Drive system, control device, control method, and program product for work machine

Abstract

A drive system of a work machine capable of suppressing the peripheral speed of the tip of an attachment. The excavator has: an attachment having a first movable member and a second movable member; a drive unit provided with a first electric actuator having a first output shaft that rotates the first movable member and a second electric actuator having a second output shaft that rotates the second movable member; and a control device that controls the drive unit. The control device performs: a first process (step S40) that calculates an upper limit rotational speed (W1U) of the first output shaft based on the relative position of the second movable member with respect to the first movable member; and a second process (step S80) that controls the first electric actuator so that the rotational speed of the first output shaft becomes lower than or equal to the upper limit rotational speed (W1U); in the first process, the longer the distance from the first output shaft to the tip on the opposite side of the attachment from the connection site of the first output shaft, the smaller the upper limit rotational speed (W1U) is made.

Description

Technical Field

[0001] This invention relates to the drive system of a work machinery, the control device of the work machinery, the control method of the work machinery, and the control program of the work machinery. Background Technology

[0002] Patent Document 1 discloses an excavator comprising a body, a boom, a stick, and a bucket. The boom is connected to the front end of the body. The boom is capable of rotating vertically relative to the body. The stick is connected to the top end of the boom. The stick is capable of rotating vertically relative to the boom. The bucket is connected to the top end of the stick. The bucket is capable of rotating vertically relative to the stick.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2001-254395

[0004] In technologies such as Patent Document 1, an electric actuator for outputting torque is arranged, for example, at a joint where the vehicle body connects to the boom. Furthermore, this electric actuator sometimes rotates the movable components such as the boom, stick, and bucket. With this configuration, the range of motion of each movable component becomes wider. Consequently, the distance from the output shaft of the electric actuator that rotates the boom to the top of the bucket may become quite long. When the boom is rotated in this state, due to the longer distance, the circumferential speed of the bucket top may be quite high. In this case, when the top of the bucket collides with the object being excavated or an obstacle, there is a problem of increased impact on the attachments. Summary of the Invention

[0005] The drive system for the work machinery used to solve the above-mentioned problems is suitable for work machinery with an attachment having a first movable member and a second movable member rotatably connected to the first movable member. The drive system for the work machinery includes: a drive unit having a first electric actuator having a first output shaft that rotates the first movable member and a second electric actuator having a second output shaft that rotates the second movable member; and a control device for controlling the drive unit. The control device performs: a first process of calculating a limit value for the rotational speed of the first output shaft based on the relative position of the second movable member relative to the first movable member; and a second process of controlling the first electric actuator to make the rotational speed of the first output shaft below the limit value; in the first process, if the distance from the first output shaft to the top end of the attachment on the opposite side of the connection point connected to the first output shaft is a first value, the limit value is reduced compared to a second value where the distance is less than the first value.

[0006] Based on the above structure, when the distance between the top of the first output shaft and the top of the accessory is relatively long, the limiting value of the rotational speed of the first output shaft is reduced. Therefore, even when the distance is relatively long, the circumferential speed of the top of the accessory can be suppressed.

[0007] In the drive system of the working machinery, when the upper limit of the circumferential speed with the top of the attachment as the target is taken as the upper limit circumferential speed, in the first process, the control device may also calculate the value corresponding to the quotient obtained by dividing the preset upper limit circumferential speed by the distance, and use it as the limit value.

[0008] In the drive system of the working machinery, the attachment has a third movable member rotatably connected to the second movable member, the drive unit has a third electric actuator, the third electric actuator has a third output shaft that rotates the third movable member, the top end of the attachment is the top end on the opposite side of the connection portion of the third movable member connected to the third output shaft, and in the first process, the control device may also calculate the limit value based on the relative position of the second movable member relative to the first movable member and the relative position of the third movable member relative to the second movable member.

[0009] In the drive system of the working machinery, when the limit value is set as the first limit value, in the first process, the control device may also calculate the first limit value, the limit value of the rotational speed of the second output shaft (i.e., the second limit value), and the limit value of the rotational speed of the third output shaft (i.e., the third limit value) based on the relative position of the second movable member relative to the first movable member and the relative position of the third movable member relative to the second movable member. In the second process, the control device may also control the first electric actuator to make the rotational speed of the first output shaft below the first limit value, control the second electric actuator to make the rotational speed of the second output shaft below the second limit value, and control the third electric actuator to make the rotational speed of the third output shaft below the third limit value. In the first process, when the distance between the first output shaft and the top end of the attachment is the first value, compared to the case where the distance is the second value, the first limit value, the second limit value, and the third limit value are reduced.

[0010] In the drive system of the operating machinery, the operating machinery can be construction machinery, the first movable component can be the boom, the second movable component can be the stick, and the third movable component can be the bucket.

[0011] A control device for a work machinery designed to solve the aforementioned problems is applicable to a work machinery comprising: an attachment having a first movable member and a second movable member rotatably connected to the first movable member; and a drive unit having a first electric actuator having a first output shaft for rotating the first movable member and a second electric actuator having a second output shaft for rotating the second movable member. The control device performs: a first process of calculating a limit value for the rotational speed of the first output shaft based on the relative position of the second movable member relative to the first movable member; and a second process of controlling the first electric actuator to make the rotational speed of the first output shaft below the limit value; in the first process, if the distance from the first output shaft to the top end of the connection portion of the attachment connected to the first output shaft is a first value, the limit value is reduced compared to a second value where the distance is less than the first value.

[0012] Based on the above structure, when the distance between the top of the first output shaft and the top of the accessory is relatively long, the limiting value of the rotational speed of the first output shaft is reduced. Therefore, even when the distance is relatively long, the circumferential speed of the top of the accessory can be suppressed.

[0013] A control method for a work machinery for solving the above-mentioned problems, the work machinery comprising: an attachment having a first movable member and a second movable member rotatably connected to the first movable member; and a drive unit having a first electric actuator having a first output shaft for rotating the first movable member and a second electric actuator having a second output shaft for rotating the second movable member. The control device applicable to the work machinery performs: a first process of calculating a limit value for the rotational speed of the first output shaft based on the relative position of the second movable member relative to the first movable member; and a second process of controlling the first electric actuator to make the rotational speed of the first output shaft below the limit value; in the first process, if the distance from the first output shaft to the top end of the connection portion of the attachment connected to the first output shaft is a first value, the limit value is reduced compared to a second value where the distance is less than the first value.

[0014] According to the above method, when the distance between the top of the first output shaft and the top of the accessory is long, the limit value of the rotational speed of the first output shaft is reduced. Therefore, even when the distance is long, the circumferential speed of the top of the accessory can be suppressed.

[0015] A control program for a work machinery designed to solve the aforementioned problems is provided. The work machinery includes: an attachment having a first movable member and a second movable member rotatably connected to the first movable member; and a drive unit comprising a first electric actuator having a first output shaft that rotates the first movable member, and a second electric actuator having a second output shaft that rotates the second movable member. The control program causes a control device suitable for the work machinery to perform: a first process of calculating a limit value for the rotational speed of the first output shaft based on the relative position of the second movable member relative to the first movable member; and a second process of controlling the first electric actuator to make the rotational speed of the first output shaft below the limit value; in the first process, if the distance from the first output shaft to the top end of the connection portion of the attachment connected to the first output shaft is a first value, the limit value is reduced compared to a second value where the distance is less than the first value.

[0016] According to the above procedure, when the distance between the top of the first output shaft and the top of the accessory is long, the control device reduces the limit value of the rotational speed of the first output shaft. Therefore, even when the distance is long, the circumferential speed of the top of the accessory can be suppressed.

