Notch Filter; Anti-Vibration Filter - Servotronix CDHD2S User Manual

Tuning

8.10 Notch filter

Note ServoStudio2 has not been fully updated.
The notch filter can be used to eliminate high-frequency oscillations that can occur in systems
with flexible connections between motor and load, such as:
Ball screw linear slide with coupling
⚫
Belt drive
⚫
Harmonic drive
⚫
Oscillation usually occurs during the first step of tuning (feedback gain). Tuning is done by
checking the oscillation frequency and setting the notch accordingly. Once the notch parameters
are set, the tuning process can continue.
The HD control notch filter can be used at any time during tuning to suppress oscillations at
fixed frequencies greater than 300Hz:
NLNOTCHCENTER (HD current filter - notch filter center)
⚫
NLNOTCHBW (HD current filter – notch filter bandwidth)
⚫
The second set of HD control notch filters (NOTCH2CENTER and NLNOTCH2BW) are available
through the terminal but do not appear in the ServoStudio2 control loop screen.

8.11 Anti-vibration Filter

Note: ServoStudio2 has not been fully updated.
Anti-vibration overview
The anti-vibration function of the HD controller is based on a proprietary control algorithm
and is used to suppress vibration at a constant frequency.
The vibration suppression function operates in a closed loop, detecting oscillations when they
occur and suppressing them immediately. Active damping load oscillation significantly reduces the
time required for heavy load or end effector to stabilize at the target position. Although the position
error at the encoder level may be high, the overall performance of the system evaluated at the load
position is improved.
A typical example is that a load is fixed to a servo control motor by means of a shaft with
certain flexibility. If the motor's servo control is set to a position error close to zero during motion,
the load will oscillate strongly. Every change in acceleration (jerk) creates a disturbance, causing
load oscillation. Although a stiff HD control loop will overcome these oscillations at the motor
position level, the load will still oscillate strongly.
The anti-vibration feature can handle systems with oscillation frequencies up to 100Hz.
The figure below shows the four stages of the vibration suppression process.
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