Switching method and device between different precision modes of high-precision motion stage

Abstract

The application discloses a switching method and device between different precision modes of a high-precision motion table, and the method comprises the following steps: during the process that the motion table runs in a servo mode s1, the motion table receives a mode switching instruction and transmits the mode switching instruction to a mode state machine, wherein the servo mode s1 corresponds to a first precision sensor and a controller A, and a servo mode s2 corresponds to a second precision sensor and a controller B; the mode state machine completes state switching corresponding to the switching from the servo mode s1 to the servo mode s2 within a current servo period T1, and transmits the mode switching instruction to a controller output retainer; the controller output retainer latches the output CtrA(T1) of the controller A in the servo mode s1 within the period T1 for one period; the first precision sensor is switched to the second precision sensor, and the controller A is switched to the controller B; and the controller B performs servo control on the basis of the T1 period output CtrA(T1) of the controller A. The controller after the switching continues to output on the inherited output signal, and the switching is realized without delay.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor equipment, in particular to a switching method and device between different precision modes of a high-precision motion table. BACKGROUND

[0002] In actual application, the high-precision motion table usually needs to switch the control precision according to the actual working condition, and the switching of the control precision will involve the switching of the feedback sensor, the control algorithm, the controller parameters and the like. At present, when the motion table switches between different precision servo modes, the high-precision sensor is usually switched to the low-precision sensor directly, or the low-precision sensor is directly switched to the high-precision sensor, the high-precision sensor and the low-precision sensor adopt the same controller, and the controller does not switch. This method of changing the sampling precision to change the servo precision of the motion table has the following defects:

[0003] (1) The switching process is rough, the impact on the motion table is large, and the precise equipment on the motion table is easily damaged;

[0004] (2) The switching process needs a long transition process, which affects the system efficiency and real-time performance;

[0005] (3) The control difficulty of the switching process is large, and the servo open loop is easily caused, and even the runaway accident is caused.

[0006] Up to now, there is no good solution. SUMMARY

[0007] In order to solve the above problems, the switching method between different precision modes of the high-precision motion table provided by the present application adopts the controller output inheritance method to complete the switching process, so as to realize the stable and non-delay switching between different precision servo modes of the motion table. The specific technical scheme is as follows:

[0008] A switching method between different precision modes of a high-precision motion table, comprising:

[0009] In the process that the motion table runs in a servo mode s1, the motion table receives a mode switching instruction and transmits it to a mode state machine, wherein the servo mode s1 corresponds to a first precision sensor and a controller A, and the servo mode s2 corresponds to a second precision sensor and a controller B;

[0010] The mode state machine completes the state switching from the servo mode s1 to the servo mode s2 in a current servo period T1, and transmits the mode switching instruction to a controller output keeper, and the controller output keeper latches the output CtrA(T1) of the controller A of the servo mode s1 in the period T1 for one period;

[0011] Switching from the first precision sensor to the second precision sensor, switching from controller A to controller B, controller B carries out servo control on the basis of CtrA(T1) outputted by controller A in T1 period.

[0012] Optionally, the output function of the controller switching is as follows:

[0013] Wherein, t represents time;

[0014]

[0015] M represents the servo mode;

[0016] Cout(t) represents the output of the current controller at t time, CtrA(t) represents the output of controller A at t time, CtrB(T1) represents the output of controller B at T1 time when the switching occurs;

[0017] CtrB(t) represents the output of controller B at t time, CtrA(T1) represents the output of controller A at T1 time when the switching occurs.

[0018] Optionally, the switching verification is carried out in a plurality of servo periods after the switching is completed, and whether the switching is successful is determined according to the servo precision and the system stability, if it is judged that the switching fails, the servo mode s1 is switched back automatically.

[0019] Optionally, before switching from the first precision sensor to the second precision sensor, the error tracker clears the tracking errors of controller A and controller B in T1 period.

[0020] Optionally, the first precision sensor and the second precision sensor are connected with the motion table respectively, controller A and controller B are connected with the motion table through the same controller output holder, the first precision sensor is connected with controller A through a switch, the second precision sensor is connected with controller B through a switch, and the mode state machine is connected with the control end of the switch, so that the closing of the switch is controlled by the mode state machine to switch the controller.

[0021] Optionally, the switching verification is carried out in not less than 10 servo periods after the switching is completed.

