Cutting machine with selectively reduced penetration intensity

Abstract

A hydraulic rotary tool includes a rotatable tool element operable on a work piece and a hydraulic motor operable to drive rotation of the rotatable tool element. A base portion supports the rotatable tool element for rotation and includes an actuator configured to move the rotatable tool element to penetrate the work piece. A pressure sensor at the hydraulic motor or actuator indicates resistance to penetration of the work piece. An electronic processor is configured to: drive the rotatable tool element with a drive signal to the actuator based on a first input command; thereafter monitor a pressure signal from the pressure sensor; calculate a second input command based on the pressure; and upon determining that the second input command is lower than the first input command, update the drive signal to the actuator to automatically reduce to a second penetration intensity based on the second input command.

Description

Attorney Docket No. 489825-0019-W001CUTTING MACHINE WITH SELECTIVELY REDUCED PENETRATION INTENSITYCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to co-pending U.S. Provisional Patent Application No. 63 / 708,928, filed October 18, 2024 and co-pending U.S. Provisional Patent Application No. 63 / 760,897, filed February 20, 2025, the entire contents of both of which are incorporated by reference herein.BACKGROUND

[0002] The present disclosure relates to machines for material reduction of tree stumps by cutting and / or grinding, and more particularly to a control system for cutting with such machines. Aspects of the present disclosure also relate to other cutting machines such as core saws, for example.

[0003] Conventional stump cutters are well known. These machines commonly include a rotating cutter wheel driven by a prime mover (e.g., a gas or diesel engine). The cutter wheel, while rotating, is advanced toward the stump and moved laterally across the face of the stump in a horizontal sweeping movement to reduce the stump material by cutting and / or grinding. The cutter wheel is mounted to one end of a boom which is, in turn, pivotally mounted on a support frame. Hydraulic boom swing cylinders are used to pivot the boom about the pivot point to move the cutter wheel back and forth across the face of the stump to reduce it, layer-by-layer. Advancing the cutter wheel down toward the stump is accomplished by separate hydraulic tilt cylinders that cause the boom to tilt within a vertical plane.

[0004] Commercially available stump cutters often include manual sweeping operations in which an operator controls the speed and position of the cutter wheel. However, for hydraulic drive systems, it is often difficult for operators to determine when the system will stall due to increases in pressure resulting from resistance from the stump. Similarly, automated systems designed for gas or diesel engines are less effective at controlling hydraulic drive systems and accordingly may also cause the hydraulic system to stall. Thus, a need exists for a stump cutting system that may prevent the hydraulic system of a stump cutter from stalling during operation.Attorney Docket No. 489825-0019-W001SUMMARY

[0005] In one aspect, the invention provides a stump cutter including a hydraulic system with a hydraulic motor and a relief valve operable to open at a threshold pressure. The stump cutter also includes a cutter wheel connected to the hydraulic system and drivable by a flow of hydraulic fluid through the hydraulic motor and a pressure sensor configured to measure a pressure of hydraulic fluid supplied to the hydraulic motor to drive the cutter wheel. The stump cutter further includes a first actuator configured to move the cutter wheel for horizontally sweeping the cutter wheel with respect to a stump, and an electronic processor in communication with the pressure sensor and the first actuator. The electronic processor is configured to: initiate sweeping of the cutter wheel at a first speed via a drive signal for the first actuator based on a sweep input command, receive a signal from the pressure sensor indicative of the measured pressure of the hydraulic fluid during the sweeping operation using the pressure sensor, compare the measured pressure to a predetermined reference pressure that is less than the threshold pressure, calculate an adjusted sweep input command based on the comparison between the hydraulic pressure and the reference pressure, and upon determining that the adjusted sweep input command is less than the sweep input command, update the drive signal to the first actuator to automatically reduce sweeping of the cutter wheel to a second speed based on the adjusted sweep input command.

[0006] In another aspect, the invention provides a stump cutter including a cutter wheel, a boom supporting the cutter wheel for rotation, and a base portion supporting the boom for articulation using a first actuator configured to move the boom and thereby sweep the cutter wheel with respect to a stump. The stump cutter also includes a hydraulic system including the first actuator, a hydraulic motor, and a plurality of valves, and a pressure sensor configured to measure the pressure of a hydraulic fluid supplied to the hydraulic motor at the cutter wheel. The stump cutter further includes an electronic processor in communication with the pressure sensor and the first actuator. The electronic processor is configured to selectively enable rotation of the cutter wheel, initiate sweeping of the cutter wheel via a drive signal for the first actuator at a first speed based on a sweep input command, receive a pressure signal from the pressure sensor indicative of the pressure of the hydraulic fluid supplied to the hydraulic motor, calculate a second sweep input command based on the pressure signal, and upon determining that theAttorney Docket No. 489825-0019-W001 second sweep input command is lower than the sweep input command, update the drive signal to the first actuator to automatically reduce sweeping of the cutter wheel to a second speed based on the second sweep input command.

[0007] In another aspect, the invention provides a method for controlling a stump cutter with a cutter wheel supported for rotation on a boom, the method driving rotation of the cutter wheel by directing hydraulic fluid at a drive pressure to a hydraulic motor connected to the cutter wheel and initiate sweeping of the cutter wheel at a first speed via a drive signal for a first actuator based on a sweep input received by an electronic processor. Upon sweeping the cutter wheel, the electronic processor receives a signal from a pressure sensor that measures the drive pressure, and calculates an adjusted sweep input command based on the measured drive pressure from the pressure sensor. Upon determining that the adjusted sweep input command is less than the sweep input command, the drive signal to the first actuator is updated to automatically reduce sweeping of the cutter wheel to a second speed.

[0008] In another aspect, the invention provides a hydraulic rotary tool including a rotatable tool element operable on a work piece and a hydraulic motor operable to drive rotation of the rotatable tool element. A base portion supports the rotatable tool element for rotation and includes an actuator configured to move the rotatable tool element to penetrate the work piece. A pressure sensor configured to measure a pressure of hydraulic fluid supplied to the hydraulic motor or the actuator and output a pressure signal corresponding to the measured pressure and indicative of resistance to penetration of the work piece by the rotatable tool element. An electronic processor of the hydraulic rotary tool is in communication with the pressure sensor and the actuator, the electronic processor configured to: initiate movement of the rotatable tool element, via a drive signal to the actuator, at a first penetration intensity based on a first input command; following the drive signal to the actuator, monitor the pressure signal from the pressure sensor; calculate a second input command based on the pressure signal; and upon determining that the second input command is lower than the first input command, update the drive signal to the actuator to automatically reduce the first penetration intensity to a second penetration intensity based on the second input command.Attorney Docket No. 489825-0019-W001

[0009] In another aspect, the invention provides a core saw including a rotatable hollow cylindrical core saw bit, and a base portion supporting the hollow cylindrical core saw bit for rotation, the base portion further including a hydraulic cylinder configured to move the hollow cylindrical core saw bit to penetrate the ground. A pressure sensor is configured to measure a pressure of hydraulic fluid at the hydraulic cylinder and output a pressure signal corresponding to the measured pressure and indicative of resistance to penetration of the ground by the hollow cylindrical core saw bit. An electronic processor is in communication with the pressure sensor and the hydraulic cylinder. The electronic processor is configured to: initiate movement of the hollow cylindrical core saw bit, via a drive signal to the hydraulic cylinder, at a first penetration intensity based on a first input command; following the drive signal to the hydraulic cylinder, monitor the pressure signal from the pressure sensor; calculate a second input command based on the pressure signal; and upon determining that the second input command is lower than the first input command, update the drive signal to the hydraulic cylinder to automatically reduce the first penetration intensity to a second penetration intensity based on the second input command.