[0017] The above technical concept can suppress the circumferential speed at the tip of the attachment. Attached Figure Description

[0018] Figure 1 This is a schematic side view of the excavator according to the first embodiment.

[0019] Figure 2 It is a schematic top view of an excavator.

[0020] Figure 3 It is a diagram showing the electrical structure and power transmission path of an excavator.

[0021] Figure 4 This is a flowchart illustrating the processing steps of the drive control in the first embodiment.

[0022] Figure 5 This is a flowchart illustrating the processing steps of the drive control in the second embodiment.

[0023] Figure 6 This is a side view used to illustrate the circumferential speed at the top of the bucket.

[0024] Explanation of reference numerals in the attached figures

[0025] 10…excavator

[0026] 20… Attachment

[0027] 21… boom

[0028] 23…fighting pole

[0029] 25… Bucket

[0030] 30…Drive Unit

[0031] 31…Actuator for boom

[0032] 32B…First drive shaft

[0033] 41…Actuator for the boom

[0034] 42B…Second drive shaft

[0035] 51… Bucket Actuator

[0036] 52B…Third drive shaft

[0037] 100… control device

[0038] 102A…Control Program

[0039] L…object distance

[0040] Vmax…the upper limit of circumferential velocity Detailed Implementation

[0041] <First Implementation>

[0042] The following description uses construction machinery as an example to illustrate the first embodiment of the drive system, control device, control method, and control program of the construction machinery. Furthermore, for simplicity and clarity, the structural components shown in the accompanying drawings may not necessarily be depicted to scale.

[0043] <Overall Structure>

[0044] like Figure 1 and Figure 2 As shown, the excavator 10, which is both a work machine and a construction machine, has a lower body 13 and an upper body 14. The upper body 14 is located on the opposite side of the ground G relative to the lower body 13. In this embodiment, when viewed from the lower body 13, the direction in which the upper body 14 is located is upward, and the opposite direction is downward. In addition, a specific direction orthogonal to upward is forward, and the opposite direction is backward. Furthermore, one direction orthogonal to both upward and forward is left, and the other is right. In addition, forward and backward are collectively referred to as the X direction. Left and right are collectively referred to as the Y direction. Upward and downward are collectively referred to as the Z direction.

[0045] like Figure 1As shown, the lower body 13 and the upper body 14 constitute the vehicle body 15. The lower body 13 is, for example, rectangular. The upper body 14 has a main frame 14A and a front frame 14B. The main frame 14A is, for example, rectangular. The interior of the main frame 14A is a hollow receiving space. The receiving space accommodates various equipment used to operate the excavator 10. The front frame 14B is located on the front side relative to the main frame 14A. The front frame 14B is located approximately at the center in the Y direction of the main frame 14A. The front frame 14B is fixed to the front of the main frame 14A. The front frame 14B is, for example, a smaller rectangular shape than the main frame 14A. The interior of the front frame 14B is hollow. Although not shown in the figure, the upper body 14 includes a cab for the operator. The upper body 14 is sometimes also referred to as the upper slewing body.

[0046] like Figure 1 and Figure 2 As shown, the excavator 10 has a slewing bearing 18. The slewing bearing 18 is located between the lower body 13 and the upper body 14. Figure 1 In the text, the vertical width of the slewing bearing 18 is exaggerated in the Z-direction. For example... Figure 2 As shown, the slewing bearing 18 has an annular inner ring 18A, an annular outer ring 18B, and a plurality of rolling elements. Figure 2 The rolling elements are not shown in the diagram. The outer diameter of the inner ring 18A is smaller than the inner diameter of the outer ring 18B. The axis of rotation 10J, which serves as the central axis of the inner ring 18A, is approximately aligned with the central axis of the outer ring 18B. The axis of rotation 10J extends along the vertical (Z) direction of the vehicle body 15. Figure 1 As shown, the axis of rotation 10J passes vertically through both the upper body 14 and the lower body 13. A plurality of rolling elements are located between the inner ring 18A and the outer ring 18B. These rolling elements rotatably support the inner ring 18A and the outer ring 18B. As a result, the outer ring 18B can rotate relative to the inner ring 18A about the axis of rotation 10J. The inner ring 18A is fixed to the lower body 13. The outer ring 18B is fixed to the main frame 14A of the upper body 14. That is, the upper body 14 can rotate relative to the lower body 13 about the axis of rotation 10J.

[0047] like Figure 2 As shown, the excavator 10 has a slewing actuator 71. The slewing actuator 71 includes an electric motor and a speed reducer that amplifies and outputs the torque of the electric motor. The slewing actuator 71 is housed in the main frame 14A of the upper body 14. The slewing actuator 71 rotates the upper body 14 relative to the lower body 13 by outputting torque.

[0048] like Figure 1 and Figure 2As shown, the excavator 10 has a pair of traveling gears 12. The pair of traveling gears 12 are located on the left and right sides of the lower body 13. Both sides of the pair of traveling gears 12 are connected to the lower body 13. Each pair of traveling gears 12 includes a track for travel and an actuation mechanism for circulating the track. The track is a ring-shaped belt. The track has openings on the left and right sides. The lower surface of the track contacts the ground G. The excavator 10 travels as the track circulates. Furthermore, the traveling gears 12 and the lower body 13 are sometimes collectively referred to as the lower traveling body.

[0049] like Figure 1 and Figure 2 As shown, the excavator 10 has a swing bracket 17. The swing bracket 17 is located on the front side relative to the main frame 14A of the upper body 14. The swing bracket 17 has a first swing wall 17A and a second swing wall 17B. The first swing wall 17A is located on the upper surface of the front frame 14B of the upper body 14. The first swing wall 17A is, for example, a circular plate. The second swing wall 17B protrudes upward from the upper surface of the first swing wall 17A. The second swing wall 17B is, for example, a rectangular plate.

[0050] like Figure 1 As shown, the excavator 10 has a swing actuator 61. The swing actuator 61 is housed in the front portion 14B of the frame of the upper body 14. The swing actuator 61 has an electric motor and a reducer that amplifies the torque of the electric motor and outputs it. The swing actuator 61 outputs torque centered on a fourth axis 61J extending vertically along the body 15. The fourth axis 61J is substantially parallel to the rotation axis 10J. The output shaft of the swing actuator 61 is connected to the first swing wall 17A. Furthermore, the swing actuator 61 causes the swing bracket 17 to rotate relative to the front portion 14B of the frame.

[0051] <Attachment>

[0052] like Figure 1 and Figure 2 As shown, the drive system of the excavator 10 has an accessory 20. The accessory 20 has a boom 21, a stick 23, and a bucket 25.

[0053] like Figure 1 and Figure 2 As shown, the boom 21 is located on the front side relative to the main frame 14A of the upper body 14. The boom 21 is a long, plate-like or columnar shape. For example, the boom 21 bends midway along its length. Figure 2 As shown, the first end 21A of the boom 21 along its length is parallel to the second swing wall 17B of the swing bracket 17 along the direction of the first axis 31J. The first axis 31J is a virtual axis that is approximately orthogonal to the fourth axis 61J. The first end 21A of the boom 21 is rotatably connected to the second swing wall 17B. Furthermore, the boom 21 corresponds to the first movable member.

[0054] like Figure 1 and Figure 2 As shown, the stick 23 extends from the second end 21B of the boom 21, opposite to the first end 21A. The stick 23 is either a long strip or a column. Figure 2 As shown, the first end 23A of the stick 23 along its length is parallel to the second end 21B of the boom 21 along the direction of the second axis 41J. The second axis 41J is a virtual axis that is substantially parallel to the first axis 31J. The first end 23A of the stick 23 is rotatably connected to the second end 21B of the boom 21. Furthermore, the stick 23 acts as a second movable member.

