Is backwards backward?

Flenser · 10-23-2009, 10:40 AM

When going backwards on the Segway, and turning, I believe that the turn direction is wrong.

Imagine if the Segway wheels were the front wheels of a wagon. If you move the leansteer to the right and move forward, the wagon would move to the right. The Segway has this part correct. Now imagine moving the leansteer to the right and backing up the wagon. The rear of the wagon would move to the right, followed by the front wheels.

On the Segway, however, moving the leansteer to the right and backing up causes the Segway to move to the left.

I don't know if this is purely a necessary outcome of the way the wheels move independently to keep the Segway balanced, or if this was just incorrectly programmed/specified.

Since all movement on the Segway is initiated by the computer, I would think that this could be corrected in software.

Everything else on the Segway feels completely natural, if I may use that term for something so high-tech. The fact that complete novices can hop on a Segway and be gliding happily in less than a minute is a testament to the hardware and software team at Inc.

My guess is that there's an inherent technical reason why backing up and turning will make nearly anyone fall off.

jgbackes · 10-23-2009, 01:56 PM

You'll get used to it.

Isidore · 10-23-2009, 05:04 PM

The programmed way is self consistant. The platform yaws the way you push the leansteer. If it were the other way around when going backwards you would push the handlebar left and the platform would twist to the right. This would give you potentially uncontrollable positive feedback. Also, at very low speeds or when standing still or just rocking on the spot you would have inconsistant and unpredictable flipping of the control direction.- I imagine it would be like one of those trick bicycles at fairgrounds which have the steering geared to work so that turning the handlebar left turns the wheel right. The showman rides it up and down and then bets you you can't ride 20 feet up the road. He always wins.

Gihgehls · 10-23-2009, 05:13 PM

There's really no holding still on a segway. In practice, you're always moving forward and back just a little bit. So, imagine you're remaining stationary, then you initiate a left turn to spin in place, then you shift your weight backwards just a little. Should the segway instantly stop turning left and suddenly start turning right?

SegwayDan · 10-23-2009, 05:54 PM

Quote:

Originally Posted by Flenser

When going backwards on the Segway, and turning, I believe that the turn direction is wrong.

Imagine if the Segway wheels were the front wheels of a wagon. If you move the leansteer to the right and move forward, the wagon would move to the right. The Segway has this part correct. Now imagine moving the leansteer to the right and backing up the wagon. The rear of the wagon would move to the right, followed by the front wheels.

On the Segway, however, moving the leansteer to the right and backing up causes the Segway to move to the left.

I don't know if this is purely a necessary outcome of the way the wheels move independently to keep the Segway balanced, or if this was just incorrectly programmed/specified.

Since all movement on the Segway is initiated by the computer, I would think that this could be corrected in software.

Everything else on the Segway feels completely natural, if I may use that term for something so high-tech. The fact that complete novices can hop on a Segway and be gliding happily in less than a minute is a testament to the hardware and software team at Inc.

My guess is that there's an inherent technical reason why backing up and turning will make nearly anyone fall off.

As Isidore said, there's a good reason for this odd behavior. And you *will* get used to it (and faster once you stop objecting to it).

Just practice with it.

If you look at it as Isidore says, it's the yaw (pivoting around the vertical axis) which is controlled by the left-right pivoting of the leansteer.

It's actually not an error at all, but a consistency of control which is essential for dynamic balancing. If you think about that a bit, the machine is actually constantly switching between forwards and backwards rotation of the wheels in order to stay beneath the rider. These corrections happen independently of the yaw or steering control. So this yaw position has to be consistent throughout all the forwards/backwards direction changes of wheel rotations.

SegwayDan · 10-23-2009, 08:52 PM

Quote:

Originally Posted by Gihgehls

There's really no holding still on a segway. In practice, you're always moving forward and back just a little bit. So, imagine you're remaining stationary, then you initiate a left turn to spin in place, then you shift your weight backwards just a little. Should the segway instantly stop turning left and suddenly start turning right?

