Work Machine

Abstract

A controller for a work machine according to the present invention calculates a required velocity of a hydraulic actuator on the basis of an operation signal, calculates a first estimated velocity of the hydraulic actuator on the basis of a detected value from a first detection device that detects operation information of a member to be driven, calculates a second estimated velocity of the hydraulic actuator on the basis of a detected value from a second detection device that detects the flow rate of a direction control valve, calculates an arbitrated velocity by arbitrating the first estimated velocity and the second estimated velocity according to the drive state of the hydraulic actuator, and controls the direction control valve on the basis of the difference between the required velocity and the arbitrated velocity. The calculation of the arbitrated velocity is arbitrated so that the influence of the second estimated velocity becomes greater than the influence of the first estimated velocity when the hydraulic actuator starts to operate, and so that the influence of the first estimated velocity becomes greater than the influence of the second estimated velocity when the drive of the hydraulic actuator approaches a steady state.

Description

[Technical field]

[0001] The present invention relates to a work machine, and more particularly to a work machine that controls the drive of a hydraulic actuator. [Background technology]

[0002] In a work machine such as a hydraulic excavator, a working device configured by connecting a plurality of driven members (link members) such as a boom, an arm, and a bucket is driven by a plurality of hydraulic actuators. As a technology for improving the work efficiency of a hydraulic excavator, an information-based construction system is known that uses information and communication technology to automatically or semi-automatically operate the working device to perform work such as finish excavation. In the information-based construction system, it is required to accurately control the bucket tip (toe) of the working device in order to improve the finishing accuracy of the construction surface relative to the design surface. Therefore, in a hydraulic excavator, it is necessary to highly accurately control the driving speed of each hydraulic actuator that operates the working device and the flow rate of pressure oil flowing into each hydraulic actuator (hereinafter sometimes referred to as meter-in flow rate).

[0003] As an example of a technique for controlling the operation of a working implement with high accuracy, for example, the technology described in Patent Document 1 is known. In the construction machine described in Patent Document 1, feedback control is performed using the motion state quantity (speed and position) of the composite center of gravity of the working implement obtained from actual measurement values ​​of sensors that measure the speed, angle, position, etc. of each member of the working implement (boom, arm, etc.) and the drive torque of the hydraulic actuator obtained from actual measurement values ​​of the stroke length, pressure, etc. of each hydraulic actuator measured by the sensors, thereby controlling the motion state quantity of the composite center of gravity of the working implement to follow a target value.

[0004] As another example of a technique for controlling the operation of a work implement with high accuracy, for example, the technique described in Patent Document 2 is known. In the excavator described in Patent Document 2, the flow rate of hydraulic oil passing through the control valve (passing flow rate) is estimated using the displacement of a spool of the control valve detected by a spool displacement sensor attached to the control valve that controls the flow rate of hydraulic oil flowing from the hydraulic pump to the hydraulic actuator, and the estimated value of the passing flow rate of the control valve is fed back, thereby controlling the passing flow rate of the control valve (i.e., the meter-in flow rate of the hydraulic actuator) to follow a target value. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-033815 A [Patent Document 2] JP 2019-157521 A Summary of the Invention [Problem to be solved by the invention]

[0006] When performing control to make the speed of the hydraulic actuator follow a target value by feeding back the speed of the hydraulic actuator derived directly from the actual measured value of a sensor (for example, a posture sensor capable of detecting the posture of the working device) that measures the speed, angle, position, etc. of the working device, as in the control of the construction machine described in Patent Document 1, the control amount (correction amount) is determined in principle according to the actual driving state of the hydraulic actuator (working device). For this reason, when an operation with a large operation amount and a fast rise time is input to the operating device, the speed of the hydraulic actuator obtained from the actual measured value of the sensor will deviate significantly from the target value according to the operation amount of the operating device when the working device starts to move due to the effect of the response delay of the hydraulic actuator caused by the inertia of the working device. In this case, the correction amount of the feedback control becomes excessive, and the hydraulic actuator is likely to jump out or hunt. In other words, when feeding back the speed of the hydraulic actuator derived directly from the actual measured value of the sensor, there is a concern that the stability of the control of the hydraulic actuator will be impaired in a situation where the fed back speed of the hydraulic actuator deviates significantly from the target value, such as when the hydraulic actuator starts to move.

[0007] In contrast, when control is executed to make the meter-in flow rate follow a target value by feeding back the flow rate through the control valve (the meter-in flow rate of the hydraulic actuator) estimated based on the detection value of the spool displacement sensor, as in the control of the excavator described in Patent Document 2, it is possible to predict the future drive state of the hydraulic actuator and determine the control amount (correction amount). Therefore, even if an operation with a large operation amount and a fast rise time is input, it is possible to correct the meter-in flow rate before the hydraulic actuator actually starts moving, and it is possible to suppress the popping out and hunting of the hydraulic actuator more than in the case of the control described in Patent Document 1.

[0008] However, since the estimated value of the flow rate passing through the control valve (the meter-in flow rate of the hydraulic actuator) using the detection value of the spool displacement sensor uses a fluid dynamic relational expression, the estimation accuracy is likely to decrease due to the influence of disturbances such as oil temperature and cavitation, and the detection accuracy of the sensor. Therefore, when the actual driving state of the hydraulic actuator approaches a target value, the accuracy of feedback control using the meter-in flow rate of the hydraulic actuator estimated based on the detection value of the spool displacement sensor tends to be inferior to the accuracy of feedback control using the speed of the hydraulic actuator obtained directly from the actual measurement value of the sensor, such as the control described in Patent Document 1.

[0009] The present invention has been made to solve the above-mentioned problems, and has as its object to provide a work machine that enables high-precision control of a hydraulic actuator while ensuring stability of control when the hydraulic actuator starts to move. [Means for solving the problem]

[0010] The present application includes a plurality of means for solving the above-mentioned problems. For example, in a work machine including a hydraulic pump that discharges pressure oil, a hydraulic actuator that is driven by the pressure oil supplied from the hydraulic pump, a directional control valve that controls the flow of the pressure oil supplied from the hydraulic pump to the hydraulic actuator, a driven member that operates by driving the hydraulic actuator, an operation device that outputs an operation signal that instructs the operation of the driven member, a first detection device that detects operation information of the driven member, a second detection device that detects information related to the flow rate of the pressure oil supplied to the hydraulic actuator via the directional control valve, and a controller that controls the operation of the hydraulic pump and the directional control valve, the controller calculates a required speed of the hydraulic actuator based on the operation signal of the operation device, calculates a speed of the hydraulic actuator estimated based on a detection value of the first detection device as a first estimated speed, and calculates a speed of the hydraulic actuator estimated based on a detection value of the first detection device as a first estimated speed. the speed of the hydraulic actuator estimated based on the detection value of the first estimated speed is calculated as a second estimated speed, the first estimated speed and the second estimated speed are arbitrated in accordance with the drive state of the hydraulic actuator to calculate an arbitrated speed, and the drive of the hydraulic pump and the directional control valve is controlled based on the deviation between the required speed and the arbitrated speed, and the calculation of the arbitrated speed by the controller is characterized in that, when it is possible to determine based on the first estimated speed that the drive state of the hydraulic actuator is a starting state, the controller arbitrates such that the influence on the second estimated speed is greater than the influence on the first estimated speed, and when it is possible to determine based on the first estimated speed that the drive state of the hydraulic actuator has exceeded a predetermined state and is approaching a steady state, the controller arbitrates such that the influence on the first estimated speed is greater than the influence on the second estimated speed. Effect of the Invention

[0011] According to the present invention, when the drive state of the hydraulic actuator is starting to move, the drive of the hydraulic actuator is controlled using the second estimated speed that predicts the future drive state of the hydraulic actuator, so that it is possible to suppress the popping out and hunting of the hydraulic actuator caused by the response delay of the hydraulic actuator due to the inertia of the driven member. Also, when the drive of the hydraulic actuator is approaching a steady state, the drive of the hydraulic actuator is controlled using the first estimated speed derived based on the actual drive state of the hydraulic actuator, so that the drive of the hydraulic actuator can be controlled with higher accuracy than when the second estimated speed, which has lower estimation accuracy than the first estimated speed, is used. In other words, it is possible to control the hydraulic actuator with high accuracy while ensuring the stability of control when the hydraulic actuator starts to move. Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0012] [Figure 1] 1 is an external view showing a hydraulic excavator as a first embodiment of a work machine according to the present invention. [Diagram 2] 1 is a circuit diagram showing a hydraulic system provided in a first embodiment of a working machine of the present invention. [Diagram 3] 3 is a functional block diagram of a controller that controls the hydraulic system of the work machine according to the first embodiment of the present invention shown in FIG. 2. [Figure 4] 4 is a flowchart showing an example of a control procedure of a controller of the first embodiment of the work machine of the present invention shown in FIG. 3. [Diagram 5] FIG. 4 is a diagram showing an example of a time change in the calculation results of various estimated speeds of the hydraulic actuator by the controller in response to an input from the operating device in the first embodiment of the work machine of the present invention. [Figure 6] FIG. 4 is a functional block diagram of a controller constituting a second embodiment of a work machine according to the present invention. [Figure 7]7 is a flowchart showing an example of a control procedure of a controller of the second embodiment of the work machine of the present invention shown in FIG. 6. [Figure 8] FIG. 11 is a diagram showing an example of a time change in the calculation results of various estimated speeds of the hydraulic actuator by the controller in response to an input from the operating device in the second embodiment of the work machine of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a working machine according to the present invention will be described with reference to the drawings. In this embodiment, a hydraulic excavator will be described as an example of a working machine. [First embodiment] First, a schematic configuration of a hydraulic excavator as a first embodiment of a work machine of the present invention will be described with reference to Fig. 1. Fig. 1 is an external view showing a hydraulic excavator as a first embodiment of a work machine of the present invention. Here, the description will be given using the direction as seen by an operator seated in the driver's seat.

[0014] In Fig. 1, a hydraulic excavator as a work machine includes a self-propelled lower traveling body 1, an upper rotating body 2 rotatably mounted on the lower traveling body 1, and a front working device 3 provided at the front of the upper rotating body 2 so as to be capable of ascending and descending. The upper rotating body 2 is configured to be driven to rotate relative to the lower traveling body 1 by a rotating device 4 including a swing hydraulic motor which is a hydraulic actuator. The upper rotating body 2 forms the machine body of the hydraulic excavator.

[0015] The lower traveling body 1 has, for example, crawler-type traveling devices 11 (only the left one is shown in FIG. 1) on both the left and right sides. The left and right traveling devices 11 are each operated to travel by a traveling hydraulic motor 12, which is a hydraulic actuator.

[0016] The upper rotating body 2 includes a rotating frame 14 as a support structure rotatably mounted on the lower traveling body 1, a cab 15 installed on the left front side of the rotating frame 14, a counterweight 16 provided at the rear end of the rotating frame 14, and a machine room 17 provided between the cab 15 and the counterweight 16. Inside the cab 15, a driver's seat (not shown) where an operator sits and an operation device 58 (see FIG. 2 described later) described below are arranged. The counterweight 16 is for achieving weight balance with the front working device 3. The machine room 17 houses various devices such as a prime mover (not shown), a hydraulic pump 31 (see FIG. 2 described later) described below, and a control valve unit 33 including a control valve 332 (see FIG. 2 described later).

[0017] The front working mechanism 3 is for performing various operations such as excavation work, and is, for example, an articulated working mechanism configured by connecting a plurality of driven members so that they can rotate vertically. The plurality of driven members are, for example, configured with a boom 19, an arm 20, and a bucket 21 as a working tool. The base end of the boom 19 is supported on the front part of the revolving frame 14 of the upper revolving body 2 so that it can rotate vertically. The base end of the arm 20 is supported on the tip of the boom 19 so that it can rotate vertically. The base end of the bucket 21 is supported on the tip of the arm 20 so that it can rotate vertically. The boom 19, the arm 20, and the bucket 21 are operated by driving a boom cylinder 22, an arm cylinder 23, and a bucket cylinder 24, which are hydraulic actuators, respectively.

[0018] The upper rotating body 2 is provided with a first attitude detection device 26 for detecting a physical quantity (attitude information) related to the attitude of the upper rotating body 2 (airframe), and a second attitude detection device 27 for detecting the rotation speed and rotation angle of the upper rotating body 2. The first attitude detection device 26 detects, for example, the inclination (pitch angle) of the upper rotating body 2 in the forward / rearward direction and the inclination (roll angle) of the upper rotating body 2 in the left / right direction (width direction) as physical quantities related to the attitude of the upper rotating body 2 (airframe). The first attitude detection device 26 and the second attitude detection device 27 are, for example, configured with an inertial measurement unit (IMU). The first attitude detection device 26 and the second attitude detection device 27 output detection signals according to the detection values ​​to a controller 60 (see FIG. 2 described later) described later.

[0019] The front working implement 3 is provided with a third posture detection device 28 that detects a physical quantity (posture information) related to the posture of the front working implement 3 and a physical quantity (operation information) related to the operating state of the front working implement 3. The third posture detection device 28 is composed of a plurality of posture sensors 28a, 28b, 28c that detect a physical quantity (posture information) related to the posture of the boom 19, the arm 20, and the bucket 21, which are components of the front working implement 3, and a physical quantity (operation information) related to the operating state of the boom 19, the arm 20, and the bucket 21, respectively. Each of the posture sensors 28a, 28b, 28c is composed of, for example, an inertial measurement unit (IMU). The third posture detection device 28 (posture sensors 28a, 28b, 28c) outputs a detection signal corresponding to the detection value to a controller 60 (see FIG. 2) described later. The posture sensors 28a, 28b, 28c constituting the third posture detection device 28 need only be capable of detecting posture information and operation information of the driven members 19, 20, 21 of the front working mechanism 3, and may be constituted by an inclination sensor, angle sensor, stroke sensor, etc. The posture sensors 28a, 28b, 28c of the third posture detection device 28 correspond to the "first detection device for detecting operation information of the driven members" recited in the claims.

[0020] Next, the configuration of the hydraulic system installed in the first embodiment of the work machine of the present invention will be described with reference to Fig. 2. Fig. 2 is a circuit diagram showing the hydraulic system provided in the first embodiment of the work machine of the present invention.

[0021] In Fig. 2, the hydraulic excavator is equipped with a hydraulic system 30 that hydraulically operates the lower traveling body 1, the upper rotating body 2, and the front working mechanism 3 (all see Fig. 1). Fig. 2 only shows a hydraulic circuit related to a boom cylinder 22 that operates the boom 19 of the front working mechanism 3, and omits other hydraulic circuits related to the traveling hydraulic motor 12 that operates the traveling mechanism 11, the swing hydraulic motor (swing mechanism 4) that swings the upper rotating body 2, and the arm cylinder 23 and bucket cylinder 24 that operate the arm 20 and bucket 21 of the front working mechanism 3. Also, omitted are those that are not related to the present invention, such as a bleed-off valve that discharges the discharge flow rate of the hydraulic pump 31 to a hydraulic oil tank 36 described below when an operating device 58 described below is not being operated, and various other devices.

[0022] The hydraulic system 30 includes a hydraulic pump 31 driven by a prime mover (not shown) to discharge pressure oil, a hydraulic actuator 32 (boom cylinder 22) driven by the pressure oil supplied from the hydraulic pump 31 to operate the boom 19, and a directional control valve 332 that controls the flow (direction and flow rate) of the pressure oil supplied from the hydraulic pump 31 to the hydraulic actuator 32. The prime mover is, for example, an engine or an electric motor.

[0023] The hydraulic pump 31 is, for example, a variable displacement pump, and has a regulator that adjusts the pump volume. The regulator adjusts the pump volume in response to a command signal from the controller 60, for example, and includes a flow command pressure port 31a to which a pilot pressure is input as a flow command signal from the pilot hydraulic circuit 40 described below.

[0024] The directional control valve 332 for the boom cylinder 22 constitutes a part of the control valve unit 33 (see FIG. 1). In other words, the control valve unit 33 is an assembly of directional control valves that control the flow (direction and flow rate) of pressure oil to each of the hydraulic actuators 12, 22, 23, and 24. The directional control valve 332 is, for example, of a hydraulic pilot type, and has a pair of command pressure ports 332a, 332b on both sides. The drive (switching direction and stroke amount) of the directional control valve 332 is controlled by inputting a pilot secondary pressure generated in a pilot hydraulic circuit 40 described below to the pair of command pressure ports 332a, 332b.

[0025] The directional control valve 332 is connected to the discharge side of the hydraulic pump 31 via a pump line 37. The directional control valve 332 is also connected to the hydraulic actuator 32 (the boom cylinder 22) via actuator lines 38, 38.

[0026] The pump line 37 is connected to the hydraulic oil tank 36 via a relief line 39 branching off from the pump line 37. A relief valve 35 is provided on the relief line 39. The relief valve 35 defines the upper limit of the discharge pressure (main hydraulic circuit) of the hydraulic pump 31, and is configured to open when the discharge pressure of the hydraulic pump 31 exceeds a set pressure.

[0027] A check valve 34 is provided on the pump line 37. The check valve 34 is configured to allow the flow of pressure oil from the hydraulic pump 31 to the directional control valve 332, while blocking the flow of pressure oil from the directional control valve 332 to the hydraulic pump 31. In other words, the check valve 34 prevents the backflow of pressure oil from the actuator lines 38, 38 to the pump line 37.

[0028] A first pressure sensor 51 that detects the discharge pressure of the hydraulic pump 31 is provided on the pump line 37. The first pressure sensor 51 outputs a pressure detection signal Pp corresponding to the detected discharge pressure of the hydraulic pump 31 to the controller 60.

[0029] Second pressure sensors 52, 53 that detect the pressure of the hydraulic actuator 32 (the driving pressure of the boom cylinder 22) are provided on the actuator lines 38, 38, respectively. The second pressure sensors 52, 53 output pressure detection signals Ps corresponding to the detected pressure of the hydraulic actuator 32 to the controller 60.

[0030] The hydraulic system 30 further includes a pilot hydraulic circuit 40 for controlling the drive (switching direction and stroke amount) of each hydraulic pilot type directional control valve constituting the control valve unit 33 and adjusting the pump volume of the hydraulic pump 31. The pilot hydraulic circuit 40 includes a pilot pump 41 as a pilot hydraulic source, a first solenoid proportional valve 43 that reduces the discharge pressure (pilot primary pressure) of the pilot pump 41 in response to a first valve command signal Cp from the controller 60 to generate a pilot secondary pressure to be input to a flow rate command pressure port 31a of a regulator of the hydraulic pump 31, and second solenoid proportional valves 44, 45 that reduce the discharge pressure (pilot primary pressure) of the pilot pump 41 in response to a second valve command signal Cv from the controller 60 to generate a pilot secondary pressure to be input to command pressure ports 332a, 332b of the directional control valve 332. An assembly of a plurality of solenoid proportional valves including the first solenoid proportional valve 43 and the second solenoid proportional valves 44, 45 constitutes a solenoid valve unit 42.

[0031] The pilot pump 41 generates a pilot primary pressure which is the source pressure of the pilot secondary pressure input to the regulator of the hydraulic pump 31 and the directional control valve 332, and is driven by a prime mover (not shown). The pilot pump 41 is, for example, a fixed displacement pump. The pilot pump 41 is connected to a solenoid valve unit 42 including a first solenoid proportional valve 43 and second solenoid proportional valves 44, 45 via a pilot line 48. The pilot line 48 is connected to the hydraulic oil tank 36 via a pilot relief valve 47. The pilot relief valve 47 is configured to open when the discharge pressure (pilot primary pressure) of the pilot pump 41 exceeds a set pressure, and is for maintaining the pilot primary pressure at the set pressure.

[0032] An output side of the first solenoid proportional valve 43 is connected to a flow rate command pressure port 31a of the regulator of the hydraulic pump 31. Output sides of the second solenoid proportional valves 44, 45 are respectively connected to command pressure ports 332a, 332b of the directional control valve 332. The first solenoid proportional valve 43 and the second solenoid proportional valves 44, 45 are connected to the hydraulic oil tank 36 via a pilot line 49.

[0033] The solenoid portion 43a of the first solenoid proportional valve 43 is electrically connected to the controller 60, and receives a first valve command signal Cp from the controller 60. The solenoid portions 44a, 45a of the second solenoid proportional valves 44, 45 are electrically connected to the controller 60, and receive a second valve command signal Cv from the controller 60. Current sensors 55, 56 are provided to detect current as the second valve command signal Cv from the controller 60 to the solenoid portions 44a, 45a of the second solenoid proportional valves 44, 45.

