Work machine

Abstract

An estimated movement path of the toe of a bucket is calculated on the basis of the orientation of a work device and a required operating direction, and a positional relationship between a target plane and the estimated movement path is calculated, and if it is determined by means of the calculated positional relationship that the estimated movement path intersects the target plane, the toe speed of the bucket is restricted while maintaining the required operating direction, and if it is determined by means of the calculated positional relationship that the estimated movement path does not intersect the target plane, the toe speed of the bucket is controlled by means of a toe speed based on an operation signal output from an operating device. As a result, unnecessary speed restriction is not imposed when there is no possibility of deviating from the target plane, and even if there is a change of state such that deviation toward the target plane is anticipated, good operability can be secured by appropriately performing deceleration and stop control.

Description

Work machinery

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

[0002] Known work machines used in road construction, building construction, civil engineering, dredging, and the like include a work machine body having a rotating body rotatably attached to the upper part of a traveling body that travels by a power system, a multi-jointed work front attached to the work machine body so as to be able to swing freely in the vertical direction, and each front member constituting the work front is driven by a cylinder. One example is a so-called hydraulic excavator having a work front composed of a boom, an arm, a bucket, and the like. Some hydraulic excavators of this type perform so-called machine control, in which the target surface to be excavated is set in advance and the boom operation, etc. are automatically controlled in accordance with the amount of arm operation by the operator so that the bucket can excavate along the target surface.

[0003] Since machine control is a semi-automatic control function in which a controller controls front operations and an operator manually operates the controls, importance is placed on both control accuracy and ease of operation by the operator. Prior art related to machine control is known, for example, from Patent Document 1 and Patent Document 2.

[0004] Patent Document 1 discloses a construction machinery control system that, when calculating the speed limit of the work equipment from the target surface distance and the target speed of the work implement, limits the speed of the boom rather than the arm, thereby relaxing the speed limit of the arm, which is strongly influenced by the operator's operating intention during excavation, and minimizing any discomfort felt by the operator.

[0005] Patent Document 2 discloses a work machine that determines whether or not there is a possibility that the work implement will intrude into the target surface when operating the arm, based on a set target surface and signals from a position sensor and an attitude sensor, and if it is determined that there is no possibility that the work implement will intrude into the target surface, controls the speed so that it does not slow down even if the position of the work implement is close to the target surface, understands the operator's intention to move the work implement quickly near the excavation surface, avoids restricting the arm, and minimizes any discomfort to the operator.

[0006] International Publication No. 2014 / 167718 International Publication No. 2021 / 064385

[0007] However, in the conventional technology described in Patent Document 1, the speed limit is calculated according to the distance of the work tool from the target surface. Therefore, even if the trajectory of the moving claw tip cannot deviate from the target surface near the target surface, the operating speed is limited, which may result in a situation contrary to the operator's intention to move quickly, resulting in a deterioration in operability.

[0008] The conventional technology described in Patent Document 2 determines whether or not an intrusion is possible based on the posture state and the input state of the operating lever, and determines whether or not to restrict the work equipment.Therefore, if an input that may indicate an intrusion is suddenly made when it has been determined that no intrusion will occur and the speed is not restricted, a sudden deceleration operation is required, which may result in the operation not being stopped completely and deviating from the target surface, or a shock may occur due to the sudden deceleration, which may impair the operator's operability and workability.

[0009] The present invention has been made in view of the above, and an object of the present invention is to provide a work machine that does not impose unnecessary speed restrictions when there is no possibility of deviation from the target plane, and that can ensure good operability by performing appropriate deceleration and stop control even if the state changes to one in which deviation from the target plane is expected.

[0010] The present application includes a plurality of means for solving the above problems, and one example thereof is a crawler body, an upper rotating body provided so as to be able to rotate relative to the crawler body, a working device having a bucket attached to the upper rotating body and swingable at least in the vertical direction, an actuator for driving the upper rotating body and the working device, an operating device for operating the actuator, an operation amount detection device for detecting an operation amount of the operating device, an attitude detection device for detecting an attitude of the upper rotating body and the working device, a target surface setting device for setting a target surface to be excavated by the bucket, and a control device for calculating a required operation direction for the bucket based on the operation amount detected by the operation amount detection device, and controlling the bucket so that the bucket does not exceed the target surface based on the required operation direction. In a work machine having a control device that calculates an operation command value for the actuator so that the required operation direction is not exceeded, and a drive device that drives the actuator based on the operation command value of the control device, the control device calculates an estimated movement trajectory of the tip of the bucket based on the attitude of the work device and the required operation direction, and calculates the positional relationship between the target surface and the estimated movement trajectory, and if it is determined that the estimated movement trajectory intersects with the target surface based on the calculated positional relationship, it limits the tip of the bucket speed while maintaining the required operation direction, and if it is determined that the estimated movement trajectory does not intersect with the target surface based on the calculated positional relationship, it controls the tip of the bucket speed using a tip speed based on an operation signal output by the operating device.

