Method for excavating material

Abstract

A device is provided for excavating material using an implement of a work machine, and a method of excavating material using an implement of a work machine for remote operation of a work machine. A default excavation mode is selected and excavation is instructed using the default excavation mode. A displacement change of the implement is compared to a first expected threshold, wherein the first expected threshold is based on the instructed excavation using the default excavation mode. In an event that the displacement change of the implement is at or above the first expected threshold, excavation continues using the default excavation mode until a payload of the implement reaches a target payload quantity. In an event that the displacement change of the implement is below the first expected threshold, a secondary excavation mode is selected and excavation is instructed using the secondary excavation mode.

Description

[0001] Description

[0002] METHOD FOR EXCAVATING MATERIAL

[0003] Field of the Disclosure

[0004] The disclosure relates to the field of work machines, and in particular to work machines configured to excavate material.

[0005] Background

[0006] It is known to use a work machine to move material from one location to another. The work machine may excavate the material from a dig location and then dump the material to a dump location, or may simply move material to a dump location. The dump location may be on the ground, in a truck or vehicle, or elsewhere. The work machine may be operated by a user in the work machine, by a remote user, or autonomously.

[0007] Dig locations from which material is to be excavated may vary considerably in terms of type of material, material characteristics, geometry and other factors. Depending on these factors, effective excavation of material may require a different part or parts of an implement of a work machine to be actuated, to provide suitable motions and forces.

[0008] A human operating a work machine from the cab of the work machine may make a judgement as to which part or parts of an implement of a work machine are actuated and how that part or parts is actuated, to achieve an efficient and effective excavation. Such a judgement may be visual, such as by inspection of the dig location and / or the material removed from the dig location. The judgement may instead or additionally be based on other factors, such as a change to resistance against the implement while excavating, or experience from a previous dig cycle at the same dig location.

[0009] Increasingly, work machines are being automated or operated remotely. Visual observations of the dig location or material may not be available, meaning that a remote operator may not be able to rely on such observations to determine whether material remains in or on the implement after depositing material from the implement. Similarly, automated systems for depositing material at dump locations currently operate on limited inputs.

[0010] It is an object of the present disclosure to provide a method of efficiently excavating material using a work machine that does not require the visual observations of an in-situ operator or prior estimation of ground material characteristics.

[0011] Summary of the Disclosure

[0012] Against this background there is provided a device for excavating material using an implement of a work machine, wherein the device is configured to: a. select a default excavation mode and instruct excavation using the default excavation mode; b. compare a displacement change of the implement to a first expected threshold, wherein the first expected threshold is based on the instructed excavation using the default excavation mode; c. in an event that the displacement change of the implement is at or above the first expected threshold, continue to instruct excavation using the default excavation mode until a payload quantity of the implement reaches a target payload quantity; and d. in an event that the displacement change of the implement is below the first expected threshold, select a secondary excavation mode and instruct excavation using the secondary excavation mode.

[0013] In this way, material may be efficiently excavated without visual observations or prior estimation of ground material characteristics. The default excavation mode may allow the implement to pick up a larger amount of material during a dig cycle. However, in certain scenarios such as when the material to be excavated is hard or compacted, the default excavation mode may not be the most efficient choice. Instead, a secondary excavation mode that might provide a more localised force or a stronger force may be used, or that uses the implement at an angle to the ground that is better able to penetrate the ground. The secondary excavation mode may be less preferable for softer or less compacted material, since it may allow the implement to pick up a smaller amount of material during a dig cycle. The device of the present disclosure determined whether the displacement change of the implement is as expected based on the commanded or instructed excavation. If the displacement change of the implement is as expected, excavation may continue using the default excavation mode that allows a larger amount of material to be excavated during a dig cycle. If the displacement change of the implement is lower than expected, the ground may be harder than is suitable for the default excavation mode and excavation may be carried out using the secondary excavation mode. As used herein, a payload of the implement may be any material carried by the implement. The payload quantity may be a volume or a load of the material being carried by the implement.

[0014] A method of excavating material using an implement of a work machine for remote operation of a work machine, the method comprising: a. selecting a default excavation mode and instructing excavation using the default excavation mode; b. comparing a displacement change of the implement to a first expected threshold, wherein the first expected threshold is based on the instructed excavation using the default excavation mode; c. in an event that the displacement change of the implement is at or above the first expected threshold, continuing to excavate using the default excavation mode until a payload quantity of the implement reaches a target payload quantity; and d. in an event that the displacement change of the implement is below an expected threshold, selecting a secondary excavation mode and instructing excavation using the secondary excavation mode.

[0015] Brief Description of the Drawings

[0016] A specific embodiment of the disclosure will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows steps carried out by a device or method according to an embodiment of the present disclosure.

[0017] Figure 2 shows steps carried out by a device or method according to an embodiment of the present disclosure.

[0018] Figure 3 shows steps carried out by a device or method according to an embodiment of the present disclosure.

[0019] Figure 4 shows steps carried out by a device or method according to an embodiment of the present disclosure.

[0020] Figure 5 shows a work machine and implement and illustrates a default excavation mode.

[0021] Figure 6 shows a work machine and implement and illustrates a secondary excavation mode.

[0022] Figure 7 shows a work machine and implement and illustrates a tertiary excavation mode.

[0023] Detailed Description

[0024] A device is provided for excavating material using an implement of a work machine. The device may be any device or controller configured to instruct excavation, and may be on the work machine or remote from the work machine. With reference to Figure 1, the device is configured to select a default excavation mode (at 110) and instruct excavation (at 115) using the default excavation mode. The device is further configured to compare a displacement change of the implement to a first expected threshold at 120. The first expected threshold is based on the instructed excavation using the default excavation mode. In an event that the displacement change of the implement is at or above the first expected threshold (illustrated by arrow 121), the device is configured to continue to instruct excavation using the default excavation mode (at 130) until a payload quantity of the implement reaches a target payload quantity (140). In an event that the displacement change of the implement is below the first expected threshold (illustrated by arrow 122), the device is configured to select a secondary excavation mode at 150 and instruct excavation at step 155 using the secondary excavation mode.

