Swing control device for work machine and work machine including the same

Abstract

To provide a turning control device capable of preventing a part of a working machine from deviating from a restriction area by a turning operation regardless of a reach length of a working device, and a working machine including the turning control device.SOLUTION: During a braking period from when a predetermined slewing stop command is output during slewing of a slewing body to when the slewing body is stopped, for each of a plurality of reference points, the control unit calculates a required braking angle required until the slewing body is stopped, based on a current slewing speed of the slewing body and a deceleration determined from a braking torque in a drive unit and a slewing inertia moment acting on the slewing body, and calculates an allowable slewing angle from a current position of the reference point to a limit area surface, A command signal corresponding to an operation amount received by an operation unit is corrected by a set deceleration coefficient set based on a ratio of the allowable turning angle to the required braking angle at each of the plurality of reference points.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a swing control device for a work machine and a work machine equipped with the same. [Background technology]

[0002] Conventionally, there are known swing control technologies for ensuring the safety of work machines. Patent Document 1 discloses a technology (braking technology) for stopping the swing operation of a hydraulic excavator based on a preset relative position between the working area surface and the attachment.

[0003] In this technology, when braking is initiated, it is first assumed that maximization of the reach length of the hydraulic excavator's attachment has begun, and the swing angle required to stop the swing (predicted swing braking angle) is derived using a motion equation or the like. Furthermore, it is determined whether the attachment will deviate from the working area if the upper rotating body of the hydraulic excavator continues to swing at the attachment reach length when the predicted swing braking angle is reached. If it is determined that the attachment will deviate from the working area, the target swing stopping angle is corrected based on the predicted reach of the attachment and the distance between the upper rotating body and the working area, and braking is initiated based on the predicted swing braking angle and the target swing stopping angle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7231444 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned conventional technology, the swing angle required to stop the swing (predicted swing braking angle) is calculated on the assumption that the shovel's reach length has started to be maximized. Therefore, operations that shorten the attachment's reach length are not taken into consideration, and in such cases, there is a risk that the farthest point of the work implement from the swing center will be outside the working area. [Means for solving the problem]

[0006] An object of the present invention is to provide a swing control device for a work machine that can prevent part of the work machine from departing from a restricted area due to a swing operation, regardless of the reach length of the work implement, and a work machine equipped with the same.

[0007] The present invention provides a swing control device for a work machine having a body including a lower body and a rotating body that can swing relative to the lower body, a work implement supported on the rotating body, an operation unit that receives operation from an operator to move the rotating body and the work implement, and a drive unit that can swing and brake the rotating body in response to input command signals. The swing control device has a control unit that can correct the command signal that corresponds to the amount of operation received by the operation unit and input it to the drive unit so that a plurality of reference points that have been preset on the work machine do not deviate from a restricted area plane that has been set around the work machine. During the braking period from when a predetermined rotation stop command is output while the rotating body is rotating until the rotating body stops, the control unit calculates, for each of the multiple reference points, a required braking angle, which is the rotation angle required for the rotating body to stop, based on the current rotation speed of the rotating body and a deceleration determined from the braking torque in the drive unit and the rotation moment of inertia acting on the rotating body, while calculating a rotation margin angle, which is the rotation angle from the current position of the reference point to reaching the restricted area surface, and corrects the command signal corresponding to the operation amount received by the operating unit by a set deceleration coefficient set based on the ratio of the rotation margin angle to the required braking angle at each of the multiple reference points.

[0008] According to this configuration, it is possible to prevent a part of the work machine from departing from the restricted area surface, regardless of the movement or reach length of the work implement.

[0009] In the above configuration, the control unit may set the minimum ratio of the turning margin angle to the required braking angle at each of the plurality of reference points as the set deceleration coefficient.

[0010] According to this configuration, the set deceleration coefficient is set based on the reference point among multiple reference points that is closest to the restricted area surface, thereby making it possible to stably prevent part of the work machine from deviating from the restricted area surface.

[0011] In the above configuration, the control unit may calculate the braking torque based on a relief pressure of a hydraulic circuit included in the drive unit and a pump displacement.

[0012] According to this configuration, the braking torque is calculated from the relief pressure of the hydraulic circuit and the pump displacement, so that braking control can be achieved taking into account the performance of the drive unit.

[0013] In the above configuration, the plurality of reference points may include a plurality of specific reference points set on the working device, and the control unit may calculate the coordinates and velocity for each of the plurality of specific reference points, and calculate the turning margin angle assuming that the velocity is maintained during the braking period.

[0014] According to this configuration, the coordinates and speed of the work implement are grasped and that speed is maintained, and the set deceleration coefficient is set under the most risk-taking conditions, thereby making it possible to stably prevent any part of the work machine from deviating from the restricted area surface.

[0015] In the above configuration, if the ratio of the turning margin angle to the required braking angle at one of the plurality of reference points exceeds 1, the control unit may regard the ratio at the one reference point as 1.

[0016] According to this configuration, when the ratio exceeds 1, the speed command based on the operator's operation is not corrected, in other words, the speed command is not amplified, and no restrictions are placed on the operator's operation of the working device. In other words, the movement of the working device according to the operator's intention is achieved as is. As a result, the operator is prevented from feeling excessive discomfort.

[0017] In the above configuration, the machine may also include a body including a lower body and a rotating body that can rotate relative to the lower body, a working device supported on the rotating body, an operating unit that receives operation from an operator to move the working device on the rotating body, a drive unit that can rotate and brake the rotating body in response to an input command signal, and the rotation control device described above.

