Sine Generation

System identification through frequency response is a common method for deriving a mathematical transfer function model of an open-loop system. To obtain frequency response data, it is essential to apply a sinusoidal signal to the input. This can be done using the StartController function.

This function takes a SineCommand as its argument, which includes the following parameters:

• axis: Specifies the axis to control. The interpretation of the controller output depends on the axis’s command mode.

• frequency: The frequency of the sinusoidal signal, in Hz.

• amplitude: The amplitude of the sinusoidal signal.

Open-Loop System Configuration

Although sine wave generation can be used in a closed-loop system, it is primarily intended for system identification in open-loop configurations. To configure an open-loop system for this purpose:

1. Set the following parameters to zero:

• offset

• integralGain (Integral gain)

• derivativeGain (Derivative gain)

1. Set the proportional gain proportionalGain to 1.

2. Disable sensor feedback by setting sensorType to None.

The following diagram illustrates this open-loop configuration:

Frequency Response Modeling

To perform frequency response modeling:

• Use controlOutputOffset to define the operating point.

• Sweep or vary frequency to introduce small sinusoidal perturbations to the system.

You can collect and analyze the response data using the Motion Scope or log module APIs.