Method and system for steering earthmoving machines

Abstract

The method, for steering an earthmoving machine, includes detecting, by a controller, a deviation of the earthmoving machine from a desired line of travel when a blade steering mode is active, in whic

Description

Technical Field

[0001] The present disclosure relates to steering of earthmoving machines, having continuous tracks. More particularly, the present disclosure relates to adjusting an implement (e.g., a blade) of an earthmoving machine to steer the earthmoving machine along a desired line of travel. Background

[0002] Earthmoving machines, such as track-type tractors, are equipped with ground-engaging implements (e.g., blades) used to engage a work surface to move materials and / or alter the work surface at a worksite. To efficiently move materials over a distance at the worksite, an earthmoving machine may travel on a defined path. Steering assist modes, such as track steering mode (i.e., varying relative speeds of oppositely positioned continuous tracks of the earthmoving machine) and blade steering mode (i.e., tilting the blade about a longitudinal axis of the track-type machine), may be used to steer the earthmoving machine on the defined path. However, heavy loads / forces exerted on the ground-engaging implement (e.g., caused by the material being moved, such as rocks, wood logs, etc.,) may tend to deviate the earthmoving machine in directions away from the defined path. Summary of the Invention

[0003] In one aspect, the disclosure relates to a method for steering an earthmoving machine. The method includes detecting, by a controller, a deviation of the earthmoving machine from a desired line of travel when a blade steering mode is active. In the blade steering mode, at least one corner of a ground-engaging implement of the earthmoving machine is lowered with respect to another corner to engage an underlying work surface and create a positive yaw rate to assist with steering the earthmoving machine along the desired line of travel. Also, the method includes determining, by the controller, that a first load acting on the ground-engaging implement in the blade steering mode exceeds a first threshold that is associated with the deviation. In addition, the method includes raising, by the controller based on the first load exceeding the first threshold, the ground-engaging implement with respect to a frame of the earthmoving machine to reduce a current load acting on the ground-engaging implement below the first threshold.

[0004] In another aspect, the disclosure is directed to a steering system for an earthmoving machine. The steering system includes a ground-engaging implement. The ground-engaging implement defines a plurality of comers. In addition, the steering system includes a controller. The controller is configured to detect a deviation of the earthmoving machine from a desired line of travel when a blade steering mode is active. In the blade steering mode, at least one corner of the ground-engaging implement is lowered with respect to another corner to engage an underlying work surface and create a positive yaw rate to assist with steering the earthmoving machine along the desired line of travel. Further, the controller is configured to determine that a first load acting on the ground-engaging implement in the blade steering mode exceeds a first threshold that is associated with the deviation. Moreover, the controller is configured to raise, based on the first load exceeding the first threshold, the ground-engaging implement with respect to a frame of the earthmoving machine to reduce a current load acting on the ground-engaging implement below the first threshold.

[0005] In yet another aspect, the disclosure relates to an earthmoving machine. The earthmoving machine includes a frame, a first track, a second track, and a steering system. The frame defines a first side and a second side of the earthmoving machine. The second side is opposite to the first side. The first track is disposed on the first side and the second track is disposed on the second side. The steering system includes a ground-engaging implement. The groundengaging implement defines a plurality of comers. In addition, the steering system includes a controller. The controller is configured to detect a deviation of the earthmoving machine from a desired line of travel when a blade steering mode is active. In the blade steering mode, at least one comer of the ground engaging implement is lowered with respect to another comer to engage an underlying work surface and create a positive yaw rate to assist with steering the earthmoving machine along the desired line of travel. Further, the controller is configured to determine that a first load acting on the ground-engaging implement in the blade steering mode exceeds a first threshold that is associated with the deviation. Moreover, the controller is configured to raise, based on the first load exceeding the first threshold, the ground-engaging implement with respect to the frame to reduce a current load acting on the ground-engaging implement below the first threshold. Brief Description of the Drawings

[0006] FIG. 1 illustrates an exemplary earthmoving machine including a ground-engaging implement, in accordance with an embodiment of the present disclosure;

[0007] FIG. 2 illustrates a system for steering the earthmoving machine along a desired line of travel on a worksite, in accordance with an embodiment of the present disclosure;

