### Rotary Tachometer

**Category: **Sensors

The Rotary Tachometer block models the behavior of a
tachometer generator using the standard ripple model. This block creates output
voltage signals proportional to input shaft velocity with ripple frequency
components. These components are a nonlinear function of the input shaft angular
velocity and number of commutator segments in the tachometer.

**Ripple Factor:** Indicates the tachometer ripple
factor in volts RMS.

**Commutator Segments**: Indicates the number of
tachometer commutator segments.

**Sensitivity**: Indicates the tachometer gain in
V/rad/sec

#### Example

**Diagram name:
**Rotary Tachometer

**Location: **Examples > eMotor > Sensor

The following simulation example shows velocity feedback
control of a permanent magnet DC motor. A load is coupled to the motor by a gear
ratio of 0.5, thus multiplying motor torque by a factor of 2. Load velocity is
measured by a tachometer with a ripple factor of 0.1 VRMS and 24 commutator
segments. The plot zooms in on the velocity as it approaches steady state (60
radians/sec). The ripple can be seen superimposed on the response.