"Free to Caster (FTC) leaning reverse trike

This was posted on the Reverse Trike yahoo group. It's an ICE trike, but very well done. He's using a system he's calling "Free to Caster" where apparently the steering is only changing the tilt of the bike, and the wheels turn as required. Very interesting concept.

http://www.youtube.com/user/CurveCutter

Hi All,

I had to try out my new HD video camera, so I thought I would take some footage that would represent what it's like to ride a Free to Caster, reverse trike, in fast mountain conditions and at high speed, down the road. The curves are done at between 45 and 60 mph on a 30 mph, one lane road. The high speed clip is at speeds in excess of 80 mph. You can clearly see how stable the FTC design is. Remember, the handle bars are not connected to the front steering wheels. I am only controlling the leaning of the vehicle. Even over harsh bumps, on some bridge approaches, you cannot see the front wheels wander. Also, the tar snakes, and gravel patches have no effect. I hope these videos will answer some questions many of you have asked.

Kind Regards,
Tom

http://www.youtube.com/watch?v=3VonlPa4vmc

http://www.youtube.com/watch?v=lGsDYRZbBdk

Click to expand...

[youtube]zAcMmYSe6qA[/youtube]

Hrmm... not sure I would bet my life on just those four welds.

i still don't quite get the FTC advantage..

any other FTC design out there?

What does it do when you get a flat tyre?

As I understand it, it was built to prove that FTC is both stable on uneven surfaces and at speed. Great proof of concept. My only complaint would be that lack of active steering makes it very difficult to perform low speed maneuvers, like parallel parking or 3-point U-turns.

ensen.

sk8norcal said:

i still don't quite get the FTC advantage..

any other FTC design out there?

Click to expand...

The benefits of FTC are numerous and significant.

1) The vehicle is steering is always at the perfect angle for given conditions of tilt, speed, grip, and road incline/decline.
2) No manual counter steer. Turn right to go right. Turn left to go left.
3) Built-in automatic stability control.
4) You are working *with* the physics as opposed to against them.

The Main Benefit (IMHO): Dynamic Stability. Unlike pretty much every other tilting system out there, FTC provides complete dynamic stability under all normal driving conditions (within reason - no system will provide stability if you run into a railroad tie at 60 miles per hour at an oblique angle). Lack of complete dynamic stability is what keeps narrow tilting vehicles (3 or 4 wheel) from gaining mass acceptance. FTC is the clear answer to this challenge (again, IMHO).

There are some other FTC vehicles out there (google "phillip james" - he's generally credited with championing the FTC system, although the basic idea is one of general physics and hence is nothing really "ground breaking" so much as just realizing that most people don't understand the true nature of the physics when applied to tilting vehicles).

Of course, just like any other invention of significance, the devil is in the details - specifically, implementation. 8)

Eric

purplepeopledesign said:

... My only complaint would be that lack of active steering makes it very difficult to perform low speed maneuvers, like parallel parking or 3-point U-turns.

ensen.

Click to expand...

Not necessarily. FTC can be set up in a way that steering is damped sufficiently at low speeds so that maneuvering is no problem because the wheels move in concert with the tilt and do not "wander" because they are damped. I found this out when we did some initial FTC trials on the prototype which came before the SPARC.

chaster said:

purplepeopledesign said:

... My only complaint would be that lack of active steering makes it very difficult to perform low speed maneuvers, like parallel parking or 3-point U-turns.

ensen.

Click to expand...

Not necessarily. FTC can be set up in a way that steering is damped sufficiently at low speeds so that maneuvering is no problem because the wheels move in concert with the tilt and do not "wander" because they are damped. I found this out when we did some initial FTC trials on the prototype which came before the SPARC.

Click to expand...

