Non-welder looking for help and advice.

[Luke]

Using hand levers, generating enough force is one thing, what about holding it?

Once you're on a tack, you may well have the wheel in the same position for quite a few minutes, that's going to hurt!

 

[knoba]

The friction could be used to our advantage; the linkages could have a variable friction device to allow adjustment of the steering cable drag. Adjustments can then be made, and held, relatively easily. Or, alternatively, a lock & ratchet system like they have on bicycles for changing gears. Which pretty much, comes down to a blending of the two ideas, on the mat!

Sorry Andy, we're fighting... errr, I mean, discussing, yes... discussing, the merits of each system.

Luke - I like your ideas! It's going to come down to Andy's preference...? If you can visualise each system Andy, what "user interface system" do you think would (ideally) work best for you? Then... where to go from there!

BTW; I have ZERO knowledge about kites and sailing. I'm a surfer & I like boarding!

 

[Luke]

Sorry Andy, we're fighting... errr, I mean, discussing, yes... discussing, the merits of each system.

That's what the design process is all about. as long as it's productive and non-bitchy, it works for me, and hopefully Andy too.

 

[knoba]

Luke

That's what the design process is all about. as long as it's productive and non-bitchy, it works for me, and hopefully Andy too.

Luke - Great stuff!

Where are we...?

User interface preference! ...I wonder, if it's worth taking these ideas to a kite/buggy forum to elicit views from the members on the various designs and see what they have to say, and what system they would seem to favour?

 

[wheelchair andy]

I'm torn between the two. Having levers on the control bar really would be ideal if they give the proper amount of control.

The central lever as illustrated by luke is the simplest method and ensures I have control over the speed of turns, but it's major drawback is that to turn I'll be left controlling the kite one handed, just at the very moment that requires the most movement and control of the kite!

The kite control bar requires complete freedom of movement, so attaching it to a rod and steering the kite and buggy that way wont work.

I'd really like to explore the possibility of using the levers and cables. I know nothing about the mechanics of linkages, variable friction devices or any other crazy voodoo stuff at all, if it's possible then it would be absolutely ideal.

The front wheel on a buggy certainly has a range of movement of around 90°, most likely around 80° in reality.

Some high speed turns require going into full left lock and then straight into full right immediately, will levers allow this range and speed of movement?

 

[Luke]

The thing that concerns me with bike style brake levers is the fact you'll already be trying to pull the kite bar - Riding a bike, your hands typically rest on the handle bar, you're not pulling back on it.

I think pulling on the 'handle bar' and pulling the brake levers as well will be troublesome. I think you won't be able to hold the brake levers without pulling them hard on - or if it makes more sense, you holding the levers still and the kite pulling the bar away from you - same thing.

If someone fancies hanging their bike from the ceiling and trying it as a test, that'd be cool

 

[knoba]

I've always found it's best to shoot for the ideal and try to eliminate all (or at least, reduce) compromises.

The bar could have retaining straps (metal <-> velcro) to keep the hands in a set position, along the bar, and over the levers. The handbrake cables would come off the kite bar, feed back, down your lower arms (secured by Velcro strips). They would then be fixed to the original chassis leading to the steering horns.

wheelchair andy

The front wheel on a buggy certainly has a range of movement of around 90°, most likely around 80° in reality.

Some high speed turns require going into full left lock and then straight into full right immediately, will levers allow this range and speed of movement?

Possibly, it now comes down to the physics & maths! Unfortunately, I'm crap at both of them! The only way I have of doing this side of design/manufacture is just by looking at the viability of an idea, making a call on whether it's possible and then sorting out issues as I go along (mad inventor stylee). I'm sure someone else on here will know how to do the maths.

It should be noted that; you have v. strong hands?

I'll try to draw out the system tomorrow (on laptop at mo), as I see it, then throw it back on here for "a good discussion" from the members.

 

[knoba]

The design has come far;

• The available wheel lock, from L/H to R/H, has been established (90 degrees).
• Picture of the Kite Control bar is available (I have no idea how the actual kite works!).
• Most Importantly; the user has stated a preference that the steering control mechanism would, ideally, be kept with the kite control bar.

While I was re-thinking the lever design today; I had concerns that although most of the issues could be overcome, it worried me that there would not be enough cable movement, to turn the wheel to a great enough degree. It also struck me that the lever design wasn't a very elegant solution and the design should work, completely, for the user.

I must say, I'm finding it incredibly hard to convey these designs in a legible way. ...Anyway, I came up with this (sorry my drawing isn't as good as Luke's excellently rendered idea). ;

FRONT OF BUGGY
View attachment TwistStyle.bmp
BACK OF BUGGY

The perspective is from the cockpit looking forward.

• Red = Kite Control Bar
• Dark Blue = Kite Control Lines
• Light Blue = Safety Harness to prevent loss of control bar when released.
• Green = Twist Grips
• Orange = Steering Control Cables (crossover on chassis rail)

OK... I'll try to explain my warped vision...
The (Green) twist handles are rather similar to motorcycle accelerator grips (eg. when twisted one way they increase the engines speed, when twisted the other way they decrease the engines speed). A lot of; speed, torque (twisting force) & cable movement is available through this arrangement. They are also very easy to hold in the correct position and are comfortable for long periods of time.