[0010] It should be understood that although certain drawings illustrate hardware and software located within particular devices, these depictions are for illustrative purposes only. Functionality described herein as being performed by one component may be performed by multiple components in a distributed manner. Likewise, functionality performed by multiple components may be consolidated and performed by a single component. In some constructions, the illustrated components may be combined or divided into separate software, firmware and / or hardware. For example, instead of being located within and performed by a single electronic processor, logic and processing may be distributed among multiple electronic processors. Regardless of how they are combined or divided, hardware and software components may be located on the same computing device or may be distributed among different computing devices connected by one or more networks or other suitable communication links. Similarly, a component described as performing particular functionality may also perform additional functionality not described herein. For example, a device or structure that is “configured” in a certain way is configured in at least that way but may also be configured in ways that are not explicitly listed.Attorney Docket No. 489825-0019-W001BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. 1 is a perspective view of a stump cutter according to a first construction of the present disclosure.

[0012] Fig. 2 is another perspective view of the stump cutter of Fig. 1, including a sweep cylinder.

[0013] Fig. 3 is a perspective view of a stump cutter according to a second construction of the present disclosure.

[0014] Fig. 4A is a schematic of the hydraulic control system of the stump cutter of Fig. 1.

[0015] Fig. 4B is another schematic of the hydraulic control system of the stump cutter ofFig. 1.

[0016] Fig. 5 is a schematic of the electronic control system of the stump cutter of Fig. 1.

[0017] Fig. 6 is an exemplary control method for operating the stump cutter of Fig. 1.

[0018] Fig. 7 is another exemplary control method of the present disclosure.

[0019] Fig. 8 is another exemplary control method of the present disclosure, including a buffering method for combining multiple control loops.

[0020] Fig. 9 is a graph illustrating the pressure of the stump cutter of Fig. 1 cutting a mulberry stump without using the control methods of the present disclosure.

[0021] Fig. 10 is a graph illustrating the pressure of the stump cutter of Fig. 1 cutting a mulberry stump using the control methods of the present disclosure.

[0022] Fig. 11 is a graph illustrating the pressure of the stump cutter of Fig. 1 cutting an ash stump without using the control methods of the present disclosure.

[0023] Fig. 12 is a graph illustrating the pressure of the stump cutter of Fig. 1 cutting an ash stump using the control methods of the present disclosure.Attorney Docket No. 489825-0019-W001

[0024] Fig. 13 is a perspective view of a core saw according to one construction of the present disclosure.

[0025] Fig. 14 is a detail view of a working end of the core saw of Fig. 13.

[0026] Fig. 15 is a view of the core saw of Fig. 13, wherein several components including the rotatable core saw bit are removed to reveal the vertical actuation cylinder.

[0027] Fig. 16 is a side elevation view of the core saw of Fig. 13.

[0028] Fig. 17 is an alternate side perspective view of the core saw of Fig. 13.

[0029] Fig. 18 is a schematic of the hydraulic control system of the core saw of Fig. 13

[0030] Fig. 19 is an exemplary control method of the present disclosure.

[0031] Fig. 20 is another exemplary control method of the present disclosure.

[0032] Fig. 21 is yet another exemplary control method of the present disclosure.DETAILED DESCRIPTION

[0033] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0034] Figs. 1 and 2 illustrate a stump cutter 100 for materially reducing tree stumps by cutting and / or grinding with a rotatable cutter wheel 102. The cutter wheel 102 can have a disc shape, as shown. A plurality of integral or removable cutters are provided on the cutter wheel 102 and configured to engage and reduce the stump during operation. Rotation of the cutter wheel 102 can be driven by a hydraulic drive motor 128 as described in further detail below. The illustrated cutter wheel 102 is configured for rotation about an axis that is horizontal. However, other cutter wheel configurations are optional, including discs that rotate about aAttorney Docket No. 489825-0019-W001 vertical axis, or drums rather than discs. The stump cutter 100 may include a base machine 104 and a stump cutter attachment 106 configured to rotate and move the cutter wheel 102. In the illustrated construction, the base machine 104 is configured to support and accordingly removably couple to various attachments beyond just the stump cutter attachment 106.

