MF-SWIFT/MF-Tyre Integration with MotionSolve

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:

1. A set of required markers.
2. One wheel/tire body per tire.
3. One revolute joint for wheel spin axis. Or, optionally, a bushing entity with very stiff rates in the non-spin direction and only damping in the spin direction.
4. One force entity that acts on two bodies of type “user”.
5. One array that contains properties relating to the tire.
6. One string entity for referencing the tire property file.
7. One string entity for referencing the road property file.
8. One state equation entity and related arrays for interfacing the tire states and tire outputs with the MBD model.

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 pointing to the left, the X axis in the plane of the wheel and oriented in the positive direction of travel, and the Z axis pointing up.

<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 the example below):

<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 “GFOSUB” or “mbdtire”. The parameters for the "USER" arguments are:

• par1: The routing ID (used only if the function name is GFOSUB).
• par2: The ID of the Force_Vector_TwoBody.
• par3: The ID of the Reference_Array used for the tire.

<Force_Vector_TwoBody
     id                  = "1"
     label               = "tire_handling_fr_AAAA_v05_0_swift.tir_wheel.force"
     type                = "ForceAndTorque"
     i_marker_id         = "1239"
     j_floating_marker_id= "1225"
     ref_marker_id       = "1223"
     usrsub_param_string = "USER(908,1,1078)"
     usrsub_dll_name     = "mbdtire"
     usrsub_fnc_name     = "GFOSUB"
/>

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

<Reference_Array
     id                  = "1096"
     label               = "tire_handling_rr_AAAA_v05_0_swift.til_wheel.input_array"
     type                = "IC"
     num_element         = "15">
   1.0950000E+03   4.0000000E+00   0.0000000E+00   9.4000000E+01   9.9000000E+01
   1.0200000E+02   1.0000000E+02   1.0100000E+02   3.1350000E+02   0.0000000E+00
  -1.0000000E+00   1.0970000E+03   1.0980000E+03   0.0000000E+00   0.0000000E+00

Element 5 above lists the ID of the string that contains the tire property file:

<Reference_String
     id                  = "86"
     label               = "tire_handling_fr_AAAA_v05_0_swift.tir_wheel.tpf_file"
     string              = "TNO_car205_60R15_swift_sin.tir"
/>

1. In the [MODEL] section, the attribute “PROPERTY_FILE_FORMAT” must be set to ‘SWIFT-TYRE’.
2. In the [MODEL] section, the attribute “FUNCTION_NAME” must be set to 'tnodelft::DTYRE'.
3. In the [MODEL] section, the attribute “ROAD_SOURCE” must be set to ‘TNO’. The attribute “ROAD_SOURCE” can have three valid options:
   • ROAD_SOURCE = ‘TNO’ – use MF-Tyre/MF-SWIFT internal road definition.
   • ROAD_SOURCE = ‘MBS’ – use road definition of MotionSolve.
   • ROAD_SOURCE = ‘USER’ – use user-written road.

Element 7 above lists the ID of the string that contains the road property file:

<Reference_String
     id                  = "87"
     label               = "tire_handling_fr_AAAA_v05_0_swift.tir_wheel.rpf_file"
     string              = "2d_flat_TNO.rdf"
/>

In addition to the above elements, a GSE (of type “USERSUB”) is required to interface the tire model with the MBD model. For example:

<Control_StateEqn
     id                  = "3"
     label               = "tir_wheel.tire_gse"
     type                = "USERSUB"
     x_array_id          = "1077"
     y_array_id          = "1076"
     u_array_id          = "1075"
     num_state           = "5"
     num_output          = "0"
     usrsub_param_string = "USER(908,1,1078)"
     usrsub_dll_name     = "mbdtire"
     usrsub_fnc_name     = "gsesub"
     usrsub_der1_name    = "GSEXX"
     usrsub_der2_name    = "GSEXU"
     usrsub_der3_name    = "GSEYX"
     usrsub_der4_name    = "GSEYU"
     is_static_hold      = "FALSE"
  />

1. The Control_StateEqn must be of type “USERSUB”.
2. The usrsub_param_string is of type USER (908, xxx, yyy) where xxx is the ID of the tire, yyy is the ID of the tire reference array. This must be consistent with the USER() string specified in the Force_Vector_TwoBody for each tire.
3. The usrsub_dll_name must be “mbdTire”.
4. The usrsub_fnc_name must be “gsesub”.
5. x_array_id points to the ID of an array that holds the tire states.
6. y_array_id points to the ID of an array that holds the outputs from the GSE (forces and moments).
7. u_array_id points to the ID of an array that holds the values of the input variables.
8. num_state lists the number of states for the tire. This is overridden internally.
9. num_output lists the number of outputs from the tire. This is also overridden internally if not equal to 6 (Fx, Fy, Fz, Mx, My, Mz).

The input variables are used to compute tire rim states. They are defined according to the following table:

USE_MODE specifies the type of calculation performed:

To use the MF-SWIFT tyre, you need to add “30” to the USE_MODE. For example, USE_MODE = 434 implies:

• combined slip
• rigid ring dynamics
• road contact for 2D roads

In addition to the regular tire requests that can be extracted in mbdTire, the TNO MF-Tyre/MF-SWIFT includes a few other requests that can be extracted using an mbdTire REQSUB with the following syntax:

<Post_Request
     id                  = "759"
     comment             = "road_contact_point_location_rear_LH"
     type                = "USERSUB"
     usrsub_param_string = "USER(902,reqType,tireId)"
     usrsub_dll_name     = "NULL"
     usrsub_fnc_name     = "REQSUB"
     cname2              = "X_rear"
     cname3              = "Y_rear"
     cname4              = "Z_rear"
     cname6              = "tire_radial_penetration_rear"
     cname7              = "tire_radial_penetration_velocity_rear"
     cunit1              = "no_units"
     cunit2              = "length"
     cunit3              = "length"
     cunit4              = "length"
     cunit5              = "no_units"
     cunit6              = "length"
     cunit7              = "velocity"
     cunit8              = "no_units"
  />

In the request element above, reqType can be: