Work machine

Abstract

Whether or not a plurality of actuators driving a plurality of structures of a work device respectively are in an overloaded state or a stopped state is determined, and in a case where any of the plurality of actuators is determined to be in the overloaded state or the stopped state, the amount of pressure oil to be supplied to the actuator selected on the basis of the determination result is corrected. By appropriately controlling the actuator operation in accordance with the speed of the work device and the load condition of the actuator, a more efficient excavation operation can be achieved.

Description

Work machinery

[0001] The present invention relates to a work machine.

[0002] In a work machine having a front working implement (working device) such as a hydraulic excavator, an assist system has been proposed that controls actuator operation in accordance with the operation content input by the operator to prevent the front working implement from stopping due to an overload when excavating earth and sand, and to ensure smooth excavation operations. Prior art related to excavation control is known, for example, from Patent Document 1 and Patent Document 2.

[0003] Patent Document 1 discloses a construction machine that performs excavation work by driving a boom, arm, and bucket, and that has a boom angle detector that detects the angle of the boom, an arm angle detector that detects the angle of the arm, a bucket angle detector that detects the angle of the bucket, a memory device that stores data related to the soil characteristics of the soil to be excavated, and a control unit that controls the excavation operation, and the control unit calculates the excavation reaction force of the soil acting on the bucket based on the detected boom angle, the detected arm angle, the detected bucket angle, and the soil characteristics stored in the memory device, and determines whether the calculated excavation reaction force is greater than a preset upper limit value to determine whether the excavation operation should be modified.

[0004] Patent Document 2 discloses a backhoe work vehicle that is provided with a first sensor that detects the vertical angle of the boom relative to the vehicle body and a second sensor that detects the boom angle of the arm, as well as a calculator that calculates the position of the tip of the arm or bucket relative to the vehicle body based on information from the first and second sensors, and an output device that compares information from the calculator with information from a setting device and issues signals to operate each actuator so that the tip of the arm or bucket follows a predetermined trajectory, and is provided with an overload determiner that determines that an overload has occurred if the tip of the arm or bucket has not moved more than a set distance within a set time based on information from the calculator.

[0005] JP 2011-252338 A JP 61-146929 A

[0006] In the conventional technology described in Patent Document 1, the force (hereinafter referred to as the excavation reaction force) that the soil exerts on the front working machine during excavation operations is obtained based on the ground depth and pre-entered soil characteristics, and an overload state is determined based on whether the excavation reaction force is greater than a predetermined upper limit value (hereinafter referred to as the maximum excavation force), and a decision is made as to whether the excavation operation needs to be corrected or the actuator operation is controlled.

[0007] However, because the maximum excavation force that a hydraulic excavator can output depends on the maximum thrust of the cylinders and the geometric arrangement of the working device (geometric structure and joint angles), the maximum excavation force also changes according to changes in the posture of the working device. Therefore, if a determination is made as to whether or not the excavation operation needs to be modified based on a predetermined maximum excavation force (upper limit value) as in Patent Document 1, it may be determined that the excavation operation needs to be modified even though there is actually a margin up to the maximum excavation force.

[0008] Furthermore, in the conventional technology described in Patent Document 2, whether or not an overload state exists is determined based on whether or not the bucket tip has moved a predetermined distance or more within a predetermined set time, i.e., whether or not the bucket tip is in a stopped state.

[0009] However, in hydraulic excavator work, the stoppage of the front working implement does not necessarily occur only due to an overload caused by the excavation reaction force. Therefore, in the above-mentioned Patent Document 2, for example, when light excavation is performed at a speed below a threshold, such as during precision ground leveling work, it may be determined that the excavation operation needs to be corrected.

[0010] The present invention has been made in view of the above, and has an object to provide a work machine that can perform excavation operations more efficiently by appropriately controlling actuator operation in accordance with the speed of the work implement and the load state of the actuator.

[0011] The present application includes multiple means for solving the above-mentioned problems, and one example is a work machine comprising a work implement consisting of multiple structures, a plurality of actuators that respectively drive the multiple structures of the work implement, an overload detection device that detects an overload state of each of the multiple actuators, an angle / speed detection device that detects the operating angle and angular velocity of each of the multiple structures of the work implement, an operation device that operates the multiple actuators, and a control device that controls the amount of pressure oil supplied to the multiple actuators in accordance with the operation amount of the operation device, wherein the control device determines whether the multiple actuators are in an overload state based on the detection result of the overload detection device, and determines whether the multiple actuators are in a stopped state based on the detection result of the angle / angular speed detection device, and if it is determined that any of the multiple actuators is in an overload state and stopped, corrects the amount of pressure oil supplied to the actuator selected based on the determination result.

[0012] According to the present invention, the actuator operation is appropriately controlled in accordance with the speed of the work implement and the load state of the actuator, thereby enabling more efficient excavation operations.

[0013] FIG. 1 is a perspective view showing the appearance of a hydraulic excavator as an example of a work machine. FIG. 2 is a functional block diagram showing the processing functions of a controller together with related configuration. FIG. 3 is a functional block diagram showing the processing functions of an assist unit of the controller together with related configuration. FIG. 4 is a flowchart showing the processing content of the controller. FIG. 5 is a diagram explaining the basic concept of calculating a command flow rate by correcting an operation flow rate. FIG. 6 is a diagram explaining an example of a method for determining an assist direction when a single actuator satisfies condition A. FIG. 7 is a diagram explaining an example of a method for determining an assist direction when a single actuator satisfies condition A. FIG. 8 is a diagram explaining an example of a method for determining an assist direction when a single actuator satisfies condition A. FIG. 9 is a diagram explaining an example of a method for determining an assist direction when a single actuator satisfies condition A. FIG. 10 is a diagram explaining an example of a method for determining an assist direction when a plurality of actuators satisfy condition A. FIG. 11 is a functional block diagram showing the processing functions of an assist unit of a controller according to a second embodiment together with related configuration. FIG. 12 is a diagram showing an example of a norm calculation table that defines the relationship between elapsed time and a norm when an arm cylinder satisfies condition A. FIG. 10 is a diagram showing the target velocity vector of the bucket tip after the operation flow rate is corrected when the norm calculation table is applied.

[0014] An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, a hydraulic excavator will be described as an example of a work machine equipped with a front work implement (working device), but the present invention can also be applied to other work machines equipped with a front work implement.

[0015] In the following description, when there are multiple identical components, an alphabet may be added to the end of the reference numeral (number), but the alphabet may be omitted to refer to the multiple components collectively. For example, when there are three angle / angular velocity detection devices 20a, 20b, and 20c, these may be collectively referred to as angle / angular velocity detection device 20. For simplicity, signal lines and the like whose connection relationships are clear from the description may be omitted from the illustration.

[0016] First Embodiment A first embodiment of the present invention will be described with reference to FIGS.

[0017] FIG. 1 is a perspective view showing the appearance of a hydraulic excavator shown as an example of a work machine in this embodiment.

[0018] In FIG. 1, the hydraulic excavator 1 comprises a lower traveling body 1C, an upper rotating body 1B that is rotatably attached to the lower traveling body 1C via a rotating device 4 and that forms a vehicle body together with the lower traveling body 1C, and a front working machine 1A that is attached to the front of the upper rotating body 1B and forms a working device.

[0019] The front working implement 1A is generally composed of a boom 8 as a structure attached to the front part of the upper rotating structure 1B so as to be rotatable in the vertical direction, an arm 9 as a structure attached to the tip (rear section) of the boom 8 so as to be rotatable in the vertical direction, a bucket 10 as a structure attached to the tip (rear section) of the arm 9 so as to be rotatable in the vertical direction, a bucket link 13 rotatably attached to the arm 9 and the bucket 10, a boom cylinder 5 connected to the upper rotating structure 1B and the boom 8 and changing the rotation angle of the boom 8 relative to the upper rotating structure 1B by driving the boom 8 in the vertical direction relative to the upper rotating structure 1B, an arm cylinder 6 connected to the boom 8 and the arm 9 and changing the rotation angle of the arm 9 relative to the boom 8 by driving the arm 9 in the vertical direction relative to the boom 8, and a bucket cylinder 7 connected to the arm 9 and the bucket link 13 and changing the rotation angle of the bucket 10 relative to the arm 9 via the bucket link 13. The arm 9 is provided in front of the bucket 10 as a structure, and the boom 8 is provided in front of the arm 9.

[0020] The lower traveling body 1C is equipped with left and right crawler-type traveling devices 3 (only the left traveling device 3 is shown in FIG. 1), and the left and right traveling devices 3 are driven by left and right traveling motors 3a (only the left traveling motor 3a is shown in FIG. 1), enabling the hydraulic excavator 1 to be moved to a desired position.

[0021] The slewing device 4 is equipped with a slewing motor 11 that changes the rotation angle of the lower traveling body 1C and the upper slewing body 1B.

[0022] A cabin 12 forming a driver's cab is disposed beside the front work implement 1A at the front of the upper rotating structure 1B. A controller 22 (control device) that controls the overall operation of the hydraulic excavator 1 is disposed behind the driver's seat in the cabin 12 where the operator sits. Furthermore, on the left and right sides in front of the driver's seat in the cabin 12, operation devices 2 are disposed that, when operated by the operator, generate operation signals that command the operation (speed and direction) of the boom 8, arm 9, bucket 10, and upper rotating structure 1B. Furthermore, an operation device that generates operation signals that command the operation (speed and direction) of the left and right traveling devices 3 is also disposed in front of the driver's seat.

[0023] The boom 8, arm 9, and bucket 10 are provided with a boom angle / angular velocity detecting device 20a, an arm angle / angular velocity detecting device 20b, and a bucket angle / angular velocity detecting device 20c, respectively, which detect angles (operating angles) relative to the horizontal plane and angular velocities due to operation. Note that the bucket angle / angular velocity detecting device 20c may be installed on the bucket link 13 instead of the bucket 10. Hereinafter, the boom angle / angular velocity detecting device 20a, the arm angle / angular velocity detecting device 20b, and the bucket angle / angular velocity detecting device 20c may be collectively referred to as the angle / angular velocity detecting device 20.

[0024] The angle / angular velocity detection device 20 is, for example, an IMU (Inertial Measurement Unit). However, the angle / angular velocity detection device 20 may be any device capable of measuring and calculating angles and angular velocities, such as a potentiometer / gyro device that directly measures angles and angular velocities, a device that performs numerical differentiation and integration of the measured angular velocities, or a combination thereof.

[0025] The boom cylinder 5 is provided with a pressure sensor 25a that detects the pressure on the bottom side (bottom pressure) and the pressure on the rod side (rod pressure) of the boom cylinder 5. Furthermore, the arm cylinder 6 is provided with a pressure sensor 25b that detects the pressure on the bottom side (bottom pressure) and the pressure on the rod side (rod pressure) of the arm cylinder 6. Similarly, the bucket cylinder 7 is provided with a pressure sensor 25c that detects the pressure on the bottom side (bottom pressure) and the pressure on the rod side (rod pressure) of the bucket cylinder 7.

[0026] The pressure sensors 25a, 25b, 25c, together with a functional section (not shown) provided in the controller 22, constitute a boom overload detection device 61a, an arm overload detection device 61b, and a bucket overload detection device 61c that detect overload states of the boom cylinder 5, the arm cylinder 6, and the bucket cylinder 7, respectively, from the thrust of the boom cylinder 5, the arm cylinder 6, and the bucket cylinder 7 and the pressure resistance specifications as equipment performance of these cylinders, or from limit values ​​(pressures) on the hydraulic circuits that drive these cylinders. Hereinafter, the boom overload detection device 61a, the arm overload detection device 61b, and the bucket overload detection device 61c may be collectively referred to as the overload detection device 61.

[0027] The overload detection device 61 determines whether the boom cylinder 5, arm cylinder 6, and bucket cylinder 7 are in an overload state based on the following (Equation 1) and (Equation 2), and determines that an overload state exists if the above (Equation 1) or (Equation 2) is satisfied.

[0028] P ｉ＿ｂｔｍ ≧P ｓａｔ＿ｉ ...(Formula 1) P ｉ＿ｒｏｄ ≧P ｓａｔ＿ｉ ...(Formula 2)

[0029] In the above (Formula 1) and (Formula 2), P ｉ＿ｂｔｍ , P ｉ＿ｒｏｄ is the pressure measured by the pressure sensor 25, and P ｓａｔ＿ｉ indicates the pressure resistance specification, and i indicates which of the boom cylinder 5, arm cylinder 6, and bucket cylinder 7 is targeted. For example, P ｂｍ＿ｂｔｍ ≧P ｓａｔ＿ｂｍ (see (Equation 1) above), or P ｂｍ＿ｒｏｄ ≧P ｓａｔ＿ｂｍ (see Equation 2 above) is satisfied, it is determined that the bottom side of the boom cylinder 5 is in an overload state. Note that, when a relief valve (a so-called overload relief valve) connected to the bottom side or the rod side is provided in the hydraulic circuit configuration, the pressure-resistant specification used for calculations in the overload detection device 61 may be the lower of the pressure-resistant specification or the relief valve set pressure, which is the limit value on the hydraulic circuit.

[0030] FIG. 2 is a functional block diagram showing the processing functions of the controller together with the related configuration.

[0031] 2 , the controller 22 has an operation flow rate calculation unit 202 that calculates an operation flow rate, which is the amount of pressure oil to be supplied to the boom cylinder 5, arm cylinder 6, and bucket cylinder 7, based on the operation state (operation direction, operation amount) of the operation device 2; a stopped state calculation unit 203 that determines whether or not each of the structures, such as the boom 8, arm 9, and bucket 10, operated by the boom cylinder 5, arm cylinder 6, and bucket cylinder 7 (hereinafter, sometimes collectively referred to as actuators), and the structure preceding them (for example, the boom 8 relative to the arm 9) are in a stopped state, based on the angular velocity detected by the angle / angular velocity detection device 20; and an assist unit 201 that calculates and outputs command flow rates for the actuators 5, 6, and 7, based on the operation flow rate from the operation flow rate calculation unit 202, the overload state from the overload detection device 61 (information indicating whether or not an overload state exists), the angle from the angle / angular velocity detection device 20, and the stop state (information indicating whether or not a stop state exists) from the stop state calculation unit 203.

[0032] The operation flow rate calculated by the operation flow rate calculation unit 202 only needs to include information regarding the operation flow rate, and the operation flow rate may be instructed from another external system, such as a remote control device or an automatic system on a server.

[0033] FIG. 3 is a functional block diagram showing the processing functions of the assist unit of the controller together with the related configuration.

[0034] In FIG. 3 , the assist unit 201 includes an upward direction designation unit 301, a toe position calculation unit 302, a fully overloaded operable direction calculation unit 303, a corrected actuator calculation unit 304, an overloaded operable direction calculation unit 305, an operating direction determination unit 306, and a command flow rate calculation unit 307.

[0035] The upward direction designation unit 301 designates the opposite direction of the gravity vector (vertically upward direction), for example, by prior input to the operation device 2. Note that instead of prior input by the operation device 2, for example, an inertial measurement unit (IMU) may be disposed on the upper rotating body 1B, and the direction corresponding to the upper part of the upper rotating body 1B may be designated by automatic input based on the detection results.

[0036] The toe position calculation unit 302 calculates the position coordinates of the toe of the bucket 10 in the vehicle body coordinate system based on the detection results (angles) from the angle / angular velocity detection device 20 .

[0037] The fully overloaded operable direction calculation unit 303 calculates a fully overloaded target speed vector that indicates the target direction and target speed for the toe movement of the bucket 10 during a fully overloaded state, based on the specification (vertical upward direction) from the upward direction specification unit 301 and the calculation result (toe coordinates) from the toe position calculation unit 302.

[0038] The correction actuator calculation unit 304 determines which actuators 5, 6, and 7 should correct the amount of pressure oil supplied by correcting the operating flow rate based on the calculation results from the stopped state calculation unit 203 (information indicating whether the structure and the structure preceding it are in a stopped state) and the detection results from the overload detection device 61 (information indicating whether there is an overload).

[0039] The operable direction calculation unit 305 during overload calculates an overload target velocity vector that indicates the target direction and target velocity for movement of the toe of the bucket 10 during an overload, based on the detection result (angle) from the angle / angular velocity detection device 20 and the calculation result (information on the actuator to be corrected) from the correction actuator calculation unit 304.

[0040] The operation direction determination unit 306 calculates a target speed vector for the tip of the bucket 10 based on the calculation result from the full overload operable direction calculation unit 303 (full overload target speed vector), the calculation result from the overload operable direction calculation unit 305 (overload target speed vector), and the calculation result from the correction actuator calculation unit (information on the actuator to be corrected).

[0041] Command flow rate calculation unit 307 calculates and determines command flow rates to actuators 5, 6, and 7 based on the calculation result (target speed vector) from operation direction determination unit 306, the calculation result (operation flow rate) from operation flow rate calculation unit 202, and the detection result (angle) from angle / angular speed detection device 20, and outputs the command flow rate to actuators 5, 6, and 7. Specifically, the command flow rate is calculated by converting the target speed vector of the tip of bucket 10 from operation direction determination unit 306 into a target speed of the cylinder using a Jacobian matrix or the like.

[0042] FIG. 4 is a flowchart showing the processing contents of the controller.

[0043] In FIG. 4, the controller 22 first calculates which actuators 5, 6, and 7 satisfy the condition (condition A) that each of the actuators 5, 6, and 7 is in an overload state and that the structures (boom 8, arm 9, bucket 10) corresponding to each of the actuators 5, 6, and 7 are in a stopped state (step S100).

[0044] Next, it is determined whether or not there is any actuator that satisfies condition A (step S110), and if the determination result is YES, that is, if all of the actuators (boom cylinder 5, arm cylinder 6, and bucket cylinder 7) do not satisfy condition A, the calculation result (operated flow rate) of the operated flow rate calculation unit 202 is output as a command flow rate to the actuators 5, 6, and 7 without correction (step S111), and the processing ends. In the processing of step S110, if there is no actuator that satisfies condition A, the operated flow rate is not corrected (see step S111), thereby improving the efficiency of the processing.

[0045] Furthermore, if the determination result in step S110 is NO, i.e., if it is determined that there is an actuator that satisfies condition A, it is determined whether the actuator that has been determined to satisfy condition A has continuously satisfied condition A for a predetermined time (predetermined time) or more (in other words, whether a predetermined time or more has passed since the actuator satisfied condition A) (step S120). The processing of step S120 is performed because if the predetermined time has passed since the actuator satisfied condition A (YES), the state of the actuator will not improve even if the operation flow rate is corrected, so by interrupting the correction of the operation flow rate and notifying (displaying) the operator, the operator is prompted to check the current situation and take action, thereby improving the efficiency of processing.

[0046] If the determination result in step S120 is YES, that is, if it is determined that condition A has been continuously satisfied for a predetermined time or more (that is, a predetermined time has passed since the actuator satisfied condition A), the calculation result (operated flow rate) of the operated flow rate calculation unit 202 is output as a command flow rate to the actuators 5, 6, and 7 without being corrected, and a message that correction of the operated flow rate has been suspended is displayed on the display device 23 to notify the operator (step S121), and the process ends. Note that returning to the process of the next step S100 after the suspension of the process of step S121 can be triggered by all operated flow rates becoming 0 (zero) (by placing the operating device in neutral), by raising the lock lever, by turning the key off, or the like.

[0047] Furthermore, if the determination result in step S120 is NO, i.e., if it is determined that an actuator that satisfies condition A has not satisfied that condition A for a predetermined time or longer (i.e., the predetermined time has not passed since the actuator satisfied condition A), it is determined whether all actuators satisfy condition A (step S130).

[0048] If the determination result in step S130 is YES, that is, if it is determined that all actuators satisfy condition A, all actuators are selected as actuators for which the operation flow rates are to be corrected, command flow rates obtained by correcting the operation flow rates of all actuators are calculated and output to actuators 5, 6, and 7 (step S131), and the process ends. Also, if the determination result in step S130 is NO, the process proceeds to step S140, as described below, where actuators that do not satisfy condition A are selected as actuators to be corrected, the operation flow rates of those actuators are corrected, and the process ends.

[0049] FIG. 5 is a diagram illustrating the basic concept of calculating a command flow rate by correcting an operation flow rate.

[0050] In FIG. 5, the tip position x of the bucket 10 at a certain time n is ｎ , toe position x ｎ The tip position x of the bucket 10 at time n-1 before reaching the tip position x ｎ－１ , the direction in which the tip of the bucket 10 has already passed at time n is represented by a vector X=x ｎ－１ -x ｎ , the vertically upward direction specified by the upward direction specifying unit 301 is indicated by a vector v. Note that the toe position x ｎ , x ｎ－１ The subscript n in the above expression defines a variable indicating the clock tick time of the controller 22, and changes as follows: ..., n-1, n, n+1, ... (n is a positive integer), but it is sufficient if the past toe position x can be referenced, and for example, it may be possible to go back a predetermined time or distance.

[0051] As shown in FIG. 5, in step S131 of FIG. 4, for example, the toe position x of the bucket 10 ｎThe direction of travel (vector x) is the opposite direction (the position x that has already passed) ｎ－１ The command flow rate is calculated by correcting the operation flow rates of the boom cylinder 5, arm cylinder 6, and bucket cylinder 7 so that the command flow rate is between the vertically upward direction (vector v) specified by the upward direction specifying unit 301 (i.e., the range indicated by diagonal lines in FIG. 5 ) and the vertically upward direction (vector v) specified by the upward direction specifying unit 301 (i.e., the range indicated by diagonal lines in FIG. 5 ). Specifically, calculation of the command flow rate by correcting the operation flow rate has as one of its purposes operation of the front working implement 1A so as to reduce the load on each of the actuators 5, 6, 7 (so as to eliminate an overload state), and the command flow rate is calculated (i.e., the operation flow rate is corrected) so that the direction of movement of the point of application of the force of the front working implement 1A with respect to an excavation target such as the ground (here, the toe position of the bucket 10) is a direction in which excavation has been completed and there is no soil or sand, i.e., the range indicated by diagonal lines in FIG. 5 . In addition, taking into account the fact that there is a certain correlation between the excavation load and the excavation depth, the operating flow rate of each actuator 5, 6, 7 may be corrected to calculate the command flow rate so that the direction of movement of the toe position of the bucket 10 is in a direction that shallows the excavation depth, i.e., a direction between the perpendicular direction to the ground surface of the excavation target and the vertically upward direction.

[0052] 4 is NO, i.e., if there is an actuator that does not satisfy condition A, the operated flow rates for the actuators that do not satisfy condition A are corrected to calculate command flow rates, which are output to actuators 5, 6, and 7 (step S140), and the process ends. Specifically, if there is an actuator that does not satisfy condition A, i.e., if at least one of boom cylinder 5, arm cylinder 6, and bucket cylinder 7 does not satisfy condition A, the operated flow rate calculated by operated flow rate calculation unit 202 is output as a command flow rate to the actuator that satisfies condition A. Furthermore, for the actuators that do not satisfy condition A, the operated flow rate is corrected to calculate a command flow rate so that the traveling direction of the bucket toe position by the actuators that do not satisfy condition A is perpendicular to the traveling direction of the toe position by the actuators that satisfy condition A, and the command flow rate is output to the actuators that do not satisfy condition A.

[0053] 4, i.e., the method for determining the movement direction (assist direction) of the toe position of the bucket 10 in calculating the command flow rate by correcting the operation flow rate. Considering the front attachment 1A exemplified in this embodiment, possible states in step S140 are a case where multiple (two) actuators satisfy condition A and a case where a single (one) actuator satisfies condition A.

[0054] 6 to 8 are diagrams for explaining an example of a method for determining the assist direction when a single actuator satisfies condition A, and illustrate a case where only the boom cylinder satisfies condition A. In FIGS. 6 to 8, BM schematically indicates the boom 8, AM indicates the arm 9, and BK indicates the bucket 10.

[0055] In the front work implement 1A, the movement of the toe of the bucket 10 caused by a certain actuator is movement around the axis rotated by the actuator. Therefore, as shown in Figure 6, when a single actuator satisfies condition A, the target speed vector of the toe of the bucket 10 caused by the actuator that satisfies condition A is a vector connecting the rotation axis on the upstream side of the structure operated by the actuator that satisfies condition A (in the case of a boom 8, the base end side of the boom 8) and the toe of the bucket 10.

[0056] In this case, assistance is provided by other actuators that do not satisfy condition A so as to move the tip of the bucket 10 in a direction closest to perpendicular to the target velocity vector of the tip of the bucket 10 by the actuators that satisfy condition A.

[0057] As shown in Figure 6, when only the boom cylinder 5 satisfies condition A, there are two solutions for the direction closest to vertical: +90 (deg) and -90 (deg) with respect to the above-mentioned vector (see Figure 6). Which of these two solutions is to be selected can be done, for example, by the following two selection methods.

[0058] A first selection method (hereinafter referred to as selection method 1) involves selecting an intervention in a predetermined direction. In this case, it is set in advance whether to select +90 (deg) or −90 (deg) for each of the actuators (boom 8, arm 9, bucket 10) that satisfy condition A.

[0059] A second selection method (hereinafter referred to as selection method 2) involves selecting a direction to match the current movement direction. In this case, for example, when the boom cylinder 5 satisfies condition A, the angular velocities of the arm 9 and bucket 10 that will intervene are measured, a directional velocity vector of the toe is calculated based on the angular velocities of the arm 9 and bucket 10 (see FIG. 7), and the solution with the smaller angle with the directional velocity vector of the toe is selected from the two solutions (see FIG. 8). Selecting the intervention direction using selection method 2 reduces changes to the current movement, making it possible to provide assistance that is less likely to cause discomfort to the operator.

[0060] Selection method 1 and selection method 2 can also be applied to the case where the single actuator that satisfies condition A is the arm 9 or the bucket 10.

[0061] 9 to 12 are diagrams for explaining an example of a method for determining the assist direction when multiple actuators satisfy condition A, and illustrate a case where the boom cylinder and arm cylinder satisfy condition A. In FIGS. 9 to 12, BM schematically indicates the boom 8, AM indicates the arm 9, and BK indicates the bucket 10.

[0062] As shown in FIG. 9 , when multiple actuators satisfy condition A, the target velocity vector of the tip of the bucket 10 by the actuators that satisfy condition A is calculated for each of the multiple actuators that satisfy condition A.

[0063] Specifically, as shown in FIGS. 9 and 10, the boom cylinder 5 operates in the direction v ＢＭ , and the direction v by the arm cylinder 6 ＡＭThere are two directions of movement, and the other actuators that do not satisfy condition A assist in moving the tip of the bucket 10 in the direction that minimizes the sum of the angles formed by each of these two vectors and the velocity vector at which the tip of the bucket can be moved by the remaining actuator (here, the bucket cylinder 7).

[0064] When the boom cylinder 5 and the arm cylinder 6 satisfy the condition A, the velocity vector in the direction in which the toe can move by the bucket cylinder 7 is the vector v ＢＫ１ and the vector v in the negative direction (operable direction (2)) ＢＫ２ There are two types (see FIG. 10).

[0065] As shown in FIGS. 11 and 12, the angle between the vectors is θ ＢＭ１ , θ ＢＭ２ , θ ＡＭ１ , θ ＡＭ２ The angle between these is calculated by the following formulas (3) to (6) using the function f calculated by the definition of the dot product of vectors and the law of cosines.

[0066] θ ＢＭ１ = f(v ＢＫ１ , v ＢＭ ) ... (Formula 3) θ ＢＭ２ = f(v ＢＫ２ , v ＢＭ ) ... (Formula 4) θ ＡＭ１ = f(v ＢＫ１ , v ＡＭ ) ... (Formula 5) θ ＡＭ２ = f(v ＢＫ２ , v ＡＭ ) ... (Formula 6)

[0067] The assist operation is performed by setting a target speed vector according to the relationship between the angles formed.

[0068] Specifically, when the following (Equation 7) is satisfied, the vector v ＢＫ１ Let be the target velocity vector.

[0069] θ ＢＭ１ +θ ＡＭ１ <θ ＢＭ２ +θ ＡＭ２ ...(Formula 7)

[0070] Furthermore, when the following (Equation 8) is satisfied, the vector v ＢＫ２ Let be the target velocity vector.

[0071] θ ＢＭ１ +θ ＡＭ１ >θ ＢＭ２ +θ ＡＭ２ ...(Formula 8)

[0072] In addition, when the following (Equation 9) is satisfied, the vector v ＢＫ１ and vector v ＢＫ２ Which of the above vectors is to be the target velocity vector is set in advance, and the set vector is set as the target velocity vector.

[0073] θ ＢＭ１ +θ ＡＭ１ = θ ＢＭ２ +θ ＡＭ２ ...(Formula 9)

[0074] The above-described method for setting the target velocity vector can be similarly applied to the case where the multiple actuators that satisfy condition A are the boom 8 and the bucket 10, or the case where the arm 9 and the bucket 10.

[0075] In the present embodiment configured as described above, it is possible to properly determine whether the front working implement (working implement) 1A is in a stopped state due to an overload condition based on the detection results of the angle / angular velocity detection device 20, and to properly determine whether correction is necessary. In addition, by correcting the operating flow rate of an actuator that is different from the actuator that is in an overloaded and stopped state, it is possible to eliminate the overload condition while maintaining as much excavation force as possible, and to perform excavation operations more efficiently.

[0076] Second Embodiment A second embodiment of the present invention will be described with reference to Figures 13 to 16. In this embodiment, the same members as those in the first embodiment will be described using the same reference numerals, and the description will be omitted as appropriate.

[0077] FIG. 13 is a functional block diagram showing the processing functions of the assist unit of the controller according to this embodiment together with the related configuration.

[0078] In FIG. 13, the assist unit 201A has an upward direction designation unit 301, a toe position calculation unit 302, a fully overloaded operable direction calculation unit 303, a corrected actuator calculation unit 304, an overloaded operable direction calculation unit 305, a time norm relationship recording unit 701, an operating direction determination unit 306A, and a command flow rate calculation unit 307.

[0079] The upward direction designation unit 301 designates the opposite direction of the gravity vector (vertically upward direction), for example, by prior input to the operation device 2. Note that instead of prior input by the operation device 2, for example, an inertial measurement unit (IMU) may be disposed on the upper rotating body 1B, and the direction corresponding to the upper part of the upper rotating body 1B may be designated by automatic input based on the detection results.

[0080] The toe position calculation unit 302 calculates the position coordinates of the toe of the bucket 10 in the vehicle body coordinate system based on the detection results (angles) from the angle / angular velocity detection device 20 .

[0081] The fully overloaded operable direction calculation unit 303 calculates a fully overloaded target speed vector that indicates the target direction and target speed for the toe movement of the bucket 10 during a fully overloaded state, based on the specification (vertical upward direction) from the upward direction specification unit 301 and the calculation result (toe coordinates) from the toe position calculation unit 302.

[0082] The correction actuator calculation unit 304 determines the actuators 5, 6, and 7 for which the operating flow rate should be corrected based on the calculation result from the stopped state calculation unit 203 (information indicating whether or not the actuator is in a stopped state) and the detection result from the overload detection device 61 (information indicating whether or not the actuator is overloaded).

[0083] The operable direction calculation unit 305 during overload calculates an overload target velocity vector that indicates the target direction and target velocity of the movement of the tip of the bucket 10 during overload, based on the detection result (angle) from the angle / angular velocity detection device 20 and the calculation result (information on the actuator that corrects the operation flow rate) from the correction actuator calculation unit 304.

[0084] The time norm relationship recording unit 701 records a norm calculation table that predetermines the relationship between the elapsed time since the condition of an overloaded state and a stopped state (condition A) was satisfied and the norm (magnitude) of the target velocity vector of the tip of the bucket 10.

[0085] FIG. 14 is a diagram showing an example of a norm calculation table that defines the relationship between the elapsed time and the norm when the arm cylinder satisfies the condition A.

[0086] As shown in Fig. 14, the norm calculation table is set so that the norm of the target velocity vector of the tip of the bucket 10 increases as the elapsed time (t) from when the condition A is satisfied increases. For example, ｎ When the norm of the target velocity vector is k ｎ As the elapsed time increases, ｍ When this happens, the norm of the target velocity vector also increases, and k ｍ 14 illustrates an example in which the norm of the target speed increases in proportion to the increase in elapsed time, but the norm calculation table may be set so that the norm of the target speed increases as the elapsed time increases, and for example, a norm calculation table showing a curved relationship rather than a linear (proportional) relationship may be set.

[0087] The operation direction determination unit 306A calculates a target speed vector for the tip of the bucket 10 based on the calculation result from the full overload operable direction calculation unit 303 (full overload target speed vector), the calculation result from the overload operable direction calculation unit 305 (overload target speed vector), the calculation result from the correction actuator calculation unit (information on the actuator that corrects the operation flow rate), and the norm calculation table in the time norm relationship recording unit 701.

[0088] The operation direction determination unit 306A records the maintenance time since the actuator determined to be the correction target by the correction actuator calculation unit 304 became an operated state (True state), and increases the norm of the target velocity vector of the tip of the bucket 10 according to the elapsed time based on the norm calculation table. Note that if the target actuator becomes a non-operated state (False state), the count of the maintenance time is reset.

[0089] 15 is a diagram showing the target velocity vector of the bucket tip after the operation flow rate is corrected when the norm calculation table is applied. In FIG. 15, BM schematically indicates the boom 8, AM indicates the arm 9, and BK indicates the bucket 10.

