Hardware Reference
In-Depth Information
r:u_v, g:u_m
2.5
2
1.5
1
0.5
0
−0.5
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
x 10
−3
Figure 3.80: Control inputs of VCM (solid line) and microactuator (dashed
line) corresponding to Figure 3.79.
10
0
−10
−20
−30
−40
−50
10
1
10
2
10
3
10
4
10
5
Hz
Figure 3.81: S (solid line) and T (dashed line).
3.7.3 PQ Method
The PID-type design of the parallel structure of dual-stage actuator discussed
earlier in this section does not take care of the phase difference at the hand-off
frequency between the two parallel paths. The PQ method, proposed in [170],
includes the condition for proper hand-off into the design process. This method
is a two-step design approach. In the first step, the design problem for the DISO
plant is converted into a problem of single-input/single-output (SISO) design
that satisfies the desired conditions for hands-off. Then, in the second step, a
feedback controller is found for the modified SISO system ensuring stability of