[0018] According to this configuration, it is possible to prevent a part of the work machine from departing from the restricted area surface, regardless of the movement or reach length of the work implement. [Effects of the Invention]

[0019] According to the present invention, a swing control device and a work machine equipped with the same are provided that can prevent a part of the work machine from departing from a restricted area due to a swing operation, regardless of the reach length of the work implement. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a side view of a work machine according to an embodiment of the present invention. [Figure 2] 1 is a block diagram of a work machine including a swing control device according to an embodiment of the present invention. [Figure 3] 10A and 10B are side views showing movement of the attachment so as to shorten the reach length in the work machine according to one embodiment of the present invention. [Figure 4] 4A and 4B are a schematic diagram and a graph showing the relationship between bucket movement and reach length in the work machine according to one embodiment of the present invention. [Figure 5]4 is a flowchart of a turning control process according to an embodiment of the present invention. [Figure 6] FIG. 4 is a flowchart of a turning control process according to an embodiment of the present invention. [Figure 7] 5 is a schematic diagram illustrating a calculation process of a deceleration coefficient in a turning control process according to an embodiment of the present invention. FIG. [Figure 8] 5 is a schematic diagram illustrating a calculation process of a deceleration coefficient in a turning control process according to an embodiment of the present invention. FIG. [Figure 9] FIG. 3 is a schematic diagram showing parameters of a work machine according to an embodiment of the present invention. [Figure 10] FIG. 3 is a schematic diagram showing parameters of a work machine according to an embodiment of the present invention. [Figure 11] 4 is a graph showing the transition of the reduction-side hydraulic oil pressure of the swing hydraulic motor in the work machine according to one embodiment of the present invention. [Figure 12] 3 is a schematic diagram showing the movement of an attachment controlled by a swing control device according to one embodiment of the present invention. FIG. [Figure 13] 1 is a diagram showing an example of a hydraulic circuit diagram of a work machine according to an embodiment of the present invention. FIG. [Figure 14] FIG. 4 is a diagram showing another example of a hydraulic circuit diagram of a work machine according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] Preferred embodiments of the present invention will now be described with reference to the drawings.

[0022] FIG. 1 shows a side view of a hydraulic excavator 1 (work machine) according to one embodiment of the present invention.

[0023] The hydraulic excavator 1 includes a lower traveling body 10 (lower main body) that can travel on the ground G (traveling surface), an upper rotating body 12 (swivel) that is rotatably supported on the lower traveling body 10, and a movable work attachment 20 (work device) that is mounted on the upper rotating body 12. The lower traveling body 10 and the upper rotating body 12 correspond to the machine body of the hydraulic excavator 1.

[0024] The lower traveling body 10 is capable of traveling on the ground surface G. The lower traveling body 10 includes a crawler-type traveling unit.

[0025] The upper rotating body 12 has a rotating frame 121 supported by the lower traveling body 10, a cab 13 mounted on the rotating frame 121, and a counterweight 15. The cab 13 allows an operator (worker) to board, and is equipped with various devices for operating the hydraulic excavator 1. The counterweight 15 is disposed at the rear of the rotating frame 121, and functions as a weight for balancing the hydraulic excavator 1.

[0026] The work attachment 20 is attached (supported) to the upper rotating body 12 so as to be movable relative to the upper rotating body 12, and performs predetermined work on the ground G or the like. The work attachment 20 includes a boom 21 connected to the front end of the revolving frame 121 so as to be rotatable in the hoisting direction about a horizontal central axis of rotation, an arm 22 connected to the tip of the boom 21 so as to be rotatable about the horizontal central axis of rotation, and a bucket 23 connected to the tip of the arm 22 so as to be rotatable about the horizontal central axis of rotation. In this embodiment, the central axes of rotation of the boom 21, arm 22, and bucket 23 are set parallel to one another. The boom 21 and arm 22 constitute a hoisting body of the hydraulic excavator 1. The upper rotating body 12 further includes a boom cylinder 21S that extends and retracts to hoist (rotate) the boom 21, an arm cylinder 22S that extends and retracts to rotate the arm 22, and a bucket cylinder 23S that extends and retracts to rotate the bucket 23. Each of these cylinders comprises a hydraulic cylinder.

[0027] Bucket 23 includes a plurality of teeth 23H. The plurality of teeth 23H are spaced apart in a direction perpendicular to the plane of the paper in FIG. 1 (left-right direction), and are provided so as to protrude from the main body of bucket 23. When hydraulic excavator 1 performs excavation work on ground G, work attachment 20 moves so that the plurality of teeth 23H of bucket 23 penetrates the ground.

[0028] The cab 13 is mounted on the front of the revolving frame 121 and constitutes a driver's cabin for operating the hydraulic excavator 1. That is, in the cab 13, the operator performs operations for operating the lower traveling structure 10, the upper revolving structure 12, and the work attachment 20, etc.

[0029] 2 is a block diagram of a hydraulic excavator 1 including a control device 100 according to this embodiment. The hydraulic excavator 1 has a control unit 50, an operation unit 52, an input unit 54, an attachment information acquisition unit 56, a vehicle body information acquisition unit 58, a LiDAR 60, a drive unit 62, and a display device 64. The hydraulic excavator 1 is also connected via wireless communication or the like to a management device 66 (server) that is located away from the work site.

[0030] The control unit 50 is composed of a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores a control program, a RAM (Random Access Memory) used as a work area for the CPU, and the like. The CPU executes the control program stored in the ROM, causing the control unit 50 to function as an excavator control unit 501, a calculation unit 502, a determination unit 503, and a storage unit 504. These functional units do not have physical entities, but correspond to units of functions executed by the control program. Note that all or part of the control unit 50 is not limited to being provided within the hydraulic excavator 1, and may be located in a location different from the hydraulic excavator 1 when the hydraulic excavator 1 is remotely controlled. The control program may be transmitted from a remote server (management device) or cloud to the control unit 50 within the hydraulic excavator 1 and executed therein, or the control program may be executed on the server or cloud, and various generated command signals may be transmitted to the hydraulic excavator 1. The control unit 50 will be described in more detail below.

