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Segways not wheely enough for Boston Police
By adamg on Wed, 08/08/2012 - 9:11pm
An officer was scooting around City Hall Plaza on this thing this morning. Maybe it's part of BPD's new strategy for enforcing those Segway rules - outrun and outgun the tourist outlaws roaming the waterfront.
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Comments
How else
are they to combat those murderous, giant robotic spiders?
This is escalation at it's finest!
meanwhile, in Japan, home to Mothra:
If these guys can take on Mothra with bikes, what the hell do Boston Police need asinine electric podiums for? One of those things probably costs as much as 5 of the decked-out mountain bikes BPD uses.
sorry to see that ballistic
sorry to see that ballistic vests have made it to Japan. Also,
they're riding on the sidewalks and in the crosswalks.
Non-Lethal Response Vehicle
More info here: http://t3motion.com/commercial/
I hope BPD's model isn't armed!
Special feature
The Judge Dredd Edition Honda Goldwing tricycle / Segway mashup has a wood chipper for when the sclerotic old potty-mouths of the BPD chase down skateboarders and steal their gear.
Natick has one (or more) of
Natick has one (or more) of those that carry officers patrolling parking meters.
What?
Do you really expect them to walk across that windswept wasteland?
Does it come
With a towable cooler?
Long ago, the Prudential
Long ago, the Prudential Center used to have four wheel ATVs to patrol the area. Those were much better: they could fit into most passageways, go up and down steps or steep inclines, were more stable, and were low-cost. These look unstable and expensive to buy and maintain. I hope these were on loan from the manufacturer and that the city didn't pay for them.
These are so much more dangerous than Segways
I've ridden these stand-up 3 wheeled policing vehicles before and they are SO much more dangerous than a Segway. You know how 3-wheelers are dangerous because they are unstable, well now reduce the size of the wheel base and raise the center of gravity.
Imagine an officer trying to take a sharp turn at speed. Game over.
In the interest of full disclosure- I worked at Segway for some time. But don't anymore, and have not material connection with the company.
3-wheelers are unstable?
If so, why is it much harder to knock over, or fall off, a tricycle, compared to a bicycle?
Not quite true: static vs dynamic stability?
Ron, the 3-wheeler may be more stable when it's standing still, but compare the behavior of a 2-wheeled and a 3-wheeled vehicle to a sharp turn. Bike just leans into the turn; trike can roll over.
Ever try standing up on one?
It's the center of gravity, Ron.
But go ahead and do some experiments if you don't believe us.
This vehicle looks front heavy though.
Your average 3 wheel ATV or kids tricycle is going to be heavier in the back (especially with a person on it), causing the vehicle to flip backwards on ramps, bumps or sharp turns.
Tipsy forward
This one looks more tipsy in the forward direction. It might flip like an SUV - peak velocity plus sharp turn = upside down.
It depends whether they mounted the cooler for after-hours beer above or below the wood chipper.
Cooler is on the side...
opposite the firearm to displace the weight. Looks like a Righty cop here using a lefty machine though. Cooler must not be filled.
Exactly, just like the Reliant Robin
This Top Gear episode was freaking hilarious and shows exactly what you're talking about. Forward Trikes have a hellish problem with turning at any kind of speed.
Still, the weight appears to be behind the wheel,
and more center mass which should help this machine stay upright, even on turns.
Behind the wheel?
I'm not sure you see what the problem is. There's mass on that monstrosity outside the tip axis between back wheel and front wheel, and a large amount of mass located far forward from the back wheels as well as too high above the wheels. The center of gravity is very high, especially with a standing rider, and the distance to the tip axis is very short. It would take very little force to tip this beastie.
But it's okay with me, because I expect Benny Hill - esque videos on YouTube showing Boston's Finest going ass over teakettle on this engineering disaster. Just tell your buddies to always brake into a turn and lean out (and make sure they're "filling in for a supervisor" first).
No I think I have an idea
Usually the Center of Mass on (2 axle) vehicle is halfway between the front and rear axles, and vertically should be about 1/3 the height of the vehicle measured from the ground. I would need the weight of this vehicle to determine if a person would even matter. It looks like the Mass and front tire should be able to counter any pedestrian weight on the back (vehicle weighs 700 pounds vs 250 pound person pusing back on one full axle.
If you look at the Youtube video, the centrifugal force overcomes the centripetal force of the vehicle, causing the vehicle to flip. These forces in what would be the front lead tire, causing the vehicle to tip. The front lead tire on this vehicle is somewhat balanced since center mass is closer to the front of this vehicle.
The "Sentinel" in action
So, I poked around the internet and found out this is being sold by a company called Xtreme Green Products. It's their Sentinel. Here's a promo video they made: http://www.youtube.com/watch?v=SWog5B8bh-M
Note that he never takes it up above about 10 mph and his turns are all at very low speed.
In other words, if you want to outrun this thing, get it going in a straight line, then run back the way you came. The officer is either going to dump it when he tries to turn, come to a near stop in order to execute its "ability to turn fully within its own radius", or jump off and chase you on foot anyways.
Step away from the engineering
And place the math on the ground, sir.
Pete, you might want to consider that moving weight forward in a delta three-wheeled vehicle makes it less stable, rather than more, and then think about how much else you don't understand about physics. I recommend learning what "moment" means (perhaps as applied to a six-foot man standing on a plane a foot above the axis between front and side wheel ground contact).
But if you like you can go ahead and advise your friends to lean forward when turning - that'll move the cg forward and make it more stable, right?
Some confused nouns
I think in parts of Pete's post that you're responding to, he's talking about "the vehicle" being the Reliant Robin in the Top Gear clip. In that case, the motor is over the front wheel making it easier to roll than if the motor had been in the boot over the back axle. I think he's claiming that to be different than the Sentinel whose weight isn't high centered over the front wheel.
However, I agree with you that it's still too high a center of mass for the wheel base and height (the Sentinel literature claims it can climb 6-8" curbs...which adds even more likelihood of it rolling over, in my opinion...no word on how high they recommend going down curb from, tee hee). Even when I watched the Denver airport security using these things in one of the only other YouTube videos showing the Sentinel in action, the only turn they do is either in-place or slow gentle lane changes around parked cars in the drop-off area.
Right, I wasn't very clear.
The Reliant Robin has a center mass right behind a small front tire at the front of the vehicle, while this police vehicle appears to have the center mass distributed upon some sort of frame designed to make the vehicle more balanced.
From the picture here it doesn't look that bad, but it does look a little more top heavy on the website (where it says it has a max speed of 29mph).
They should just put them on
They should just put them on those Hubway bikes. And require them to follow the rules.
I often see Boston's cops who are on bikes ride the wrong way down the street, ride in bike lanes in the wrong direction, ride through red lights, and ride on sidewalks. They don't make a very good example for the general public.