CDHD Tuning
User Manual 215
9 .1 0 N otch Filters
Not ch filters can be used to eliminate high frequency oscillations t hat m ay occur
in systems having a flexible link between m otor and load, such as:
Ballscrew linear slide with coupling
Belt drive
Harmonic drive
Oscillations usually occur during the first st eps in t uning (feedback gain) . Tuning
is done by checking the frequency of the oscillation, and setting the notch
accordingly. Once notch param eters are set, the tuning procedure can continue.
HD control notch filters are used at any time during tuning t o dam p oscillations
at a fixed frequency greater than 300 Hz:
NLNOTCHCENTER (HD Current Filter – Notch Filter Center)
NLNOTCHBW (HD Current Filter – Not ch Filter Bandwidth)
A second set of HD control notch filters (NOTCH2CENTER and NLNOTCH2BW) is
available through Terminal, but does not appear in the ServoStudio control loop
screen.
9 .1 1 Ant i- Vibration Filters
Ant i- Vibra tion Overvie w
The HD cont rol ant i-vibration function is based on propriet ary cont rol algorithm s
and serves to suppress vibrations at constant frequencies.
The vibration suppression function runs in a closed loop, detecting oscillations as
t hey occur, and dam ping them im mediately. Actively damping load oscillations
significantly reduces the time it takes for a heavy load or an end effector to
settle at the target position. Although the position error at the encoder level m ay
be higher, the overall perform ance of the syst em , as evaluat ed at load position,
is significantly im proved.
A typical exam ple is a load fixed to a servo controlled m otor by means of a shaft
that has a certain am ount of flexibility. I f the servo control of the motor is set for
near-zero posit ion error during movem ent , then the load will oscillate st rongly.
Every change in the acceleration (jerk) will apply a perturbation, resulting in
oscillat ions of the load. While t he stiff HD control loop will overcom e these
oscillations at motor position level, the load will still oscillate strongly.
The anti-vibration function can handle systems with an oscillation frequency of
up to 100 Hz.
To Next Page
