Cam curve generating device and cam curve generating method

1 . A cam curve generating device that generates a cam curve for controlling a position of a driven shaft of a motor, the cam curve generating device comprising:

one or more memories; and

at least one processor coupled to at least one of the one or more memories and configured to perform operations comprising:

acquiring a boundary condition of an application section to be a target of generation of the cam curve in a range in which a main shaft changes in position,

acquiring a division condition for dividing the application section into a plurality of sub-sections,

dividing the application section into the plurality of sub-sections that satisfy the division condition,

generating the cam curve in the application section, the cam curve satisfying the boundary condition, and

causing a servo control device to drive the motor based on the cam curve,

wherein

each of the plurality of sub-sections is any one of types of an increasing sub-section in which acceleration of the driven shaft monotonously increases, a decreasing sub-section in which the acceleration of the driven shaft monotonously decreases, and a constant sub-section in which the acceleration of the driven shaft does not change,

the division condition includes a length and a type of each of the plurality of sub-sections,

the boundary condition includes a position of the driven shaft, a speed of the driven shaft, and the acceleration of the driven shaft at each of a start and an end of the application section, and

the generating comprises generating the cam curve that allows a position of the driven shaft, speed of the driven shaft, and the acceleration of the driven shaft to be continuous at each of boundaries of the plurality of sub-sections.

2 . The cam curve generating device according to claim 1 , wherein

the cam curve includes at least one sub-section of the increasing sub-section and the decreasing sub-section, and

the generating comprises generating the cam curve with a waveform of the acceleration of the driven shaft from a start to an end of the at least one sub-section, the waveform having a shape of a ¼ period part up to an apex of a sine wave.

3 . The cam curve generating device according to claim 1 , wherein

the cam curve includes at least one sub-section of the increasing sub-section and the decreasing sub-section, and

the generating comprises generating the cam curve with a waveform of the acceleration of the driven shaft from a start to an end of the at least one sub-section, the waveform having a shape of a half period part from the apex of the sine wave.

4 . The cam curve generating device according to claim 1 , wherein

the cam curve includes at least one sub-section of the increasing sub-section and the decreasing sub-section, and

the generating comprises generating the cam curve with a waveform of the acceleration of the driven shaft from a start to an end of the at least one sub-section, the waveform having a shape of a ¼ period part from the apex of the sine wave.

5 . The cam curve generating device according to claim 1 , wherein

the cam curve includes at least one sub-section of the increasing sub-section and the decreasing sub-section, and

the generating comprises generating the cam curve with a waveform of the acceleration of the driven shaft from a start to an end of the at least one sub-section, the waveform being defined by a linear polynomial of a position of the main shaft.

6 . The cam curve generating device according to claim 1 , wherein

the plurality of sub-sections are five sub-sections that include a first sub-section, a second sub-section, a third sub-section, a fourth sub-section, and a fifth sub-section, and that are sequentially continuous,

the first sub-section, the third sub-section, and the fifth sub-section are each the increasing sub-section or the decreasing sub-section, and

the second sub-section and the fourth sub-section are each the constant sub-section.

7 . The can curve generating device according to claim 6 , wherein the acceleration of the driven shaft in the second sub-section and the fourth sub-section has a value other than zero.

8 . The cam curve generating device according to claim 1 , wherein

the plurality of sub-sections are seven sub-sections that include a first sub-section, a second sub-section, a third sub-section, a fourth sub-section, a fifth sub-section, a sixth sub-section, and a seventh sub-section and that are sequentially continuous,

the first sub-section, the third sub-section, the fifth sub-section, and the seventh sub-section are each the increasing sub-section or the decreasing sub-section, and

the second sub-section, the fourth sub-section, and the sixth sub-section are each the constant sub-section.

9 . The cam curve generating device according to claim 8 , wherein

the acceleration of the driven shaft in the second sub-section and the sixth sub-section has a value other than zero, and

the acceleration of the driven shaft in the fourth sub-section is zero.

10 . The cam curve generating device according to claim 1 , wherein the operations further comprise dividing a range in which the main shaft changes in position into the application section and a non-application section other than the application section.

11 . The cam curve generating device according to claim 1 , wherein the operations further comprise:

storing an existing cam curve generated in advance; and

calculating values from the existing cam curve, the values including: a first position of the driven shaft at a first position of a main shaft; first speed of the driven shaft at the first position of the main shaft; first acceleration of the driven shaft at the first position of the main shaft; a second position of the main shaft at a time after the first position of the main shaft; second speed of the driven shaft at the second position of the main shaft; and second acceleration of the driven shaft at the second position of the main shaft, and that calculates boundary conditions in which a first section from the first position of the main shaft to the second position of the main shaft is defined as the application section in the range in which the main shaft changes in position in the existing cam curve, the boundary conditions including: a first boundary condition where the first position of the driven shaft, the first speed of the driven shaft, and the first acceleration of the driven shaft are respectively defined as a position of the driven shaft at the start, speed of the driven shaft at the start, and acceleration of the driven shaft at the start; and a second boundary condition where the second position of the driven shaft, the second speed of the driven shaft, and the second acceleration of the driven shaft are respectively defined as a position of the driven shaft at the end, speed of the driven shaft at the end, and the acceleration of the driven shaft at the end, wherein

the acquiring the boundary condition comprises acquiring the boundary conditions,

the acquiring the division condition comprises acquiring the division condition where the first section is defined as the application section,

the dividing comprises defining the first section as the application section and divides the application section into the plurality of sub-sections, and

the generating comprises generating the cam curve with the first section as the application section.

