Re: car's trajectory

It's not TRACKS. It's AXLE centerl Nonsense. When the car is travelling straight the axle centerlines are parallel and therefore do not meet (by definition of parallel). _________________________________________________________

Your email suggests that you are a student of physics. Ask your instructor to explain the concept of the limiting case of an arc's trajectory as its radius approaches infinity.

Rodan.

t.

to elaborate, the centerline of the rear axle and the centerlines of each front spindle all meet at a common point. As the vehicle travels a path closer to straight ahead, that point becomes increasingly distant from the vehicle itself, and when the vehicle is in actuality traveling perfectly straight ahead, that point is infinitely far away.

nate

to elaborate, the centerline of the rear axle and the centerlines of each front spindle all meet at a common point. As the vehicle travels a path closer to straight ahead, that point becomes increasingly distant from the vehicle itself, and when the vehicle is in actuality traveling perfectly straight ahead, that point is infinitely far away.

nate

=============================================== The centerlines of each front spindle do NOT meet at a common point shared by the rear axle except for one identifiable and particular turning radius, as shown here:

In a 100% Ackermann geometry system, they do - at ALL turning radii. I'm not sure what the heck your diagram is supposed to show, but it appears to be a car that changes between cornering correctly and scrubbing the hell out of the tires.

nate

| >>| | >>| You claimed that the tracks of the tires all pointed | >>| to a single point. Put up the math (including the | >>| geometry), 'cause i do not think it can be done. | >>| __________________________________________ | >>| | >>| It's not TRACKS. It's AXLE centerlines that all meet at a single point. | >>

| >>Nonsense. When the car is travelling straight the axle centerlines | >>are parallel and therefore do not meet (by definition of parallel). | >

| >

| > to elaborate, the centerline of the rear axle and the centerlines of | > each front spindle all meet at a common point. As the vehicle travels | > a path closer to straight ahead, that point becomes increasingly | > distant from the vehicle itself, and when the vehicle is in actuality | > traveling perfectly straight ahead, that point is infinitely far away. | >

| > nate | >

| > =============================================== | > The centerlines of each front spindle do NOT meet at a common point | > shared by the rear axle except for one identifiable and particular turning | > radius, as shown here: | >

| | In a 100% Ackermann geometry system, they do - at ALL turning radii.

When the car is travelling straight the axle centerlines are parallel and therefore do NOT meet (by DEFINITION of parallel).

Your argument fails because infinity is not defined, try dividing by zero on any calculator.

| I'm not sure what the heck your diagram is supposed to show,

Ok, so you are just another unintelligent argumentative f*****ad I should not waste my time on. *plonk*

I'm merely repeating the *definition* of Ackermann geometry. The fact that you can't handle a piddly little infinity is of little concern to me. Since "going straight" can easily be reworded as "an infinitely large turning radius" I don't see any kind of issue with allowing the distance from the vehicle of the intersections of all the turning radii to go to infinity as well. As soon as you deviate, even slightly, from straight ahead, you can find the intersection point clearly defined - even if it is miles away (this is assuming, of course, an idealized vehicle with no slop anywhere in the steering linkage.)

If you think about it, the Ackermann principle is very simple... assuming zero slip angles at all tires (which is the assumption that the whole principle is based on, and also why in some applications engineers choose to ignore or modify it) BY DEFINITION the centerlines of the spindles/axles have to meet at a common point for any non-zero turning radius, as the vehicle is a single mass and therefore when turning has to describe an arc with a single center. The zero slip angle assumption defines the direction of travel of each wheel as being at an angle of 90 degrees from a line drawn from the center of that arc. Therefore indeed lines drawn perpendicular to the direction of travel of each wheel, or in other words, the centerlines of the spindles or axles, MUST meet at a common point.

yeah, I guess all those years messing with cars and taking engineering classes makes me supremely unqualified to talk about something as basic as Ackermann steering.

Why don't you DAGS for the definition of Ackermann steering and then come back and apologize for your rudeness?

nate

So you have two steering wheels, one for each front wheel?

In every car i have ever seen, turning the steering wheel turns *both front wheels....

turning

Hi guy, In the car, yes only one steering wheel, but according to the angles of the wheels, it is like having 2 steering wheels, one for each wheels angle. The combination of steering linkage and front end parts (ball joints, arms etc..) create two different angles while it turns the wheels.

And also the limiting case as the distance to the point of crossing approaches infinity. Infinity is not a quantity, but the limit of a function as a parameter approaches infinity can be a quantity. For example, Lim(1/n) as n approaches infinity is zero. Lim (1/n +1) as n appoaches infinity is 1. One and zero are both quantities.

Same applies in trigonometry as the length of the leg of a triangle approaches infinity, which is basically what Nate is saying.

Infinity IS quite clearly defined, for anyone who's had a math class beyond 8th grade algebra. The fact that it isn't a quantity doesn't make it any less defined, and equations are written in terms of limits approaching infinity all the time.

Oh, get over yourself.

I'm torn on whether this would sound better as done by Rowan Atkinson in his best Blackadder voice (the world-weary series 4, perhaps) or by the late Graham Chapman as, say, Yellowbeard.

John Travolta as Chief of Security Terl in Battlefield Earth: A Saga of the Year 3000. Or, better yet, Dan Haggerty as the voice of Terl in Battlefield Earth: The Anime Series. Unless, of course, the rumored Chinese version with Chow Yun Fat voicing Terl actually exists...

You just can't beat a nine foot tall alien Psychlo with hoses up his nose when you *really* want to express disdain for a lesser being.

Could you redo the .gif so that it shows how both wheels turn? As it is now, it shows one front wheel turning while the other does not turn. You need to show both turning -- possibly at different rates/angles, but still both turning at the same time.

BTW, what app are you usintg to g=create the .gif files? I really like the look.

That was made by Androcles, If he gets bored enough he might make another one if he sees the request. :)

I've used this in the past, back when it was just shareware:

I don't know if they still have a "free" version.

Cheers! Rich