Actual Jerk Filter

Type:	Axis Parameter Register
RMC70 Address:	Primary Input: Fn:5, where n = 12 + the axis number Secondary Input: Fn:23, where n = 12 + the axis number
RMC150 Address:	Primary Input: Fn:5, where n = 24 + the axis number Secondary Input: Fn:23, where n = 24 + the axis number
System Tag:	Primary Input: _Axis[n].JerkFilter Secondary Input: _Axis[n].SecJerkFilter where n is the axis number
How to Find:	Axes Parameters Pane, All tab: Feedback → Filtering/Modeling
Data Type:	REAL
Units:	Hz
Range:	0 (Off) or greater than 0.01
Default Value:	25

Description

This parameter specifies the cut-off frequency of the Actual Jerk input filter in hertz. The filter is a low-pass fourth order Butterworth filter.

For most position or velocity control applications, there is no need to change this parameter from its default setting. Setting the Actual Jerk Filter to zero (0) disables the filter.

This filter will apply to both the Actual Jerk status register and the jerk value used by the higher-order Active Damping and Acceleration Control algorithms.

Limits

The filter frequency range is limited to greater than 0.01 due to inaccuracies in the calculations for lower values. The filter is disabled (without notice to the user) when the frequency is set above 1/4 the sample frequency (500Hz for 500us loop, 250Hz for 1ms loop, 125Hz for 2ms loop, 62.5Hz for 4ms loop).

Why Bother?

Filtering makes the plots look cleaner.
Filtering can be used to "smooth" a reference input.
Filtering the input can reduce noise in the feedback which may improve system control.