[0025] A dig cycle of the implement may comprise either starting with the implement in a dig start pose, or moving the implement to the dig start pose. The dig cycle may comprise moving the implement from the dig start pose towards a dig stop pose, while picking up or excavating material with the implement such that material is accumulated on or in the implement. The implement may move to the dig stop pose, or the implement may move partway to the dig stop pose and may stop when the implement is determined to have picked up a target payload quantity of material. For example, using the example of an implement comprising a bucket, an implement may move towards the dig stop pose and may stop when a bucket volume estimation determines that the bucket is full or when an estimation of swept volume is above the target payload quantity. This may occur, for example, if the dig stop pose is positioned such that moving the implement fully to the dig stop pose from the dig start pose would excavate more than one bucket volume. In an example, two successive dig cycles may comprise starting with the implement in a dig start pose, moving the implement from the dig start pose towards a dig stop pose while picking up or excavating material with the implement such that material is accumulated on or in the implement (until either the implement reaches the dig stop pose or until a target payload quantity of material has accumulated on or in the implement), moving the implement back to the dig start pose without picking up material, and again moving the implement from the dig start pose towards a dig stop pose while picking up or excavating material with the implement such that material is accumulated on or in the implement. Successive dig cycles may use the same or different dig start poses. Successive dig cycles may use the same or different dig stop poses. Instructing excavation may comprise instructing the work machine to begin or continue a dig cycle. A dig cycle may not include dumping the payload of the implement. An excavation cycle may comprise one or more dig cycles followed by moving the implement to a dump region and depositing the payload of the implement at the dump region. With reference to Figure 2, in an event that the displacement change of the implement is at or above the first expected threshold at 120, the device is configured to instruct excavation using the default excavation mode (at 130) until a payload quantity of the implement reaches a target payload quantity (140). Once the payload of the implement reaches the target payload quantity, the device may be configured to instruct the work machine to dump the payload of the implement at a dump region at 160. For example, the device may instruct the implement to move to a dump region and deposit the payload. The device may be further configured to return the implement to a dig start pose (either the previous dig start pose or a new dig start pose), and repeat steps 110 onwards. In an event that the displacement change of the implement is below the first expected threshold at 120, the device is configured to select a secondary excavation mode (150) and instruct excavation using the secondary excavation mode (155). After instructing excavation using the secondary excavation mode, the device may be configured to instruct the work machine to dump the payload of the implement at a dump region at 170. For example, the device may instruct the implement to move to a dump region and deposit the payload. The device may be further configured to return the implement to the dig start pose, and repeat steps 110 onwards. Optionally, at 155 the device may be configured to instruct excavation using the secondary excavation mode until a payload quantity of the implement reaches a target payload quantity, such that once the payload quantity of the implement reaches the target payload quantity, the device may be configured to instruct the work machine to dump the payload of the implement at a dump region at 170.

[0026] A displacement change of the implement may comprise any change to a position of the implement. The first expected threshold may be indicative of an expected displacement change of the implement when excavation is instructed using the default excavation mode. The expected displacement change may be based on the default excavation and, optionally, may be further based on information relating to the work machine and / or material to be excavated. For example, the expected displacement change may be further based on one or more of a model of work machine, a type of implement, a configuration of implement and a linkage connecting the implement to the work machine, operating characteristics of the work machine, one or more other properties of the work machine or implement, type of material to be excavated, density of the material to be excavated, or one or more other properties of material to be excavated.

[0027] Comparing the displacement change of the implement to the first expected threshold at 120 may comprise determining whether motion of the implement is as expected based on a command or instruction for excavation. For example, for a particular implement, a relationship between a command or instruction and expected movement of the implement may be known. In an event that movement of the implement is impeded by harder ground, the movement of the implement may be less than expected for a given command or instruction.

[0028] Comparing the displacement change of the implement to the first expected threshold at 120 may comprise comparing a position or change in position of the implement to the first expected threshold, wherein the first expected threshold comprises one or more expected positions of the implement. Comparing the displacement change of the implement to the first expected threshold at 120 may comprise comparing a change in position with respect to time (i.e. velocity of the implement) to the first expected threshold, wherein the first expected threshold comprises one or more expected velocities (change in expected position with respect to time) of the implement. The first expected threshold may comprise expected positions or velocities of the implement when the implement is operated in the default excavation mode. The first expected threshold may further be based on an expected material type.

[0029] In certain embodiments, comparing the displacement change of the implement to the first expected threshold may comprise one or more further steps to avoid identifying anomalous or spurious displacement changes that are below the first expected threshold. For example, the device may be configured to average two or more displacement changes, and / or reduce noise (such as by debouncing or via another method), and / or use a filter, and / or take an accumulated or windowed sum of the displacement change, and / or identify and reject anomalous displacement changes.

[0030] In certain embodiments, the first expected threshold may comprise a position of the implement, wherein the position of the implement may be with respect to a frame of reference of the work machine or to a globally-referenced inertial frame of reference. For example, the position of the implement may be with respect to a start position of the implement at the dig start pose. The first expected threshold may vary throughout a dig cycle and may comprise an expected position of the implement at each of a plurality of time intervals from instructing the work machine to begin a dig cycle or from instructing the work machine to move the implement from the dig start pose to the dig stop pose. In other words, the first expected threshold may comprise expected positions of the implement over time when starting from the dig start pose. The first expected threshold may comprise a function of expected position with respect to time, or the first expected threshold may comprise a plurality of expected positions each corresponding to a time point. Comparing a displacement change of the implement to the first expected threshold may comprise comparing a position of the implement at a time point to an expected position at the time point, or comparing a change in position of the implement between two time points to a difference in expected positions at the two time points. In an event that the displacement change is at a time point that does not directly correspond to a time point of the first expected threshold, an expected position may be extrapolated between two or more expected positions, or an expected position may be selected that is at a time point closest to the time point of the displacement change.

[0031] In other embodiments, the first expected threshold may comprise a velocity of the implement, wherein the velocity of the implement may be with respect to a frame of reference of the work machine. The first expected threshold may be constant throughout a dig cycle. Or, the first expected threshold may vary throughout a dig cycle and may comprise an expected velocity of the implement at each of a plurality of time intervals from instructing the work machine to begin a dig cycle. In other words, the first expected threshold may comprise expected velocities of the implement over time when starting from stationary at the dig start pose. The first expected threshold may comprise a plurality of expected velocities each corresponding to a time point, or may comprise a function of expected velocity with respect to time. Comparing a displacement change of the implement to the first expected threshold may comprise comparing a velocity of the implement at a time point to an expected velocity at the time point. Comparing a displacement change of the implement to the first expected threshold may comprise calculating an average velocity using a change in position of the implement between two time points and comparing the average velocity to the expected velocity at or between the two time points. In an event that the displacement change is at a time point that does not directly correspond to a time point of the first expected threshold, an expected velocity may be extrapolated between two or more expected velocities, or an expected velocity may be selected that is at a time point closest to the time point of the displacement change.

[0032] Comparing the displacement change of the implement to the first expected threshold at 120 may be carried out at intervals during a dig cycle, or continuously during a dig cycle.

[0033] Comparing the displacement change of the implement to the first expected threshold at 120 may comprise comparing any property of the work machine that is indicative of movement of the implement to the first expected threshold. The displacement change may be determined using data obtained from one or more sensor of the work machine.

[0034] The displacement change may be determined via one or more of the following examples.

[0035] The displacement change may be determined using data from any kinematic sensor. The displacement change may be determined using data from an inertial measurement unit (IMU). For example, the implement may be connected to the work machine via one or more linkage body and the displacement change may be determined using data from one or more IMU on the one or more linkage body. The displacement change may be determined using data from a rotary joint angle sensor, such as a magnetorestrictive sensor. In an event that the implement comprises a boom, a stick and a bucket, the displacement change may be determined using an IMU on each of the boom and the stick, and a rotary sensor on the bucket. The relative positions and orientations of the boom, stick and bucket may be determined using these sensors.

[0036] The displacement change may be determined using data from a displacement sensor and / or pressure sensor and / or flow sensor of a hydraulic cylinder of the work machine. For example, the implement may be movable using a hydraulic cylinder, and the displacement change may be determined using data from one or more displacement sensor on the hydraulic cylinder. The displacement change may be determined using data from one or more hydraulic flow sensor (wherein hydraulic flow may be converted to displacement change of the implement with respect to time) and one or more hydraulic pressure sensor, wherein the flow sensor(s) and pressure sensor(s) may be used to determine when flow of hydraulic fluid is resulting in cylinder motion (low pressure) or when flow of hydraulic fluid is into a pressure relief valve (high pressure). In other words, the pressure sensor may be used to determine whether or not flow of hydraulic fluid is resulting in cylinder motion and, therefore, movement of the implement. In an event that the implement is connected to the work machine via one or more linkage body, the implement and the one or more linkage body may each be movable using a hydraulic cylinder, and the displacement change may be determined using data from one or more displacement sensor on each hydraulic cylinder and / or one or more hydraulic flow sensor and / or one or more hydraulic pressure sensor. For example, fluid flowing out of a pressure relief valve may indicate increased resistance to movement of the implement and, therefore, a reduced displacement change. The displacement change may be determined using data from a load sensor, such as by determining a digging force. The load sensor may be used in combination with a flow sensor, to determine whether or not flow of hydraulic fluid is resulting in cylinder motion and, therefore, movement of the implement. The displacement change may be determined using data from a tilt sensor of the work machine such as a tilt sensor on a body of the work machine. In an event that resistance to moving the implement increases, the body of the work machine may tilt. The displacement change may be determined using an estimate of a payload quantity of the implement. The displacement change may be determined using data from any other sensor.

[0037] In an example, where the implement is connected to the work machine via one or more linkages, comparing displacement change of the implement to the first expected threshold may comprise determining whether a linkage command results in an expected linkage velocity. The linkage velocity may be a velocity of a linkage cylinderjoint of a linkage or tip of the implement, for example. A linkage velocity may be compared to an expected velocity for a particular command, wherein the first expected threshold may comprise one or more expected velocities each corresponding to a linkage command (or an expected velocity as a function of linkage command). A linkage command may comprise an instruction to move the implement with a particular force and / or torque and / or velocity and / or hydraulic valve opening percentage. In another example, in an event that the implement (or a component connecting the implement to the work machine) is movable using a hydraulic cylinder, a hydraulic head-end pressure may be indicative of movement of the implement. In this case, a higher hydraulic head-end pressure indicates a higher resistance to movement of the implement (that causes hydraulic fluid to flow) and is therefore indicative of a smaller displacement change. Conversely, a lower hydraulic headend pressure indicates a lower resistance to movement of the implement and is therefore indicative of a larger displacement change. Comparing displacement change of the implement to the first expected threshold may comprise comparing an inverse or negative exponent of the hydraulic head-end pressure to the first expected threshold.