[0022] Optionally, before the mode switching instruction received by the motion table is transmitted to the mode state machine, the received mode switching instruction is analyzed.

[0023] The application also provides a switching device between different precision modes of a high-precision motion table, comprising:

[0024] The switching instruction receiving module is configured to enable the motion table to receive a mode switching instruction and transmit the mode switching instruction to the mode state machine during operation of the motion table in a servo mode s1, wherein the servo mode s1 corresponds to a first precision sensor and a controller A, and the servo mode s2 corresponds to a second precision sensor and a controller B.

[0025] The original output maintaining module is configured to enable the mode state machine to complete state switching corresponding to switching of the servo mode s1 to the servo mode s2 within a current servo period T1, and transmit the mode switching instruction to a controller output keeper, and the controller output keeper latches an output CtrA(T1) of the controller A in the servo mode s1 within the period T1 for one period.

[0026] The continuous control module is configured to enable switching from the first precision sensor to the second precision sensor and from the controller A to the controller B, and the controller B performs servo control on the basis of the T1 period output CtrA(T1) of the controller A.

[0027] Optionally, the continuous control module is provided with an output function of controller switching as follows:

[0028] Wherein, t represents a time point;

[0029]

[0030] M represents a servo mode;

[0031] Cout(t) represents an output of a current controller at the time point t, CtrA(t) represents an output of the controller A at the time point t, and CtrB(T1) represents an output of the controller B at the time point T1 of switching occurrence;

[0032] CtrB(t) represents an output of the controller B at the time point t, and CtrA(T1) represents an output of the controller A at the time point T1 of switching occurrence.

[0033] Optionally, the first precision sensor and the second precision sensor are connected with the motion table respectively, the controller A and the controller B are connected with the motion table through the same controller output keeper, the first precision sensor is connected with the controller A through a switch, the second precision sensor is connected with the controller B through a switch, and the mode state machine is connected with a control end of the switch, so that the mode state machine is used to control closing of the switch to switch the controllers.

[0034] The switching method and device for the high-precision motion table with different precision modes have the following beneficial effects:

[0035] (1) Servo controller switching

[0036] When the servo precision mode is switched, the controller after the switching will switch to the controller corresponding to the precision requirement according to the requirement. The servo modes with different precision have different requirements for the controller capability, and switching the controller according to the requirement when the servo precision mode is switched helps to improve the servo precision and the stability of the switching process.

[0037] (2) Controller output inheritance

[0038] When the servo precision mode is switched, the control output signal before the switching will be retained and inherited by the controller after the switching, and the controller after the switching will continue to output on the inherited output signal. This method can realize the completion of the switching process within 1 servo cycle, and can realize the continuity of the controller output before and after the switching without special smoothing transition process, realizes the non-delay switching, and meets the requirements of arbitrary servo precision and real-time performance.

[0039] (3) Critical error zeroing

[0040] When the servo precision mode is switched, the error signals accumulated by the controllers before and after the switching will be zeroed, and then the error calculation is restarted at the switching time. This method can eliminate the disturbance of the error signal before the switching to the system after the switching, and improve the switching stability. This method is suitable for the system with or without sensor switching in the switching process. BRIEF DESCRIPTION OF DRAWINGS

[0041] The above features and technical advantages of the present application will become more apparent and easily understood from the following description of its embodiments, taken in conjunction with the accompanying drawings.

[0042] Figure 1 is a connection relationship diagram between different precision modes of a motion table of an embodiment of the present application;

[0043] Figure 2 is a flow chart of a switching method between different precision modes of a high-precision motion table of an embodiment of the present application;

[0044] Figure 3 is a control logic diagram of the switching of the servo mode s1 to s2 of an embodiment of the present application

[0045] Figure 4 is a module composition diagram of a switching device between different precision modes of a high-precision motion table of an embodiment of the present application. DETAILED DESCRIPTION

[0046] Embodiments of the present application will be described below with reference to the accompanying drawings. Those skilled in the art can appreciate that the described embodiments can be modified in various ways or combinations without departing from the spirit and scope of the present application. Therefore, the accompanying drawings and description are illustrative in nature and are not intended to limit the scope of protection of the claims. In addition, in the present specification, the drawings are not drawn to scale, and the same reference numerals represent the same parts.