[0034] An operating device 58 that commands the operation of the boom 19 and other driven members of the front working mechanism 3 is electrically connected to the controller 60. The operating device 58 is, for example, an electric type, and outputs an operating signal corresponding to the input operating amount and operating direction as an electric signal to the controller 60. The operating device 58 is, for example, an operating lever device, and has an operating lever 58a held by the operator, and an electric signal generator 58b that detects the operating direction and operating amount of the operating lever 58a and generates an operating signal corresponding to the detected values ​​as an electric signal.

[0035] The controller 60 controls the opening degree of each electromagnetic proportional valve 43, 44, 45 based on an operation signal (electrical signal) from the operating device 58 and detection signals (detection values) from each sensor 28a (28), 51, 52, 53, 55, 56, and thereby ultimately controls the drive of the hydraulic actuator 32 (boom cylinder 22).

[0036] Next, the function of the controller constituting a part of the first embodiment of the work machine of the present invention will be described with reference to Fig. 3. Fig. 3 is a functional block diagram of the controller that controls the hydraulic system of the first embodiment of the work machine of the present invention shown in Fig. 2.

[0037] In FIG. 3, the controller 60 includes, as a hardware configuration, a storage device 61 including a RAM, a ROM, etc., and a processing device 62 including a CPU, an MPU, etc. The storage device 61 stores in advance a program and various information required for controlling the pump volume (pump flow rate) of the hydraulic pump 31 and the drive of the directional control valve 332. The processing device 62 appropriately reads the program and various information from the storage device 61 and executes processing according to the program to realize various functions. The controller 60 of this embodiment is characterized in that it estimates the speed of each hydraulic actuator of the boom cylinder 22, the arm cylinder 23, and the bucket cylinder 24 using two types of methods, arbitrates the two estimated speeds according to the drive state of each hydraulic actuator to calculate an arbitrated speed, which is an arbitrated speed, and performs feedback control based on the arbitrated speed as a result of the calculation, thereby performing drive control (speed control) of each hydraulic actuator. Note that only the drive control (speed control) of the boom cylinder 22 (hydraulic actuator 32) will be described here, but the drive control (speed control) of the arm cylinder 23 and the bucket cylinder 24 is similar, so that the description thereof will be omitted. "Arbitration" is synonymous with signal arbitration and means adjusting one rate to be larger relative to the other rate and the other rate to be smaller relative to the one rate.

[0038] The controller 60 has, as functions executed by the processing device 62, a required speed calculation unit 71, a first estimated speed calculation unit 72, a second estimated speed calculation unit 73, an estimated speed arbitration unit 74, a feedback controller (hereinafter sometimes referred to as the FB controller) 76, a pump target flow rate calculation unit 77, a pump flow rate control unit 78, and a directional control valve control unit 79.

[0039] The required speed calculation unit 71 receives an operation signal L from the operating device 58, and calculates a required speed Vs_R of the hydraulic actuator 32 (boom cylinder 22) based on the received operation signal L. The required speed calculation unit 71 can calculate the required speed Vs_R, for example, by using a characteristics table that predefines the correspondence relationship between the operation amount of the operating device 58 and the speed of the hydraulic actuator (hydraulic cylinder). The calculated required speed Vs_R is used by the FB controller 76 for feedback control calculation, which will be described later.

[0040] The first estimated speed calculation unit 72 takes in detection values ​​Si of the posture sensors 28a, 28b, 28c of the third posture detection device 28 that detects posture information and operation information of the boom 19, arm 20, and bucket 21 that constitute the front working mechanism 3, and estimates the drive speed of the boom cylinder 22 that operates the boom 19 as a first estimated speed Vs_E1 based on the taken-in detection values ​​Si of the posture sensors 28a, 28b, 28c.

[0041] Since the posture sensors 28a, 28b, 28c detect the actual operating states of the driven members 19, 20, 21 of the front working implement 3, the first estimated speed Vs_E1 is a value obtained by directly calculating the drive speed of each hydraulic actuator based on the actual operating states of the driven members 19, 20, 21 from the geometrical relationship between each driven member 19, 20, 21 and each hydraulic actuator (boom cylinder 22, arm cylinder 23, bucket cylinder 24). Therefore, the first estimated speed Vs_E1 is a value obtained by highly accurately estimating the actual drive state (drive speed) of the hydraulic actuator 32 (boom cylinder 22). Conversely, since the posture sensors 28a, 28b, 28c output operation information of a stopped state until each driven member 19, 20, 21 of the front working implement 3 actually starts to move, the first estimated speed Vs_E1 is an estimated value of zero until each driven member 19, 20, 21 actually starts to move. For this reason, it is impossible to predict the movements of the driven members 19, 20, 21 of the front working mechanism 3 and appropriately adjust the control commands based on the first estimated speed Vs_E1 estimated from the detection values ​​of the posture sensors 28a, 28b, 28c.

[0042] The second estimated speed calculation unit 73 takes in the detection value Pp (discharge pressure of the hydraulic pump 31) of the first pressure sensor 51, the detection value Ps (pressure of the hydraulic actuator 32) of the second pressure sensors 52, 53, and the detection value Iv (current value as a second valve command signal to the second solenoid proportional valves 44, 45) of the current sensors 55, 56, and estimates the driving speed of each of the hydraulic actuators 32 as a second estimated speed Vs_E2 based on the detection values ​​of the respective sensors 51, 52, 53, 55, 56. The differential pressure across the directional control valve 332 can be estimated from the difference between the discharge pressure of the hydraulic pump 31 (detection value Pp of the first pressure sensor 51) and the pressure of the hydraulic actuator 32 (detection value Ps of the second pressure sensors 52, 53). In addition, the opening degree (opening area) of the directional control valve 332 can be estimated based on the current value to the second solenoid proportional valves 44, 45. It is possible to estimate the flow rate of pressure oil flowing from the directional control valve 332 to the hydraulic actuator 32 by using a fluid dynamic relational expression from the pressure difference across the directional control valve 332 and the opening area.

[0043] Specifically, the second estimated speed Vs_E2 is calculated, for example, using the following formula (1).

[0044]

number

[0045] Here, Cd is the flow coefficient, Av is the opening area of ​​each directional control valve 332, As is the pressure-receiving area of ​​each hydraulic actuator 32 (boom cylinder 22), ΔP is the differential pressure before and after each directional control valve 332, and ρ is the density of the hydraulic oil. The flow coefficient Cd, the density ρ of the hydraulic oil, and the pressure-receiving area As of the hydraulic actuator 32 (boom cylinder 22) are stored in advance in the storage device 61.

[0046] The second estimated speed Vs_E2 is the drive speed of the hydraulic actuator 32 (boom cylinder 22) predicted from the flow rate (meter-in flow rate) of pressure oil supplied from the directional control valve 332 to the hydraulic actuator 32 (boom cylinder 22). In other words, the second estimated speed Vs_E2 is not estimated based on the actual drive state of the hydraulic actuator 32 (boom cylinder 22), but is an estimated value that predicts the likely drive state of the hydraulic actuator 32 (boom cylinder 22). For this reason, it is possible to predict the operation of each of the driven members 19, 20, 21 of the front working implement 3 and appropriately adjust the control command based on the second estimated speed Vs_E2 estimated from the detection values ​​of each of the sensors 51, 52, 53, 55, 56 related to the directional control valve 332. However, since the second estimated speed Vs_E2 is an estimated value obtained by using a fluid dynamic relational expression, the estimation accuracy is likely to be reduced due to the influence of disturbances such as oil temperature and cavitation, and the detection accuracy of the sensors. For this reason, the second estimated speed Vs_E2 tends to have lower estimation accuracy than the first estimated speed Vs_E1.

[0047] In this embodiment, the first pressure sensor 51, the second pressure sensors 52, 53 and the current sensors 55, 56 constitute a detection device that detects information related to the flow rate of pressure oil supplied to the hydraulic actuator 32 via the directional control valve 332. When the detection device is subdivided, the first pressure sensor 51 and the second pressure sensors 52, 53 constitute a detector that detects a physical quantity related to the differential pressure before and after the directional control valve 332. In addition, the current sensors 55, 56 constitute a detector that detects a physical quantity related to the opening area of ​​the directional control valve 332.

[0048] The estimated speed arbitration unit 74 calculates an arbitrated speed Vs_Ar of the hydraulic actuator 32 (boom cylinder 22) using the first estimated speed Vs_E1 of the hydraulic actuator 32 (boom cylinder 22) which is the calculation result of the first estimated speed calculation unit 72, and the second estimated speed Vs_E2 of the hydraulic actuator 32 (boom cylinder 22) which is the calculation result of the second estimated speed calculation unit 73. The estimated speed arbitration unit 74 calculates the arbitrated speed Vs_Ar by arbitrating the first estimated speed Vs_E1 and the second estimated speed Vs_E2 in accordance with the driving state of the hydraulic actuator 32, taking into account the characteristics of the first estimated speed Vs_E1 and the characteristics of the second estimated speed Vs_E2 described above.

[0049] In summary, when the hydraulic actuator 32 (boom cylinder 22) starts moving, in order to suppress control instability (hunting, etc.) due to the effect of a response delay of the hydraulic actuator 32 caused by the inertia of the front working implement 3 (boom 19), arbitration is performed so that the weighting of the second estimated speed Vs_E2 is greater than the weighting of the first estimated speed Vs_E1. Here, "weighting" is synonymous with influence or priority. In addition, when the driving state of the hydraulic actuator 32 (boom cylinder 22) transitions from the starting state and exceeds a predetermined state and approaches a steady state, arbitration is performed so that the weighting of the first estimated speed Vs_E1 is increased while the weighting of the second estimated speed Vs_E2 is relatively decreased in order to improve the accuracy of the estimated speed of the hydraulic actuator 32. By performing such arbitration, an estimated speed (arbitrated speed Vs_Ar) of the hydraulic actuator 32 appropriate for feedback control is calculated according to the driving state of the hydraulic actuator 32, such as when the hydraulic actuator 32 starts moving or approaches a steady state more than a predetermined state.

[0050] Specifically, the arbitration speed Vs_Ar is calculated, for example, using the following formulas (2) to (4): where Vs_E1 is the first estimated speed, Vs_E2 is the second estimated speed, and Vs_R is the required speed.

[0051]

number

[0052]

number

[0053]

number

[0054] α derived from equation (3) and β derived from equation (4) are weights used when arbitrating the first estimated speed Vs_E1 and the second estimated speed Vs_E2. The coefficient α is basically a weight that reflects whether or not the drive state of the hydraulic actuator 32 (boom cylinder 22) is in a start-of-movement state. That is, it functions as an index that can determine whether or not the hydraulic actuator 32 is in a start-of-movement state. The coefficient α also serves as a weight that reflects that the drive state of the hydraulic actuator 32 (boom cylinder 22) has transitioned from the start-of-movement state and has exceeded a predetermined state and is approaching a steady state. That is, it also serves as an index that can determine whether or not the hydraulic actuator 32 is in a state that has exceeded a predetermined state and is approaching a steady state. On the other hand, the coefficient β is a weight that more reliably reflects whether or not the drive state of the hydraulic actuator 32 (boom cylinder 22) is in a state that has exceeded a predetermined state and is approaching a steady state than the coefficient α. That is, it functions as an index that can more reliably determine whether or not the hydraulic actuator 32 is in a state that has exceeded a predetermined state and is approaching a steady state.

[0055] In the calculation of α in equation (3), if the degree of deviation of the first estimated speed Vs_E1 from the second estimated speed Vs_E2 is large, it means that the actual driving state of the hydraulic actuator 32 (boom cylinder 22) deviates from the driving state of the hydraulic actuator 32 predicted based on the flow rate of pressure oil supplied to the hydraulic actuator 32 via the directional control valve 332. This state is usually assumed to be a state in which the hydraulic actuator 32 (boom cylinder 22) has just started moving. In this case, the weight α of the second estimated speed Vs_E2 becomes large, while the weight of the first estimated speed Vs_E1 becomes relatively small.

[0056] Conversely, when the degree of deviation of the first estimated speed Vs_E1 from the second estimated speed Vs_E2 is extremely small in the calculation of α in equation (3), this means that the actual driving state of the hydraulic actuator 32 (boom cylinder 22) is close to the driving state of the hydraulic actuator 32 predicted from the flow rate passing through the directional control valve 332. This state is usually assumed to be a state in which the hydraulic actuator 32 (boom cylinder 22) continues to be in a driving state approaching a steady state beyond a predetermined state. In this case, the weight α of the second estimated speed Vs_E2 becomes small, while the weight of the first estimated speed Vs_E1 becomes relatively large.

[0057] However, even if the degree of deviation (coefficient α) of the first estimated speed Vs_E1 from the second estimated speed Vs_E2 is extremely small, the first estimated speed Vs_E1 does not necessarily reach the vicinity of the required speed Vs_R. Therefore, the coefficient β is further used to arbitrate the first estimated speed Vs_E1 and the second estimated speed Vs_E2. In the calculation of β in the formula (4), when the degree of deviation of the first estimated speed Vs_E1 from the required speed Vs_R is extremely small, it means that the actual driving state of the hydraulic actuator 32 (boom cylinder 22) is close to the required speed Vs_R according to the operation of the operating device 58. This state is when the actual driving state of the hydraulic actuator 32 (boom cylinder 22) appropriately follows the control target value. In this case, the weight β of the second estimated speed Vs_E2 is made small, while the weight of the first estimated speed Vs_E1 is made relatively large. By increasing the weight of the first estimated speed Vs_E1, which is more accurate than the second estimated speed Vs_E2, it is possible to estimate with high accuracy the speed of the hydraulic actuator 32, which is in a driving state close to a steady state.

[0058] Conversely, in the calculation of β in equation (4), if the degree of deviation of the first estimated speed Vs_E1 from the required speed Vs_R is large, this means that the actual driving state of the hydraulic actuator 32 (boom cylinder 22) is in a state deviating from the required speed Vs_R according to the operation. If feedback control is performed using the first estimated speed Vs_E1, the correction amount of the feedback control becomes excessive, which may cause the hydraulic actuator 32 to jump out or hunt. Therefore, in such a case, the weight β of the second estimated speed Vs_E2 is increased, while the weight of the first estimated speed Vs_E1 is relatively decreased.

[0059] The FB controller 76 calculates a target speed Vs_T of the hydraulic actuator 32 that corrects a control command so as to reduce the speed deviation between the requested speed Vs_R and the arbitrated speed Vs_Ar, based on the requested speed Vs_R of the hydraulic actuator 32 which is the calculation result of the requested speed calculation unit 71 and the arbitrated speed Vs_Ar of the hydraulic actuator 32 which is the calculation result of the estimated speed arbitration unit 74. The target speed Vs_T is calculated based on the speed deviation between the requested speed Vs_R and the arbitrated speed Vs_Ar, for example, using a PID control calculation method.

[0060] The pump target flow rate calculation unit 77 calculates a pump target flow rate Qp of the hydraulic pump 31 based on the target speed Vs_T of the hydraulic actuator 32, which is the calculation result of the FB controller 76. In calculating the pump target flow rate Qp, the design specifications of the hydraulic actuator 32 stored in advance in the storage device 61 are also used.

[0061] The pump flow rate control unit 78 calculates a first valve command signal Cp for the first solenoid proportional valve 43 according to the pump target flow rate Qp which is a calculation result of the pump target flow rate calculation unit 77. The pump flow rate control unit 78 can calculate the first valve command signal Cp, for example, by using a characteristics table which predefines the correspondence relationship between the pump target flow rate Qp and the first valve command signal Cp for the first solenoid proportional valve 43. The pump flow rate control unit 78 outputs the first valve command signal Cp to the first solenoid proportional valve 43.

[0062] The directional control valve control unit 79 calculates a second valve command signal Cv for the second solenoid proportional valves 44, 45 according to the target speed Vs_T of the hydraulic actuator 32, which is the calculation result of the FB controller 76. The directional control valve control unit 79 can calculate the second valve command signal Cv, for example, by using a characteristics table that predefines the correspondence relationship between the target speed Vs_T and the second valve command signal Cv for the second solenoid proportional valves 44, 45. The directional control valve control unit 79 outputs the second valve command signal Cv to the second solenoid proportional valves 44, 45.

[0063] Next, an example of a control procedure executed by the controller of the first embodiment of the work machine of the present invention will be described with reference to Fig. 4. Fig. 4 is a flow chart showing an example of a control procedure of the controller of the first embodiment of the work machine of the present invention shown in Fig. 3.

[0064] 4, the controller 60 shown in FIG. 3 first determines whether or not there is an operation input to the operation device 58 (input of an operation signal from the operation device 58) (step S10). If there is an operation input to the operation device 58, that is, if an operation signal has been input (if YES), the process proceeds to step S20. On the other hand, if there is no operation signal input (if NO), the process returns to step S10 again, and step S10 is repeated until YES is obtained.

[0065] If the answer is YES in step S10, the required speed calculation unit 71 of the controller 60 calculates the required speed Vs_R of each hydraulic actuator 32 based on the operation signal L (operation input amount) from the operation device 58 (step S20). The required speed calculation unit 71 calculates the required speed Vs_R, for example, by using a characteristics table that predefines the correspondence relationship between the operation input amount and the speed of the hydraulic actuator.

[0066] Next, the first estimated speed calculation unit 72 of the controller 60 calculates the drive speed of each hydraulic actuator 32 as a first estimated speed Vs_E1 based on the detection values ​​Si of the attitude sensors 28a, 28b, 28c of the third attitude detection device 28 (attitude information and operation information of the driven members 19, 20, 21 of the front working mechanism 3) (step S30). The first estimated speed Vs_E1 is a value obtained by directly estimating the drive speed of the driven members 19, 20, 21 from the geometric relationship of the driven members 19, 20, 21 based on actual operation information of the driven members 19, 20, 21 of the front working mechanism 3.

[0067] At the same time, the second estimated speed calculation unit 73 of the controller 60 calculates the drive speed of each hydraulic actuator 32 as a second estimated speed Vs_E2 based on the discharge pressure of the hydraulic pump 31, which is the detection value Pp of the first pressure sensor 51, the pressure of the hydraulic actuator 32, which is the detection value Ps of the second pressure sensors 52, 53, and the current value as the second valve command signal Cv to the second electromagnetic proportional valves 44, 45, which is the detection value Iv of the current sensors 55, 56 (step S40). The second estimated speed calculation unit 73 calculates the second estimated speed Vs_E2 by using, for example, the above-mentioned formula (1), which is a fluid dynamics relational expression. The second estimated speed Vs_E2 is an estimate of the drive speed of each hydraulic actuator 32 that is predicted to be generated based on the flow rate of the pressure oil supplied to the hydraulic actuator 32 via the directional control valve 332.

[0068] Next, the estimated speed arbitration unit 74 of the controller 60 calculates an arbitrated speed Vs_Ar of each hydraulic actuator 32 using the first estimated speed Vs_E1 which is the calculation result of the first estimated speed calculation unit 72 and the second estimated speed Vs_E2 which is the calculation result of the second estimated speed calculation unit 73 (step S50). The estimated speed arbitration unit 74 calculates the arbitrated speed Vs_Ar obtained by arbitrating the first estimated speed Vs_E1 and the second estimated speed Vs_E2 in accordance with the drive state of each hydraulic actuator 32, for example, by using the above-mentioned equations (2) to (4).

[0069] When the degree of deviation of the first estimated speed Vs_E1 from the second estimated speed Vs_E2 is large, the weight α of the second estimated speed Vs_E2 becomes large while the weight of the first estimated speed Vs_E1 becomes relatively small. Conversely, when the degree of deviation of the first estimated speed Vs_E1 from the second estimated speed Vs_E2 is extremely small, the weight α of the second estimated speed Vs_E2 becomes small while the weight of the first estimated speed Vs_E1 becomes relatively large.

[0070] Furthermore, when the deviation of the first estimated speed Vs_E1 from the required speed Vs_R is extremely small, the weight β of the second estimated speed Vs_E2 becomes small while the weight of the first estimated speed Vs_E1 becomes relatively large. Conversely, when the deviation of the first estimated speed Vs_E1 from the required speed Vs_R is large, the weight β of the second estimated speed Vs_E2 becomes large while the weight of the first estimated speed Vs_E1 becomes relatively small.

[0071] Next, the FB controller 76 of the controller 60 calculates a target speed Vs_T of the hydraulic actuator 32 based on the required speed Vs_R which is the calculation result of the required speed calculation unit 71 and the arbitrated speed Vs_Ar which is the calculation result of the estimated speed arbitration unit 74 (step S60). The target speed Vs_T is, for example, a target value (control amount) for correcting a control command so that the speed deviation between the required speed Vs_R and the arbitrated speed Vs_Ar becomes small.

[0072] Next, the pump target flow rate calculation unit 77 of the controller 60 calculates a pump target flow rate Qp of the hydraulic pump 31 based on the target speed Vs_T of each hydraulic actuator 32 which is the calculation result of the FB control unit 76 (step S70). Furthermore, the pump flow rate control unit 78 of the controller 60 calculates a first valve command signal Cp for the first solenoid proportional valve 43 according to the pump target flow rate Qp of the hydraulic pump 31 which is the calculation result of the pump target flow rate calculation unit 77, and outputs the first valve command signal Cp to the first solenoid proportional valve 43 (step S80).

[0073] 2 generates a pilot secondary pressure corresponding to the first valve command signal Cp from the pilot primary pressure as the discharge pressure of the pilot pump 41. The pilot secondary pressure generated by the first solenoid proportional valve 43 is input to the fluid pressure port 31a of the regulator of the hydraulic pump 31, whereby the pump flow rate (pump volume) of the hydraulic pump 31 is adjusted to become the pump target flow rate Qp which is the calculation result of the controller 60.

[0074] Further, the directional control valve control section 79 of the controller 60 calculates a second valve command signal Cv for the second electromagnetic proportional valves 44, 45 according to the target speed Vs_T of each hydraulic actuator 32, which is the calculation result of the FB controller 76, and outputs the second valve command signal Cv to the second electromagnetic proportional valves 44, 45 (step S90). As a result, the second electromagnetic proportional valves 44, 45 shown in FIG. 2 generate a pilot secondary pressure according to the second valve command signal Cv from the pilot primary pressure as the discharge pressure of the pilot pump 41. The pilot secondary pressure generated by the second electromagnetic proportional valves 44, 45 is input to the command pressure ports 332a, 332b of the directional control valve 332, thereby controlling the opening area (opening degree) of the directional control valve 332, and thereby controlling the flow rate (meter-in flow rate) of the pressure oil supplied to the hydraulic actuator 32 via the directional control valve 332 to be the target speed Vs_T of the hydraulic actuator 32, which is the calculation result of the controller 60.

[0075] When the controller 60 finishes outputting the first valve command signal Cp to the first electromagnetic proportional valve 43 (step S80) and the second valve command signal Cv to the second electromagnetic proportional valves 44, 45 (step S90), it returns and starts a new control cycle. That is, the controller 60 again executes and repeats the control cycle constituted by steps S10 to S90 shown in FIG.

[0076] Next, the operation and effects of the first embodiment of the work machine of the present invention will be described. Here, for ease of explanation, the operation of the hydraulic system when operating the boom alone will be described with reference to Fig. 2 and Fig. 5. Fig. 5 is a diagram showing an example of the change over time of the calculation results of various estimated speeds of the hydraulic actuator by the controller in response to an input to the operation device in the first embodiment of the work machine of the present invention. In Fig. 5, the upper diagram shows the change over time of an example of the operation input amount to the operation device, and the lower diagram shows an example of the change over time of various speeds of the boom cylinder which are the calculation results of the controller in response to the operation input amount shown in the upper diagram.

[0077] At time T1 shown in Fig. 5, a step-like operation input (solid line in the upper diagram of Fig. 5) is started to the operation device 58 shown in Fig. 2. As a result, the controller 60 shown in Fig. 3 calculates a required speed Vs_R (long dashed line in the lower diagram of Fig. 5) of the boom cylinder 22 according to the operation input amount L from the operation device 58. The controller 60 outputs command signals to the hydraulic pump 31 and the directional control valve 332 based on the required speed Vs_R.

[0078] 2 opens in response to a command signal (second valve command signal Cv for the second solenoid proportional valves 44, 45) from the controller 60, thereby causing pressure oil to be supplied from the hydraulic pump 31 to the hydraulic actuator 32 (boom cylinder 22) via the directional control valve 332. For this reason, the second estimated speed Vs_E2 calculated by the controller 60 based on the detection value Pp of the first pressure sensor 51 and the detection value Ps of the second pressure sensors 52, 53 (pressure difference between before and after the directional control valve 332) and the detection value Iv of the current sensors 55, 56 (opening area of ​​the directional control valve 332) becomes a value other than 0.

[0079] On the other hand, the boom cylinder 22 applies a driving force to the boom 19, which has a large mass and is in a stopped state, but the boom 19 remains in a stopped state due to inertia or the like. Therefore, the attitude sensor 28a of the third attitude detection device 28 detects the drive state of the boom cylinder 22 as a stopped state. Therefore, the first estimated speed Vs_E1 calculated by the controller 60 based on the detection value Si of the third attitude detection device 28 becomes 0 (zero). As a result, the arbitration speed Vs_Ar calculated by the controller 60 based on the first estimated speed Vs_E1 and the second estimated speed Vs_E2 becomes equal to the second estimated speed Vs_E2. That is, before the boom cylinder 22 actually starts moving, the attitude sensor 28a of the third attitude detection device 28 detects the stopped state of the boom cylinder 22, so that the weights α and β of the second estimated speed Vs_E2 shown in the above-mentioned equations (2) to (4) are arbitrated to be 1, while the weight of the first estimated speed Vs_E1 is arbitrated to be 0.

[0080] At time T3, after a certain time has elapsed from time T2, the boom 19 transitions to a state in which it is actually operating. That is, the attitude sensor 28a of the third attitude detection device 28 detects the actual drive of the boom cylinder 22. For this reason, the first estimated speed Vs_E1 becomes a value corresponding to the detection value Si of the third attitude detection device 28. On the other hand, the second estimated speed Vs_E2 becomes a value corresponding to the detection value Pp of the first pressure sensor 51 and the detection value Ps of the second pressure sensors 52 and 53 (the differential pressure before and after the directional control valve 332) and the detection value Iv of the current sensors 55 and 56 (the opening area of ​​the directional control valve 332), as at time T2.

[0081] In this case, the adjusted speed Vs_Ar is a value obtained by adjusting the first estimated speed Vs_E1 and the second estimated speed Vs_E2 in accordance with the weights α and β shown in the above-mentioned formulas (2) to (4). Immediately after the boom cylinder 22 starts moving, such as at time T3, the difference between the second estimated speed Vs_E2 and the first estimated speed Vs_E1 is large. For this reason, the adjusted adjusted speed Vs_Ar is calculated such that the weight α of the second estimated speed Vs_E2 is large while the weight of the first estimated speed Vs_E1 is relatively small.

[0082] At time T4, when a considerable amount of time has elapsed since the start time T1 of the operation input, the first estimated speed Vs_E1 calculated based on the detection value Si of the third attitude detection device 28 is close to the required speed Vs_R according to the amount of operation input. That is, the boom cylinder 22 is in a driving state very close to the steady state. In this case, since the degree of deviation of the first estimated speed Vs_E1 from the required speed Vs_R is very small, the weight β of the second estimated speed Vs_E2 becomes small, while the weight of the first estimated speed Vs_E1 becomes relatively large. Therefore, the arbitration speed Vs_Ar is arbitrated so that the component of the first estimated speed Vs_E1 is the majority and the component of the second estimated speed Vs_E2 is almost the same.

[0083] In this manner, in this embodiment, when the boom cylinder 22 starts to move immediately after the operation input to the operating device 58 is started, the drive control of the boom cylinder 22 is performed mainly using the second estimated speed Vs_E2 of the boom cylinder 22 predicted based on the flow rate of pressure oil supplied to the boom cylinder 22 via the directional control valve 332. Immediately after the operation input is started, the effect of the response delay of the boom cylinder 22 caused by the inertia of the boom 19 is large, so using the second estimated speed Vs_E2 can suppress deviation from the required speed Vs_R according to the operation input more than using the first estimated speed Vs_E1 of the boom cylinder 22 calculated based on the actual drive state (almost stopped state) of the boom cylinder 22. Therefore, it is possible to suppress the occurrence of the boom cylinder 22 popping out or hunting due to an excessive correction amount of the feedback control.

[0084] On the other hand, when the actual drive state of the boom cylinder 22 is close to the state corresponding to the operation input, the drive control of the boom cylinder 22 is mainly performed using the first estimated speed Vs_E1 of the boom cylinder 22 calculated based on the detection value of the attitude sensor 28a that detects the actual drive state of the boom cylinder 22. Since the first estimated speed Vs_E1 estimates the drive speed of the boom cylinder 22 based on the actual drive state of the boom cylinder 22, a highly accurate estimated value can be obtained. On the other hand, since the second estimated speed Vs_E2 estimates the drive speed of the boom cylinder 22 via a fluid dynamics relational expression, the estimation accuracy tends to be lower than that of the first estimated speed Vs_E1. Therefore, when the boom cylinder 22 is close to the drive state corresponding to the operation of the operating device 58, the boom cylinder 22 is mainly controlled using the first estimated speed Vs_E1, which is an estimated value more accurate than the second estimated speed Vs_E2, so that highly accurate speed control of the boom cylinder 22 can be realized.

[0085] Therefore, in this embodiment, good control accuracy of the hydraulic actuator 32 can be achieved from the time when the drive state of the boom cylinder 22 (hydraulic actuator 32) changes from the start of movement state to a steady state.

[0086] In this embodiment, the arbitrated speed Vs_Ar of the hydraulic actuator 32 is calculated by relatively increasing or decreasing the weighting for the first estimated speed Vs_E1 and the weighting for the second estimated speed Vs_E2 according to the drive state (transition from the start-of-motion state to the steady state) of the hydraulic actuator 32. Therefore, the arbitrated speed Vs_Ar does not instantaneously switch between the value of the first estimated speed Vs_E1 and the value of the second estimated speed Vs_E2, so that a calculation result of continuous change can be obtained. Therefore, in the control based on the arbitrated speed Vs_Ar, the stability of the control can be ensured.

[0087] An example of the operation of a hydraulic excavator in which the action and effect of the present embodiment are exerted is the loading operation of soil after excavation. Assume that the soil excavated by the bucket 21 is swung and lifted by raising the boom, and then loaded onto a dump truck. It is expected that the operator of the hydraulic excavator will input a large operation amount with a fast rise after excavation in order to shorten the work time (see the upper diagram of FIG. 5). In this case, the time (time) when the first estimated speed Vs_E1 of the boom cylinder 22 rises is slower than the time (time) when the second estimated speed Vs_E2 rises. That is, the time region where the first estimated speed Vs_E1 is 0 (zero), such as time T2 in the lower diagram of FIG. 5, becomes longer. In addition, the required speed Vs_R increases in response to a large operation amount, so the time region until the actual speed of the boom cylinder 22 approaches the required speed Vs_R (the time region from near time T3 to time T4 in the lower diagram of FIG. 5) also becomes longer. Therefore, it is considered that the action and effect of this embodiment will be greatly exerted in the loading operation of soil and sand after excavation by the hydraulic excavator.

[0088] In the hydraulic excavator (work machine) according to the first embodiment of the present invention described above, the controller 60 calculates the arbitration speed Vs_Ar in such a way that as the degree of deviation α of the first estimated speed Vs_E1 from the second estimated speed Vs_E2 increases, the weighting on the second estimated speed Vs_E2 increases while the weighting on the first estimated speed Vs_E1 becomes relatively smaller.

[0089] According to this configuration, when the hydraulic actuator 32 starts moving, arbitration is performed to weight the second estimated speed Vs_E2 greater than the weight assigned to the first estimated speed Vs_E1, and the drive of the hydraulic actuator 32 is controlled using the arbitrated speed Vs_Ar which has as its main component the second estimated speed Vs_E2 which predicts the future drive state of the hydraulic actuator 32. This makes it possible to suppress instability in control (such as hunting) caused by the effect of a delayed response of the hydraulic actuator 32 due to the inertia of the front working implement 3. Furthermore, when the drive state of the hydraulic actuator 32 exceeds a predetermined state and approaches a steady state, the weighting for the first estimated speed Vs_E1 is increased while the weighting for the second estimated speed Vs_E2 is relatively decreased by performing arbitration, so that the drive of the hydraulic actuator 32 is controlled using an arbitrated speed mainly composed of the first estimated speed Vs_E1 derived based on the actual drive state of the hydraulic actuator 32. Therefore, the drive of the hydraulic actuator 32 can be controlled with higher accuracy than when the second estimated speed Vs_E2, which has lower estimation accuracy than the first estimated speed Vs_E1, is used. That is, the hydraulic actuator 32 can be controlled with high accuracy while ensuring the stability of control when the hydraulic actuator 32 starts moving. In addition, by performing arbitration so that the weighting for the first estimated speed Vs_E1 and the weighting for the second estimated speed Vs_E2 are relatively changed according to the increase or decrease in the degree of deviation α, the arbitrated speed Vs_Ar changes continuously, so that the stability of control using the arbitrated speed Vs_Ar can be ensured.

[0090] Furthermore, in this embodiment, the calculation of the arbitrated speed Vs_Ar by the controller 60 is such that as the degree of deviation β of the first estimated speed Vs_E1 from the required speed Vs_R becomes smaller, the weighting on the first estimated speed Vs_E1 becomes larger while the weighting on the second estimated speed Vs_E2 becomes relatively smaller.

[0091] According to this configuration, when the driving state of the hydraulic actuator 32 exceeds a predetermined state and approaches a steady state, the weight β for the second estimated speed Vs_E2 is reduced, while the weight for the first estimated speed Vs_E1 is relatively increased by arbitration, so that the driving of the hydraulic actuator 32 is controlled using an arbitrated speed mainly composed of the first estimated speed Vs_E1 derived based on the actual driving state of the hydraulic actuator 32, and therefore the driving of the hydraulic actuator 32 can be controlled with higher accuracy than when the second estimated speed Vs_E2, which has lower estimation accuracy than the first estimated speed Vs_E1, is used. In addition, the weight β indicates the degree of deviation of the first estimated speed Vs_E1 from the required speed Vs_R, and therefore serves as an index that reliably reflects whether the driving state of the hydraulic actuator 32 exceeds a predetermined state and approaches a steady state. [Second embodiment] Next, a second embodiment of the work machine of the present invention will be described with reference to Figures 6 to 8. In Figures 6 to 8, the same reference numerals as those in Figures 1 to 5 denote similar parts, and detailed description thereof will be omitted. Figure 6 is a functional block diagram of a controller constituting the second embodiment of the work machine of the present invention. Again, only the drive control (speed control) of the boom cylinder 22 (hydraulic actuator 32) will be described, but the same applies to the drive control (speed control) of the arm cylinder 23 and bucket cylinder 24.

[0092] The second embodiment of the working machine of the present invention differs from the first embodiment in that the arbitration method (method of calculating arbitrated speed Vs_Ar) of the first estimated speed Vs_E1 and the second estimated speed Vs_E2 of the estimated speed arbitration section 74A in the controller 60A shown in Fig. 6 is different. The estimated speed arbitration section 74 of the controller 60 according to the first embodiment calculates the arbitrated speed Vs_Ar by arbitrating the first estimated speed Vs_E1 and the second estimated speed Vs_E2 by continuously changing the ratio of the first estimated speed Vs_E1 and the ratio of the second estimated speed Vs_E2 using two coefficients, weights α and β, for the first estimated speed Vs_E1 and the second estimated speed Vs_E2. In contrast, the estimated speed arbitration unit 74A according to the present embodiment basically calculates the arbitrated speed Vs_Ar by arbitrating the first estimated speed Vs_E1 and the second estimated speed Vs_E2 so as to switch to one of the first estimated speed Vs_E1 and the second estimated speed Vs_E2 according to the magnitude relationship (result of comparison judgment) between the first estimated speed Vs_E1 and the threshold γ. That is, the estimated speed arbitration unit 74A sets a weight of 1 for one of the first estimated speed Vs_E1 and the second estimated speed Vs_E2 and sets a weight of 0 for the other based on the magnitude relationship between the first estimated speed Vs_E1 and the threshold γ. When the magnitude relationship between the first estimated speed Vs_E1 and the threshold γ is inverse, the arbitration unit 74A calculates the arbitrated speed Vs_Ar by arbitrating so as to reverse the weights (0 and 1) set for the first estimated speed Vs_E1 and the second estimated speed Vs_E2.

[0093] Specifically, the estimated speed arbitration unit 74A of the controller 60A first judges whether or not the first estimated speed Vs_E1, which is the calculation result of the first estimated speed calculation unit 72, has reached a threshold value γ. When the hydraulic actuator 32 (boom cylinder 22) is accelerating, the arbitration unit 74A judges whether or not the first estimated speed Vs_E1 is equal to or greater than the threshold value γ. When the hydraulic actuator 32 (boom cylinder 22) is decelerating, the arbitration unit 74A judges whether or not the first estimated speed Vs_E1 is equal to or less than the threshold value γ. The threshold value γ is set to, for example, 80% of the required speed Vs_R, which is the calculation result of the required speed calculation unit 71. This threshold value γ is set to a situation in which the driving state of the hydraulic actuator 32 is assumed to have transitioned from a start state, exceeded a predetermined state, and approached a steady state. Specifically, the posture sensors 28a, 28b, 28c of the third posture detection device 28 are set in a state where they can detect the drive state of the hydraulic actuator 32 almost without being affected by a response delay of the hydraulic actuator 32 caused by the inertia of the driven members 19, 20, 21 of the front working implement 3.

[0094] When the first estimated speed Vs_E1 does not reach the threshold value γ, the estimated speed arbitration unit 74A calculates the second estimated speed Vs_E2, which is the calculation result of the second estimated speed calculation unit 73, as the arbitrated speed Vs_Ar. That is, arbitration is performed so that the weight of the first estimated speed Vs_E1 is set to 0, while the weight of the second estimated speed Vs_E2 is set to 1.

[0095] On the other hand, when the first estimated speed Vs_E1 reaches the threshold value γ, the estimated speed arbitration unit 74A calculates a rate-limited speed V_rlmt for limiting the amount of change in the calculation result of the arbitration speed Vs_Ar.

[0096] Specifically, when the first estimated speed Vs_E1 when the hydraulic actuator 32 (boom cylinder 22) is accelerating is equal to or greater than the rate limit speed V_rlmt of the calculation result, or when the first estimated speed Vs_E1 when the hydraulic actuator 32 (boom cylinder 22) is decelerating is equal to or less than the rate limit speed V_rlmt, the first estimated speed Vs_E1 is calculated as the arbitrated speed Vs_Ar. That is, arbitration is performed so that the weight of the first estimated speed Vs_E1 is set to 1, while the weight of the second estimated speed Vs_E2 is set to 0. Also, when the first estimated speed Vs_E1 during acceleration is smaller than the rate limit speed V_rlmt, or when the first estimated speed Vs_E1 during deceleration is larger than the rate limit speed V_rlmt, the rate limit speed V_rlmt is calculated as the arbitrated speed Vs_Ar.

[0097] The estimated speed arbitration unit 74A basically switches the setting of the arbitrated speed Vs_Ar to either the first estimated speed Vs_E1 or the second estimated speed Vs_E2 using a threshold value γ. However, if the amount of change in the calculation result of the arbitrated speed Vs_Ar is large when switching between the first estimated speed Vs_E1 and the second estimated speed Vs_E2, there is a concern that the stability of control will be impaired due to the sudden change in the arbitrated speed Vs_Ar. Therefore, the rate limit speed V_rlmt is used to limit the amount of change when the arbitrated speed Vs_Ar is switched.

[0098] Specifically, for example, the rate limit speed V_rlmt is calculated using the following equation (5).

[0099]

number

[0100] Here, Vs_E1 is the first estimated speed, Vs_E2 is the second estimated speed, R is the limit rate, and t is the elapsed time from the time when it is determined that the first estimated speed Vs_E1 has reached the threshold value γ. The limit rate R is, for example, a preset fixed value, and is stored in the storage device 61 in advance.

[0101] Next, an example of a control procedure executed by the controller of the second embodiment of the work machine of the present invention will be described with reference to Fig. 7. Fig. 7 is a flow chart showing an example of a control procedure of the controller of the second embodiment of the work machine of the present invention shown in Fig. 6.

[0102] The control procedure of the controller 60A of the second embodiment shown in Fig. 7 differs from the control procedure of the controller 60 of the first embodiment shown in Fig. 4 in that the calculation procedure of the arbitration speed Vs_Ar of steps S42 to S56 is executed instead of the calculation procedure of the arbitration speed Vs_Ar of step S50 of the first embodiment. The other processing procedures, that is, steps S10 to S40 and S60 to S90 shown in Fig. 7, are the same as the processing procedures of the controller 60 of the first embodiment shown in Fig. 4, and the description thereof will be omitted.

[0103] In FIG. 7, a controller 60A according to the present embodiment calculates the arbitration speed Vs_Ar by executing the processes of steps S42 to S56.

[0104] Specifically, first, the estimated speed arbitration unit 74A of the controller 60A judges whether or not the first estimated speed Vs_E1 has reached a threshold value γ (step S42). If the hydraulic actuator 32 is accelerating, it judges whether or not the first estimated speed Vs_E1 is equal to or greater than the threshold value γ. If the hydraulic actuator 32 is decelerating, it judges whether or not the first estimated speed Vs_E1 is equal to or less than the threshold value γ. If the judgment result is YES, the process proceeds to step S44, whereas if the judgment result is NO, the process proceeds to step S52.

[0105] If the result of step S42 is NO, the estimated speed arbitration unit 74A calculates the second estimated speed Vs_E2, which is the calculation result of step S40, as an arbitrated speed Vs_Ar (step S52). That is, arbitration is performed so that the weight of the first estimated speed Vs_E1 is set to 0, while the weight of the second estimated speed Vs_E2 is set to 1.

[0106] On the other hand, if the result of step S42 is YES, the estimated speed arbitration unit 74A calculates a rate limit speed V_rlmt for limiting the amount of change in the arbitration speed Vs_Ar (step S44). The rate limit speed V_rlmt is calculated from the above-mentioned formula (5) using, for example, the first estimated speed Vs_E1, the second estimated speed Vs_E2, the limit rate R which is a set value, and the time t elapsed since the determination of YES in step S42.

[0107] Next, if the hydraulic actuator 32 is accelerating, the estimated speed arbitration unit 74A determines whether or not the first estimated speed Vs_E1 is smaller than the rate limit speed V_rlmt (step S46). If the hydraulic actuator 32 is decelerating, the estimated speed arbitration unit 74A determines whether or not the first estimated speed Vs_E1 is greater than the rate limit speed V_rlmt (step S46). If the determination result is YES, the process proceeds to step S54, whereas if the determination result is NO, the process proceeds to step S56.

[0108] If the result of step S46 is NO, the estimated speed arbitration unit 74A calculates the first estimated speed Vs_E1, which is the calculation result of step S30, as an arbitrated speed Vs_Ar (step S56). That is, arbitration is performed so that the weight of the first estimated speed Vs_E1 is set to 1, while the weight of the second estimated speed Vs_E2 is set to 0.

[0109] On the other hand, if the answer is YES in step S46, the estimated speed arbitration unit 74A calculates the rate limit speed V_rlmt, which is the calculation result of step S44, as the arbitration speed Vs_Ar (step S54). This is an arbitration performed so that the amount of change in the arbitration speed Vs_Ar at the time of switching is limited by the rate limit speed V_rlmt.

[0110] Next, the operation and effects of the second embodiment of the work machine of the present invention will be described. Here, for ease of explanation, the operation of the hydraulic system when operating the boom alone will be described with reference to Fig. 2 and Fig. 8. Fig. 8 is a diagram showing an example of the change over time of the calculation results of various estimated speeds of the hydraulic actuator by the controller in response to an input to the operation device in the second embodiment of the work machine of the present invention. In Fig. 8, the upper diagram shows the change over time of an example of the operation input amount to the operation device, and the lower diagram shows an example of the change over time of various speeds of the boom cylinder which are the calculation results of the controller in response to the operation input amount shown in the upper diagram.

[0111] The operation input of the operation device 58 shown in the upper diagram of Fig. 8 is similar to the operation input of the operation device 58 shown in the upper diagram of Fig. 5 in the case of the first embodiment. That is, at time T1 shown in Fig. 8, a stepwise operation input (solid line in the upper diagram of Fig. 8) is started to the operation device 58.

[0112] As a result, the controller 60A shown in Fig. 6 calculates a required speed Vs_R (long dashed line in the lower diagram of Fig. 8) of the boom cylinder 22 according to the operation input amount L from the operating device 58. This required speed Vs_R is similar to the required speed Vs_R shown by the long dashed line in the lower diagram of Fig. 5 in the case of the first embodiment. The controller 60A outputs command signals to the hydraulic pump 31 and the directional control valve 332 based on the required speed Vs_R.

[0113] At time T2 shown in FIG. 8, similarly to the time T2 shown in FIG. 5 in the first embodiment, the directional control valve 332 shown in FIG. 2 opens in response to the second valve command signal Cv from the controller 60A, thereby supplying pressure oil to the boom cylinder 22. Therefore, the second estimated speed Vs_E2 calculated by the controller 60A based on the opening area of ​​the directional control valve 332 and the front-rear differential pressure is a value other than 0. On the other hand, since the boom 19 remains in a stopped state due to the influence of inertia, etc., the third attitude detection device 28 detects the drive state of the boom cylinder 22 as a stopped state. Therefore, the first estimated speed Vs_E1 calculated by the controller 60A based on the detection value Si of the third attitude detection device 28 becomes 0. Therefore, similarly to the first embodiment, the arbitration speed Vs_Ar is set to the second estimated speed Vs_E2.

[0114] At time T3a shown in FIG. 8, the boom 19 has transitioned to a state in which it is actually operating, similar to the case of time T3 shown in FIG. 5 in the first embodiment. Therefore, the third attitude detection device 28 detects the actual drive of the boom cylinder 22, and the first estimated speed Vs_E1 becomes a value corresponding to the detection value Si of the third attitude detection device 28. However, since the boom cylinder 22 has not yet started moving, the first estimated speed Vs_E1 is a value smaller than the threshold value γ. In this case, unlike the first embodiment, the arbitration speed Vs_Ar is set to the second estimated speed Vs_E2. This is synonymous with arbitration such that the weight of the first estimated speed Vs_E1 is set to 0 and the weight of the second estimated speed Vs_E2 is set to 1.

[0115] At time T5 shown in Fig. 8, the first estimated speed Vs_E1 is greater than the threshold γ. However, the first estimated speed Vs_E1 is smaller than the rate-limited speed V_rlmt. Therefore, the arbitrated speed Vs_Ar is arbitrated to become the rate-limited speed V_rlmt without switching from the second estimated speed Vs_E2 to the first estimated speed Vs_E1. The arbitrated speed Vs_Ar is maintained at the rate-limited speed V_rlmt thereafter, and when the first estimated speed Vs_E1 becomes greater than the rate-limited speed V_rlmt, the rate-limited speed V_rlmt is switched to the first estimated speed Vs_E1.

[0116] At time T4a, when a considerable amount of time has passed since the start time T1 of the operation input, the first estimated speed Vs_E1 is greater than the threshold value γ and greater than the rate limit speed V_rlmt. Therefore, the arbitration speed Vs_Ar is set to the first estimated speed Vs_E1. This is equivalent to arbitration such that the weight of the first estimated speed Vs_E1 is set to 1 and the weight of the second estimated speed Vs_E2 is set to 0.

[0117] In this manner, in this embodiment, when the boom cylinder 22 starts to move immediately after the operation input to the operating device 58 is started, the drive control of the boom cylinder 22 is performed using only the second estimated speed Vs_E2 predicted based on the flow rate of pressure oil supplied to the boom cylinder 22 via the directional control valve 332. Immediately after the operation input is started, the effect of the response delay of the boom cylinder 22 caused by the inertia of the boom 19 is large, so that it is possible to suppress deviation from the required speed Vs_R according to the operation input compared to the case where the first estimated speed Vs_E1 of the boom cylinder 22 calculated based on the actual drive state (almost stopped state) of the boom cylinder 22 is used. Therefore, it is possible to suppress the occurrence of the boom cylinder 22 popping out or hunting due to an excessive correction amount of the feedback control.

[0118] On the other hand, when the actual drive state of the boom cylinder 22 is close to the state corresponding to the operation input, the drive control of the boom cylinder 22 is performed by switching to the first estimated speed Vs_E1 calculated based on the detection value of the attitude sensor 28a that detects the actual drive state of the boom cylinder 22. The first estimated speed Vs_E1 estimates the drive speed of the boom cylinder 22 based on the actual drive state of the boom cylinder 22, so that a highly accurate estimated value can be obtained. Therefore, when the boom cylinder 22 is close to the drive state corresponding to the operation of the operating device 58, the drive control of the boom cylinder 22 is performed by switching to the first estimated speed Vs_E1, which is an estimated value more accurate than the second estimated speed Vs_E2, so that highly accurate control of the boom cylinder 22 can be realized.

[0119] Therefore, in this embodiment, good control accuracy of the hydraulic actuator 32 can be achieved from the drive state of the boom cylinder 22 (hydraulic actuator 32) from the start of movement to a steady state.

[0120] In addition, in this embodiment, by limiting the amount of change in the arbitrated speed Vs_Ar when switching between the first estimated speed Vs_E1 and the second estimated speed Vs_E2, it is possible to smooth the change in the arbitrated speed Vs_Ar when switching between them, thereby ensuring the stability of the control using the arbitrated speed Vs_Ar.

[0121] Also, the actions and effects of this embodiment, like the first embodiment, are considered to be most effective when loading earth and sand after excavation by a hydraulic excavator.

[0122] The controller 60A according to the second embodiment of the working machine of the present invention described above is configured to calculate the arbitrated speed Vs_Ar by arbitrating between the first estimated speed Vs_E1 and the second estimated speed Vs_E2. The calculation of the arbitrated speed Vs_Ar by the controller 60A is such that, when the first estimated speed Vs_E1 is smaller than the threshold value γ during acceleration of the hydraulic actuator 32 or when the first estimated speed Vs_E1 is larger than the threshold value γ during deceleration of the hydraulic actuator 32, the second estimated speed Vs_E2 is calculated as the arbitrated speed Vs_Ar, whereas, when the first estimated speed Vs_E1 is equal to or larger than the threshold value γ during acceleration of the hydraulic actuator 32 or when the first estimated speed Vs_E1 is equal to or smaller than the threshold value γ during deceleration of the hydraulic actuator 32, the first estimated speed Vs_E1 is calculated as the arbitrated speed Vs_Ar. The threshold value γ is set as a value of a predetermined ratio to the required speed Vs_R.