[0031] The operating unit 52 is disposed inside the cab 13 and includes various levers and the like that are operated by the operator. That is, the operating unit 52 receives operations for moving various parts of the hydraulic excavator 1. These operations include traveling of the lower traveling structure 10, rotating of the upper rotating structure 12, driving of the work attachment 20 (boom 21, arm 22, bucket 23), and the like (see FIGS. 13 and 14).

[0032] The input unit 54 is disposed inside the cab 13 and receives input of various types of information. As an example, the input unit 54 includes various input buttons, switches, and a touch panel included in the display device 64. In particular, the input unit 54 receives input of a start signal for starting turning control by the control unit 50.

[0033] The attachment information acquisition unit 56 acquires information for detecting information related to the attitude of the work attachment 20 relative to the upper rotating body 12. As an example, the attachment information acquisition unit 56 includes three stroke sensors 56A attached to the boom cylinder 21S, arm cylinder 22S, and bucket cylinder 23S, respectively, and detects the stroke (extension amount, length) of each cylinder. The stroke of each cylinder detected by each stroke sensor 56A is used to calculate the position and attitude of the boom 21, arm 22, and bucket 23. Note that, in order to calculate the position and attitude of the boom 21, arm 22, and bucket 23, angle sensors 56B (boom angle sensor, arm angle sensor, bucket angle sensor) that detect the rotation angles of the boom 21, arm 22, and bucket 23, respectively, may be used instead of the stroke sensors 56A.

[0034] The vehicle body information acquisition unit 58 acquires position information of the hydraulic excavator 1. As an example, the vehicle body information acquisition unit 58 can acquire vehicle body coordinate information, which is information regarding the absolute coordinates at the work site of a vehicle body reference point that is provided in advance on the upper rotating body 12. The vehicle body information acquisition unit 58 has an antenna 58A that constitutes the vehicle body reference point. The antenna 58A is disposed on the top surface of the cab 13 and functions as a GNSS mobile station. Meanwhile, a GNSS (Global Navigation Satellite System) reference station (not shown) is provided to acquire the vehicle body coordinate information. The GNSS reference station is a reference station that is disposed at the work site or in a location closest to the work site. Note that, in addition to the well-known GPS (Global Positioning System), satellite positioning systems such as GLONASS (Global Navigation Satellite System), Galileo, and QZSS (Quasi-Zenith Satellite System) may also be adopted as the GNSS.

[0035] Furthermore, the vehicle body information acquisition unit 58 acquires the attitude of the hydraulic excavator 1 with respect to the ground. Specifically, the vehicle body information acquisition unit 58 includes an IMU (Inertial Measurement Unit) 58B mounted on the upper rotating body 12. The IMU 58B detects information relating to the attitude of the upper rotating body 12 with respect to the ground G. In other words, the IMU 58B detects the attitude and angle (inclination) of the hydraulic excavator 1 machine body.

[0036] The LiDAR 60 is disposed at the front end of the top surface of the cab 13. The LiDAR 60 photographs surrounding objects in front of the cab 13, and in particular, acquires image information about the periphery of the bucket 23. More specifically, the LiDAR 60 has a coordinate origin and is capable of acquiring a three-dimensional distance distribution of surrounding objects, including the bucket 23, relative to the coordinate origin. The three-dimensional distance distribution is a distribution of distances between the coordinate origin and a plurality of surrounding measurement points. The acquired distance distribution is input to the control unit 50 as three-dimensional distance data. Note that the coordinate origin may be another specific part of the hydraulic excavator 1. In other embodiments, a time-of-flight (TOF) sensor, a stereo camera, a depth sensor, or the like may be used instead of the LiDAR 60.

[0037] The drive unit 62 drives various structural components of the hydraulic excavator 1, including the undercarriage 10, the upper rotating body 12, and the work attachment 20, which are operated by the operation unit 52. In particular, the drive unit 62 can rotate and brake the upper rotating body 12 in response to input command signals. The drive unit 62 can also move the work attachment 20 in response to input command signals. In this case, the drive unit 62 receives predetermined command signals (drive command signals) and drives the work attachment 20 in response to the command signals. These command signals also include input signals to proportional valves, which will be described later. The drive unit 62 can change the attitude of the work attachment 20 relative to the upper rotating body 12. The drive unit 62 includes hydraulic circuits, such as a hydraulic pump and a hydraulic motor (see FIGS. 13 and 14).

[0038] The display device 64 is a liquid crystal display provided inside the cab 13, and displays various information relating to the operation of the hydraulic excavator 1, detection results, calculation results, etc., to notify the operator. In this case, the display device 64 receives a predetermined display command signal, and displays (outputs) various information to be notified to the operator in accordance with the display command signal. The display device 64 is also capable of displaying map information, 3D images, etc. of the work site, and can display the position information of the hydraulic excavator 1 in association with these images. The display device 64 functions in the same way even during remote operation.

[0039] The management device 66 is, for example, a server provided in a management center located in a remote location. The management device 66 has a memory unit (management memory unit) similar to the memory unit 504. The memory unit can store the work information of the hydraulic excavator 1 and the position information of the hydraulic excavator 1 acquired by the vehicle body information acquisition unit 58 in association with each other.

[0040] Next, the control unit 50 will be described in further detail. The excavator control unit 501 inputs a drive command signal to the drive unit 71 in accordance with the content of the operation received by the operating unit 51. As a result, the operations of the lower traveling structure 10, the upper rotating structure 12, the work attachment 20, and the like are controlled. Furthermore, when the hydraulic excavator 1 operates in the automatic operation mode, the excavator control unit 501 inputs a drive command signal to the drive unit 62 so that the teeth 23H of the bucket 23 move along a preset design surface. The drive command signal is based on a virtual trajectory along which the teeth 23H move at the work site, and the trajectory may be stored in advance in the memory unit 504 by teaching or the like.

[0041] The calculation unit 502 executes various calculations in the turning control executed by the control unit 50.

[0042] The determination unit 503 executes various determination processes executed in the above-mentioned turning control.

[0043] The storage unit 504 stores (memorizes) in advance various thresholds, parameters, etc. that are referenced in the operation of the hydraulic excavator 1 and in the control unit 50.

[0044] Fig. 3 is a side view showing the movement of the work attachment 20 that shortens the reach length in the hydraulic excavator 1 according to this embodiment. Fig. 4 is a schematic diagram and graph showing the relationship between the movement of the bucket 23 and the reach length in the hydraulic excavator 1 according to this embodiment. Note that the reach length in the present invention means the distance from the center of rotation of the upper rotating body 12 to the farthest part of the work attachment 20 in a plan view.

[0045] If there are obstacles or worker walkways around the hydraulic excavator 1 at a work site, there is a possibility of danger if the bucket 23 or the like approaches as the hydraulic excavator 1 moves. For this reason, a restricted area is set in advance around the hydraulic excavator 1, taking into account the location of obstacles and the like. As an example, the restricted area covers the entire hydraulic excavator 1 and is configured as an area through which the work attachment 20 can pass as the upper rotating body 12 rotates. In this embodiment, the restricted area is a virtual area in the shape of a rectangular parallelepiped. Each side of the restricted area is defined as a restricted area surface. The restricted area surface is disposed around the hydraulic excavator 1. Note that if the restricted area is set too small, the movement of the hydraulic excavator 1 will be excessively restricted, while if it is set too large, safety will not be sufficiently ensured. Therefore, it is desirable to set the extent of the restricted area by balancing safety and work efficiency. The shape and position (coordinates) of the restricted area may be stored in advance in the storage unit 504.

[0046] For example, when the upper rotating body 12 swings while holding the arm 22 of the work attachment 20, the reach length of the work attachment 20 becomes shorter in a plan view, but the connection portion between the arm 22 and the rod tip of the arm cylinder 22S (indicated by the dashed-dotted line in FIG. 3 ) moves in a direction away from the center of rotation of the upper rotating body 12. This means that part of the work attachment 20 may move out (deviate) from the restricted area. Also, as shown in FIG. 4 , when performing an operation such as holding the bucket 23, the position from the center of rotation of the upper rotating body 12 to the farthest part of the work attachment 20 changes from the tip (toe) of the bucket 23 to the back surface of the bucket, and then from the back surface of the bucket to the connection portion between the bucket and the tip of the cylinder rod. Therefore, during the operation of shortening the reach length, the distance from the center of rotation to the farthest point of the work machine repeatedly moves closer to and further away from the center of rotation.

[0047] In this embodiment, the control device 100 (swing control device) executes a swing control process to prevent a part of the hydraulic excavator 1 from deviating from the restricted area due to the swing operation of the upper swing body 12, regardless of the movement of the work attachment 20 as described above. In particular, the control unit 50 of the control device 100 corrects a command signal corresponding to the amount of operation received by the operation unit 52 and inputs the corrected command signal to the drive unit 62 so that a plurality of reference points N set in advance on the hydraulic excavator 1 do not deviate from the restricted area plane set around the hydraulic excavator 1. For example, the restricted area plane is a plane intersecting with the swing plane of the hydraulic excavator 1 (a plane perpendicular to the swing central axis).

[0048] Fig. 5 is a flowchart of the swing control processing according to this embodiment. Fig. 6 is a flow diagram of the swing control processing according to this embodiment, and is used to explain a part of the flowchart of Fig. 5 in more detail. Figs. 7 and 8 are schematic diagrams included in Fig. 6 that explain the calculation process of the deceleration coefficient of the swing control device. Figs. 9 and 10 are schematic diagrams showing parameters of the hydraulic excavator 1 that are referenced in the control device 100.

[0049] If the operator wants to prevent a part of the work attachment 20 from departing from the restricted area during work, he / she can issue a command to execute a swing control process (swing stop command) via the input unit 54 (FIG. 2), for example, before or during a swing operation.

[0050] When the execution of the swing control process is started, the control unit 50 acquires a pilot pressure (Pi pressure) generated by a lever input to the operation unit 52 for the movement of the work attachment 20 and the swing operation of the upper swing body 12 (step S1 in FIG. 5). The pilot pressure can be acquired by various sensors, which will be described in detail later (FIGS. 13 and 14).

[0051] Next, the control unit 50 generates a speed command value for each axis corresponding to the pilot pressure obtained by the operator's operation on the operation unit 52, using conversion map 1 (FIG. 6) (reference information) that shows the relationship between the pilot pressure and the speed of each axis (step S2 in FIG. 5). That is, when the operator intends to move the work attachment 20 (boom 21, arm 22, bucket 23) by himself / herself, a speed command value for each member is derived according to the amount of operation of each lever. The speed in this case corresponds to the angular velocity around each rotation axis of the boom 21, arm 22, and bucket 23 (shaft speed). The above map (reference information) is obtained in advance by experiments or the like, and is stored in the storage unit 504.

[0052] In this embodiment, each speed command value corresponding to the operator operation obtained above is subjected to restricted area processing, which further controls the movement of the hydraulic excavator 1 so as not to deviate from the restricted area, and the speed command value is updated by multiplying each speed command value by a predetermined gain (the set deceleration coefficient K in FIG. 6), thereby performing safe stop control for the set area surface (all set surfaces such as a part of the restricted area and the sides).

[0053] The method for setting the gains described above will now be described in further detail. First, the control unit 50 acquires information relating to the current actual movement of the work attachment 20. Specifically, the control unit 50 calculates the current coordinates (postures) and velocities of multiple reference points N on the hydraulic excavator 1 using stroke information (angle information) acquired by the sensors provided on the work attachment 20 (boom 21, arm 22, bucket 23) (step S3 in FIG. 5).

[0054] FIG. 9 shows the attachment specifications in the initial state, as well as the relationship between arbitrary points N1, N2, and N3 on the attachment and the position vectors n1, n2, and n3 from the corresponding axes of each point. N1 denotes an arbitrary point on the boom 21, N2 denotes an arbitrary point on the arm 22, and N3 denotes an arbitrary point on the bucket 23. Axis 1 denotes the rotation axis of the boom 21, axis 2 denotes the rotation axis of the arm 22, and axis 3 denotes the rotation axis of the bucket 23. Mup, Mbm, Mam, and Mbk shown in the figure represent the masses indicated at the centers of gravity of the upper rotating body 12, boom 21, arm 22, and bucket 23, respectively. The values ​​indicated by L and H represent the distances between the center lines, point N, and centers of gravity of each member. This will be specifically described using FIG. 9, in which the boom 21, arm 22, and bucket 23 are all extended horizontally. L1, L2, and L3 represent the length from the boom foot to the boom top, the length from the arm foot to the arm top, and the length from the bucket foot to the bucket tip, respectively. lWis the horizontal distance (height) from the ground to the joint point between the lower running body 10 and the upper rotating body 12. H0 is the vertical distance from the joint point between the upper rotating body 12 and the lower running body 10 to the boom foot. L0 is the horizontal distance from the joint point between the lower running body 10 and the upper rotating body 12 to the boom foot. Hup is the height from the boom foot to the center of gravity of the upper rotating body 12. Lup represents the horizontal distance from the center of gravity of the upper rotating body 12 to the joint point between the upper rotating body 12 and the lower running body 10. Lbm and Hbm are the horizontal and vertical distances, respectively, from the boom foot to the center of gravity of the boom 21. Lam and Ham are the horizontal and vertical distances, respectively, from the arm foot to the center of gravity of the arm 22. Lbk and Hbk represent the horizontal and vertical distances, respectively, from the bucket foot to the center of gravity of the bucket 23.

[0055] Fig. 10 shows the relationship of angular displacement from the initial state in Fig. 9. If the vehicle rotation angle, tilt angle, swing angle, boom angle, arm angle, and bucket angle of the hydraulic excavator 1 are θ_roll, θ_up, θ_sw, θ_bm, θ_am, and θ_bk, respectively, and the rotation matrices for each angle are R_roll, R_up, R_sw, R_bm, R_am, and R_bk, the coordinates [X_bm, Y_bm, Z_bm] of point N1 on the boom, the coordinates [X_am, Y_am, Z_am] of point N2 on the arm, and the coordinates [X_bk, Y_bk, Z_bk] of point N3 on the bucket can be expressed by the following equation 1. Note that points N1, N2, and N3 are collectively referred to as reference point N.

[0056]

number

[0057] Furthermore, by differentiating Equation 1, the velocities of each of the reference points N1, N2, and N3 can be calculated. Also, the angular velocities of each attachment, i.e., ω_roll, ω_up, ω_sw, ω_bm, ω_am, and ω_bk, which are the respective velocities of the vehicle body rotation angle, tilt angle, swing angle, boom angle, arm angle, and bucket angle of the hydraulic excavator 1, can be obtained by time-differentiating θ_roll, θ_up, θ_sw, θ_bm, θ_am, and θ_bk, respectively. Note that, although the above description uses three reference points N, it is desirable to set a plurality of reference points N in advance so as to include portions of the hydraulic excavator 1, and in particular, the surface of the work attachment 20, that are likely to deviate from the restricted area.

[0058] Next, the control unit 50 estimates the attitude of the hydraulic excavator 1 after a predetermined time from the attitude (position) of the hydraulic excavator 1 (work attachment 20) described above, assuming that the movement of each part will continue to be maintained at each speed. Then, the control unit 50 calculates the rotational moment of inertia J for each changing attitude (step S4 in FIG. 5). Here, attention is focused on the fact that the rotational moment of inertia J generated when the upper rotating body 12 of the hydraulic excavator 1 rotates is affected by the movement and attitude of the work attachment 20 supported by the upper rotating body 12.

[0059] The calculation of the rotational moment of inertia J will be described in detail below. The control unit 50 calculates the coordinates of the center of gravity of each attachment member (boom, arm, etc.) that makes up the work attachment 20 from the attachment specifications such as the dimensions, weight, and position of the center of gravity of each attachment shown in Figures 9 and 10, and the current posture, and can then calculate the rotational moment of inertia J about the rotation axis from the weight, coordinates of the center of gravity, and the distance to the center of rotation using the following equation 2.

[0060]

number

[0061] The control unit 50 also calculates the maximum deceleration α (deceleration) using the swing moment of inertia J calculated above and the maximum braking torque τ, which is determined by the relief valve and pump capacity in the hydraulic circuit included in the drive unit 62, from the following equation 3. Note that the maximum deceleration calculated using this method differs depending on the posture. The maximum deceleration is calculated so that the swing can be stopped at the shortest possible braking angle. If the vehicle is decelerated at the maximum deceleration, it can be stopped at the shortest swing braking angle for the posture of that moment of inertia.

