Control device and computer-readable recording medium

Abstract

A control device according to the present disclosure is provided with: an analysis unit that analyzes a command of a control program; a corner detection unit that detects, on the basis of the result of the analysis by the analysis unit, a corner part in which the direction of the movement path becomes discontinuous; a reference curve generation unit that performs acceleration / deceleration processing on each of the movements on the forward and backward movement paths of the corner section, and generates, as a reference curve, a curve that overlaps a predetermined overlap time; a corner curvilinear section that generates a curvilinear movement path by inserting, into the corner section, a curve passing through at least one predetermined reference position on the reference curve; and a curvilinear velocity planning unit that generates a velocity plan pertaining to the movement on the curvilinear movement path, the curvilinear velocity planning unit determining, on the basis of the movement velocity at the reference position on the reference curve, the velocity at the reference position during the movement on the movement path.

Description

Technical Field

[0001] The present invention relates to a control device and a computer-readable recording medium. Background Art

[0002] In industrial machinery such as machine tools with multiple feed axes, when a tool is moved along a discontinuous path such as a right-angle corner at a processing point, the feed speed is reduced at the corner or the shape of the corner is rounded so that no impact is generated when passing the corner (for example, Patent Document 1, etc.).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 09-190211 Summary of the invention

[0006] Problems to be solved by the invention

[0007] As a way to round the shape of the corner, consider inserting a circular arc, a spline curve, a clothoid curve, etc. However, if the speed control at this time is not done well, the speed waveform of each feed axis becomes an undulating shape. Moreover, sometimes due to this reason, impact caused by the change of acceleration or reduction in processing accuracy occurs.

[0008] Therefore, it is important not only to round the shape of the corner portion but also to control the feed speed.

[0009] Means for solving problems

[0010] The control device disclosed in the present invention solves the above-mentioned problem by determining the curvilinearity of the corner and the distribution of the passing speed with reference to a reference curve generated based on the shape of the corner. The reference curve is generated by smoothly accelerating and decelerating each feed axis according to the corner shape of the corner.

[0011] Furthermore, one embodiment of the present disclosure is a control device that drives a feed axis of an industrial machine according to a control program, the control device comprising: an analysis unit that analyzes instructions of the control program; a corner detection unit that detects a corner portion where the direction of a moving path becomes discontinuous based on a result of the analysis by the analysis unit; a reference curve generation unit that performs acceleration and deceleration processing on the movement on the moving path before and after the corner portion, respectively, and generates a curve that overlaps by a predetermined amount of overlapping time as a reference curve; a corner curvilinearization unit that generates a curved moving path by inserting a curve passing through at least one predetermined reference position on the reference curve into the corner portion; and a curve speed planning unit that generates a speed plan involved in the movement on the curved moving path, the curve speed planning unit determining the speed at the reference position in the movement on the moving path based on the moving speed at the reference position on the reference curve.

[0012] Another aspect of the present disclosure is a computer-readable recording medium having a program recorded thereon for causing a computer to operate as a control device that drives a feed axis of an industrial machine according to the control program, the program causing the computer to operate as the following components: an analysis unit that analyzes instructions of the control program; a corner detection unit that detects a corner portion where the direction of a moving path becomes discontinuous based on a result of the analysis by the analysis unit; a reference curve generation unit that performs acceleration and deceleration processing on the movement on the moving path before and after the corner portion, respectively, and generates a curve that overlaps by a predetermined amount of overlapping time as a reference curve; a corner curve forming unit that generates a curve-formed moving path by inserting a curve passing through at least one predetermined reference position on the reference curve into the corner portion; and a curve speed planning unit that generates a speed plan involved in the movement on the curve-formed moving path, the curve speed planning unit determining the speed at the reference position in the movement on the moving path based on the moving speed at the reference position on the reference curve.

[0013] Effects of the Invention

[0014] In one aspect of the present disclosure, by determining the curve formation and the passing speed of the corner portion based on the reference curve, it is expected that the speed waveform fluctuation of each feed axis can be suppressed, the shock can be reduced, and the machining accuracy can be improved.

