Which Steering geometry you should use : Ackermann or Anti-Ackermann ?
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- Опубликовано: 28 авг 2024
- When you are cornering at high speeds ,then their is Lateral Load transfer and load on outer tire increases as compare to the inner tire of car .
This change in load on the tire causes the change in the slip angle of tire.
In this video you will learn about :-
1) Lateral force Vs slip angle curve.
2) Lateral Load transfer.
3) Tire load performance curves.
4) Ackermann and Anit-ackermann geometry
5) Which geometry you should choose ?
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![Use Slip Angles to Corner Faster [TIRES EXPLAINED]](/img/1.gif)
This is the only video on RUclips that I’ve found that explains the benefits of anti Ackerman. Thank you!
I designed and built 3 FSAE cars. Most of the ackerman videos give misinformation but
this video completely right.
Goog job !
Thanks man !
Hey so tell me if I need to choose between Ackerman and anti ackerman for my baja what should I choose
Baja vehicles, generally have maximum speed of 57km/hr ,and drivers do not corner at maximum speed .
So , at speed of about 45 km/hr to 57 km/hr their is less lateral load transfer in baja vehicles ,as compare to high speed cars .
So going for Ackerman at low speed corners would be better !
@@thevatsaljain ı agree that. At the same time ; when inner tire has more toe out (normal ackerman) , the tire creates more drag force (more steer angle more friction ). And this inner tire creates more yaw moment.
Okau that was great but the thing is I've seen some teams use anti ackerman get their vehicle turns for less than two feet turn i was amazed and I am really curious is that because of ackerman or is it because of the rack and pinion design
Oh Man! You and your videos are way underrated. Hope your channel reach heights soon. Keep up your good work.
Thank you so much !
i have one doubt. when does the second case of increase in vertical , decreses slip angle occur. I have heard only first case. please clarify this . i m a bit confused
Inner tire: Load decrease is the same as outer tire: load increased. You drew the same diagram and alphas, just different graphs and representations of the geometry on the car. What you really want is this:
Ackerman for low-speed steering not at the limits of grip, with low load transfer, and when desiring drivability, predictability, and low tire wear.
Anti-ackerman for high speed steering, pushing the limits of grip with high load transfer, when maximum steering force is required; but at the COST of tire wear.
Anti-ackerman is also ideal for drifting since it's a weird combination of inside tire load increased, but also low speed. You want the tires to track the corner correctly while the ass end is swung out, so yeah.
All the tyre profiles iv seen seem to match with case 1 how is case 2 possible ie. How can slip angle decrease with increase in lateral force please explain
How to design a steering geometry?
Like how to calculate steering arm length, angle of steering arm with knuckle and tie road length?
And how to reduce steering effort
Hi. So for a circle asphalt low downforce car on a small oval 0.25mile track going about 55-65mph around a low banked corner ONLY turning RIGHT. You would want anti Ackerman on the left front and Ackerman on the right front??
Nice video!!
1 question:
The difference between the two cases, depends on the tyre parameters?
Choosing Ackerman or Anti-Ackerman depends on Tyre parameters and also on the cornering of vehicle ,i.e whether their is high or low speed cornering and sharp turns or normal turns. It also depends on the position of roll center as if the roll center is at more distance from the center of gravity ,it will increase roll moment and this will increase the weight transfer,which leads to change in slip angles.
Very informative video!
Thank you for this very informative video! Could you please provide the name of the book and chapter where you got this explanation? I would need it for referencing purposes.
Glad you like it. Sorry, but I don't remember the book name right now.
For a SAE Formula Student vehicle which geometry is preferred and why?
Tire load performance curve is one of the criteria for choosing the type of geometry. For SAE formula student , or any other competition choosing geometry should depend on your tire load performance curve, load transfer characteristics, cornering speed, track characteristics ,required turning angle to achieve a required turning radius with specific wheelbase and track-width.
Why in anti Ackerman steering the outer wheel has more angle than the inner wheel
because the steering knuckle placed more outside of the kingpin axis (back placed steering rack) or the steering knuckle placed more inside of the kingpin axis (front placed steering rack)
For the second case the value of à1 is greater than à3.
But in image representation you have shown that à1
α(Slip angle) is shown on x axis, and that shows α3> α1. The curve is showing that α1 is achieved at maximum vertical load and α3 is achieved at minimum vertical load.
Nice video 👌 sir
Thank you !😃
This approach is over simplified. Do you really think that, for given tires you will get same Ackermann geometry if you have
- a different wheelbase
- a different radius
- a different yaw angle
- a different speed (and therefore a different yaw velocity)
?
A few additional and important comments:
1. Initial toe is important . The initial toe setup will be carried at all steering angles
2. Grip and balance are two different things. You could improve the front grip so much that it could create major oversteer
3. All these calculations could be be washed away one the compliance is considered
Remember that tires Fx and Mz will also play a role in the car balance
Great points! Ackermann geometry is indeed influenced by multiple factors like wheelbase, radius, yaw angle, speed, and more. Initial toe, grip, balance, compliance, and tire characteristics are all essential considerations. Thanks for highlighting these aspects!
Noice!
Must a new college graduate.