That's a good way of putting it!

KSagal · 10-23-2009, 11:05 PM

As sophisticated as the segway is, it is just a machine that does what it is designed to do. It does not learn.

You are a bit more sophisticated, and have the capacity to learn. You will learn to steer and control the segway in reverse...

As was stated, it is easier when you stop fighting it. Most of segway control is like that. The less you make it do stuff, the more stuff it will do...

Bob.Kerns · 10-24-2009, 10:00 AM

Quote:

Originally Posted by Flenser

When going backwards on the Segway, and turning, I believe that the turn direction is wrong.

Imagine if the Segway wheels were the front wheels of a wagon. If you move the leansteer to the right and move forward, the wagon would move to the right. The Segway has this part correct. Now imagine moving the leansteer to the right and backing up the wagon. The rear of the wagon would move to the right, followed by the front wheels.

On the Segway, however, moving the leansteer to the right and backing up causes the Segway to move to the left.

While I (mostly) agree with everyone's descriptions of why a Segway behaves the way it does, I think the problem lies with your analogy of a wagon.

I bet you're doing this in Riderless Balance Mode. I found that incredibly confusing at first, too, for the same reason. I think experience backing wagons with tractors or other vehicles makes this more confusing.

You're thinking of the LSF and the base as being separate units, and you have to move the tongue to get some imaginary "front wheels" pointed to your left to turn the unit to the right, and then those "front wheels" and "tongue" will follow.

But the Segway is NOT a wagon. It is a trailer. The LSF is not attached to some invisible "front wheels", it is a slightly bendy tongue on a trailer.

To back a trailer, you simply rotate the trailer in the direction you want it to go.

You want to back to the right, you face the back of the unit to the right. That means you face the front of the unit in the opposite way, by pushing the tongue to the left.

I think once you can switch to thinking of it as a trailer, rather than a wagon, it will start to feel natural to you.

lucas · 10-24-2009, 11:06 AM

I personaly didn't think so deeply before but I frankly would like to give a try to such a software modified version on that point, could be interesting even if I frankly feel the current implementation is perfectly fine.

BR

Lucas from Switzerland.

Flenser · 10-25-2009, 01:03 AM

Bob's response was the key for me to understand the behavior -- the Segway acts like a two-wheeled trailer, not a four-wheeled wagon.

This behavior isn't an issue for me in riderless balance mode. When moving the Segway around, it acts as I expect: like my reel mower. Or the flip side: my mental model matches the Segway's actions.

It's when I'm riding it that I have no previous experience to match its behavior. I've never stood on a trailer and backed it up. Or on my reel mower.

I maintain that this behavior is probably the only non-intuitive part of the Segway. I've had about 20 people go gliding on my i2 with less than a minute of training. Four or five of them have tried turning while going backwards and every one of those almost dumped. Statements in this thread like "you'll get used to it" or "you can learn" are indicative of the non-intuitive behavior.

Lest I give the wrong impression: I love my i2 and am amazed both at how easy it is to use, and how much fun it is.

10-23-2009, 10:40 AM	#1
Flenser Junior Member Join Date: Sep 2009 Location: Boston, MA Posts: 34	Is backwards backward? When going backwards on the Segway, and turning, I believe that the turn direction is wrong. Imagine if the Segway wheels were the front wheels of a wagon. If you move the leansteer to the right and move forward, the wagon would move to the right. The Segway has this part correct. Now imagine moving the leansteer to the right and backing up the wagon. The rear of the wagon would move to the right, followed by the front wheels. On the Segway, however, moving the leansteer to the right and backing up causes the Segway to move to the left. I don't know if this is purely a necessary outcome of the way the wheels move independently to keep the Segway balanced, or if this was just incorrectly programmed/specified. Since all movement on the Segway is initiated by the computer, I would think that this could be corrected in software. Everything else on the Segway feels completely natural, if I may use that term for something so high-tech. The fact that complete novices can hop on a Segway and be gliding happily in less than a minute is a testament to the hardware and software team at Inc. My guess is that there's an inherent technical reason why backing up and turning will make nearly anyone fall off.

