Control system for cornering operations of a motor grader

Abstract

Motor grader (10) which has the following features: a hinged frame (12, 14) having one or more steerable traction devices (58, 60) at one end of the hinged frame (12, 14) and one or more drive traction devices (22) at an opposite end of the hinged frame (12, 14); a shield (30) which is positioned under the hinged frame (12, 14) to level or work a ground surface under the motor grader (10); a steering actuation device (64, 66) arranged and configured to establish an articulated steering angle of the articulated frame (12, 14), further a steering actuation device (88), which is arranged and configured to establish a steering angle of one or more steerable traction devices (58, 60), and a lateral displacement actuation device (40) arranged and configured to displace the shield (30) relative to the hinged frame (12, 14); at least one object sensor (118) arranged and configured to detect a road marking adjacent to the motor grader (10) and to provide information indicating a distance between the sign (30) and the road marking; and a control device (94) configured to receive a mode selection signal from a mode selection switch (134) which identifies a desired operating mode from a variety of available modes, including a manual mode, an automatic shield control mode in which the control device (94) controls the shield's side-shift actuation device (40) to maintain a target distance between the shield (30) and the road marking, an automatic shield and articulated steering control mode in which the control device (94) controls the shield's side-shift actuation device (40) and the articulated steering actuation device (64, 66) to maintain the target distance between the shield (30) and the road marking when the motor grader is steered by an operator, and a fully automatic control mode.in which the control device (94) controls the side-shift actuation device (40) of the sign (30), the articulated steering actuation device (64, 66) and the steering actuation device (88) to guide the motor grader (10) while maintaining the target distance between the sign (30) and the road marking.

Description

Technical field of the disclosure

[0001] The present disclosure relates to the operation of a motor grader and, more particularly, to a blade and steering control of a motor grader for operations near road markings, such as curbs. Background of the Revelation

[0002] Motor graders, or road graders, are earthmoving machines used for a variety of tasks, including forming tools for creating banks, ditches, and shoulders; surface preparation tools for ripping and other surface treatments; and finishing tools for refining or smoothing site and road surfaces to a final shape and contour. Although not always the case, motor graders typically have a front frame and a rear frame connected at an articulating joint. The rear frame includes compartments for housing the power source and cooling components, with the power source operatively coupled to the rear wheels for primary propulsion of the machine. The rear wheels are typically arranged in tandem sets on opposite sides of the rear frame.The front frame typically has a pair of front wheels and carries an operator station and a blade assembly.

[0003] To create a desired shape, contour, and / or finish, the blade of the motor grader or road grader can generally be rotated, tilted, raised, lowered, and / or shifted laterally to any of a wide variety of positions with fine motion resolution. Thus, although the blade is attached to the motor grader, the relative blade position is highly variable.

[0004] The overall steering of the machine is generally a function of both a steering movement of the front wheels (typically referred to as "steer") and an articulation movement of the front frame relative to the rear frame (typically referred to as "articulated movement"). This allows the machine to navigate relatively tight turns and circles, such as those encountered when cornering or turning a road. Given the ability to control the blade position, frame articulation, and wheel steering, operating a motor grader presents operators with a complex task.The operator interface for controlling the machine generally includes various manually operated controls to steer the front wheels, position the blade, control frame articulation, and control additional devices such as rippers and plows, while also including various displays for monitoring machine conditions and / or machine functions.

[0005] During tasks that require fine positioning of the blade and machine, even experienced operators will often need to slow down to avoid damaging the road or striking nearby markings while ensuring the blade reaches the boundaries of the area being worked. As used here, the term "marker" refers to a structure that must be followed, such as an edge or curb. While a mark does not need to be specifically marked with a visible paint or other marking substance, the term "marker" does not exclude such visibly marked structures.

[0006] When grading or grading in a dead-end path, the operator must maneuver the motor grader around a tightly curved path while keeping the blade at a desired distance from edges and other obstacles. This requires the operator to simultaneously control the blade, the front wheel steering, and the frame articulation angle. Failure to properly control any of these variables can result in collisions between the blade and an obstacle or incomplete processing.

[0007] Certain systems attempt to address parts of this problem. For example, US 2010 / 0 010 703 A1 by Coats et al. discloses a method for guiding a machine directed toward maintaining a machine position relative to a marker. While the system by Coats et al. helps operators automate certain machine positioning tasks, it does not address blade positioning for sensitive operations such as dead-end peeling and contouring.

[0008] US 2006 / 0 042 810 A1 discloses a method and control for lateral shifting of work implements. A position monitoring system tracks a position of the work implement relative to a mapped landscape and is programmed to include an electronic representation of at least one object to be avoided in the mapped landscape. A controller initiates movement of the work implement in response to information from the position monitoring system.

[0009] DE 10 2008 008 448 A1 discloses a machine with an automated steering system operatively connected to at least one ground-engaging device. A path generator generates a path along which the machine can travel. A path tracking device automatically controls the steering system to position the machine in a predetermined vicinity of a starting point of the generated path and to guide the machine along the generated path.

[0010] The present disclosure is directed to a control system and control method for a machine to improve operations of a motor grader to address one or more of the problems or disadvantages set forth above. It should be noted, however, that the solution to any particular problem is not a limitation on the scope of this disclosure and the appended claims unless expressly stated. Furthermore, this Background Art section discusses problems and solutions noted by the inventors; however, the inclusion of any problem or solution in this section is not an indication that the problem or solution represents known prior art unless expressly stated.With regard to the prior art expressly mentioned as such, its summary shall not modify or supplement the prior art document itself; any deviation or difference should be resolved by reference to the prior art. Summary of Revelation

[0011] The object of the present invention is achieved by a motor grader and by a method for controlling a motor grader according to the main claims. The subclaims relate to preferred embodiments of the invention.

[0012] According to one aspect of the present disclosure, a motor grader is provided having an articulated frame with one or more steerable traction devices at one end of the articulated frame and one or more drive traction devices at an opposite end of the articulated frame. A blade is positioned below the articulated frame to plow a ground surface beneath the motor grader, and an articulated actuator is arranged and configured to establish an articulation angle of the articulated frame.A steering actuator is arranged and configured to establish a steering angle of the one or more steerable traction devices, and a translation actuator is arranged and configured to translate the blade relative to the articulated frame. At least one object sensor detects a road marking adjacent to the motor grader and provides information indicative of a distance between the blade and the road marking. A controller is provided to receive a mode selection signal from a mode selection switch that identifies a desired operating mode from a plurality of available modes, including a manual mode and an automatic blade control mode, wherein the controller controls the blade translation actuator to achieve a target orTarget distance between the blade and the road marking is maintained, an automatic blade and articulation control mode in which the controller controls the blade shift actuator and the articulation actuator so that the target distance between the blade and the road marking is maintained when the machine is steered by the operator, and a fully automatic control mode in which the controller controls the blade shift actuator, the articulation actuator and the steering actuator to guide the motor grader while maintaining the target distance between the blade and the road marking.

[0013] According to another aspect of the disclosure, a method is provided for controlling a motor grader having a blade, a blade shift actuator, an object sensor for detecting a distance to an edge, one or more steerable wheels, a steering actuator, an articulated frame, and an articulated joint actuator. The method includes periodically determining, via the object sensor, a gap between the blade and a feature of the edge, wherein the object sensor detects the feature of the edge adjacent to the motor grader and provides information indicative of a distance between the blade and the feature of the edge, and maintaining the gap at a target distance in the absence of operator intervention by automatically manipulating the blade shift actuator, the steering actuator, and the articulated joint actuator.

[0014] Additional and alternative features and aspects of the disclosed methods and systems will become apparent upon reading the detailed description in conjunction with the accompanying drawing figures. Short description of the drawings Fig. 1 is a pictorial representation of a side view of an exemplary motor grader; Fig. 2 is a pictorial representation of a top view of an exemplary motor grader; Fig. 3 is a schematic illustration of a top view of an exemplary motor grader illustrating steering and articulation angles; Fig. 4 is a control schematic showing controller inputs and outputs used in carrying out various embodiments of the disclosed systems and methods; Fig. Figure 5 is a flowchart illustrating an overview of an operating procedure of certain aspects of a motor grader machine based on a mode selection by the operator: Fig. 6 is a flowchart illustrating an automatic shield control method according to an embodiment of the disclosure; Fig. 7 is a flowchart illustrating an automatic blade and articulated control method according to an embodiment of the disclosure; Fig. 8 is a flowchart illustrating an automatic blade, steering, and articulation control method according to an embodiment of the disclosure; and Fig. Figure 9 is a schematic example of a display that allows selection of certain parameters by an operator. Detailed description of the revelation

[0015] The present disclosure provides a system and method for steering and blade control of a motor grader for operations related to road markings, such as, but not limited to, edges or curbs, etc. Referring now to Fig. 1 and Fig. 2, an exemplary motor grader according to an embodiment of the present disclosure is shown. The illustrated motor grader 10 includes a front frame 12, a rear frame 14, and a work tool 16. In the context of a motor grader, a work tool 16 is typically a blade assembly 18, sometimes referred to as a drawbar-circle-moldboard (DCM) assembly. The blade assembly 18 may include a separate blade portion and a moldboard portion, and such assemblies are collectively referred to herein as a blade-moldboard or DCM.

[0016] The rear frame 14 includes a power source (not shown) contained within a rear compartment 20. The power source is typically operatively coupled through a transmission (not shown) to rear traction devices or wheels 22 for primary propulsion of the machine. As shown, the rear wheels 22 are operatively suspended in tandem assemblies 24 pivotally connected to the machine between the rear wheels 22 on each side of the motor grader 10. The power source may, for example, be a diesel engine, a gasoline engine, a natural gas engine, or any other engine known in the art. The power source may additionally or alternatively comprise a battery, a fuel cell, or other device for storing electrical power known in the art.The transmission may be a mechanical transmission, a hydraulic transmission, or any other type of transmission known in the art and may be operable to produce multiple output speed ratios (or a continuously variable speed ratio) between the power source and the driven traction devices.

[0017] The front frame 12 supports an operator station 26 containing various operator controls along with a variety of displays or indicators used to provide information to the operator used for the primary operation of the motor grader 10. The front frame 12 also includes a beam 28 supporting the blade assembly 18. The blade assembly 18 includes a drawbar 32 pivotally connected to a first end 34 of the beam 28 via a ball joint (not shown). The position of the drawbar 32 is controlled by three hydraulic cylinders: a right lift cylinder 36 and a left lift cylinder 38 that control vertical movement, and a center shift cylinder 40 that controls horizontal movement. As used herein, "blade shift" refers to lateral translation of the blade via the center shift cylinder 40.

[0018] The right and left lifting cylinders 36, 38 are pivotally connected to the carrier 28 for rotation about an axis C via a coupling device 70 having lifting arms 72. A lower part of the coupling device 70 has a horizontal member 74 of adjustable length, which is connected to the central displacement cylinder 40.

[0019] The drawbar 32 includes a large, flat plate, commonly referred to as the yoke plate 42. Beneath the yoke plate 42 is a circular gear assembly and support, commonly referred to as the circle 44. The circle 44 is rotated, for example, by a hydraulic motor, referred to as the circle drive 46. In other embodiments, an electric motor is used to enable rotation of the circle 44.

[0020] Regardless of the technology used to drive the circular drive 46, rotation of the circle 44 by the circular drive 46 rotates the blade 30 attached thereto about an axis A perpendicular to a plane of the drawbar yoke plate 42. As used herein, the blade cut angle refers to an angle of the blade 16 relative to a longitudinal axis 48 of the front frame 12. For example, at a blade cut angle of zero degrees, the blade 30 is disposed at a right angle to the longitudinal axis 48 of the front frame 12 and the beam 28 transverse to the machine 10, as shown in Fig. 2 shown.

[0021] A pivot assembly 50 between the blade 30 and the circle 44 allows the blade 30 to tilt relative to the circle 44. For this purpose, a blade tilt cylinder 52 is used to tilt the blade 30 forward or backward. In other words, the blade tilt cylinder 52 is used to tilt or tilt an upper edge 54 relative to the lower cutting edge 56 of the blade 30, and the occurrence or extent of this tilting is commonly referred to as "blade tilt" or "blade pitch," respectively.

