Slave station for fluid control equipment

Abstract

To provide a slave station for fluid control apparatuses making it possible to minimize an adverse effect of a delay in a response time of a fluid control apparatus or of noise derived from transfer of signals, or to reduce a work load imposed on designation of a proper PID parameter.SOLUTION: A slave station 12 for fluid control apparatuses is employed in a field network 1 including an electropneumatic regulator 13, a master 11 that outputs a command target value which is a signal of commanding a target pressure value for a control fluid to be outputted from the electropneumatic regulator 13, and a pressure sensor 14 that detects the pressure value of the control fluid outputted from the electropneumatic regulator 13, and outputs a detection signal. The slave station for fluid control apparatuses relays signals to be transferred among the master 11, electropneumatic regulator 13, and pressure sensor 14. The slave station 12 for fluid control apparatuses includes a feedback control arithmetic unit 121A that implements feedback control in the electropneumatic regulator 13 on the basis of the command target value and detection signal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a slave station for a fluid control device that is used in a field network composed of a fluid control device, a master that outputs a command signal for controlling the fluid control device, and a sensor that detects the output of the fluid control device and outputs a detection signal, and that relays signals between the master, the fluid control device, and the sensor. [Background technology]

[0002] Wafers used as semiconductor materials are required to have a highly flat and contaminant-free surface. For this reason, in the wafer manufacturing process, the wafer surface is polished, for example, by chemical mechanical polishing, which can obtain an extremely smooth polished surface. The wafer surface is polished, for example, by contacting the wafer surface with a rotating polishing pad. The contact pressure between the polishing pad and the wafer during this contact is controlled, for example, by air pressure, and this air pressure control is performed by an electropneumatic regulator as a fluid control device, as shown in Patent Document 1.

[0003] The electro-pneumatic regulator, for example, like the electro-pneumatic regulator 13 shown in FIG. 4, comprises a master 51, a slave station for fluid control equipment 52, and a pressure sensor 14, and is controlled by feedback control (PID control).

[0004] The master 51 outputs a command target value as a target value for the pressure value output by the electro-pneumatic regulator 13 and a feedback command value for performing feedback control as an operation amount for the electro-pneumatic regulator 13 .

[0005] The master 51 includes a feedback control calculation unit 51A for performing feedback control of the electro-pneumatic regulator 13 and a parameter setting unit 51B for setting PID parameters. The master 51 also has a PID parameter setting mode and an electro-pneumatic regulator control mode. When an operator selects the PID parameter setting mode, the parameter setting unit 51B calculates PID parameters, and the calculated PID parameters can be stored in the master 51. When the operator selects the electro-pneumatic regulator control mode, the feedback control calculation unit 51A adjusts a feedback command value to the electro-pneumatic regulator 13 based on the PID parameters calculated by the parameter setting unit 51B and a detection signal output from a pressure sensor 14 (described later) so that the pressure value output by the electro-pneumatic regulator 13 approaches a command target value, and controls the electro-pneumatic regulator 13 based on the feedback command value. Furthermore, the master 51 is connected to a slave station 52 for fluid control equipment by a digital signal line 53, and the master 51 and the slave station 52 for fluid control equipment can exchange digital signals with each other.

[0006] The fluid control device slave station 52 includes a CPU 521, a D / A conversion unit 522, and an A / D conversion unit 523. The fluid control device slave station 52 is also connected to the electro-pneumatic regulator 13 and the pressure sensor 14 by analog signal lines 54, 55. This enables the fluid control device slave station 52 to transmit an analog voltage signal to the electro-pneumatic regulator 13, and to receive an analog voltage signal output from the pressure sensor 14.

[0007] The electropneumatic regulator 13 is a fluid control device that uses air as a control fluid, and controls the pressure value of the output air based on a signal transmitted from the fluid control device slave station 52 via an analog signal line 55 .

[0008] The pressure sensor 14 detects the pressure value at the output port of the electro-pneumatic regulator 13. The pressure sensor 14 outputs the detected pressure value as a detection signal. The pressure sensor 14 may be integrated with the electro-pneumatic regulator 13 or may be separate from the electro-pneumatic regulator 13.

[0009] According to the field network 5 configured as above, the electro-pneumatic regulator 13 is controlled as follows.

[0010] First, the operator sets the master 51 to a PID parameter setting mode, calculates the PID parameters using the parameter setting unit 51B, and causes the master 51 to store the calculated PID parameters.