[0008] FIG. 3 illustrates raising the ground-engaging implement to steer the earthmoving machine on the desired line of travel, when a blade steering mode is active, in accordance with an embodiment of the present disclosure;

[0009] FIG. 4 illustrates a bird’s-eye view of the earthmoving machine of FIG. 3, in accordance with an embodiment of the present disclosure; and

[0010] FIG. 5 illustrates a flowchart illustrating a method for steering the earthmoving machine, in accordance with an embodiment of the present disclosure. Detailed Description

[0011] Reference will now be made in detail to specific embodiments or features, examples of which are illustrated in the accompanying drawings. Generally, corresponding reference numbers may be used throughout the drawings to refer to the same or corresponding parts, e.g., 1, 1', 1", 101 and 201 could refer to one or more comparable components used in the same and / or different depicted embodiments.

[0012] Referring to FIG. 1, an exemplary earthmoving machine 100 (hereinafter referred to as ‘machine 100’) is shown. The machine 100 may perform a variety of tasks associated with an industry such as construction, mining, farming, transportation, or any other industry known in the art. As an example, the machine 100 is embodied as a track-type tractor 100' capable of performing the tasks associated with altering the current geography at a worksite 104, such as, a grading, a scraping, a leveling, a bulk material removal, or any other type of geography altering tasks at a worksite 104 (e.g., a mining site).

[0013] The machine 100 includes a frame 108, a first track 112, a second track 116 (shown in FIG. 4), and a ground-engaging implement 120. The frame 108 defines a forward end 124 and a rearward end 128 of the machine 100. The rearward end 128 is opposite to the forward end 124. The forward end 124 and the rearward end 128 may be defined in relation to an exemplary direction of travel of the machine 100 (indicated by an arrow ‘A’), with said direction of travel being defined from the rearward end 128 towards the forward end 124. Also, the frame 108 defines two lateral sides of the machine 100, namely - a first side 132 (or right side 132) and a second side 136 (or left side 136, shown in FIG. 4) opposite to the first side 132.

[0014] The first track 112 is disposed on the first side 132 and, the second track is disposed on the second side 136 of the machine 100. The first track 112 and the second track 116 may support the frame 108 (or the machine 100) on a work surface 140 at the worksite 104. The first track 112 and the second track 116 may be powered by a power source, for example, an internal combustion engine along with a transmission (depicted by a dashed line 144) of the machine 100, to propel the machine 100, for example, forward or backward, over the work surface 140. In addition, the first track 112 and the second track 116 may be utilized to steer the machine 100, for example, to the left or to the right, over the work surface 140 at the worksite 104.

[0015] The ground-engaging implement 120 includes a dozer blade 148 configured to engage with the underlying work surface 140, for example, for cutting into the work surface 140 and hence to level the work surface 140. The ground-engaging implement 120 (or the dozer blade 148) defines multiple comers. For instance, the ground-engaging implement 120 defines two corners, namely - a first comer 152 and a second corner 156 (shown in FIG. 3) at a cutting edge 160 of the ground-engaging implement 120. The ground-engaging implement 120 may be mounted at or towards the forward end 124 of the frame 108, for example, via a linkage assembly 164. The linkage assembly 164 may facilitate movement of the ground-engaging implement 120 relative to the frame 108 of the machine 100.

[0016] In an exemplary embodiment, as shown in FIG. 1, the linkage assembly 164 includes multiple actuators, such as one or more first actuators 168, one or more second actuators 172, and one or more third actuators 176. The first actuator(s) 168 may be configured to raise or lower the ground-engaging implement 120 with respect to the frame 108. The second actuator(s) 172 may be configured to tilt the ground-engaging implement 120 with respect to the frame 108. The third actuator(s) 176 may be configured to yaw the ground-engaging implement 120 with respect to the frame 108. It should be noted that the term “tilt” used herein refers to a rotation of the ground-engaging implement 120 (about a longitudinal axis ‘L’ of the machine 100, shown in FIG. 4) in which at least one corner (e.g., the first comer 152) of the ground-engaging implement 120 is at a lower position with respect to another comer (e.g., the second comer 156) and, the term “yaw” used herein refers to a rotation of the ground-engaging implement 120 about a vertical axis ‘V’ of the machine 100 in which at least one comer of the ground-engaging implement 120 is relatively closer to the forward end 124 of the machine 100 than the other comer.