I don't understand how you would get this motion with the geometry. Take the simplest FTC... the typical bike with front fork. Tilting the bike at 45 degrees does not cause the fork to rotate 45 degrees. A minimum radius turn cannot be done at a crawling speed unless the vehicle is moving backwards, which forces the fork to keep rotating until it hits a stop or equalizes with the weight on the head tube. I can see now how this might be used for parallel parking, since all you would have to do is pull forward of the space, tilt towards it a little, back up to force the FTC to steering lock. Halfway into the space, tilt the opposite direction to swing the FTC to opposite lock and finish at the curb. But getting out again would require the moving forward, tilting the vehicle toward the road and reversing to swing the tail of the vehicle out of the space. This might be easy enough for a forklift driver, but most people would have trouble at first and worse, other road users would find it disconcerting to see a vehicle backing out into traffic.

ensen.

chaster, thx for the info.

I need to read through this again...
http://www.tiltingvehicle.net/technical.html
http://tiltingvehicles.blogspot.com/2010/07/tva-phillip-james.html


on the TBX3, I see steering rod linkages (see 0:45)
so how is that FTC

any other FTC, other than those two vehicles?

I trust my life to this steering method most every time I'm riding my GSXR down a curvy road with no hands. You shift your weight a bit with your hips, the bike starts to lean a touch, and the wheel just follows as nice as can be. It works extremely well, and I really enjoy the fun of riding a twisty road with no hands.

But I personally can't see the harm in having linkage.

Isn't LOWRACER's latest trike about the simplest possible FTC leaning trike? http://endless-sphere.com/forums/viewtopic.php?f=7&t=20730 He addressed dampening and said the input at by his hands is all that's necessary on his trike, just like on our bikes.

purplepeopledesign said:

chaster said:

purplepeopledesign said:

... My only complaint would be that lack of active steering makes it very difficult to perform low speed maneuvers, like parallel parking or 3-point U-turns.

ensen.

Click to expand...

Not necessarily. FTC can be set up in a way that steering is damped sufficiently at low speeds so that maneuvering is no problem because the wheels move in concert with the tilt and do not "wander" because they are damped. I found this out when we did some initial FTC trials on the prototype which came before the SPARC.

Click to expand...

I don't understand how you would get this motion with the geometry. Take the simplest FTC... the typical bike with front fork. Tilting the bike at 45 degrees does not cause the fork to rotate 45 degrees. A minimum radius turn cannot be done at a crawling speed unless the vehicle is moving backwards, which forces the fork to keep rotating until it hits a stop or equalizes with the weight on the head tube. I can see now how this might be used for parallel parking, since all you would have to do is pull forward of the space, tilt towards it a little, back up to force the FTC to steering lock. Halfway into the space, tilt the opposite direction to swing the FTC to opposite lock and finish at the curb. But getting out again would require the moving forward, tilting the vehicle toward the road and reversing to swing the tail of the vehicle out of the space. This might be easy enough for a forklift driver, but most people would have trouble at first and worse, other road users would find it disconcerting to see a vehicle backing out into traffic.

ensen.

Click to expand...

ensen, I understand the confusion. It's not simple to understand the physics because they are quite counter-intuitive to traditional vehicles. First off, let me say that your comparison is somewhat misleading as a two-wheel bicycle is not an FTC vehicle as typically defined by proponents of FTC. The key to FTC is that you are reversing the dynamics of control. Instead of steering first to drive the tilting, FTC uses tilting first to drive the steering. On a bicycle this isn't a good comparison because it's a vehicle that depends on balancing. Yes, you can "drive" a bicycle without hands on the handlebars, but it's not quite the same as a multi-track vehicle forcing tilt. All the FTC vehicles I know of are at least 3 wheel, and they utilize the outboard wheels to drive (push) tilt.

*EDIT - actually, I do know of an FTC vehicle that is only 2 wheels: the Dirtsurfer (an offroad skateboard which has a FTC front wheel). Google it to see some cool videos.

That said, your example is a bit difficult for me to analyze as you start with a simple assumption - "tilting the bike at 45 degrees does not cause the fork to rotate 45 degrees". Well, yes. this might be true, but it depends on the rake of the FTC wheel (give enough rake, and your fork will turn MORE than 45 degrees if you tilt 45 degrees - you'll get wheel "flop"...) . That said, if a vehicle designer does not trust my assertions regarding FTC at low speeds (and I understand why he/she would not), it is a fairly straightforward concept to only utilize FTC above a certain transition speed, and "standard" steering at speeds below that. Philip James' early prototype FTC implementations all did this using cable tensioning mechanisms (the connection to the front wheel steering was connected by tensioned cables at low speeds, but the cable tension is gradually released as speed is increased to the transition speed - whereupon the vehicle is fully FTC controlled).