[0055] like Figure 1 and Figure 2 As shown, the bucket 25 is located near the second end 23B of the boom 23, on the side opposite to the first end 23A. The bucket 25 has a bucket body 26, a plurality of bucket teeth 27, and a bucket connecting wall 28. The bucket body 26 is box-shaped. That is, as shown... Figure 2 As shown, the bucket body 26 has an opening 26A. Bucket teeth 27 protrude from one side of the rectangular opening edge of the bucket body 26. A bucket connecting wall 28 protrudes from the outer wall of the bucket body 26, across the opening 26A, on the side opposite to the bucket teeth 27. Figure 2 As shown, the bucket connecting wall 28 is parallel to the second end 23B of the stick 23 along the direction of the third axis 51J. The third axis 51J is a virtual axis that is substantially parallel to both the first axis 31J and the second axis 41J. The bucket connecting wall 28 is rotatably connected to the second end 23B of the stick 23. Furthermore, the bucket 25 acts as a third movable member.

[0056] <Driver Unit>

[0057] like Figure 3 As shown, the excavator 10's drive system includes a drive unit 30. The drive unit 30 includes a boom actuator 31, a stick actuator 41, and a bucket actuator 51. Additionally, the excavator 10 includes a first inverter 35, a second inverter 45, a third inverter 55, and a battery 19. Although not shown in the figures, the first inverter 35, the second inverter 45, the third inverter 55, and the battery 19 are housed within the main frame 14A of the upper body 14. Furthermore, the boom actuator 31 corresponds to the first electric actuator. The stick actuator 41 corresponds to the second electric actuator. The bucket actuator 51 corresponds to the third electric actuator.

[0058] like Figure 2 As shown, the boom actuator 31 is located between the second swing wall 17B of the swing bracket 17 and the first end 21A of the boom 21. Figure 3As shown, the boom actuator 31 has a first electric motor 32 and a first reducer 33. The first electric motor 32 is a three-phase AC motor. The first electric motor 32 is electrically connected to the battery 19 via a first inverter 35. The first electric motor 32 has a housing 32A and a first drive shaft 32B. The housing 32A is mounted on the second swing wall 17B of the swing bracket 17. The first drive shaft 32B protrudes from the inside of the housing 32A to the outside. The first drive shaft 32B is cylindrical. The first drive shaft 32B is capable of rotating relative to the housing 32A about its own central axis, i.e., the first axis 31J. That is, the first drive shaft 32B outputs torque centered on the first axis 31J. The first drive shaft 32B is capable of rotating in both forward and reverse directions about the first axis 31J. Furthermore, as Figure 2 As shown, the first axis 31J passes through both the second swing wall 17B of the swing bracket 17 and the first end 21A of the boom 21.

[0059] like Figure 3 As shown, the first reducer 33 has a housing 33A, a reduction mechanism 33B, and an output member 33C. The housing 33A is mounted on the housing 32A of the first electric motor 32. The reduction mechanism 33B is located inside the housing 33A. Torque is input from the first drive shaft 32B of the first electric motor 32 to the reduction mechanism 33B. The reduction mechanism 33B amplifies the torque from the first drive shaft 32B at a predetermined ratio and outputs it to the output member 33C. The reduction mechanism 33B is, for example, an eccentric oscillating gear type or a planetary gear type. The output member 33C is cylindrical. The central axis of the output member 33C is substantially aligned with the first axis 31J. The output member 33C is rotatable relative to the housing 33A. The output member 33C rotates about the first axis 31J in accordance with the rotation of the first drive shaft 32B. The output member 33C is mounted on the first end 21A of the boom 21. That is, the output member 33C inputs torque centered on the first axis 31J to the boom 21. The boom 21 receives the torque and rotates about the first axis 31J. Through this series of torque transmissions, the first drive shaft 32B rotates the boom 21 via the reduction mechanism 33B and the output member 33C. The first drive shaft 32B is equivalent to the first output shaft.

[0060] like Figure 2 As shown, the stick actuator 41 is located between the second end 21B of the boom 21 and the first end 23A of the stick 23. Except for details such as dimensions, reduction ratio, and output, the structure of the stick actuator 41 is basically the same as that of the boom actuator 31. Therefore, the structure of the stick actuator 41 will be briefly described below.

[0061] like Figure 3As shown, the boom actuator 41 has a second electric motor 42 and a second reducer 43. The second electric motor 42 is electrically connected to the battery 19 via a second inverter 45. The housing 42A of the second electric motor 42 is mounted on the second end 21B of the boom 21. The second drive shaft 42B of the second electric motor 42 outputs torque centered on its own central axis, i.e., the second axis 41J. Figure 2 As shown, the second axis 41J passes through both the second end 21B of the boom 21 and the first end 23A of the stick 23. The output component 43C of the second reducer 43 is mounted on the first end 23A of the stick 23. Figure 3 As shown, the torque output from the second drive shaft 42B is input to the stick 23 via the reduction mechanism 43B and output member 43C of the second reducer 43. The stick 23 rotates together with the output member 43C around the second axis 41J. Thus, the second drive shaft 42B rotates the stick 23 via the reduction mechanism 43B and output member 43C. The second drive shaft 42B is equivalent to the second output shaft. Furthermore, the housing 43A of the second reducer 43 is mounted on the housing 42A of the second electric motor 42.

[0062] like Figure 2 As shown, the bucket actuator 51 is located between the second end 23B of the boom 23 and the bucket connecting wall 28 of the bucket 25. Except for details such as dimensions, reduction ratio, and output, the structure of the bucket actuator 51 is basically the same as that of the boom actuator 31. Therefore, the structure of the bucket actuator 51 will be briefly described below.

[0063] like Figure 3 As shown, the bucket actuator 51 has a third electric motor 52 and a third reducer 53. The third electric motor 52 is electrically connected to the battery 19 via a third inverter 55. The housing 52A of the third electric motor 52 is mounted on the second end 23B of the boom 23. The third drive shaft 52B of the third electric motor 52 outputs torque centered on its own central axis, i.e., the third axis 51J. Figure 2 As shown, the third axis 51J passes through both the second end 23B of the boom 23 and the bucket connecting wall 28. The output component 53C of the third reducer 53 is mounted on the bucket connecting wall 28. Figure 3 As shown, the torque output from the third drive shaft 52B is input to the bucket connecting wall 28 via the reduction mechanism 53B and output member 53C of the third reducer 53. The bucket connecting wall 28 rotates together with the output member 53C around the third axis 51J. Thus, the third drive shaft 52B rotates the bucket 25 via the reduction mechanism 53B and output member 53C. The third drive shaft 52B is equivalent to the third output shaft. Furthermore, the housing 53A of the third reducer 53 is mounted on the housing 52A of the third electric motor 52.

[0064] <Sensors>

[0065] like Figure 3 As shown, the drive system of the excavator 10 includes a first angle sensor 38, a second angle sensor 48, and a third angle sensor 58. The first angle sensor 38 detects the angular position 38S of the first drive shaft 32B of the first electric motor 32. The second angle sensor 48 detects the angular position 48S of the second drive shaft 42B of the second electric motor 42. The third angle sensor 58 detects the angular position 58S of the third drive shaft 52B of the third electric motor 52. The angular positions detected by each angle sensor 38, 48, and 58 are defined with a preset reference position of "0 degrees" and expressed in a range of "0 degrees to 360 degrees". That is, each angular position represents the absolute angle of the drive shaft of each electric motor 32, 42, and 52. Each angle sensor 38, 48, and 58 sends a signal corresponding to the information it detects to the control device 100, which will be described later.