[0038] The device is configured to continue to instruct excavation using the default excavation mode (at 130) until a payload quantity of the implement reaches a target payload quantity (140). The device may be configured to check whether the payload quantity of the implement has reached the target payload quantity (or is within a percentage of the target payload quantity) after a dig cycle. The device may be configured to perform the check when the implement reaches the dig stop pose. The device may be configured to perform the check when a bucket volume estimation determines that the bucket is full. The device may be configured to perform the check when a swept volume of the bucket motion has accumulated to more than an expected volume threshold value. The swept volume may be based on the path of swept motion of the implement and an estimated terrain surface, wherein the path of the swept motion is indicative of a trajectory of the implement through the material being excavated. In other words, for a given path of swept motion, the estimated terrain surface may be used to determine the portion of the path of swept motion that passes through the material to be excavated and, therefore, the trajectory that the implement took may be used to determine a volume of material that has been swept by the implement. The path of the swept motion may be determined from a command provided to the work machine to move the implement, or from motion or position sensors of the work machine or implement. The device may be configured to perform the check in an event that a certain length of time has passed since instructing the implement to move from the dig start pose, or in an event that a certain number of dig cycles have occurred since dumping the payload of the implement. The device may be configured to perform the check at another time.

[0039] With reference to Figure 3, in an event that the device has continued to instruct excavation using the default excavation mode at 130, at step 141 the device may be configured to check whether the payload quantity of the implement has reached the target payload quantity. The device may be configured to check whether the payload quantity of the implement has reached the target payload quantity by comparing the payload quantity of the implement to the target payload quantity once the implement has reached the dig stop pose or once an estimation of swept volume is above the target payload quantity before it reaches the dig stop pose (this may occur, for example, if the dig stop pose is positioned such that moving the implement fully to the dig stop pose from the dig start pose would excavate more than one bucket volume). In an event that the payload quantity is less than the target payload quantity the device may be configured to return the implement to the dig start pose and instruct excavation using the default excavation mode at 115. In an event that the payload quantity is equal to or greater than the target payload quantity the device may be configured to instruct the work machine to dump the payload at the dump region at 160. In certain examples, in an event that the payload quantity is less than the target payload quantity but within a certain percentage of the target payload quantity, the device may be configured to instruct the work machine to dump the payload at the dump region at 160. The target payload quantity may be a set value or may depend on factors such as the type or density of material being excavated or a capacity of the implement. As used herein, the payload and the target payload quantity may be a load (i.e. a mass or weight) or a volume of material.

[0040] In an event that the device has instructed excavation in the secondary excavation mode at step 155, at step the device may be configured to continue excavation in the secondary excavation mode. At step 157 the device may be configured to check whether the payload quantity of the implement has reached the target payload quantity by comparing the payload quantity of the implement to the target payload quantity once the implement has reached the dig stop pose or once an estimation of swept volume is above the target payload quantity before it reaches the dig stop pose. In an event that the payload quantity is less than the target payload quantity the device may be configured to return the implement to the dig start pose and instruct excavation using the secondary excavation mode at 156. In an event that the payload quantity is equal to or greater than the target payload quantity the device may be configured to instruct the work machine to dump the payload at the dump region at 170. In certain examples, in an event that the payload quantity is less than the target payload quantity but within a certain percentage of the target payload quantity, the device may be configured to instruct the work machine to dump the payload at the dump region at 170. A payload quantity (such as a load) of the implement may be determined or estimated by any suitable method. In an example, the payload quantity may be determined or estimated by lifting the implement from the ground at the dig stop pose and determining a load on the implement using a load sensor. The payload quantity may be estimated using a strain gauge or strain bridge. The payload quantity may be estimated based on a hydraulic cylinder pressure. In another example, the payload quantity may be estimated using the estimated volume and an estimated density of the material. In another example, the payload quantity may be estimated based on a length of time that has passed since instructing the implement to move from the dig start pose, or based on the number of dig cycles that have occurred since dumping the payload of the implement. In another example the payload quantity may be determined or estimated based on a swept volume of the implement and an estimated terrain surface. The swept volume may be determined from a command provided to the work machine to move the implement, or from motion or position sensors of the work machine or implement. The estimated terrain surface may be determined by any suitable method. For example, the estimated terrain surface may be determined by defining or determining an initial terrain surface prior to any excavation by the work machine (using an estimate, visual inspection, one or more sensors, or other method) and subtracting an estimate of a volume of material excavated for each dig cycle from the initial terrain surface.

[0041] In the description of Figures 1 to 3, in an event that the displacement change of the implement is below the first expected threshold, the device is configured to select a secondary excavation mode and instruct excavation using the secondary excavation mode. In certain embodiments, the device is further configured to compare the displacement change of the implement to a second expected threshold based on the instructed excavation using the secondary excavation mode. In an event that the displacement change of the implement is below the second expected threshold, the device may be further configured to select a tertiary excavation mode and instruct excavation using the tertiary excavation mode. In certain embodiments, in an event that the displacement change of the implement is above the second expected threshold the device may be further configured to determine whether a payload quantity of the implement reaches a target payload quantity. In an event that the payload quantity is at or above the target payload quantity, the device may be configured to instruct the work machine to dump the payload at a dump region. In an event that the payload quantity is below the target payload quantity but above a threshold quantity, the device may be configured to instruct the work machine to continue excavating using the secondary excavation mode until a payload quantity reaches the target payload quantity. The threshold quantity may be a certain percentage of the target payload quantity. In an event that a payload quantity is below the threshold quantity, the device may be configured to select the tertiary excavation mode and instruct excavation using the tertiary excavation mode.