Hope that helps,

Chaster

sk8norcal said:

chaster, thx for the info.

I need to read through this again...
http://www.tiltingvehicle.net/technical.html
http://tiltingvehicles.blogspot.com/2010/07/tva-phillip-james.html

...

any other FTC, other than those two vehicles?

Click to expand...

Off the top of my head, I can't point you to anything that is easily available on the internet. However, I will say this:

1) There is a company working on an FTC vehicle for a commercial market (sadly, not here in the U.S.). I am not involved with this company at all. Unfortunately, the information that has been shown to me is confidential, and I can't share it. (I only know about this because I know one of the guys working on it).

2) When I was in college, we did some soapbox derby racing with emphasis on absurdity (engineer humor, you either get it or you don't). One year, my team's entry was... FTC steered. Yep, this was back around 1990 or so (can't remember the exact year). We thought it would be funny to race down a half mile long hill in a soapbox car that had no connection to the front wheels for steering. Instead, we put both front wheels on A-arms with oversize storm door springs for shocks (they had mountain bike shocks back then, but they were EXPENSIVE!). Didn't connect the wheels to any steering whatsoever, and told the driver to lean to steer. (yes, we had a crazy dude who actually drove it - and he made it down to the bottom without crashing!). Back then, we didn't have a name for this system, we just called it the gyroscopic skateboard effect (not really accurate, but <shrug> we were just a buncha college kids.. ya know?). Oh, and the vehicle only had a single brake on ONE of the back wheels (bicycle caliper brake).

on the TBX3, I see steering rod linkages (see 0:45)
so how is that FTC

Click to expand...

If memory serves, I believe the steering linkage you see connects the front wheels to each other - for damping. It is not connected to the handlebars that Tom uses to steer the TBX3. However, I'm not sure if Tom uses the "cable tensioning" system for low speed steering that Philip has used on early FTC prototypes.

You know, Tom Blackburn (maker of the TBX3) is a pretty nice and friendly guy. You guys who have questions or are skeptical should e-mail him. You might be surprised to learn that he originally built the TBX3 to *DISPROVE* the FTC claims of Philip (who, while being quite smart, also has a rather difficult personality...). In other words, Tom was a skeptic. However, in the end, he found out that Philip was right, and Tom became a believer.

Chaster

One more thing: reading through the info on Philip's website is going to be confusing... He is very protective of his ideas and technology (I understand why) so he is intentionally vague in his description of how everything works. If you want more info/explanation, you should search the archives of the Yahoo Tilting Vehicles SIG discussion list. Tom blackburn is also on that list and he gives plenty of details about his FTC implementation on the TBX3.

Cheers,

Chaster

John in CR said:

Isn't LOWRACER's latest trike about the simplest possible FTC leaning trike? http://endless-sphere.com/forums/viewtopic.php?f=7&t=20730 He addressed dampening and said the input at by his hands is all that's necessary on his trike, just like on our bikes.

Click to expand...

I don't know much about LOWRACER's trike, but looking at the videos, it does not appear to be an FTC vehicle to me. It seems he has the ability to tilt the main portion of the frame (where he is sitting) but I do not see the front wheels tilting at all, and it seems like the handlebars are attached to the cross member directly... I could be wrong (kind of hard to tell without looking at the vehicle in detail) but it seems to be just a regular trike with a tiltable main tube to me...

<shrug>

chaster

liveforphysics said:

I trust my life to this steering method most every time I'm riding my GSXR down a curvy road with no hands. You shift your weight a bit with your hips, the bike starts to lean a touch, and the wheel just follows as nice as can be. It works extremely well, and I really enjoy the fun of riding a twisty road with no hands.

But I personally can't see the harm in having linkage.

Click to expand...