[0066] Although the illustrations are omitted, the excavator 10's drive system, in addition to the aforementioned sensors, includes various sensors necessary for the excavator 10 to operate. For example, the excavator 10's drive system includes sensors that detect the current flowing through each of the electric motors 32, 42, and 52, and sensors that detect the temperature of the battery 19. Furthermore, the excavator 10's drive system includes various operating devices 90 operated by the operator. In the accompanying drawings, these various operating devices 90 are shown in summary. These operating devices 90 are located in the operator's cab. Each operating device 90 sends signals 90S corresponding to the operator's actions to the control device 100, which will be described later.

[0067] <Control Device>

[0068] like Figure 3 As shown, the drive system of the excavator 10 includes a control unit 100. The control unit 100 is a computer with processing circuitry. The processing circuitry includes a CPU 101 and a memory 102. The memory 102 includes three types: RAM, ROM, and electrically erasable non-volatile memory. In this embodiment, these three types are collectively referred to as memory 102. The memory 102 pre-stores various control programs 102A that describe the processes to be executed by the CPU 101. The memory 102 pre-stores various data 102B required by the CPU 101 to execute the control programs 102A. The processing circuitry includes communication circuitry for wireless communication with external devices.

[0069] CPU 101 can receive an angular position 38S transmitted from the first angle sensor 38. CPU 101 can receive an angular position 48S transmitted from the second angle sensor 48. CPU 101 can receive an angular position 58S transmitted from the third angle sensor 58. CPU 101 can receive a signal 90S transmitted from the operating device 90.

[0070] The CPU 101 converts the angle position 38S received from the first angle sensor 38 from the actual angle of the first electric motor 32 into a first angle position 21S related to the boom 21. The first angle position 21S is the angle position of the boom 21 from a preset first position. The first position and the first angle position 21S are defined in a specific top-down view of the excavator 10 viewed along the first axis 31J. An example of the first position is an angle position in which both the first end 21A and the second end 21B of the boom 21 are positioned on a virtual straight line orthogonal to both the first axis 31J and the fourth axis 61J. In this example of the first position, the second end 21B of the boom 21 is positioned on the side opposite to the vehicle body 15 across the first axis 31J. The first angle position 21S represents the relative position of the boom 21 with respect to the swing bracket 17 or the vehicle body 15. Furthermore, the first angle sensor 38, which detects the actual angle of the first electric motor 32, essentially detects the first angle position 21S.

[0071] The CPU 101 converts the angle position 48S received from the second angle sensor 48 from the actual angle of the second electric motor 42 into a second angle position 23S related to the stick 23. The second angle position 23S is the angular position of the stick 23 from a predetermined second position. The second position and the second angle position 23S are defined in the specific top-down view described above. An example of the second position is the angular position where the first end 23A and the second end 23B of the stick 23 are both positioned on a virtual straight line passing through the first axis 31J and the second axis 41J. In this example of the second position, the second end 23B of the stick 23 is positioned on the opposite side of the first axis 31J, separated by the second axis 41J. The second angle position 23S represents the relative position of the stick 23 with respect to the boom 21. Furthermore, the second angle sensor 48, which detects the actual angle of the second electric motor 42, essentially detects the second angle position 23S.

[0072] The CPU 101 converts the angle position 58S received from the third angle sensor 58 from the actual angle of the third electric motor 52 into a third angle position 25S related to the bucket 25. The third angle position 25S is the angle position of the bucket 25 from a preset third position. The third position and the third angle position 25S are defined in the specific top-down view described above. An example of the third position is the angle position where the top of the bucket teeth 27 of the bucket 25 is positioned on a virtual straight line passing through the second axis 41J and the third axis 51J. In this example of the third position, the bucket teeth 27 of the bucket 25 are positioned on the opposite side of the second axis 41J, separated by the third axis 51J. The third angle position 25S represents the relative position of the bucket 25 with respect to the stick 23. Furthermore, the third angle sensor 58, which detects the actual angle of the third electric motor 52, essentially detects the third angle position 25S.

[0073] Each time the CPU 101 receives an angular position 38S from the first angle sensor 38, it calculates a first angular position 21S. That is, the CPU 101 repeatedly calculates the first angular position 21S. The CPU 101's calculation of the first angular position 21S is equivalent to the CPU 101 acquiring the first angular position 21S. Similarly, the CPU 101 repeatedly calculates the second angular position 23S and the third angular position 25S. Likewise, the CPU 101's calculation of these angular positions 23S and 25S is equivalent to the CPU 101 acquiring these respective angular positions 23S and 25S.

[0074] <Restricted Content>

[0075] CPU 101 controls drive unit 30. Specifically, CPU 101 controls the first electric motor 32 of boom actuator 31, the second electric motor 42 of stick actuator 41, and the third electric motor 52 of bucket actuator 51. Furthermore, while controlling each electric motor 32, 42, and 52, CPU 101 also substantially controls the inverters 35, 45, and 55 connected to each electric motor 32, 42, and 52.

[0076] When controlling each of the electric motors 32, 42, and 52, the CPU 101 determines a target value for the rotational speed of each drive shaft 32B, 42B, and 52B. Furthermore, it controls each electric motor 32, 42, and 52 in a manner consistent with the target value and the actual rotational speed. In this embodiment, the rotational speed of the drive shafts 32B, 42B, and 52B of each electric motor 32, 42, and 52 is described using rotational speed. For example, if it is the rotational speed of the first drive shaft 32B of the first electric motor 32, then the rotational speed of the first drive shaft 32B is processed. Rotational speed is the number of rotations of the drive shaft per unit time.

[0077] CPU 101 is capable of performing drive control. In this embodiment, the drive control is directed at the first electric motor 32. In drive control, CPU 101 rotates the boom 21 by driving the first electric motor 32. Furthermore, in this embodiment, the drive control is performed while the angular positions of the stick 23 and the bucket 25 are kept constant. The following describes a series of processes performed by CPU 101 in drive control.

[0078] For example, when the CPU 101 receives a signal 90S from the operating device 90 instructing the boom 21 to rotate, it begins drive control. Figure 4 As shown, when CPU101 starts driving control, it first performs step S10.

[0079] In step S10, CPU 101 acquires the latest first reference speed W1. The first reference speed W1 is an instruction value indicating the speed of the first electric motor 32. The first reference speed W1 is calculated in a reference value calculation process that is different from the current drive control process. For example, if the operator operates the operating device 90, i.e., the joystick, CPU 101 calculates the first reference speed W1 based on the amount of joystick operation in the reference value calculation process. At this time, CPU 101 calculates the first reference speed W1 as a value less than the limit speed. The limit speed is the physical limit value of the speed of the first drive shaft 32B determined by the specifications of the first electric motor 32. After processing in step S10, CPU 101 causes the process to proceed to step S20.

[0080] In step S20, CPU 101 acquires the latest second angle position 23S and the latest third angle position 25S. Afterward, CPU 101 proceeds to step S30.

[0081] In step S30, CPU101 calculates the object distance L. For example... Figure 6 As shown, the object distance L is the distance from the first axis 31J to the tip of the bucket tooth 27 of the bucket 25 in a specific top view. Here, the tip of the bucket tooth 27 of the bucket 25 is the tip on the opposite side of the connection portion of the bucket 25 connected to the third drive shaft 52B. The tip of the bucket tooth 27 of the bucket 25 can also be described as a specific part of the bucket 25. Furthermore, the tip of the bucket tooth 27 of the bucket 25 is the tip on the opposite side of the first end 21A of the boom 21 in the attachment 20. Moreover, the first end 21A of the boom 21 is the part of the attachment 20 connected to the first drive shaft 32B. That is, the object distance L is equivalent to the distance from the first drive shaft 32B to the tip on the opposite side of the connection portion of the attachment 20 connected to the first drive shaft 32B in a specific top view. The object distance L is an indicator representing the positional relationship between the first drive shaft 32B and even the first axis 31J and the tip of the bucket tooth 27 of the bucket 25. In step S30, it can be said that CPU 101 calculates the object distance L and estimates the above positional relationship. The method for calculating the object distance L is explained below.