[0011] According to the present invention, when there is no possibility of deviation from the target surface, unnecessary speed restrictions are not imposed, and even if the state changes to one in which deviation to the target surface is expected, appropriate deceleration and stopping control can be performed, thereby ensuring good operability.

[0012] Fig. 1 is a side view showing a schematic overall configuration of a hydraulic excavator, which is an example of a work machine; Fig. 2 is a diagram showing a main controller together with related configurations; Fig. 3 is a functional block diagram showing the processing contents of the main controller; Fig. 4 is a diagram showing the relationship between a target surface and an estimated toe movement trajectory; Fig. 5 is a diagram showing the relationship between the target surface and an estimated toe movement trajectory; Fig. 6 is a flowchart showing the processing contents of the main controller; Fig. 7 is a flowchart showing the processing contents of the main controller; Fig. 8 is a diagram showing the relationship between the target surface and an estimated toe movement trajectory; Fig. 9 is a diagram showing the relationship between the target surface and an estimated toe movement trajectory.

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] <Target Device> The target of this embodiment is made up of the work machine 1 and a construction target surface. The construction target surface is a construction target surface that has so-called three-dimensional information, that is, information on the left and right directions in addition to the front and rear directions of the work machine 1. The construction target surface may be set relative to the work machine 1, or may be set in a global coordinate system based on the construction site or the Earth.

[0015] <Configuration of the Device> FIG. 1 is a side view showing a schematic overall configuration of a hydraulic excavator, which is an example of a work machine according to this embodiment.

[0016] As shown in Figure 1, the work machine 1 includes a front work unit 2 (working device), a revolving unit 3 (upper revolving unit), and a running unit 4. The revolving unit 3 (upper revolving unit) and the running unit 4 form the work machine main body.

[0017] The front work unit 2 is configured to rotate relative to the rotating unit 3, and the rotating unit 3 is configured to rotate relative to the running unit 4, each centering on a connecting portion. The front work unit 2 includes a boom 20 connected at one end to the rotating unit 3, an arm 21 connected at one end to the boom 20, a bucket 22 connected at one end to the arm 21, a boom cylinder 20A connected at both ends to the boom 20 and the rotating unit 3, respectively, an arm cylinder 21A connected to the arm 21 and the boom 20, respectively, a link A 22B, a link B 22C, and a bucket cylinder 22A connected to link B 22C and the arm 21. These members are configured to rotate vertically, each centering on a connecting portion. The running unit 4 includes a travel motor 41 and a crawler track 45.

[0018] The boom cylinder 20A, arm cylinder 21A, and bucket cylinder 22A are each configured to extend and retract hydraulically, and the extension and contraction can rotate the boom 20, arm 21, and bucket 22. The bucket 22 can be arbitrarily replaced with an attachment (not shown) such as a grapple, breaker, ripper, magnet, or rotary tilt bucket.

[0019] The boom 20 and the arm 21 are respectively equipped with an IMU (Inertial Measurement Unit) (boom) 20S and an IMU (arm) 21S for detecting the attitudes of the boom 20 and the arm 21. The link A 22B is equipped with an IMU (bucket) 22S for detecting the attitude of the bucket 22. The IMU (boom) 20S, IMU (arm) 21S, and IMU (bucket) 22S are each composed of an angular velocity sensor and an acceleration sensor.

[0020] The boom cylinder 20A is equipped with a pressure sensor (boom rod) 20RP and a pressure sensor (boom bottom) 20BP for detecting the load. The arm cylinder 21A is equipped with a pressure sensor (arm rod) 21RP and a pressure sensor (arm bottom) 21BP for detecting the load. The bucket cylinder 22A is equipped with a pressure sensor (bucket rod) 22RP and a pressure sensor (bucket bottom) 22BP for detecting the load.

[0021] The rotating body 3 is equipped with a rotation angle sensor 2S, an IMU (rotating body) 30S, a main frame 31, a driver's cab 32, a main controller 34, a drive unit 35, a prime mover 36, a rotation load measuring device 37, and a position measuring device 250.

[0022] The swing angle sensor 2S is attached so as to be able to detect the relative angle between the running body 4 and the swing body 3.