[0042] With reference to Figure 4, the device is configured to select a default excavation mode (at 411) and instruct excavation (at 412) using the default excavation mode. The device is further configured to compare a displacement change of the implement to a first expected threshold at 413. The first expected threshold is based on the instructed excavation using the default excavation mode. In an event that the displacement change of the implement is at or above the first expected threshold, the device is configured to continue to instruct excavation using the default excavation mode (at 414) until a payload quantity of the implement reaches a target payload quantity. At 415, the device may be configured to compare a payload quantity of the implement after a dig cycle to the target payload quantity. In an event that the payload quantity is at or above the target payload quantity (or below the target payload quantity but within a certain tolerance of the target payload quantity), the device may be configured to instruct the work machine to dump the payload at a dump region at 440. In an event that the payload quantity is below the target payload quantity (or below the target payload quantity by more than the certain tolerance of the target payload quantity), the device may be configured to return to step 412 and instruct excavation using the default excavation mode. In certain embodiments, in an event that at 415 the payload quantity is below the target payload quantity, the payload quantity may be compared to a threshold quantity that is a certain percentage of the target payload quantity at step 416. In an event that at 416 the payload quantity is above the threshold quantity, the device may be configured to instruct the work machine to return to step 412 and instruct excavation using the default excavation mode. In an event that at 416 a payload quantity is below the threshold quantity, the device may be configured to select a secondary excavation mode at 421 and instruct excavation using the secondary excavation mode at 422. In other embodiments, step 416 may comprise a different check. For example, at step 416 the device may be configured to estimate an added quantity of material that was excavated (added to the payload) during that dig cycle, and compare the added quantity to a threshold added quantity. In an event that at 416 the added payload quantity is above the threshold added quantity, the device may be configured to instruct the work machine to return to step 412 and instruct excavation using the default excavation mode. In an event that at 416 the added payload quantity is below the threshold added quantity, the device may be configured to select a secondary excavation mode at 421 and instruct excavation using the secondary excavation mode at 422. In another example, at step 416 the device may be configured to determine whether a number of dig cycles during the current excavation cycle has reached a maximum number of dig cycles. In an event that the number of dig cycles is below the maximum number of dig cycles, the device may be configured to instruct the work machine to return to step 412 and instruct excavation using the default excavation mode. In an event that the number of dig cycles is at (or above) the maximum number of dig cycles, the device may be configured to select a secondary excavation mode at 421 and instruct excavation using the secondary excavation mode at 422.

[0043] In an event that at 413 the displacement change of the implement is below the first expected threshold, the device is configured to select a secondary excavation mode at 421 and instruct excavation at step 422 using the secondary excavation mode. The device may be further configured to compare a displacement change of the implement to a second expected threshold at 423. The second expected threshold is based on the instructed excavation using the secondary excavation mode. In an event that the displacement change of the implement is at or above the second expected threshold, the device is configured to continue to instruct excavation using the secondary excavation mode (at 424) until a payload quantity of the implement reaches a target payload quantity. At 425, the device may be configured to compare a payload quantity of the implement after a dig cycle to the target payload quantity.

[0044] In an event that at 425 the payload quantity is at or above the target payload quantity (or below the target payload quantity but within a certain tolerance of the target payload quantity), the device may be configured to instruct the work machine to dump the payload at a dump region at 440. For the next excavation cycle, the device may be configured to select the default excavation mode at step 411. Alternatively, for the next excavation cycle, the device may be configured to select the secondary excavation mode at step 421.

[0045] In an event that at 425 the payload quantity is below the target payload quantity, the payload quantity may be compared to a threshold quantity that is a certain percentage of the target payload quantity at step 426. In an event that at 426 the payload quantity is above the threshold quantity, the device may be configured to instruct the work machine to return to step 422 and instruct excavation using the secondary excavation mode. In an event that at 426 a payload quantity is below the threshold quantity, the device may be configured to select a tertiary excavation mode at 431 and instruct excavation using the tertiary excavation mode at 432. In other embodiments, step 426 may comprise a different check. For example, at step 426 the device may be configured to estimate an added quantity of material that was excavated (added to the payload) during that dig cycle, and compare the added quantity to a threshold added quantity. In an event that at 426 the added payload quantity is above the threshold added quantity, the device may be configured to instruct the work machine to return to step 422 and instruct excavation using the secondary excavation mode. In an event that at 426 the added payload quantity is below the threshold added quantity, the device may be configured to select a tertiary excavation mode at 431 and instruct excavation using the tertiary excavation mode at 432. In another example, at step 426 the device may be configured to determine whether a number of dig cycles during the current excavation cycle has reached a maximum number of dig cycles. In an event that the number of dig cycles is below the maximum number of dig cycles, the device may be configured to instruct the work machine to return to step 422 and instruct excavation using the secondary excavation mode. In an event that the number of dig cycles is at (or above) the maximum number of dig cycles, the device may be configured to select a tertiary excavation mode at 431 and instruct excavation using the tertiary excavation mode at 432.

[0046] In an event that at 423 the displacement change of the implement is below the second expected threshold, the device is configured to select the tertiary excavation mode at 431 and instruct excavation at step 432 using the tertiary excavation mode. The device may be further configured to compare a displacement change of the implement to a third expected threshold at 433. The third expected threshold is based on the instructed excavation using the tertiary excavation mode. In an event that the displacement change of the implement is at or above the third expected threshold, the device may be configured to continue to instruct excavation using the tertiary excavation mode (at 434) until a payload quantity of the implement reaches a target payload quantity. At 435, the device may be configured to compare a payload quantity of the implement after a dig cycle to the target payload quantity. In an event that the payload quantity is at or above the target payload quantity (or below the target payload quantity but within a certain tolerance of the target payload quantity), the device may be configured to instruct the work machine to dump the payload at a dump region at 440. For the next excavation cycle, the device may be configured to select the default excavation mode at step 411. Alternatively, for the next excavation cycle, the device may be configured to select the secondary excavation mode at step 421 or the device may be configured to select the tertiary excavation mode at step 431. In an event that the payload quantity is below the target payload quantity, the load may be compared to a threshold quantity that is a certain percentage of the target payload quantity at step 436. In an event that at 436 the payload quantity is above the threshold quantity, the device may be configured to instruct the work machine to return to step 432 and instruct excavation using the tertiary excavation mode. In an event that at 436 a payload quantity is below the threshold quantity, the device may instruct excavation to end. In an event that at 433 the displacement change of the implement is below the third expected threshold, the device may instruct excavation to end. In other embodiments, step 436 may comprise a different check. For example, at step 436 the device may be configured to estimate an added quantity of material that was excavated (added to the payload) during that dig cycle, and compare the added quantity to a threshold added quantity. In an event that at 436 the added payload quantity is above the threshold added quantity, the device may be configured to instruct the work machine to return to step 432 and instruct excavation using the tertiary excavation mode. In an event that at 436 the added payload quantity is below the threshold added quantity, the device may instruct excavation to end. In another example, at step 436 the device may be configured to determine whether a number of dig cycles during the current excavation cycle has reached a maximum number of dig cycles. In an event that the number of dig cycles is below the maximum number of dig cycles, the device may be configured to instruct the work machine to return to step 432 and instruct excavation using the tertiary excavation mode. In an event that the number of dig cycles is at (or above) the maximum number of dig cycles, the device may instruct excavation to end.