[0082] As information used by CPU 101 to calculate object distance L, memory 102 pre-stores distance information. The distance information represents the relationship between the second angular position 23S and the third angular position 25S and the object distance L. Specifically, the distance information represents the object distance L under various combinations of the second angular position 23S and the third angular position 25S. The distance information may be composed of, for example, tables, graphs, or formulas. Whenever calculating the object distance L, CPU 101 calculates the object distance L by applying the latest second angular position 23S and the latest third angular position 25S obtained in step S20 to the distance information. Thus, in step S30, CPU 101 calculates the object distance L based on the second angular position 23S and the third angular position 25S. Figure 4 As shown, when the object distance L is calculated, CPU101 causes the processing to proceed to step S40.

[0083] In step S40, CPU 101 calculates the upper limit speed W1U. The upper limit speed W1U is a limit value for the speed of the first drive shaft 32B. Specifically, the upper limit speed W1U is a limit value that specifies the upper limit of the speed allowed by the first drive shaft 32B. The upper limit speed W1U is a first limit value. In this step S40, CPU 101 considers the object distance L calculated in step S30 and converts the upper limit circumferential speed Vmax stored in memory 102 into speed. Specifically, first, CPU 101 calculates the quotient obtained by dividing the upper limit circumferential speed Vmax by the object distance L. Then, CPU 101 calculates the value obtained by dividing the quotient by a predetermined coefficient as the upper limit speed W1U. The predetermined coefficient is a constant that takes into account unit conversion and pi, etc. For example, the unit time is set to "1 minute" and the length unit is set to "m" to make the units consistent, just like circumferential speed [m / minute], object distance L [m], and speed [ / minute]. In this case, the predetermined coefficient is twice pi. Not limited to this example, the specified coefficient can also include a correction value to adjust the magnitude of the upper limit rotational speed W1U. In this case, the upper limit rotational speed W1U is the value corresponding to the quotient obtained by dividing the upper limit circumferential speed Vmax by the object distance L.

[0084] The upper limit of the circumferential speed Vmax is the upper limit value of the circumferential speed V preset with the tip of the bucket tooth 27 of the bucket 25 as the target. Here, as Figure 6 As shown, a virtual circle centered on the first axis 31J and with a radius equal to the distance L from the object, viewed from a specific top view, is called the specific virtual circle Q. The circumferential velocity V at the tip of the bucket teeth 27 of the bucket 25 is the velocity along the tangential direction of the specific virtual circle Q. Furthermore, the upper limit circumferential velocity Vmax can be considered as the maximum value of the circumferential velocity V that can protect the attachment 20 when the tip of the bucket teeth 27 of the bucket 25 collides with the excavated object or obstacle. The upper limit circumferential velocity Vmax is a value preset through experiments or simulations.

[0085] As described above, in step S40, CPU 101 calculates the upper limit rotational speed W1U based on the upper limit circumferential speed Vmax and the object distance L calculated in step S30. Here, the upper limit rotational speed W1U is the reciprocal of the object distance L. Therefore, when the object has the same upper limit circumferential speed Vmax, the longer the object distance L, the smaller the upper limit rotational speed W1U calculated by CPU 101. Furthermore, the object distance L is a value calculated based on the second angular position 23S and the third angular position 25S. That is, through steps S30 and S40, CPU 101 calculates the upper limit rotational speed W1U based on the second angular position 23S and the third angular position 25S. These steps S30 and S40 constitute the first process. Figure 4 As shown, when the processing of step S40 is executed, CPU101 causes the processing to proceed to step S50.

[0086] In step S50, CPU 101 determines whether the first reference speed W1 obtained in step S10 is below the upper limit speed W1U calculated in step S40. If the first reference speed W1 is below the upper limit speed W1U (step S50: "Yes"), CPU 101 causes the process to proceed to step S60. In this case, in step S60, CPU 101 sets the first reference speed W1 as the target speed W1F of the first drive shaft 32B.

[0087] On the other hand, in step S50, if the first reference speed W1 is greater than the upper limit speed W1U (step S50: "No"), CPU 101 causes the process to proceed to step S70. In this case, in step S70, CPU 101 sets the upper limit speed W1U as the target speed W1F of the first drive shaft 32B. When calculating the target speed W1F, CPU 101 causes the process to proceed to step S80. Thus, through steps S50, S60, and S70, CPU 101 sets the smaller value between the first reference speed W1 and the upper limit speed W1U as the target speed W1F of the first drive shaft 32B.

[0088] In step S80, CPU 101 controls the first electric motor 32 based on the target rotational speed W1F calculated in step S60 or S70. Specifically, CPU 101 controls the first electric motor 32 to make the target rotational speed W1F consistent with the actual rotational speed of the first drive shaft 32B. Here, while considering the processing of steps S50, S60, and S70, the target rotational speed W1F becomes a value below the upper limit rotational speed W1U. Therefore, in step S80, CPU 101 controls the first electric motor 32 to make the rotational speed of the first drive shaft 32B below the upper limit rotational speed W1U. CPU 101 continues the processing of step S80 until the termination condition is met. One example of the termination condition is that a pre-set first control period has elapsed since the start of step S80. The first control period is, for example, a few seconds. The first control period is any period suitable for continuous rotation of the boom 21 in various operations such as digging. Another example of the termination condition is receiving a signal 90S from the operating device 90 indicating that the rotation of the boom 21 has stopped. When the termination condition is met, CPU101 terminates drive control. The processing in step S80 is the second processing.

[0089] <Function of the First Embodiment>

[0090] like Figure 6 As shown, the object distance L is the radius of rotation when the stick 23 and bucket 25 rotate together with the boom 21, with the first drive shaft 32B as the center of rotation. Furthermore, as the object distance L increases, the circumferential velocity V of the tip of the bucket tooth 27 increases relative to the same rotational speed of the first drive shaft 32B. Simultaneously, the kinetic energy near the tip of the bucket tooth 27 increases. In this case, when the tip of the bucket tooth 27 collides with the object being excavated or an obstacle, the impact applied to the attachment 20 is greater due to the larger energy involved.

[0091] Therefore, in drive control, the longer the rotation radius, i.e., the object distance L, the smaller the upper limit speed W1U of the CPU 101 (step S40). Then, the CPU 101 controls the first electric motor 32 to make the speed of the first drive shaft 32B below the upper limit speed W1U (steps S50 to S80). In this way, by suppressing the speed of the first drive shaft 32B according to the object distance L, the CPU 101 can keep the circumferential speed V of the top of the bucket teeth 27 of the bucket 25 below the upper limit circumferential speed Vmax, regardless of the size of the object distance L.

[0092] <Effects of the First Implementation>

[0093] (1-1) As described in the section on the function of the embodiment, the CPU 101 of this embodiment can suppress the circumferential velocity V at the tip of the bucket teeth 27 of the bucket 25 regardless of the object distance L. Therefore, when the bucket 25 collides with the object being excavated or an obstacle, the CPU 101 can mitigate the impact applied to the attachment 20.

[0094] (1-2) In the first process of step S40, CPU101 converts the upper limit circumferential speed Vmax into a rotational speed by dividing the object distance L. By limiting the rotational speed of the first drive shaft 32B to be below this converted value, i.e., the upper limit rotational speed W1U, CPU101 can reliably suppress the circumferential speed V at the tip of the bucket tooth 27 to be below the upper limit circumferential speed Vmax.