[0017] To move materials at the worksite 104, for example, from an initial location to a spread or dump location of the worksite 104, the machine 100 is required to follow a desired line of travel between the initial location and the spread or dump location. To steer the machine 100 along the desired line of travel, an operator (physically located within a cabin 180 of the machine 100 or at a remote location) may operate the machine 100 with the use of one or more input devices 184 (e.g., via a joystick 188 located within the cabin 180). For example, the operator may move the joystick 188 forward to cause the machine 100 to move forward or, may move the joystick 188 rearward to cause the machine 100 to move backward or, may turn the joystick 188 left or right to cause the machine 100 to tum left or right, respectively. As the machine 100 is operated and the ground-engaging implement 120 (e.g., the dozer blade 148) comes under heavy loads (e.g., materials, rocks, wood logs, etc.,), forces (due to the heavy loads) on the ground-engaging implement 120 may cause the machine 100 to deviate from its desired line of travel.

[0018] To assist the operator in steering the machine 100 along the desired line of travel, in one or more aspects of the present disclosure, a steering system 200 is disclosed. As shown in FIG. 2, the steering system 200 includes the groundengaging implement 204 and a controller 208. In addition, the steering system 200 may include one or more sensing devices 212 associated with the machine 100. The ground-engaging implement 204 is the same as the ground-engaging implement 120, and hence, may be used interchangeably.

[0019] The sensing devices 212 may include a load sensing device 216. The load sensing device 216 may be configured to sense one or more parameters indicative of a load acting on the ground-engaging implement 120. It should be noted that the term “load” as used herein denotes a reactive load imposed against the machine 100, its ground-engaging implement 120, or its driveline components, for example, due to positioning of the ground-engaging implement 120. Thus, for example, the load acting on the ground-engaging implement 120 may be measured as a drawbar pull of the machine 100. The term “drawbar pull” as used herein refers to the force delivered to the first track 112 and the second track 116 of the machine 100. This force may be expended primarily by moving the machine 100, e.g., pushing a load, and by moving material under the tracks (e.g., the first track 112 and the second track 116) in the form of track slip. In the present embodiment, the load sensing device 216 includes a transmission output torque sensor 216' configured to directly sense a torque output and / or output speed of the power source 144 of the machine 100. The measured torque output and / or output speed may be utilized to determine the drawbar pull of the machine 100 (or the load acting on the ground-engaging implement 120).

[0020] It is contemplated that, in other embodiments, alternative techniques for determining the load acting on the ground-engaging implement 120 may be implemented, such as measuring, via pressure sensors, an amount of pressure associated with at least one of the first actuators 168, the second actuators 172, and the third actuators 176 to determine the load, or measuring, via strain gauges, an amount of strain on the linkage assembly 164 coupling the ground-engaging implement 120 with the frame 108, and the like.

[0021] The controller 208 may be communicably coupled to the input device 184 (e.g., the joystick 188). Also, the controller 208 may be communicably coupled to the sensing devices 212 (e.g., the load sensing device 216). Further, the controller 208 may be communicably coupled to the power source 144 (e.g., the internal combustion engine along with the transmission). Furthermore, the controller 208 may be communicably coupled to at least one of the first actuators 168, the second actuators 172, and the third actuators 176 of the linkage assembly 164 coupling the ground-engaging implement 120 to the frame 108 of the machine 100. Moreover, the controller 208 may also be communicably coupled to a memory 220 (which may be one of integrally or externally configured with the controller 208).

[0022] As an example, by way of the controller’s 208 communicable coupling with the input device 184 (e.g., the joystick 188), the controller 208 may be configured to detect an actuation of the input device 184 and receive an input, from the input device 184, indicative of an activation of a steering assistance mode. Based on such actuation and the receipt of the input corresponding to the activation of the steering assistance mode, the controller 208 may be configured to activate a track steering mode for adjusting the steering of the machine 100.