[0011] Then, the master 51 is switched to the electro-pneumatic regulator control mode. First, the master 51 outputs a command target value to the fluid control equipment slave station 52. This command target value is a digital signal, and upon receiving the command target value, the fluid control equipment slave station 52 converts the command target value into an analog voltage signal by the D / A conversion unit 522 and outputs it to the electro-pneumatic regulator 13. The electro-pneumatic regulator 13 receives this command target value and starts controlling the pressure value to be output.

[0012] The pressure sensor 14 detects the pressure value at the output port of the electro-pneumatic regulator 13, and outputs the detection result as a detection signal to the fluid control device slave station 52 via the analog signal line 55. This detection signal is an analog voltage signal.

[0013] When the fluid control device slave station 52 receives a detection signal from the pressure sensor 14, the A / D conversion unit 523 converts the detection signal into a digital signal. The digitally converted detection signal is then transmitted to the master 51. The feedback control calculation unit 51A adjusts a feedback command value for the electro-pneumatic regulator 13 based on the detection signal and preset PID parameters so that the pressure value output by the electro-pneumatic regulator 13 approaches a target value, and outputs the adjusted feedback command value to the fluid control device slave station 52 via the digital signal line 53. This feedback command value is a digital signal.

[0014] When the fluid control device slave station 52 receives the feedback command value, the D / A converter 522 converts the feedback command value into an analog voltage signal and outputs it to the electro-pneumatic regulator 13. The electro-pneumatic regulator 13 receives this feedback command value and controls the pressure value to be output. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] Patent No. 4615753 Summary of the Invention [Problem to be solved by the invention]

[0016] However, the above-mentioned conventional techniques have the following problems. The output from the pressure sensor 14 is sent to the slave station 52 for the fluid control device, and then to the master 51. A feedback command value based on this output is sent from the master 51 to the slave station 52 for the fluid control device, and then to the electro-pneumatic regulator 13. In this manner, since the number of devices through which the signal passes is large, there is a risk of a delay in the response time from when the pressure sensor 14 outputs until the pressure value actually output by the electro-pneumatic regulator 13 changes. In addition, if the number of devices through which the signal passes is large, there is a high possibility that the signal will be affected by noise when the signal is passed. Although the delay in the response time and the effect of noise are considered to be minimal, particularly when the electro-pneumatic regulator 13 is used in a wafer polishing device, the wafer surface is required to have an extremely high degree of flatness, and therefore even a slight delay in the response time and the effect of noise may adversely affect the quality of the wafer.

[0017] It is possible to introduce multiple electro-pneumatic regulators 13 by connecting multiple fluid control device slave stations 52 in parallel to the master 51, but at the site where the electro-pneumatic regulators 13 are used, appropriate PID parameters must be set for each of the multiple electro-pneumatic regulators 13. Setting the PID parameters takes time, so it is desirable to reduce the workload.

[0018] The present invention is intended to solve the above problems, and aims to provide a slave station for fluid control equipment that can reduce delays in the response time of fluid control equipment due to signal transmission and reception, and the effects of noise, as well as reduce the workload involved in setting appropriate PID parameters. [Means for solving the problem]

[0019] In order to solve the above problems, a slave station for a fluid control device according to the present invention has the following configuration.

[0020] (1) A slave station for fluid control equipment used in a field network consisting of a fluid control device, a master that outputs a command target value, which is a signal for commanding a target value of the output of the fluid control device, and a sensor that detects the output of the fluid control device and outputs a detection signal, the slave station for fluid control equipment relaying signals between the master, the fluid control device, and the sensor, the slave station for fluid control equipment having a feedback control calculation unit that performs feedback control of the fluid control device based on the command target value and the detection signal, the feedback control being PID control, the slave station for fluid control equipment having a parameter setting unit that sets PID parameters, and shipped with the PID parameters set, Even when multiple fluid control devices are installed at a work site, there is no need to set PID parameters for each fluid control device individually, which reduces the workload at the work site. It is characterized by:

[0021] The slave station for a fluid control device described in (1) is used in a field network composed of a fluid control device (e.g., an electro-pneumatic regulator), a master that outputs a command target value, which is a signal for commanding a target value of the output of the fluid control device (e.g., a target pressure value of the controlled fluid output by the electro-pneumatic regulator), and a sensor (e.g., a pressure sensor) that detects the output of the fluid control device (e.g., the pressure value of the controlled fluid output by the electro-pneumatic regulator) and outputs a detection signal, and is equipped with a feedback control calculation unit that performs feedback control of the fluid control device based on the command target value and the detection signal. Therefore, the slave station for the fluid control device itself can perform feedback control of the fluid control device based on the command target value and the detection signal so that the output of the fluid control device approaches the command target value. Since the slave station for the fluid control device itself performs feedback control, the number of devices through which the signal passes when transmitting and receiving signals for performing feedback control can be reduced compared to the conventional case. Therefore, the possibility of a delay in the response time from when the sensor outputs a detection signal to when the output of the fluid control device actually changes is reduced. In addition, by reducing the number of devices through which a signal passes, the possibility that the signal will be affected by noise when it is sent and received is reduced. If such a slave station for fluid control devices is used in, for example, an electro-pneumatic regulator used in a wafer polishing device, it is possible to suppress adverse effects on wafer quality caused by minute delays in response time and the effects of noise.

[0023] In addition, (1) According to the slave station for fluid control equipment described in the above, it is possible to improve the work efficiency. For example, when a semiconductor manufacturer uses a fluid control equipment, the master is the equipment of the semiconductor manufacturer, and the slave station for fluid control equipment is generally procured from the fluid control equipment manufacturer together with the fluid control equipment. In this situation, if the slave station for fluid control equipment has a parameter setting unit for setting PID parameters, the fluid control equipment manufacturer can deliver the slave station for fluid control equipment to the semiconductor manufacturer in a state in which the PID parameters determined by the semiconductor manufacturer at the prototype stage of the semiconductor are set in the slave station for fluid control equipment at the shipping stage. Then, even if multiple fluid control equipment are introduced at a work site, it is not necessary to set the PID parameters for each of the fluid control equipment individually, and the work load at the work site can be reduced. Effect of the Invention

[0024] By having the above-mentioned configuration, the slave station for fluid control equipment of the present invention can reduce delays in the response time of the fluid control equipment due to the transmission and reception of signals, and the effects of noise, as well as reduce the workload involved in setting appropriate PID parameters. [Brief description of the drawings]

[0025] [Figure 1] 1 is a block diagram showing a configuration of a field network configured using a slave station for a fluid control device according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a circuit diagram of an electro-pneumatic regulator used in a field network. [Diagram 3] FIG. 11 is a diagram showing an operation flow of a slave station for a fluid control device. [Figure 4] FIG. 1 is a block diagram showing a configuration of a field network according to a conventional technique. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] An embodiment of a slave station for a fluid control device of the present invention will be described in detail with reference to the drawings. Fig. 1 is a block diagram showing the configuration of a field network 1 configured using a slave station for a fluid control device 12 according to this embodiment. Fig. 2 is a circuit diagram of an electro-pneumatic regulator 13 used in the field network 1.

[0027] A field network 1 shown in Fig. 1 is used, for example, in a polishing device for wafers, which are semiconductor materials. The field network 1 is a system in which a master 11 as a parent station and a slave station 12 for a fluid control device as a child station are connected, for example, by CC-Link (registered trademark), and further comprises an electro-pneumatic regulator 13 (an example of a fluid control device) and a pressure sensor 14 (an example of a sensor) connected to the slave station 12 for the fluid control device. Such a field network 1 makes it possible to perform feedback control (PID control) of the electro-pneumatic regulator 13.

[0028] The master 11 is, for example, a programmable logic controller (PLC), and is a unit that inputs and outputs signals to manage the entire field network 1. The master 11 outputs a command target value as a target pressure value of the controlled fluid output by the electro-pneumatic regulator 13.

[0029] The master 11 is also connected to the fluid control device slave station 12 by a digital signal line 15, and the master 11 and the fluid control device slave station 12 can send and receive digital signals to and from each other.

[0030] The fluid control device slave station 12 includes a CPU 121, a D / A conversion unit 122, and an A / D conversion unit 123. The CPU 121 also includes a feedback control calculation unit 121A for performing feedback control of the electro-pneumatic regulator 13, and a parameter setting unit 121B for calculating PID parameters and storing the calculated PID parameters in the fluid control device slave station 12.