[0095] (1-3) The rotation radius of the bucket 25, i.e., the object distance L, varies according to the posture of the attachment 20. In the first processing of step S30, the CPU 101 of this embodiment calculates the object distance L based on the angular positions of each movable member reflecting the posture of the attachment 20. As a result, the CPU 101 can calculate the object distance L and even the upper limit rotational speed W1U corresponding to the posture of the attachment 20 with high accuracy.

[0096] (1-4) In the excavator 10, there are many operations in which the attachment 20 collides with objects such as sand and soil. Therefore, applying the drive control of this embodiment to the excavator 10 is particularly effective in increasing the chance of mitigating the impact applied to the attachment 20 using the technology of this embodiment.

[0097] <Second Implementation>

[0098] The following describes a second embodiment of the drive system, control device, control method, and control program for the working machinery. In this embodiment, the drive control differs from that of the first embodiment. Apart from this, the second embodiment is essentially the same as the first embodiment. Hereinafter, the second embodiment will primarily describe the parts that differ from the first embodiment; parts that overlap with the first embodiment will be appropriately omitted or simplified.

[0099] The drive control in this embodiment targets the first electric motor 32, the second electric motor 42, and the third electric motor 52. In the drive control, the CPU 101 performs the rotational drive of the boom 21 by the first electric motor 32, the rotational drive of the stick 23 by the second electric motor 42, and the rotational drive of the bucket 25 by the third electric motor 52 in parallel. Furthermore, the drive control in this embodiment is an extension of the drive control in the first embodiment to three electric motors, and the basic concept is the same as the drive control in the first embodiment. Therefore, the drive control will be described in a simplified manner below.

[0100] For example, when the CPU 101 receives a signal 90S from the operating device 90 instructing the boom 21, stick 23, and bucket 25 to rotate, it begins drive control. Figure 5 As shown, when drive control begins, CPU101 first performs step S110.

[0101] In step S110, CPU 101 acquires the latest first reference speed W1, the latest second reference speed W2, and the latest third reference speed W3. Each reference speed W1, W2, and W3 is calculated in the reference value calculation process based on the operator's operation of the operating equipment 90. Similar to the first reference speed W1, the second reference speed W2 and the third reference speed W3 are respectively less than the physical limits of the speeds of their respective drive shafts 42B and 52B. Upon acquiring each reference speed W1, W2, and W3, CPU 101 proceeds to step S120.

[0102] In step S120, CPU 101 acquires the latest first angle position 21S, the latest second angle position 23S, and the latest third angle position 25S. Then, CPU 101 causes the process to proceed to step S130.

[0103] In step S130, similarly to step S30 in the first embodiment, CPU 101 calculates the object distance L. After the processing in step S130, CPU 101 causes the processing to proceed to step S140.

[0104] In step S140, CPU 101 calculates a first upper limit speed W1U, a second upper limit speed W2U, and a third upper limit speed W3U. The first upper limit speed W1U is a limit value specifying the upper limit of the speed allowed by the first drive shaft 32B. The second upper limit speed W2U is a limit value specifying the upper limit of the speed allowed by the second drive shaft 42B. The third upper limit speed W3U is a limit value specifying the upper limit of the speed allowed by the third drive shaft 52B. The first upper limit speed W1U is the first limit value. The second upper limit speed W2U is the second limit value. The third upper limit speed W3U is the third limit value. In step S140, the longer the object distance L, the smaller the first upper limit speed W1U, the second upper limit speed W2U, and the third upper limit speed W3U are. CPU 101 appropriately sets the first upper limit speed W1U, the second upper limit speed W2U, and the third upper limit speed W3U using formulas or other methods established based on experiments or simulations. At this point, in the subsequent step S160, when controlling each of the electric motors 32, 42, and 52, the CPU 101 makes the circumferential speed V at the tip of the bucket teeth 27 of the bucket 25 lower than the upper limit circumferential speed Vmax. For example, the CPU 101 can also calculate the first upper limit speed W1U in the same way as step S40 of the first embodiment. When calculating each upper limit speed W1U, W2U, and W3U, the CPU 101 can also adjust the respective upper limit speed W1U, W2U, and W3U based on the respective angle positions 21S, 23S, and 25S obtained in step S110. When each upper limit speed W1U, W2U, and W3U is calculated, the CPU 101 causes the process to proceed to step S150. Furthermore, in steps S130 and S140, the CPU 101 calculates each upper limit speed W1U, W2U, and W3U based on the object distance L calculated from the second angle position 23S and the third angle position 25S. The processing in steps S130 and S140 is the first processing.

[0105] In step S150, CPU 101 calculates a first target speed W1F, a second target speed W2F, and a third target speed W3F. The first target speed W1F is the target speed of the first drive shaft 32B. The second target speed W2F is the target speed of the second drive shaft 42B. The third target speed W3F is the target speed of the third drive shaft 52B. CPU 101 calculates each target speed W1F, W2F, and W3F in the same manner as steps S50 to S70 of the first embodiment. That is, CPU 101 sets the smaller of the first reference speed W1 and the first upper limit speed W1U as the first target speed W1F. CPU 101 sets the smaller of the second reference speed W2 and the second upper limit speed W2U as the second target speed W2F. CPU 101 sets the smaller of the third reference speed W3 and the third upper limit speed W3U as the third target speed W3F. Furthermore, when the reference speed and the upper limit speed are the same, CPU 101 only needs to use the reference speed as the target speed. Thus, by setting the target speeds W1F, W2F, and W3F, each target speed W1F, W2F, and W3F becomes below its respective upper limit speed W1U, W2U, and W3U. When each target speed W1F, W2F, and W3F is calculated, CPU 101 causes the processing to proceed to step S160.

[0106] In step S160, CPU 101 controls the respective electric motors 32, 42, and 52 based on each target speed W1F, W2F, and W3F. For example, if it is the second electric motor 42, CPU 101 controls the second electric motor 42 in such a way that the speed of the second drive shaft 42B is consistent with the second target speed W2F. The same applies to the other two electric motors 32 and 52. Taking into account the target speeds W1F, W2F, and W3F calculated in step S150, CPU 101 controls each electric motor 32, 42, and 52 as follows: CPU 101 controls the first electric motor 32 so that the speed of the first drive shaft 32B is below the first upper limit speed W1U. CPU 101 controls the second electric motor 42 so that the speed of the second drive shaft 42B is below the second upper limit speed W2U. CPU 101 controls the third electric motor 52 so that the speed of the third drive shaft 52B is below the third upper limit speed W3U. CPU 101 continues the processing of step S160 during the pre-set second control period. The second control period is typically a few seconds. After the second control period has elapsed since the start of step S160, CPU 101 terminates the processing of step S160. The processing of step S160 is the second processing.

[0107] When the processing of step S160 ends, CPU 101 returns to the processing of step S110. Then, CPU 101 performs the processing after step S110 again. In this way, CPU 101 repeats the processing of steps S110 to S160. When the termination condition is met during this repetition, CPU 101 terminates the drive control. An example of the termination condition is receiving a signal 90S from the operating device 90 indicating that the rotation of the boom 21, stick 23, and bucket 25 has stopped.

[0108] <Function and Effects of the Second Embodiment>

[0109] The structure of this embodiment has the same effect as (1-1) to (1-4). In addition, the structure of this embodiment also has the following effect.

