Design aid equipment, design aid method and design aid program

Abstract

[Problem] When designing mechanical elements constituting a mechanical device driven by a feedback-controlled electric motor, a user is enabled to easily confirm how the characteristics of the mechanical elements affect the generation of abnormal vibrations of the mechanical device. [Solution] A design assistance device (1) is used to perform design assistance processing of the mechanical device, wherein the design assistance device (1) is configured to cause a processor (11) to: set a plurality of parameters in a mathematical model of an element to be analyzed from one or more mechanical elements (24, 56, 58) constituting the mechanical device (21, 51); calculate the extreme values ​​of the transfer function of the mechanical device based on the plurality of parameters with respect to one or more vibration modes of the mechanical device (21, 51); and create a stability discriminant line diagram including contour lines of the real part of the extreme values ​​of the transfer function.

Description

Technical Field

[0001] The present invention relates to a design assistance apparatus, a design assistance method, and a design assistance program configured to support the design of a mechanical device driven by a feedback-controlled electric motor. Background Art

[0002] In a feed drive mechanism that converts the rotational motion of a servo motor controlled by a feedback control system into linear motion of a stage via a ball screw and a nut, it is known that increasing the gain constant of the feedback control system increases the responsiveness and accuracy of the servo motor's rotational motion. However, it is also known that if the gain constant is too large, abnormal vibration may occur at the natural frequency (eigenfrequency) that depends on the mass and stiffness of the various parts of the feed drive mechanism.

[0003] Conventionally, as a technique for determining appropriate characteristics of a control system, it is known to generate a root locus diagram based on the characteristics of the corresponding mechanical system. See Non-Patent Document 1. As a method for improving the overall performance of a mechanical device, it is also known to design various components of the mechanical device by analyzing the relationship between the moment of inertia and stiffness of the mechanical elements and the servo stiffness, which is a performance indicator of the mechanical device. See Non-Patent Document 2. To assist in the optimal design of a mechanical device, it is also known to simulate its characteristics based on a model of the mechanical device. See Patent Document 1.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: JP2008-102714A

[0007] Non-patent literature

[0008] Non-Patent Document 1: “Design and Control of Precision Positioning and FeedDrive systems”, Matsubara Atsushi, Morihoku Publishing, 2008.

[0009] Non-patent document 2: “A Study on the Total Tuning of Feed Drive System in NCMachine Tools (3rd report)-Single Axis Mechanical Parameter Tuning”, Yoshiaki Nakano, Atsushi Matsubara, Daisuke Ueda, Hideo Nakagawa, Takuo Takeshita, Hisaichi Maruyama, Journal of the Japan Society of Precision Engineering, Vol. 62, No. 3, (1996), pp. 423-427. Summary of the Invention

[0010] Tasks to be achieved by the present invention

[0011] However, the ultimate performance of a mechanical device is limited by the characteristics of its mechanical system. The prior art disclosed in Non-Patent Document 1 is strictly related to the control system and does not consider the mechanical device itself or its mechanical elements. The prior art disclosed in Non-Patent Document 2 only considers the first-order natural frequency and fails to provide users with sufficient information about the vibrations that may occur in the mechanical device. The prior art disclosed in Patent Document 1 provides a design that optimizes servo gain when forming a desired shape by simultaneously actuating multiple feed drive mechanisms, but fails to provide guidance on how to design the characteristics of the mechanical system to improve its performance.

[0012] When a user designs (or selects) mechanical elements that form a mechanical device, it is desirable for the user to know how the characteristics of each mechanical element affect the generation of abnormal vibration of the mechanical device. However, the above-mentioned prior art cannot meet such needs or convenience of the user.

[0013] In view of such problems in the prior art, the main object of the present invention is to provide a design assistance device, a design assistance method, and a design assistance program, which are configured to support the design of a mechanical device driven by a feedback-controlled electric motor in a manner that enables a user to easily know how the characteristics of the mechanical elements affect the generation of abnormal vibrations of the mechanical device.

[0014] Means of achieving tasks

[0015] To achieve this object, a first aspect of the present invention provides a design assistance device (1) provided with a processor (11) configured to perform processing for assisting the design of a mechanical device (21, 51) driven by a feedback-controlled electric motor (23, 57), wherein the processor is configured to set a plurality of parameters of a mathematical model of an analysis target element selected from one or more mechanical elements (24, 56, 58) forming the mechanical device, calculate the poles of a transfer function of the mechanical device associated with one or more vibration modes of the mechanical device based on the plurality of parameters, and create a stability discriminant diagram including contour lines of the real part of the poles of the transfer function.

[0016] Thus, when designing (or selecting) the mechanical elements that form a mechanical device, the user can easily understand how the characteristics (parameters) of the mechanical elements affect the generation of abnormal vibrations in the mechanical device. This allows the user to prevent the occurrence of abnormal vibrations in the mechanical device in advance, and to obtain specific guidance on improvements to the characteristics of the mechanical elements that may be necessary to suppress abnormal vibrations that have already occurred in the mechanical device.

[0017] According to a second aspect of the present invention, the design aid device further includes a display unit for displaying the stability discriminant diagram (41, 71).

[0018] Thus, the user can easily visually grasp the influence of the characteristics of the mechanical elements on the occurrence of abnormal vibration of the mechanical device by using the stability discrimination diagram displayed on the display unit.