[0023] The IMU (rotating body) 30S is equipped with an acceleration sensor and an angular velocity sensor, and is attached so as to be able to detect the tilt angle of the rotating body 3.

[0024] The operator's cab 32 is equipped with an operation device 33 , a setting input / display device 100 , and a construction surface management device 2000 .

[0025] The operation device 33 is composed of an operation lever and is provided with an operation amount detection device that detects the amount by which the operation lever is tilted. The operation amount detection device is composed of an operation amount detection sensor such as an angle sensor provided on the operation lever, and is attached so that by detecting the amount by which the operator tilts the operation lever, it can convert the target operation of each movable part requested by the operator into an electric signal.

[0026] The construction surface management device 2000 is connected to the setting input / display device 100 and is installed so as to be able to manage and store the construction target surface that is the target for excavation by the work front 2.

[0027] The setting input / display device 100 is composed of a display monitor and a touch panel, and is attached so that it can display the posture of the work machine 1, information about the construction target surface, the positional relationship and distance between the construction target surface and the work front 2, etc., and can also set various dimensions and mass of the work front 2.

[0028] FIG. 2 is a diagram showing the main controller together with the related components.

[0029] As shown in FIG. 2, the drive device 35 is composed of an electromagnetic control valve and a directional change valve, and is installed so as to operate the drive actuators, that is, the boom cylinder 20A, the arm cylinder 21A, and the bucket cylinder 22A, by driving the electromagnetic control valve and the directional change valve in accordance with operation command values ​​instructed by the main controller 34.

[0030] The prime mover 36, which is the power source, is made up of an engine 36a and a hydraulic pump 36b connected to the output shaft of the engine 36a. More specifically, the hydraulic pump 36b is driven by the power of the engine 36a, and is installed so that the power required to operate the work machine 1 is generated by the pressurized oil discharged by the hydraulic pump 36b.

[0031] The swing load measuring device 37 is made up of a pressure sensor and is attached so as to be able to measure the load in the swing direction of the swing body 3 .

[0032] The running body 4 is equipped with tracks, and the operator can drive the work machine 1 by operating the operating device 33. The running body 4 is not limited to one equipped with tracks, but may be one equipped with running wheels made up of tires. Note that in this embodiment, a mobile work machine equipped with the running body 4 has been described as an example, but the present invention is not limited to this, and may be one that is fixed to a construction site, for example.

[0033] The configuration of the work machine 1 is an example, and the work machine 1 may have a similar device or configuration.

[0034] FIG. 3 is a functional block diagram showing the processing contents of the main controller.

[0035] As shown in FIG. 3, the main controller 34 provided in the work machine 1 is connected to an operation device 33, an attitude detection device 200, a load measurement device 210, a position measurement device 250, a drive device 35, a construction surface management device 2000, and a setting input / display device 100.

[0036] The construction surface management device 2000 is connected to the setting input / display device 100 .

[0037] The driving device 35 is connected to a prime mover 36 and an actuator 2ACT.

[0038] <Detailed Configuration and Function of the Device> <Operation Device 33> The operation device 33 is composed of an operation lever and is provided with an operation amount detection device that detects the amount by which the operation lever is tilted. The amount by which the operator operates the operation lever (i.e., the amount of tilt) is detected by the operation amount detection device and converted into an electrical signal. In hydraulic excavators, the actuator operating speed is generally set to increase as the amount by which the lever is tilted increases, and the operator changes the operating speed of each actuator by changing the amount by which the lever is tilted, thereby operating the work machine. Note that the operation device 33 may be of a hydraulic pilot type or a remotely controlled type, as long as it has equivalent functions.

[0039] <Attitude Detection Device 200> The attitude detection device 200 is equipped with an angular velocity sensor and an acceleration sensor in each of the IMU (swivel unit) 30S, IMU (boom) 20S, IMU (arm) 21S, and IMU (bucket) 22S, and further includes a swing angle sensor 2S. Attitude information of the work machine 1 can be obtained from these IMUs and angle sensors. The boom 20, arm 21, bucket 22, boom cylinder 20A, arm cylinder 21A, bucket cylinder 22A, link A 22B, link B 22C, and revolving unit 3 are each mounted so as to be able to swing, and therefore the attitudes of the boom 20, arm 21, bucket 22, and revolving unit 3 can be estimated from the mechanical link relationships. Note that the attitude detection method shown here is just one example, and the relative angles of each part of the front work unit 2 may be directly measured, or the strokes of the boom cylinder 20A, arm cylinder 21A, and bucket cylinder 22A may be detected to calculate the attitude of each part of the work machine 1.

[0040] <Position measuring device 250> The position measuring device 250 may be a GNSS (Global Navigation Satellite System), a laser positioning device, or a total station. Position measuring devices other than those described above may also be provided as long as they can identify the position of the work machine 1.

[0041] <Drive unit 35> The drive unit 35 is composed of an electromagnetic control valve and a directional change valve, and controls the amount of pressurized oil supplied to the cylinders and hydraulic motors that drive each part of the work machine in accordance with operation command values ​​issued from the main controller 34. The operation command value output from the main controller 34 is converted into pilot pressure by the electromagnetic control valve, and the pilot pressure drives the directional change valve that controls the amount of movement of the actuator. The hydraulic oil, the flow rate of which is adjusted by the directional change valve, is supplied to the cylinders and hydraulic motors that drive each part of the work machine, and drives each moving part. Furthermore, by adding or changing the configuration, it is possible to drive additional attachments and equipment not included above.

[0042] <Motor unit 36> The motor unit 36 ​​is made up of an engine and a hydraulic pump, and generates hydraulic pressure as power required to operate the work machine 1. In addition to the above, the motor unit 36 ​​may also be one that extracts hydraulic power from an electrically driven motor.

[0043] <Actuator 2ACT> The actuator 2ACT is a general term for actuators including the boom cylinder 20A, the arm cylinder 21A, the bucket cylinder 22A, the hydraulic motor for swinging, the hydraulic motor for traveling, and the like.

[0044] <Construction surface management device 2000> The construction surface management device 2000 can set and manage a construction target surface for the work machine 1 using the setting input / display device 100. The construction target surface can be set to have a single plane or multiple planes, making it possible to set the range that can be excavated by the work front 2. The construction target surface may be set relative to the work machine 1 as the base, or may be set in a coordinate system that uses the construction site or the Earth as the base.

[0045] <Setting input / display device 100> The setting input / display device 100 can display to the operator the posture of the work machine 1, area information of the construction target surface set by the construction surface management device 2000, the distance between the work front 2 and the construction target surface, and the like.

[0046] <Main controller 34> As shown in Figure 3, the main controller 34 is connected to the operation device 33, the construction surface management device 2000, the setting input / display device 100, the attitude detection device 200, the position measurement device 250, and the drive device 35, and is composed of an attitude calculation unit 310, a target surface distance calculation unit 320, a required speed calculation unit 330, an estimated toe movement trajectory calculation unit 340, a target surface interference determination unit 350, a required speed holding unit 360, a memory unit 370, a speed limit coefficient calculation unit 400, a target speed calculation unit 410, and an operation command value calculation unit 430.

[0047] The attitude calculation unit 310 calculates the attitude of the work machine 1 based on the information from the attitude detection device 200 .

[0048] The target surface distance calculation unit 320 uses the attitude and position information of the work machine 1 to calculate the distance to the construction target surface (hereinafter referred to as the target surface distance).

[0049] The required speed calculation section 330 calculates the operating speed required of the work machine 1 using the attitude of the work machine 1 and the amount of operation by the operator.

[0050] The estimated toe movement trajectory calculation unit 340 calculates an estimated toe movement trajectory (hereinafter, movement trajectory) by estimating the movement of the bucket toe using the attitude and required speed of the work machine 1.

[0051] The target surface interference determination unit 350 uses the construction target surface information and the movement trajectory to determine whether or not the toe of the bucket is estimated to interfere with the construction target surface.

[0052] The required speed holding unit 360 holds the required speed using the required speed, the target surface interference determination result, and the speed limit coefficient, and applies the held required speed to the speed limit coefficient calculation unit.

[0053] The storage unit 370 is made up of a memory that stores various settings and information input by the setting input / display device 100, and transmits the information to each functional unit of the main controller .

[0054] The speed limit coefficient calculation unit 400 calculates a speed limit coefficient for correcting the required speed in accordance with the posture information of the work machine 1, the target surface distance, the required speed to be maintained, and the target surface interference determination result.

[0055] The target speed calculation unit 410 calculates the target speed of the actuator 2ACT in accordance with the attitude information of the work machine 1, the target surface distance, the required speed and the speed limit coefficient.

[0056] The operation command value calculation unit 430 generates an operation command value for controlling the drive device 35 based on the target speed of the actuator 2 ACT calculated by the target speed calculation unit 410 .