[0110] (2-1) In this embodiment, the CPU 101 drives three drive shafts 32B, 42B, and 52B to make the boom 21, stick 23, and bucket 25 move in parallel. In this case, the object distance L changes sequentially according to the changes in the positions of the boom 21, stick 23, and bucket 25. In this case, the longer the object distance L, the smaller the first upper limit speed W1U of the first drive shaft 32B, the second upper limit speed W2U of the second drive shaft 42B, and the third upper limit speed W3U of the third drive shaft 52B set by the CPU 101. In this way, by setting each upper limit speed W1U, W2U, and W3U in coordination with the change in object distance L, the circumferential speed V of the tip of the bucket teeth 27 can be suppressed even when the trajectory of the tip of the bucket teeth 27 changes freely.

[0111] <Variation Example>

[0112] The above embodiments can be implemented with the following modifications. The above embodiments and the following variations can be combined and implemented with each other within the scope of technical non-contradiction.

[0113] The upper limit circumferential speed Vmax is not limited to the examples of the above embodiments. Depending on the operation of the excavator 10, the circumferential speed V at the tip of the bucket teeth 27 may sometimes be limited for purposes other than the protective attachment 20. There are also cases where an appropriate value is set as the upper limit circumferential speed Vmax as needed. Furthermore, the upper limit circumferential speed Vmax is not limited to one value; multiple values ​​may be preset. That is, the memory 102 may, for example, store multiple upper limit circumferential speeds Vmax in conjunction with various operations performed by the excavator 10. In this case, in step S40 of the first embodiment, the CPU 101 only needs to select one of these multiple upper limit circumferential speeds Vmax to calculate the upper limit rotational speed W1U.

[0114] The method for calculating the first limit value is not limited to the examples of the above embodiments. The first limit value only needs to be smaller when the object distance L is the first value, compared to the case where the object distance L is the second value. The second value is smaller than the first value. It is not necessary for the first limit value to be smaller as the object distance L increases. For example, the first limit value can also vary in stages relative to the object distance L. It is not necessary to use the upper limit circumferential velocity Vmax of the tip of the bucket tooth 27 when calculating the first limit value. An appropriate calculation method can be used to suppress the circumferential velocity V at the tip of the bucket tooth 27 regardless of the length of the object distance L. In this case, the first limit value only needs to be calculated based at least on the information of the second angular position 23S.

[0115] Regarding the second embodiment, the calculation method for the second and third limit values ​​is not limited to the examples described above. Similar to the first limit value, it is not necessary to calculate the second and third limit values ​​in such a way that the value decreases as the object distance L increases. Furthermore, at least one of the second and third limit values ​​can be eliminated. For example, by strictly setting the first limit value, the circumferential velocity V at the tip of the bucket tooth 27 can be suppressed even if the second and third limit values ​​are eliminated.

[0116] The electric motor used as the driving object in drive control is not limited to the examples of the above embodiments. For example, in drive control, the first electric motor 32 and the second electric motor 42 out of the three electric motors 32, 42, and 52 can also be driven. This allows the boom 21 and stick 23 to rotate. In this case, when both the first and second limit values ​​are set, it is suitable to suppress the circumferential speed V at the tip of the bucket teeth 27. Similarly to the second embodiment, both the first and second limit values ​​are calculated in such a way that the longer the object distance L, the smaller the value.

[0117] In the drive control, the second electric motor 42 and the third electric motor 52 out of the three electric motors 32, 42, and 52 can also be driven. This allows the stick 23 and the bucket 25 to rotate. In this case, the stick 23 constitutes the first movable member, and the stick actuator 41 constitutes the first electric actuator. The bucket 25 constitutes the second movable member, and the bucket actuator 51 constitutes the second electric actuator. In such a structure, for example, the object distance can be set to the distance from the second axis 41J to the top of the bucket tooth 27 of the bucket 25 when viewed from a specific top angle. Furthermore, this object distance is calculated based on the third angular position 25S, and the limit value of the second drive shaft 42B is calculated based on the object distance L.

[0118] As described in the above-described modified examples, the components treated as the first movable member and the components treated as the second movable member in Annex 20 can be appropriately changed. Depending on which component is treated as the first movable member, the actuator constituting the first electric actuator can be changed. When changing the first movable member from the example of the above embodiment, the first electric actuator only needs to be an actuator that rotates the first movable member. Similarly, depending on which component is treated as the second movable member, the actuator constituting the second electric actuator can be changed. The second electric actuator only needs to be an actuator that rotates the second movable member. Furthermore, when a movable member different from the first movable member is connected to the second movable member, it is sufficient to treat that movable member as a third movable member. Moreover, it is sufficient to treat the actuator that rotates the third movable member as a third electric actuator.

[0119] The rotational speed of each drive shaft 32B, 42B, and 52B can also be represented by the angular velocity, which is the change in the angular position of the drive shaft per unit time. In this case, the angular velocity can be used to represent each limit value.

[0120] The overall structure of Annex 20 is not limited to the examples of the above embodiments. Annex 20 can also be constructed using appropriate movable members depending on the operation. For example, a member other than bucket 25 can be used as the third movable member. Depending on the third movable member used, the top end of the connection portion of the third movable member opposite to the connection portion connected to the third output shaft can be changed. Furthermore, the top end of the connection portion of Annex 20 opposite to the connection portion connected to the first output shaft can be changed. The third movable member can also be omitted. Annex 20 only needs to have two or more movable members. In addition, if the third movable member is omitted, the top end of the connection portion of Annex 20 opposite to the connection portion connected to the first output shaft is constituted by the second movable member.

[0121] Alternatively, the first output component 33C of the first reducer 33 can be treated as the first output shaft, replacing the first drive shaft 32B of the first electric motor 32. In this case, considering only the reduction ratio of the first reducer 33, the values ​​of parameters such as the reference speed, upper limit speed, and target speed set with the first drive shaft 32B as the target can be converted into the values ​​corresponding to the first output component 33C. Similarly, the output component 43C of the second reducer 43 can be treated as the second output shaft, replacing the second drive shaft 42B of the second electric motor 42. The output component 53C of the third reducer 53 can also be treated as the third output shaft, replacing the third drive shaft 52B of the third electric motor 52.

[0122] The shapes of the first drive shaft 32B of the first electric motor 32 and the output member 33C of the first reducer 33 are not limited to cylindrical shapes. The first drive shaft 32B and the output member 33C can be any shape capable of transmitting torque to the mating member. Similarly, the shapes of the second drive shaft 42B of the second electric motor 42 and the output member 43C of the second reducer 43 are not limited to cylindrical shapes. The shapes of the third drive shaft 52B of the third electric motor 52 and the output member 53C of the third reducer 53 are also the same.

[0123] The structure of the boom actuator 31 is not limited to the examples of the above embodiments. The boom actuator 31 can be any actuator that includes an electric motor and is capable of driving the rotation of the boom 21. For example, the first reducer 33 can be omitted from the boom actuator 31. Furthermore, the boom actuator 31 is not limited to an actuator that outputs torque coaxial with the drive shaft of the electric motor to the outside.

[0124] The mounting method of the boom actuator 31 relative to the boom 21 and the swing bracket 17 is not limited to the examples of the above embodiments. The mounting method is not limited as long as the boom 21 can be rotated by the boom actuator 31. For example, the orientation of the boom actuator 31 between the second swing wall 17B of the swing bracket 17 and the boom 21 can be reversed. That is, the boom actuator 31 can be mounted on the boom 21 and the swing bracket 17 with the first reducer 33 located near the second swing wall 17B and the first electric motor 32 located near the boom 21.

[0125] Similar to the aforementioned variations of the boom actuator 31, the structure and installation method of the stick actuator 41 are not limited to the examples of the above embodiments. The stick actuator 41 only needs to include an electric motor and be able to drive the rotation of the stick 23.

