Update Content - 2024-12-17

content/book/du19_multi_actuat_system_contr.md

@@ -83,14 +83,14 @@ and the resonance \\(P\_{ri}(s)\\) can be represented as one of the following fo
 
 #### Secondary Actuators {#secondary-actuators}
 
-We here consider two types of secondary actuators: the PZT milliactuator (figure [1](#figure--fig:pzt-actuator)) and the microactuator.
+We here consider two types of secondary actuators: the PZT milliactuator ([Figure 1](#figure--fig:pzt-actuator)) and the microactuator.
 
 <a id="figure--fig:pzt-actuator"></a>
 
 {{< figure src="/ox-hugo/du19_pzt_actuator.png" caption="<span class=\"figure-number\">Figure 1: </span>A PZT-actuator suspension" >}}
 
 There are three popular types of micro-actuators: electrostatic moving-slider microactuator, PZT slider-driven microactuator and thermal microactuator.
-There characteristics are shown on table [1](#table--tab:microactuator).
+There characteristics are shown on [Table 1](#table--tab:microactuator).
 
 <a id="table--tab:microactuator"></a>
 <div class="table-caption">
@@ -107,7 +107,7 @@ There characteristics are shown on table [1](#table--tab:microactuator).
 
 ### Single-Stage Actuation Systems {#single-stage-actuation-systems}
 
-A typical closed-loop control system is shown on figure [2](#figure--fig:single-stage-control), where \\(P\_v(s)\\) and \\(C(z)\\) represent the actuator system and its controller.
+A typical closed-loop control system is shown on [Figure 2](#figure--fig:single-stage-control), where \\(P\_v(s)\\) and \\(C(z)\\) represent the actuator system and its controller.
 
 <a id="figure--fig:single-stage-control"></a>
 
@@ -145,7 +145,7 @@ In view of this, the controller design for dual-stage actuation systems adopts a
 
 ### Control Schemes {#control-schemes}
 
-A popular control scheme for dual-stage actuation system is the **decoupled structure** as shown in figure [4](#figure--fig:decoupled-control).
+A popular control scheme for dual-stage actuation system is the **decoupled structure** as shown in [Figure 4](#figure--fig:decoupled-control).
 
 -   \\(C\_v(z)\\) and \\(C\_p(z)\\) are the controllers respectively, for the primary VCM actuator \\(P\_v(s)\\) and the secondary actuator \\(P\_p(s)\\).
 -   \\(\hat{P}\_p(z)\\) is an approximation of \\(P\_p\\) to estimate \\(y\_p\\).
@@ -175,7 +175,7 @@ The sensitivity functions of the VCM loop and the secondary actuator loop are
 And we obtain that the dual-stage sensitivity function \\(S(z)\\) is the product of \\(S\_v(z)\\) and \\(S\_p(z)\\).
 Thus, the dual-stage system control design can be decoupled into two independent controller designs.
 
-Another type of control scheme is the **parallel structure** as shown in figure [5](#figure--fig:parallel-control-structure).
+Another type of control scheme is the **parallel structure** as shown in [Figure 5](#figure--fig:parallel-control-structure).
 The open-loop transfer function from \\(pes\\) to \\(y\\) is
 \\[ G(z) = P\_p(z) C\_p(z) + P\_v(z) C\_v(z) \\]
 
@@ -192,7 +192,7 @@ Because of the limited displacement range of the secondary actuator, the control
 ### Controller Design Method in the Continuous-Time Domain {#controller-design-method-in-the-continuous-time-domain}
 
 \\(\mathcal{H}\_\infty\\) loop shaping method is used to design the controllers for the primary and secondary actuators.
-The structure of the \\(\mathcal{H}\_\infty\\) loop shaping method is plotted in figure [6](#figure--fig:h-inf-diagram) where \\(W(s)\\) is a weighting function relevant to the designed control system performance such as the sensitivity function.
+The structure of the \\(\mathcal{H}\_\infty\\) loop shaping method is plotted in [Figure 6](#figure--fig:h-inf-diagram) where \\(W(s)\\) is a weighting function relevant to the designed control system performance such as the sensitivity function.
 
 For a plant model \\(P(s)\\), a controller \\(C(s)\\) is to be designed such that the closed-loop system is stable and
 
@@ -206,7 +206,7 @@ is satisfied, where \\(T\_{zw}\\) is the transfer function from \\(w\\) to \\(z\
 
 {{< figure src="/ox-hugo/du19_h_inf_diagram.png" caption="<span class=\"figure-number\">Figure 6: </span>Block diagram for \\(\mathcal{H}\_\infty\\) loop shaping method to design the controller \\(C(s)\\) with the weighting function \\(W(s)\\)" >}}
 
-Equation [1](#org60aa04e) means that \\(S(s)\\) can be shaped similarly to the inverse of the chosen weighting function \\(W(s)\\).
+Equation [ 1](#orgc94b8e5) means that \\(S(s)\\) can be shaped similarly to the inverse of the chosen weighting function \\(W(s)\\).
 One form of \\(W(s)\\) is taken as
 
 \begin{equation}
@@ -219,13 +219,13 @@ The controller can then be synthesis using the linear matrix inequality (LMI) ap
 
 The primary and secondary actuator control loops are designed separately for the dual-stage control systems.
 But when designing their respective controllers, certain performances are required for the two actuators, so that control efforts for the two actuators are distributed properly and the actuators don't conflict with each other's control authority.
-As seen in figure [7](#figure--fig:dual-stage-loop-gain), the VCM primary actuator open loop has a higher gain at low frequencies, and the secondary actuator open loop has a higher gain in the high-frequency range.
+As seen in [Figure 7](#figure--fig:dual-stage-loop-gain), the VCM primary actuator open loop has a higher gain at low frequencies, and the secondary actuator open loop has a higher gain in the high-frequency range.
 