[0019] According to a third aspect of the present invention, when the mechanical device has a plurality of vibration modes, the stability discriminant map created by the processor includes contour lines of real parts of poles of transfer functions corresponding to respective vibration modes.

[0020] Thus, the user can grasp the influence of the characteristics of the mechanical elements on the occurrence of abnormal vibration of the mechanical device in a more reliable manner by using the stability discrimination diagram based on the vibration pattern displayed on the display unit.

[0021] According to a fourth aspect of the present invention, the plurality of parameters include parameters related to stiffness and damping characteristics of the mechanical element.

[0022] Thus, the user can appropriately grasp the influence of the characteristics of the mechanical elements on the occurrence of abnormal vibration of the mechanical device.

[0023] According to the fifth aspect of the present invention, when the poles of the transfer function are arranged in descending order of their imaginary parts, contour lines are generated for the real parts of the poles that have the difference between the degree of freedom of the mathematical model and the number of vibration modes in descending order.

[0024] Thus, a stability discriminant diagram including contours of the real part of the extreme points of the transfer function can be generated in an appropriate manner.

[0025] According to a sixth aspect of the present invention, the processor is configured to create the stability discriminant map to include indicia indicating a plurality of parameters of one or more target products that can be candidates for the mechanical element.

[0026] Thus, when selecting a mechanical element, the user can understand how the characteristics (parameters) of the target product, which is a candidate for the mechanical element, affect the occurrence of abnormal vibration in the mechanical device. Consequently, the user can select a mechanical element to prevent the occurrence of abnormal vibration in the mechanical device or to suppress abnormal vibration that has already occurred in the mechanical device.

[0027] A seventh aspect of the present invention provides a design assistance method for assisting the design of a mechanical device (21, 51) driven by a feedback-controlled electric motor (23, 57), comprising the following steps: setting multiple parameters of a mathematical model of an analysis target element selected from one or more mechanical elements (24, 56, 58) forming the mechanical device; calculating the poles of the transfer function of the mechanical device associated with one or more vibration modes of the mechanical device based on the multiple parameters; and creating a stability discriminant diagram including contour lines of the real part of the poles of the transfer function.

[0028] Thus, when designing (or selecting) the mechanical elements that form a mechanical device, the user can easily understand how the characteristics (parameters) of the mechanical elements affect the generation of abnormal vibrations in the mechanical device. This allows the user to prevent the occurrence of abnormal vibrations in the mechanical device in advance, and to obtain specific guidance on improvements to the characteristics of the mechanical elements that may be necessary to suppress abnormal vibrations that have already occurred in the mechanical device.

[0029] An eighth aspect of the present invention provides a design assistance program that performs processing for assisting the design of a mechanical device (21, 51) driven by a feedback-controlled electric motor (23, 57), characterized in that a computer (1) is caused to perform the following processes: setting multiple parameters of a mathematical model of an analysis target element selected from one or more mechanical elements (24, 56, 58) forming the mechanical device; calculating the poles of the transfer function of the mechanical device associated with one or more vibration modes of the mechanical device based on the multiple parameters; and creating a stability discriminant diagram including contour lines of the real part of the poles of the transfer function.

[0030] Thus, when designing (or selecting) the mechanical elements that form a mechanical device, the user can easily understand how the characteristics (parameters) of the mechanical elements affect the generation of abnormal vibrations in the mechanical device. This allows the user to prevent the occurrence of abnormal vibrations in the mechanical device in advance, and to obtain specific guidance on improvements to the characteristics of the mechanical elements that may be necessary to suppress abnormal vibrations that have already occurred in the mechanical device.

[0031] Effects of the present invention

[0032] As described above, according to the present invention, when designing mechanical elements constituting a mechanical device driven by an electric motor under feedback control, a user can easily grasp the influence of the characteristics of the mechanical elements on the occurrence of abnormal vibration of the mechanical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] [ Figure 1 ] Functional block diagram of design auxiliary equipment;

[0034] [ Figure 2 ]Hardware structure diagram of design auxiliary equipment;

[0035] [ Figure 3 ] A flow chart of a design assistance process performed by a design assistance device;

[0036] [ Figure 4 ] A diagram of a first mechanical device given as an example of the application of the design assistance process;

[0037] [ Figure 5 ] a mechanical model of the first mechanical device;

[0038] [ Figure 6 ] A block diagram of a control system for an electric motor of a first mechanical device;

[0039] [ Figure 7 ] Example of a stability discriminant diagram for a coupling of a first mechanical device;

[0040] [ Figure 8 ] A graph showing changes in the rotational speed of a target product given as a candidate for a coupling of a first mechanical device (A: first coupling, B: second coupling);

[0041] [ Figure 9 ] A view showing an example of a GUI screen generated by design assistance software executed by a design assistance apparatus in conjunction with a design of a first mechanical device;

[0042] [ Figure 10 ] A diagram of a second mechanical device given as an example of the application of the design assistance process;

[0043] [ Figure 11] a diagram of a mechanical model of a second mechanical device;

[0044] [ Figure 12 ] Graphs associated with examples of stability discriminant diagrams of a support bearing of a second mechanical device (A: primary vibration mode, B: secondary vibration mode);