[0126] Similar to the aforementioned variations of the boom actuator 31, the structure and installation method of the bucket actuator 51 are not limited to the examples of the above embodiments. The bucket actuator 51 only needs to include an electric motor and be able to drive the rotation of the bucket 25.

[0127] The structure of the upper body 14 is not limited to the examples of the embodiments described above. For example, the driver's cab may be omitted from the upper body 14. The shapes of the main frame 14A and the front frame 14B may also be other than cuboid shapes. The upper body 14 can be configured to perform the required functions, such as accommodating various equipment.

[0128] As in the aforementioned variation, the operating equipment 90 can also be removed from the upper body 14 in accordance with the removal of the cab from the upper body 14. At the same time, various signals instructing the excavator 10 to be transmitted from external devices on the vehicle body 15 to the control device 100 via wireless communication.

[0129] The structural components included in the drive system of excavator 10 are not limited to the examples of the above embodiments. For example, Annex 20 may be treated as a structural component not included in the drive system. The drive system only needs to include drive unit 30 and control device 100.

[0130] The overall structure of the vehicle body 15 and even the excavator 10 is not limited to the examples of the above embodiments. For example, as in the modified examples described above, the overall shape of the vehicle body 15 can be changed by changing the shape of the upper body 14. For example, it is sufficient as long as the excavator 10 is configured to perform the required operations such as digging.

[0131] The work machinery is not limited to excavator 10. The work machinery can also be construction machinery other than excavator 10. Furthermore, the work machinery is not limited to construction machinery. Examples of work machinery other than construction machinery include machinery used in forestry, gravel crushing, industrial waste treatment, and agriculture.

[0132] The processing circuit of the control device 100 can adopt any one of the following structures (a) to (c).

[0133] (a) The processing circuit has one or more processors that perform various processes according to a computer program. The processor includes a CPU 101, a memory 102 such as RAM and ROM. The memory 102 stores program code or instructions configured to cause the CPU 101 to perform processes. The memory 102, i.e., computer-readable medium, includes any usable medium that can be accessed by a general-purpose or special-purpose computer.

[0134] (b) The processing circuit has one or more dedicated hardware circuits that perform various processes. As dedicated hardware circuits, they can include, for example, application-specific integrated circuits, such as ASICs or FPGAs.

[0135] (c) The processing circuit has a processor that performs a portion of the various processes according to a computer program, and dedicated hardware circuitry that performs the remaining processes in the various processes.

[0136] In the above embodiments, a component composed of a plurality of objects can integrate the plurality of objects into one unit, and conversely, a component composed of a single object can be divided into a plurality of objects. Regardless of whether they are integrated or not, the configuration is sufficient to achieve the purpose of the invention.

[0137] In the above embodiments, for a component where multiple functions are distributed, some or all of the multiple functions may be centrally distributed; conversely, for a component where multiple functions are centrally distributed, some or all of the multiple functions may be distributed. Regardless of whether the functions are centrally distributed or distributed, as long as the configuration achieves the purpose of the invention.

Claims

1. A drive system for a work-related machine, wherein, This is applicable to working machinery with attachments, the attachments having a first movable member and a second movable member rotatably connected to the first movable member. The drive system of the operating machinery has: The drive unit includes a first electric actuator having a first output shaft for rotating the first movable member, and a second electric actuator having a second output shaft for rotating the second movable member. Control device, controls the drive unit; The control device performs: The first process calculates a limit value for the rotational speed of the first output shaft based on the relative position of the second movable member relative to the first movable member, and... The second process involves controlling the first electric actuator to reduce the rotational speed of the first output shaft to below the limit value. In the first process, when the distance from the first output shaft to the top of the connection portion in the accessory connected to the first output shaft is a first value, the limiting value is reduced compared to a second value where the distance is less than the first value.

2. The drive system of the operating machinery according to claim 1, wherein, When the upper limit of the circumferential velocity with the top of the attachment as the target is taken as the upper limit circumferential velocity, In the first process, the control device calculates the value corresponding to the quotient obtained by dividing the preset upper limit circumferential speed by the distance, and uses it as the limit value.

3. The drive system of the operating machinery according to claim 1, wherein, The accessory has a third movable member that is rotatably connected to the second movable member. The drive unit has a third electric actuator, which has a third output shaft that rotates the third movable member. The top end of the accessory is the top end on the opposite side of the connection portion of the third movable member that is connected to the third output shaft. In the first process, the control device calculates the limit value based on the relative position of the second movable member relative to the first movable member and the relative position of the third movable member relative to the second movable member.

4. The drive system of the operating machinery according to claim 3, wherein, When the limit value is set to the first limit value, In the first process, the control device calculates the first limit value, the second limit value (i.e., the rotational speed limit of the second output shaft), and the third limit value (i.e., the rotational speed limit of the third output shaft) based on the relative position of the second movable member relative to the first movable member and the relative position of the third movable member relative to the second movable member. In the second process, the control device controls the first electric actuator to make the rotational speed of the first output shaft below the first limit value, controls the second electric actuator to make the rotational speed of the second output shaft below the second limit value, and controls the third electric actuator to make the rotational speed of the third output shaft below the third limit value. In the first process, when the distance between the first output shaft and the top of the accessory is the first value, the first limit value, the second limit value, and the third limit value are reduced compared to when the distance is the second value.

5. The drive system of the operating machinery according to claim 3, wherein, The machinery being operated is construction machinery. The first movable component is a lever arm. The second movable component is the boom. The third movable component is the bucket.

6. A control device for a work machine, wherein, Suitable for operating machinery, The operating machinery has: The attachment includes a first movable member and a second movable member rotatably connected to the first movable member. The drive unit includes a first electric actuator having a first output shaft that rotates the first movable member, and a second electric actuator having a second output shaft that rotates the second movable member. The control device performs: The first process calculates a limit value for the rotational speed of the first output shaft based on the relative position of the second movable member relative to the first movable member, and The second process involves controlling the first electric actuator to reduce the rotational speed of the first output shaft to below the limit value. In the first process, when the distance from the first output shaft to the top of the connection portion in the accessory connected to the first output shaft is a first value, the limiting value is reduced compared to a second value where the distance is less than the first value.

7. A control method for a work-related machine, wherein, The operating machinery has: The attachment includes a first movable member and a second movable member rotatably connected to the first movable member. The drive unit includes a first electric actuator having a first output shaft that rotates the first movable member, and a second electric actuator having a second output shaft that rotates the second movable member. The control device applied to the aforementioned working machinery executes: The first process calculates a limit value for the rotational speed of the first output shaft based on the relative position of the second movable member relative to the first movable member, and The second process involves controlling the first electric actuator to reduce the rotational speed of the first output shaft to below the limit value. In the first process, when the distance from the first output shaft to the top of the connection portion in the accessory connected to the first output shaft is a first value, the limiting value is reduced compared to a second value where the distance is less than the first value.

8. A computer program product, comprising a control program for a work machine, wherein, The operating machinery has: The attachment includes a first movable member and a second movable member rotatably connected to the first movable member. The drive unit includes a first electric actuator having a first output shaft that rotates the first movable member, and a second electric actuator having a second output shaft that rotates the second movable member. The control program for the operating machinery causes the control device applicable to the operating machinery to execute: The first process calculates a limit value for the rotational speed of the first output shaft based on the relative position of the second movable member relative to the first movable member, and The second process involves controlling the first electric actuator to reduce the rotational speed of the first output shaft to below the limit value. In the first process, when the distance from the first output shaft to the top of the connection portion in the accessory connected to the first output shaft is a first value, the limiting value is reduced compared to a second value where the distance is less than the first value.

Images