I would propose that each grip has an internal mechanism that controls two sets of cables (one cable goes to the left hand steering arm and the other cable goes to the right hand steering arm from the same grip. ...and a similar set-up for the other grip too). This system relies on the kite being under load in order to control the steering.

What it should be like in practice, is the user holding onto the grips (controlling the kite normally by pulling either end, of the kite control bar, backwards or forwards) whilst simultaneously twisting both grips in unison (both in the same rotational direction) to turn the steering, one way, or other.

If a greater degree of steering movement is required, it would be possible to slightly loosen one hand to achieve a greater purchase, twist further, and then let the other hand catch up.

I also think that, it might be possible, if the cabling was correctly set-up, that it would be possible to steer the buggy and fly the kite, without thinking about it at all. I think this design is a definite go-er and may possibly be easier than the current foot control system when in actual use.

Most of the design / production costs would be in the control bar. Whereas; very few modifications would be needed to the actual buggy itself.

What do you think? Have I explained it well enough? Any other ideas? Or improvements to this system?

 

[wheelchair andy]

I thought I should explain the kite control bar a bit more. Some are more simple than others, but this is a pretty good example:

So the bar itself is pretty simple, with the steering lines on each end and the control lines in the center.

The central control lines are basically brake lines attached to the trailing edge of the wing and used to collapse and de-power the kite rather than steer.

The 'chicken loop' is a way of connecting the bar to a harness, or in my case to the buggy itself, so that the arms aren't taking the full strength of the kite.
It has a quick release system so that you can.............quickly release yourself from the kite if needed

When this happens, the elasticated tether that connects you and the control lines stays connected, immediately collapsing the kite so it's no longer dragging you around and creating a scene.

So looking at the control bar it looks like a perfect place for some levers to control steering, but because the bar has to keep the ability for quick release, maybe the brake cables would get in the way and cause a safety issue.

 

[jugs]

QUOTE]

Andy, if you look like that, you can fly into my backyard any day

 

[knoba]

Is the rider not strapped into the buggy, by a safety harness, Andy? Or... let me re-phrase the question several ways;;

Is it likely that the rider will have to release themselves from the buggy, during a ride, in order to abort?
Are you also saying that; if the rider was pulled out of the buggy, the kite would then drag the buggy (and rider) because of the proposed steering cables?

 

[Drains]

Andy, can we just confirm the limits of your movement? eg Arms 100%, waist x%, legs x%?

The reason I ask is I wonder how much stomach/waist movement you have, as it may have a bearing on other possible solutions.

There is another arm-only solution that occurred to me, which is to rig the bar (above) to a forward/reverse joystick. Or for that matter a left/right joystick. With the left/right joystick you would have two ranges of movement - one to steer by swinging left, right, the other to control the kite, pulling in, left/right. Only rigging this up would prove whether you could control the swing of the kart steerage, against the force of the kite. The geometry to balance the forces might be interesting, if at all possible.

 

[knoba]

Good Kite buggying research video here.

 

[knoba]

Here's another hand only idea... Using a similar set-up to the differential cage found in an axle; the user would twist the kite control bar (holding onto the half-shafts). A portion of the bar would remain static (axle casing), held by the kite, while. a take-off shaft from one the planet wheels would provide the necessary motive force to convert the user's twisting movements to the steering assembly.

Lot's of; torque, great potential for wide steering movement and very responsive.

Needs a torsion cable drive from control bar to steering linkage. But, it would be much easier to use a single quick connect / disconnect cable interface (if necessary?).

 

[drjim]

That's a pretty good idea

 

[Luke]

Lots of torque

Really? I don't think so......

Given we're after 80 degrees of steering lock, and the human wrist offers about 100 degrees of lock, you're basically asking the user to steer the front wheel by turning it by hand abouts its axis, on a 50mm (say) shaft.....

Same holds for your other idea. Wirsts just aren't powerful enough in my opinion. (ahem)

 

[knoba]

Luke

the human wrist offers about 100 degrees of lock

...so 2 (2 hands) offer 200 degrees, add to that shoulder & arm movement ...say 240 degrees potential. Realistic steering range = 80 degrees. 3:1 ratio.

Also Andy's wrists are going to much stronger than most peoples.

It's nice to see you back though Luke!

 

[Luke]

eh?! have you actually looked at what 240 degrees looks like?

How are you supposed to do anything like that whilst still controlling the kite in a sensible manner.

With a differential (if that's what you propose) twisting the half shafts in opposite directions would result in zero rotation off the diff "input shaft".

Rotating both hands together would inevitably result in the control bar being moved in space - upsetting the kite. Again, in this situation, you aren't just resisting the force at the wheel, but also the force due to the control lines.

 

[Luke]

New idea.

Turn the buggy round. the front wheel becomes a rear trundle wheel - leave it to it's own devices.

Fiddle brakes on each of the front wheels would give you steering ability, and would require much less force, as you're only dealing with actuating a calliper.

It still remains to be seen if you can squeeze levers whilst hanging on to the bar. At least with this scenerio you are within the realms that bike brakes were designed for

 

[madkayaker]

Luke that really is thinking out of the box like the idea. If it wasn't possible to pull a brake while hanging on for dear life and filling the undercarriage with some thing smelly could go to Knoba's idea of twist grips for the brakes