[0023] When the track steering mode is active, the controller 208 may be configured to vary a relative speed between the first track 112 and the second track 116 to steer the machine 100 along the desired line of travel. For example, in order to steer the machine 100 towards the right (direction from the perspective of the operator in the cabin 180), the controller 208 is configured to control the power source 144 in a manner to reduce or remove power from a first track 112 (disposed on the first or right side 132 of the machine 100) and continue to supply power to the second track 116 (disposed on the second or left side 136 of the machine 100).

[0024] When the track steering mode is active, the controller 208 may be configured to determine the load acting on the ground-engaging implement 120, for example, when the ground-engaging implement 120 engages with a material 228 on the work surface 140 (as shown in FIG. 3). The load determined by the controller 208, when only the track steering mode is active, is hereinafter referred to as a “second load”, for clarity purposes. In the present embodiment, the controller 208 may receive data corresponding to the torque output of the power source 144 from the load sensing device 216 (e.g., transmission output torque sensor 216 ). The controller 208 may receive the torque output data, from the load sensing device 216, on a scheduled basis (e.g., every second, every 10 seconds, every minute, and / or the like), on an on-demand basis (e.g., upon receiving a command from controller 208 to provide the torque output data to the controller 208), on a triggered basis (e.g., upon the ground-engaging implement 120 lifting a load of material), and / or the like. The controller 208 may utilize the torque output data to determine a value of the second load acting on the groundengaging implement 120 (i.e., the drawbar pull of the machine 100), when the track steering mode is active.

[0025] In another embodiment, the controller 208 may utilize data related to an amount of pressure associated with at least one of the first actuators 168, the second actuators 172, and the third actuators 176 to determine the load acting on the ground-engaging implement 120. In yet another embodiment, the controller 208 may utilize data related to an amount of strain on the linkage assembly 164 to determine the load acting on the ground-engaging implement 120.

[0026] Further, the controller 208 may be configured to compare the value of the second load with a corresponding threshold (hereinafter referred to as a “second threshold”). The second threshold may be pre-stored in the memory 220 associated with the controller 208. In the present embodiment, the second threshold may be related to a percent of the machine’s 100 weight. For example, the second threshold may be a drawbar pull that is equivalent to 40% of the machine's 100 weight.

[0027] When the value of the second load exceeds the second threshold, the controller 208 is configured to activate a blade steering mode for adjusting the steering of the machine 100. In the blade steering mode, at least one comer of the ground-engaging implement 120 is lowered with respect to another corner to engage the underlying work surface 140 and create a positive yaw rate to assist with steering the machine 100 along the desired line of travel. It should be noted that the term “yaw rate” as used herein refers to changes in yaw of the machine 100 about the vertical axis ‘V’ over a pre-determined time period. Accordingly, if the machine 100 is maneuvered along a straight line, the yaw rate of the machine 100 is considered to be a “zero yaw rate”. Similarly, if the machine 100 is turned to the left (or to the right), the yaw rate of the machine 100 is considered to be a “positive yaw rate”.

[0028] In an example, as shown in FIGS. 3 and 4, in which the machine 100 veer to the left from its desired line of travel ‘T’ (e.g., due to the load of material 228 acting on a left portion of the ground-engaging implement 120), the controller 208 is configured to tilt the ground-engaging implement 120 in a counterclockwise direction such that the first corner 152 (located towards the right side 132) of the ground-engaging implement 120 is lowered relative to the second corner 156 (located towards the left side 136) to engage the underlying work surface 140 and create a positive yaw rate to steer the machine 100 to the right towards the desired line of travel‘T’.

[0029] To verify if the machine 100 is following its desired line of travel (e.g., line of travel T’) when the blade steering mode is active, the controller 208 is configured to detect a deviation, if any, of the machine 100 from its desired line of travel. In an example, the controller 208 may receive, for example, from one or more orientation sensors of the machine 100, a data associated with an actual orientation of the machine 100. The controller 208 may compare the actual orientation with a desired orientation (e.g., pre-stored in the memory 220) to detect if the machine 100 is deviating from its desired line of travel. In some embodiments, the controller 208 may detect deviation of the machine 100 when both the track steering mode and the blade steering mode are active. Examples of the orientation sensors may include, but not limited to, an Inertial Measurement Unit (IMU), an inclinometer, a gyroscope, a position sensor (e.g., a global navigation satellite system (GNSS), and vision devices, such as a stereo camera system, LIDAR, RADAR, and the like.