[0047] In this embodiment, the connection relationship between different precision modes of the high-precision motion stage is as shown in Figure 1 The first precision sensor (corresponding to the high-precision mode s1) and the second precision sensor (corresponding to the low-precision mode s2) are connected to the motion stage (controlled object) as measurement elements of two precision levels in the measurement system. Both controller A and controller B are connected to the motion stage through the same controller output holder. The mode state machine is connected to the first precision sensor and the second precision sensor, and the first precision sensor and the second precision sensor are respectively connected to controller A and controller B through switches. The mode state machine is connected to the control end of the switch, so that the closing of the switch can be controlled by the mode state machine, thereby switching the controller. It should be noted that this embodiment is described in two precision modes, but the number of precision modes is not limited by the present application, for example, there can be three precision modes, and the three precision modes are switched back and forth.

[0048] Figure 2 is a flow chart of the switching method between different precision modes of the high-precision motion stage, Figure 3 is a control logic diagram of switching from servo mode s1 to servo mode s2, which is described in combination with Figure 2 , Figure 3 The switching method between different precision modes of the high-precision motion stage of this embodiment includes the following steps:

[0049] Step S1, after the initialization of the motion stage is completed, enter the servo mode s1, and in the process of running the motion stage in the servo mode s1, the motion stage (controlled object) receives and analyzes the mode switching instruction M, confirms the servo mode s2 to be switched in, and sends it to the mode state machine;

[0050] Step S2, the mode state machine receives the mode switching instruction, completes the state switching required for the mode s1 to s2 in the current servo period T1, and at the same time transmits the mode switching instruction to the controller output holder, and the controller output holder latches the output CtrA(T1) of the controller A of the servo mode s1 in the T1 period for one period.

[0051] The mode state machine is composed of a state register and a combination logic circuit, and can perform state transition according to a preset state according to a mode switching instruction, and is a control center for coordinating the actions of related signals and completing specific operations.

[0052] Step S3, the error tracker clears the tracking errors of controllers A and B in the T1 period, so that the tracking states of the two controllers at the switching time are synchronized.

[0053] Step S4, switch from the first precision sensor to the second precision sensor, because the servo precision changes, the sensor of the feedback signal needs to be changed synchronously to match the sampling precision and the servo precision.

[0054] Step S5, switch from controller A to controller B, different controllers have different control capabilities for servo precision, and in different precision modes, the controller matching the precision requirement is selected according to the precision requirement. The use of the controller matching the precision and the mode before and after the switching can improve the switching success rate and effectively suppress the disturbance caused by the switching process and protect the precision instrument.

[0055] Step S6, the controller B of the servo mode s2 will start servo control based on the output CtrA(T1) of the controller A of the servo mode s1.

[0056] The output function of the controller switching is as follows:

[0057]

[0058] Where, t represents the time;

[0059] M represents the servo mode, 0 represents the s1 mode, and 1 represents the s2 mode.

[0060] Cout(t) represents the output instruction of the current controller at time t, CtrA(t) represents the output of controller A at time t, and CtrB(T1) represents the output of controller B at time T1 when the switching occurs.

[0061] CtrB(t) represents the output of controller B at time t, and CtrA(T1) represents the output of controller A at time T1 when the switching occurs.

[0062] When switching from the servo mode s1 to the servo mode s2, the current controller is controller B, and the output of controller B includes the output CtrA(T1) of controller A in the T1 period, and the output CtrB(t) of controller B is added to be used as the output of controller B.

[0063] When switching from the servo mode s2 to the servo mode s1, the current controller is the controller A, and the output of the controller A comprises the output CtrB(T1) of the controller B in the T1 period and the output CtrA(t) of the controller A.

[0064] This mode makes the original outputs of the two different controllers A and B continuous, and the switching is quickly completed.

[0065] Further, the switching verification is also included, and the switching verification is performed in the 10 servo periods after the switching is completed.

[0066] The application also provides a switching device 100 between different precision modes of a high-precision motion table, which comprises a switching instruction receiving module 101, an original output keeping module 102 and a continuous control module 103.

[0067] The switching instruction receiving module 101 is used for enabling the motion table to receive a mode switching instruction and transmit the mode switching instruction to a mode state machine during the process that the motion table runs in the servo mode s1, wherein the servo mode s1 corresponds to the first precision sensor and the controller A, and the servo mode s2 corresponds to the second precision sensor and the controller B.

[0068] The original output keeping module 102 is used for enabling the mode state machine to complete the state switching from the servo mode s1 to the servo mode s2 in the current servo period T1, and transmit the mode switching instruction to a controller output keeper.

