Curb to Curb Diameter and Ackerman 3 and 4

Branch ID: 300 Request Number: 50000300

Table 1.
Component Unit Comment
1 (X): Not Used Not Used Not Used
2 (Y): Percent Ackerman (Method 3) % The third method of calculating percent Ackerman. Ackerman is used to quantify the amount of scrubbing occurring on the front of the vehicle during a turn assuming no rear wheel steer. A vehicle whose front wheels are parallel (the same steer angle) has 0% Ackerman. Conversely a vehicle is said to be 100% Ackerman when the lines through the left and right spindle axes intersect in the top view at a lateral line passing through the rear wheel centers. The following equation is used to calculate percent Ackerman with Method 3. See Component 1 above for intermediate term calculations.
When the Vehicle is Steering Right

outer = abs((left toe-in)/rtod)

inner = abs((right toe-in)/rtod)

percent Ackerman = (wheel base)*(atan(inner)-atan(outer))*100/ ((right spindle at kingpin y)-(left spindle at kingpin y))

When the Vehicle is Steering Left

inner = abs((left toe-in)/rtod)

outer = abs((right toe-in)/rtod)

percent Ackerman = (wheel base)*(atan(inner)-atan(outer))*100/ ((right spindle at kingpin y)-(left spindle at kingpin y))
3 (Z): Not Used Not Used Not Used
4 (RX): Curb to Curb Diameter (Method 4) m The fourth method of calculating the approximate diameter of the circle the vehicle would move around at the current steer angles assuming no rear wheel steer.
When the Vehicle is Steering Right

outer = abs((left toe-in)/rtod)

inner = abs((right toe-in)/rtod)

turn radius = (wheel base)*(1/tan(inner)+1/tan(outer))/2

ctoc diam = 2*sqrt(((turn radius)+track/2)^2+ (wheel base)^2)/1000

When the Vehicle is Steering Left

inner = abs((left toe-in)/rtod)

outer = abs((right toe-in)/rtod)

turn radius = (wheel base)*(1/tan(inner)+1/tan(outer))/2

ctoc diam = 2*sqrt(((turn radius)+track/2)^2+ (wheel base)^2)/1000
5 (RY): Percent Ackerman (Method 4) % The fourth method of calculating percent Ackerman. See Component 2 above for an explanation of Percent Ackerman. See Component 4 above for intermediate term calculations.
When the Vehicle is Steering Right

alpha = atan((wheel base)/((turn radius)+track/2))

percent Ackerman = (inner-outer)*100/(atan((wheel base)/ ((turn radius)-(right spindle at kingpin))) -atan((wheel base)/((turn radius)+ (right spindle at kingpin))))

When the Vehicle is Steering Left

alpha = atan((wheel base)/((turn radius)+track/2))

percent Ackerman = (inner-outer)*100/(atan((wheel base)/ ((turn radius)+(left spindle at kingpin))) -atan((wheel base)/((turn radius)- (left spindle at kingpin))))
6 (RZ): Ackerman Deviation (Method 4) deg The fourth method of calculating Ackerman deviation. Ackerman deviation, like percent Ackerman is used to quantify the amount of scrubbing occurring on the front of the vehicle during a turn assuming no rear wheel steer. Zero Ackerman deviation means that lines through the left and right spindle axes intersect in the top view at a lateral line passing through the rear wheel centers. The following equation is used to calculate Ackerman deviation with Method 4. See Component 4 above for intermediate term calculations.

deviation = (outer-alpha)*rtod