[0030] The controller 208 is also configured to determine the load acting on the ground-engaging implement 120 when the blade steering mode is active. The load determined by the controller 208, when the blade steering mode is active, is hereinafter referred to as a “first load”, for clarity purposes. The first load may be different from the second load. In the present embodiment, the controller 208 may utilize the torque output data to determine the first load acting on the ground-engaging implement 120 (i.e., the drawbar pull of the machine 100), when the blade steering mode is active.

[0031] The controller 208 is further configured to compare the first load with a corresponding first threshold to determine if the first load exceeds the first threshold. The first threshold may correspond to a load value (pre-stored in the memory 220) associated with the deviation of the machine 100 when the blade steering mode is active. The first threshold may be greater than the second threshold. In the exemplary embodiment, the first threshold may be a drawbar pull that is equivalent to 70% of the machine's 100 weight, whereas the second threshold may be a drawbar pull that is equivalent to 40% of the machines’ 100 weight. An event of the first load exceeding the first threshold may prevent the machine 100 from following its desired line of travel in the blade steering mode (optionally, along with the track steering mode).

[0032] Based on the first load exceeding the first threshold, the controller 208 is configured to raise the ground-engaging implement 120 with respect to the frame 108. Raising the ground-engaging implement 120 results in a reduction of the load (i.e., the current load) acting on the ground-engaging implement 120 below the first threshold. Once the current load acting on the ground-engaging implement 120 is reduced below the first threshold, it is possible for the machine 100 to steer in the blade steering mode (optionally, along with the track steering mode) to return towards its desired line of travel.

[0033] In some embodiments, the controller 208 is configured to raise the ground-engaging implement 120 with respect to the frame 108 upon determining that the blade steering mode is at a maximum steering value. In some other embodiments, the controller 208 is configured to raise the ground-engaging implement 120 with respect to the frame 108 upon determining that both the blade steering mode and the track steering mode are at their respective maximum steering values. The maximum steering value in the blade steering mode may correspond to a steering condition in which the second actuator 172 responsible for tilting the ground-engaging implement 120 is at any one of its extreme positions (e.g., either at a fully retracted position or at a fully extended position). The maximum steering value in the track steering mode corresponds to a steering condition in which the relative speeds between the first track 112 and the second track 116 is at its maximum value.

[0034] When the ground-engaging implement 120 is raised (when the blade steering mode is active), the ground-engaging implement 120 is disengaged from the underlying work surface 140. At this stage, the controller 208 may be configured to determine that the current load is below the first threshold. Based on the current load no longer exceeding the first threshold, the controller 208 is configured to lower the ground-engaging implement 120 with respect to the frame 108 such that the ground-engaging implement 120 re-engages with the underlying work surface 140 and perform the dozing operations.

[0035] The controller 208 may be a microprocessor-based device, and / or may be envisioned as an application-specific integrated circuit, and / or other logic devices, which provide controller functionality, and such devices being known to those with ordinary skill in the art. In one example, it is possible for the controller 208 to include or be representative of one or more controllers having separate or integrally configured processing units to process a variety of data (or input or commands). In some embodiments, a transmission of data between the controller 208 and various other devices, e.g., the input device 184, the sensing devices 212, the power source 144, the first actuators 168, the second actuators 172, the third actuators 176, etc., may be facilitated wirelessly, through a wired connection, through a Controlled Area Network (CAN) connection, and / or through transmission modes which are now known or in the future developed.

[0036] The controller 208 may include a processor 224 to process a variety of data (or inputs) such as the torque output data, the orientation data, speed data, and the like. Examples of the processor 224 may include, but are not limited to, an X86 processor, a Reduced Instruction Set Computing (RISC) processor, an Application Specific Integrated Circuit (ASIC) processor, a Complex Instruction Set Computing (CISC) processor, an Advanced RISC Machine (ARM) processor, or any other processor.

[0037] Examples of the memory 220 may include a hard disk drive (HDD), and a secure digital (SD) card. Further, the memory 220 may include non-volatile / volatile memory units such as a random-access memory (RAM) / a read only memory (ROM), which may include associated input and output buses. The memory 220 may be configured to store various other instruction sets for various other functions of the machine 100, along with the set of instruction, discussed above. Industrial Applicability

[0038] Referring to FIG. 5, an exemplary method for steering the machine 100 is discussed. The method is discussed by way of a flowchart 500 that illustrates exemplary steps (i.e., from 504 to 528) associated with the method. The method is also discussed in conjunction with FIGS. 3 and 4.

