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University of Adelaide's EDWARD Electric Dicycle

Posted: June 25th, 2011 | Author: | Filed under: Blip, Eco Driver, electric, Grilled, Michael Courtenay, On Two Wheels | Tags: , , , , , , | Comments Off on University of Adelaide's EDWARD Electric Dicycle

Meet Edward, with a top speed of 40kmh / 25 mph is a futuristic, purely electric dicycle. Designed by Honor students – Ben S. Cazzolato, Chris Dyer, Kane Fulton, Jonathon Harvey, Evan Schumann, Charles Zhu, Luke Charles Francou, Jack Scott Parsons, Benjamin John Wright, Bo Zhu, Jonathon R. Atterton, Ben L. Davis, Samuel C. Hart and Erin E. Pearce – at the University of Adelaide, Australia, Edward is an advanced program in good looking mechanical design. Although it looks like some dystopian vehicle ridden by Gaff in Bladerunner, Edward is a fully operational electric, human operated dicyclele.

EDWARD is an acronym – Electric Diwheel With Active Rotation Damping. A diwheel or dicycle is similar to a monowheel, in which the rider’s seat is located inside the wheel. However, in the case of EDWARD, there are two axially aligned wheels instead of one, and the seat is located between them. Mechanical Engineering students have been working on the project since 2009, and it now seems to be close to completion – the designers have achieved quite a high level of controllability and stability.

This honours project involved the construction of a human operated diwheel. Many diwheels in the past have been human powered or powered by IC engines. This one is purely electric. It has additional functionality lacking in other models, including inbuilt dynamic lateral stability and slosh control to prevent “gerbiling” or tumbling in aggressive braking or acceleration maneuvers. The diwheel also incorporates a unique feature that allows the rider to drive the vehicle when “upside down” – keeping the vehicle in its unstable state is achieved using a combined swingup and inversion controller. The mechanical design and some of the electronics was completed in 2009, with the majority of the electronics and control systems developed in 2010.

One might think that such a diwheel design could make it hard to keep the rider’s seat level, especially when using the brakes or accelerating (the so-called “gerbiling” effect, in which the rider rocks like a gerbil in an exercise wheel). However, due to “in-built lateral stability and slosh control,” EDWARD allows riders to move in any direction, while their seat stays in a fixed position. The control system calculates and sets the best level of the seat after each movement. While regular upright riding is entirely possible, users can also ride the vehicle upside-down, should they wish. Controlling an inverted ride is made possible through the use of a combined swing-up and inversion controller. The vehicle is driven via a joystick, and there’s also a touchscreen-based control panel. The rider’s safety is achieved through a five-point racing harness, that keeps them from falling out.

  • Top Speed: 40km/hr. This is limited by the drive ratio of the motor and drive wheels. It is possible to change this ratio to increase the maximum speed, but this would be at the expense of the rapid acceleration and maneuverability.
  • Maximum Incline: 12 degrees. This is simply a function of the mass of the wheels and inner frame, and their mass distribution. It should be noted that EDWARD was designed to have a high centre of gravity to make it susceptible to slosh and tumbling. This high c. of g. has limited the maximum incline that can be climbed (without forward momentum) to a relatively gentle gradient.
  • Braking Deceleration: 0.2G. This is also a function of the mass of the wheels and inner frame, and their mass distribution. The high c. of g. in EDWARD has restricted the maximum acceleration/deceleration to be about 1/4 what a bike or car can achieve on a dry sealed road surface, and more like a lose unsealed road. Again, it is conceivable, using alloy wheels and frame, and intentionally keeping weight low, to realise a design with a deceleration of 0.7G, which is not much lower than most vehicles.
  • Battery Life: 1hr. We typically get about 1hr from the existing sealed lead acid batteries. This would involve a fairly aggressive driving style involving rapid turns and spins, tumbles and acceleration/deceleration. It is likely that a more sensible driving regime with slosh control on would provide several times more time before swapping the battery pack.

 

 

Dicycle aka diwheel is a vehicle with two wheels side by side, unlike the usual motorcycles and bicycles, which have a wheel followed by another, called tandem placed wheels.

The diwheel design has the two large outer wheels completely encompassing an inner frame. The inner frame is free to rotate within the wheels, and is typically supported by a common axle or idlers which roll on the wheels (see figure). Diwheels, like their more popular cousins the monowheel, have been around for almost one and a half centuries. All of these platforms suffer from two common issues affecting driver comfort; slosh and tumbling (also known as gerbilling). Sloshing is when the inner frame oscillates, and it occurs in all monowheels and diwheels where the centre of gravity of the inner frame is offset from the centre line of the wheels. It is very prevalent as these platforms typically have low damping between the wheel and the frame, to minimise power consumption during locomotion. In addition, during severe braking or acceleration the inner frame will tumble relative to the earth centred frame, which affects the ability of the driver to control the platform. Both the sloshing and tumbling issue can be controlled through feedback control, and has been demonstrated successfully in the diwheel called EDWARD.

US Patent Class 180/240 lists all the vehicles coming under powered dicycles. This class has patents related to unmanned folding vehicles to be used for tactical purposes by the US government. Other vehicles in this US Patent Class are mostly invented by Dean Kamen or his associates, like the Segway PT, a balancing dicycle.


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