Forward motion without rider

[CCoops1984]

Can anyone explain to me the logic behind having the Segway move forward without a rider on board?
As a new rider, it is my opinion that the Segway program should keep it stationary in the 'Balance' mode until a rider is on board.

Thanks.

Student of Life

[BruceWright]

A segway cannot balance and stay level without a rider.

As Scotty on Star Trek used to say, "You canna change the laws of physics!"


The reason it can't is because of the center of gravity of the Segway itself.

The handlebars are forward of the axel. That means the center of gravity is also forward of the axel, because the handlebars have weight. That weight is in front of the axel.



In order for the Segway to remain stationary, the center of gravity has to be ABOVE the axel.

When a person is standing on the segway, the center of gravity IS above the axel.

The E series could do this, because the e-series had bags high up on the sides. If you put weights in the side-bags, it could auto-balance. But if you took the weight out of them, it couldn't.



The Segway uses your weight to balance. Without it, it cannot. Unless you want to design a Segway without handlebars. ;)

-Bruce Wright

Segway: Vehicle of Dream

[KSagal]

First off, I have an 'E' model, which has the capacity to stay stationary in the balance mode. Because of your question, I assume you to mean that you have an 'I' or a 'P' model.

The segway is not compelled to drive forward. It does however, attempt to stay under the center of gravity. This is why, in balance mode, it goes forward when you lean forward.

When there is no rider on the platform, there is obviously no weight. The only weight that the segway balance sensors can perceive is that of the control shaft and handlebar. (And handlebar bag if you have one)

Because there is a forward weight (the control shaft/handlebar) and no counterbalancing weight on the platform, then machine moves forward...

If you were to put a briefcase or bowling bag on the platform when you got off, the machine would act differently. If the weight were enough to counteract the control shaft and still be behind the center of gravity, the machine would then go in reverse. Move the bowling bag and get different results...

This was talked about in the past. Usually not on purpose, but someone would inadvertantly put a bag or something on the platform, and the machine would just drive away...

This is why there is about a 6 foot electronic leash on your machine, but that is a topic for another day...

Karl Ian Sagal

Each road you travel should be just a bit better for having had you pass.

[BruceWright]

Can you imagine a handlebar design like two ski poles, just above the axel, coming from where the gear boxes are?

That would be really cool. Then stationary balance would work.

-Bruce Wright

Segway: Vehicle of Dream

[KSagal]

Bruce,

You should see the clay prototype of a segway from the future that was featured on a show that John Rattsenberger hosted. I think it was 'On the road in America' or something like that...

It has the exact design that you described... I am sure that someone can chime in with more details... That show, and links to that prototype are here on this forum somewhere. I think it was from last summer...

Karl Ian Sagal

Each road you travel should be just a bit better for having had you pass.

[solotrek]

I found that my Seg would self balance, while pointed uphill, on a driveway with a slight grade.

[Desert_Seg]

BTW, the phenomenom that Bruce and Karl describe is something that I love to train folks on.

Imagine getting to a steep downward slope.....

What happens in a car or any other wheeled transportation EXCEPT an HT? Your center of gravity changes as if you were on a fulcrum and you "tilt" downwards.

What happens if you are on an HT? You center of gravity remains the same, platform remains level to earth!

Oh, the look on folks faces when you show them this "trick".

It is also, I believe, the most difficult concept to both envision and teach!

Stenve

--- EAMUS CATULI! ---

No person is truly useless. They may always serve as a bad example!

[KennyG]

Hey Desert_Seg,
Your description is right on! That phenomenon is why I now have scratches on my aft battery pack. My speed was high, the slope angularity was high, and the Seg was adamant it was going to remain level!!

KennyG
http://home.earthlink.net/~kenng/images/Warpaint1.jpg

[KSagal]

I describe it as the escalator effect...

In my teachings, "... on a bike or car, when traveling down hill, you are facing the floor of the valley. When traveling up hill, you are facing the sky beyond the peak of the hill. On a seg, you are always facing forward, but traveling up or down. Kind of like the difference between the motion of an escallator to that of a ramp..."

Karl Ian Sagal

Each road you travel should be just a bit better for having had you pass.

[amturnip]

Whether it stands still or hovers is a red herring. The question is: how far should it muddle onward before melting? Developments in that realm would be welcome. Google crack marble wall historic building or segway fell ban metro tracks to jog your memory.

[cmonkey]

quote:Originally posted by CCoops1984

Can anyone explain to me the logic behind having the Segway move forward without a rider on board?
As a new rider, it is my opinion that the Segway program should keep it stationary in the 'Balance' mode until a rider is on board.

Thanks.

Student of Life


Aside from the e series, which can balance on it's own without a rider, the i series needs to be in balance mode before you get on it.
As shown in the safety video you test this by gently rocking the segway to see if it tries to level itself.

When you get on the segway you depress the rider detect buttons and the system stays in balance mode with you on it.

If you let the segway go and the rider detects aren't depressed, the segway shuts itself off for safety.

The segway moving forward is just because the mass of the control shaft and handlebars is in front of the CoG, and thus it goes forward.

I have seen an 'i' series set up with a counter weight to exactly balance against the mass of the CS assembly. Neat to see the unit stand without moving, but the equilibrium is easily upset.