The arguments for FTC are subtle yet quite convincing if you truly understand the dynamics. The main benefit of FTC is not the lack of direct steering linkage. =) Besides dynamic stability in all non-catastrophic dynamic situations, the other main benefit of FTC is simple steering ("SS") for a tilting vehicle. By Simple Steer - I mean, "turn right to go right, turn left to go left". Motorcycles and bicycles don't have this and hence, are dangerous in emergency situations (from a dynamics standpoint).

True, the human mind's ability to adapt is without peer, but in an emergency situation, the need to remember to countersteer (for a bicycle or motorcycle or any other manual countersteer tilting vehicle) can mean the difference between life and death. Yes, you can design sophisticated computerized systems to mimic the human mind's ability to countersteer a vehicle, but since most of these systems are designed to constrain the front wheel's steering (instead of letting physics take care of the steering) they end up being very complex, heavy, and expensive (not to mention the dangers of failure that become much more pronounced as the systems become more complex).

FTC is (IMHO) beautiful and elegant because it is mechanically simple, superior to the computerized systems (yes, SUPERIOR), cheap, robust, and far more efficient - all because it works WITH the physics instead of against.

Chaster

chaster said:

John in CR said:

Isn't LOWRACER's latest trike about the simplest possible FTC leaning trike? http://endless-sphere.com/forums/viewtopic.php?f=7&t=20730 He addressed dampening and said the input at by his hands is all that's necessary on his trike, just like on our bikes.

Click to expand...

I don't know much about LOWRACER's trike, but looking at the videos, it does not appear to be an FTC vehicle to me. It seems he has the ability to tilt the main portion of the frame (where he is sitting) but I do not see the front wheels tilting at all, and it seems like the handlebars are attached to the cross member directly... I could be wrong (kind of hard to tell without looking at the vehicle in detail) but it seems to be just a regular trike with a tiltable main tube to me...

<shrug>

chaster

Click to expand...

You're right. The front wheels don't lean, so it's more like a skateboard without the rubber to damp the turn. I guess I don't understand what FTC really means. Can FTC be done in a very simple and light manner that is safe at high speeds?

BTW, thanks for all your input in the thread.

John

John in CR said:

Can FTC be done in a very simple and light manner that is safe at high speeds?

BTW, thanks for all your input in the thread.

John

Click to expand...

Well, I guess that's yet to be seen. Since there are very few highway capable FTC vehicles in existence (that I know of) - they are all prototypes that were decidedly non-simple to develop (because of their groundbreaking nature). Once you "get it" the FTC concept is actually quite simple. However, just because a concept is simple does not necessarily translate into "simple and light" implementation.

That said, I am working on an implementation that (I hope) will have both of those attributes (along with inexpensive and robust) for a highway capable vehicle. However, I should add the disclaimer that my implementation is a variation on FTC that uses passive (unpowered) hydraulics automatic counter-steer (PHACS) in place of powered hydraulic tilt (which the TBX3 uses). It's my own idea to supplement FTC, but it's hardly unique in what it does, just in how it does it.

Chaster

marvin, I am a long time skater too, been longboarding for the past ten years.

the bmw streetcarver is interesting, but the ride is less than impressive.
slow wheels, lack of return to center, heavy, etc...
another company flexboardz have copied the idea and added return to center and air tires.
but it doesn't seem any better than a Carveboard.

http://wackyboards.blogspot.com/search/label/tilting%20wheels


but anyways, this thread is regarding FTC
which as If I understand correctly, a skateboard is not.
nor are peddle trikes that uses this steering concept.

chaster said:

*EDIT - actually, I do know of an FTC vehicle that is only 2 wheels: the Dirtsurfer (an offroad skateboard which has a FTC front wheel). Google it to see some cool videos.

Click to expand...

hmmm, a dirtsurfer is very similar to no hand bike riding, (see also bike surfing)
a negative head angle with lots of trail.

the reviews i read is that dirtsurfers are bad for tight turns.
I seen videos of them going around tight corners, very awkward.

chaster said:

One more thing: reading through the info on Philip's website is going to be confusing... He is very protective of his ideas and technology (I understand why) so he is intentionally vague in his description of how everything works.