[0057] <Device Operation and Calculation Method> <Machine Control Operation> In machine control, a controller controls the operation of the work machine 1 so that the implement of the work machine 1, which is driven based on operator operation, operates without diving into the target construction surface. For example, when operating the front toward the target surface to perform excavation with a bucket, the front speed is reduced from the approach stage as the toe of the bucket approaches the target surface so that the bucket toe position does not deviate from the target surface, and if the toe is above the target surface, the front operation is restricted so that it does not move any further below the target surface. This control is carried out by calculating the operator's requested speed, which quantitatively gives the operation required by the operator, and calculating the target speed based on the calculation result of the speed limit coefficient.

[0058] <Method of calculating required speed: required speed calculation unit 330> One method of calculating the operator's required movement is to calculate a required speed vector based on the lever operation amount. Since the work machine 1 is all mechanically connected and there is a one-to-one correspondence between the levers operated by the operator and the actuator operations, the lever operation amount can be obtained as the speed of each actuator, that is, the required speed. Therefore, for example, it is possible to express as a vector the direction and extent to which the tip of the bucket 22 (hereinafter simply referred to as the tip) moves in response to the lever operation amount.

[0059] 4 and 5 are diagrams showing the relationship between the target surface and the estimated toe movement trajectory.

[0060] In the case shown in Figure 4, the vector indicates the dotted arrow extending diagonally downward to the right from the toe. Furthermore, if the required speed defined as above is defined as V, the required speed V is decomposed into a speed component V_x parallel to the construction target surface, which is defined by the dotted arrow extending right from the toe, and a speed component V_z perpendicular to the construction target surface, which is defined by the dotted arrow extending downward from the toe. Hereinafter, the component parallel to the construction target surface is defined as the x component, and the component perpendicular to the construction target surface is defined as the z component.

[0061] In the above explanation, a method of calculating a required movement vector based on the lever operation amount has been shown as one method of calculating the operator's required movement, but other methods may be used as long as they can calculate or determine the operator's required movement. Furthermore, V_x and V_z may be corrected by a certain correction value α based on the mass of the work machine. For example, when a sudden lever operation is made, a maximum value is set for the amount of change in the required speed over time, so that acceleration and deceleration can be performed smoothly except in emergencies. By setting the correction value α to a value that does not exceed this maximum value, it becomes possible to perform an operation that follows the operator's intuition that it is difficult to accelerate or decelerate objects with a large mass (this is also an operation that follows physical properties).

[0062] <Method of calculating target surface distance: target surface distance calculation unit 320> As shown in Figure 4, the target surface distance is defined and calculated as the shortest distance d between the toe and the construction target surface. Note that methods other than the above may be used as long as it is possible to define and calculate a variable whose value decreases as the distance between the work machine 1 and the construction target surface decreases.

[0063] <Method of Calculating the Speed ​​Limit Coefficient of the Z Component: Speed ​​Limit Coefficient Calculation Unit 400> The speed limit coefficient of the z component is calculated using the required speed component V_z perpendicular to the construction target surface and the target surface distance d, and is a dimensionless quantity defined by b_z. Here, the closer b_z is to 0, the stronger the speed limit is applied; the closer b_z is to 1, the weaker the speed limit is applied; and when b_z is 1, no speed limit is applied. Furthermore, as shown in the following (Equation 1), (Equation 2), and (Equation 3), when d = 0, b_z = 0, and at a certain target surface distance d1, b_z = 1. When d is greater than 0 and less than d1, b_z also takes a larger value in the range greater than 0 and less than 1 as d increases (i.e., the rate of change b_z' of b_z with respect to d has a positive value), and when d is equal to or greater than d1, it has a constant value of b_z = 1. Generally, d1 takes on a larger value as V_z increases, but d1 may take on any value as long as the work implement of the work machine 1 operates without diving into the target work surface. When b_z calculated by the above method is ultimately transmitted to the target speed calculation, this control is called "deceleration control."

[0064] d = 0; b_z = 0 ... (Equation 1) 0 < d < d1; 0 < b_z < 1 and b_z' > 0 ... (Equation 2) d > = d1; b_z = 1 ... Equation (3) Note that b_z calculated by deceleration control may be rejected depending on the positional relationship between the target surface and the movement trajectory, which will be described later, and may be defined as a different value between 0 and 1.

[0065] <Method of calculating the speed limit coefficient of the x component in deceleration control: speed limit coefficient calculation unit 400> The speed limit coefficient b_x of the x component is calculated as shown in Equation 4 below using the speed limit coefficient b_z of the z component calculated by the above method.

[0066] b_x=b_z (Equation 4) Note that b_z calculated by deceleration control may be rejected depending on the positional relationship between the target surface and the movement trajectory, which will be described later, and may be defined as another value between 0 and 1.