[0062]

number

[0063] FIG. 11 is a graph showing the transition of the deceleration-side hydraulic fluid pressure P of the swing hydraulic motor in the hydraulic excavator 1 according to this embodiment. Referring to the graph on the left side of FIG. 11, the control according to this embodiment causes the swing operation to be suddenly braked, so the deceleration-side pressure of the swing hydraulic motor transitions in a trapezoidal waveform as shown in the same figure. In particular, at the beginning of deceleration, the flow rate out of the relief valve is large, so a pressure slightly higher than the relief pressure setting is generated. Meanwhile, referring to the graph on the right side of FIG. 11, the braking torque τ included in the above equation 3 can be calculated based on the following equation 4 by setting the relief pressure Pref to an approximate value of the average pressure on the deceleration side of the swing motor during swing deceleration. In addition, in equation 4, qm is the pump displacement of the hydraulic pump.

[0064]

number

[0065] Next, if the speed during calculation is ω0, by using the maximum deceleration α, the speed ω(t) with time t during maximum deceleration as a variable can be expressed by the following equation 5, and similarly the angle θ(t) can be expressed by the following equation 6.

[0066]

number

[0067]

number

[0068] Here, by eliminating time t from equations 5 and 6 and rearranging them, the angle θ(t) is expressed by the following equation 7.

[0069]

number

[0070] Fig. 12 is a schematic diagram showing the movement of the work attachment 20 controlled by the control device 100 according to this embodiment. Fig. 12 shows the work attachment 20 when braking processing is initiated, the work attachment 20 at a certain time during subsequent swinging, and the work attachment 20 when it virtually reaches the area surface.

[0071] From the above equation 7, the angle θstop required for the upper swing body 12 to stop from the current position is expressed by the following equation 8. In this embodiment, the angle θstop in equation 8 is referred to as the predicted swing braking angle (also referred to as the required braking angle, see FIG. 7). Equation 8 is based on the premise that the speed ω=0.

[0072]

number

[0073] Furthermore, by rearranging Equation 7 with respect to the speed ω (angular speed), the speed until stopping at maximum deceleration can be expressed by the following Equation 9 (step S5 in FIG. 5). Note that ω(θ) represents the rotation speed at which the robot can stop without crossing the limit area, and the control unit 50 uses this speed to limit the speed of each axis.

number

[0074] Next, the control unit 50 assumes that the axis speed at that time is maintained for each control cycle and that the posture of the work attachment 20 continues to change, and geometrically derives the swing margin angle θre (also referred to as the swing angle to the region, see FIG. 7) from an arbitrary point i (FIG. 8) set on the hydraulic excavator 1 to the region surface of the restricted region (step S6 in FIG. 5). In other words, in step S6, the control unit 50 calculates the swing angle until point i reaches the region surface.

[0075] As an example of a method for deriving the above θre, for example, a minute angle is added to the current attitude angle of the work attachment 20, the coordinates of the trajectory of each point N on the shovel are calculated, and if there is a point where these coordinates overlap with the area surface, it can be derived from that intersection point and the current swing angle. An example will be explained below using the swing angle θ, the length R of the attachment, and the distance D from the swing center to the area surface shown in Figure 12. First, let m be an integer and δθ be a minute angle, and find the smallest m that satisfies Equation 10. min If exists, θre can be expressed as the following equation 11. min If no limit exists, it can be said that the work attachment 20 does not exceed the restricted area surface.

[0076]

number

[0077]

number

[0078] As another calculation method, it is also possible to mathematically express the locus of points on the hydraulic excavator 1 and analytically solve the intersection between the restricted area surface of the restricted area and the locus.

[0079] Here, if the ratio of θre to θstop is taken as the deceleration coefficient Ki (also referred to as the speed command limit coefficient) at point i on the hydraulic excavator 1, the control unit 50 calculates this deceleration coefficient Ki based on the following equation 12 (step S7 in FIG. 5). Note that, although the swing margin angle and predicted swing braking angle are used to derive the deceleration coefficient Ki here, it may also be derived using the distance to the limit area surface corresponding to each angle.

number

[0080] If the calculation result of this ratio is 1 or greater, Ki is fixed at 1, so that no gain is set for the speed command value based on the operator's operation, in other words, the speed command value is not amplified, and no restrictions are placed on the operator's operation of the attachment. In other words, the movement of the work attachment 20 according to the operator's intention is realized as is.

[0081] The control unit 50 then determines whether or not the derivation of the deceleration coefficients Ki has been completed for all of the n points on the hydraulic excavator 1 that have been preset as shown in Figures 7 and 8 (step S8 in Figure 5). If the derivation of all deceleration coefficients Ki has been completed (YES in step S8), the process proceeds to step S9. On the other hand, if the derivation of all deceleration coefficients Ki has not been completed (NO in step S8), step S3 and subsequent steps are repeated.

[0082] In step S9, the control unit 50 adopts the smallest value among the derived multiple deceleration coefficients Ki as the set deceleration coefficient K. Note that selecting the smallest value among the multiple deceleration coefficients Ki means restricting the speed of each axis so that the point closest to the area surface of the restricted area does not deviate from the area.

[0083] Next, in step S10 of FIG. 5, the control unit 50 updates the operator speed command value by multiplying the speed command value of each axis by the set deceleration coefficient K. The updated speed command value is then converted into a pilot pressure command. The control unit 50 then converts and updates this pilot pressure command into a speed command for each axis using conversion map 2 of FIG. 6, and applies a current corresponding to the command value to the proportional valve (step S11 of FIG. 5), thereby braking the swing operation of the upper swing body 12 and the movement of the work attachment 20. As a result, it is possible to prevent each part of the work attachment 20 from deviating from its restricted area (area surface). The flowchart of FIG. 5 is repeated while the swing control process is being executed by the control device 100.

[0084] <Hydraulic circuits of work machines to which swing control devices are applied> Fig. 13 is a diagram showing an example of a hydraulic circuit diagram of the hydraulic excavator 1 according to this embodiment. Note that in Fig. 13, a reference numeral is assigned to one of a plurality of members, and the reference numerals of other members having the same function and structure as that member are omitted.

