VL.FFDELAY

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VL.FFDELAY

General Information
Type	R/W Parameter
Description	Sets the delay time for the velocity feedforward integrator component.
Units	Microseconds
Range	0, 100 to 625,000
Default Value	0
Data Type	Integer
Start Version	M_01-13-01-000

FieldbusA Fieldbus is an industrial network system for real-time distributed control (e.g. CAN or Profibus). It is a way of connecting instruments in a plant design	Index/Subindex	Object Start Version
EtherCATEtherCAT is an open, high-performance Ethernet-based fieldbus system. The development goal of EtherCAT was to apply Ethernet to automation applications which require short data update times (also called cycle times) with low communication jitter (for synchronization purposes) and low hardware costs COE and CANopen	53D6/0	M_01-00-00-000

Description

VL.FFDELAY sets the delay applied to the velocity feedforward term that is passed into the velocity loop integrator. The delay is applied to the velocity feedforward, and then subtracted from the current velocity feedforward term. This difference is the value fed into the velocity loop integrator. If tuned correctly, this delay will help reduce position following error and velocity following error.

This filter is considered a feedforward. For best results it should be set in conjunction with PL.PDELAY.

After making an approximation of the Open Loop bandwidthIn computer networking, bandwidth often refers to a data rate measured in bits/s, for example, network throughput. The reason for the connection of data rate with the term bandwidth is that the limit to the data rate of a physical communication link is related to its bandwidth in hertz (Hz) in the Performance Servo Tuner, calculate VL.FFDELAY:

VL.FFDELAY = 1 / (Open Loop BW (Hz) * 2π) * 1,000,000

1,000,000 = seconds to microseconds