[0090] 15, the target velocity vector is set so that the norm tm when the elapsed time tm is greater than the norm kn when the elapsed time tn is reached. In other words, it can be said that the magnitude of the target velocity vector after correction of the operating flow rate of the actuator increases according to the time that has elapsed since the actuator entered an overloaded and stopped state.

[0091] Command flow rate calculation unit 307A calculates and determines command flow rates to actuators 5, 6, and 7 based on the calculation result (target speed vector) from operation direction determination unit 306, the calculation result (operation flow rate) from operation flow rate calculation unit 202, and the detection result (angle) from angle / angular speed detection device 20, and outputs the command flow rate to actuators 5, 6, and 7. Specifically, the command flow rate is calculated by converting the target speed vector of the tip of bucket 10 from operation direction determination unit 306 into a target speed of the cylinder using a Jacobian matrix or the like.

[0092] The other configurations are the same as those of the first embodiment.

[0093] The present embodiment configured as above can also achieve the same effects as the first embodiment.

[0094] In addition, the amount of pressure oil supplied to the actuator (operating flow rate) is corrected to increase depending on the elapsed time since condition A of an overloaded state and a stopped state is met, so that the stopped state of the structure due to an overload can be resolved more quickly.

[0095] <Notes> The present invention is not limited to the above-described embodiments, and includes various modifications and combinations within the scope of the gist thereof. Furthermore, the present invention is not limited to those including all of the configurations described in the above-described embodiments, and also includes those in which some of the configurations are omitted. Furthermore, the above-described configurations, functions, etc. may be realized in part or in whole by designing them as, for example, integrated circuits. Furthermore, the above-described configurations, functions, etc. may be realized in software by a processor interpreting and executing a program that realizes each function.

[0096] 1... Hydraulic excavator, 1A... Front working machine (working device), 1B... Upper rotating body, 1C... Lower traveling body, 2... Operating device, 3... Traveling device, 3a... Traveling motor, 4... Swinging device, 5... Boom cylinder, 6... Arm cylinder, 7... Bucket cylinder, 8... Boom, 9... Arm, 10... Bucket, 11... Swing motor, 12... Cabin, 13... Bucket link, 20a, 20b, 20c... Angle / angular velocity detection device, 22... Controller, 23... Display device, 25a, 25b, 25c...Pressure sensors, 61a, 61b, 61c...Overload detection devices, 201, 201A...Assist unit, 202...Operation flow rate calculation unit, 203...Stop state calculation unit, 301...Upward direction designation unit, 302...Toe position calculation unit, 303...Operable direction calculation unit under full overload, 304...Corrected actuator calculation unit, 305...Operable direction calculation unit under overload, 306, 306A...Operation direction determination unit, 307, 307A...Command flow rate calculation unit, 701...Time norm relationship recording unit

Claims

1. A working device consisting of a plurality of structures; A plurality of actuators each driving a plurality of the structures of the working device; an overload detection device that detects an overload state of each of the actuators; an angle / angular velocity detection device that detects the motion angles and angular velocities of the plurality of structures of the working device; An operating device for operating the actuators; A control device that controls an amount of pressure oil supplied to the plurality of actuators in accordance with an operation amount of the operating device, The control device includes: determining whether or not the plurality of actuators are in an overload state based on a detection result of the overload detection device, and determining whether or not the plurality of actuators are in a stopped state based on a detection result of the angle / angular velocity detection device; a control unit for controlling a supply of pressure oil to an actuator selected from among the plurality of actuators, the control unit correcting an amount of pressure oil supplied to the actuator selected based on a result of the determination when the actuator is determined to be overloaded and stopped.

2. 2. The work machine according to claim 1, The control device includes: a control unit for controlling a supply of pressure oil to an actuator other than the actuator that is overloaded and stopped when it is determined that some of the actuators are overloaded and stopped.

3. 2. The work machine according to claim 1, The control device includes: a supply amount of pressure oil supplied to all of the actuators is corrected when it is determined that all of the actuators among the plurality of actuators are in an overloaded state and stopped.

4. A working machine according to claim 2 or 3, The control device, when it is determined that an actuator is overloaded and stopped, corrects the amount of pressure oil supplied to the actuator if the time that the actuator remains overloaded and stopped is shorter than a predetermined time.

5. 2. The work machine according to claim 1, a velocity vector of the tip of the working device after the supply amount of pressure oil supplied to the actuator by the control device is corrected, the velocity vector being oriented approximately perpendicular to a directional vector in which the tip of the working device moves due to an actuator that is in an overloaded state and at a stop.

6. 2. The work machine according to claim 1, The control device includes: a supply amount of pressure oil supplied to the actuator is corrected so that a magnitude of a velocity vector of the tip of the working device after the supply amount of pressure oil supplied to the actuator is corrected increases according to the elapsed time since the actuator was in an overloaded state and stopped.