[0047] After instructing the work machine to dump the payload at the dump region at step 440, the device may be configured to determine whether further excavation is required at step 450. If no further excavation is required the device may be configured to end excavation. If further excavation is required the device may be configured to return to step 411 and select the default excavation mode. Step 450 may comprise comparing a total payload volume for one or more excavation cycles to a total required excavation volume. The device may be further configured to record whether an excavation cycle is normal or abnormal. A normal excavation cycle may be one in which the device only instructs excavation in the default excavation mode, and / or in which the target payload quantity is excavated. An abnormal excavation cycle may be one in which the secondary excavation mode is selected and / or the tertiary excavation mode is selected and / or a payload quantity below the target payload quantity is excavated. The device may be further configured to start a subsequent excavation cycle in either the secondary or tertiary excavation modes in an event that the recorded number of abnormal excavation cycles exceeds a cycle threshold. The device may be further configured to start a subsequent excavation cycle in either the secondary or tertiary excavation modes either in an event that more than a certain number of consecutive excavation cycles are recorded as abnormal cycles, or in an event that more than a certain proportion of consecutive excavation cycles are recorded as abnormal cycles, or in an event that consecutive abnormal excavation cycles exceed a certain time period.

[0048] The device may be further configured to record whether each excavation cycle is started in the default excavation mode or in either the secondary or tertiary excavation modes. The cycle threshold may depend on the proportion of excavation cycles that are started in the default excavation mode. In an event that the proportion of excavation cycles that are started in the default excavation mode increases, the cycle threshold may increase (but may not exceed an upper limit) such that the subsequent excavation cycle is more likely to be started in the default excavation mode. In an event that the proportion of excavation cycles that are started in the default excavation mode decreases, the cycle threshold may decrease (but not past a lower limit) such that the subsequent excavation cycle is less likely to be started in the default excavation mode and more likely to be started in either the secondary or tertiary excavation modes.

[0049] The implement may comprise one or more components or linkages configured to connect an implement to the work machine. For example, the implement may comprise a linkage configured to connect a bucket to the work machine. The implement may comprise a boom, a stick and a bucket. A first distal end of the stick may be connected to a distal end of the boom. The bucket may be connected to a second distal end of the stick. The implement may comprise a first hydraulic cylinder configured to move the boom relative to a body of the work machine, a second hydraulic cylinder configured to move the stick relative to the boom and a third hydraulic cylinder configured to move the bucket relative to the stick.

[0050] An example of an implement of a work machine 500 is illustrated in Figure 5, wherein the implement comprises a boom 510, a stick 520 and a bucket 530. A first distal end 522 of the stick 520 may be connected to a distal end of the boom 510. The bucket 530 may be connected to a second distal end 523 of the stick 520. The implement may comprise a first hydraulic cylinder 511 configured to move the boom 510 relative to a body 540 of the work machine, a second hydraulic cylinder 521 configured to move the stick 520 relative to the boom 510 and a third hydraulic cylinder 531 configured to move the bucket 530 relative to the stick 520.

[0051] In certain embodiments, the default excavation mode comprises rotation of the stick 520 relative to the boom 510 about the first distal end 522 of the stick 520. This may be referred to as a stick digging mode. A resulting movement of the bucket 530 is illustrated by arrow 550, wherein dashed line 551 indicates that the rotation of the bucket 530 is centred about the first distal end 522 of the stick 520 (or, in other words, about a joint between the stick 520 and the boom 510). Rotation of the stick 520 about the joint between the boom 510 and the stick 520 may result in efficient excavation that achieves a relatively large arc of the bucket 530 in the material to be excavated, and that fills the bucket well. Rotation of the stick 520 about the joint between the boom 510 and the stick 520 may be more effective in excavating softer or looser material than in excavating harder or more compacted material. In certain embodiments, at a dig start pose the stick 520 may be angled at 30° or between 0° and 45° from a vertical (the vertical being relative to a frame of reference of the work machine, such that the vertical is perpendicular to tracks of work machine, or the vertical being perpendicular to the ground), achieving a desired breakout force into the ground. The stick digging mode may, in certain examples, further comprise other rotations of the implement in addition to rotation of the stick 520 relative to the boom 510 (such as rotation of the boom 510 relative to the body 540 of the work machine or rotation of the bucket 530 relative to the stick 520), wherein these additional rotations may be smaller than the rotation of the stick 520 relative to the boom 510.