[0015] Translation of attached pictures

[0016] Figure 1 This is a schematic hardware configuration diagram of a control device according to one embodiment of the present invention.

[0017] Figure 2 This is a block diagram showing the schematic functions of a control device according to one embodiment of the present invention.

[0018] Figure 3 This is a diagram illustrating a corner portion in a moving path.

[0019] Figure 4 This is a graph illustrating the relationship between the moving speeds in each moving path when generating a reference curve.

[0020] Figure 5 It is a diagram showing an example of a reference curve generated by the reference curve generating unit.

[0021] Figure 6 1 and 2 are diagrams showing examples of curves inserted into corner portions by the corner curve forming unit 130 . DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0023] Figure 1 1 is a schematic hardware structure diagram of the main part of the control device of one embodiment of the present invention. The control device 1 of the present invention can be installed as a control device for controlling industrial machinery such as a machine tool and a robot having a moving object that is moved by a motor. The following description takes the control device 1 of a machine tool that controls a workpiece by controlling the relative position of a tool and a workpiece as an example.

[0024] The CPU 11 included in the control device 1 of the present invention is a processor that controls the control device 1 as a whole. The CPU 11 reads a system program stored in the ROM 12 via the bus 22, and controls the control device 1 as a whole according to the system program. The RAM 13 temporarily stores temporary calculation data, display data, and various data input from the outside.

[0025] The nonvolatile memory 14 is composed of, for example, a memory backed up by a battery (not shown), an SSD (Solid State Drive), etc., and maintains the storage state even when the power supply of the control device 1 is turned off. The nonvolatile memory 14 stores control programs and data read from the external device 72 via the interface 15, data and control programs input via the input device 71, and various data obtained from the industrial machine 3. The control programs and data stored in the nonvolatile memory 14 can also be expanded in the RAM 13 when executed / used. In addition, various system programs such as well-known analysis programs are pre-written in the ROM 12.

[0026] The interface 15 is an interface for connecting the CPU 11 of the control device 1 to an external device 72 such as a USB device. For example, a control program, various parameters, etc. used for controlling the industrial machine 3 can be read from the external device 72 side. In addition, the control program, various parameters, etc. edited in the control device 1 can be stored in an external storage unit via the external device 72. The PLC (Programmable Logic Controller) 16 outputs signals to the industrial machine 3 and the peripheral devices of the industrial machine 3 (for example, tool changers, actuators such as robots, sensors installed on the industrial machine 3, etc.) through the timing program built into the control device 1 and controls it through the I / O unit 17. In addition, the PLC 16 receives signals from various switches and peripheral devices of the operating panel equipped on the main body of the industrial machine 3, and transmits them to the CPU 11 after necessary signal processing.

[0027] The display device 70 outputs and displays various data read into the memory, data obtained as a result of executing the control program, the system program, etc., via the interface 18. In addition, the input device 71 composed of a keyboard, a pointing device, etc. transmits instructions, data, etc. based on the operator's operation to the CPU 11 via the interface 19.

[0028] The axis control circuit 30 for controlling the axis of the industrial machine 3 receives the axis movement instruction from the CPU 11, and outputs the axis instruction to the servo amplifier 40. The servo amplifier 40 receives the instruction and drives the servo motor 50 that moves each moving object of the industrial machine 3 along the axis. The servo motor 50 of the axis has a built-in position / speed detector, and the position / speed feedback signal from the position / speed detector is fed back to the axis control circuit 30. The axis control circuit 30 performs feedback control of the position / speed of the servo motor 50. In addition, Figure 1 In the hardware structure diagram of FIG, one axis control circuit 30, one servo amplifier 40, and one servo motor 50 are shown, but in reality, the number of axes of the industrial machine 3 to be controlled is prepared. For example, when controlling a general machine tool with three linear axes, three sets of axis control circuits 30, servo amplifiers 40, and servo motors 50 are prepared to move the spindle with the tool mounted thereon and the workpiece relative to each other in the directions of the three linear axes (X-axis, Y-axis, and Z-axis).

[0029] The spindle control circuit 60 receives the spindle rotation command and outputs a spindle speed signal to the spindle amplifier 61. The spindle amplifier 61 receives the spindle speed signal and rotates the spindle motor 62 of the industrial machine 3 at the instructed rotation speed to drive the spindle. The spindle motor 62 is combined with a position encoder 63. The position encoder 63 outputs a feedback pulse in synchronization with the rotation of the spindle, and the feedback pulse is read by the CPU 11.

[0030] Figure 2This is a diagram showing the functions of a control device 1 according to an embodiment of the present invention as a schematic block diagram. The control device 1 according to this embodiment controls the relative position of a rotating tool and a workpiece, and cuts the workpiece by bringing the tool into contact with the workpiece. The functions of the control device 1 according to this embodiment are shown in FIG. Figure 1 This is achieved by the CPU 11 included in the control device 1 executing a system program to control the operation of each unit of the control device 1 .

[0031] The control device 1 of the present embodiment includes an analyzing unit 100, a corner detecting unit 110, a reference curve generating unit 120, a corner curve forming unit 122, a curve speed planning unit 140, an axis acceleration / deceleration unit 150, and a control unit 160. In addition, a control program 200 for controlling the industrial machine 3 is stored in advance in the RAM 13 or the nonvolatile memory 14 of the control device 1.

[0032] The analysis unit 100 reads out the program blocks of the control program 200 in sequence. Then, the instructions of the read program blocks are analyzed. The control program 200 includes instructions such as the movement amount, movement path, and movement speed of the feed axis. The analysis unit 100 analyzes these instructions and generates data related to the movement instructions for controlling the positions of the servo motors 50. In addition, when the control program 200 includes instructions for the rotation speed of the spindle, data related to the spindle rotation instructions for controlling the rotation of the spindle motor 62 are generated. Preferably, the analysis unit 100 pre-reads and analyzes the program blocks of the control program 200. The analysis unit 100 outputs the data related to the generated instructions to the corner detection unit 110.

[0033] The corner detection unit 110 detects a corner portion where the direction of the moving path becomes discontinuous based on the data related to the moving command input from the analyzing unit 100. In this specification, between two continuous moving paths P 1 , P 2 In the previous moving path P 1 The direction and the subsequent moving path P 2 A portion that is discontinuously connected in a direction is called a corner portion. Figure 3 Indicates an example of a corner. Figure 3 In the example, the moving path P before the corner 1 The direction and the moving path after the corner 2 The corner portion C is connected at a substantially right angle. Figure 3 In addition to the examples shown, the connection may be more acute or more obtuse. 1 , P 2The moving path does not need to be a straight line, and a curve may be drawn. The corner detection unit 110 detects the connection point of each moving path based on the data related to the moving command input from the analysis unit 100. And, for example, the angle formed by the moving path before and after the connection point is a predetermined angle θ determined in advance. th (θ th <180°), the connection point is detected as a corner.

[0034] The reference curve generating unit 120 generates a moving path P before and after the corner C detected by the corner detecting unit 110. 1 , P 2 The reference curve is a curve that is referenced in order to generate a curve inserted into the corner. The reference curve of this embodiment is the moving path P before and after the corner C. 1 , P 2 The movement at the position is accelerated and decelerated, thereby making the moving path P 1 , P 2 Overlap time t o The curve that the moving object moves when the overlapping time t o The path error of the reference curve is adjusted so as to fall within a predetermined allowable error range determined in advance. Figure 4 is the moving path P when generating the reference curve 1 The moving speed and moving path P 2 The curve diagram of the relationship between the moving speed and the moving speed. Figure 4 As shown in the example, the reference curve generation unit 120 makes the moving path P before and after the corner part 1 , P 2 The acceleration and deceleration become smooth acceleration and deceleration with continuous acceleration. Then, by finding the moving path P before the corner 1 The timing advance overlap time t of the mobile completion in o The moving path P after the corner is started 2 The reference curve is generated by the curve of the moving path of the moving object in the case of movement in the overlapping time t o The time constant applied to each axis can be determined as a reference value. Figure 5 2 shows an example of a reference curve generated by the reference curve generating unit 120. The reference curve is a composite of the movement paths P before and after the corner. 1 , P 2 Therefore, even if the reference curve is moved at a composite speed, the speed components in each direction of the moving path, the speed components of each feed axis, and the acceleration component fluctuations can be suppressed, and no fluctuations in speed changes will occur.

