To celebrate the 200th anniversary of the draisine, computer scientists from Saarland University in Germany build a modern, electric powered derivative.
You might not realise it, but today’s a big date in cycling history. Back in 1817, exactly 200 years ago on June 12, German inventor Karl von Drais took his draisine, or “dandy horse” as it’s better known, for its first proper long spin – proving to the world that you didn’t need a horse to get around; two wheels work just fine, too. Little did anyone realise at the time, but the basic tech that would later evolve into the modern bicycle had been born. Today, the inventor’s legacy still lives on, but in a much more humbler form; namely those balance bikes most toddlers learn to ride on.
To celebrate this momentous occasion and honour the man who brought two wheels into existence, a team of computer scientists from Saarland University decided to build a modern version. Just like the original dandy horse, they constructed it entirely out of wood, but added a modern twist – kitting it out with an electric motor, sensors and a mini-computer to create a powered-assisted version. And, to pay homage to the draisine’s 200th anniversary, they decided to name their one-off creation “Draisine 200.0”.
You might be thinking this is just about a bunch of overqualified dudes who’ve come up with a great way to have some fun. But make no mistake, their project has a serious side. Professor Holger Hermanns and his team want to help the fast-growing electric bicycle industry avoid programming errors in the future when components from different manufacturers start getting “mixed and matched”. And the only way to get that right was for them to attempt something completely different.
Teaming up with Belgian bicycle engineer Dries Callebaut, they developed the Draisine 200.0 in just a few months. The hub of the rear wheel houses a 200-watt electric motor powered by a 750 gram battery. Two on-board sensors measure forward acceleration and the position of the rear wheel, which are in turn connected to a Raspberry Pi mini computer. And to keep everything looking authentic, all electronics is hidden neatly inside the modern dandy horse’s wooden frame.
Getting the motor to kick in with the right amount of power when you push with your legs wasn’t easy. “In the case of conventional electric bicycles, the engine is switched on when the pedals move, there is no such thing with a draisine,” explains Hermanns. “Accurately detecting when the rider pushes with his feet was a challenge that required fine-tuning of the controlling software. Imagine you’ve just bounced over a curb, the sensor system interprets this as pushing, and accelerates the electric motor to a top speed of 25 kilometres per hour.” To solve this, they mounted a camera on the frame in order to verify the correct interplay of human and electric driving forces via video. And, to make sure their video recordings synchronised with the sensor data, they had to develop a special light-emitting diode clock.
Currently, the Draisine 200.0’s motor doesn’t react to the rider’s first push because the speed’s too low. But the second push receives an impressive boost, allowing one to easily reach speeds up to 20km/h on flat terrain. In order to slow down, all the research team has to rely on is a simple foot brake. Now that Prof Hermanns and his team has ironed out the major bugs of their design, all they really need now is a nice long test drive. You know, just like the original. – (c) 2017 NavWorld
Source: Saarland University