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Look mum: no hands!
It’s the
by Ross Tester
AirWheel
What has one wheel, no handlebars, no “apparent” controls but is
enormous fun to ride once you get the hang of it? An accelerometerstabilised and microprocessor-controlled AirWheel, that’s what!
SILICON CHIP recently took one for a spin – literally!
Y
ou must have seen the Segway – and wondered how
anyone could ride such a gravity and balance-defying
device. Yet people – many people – have mastered
the art. So much so that you now even see TV cameramen
zipping up and down the football sidelines on their Segways
– no doubt saving their own energy but just as importantly,
giving a smooth, jerk-free picture back to the director.
Well, if you thought the Segway (with its two wheels)
was gravity and balance-defying, folks, you ain’t seen
nuthin’ yet!
Here comes the Airwheel!
The first thing you notice about the Airwheel is that there
is only one wheel. (In truth, there are models with twin
wheels but they’re only a couple of centimetres apart so
in our book, that qualifies as one!)
The second thing you notice about the Airwheel is that,
unlike the Segway (and imitators) there is nothing to hang
on to – no handlebars, no balance straps, nothing.
14 Silicon Chip
The third thing you notice about the Airwheel is that it
looks impossible to ride – until you see someone glide by
without (apparently) a care in the world. You’ll see Airwheel riders with a bit of practice under their belts riding
with hands in pockets, hands on hips, hands anywhere
except spread right out grasping for balance! There are
even plenty of videos of riders with one foot in the air . . .
The Airwheel comes in a variety of models, which are
all variations on a theme. And there are other similar devices on the market such as the Solowheel and the Electric
Unicycle. But we’ll concentrate on the Airwheel, mainly
because we got to have a play with one for a week or so,
courtesy of Airwheel Australia!
OK, what is an Airwheel?
In a nutshell, it’s a battery-powered, microprocessor and
gyroscopically-controlled single wheel personal transportation device. It has a pair of foot supports (they call them
pedals, but they don’t pedal anything!) emerging from
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each side; to ride it you simply step on it and go! To move
forward, you transfer some of your weight forward. To slow
down, stop or even go backward, you transfer some of your
weight backward. To go left . . . you’ve guessed it – you
transfer some of your weight to the left (and similarly to
go right).
The manufacturers describe it as “incorporating the
latest in fuzzy software, posture control, motion control,
anti-electromagnetic interference and a gyroscope.”
Breaking open the nutshell, the Airwheel is battery
powered and has a maximum speed (depending on model,
which in turn depends on which battery is fitted) of about
12-18km/h or so. In fact, where legal (see panel overleaf),
12km/h is usually the maximum speed allowed.
It has three-way gyroscopic control to maintain balance
and direction with a number (again depending on model)
of accelerometers to sense the rider’s weight transfers.
A microprocessor takes over then to apply power to the
pancake-type electric motor, which is basically the entire
wheel.
A Lithium-ion or Lithium Phosphate rechargeable battery of between 130 and 340Wh (depending on model) will
give around 15-21km or so range, although this depends
on both the weight being carried (maximum 120kg) and
the inclines you try to traverse. We’ve seen figures quoting
15-30° maximum on the largest models but we find even
the lower figure a bit hard to believe: the ramp up to the
first-floor SILICON CHIP offices is about 10° and we couldn’t
get the Airwheel up that! Battery life is rated at up to 1600
charge/discharge cycles.
The motors are rated at up to 800W and drive wheels up
to 36cm in diameter
Where do they come from?
The Airwheel is designed and manufactured in Changzhou, China but some references say it was invented in
Resplendent in floppy hat and sunnies (safety equipment,
no doubt) our intrepid Editor got the hang of the Airwheel
within minutes (albeit with trainer wheels fitted), zooming
around the carpark. This is the two-wheeled model – it’s
slightly easier to learn to ride than the one-wheel model
shown at left in carried “transportation” mode.
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February 2015 15
OK, so he’s showing off . . . but this
rider ably demonstrates the stability of
the airwheel, thanks to its gyroscopes,
accelerometers and microprocessor.
COILS
MAGNETS
(ONE PER
COIL)
Inside the AirWheel motor: you can see the 56 coils around the edge of the rotor
(which remains stationary!), with 56 very powerful magnets alongside around
the stator. The tyre goes on the outside of the stator, shown assembled above.
England. There is now world-wide
distribution for the Airwheel and any
number of organisations are advertising it, even on ebay.
Weight and portability
There are quite a few Airwheel
models available (see opposite) but
all have one thing in common – their
portability. They’re touted as being
ideal for riding to the station and carrying onto a train. At 10-15kg, we say
“good luck” – that’s quite a weight to
tote up and down station stairs etc – or
even carry for any significant distance.
Possible, yes. Practical? Ummm . . .
which either attracts or repels the
magnets. So the stator moves either
toward or away from the coils . But by
the time the stator reaches the point
where equilibrium would be reached,
power has been switched to the next
coil, and then the next, and the next
– resulting in the motor turning forward or reverse, always attempting
to maintain that magnetic balance but
never achieving it while ever power
is applied.
Rather than running on DC straight
from the 60V battery, the Airwheel
is driven by a three-phase inverter
through its microprocessor-powered
controller – what this means is much
more power available from the motor
for the amount of voltage applied.
Just as importantly, it enables very
good speed control over the motor, an
important consideration when your
only means of control is small shifts
in body weight!
Safety features
Learning to ride the Airwheel is at
best a little daunting because it goes
against everything your brain tells you
about balance and stability.
For this reason, detachable “trainer
wheels” are supplied which fit as outriggers and help the new rider board
the Airwheel and commence to ride.