[0052] With reference to Figure 6, the secondary excavation mode may comprise rotation of the bucket 530 relative to the stick 520 about the second distal end 523 of the stick 520. This may be referred to as a bucket digging mode. A resulting movement of the bucket 530 is illustrated by arrow 610, wherein dashed line 611 indicates that the rotation of the bucket 530 is centred about the second distal end 523 of the stick 520 (or, in other words, about a joint between the stick 520 and the bucket 530). The arc of the bucket is smaller than when using the stick digging mode illustrated in Figure 5. In certain embodiments, the stick 520 may be stationary relative to the boom 510 or may rotate by a small angle relative to the boom 510. Rotation of the bucket 530 relative to the stick 520 may achieve a more localised force on the ground than rotation of the stick 520 relative to the boom 510, making the bucket digging mode more suitable for harder or more compacted material than the stick digging mode. The bucket digging mode may excavate a smaller volume with respect to time per dig cycle than the stick digging mode, due to the smaller arc. The bucket sweeps a lower volume per unit hydraulic cylinder length extension. In use, the bucket digging mode may be used to create a small hole in the ground, and the stick digging mode may then be used to start within the small hole. For example, the bucket digging mode may penetrate a harder crust on the surface of the ground, allowing the stick digging mode to then be used to peel layers of material starting from within the small hole. The bucket digging mode may, in certain examples, further comprise other rotations of the implement in addition to rotation of the bucket relative to the stick (such as rotation of the boom 510 relative to the body 540 of the work machine or rotation of the stick 520 relative to the boom 510), wherein these additional rotations may be smaller than the rotation of the bucket 530 relative to the stick 530.

[0053] With reference to Figure 7, the tertiary excavation mode may comprise linear movement of a bucket frame of reference relative to either a plane of the ground or an inertial frame of reference or a machine frame of reference. This may be referred to as a flat digging mode. A resulting movement of the bucket 530 is illustrated by arrow 710. The plane of movement of the bucket may not be horizontal (wherein horizontal is perpendicular to the gravity vector). The flat digging mode may use coordinated movement of each of the boom 510, stick 520 and bucket 530 to achieve a linear trajectory of the bucket that is parallel to the ground surface, such that in use the bucket 530 scrapes off a top layer of ground. The angle of the bucket 530 relative to the ground may be such that teeth and bottom cutting surface of the bucket 530 are flat relative to the ground and cut a layer parallel to the ground surface.

[0054] Other excavation modes are possible for the default excavation mode, the secondary excavation mode and the tertiary excavation mode. In general, the default excavation mode may excavate faster than the secondary and tertiary excavation modes (excavating a larger volume of material per unit time, due to sweeping a higher volume per unit hydraulic cylinder length extension), in an event that the displacement change of the implement is as expected in the default excavation mode. In general, the secondary and tertiary excavation modes may apply a more localised or stronger force on the ground but may excavate more slowly (may excavate a smaller volume of material per unit time).

[0055] In use, the work machine may be moved to an excavation site, either by an operator, in response to remote commands, or autonomously. A dig region may be identified and a dump region may be identified, wherein the device is configured to instruct excavation from the dig region and to instruct depositing material at the dump region. In certain examples, the work machine may remain in a particular location while excavating and while dumping material, and may be configured to swing between a first rotational position at which the work machine is configured to excavate from the dig region and a second rotational position at which the work machine is configured to deposit material at the dump region. The work machine may be configured to rotate the implement between the first rotational position and the second rotational position, and / or rotate a body of the work machine between the first rotational position and the second rotational position. In other examples the work machine may move between a first location at which the work machine is configured to excavate from the dig region and a second location at which the work machine is configured to deposit material at the dump region.

[0056] In use, the device may be configured to begin excavation of the ground in the stick digging mode. In an event that the displacement change of the implement is below a first expected threshold, this may be indicative that motion of the implement is not as instructed based on control commands, which in turn may be indicative of harder ground. The device may be configured to select the bucket digging mode and instruct excavation in the bucket digging mode. In an event that the displacement change of the implement is at or above a second expected threshold, the device may be configured to continue to instruct excavation in the bucket digging mode for the remainder of the excavation cycle. More than one dig cycle may be carried out in the bucket digging mode to reach the target payload quantity. For the next excavation cycle, the device may return to the stick digging mode and may again compare the displacement change of the implement to the first expected threshold. In an event that the displacement change of the implement is below the second expected threshold, or in an event that after a certain number of dig cycles a threshold payload has not been reached, the device may be configured to select the flat digging mode. The device may be configured to continue to instruct excavation in the flat digging mode for a certain length of time or for a certain number of dig cycles or for a certain number of excavation cycles. The device may then be configured to return to the stick digging mode or to the bucket digging mode.

[0057] A method is provided of excavating material using an implement of a work machine for remote operation of a work machine. The method may comprise any of the steps laid out above that the device is configured to perform. The method comprises selecting a default excavation mode and instructing excavation using the default excavation mode. The method further comprises comparing a displacement change of the implement to a first expected threshold, wherein the first expected threshold is based on the instructed excavation using the default excavation mode. In an event that the displacement change of the implement is at or above the first expected threshold, the method comprises continuing to excavate using the default excavation mode until a payload quantity of the implement reaches a target payload quantity. In an event that the displacement change of the implement is below an expected threshold, the method comprises selecting a secondary excavation mode and instructing excavation using the secondary excavation mode.

[0058] The method may comprise the steps illustrated in Figures 1 to 4. Any of the foregoing description relating to the device may apply to the method.

Claims

Claims1. A device for excavating material using an implement of a work machine, wherein the device is configured to: a. select a default excavation mode and instruct excavation using the default excavation mode; b. compare a displacement change of the implement to a first expected threshold, wherein the first expected threshold is based on the instructed excavation using the default excavation mode; c. in an event that the displacement change of the implement is at or above the first expected threshold, continue to instruct excavation using the default excavation mode until a payload quantity of the implement reaches a target payload quantity; and d. in an event that the displacement change of the implement is below the first expected threshold, select a secondary excavation mode and instruct excavation using the secondary excavation mode.

2. The device of claim 1, wherein at step c) the device is configured to compare a payload quantity of the implement to the target payload quantity when the implement reaches a stop pose, and wherein: in an event that at the stop pose the payload quantity is below the target payload quantity, return the implement to a start pose and continue to excavate until the implement reaches the stop pose; and in an event that at the stop pose the payload quantity is above the target payload quantity, move the implement to a dump region and deposit the payload.

