"Free to Caster (FTC) leaning reverse trike

[sk8norcal]

https://www.kickstarter.com/projects/1690474092/lean-skateboard-leans-into-turns

cool tilting wheel skateboard truck.

not sure exactly how it works,
The wheels lean and also steer with no steering linkages. (FTC? maybe?)

How does it lean into turns?

Whenever the rider leans his/her body into a turn, the Lean Board’s wheels lean into the same direction. The steering mechanism is a simple four-bar linkage system which is attached to the board. Every joint is designed in such a way that it has two rotational degrees of freedom (Red and Blue arrows). In the XYZ coordinate system, the origin is at the center of the steering. The parallelogram linkage system's center part is perpendicular to the board. When the board is pushed down towards the direction of the turn then the wheels rotate in XY (Blue) and XZ (Red) plane. The Lean Board’s steering is designed in a such a way that all joints rotate in both XY’ and XZ’. These planes rotate at the same time causing the wheels to turn in one plane and lean into another plane. The center axis of the wheels is the intersecting line of XY’ and XZ’ planes. Each wheel has an individual axis which moves in a Conical shape, making them turn in 3 dimensions. The lean board's spherical wheels let it lean and rotate at the same time in a smooth manner. Moreover, they are big enough to go over any moderate crack making the ride smoother.

 

[Martin A]

The wheels both tilt and steer toward the inside of the turn as the board leans.

Both are due to the inclined parallelogram that is formed by the cross links and the uprights. Although it is not obvious from the diagram, the top link is forward of the bottom one.

So the tilt is caused due to the fact that the top link moves toward the inside of the turn (relative to the bottom one) and so the top of the wheel moves inwards as the board leans.

The inclined parallelogram also causes the wheels to steer from the straight ahead by pushing the front of the wheel inwards as the board leans because the top link is ahead of the wheel centre line and the lower link is behind it. This steering is the caster effect.

As the caster is linked to lean angle this is therefore, like most skateboards, not a free to caster set up.

An obvious steering linkage is there, it's simply hidden in full sight if you're unfamiliar with this style of steering. Just like in a primitive soap box racer, there doesn't appear to be a linkage until you realise that the feet steer the front axle directly. It is the parallelogram, that is the steering linkage attachment to the board. that steers the wheels.

 

[sk8norcal]

Good explaination, I was thinking along similar lines, here's a better pic,

The inclined parallelogram also causes the wheels to steer from the straight ahead by pushing the front of the wheel inwards as the board leans because the top link is ahead of the wheel centre line and the lower link is behind it.

his prototype might be FTC...

 

[Martin A]

Thanks for the feedback on my explanation. Glad to know I can be of help on this forum whose experts I hold in such high esteem.

The prototype is more akin to Free to Caster, but as the wheels are connected neither are completely free to caster. This is okay on a smooth surface but if one wheel encounters a bump or hole that slows it down, then both wheels will steer in the direction that is on the side of the obstruction, which can obviously be a problem.

I speak from experience having dabbled with FTC designs myself. I imagine the creator of the board discovered the same thing.

The highway-legal powered trikes that use FTC overcome this problem by adding torque sensors and hydraulics, and of course by having much larger wheels and pneumatic tyres they are less sensitive to small disruptions in the road surface.

 

[sk8norcal]

2 piaggio mp3 crashes,

https://www.youtube.com/watch?v=rH-gemnfLlA
https://www.youtube.com/watch?v=wHSF50_ZrXc


mp3 on a track
https://www.youtube.com/watch?v=L-Ul4XraErU


ice road simulation at 0:53
https://www.youtube.com/watch?v=DZN-fL___30
https://www.youtube.com/watch?v=LjaMi7fw2Ss

 

[felix]

I was thinking about the axis of tilt of the vehicle body. On most all designs I see the axis is at the very bottom of the vehicle body. If the axis is placed higher up (closer to the CG) I would assume that it would be a lot easier to tilt (and therefor steer) at lower velocities. Could this be? This however will reduce the amount that the cg is displaced while turning, how would this affect high speed tilting/turning?

 

[Willow]

I was thinking about the axis of tilt of the vehicle body. On most all designs I see the axis is at the very bottom of the vehicle body. If the axis is placed higher up (closer to the CG) I would assume that it would be a lot easier to tilt (and therefor steer) at lower velocities. Could this be? This however will reduce the amount that the cg is displaced while turning, how would this affect high speed tilting/turning?