10-23-2009, 01:56 PM	#2
jgbackes Senior Member Join Date: May 2007 Location: San Jose, CA - USA Posts: 1,314	You'll get used to it. __________________ sǝʞɔɐq ɟɟǝɾ If I had known I was going to live this long, I would have taken better care of myself. To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.

10-23-2009, 05:04 PM	#3
Isidore Member Join Date: Jun 2004 Location: London, United Kingdom. Posts: 931	The programmed way is self consistant. The platform yaws the way you push the leansteer. If it were the other way around when going backwards you would push the handlebar left and the platform would twist to the right. This would give you potentially uncontrollable positive feedback. Also, at very low speeds or when standing still or just rocking on the spot you would have inconsistant and unpredictable flipping of the control direction.- I imagine it would be like one of those trick bicycles at fairgrounds which have the steering geared to work so that turning the handlebar left turns the wheel right. The showman rides it up and down and then bets you you can't ride 20 feet up the road. He always wins. __________________ Regards Isidore

10-23-2009, 05:13 PM	#4
Gihgehls Senior Member Join Date: May 2006 Location: Galactic Sector ZZ9 Plural Z Alpha Posts: 2,086	There's really no holding still on a segway. In practice, you're always moving forward and back just a little bit. So, imagine you're remaining stationary, then you initiate a left turn to spin in place, then you shift your weight backwards just a little. Should the segway instantly stop turning left and suddenly start turning right? __________________ To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. "...if you insist on being imprecise in use and unique in definition, you should hardly be surprised that your attempts at communication are poorly understood." -a wise man

10-23-2009, 11:05 PM	#7
KSagal Glides a lot, talks more... Join Date: Jan 2004 Location: Pelham, NH, USA. Posts: 10,356	As sophisticated as the segway is, it is just a machine that does what it is designed to do. It does not learn. You are a bit more sophisticated, and have the capacity to learn. You will learn to steer and control the segway in reverse... As was stated, it is easier when you stop fighting it. Most of segway control is like that. The less you make it do stuff, the more stuff it will do... __________________ Karl Ian Sagal To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts. "Well done is better than well said." (Ben Franklin) Bene factum melior bene dictum Proud past President of SEG America and member of the First Premier Segway Enthusiasts Group and subsequent ones as well.

10-24-2009, 11:06 AM	#9
lucas Junior Member Join Date: Sep 2009 Location: Switzerland Posts: 19	I personaly didn't think so deeply before but I frankly would like to give a try to such a software modified version on that point, could be interesting even if I frankly feel the current implementation is perfectly fine. BR Lucas from Switzerland.

10-25-2009, 01:03 AM	#10
Flenser Junior Member Join Date: Sep 2009 Location: Boston, MA Posts: 34	Acting like a trailer Bob's response was the key for me to understand the behavior -- the Segway acts like a two-wheeled trailer, not a four-wheeled wagon. This behavior isn't an issue for me in riderless balance mode. When moving the Segway around, it acts as I expect: like my reel mower. Or the flip side: my mental model matches the Segway's actions. It's when I'm riding it that I have no previous experience to match its behavior. I've never stood on a trailer and backed it up. Or on my reel mower. I maintain that this behavior is probably the only non-intuitive part of the Segway. I've had about 20 people go gliding on my i2 with less than a minute of training. Four or five of them have tried turning while going backwards and every one of those almost dumped. Statements in this thread like "you'll get used to it" or "you can learn" are indicative of the non-intuitive behavior. Lest I give the wrong impression: I love my i2 and am amazed both at how easy it is to use, and how much fun it is.

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