[0069] The continuous control module 103 is used for enabling the first precision sensor to be switched to the second precision sensor and the controller A to be switched to the controller B, and enabling the controller B to perform servo control on the basis of the T1 period output CtrA(T1) of the controller A.

[0070] The functions of the modules of the switching device are the same as the steps in the above switching method, and will not be described in detail here.

[0071] The above merely illustrates the preferred embodiments of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A switching method between different precision modes of a high-precision motion stage, characterized in that, Comprising: During the process that the motion stage is running in the servo mode s1, the motion stage receives a mode switching instruction and transmits it to a mode state machine, wherein the servo mode s1 corresponds to a first precision sensor and a controller A, and the servo mode s2 corresponds to a second precision sensor and a controller B; The mode state machine completes the state switching from the servo mode s1 to the servo mode s2 in a current servo period T1, and transmits the mode switching instruction to a controller output keeper, which latches the output CtrA(T1) of the controller A in the servo mode s1 in the T1 period; The first precision sensor is switched to the second precision sensor, and the controller A is switched to the controller B, which performs servo control on the basis of the T1 period output CtrA(T1) of the controller A, The output function of the controller switching is as follows: Wherein, t represents the time; M represents the servo mode; Cout(t) represents the output of the current controller at the time t, CtrA(t) represents the output of the controller A at the time t, and CtrB(T1) represents the output of the controller B at the time T1 when the switching occurs; CtrB(t) represents the output of the controller B at the time t, and CtrA(T1) represents the output of the controller A at the time T1 when the switching occurs, The first precision sensor and the second precision sensor are connected with the motion stage respectively, the controller A and the controller B are connected with the motion stage through the same controller output keeper, the first precision sensor is connected with the controller A through a switch, the second precision sensor is connected with the controller B through a switch, and the mode state machine is connected with the control end of the switch, so that the closing of the switch is controlled by the mode state machine to switch the controllers.

2. The switching method between different precision modes of the high-precision motion stage according to claim 1, wherein Switching verification is performed in a plurality of servo periods after the switching is completed, and whether the switching is successful is determined according to the servo precision and the system stability, and if it is judged that the switching fails, the servo mode s1 is switched back automatically.

3. The switching method between different precision modes of the high-precision motion stage according to claim 1, wherein Before the first precision sensor is switched to the second precision sensor, the error tracker clears the tracking errors of the controller A and the controller B in the T1 period.

4. The switching method between different precision modes of the high-precision motion stage according to claim 2, wherein The switching verification is performed in not less than 10 servo periods after the switching is completed.

5. The switching method between different precision modes of the high-precision motion stage according to claim 2, wherein Before the motion stage receives the mode switching instruction and transmits it to the mode state machine, the received mode switching instruction is analyzed.

6. A switching device between different precision modes of a high-precision motion stage, characterized in that, Comprising: A switching instruction receiving module, configured to, during the process that the motion stage is running in the servo mode s1, the motion stage receives a mode switching instruction and transmits it to a mode state machine, wherein the servo mode s1 corresponds to a first precision sensor and a controller A, and the servo mode s2 corresponds to a second precision sensor and a controller B; The original output holding module is used for making the mode state machine complete the state switching from the servo mode s1 to the servo mode s2 in the current servo period T1, and transmitting the mode switching instruction to the controller output holder, which latches the output CtrA(T1) of the controller A in the servo mode s1 in the T1 period for one period; The continuous control module is used for switching from the first precision sensor to the second precision sensor, and from the controller A to the controller B, and the controller B performs servo control on the basis of the T1 period output CtrA(T1) of the controller A, The continuous control module is provided with an output function of controller switching as follows: Wherein, t represents the time; M represents the servo mode; Cout(t) represents the output of the current controller at the time t, CtrA(t) represents the output of the controller A at the time t, and CtrB(T1) represents the output of the controller B at the time T1 when the switching occurs; CtrB(t) represents the output of the controller B at the time t, and CtrA(T1) represents the output of the controller A at the time T1 when the switching occurs, The first precision sensor and the second precision sensor are respectively connected with the motion table, the controller A and the controller B are connected with the motion table through the same controller output holder, the first precision sensor is connected with the controller A through a switch, the second precision sensor is connected with the controller B through a switch, and the mode state machine is connected with the control end of the switch, so that the closing of the switch is controlled by the mode state machine to switch the controllers.

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