CONTROLLER AND STORAGE DEVICE
According to one embodiment, in a controller of a servo system that performs positioning control of a head by feedback control includes a generating module and a notch filter. The generating module compares a target position and position information decoded from data read by the head from a recording medium to generate a position error signal. The notch filter performs notch filter processing to remove machine vibration of a head driving module on the position error signal. The transfer function H(s) of the notch filter is set to H(s)=[{s 2 +2 kζωs+ω 2 }/{s 2 +2 ζωs+ω 2 }]·[(τ 1 s+ 1 )] where s is a Laplace operator, k is a constant, τ 1 and τ 2 are time constants, ζ is a damping constant, and ω is a notch frequency.
1 . A controller of a servo system that performs positioning control of a head by feedback control, the controller comprising:
a generating module configured to compare a target position and position information decoded from data read by the head from a recording medium to generate a position error signal; and
a notch filter configured to perform notch filter processing to remove machine vibration of a head driving module on the position error signal, wherein
a transfer function H(s) of the notch filter is set to H(s)=[{s 2 +2kζωs+ω 2 }/{s 2 +2ζωs+ω 2 }]·[(τ 1 s+1)/(τ 2 s+1)] where s is a Laplace operator, k is a constant, τ 1 and τ 2 are time constants, ζ is a damping constant, and ω is a notch frequency.
2 . The controller of claim 1 , wherein τ 1 /τ 2 is approximately 4 to 6.
3 . The controller of claim 1 , wherein
the notch frequency o of the notch filter is set to be substantially equal to a main resonance frequency of the head driving module, and
a gain at frequencies higher than the notch frequency co is set according to an antiresonance frequency of the head driving module.
4 . The controller of claim 1 , wherein
the notch frequency o of the notch filter is set to be substantially equal to a main resonance frequency of the head driving module, and
the notch filter includes a notch filter that removes high-order resonance frequency of the head driving module.
5 . The controller of claim 1 , wherein the notch filter is configured of a digital signal processor that performs the notch filter processing by arithmetic processing.
6 . A storage device comprising:
a head driving module configured to drive a head; and
a servo system configured to perform positioning control of the head by feedback control, the servo system comprising
a generating module configured to compare a target position and position information decoded from data read by the head from a recording medium to generate a position error signal, and
a notch filter configured to perform notch filter processing to remove machine vibration of the head driving module on the position error signal, wherein
a transfer function H(s) of the notch filter is set to H(s)=[{s 2 +2kζωs+ω 2 }/{s 2 +2ζωs+ω 2 }]·[(τ 1 s+1)/(τ 2 s+1)] where s is a Laplace operator, k is a constant, τ 1 and τ 2 are time constants, ζ is a damping constant, and ω is a notch frequency.
7 . The storage device of claim 6 , wherein τ 1 /τ 2 is approximately 4 to 6.
8 . The storage device of claim 6 , wherein
the notch frequency ω of the notch filter is set to be substantially equal to a main resonance frequency of the head driving module, and
a gain at frequencies higher than the notch frequency ω is set according to an antiresonance frequency of the head driving module.
9 . The storage device of claim 6 , wherein
the notch frequency ω of the notch filter is set to be substantially equal to a main resonance frequency of the head driving module, and
the notch filter includes a notch filter that removes high-order resonance frequency of the head driving module.
10 . The storage device of claim 6 , wherein the notch filter is configured of a digital signal processor that performs the notch filter processing by arithmetic processing.