System for mitigating unintentional movement of working machine

Abstract

An apparatus may include sensor circuitry for detecting mechanical movement of a work machine along a surface. The apparatus may also include processing circuitry to receive the mechanical movement information or force-related information and determine a probability that unwanted movement will occur. The processing circuitry may also provide a mitigation control signal to mitigate the unwanted movement in response to determining that the probability that the unwanted movement will occur is above a threshold.

Description

Technical Field

[0001] The present disclosure relates to construction equipment, and more particularly to a system and method for mitigating unintentional movement of construction equipment. Background Art

[0002] Work machines may experience unintentional movement during work operations. For example, in the case of an excavator, the work machine may be unintentionally dragged forward during digging operations due to the reaction force of digging, sliding on muddy surfaces, or other reasons. Unintentional movement may cause miscuts, mistilts, and reduced efficiency, especially when the operator cannot make adjustments in or near the work machine. Therefore, a system is generally needed to reduce the instances or amount of unintentional movement and compensate for unintentional movement when such movement occurs.

[0003] US Patent 7,756,622 discusses attenuating the movement of a construction vehicle using methods that can be adapted to changing conditions of the construction machine. Summary of the invention

[0004] In an example according to the present disclosure, a device includes a sensor circuit for detecting mechanical movement or the possibility of mechanical movement of a working machine along a surface; and a processing circuit coupled to the sensor circuit to receive mechanical movement information and configured to: determine a probability that undesirable movement will occur; and in response to determining that the probability that undesirable movement will occur is above a threshold, provide a mitigation control signal to mitigate the undesirable movement. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] In the drawings that are not necessarily drawn to scale, like reference numerals may describe similar components in different views. Like reference numerals with different letter suffixes may represent different instances of similar components. The drawings generally illustrate various embodiments discussed in this document by way of example and not limitation.

[0006] Figure 1 A side view of an excavator according to the present disclosure is shown.

[0007] Figure 2 Movements for compensating for undesired track movement in accordance with the present disclosure are illustrated.

[0008] Figure 3 A flow chart of a method for unintentional movement mitigation and compensation according to the present disclosure is shown. DETAILED DESCRIPTION

[0009] Figure 1A side view of an excavator 100 according to the present disclosure is shown. Although the example embodiment is described with reference to the excavator 100, examples according to the present disclosure may be applied to various types of work machines in which a bucket or boom attached to the work machine may be caused to move unexpectedly by digging or swinging, or in which tracks or wheels may inadvertently slide on a surface during work.

[0010] Reference Figure 1 , the excavator 100 may include an upper structure 102, a lower structure 104, and a working element 106. The upper structure 102 may include a body 108 and an operator cab 110. The operator cab 110 is mounted on the body 108. The operator cab 110 may include a device for receiving input from a machine operator, which input may indicate a desired operation of the excavator 100. Specifically, the operator cab 110 may include one or more operator interface devices. Examples of operator interface devices include, but are not limited to, joysticks, travel control levers, and / or pedals (all not shown, but well known in the industry).

[0011] The substructure 104 may include a pair of tracks 112 (eg, transport equipment) to drive the excavator 100 on a path. The pair of tracks 112 may be driven by a hydrostatic transmission or by an electric travel motor, which in turn is powered by a prime mover such as an internal combustion engine (not shown).

[0012] The working element 106 includes a boom 114, an arm (e.g., a "stick") 116, and a working tool 118. The working tool 118 may include, for example, a bucket. The boom 114 may be mounted on the body 108 at a pivot point 120. The boom 114 is vertically pivoted by means of a boom cylinder 122. A first end 124 of the boom cylinder 122 may be coupled to the body 108. A second end 126 of the boom cylinder 122 may be coupled to the boom 114. The boom 114 may be coupled to the stick 116.

[0013] The stick 116 is moved relative to the boom 114 by extending or retracting an arm cylinder 128. A first end 130 of the arm cylinder 128 is coupled to the boom 114. A second end 132 of the arm cylinder 128 is coupled to the stick 116. The stick 116 may also be coupled to the work tool 118.

[0014] The work tool 118 is moved relative to the stick 116 by extending or retracting the work tool hydraulic cylinder 134. The work tool hydraulic cylinder 134 moves the work tool 118 through the bucket linkage assembly 136. A first end 138 of the work tool hydraulic cylinder 134 can be coupled to the stick 116. A second end 140 of the work tool hydraulic cylinder 134 is coupled to the bucket linkage assembly 136. In an embodiment, the bucket linkage assembly 136 may be referred to as a work tool linkage assembly and may be used to couple any type of work tool.