[0035] The corner curve forming unit 130 generates a curve based on the reference curve generated by the reference curve generating unit 120, and generates a moving path by inserting the generated curve into the corner detected by the corner detecting unit 110. The corner curve forming unit 130 generates a curve passing through at least one predetermined reference position on the reference curve. The predetermined reference position may be, for example, a position with the maximum curvature on the reference curve.

[0036] Figure 6 1 shows an example of a curve inserted into a corner by the corner curvilinear portion 130. Figure 6 In the example, the reference curve P r The position with the maximum curvature on the 1 , generating a 1 In this case, the corner curve forming unit 130 forms a curve that starts at a predetermined point Ps on the moving path before the corner and ends at a predetermined point Pe on the moving path after the corner, passing through the reference position R. 1 The curve P i Insert the corner portion C. The positions of the starting point Ps and the end point Pe can be compared with the reference curve P r With the moving path P 1 , P 2 The position where the curves meet is closer to the corner. That is, the curve is generated using a second acceleration / deceleration time constant that is smaller than the acceleration / deceleration time constant used to generate the reference curve. By forming a curve with the same position with a large curvature and a reduced acceleration / deceleration time constant, the path error of the curve can be reduced without increasing the shock. p Then, the moving path P before the corner 1 Replace it with a moving path P whose end point is point Ps 1 ', the moving path P after the corner 2 Replace it with the moving path P starting at point Pe 2 ', thus generating a new movement path. The inserted curve only needs to have the same position, velocity, and acceleration at both ends as the movement path P before and after the corner. 1 '、P 2 'It is sufficient that it is approximately continuous. In addition, it is preferred that the interpolated curve is a curve that can be differentiated by multiple orders of second order or higher. Such interpolation processing of curves is well known in, for example, Japanese Patent Publication No. 09-190211 and Japanese Patent Publication No. 10-320026, and therefore a detailed description thereof is omitted in this specification.

[0037] The predetermined reference position on the reference curve that the corner curve conversion unit 130 refers to when generating the curve inserted into the corner portion may be, for example, a position close to the corner portion. The curve passing through this position becomes a curve whose path error is equal to that of the reference curve. In addition, the reference position may be a position where the curvature of the reference curve is locally maximum, that is, a position where the rate of change of the curvature is 0. The corner curve conversion unit 130 may also determine a plurality of positions on the reference curve as reference positions.

[0038] The curve speed planning unit 140 generates a speed plan when moving on the curve inserted by the corner curve forming unit 130. When generating the speed plan, the curve speed planning unit 140 sets the speed when passing through the reference position to a speed substantially the same as the speed when moving on the reference curve. Regarding the speeds at other positions on the curve, the speed plan may be formulated so that the acceleration becomes continuous and smooth acceleration and deceleration.

[0039] The axis acceleration / deceleration unit 150 calculates the movement amount of each axis of the industrial machine 3 per control cycle based on the movement path generated by the corner curve forming unit 130 and the speed plan prepared by the curve speed planning unit 140 , and performs acceleration / deceleration processing on the calculated movement amount.

[0040] The control unit 160 controls the motors of the industrial machine 3 based on the movement amount after the acceleration / deceleration processing by the axis acceleration / deceleration unit 150 and the data related to the spindle rotation command.

[0041] The control device 1 with the above structure determines the passing speed of the corner portion in a manner that the rate of change of the speed in each direction changes monotonically when each moving object moves along the path after the corner portion is curved, so the behavior in each direction is stable and the impact on the machine can be suppressed. In addition, it can also be expected that the processing accuracy of the corner portion will be improved.

[0042] As mentioned above, although embodiment of this invention was described, this invention is not limited only to the example of the said embodiment, It can implement in various forms by adding appropriate changes.

