Calculating Steering wheel angles

[Pauly]

With zero ackerman am just calculating steering angles using inv tan(L/R). where L is wheelbase and R is radius. This seems to be right. However for 100% ackerman I am having trouble. How do you go from 0% which I have calculated to calculating 100% ackerman?- obviously for inner wheel. AM trying to calculate 100% ackerman for R = 2.75m, L= 1525mm.

Thanks for the help

[Pauly]

With zero ackerman am just calculating steering angles using inv tan(L/R). where L is wheelbase and R is radius. This seems to be right. However for 100% ackerman I am having trouble. How do you go from 0% which I have calculated to calculating 100% ackerman?- obviously for inner wheel. AM trying to calculate 100% ackerman for R = 2.75m, L= 1525mm.

Thanks for the help

[Z]

Probably best to start with a sketch. If by 100% Ackermann you mean all 4 axles pointing to the same point then the "low G turn centre" will be on an extension of the rear axle line. If "R" is to the centre of the diff, and T = front track, then;

Tan(Angle-outer-front-wheel) = L/(R+T/2)
Tan(Angle-inner-front-wheel) = L/(R-T/2)

Of course, when cornering at high G's all the wheels will be running at a slip angle, about 3 to 6 degrees for each wheel. This puts the turn centre in front of the rear axle line. Type in "Ackermann/ackerman/steering/toe.." etc. under [Find] for more references.

Z

[Pauly]

Z,
Yeah thats what I thought I just assumed I was getting it wrong as was comparing my results with previous reports were they were getting crazy values liek 45 deg inner wheel for 100% ackerman on a 2.75m radius turn(dist to inside wheel).