[0022] As noted above, the steering of the motor grader 10 is achieved by a combination of a steering movement of the front wheels and an articulated movement of the machine. Fig. 2, steerable traction devices (right wheel 58 and left wheel 60 in the illustrated example) are associated with the first end 34 of the beam 28. The right wheel 58 and the left wheel 60 may be pivotable and tiltable for use during steering and leveling of a work surface 86. The right wheel 58 and the left wheel 60 are connected via a steering device 88, which includes a pull rod 90 for simultaneously pivoting the wheels about pivot points 80, as well as one or more wheel tilt actuators 91 for providing tilting movement of the front wheels.

[0023] With reference to the Fig. 1 and Fig. 3, the motor grader 10 has an articulated joint 62 which pivotally connects the front frame 12 and the rear frame 14 at an articulated axle B. Both a right articulated steering cylinder 64 and a left articulated steering cylinder 66 are connected between the front frame 12 and the rear frame 14 on opposite sides of the machine 10. The right and left articulated steering cylinders 64, 66 are used to pivot the front frame 12 relative to the rear frame 14, which are separated at the articulated axle B. In the illustrated example of the Fig. 2, the motor grader 10 is positioned in the neutral position or position with a zero articulated steering angle, with the longitudinal axis 48 of the front frame 12 aligned with a longitudinal axis 68 of the rear frame 14.

[0024] Fig. 3 provides a plan view of the motor grader 10 with the front frame 12 articulated about an angle α defined by the intersection of the longitudinal axis 48 of the front frame 12 and the longitudinal axis 68 of the rear frame 14, the intersection point corresponding to the position of the articulated linkage 62. This illustration follows the convention that a positive value indicates leftward articulated movement from the perspective of an operator looking forward, while a negative value would indicate rightward articulated movement. A front wheel steering angle θ is defined between a longitudinal axis 76 parallel to the longitudinal axis 48 of the front frame 12 and a longitudinal axis 78 of the front wheels 58, 60, with the angle θ having an origin at the pivot point 80 of the front wheels 58, 60. This is shown in conjunction with the left front wheel 60, but is applicable to the right front wheel 58.It will be clear that a slightly different steering angle must be provided in order to make the turning centers of the front wheels 58, 60 coincide as shown, the outer wheel generally having a longer radius.

[0025] As can be seen, the motor grader 10 has many degrees of freedom, both in terms of steering position and blade position, providing the ability to perform precise work. However, these various degrees of freedom must be carefully controlled to provide the best work product and experience for the operator. As mentioned above, dead-end or turnaround operations can be particularly challenging, given the need to precisely steer the motor grader 10 while simultaneously positioning the blade assembly 18 with sufficient accuracy, particularly in the translation direction, to avoid damage to the curb contour or incomplete finishing or leveling.

[0026] In one embodiment of the disclosure, a number of special machine modes are provided, including an automatic blade mode in which the blade assembly 18 is automatically positioned relative to a pavement marking, such as a curb or road edge, while the operator controls the positioning of the machine 10 via steering and articulation. In another embodiment, the machine's articulation is also automated, so that the articulation movement and blade translation are cooperatively controlled to maintain a desired spacing between the edge of the blade assembly 18 and the marking. In yet another embodiment, a fully automatic mode provides automatic control of blade lateral translation, frame articulation movement, and wheel steering movement.As an optional aspect of one or more modes, the machine speed can be controlled or limited. These different modes simplify the interaction of leveling or finishing in a dead-end lane near curbs and improve work product uniformity during long stretches of straight-line leveling near a road edge or curb.

[0027] With reference to Fig. 4, one embodiment of the disclosure employs a controller 94 for receiving and evaluating machine commands, such as mode selection, although other physical implementations are possible. The controller 94 is also configured to receive and evaluate machine data, such as a steering angle, a blade angle, a blade shift, a blade pitch, a machine speed, etc. Additionally, the controller 94 may receive and evaluate sensor data, such as the location of the pavement marking adjacent to the machine, the curvature of the marking, or a decrease in the distance between points on the marking, etc.The controller 94 also provides data and control outputs as needed to carry out the methods described herein, depending on the selected mode, for example, to adjust the displacement of the blade assembly 18, to adjust the steering movement and tilt angle of one or more machine wheels, to adjust the articulation angle, etc.

[0028] The control device 94, in one embodiment, is embodied as a computing device embodying one or more microcontrollers and / or microprocessors (collectively referred to herein as a "processor" or "digital processor"). The control device 94 operates by reading or loading computer-executable instructions, or code, from a non-transitory computer-readable medium, such as non-transitory memory, magnetic or optical disk storage, flash memory, etc. The control device 94 may execute the instructions in a time-shared manner, in a multi-threaded manner, or any other suitable execution technique. It will be understood that data used by the control device 94 in executing the computer-readable instructions may also be stored and retrieved, or may be generated in real time.The controller 94 has one or more interfaces for receiving data and / or commands, and one or more outputs for outputting data and / or commands, such as those discussed above. The controller 94 may be an isolated controller or, alternatively, may be integrated with another controller that also serves other machine functions.

[0029] In the Fig. 4, the controller 94 receives a steering angle sensor input signal 96 from one or more steering angle sensors 98. This steering angle sensor input signal 96 provides a signal indicative of the steering angle. As used herein, a signal indicates a particular quantity or value when communicated directly or indirectly, or it can be used to directly or indirectly calculate the quantity or value. With respect to all input quantities, it will be appreciated that each signal can be communicated over a dedicated physical line or channel, or can be multiplexed over one channel for multiple signals, as may be the case if the machine 10 utilizes a managed machine network. In any event, one or more input signals can be communicated at least in part by wireless transmission.

[0030] The control device 94 further receives a steering input signal 100 from one or more operator steering control devices 102, which indicates an operator steering command. The operator steering controls 102 may include a joystick, as shown in FIGS. Fig. 1-2, or any other type of operator input device, such as a wheel, keyboard, pedal, or other devices known in the art. In one embodiment, a steering angle sensor is configured to sense the rotation or position of the operator steering controls 102 and provide a steering input signal 100 indicative of a steering angle θ.

[0031] In one embodiment, the controller 94 further receives an articulated steering input signal 104 from one or more articulated steering sensors 106, the articulated steering input signal 104 indicative of the articulated steering angle α at the axis B between the rear frame 14 and the front frame 12. In another embodiment, the one or more articulated steering sensors 106 include a pivot sensor disposed at the articulated steering linkage 62 to sense rotation about the articulated steering axis B. Additionally or alternatively, the one or more articulated steering sensors 106 may include one or more sensors configured to monitor the extension movement of the right and / or left articulated steering cylinders 64, 66.It will be appreciated that the steering angle sensors 98, the steering wheel sensor (on the operator steering controls 102), the articulated steering sensors 106, as well as other rotary motion sensors, such as potentiometers, extension motion sensors, proximity sensors, angle sensors, rotary encoders, etc.

[0032] In one embodiment, one or more blade position sensors 110 provide a blade position input signal 108 to the controller 94, where the blade position input signal 108 is indicative of the actual position of the blade 30. Such sensors may be configured to directly sense blade position or may be configured to indirectly sense blade position (e.g., from pin angle sensors, etc.) based on the positions of related hydraulic actuators. In one embodiment, the blade position is sensed in at least the translation direction via a non-contact sensor ("object sensor"), such as a digital camera, LADAR, LIDAR, etc. The blade position input signal 108 may also indicate a position of the blade 30 in other dimensions, such as pitch, inclination, and roll or cut angle.

[0033] Similarly, a blade position command input signal 124 from an operator blade position input device 126 provides information to the control device 94 regarding operator inputs for positioning the blade 30. The operator blade position input device 126 may be any suitable operator control for adjusting the blade position, including, but not limited to, one or more joysticks, levers, etc.

[0034] One or more transmission sensors 114 associated with the transmission may be used to provide a gear input signal 112 indicative of a current gear or output ratio associated with the machine's transmission. Alternatively, the gear input signal 112 may be provided by signals associated with operator controls for the transmission (not shown).

[0035] Although the machine configuration may be known from the above-mentioned data inputs to the controller 94, the position of the machine and blade relative to a pavement marking, such as a curb, cannot be determined from these inputs, except perhaps by extrapolation from a past known relationship. To provide real-time information regarding the location of the marking adjacent to the machine 10 and / or in front of the machine 10, one or more marker sensors 118 ("object sensors") provide a marker position input signal 116 to the controller 94 for this purpose. In one embodiment, the one or more marker sensors 118 comprise only a single sensor that is selectively directed to one side of the machine 10 or the other, depending on which side of the machine 10 the pavement marking is known to be located or has been detected.Additionally or alternatively, the one or more marker sensors 118 may comprise multiple stationary sensors or a more limited number of scanning sensors, or a combination of stationary and scanning sensors. A scanning sensor, in this context, is one that can be dynamically directed to a different field of view, i.e., it can be selectively directed forward or sideways, downward or sideways, left or right, etc. Additionally, virtual sensor arrays can be further developed from a single sensor via heterodyne detection schemes to enhance the characteristics of the individual sensors.

[0036] The one or more marker sensors 118 may include one or more LIDAR (light detection and ranging) sensors, one or more LADAR (laser detection and ranging) sensors, one or more digital cameras, and / or other types of sensors. It should be noted that LIDAR sensing involves emitting and detecting UV, visible, or near-infrared radiation to determine a distance between the sensor and a target object, such as a road marking. Similarly, LADAR involves the use of laser radiation to detect the distance to the target object. In addition to employing coherent radiation instead of the non-coherent radiation used in LIDAR, LADAR can also operate in regions of the electromagnetic spectrum not used by LIDAR.

[0037] While LADAR can generally provide better accuracy at greater distances than LIDAR, the systems and methods of this disclosure relate to short-range detection. Similarly, cameras typically provide accurate range information only at short distances relative to both LADAR and LIDAR, but cameras provide suitable ranging capabilities within the short ranges contemplated here. As such, the selection of sensor type, number, and location may be resolved by considerations of cost and availability, as well as any other considerations of sensor multiplexability, rather than by issues of efficiency. For example, a single sensor may be used for both object detection and person detection, or for other additional purposes.

[0038] In one embodiment, all or a subset of the one or more marker sensors 118 may be configured in conjunction with the processor to preferentially detect a particular marker, material, or quality associated with the pavement marking. For example, a curb edge may be characterized by an elongated block of a certain color or color range delimited by linear boundaries, or with respect to other colors, such as the color of the ground, grass, etc.

[0039] In environments where the linear character of the curb edge is indistinguishable or the color of the curb edge is too close to the colors of other surfaces surrounding the curb edge, a non-naturally occurring color may be applied to the curb edge to provide a signal to the one or more marker sensors 118 that are preferentially to be detected. For example, a continuous stripe of bright white or neon orange color may be applied to the curb edge to aid in detection and / or ranging. In this embodiment, the detected non-naturally occurring color would identify a target, such as the curb edge, to which the ranging is related.

[0040] In one embodiment, a drive input signal 120 is provided to the controller 94 from one or more operator-controlled drive interface devices 122, such as accelerator pedals or levers, transmission mode selectors, etc. Such interface devices 122 may be located in the operator station 26. An engine speed input signal 121 is also provided to the controller 94 in one embodiment, with associated engine speed data from a revolution sensor 123 or the like.

[0041] A machine position sensor cluster 130 is configured to provide the controller 94 with a machine position input signal 128. The machine position sensor cluster 130 may include, without limitation, one or more accelerometers, inclinometers, inertial measurement units, and other orientation sensors, as well as a GPS or other positioning system. As such, the machine position input signal 128 provides the controller 94 with information regarding both the position and orientation of the machine 10.

[0042] As mentioned above, a mode selection option is provided to the operator in one embodiment of the disclosure. The mode selection option may be offered via a mode selection switch 134, which provides a mode selection signal 132 to the controller 94. As discussed in more detail below, the mode selection switch 134 may be used to select among various operating modes, including, for example, an automatic blade mode, an automatic blade and articulated mode, a fully automatic mode, and a normal or manual mode.

[0043] Before discussing these modes and the operation and configuration of the controller 94 for performing the operations in the various modes, exemplary outputs of the controller 94 will be briefly identified and discussed. It will be understood that each output signal may be provided over a dedicated physical line or channel, or that all outputs may be multiplexed over a smaller number of non-dedicated lines or channels. One or more outputs may be communicated, at least in part, via wireless transmissions.