[0043] For example, in the above-mentioned embodiment, the start point Ps and the end point Pe of the interpolated curve are shown to be larger than the reference curve P. r With the moving path P 1 '、P 2 However, the starting point Ps and the end point Pe of the inserted curve are set to be closer to the reference curve P r With the moving path P 1 '、P 2 'When the position of contact is farther from the corner, the time to pass the curve can be shortened. This is because 1 '、P2 'The jerk generated in the orthogonal direction is reduced, making it easier to further increase the cornering speed.

[0044] Description of Reference Numerals

[0045] 1. Control device

[0046] 3Industrial Machinery

[0047] 11CPU

[0048] 12ROM

[0049] 13RAM

[0050] 14 Non-volatile memory

[0051] Interfaces 15, 18, and 19

[0052] 16PLC

[0053] 17I / O Unit

[0054] 22 bus

[0055] 30-axis control circuit

[0056] 40 Servo Amplifier

[0057] 50 Servo motor

[0058] 60 spindle control circuit

[0059] 61 Spindle Amplifier

[0060] 62 Spindle motor

[0061] 63 position encoder

[0062] 70 Display device

[0063] 71 Input device

[0064] 72 External devices

[0065] 100 Analysis Department

[0066] 110 Corner Detection Unit

[0067] 120 reference curve generating unit

[0068] 130 Corner Curve

[0069] 140 Curve Speed ​​Planning Department

[0070] 150 Each axis acceleration and deceleration unit

[0071] 160 Control Department

[0072] 200 control program.

Claims

1. A control device for driving a feed axis of an industrial machine according to a control program, characterized in that: The control device has: an analyzing unit that analyzes instructions of the control program; a corner detection unit that detects a corner portion where the direction of the moving path becomes discontinuous based on the analysis result of the analysis unit; a reference curve generating unit that performs acceleration and deceleration processing on the movement on the front and rear movement paths of the corner portion, respectively, and generates a curve overlapped by a predetermined overlap time as a reference curve; a corner curvilinear unit for generating a curved moving path by inserting a curve passing through at least one predetermined reference position on the reference curve into the corner; as well as a curve speed planning unit for generating a speed plan for movement on the curve-formed movement path; The curve speed planning unit determines a speed at the reference position during movement on the movement path based on a movement speed at the reference position on the reference curve.

2. The control device according to claim 1, characterized in that: The reference position includes a position on the reference curve where the curvature is maximum.

3. The control device according to claim 1, characterized in that: The reference position includes a position on the reference curve that is closest to the corner portion.

4. The control device according to claim 1, characterized in that: The reference position includes a position on the reference curve where the curvature is locally large.

5. The control device according to claim 1, characterized in that: The acceleration and deceleration processing performed by the reference curve generating unit on the movement on the movement path before and after the corner portion is acceleration and deceleration with continuous acceleration.

6. The control device according to claim 1, characterized in that: The overlap time is determined based on the acceleration and deceleration time constants applied to each axis.

7. The control device according to claim 1, characterized in that: The curve speed planning unit makes the speed at the reference position during movement on the movement path substantially the same as the movement speed at the reference position on the reference curve.

8. The control device according to claim 1, characterized in that: The corner curve forming unit generates a curve using a second acceleration / deceleration time constant smaller than the acceleration / deceleration time constant when generating the reference curve so that the distance from the corner of the portion with the maximum curvature becomes the same as the reference curve.

9. A computer-readable recording medium having a program recorded thereon for causing a computer to operate as a control device, the control device driving a feed axis of an industrial machine according to the control program, characterized in that: The program causes the computer to operate as follows: an analyzing unit that analyzes instructions of the control program; a corner detection unit that detects a corner portion where the direction of the moving path becomes discontinuous based on the analysis result of the analysis unit; a reference curve generating unit for performing acceleration and deceleration processing on the movement on the front and rear movement paths of the corner portion, respectively, and generating a curve overlapped by a predetermined overlap time as a reference curve; a corner curvilinear unit for generating a curved moving path by inserting a curve passing through at least one predetermined reference position on the reference curve into the corner; as well as a curve speed planning unit for generating a speed plan for movement on the curve-formed movement path; The curve speed planning unit determines a speed at the reference position during movement on the movement path based on a movement speed at the reference position on the reference curve.

Images