[0031] The fluid control device slave station 12 has a PID parameter setting mode and an electro-pneumatic regulator control mode. When an operator selects the PID parameter setting mode, the fluid control device slave station 12 can calculate and store PID parameters for feedback control of the electro-pneumatic regulator 13 by the parameter setting unit 121B. When the electro-pneumatic regulator control mode is selected, the fluid control device slave station 12 adjusts a feedback command value to the electro-pneumatic regulator 13 by the feedback control calculation unit 51A so that the pressure value output by the electro-pneumatic regulator 13 approaches the command target value received from the master 11. This adjustment of the feedback command value is performed based on the PID parameters calculated by the parameter setting unit 51B and a detection signal output from a pressure sensor 14, which will be described later.

[0032] The D / A conversion section 122 converts a digital signal into an analog voltage signal, and the A / D conversion section 123 converts an analog voltage signal into a digital signal.

[0033] The fluid control device slave station 12 is connected to the electro-pneumatic regulator 13 by an analog signal line 16. More specifically, the electro-pneumatic regulator 13 is connected to a D / A conversion unit 122 of the fluid control device slave station 12 by the analog signal line 16. This allows the fluid control device slave station 12 to convert the command target value output from the master 11 and the feedback command value adjusted by the feedback control calculation unit 121A into analog voltage signals by the D / A conversion unit 122 and then transmit them to the electro-pneumatic regulator 13.

[0034] Further, the pressure sensor 14 is connected to the fluid control device slave station 12 by an analog signal line 17. More specifically, the pressure sensor 14 is connected to an A / D conversion unit 123 of the fluid control device slave station 12 by the analog signal line 17. This allows the fluid control device slave station 12 to receive an analog voltage signal output from the pressure sensor 14 after the analog voltage signal is converted into a digital signal by the A / D conversion unit 123.

[0035] The electro-pneumatic regulator 13 is a fluid control device that uses air as a control fluid, and controls the pressure value of the output air between approximately 100 Kpa and 500 Kpa based on a feedback command value transmitted from the fluid control device slave station 12 via an analog signal line 55.

[0036] The electropneumatic regulator 13 is used in a wafer polishing apparatus to adjust the contact pressure when the wafer surface is brought into contact with a polishing pad. As shown in Fig. 2, the electropneumatic regulator 13 comprises a control circuit 138, an air supply control valve 132 and an exhaust control valve 133 controlled by the control circuit 138, a main valve unit 134 operated by the air supply control valve 132 and the exhaust control valve 133, an input port 131 for inputting a control fluid, and an output port 137 for outputting the control fluid.

[0037] The input port 131 and the output port 137 are connected to the main valve unit 134 via an input flow path 139 and an output flow path 140, respectively. The input port 131 is connected to a supply source of a control fluid (e.g., air) and the control fluid is supplied. The main valve unit 134 has a valve body and a valve seat (not shown), and adjusts the pressure value of the control fluid output from the output port 137 by bringing the valve body and the valve seat into contact with and away from each other. The adjustment of the pressure value of the control fluid is made based on a command target value output from the master 11 and a feedback command value output from the slave station 12 for fluid control equipment. By adjusting the pressure value of the control fluid, the contact pressure when the wafer surface is brought into contact with the polishing pad in the wafer polishing apparatus is adjusted.

[0038] The air supply control valve 132 is connected to the input port 131 via an input flow path 139, and is connected to a pilot chamber (not shown) of the main valve section 134 via a flow path 142. The air supply control valve 132 operates the main valve section 134 by supplying air to the pilot chamber, and controls the output pressure value at the output port 137 of the control fluid input to the input port 131.

[0039] The exhaust flow path 141 branches off from the flow path 142 between the air intake control valve 132 and the main valve portion 134, and is connected to an exhaust port 135 that is open to the atmosphere. An exhaust control valve 133 is disposed in the exhaust flow path 141. This exhaust control valve 133 controls the control fluid that is exhausted from the pilot chamber of the main valve portion 134 to the exhaust port 135 via the flow path 142.

[0040] The control circuit 138 is electrically connected to the air supply control valve 132 and the exhaust control valve 133. The control circuit 138 is connected to the fluid control device slave station 12, and receives the command target value and the feedback command value as an analog voltage signal. The control circuit 18 controls the opening and closing of the air supply control valve 132 or the exhaust control valve 133 based on the received command target value and the feedback command value, and operates the main valve unit 134 to adjust the pressure value at the output port 137 of the control fluid input to the input port 131.