[0015] Many different work tools 118 can be attached to the excavator 100 and can be controlled by the machine operator. The work tool 118 can include any equipment used to perform a specific task, such as a blade, a fork, a bucket (in the Figure 1 ), shovels, cutting equipment, grabbing equipment and / or any other task performing equipment known in the art.

[0016] A controller 150 may be provided for electrically controlling various aspects of the work machine 100, including controlling movement to prevent or regulate unintended movement of the work machine 100. For example, the controller 150 may send and receive signals from various components of the work machine 100 during operation of the work machine 100. The controller 150 may include onboard memory or may access memory in a remote location. For example, the work machine 100 and its controller 150 may wirelessly connect to a remote device 154 using a connection 152, which may include a memory 156.

[0017] The work machine 100 may include sensor circuitry for detecting translational or rotational movement of the work machine along a surface, or horizontal mechanical movement, or rolling, pitching, or yaw movement. For example, the work machine 100 may include a position sensor 158 connected at one or more locations. The position sensor 158 is capable of determining the location of the work machine 100 and may include and / or contain components of a global positioning system (GPS). For example, the position sensor 158 may include a GPS receiver or other such device, and the position sensor 158 may communicate with one or more GPS satellites to determine the location of the work machine 100 continuously, substantially continuously, or at various time intervals. In some embodiments, a processing circuit (e.g., a controller 150) may be coupled to the sensor circuitry to receive mechanical movement information for control using software, but embodiments are not limited thereto. The sensor circuitry may also include a camera (including a camera with visual odometer tracking), a range sensor, or other sensor.

[0018] Horizontal movement can include forward and backward movement and side to side movement. Additionally, other movements such as roll, pitch, or yaw can be detected. For example, unexpected roll may have a negative impact on excavation. Therefore, if a roll above a threshold is detected, track movement compensation can be performed by, for example, performing alternating reverse rotations of the tracks to stabilize the ground. Pitch changes above a threshold may reduce optimal digging forces during excavation and can be handled similarly to roll. Yaw movement can typically be compensated or handled by offsets in the excavation trajectory planner and typically does not trigger other compensations or mitigations as described herein. Therefore, the processing circuit 150 can detect that the working machine has moved from the working position beyond the linear or angular displacement allowed by the threshold boundary.

[0019] During operation (e.g., excavation), the work machine 100 may move unintentionally. Such movement is more likely to occur during autonomous operation when the operator is not present to prevent extraneous movement, but unintentional or unwanted movement may occur even when the operator is present. For example, during autonomous excavation, the work machine 100 may be dragged toward the work tool 118 (e.g., a bucket) with or without the movement of the tracks 112. This dragging or other unintentional movement may be caused by strong reaction forces from excavation, or by the presence of slippery or sloping ground around the work machine 100. Unintentional movement may cause miscutting / mistilting and inefficiency due to excavation at non-ideal angles. In addition, unexpected movement of the work machine 100 may result in uninterrupted empty excavation, in which the work machine 100 cannot reach the termination condition based on the bucket position. For example, the bucket or other work tool 118 may not be able to move to the termination position due to unwanted movement. For example, the end position can be defined as the bucket posture reaching a sufficient depth in the vertical direction, a sufficient range in the horizontal direction (in front of the cab), or a sufficient angle of cab yaw to fully excavate the desired volume of material to complete a trench, foundation, etc.

[0020] To address these and other issues, systems, apparatus, and methods according to some embodiments may provide controlled movement to prevent or regulate unintended movement of work machine 100 .

[0021] Figure 2Movements for mitigating and compensating for undesirable movement of the track 112 (and movement of the entire work machine 100) in accordance with the present disclosure are illustrated. Compensation operations may be performed at times determined by the operator or machine customer, such as during a swing-back period after dumping and before returning to a position for the next digging cycle. Undesirable movement is detected based on reaction forces from the bucket 118, distance traveled by the track 112, distance traveled by the work machine 100, speed of movement of the track 112, speed of movement of the work machine 100, and other parameters. Distance traveled and speed may be provided by, for example, an inertial measurement unit (IMU), GPS 158, or another sensor or device.