[0123] According to this configuration, when the hydraulic actuator 32 starts moving, arbitration is performed to switch the arbitrated speed Vs_Ar to the second estimated speed Vs_E2, so that the drive of the hydraulic actuator 32 is controlled using the arbitrated speed Vs_Ar, which is the second estimated speed Vs_E2 that predicts the future drive state of the hydraulic actuator 32, thereby making it possible to suppress instability in control (such as hunting) caused by the effect of a response delay of the hydraulic actuator 32 due to the inertia of the front working implement 3. Furthermore, when the drive state of the hydraulic actuator 32 exceeds a predetermined state and approaches a steady state, arbitration is performed to switch the arbitrated speed Vs_Ar to the first estimated speed Vs_E1, so that the drive of the hydraulic actuator 32 is controlled using the arbitrated speed, which is the first estimated speed Vs_E1 derived based on the actual drive state of the hydraulic actuator 32, thereby making it possible to control the drive of the hydraulic actuator 32 with higher accuracy than when the second estimated speed Vs_E2, which has lower estimation accuracy than the first estimated speed Vs_E1, is used. That is, it is possible to ensure the stability of control when the hydraulic actuator 32 starts to move, while enabling highly accurate control of the hydraulic actuator 32.

[0124] Furthermore, in this embodiment, the calculation of the arbitration speed by the controller limits the amount of change before and after switching between the first estimated speed and the second estimated speed.

[0125] According to this configuration, by limiting the amount of change in the arbitration speed before and after switching between the first estimated speed and the second estimated speed, the change in the arbitration speed Vs_Ar can be smoothed, thereby ensuring the stability of control using the arbitration speed Vs_Ar.

[0126] [Other embodiments] Although the first and second embodiments described above show an example in which the present invention is applied to a hydraulic excavator, the present invention can be widely applied to various types of work machines equipped with a work implement driven by a hydraulic actuator.

[0127] Furthermore, the present invention is not limited to the above-described embodiment, and various modified examples are included. The above-described embodiment has been described in detail to easily explain the present invention, and is not necessarily limited to those having all of the configurations described. For example, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0128] For example, in the above-described embodiment, an example of a configuration has been shown in which the current sensors 55, 56 that detect the current value of the second valve command signal Cv to the second solenoid proportional valves 44, 45 are used as detectors that detect a physical quantity related to the opening area of ​​the directional control valve 332. However, it is also possible to use a pressure sensor that detects the pilot pressure input to the fluid pressure ports 332a, 332b of the directional control valve 332 or a spool displacement sensor that detects the displacement of the spool of the directional control valve 332 as the detector. The opening area of ​​the directional control valve 332 can be estimated by calculating the displacement of the spool of the directional control valve 332 based on the pilot pressure detected by the pressure sensor and the detection value of the spool displacement sensor.

[0129] In the above-described first embodiment, an example of a configuration in which the controller 60 calculates the arbitrated speed Vs_Ar using the above-described formula (2) has been shown. That is, an example of a configuration in which the controller 60 calculates the arbitrated speed Vs_Ar using two weights, the weight α defined by the above-described formula (3) and the weight β defined by the above-described formula (4), has been shown. However, the controller 60 can also be configured to calculate the arbitrated speed Vs_Ar using only the weight α. However, in this case, the control accuracy of the hydraulic actuator may be inferior to the case in which the two coefficients, the weight α and the weight β, are used.

[0130] In the above-described second embodiment, an example of the controller 60A configured to calculate the arbitration speed Vs_Ar using the rate limit speed V_rlmt when the first estimated speed Vs_E1 reaches the threshold value γ has been shown. However, the controller 60A can be configured to calculate the arbitration speed Vs_Ar so as to switch between the first estimated speed Vs_E1 and the second estimated speed Vs_E2 depending on the magnitude relationship between the first estimated speed Vs_E1 and the threshold value γ (result of comparison determination) without using the rate limit speed V_rlmt. However, the amount of change in the arbitration speed Vs_Ar may change more suddenly than in the case of the configuration using the rate limit speed V_rlmt, resulting in a decrease in stability of control. [summary] In summary, the work machine according to the embodiment of the present invention described above comprises a hydraulic pump 31 that discharges pressurized oil, a hydraulic actuator 32 that is driven by pressurized oil supplied from the hydraulic pump 31, a directional control valve 332 that controls the flow of pressurized oil supplied from the hydraulic pump 31 to the hydraulic actuator 32, driven members 19, 20, 21 that operate by driving the hydraulic actuator 32, an operation device 58 that outputs an operation signal that instructs the operation of the driven members 19, 20, 21, a third attitude detection device 28 (first detection device) that detects operation information of the driven members 19, 20, 21, a first pressure sensor 51, a second pressure sensor 52, 53 and current sensors 55, 56 that constitute a second detection device that detects information related to the flow rate of pressurized oil supplied to the hydraulic actuator 32 via the directional control valve 332, and controllers 60, 60A that control the operation of the hydraulic pump 31 and the directional control valve 332. The controllers 60, 60A are configured to calculate a required speed Vs_R of the hydraulic actuator 32 based on an operation signal from the operating device 58, calculate a speed of the hydraulic actuator 32 estimated based on the detection value of the third attitude detection device 28 (first detection device) as a first estimated speed Vs_E1, calculate a speed of the hydraulic actuator 32 estimated based on the detection values ​​of the first pressure sensor 51, the second pressure sensors 52, 53, and the current sensors 55, 56 (second detection devices) that constitute the second detection device as a second estimated speed Vs_E2, calculate an arbitrated speed Vs_Ar by arbitrating the first estimated speed Vs_E1 and the second estimated speed Vs_E2 in accordance with the driving state of the hydraulic actuator 32, and control the driving of the hydraulic pump 31 and the directional control valve 332 based on the deviation between the required speed Vs_R and the arbitrated speed Vs_Ar. The calculation of the arbitrated speed Vs_Ar by the controllers 60, 60A is such that when it is possible to determine based on the first estimated speed Vs_E1 that the driving state of the hydraulic actuator 32 is starting to move, the arbitration is performed so that the influence on the second estimated speed Vs_E2 is greater than the influence on the first estimated speed Vs_E1, whereas when it is possible to determine based on the first estimated speed Vs_E1 that the driving state of the hydraulic actuator 32 has exceeded a predetermined state and is approaching a steady state, the arbitration is performed so that the influence on the first estimated speed Vs_E1 is greater than the influence on the second estimated speed Vs_E2.

[0131] According to this configuration, when the drive state of the hydraulic actuator 32 is starting to move, the drive of the hydraulic actuator 32 is controlled using the second estimated speed Vs_E2 that predicts the future drive state of the hydraulic actuator 32, so that it is possible to suppress the jumping out and hunting of the hydraulic actuator 32 due to the effect of a response delay of the hydraulic actuator 32 caused by the inertia of the driven members 19, 20, 21. In addition, when the drive of the hydraulic actuator 32 is approaching a steady state, the drive of the hydraulic actuator 32 is controlled using the first estimated speed Vs_E1 derived based on the actual drive state of the hydraulic actuator 32, so that the drive of the hydraulic actuator 32 can be controlled with higher accuracy than when the second estimated speed Vs_E2, which has lower estimation accuracy than the first estimated speed Vs_E1, is used. In other words, it is possible to control the hydraulic actuator 32 with high accuracy while ensuring the stability of control when the hydraulic actuator 32 starts to move. [Explanation of symbols]

[0132] DESCRIPTION OF SYMBOLS 19... Boom (driven member), 20... Arm (driven member), 21... Bucket (driven member), 22... Boom cylinder (hydraulic actuator), 23... Arm cylinder (hydraulic actuator), 24... Bucket cylinder (hydraulic actuator), 28... Third attitude detection device (first detection device), 31... Hydraulic pump, 332... Directional control valve, 51... First pressure sensor (second detection device), 52, 53... Second pressure sensor (second detection device), 55, 56... Current sensor (second detection device), 58... Operation device, 60, 60A... Controller

Claims

1. A hydraulic pump that discharges pressure oil; a hydraulic actuator driven by pressure oil supplied from the hydraulic pump; a directional control valve for controlling a flow of pressure oil supplied from the hydraulic pump to the hydraulic actuator; a driven member that is operated by driving the hydraulic actuator; an operating device that outputs an operating signal that instructs an operation of the driven member; A first detection device that detects operation information of the driven member; a second detection device that detects information related to a flow rate of pressure oil supplied to the hydraulic actuator via the directional control valve; A working machine including a controller for controlling the drive of the hydraulic pump and the directional control valve, The controller: Calculating a required speed of the hydraulic actuator based on an operation signal of the operating device; calculating a speed of the hydraulic actuator estimated based on a detection value of the first detection device as a first estimated speed; calculating a speed of the hydraulic actuator estimated based on a detection value of the second detection device as a second estimated speed; calculating an adjusted speed by adjusting the first estimated speed and the second estimated speed in accordance with a drive state of the hydraulic actuator; a control unit configured to control the operation of the hydraulic pump and the directional control valve based on a deviation between the requested speed and the adjusted speed; The calculation of the arbitration speed by the controller includes: When it is possible to determine that the drive state of the hydraulic actuator is a start-of-motion state based on the first estimated speed, an adjustment is made so that the degree of influence on the second estimated speed is greater than the degree of influence on the first estimated speed, When it is possible to determine that the drive state of the hydraulic actuator has exceeded a predetermined state and is approaching a steady state based on the first estimated speed, an adjustment is performed so that the degree of influence on the first estimated speed is greater than the degree of influence on the second estimated speed. A working machine characterized by:

2. 2. The work machine according to claim 1, The calculation of the arbitration speed by the controller is performed such that, as the degree of deviation of the first estimated speed from the second estimated speed increases, the influence on the second estimated speed increases, while the influence on the first estimated speed becomes relatively smaller. A working machine characterized by:

3. 3. The work machine according to claim 2, The calculation of the arbitration speed by the controller is performed such that, as the degree of deviation of the first estimated speed from the requested speed becomes smaller, the influence on the first estimated speed becomes larger, while the influence on the second estimated speed becomes relatively smaller. A working machine characterized by:

4. 2. The work machine according to claim 1, the controller is configured to calculate the arbitrated speed by arbitrating between the first estimated speed and the second estimated speed; The calculation of the arbitration speed by the controller includes: When the first estimated speed is smaller than a threshold value during acceleration of the hydraulic actuator or when the first estimated speed is greater than a threshold value during deceleration of the hydraulic actuator, the second estimated speed is calculated as the arbitration speed, when the first estimated speed is equal to or greater than a threshold value when the hydraulic actuator is accelerating, or when the first estimated speed is equal to or less than a threshold value when the hydraulic actuator is decelerating, the first estimated speed is calculated as the adjusted speed, The threshold value is set as a predetermined percentage of the requested speed. A working machine characterized by:

5. 5. The working machine according to claim 4, The calculation of the arbitration speed by the controller limits the amount of change before and after switching between the first estimated speed and the second estimated speed. A working machine characterized by:

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