Coulomb and Viscous Friction (Simulink Reference)

Model discontinuity at zero, with linear gain elsewhere

Library

Discontinuities

Description

The Coulomb and Viscous Friction block models Coulomb (static) and viscous (dynamic) friction. The block models a discontinuity at zero and a linear gain otherwise. The offset corresponds to the Coulombic friction; the gain corresponds to the viscous friction. The block is implemented as

```
y = sign(u) * (Gain * abs(u) + Offset)
```

where y is the output, u is the input, and Gain and Offset are block parameters.

The block accepts one input and generates one output.

Data Type Support

The Coulomb and Viscous Friction block accepts and outputs real signals of type double.

Parameters and Dialog Box

Coulomb friction value: The offset, applied to all input values. The default is [1 3 2 0].
Coefficient of viscous friction: The signal gain at nonzero input points. The default is 1.

Characteristics

Direct Feedthrough
Yes

Sample Time
Inherited from driving block

Scalar Expansion
No

Dimensionalized
Yes

Zero Crossing
Yes, at the point where the static friction is overcome

Direct Feedthrough	Yes
Sample Time	Inherited from driving block
Scalar Expansion	No
Dimensionalized	Yes
Zero Crossing	Yes, at the point where the static friction is overcome

Cosine Counter Free-Running