I find the unit's ability to try and balance when riderless a very convenient feature. When I roll into my local bank or starbucks, I just point the seg at the wall and let go. (usually less than a foot away from wall) It runs into the wall and stays there in balance mode. When I've gotten my coffee I just hop back on and roll away, no fumbling with the button.

If you try to lean a seg against a wall in power assist mode or off, it may eventually roll back and fall to the floor.

But, if you've got a version of software with the presidential upgrade in it, you don't ever have to put the unit into balance mode. With the unit in power assist mode, (and perfectly level) you can step right up and the unit will automatically go into balance mode.
If your seg isn't level and you try this, you stand a very good chance of doing a faceplant.

Thus the ability to put it into and out of balance mode with the touch of a button.

David S

I love my magic carpet!

[amturnip]

quote:Originally posted by cmonkey
But, if you've got a version of software with the presidential upgrade in it, you don't ever have to put the unit into balance mode. With the unit in power assist mode, (and perfectly level) you can step right up and the unit will automatically go into balance mode.
That feature was present on the version 10.0 Amazon.com HTs from 2003. Anyway, the President's HT was switched-off (not in power-assist), according to http://www.segway.com/connect/newsletters/general_004.html. All indications are that the current President is not upgradeable.

[KSagal]

amturnip,

I did as you suggested and googled the exact terms you stated. I found an article from DC that is almost 3 years old. It states that a person lost control of the seg and it fell. What a machine does when someone looses control is not a reasonable thing to base that machine's performace on...I suspect that most devices that are used and then the operator looses control, do things that would not be considered a good thing...

The second reference that you suggested and I looked up was that of the cracked marble wall. If you do your own research, you see that the "demo" was being done for 'Transportation for a Livable City, and the San Francisco Bicycle Coalition.

Both of those organizations published in their own newsletters, in December of 2002 that they were clearly and outwardly anti-Segway. That would tend to shade later reports that support their preconcieved position... When a group that clearly has come out publicly and decried segways as bad and should not be allowed on the sidewalks, and later says that a seg did damage during a demo for just them, makes me wonder...

Why was someone doing a demo for these published segway haters... It does make me wonder. I think we have heard negative from bicycle groups before, and having someone bring up events of 3 or more years ago, that have yet to be repeated, despite the far greater exposure to segs in public now compared to then, only works to help their mis-information campaign...

I am not saying that a segway, when improperly handled cannot cause some damage of some sort, but it ssms to me that if there was a problem of the nature of the comments from the two sites you indicated, there would have been far more events and more current events than those that you are using as examples...

As I said in earlier posts, I have an 'E' machine, and it does not do what the 'I' does when you get off it. It stays where it was when you got off it, and waits. Maybe what you are looking for is an "e".



Karl Ian Sagal

Each road you travel should be just a bit better for having had you pass.

[cmonkey]

lol, my bad, I was told that update came into being with version 12.0

I love my magic carpet!

[amturnip]

quote:Originally posted by KSagal

Why was someone doing a demo for these published segway haters... It does make me wonder. I think we have heard negative from bicycle groups before, and having someone bring up events of 3 or more years ago, that have yet to be repeated, despite the far greater exposure to segs in public now compared to then, only works to help their mis-information campaign...
Why give them the rope? Why wait for another surprise? The question of the thread is "forward motion without rider". There's room for improvement.

[RC Mike]

it balances what is above it... why let go?

mike

[CCoops1984]

Thank you all for your lively discussion and enlightened views.

However, I still have questions.
Given:
1. In the power assist mode I can navigate my HT up/down stairs and to/from its parking spot.
2. There exist 'rider detect' limit switches.
3. The gyros can detect a vertical position and will not go into 'balance mode' unless the HT is vertical.

Therefore:
Why can the HT NOT continue to hold the vertical position in the balance mode until the 'rider detect' limit switches have been made?

Student of Life

[BarnyFife]

The engineers designed the software so that if no rider is detected and the machine moves forward over 3 feet it will kick the CS over and stop, this is called the electronic leash.

What if someone fell or jumped off a moving machine, they had to program it to do something to be safe.

As has been stated previously with no payload the center of gravity is such that the CS would have to tilt way back to balance.

[Red Seg]

The bottom line (IMHO) is physics. The only reason the e model can remain upright is because the center of gravity is almost directly above the axle. Only minor corrections are necessary to keep it there. On all other models, the center of gravity is too far in front of the axle. To remain standing the axle must move forward before the control shaft and handlebars can move. If it moves too slowly forward, the control shaft and handlebars will move as well therefore no balance.

The only way the Segway can pull the center of gravity back over the axle is to spin the axle. This spinning will cause movement in the area of least resistance. If nothing is blocking the wheels, the Segway will roll. If the wheels are blocked the control shaft will pull back. You can try this just by putting you foot in front of one of the wheel while the machine is in balance mode.

No programming can overcome the laws of physics.

[CCoops1984]

To all,
Thanks again for your patience and your informed opinions.
I love my i80 and will gladly explain this feature to any/all who ask for a demonstration.
Happy Gliding!

Student of Life

[Georgem]

I have an XT which I use to accompany The Light of My Life on walks along the beach. I have discovered that if I point the beast uphill, it will stand unattended in the balance mode most of the time. Softer sand helps guarantee this. This makes getting on and off whilst seeking fossilized shark teeth much easier.

[Runway01]

Try putting your foot in front of one of the wheels when it is in balance mode. The result is interesting, predictable (according to this thread) and useful sometimes.