My trike sits very high.... though the actual weight distribution of the batteries and motors etc. are relatively low. It rides as a 2 wheeler would at high speed - very sure footed in a corner..... and at slow speeds it is stable, but requires a little more effort to lean it. Low slung tilters tend to rely on other mechanical assistance to lean, rather than the weight of the rider.

 

[Willow]

I was thinking about the axis of tilt of the vehicle body. On most all designs I see the axis is at the very bottom of the vehicle body. If the axis is placed higher up (closer to the CG) I would assume that it would be a lot easier to tilt (and therefor steer) at lower velocities. Could this be? This however will reduce the amount that the cg is displaced while turning, how would this affect high speed tilting/turning?

My trike sits very high.... though the actual weight distribution of the batteries and motors etc. are relatively low. It rides as a 2 wheeler would at high speed - very sure footed in a corner..... and at slow speeds it is stable, but requires a little more effort to lean it. Low slung tilters tend to rely on other mechanical assistance to lean, rather than just the shifting weight of the rider.

 

[sk8norcal]

http://www.autoblog.com/2014/09/07/yamaha-electric-leaning-trike-patent/?icid=autoblog|check-these-out

yamaha electric leaner with 2 rear hub motor

 

[Martin A]

I was thinking about the axis of tilt of the vehicle body. On most all designs I see the axis is at the very bottom of the vehicle body. If the axis is placed higher up (closer to the CG) I would assume that it would be a lot easier to tilt (and therefor steer) at lower velocities. Could this be? This however will reduce the amount that the cg is displaced while turning, how would this affect high speed tilting/turning?

The axis of tilt will always be at the level of the tire/road interface. If it were any higher the tires would lift from the road surface as the vehicle leaned, which is of course impossible due to gravity and also they would then not be able to generate a sideways thrust against the road surface..

To check this, hold a pencil half way along its length between your thumb and finger. Have it pointing downwards with its tip on a table. Now without allowing your hand to drop at all twist it to lean the pencil. You'll notice that the pencil will lift from the surface of the table. You can't make it lean without losing contact with the table unless of course the tip remains in contact with the table.

On another note neither Willow's nor Yamaha's trike are free to caster.

 

[sk8norcal]

http://www.ev4.pl/index-en.html

[youtube]pSEh8Ngcm4Y[/youtube]

 

[sk8norcal]

http://www.swincar.fr/


[youtube]Wo3JzateMM4[/youtube]

 

[Martin A]

Neither EV4 nor Swincar are Free to Caster. Both have a control which links lean angle and the direction of the wheel. Free to Caster vehicles don't have this connection.

The Swincar moves its centre of gravity toward the outside wheels which means a greater likelihood of overturning than if the seat was fixed in the chassis. Yes it keeps the driver upright but there's a cost to that. It needs a wide track to keep the c of g in a sensible place.

 

[Willow]

just built a tilting LEGO quad.

 

[sk8norcal]

irukan
http://tiltingvehicles.blogspot.com/2015/03/electric-luge-trike.html

[youtube]MAYgtkzNveE[/youtube]

 

[sk8norcal]

Gagarin Company - Grasshopper

[youtube]34TUasDd6k8[/youtube]

 

[Martin A]

Neither Irukan nor Grasshopper are Free to Caster.

 

[sk8norcal]

Yeah, they are not.

I am just putting e-leaners in this thread, instead of starting another thread.

not too many e-leaners out there.


saw this on FB,

self driving 3wheel scooters (concept video)
https://vimeo.com/116490222

 

[ricklearned]

[No message]

 

[Martin A]

Yeah, they are not.

I am just putting e-leaners in this thread, instead of starting another thread.

not too many e-leaners out there.

That's cool, I just like to keep people informed.

saw this on FB,

self driving 3wheel scooters (concept video)
https://vimeo.com/116490222

Looks like the future to me, unless you live somewhere where it rains. Bring on the Lit C-1 body in this kind of thing in the UK.

 

[sk8norcal]

^ yeah, that will be cool.



honda leaning motorbike?

http://www.autoevolution.com/news/honda-works-on-3-wheel-leaning-scooter-based-on-the-nc750-platform-91469.html#
http://blog.motorcycle.com/2015/01/21/design/honda-developing-leaning-three-wheeler/

 

[hodala]

My leaning trike front end kit production soon

 

[sk8norcal]

cool! that e-grom knock-off looks interesting

 

[sk8norcal]

Sway on shark tank

20:21
[youtube]c8xivMT_b04[/youtube]

 

[Willow]

interesting... have been following Joe for years, will be interesting to see what happens next.