3. The device of claim 1, wherein at step c) the device is configured to compare a payload quantity of the implement to the target payload quantity when the implement reaches a stop pose, and wherein:in an event that at the stop pose the payload quantity is above a threshold quantity lower than the target payload quantity, continue excavating using the default excavation mode until the payload quantity reaches the target payload quantity; and in an event that at the stop pose the payload quantity is below the threshold quantity, select the secondary excavation mode and instruct excavation using the secondary excavation mode; and in an event that at the stop pose the payload quantity is above the target payload quantity, move the implement to a dump region and deposit the payload.

4. The device of any preceding claim, wherein at step d) the device is further configured to: compare the displacement change of the implement to a second expected threshold based on the instructed excavation using the secondary excavation mode; and in an event that the displacement change of the implement is below the second expected threshold, select a tertiary excavation mode and instruct excavation using the tertiary excavation mode.

5. The device of claim 4, wherein in an event that the displacement change of the implement is above the second expected threshold the device is further configured to compare a payload quantity of the implement to the target payload quantity when the implement reaches a stop pose and wherein: in an event that at the stop pose the payload quantity is above a threshold quantity that is below the target payload quantity, continue excavating using the secondary excavation mode until the payload quantity reaches the target payload quantity; in an event that the payload quantity is below a threshold quantity, select the tertiary excavation mode and instruct excavation using the tertiary excavation mode; andin an event that at the stop pose the payload quantity is above the target payload quantity, move the implement to a dump region and deposit the payload.

6. The device of any preceding claim, wherein comparing the displacement change of the implement to a first expected threshold is based on one or more of: data obtained from a kinematic sensor; digging force data obtained from one or more sensors of the work machine; data obtained from one or more displacement sensor on a hydraulic cylinder of the work machine; data obtained from one or more hydraulic flow sensors and one or more hydraulic cylinder pressure sensors of the work machine; and a tilt of the work machine.

7. The device of any preceding claim, wherein the implement comprises: a boom; a stick wherein a first distal end of the stick is connected to a distal end of the boom; and a bucket connected to a second distal end of the stick; wherein the default excavation mode comprises rotation of the stick relative to the boom about the first distal end of the stick.

8. The device of any preceding claim, wherein the implement comprises: a boom; a stick wherein a first distal end of the stick is connected to a distal end of the boom; and a bucket connected to a second distal end of the stick;wherein the secondary excavation mode comprises rotation of the bucket relative to the stick about the second distal end of the stick.

9. The device of any preceding claim, wherein the implement comprises: a boom; a stick wherein a first distal end of the stick is connected to a distal end of the boom; and a bucket connected to a second distal end of the stick; wherein the tertiary excavation mode comprises linear movement of a bucket frame of reference relative to either a plane of the ground or an inertial frame of reference or a machine frame of reference.

10. The device of any preceding claim wherein a payload quantity of the implement is determined based on one or more of: a payload quantity of the implement estimated while the implement is lifted away from the ground; data indicative of a depth of the implement and / or a motion of the implement; a number of digs since depositing payload material from the implement; and a time period of excavation since instructing excavation using the default excavation mode.

11. A method of excavating material using an implement of a work machine for remote operation of a work machine, the method comprising: a. selecting a default excavation mode and instructing excavation using the default excavation mode; b. comparing a displacement change of the implement to a first expected threshold, wherein the first expected threshold is based on the instructed excavation using the default excavation mode;c. in an event that the displacement change of the implement is at or above the first expected threshold, continuing to excavate using the default excavation mode until a payload quantity of the implement reaches a target payload quantity; and d. in an event that the displacement change of the implement is below an expected threshold, selecting a secondary excavation mode and instructing excavation using the secondary excavation mode.

12. The method of claim 11, wherein at step c) the method further comprises comparing a payload quantity of the implement to the target payload quantity when the implement reaches a stop pose, and wherein: in an event that at the stop pose the payload quantity is below the target payload quantity, the method further comprises returning the implement to a start pose and continuing to excavate until the implement reaches the stop pose; and in an event that at the stop pose the payload quantity is above the target payload quantity, the method further comprises moving the implement to a dump region and depositing the payload.

13. The method of claim 11, wherein at step c) the method further comprises comparing a payload quantity of the implement to the target payload quantity when the implement reaches a stop pose, and wherein: in an event that at the stop pose the payload quantity is above a threshold quantity lower than the target payload quantity, the method comprises continuing to excavate using the secondary excavation mode until the payload quantity reaches the target payload quantity; and in an event that at the stop pose the payload quantity is below the threshold quantity, the method comprises selecting the tertiary excavation mode and instruct excavation using the tertiary excavation mode; andin an event that at the stop pose the payload quantity is above the target payload quantity, the method comprises moving the implement to a dump region and depositing the payload.

14. The method of any of claims 11 to 13, wherein at step d) the method further comprises: comparing the displacement change of the implement to a second expected threshold based on the instructed excavation using the secondary excavation mode; and in an event that the displacement change of the implement is below the second expected threshold, selecting a tertiary excavation mode and instructing excavation using the tertiary excavation mode.

15. The method of claim 14, wherein in an event that the displacement change of the implement is above the second expected threshold the method further comprises comparing a payload quantity of the implement to the target payload quantity when the implement reaches a stop pose and wherein: in an event that at the stop pose the payload quantity is above a threshold quantity that is below the target payload quantity, the method further comprises continuing excavating using the secondary excavation mode until the payload quantity reaches the target payload quantity; in an event that the payload quantity is below a threshold quantity, the method further comprises selecting the tertiary excavation mode and instructing excavation using the tertiary excavation mode; and in an event that at the stop pose the payload quantity is above the target payload quantity, the method further comprises moving the implement to a dump region and depositing the payload.

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