[0035] The base machine 104 may be a skid steer, tractor, compact tool carrier, or another vehicle configured to support various attachments, such as the stump cutter attachment 106. The base machine 104 further includes a ground drive system 108 including wheels and / or tracks configured to provide motive operation of the stump cutter 100 along a ground surface, and loader 112. Figs. 1 and 2 illustrate loader 112 having as two arms 110 and a mounting plate (not visible) pivotally attached to the arms 110. The mounting plate is configured to couple to and support the stump cutter attachment 106. The loader 112 may be operable to tilt and vertically adjust the position of the mounting plate, thereby moving the stump cutter attachment 106 coupled to the mounting plate. Fig. 3 illustrates a construction of stump cutter 100’ where the base machine 104 that does not include a loader 112 and the stump cutter attachment 106 may be directly secured to the base machine 104. In other constructions, additional or fewer mounting components may be used. Furthermore, both the base machine 104 and the stump cutter attachment 106 may include a hydraulic interface 111 configured to support the flow of fluid between the base machine 104 and the stump cutter attachment 106. At the hydraulic interface 111 or separately, an electrical interface is provided between the base machine 104 and the stump cutter attachment 106 (e.g., providing electrical power to the stump cutter attachment 106 from the base machine 104). Although the position of the stump cutter attachment 106 can be manipulated using the base machine 104 (e.g., through the ground drive system 108 and loader 112), the base machine 104 is typically used to position the cutting wheel 102 in an advantageous position to begin the sweeping and plunging portion of a stump cutting operation, then, after a series of sweep passes and plunges, the base machine may advance (creep forward) a short distance to position the cutting wheel for another series of cutter wheel sweeps and plunges, this process is repeated accordingly until the stump is adequately removed.Accordingly, the stump cutter attachment 106 is operable to manipulate movements of the cutter wheel 102 in multiple directions with respect to the base machine 104 of the stump cutter 100 and 100’ independent to the base machine 104. As described in further detail below, the cutterAttorney Docket No. 489825-0019-W001 wheel 102 can swing horizontally (“swing” or “sweep”) and can also tilt vertically (“plunge” and “lift”).

[0036] In order to provide the horizontal swing and vertical tilt capability for the cutter wheel 102, the stump cutter attachment 106 is configured to articulate the cutter wheel 102 independently with respect to the base machine 104. As previously mentioned, the construction illustrated in FIGS 1 and 2 shows the stump cutter attachment 106 coupled to the base machine 104 through a loader 112. More specifically, a base frame 114 of the stump cutter attachment 106 is removably coupled to the mounting plate attached to the arms 110 of the loader 112. Pivotally attached to base frame 114 is a subframe 116, which supports a boom 118. The boom 118 has a proximal end pivotally coupled to the subframe 116 and a distal end that rotatably supports the cutter wheel 102. As will be appreciated in the art, a powered mechanism is provided to manipulate the boom 118. The powered mechanism can include pivots and actuators, such as hydraulic cylinders. As illustrated in Fig. 1 by way of example, an actuator 120 for raising and lowering the cutter wheel 102 is provided as a hydraulic cylinder between the subframe 116 and the boom 118. The tilt cylinder 120 is configured to drive movement of the boom 118 about an axis A between an upper limit position and a lower limit position. The axis A is defined by a pivot and extends horizontally. As such, the tilt cylinder 120 can raise or lower the cutter wheel 102. Similarly, as illustrated in Fig. 2, an actuator 122 for swinging the cutter wheel 102 left and right, along a horizontal plane, is provided as a double-acting hydraulic sweep cylinder connected at a first end to the base frame 114 and connected at a second end to the subframe 116. The sweep cylinder 122 is configured to pivot the subframe 116 relative to base frame 114 and thereby move the boom 118 about a vertical axis B and along a sweep path S. The sweep path S, which is arcuate in the illustrated construction, resides in a horizontal plane. In other constructions, multiple sweep cylinders may be provided (e.g., two cylinders in tandem), which is also optional for the tilt cylinder 120. It will be appreciated that a variety of mechanisms, including those of various known configurations as well as those of configurations later developed, can be used within the context of the present disclosure. Various examples of stump cutter systems and configurations that may be incorporated in part or whole in the stump cutter 100 can be found in U.S. Patent 11,326,655 and U.S. Patent 11,612,114, the entire contents of both of which are incorporated by reference herein. The shape and type of the boom is also not limited to that shown.Attorney Docket No. 489825-0019-W001