[0067] <Method of calculating movement trajectory: estimated toe movement trajectory calculation unit 340> The movement trajectory is defined by the x-component V_x and z-component V_z of the current attitude and required speed of the work machine 1. First, as shown in Fig. 4 and equation (5), the vector direction θ of the required speed is defined by V_x and V_z.

[0068] θ=Tan^(-1)(V_x / V_z) (Equation 5) Next, assuming that the required speed is the speed given by the boom and arm of the work machine 1, the operation amount ratio of the boom and arm to achieve θ is uniquely determined. If it is assumed that the work machine 1 operates thereafter while maintaining a constant operation amount ratio, it will trace a trajectory that is convex downward and passes through the current toe of the bucket, as shown in Figure 4. This type of trajectory is defined as the "estimated movement trajectory."

[0069] The movement trajectory may be defined over the entire range of motion of the boom and arm of the work machine 1, or may be defined within a range of a separately defined effective length β. Furthermore, if a method other than the above can estimate the movement trajectory with greater accuracy, the movement trajectory may be defined using that method. As the effective length β, for example, it is possible to define the shorter of the length predicted up to a predetermined time later and the length predicted up to the end of the range of motion. It is also possible to determine the effective length β by taking into account the surrounding environment at the time of prediction and the computational cost.

[0070] <Method for calculating the positional relationship between the construction target surface and the movement trajectory: target surface interference determination unit 350> The movement trajectory may have no intersection with the construction target surface as shown in Fig. 4, or may have an intersection with the construction target surface as shown in Fig. 5. If a two-dimensional plane model is assumed and the construction target surface is defined as a straight line with z = 0, for example, it can be determined that if the positive and negative z coordinates of the entire movement trajectory are always constant, there is no intersection with the construction target surface, and if the positive and negative coordinates switch, there is an intersection with the construction target surface.

[0071] If it is possible to make a determination, other numerical models may be defined and used for calculation.

[0072] <Definition and calculation method of limit release control> When the calculation of the positional relationship determines that the construction target surface and the movement trajectory have no intersection with each other, as shown in Fig. 4, the value of the speed limit coefficient b_z of the z component calculated by the deceleration control is discarded and instead applied as b_z = 1. At the same time, the value of the speed limit coefficient b_x of the x component is also applied as b_x = 1.

[0073] Here, it is assumed that the situation where b_x=b_z=1 occurs in (State 1) and (State 2) shown below.

[0074] State 1: When d >= d1 regardless of the relationship between the construction target surface and the movement trajectory State 2: When the construction target surface and the movement trajectory have a relationship in which they do not intersect with each other and d < d1 (State 1) is defined as being in a "deceleration control" state, and (State 2) is defined as being in a "limit release control" state. "Limit release control" is characterized in that if the bucket toe speed were controlled only by the magnitude of the target surface distance d, a target speed smaller than the requested speed would be calculated, but the calculation result is rejected based on the positional relationship between the construction target surface and the movement trajectory, and the target speed is set to a value equal to the requested speed.

[0075] Furthermore, (State 3) is defined as follows:

[0076] State 3: When the construction target surface and the movement trajectory have a mutual intersecting point and d<d1 In a situation switching from (State 1) to (State 3), it is sufficient to continue performing deceleration control, but in a situation switching from (State 2) to (State 3), the time changes of b_x and b_z become significantly large as shown in Figure 8, and there is a risk that control will not be able to be performed in time and the control target surface and the bucket will interfere. Therefore, a calculation to reduce the risk is performed using the method described below.

[0077] <Definition of held toe velocity vector: required velocity holding unit 360> In the limit release control state, assuming a situation in which the state switches from (State 2) to (State 3), the current required velocity is recorded in the required velocity holding unit in order to support the calculation method described below. A velocity vector constructed based on the recorded required velocity is called the held toe velocity vector V_hold.

[0078] <Calculation Method When the Limit Release Control State Switches to a State in Which the Movement Trajectory Interferes with the Target Surface> In the limit release control state, when the bucket switches from (State 2) to (State 3), this is defined as a "limit release deviation." In the "limit release deviation" state, as shown in FIG. 9 , a resultant vector direction Φ is calculated, which is defined by the vector V + V_hold obtained by combining the current toe velocity vector V and the held toe velocity vector V_hold held in the required velocity holding unit. Furthermore, the z-component speed limit coefficient b_z is determined, for example, using one of the above (Equation 1), (Equation 2), and (Equation 3), and the x-component speed limit coefficient b_x is calculated based on Φ and the x-component required velocity V_x. Note that b_z may be determined by another method as long as the bucket does not interfere with the construction target surface.

