prevented motorized skates from emerging as a significant market (you know, besides the whole amplified risk of dying a bloody, cranially traumatic death).  The ‘blades have the following characteristics:

  • All-wheel drive with four hub motors, which are the most compact drive solution possible. The motors add minimal drivetrain drag to the system, so the skates can still be used normally. I contend this should always be available as a backup propulsion method for small electric vehicles.
  • 100% self-contained. All of the batteries and controls are contained within the skate body, and each skate frame is effectively a single-channel motor vehicle. No power is shared between the two units. There is of course then the downside of uneven battery life depending on which side of your body is dominant.
  • Controlled wirelessly via 2.4Ghz radio modules.  Not only does this keep the hands free to perform standard skating motions, but also allows for creative control methods. I’ve integrated the throttle into one of the wrist guards, which is equipped with force sensors to read applied forearm and wrist bending force. The wrist guards constrain physical movement, therefore making detection of force relatively easy.

The build log for the RazErBlades can be found in its (their?) category.


Specifications

(For one power unit; a complete set is, of course, two)

Vehicle Electric inline skate (Rollerblade Bravoblade GLX base)
Drivetrain 2 wheel direct drive
Mechanical 6061 aluminum skate frame, ABS and various plastics upper
Motor 2 100 watt custom BLDC hub motors
Controller Maxon 380200 DEC 50/5 BLDC control module
DIGI XBee 2.4Ghz 802.15.4 radio modules
Battery 2.6Ah 22.2 volt lithium polymer battery
Top Speed 10 to 15 MPH
Range 3 to 5 miles
Curb Weight 6 pounds (2.7kg)

Here’s a list of testing videos relevant to the project.

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