Steering theory...

Tips and tricks about building a car. painting it a making it run smooth.
acboother
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Joined: Wed 25. Oct 2017 07:27

Steering theory...

Post by acboother »

Apologies once again for being a noob.

I'm trying to understand the theory behind the steering. As I think I understand it the car is steered by the magnet following the wire.

Originally the steering was pulled off line by solenoid(s) and when the track wire 'broke' these solenoids had enough umph to pull the steering to one side or the other. The wire would be seen by the steering magnet once again and would take over steering control (even if the steering solenoid was activated?).

Now there is a small servo. This is where I get need confirmation or otherwise... The magnet between the servo arm and the steering has to be weak enough to allow the magnet following the track wire to move? Is it the case that when the servo is moved the track magnet following the wire is still strong enough to keep the car on track? When the car passes the break in the track wire the servo magnet now takes control of the steering until the car comes back to the track wire?

If this is the case, in the case of a servo, then the steering magnet has to do the steering and 'fight' the servo magnet.

Am I on the right track (no pun intended).

Cheers
Alan
kiklo
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Re: Steering theory...

Post by kiklo »

At percent there are 3 different steering setup. (That I know of.)

Mag1 the original.
Mag2 from magneticracing with servo. And Neds cars.

My own also using servo but a in a different way. Look at my 'KK-proto' posts.

But all use the same steering-pivoting guide under the cars.
Racing Regards

Kim K.
acboother
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Joined: Wed 25. Oct 2017 07:27

Re: Steering theory...

Post by acboother »

I've seen your video and it's a bit tricky to work out for certain what's going on but is it this?

There is a linear servo which actuates the steering and works against repelling magnets rather than an attracting magnet in the traditional servo design?

As I mentioned in the lap-counting thread I think I'll go down the route of reusing the technology I already have.

My initial thoughts are to have the steering magnet directly attached to the steering (as all the others appear to be). The overriding steering control will be done with a small coreless motor acting directly on the steering as well. When not powered the motor is almost totally free to rotate so the steering magnet needs only to work on the steering and not fight against a servo magnet. When powered it will pull the steering one way or the other. May even be possible to make it strong enough that a track break isn't required and lane changing could happen anywhere... (if that's desirable even).

Cheers Alan
kiklo
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Re: Steering theory...

Post by kiklo »

Yes I'm using repelling magnets.
And have tested with both linear and rotary servos.
And bye tuning the magnet-arm i can override track-magnet at any time if I like.

Your idea of a small motor is interesting - but that is really what the servo is ??? How will you control the rotation ?

It will be interesting to have a look when you have a drawing or a prototype.
Racing Regards

Kim K.
kiklo
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Re: Steering theory...

Post by kiklo »

http://magracingforum.com/viewtopic.php?f=6&t=724#p4469

This shows the steering - but I think the rotary servos are even better.
Racing Regards

Kim K.
kiklo
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Re: Steering theory...

Post by kiklo »

I was intrigued by your steering suggestion. Trying to figure out what you where thinking of .

Something like this ?

Having the steering-guide direct one the motor axle ?
dir-drive.jpg
dir-drive.jpg (28.14 KiB) Viewed 9675 times
Racing Regards

Kim K.
acboother
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Joined: Wed 25. Oct 2017 07:27

Re: Steering theory...

Post by acboother »

Here is the best I can do for the moment about the coreless steering motor.

It is the remains of an experiment into making a lane change feature for slot cars. The motor and link between the steering knuckles have been removed - probably for another project!

I stopped the slot car lane change when I wanted to experiment with different designs of 'junction'. This I felt was going to be critical so I was going to laser cut them for accuracy and speed of producing them... and then I lost access to the laser cutter. Having done routing by hand I didn't fancy doing it for the slotcar project :(

Image
acboother
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Joined: Wed 25. Oct 2017 07:27

Re: Steering theory...

Post by acboother »

And here are two steering front ends I designed/3D printed. One is rather inside out (ackerman wrong!) however these were part of the push car experiment plus I wanted to get the wheel king pin axis in the centre of the wheel to minimise the negative steering effect of hitting a bump in the road. Fitted slotcar aluminum wheels inside out and they fitted right inside :)

I suspect a little bit of offset would help.

Also had/have a design for a macpherson strut style where one pivot is above the wheel and one in well of the wheel.

Image
WesR
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Joined: Fri 21. Dec 2012 17:37

Re: Steering theory...

Post by WesR »

I spent many hours working on r/c operated lane changing for slot racing. The one unsolvable problem was that no matter how sharp a point you have in the track frog, where the slots join, and no matter how sharp a point you have on the car steering flag, on some occasion these two will collide head on! This may only happen once every 100 times but, if you have ten lane change points around your track, this could happen perhaps every ten laps. With disasterous consequences!
Hence Magracing.
I think Alan probably understands all now but one aspect which many people don't understand is that, because remote human drivers are not capable of operating the steering exactly at the point of the lane change, it is necessary to be able to turn well before the lane change and hold until after the lane change.
This of course is similar to digital slot racing except that we have a much more realistic steering wheel instead of a button!
And we can drive back onto the track after an 'off', and we can reverse, and..... etc. etc. etc.
acboother
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Joined: Wed 25. Oct 2017 07:27

Re: Steering theory...

Post by acboother »

Biggest concern was hitting the divide between left and right lane.

I'd anticipated many iterations of a split/change lane design having to be made and tested and IF it was possible it would have been fractions of a millimeter between working and not working. I didn't relish making these and know they wouldn't be accurate if I made them by hand hence the laser option. Almost glad the laser 'evaporated' before I spent too much time on this one.

My starting point was to have the guide biased to one direction...
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