[0044] To maintain machine position for modes requiring such control, controller 94 provides a steering output 136 for adjusting the steering angle to the front wheels of machine 10. Steering output 136 may be provided to a system controller that executes the steering command. For example, steering output 136 may be provided to and processed by the same logic and hardware that processes steering commands from the operator steering controls, which further actuates hydraulic cylinders (not shown) of steering device 88 to execute the steering command. As discussed later, in one embodiment, steering output 136 may be overridden by the operator.

[0045] To control the articulated movement of the machine 10 when a mode requires such control, the controller 94 provides an articulated steering output 138. As with other outputs, the articulated steering output 138 may be provided to another controller or subsystem responsible for executing articulated steering commands. Alternatively, the articulated steering output 138 may be executed via independent hardware components and processing. In either case, the indicated articulated steering command is used to control the articulated steering movement of the machine frame, for example, via the articulated steering actuators 64, 66.

[0046] To control the position of the blade 30 to maintain the distance between the blade and the road marking during operations ("target distance"), the controller 94 provides a blade displacement output 140. The blade displacement output 140 may be provided to a control solenoid associated with a hydraulic control valve for the center displacement cylinder 40 via the same components as the operator input displacement commands or via an independent channel or circuit.

[0047] Finally, in some modes, it may be desirable to control machine speed. For this purpose, controller 94 provides a machine speed output 142. Machine speed output 142 may include, or may be used to generate, commands to control machine engine speed, drive speed, and / or transmission mode or range. For example, in rough ground conditions, it may be desirable to maintain constant torque on the traction elements, while in an environment with significant grade variation, it may be desirable to maintain a constant machine speed.

[0048] Exemplary methods used by the controller 94 in one embodiment to control the sign distance to a road marking in various modes are described in the Fig. 5-8. While the disclosure will exemplify these methods as being performed by the controller 94, it will be understood that the methods may be performed in a distributed manner in a given implementation, if needed or desired. Furthermore, it will be understood that the order of steps within each process is illustrative, and the steps need not occur in the given order unless otherwise apparent from the disclosure. Moreover, while the disclosure explains operations in various executable modes, it is also contemplated that for a machine in a particular implementation, it may support only a subset of the described methods, or indeed support only a single mode, without departing from the scope of the teachings.

[0049] Now with reference to Fig. 5 shows an overview method 150 for operating certain aspects of the machine based on a mode selection by the operator, for example, through the mode selection switch 134. The method 150 is used to identify further methods for execution based on the mode selection. In step 152 of the method 150, the controller 94 receives a mode selection signal from the mode selection switch 134. The mode selection signal identifies a desired operating mode selected from available modes, such as manual control, automatic blade control, automatic blade and articulated control, and fully automatic control.

[0050] In the illustrated embodiment, the method 150 subsequently determines in step 154 ​​which of the available modes has been selected and ends if manual operation has been selected, proceeding to jump point A (see Fig. 6), if automatic shield control has been selected, proceed to jump point B (see Fig. 7) if automatic blade and articulated steering control has been selected, and proceeds to jump point C (see Fig. 8) when fully automatic control has been selected. In an optional embodiment, modes other than manual mode may be locked, i.e., not selectable, when the machine speed is higher than a predetermined acceptable speed.

[0051] With reference to Fig. 6, an automatic blade control method 160 is shown. The automatic blade control method 160 is entered at jump point A and begins with optional step 162, where the controller 94 receives a marker sensor position signal, for example, an indication of whether a marker sensor, such as a camera, LIDAR sensor, or other marker sensor, is pointing toward the left or right side of the machine 10. Alternatively, the controller 94 may determine an appropriate direction for the marker sensor and automatically position the marker sensor.

[0052] For example, if an automatic mode is selected in a single-sensor embodiment, the controller 94 may scan or guide the sensor to a first side of the machine 10, for example, to the right relative to a curb or other marking, and if such a marking is found, maintain the sensor in that orientation. If no curb or other marking is found during a scan on the right, the controller 94 may then scan or guide the sensor on the opposite side of the machine 10. In an embodiment using separate left- and right-facing sensors, the mark sensor position signal may indicate which mark sensor should be active, for example, on which side of the machine 10 the mark was detected.

[0053] Before proceeding in method 160, the controller 94 may instruct the operator via a visible display to adjust certain aspects of the blade positioning to a desired setting, such as setting a desired blade pitch, inclination, and circle shift. Once the marker sensor position has been determined, the method 160 proceeds to step 164, where the controller 94 determines the distance from the blade 30 to the detected marker, such as the curb or other marker. While a given sensor, such as a camera, LIDAR sensor, LADAR sensor, etc., will typically only determine the distance between the sensor itself and the marking, the controller 94 can then process the distance information, taking into account the known sensor position relative to the machine and the known blade position relative to the machine, to determine the distance from the blade edge to the marking.

[0054] In one embodiment, the detected marking structure may be displayed to the user, who then selects which feature to follow. For example, a square (curb) edge may have four or more linear features, including those in the base, and the user may select a feature of the displayed structure to which the distance should be measured. In an alternative embodiment, the operator is also prompted to set an acceptable sign gap. For example, the operator may be shown a camera view of the sign and marker on a display and may set a gap visually or numerically on the screen, or may manually move the sign while observing the display unit until the desired gap is reached.

[0055] A schematic example of a display allowing a selection of parameters by the user is shown in Fig. 9. The illustrated selection display 206 shows the detected linear features of a (curb) edge 208 in cross-section as a (curb) edge point A (210), (curb) edge point B (212), and (curb) edge point C (214). In one embodiment, a marker, such as bright paint, may be applied to the curve, either along the entire length to be followed or periodically, to enhance the sensor's ability to detect and distinguish the curve or certain features of the (curb) edge.

[0056] Each (curb) edge point 210, 212, 214 is associated with a tracking curve, i.e., tracking curve A (216), tracking curve B (218), and tracking curve C (220). The sign 30 is represented in the display 206 by the sign outline 222. In one embodiment, the display 206 includes one or more parameter fields that allow the operator to enter desired parameters. In the illustrated embodiment, the display 206 includes a sign gap field 224 in which the operator can enter a numerical sign gap, as well as a finish selection field 226 for selection when a finish setting for the gap exists.As mentioned above, the user may also manually adjust the shield gap while viewing the display 206, or in another embodiment, the user may adjust the gap by operating the display itself via cursor selection or touch screen operation.