[0085] In this example, the drive unit 62 has a hydraulic pump 620. The hydraulic pump 620 is connected to an output shaft of an engine 621 and is driven by power received from the engine 621. Note that an electric motor may be used instead of the engine 621.

[0086] The hydraulic oil discharged by the hydraulic pump 620 is supplied to the swing motor 12S, boom cylinder 21S, arm cylinder 22S, and bucket cylinder 23S through each control valve 622. These hydraulic actuators are driven by receiving hydraulic oil in one oil chamber and discharging hydraulic oil from the other oil chamber. Note that switching the oil chamber that receives hydraulic oil switches the rotation direction of the swing motor 12S and the extension and contraction of each cylinder. As mentioned above, a stroke sensor 56A is attached to each cylinder. In addition, the swing motor 12S is attached to an angle sensor 56B that can detect the swing angle.

[0087] The operation unit 52 includes a swing lever 521, a boom lever 522, an arm lever 523, and a bucket lever 524. Note that the functions of two of these levers may be performed by a single lever. Each lever has a hydraulic remote control valve, and a pressure (pilot pressure) corresponding to the amount of operation is detected by a pressure sensor 624. As a result, pilot pressure information is input to the control unit 50. In addition, the pilot pressure corresponding to the amount of operation received by the operation unit 52 can be adjusted by a proportional valve 623 (electromagnetic proportional pressure reducing valve) located between the remote control valve and the control valve 622. The opening of the proportional valve 623 for this purpose is adjusted by a proportional valve command input from the control unit 50.

[0088] In this embodiment, as described above, the control unit 50 updates the operator speed command value by multiplying the speed command value of each axis by the set deceleration coefficient K. Then, the updated speed command value is converted into a pilot pressure command. Thereafter, the control unit 50 converts this pilot pressure command into a speed command for each axis using conversion map 2 in FIG. 6, and realizes braking control by passing a current corresponding to the command value to the proportional valve 623.

[0089] 13, a relief valve 625 is provided between the control valve 622 and each hydraulic actuator. Therefore, as described above, the braking torque τ included in Equation 3 can be set to the relief pressure Pref (FIG. 11), that is, the stable pressure after excessive pressure has been released, as an approximate value of the average pressure on the deceleration side of the swing motor 12S during swing deceleration. As a result, swing braking by the braking torque τ taking into account the relief valve 625 and the pump capacity qm of the hydraulic pump 620 becomes possible.

[0090] FIG. 14 is a diagram showing another example of a hydraulic circuit diagram of the hydraulic excavator 1 according to this embodiment. In this example, the amount of lever operation by the operator is determined and controlled not by pilot pressure but by sensor information such as a potentiometer attached to the lever. For this reason, levers 521 to 524 are configured as electric levers, and information corresponding to the amount of operation (lever operation information) is input to the control unit 50. The other configurations are the same as those in FIG. 13.

[0091] As described above, in this embodiment, when the operator operates the control lever of the operation unit 52 to rotate the upper rotating body 12, even if the operator further operates the control lever for moving the work attachment 20, the ratio of the margin angle θre to the area surface of each reference point i if the movement of the work attachment 20 continues to the predicted swing braking angle θstop (required braking angle), which is the angle required for the upper rotating body 12 to stop, is referenced. At this time, the calculation of the required braking angle also includes the component of the swing moment of inertia J associated with the movement of the work attachment 20. As a result, the required braking angle can be calculated with high accuracy, taking into account the influence of the movement of the work attachment 20. Then, the deceleration coefficient Ki, which is the ratio of θre to θstop, is calculated for each reference point i, and the minimum value thereof is used as the set deceleration coefficient K. Therefore, braking control of the upper rotating body 12 and control of the movement of the work attachment 20 are realized by focusing on the part that is most likely to come close to the restricted area surface, so that the hydraulic excavator 1 can be stably prevented from departing from the restricted area.

[0092] Furthermore, with this control, even when the arm 22 of the work attachment 20 is moved toward the upper rotating body 12 and the reach length of the work attachment 20 is reduced, it is possible to prevent a part of the work attachment 20 from departing from the restricted area. For example, if there is a ceiling above the work attachment 20 at the work site, an arm pulling operation that reduces the reach length may cause the base end of the arm 22 to move upward and interfere with the ceiling. Even in such cases, the above control can accurately prevent the base end of the arm from interfering with the ceiling.

[0093] During the braking period from when a predetermined rotation stop command is output during the rotation of the upper rotating body 12 until the upper rotating body 12 stops, the control unit 50 of the control device 100 according to this embodiment calculates, for each of a plurality of reference points N, a required braking angle θstop, which is the rotation angle required for the upper rotating body 12 to stop, based on the current rotation speed of the upper rotating body 12 and the deceleration determined from the braking torque τ in the drive unit 62 and the rotation moment of inertia J acting on the upper rotating body 12, while calculating a rotation margin angle θre, which is the rotation angle from the current position of the reference point N until it reaches the restricted area surface, and corrects the command signal corresponding to the operation amount received by the operating unit 52 by a set deceleration coefficient K set based on the ratio of the rotation margin angle to the required braking angle at each of the plurality of reference points N.

[0094] With this configuration, regardless of the movement or reach length of the work attachment 20, it is possible to prevent a part of the work attachment 20 from departing from the restricted area surface.

[0095] In this embodiment, the control unit 50 sets the minimum ratio among the ratios Ki of the turning margin angle θre to the required braking angle θstop at each of the plurality of reference points N as the set deceleration coefficient K.

[0096] According to this configuration, the set deceleration coefficient K is set based on the reference point among the multiple reference points N that is closest to the restricted area surface, thereby making it possible to stably prevent part of the hydraulic excavator 1 from deviating from the restricted area surface.