Click to expand...

it seems like most stuff I read regarding leaning vehicle is very vague in terms of details.
there has been much interest in the last ten years, but everyone is kind of secretive about their design.

If you want more info/explanation, you should search the archives of the Yahoo Tilting Vehicles SIG discussion list. Tom blackburn is also on that list and he gives plenty of details about his FTC implementation on the TBX3.

Click to expand...

I will look at that again,
I checked out the yahoo forum before,
that forum is kind of dead, and the yahoo group software is horrible,
I really wish that someone would start a PHP forum for tilting vehicles.

Carv'n Marv'n said:

Ok...wasn't sure about the FTC thang.

Agree with the comments on the carver. Is a dog to kick, push, kick , push...coast.

Have been skating for 29years - not too many tricks these days, just like going fast, carving hard and styling. Have designed and built a number of skateparks over the past 12 years, none of them have had much of a budget to work with, but all are fun places to play..

http://www.skateboard.com.au/v2/index.cfm?smithgrind=view&id=1327
http://www.skateboard.com.au/v2/index.cfm?smithgrind=view&id=1117
http://www.skateboard.com.au/v2/index.cfm?smithgrind=view&id=875

...I'll stop Hijacking this thread now.

My trike has a return to centre - similar to a skateboard, sort of.

Click to expand...

awesome to meet a fellow skater on here,
i am into the park scene too. bowls are where its at. I live close to the Cunningham superpark in San Jose,
I am 37 been skating since middle school.
we just had a sick longboard slide contest last sunday.
kids busting standup slide at 30+ mph on soft wheels.
me at 0:47
[youtube]BJzOnJA89J8[/youtube]

to me a skateboard is the ultimate leaning vehicle !


your trike is interesting,
there are a lot of similar rear lean wheels though,
http://tiltingvehicles.blogspot.com/search/label/Motorized%20-%202%20wheels%20rear
I would like to see how yours is diffrent,
but you probably don't want to divulge too much until it goes to production. :wink:

I need to give the MP3 a try,
they seem to be pretty successful,
I would like to see videos of a mp3 on a track,
cornering to the limit of traction..

[youtube]2q3ZGwbtXXc[/youtube]

can someone tell me what those two tubes going into the shock are for?

any info on this tilter?

Hi All

purplepeopledesign said:

chaster said:

purplepeopledesign said:

... My only complaint would be that lack of active steering makes it very difficult to perform low speed maneuvers, like parallel parking or 3-point U-turns.

ensen.

Click to expand...

Not necessarily. FTC can be set up in a way that steering is damped sufficiently at low speeds so that maneuvering is no problem because the wheels move in concert with the tilt and do not "wander" because they are damped. I found this out when we did some initial FTC trials on the prototype which came before the SPARC.

Click to expand...

I don't understand how you would get this motion with the geometry. Take the simplest FTC... the typical bike with front fork. Tilting the bike at 45 degrees does not cause the fork to rotate 45 degrees. A minimum radius turn cannot be done at a crawling speed unless the vehicle is moving backwards, which forces the fork to keep rotating until it hits a stop or equalizes with the weight on the head tube. I can see now how this might be used for parallel parking, since all you would have to do is pull forward of the space, tilt towards it a little, back up to force the FTC to steering lock. Halfway into the space, tilt the opposite direction to swing the FTC to opposite lock and finish at the curb. But getting out again would require the moving forward, tilting the vehicle toward the road and reversing to swing the tail of the vehicle out of the space. This might be easy enough for a forklift driver, but most people would have trouble at first and worse, other road users would find it disconcerting to see a vehicle backing out into traffic.

ensen.

Click to expand...

I have been doing some experiments with FTC and have discovered that the low speed problems are due to uneven weight distribution fore and aft of the inclined axis of the fork. i.e. the wheel leans disproportionately because gravity is the dominant force, dragging the heavier side down. If the weights are equalised, then the effects of gravity are neutralised and the steer to lean ratio remains constant.

Hope this helps

Best regards

Martin A