[0057] When selecting a curb edge point to measure to, in one embodiment, the operator also selects the corresponding tracking curve. Because the mechanisms associated with the blade 30 cannot react instantly, the curve allows the control device 94 to predict and accommodate upcoming curves and discontinuous portions. In this context, it should be noted that the tracking curves 216, 218, 220 do not need to precisely follow the selected curb edge point. Instead, a tracking curve can be interpolated over smaller gaps or discontinuous portions of a specific curb edge point, such as a gap for a drain grate, a manhole cover opening, etc.

[0058] In one embodiment, the interpolated tracking curve during a discontinuous portion consists of a curve segment connecting the last non-interpolated point before the gap and the first non-interpolated point after the gap. In this embodiment, the curve segment has a curvature that is essentially the average of the curve values ​​immediately before and immediately after the gap. Local curvatures can be identified by a radius, a polynomial expression, or in another way.

[0059] In some cases, the tracking curve may have an end, meaning no point beyond the curve is visible, unlike a gap where a point on the other side can be detected. In such cases, when the sign 30 reaches an end point, the tracking method may fix the sign position at its current position until the curve is detected again, may terminate automatic sign control, or may shift the sign 30 sideways away from the curb edge. A different response may be appropriate depending on the implementation environment. For example, if the tracked curb edge or other marker is known to be circular or follows some other predetermined path, the tracking method may continue to track the virtual known curve even if no actual detectable curb edge or other marker is present.

[0060] Continuing with method 160, if the operator has not manually adjusted the gap, the controller 94 moves the blade 30 in step 166 to the extent necessary for the distance from the blade edge to the marker to match a target blade gap distance, which may be as little as approximately 30 mm or less, depending on the machine's motion resolution, up to much greater gap distances, such as may be required when working near (curb) edges that have extended base portions. In one embodiment, the target blade gap distance is a preset value, and in an alternative embodiment, the operator may select the target distance to be maintained, as mentioned above.

[0061] In step 167, the controller 94 maintains the gap between the blade 30 and the selected curve as the machine 10 moves forward by adjusting the blade lateral displacement via the center displacement cylinder 40. In one embodiment, the blade displacement performed in step 167 is limited to a predetermined percentage of the range of available displacement of the blade to allow some reserve capacity for further displacement if necessary. For example, the displacement in step 167 may be limited to 75% of the total available range. A warning indicator is provided in one embodiment when the lateral displacement reaches the preset limit.

[0062] As the machine 10 continues to advance along the marker, the controller determines in step 169 whether the operator has steered the machine 10 out of the marker range. If the operator has steered the machine 10 out of the marker range, the method 160 raises the blade in step 170 and returns the machine to manual control. Conversely, if it is determined in step 169 that the operator has not steered out of the marker range, the method loops back to step 162 to re-evaluate and further refine the blade position as the machine 10 moves forward. In one embodiment, a warning may be provided before returning to manual control. For example, a visual or audible warning may indicate that the blade gap distance is at risk of being out of range, that the machine is traveling too fast, etc.

[0063] In addition to the termination conditions mentioned above, one or more other conditions may also cause the machine 10 to return to manual control. For example, in one embodiment, method 160 is terminated and the machine 10 is returned to manual operation when the operator manually manipulates the blade's lateral shift, for example, via operator controls at operator station 26.

[0064] If the automatic blade and articulated steering control mode was selected in step 154 ​​of the method 150, then the controller 94 operates according to the Fig. 7, which is initially similar to the automatic blade control method 172. Method 172 is entered at jump point B and begins with optional step 174, where the controller 94 receives a marker sensor position signal or determines an appropriate direction for the marker sensor and automatically positions the marker sensor, as discussed above. Before proceeding, the controller 94 may instruct the operator via a visual display to adjust certain aspects of the blade positioning to the desired setting, such as adjusting a desired blade pitch, rake, and circle shift, as discussed with respect to method 160.

[0065] The controller 94 then determines the distance from the sign 30 to the detected mark in step 176 and moves the sign 30 to the required extent in step 178 so that the distance from the sign edge to the mark matches the preset sign gap distance if the user has not manually adjusted the gap. As described above with reference to Fig. As mentioned in Figure 9, in an alternative embodiment, the detected marking structure can be displayed to the user, who then selects which feature to follow and sets an appropriate gap.

[0066] As the machine 10 subsequently moves forward, the controller 94 maintains the gap initially established between the blade 30 and the selected curve by adjusting the lateral displacement of the blade via the center displacement cylinder 14 in step 179. In one embodiment, the blade displacement is limited to less than the actual available range of lateral displacement of the blade, for example, to 75% of the total available range. Again, a warning indicator may be provided when the lateral displacement reaches the preset limit.

[0067] In addition to checking and adjusting the blade position, the controller 94 also controls the articulated steering movement of the machine in a present embodiment. Controlling the articulated steering movement serves three purposes: ensuring compliance with certain movement rules, providing additional lateral shift capability, and allowing the rear wheels to follow to an extent compatible with other articulated steering objectives. Thus, the controller senses the steering angle θ, for example, via the steering input signal 100 in step 180.In step 182, the controller 94 adjusts the frame articulation angle α (as sensed via the articulation input signal 104 and controlled via the articulation output 138 for the right and left articulation cylinders 64, 66) based on (1) certain driving rules that, for example, do not allow the rear wheels to hit the (curb) edge, (2) the amount of remaining required lateral displacement of the blade, if any, and (3) the detected steering angle θ.

[0068] In one embodiment, these objectives are pursued in order. For example, an articulated steering adjustment required to prevent the rear wheels from striking the curb will be given priority over any adjustments needed to provide additional lateral displacement of the blade or to keep the front and rear wheels in-line. Furthermore, if there is no apparent risk of striking the curb, any adjustment needed to provide additional lateral displacement of the blade will be given priority over adjustments needed to keep the front and rear wheels in-line.Finally, if no articulated steering motion adjustments are required to avoid hitting the (curb) edge or to provide lateral displacement, then an articulated steering motion adjustment can be performed to allow the wheels to remain in the lane.

[0069] Additionally, in one aspect, a warning or indicator may be provided to the operator when an articulation movement is actively altered by the controller 94. In one embodiment, the controller 94 may additionally adjust the blade circle offset to provide an additional range of blade lateral movement when the articulation movement available within the above limits is insufficient for the blade 30 to continue following the curve.

[0070] The manner of linking the detected steering angle θ to a desired articulated steering angle for wheel tracking can be accomplished by any suitable method. For example, the method described in US 2011 / 0 035 109 A1 controls an articulated steering movement based on the steering angle in such a way that a rear centerline point will follow a front centerline point. It will be appreciated that other types of steering-based articulated steering control may be used instead, depending on the application environment. For example, instead of following the steering movement of the front wheel, the articulated steering movement may be used to emphasize or dampen steering impulses.

[0071] With reference to Fig. 7, as the machine 10 travels along the marker, the controller 94 determines in step 184 whether the operator has steered the machine 10 out of the range of the marker and raises the blade 30 and returns to manual control in step 186 if this has occurred. Otherwise, the method 160 loops back to step 174 to again evaluate and refine the blade position as the machine 10 moves forward. Even without movement of the blade 30 itself relative to the machine 10, it will be appreciated that changes in the blade position relative to the marker may occur due to machine movement due to steering and articulation and / or due to lateral variations in the position of the marker.

[0072] In an alternative embodiment, controller 94 adjusts frame articulation and blade position in conjunction with each other, rather than adjusting these variables sequentially based on trends in the marker and / or features of upcoming markers, such as the curvature of the marker. For example, if the blade edge is detected to be too far from the curb or other marker, controller 94 may determine whether the marker will curve within an upcoming predetermined distance, such as one machine length, 30 feet, or a desired gauge length.If the marker does not curve within the specified distance, the controller 94 may wait to receive a predicted change in steering and may then use an articulation adjustment in conjunction with a translation of the blade to close the gap between the blade edge and the marker to the appropriate distance.

[0073] Similarly, controller 94 may use frame articulation and blade translation to balance each other to allow the greatest remaining adjustment freedom as machine 10 continues to move forward. For example, if the current blade translation position is far from center and approaching a path boundary to the left or right, controller 94 may adjust the blade translation back toward center while adjusting frame articulation to compensate for the changed blade edge position relative to the marker.

[0074] If the blade edge is shifted too far from the center toward the marker, the controller 94, in a particular embodiment, may shift the blade 30 back toward the center while reducing the articulation movement, with the result that the gap between the edge of the blade and the marker remains as desired. However, as mentioned above, the operator may steer so far away from the marker that the full range of blade shift and frame articulation movement is insufficient to maintain the gap at the appropriate level. As described in steps 168 and 184 of the Fig. 6 or 7, the control device 94 may in this case assume that the machine 10 is outside the range and may terminate the desired automatic procedure.

[0075] With brief reference to Fig. 5, a fully automatic control has been selected when step 154 ​​directs the method 150 to the jump point C, and the control device 94 executes the method 188 which is shown in Fig. 8. In one embodiment, the fully automatic control entails controlling a lateral shift of the machine blade and an articulated steering movement to maintain a set gap to the edge (curb) or other marking. Additionally, the machine speed may optionally be controlled to remain below a preset setpoint. Alternatively, method 188 may require a check of the machine speed before beginning, as discussed above with respect to other embodiments.

[0076] In performing method 188, controller 94 initially receives a marker sensor position signal or determines a suitable direction for the marker sensor and automatically positions the marker sensor in step 190, as discussed above. At this time, controller 94 may prompt the operator via a visible display to adjust the blade pitch, tilt, and rotation or orbital translation, and optionally adjust a suitable gap between the blade and the curb or other marker, for example, via a display-driven process as discussed above.

[0077] The controller 94 then determines the distance from the sign 30 to the detected marker in step 192 and moves the sign 30 in step 194 to the extent necessary so that the distance from the sign edge to the marker matches the preset sign gap distance if the user has not manually adjusted the gap, to the extent that such movement does not violate a predetermined range boundary.

[0078] As the machine 10 then moves forward, the controller 94 maintains the initially set gap between the blade 30 and the selected curve primarily by adjusting the blade's lateral displacement via the center displacement cylinder 40 in step 194. If the blade's displacement is limited to less than the actual available range of blade lateral displacement, as discussed above, then any unmet lateral displacement request can be accommodated in later steps. In this embodiment, a warning indicator may be provided when the lateral displacement reaches the preset limit.

[0079] In step 196, the controller 94 controls the machine steering angle θ and the frame articulation angle α to provide any additional lateral displacement to the extent that this is compatible with any movement rules, such as not allowing the rear wheels to strike the curb or other marking. Thus, in step 196, the controller 94 adjusts the steering angle and the articulation angle so that the machine 10 moves closer to or farther from the curb to help maintain the gap at the desired value, while also maintaining the lateral displacement of the blade within an acceptable range, to the extent that the adjustment does not violate any movement rules.

[0080] The relationship between the steering angle θ and the articulation angle α can be set in any desired manner, however, in one embodiment, the steering angle and the articulation angle are set such that a rear centerline point will follow a front centerline point, as discussed above. If the available articulation movement within the above limits is insufficient to allow the blade 30 to continue following the curve without violating a constraint as mentioned above, the controller 94 can additionally adjust the circular displacement of the blade to provide an additional range of lateral movement of the blade.

[0081] As the machine 10 advances along the marker, the controller 94 adjusts the steering angle and the frame articulation angle together in step 198 to follow the desired curve. If the curve ends, as determined in step 200 (other than a momentary termination with an expected restart, for example, after a gap), or if the user manually terminates the automatic control method, as determined in step 202, then the method 188 ends. Otherwise, the method 188 continues to execute step 198 to follow the desired curve.

[0082] Although this is not explicitly stated in the Fig.6-8, the controller 94 may control the machine speed during any automatic mode, for example, to maintain a constant speed, in addition to ensuring that the machine speed is less than a predetermined threshold speed. For example, automatic speed control may be useful during operations in environments that have frequent grade changes.