[0097] In this embodiment, the control unit 50 calculates the braking torque τ based on the relief pressure of the hydraulic circuit included in the drive unit 62 and the pump displacement.

[0098] According to this configuration, the braking torque τ is calculated from the relief pressure Pref of the hydraulic circuit and the pump displacement qm, so that braking control taking into account the performance of the drive unit 62 can be realized.

[0099] In addition, in this embodiment, the multiple reference points N include multiple specific reference points N set on the work attachment 20, and the control unit 50 calculates the coordinates and speed for each of the multiple specific reference points, and calculates the turning margin angle assuming that the speed is maintained during the braking period.

[0100] With this configuration, the coordinates and speed of the work attachment 20 are grasped and that speed is maintained, and the set deceleration coefficient K is set under the most risk-taking conditions, so that it is possible to stably prevent part of the hydraulic excavator 1 from deviating from the restricted area surface.

[0101] Furthermore, in this embodiment, if the ratio of the turning margin angle to the required braking angle at one of the multiple reference points N exceeds 1, the control unit 50 regards the ratio at that one reference point as 1.

[0102] With this configuration, when the ratio exceeds 1, the speed command based on the operator's operation is not corrected, in other words, the speed command is not amplified, and no restrictions are placed on the operator's operation of the work attachment 20. In other words, the movement of the work attachment 20 according to the operator's intention is achieved as is. As a result, the operator is prevented from feeling excessive discomfort.

[0103] Although an embodiment of the control device 100 and the hydraulic excavator 1 according to the present invention has been described above, the present invention is not limited to the above embodiment.

[0104] In the above embodiment, the control device 100 is described as being mounted on the hydraulic excavator 1, but a part of the control device 100 may be disposed at a location remote from the hydraulic excavator 1. In this case, information may be transmitted and received via wireless communication or the like between the structure of the control device 100 mounted on the hydraulic excavator 1 and the structure disposed at a location remote from the hydraulic excavator 1. Furthermore, the hydraulic excavator 1 is an example of a work machine, and the control device 100 may be adopted for other work machines.

[0105] In the above embodiment, the multiple reference points N (specific reference points) are described as being set on the work attachment 20, but the reference point N may also be set on the rotating frame 121 of the upper rotating body 12, etc.

[0106] Furthermore, in the above embodiment, the set deceleration coefficient K is reflected in the speed of each axis of the rotating portion of the work attachment 20 and the upper rotating body 12. However, the set deceleration coefficient K may be reflected only in the rotating speed of the upper rotating body 12. In this case as well, by braking the upper rotating body 12, it is possible to prevent a part of the work attachment 20 from deviating from the restricted area surface, regardless of the movement or reach length of the work attachment 20. [Explanation of symbols]

[0107] 1. Hydraulic excavator (work machine) 10 Lower running body (lower body) 100 Control device (turning control device) 12 Upper rotating body (rotating body) 121 Swivel Frame 13 Cab 15 Counterweight 20 Work attachments (working devices) 21 Boom 22 Arm 23 Bucket 23H Tooth 50 control section 501 Excavator control unit 502 Arithmetic section 503 Judgment section 504 Storage section 52 Operation section 54 Input section 56 Attachment information acquisition unit 56A Stroke Sensor 56B Angle Sensor 58 Vehicle information acquisition unit 58A Antenna 58B IMU 60 LiDAR 62 Drive unit 64 Display device 66 Management device

Claims

1. A swing control device for a work machine having a machine body including a lower body and a rotating body that can swing relative to the lower body, a working device supported on the rotating body, an operation unit that receives operation from an operator to move the rotating body and the working device, and a drive unit that can swing and brake the rotating body in response to input command signals, a control unit that is capable of correcting the command signal corresponding to the amount of operation received by the operation unit and inputting the corrected command signal to the drive unit so that a plurality of reference points that have been set in advance on the work machine do not deviate from a restricted area surface that has been set around the work machine; The control unit During a braking period from when a predetermined rotation stop command is output during rotation of the rotating body until the rotating body stops, For each of the plurality of reference points, a required braking angle is calculated, which is the rotation angle required for the rotating body to stop, based on the current rotation speed of the rotating body and a deceleration determined from the braking torque in the drive unit and the rotation moment of inertia acting on the rotating body, while a rotation margin angle is calculated, which is the rotation angle from the current position of the reference point to the time when the restricted area surface is reached; a set deceleration coefficient set based on the ratio of the required braking angle to the swing margin angle at each of the plurality of reference points, and corrects the command signal corresponding to the operation amount received by the operating unit.

2. 2. The swing control device for a work machine according to claim 1, wherein the control unit sets the minimum ratio of the swing margin angle to the required braking angle at each of the plurality of reference points as the set deceleration coefficient.

3. 3. The swing control device for a work machine according to claim 1, wherein the control unit calculates the braking torque based on a relief pressure and a pump capacity of a hydraulic circuit included in the drive unit.

4. the plurality of reference points include a plurality of specific reference points set on the work device, 3. The turning control device for a work machine according to claim 1, wherein the control unit calculates coordinates and a velocity for each of the plurality of specific reference points, and calculates the turning margin angle on the assumption that the velocity is maintained during the braking period.

5. 3. The turning control device for a work machine according to claim 1, wherein, when a ratio of the turning margin angle to the required braking angle at one of the plurality of reference points exceeds 1, the control unit regards the ratio at the one reference point as 1.

6. a body including a lower body and a rotating body that is rotatable relative to the lower body; a working device supported on the rotating body; an operating unit that receives an operation from an operator to move the working device of the rotating body; a drive unit capable of rotating and braking the rotating body in response to an input command signal; The turning control device according to claim 1 ; A work machine comprising:

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