 <a id="figure--fig:dual-stage-loop-gain"></a>
 
 {{< figure src="/ox-hugo/du19_dual_stage_loop_gain.png" caption="<span class=\"figure-number\">Figure 7: </span>Frequency responses of \\(G\_v(s) = C\_v(s)P\_v(s)\\) (solid line) and \\(G\_p(s) = C\_p(s) P\_p(s)\\) (dotted line)" >}}
 
-The sensitivity functions are shown in figure [8](#figure--fig:dual-stage-sensitivity), where the hump of \\(S\_v\\) is arranged within the bandwidth of \\(S\_p\\) and the hump of \\(S\_p\\) is lowered as much as possible.
+The sensitivity functions are shown in [Figure 8](#figure--fig:dual-stage-sensitivity), where the hump of \\(S\_v\\) is arranged within the bandwidth of \\(S\_p\\) and the hump of \\(S\_p\\) is lowered as much as possible.
 This needs to decrease the bandwidth of the primary actuator loop and increase the bandwidth of the secondary actuator loop.
 
 <a id="figure--fig:dual-stage-sensitivity"></a>
@@ -261,7 +261,7 @@ A VCM actuator is used as the first-stage actuator denoted by \\(P\_v(s)\\), a P
 
 ### Control Strategy and Controller Design {#control-strategy-and-controller-design}
 
-Figure [9](#figure--fig:three-stage-control) shows the control structure for the three-stage actuation system.
+[Figure 9](#figure--fig:three-stage-control) shows the control structure for the three-stage actuation system.
 
 The control scheme is based on the decoupled master-slave dual-stage control and the third stage microactuator is added in parallel with the dual-stage control system.
 The parallel format is advantageous to the overall control bandwidth enhancement, especially for the microactuator having limited stroke which restricts the bandwidth of its own loop.
@@ -296,13 +296,13 @@ The PZT actuated milliactuator \\(P\_p(s)\\) works under a reasonably high bandw
 The third-stage actuator \\(P\_m(s)\\) is used to further push the bandwidth as high as possible.
 
 The control performances of both the VCM and the PZT actuators are limited by their dominant resonance modes.
-The open-loop frequency responses of the three stages are shown on figure [10](#figure--fig:open-loop-three-stage).
+The open-loop frequency responses of the three stages are shown on [Figure 10](#figure--fig:open-loop-three-stage).
 
 <a id="figure--fig:open-loop-three-stage"></a>
 
 {{< figure src="/ox-hugo/du19_open_loop_three_stage.png" caption="<span class=\"figure-number\">Figure 10: </span>Frequency response of the open-loop transfer function" >}}
 
-The obtained sensitivity function is shown on figure [11](#figure--fig:sensitivity-three-stage).
+The obtained sensitivity function is shown on [Figure 11](#figure--fig:sensitivity-three-stage).
 
 <a id="figure--fig:sensitivity-three-stage"></a>
 
@@ -319,7 +319,7 @@ Otherwise, saturation will occur in the control loop and the control system perf
 Therefore, the stroke specification of the actuators, especially milliactuator and microactuators, is very important for achievable control performance.
 Higher stroke actuators have stronger abilities to make sure that the control performances are not degraded in the presence of external vibrations.
 
-For the three-stage control architecture as shown on figure [9](#figure--fig:three-stage-control), the position error is
+For the three-stage control architecture as shown on [Figure 9](#figure--fig:three-stage-control), the position error is
 \\[ e = -S(P\_v d\_1 + d\_2 + d\_e) + S n \\]
 The control signals and positions of the actuators are given by
 
@@ -335,11 +335,11 @@ Higher bandwidth/higher level of disturbance generally means high stroke needed.
 
 ### Different Configurations of the Control System {#different-configurations-of-the-control-system}
 
-A decoupled control structure can be used for the three-stage actuation system (see figure [12](#figure--fig:three-stage-decoupled)).
+A decoupled control structure can be used for the three-stage actuation system (see [Figure 12](#figure--fig:three-stage-decoupled)).
 
 The overall sensitivity function is
 \\[ S(z) = \approx S\_v(z) S\_p(z) S\_m(z) \\]
-with \\(S\_v(z)\\) and \\(S\_p(z)\\) are defined in equation [1](#org3237465) and
+with \\(S\_v(z)\\) and \\(S\_p(z)\\) are defined in equation [ 1](#org5626095) and
 \\[ S\_m(z) = \frac{1}{1 + P\_m(z) C\_m(z)} \\]
 
 Denote the dual-stage open-loop transfer function as \\(G\_d\\)
@@ -360,7 +360,7 @@ The control signals and the positions of the three actuators are
   u\_v &= C\_v(1 + \hat{P}\_p C\_p) (1 + \hat{P}\_m C\_m) e, \ y\_v = P\_v u\_v
 \end{align\*}
 
-The decoupled configuration makes the low frequency gain much higher, and consequently there is much better rejection capability at low frequency compared to the parallel architecture (see figure [13](#figure--fig:three-stage-decoupled-loop-gain)).
+The decoupled configuration makes the low frequency gain much higher, and consequently there is much better rejection capability at low frequency compared to the parallel architecture (see [Figure 13](#figure--fig:three-stage-decoupled-loop-gain)).
 
 <a id="figure--fig:three-stage-decoupled-loop-gain"></a>