[0039] The machine 100 starts moving from an initial location (not shown) at the worksite 104 along the desired line of travel ‘T’. During the movement of the machine 100 along the desired line of travel ‘T’, the operator of the machine 100 may face difficulty in manually steering the machine 100 along the desired line of travel ‘T’. Accordingly, the operator may actuate the input device 184 (e.g., the joystick 188) to enable the steering assistance mode, at step 504. The controller 208 detects the actuation of the input device 184 and receives the input indicative of the activation of the steering assistance mode. In response to the input, the controller 208 activates the track steering mode to automatically steer the machine 100 along the desired line of travel ‘T’, at stage 508.

[0040] Along the desired line of travel‘T’, the machine 100 encounters a heavy load (e.g., the load of material 228 on a left portion of the ground-engaging implement 120), for example, when the ground-engaging implement 120 is at a first position ‘Pl’ (shown in FIG. 3). The load may cause the machine 100 to veer to the left as the ground-engaging implement 120 encounters the material 228 (as shown in FIG. 4). Due to this, the machine 100 may encounter difficulty automatically steering, in the track steering mode, to maintain its track along the desired line of travel ‘T’. That is, the machine 100 may begin to turn to the left, away from its desired line of travel T' due to the load acting on the groundengaging implement 120 even when the track steering mode is active.

[0041] In response, the controller 208 determines the load (e.g., the second load) acting on the ground-engaging implement 120, when the track steering mode is active. The controller 208 compares the second load with its corresponding second threshold (e.g., drawbar pull equivalent to 40% of the machines’ 100 weight), at step 512. In cases in which the second load is below the second threshold, the controller 208 continues to operate the machine 100 in the track steering mode only and de-activate the blade steering mode (if active), step 516. However, if the second load exceeds the second threshold, the controller 208 activates the blade steering mode (e.g., independently of or in addition to the track steering mode active), step 520.

[0042] To automatically steer the machine 100 in the blade steering mode, the controller 208 may tilt the ground-engaging implement 120 from the first position ;Pf to a second position ‘P2’. For example, as shown in FIG. 3, the controller 208 may control the second actuator 172 to tilt the ground-engaging implement 120 in a counterclockwise direction such that the first comer 152 (located towards the right side 132) of the ground-engaging implement 120 is lowered relative to the second corner 156 (located towards the left side 136) to engage the underlying work surface 140 and create a positive yaw rate to steer the machine 100 to the right towards the desired line of travel ‘T’.

[0043] When the blade steering mode is active and the ground-engaging implement 120 is at the second position ‘P2’, the controller 208 may determine if the machine 100 is tracking its desired line of travel £T’, step 524. To do so, the controller 208 detects if there is any deviation of the machine 100 from its desired line of travel ‘T’, when the blade steering mode is active. At this stage, the controller 208 further determines the load (e.g., as the first load different from the second load) acting on the ground-engaging implement 120. The controller 208 compares the first load with its corresponding first threshold (e.g., a drawbar pull equivalent to 70% of the machines’ 100 weight) associated with the deviation.

[0044] When the first load is below its corresponding first threshold, the controller 208 returns to the step 512, and repeat the process. When the first load exceeds the first threshold, the controller 208 determines that the machine 100 is not tracking its desired line of travel ‘T’. In response to first load exceeding the first threshold, the controller 208 raises the ground-engaging implement 120 from the second position ‘P2’ to a third position ;P3\ step 528. Raising the groundengaging implement 120 relative to the frame 108 to the third position ‘P3’ reduces the current load acting on the ground-engaging implement 120 below the first threshold. In an example, the ground-engaging implement 120 is raised to the third position ‘P3’ to disengage from the load (i.e., current load) acting on the ground-engaging implement 120. At this point, the controller 208 may return to the step 512.