[0083] In one embodiment, the controller 94 exits any automatic blade gap adjustment mode in the event that the operator either attempts to control an automated or fixed function, such as blade depth or blade displacement, or operates a manual control, such as steering, to the extent that the machine 10 is taken out of an automatically correctable range. If the operator switches from an automatic mode to a manual mode at any time, the controller 94 similarly returns the machine 10 to manual control. In another embodiment, the controller 94 causes the blade 30 to be raised when switching from any automatic mode to the manual mode. Industrial applicability

[0084] Generally speaking, the present disclosure provides a system and method for controlling a motor grader during operations that follow a pavement marking, such as a curb. In one embodiment, the system and method control one or more aspects of motor grader operation while grading near a curb in a dead-end lane. In another embodiment, a machine operator may select a mode of operation, with example modes including a manual mode, an automatic blade mode, an automatic blade and steer mode, and a fully automatic mode wherein blade translation, machine steering, and machine articulated movement are automated to follow the marking.At any time during automated operation, the operator can change modes or, in one embodiment, can simply control the machine from a current automatic mode, in which case the machine returns to manual mode. The method and system for operating a motor grader described herein maintains a desired gap between the blade and the marker to prevent the motor grader's blade from striking the marker during operation, particularly during operations adjacent to curved markers, such as the curb in a dead-end street.

[0085] In addition to allowing an operator to hold a motor grader blade at a fixed distance from a curb or other marker, the distance data obtained by this method can also be used or stored historically to provide a record of the leveling process. For example, in one embodiment, the data is used to provide the operator with a map of areas that have been leveled to the desired gap—that is, areas traversed while the blade control was in use. This record can optionally be overlaid on a terrain map to provide an operator or supervisor with a record of work completed, as well as a representation of work yet to be completed.In a further embodiment, the display comprises one or more indicators that show areas where there were problems that needed to be corrected or recorded, such as areas where the gap edge adjustment was violated.

[0086] It will be appreciated that the present disclosure provides an effective and efficient mechanism and control system for controlling a motor grader. Not only does the described system and method generally improve operator comfort and reduce operator fatigue, but they also result in a high-quality grading product or leveling job with less operator training and experience than would otherwise be required.

Claims

[1] Motor grader (10) comprising: an articulated frame (12, 14) having one or more steerable traction devices (58, 60) at one end of the articulated frame (12, 14) and one or more drive traction devices (22) at an opposite end of the articulated frame (12, 14); a blade (30) positioned beneath the articulated frame (12, 14) for leveling or cultivating a ground surface beneath the motor grader (10); an articulated steering actuator (64, 66) arranged and configured to establish an articulated steering angle of the articulated frame (12, 14), further comprising a steering actuator (88), which is arranged and configured to establish a steering angle of the one or more steerable traction devices (58, 60), and a side shift actuator (40) arranged and configured to shift the shield (30) relative to the articulated frame (12, 14); at least one object sensor (118) arranged and configured to detect a road marking adjacent to the motor grader (10) and provide information indicative of a distance between the shield (30) and the road marking; and a controller (94) configured to receive a mode selection signal from a mode selection switch (134) that identifies a desired operating mode from a plurality of available modes, including a manual mode, an automatic blade control mode in which the controller (94) controls the side shift actuator (40) of the blade to maintain a desired distance between the blade (30) and the road marking, an automatic blade and articulated steering control mode, wherein the controller (94) controls the side shift actuator (40) of the blade (30) and the articulated steering actuator (64, 66) to maintain the desired distance between the blade (30) and the road marking when the motor grader is steered by an operator, and a fully automatic control mode,in which the control device (94) controls the side shift actuator (40) of the blade (30), the articulated steering actuator (64, 66) and the steering actuator (88) to guide the motor grader (10) while maintaining the desired distance between the blade (30) and the road marking., [2] The motor grader (10) of claim 1, wherein the at least one object sensor (118) comprises a single repositionable object sensor, and wherein the controller (94) is configured to use the single repositionable object sensor to determine on which side of the motor grader (10) the road marking is located and to position the object sensor (118) to detect the distance to the road marking. [3] The motor grader (10) of any of claims 1 and 2, wherein the controller (94) is further configured to detect an edge of a feature of the road marking and cause the blade (30) to remain a desired distance from the edge when the mode selection signal identifies the automatic blade control mode, the automatic blade and articulated control mode, or the fully automatic control mode. [4] The motor grader (10) of any of claims 1-3, wherein the controller (94) is further configured to detect a steering command from the operator and provide an articulation command to adjust a degree of frame articulation movement based on the detected steering command when the mode selection signal identifies the automatic blade and articulation control mode. [5] The motor grader (10) of any of claims 1-4, wherein the controller (94) is further configured to return to the manual mode of operation when the operator attempts manual control of an automated function. [6] The motor grader (10) of any of claims 1-5, wherein the controller (94) is further configured to return to the manual mode of operation when the operator steers the motor grader (10) beyond a predetermined area of ​​the road marking. [7] A method for controlling a motor grader (10) having a blade (30) with a blade side shift actuator (40), an object sensor (118) for detecting a distance to an edge, one or more steerable wheels (58, 60), a steering actuator (88), an articulated frame (12, 14) and an articulated steering actuator (64, 66), the method comprising: periodically determining a gap between the blade (30) and a feature of the edge via the object sensor (118), wherein the object sensor (118) detects the feature of the edge adjacent to the motor grader (10) and provides information indicative of a distance between the blade (30) and the feature of the edge; and automatically maintaining the gap at a desired distance above the object sensor (118) in the absence of user interaction by automatically actuating the blade side shift actuator (40) and the steering actuator (88) and the articulated steering actuator (64, 66). [8] A method of controlling a motor grader (10) according to claim 7, wherein the feature of the edge exhibits a curvature substantially along its length in the direction of travel, and wherein maintaining the gap at the desired distance comprises causing the blade (30) to follow the edge at the desired distance from the feature of the edge. [9] A method for controlling a motor grader (10) according to any one of claims 7 and 8, wherein the object sensor (118) comprises a first object sensor positioned to detect objects on a first side of the motor grader (10) and a second object sensor positioned to detect objects on a second side of the motor grader (10), and wherein periodically determining a gap between the blade (30) and a feature of the edge comprises, by means of the object sensor (118), detecting a distance from one of the first and second object sensors to the edge. [10] A method of controlling a motor grader (10) according to any one of claims 7 and 8, wherein the object sensor (118) comprises a single positionable object sensor, and wherein determining a gap between the blade and a feature of the edge comprises first directing the single positionable object sensor toward the edge.

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