WOLFRAM SYSTEM MODELER

# RollingResistance

Resistance of a rolling wheel

# Wolfram Language

In[1]:=
`SystemModel["Modelica.Mechanics.Translational.Components.RollingResistance"]`
Out[1]:=

# Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

Simplified model of the resistance of a rolling wheel, dependent on vertical wheel load (due to gravity, i.e. static only), inclination and rolling resistance coefficient:

```flange.f = Cr * fWeight * cos(alpha)
```

The rolling resistance coefficient Cr is either constant (given by the parameter `CrConstant`) or prescribed by the input `cr`.

The inclination is either constant (parameter `inclinationConstant`) or prescribed by the input `inclination`. This corresponds to the road rise over running distance of 100 m which, in general, is written as a percentage and is equal to tan(α). For example for a road rising by 10 m over 100 m the grade = 10 % and, thus, the inclination is 0.1. Positive inclination means driving uphill, negative inclination means driving downhill, in case of positive vehicle velocity.

#### Note

The rolling resistance is independent of velocity here, but changes its direction with the direction of velocity. To avoid numerical problems around zero velocity, the rolling resistance is regularized accordingly within `[-v0, v0]`. Therefore static friction at vehicle's standstill is not taken into account.

# Parameters (8)

useSupport Value: false Type: Boolean Description: = true, if support flange enabled, otherwise implicitly grounded Value: Type: Force (N) Description: Wheel load due to gravity Value: false Type: Boolean Description: Enable signal input for Cr Value: 0.01 Type: Real Description: Constant rolling resistance coefficient Value: false Type: Boolean Description: Enable signal input for inclination Value: 0 Type: Real Description: Constant inclination = tan(angle) Value: Modelica.Blocks.Types.Regularization.Exp Type: Regularization Description: Type of regularization Value: 0.1 Type: Velocity (m/s) Description: Regularization below v0

# Connectors (4)

flange Type: Flange_b Description: Flange of component Type: Support Description: Support/housing of component Type: RealInput Description: Inclination=tan(angle) Type: RealInput Description: Rolling resistance coefficient

# Used in Components (1)

 Vehicle Modelica.Mechanics.Translational.Components Simple vehicle model