[0045] [ Figure 13 ] A graph showing changes in the rotational speed of a target product given as a candidate for the support bearing of the second mechanical device (A: first support bearing, B: second support bearing);

[0046] [ Figure 14 ] A diagram showing an example of a stability discrimination diagram for a coupling of a second mechanical device (A: first-order vibration mode, B: second-order vibration mode);

[0047] [ Figure 15 ] A graph showing changes in the rotational speed of a target product given as a candidate for the coupling of the second mechanical device (A: first coupling, B: second coupling);

[0048] [ Figure 16 ] Figure 14 A modification of the stability discriminant diagram shown; and

[0049] [ Figure 17 ] A view of an example of a GUI screen generated by the design assistance software executed by the design assistance apparatus in conjunction with the design of the second mechanical device. DETAILED DESCRIPTION

[0050] The present invention will be described below based on specific embodiments with reference to the accompanying drawings.

[0051] Figure 1 and Figure 2 1 and 2 are a functional block diagram and a hardware structure diagram of a design support device 1 according to an embodiment of the present invention, respectively.

[0052] The design assistance device 1 performs processing for assisting the design of a mechanical device driven by a feedback-controlled motor (hereinafter referred to as "design assistance processing"), and particularly allows the user to easily grasp the influence of the characteristics of the mechanical elements (parameters of the mathematical model) that form the mechanical device on the occurrence of abnormal vibration of the mechanical device in combination with the design of the mechanical elements (including the selection of the mechanical elements).

[0053] like Figure 1As shown, the design assistance apparatus 1 basically includes: a transfer function calculation unit 2 for calculating a transfer function of a mechanical device representing dynamic response characteristics of the mechanical device from a mathematical model composed of a mathematical expression simulating characteristics of the mechanical device (not shown in the figure); an analysis parameter setting unit 3 for setting a parameter range of the mathematical model of a mechanical element to be analyzed (hereinafter referred to as an "analysis target element"); a fixed parameter setting unit 4 for setting parameters of the mathematical model of mechanical elements other than the analysis target element; a vibration mode setting unit 5 for setting the vibration mode of the analysis target element; a stability discriminant diagram creation unit 6 for calculating the poles of the transfer function of the mechanical device in combination with one or more vibration modes and creating a stability discriminant diagram including contour lines of the real parts of the poles; and a display unit 7 for accepting input of various settings made by a user (for example, see Figure 9 ), and displays analysis results, such as a stability discriminant diagram to be described below.

[0054] The design support device 1 is constituted by a computer provided with hardware known per se, and Figure 2 As shown, it includes: one or more processors 11, which are used to perform design assistance processing according to design assistance software (control program); RAM (random access memory) 12, which serves as a working area for the processor 11; ROM (read-only memory) 13, which stores the control program and data executed by the processor 11; and a network interface (I / F) 14, which is composed of a network adapter, which is used to allow the design assistance device 1 to be connected to a communication network known per se, and these components are connected to an input / output bus 15.

[0055] The design assistance device 1 is also provided with peripheral devices, such as an input device 16 consisting of a keyboard and a mouse that can be used by the user to enter various settings in the design assistance device 1, together with a display of analysis results, a display device 17 consisting of an LCD monitor forming the display unit 7, an external storage device 18 consisting of a storage device such as an HDD or a flash memory, and the like. Figure 1 The functions of the various units or devices of the illustrated design aid apparatus 1 can be implemented by the processor 11 executing a predetermined control program including design aid software.

[0056] The hardware of the design support device 1 is not limited to Figure 2 The hardware shown is sufficient as long as it can execute the design support process and can be changed as appropriate. For example, the design support apparatus 1 can also be implemented by a plurality of computers.

[0057] Figure 31 is a flowchart showing the flow of a design assistance process (design assistance method) executed by the design assistance apparatus 1 (stability discriminant diagram creation unit 6 ).

[0058] In the design aid 1, the user can select any parameters of the mathematical model of the mechanical device (for example, two parameters A and B). These parameters are indicated on the horizontal and vertical axes of the stability discriminant diagram (see the diagram described below). Figure 7 ).

[0059] At the start of the design support process, the user selects the number n and m of divisions of the horizontal and vertical axes, respectively (ST101), with the result that the analysis range of parameter A is divided into n increments (ST102), and the analysis range of parameter B is divided into m increments (ST103). The division of the horizontal and vertical axes can be performed linearly or logarithmically. Furthermore, the user does not have to set the number of divisions n and m each time, and can also use the number of divisions n and m pre-stored in the external storage device 18 or the like. Here, if the number of divisions is large, the analysis can be performed with higher resolution, but the computational load increases. Therefore, the range of the number of divisions of the horizontal and vertical axes can be predetermined (for example, by setting an upper limit value and / or a lower limit value).

[0060] The parameters Ai (i=1 to n) and Bj (j=1 to m) to be analyzed (in other words, the values ​​of the parameters A and B that vary according to the respective division numbers n and m) are substituted into the transfer function, and poles are sequentially calculated (ST104). At this time, the poles of the transfer function can be obtained as the roots of the denominator polynomial of the transfer function.

[0061] Here, assuming that the degrees of freedom of the mechanical device model are DOF, the number of vibration modes of the mechanical device is (DOF-1). The absolute value of the imaginary part of each pole determined in step ST104 corresponds to the vibration frequency of the pole. When the Nth-order vibration mode is to be analyzed, the absolute value of the real part of the pole with the (DOF-N)th largest imaginary part absolute value is stored in an external storage device as Cij (ST105). Therefore, when the Nth-order vibration mode is to be analyzed, the pole with the (DOF-N)th largest imaginary part absolute value among the poles determined in step ST104 corresponds to the Nth-order vibration mode. The real part of each pole of the transfer function is related to the stability of the mechanical machine. If the real part value is negative, the mechanical device is stable; if the real part value is positive, the mechanical device is unstable.

[0062] Then, by calculating contour lines on a graph having A along the horizontal axis and B along the vertical axis with respect to the real part value Cij obtained in step ST105, a stability discriminant map including contour lines (graph data including contour lines) can be created (ST106). The created stability discriminant map is stored in the external storage device 18. The stability discriminant map can be a three-dimensional graph based on the parameters Ai and Bj and the real part value Cij.

[0063] As will be described below, the user can refer to the stability discrimination chart described above when designing (including selecting) mechanical elements that constitute a mechanical device. The user can preferably refer to the stability discrimination chart by displaying a design assistance screen including the stability discrimination chart on the display device 17. However, the present invention is not limited to this, and other forms (e.g., voice output on the stability discrimination chart) may also be used for this purpose.

[0064] This allows users to easily understand how the characteristics (parameters) of various mechanical elements affect the occurrence of abnormal vibration in a mechanical device. This allows users to proactively prevent abnormal vibration in newly designed mechanical devices. Furthermore, if abnormal vibration occurs in an existing mechanical device, users can receive specific guidance on how to improve and suppress it.

[0065] The following describes a design assistance apparatus 1 and a design assistance method according to preferred embodiments of the present invention.

[0066] Figure 4 is a diagram showing a first mechanical device 21 as an example of application of the design assistance process performed by the design assistance apparatus 1, and Figure 5 2 is a diagram showing a mechanical model of the first mechanical device 21 . Figure 6 is a block diagram of a control system for the electric motor 23 used in the first mechanical device 21 .

[0067] like Figure 4 As shown, a mechanical device 21 is configured as a rotational drive mechanism for a roller 22 in a printing press and includes an electric motor 23 for driving the roller 22 and a coupling 24 connecting a shaft 22a extending from one end of the roller 22 to an output shaft 23a of the electric motor 23. In this case, the analysis target element of the design support device 1 is the coupling 24. By appropriately designing the stiffness and damping characteristics of the coupling 24, the performance of the drive mechanism can be improved.

[0068] Figure 5 The mechanical model shown represents the mechanical characteristics of the rotary drive mechanism of the mechanical device 21. The speed of the electric motor 23 is feedback controlled, as shown in FIG. Figure 6Here, Tm is the output torque of the electric motor 23, θm is the rotation angle of the electric motor 23, and θr is the rotation angle of the roller 22. Table 1 shows Figure 5 and Figure 6 Parameters are shown along with numerical examples used for the analysis.

[0069] Table 1

[0070]

[0071] from Figure 5 The following motion equation is obtained from the mechanical model shown in the figure, and from this motion equation and Figure 6 The block diagram shown makes it possible to calculate the transfer function of the entire mechanical device 21 based on methods known per se.

[0072] [Equation 1]

[0073]

[0074] Figure 7 It shows about Figure 4 A graph showing an example of a stability discriminant diagram of the coupling 24 of the first mechanical device 21 is shown, and Figure 8 (A) and (B) show changes in the rotational speed of a target product (which may be the first coupling or the second coupling) given as an example of the coupling 24 of the first mechanical device 21 .

[0075] exist Figure 7 In the stability discriminant diagram shown, the stiffness and damping characteristics (torsional stiffness and motor-roller viscous friction coefficient) of the coupling 24 are used as parameters and are shown along the horizontal axis and the vertical axis, respectively. Figure 7 The numerical values ​​associated with each contour line in (here, -50, 0, 50, 100) are the values ​​of the real part of the transfer function for the secondary vibration mode of the mechanical device 21. In this example, except for the region where the torsional stiffness is relatively small (for example, the torsional stiffness is less than 2.0×10 5 In the stable region where the value of the real part of the transfer function is negative, abnormal vibration is unlikely to be generated in the mechanical device 21, while in the unstable region where the value of the real part is positive, abnormal vibration is likely to occur in the mechanical device 21. The stability discrimination diagram is not limited to Figure 7 As shown in the figure, and for example, Figure 7 The horizontal and vertical axes shown may be interchanged with one another.

[0076] Figure 8 (A) and (B) respectively show changes in the rotation speed of the roller 22 when the rotation speed of the motor 23 increases from zero to 100 rpm in the mechanical device 21 to which the first coupling and the second coupling are applied as the coupling 24 .

[0077] Here, the values ​​of the stiffness and damping characteristics of the first coupling are located in the unstable region of the stability discriminant diagram, as shown in Figure 7 On the other hand, the values ​​of the torsional stiffness and viscous damping characteristics of the second coupling are located in the stable region of the stability discriminant diagram, as shown in Figure 7 The "target product" used in the present invention may be selected from existing products such as commercial products, but may also be a newly designed and manufactured mechanical element.

[0078] like Figure 8 As shown in (A), when the first coupling having values ​​of stiffness and damping characteristics in the unstable region is applied to the mechanical device 21, abnormal vibration occurs as the roller 22 rotates. It is understood that normal use of the mechanical device 21 is difficult. On the other hand, as Figure 8 As shown in (B), when the second coupling having values ​​of stiffness and damping characteristics that are in the stable region is applied to the mechanical device 21, the roller 22 of the mechanical device 21 can rotate in a normal manner.

[0079] Thus, the user can easily grasp the influence of the characteristics of the coupling 24 (in this case, the stiffness and damping characteristics) on the vibration of the mechanical device 21 from the above-mentioned stability discrimination diagram. Therefore, the user can prevent abnormal vibration from occurring in the mechanical device 21 by designing (including selecting) the coupling 24 so that the values ​​of the stiffness and damping characteristics are within the stable region. In addition, when abnormal vibration occurs in the mechanical device 21, the user can obtain specific improvement guidance related to the stiffness and damping characteristics of the coupling 24 for suppressing the generation of vibration. By using the present invention, guidance for ensuring stable operation of mechanical elements such as couplings can be displayed in such a way that allows the user to easily make the necessary decisions. Therefore, a highly advantageous effect can be achieved.

[0080] Figure 9 1 is a diagram showing an example of a GUI (Graphical User Interface) screen 30 created by design assisting software installed in the design assisting apparatus 1 in conjunction with the design assisting operation of the first mechanical device 21 .

[0081] like Figure 9As shown, the GUI screen 30 includes an analysis parameter setting bar 31, which enables the user's input operation, and the input operation is used to select the range of the parameters of the analysis target element set by the analysis parameter setting unit 3 (here, the stiffness and damping characteristics of the coupling 24, etc.). The fixed parameter setting bar 32 enables the user's input operation, and the input operation is used to select the parameters of the mechanical elements other than the analysis target element set by the fixed parameter setting unit 4 (such as the speed loop proportional gain Kvp, the speed loop integral gain Kvi, the viscous friction coefficient of the electric motor, the viscous friction coefficient of the roller, the motor-roller viscous damping coefficient, etc.). Further, the analysis result output bar 33 displays the analysis result in accordance with the user's specified operation. Figure 7 The graph shown corresponds to a stability discrimination graph 41 and a three-dimensional graph 42. By checking "Rotate Open" on the GUI screen, the three-dimensional graph 42 can be displayed from any desired viewpoint. The "Rotate Open" display can be omitted to allow for constant rotation, or the viewpoint can be fixed.

[0082] The transfer function calculation unit 2 is a part of the design support software, and the parameters of the mechanical elements that do not need to be changed are stored in advance in the external storage device 18 as data belonging to the design support software. In this particular case, since the vibration mode of the mechanical device 21 is one, as will be described below, Figure 17 The vibration pattern setting column shown is not essential, and the above-mentioned vibration pattern setting unit 5 may be omitted.

[0083] In the design support device 1, various settings can be input by the user using the GUI screen 40, and analysis results (such as a stability discriminant diagram) can also be output to the user. As such output of analysis results, the analysis result output column 33 can display a root locus diagram 45 created from the parameters of the coupling 24 using a method known per se.

[0084] Figure 10 is a diagram showing a second mechanical device 51 given as another example of application of the design assisting process performed by the design assisting apparatus 1, and Figure 11 2 is a diagram showing a mechanical model of the mechanical device 51. With respect to the second mechanical device 51, reference should be made to the above description of the first mechanical device 21 for matters not particularly mentioned below.

[0085] like Figure 10As shown, a mechanical device 51 is configured as a feed drive mechanism for manufacturing equipment (e.g., a machine tool) and includes a ball screw 52, ​​a table 54 attached to a nut 53 of the ball screw 52, ​​a support bearing 56 supporting a screw shaft 55 of the ball screw 52, ​​a servo motor 57 for driving the ball screw 52, ​​and a coupling 58 connecting an end 55a of the screw shaft 55 to an output shaft 57a of the servo motor 57. This configuration enables the mechanical device 51 to convert the rotational motion of the servo motor 57 into linear motion of the table 54 via the screw shaft 55 and the nut 53. The elements to be analyzed by the design aid 1 are the coupling 58 and the support bearing 56. By appropriately designing the stiffness and damping characteristics of the coupling 58 and the support bearing 56, the performance of the feed drive mechanism of the mechanical device 51 can be improved.

[0086] Figure 11 The mechanical model shown represents the mechanical characteristics of the drive mechanism of the mechanical device 21. Figure 11 Where Tm is the output torque of the servo motor 57, θm is the rotation angle of the servo motor 57, θs is the rotation angle of the screw shaft 55, xs is the axial displacement of the screw shaft 55, and xt is the axial displacement of the stage 54. Table 2 shows Figure 11 Parameters are shown along with numerical examples used for the analysis.

[0087] Table 2

[0088]

[0089]

[0090] The equation of motion given below is Figure 11 The mechanical model shown is obtained, and the transfer function of the entire mechanical device 51 can be based on the motion equation and Figure 6 The block diagram shown is similar to the block diagram for calculation.

[0091] Equation 2

[0092]

[0093] Figure 12 (A) and (B) are respectively Figure 10 The stability discrimination diagram shown is related to the primary vibration mode and the secondary vibration mode of the support bearing 56, which is one of the mechanical elements of the second mechanical device 51. Figure 13 (A) and (B) show speed changes in the case of using target products (a first support bearing and a second support bearing) as candidates for the support bearing 56 of the second mechanical device 51 .

[0094] exist Figure 12In the stability discrimination diagrams shown in (A) and (B) of FIG. 5 , the stiffness and damping characteristics (axial stiffness and axial viscous damping coefficient) of the support bearing 56 are used as parameters and are indicated along the horizontal axis and the vertical axis, respectively. Figure 11 The mechanical model of the mechanical device 51 shown has four degrees of freedom, so the number of vibration modes is three. Here, only two vibration modes ( Figure 12 The primary vibration mode shown in (A) and Figure 12 (B) shows the secondary vibration mode shown in the stability discrimination diagram.

[0095] With the above Figure 7 The same is true for Figure 12 In (A) and (B), in the stable region where the real part of the transfer function is negative, the possibility of abnormal vibration occurring in the mechanical device 51 is low. On the other hand, in the unstable region where the real part is positive, the possibility of abnormal vibration occurring in the mechanical device 51 is high.

[0096] Figure 13 (A) and (B) show responses (speed changes) of the mechanical device 51 to which the first support bearing and the second support bearing are respectively applied as the support bearing 56 when the speed command of the servo motor 57 is changed in a stepwise manner.

[0097] Here, the values ​​of the axial stiffness and axial viscous damping coefficient of the first support bearing are Figure 12 (A) and (B) are indicated by triangle marks (Δ), and for Figure 12 The primary vibration mode shown in (A) is in the stable region, but for Figure 12 The secondary vibration mode shown in (B) is located in the unstable region. Moreover, the values ​​of the axial stiffness and axial viscous damping coefficient of the second support bearing are Figure 12 (A) and (B) are indicated by circle marks (○), and opposite to the first support bearing, for Figure 12 The primary vibration mode shown in (A) is in the unstable region, but for Figure 12 The secondary vibration mode shown in (B) is located in the stable region.

[0098] exist Figure 13 In the case of the first support bearing shown in (A), the vibration is Figure 13 The case of the second support bearing shown in (B) has a higher frequency. This corresponds to the value of the axial stiffness and axial viscous damping coefficient of the first support bearing being located at Figure 12 The fact that the stability discriminant map shown in (B) is in the unstable region.

[0099] Thus, by using Figure 12The stability discrimination diagrams shown in (A) and (B) of FIG. 1 and FIG. 2 show how the characteristics of the support bearing 56 of the mechanical device 51 (here, the axial stiffness and the axial viscous damping coefficient) affect the vibration of the mechanical device 51 in the primary and secondary vibration modes. Thus, according to the present invention, the stability of mechanical elements of a mechanical device having two or more vibration modes can be easily determined not only after the mechanical device is manufactured but also during the design of the mechanical device.

[0100] Figure 14 (A) and (B) are respectively Figure 10 An example of a stability discrimination diagram regarding the primary vibration mode and the secondary vibration mode of the coupling 58 , which is one of the mechanical elements of the second mechanical device 51 , is shown. Figure 15 (A) and (B) are graphs showing speed changes when target products (a first coupling and a second coupling) representing the coupling 58 of the second mechanical device 51 are used, respectively. Figure 16 yes Figure 14 (A) and (B) are modified graphs of the stability discriminant diagram shown.

[0101] exist Figure 14 In the stability discrimination diagrams shown in (A) and (B) of FIG. , the stiffness and damping characteristics of the coupling 58 are used as parameters and are indicated along the horizontal axis and the vertical axis, respectively. Figure 12 The cases of (A) and (B) are similar, showing the stability discrimination diagrams of the primary vibration mode and the secondary vibration mode.

[0102] As described above, according to the design assistance apparatus 1 and the design assistance method associated therewith, it is possible to freely select the analysis target and the vibration mode when creating the stability discriminant diagram. Figure 7 Similar situation, such as Figure 14 As shown in (A) and (B), in the stable region where the real part of the transfer function is negative, the possibility of abnormal vibration occurring in the mechanical device 5 is low. On the other hand, in the unstable region where the real part is positive, the possibility of abnormal vibration occurring in the mechanical device 51 is high.

[0103] like Figure 14 As shown in (A), in the mechanical device 51, it can be seen that changing the characteristics of the coupling 58 has almost no effect on the stability in the primary vibration mode. Figure 14 As shown in FIG. 5B , in the secondary vibration mode, it can be seen that the torsional stiffness and viscous damping characteristics of the coupling 58 affect the stability of the mechanical device 51 .

[0104] Figure 15(A) and (B) show responses of the mechanical device 51 when the speed command of the servo motor 57 is changed in a stepwise manner in the case where the first coupling and the second coupling are used, respectively.

[0105] Here, the values ​​of the axial stiffness and axial viscous damping coefficient of the first support bearing are Figure 14 (A) and (B) are indicated by triangle marks (Δ), and for Figure 14 The primary vibration mode shown in (A) is in the stable region, but for Figure 14 The secondary vibration mode shown in (B) is located in the unstable region. Figure 14 In (A) and (B), the axial stiffness of the second coupling and the values ​​of the axial viscous damping coefficient are indicated by circle marks (○), and for Figure 14 The primary vibration mode shown in (A) and Figure 14 In both secondary vibration modes shown in (B), the mechanical device 51 is in the stable region.

[0106] exist Figure 15 In the first coupling shown in (A), the vibration is Figure 15 The higher frequency occurs in the second support bearing shown in (B). This corresponds to the fact that the values ​​of the axial stiffness and axial viscous damping coefficient of the first coupling are located in the unstable region of the stability discriminant diagram of the secondary vibration mode. On the other hand, in Figure 15 In the second coupling shown in (B), it can be seen that the response is not oscillatory and the second mechanical device 51 can be used in a normal manner.

[0107] Based on the analysis results of the feed drive mechanism of the mechanical device 51, the overall performance of the feed drive mechanism can be improved by designing the characteristics of the support bearing 56 so that it lies within the stable region of the stability discriminant diagram for the primary vibration mode, and then within the stable region of the stability discriminant diagram for the secondary vibration mode. Furthermore, if the stiffness of the support bearing 56 is selected to lie between the values ​​of the first support bearing and the second support bearing, these values ​​can lie within the stable region of the stability discriminant diagram for both the primary and secondary vibration modes. It is well known that the axial stiffness of the support bearing can be adjusted by varying the bearing preload.

[0108] Thus, by using the design support apparatus 1 and the design support method associated therewith, the user can easily grasp the influence of multiple analysis target elements on the vibration of the mechanical device 51. Furthermore, the user can know the stiffness and damping characteristics of the mechanical elements that are optimal for improving the performance of the mechanical device 51, and can design the mechanical elements (including the selection of the mechanical elements) so as to improve the performance of the mechanical device.

[0109] The stability discriminant diagram is Figure 12and Figure 14 Although the stability discriminant diagram is created based on the characteristics of each individual mechanical element (support bearing 56, coupling 58), a stability discriminant diagram may also be created based on the characteristics of multiple mechanical elements (for example, by indicating the stiffness of support bearing 56 along the horizontal axis and the stiffness of coupling 58 along the vertical axis). Furthermore, at least one of the horizontal and vertical axes of the stability discriminant diagram may indicate the servo gain of the control system of servo motor 57, the lead of ball screw 52, ​​or the moment of inertia and mass of the mechanical element.

[0110] exist Figure 12 In the examples of (A) and (B), a stability discrimination map is created for each of a plurality of vibration modes, but a single stability discrimination map may also be created, which includes a plurality of stability discrimination maps corresponding to the respective vibration modes, and these stability discrimination maps are superimposed one on another to be displayed on the display unit 7.

[0111] For example, Figure 16 The stability discriminant diagram shown contains Figure 12 The contour lines related to the primary and secondary vibration modes shown in (A) and (B) of FIG. 3 are shown, and the stable region is defined by considering the two vibration modes (see Figure 16 ) and unstable areas. Thus, by using a stability discriminant diagram based on multiple vibration modes, the user can more reliably grasp the influence of the characteristics of the support bearing 56 on the occurrence of abnormal vibration of the mechanical device. In the design assistance device 1 and the design assistance method associated therewith, a single stability discriminant diagram can also be created in which stability discriminant diagrams created for each of three or more vibration modes are superimposed on each other.

[0112] Figure 17 1 is a diagram showing an example of a GUI screen 60 created by executing design assistance software on the design assistance apparatus 1 , regarding design assistance of the second mechanical device 51 .

[0113] like Figure 17As shown, the GUI screen 60 includes an analysis parameter setting bar 61, which allows the user to manually input the range of the parameters of the analysis target element determined by the analysis parameter setting unit 3 (here, the axial stiffness and axial viscous damping coefficient of the support bearing 56). The user can appropriately change the analysis target element in the analysis parameter setting bar 61. The GUI screen 60 also includes a fixed parameter setting bar 62, which allows the user to manually input parameters of mechanical elements other than the analysis target element set by the fixed parameter setting unit 4, such as the velocity loop proportional gain Kvp, the velocity loop integral gain Kvi, the axial stiffness, torsional stiffness and viscous damping coefficient of the coupling 58, the axial stiffness and viscous damping coefficient of the bearing, and the axial stiffness and viscous friction coefficient of the nut 53. The GUI screen 60 also includes a vibration mode setting bar 64, which allows the user to perform an input operation regarding the vibration mode of the analysis target element set by the vibration mode setting unit 5. In this case, a secondary vibration mode is input (selected) in the vibration mode setting bar 64, but the user can also input a primary vibration mode or multiple vibration modes ( Figure 16 The analysis result output column 63 includes Figure 12 (B) The corresponding stability discriminant diagram 71 and the associated three-dimensional diagram 72 are displayed. By checking "Rotate Open" on the GUI screen, the three-dimensional diagram can be displayed from any viewpoint. The "Rotate Open" display can be omitted to allow for continuous rotation, or the viewpoint can be fixed. In the analysis result output section 63, a root locus diagram 75 created using a known method based on the parameters of the support bearing 56 can also be displayed.

[0114] The present invention can be applied not only to cases where the mechanical device has only one vibration mode, but also to cases where the mechanical device has two or more vibration modes. This has a greater advantage because the parameters of the mechanical elements can be selected so that stable operation can be ensured in each vibration mode. The present invention not only provides a measure for abnormal vibration discovered after the mechanical device is manufactured, but also allows the various parameters of the mechanical elements to be appropriately set before the mechanical device is actually manufactured.

[0115] The present invention has been described with reference to specific embodiments, but the present invention is not limited to these embodiments and can be modified in various ways without departing from the scope of the invention. For example, the design assistance device and the design assistance method according to the present invention are not limited to the above examples in their applications, and can be applied, for example, to drive mechanisms of various other mechanical devices such as semiconductor manufacturing devices, power steering devices, lift devices (control surface devices) of aircraft, and industrial robots. The various elements of the design assistance device, design assistance method, and design assistance program according to the present invention described above based on the specific embodiments are not completely necessary for the present invention, but can be appropriately omitted and replaced without departing from the scope of the invention.

[0116] Glossary

[0117] 1: Design auxiliary equipment

[0118] 2: Transfer function calculation unit

[0119] 3: Analysis parameter setting unit

[0120] 4: Fixed parameter setting unit

[0121] 5: Vibration mode setting unit

[0122] 6: Stability discriminant diagram creation unit

[0123] 7: Display unit

[0124] 11: Processor

[0125] 15: Input / output bus

[0126] 16: Input device

[0127] 17: Display device

[0128] 18: External storage device

[0129] 21: First Mechanical Device

[0130] 22: Roller

[0131] 23: Electric motor

[0132] 24: Coupling

[0133] 30, 60: GUI screen

[0134] 31, 61: Analysis parameter setting bar

[0135] 32, 62: Fixed parameter setting bar

[0136] 33, 63: Analysis result output column

[0137] 41, 71: Stability discriminant diagram

[0138] 42, 72: Three-dimensional graph

[0139] 45, 75: Root locus diagram

[0140] 51: Second mechanical device

[0141] 52: Ball screw

[0142] 53: Nut

[0143] 54: Taiwan

[0144] 55: Screw shaft

[0145] 56: Support bearing

[0146] 57: Servo motor

[0147] 58: Coupling

Claims

1. A design aid device provided with a processor, the processor being configured to execute processing for assisting design of a mechanical device driven by a feedback-controlled electric motor, the design aid device comprising a display unit for displaying a graphical user interface screen, in, The processor is configured to set a plurality of parameters of a mathematical model of an analysis target element selected from one or more mechanical elements forming the mechanical device, calculate poles of a transfer function of the mechanical device associated with one or more vibration modes of the mechanical device based on the plurality of parameters, and create a stability discriminant diagram including contour lines of real parts of the poles of the transfer function, the stability discriminant diagram including marks indicating the plurality of parameters of a plurality of target products that can be candidates for the mechanical element, and The graphical user interface screen includes: an analysis parameter setting bar, which enables a user's input operation, and the input operation is used to select a range of each parameter of the multiple parameters of the analysis target element set by the processor; a vibration mode setting bar, which allows the user to perform an input operation regarding the vibration mode of the analysis target element; and an analysis result output bar, which displays the stability judgment diagram, and the mark is displayed on the graphical user interface screen in a manner that enables the user to compare the parameters of each target product, so that the user can appropriately select the target product to suppress the vibration of the mechanical device.

2. The design aid device according to claim 1, wherein When the mechanical device has a plurality of vibration modes, the stability discrimination map created by the processor includes a plurality of stability discrimination maps corresponding to the respective vibration modes, and the plurality of stability discrimination maps are superimposed one on another to be displayed on the display unit.

3. The design aid device according to claim 1 or 2, wherein: The plurality of parameters include parameters related to stiffness and damping characteristics of the mechanical element.

4. A design assistance method performed by a design assistance device, the design assistance method being used to assist in the design of a mechanical device driven by a feedback-controlled electric motor, comprising the following steps: setting a plurality of parameters of a mathematical model of an analysis target element selected from one or more mechanical elements forming the mechanical device; calculating poles of a transfer function of the mechanical device associated with one or more vibration modes of the mechanical device based on the plurality of parameters; as well as creating a stability discriminant diagram including contour lines of the real part of the extreme points of the transfer function, the stability discriminant diagram including marks indicating the plurality of parameters of a plurality of target products that can be candidates for the mechanical element, The design auxiliary device includes a display unit for displaying a graphical user interface screen. The design assistance method further comprises the following steps: when the plurality of parameters are set, displaying a graphical user interface screen on the display unit, and The graphical user interface screen includes: an analysis parameter setting bar, which enables a user's input operation, and the input operation is used to select a range for each parameter of the multiple parameters of the analysis target element; a vibration mode setting bar, which allows the user to perform an input operation regarding the vibration mode of the analysis target element; and an analysis result output bar, which displays the stability judgment diagram, and the mark is displayed on the graphical user interface screen in a manner that enables the user to compare the parameters of each target product, so that the user can appropriately select the target product to suppress the vibration of the mechanical device.

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