Even so, the first hour or so is likely to
be an on/off, stop/start affair.
Gradually, though, you’ll learn that
the Airwheel is actually assisting you
The motor
Like most small electric-motorpowered people movers, the Airwheel
uses a brushless DC motor (BLDC), also
known as a pancake motor.
Unlike most electric motors, where
(as you would expect) the rotor spins
and the stator remains stationary, in
this pancake motor the rotor remains
rigidly fixed to the frame and the stator spins. In the Airwheel, the stator
actually forms the wheel halves, so it
provides the power to move.
The motor has 56 very powerful
magnets firmly positioned around the
outside of the stator and 56 matching
coils attached to the rotor. The microprocessor switches power to the
appropriate coils at the appropriate
time, resulting in a magnetic field
16 Silicon Chip
The AirWheel controller board. The three pairs of MOSFETs at the rear provide
the 3-phase drive for the motor – the rest of the circuitry keeps the wheel stable.
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by countering the natural tendency to
tip over.
We’ve already mentioned the microprocessor and gyroscopic control.
There’s an automatic speed controller
built in to some models, whereby the
front of the foot platform rises above
12km/h to prevent further acceleration. This also actuates when the battery level falls to 10% of capacity – in
this case the Airwheel decelerates to
a complete stop.
A sensor will stall the motor when
the Airwheel inclines more than 45°.
Battery and charging
The battery is inbuilt and is charged
by a switch-mode charger which plugs
into the standard 230VAC power
point. It takes about 90 minutes to
charge completely; 80% charge is
achieved in 60 minutes.
We found that with intermittent use,
the battery life is very good – we didn’t
need to recharge for the whole week
we were playing researching.
In use
With the training wheels fitted (they
can be removed quickly) we found
MODEL
X3
X5
X6
X8
Q1
Q3
Q5
MOTOR
400W
500W
600W
800W
800W
800W
800W
BATTERY
132Wh
132Wh
132Wh
170Wh
132Wh
170Wh
340Wh
SPEED
19km/h
19km/h
19km/h
19km/h
19km/h
19km/h
19km/h
DISTANCE
9-12km
11-15km
12-16km
16-23km
11-15km
16-26km
38-45km
UNIT WEIGHT
9.8kg
9.8kg
11.5kg
11.5kg
13kg
13kg
13kg
CHARGE TIME
1h
1.5h
1.5h
1.5h
1.5h
1.5h
2h
MAX WEIGHT
120kg
120kg
120kg
120kg
120kg
120kg
120kg
355mm
355mm
405mm
405mm
355mm*
355mm*
355mm*
TYRE SIZE
* twin wheel
riding the AirWheel relatively easy. In
fact, our Editor suggested that once you
got the hang of it, the trainer wheels
should come off to make turning easier.
But none of us were game to take up
his suggestion!
The lack of any handle or leash is a
bit unnerving to start off with, after all,
every instinct tells you that the damn
thing should topple over as soon as
you place one foot on it! And standing
there with two feet on it and it moving
away underneath you, well, that’s just
crazy stuff, isn’t it?
But after a few minutes of leaning on
someone else’s shoulders for support,
you find you don’t need them!
Where from, how much
Our Airwheel came from Airwheel
Australia, of Frenchs Forest NSW. As
mentioned earlier, there are numerous
models available, ranging in price from
about $750 to $1100.
The one we trialled was one of the
Airwheel Q3 models, which has a
recommended retail price of $1099
including GST.
Contact Airwheel Australia via their
website: www.air-wheel.com.au SC
Where can they be used?
That question opens a real can of worms because the way the
laws are written in at least the major Australian states, they cannot
legally be used virtually anywhere, except on private property.
In fact, they’re specifically excluded under NSW (and we believe
most other states) legislation. They come under the “prohibited
vehicles” section of the Act, which says “These types of devices
must not be used on roads or in any public areas such as footpaths, car parks and parks.”
Motorised human transporters (MHTs) such as the WheelMan
or Segway are specifically mentioned. Ref www.rms.nsw.gov.au/
roads/registration/unregistered.html The legislators haven’t quite
caught up with the AirWheel yet!
SILICON CHIP believes this is very short-sighted legislation and to
some degree, appears to be the result of lobbyists trying to ensure
a particular product was legal and nothing else!
Or perhaps it is simply that technology has once again significantly overtaken the lawmakers.
Of course, there are already many users who do ride MHTs in
public places, either ignorant of the law, don’t care, or assume they
can outrun any pursuer on foot (perhaps they can!).
Indeed, in other parts of the world, Governments have been
much more proactive in recognising the potential of these devices
in assisting in the movement of people, whether that’s to and from
public transport hubs or indeed the whole journey. They recognise
the potential of personal people movers and their ability to reduce
the number of other vehicles on the road.
Back in Australia, the Queensland government showed significantly more foresight than NSW and Victoria by legalising human
transporters, at least on public paths, on August 1 2013, providing
users wear a helmet. Incidentally, section 244L of the Queensland
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traffic laws demands they be fitted with a bell. Ummm – where!
Motorised human transporters are rapidly gaining favour on
university campuses with both students and staff having to get
from point A to point B as efficiently and effectively as possible.
They’re being used by staff moving around large warehouses and
distribution centres and by supervisors traversing large assembly
lines quickly and easily.
AirWheel have even been in discussions with large housing
estate developers who would like to keep motor vehicles outside
the housing areas – eg, park on the outskirts and AirWheel to your
house on the pathways provided! Far fetched? At the moment
maybe, but wait a year or two . . .
February 2015 17
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