[0079] <Method of calculating target speed> The x-component V_xlim of the target speed V_lim is calculated using the x-component speed limit coefficient b_x and the x-component V_x of the required speed V as shown in (Equation 6) below, and the z-component V_zlim of the target speed V_lim is calculated using the z-component speed limit coefficient b_z and the z-component V_z of the required speed V as shown in (Equation 7) below.

[0080] V_xlim = b_x × V_x (Equation 6) V_zlim = b_z × V_z (Equation 7) An example of calculation and operation is shown in Figure 9. For example, when the movement trajectory is in a positional relationship where it does not intersect with the construction target surface, the above (Equation 4) holds, and V_xlim is equal to V_x, and V_zlim is equal to V_z. Furthermore, if (State 2) applies, the target speeds V_xlim' and V_zlim', which would be calculated if the bucket toe speed were controlled only by the magnitude of the target surface distance d, are also potentially calculated, but are actually discarded.

[0081] Next, consider the case where the required speed V changes and the state switches to (State 3). In the prior art, the target speed was given in the vector direction equal to the required speed vector, so the movement trajectory does not change due to control. Therefore, if the state switches to (State 3) when the target surface distance d is small, there is a risk that control will not be able to be completed in time and the bucket will interfere with the construction target surface. In contrast, in the present invention, the target speeds V_xlim and V_zlim are given in the vector direction equal to the vector direction Φ defined by the vector V+V_hold, which is a combination of the current toe speed vector V and the held toe speed vector V_hold held in the required speed holding unit, thereby changing the movement trajectory and reducing the risk.

[0082] <Control Procedure> FIGS. 6 and 7 are flowcharts showing the processing contents of the main controller.

[0083] As shown in Figures 6 and 7, first, the main controller 34 acquires and calculates the attitude of the work machine (step S100), acquires and calculates information about the construction target surface (step S110), acquires and calculates the amount of operation by the operator (step S120), calculates the speed required by the operator (step S130), calculates an estimated toe movement trajectory (step S140), calculates the positional relationship between the construction target surface and the estimated toe movement trajectory (step S150), and provisionally calculates the z-component speed limit coefficient b_z based on the target surface distance d (step S160).

[0084] Here, it is determined whether or not there is an intersection between the construction target surface and the estimated toe movement trajectory (step S170).

[0085] If the determination result in step S170 is YES, that is, if it is determined that an intersection exists, it is then determined whether the speed limiting coefficient b_z of the z component temporarily calculated in step S160 is 1 (step S180).

[0086] If the determination result in step S180 is NO, i.e., if the speed limit coefficient b_z is other than 1, it is then determined whether the control mode when the process shown in Figures 6 and 7 was last performed was deceleration control (step S200). Note that if the calculation was not performed immediately before, such as at the start of the process, it is assumed that deceleration control was performed.

[0087] If the determination result in step S200 is YES, the speed limit coefficient b_z of the z component temporarily calculated in step S160 is applied as the numerical value to be passed to the target calculation unit, and further, the speed limit coefficient b_x of the x component is set to the same value as b_z (step S220), and then it is determined that deceleration control is in progress (step S230).

[0088] Furthermore, if the determination result in step S200 is NO, that is, if the previous calculation was not deceleration control, the maintained toe velocity vector and the current toe velocity vector are combined to calculate the vector direction Φ (step S240), the speed limit coefficient b_z of the z component temporarily calculated in step S160 is applied as the numerical value to be passed to the target calculation unit, and further the speed limit coefficient b_x of the x component is calculated so that the vector direction becomes Φ (step S250), and it is determined that the restriction release deviation processing is in progress (step S260).

[0089] Furthermore, if the judgment result in step S170 is NO (i.e., if it is judged that no intersection exists), or if the judgment result in step S180 is YES (i.e., if the speed limit coefficient b_z is 1), the speed limit coefficients b_x and b_z of the x and z components are set to 1 (step S190), and then it is judged whether the speed limit coefficient b_z of the provisionally calculated z component is 1 (step S210).

[0090] If the determination result in step S210 is YES, that is, if the speed limit coefficient b_z is 1, it is determined that deceleration control is being performed (step S270).

[0091] Also, if the determination result in step S210 is NO, that is, if the speed limit coefficient b_z is other than 1, the held toe speed vector is updated to the current toe speed vector (step S280), and it is determined that the limit release control is in progress (step S290).

[0092] After the process of any one of steps S230, S260, S270, and S290 is completed, the target speed is calculated based on the speed limit coefficient calculated in step S190, step S220, or step S250 (step S300).

