How is "toe angle" defined in suspension module?

Hi,

I'm now working on the modelling of an independent suspension with Vehicle Dynamic Blockset and I've got a bit confused by the definition of the toe angle.

Formerly I believed that the toe angle is the angle of the left and right wheel when observed from the top. Therefore, a subtraction between the steering angle of the two wheels should yield the toe angle according to my experience on ADAMS Car. However here in the suspension module it seems that the calculation of the "toe angle" on each wheel is handled seperately and I've got no idea how it works.

I wonder how the "toe angle" is defined in the suspension module and how the value is taken into the calculation of the angle between the wheel and the axle.

Furthermore, I've found out that the output toe/camber angle from the "info" port doesn't completely match the output from the "WhlAng" port, e.g. on the "info" port the toe angle values of the two wheels on the same axle have different signs while the values from the "WhlAng" port have the same one. How are they defined?

I'd appreciate it if someone could provide some information. Thanks!

Answer 1

[Manikanta Aditya]

Hi,

As per my understanding, you would like to know how toe angle is defined in suspension module.

Toe angle is defined as the angle between the longitudinal axis of the wheel and the direction of travel when observed from the top. In the Vehicle Dynamics Blockset, toe angle is calculated separately for each wheel and is defined as the angle between the tire plane (the plane perpendicular to the direction of travel) and the longitudinal axis of the wheel.

In the independent suspension module of Vehicle Dynamics Blockset, the toe angle is calculated based on the position and orientation of the suspension links, as well as the position of the wheel centre. The calculation considers the motion of the suspension and the steering angle of the wheel. The exact calculation depends on the type of suspension model used.

Regarding the difference between the output of the "info" port and the "WhlAng" port, "info" port provides information about the suspension geometry, including the position and orientation of the suspension links and the tire contact patch. The "WhlAng" port, on the other hand, provides the actual wheel angles, which are the angles between the longitudinal axis of the wheel and the direction of travel, as measured by sensors on the vehicle.

After a quick google search, I found this article related to methods to control the toe angle and chamber angles:

• https://patents.google.com/patent/US9216625

I hope this resolves the issue you are facing.