[0041] The pressure sensor 14 is connected to the output flow path 140 of the electro-pneumatic regulator 13. This allows the pressure sensor 14 to constantly detect the pressure value of the controlled fluid at the output port 137. The detected pressure value is output as a detection signal to the fluid control device slave station 12 via the analog signal line 17. Although the pressure sensor 14 is shown as a separate body from the electro-pneumatic regulator 13 in FIG. 2, it may be integrated with the electro-pneumatic regulator 13.

[0042] In the field network 1 configured as above, the fluid control device slave station 12 controls the electro-pneumatic regulator 13 as follows: Fig. 3 is a diagram showing an operation flow of the fluid control device slave station 12.

[0043] First, in order to set PID parameters for feedback control of the electro-pneumatic regulator 13, the operator sets the fluid control device slave station 12 to a PID parameter setting mode. When the fluid control device slave station 12 is operated, the fluid control device slave station 12 first receives a command target value from the master 11 (S11). Next, the fluid control device slave station 12 judges whether it is set to the PID parameter setting mode or the electro-pneumatic regulator control mode (S12). If it is judged that it is set to the PID parameter setting mode, the parameter setting unit 51B is operated (S12: setting mode). Then, the fluid control device slave station 12 calculates appropriate PID parameters by the parameter setting unit 51B to bring the pressure value output by the electro-pneumatic regulator 13 close to the command target value received from the master 11, and stores the calculated PID parameters (S16).

[0044] When the electro-pneumatic regulator 13 is to be controlled after the PID parameters have been set, the fluid control device slave station 12 is switched to an electro-pneumatic regulator control mode. When the fluid control device slave station 12 is switched to the electro-pneumatic regulator control mode, the feedback control calculation unit is operated (S11: control mode). Then, the fluid control device slave station 12 receives a detection signal from the pressure sensor 14 via the analog signal line 55 (S13). Since this detection signal is an analog voltage signal, it is converted to a digital signal by the A / D conversion unit 123 and used for feedback control. Then, the feedback control calculation unit 121A adjusts a feedback command value to the electro-pneumatic regulator 13 based on the detection signal converted to a digital signal and the preset PID parameters so that the pressure value output by the electro-pneumatic regulator 13 approaches the command target value received from the master 11 (S13). Since this feedback command value is a digital signal, the fluid control device slave station 12 converts the feedback command value into a digital signal using the D / A converter 122 and outputs it to the electro-pneumatic regulator 13 (S15). The control circuit 138 of the electro-pneumatic regulator 13 receives this feedback command value and controls the pressure value to be output.

[0045] In the above embodiment, one fluid control device slave station 12 is connected to the master 11 to control one electro-pneumatic regulator 13, but it is possible to control a plurality of electro-pneumatic regulators 13 by connecting a plurality of fluid control device slave stations 12 to the master 11. When a plurality of fluid control device slave stations 12 are used, for example, at the prototype stage of a semiconductor, if PID parameters set in the first fluid control device slave station 12 are set in the second and subsequent fluid control device slave stations 12 at the time of shipment, there is no need to set PID parameters individually in the second and subsequent fluid control device slave stations 12 at the semiconductor production site.

[0046] As described above, according to the fluid control device slave station 12 of the present embodiment, (1) The field network 1 is comprised of a fluid control device (e.g., an electro-pneumatic regulator 13), a master 11 that outputs a command target value, which is a signal for commanding a target value of the output of the fluid control device (electro-pneumatic regulator 13) (e.g., a target pressure value of the controlled fluid output by the electro-pneumatic regulator 13), and a sensor (e.g., a pressure sensor 14) that detects the output of the fluid control device (e.g., the pressure value of the controlled fluid output by the electro-pneumatic regulator 13) and outputs a detection signal. In the fluid control device slave station 12 that relays signals between the master 11, the fluid control device (electro-pneumatic regulator 13), and the sensor (pressure sensor 14), the fluid control device slave station 12 is characterized in that it includes a feedback control calculation unit 121A that performs feedback control of the fluid control device (electro-pneumatic regulator 13) based on the command target value and the detection signal.