[0093] Next, an operation command value for operating the work machine is calculated (step S310), and the operation command value is transmitted to the drive device (step S320), and the process ends.

[0094] <Effects of this embodiment> As described above, according to this embodiment, when there is no possibility of deviation from the target surface even when the bucket is near the target surface, it is possible to move the bucket in the direction intended by the operator without imposing unnecessary speed restrictions, and even when the state switches to one in which deviation from the target surface is anticipated, it is possible to appropriately transition to a deceleration / stop control state, thereby ensuring good operability.

[0095] <Others> The present invention is not limited to the above-described embodiments and includes various modifications within the scope of the gist thereof. For example, the present invention is not limited to those including all of the configurations described in the above-described embodiments and includes those in which some of the configurations are omitted. It is also possible to add or replace part of the configuration of one embodiment with the configuration of another embodiment. Furthermore, the components of the above-described control device, as well as their functions and execution processes, may be implemented in part or in whole by hardware (e.g., by designing logic that executes each function using an integrated circuit). Furthermore, the components of the above-described control device may be implemented as a program (software) that is read and executed by an arithmetic processing device (e.g., a CPU) to realize the functions of the control device. Information related to the program may be stored, for example, in semiconductor memory (e.g., flash memory, SSD), magnetic storage device (e.g., hard disk drive), or recording medium (e.g., magnetic disk, optical disk), etc.

[0096] 1...work machine, 2...work front, 2ACT...actuator, 2S...swing angle sensor, 3...swinging body, 4...traveling body, 20...boom, 20A...boom cylinder, 20BP...pressure sensor (boom bottom), 20RP...pressure sensor (boom rod), 20S, 21S, 22S, 30S...IMU (inertial measurement unit), 21...arm, 21A...arm cylinder, 21BP...pressure sensor (arm bottom), 21RP...pressure sensor (arm rod), 22...bucket, 22A...bucket cylinder, 22BP...pressure sensor (bucket bottom), 22RP...pressure sensor (bucket rod), 31...main frame, 32...operation Room, 33...operation device, 34...main controller, 35...drive device, 36...prime mover (36a...engine, 36b...hydraulic pump), 37...turning load measuring device, 41...travel motor, 45...crawler, 100...setting input / display device, 200...attitude detection device, 250...position measurement device, 310...attitude calculation unit, 320...target surface distance calculation unit, 330...required speed calculation unit, 340...estimated toe movement trajectory calculation unit, 350...target surface interference determination unit, 360...required speed holding unit, 370...memory unit, 400...speed limit coefficient calculation unit, 410...target speed calculation unit, 430...motion command value calculation unit, 2000...construction surface management device, A22B, B22C...link

Claims

1. A working machine comprising: a traveling body; an upper swing body rotatably provided with respect to the traveling body; a working device attached to the upper swing body and having a bucket that is swingable at least in the vertical direction; an actuator that drives the upper swing body and the working device respectively; an operating device that operates the actuator; an operation amount detection device that detects an operation amount of the operating device; a posture detection device that detects postures of the upper swing body and the working device; a target surface setting device for setting a target surface to be excavated by the bucket; a control device that calculates a required operation direction for the bucket based on the operation amount detected by the operation amount detection device and calculates an operation command value of the actuator so that the bucket does not exceed the target surface based on the required operation direction; and a drive device that drives the actuator based on the operation command value of the control device. In the working machine, the control device calculates an estimated movement locus of the tip of the bucket based on the posture of the working device and the required operation direction, and calculates a positional relationship between the target surface and the estimated movement locus. When it is determined that the estimated movement locus intersects the target surface based on the calculated positional relationship, the tip speed of the bucket is limited while maintaining the required operation direction. When it is determined that the estimated movement locus does not intersect the target surface based on the calculated positional relationship, the tip speed of the bucket is controlled by the tip speed based on the operation signal output by the operating device.

2. The working machine according to claim 1, wherein when it is determined that the estimated movement locus does not intersect the target surface and the tip speed is controlled based on the operation signal output by the operating device, and when the estimated movement locus changes to a state of intersecting the target surface, the control device calculates a target tip speed based on a composite vector direction of the required operation direction and an actual tip speed vector calculated from a value obtained from a posture sensor.

3. The working machine according to claim 2, wherein the control device corrects the actual tip speed vector using a correction value calculated based on the mass of the working device.

4. In the working machine according to any one of claims 1 to 3, the control device sets the effective length of the estimated movement trajectory to a predetermined value determined in advance starting from the tip of the bucket claw, and calculates the positional relationship between the target surface and the estimated movement trajectory within the range of the effective length. A working machine characterized by this.

Images