[0045] Further, the controller 208 may determine if the current load acting on the ground-engaging implement 120 is below the first threshold. Based on the current load no longer exceeding the first threshold, the controller 208 may lower the ground-engaging implement 120 with respect to the frame 108 such that the ground-engaging implement 120 re-engages with the underlying work surface 140 to further perform the dozing operations as the machine 100 moves along its desired line of travel.

[0046] In another embodiment, when the blade steering mode is active, the controller 208 may determine if the blade steering mode is at its maximum steering value. For instance, the controller 208 may receive data associated with positioning of the second actuator 172 (responsible for tilting the groundengaging implement 120). Upon receiving the data corresponding to the extreme positioning (e.g., a fully retracted position or at a fully extended position) of the second actuator 172, the controller 208 may determine that the blade steering mode is at its maximum steering value. At this stage, if the controller 208 determines that the machine 100 is still experiencing the heavy load (i.e., the first load exceeding the first threshold) while the blade steering mode is at its maximum steering value, the controller 208 may raise the ground-engaging implement 120 to the third position ‘P3’.

[0047] In yet another embodiment, when both the track steering mode and the blade steering mode are active, the controller 208 may determine if the track steering mode and the blade steering mode are at their respective maximum steering values. For instance, in addition to determining that the blade steering mode is at its maximum value (as discussed above), the controller 208 may determine relative speeds between the first track 112 and the second track 116. Upon determining a maximum value of the relative speed between the first track 112 and the second track 116, the controller 208 determines that the track steering mode is at its maximum steering value. At this stage, if the controller 208 determines that the machine 100 is still experiencing the heavy load (i.e., the first load exceeding the first threshold) while both the blade steering mode and the track steering mode are at their respective maximum steering value, the controller 208 may raise the ground-engaging implement 120 to the third position ‘P3’.

[0048] While steps 504-528 have been described in an exemplary sequence, as understood, one or more of these steps may be performed simultaneously or performed and / or repeated in a different order. Moreover, any two or more of these steps may be performed simultaneously and / or at overlapping periods of time.

[0049] The steering system 200 may facilitate the machine 100 to travel along its desired line of travel, even when the machine 100 encounters heavy loads that tend to cause the machine 100 to deviate from its desired line of travel. The steering system 200 may reduce or eliminate steering difficulties encountered (e.g., due to heavy loads) while both the blade steering mode and the track steering mode are active but ineffective, even at their respective maximum steering values.

[0050] Unless explicitly excluded, the use of the singular to describe a component, structure, or operation does not exclude the use of plural such components, structures, or operations or their equivalents. The use of the terms “a” and “an” and “the” and “at least one” or the term “one or more,” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B” or one or more of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B; A, A and B; A, B and B), unless otherwise indicated herein or clearly contradicted by context. Similarly, as used herein, the word "or" refers to any possible permutation of a set of items. For example, the phrase "A, B, or C" refers to at least one of A, B, C, or any combination thereof, such as any of: A; B; C; A and B; A and C; B and C; A, B, and C; or multiple of any item such as A and A; B, B, and C; A, A, B, C, and C; etc.

[0051] It will be apparent to those skilled in the art that various modifications and variations can be made to the method, the steering system, and / or the earthmoving machine of the present disclosure without departing from the scope of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the method, the steering system, and / or the earthmoving machine disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalent.

Claims

What is claimed is:

1. A method for steering an earthmoving machine, the method comprising: detecting, by a controller, a deviation of the earthmoving machine from a desired line of travel when a blade steering mode is active, wherein, in the blade steering mode, at least one comer of a groundengaging implement of the earthmoving machine is lowered with respect to another corner to engage an underlying work surface and create a positive yaw rate to assist with steering the earthmoving machine along the desired line of travel;determining, by the controller, that a first load acting on the ground-engaging implement in the blade steering mode exceeds a first threshold that is associated with the deviation; andraising, by the controller based on the first load exceeding the first threshold, the ground-engaging implement with respect to a frame of the earthmoving machine to reduce a current load acting on the groundengaging implement below the first threshold.

2. The method of claim 1, wherein the earthmoving machine includes a first track disposed on a first side of the earthmoving machine and a second track disposed on a second side of the earthmoving machine opposite to the first side, the method further including:activating, by the controller, a track steering mode, wherein, in the track steering mode, a relative speed between the first track and the second track is varied to steer the earthmoving machine along the desired line of travel.