[0047] According to the slave station 12 for the fluid control device described in (1), the slave station 12 for the fluid control device itself can perform feedback control of the fluid control device (electro-pneumatic regulator 13) based on the command target value and the detection signal so that the output of the fluid control device (electro-pneumatic regulator 13) approaches the command target value. Since the slave station 12 for the fluid control device itself performs the feedback control, the number of devices through which the signal passes when transmitting and receiving the signal for the feedback control can be reduced compared to the conventional method. Therefore, the possibility of a delay in the response time from when the sensor (pressure sensor 14) outputs a detection signal to when the output (pressure value) of the fluid control device (electro-pneumatic regulator 13) actually changes is reduced. In addition, by reducing the number of devices through which the signal passes compared to the conventional method, the possibility of the signal being affected by noise when transmitting and receiving the signal is reduced. By using such a slave station 12 for the fluid control device in the electro-pneumatic regulator 13 used in, for example, a wafer polishing device, it is possible to suppress a slight delay in the response time and adverse effects on the quality of the wafer due to the effects of noise.

[0048] (2) In the fluid control device slave station 12 described in (1), the feedback control is PID control, and the fluid control device slave station 12 is characterized in that it includes a parameter setting unit 121B that sets PID parameters.

[0049] According to the slave station 12 for fluid control equipment described in (2), it is possible to improve the work efficiency. For example, when a semiconductor manufacturer uses a fluid control equipment (for example, an electro-pneumatic regulator 13), the master 11 is a facility of the semiconductor manufacturer, and the slave station 12 for fluid control equipment is generally procured from the fluid control equipment manufacturer together with the fluid control equipment (electro-pneumatic regulator 13). In this situation, if the slave station 12 for fluid control equipment has a parameter setting unit 121B for setting PID parameters, the fluid control equipment manufacturer can deliver the fluid control equipment slave station 12 to the semiconductor manufacturer in a state in which the PID parameters determined by the semiconductor manufacturer at the prototype stage of the semiconductor are set in the slave station 12 for fluid control equipment at the shipping stage. Then, even if a plurality of fluid control equipment (electro-pneumatic regulators 13) is introduced at the work site, it is not necessary to set the PID parameters for each of the fluid control equipment (electro-pneumatic regulators 13), so that the work load at the work site can be reduced.

[0050] It should be noted that this embodiment is merely an example and does not limit the present invention in any way. Therefore, the present invention can be improved and modified in various ways without departing from the scope of the invention. For example, although the electropneumatic regulator 13 is given as an example of a fluid control device, other fluid control devices may be used. Furthermore, although the pressure sensor 14 is given as an example of a sensor, the present invention is not limited to this. [Explanation of symbols]

[0051] 1 Field network 11 Master 12 Slave station for fluid control equipment 13 Electro-pneumatic regulator (an example of a fluid control device) 14 Pressure sensor (example of sensor) 121A Feedback control calculation section 121B Parameter setting section

Claims

1. A fluid control device slave station for use in a field network comprising a fluid control device, a master for outputting a command target value which is a signal for commanding a target value of an output of the fluid control device, and a sensor for detecting the output of the fluid control device and outputting a detection signal, the slave station for the fluid control device relaying signals between the master, the fluid control device, and the sensor, a slave station for a fluid control device comprising a feedback control calculation unit that performs feedback control of the fluid control device based on the command target value and the detection signal; the feedback control is a PID control, the slave station for the fluid control device includes a parameter setting unit for setting a PID parameter, and is shipped in a state in which the PID parameter is set; Even when a plurality of the fluid control devices are installed at a work site, it is not necessary to set PID parameters for each of the fluid control devices individually, thereby reducing the workload at the work site. a D / A converter that converts the command target value output from the master into an analog voltage signal; an A / D converter that converts the detection signal output from the sensor into a digital signal; Incorporating The fluid control device is used in a wafer polishing apparatus to adjust a contact pressure when a wafer surface is brought into contact with a polishing pad; A slave station for a fluid control device, comprising:

2. 2. The slave station for fluid control equipment according to claim 1, the fluid control device is an electro-pneumatic regulator; the master commands a target pressure value of the control fluid to be output by the electro-pneumatic regulator as the command target value; the sensor is a pressure sensor and detects a pressure value of the control fluid outputted from the electro-pneumatic regulator; the feedback control calculation unit controls the electro-pneumatic regulator so as to bring the pressure value closer to the target pressure value; A slave station for a fluid control device, comprising:

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