12 . The cam curve generating device according to claim 1 , wherein

the range in which the main shaft changes in position includes a section other than the application section, the section being defined as a non-application section,

the boundary condition includes a third boundary condition at the start of the application section, the third boundary condition being set to a position of the driven shaft, speed of the driven shaft, and the acceleration of the driven shaft in the non-application section at time corresponding to the start, and a fourth boundary condition at the end of the application section, the fourth boundary condition being set to a position of the driven shaft, speed of the driven shaft, and the acceleration of the driven shaft in the non-application section at time corresponding to the end.

13 . A cam curve generating method for generating a cam curve for controlling a position of a driven shaft of a motor, the cam curve generating method comprising:

a first step of acquiring a boundary condition of an application section to be a target of generation of the cam curve in a range in which a main shaft changes in position;

a second step of acquiring a division condition for dividing the application section into a plurality of sub-sections;

a third step of dividing the application section into the plurality of sub-sections that satisfy the division condition; and

a fourth step of generating the cam curve in the application section, the cam curve satisfying the boundary condition, wherein

each of the plurality of sub-sections is any one of types of an increasing sub-section in which acceleration of the driven shaft monotonously increases, a decreasing sub-section in which the acceleration of the driven shaft monotonously decreases, and a constant sub-section in which the acceleration of the driven shaft does not change,

the division condition includes a length and a type of each of the plurality of sub-sections,

the boundary condition includes a position of the driven shaft, speed of the driven shaft, and the acceleration of the driven shaft at each of a start and an end of the application section,

the fourth step is performed to generate the cam curve that allows a position of the driven shaft, speed of the driven shaft, and the acceleration of the driven shaft to be continuous at each of boundaries of the plurality of sub-sections, and

the method further comprises causing a servo control device to drive the motor based on the cam curve.

14 . The cam curve generating method according to claim 13 , wherein

the cam curve includes at least one sub-section of the increasing sub-section and the decreasing sub-section, and

the generating comprises generating the cam curve with a waveform of the acceleration of the driven shaft from a start to an end of the at least one sub-section, the waveform having a shape of a ¼ period part up to an apex of a sine wave.

15 . The cam curve generating method according to claim 13 , wherein

the cam curve includes at least one sub-section of the increasing sub-section and the decreasing sub-section, and

the generating comprises generating the cam curve with a waveform of the acceleration of the driven shaft from a start to an end of the at least one sub-section, the waveform having a shape of a half period part from the apex of the sine wave.

16 . The cam curve generating method according to claim 13 , wherein

the cam curve includes at least one sub-section of the increasing sub-section and the decreasing sub-section, and

the generating comprises generating the cam curve with a waveform of the acceleration of the driven shaft from a start to an end of the at least one sub-section, the waveform having a shape of a ¼ period part from the apex of the sine wave.

17 . The cam curve generating method according to claim 13 , wherein

the cam curve includes at least one sub-section of the increasing and the decreasing sub-section, and

the generating comprises generating the cam curve with a waveform of the acceleration of the driven shaft from a start to an end of the at least one sub-section, the waveform being defined by a linear polynomial of a position of the main shaft.

18 . The cam curve generating method according to claim 13 , wherein

the plurality of sub-sections are five sub-sections that include a first sub-section, a second sub-section, a third sub-section, a fourth sub-section, and a fifth sub-section, and that are sequentially continuous,

the first sub-section, the third sub-section, and the fifth sub-section are each the increasing sub-section or the decreasing sub-section, and

the second sub-section and the fourth sub-section are each the constant sub-section.

19 . The can curve generating method according to claim 18 , wherein the acceleration of the driven shaft in the second sub-section and the fourth sub-section has a value other than zero.

20 . The cam curve generating method according to claim 13 , wherein

the plurality of sub-sections are seven sub-sections that include a first sub-section, a second sub-section, a third sub-section, a fourth sub-section, a fifth sub-section, a sixth sub-section, and a seventh sub-section and that are sequentially continuous,

the first sub-section, the third sub-section, the fifth sub-section, and the seventh sub-section are each the increasing or the decreasing sub-section, and

the second sub-section, the fourth sub-section, and the sixth sub-section are each the constant sub-section.