Using Tires with MotionSolve

In some cases where you have a full vehicle model in the MotionSolve xml format and you want to manually enable it to use tires, the following information will apply.

MotionSolve Input Deck

Given a tire and road property file you can setup a MotionSolve input deck to include a tire (assuming you have a full vehicle without tires to start with).

There is a collection of solver entities required to enable a tire model. You can build up a vehicle model to utilize a tire model using the set of entities described below:

•	A set of required markers (Reference_Marker)

•	One wheel/tire body (Body_Rigid)

•	One revolute joint for wheel spin axis, or optionally a busing entity with very stiff rates in the non-spin direction and only damping in the spin direction (Constraint_Joint) or (Force_Bushing)

•	One force_vector_twobody of type "User" (Force_Vector_Twobody)

•	One reference_array (Reference_Array)

•	One string entity for .tir file (Reference_String)

•	One string entity for .rdf file (Reference_String)

A marker is required, located at the wheel center and attached to the ground body. This is a floating marker that will stay superimposed on the marker used to define the tire force.

<Reference_Marker

id = "11001020"

label = "Front Tire J Marker-left"

body_id = "30101"

body_type = "RigidBody"

pos_x = "1000."

pos_y = "-750."

pos_z = "1000."

A road reference marker is required to define the height of the road. This marker is attached to ground.

<Reference_Marker

id = "11001010"

label = "Road Reference Marker Front-left"

body_id = "30101"

body_type = "RigidBody"

pos_x = "0."

pos_y = "0."

pos_z = "680.03"

A marker is required for the action-reaction tire force. It is attached to the wheel/tire body and oriented with the y axis along the spin axis.

<Reference_Marker

id = "11003020"

label = "Front Tire Force Reference-left"

body_id = "10403"

body_type = "RigidBody"

pos_x = "1000."

pos_y = "-750."

pos_z = "1000."

a00 = "-1."

a10 = "0."

a20 = "0."

a02 = "0."

a12 = "0."

a22 = "1."

The model must contain a wheel body and a revolute joint between the wheel body, and another part of the vehicle model. The revolute joint should be aligned to represent the spin axis of the tire (see example below):

Note	A bushing can be used in place of the revolute joint, however this is rarely used.

<Body_Rigid

id = "10403"

label = "Wheel-left"

cg_id = "10403010"

im_id = "10403010"

lprf_id = "10403001"

mass = "36."

inertia_xx = "1750000."

inertia_yy = "1750000."

inertia_zz = "1000000."

v_ic_x = "-24587.2"

v_ic_y = "0."

v_ic_z = "0."

w_ic_x = "0."

w_ic_y = "0."

w_ic_z = "-76.842204"

v_ic_x_flag = "TRUE"

v_ic_y_flag = "TRUE"

v_ic_z_flag = "TRUE"

w_ic_flag = "TRUE"

<Constraint_Joint

id = "104002"

label = "Wheel spindle rj-left"

type = "REVOLUTE"

i_marker_id = "10404020"

j_marker_id = "10401020"

The input deck then requires a Force_Vector_TwoBody force (action-reaction force) of the type "User". The usrsub_dll_name must be “mbdtire” and the usrsub_fnc_name must be “mbdtire”. The parameters for the "USER" arguments are:

-	par1: The routing ID (not needed as long as fnc_name is"mbdtire").

-	par2: The ID of the Force_Vector_TwoBody.

-	par3: The ID of the Reference_Array used for the tire.

-	par4: In the case where co-simulation tire is used, this is the order of the interpolating polynomial between subsequent evaluation of forces at integrator convergence. Set to 0 for zero order hold, or 1 for first order hold.

<Force_Vector_TwoBody

id = "11001"

label = "Front tire force-left"

type = "ForceAndTorque"

i_marker_id = "11003020"

j_floating_marker_id= "11001022"

ref_marker_id = "11001010"

usrsub_param_string = "USER(408,11001,31000100,0)"

usrsub_dll_name = "mbdtire"

usrsub_fnc_name = "mbdtire"

Many of the required values for the tire are stored in the Reference_array from par3:

<Reference_Array

id = "31000100"

label = "Front tire input array left"

type = "IC"

num_element = "7">

0.0000000E+00 1.8000000E+01 0.0000000E+00 3.1000900E+05 3.1000100E+05 3.1001100E+05 3.1000500E+05

</Reference_Array>

Num_element must be seven; however the only two that currently apply are element 5 and element 7 (the others are reserved for future use).

Element 5: The ID of the string that contains the tire property file (see example below):

<Reference_String

id = "310001"

label = "Front left tire property file string"

string = "prop_files/ftire.tir"

Element 7: The ID of the string that contains the road property file (see example below):

<Reference_String

id = "310005"

label = "Front left road property file string"

string = "prop_files/2d_road.rdf"

Using Tires with MotionSolve

Using Tires with MotionSolve

Using Tires with MotionSolve

MotionSolve Input Deck

See Also: