Cam Curve Generation Device, Cam Curve Generation Method, and Program

Abstract

Generate a cam curve that smoothly connects to the off-interval cam curve and suppresses fluctuations in the speed and acceleration of the follower shaft. The cam curve generation device (100) includes: an interval division unit (60) that divides the application interval into a plurality of sub-intervals in a manner that satisfies the division conditions; and a cam curve generation unit (70) that generates a cam curve for the application interval in a manner that satisfies the boundary conditions. Each of the plurality of sub-intervals is a sub-interval in which the acceleration of the follower shaft monotonically increases, a sub-interval in which the acceleration of the follower shaft monotonically decreases, or a sub-interval in which the acceleration of the follower shaft is constant. The division conditions include the length and the category related to each of the plurality of sub-intervals. The boundary conditions include the position, speed, and acceleration of the follower shaft at the start end of the application interval, and the position, speed, and acceleration of the follower shaft at the end end of the application interval. The cam curve generation unit (70) generates a cam curve in such a way that the position, speed, and acceleration of the follower shaft are continuous at each boundary of the plurality of sub-intervals.

Description

Technical Field

[0001] The present disclosure relates to a cam curve generation device that generates a cam curve for implementing electronic cam control for synchronously controlling the position of a follower shaft with the position of a main shaft. Background Art

[0002] Conventionally, there has been known a technique in which when boundary conditions at the start of an interval and boundary conditions at the end of the interval are given, a cam curve that is smoothly connected to an out-of-interval cam curve outside the interval is generated (for example, refer to Patent Document 1). Here, the out-of-interval cam curve being smoothly connected to the generated cam curve means that the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft in the out-of-interval cam curve are continuous with the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft in the generated cam curve at the connection point. Further, here, a certain physical quantity in the out-of-interval cam curve being continuous with a certain physical quantity in the generated cam curve at the connection point means that the physical quantity is the same at the connection point.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2006-172438 Summary of the Invention

[0006] According to the above-described conventional technique for generating a cam curve, the cam curve corresponding to the boundary conditions at the start of the interval and the boundary conditions at the end of the interval is uniquely determined. Therefore, depending on the boundary conditions at the start of the interval and the boundary conditions at the end of the interval, a cam curve in which the speed or the acceleration of the follower shaft within the application interval varies relatively greatly is generated.

[0007] Therefore, an object of the present disclosure is to provide a cam curve generation device, a cam curve generation method, and a program for causing a cam curve generation device to execute a cam curve generation process that can generate a cam curve that is smoothly connected to an out-of-interval cam curve and suppresses variations in the speed and acceleration of the follower shaft within the application interval.

[0008] A cam curve generation device according to an aspect of the present disclosure is an electronic cam control cam curve generation device that controls the position of a follower shaft. The cam curve generation device includes a boundary condition acquisition unit, a division condition acquisition unit, an interval division unit, and a cam curve generation unit. The boundary condition acquisition unit acquires boundary conditions of an application interval that is an object of generating the cam curve within a range of the main shaft position transition. The division condition acquisition unit acquires division conditions for dividing the application interval into a plurality of sub-intervals. The interval division unit divides the application interval into the plurality of sub-intervals in a manner that satisfies the division conditions. The cam curve generation unit generates a cam curve of the application interval in a manner that satisfies the boundary conditions. Each of the plurality of sub-intervals is a sub-interval in which the acceleration of the follower shaft monotonically increases, a sub-interval in which the acceleration of the follower shaft monotonically decreases, or a sub-interval in which the acceleration of the follower shaft is constant. The division conditions include the lengths and categories of the plurality of sub-intervals. The boundary conditions include the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the start end of the application interval, and the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the end end of the application interval. The cam curve generation unit also generates the cam curve in such a manner that the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft are continuous at each boundary of the plurality of sub-intervals.

[0009] Another aspect of the present disclosure relates to a cam curve generation method for generating a cam curve for electronic cam control for achieving control of the position of a follower shaft. The cam curve generation method includes a first step, a second step, a third step, and a fourth step. In the first step, boundary conditions of an application interval that is an object of generating the cam curve are obtained within a range of the main shaft position migration. In the second step, a division condition for dividing the application interval into a plurality of sub-intervals is obtained. In the third step, the application interval is divided into the plurality of sub-intervals in a manner that satisfies the division condition. In the fourth step, the cam curve of the application interval is generated in a manner that satisfies the boundary conditions. Each of the plurality of sub-intervals is a sub-interval in any one of a category where the acceleration of the follower shaft monotonically increases, a category where the acceleration of the follower shaft monotonically decreases, and a category where the acceleration of the follower shaft remains unchanged. The division condition includes the lengths and categories of the plurality of sub-intervals. The boundary conditions include the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the start end of the application interval, and the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the end of the application interval. In the fourth step, the cam curve is also generated in a manner that makes the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft continuous at each boundary of the plurality of sub-intervals.

[0010] Another program according to an aspect of the present disclosure is a program for causing a cam curve generation device to execute a cam curve generation process for generating a cam curve for implementing electronic cam control for controlling the position of a follower shaft. This program includes a first step, a second step, a third step, and a fourth step. In the first step, the cam curve generation process acquires boundary conditions of an application section that is an object of generating the cam curve within a range of spindle position migration. In the second step, division conditions for dividing the application section into a plurality of sub-sections are acquired. In the third step, the application section is divided into the plurality of sub-sections in a manner that satisfies the division conditions. In the fourth step, the cam curve of the application section is generated in a manner that satisfies the boundary conditions. Each of the plurality of sub-sections is a sub-section in any one of a category where the acceleration of the follower shaft monotonically increases, a category where the acceleration of the follower shaft monotonically decreases, and a category where the acceleration of the follower shaft is constant. The division conditions include the lengths and categories of the plurality of sub-sections. The boundary conditions include the position, speed, and acceleration of the follower shaft at the start end of the application section, and the position, speed, and acceleration of the follower shaft at the end of the application section. In the fourth step, the cam curve is generated such that the position, speed, and acceleration of the follower shaft are continuous at each boundary of the plurality of sub-sections.

[0011] According to the cam curve generation device, cam curve generation device, and program according to the present disclosure, it is possible to generate a cam curve that is smoothly connected to an out-of-range cam curve and suppresses fluctuations in the speed and acceleration of the follower shaft within the application section. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a block diagram showing an example of the configuration of a cam curve generation system according to Embodiment 1.

[0013] Figure 2 is a flowchart of a first cam curve generation process according to Embodiment 1.

[0014] Figure 3 is a waveform diagram showing an example of a cam curve according to Embodiment 1.

[0015] Figure 4 is a waveform diagram showing another example of a cam curve according to Embodiment 1.

[0016] Figure 5 is a block diagram showing an example of the configuration of a cam curve generation system according to Embodiment 2.

[0017] Figure 6 This is a flowchart of the second cam curve generation process according to Embodiment 2. Detailed implementation

[0018] (Process of obtaining one mode of the present disclosure)

[0019] In an industrial equipment such as a pillow packaging machine that wraps a product with a film by continuously feeding the film while sealing and cutting the film into a specified size, there is industrial equipment that repeatedly and continuously performs a series of processing steps. In such industrial equipment, multiple axes for performing a series of processing steps are provided, and the required operations are performed while synchronizing these multiple axes with each other.

[0020] As a method of synchronizing multiple axes with each other, the following methods are known: a cyclic motion is imparted to other driven axes via a cam mechanism mechanically mounted on a drive shaft as a main shaft; and for each driven shaft, a servo motor is used to cyclically drive each driven shaft in a pattern of a position signal related to other shafts. As an example of the latter, there is a method of controlling a driven shaft based on electronic cam control.

[0021] The method of controlling a driven shaft based on electronic cam control is a control method that outputs a position command for the driven shaft to the servo motor based on a cam curve that defines the relationship between the position of the main shaft and the position of the driven shaft. The method of controlling a driven shaft based on electronic cam control has advantages such as easy change of the operation mode and simplification of the mechanism compared to the method of controlling a driven shaft using a mechanical cam mechanism.

[0022] The cam curve is generated corresponding to the operation mode required by the industrial equipment. As a method of generating a cam curve, the following method is known: the operation mode is divided into multiple intervals, a cam curve is generated for each interval, and the cam curves of the multiple intervals are connected to generate one cam curve.

[0023] For example, in the case where the driven shaft is the sealer shaft of a pillow packaging machine, the following method is known: at least two intervals are divided, namely, an interval from the start position to the end position of one sealing (hereinafter also referred to as the "sealing interval") and an interval from the end position of one sealing to the start position of the next sealing (hereinafter also referred to as the "relay interval"), to generate a cam curve.

[0024] In the sealing interval, since it is necessary to bring the sealing surface of the sealer into contact with a specified sealing portion of the film, the moving speed of the sealer is uniquely determined relative to the conveying speed of the film. Therefore, the cam curve of the sealer shaft in the sealing interval is uniquely determined.

[0025] On the other hand, in the relay section, since the sealing surface of the capper moves away from the film, the moving speed of the capper can be non-uniquely determined relative to the conveying speed of the film. Therefore, the cam curve of the axis of the capper in the relay section is non-uniquely determined.

[0026] In addition, when the operation mode is divided into multiple sections and a cam curve is generated for each section, the speed of the follower shaft obtained by differentiating the cam curve with respect to the position of the main shaft by the first order and the acceleration of the follower shaft obtained by differentiating the cam curve with respect to the position of the main shaft by the second order may become discontinuous at the boundary between two adjacent sections.

[0027] When such a discontinuity exists, near its boundary, the speed, acceleration, etc. of the follower shaft change sharply. The sharp change in the speed and acceleration of the follower shaft causes a relatively large acceleration, torque, jerk, etc. of the follower shaft, which becomes a cause of vibration or shock to the industrial equipment.

[0028] In order to prevent such vibration or shock to the industrial equipment, for example, in a section where the cam curve is non-uniquely determined, such as the relay section in the above-mentioned pillow packaging machine, a cam curve needs to be generated in a manner that smoothly connects with the cam curve of the adjacent section where the cam curve is uniquely determined. As a technique for generating such a cam curve, for example, the prior art described in Patent Document 1 is known.

[0029] This prior art generates a cam curve that smoothly connects with the cam curve outside the section at the boundary with the adjacent section by using a cam curve that defines the position of the follower shaft relative to the position of the main shaft with a fifth-degree function, defines the speed of the follower shaft relative to the position of the main shaft with a fourth-degree function, and defines the acceleration of the follower shaft relative to the position of the main shaft with a third-degree function.

[0030] However, in the above prior art, when the boundary conditions at the start and end of the section are given, the shape of the cam curve is uniquely determined according to the boundary conditions. Therefore, according to the boundary conditions at the start and end of the section, the speed of the follower shaft or the acceleration of the follower shaft within the section sometimes changes significantly.

[0031] If the change in the speed or acceleration of the follower shaft becomes larger, the vibration or shock to the industrial equipment becomes larger. In addition, since a motor for generating a larger speed and torque is required, it leads to high cost, large size, and heavy weight of the industrial equipment, etc.

[0032] Therefore, the inventors have dedicatedly and repeatedly conducted experiments and research on a cam curve generation device that can generate a cam curve that smoothly connects to the out-of-range cam curve and suppresses fluctuations in the speed and acceleration of the follower shaft within the application range.

[0033] As a result, the inventors have conceived of the following cam curve generation device and the like, and a cam curve generation method.

[0034] The cam curve generation device according to one aspect of the present disclosure generates a cam curve for electronic cam control that controls the position of a follower shaft. The cam curve generation device includes a boundary condition acquisition unit, a division condition acquisition unit, an interval division unit, and a cam curve generation unit. The boundary condition acquisition unit acquires boundary conditions of an application range that is the object of generating the cam curve within the range of the main shaft position transition. The division condition acquisition unit divides the application range into a plurality of sub-ranges. The interval division unit divides the application range into the plurality of sub-ranges in a manner that satisfies the division conditions. The cam curve generation unit generates the cam curve of the application range in a manner that satisfies the boundary conditions. Each of the plurality of sub-ranges is a sub-range in which the acceleration of the follower shaft monotonically increases, a sub-range in which the acceleration of the follower shaft monotonically decreases, or a sub-range in which the acceleration of the follower shaft is constant. The division conditions include the lengths of the plurality of sub-ranges and the categories. The boundary conditions include the position, speed, and acceleration of the follower shaft at the start end of the application range, and the position, speed, and acceleration of the follower shaft at the end end of the application range. The cam curve generation unit generates the cam curve in such a manner that the position, speed, and acceleration of the follower shaft are continuous at each boundary of the plurality of sub-ranges.

[0035] According to the cam curve generation device having the above structure, the position, speed, and acceleration of the follower shaft at the start end of the application range, and the position, speed, and acceleration of the follower shaft at the end end of the application range are determined based on the acquired boundary conditions. Therefore, according to the cam curve generation device having the above structure, by setting the acquired boundary conditions to appropriate conditions, a cam curve that smoothly connects to the out-of-range cam curve outside the application range can be generated.

[0036] In addition, according to the cam curve generation device having the above structure, the speed and acceleration of the follower shaft within the application range are determined based on the acquired division conditions. Therefore, according to the cam curve generation device having the above structure, by setting the acquired division conditions to appropriate conditions, a cam curve that suppresses fluctuations in the speed and acceleration of the follower shaft within the application range can be generated.

[0037] Therefore, the cam curve generation device according to the above structure can generate a cam curve that smoothly connects with the outer interval cam curve and suppresses the variations in the speed of the follower shaft and the acceleration of the follower shaft within the application interval.

[0038] In addition, it can be set that in at least one of the sub-intervals where the acceleration of the follower shaft is monotonically increasing and the sub-intervals where the acceleration of the follower shaft is monotonically decreasing, the cam curve generation unit generates the cam curve in such a way that the waveform of the acceleration of the follower shaft from the start end to the end end of the sub-interval is in the shape of a quarter-period portion up to the peak of a sine wave.

[0039] In addition, it can be set that in at least one of the sub-intervals where the acceleration of the follower shaft is monotonically increasing and the sub-intervals where the acceleration of the follower shaft is monotonically decreasing, the cam curve generation unit generates the cam curve in such a way that the waveform of the acceleration of the follower shaft from the start end to the end end of the sub-interval is in the shape of a half-period portion starting from the peak of a sine wave.

[0040] In addition, it can be set that in at least one of the sub-intervals where the acceleration of the follower shaft is monotonically increasing and the sub-intervals where the acceleration of the follower shaft is monotonically decreasing, the cam curve generation unit generates the cam curve in such a way that the waveform of the acceleration of the follower shaft from the start end to the end end of the sub-interval is in the shape of a quarter-period portion starting from the peak of a sine wave.

[0041] In addition, it can be set that in at least one of the sub-intervals where the acceleration of the follower shaft is monotonically increasing and the sub-intervals where the acceleration of the follower shaft is monotonically decreasing, the cam curve generation unit generates the cam curve in such a way that the waveform of the acceleration of the follower shaft from the start end to the end end of the sub-interval is a waveform defined by a first-degree polynomial passing through the main shaft position.

[0042] In addition, it can be set that the plurality of sub-intervals are five sub-intervals, namely, a first sub-interval, a second sub-interval, a third sub-interval, a fourth sub-interval, and a fifth sub-interval that are sequentially continuous. It can also be set that the first sub-interval, the third sub-interval, and the fifth sub-interval are sub-intervals of the category where the acceleration of the follower shaft is monotonically increasing or monotonically decreasing, and the second sub-interval and the fourth sub-interval are sub-intervals of the category where the acceleration of the follower shaft is constant.

[0043] In addition, it can be set that the acceleration of the follower shaft in the second sub-interval and the fourth sub-interval is a value other than 0.

[0044] Alternatively, it can be set that the multiple sub-intervals are seven sub-intervals, namely, a first sub-interval, a second sub-interval, a third sub-interval, a fourth sub-interval, a fifth sub-interval, a sixth sub-interval, and a seventh sub-interval, which are consecutive in order. It can be set that the first sub-interval, the third sub-interval, the fifth sub-interval, and the seventh sub-interval are sub-intervals in categories where the acceleration of the driven shaft monotonically increases or decreases. It can also be set that the second sub-interval, the fourth sub-interval, and the sixth sub-interval are sub-intervals in categories where the acceleration of the driven shaft remains unchanged.

[0045] Alternatively, it can be set that the acceleration of the driven shaft in the second sub-interval and the sixth sub-interval is a value other than 0, and the acceleration of the driven shaft in the fourth sub-interval is 0.

[0046] Alternatively, it can be set that an interval setting unit is further provided, and the interval setting unit divides the range of the main shaft position migration into the application interval and a non-application interval outside the application interval.

[0047] Alternatively, it may be configured to further include an existing cam curve storage unit and a boundary condition calculation unit. The existing cam curve storage unit stores pre-generated existing cam curves. The boundary condition calculation unit calculates the following values. That is, based on the existing cam curve, it calculates the first follower shaft position of the follower shaft at the first main shaft position, the first follower shaft speed of the follower shaft at the first main shaft position, the first follower shaft acceleration of the follower shaft at the first main shaft position, the second follower shaft position of the follower shaft at a second main shaft position that is later in time than the first main shaft position, the second follower shaft speed of the follower shaft at the second main shaft position, and the second follower shaft acceleration of the follower shaft at the second main shaft position. Additionally, a first interval from the first main shaft position to the second main shaft position within the range of the main shaft position migration in the existing cam curve is set as the application interval, and the following boundary conditions are calculated. That is, the boundary conditions are set such that the first follower shaft position, the first follower shaft speed, and the first follower shaft acceleration are the position of the follower shaft at the start end, the speed of the follower shaft at the start end, and the acceleration of the follower shaft at the start end. Additionally, the boundary conditions are set such that the second follower shaft position, the second follower shaft speed, and the second follower shaft acceleration are the position of the follower shaft at the end, the speed of the follower shaft at the end, and the acceleration of the follower shaft at the end. The boundary condition acquisition unit acquires the boundary conditions related to the start end and the boundary conditions related to the start and end calculated by the boundary condition calculation unit. The segmentation condition acquisition unit acquires the segmentation conditions with the first interval set as the application interval. The interval segmentation unit sets the first interval as the application interval and divides the application interval into the plurality of sub-intervals. Alternatively, the cam curve generation unit may generate the cam curve with the first interval set as the application interval.

[0048] Another aspect of the present disclosure relates to a cam curve generation method for generating a cam curve for implementing electronic cam control to control the position of a follower shaft. The cam curve generation method includes a first step, a second step, a third step, and a fourth step. In the first step, boundary conditions of an application range, which is an object of generating the cam curve, within the range of the main shaft position migration are obtained. In the second step, division conditions for dividing the application range into a plurality of sub-ranges are obtained. In the third step, the application range is divided into the plurality of sub-ranges in a manner that satisfies the division conditions. In the fourth step, the cam curve of the application range is generated in a manner that satisfies the boundary conditions. Each of the plurality of sub-ranges is a sub-range in any one of a category where the acceleration of the follower shaft monotonically increases, a category where the acceleration of the follower shaft monotonically decreases, and a category where the acceleration of the follower shaft remains unchanged. The division conditions include the lengths of the plurality of sub-ranges and the categories. The boundary conditions include the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the start end of the application range, and the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the end of the application range. In the fourth step, the cam curve is also generated in a manner that makes the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft continuous at each boundary of the plurality of sub-ranges.

[0049] According to the above cam curve generation method, the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the start end of the application range, and the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the end of the application range are determined based on the obtained boundary conditions. Therefore, according to the above cam curve generation method, by setting the obtained boundary conditions to appropriate conditions, a cam curve that is smoothly connected to the out-of-range cam curve outside the application range can be generated.

[0050] In addition, according to the above cam curve generation method, the speed of the follower shaft and the acceleration of the follower shaft within the application range are determined based on the obtained division conditions. Therefore, according to the above cam curve generation method, by setting the obtained division conditions to appropriate conditions, a cam curve that suppresses the variation of the speed of the follower shaft and the acceleration of the follower shaft within the application range can be generated.

[0051] Thus, according to the above cam curve generation method, a cam curve that is smoothly connected to the out-of-range cam curve and suppresses the variation of the speed of the follower shaft and the acceleration of the follower shaft within the application range can be generated.

[0052] Another program according to an aspect of the present disclosure is a program for causing a cam curve generation device to perform a cam curve generation process for generating a cam curve for implementing electronic cam control for controlling the position of a follower shaft. This program includes a first step, a second step, a third step, and a fourth step. In the first step, the cam curve generation process acquires boundary conditions of an application section, which is a section within the range of the main shaft position transition and is an object for generating a cam curve. In the second step, division conditions for dividing the application section into a plurality of subsections are acquired. In the third step, the application section is divided into a plurality of subsections in a manner that satisfies the division conditions. In the fourth step, a cam curve of the application section is generated in a manner that satisfies the boundary conditions. Each of the plurality of subsections is either a subsection in which the acceleration of the follower shaft monotonically increases or decreases or a subsection in which the acceleration of the follower shaft remains constant. The division conditions include the length and category related to each of the plurality of subsections. The boundary conditions include the position, velocity, and acceleration of the follower shaft at the start end of the application section, and the position, velocity, and acceleration of the follower shaft at the end of the application section. In the fourth step, the cam curve is also generated in a manner that makes the position, velocity, and acceleration of the follower shaft continuous at each boundary of the plurality of subsections.

[0053] According to the above program, based on the acquired boundary conditions, the position, velocity, and acceleration of the follower shaft at the start end of the application section, and the position, velocity, and acceleration of the follower shaft at the end of the application section are determined. Therefore, according to the above program, by setting the acquired boundary conditions as appropriate conditions, a cam curve that is smoothly connected to the out-of-section cam curve outside the application section can be generated.

[0054] In addition, according to the above program, based on the acquired division conditions, the velocity and acceleration of the follower shaft within the application section are determined. Therefore, according to the above program, by setting the acquired division conditions as appropriate conditions, a cam curve that suppresses fluctuations in the velocity and acceleration of the follower shaft within the application section can be generated.

[0055] Thus, according to the above program, a cam curve that is smoothly connected to the out-of-section cam curve and suppresses fluctuations in the velocity and acceleration of the follower shaft within the application section can be generated.

[0056] Next, a specific example of a cam curve generation device and a cam curve generation method according to the embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments shown here are all specific examples of the present disclosure. Therefore, the numerical values, shapes, constituent elements, arrangements and connection manners of the constituent elements, and steps (processes) and the order of the steps shown in the following embodiments are examples and are not intended to limit the present disclosure. In addition, the drawings are schematic diagrams and are not strictly illustrated.

[0057] Furthermore, the general or specific embodiments of the present disclosure can be implemented by a system, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or can also be implemented by any combination of a system, a method, an integrated circuit, a computer program, and a recording medium.

[0058] (Embodiment 1)

[0059] Here, an electronic cam control system for performing electronic cam control to synchronize the position of a follower shaft with the position of a main shaft will be described with reference to the accompanying drawings.

[0060] <Structure>

[0061] Figure 1 FIG. is a block diagram showing an example of the structure of a cam curve generation system 1 according to Embodiment 1.

[0062] As Figure 1 shown, the cam curve generation system 1 includes a cam curve generation device 100, a servo control device 200, and a motor 300.

[0063] The cam curve generation device 100 generates a cam curve that defines the relationship between the position of the main shaft and the position of the follower shaft for implementing electronic cam control to synchronize the position of the follower shaft with the position of the main shaft.

[0064] The cam curve can be, for example, a function that defines the relationship between the position of the main shaft and the position of the follower shaft, or a data table.

[0065] The cam curve can also define, for example, the relationship between the position of the main shaft and the speed of the follower shaft, the relationship between the position of the main shaft and the acceleration of the follower shaft, or the relationship between the position of the main shaft and the jerk of the follower shaft. That is, the cam curve can include a function that also defines the relationship between the position of the main shaft and the speed of the follower shaft, the relationship between the position of the main shaft and the acceleration of the follower shaft, or the relationship between the position of the main shaft and the jerk of the follower shaft, and can also include a data table that also defines the relationship between the position of the main shaft and the speed of the follower shaft, the relationship between the position of the main shaft and the acceleration of the follower shaft, or the relationship between the position of the main shaft and the jerk of the follower shaft.

[0066] In addition, the cam curve generation device 100 generates an instruction for the follower shaft based on the generated cam curve and the main shaft position indicating the position of the main shaft, and outputs the instruction. The instruction can be, for example, a position instruction, a speed instruction, or a torque instruction.

[0067] Here, the main shaft position is a position signal that serves as a synchronization reference for the cam curve generation system 1. The main shaft position can be, for example, a position instruction for the main shaft, a signal indicating the position of the main shaft obtained by an external device such as a pulser or an encoder, or a signal indicating the position of a shaft other than the main shaft that operates synchronously with the main shaft or the position of a movable part of an industrial device such as a belt conveyor. When the main shaft position is a position instruction for the main shaft, the cam curve generation device 100 can also generate the position instruction. And the main shaft does not necessarily have to be an actual shaft and can also be a virtual shaft.

[0068] The motor 300 drives the follower shaft.

[0069] The servo control device 200 controls the motor 300 based on the instruction for the follower shaft output from the cam curve generation device 100.

[0070] As Figure 1 shown, the cam curve generation device 100 includes an input reception unit 10, an interval information acquisition unit 20, a division condition acquisition unit 30, a boundary condition acquisition unit 40, an interval setting unit 50, an interval division unit 60, a cam curve generation unit 70, a cam curve storage unit 80, and a follower shaft instruction generation unit 90.

[0071] The cam curve generation device 100 can also be implemented, for example, by a computer having a processor and a memory. In this case, each component constituting the cam curve generation device 100 can also be implemented by the processor executing a program stored in the memory.

[0072] The input reception unit 10 is configured to receive the input of cam curve generation conditions.

[0073] The cam curve generation conditions include interval information of an application interval that is an object for generating a cam curve within the range of the position transition of the main shaft, boundary conditions of the application interval, and division conditions for dividing the application interval into a plurality of sub-intervals.

[0074] The interval information acquisition unit 20 acquires interval information according to the cam curve generation conditions accepted by the input acceptance unit 10. Here, it is assumed that the interval information is included in the cam curve generation conditions for explanation, but the interval information can also be predetermined, for example. In this case, the interval information acquisition unit 20 can also store the predetermined interval information instead of acquiring the interval information according to the cam curve generation conditions accepted by the input acceptance unit 10.

[0075] Regarding the interval information, as an example where it is not necessarily necessary to limit the interval information, for example, the interval information is represented by the coordinate values in the xy orthogonal coordinate system with the position of the main shaft as the x-axis (horizontal axis) and the position of the driven shaft as the y-axis (vertical axis). The coordinate values can be, for example, only the position of the main shaft, or the position of the main shaft and the position of the driven shaft. Here, it is assumed that the coordinate values are the position of the main shaft and the position of the driven shaft for explanation.

[0076] The interval setting unit 50 divides the range of the position migration of the main shaft into an application interval and a non-application interval outside the application interval based on the interval information acquired by the interval information acquisition unit 20. Thereby, the interval setting unit 50 sets the application interval and the non-application interval.

[0077] Regarding the application interval, for example, in the case where the driven shaft is the sealing end shaft of a pillow packaging machine, the interval that can not uniquely determine the cam curve, such as the relay interval, conforms to the application interval. Regarding the non-application interval, for example, in the case where the driven shaft is the sealing end shaft of a pillow packaging machine, the interval that uniquely determines the cam curve, such as the sealing interval, conforms to the non-application interval.

[0078] When the interval setting unit 50 determines the application interval and the non-application interval, it acquires or generates an out-of-interval cam curve that specifies the relationship between the position of the main shaft and the position of the driven shaft within the specified non-application interval from the outside.

[0079] When the interval setting unit 50 is to generate an out-of-interval cam curve, for example, in addition to acquiring the coordinate values in the interval information, it can also acquire the dimensions of various components in the industrial equipment, the operating conditions of the processing procedures performed by the industrial equipment, etc. from the outside, and generate the out-of-interval cam curve based on these coordinate values, dimensions, operating conditions, etc.

[0080] The out-of-interval cam curve can also specify, for example, the relationship between the position of the main shaft and the speed of the driven shaft, the relationship between the position of the main shaft and the acceleration of the driven shaft, or the relationship between the position of the main shaft and the jerk of the driven shaft within the non-application interval.

[0081] The out-of-interval cam curve acquired or generated by the interval setting unit 50 is stored in the cam curve storage unit 80 described later.

[0082] The division condition acquisition unit 30 acquires division conditions based on the cam curve generation conditions received by the input reception unit 10. Here, it is described that the division conditions are included in the cam curve generation conditions, but the division conditions may also be predetermined, for example. In this case, the division condition acquisition unit 30 may also store the predetermined division conditions instead of acquiring the division conditions based on the cam curve generation conditions received by the input reception unit 10.

[0083] The division conditions include the division number indicating the number of subintervals to be divided, the length of each subinterval among the plurality of subintervals, and the category of each subinterval among the plurality of subintervals.

[0084] Here, the length of the subinterval is information that can calculate the difference between the position of the main shaft at the start end of the subinterval and the position of the main shaft at the end end of the subinterval. Regarding the length of the subinterval, as an example where it is not necessarily required to limit the length of the subinterval, for example, the length of the subinterval is the interval between the position of the main shaft at the start end of the subinterval and the position of the main shaft at the end end of the subinterval.

[0085] Here, the category is information indicating which category of subinterval it is, that is, a subinterval in which the acceleration of the follower shaft monotonically increases or decreases or a subinterval in which the acceleration of the follower shaft remains unchanged.

[0086] The interval division unit 60 divides the application interval into a plurality of subintervals in a manner that satisfies the division conditions based on the division conditions acquired by the division condition acquisition unit 30.

[0087] Therefore, the interval division unit 60 divides the application interval into subintervals of any one of the categories, that is, subintervals in which the acceleration of the follower shaft monotonically increases or decreases and subintervals in which the acceleration of the follower shaft remains unchanged.

[0088] When the interval division unit 60 divides the application interval into a plurality of subintervals, it outputs information indicating each subinterval to the cam curve generation unit 70. The information indicating the subinterval may be, for example, the coordinate value of the position of the main shaft at the boundary of the subinterval and the category of the subinterval.

[0089] The boundary condition acquisition unit 40 acquires boundary conditions based on the cam curve generation conditions received by the input reception unit 10.

[0090] The boundary conditions include the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the start end of the application interval, and the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the end end of the application interval.

[0091] Here, it is described by assuming that the boundary conditions are included in the cam curve generation conditions. However, the boundary conditions can also be predetermined, for example. In this case, the boundary condition acquisition unit 40 can also store the predetermined boundary conditions instead of acquiring the boundary conditions based on the cam curve generation conditions received by the input reception unit 10.

[0092] In addition, the boundary condition acquisition unit 40 can also generate the boundary conditions based on the out-of-range cam curves stored in the cam curve storage unit 80 instead of acquiring the boundary conditions based on the cam curve generation conditions received by the input reception unit 10. In this case, the boundary condition acquisition unit 40 can, for example, also calculate the position, velocity, and acceleration of the follower shaft at the end of the out-of-range cam curve of the out-of-range application interval adjacent to the application interval as the position, velocity, and acceleration of the follower shaft at the start of the application interval, respectively. It can also calculate the position, velocity, and acceleration of the follower shaft at the start of the out-of-range cam curve of the out-of-range application interval adjacent to the application interval after the application interval as the position, velocity, and acceleration of the follower shaft at the end of the application interval, respectively.

[0093] The cam curve generation unit 70 generates the cam curve of the application interval in a manner that satisfies the boundary conditions based on the boundary conditions acquired by the boundary condition acquisition unit 40. At this time, the cam curve generation unit 70 generates the cam curve in a manner that makes the position, velocity, and acceleration of the follower shaft continuous at each boundary of the plurality of sub-intervals based on the information indicating the sub-intervals output from the interval division unit 60.

[0094] A specific example of the cam curve generated by the cam curve generation unit 70 will be described later.

[0095] The cam curve storage unit 80 stores the cam curve generated by the cam curve generation unit 70. In addition, as described above, the cam curve storage unit 80 stores the out-of-range cam curves acquired or generated by the interval setting unit 50.

[0096] The cam curve storage unit 80 can store the cam curve or the out-of-range cam curve itself. In the case where the cam curve or the out-of-range cam curve is a function that defines the relationship between the position of the main shaft and the position of the follower shaft, it can also store the factor data of the function. In the case where the cam curve or the out-of-range cam curve is a data table that defines the relationship between the position of the main shaft and the position of the follower shaft, it can also store the numerical values of the data constituting the data table.

[0097] The follower shaft command generation unit 90 acquires the main shaft position, generates a command for the follower shaft based on the main shaft position and the cam curve or the out-of-range cam curve stored in the cam curve storage unit 80, and outputs the command.

[0098] <Operation>

[0099] As an example, the cam curve generation device 100 with the above structure performs a first cam curve generation process for generating a cam curve.

[0100] Next, the first cam curve generation process performed by the cam curve generation device 100 will be described with reference to the drawings.

[0101] Figure 2 is a flowchart of the first cam curve generation process.

[0102] For example, the first cam curve generation process is started by operating the cam curve generation device 100 to start the first cam curve generation process.

[0103] When the first cam curve generation process starts, the section information acquisition unit 20 acquires section information (step S10). More specifically, the section information acquisition unit 20 acquires section information according to the cam curve generation conditions accepted by the input acceptance unit 10. When the section information acquisition unit 20 acquires the section information, the section setting unit 50 sets an application section and a non-application section based on the section information (step S20).

[0104] Next, the division condition acquisition unit 30 acquires division conditions (step S30). More specifically, the division condition acquisition unit 30 acquires division conditions according to the cam curve generation conditions accepted by the input acceptance unit 10. When the division condition acquisition unit 30 acquires the division conditions, the section division unit 60 divides the application section into a plurality of sub-sections in a manner that satisfies the division conditions based on the division conditions (step S40). Then, the section division unit 60 outputs information representing each sub-section to the cam curve generation unit 70.

[0105] Next, the boundary condition acquisition unit 40 acquires boundary conditions (step S50). More specifically, the boundary condition acquisition unit 40 acquires boundary conditions according to the cam curve generation conditions accepted by the input acceptance unit 10. When the boundary condition acquisition unit 40 acquires the boundary conditions, the cam curve generation unit 70 generates a cam curve for the application section in a manner that satisfies the boundary conditions based on the boundary conditions acquired by the boundary condition acquisition unit 40. At this time, the cam curve generation unit 70 generates a cam curve in such a way that the position, speed, and acceleration of the follower shaft are continuous at the boundaries of the plurality of sub-sections based on the information representing the sub-sections output from the section division unit 60 (step S60).

[0106] When the process of step S60 ends, the cam curve generation device 100 ends the first cam curve generation process.

[0107] <Specific example>

[0108] Next, the specific processing content of the processing in step S60 will be described with reference to the accompanying drawings.

[0109] Figure 3 It is a waveform diagram showing an example of the cam curve generated by the cam curve generation unit 70 in the processing of step S60.

[0110] Figure 3 The upper waveform diagram shows the cam curve representing the relationship between the position of the specified main shaft and the position of the driven shaft. In the upper waveform diagram, the horizontal axis (x-axis) represents the position x of the main shaft, and the vertical axis (y-axis) represents the position y of the driven shaft.

[0111] Figure 3 The middle waveform diagram shows the cam curve representing the relationship between the position of the specified main shaft and the speed of the driven shaft. In the middle waveform diagram, the horizontal axis (x-axis) represents the position x of the main shaft, and the vertical axis (v-axis) represents the speed v of the driven shaft.

[0112] Figure 3 The lower waveform diagram shows the cam curve representing the relationship between the position of the specified main shaft and the acceleration of the driven shaft. In the lower waveform diagram, the horizontal axis (x-axis) represents the position x of the main shaft, and the vertical axis (a-axis) represents the acceleration a of the driven shaft.

[0113] In Figure 3 the upper waveform diagram, the middle waveform diagram, and the lower waveform diagram, the interval where the position of the main shaft is from X0 to X5 is the interval set as the application interval, and the interval where the position of the main shaft is from X s to X0 is the interval set as the first non-application interval, and the interval where the position of the main shaft is from X5 to X e is the interval set as the second non-application interval. That is, the cam curve of the application interval where the position of the main shaft is from X0 to X5 is the cam curve generated by the cam curve generation unit 70 in the processing of step S60.

[0114] For example, in Figure 3 the upper waveform diagram, the coordinate values representing the boundaries of the application interval are (X0, Y0), (X5, Y5).

[0115] The boundary condition at the start end of the application interval is set to the coordinate values equal to the end of the cam curve of the first non-application interval, that is, the position Y0 of the driven shaft, the speed V0 of the driven shaft, and the acceleration A0 of the driven shaft. In addition, the boundary condition at the end of the application interval is set to the coordinate values equal to the start of the cam curve of the second non-application interval, that is, the position Y5 of the driven shaft, the speed V5 of the driven shaft, and the acceleration A5 of the driven shaft.

[0116] In Figure 3In the example shown, the application range is divided into five sub-ranges: a first sub-range, a second sub-range, a third sub-range, a fourth sub-range, and a fifth sub-range, which are consecutive in order starting from the side with a smaller position on the main axis. The coordinate values of the positions of the main axis representing the boundaries of these five sub-ranges are X0, X1, X2, X3, X4, and X5.

[0117] The first sub-range, the third sub-range, and the fifth sub-range are set as sub-ranges of the category in which the acceleration of the slave axis monotonically increases or decreases. In addition, the second sub-range and the fourth sub-range are set as sub-ranges of the category in which the acceleration of the slave axis remains unchanged.

[0118] In the process of step S60, the cam curve generation unit 70 defines the acceleration a of the slave axis within the first sub-range to the fifth sub-range using a function a(x) of the position x of the main axis shown in the following (Equation 1). In (Equation 1), K iT (i = 1, 3, 5) and K i2 (i = 1, 2, 3, 4, 5) are coefficients.

[0119] (Equation 1)

[0120] It is set as

[0121] [Formula 1]

[0122] Δx = x - X i-1 , ΔX i = X i - X i-1 ,

[0123] Then it is defined as

[0124] [Formula 2]

[0125]

[0126] In (Equation 1), the waveform of the acceleration a of the follower shaft within the first sub-interval from the start to the end of the first sub-interval is defined by a sine wave with a phase shift from 0 to π×1 / 2. That is, the waveform of the acceleration a of the follower shaft within the first sub-interval from the start to the end of the first sub-interval is the shape of a quarter-cycle portion up to the peak of the sine wave. Here, in this specification, the term "peak" includes both positive and negative peaks. Additionally, the waveform of the acceleration a of the follower shaft within the third sub-interval from the start to the end of the third sub-interval is defined by a sine wave with a phase shift from π×1 / 2 to π×3 / 2. That is, the waveform of the acceleration a of the follower shaft within the third sub-interval from the start to the end of the third sub-interval is the shape of a half-cycle portion starting from the peak of the sine wave. Moreover, the waveform of the acceleration a of the follower shaft within the fifth sub-interval from the start to the end of the fifth sub-interval is defined by a sine wave with a phase shift from π×3 / 2 to π×2. That is, the waveform of the acceleration a of the follower shaft within the fifth sub-interval from the start to the end of the fifth sub-interval is the shape of a quarter-cycle portion starting from the peak of the sine wave.

[0127] Furthermore, these functions are an example, and as long as the function is such that the acceleration a of the follower shaft monotonically increases or decreases within the first sub-interval, the third sub-interval, and the fifth sub-interval, the functions within these intervals can also be arbitrary functions. For example, the waveform of the acceleration a of the follower shaft within the first sub-interval from the start to the end of the first sub-interval can also be defined by a sine wave with a phase shift from π to π×3 / 2. That is, the waveform of the acceleration a of the follower shaft within the first sub-interval from the start to the end of the first sub-interval can also be the shape of a quarter-cycle portion up to the peak of the sine wave. Additionally, the waveform of the acceleration a of the follower shaft within the third sub-interval from the start to the end of the third sub-interval can also be defined by a sine wave with a phase shift from π×(-1 / 2) to π×1 / 2. That is, the waveform of the acceleration a of the follower shaft within the third sub-interval from the start to the end of the third sub-interval can also be the shape of a half-cycle portion starting from the peak of the sine wave. Moreover, the waveform of the acceleration a of the follower shaft within the fifth sub-interval from the start to the end of the fifth sub-interval can also be defined by a sine wave with a phase shift from π×1 / 2 to π. That is, the waveform of the acceleration a of the follower shaft within the fifth sub-interval from the start to the end of the fifth sub-interval can also be the shape of a quarter-cycle portion starting from the peak of the sine wave.

[0128] By integrating (Equation 1) with respect to the position x of the main shaft, a function v(x) that defines the velocity v of the follower shaft within the first sub-interval to the fifth sub-interval is obtained as follows in (Equation 2). In (Equation 2), K i1 (i = 1, 2, 3, 4, 5) is an integration constant and is a coefficient.

[0129] (Equation 2)

[0130] Set as

[0131] [Number 3]

[0132] Δx = x - X i-1 , ΔX i = X i - X i-1 ,

[0133] Then obtain

[0134] [Number 4]

[0135]

[0136] By integrating (Equation 2) with respect to the position x of the main axis, a function y(x) that defines the position y of the follower axis within the first to fifth sub-intervals is obtained as described in (Equation 3) below. In (Equation 3), K i0 (i = 1, 2, 3, 4, 5) are integration constants and are coefficients.

[0137] (Equation 3)

[0138] Set as

[0139] [Number 5]

[0140] Δx = x - X i-1 , ΔX i = X i - X i-1 ,

[0141] Then obtain

[0142] [Number 6]

[0143]

[0144] The Ks included in (Equation 1), (Equation 2), and (Equation 3) iT (i = 1, 3, 5), K i2 (i = 1, 2, 3, 4, 5), K i1 (i = 1, 2, 3, 4, 5) and K i0 (i = 1, 2, 3, 4, 5) are coefficients of the cam curve or factors thereof. They are unknowns before the processing of step S60, but are calculated by the cam curve generation unit 70 during the processing of step S60.

[0145] In the examples of (Equation 1), (Equation 2), and (Equation 3), the unknowns are the above 18 unknowns. Therefore, the calculation of the unknowns requires 18 conditions of the same number. As described below, in the process of step S60, the cam curve generation unit 70 calculates the above 18 unknowns based on 6 boundary conditions at the start and end of the application interval and 12 continuous conditions of the position, speed, and acceleration of the follower shaft at the boundaries of each sub-interval, for a total of 18 conditions.

[0146] Substitute Figure 3 the boundary conditions Y0, V0, and A0 at the start of the application interval shown, that is, the position X0 of the main shaft of the first sub-interval, into (Equation 1), (Equation 2), and (Equation 3) to obtain the 3 equations shown in the following (Equation 4).

[0147] (Equation 4)

[0148] [Equation 7]

[0149] A0 = a1(X0) → A0 = K 12

[0150]

[0151] Y0 = y1(X0) → Y0 = K 10

[0152] Substitute Figure 3 the boundary conditions Y5, V5, and A5 at the end of the application interval shown, that is, the position X5 of the main shaft of the fifth sub-interval, into (Equation 1), (Equation 2), and (Equation 3) to obtain the 3 equations shown in the following (Equation 5).

[0153] (Equation 5)

[0154] Let

[0155] [Equation 8]

[0156] ΔX5 = X5 - X4,

[0157] then we get

[0158] [Equation 9]

[0159] A5 = a5(X5) → A5 = K 52 +K 5r

[0160] V5 = v5(X5) → V5 = K 51 +K 52 ΔX5

[0161]

[0162] By assigning the acceleration a of the follower shaft to (Equation 1)Figure 3 Continuously satisfy such conditions at the boundaries of the respective subintervals shown to obtain the following four equations shown in (Equation 6).

[0163] (Equation 6)

[0164] Let it be

[0165] [Number 10]

[0166] ΔX i = X i - X i-1 ,

[0167] Then, we obtain

[0168] [Number 11]

[0169] a1(X1) = a2(X1) → K 12 + K 1T = K 22

[0170] a2(X2) = a3(X2) → K 22 = K 32 + K 3T

[0171] a3(X3) = a4(X3) → K 32 - K 3T = K 42

[0172] a4(X4) = a5(X4) → K 42 = K 52 + K 5T

[0173] By imposing the condition that the speed v of the driven shaft is continuous at the boundaries of the respective subintervals shown in (Equation 2), the following four equations shown in (Equation 7) are obtained. Figure 3 Continuously satisfy such conditions at the boundaries of the respective subintervals shown to obtain the following four equations shown in (Equation 7).

[0174] (Equation 7)

[0175] Let it be

[0176] [Number 12]

[0177] ΔX i = X i - X i-1 ,

[0178] Then we obtain

[0179] [Number 13]

[0180] v1(X1) = v2(X1) → K 11 + K 12 ΔX1 = K21

[0181] v2(X2) = v3(X2) → K 21 +K 22 ΔX2 = K 31

[0182] v3(X3) = v4(X3) → K 31 +K 32 ΔX3 = K 41

[0183] v4(X4) = v5(X4) → K 41 +K 42 ΔX4 = K 51

[0184] By imposing the condition that the position y of the follower shaft is continuous at the boundaries of the respective sub - intervals shown in Figure 3 the following four equations shown in (Equation 8) are obtained.

[0185] (Equation 8)

[0186] Let it be

[0187] [Number 14]

[0188] ΔX i = X i - X i-1 ,

[0189] then we get

[0190] [Number 15]

[0191]

[0192]

[0193]

[0194]

[0195] In the process of step S60, the cam curve generation unit 70 solves the 18 - variable simultaneous equations composed of the 18 equations shown in (Equations 4) to (Equation 8) to calculate the unknowns K iT (i = 1, 3, 5), K i2 (i = 1, 2, 3, 4, 5), K i1 (i = 1, 2, 3, 4, 5) and K i0 (i = 1, 2, 3, 4, 5).

[0196] The cam curve generation unit 70 can calculate the above unknowns by solving the above 18 - variable simultaneous equations each time a cam curve is generated, or can pre - store the calculation formula obtained by transforming the above 18 - variable simultaneous equations and calculate the above unknowns based on the stored calculation formula.

[0197] Next, an example of the cam curve shown in Figure 3 is used to illustrate an example of the effect obtained by the cam curve generation device 100.

[0198] In the cam curve of the application interval in Figure 3 , at the start end where the position of the main shaft is represented as X0, it has the position Y0 of the follower shaft, the speed V0 of the follower shaft, and the acceleration A0 of the follower shaft that are equal to the end of the cam curve of the adjacent first application outer interval. In addition, at the end where the position of the main shaft is represented as X5, it has the position Y5 of the follower shaft, the speed V5 of the follower shaft, and the acceleration A5 of the follower shaft that are equal to the start of the cam curve of the adjacent second application outer interval. In this way, according to the cam curve generation device 100, the cam curve of the application interval is generated in such a way that it has a start - end shape and an end - shape that are smoothly connected to the adjacent application outer intervals. Therefore, according to the cam curve generation device 100, it is possible to provide an electronic cam control in which the speed and acceleration of the follower shaft do not change abruptly near the boundary between the application interval and the application outer interval.

[0199] In addition, Figure 3 the cam curve of the application interval in

[0200] has a second sub - interval and a fourth sub - interval in which the acceleration a of the follower shaft is constant, and the position y of the follower shaft, the speed v of the follower shaft, and the acceleration a of the follower shaft are continuous at the boundaries of each sub - interval. Therefore, according to the cam curve generation device 100, compared with the electronic cam control using a cam curve generated by a fifth - order curve as in the prior art described in Patent Document 1, it is possible to provide an electronic cam control that suppresses the variation of the speed and acceleration of the follower shaft within the application interval.

[0201] Figure 4 is a waveform diagram showing another example of the cam curve generated by the cam curve generation unit 70 in the process of step S60.

[0202] Figure 4The waveform diagram above shows a cam curve that defines the relationship between the position of the main shaft and the position of the driven shaft. In the upper waveform diagram, the horizontal axis (x-axis) represents the position x of the main shaft, and the vertical axis (y-axis) represents the position y of the driven shaft.

[0203] Figure 4 The middle waveform diagram shows a cam curve that defines the relationship between the position of the main shaft and the speed of the driven shaft. In the middle waveform diagram, the horizontal axis (x-axis) represents the position x of the main shaft, and the vertical axis (v-axis) represents the speed v of the driven shaft.

[0204] Figure 4 The waveform diagram below shows a cam curve that defines the relationship between the position of the main shaft and the acceleration of the driven shaft. In the lower waveform diagram, the horizontal axis (x-axis) represents the position x of the main shaft, and the vertical axis (a-axis) represents the acceleration a of the driven shaft.

[0205] In Figure 4 the upper waveform diagram, the middle waveform diagram, and the lower waveform diagram, the interval where the position of the main shaft is from X0 to X7 is set as the application interval, and the interval where the position of the main shaft is from X s to X0 is set as the first non-application interval, and the interval where the position of the main shaft is from X7 to X e is set as the second non-application interval. That is, the cam curve in the application interval where the position of the main shaft is from X0 to X7 is the cam curve generated by the cam curve generation unit 70 in the process of step S60.

[0206] The boundary conditions at the start of the application interval are set to the coordinate values equal to the end of the cam curve in the first non-application interval, that is, the position Y0 of the driven shaft, the speed V0 of the driven shaft, and the acceleration A0 of the driven shaft. In addition, the boundary conditions at the end of the application interval are set to the coordinate values equal to the start of the cam curve in the second non-application interval, that is, the position Y7 of the driven shaft, the speed V7 of the driven shaft, and the acceleration A7 of the driven shaft.

[0207] In Figure 4 the example shown, the application interval is divided into seven sub-intervals: the first sub-interval, the second sub-interval, the third sub-interval, the fourth sub-interval, the fifth sub-interval, the sixth sub-interval, and the seventh sub-interval, which are consecutive in order from the side with the smaller position of the main shaft. The coordinate values of the positions of the main shaft representing the boundaries of these seven sub-intervals are X0, X1, X2, X3, X4, X5, X6, X7.

[0208] The first sub-interval, the third sub-interval, the fifth sub-interval, and the seventh sub-interval are set as sub-intervals of the category in which the acceleration of the follower shaft monotonically increases or decreases. Additionally, the second sub-interval and the sixth sub-interval are set as sub-intervals of the category in which the acceleration of the follower shaft is constant and the acceleration is a value other than 0. Additionally, the fourth sub-interval is set as a sub-interval of the category in which the acceleration of the follower shaft is constant and the acceleration is 0.

[0209] In the process of step S60, the cam curve generation unit 70 defines the acceleration a of the follower shaft within the first sub-interval to the seventh sub-interval using a function a(x) of the position x of the main shaft shown in the following (Equation 9). In (Equation 9), K i3 (i = 1, 3, 5, 7) and K i2 (i = 1, 2, 3, 5, 6, 7) are coefficients.

[0210] (Equation 9)

[0211] Let it be

[0212] [Equation 16]

[0213] Δx = x - X i-1 ,

[0214] Then it is defined as

[0215] [Equation 17]

[0216]

[0217] In (Equation 9), the waveforms of the acceleration a of the follower shaft from the start to the end of each sub-interval within the first sub-interval, the third sub-interval, the fifth sub-interval, and the seventh sub-interval are defined by a first-degree polynomial of the position x of the main shaft. In addition, these functions are an example, and as long as the function is one in which the acceleration a of the follower shaft monotonically increases or decreases within the first sub-interval, the third sub-interval, the fifth sub-interval, and the seventh sub-interval, the functions in these intervals can also be arbitrary functions.

[0218] By integrating (Equation 9) with respect to the position x of the main shaft, a function v(x) that defines the speed of the follower shaft within the first sub-interval to the seventh sub-interval is obtained as shown in the following (Equation 10). In (Equation 10), K i1 (i = 1, 2, 3, 4, 5, 6, 7) are integration constants and are coefficients.

[0219] (Equation 10)

[0220] Let it be

[0221] [Equation 18]

[0222] Δx = x - X i-1 ,

[0223] Then,

[0224] [Number 19]

[0225]

[0226] By integrating (Equation 10) with respect to the position x of the main shaft, a function y(x) that defines the position y of the slave shaft within the first to seventh sub-intervals is obtained as shown in the following (Equation 11). In (Equation 11), K i0 (i = 1, 2, 3, 4, 5, 6, 7) is an integration constant and is a coefficient.

[0227] (Equation 11)

[0228] Let it be

[0229] [Number 20]

[0230] Δx = x - X i-1 ,

[0231] Then,

[0232] [Number 21]

[0233]

[0234] The K i3 (i = 1, 3, 5, 7), K i2 (i = 1, 2, 3, 5, 6, 7), K i1 (i = 1, 2, 3, 4, 5, 6, 7), and K i0 (i = 1, 2, 3, 4, 5, 6, 7) included in (Equation 9), (Equation 10), and (Equation 11) are coefficients of the cam curve or factors thereof. They are unknowns before the processing of step S60, but are calculated by the cam curve generation unit 70 in the processing of step S60.

[0235] In the examples of (Equation 9), (Equation 10), and (Equation 11), there are 24 unknowns as described above. Therefore, the calculation of the unknowns requires 24 conditions of the same number. As described below, in the processing of step S60, the cam curve generation unit 70 calculates the above 24 unknowns based on 6 boundary conditions at the start and end of the application interval and 18 continuity conditions of the position, velocity, and acceleration of the slave shaft at the boundaries of each sub-interval, for a total of 24 conditions.

[0236] Substitute Figure 4 the boundary conditions Y0, V0, A0 at the start of the application interval shown, that is, at the position X0 of the main shaft in the first sub-interval, into (Number 9), (Number 10), and (Number 11), to obtain 3 equations shown in the following (Equation 12).

[0237] (Equation 12)

[0238] [Number 22]

[0239] A0 = a1(X0) → A0 = K 12

[0240] V0 = v1(X0) → V0 = K 11

[0241] Y0 = y1(X0) → Y0 = K 10

[0242] Substitute Figure 4 the boundary conditions Y7, V7, A7 at the end of the application interval shown, i.e., at the position X7 of the main axis of the seventh sub-interval, into (Equation 9), (Equation 10), and (Equation 11), to obtain the following 3 equations shown in (Equation 13).

[0243] (Equation 13)

[0244] Let it be

[0245] [Number 23]

[0246] ΔX7 = X7 - X6,

[0247] then we get

[0248] [Number 24]

[0249] A7 = a7(X7) → A7 = K 72 +K 73 ΔX7

[0250]

[0251]

[0252] By imposing the condition that the acceleration a of the follower shaft is continuous at the boundaries of each sub-interval shown in Figure 4 the following 6 equations shown in (Equation 14) are obtained.

[0253] (Equation 14)

[0254] Let it be

[0255] [Number 25]

[0256] ΔX i = X i - X i-1 ,

[0257] then we get

[0258] [Number 26]

[0259] a1(X1) = a2(X1) → K 12 +K 13 ΔX1 = K 22

[0260] a2(X2) = a3(X2) → K 22 =K 32

[0261] a3(X3) = a4(X3) → K 32 +K 33 ΔX3 = 0

[0262] a4(X4) = a5(X4) → 0 = K 52

[0263] a5(X5) = a6(X5) → K 52 +K 53 ΔX5 = K 62

[0264] a6(X6) = a7(X6) → K 62 =K 72

[0265] By imposing the condition that the velocity v of the driven shaft is continuous at the boundaries of the respective sub - intervals shown in Figure 4 the following six equations shown in (Equation 15) are obtained.

[0266] (Equation 15)

[0267] Let it be

[0268] [Equation 27]

[0269] ΔX i =X i -X i-1 ,

[0270] Then we get

[0271] [Equation 28]

[0272]

[0273] v2(X2) = v3(X2) → K 21 +K 22 ΔX2 = K 31

[0274]

[0275] v4(X4) = v5(X4) → K 41 =K 51

[0276]

[0277] v6(X6) = v7(X6) → K 61 +K 62 ΔX6 = K 71

[0278] By imposing the condition that the position y of the follower shaft is continuous at the boundaries of the respective sub - intervals shown in Figure 4 the following six equations shown in (Equation 16) are obtained.

[0279] (Equation 16)

[0280] Let it be

[0281] [Number 29]

[0282] ΔX i = X i - X i-1 ,

[0283] Then we get

[0284] [Number 30]

[0285]

[0286]

[0287]

[0288] y4(X4) = y5(X4) → K 40 +K 41 ΔX4 = K 50

[0289]

[0290]

[0291] In the process of step S60, the cam curve generation unit 70 solves a system of 24 simultaneous equations composed of the 24 equations shown in (Equations 12) to (16) to calculate the unknowns K i3 (i = 1, 3, 5, 7), K i2 (i = 1, 2, 3, 5, 6, 7), K i1 (i = 1, 2, 3, 4, 5, 6, 7) and K i0 (i = 1, 2, 3, 4, 5, 6, 7).

[0292] The cam curve generation unit 70 can calculate the above-mentioned unknowns by solving the above 24-variable simultaneous equations every time a cam curve is generated, or can pre-store the calculation formula obtained by transforming the above 24-variable simultaneous equations and calculate the above-mentioned unknowns based on the stored calculation formula.

[0293] Next, an example of the cam curve shown in Figure 4 is used to illustrate an example of the effect obtained in addition to the example of the effect obtained by the cam curve generation device 100 illustrated by an example of the cam curve shown in Figure 3 An example of the effect obtained is illustrated.

[0294] Figure 4 The cam curve in the application interval in [[ ]] has a fourth sub-interval in which the speed v of the follower shaft is constant, and the position y of the follower shaft, the speed v of the follower shaft, and the acceleration a of the follower shaft are continuous at the boundaries of each sub-interval. Therefore, according to the cam curve generation device 100, compared with the electronic cam control using a cam curve generated by a fifth-degree curve as in the prior art described in Patent Document 1, it is possible to provide an electronic cam control that suppresses fluctuations in the speed of the follower shaft and the acceleration of the follower shaft within the application interval.

[0295] <Examination>

[0296] According to the cam curve generation device 100, the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the start end of the application interval, and the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the end of the application interval are determined based on the acquired boundary conditions. Therefore, according to the cam curve generation device 100, by setting the acquired boundary conditions as appropriate conditions, it is possible to generate a cam curve that is smoothly connected to the out-of-interval cam curve outside the application interval.

[0297] In addition, according to the cam curve generation device 100, the speed of the follower shaft and the acceleration of the follower shaft within the application interval are determined based on the acquired division conditions. Therefore, according to the cam curve generation device 100, by setting the acquired division conditions as appropriate conditions, it is possible to generate a cam curve that suppresses fluctuations in the speed of the follower shaft and the acceleration of the follower shaft within the application interval.

[0298] Therefore, according to the cam curve generation device 100, it is possible to generate a cam curve that is smoothly connected to the out-of-interval cam curve and suppresses fluctuations in the speed of the follower shaft and the acceleration of the follower shaft within the application interval.

[0299] (Embodiment 2)

[0300] Next, the cam curve generation system according to Embodiment 2, which is formed by changing a part of the structure of the cam curve generation system 1 according to Embodiment 1, will be described.

[0301] <Structure>

[0302] Figure 5 It is a block diagram showing an example of the structure of the cam curve generation system 1A according to Embodiment 2.

[0303] As Figure 5 shown, the cam curve generation system 1A is configured by changing the cam curve generation device 100 to the cam curve generation device 100A with respect to the cam curve generation system 1 according to Embodiment 1. Moreover, the cam curve generation device 100A is configured by changing the boundary condition acquisition unit 40 to the boundary condition acquisition unit 40A, changing the cam curve storage unit 80 to the cam curve storage unit 80A, and adding a boundary condition calculation unit 110 with respect to the cam curve generation device 100 according to Embodiment 1.

[0304] In addition to the functions of the cam curve storage unit 80 according to Embodiment 1, the cam curve storage unit 80A has the following functions. That is, the cam curve storage unit 80A stores cam curves generated in advance by an external device.

[0305] Therefore, the cam curve storage unit 80A stores the cam curves generated by the cam curve generation unit 70 or the cam curves generated in advance by an external device. Hereinafter, the "cam curves generated by the cam curve generation unit 70" or the "cam curves generated in advance by an external device" stored in the cam curve storage unit 80A will be referred to as "existing cam curves".

[0306] The boundary condition calculation unit 110 calculates the first follower position at the first main shaft position, the first follower speed at the first main shaft position, the first follower acceleration at the first main shaft position, the second follower position at the second main shaft position later in time than the first main shaft position, the second follower speed at the second main shaft position, and the second follower acceleration at the second main shaft position based on the existing cam curves stored in the cam curve storage unit 80A.

[0307] Here, the boundary condition calculation unit 110 can, for example, acquire the first main shaft position and the second main shaft position from the outside, or store the pre-determined first main shaft position and the second main shaft position instead of acquiring them from the outside.

[0308] The boundary condition calculation unit 110 calculates the position, speed, and acceleration of the first driven shaft, the position, speed, and acceleration of the second driven shaft. Moreover, a first section from the position of the first main shaft to the position of the second main shaft is set as an application section, and boundary conditions are calculated by setting the position, speed, and acceleration of the first driven shaft as the position, speed, and acceleration of the driven shaft at the start of the application section. In addition, boundary conditions are calculated by setting the position, speed, and acceleration of the second driven shaft as the position, speed, and acceleration of the driven shaft at the end of the application section.

[0309] In addition to having the functions of the boundary condition acquisition unit 40 according to the first embodiment, the boundary condition acquisition unit 40A further has the following functions. That is, the boundary condition acquisition unit 40A acquires the boundary conditions calculated by the boundary condition calculation unit 110.

[0310] <Action>

[0311] As an example, the cam curve generation device 100A with the above structure performs a second cam curve generation process for generating a cam curve.

[0312] Next, the second cam curve generation process performed by the cam curve generation device 100A will be described with reference to the accompanying drawings.

[0313] Figure 6 is a flowchart of the second cam curve generation process.

[0314] As Figure 6 shown, the second cam curve generation process is as follows: with respect to the first cam curve generation process according to the first embodiment, the process of step S5 is added, the process of step S10 is changed to the process of step S10A, the process of step S30 is changed to the process of step S30A, the process of step S50 is changed to the process of step S50A, and the process of step S60 is changed to the process of step S60A. Therefore, here, the processes of step S5, step S10A, step S30A, step S50A, and step S60A will be mainly described.

[0315] For example, the second cam curve generation process is started by operating the cam curve generation device 100A to indicate the start of the second cam curve generation process.

[0316] When the second cam curve generation process starts, the boundary condition calculation unit 110 sets the first interval as the application interval and calculates the boundary conditions based on the existing cam curve stored in the cam curve storage unit 80A (step S5).

[0317] Next, the interval information acquisition unit 20 acquires interval information (step S10A). More specifically, the interval information acquisition unit 20 acquires the interval information in which the first interval is set as the application interval based on the cam curve generation conditions accepted by the input acceptance unit 10. Then, the process proceeds to step S20.

[0318] When the process of step S20 ends, the division condition acquisition unit 30 acquires the division conditions (step S30A). More specifically, the division condition acquisition unit 30 acquires the division conditions in which the first interval is set as the application interval based on the cam curve generation conditions accepted by the input acceptance unit 10. Then, the process proceeds to step S40.

[0319] When the process of step S40 ends, the boundary condition acquisition unit 40A acquires the boundary conditions (step S50A). More specifically, the boundary condition acquisition unit 40A acquires the boundary conditions calculated by the boundary condition calculation unit 110.

[0320] When the boundary conditions are acquired by the boundary condition acquisition unit 40A, the cam curve generation unit 70 generates a cam curve for the application interval in a manner that satisfies the boundary conditions by setting the first interval as the application interval based on the boundary conditions acquired by the boundary condition acquisition unit 40A. At this time, the cam curve generation unit 70 generates a cam curve in such a way that the position, speed, and acceleration of the follower shaft are continuous at the boundaries of the multiple sub-intervals based on the information representing the sub-intervals output from the interval division unit 60 (step S60A).

[0321] When the process of step S60A ends, the cam curve generation device 100A ends this second cam curve generation process.

[0322] <Examination>

[0323] According to the cam curve generation device 100A, it is possible to generate a new cam curve that is smoothly connected to the existing cam curve at the first main shaft position and the second main shaft position and whose main shaft migration range is set from the first main shaft position to the second main shaft position based on the pre-generated existing cam curve.

[0324] (Other Embodiments)

[0325] As described above, the cam curve generation device and the like according to one aspect of the present disclosure have been described based on Embodiment 1 and Embodiment 2. However, the present disclosure is not limited to these embodiments. Modes obtained by applying various modifications conceived by those skilled in the art to these embodiments without departing from the gist of the present disclosure, and modes constructed by combining constituent elements in different embodiments may also be included within the scope of one or more aspects of the present disclosure.

[0326] (1) In Embodiment 1, as an example, it has been described that the cam curve generation device 100 has a structure including the follower shaft command generation unit 90. However, the cam curve generation device 100 does not necessarily need to be limited to the structure including the follower shaft command generation unit 90. For example, the cam curve generation device 100 may be configured not to include the follower shaft command generation unit 90, and the function of the follower shaft command generation unit 90 may be realized by a device external to the cam curve generation device 100.

[0327] (2) In Embodiment 1, it has been described that the cam curve generation device 100 and the servo control device 200 are independent devices. However, it is not necessarily limited to the structure in which the cam curve generation device 100 and the servo control device 200 are independent devices. For example, the cam curve generation device 100 may also be a structure that also realizes the function of the servo control device 200.

[0328] (3) One aspect of the present disclosure is not only such a cam curve generation device 100 and a cam curve generation device 100A, but may also be a cam curve generation method in which characteristic structural parts included in the cam curve generation device 100 and the cam curve generation device 100A are set as steps. In addition, one aspect of the present disclosure may also be a computer program that causes a computer to execute each characteristic step included in the cam curve generation method. In addition, one aspect of the present disclosure may also be a computer-readable non-transitory recording medium on which such a computer program is recorded.

[0329] Industrial Applicability

[0330] The present disclosure can be widely used in a cam curve generation device and the like for generating a cam curve for realizing electronic cam control that controls the position of a follower shaft in synchronization with the position of a main shaft. In addition, the cam curve generation device is also useful in industrial equipment that repeatedly and continuously performs a series of processing steps.

[0331] Description of Reference Numerals

[0332] 1, 1A: Cam curve generation system; 10: Input reception unit; 20: Interval information acquisition unit; 30: Division condition acquisition unit; 40, 40A: Boundary condition acquisition unit; 50: Interval setting unit; 60: Interval division unit; 70: Cam curve generation unit; 80, 80A: Cam curve storage unit; 90: Driven shaft command generation unit; 100, 100A: Cam curve generation device; 110: Boundary condition calculation unit; 200: Servo control device; 300: Motor.

Claims

1. A cam curve generation device generates a cam curve for controlling the position of a follower shaft. The cam curve generation device includes a boundary condition acquisition unit, a segmentation condition acquisition unit, an interval segmentation unit, and a cam curve generation unit. Among them, The boundary condition acquisition unit acquires boundary conditions of an application interval that is an object of generating the cam curve within a range of the main shaft position transition. The segmentation condition acquisition unit acquires segmentation conditions for dividing the application interval into a plurality of sub-intervals. The interval segmentation unit divides the application interval into the plurality of sub-intervals in a manner that satisfies the segmentation conditions. The cam curve generation unit generates the cam curve of the application interval in a manner that satisfies the boundary conditions. Each of the plurality of sub-intervals is a sub-interval in any one of a category of a sub-interval in which the acceleration of the follower shaft monotonically increases, a sub-interval in which the acceleration of the follower shaft monotonically decreases, and a sub-interval in which the acceleration of the follower shaft remains unchanged. The segmentation conditions include the lengths and categories of the plurality of sub-intervals. The boundary conditions include the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the start end of the application interval, and the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft at the end end of the application interval. The cam curve generation unit generates the cam curve in a manner that makes the position of the follower shaft, the speed of the follower shaft, and the acceleration of the follower shaft continuous at each boundary of the plurality of sub-intervals.

2. The cam curve generation device according to claim 1, wherein in at least one of the sub-intervals in which the acceleration of the follower shaft monotonically increases and the sub-intervals in which the acceleration of the follower shaft monotonically decreases, the cam curve generation unit generates the cam curve in a manner that makes the waveform of the acceleration of the follower shaft from the start end to the end end of the sub-interval have a shape of a quarter-cycle portion up to the apex of a sine wave.

3. The cam curve generation device according to claim 1, wherein in at least one of the sub-intervals in which the acceleration of the follower shaft monotonically increases and the sub-intervals in which the acceleration of the follower shaft monotonically decreases, the cam curve generation unit generates the cam curve in a manner that makes the waveform of the acceleration of the follower shaft from the start end to the end end of the sub-interval have a shape of a half-cycle portion starting from the apex of a sine wave.

4. The cam curve generation device according to claim 1, wherein in at least one of the sub-intervals in which the acceleration of the follower shaft monotonically increases and the sub-intervals in which the acceleration of the follower shaft monotonically decreases, the cam curve generation unit generates the cam curve in a manner that makes the waveform of the acceleration of the follower shaft from the start end to the end end of the sub-interval have a shape of a quarter-cycle portion starting from the apex of a sine wave.

5. The cam curve generation device according to claim 1, wherein In at least one of a sub - interval in which the acceleration of the follower shaft monotonically increases and a sub - interval in which the acceleration of the follower shaft monotonically decreases, the cam curve generation unit generates the cam curve such that the waveform of the acceleration of the follower shaft from the start end to the end of the sub - interval is a waveform defined by a first - order polynomial passing through the main shaft position.

6. The cam curve generation device according to any one of claims 1 to 5, wherein the plurality of sub - intervals are five sub - intervals, namely, a first sub - interval, a second sub - interval, a third sub - interval, a fourth sub - interval, and a fifth sub - interval, which are consecutive in order. the first sub - interval, the third sub - interval, and the fifth sub - interval are sub - intervals in which the acceleration of the follower shaft monotonically increases or sub - intervals in which the acceleration of the follower shaft monotonically decreases. the second sub - interval and the fourth sub - interval are sub - intervals in which the acceleration of the follower shaft is constant.

7. The cam curve generation device according to claim 6, wherein the acceleration of the follower shaft in the second sub - interval and the fourth sub - interval is a value other than 0.

8. The cam curve generation device according to any one of claims 1 to 5, wherein the plurality of sub - intervals are seven sub - intervals, namely, a first sub - interval, a second sub - interval, a third sub - interval, a fourth sub - interval, a fifth sub - interval, a sixth sub - interval, and a seventh sub - interval, which are consecutive in order. the first sub - interval, the third sub - interval, the fifth sub - interval, and the seventh sub - interval are sub - intervals in which the acceleration of the follower shaft monotonically increases or sub - intervals in which the acceleration of the follower shaft monotonically decreases. the second sub - interval, the fourth sub - interval, and the sixth sub - interval are sub - intervals in which the acceleration of the follower shaft is constant.

9. The cam curve generation device according to claim 8, wherein the acceleration of the follower shaft in the second sub - interval and the sixth sub - interval is a value other than 0, and the acceleration of the follower shaft in the fourth sub - interval is 0.

10. The cam curve generation device according to any one of claims 1 to 9, wherein it further includes an interval setting unit that divides the range of the main shaft position migration into the application interval and a non - application interval outside the application interval.

11. The cam curve generation device according to any one of claims 1 to 10, further includes: an existing cam curve storage unit that stores a pre - generated existing cam curve; and A boundary condition calculation unit that calculates, based on the existing cam curve, the first follower shaft position of the follower shaft at the first main shaft position, the first follower shaft speed of the follower shaft at the first main shaft position, the first follower shaft acceleration of the follower shaft at the first main shaft position, the second follower shaft position of the follower shaft at a second main shaft position that is later in time than the first main shaft position, the second follower shaft speed of the follower shaft at the second main shaft position, and the second follower shaft acceleration of the follower shaft at the second main shaft position. The boundary condition calculation unit sets a first interval from the first main shaft position to the second main shaft position within the range of the main shaft position migration in the existing cam curve as the application interval, and calculates the boundary conditions in which the first follower shaft position, the first follower shaft speed, the first follower shaft acceleration, the second follower shaft position, the second follower shaft speed, and the second follower shaft acceleration are respectively set as the position of the follower shaft at the start end, the speed of the follower shaft at the start end, the acceleration of the follower shaft at the start end, the position of the follower shaft at the end, the speed of the follower shaft at the end, and the acceleration of the follower shaft at the end. The boundary condition acquisition unit acquires the boundary conditions calculated by the boundary condition calculation unit. The segmentation condition acquisition unit acquires the segmentation conditions for setting the first interval as the application interval. The interval segmentation unit sets the first interval as the application interval and divides the application interval into the plurality of sub-intervals. The cam curve generation unit generates the cam curve by setting the first interval as the application interval.

12. The cam curve generation device according to any one of claims 1 to 11, wherein when an interval other than the application interval in the range of the main shaft position migration is set as an out-of-application interval, at the start end of the application interval, the boundary condition is set as the position, speed, and acceleration of the follower shaft in the out-of-application interval at the time corresponding to the start end, and at the end of the application interval, the boundary condition is set as the position, speed, and acceleration of the follower shaft in the out-of-application interval at the time corresponding to the end.

13. A cam curve generation method for generating a cam curve for controlling the position of a follower shaft, the cam curve generation method comprising the following steps: A first step of acquiring boundary conditions for an application interval that is the object of generating the cam curve within the range of the main shaft position migration; A second step of acquiring segmentation conditions for dividing the application interval into a plurality of sub-intervals; A third step of dividing the application interval into the plurality of sub-intervals in a manner that satisfies the segmentation conditions; and A fourth step of generating the cam curve of the application interval in a manner that satisfies the boundary conditions. Among them, each of the multiple sub-intervals is any one type of sub-interval among the sub-intervals in which the acceleration of the driven shaft monotonically increases, the sub-intervals in which the acceleration of the driven shaft monotonically decreases, and the sub-intervals in which the acceleration of the driven shaft remains unchanged. The segmentation conditions include the lengths and types of the multiple sub-intervals. The boundary conditions include the position of the driven shaft, the speed of the driven shaft, and the acceleration of the driven shaft at the start end of the application interval, and the position of the driven shaft, the speed of the driven shaft, and the acceleration of the driven shaft at the end end of the application interval. In the fourth step, the cam curve is also generated in such a way that the position of the driven shaft, the speed of the driven shaft, and the acceleration of the driven shaft are continuous at each boundary of the multiple sub-intervals.

14. A program for causing a cam curve generation device to execute a cam curve generation process for electronically controlling the position of a driven shaft, where the cam curve generation process includes the following steps: The first step is to obtain the boundary conditions of the application interval that is the object of generating the cam curve within the range of the main shaft position migration. The second step is to obtain the segmentation conditions for dividing the application interval into multiple sub-intervals. The third step is to divide the application interval into the multiple sub-intervals in a manner that satisfies the segmentation conditions; and The fourth step is to generate the cam curve of the application interval in a manner that satisfies the boundary conditions. Among them, each of the multiple sub-intervals is any one type of sub-interval among the sub-intervals in which the acceleration of the driven shaft monotonically increases, the sub-intervals in which the acceleration of the driven shaft monotonically decreases, and the sub-intervals in which the acceleration of the driven shaft remains unchanged. The segmentation conditions include the lengths and types of the multiple sub-intervals. The boundary conditions include the position of the driven shaft, the speed of the driven shaft, and the acceleration of the driven shaft at the start end of the application interval, and the position of the driven shaft, the speed of the driven shaft, and the acceleration of the driven shaft at the end end of the application interval. In the fourth step, the cam curve is also generated in such a way that the position of the driven shaft, the speed of the driven shaft, and the acceleration of the driven shaft are continuous at each boundary of the multiple sub-intervals.

Images