[0022] Mitigation may include raising the boom 114 (e.g., operation 200). To mitigate movement during digging, the bucket 118 may be dumped (e.g., dumped outwardly in operation 210), which reduces horizontal dirt interaction, thereby reducing reaction forces. The reaction forces may be defined as follows: When the work machine 100 is digging, the stick 116 is rotated toward the machine and the bucket is curled in operation 202, generating a reaction force from the dirt / material in the opposite direction (i.e., horizontally outwardly from the work machine 100 and downwardly against the curling direction of the bucket 118). Other mitigation movements may include stick outward operation 208.

[0023] If the work machine 100 exhibits undesirable movement in excess of a threshold amount (either as a mitigation movement or before any mitigation movement is attempted), a compensating movement may be performed. For example, a compensating movement may be performed when undesirable movement, as indicated by an IMU, GPS, etc., has moved the work machine 100 outside of the area where the work is to be performed or away from the original position of the work machine 100 prior to the undesirable movement. In addition to the mitigation movements described above, the compensating movement may include moving the tracks forward or moving the tracks backward in operations 250, 252, respectively. The tracks 112 may also be moved to move the entire work machine 100; for example, if the work machine 100 is inadvertently moved forward due to a slope, slippery surface, or movement of the bucket 118, the work machine 100 may be moved backward. Other movements may include boom down operation 204 and stick in operation 206.

[0024] Processing circuitry (eg, controller 150, remote device 154 ( Figure 1)) can compensate for a misaligned posture of the work machine 100 to bring the work machine 100 back into alignment with a desired posture (where "posture" can be understood as the translation and orientation of the machine in natural space). In some instances, the movement compensation action occurs during the swing-back phase after dumping but before the next excavation. However, these actions can be controlled to occur at different points in other phases of the operation of the work machine 100. Other phases may include, for example, after dumping, when the bucket 118 remains stationary; after excavation, when the bucket 118 is lifted out of the pit but remains stationary. However, when the bucket 118 is in the pit, it will generally not move in most cases due to the uncontrollable forces that may be generated on the connecting rod. Compensation actions and mitigation actions may include other movements, or combinations of the above movements.

[0025] Figure 3 A flow chart of a method 300 for unintentional movement mitigation and compensation according to the present disclosure is shown. The method 300 may be performed by, for example, a processing circuit of the controller 150 or the remote device 154, but embodiments are not limited thereto.

[0026] The method 300 begins at operation 302, where operation of the work machine 100 begins, for example, an excavator and other work machines 100 that can perform excavation (e.g., a backhoe, a mini excavator, a mining shovel, an electric rope shovel, a wheel loader, etc.) begin digging. Generally, when the digging cycle begins (e.g., when the bucket 118 begins digging), at operation 304, the processing circuitry may perform mitigation to detect or determine the probability that an undesirable movement of the work machine 100 may occur at operation 304. Such detection may be based on the reaction force from the bucket 118, the distance moved by the track 112 or the work machine 100, the speed of movement of the track 112 or the work machine 100 (based on IMU and / or GPS). Other indicators may be applied to other types of work machines 100. For example, a hydraulic signal of the boom 114 may be monitored, a stick 116 or bucket 118 hydraulic cylinder (typically the head end) may be monitored, and upon indicating a threshold force, a mitigation action may be taken.

[0027] At operation 306, if an undesirable movement or possibility is detected, the processing circuitry may perform mitigation operations similar to those described above. For example, the processing circuitry may control the boom 114 to lift, or control the bucket 118 to dump downward, and / or move the stick 116 outward, continuously, simultaneously, or in any combination thereof. Mitigation operations may be provided to reduce horizontal dirt interactions and downward pitch cab movement, thereby reducing reaction forces.

[0028] Even after the processing circuit provides the mitigation control signal, and even after the work machine 100 performs the mitigation operation, the work machine 100 may still move several inches or even several feet. As described above, this can adversely affect the excavation operation, particularly when an operator is not present to prevent such movement. Therefore, the processing circuit can determine whether the undesired movement is large enough to cause the work machine 100 to move outside a threshold range of the original or desired excavation position. The threshold range can be defined, for example, as a circular or elliptical threshold relative to the machine's center of rotation attitude, or as a square or rectangular threshold (in the fore-and-aft direction and in the left-right direction). Other thresholds may be considered, including thresholds with reference to the machine's pitch and roll angles. If the undesired movement is large enough, then at operation 308, the processing circuit can select a time point at which to perform compensation or begin to perform compensation, and further select a compensatory action.

[0029] Although configurable for different digging phases, the compensation action may be particularly beneficial during the excavator "swing back" phase (after dumping but before the next digging cycle) because performing compensation while "swinging back" can minimize the impact of compensation on active digging or dumping. In any case, once the optimal compensation time has been determined, at operation 310, once the navigation planner has been executed to determine the best navigation path to use, the processing circuitry may apply track commands to the left / right tracks to move toward the original ideal position (e.g., the position of the work machine 100 before the undesired movement occurred). At operation 312, digging may occur or resume.

[0030] In an example, the compensating movement should be as smooth as possible, so the movement command should have the minimum effect necessary to move the work machine 100 back to the original position. In some examples, the amount of time to swing back can be predicted, and the movement is controlled at a certain speed to move the work machine 100 back within the swing back time. For example, if the swing back time is about 3 seconds and the maximum machine track speed is 2m / second, and the undesired movement distance is 3 meters, the processing circuit can apply half of the maximum possible track speed to correct (or compensate) the undesired movement. Therefore, the compensating movement is kept at a minimum speed to provide smooth work machine operation.

[0031] On the other hand, if the undesired travel distance is 7 meters, the processing circuitry may apply the maximum possible track speed to compensate. In this example, the remaining 1 meter may be covered by an additional bucket pause prior to digging to allow time for additional chassis compensation, or additional compensation may be provided in the next subsequent digging cycle. If compensation is still required in the subsequent digging cycle, the processing circuitry may perform mitigation similar to operation 306, or perform compensation similar to operation 310, or a combination of mitigation and compensation.

[0032] By performing mitigation and compensation as described herein, processing circuitry according to example aspects can avoid the deleterious effects of unwanted movement on the digging and dumping performance of a work machine. The operator can also avoid uninterrupted empty bucket digging that may be caused by digging position errors.

[0033] Industrial Applicability

[0034] Typically, the work machine 100 can be configured and equipped to detect actual or imminent undesirable movement that places the work machine 100 away from the original position and away from the position where the work machine 100 is to perform an excavation operation. The work machine 100 can include sensors to detect horizontal mechanical movement and provide a mitigation control signal if there is a high probability that undesirable mechanical movement will occur. The probability can be determined based on the terrain around the work machine 100, the speed of the work machine 100, the reaction force of the work machine 100 as sensed by other sensors, and other factors. If the mitigation measures are not sufficient to prevent the undesirable movement, compensatory movement can be controlled to move the work machine 100 back to the original or ideal position where the work machine 100 performs excavation or other operations. The compensatory movement can be performed at such a time and such a speed that jerky movement can be avoided and the excavation operation is not affected.

[0035] The above detailed description is intended to be illustrative rather than limiting. The scope of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A device (100), comprising: Sensor circuitry (158) for detecting mechanical movement or the possibility of mechanical movement of a working machine along a surface; as well as a processing circuit (150) coupled to the sensor circuit to receive the mechanical movement information and configured to: Determining the probability that the undesired movement will occur; and In response to determining that the probability that the undesired movement will occur is above a threshold, a mitigation control signal is provided to mitigate the undesired movement.

2. The apparatus of claim 1, wherein the probability is based on a reaction force from an operation of the work machine. The apparatus of claim 2 , wherein the reaction force is estimated based on hydraulic pressure.

4. The apparatus of claim 1, wherein the mitigation control signal comprises a control signal to dump the bucket outwardly away from the surface. 5 . The apparatus according to claim 1 , wherein the mitigation control signal comprises a control signal for raising a boom of the work machine or moving an arm of the work machine outward.

6. The apparatus of claim 1, wherein the mechanical movement comprises at least one of horizontal movement, rolling movement, pitch movement, and yaw movement.

7. The apparatus of claim 1 , wherein the processing circuit is further configured to: detecting that the work machine has moved from a work position beyond a threshold boundary allowed linear or angular displacement; and A compensating control signal is provided in response to the detection to control movement of the work machine to the work position.

8. The apparatus of claim 1, wherein the processing circuit is further configured to determine an undesired movement distance and an amount of time for the work machine to return to a starting position, and to control a compensating movement of the work machine at a minimum speed to move the undesired movement distance.

9. The apparatus of claim 8, wherein the work machine comprises an excavator, and wherein the amount of time for the work machine to return to the starting position comprises a swing back time of the excavator.

10. The apparatus of claim 8, wherein the compensating movement comprises a track movement command.

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