3. The method of claim 2 further including receiving, by the controller, an input to activate the track steering mode, wherein the track steering mode is activated based on the input.

4. The method of claim 2 further including:determining, by the controller, a value of a second load acting on the ground-engaging implement in the track steering mode; andactivating, by the controller, the blade steering mode when the second load exceeds a second threshold that is less than the first threshold.

5. The method of claim 1, wherein when the ground-engaging implement is raised, the ground-engaging implement is disengaged from the underlying work surface, the method further including:determining, by the controller, that the current load is below the first threshold; andlowering, based on the current load no longer exceeding the first threshold, the ground-engaging implement with respect to the frame such that the ground-engaging implement re-engages with the underlying work surface.

6. The method of claim 1, further including:determining, by the controller, that the blade steering mode is at a maximum steering value, wherein raising the ground-engaging implement is further based on the blade steering mode being at the maximum steering value.

7. The method of claim 2, further including:determining, by the controller, that the blade steering mode and the track steering mode are at respective maximum steering values, wherein raising the ground-engaging implement is further based on the bladesteering mode and the track steering mode being at the respective maximum steering values.

8. A steering system for an earthmoving machine, the steering system comprising:a ground-engaging implement defining a plurality of corners; anda controller configured to:detect a deviation of the earthmoving machine from a desired line of travel when a blade steering mode is active, wherein, in the blade steering mode, at least one corner of the ground-engaging implement is lowered with respect to another corner to engage an underlying work surface and create a positive yaw rate to assist with steering the earthmoving machine along the desired line of travel;determine that a first load acting on the ground-engaging implement in the blade steering mode exceeds a first threshold that is associated with the deviation; andraise, based on the first load exceeding the first threshold, the ground-engaging implement with respect to a frame of the earthmoving machine to reduce a current load acting on the ground-engaging implement below the first threshold.

9. The steering system of claim 8, wherein the earthmoving machine includes a first track disposed on a first side of the earthmoving machine and a second track disposed on a second side of the earthmoving machine opposite to the first side, the controller is configured to:activate a track steering mode, wherein, in the track steering mode, a relative speed between the first track and the second track is varied to steer the earthmoving machine along the desired line of travel.

10. The steering system of claim 9, wherein the controller is configured to receive an input to activate the track steering mode, wherein the track steering mode is activated based on the input.

11. The steering system of claim 9, wherein the controller is configured to: determine a value of a second load acting on the ground-engaging implement in the track steering mode; andactivate the blade steering mode when the second load exceeds a second threshold that is less than the first threshold.

12. The steering system of claim 8, wherein when the ground-engaging implement is raised, the ground-engaging implement is disengaged from the underlying work surface, the controller is configured to:determine that the current load is below the first threshold; and lower, based on the current load no longer exceeding the first threshold, the ground-engaging implement with respect to the frame such that the ground-engaging implement re-engages with the underlying work surface.

13. The steering system of claim 8, wherein the controller is configured to: determine that the blade steering mode is at a maximum steering value, wherein raising the ground-engaging implement is further based on the blade steering mode being at the maximum steering value.

14. The steering system of claim 9, wherein the controller is configured to: determine that the blade steering mode and the track steering mode are at respective maximum steering values, wherein raising the groundengaging implement is further based on the blade steering mode and the track steering mode being at the respective maximum steering values.

15. An earthmoving machine, compri sing:a frame defining a first side and a second side of the earthmoving machine, the second side being opposite to the first side;a first track disposed on the first side and a second track disposed on the second side; anda steering system for steering the earthmoving machine, the steering system comprising:a ground-engaging implement defining a plurality of comers; anda controller configured to:detect a deviation of the earthmoving machine from a desired line of travel when a blade steering mode is active, wherein, in the blade steering mode, at least one corner of the ground-engaging implement is lowered with respect to another corner to engage an underlying work surface and create a positive yaw rate to assist with steering the earthmoving machine along the desired line of travel;determine that a first load acting on the groundengaging implement in the blade steering mode exceeds a first threshold that is associated with the deviation; andraise, based on the first load exceeding the first threshold, the ground-engaging implement with respect to the frame to reduce a current load acting on the groundengaging implement below the first threshold.

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