[0037] The movements of the cutter wheel 102, as controlled by the tilt and sweep cylinders 120, 122, can be controlled from the controls of an operator interface or control panel 124. In some constructions, the control panel 124 is provided on the stump cutter 100 at a proximal or operator end, which is opposite a distal or cutting end. As will be appreciated, the control panel 124 can include physical controls (e.g., one or more joysticks, one or more buttons, etc.) and / or interactive electronic screen(s). Also, it will be appreciated that the control panel 124, or an additional control panel, can be provided on a remote electronic device, which may be a dedicated remote of the stump cutter 100, or a personal handheld electronic device. In any case, the movements of the cutter wheel 102 among other functions are implemented through an electronic and / or hydraulic control system in command of the actuators configured to move the cutter wheel 102 through articulation of the boom 118 and subframe 116. Movement of the cutter wheel 102 with respect to a stump may be accomplished in three-dimensional space by separate inputs from an operator to the control panel 124. In particular, the control panel 124 can include operator controls individually operable to control + / - sweep (which moves the cutter wheel 102 horizontally), and + / - plunge (which moves the cutter wheel 102 vertically). In the illustrated construction, the control panel 124 is a control panel associated with the attachment 106, rather than the base machine 104. The control panel 124 can be removably received on the base machine 104 (e.g., by magnets, latches, etc.). The control panel 124 can be supported at or adjacent a main control panel of the base machine 104. In other constructions, the control panel 124 disposed on the attachment 106 or another external location. As discussed in further detail below, in the illustrated embodiment the control panel 124 is only configured to control the stump cutter attachment 106. Accordingly, in some constructions, the stump cutter may further include a base machine control 126 operable to control + / - creep (which moves the entire stump cutter 100 via the ground drive system 108) or + / - tilt (which moves the stump cutter attachment 106 via the loader 112). The control panel 124 may also enable the operator to input a command to initiate an automated cutting cycle in which one or more movements without further operator command.

[0038] Fig. 4A is an exemplary schematic of a hydraulic circuit of the stump cutter 100 that illustrates the flow of pressurized fluid between the base machine 104 and the stump cutter attachment 106 along a plurality of fluid lines 130 for controlling movement of the cutter wheel 102. The pressurized fluid is produced within the base machine 104 by a hydraulic pump 132,Attorney Docket No. 489825-0019-W001 which is in turn powered by a power source 136 such as an engine or an electric motor. The pump 132 may draw fluid from a tank 140 disposed within the base machine 104. As discussed in further detail below, the stump cutter attachment 106 may control the rotation and movement of the cutter wheel 102 using the pressurized fluid produced by the base machine 104. Specifically, pressurized fluid powers the hydraulic drive motor 128 to drive rotation of the cutter wheel 102. The stump cutter attachment 106 also includes tilt and sweep cylinders 120, 122 to control the movement of the cutter wheel 102 relative to the base machine 104. The flow of fluid within the stump cutter attachment 106 is controlled, at least in part, by a plurality of valves 144 (e.g., implemented as individual valves with separate bodies or blocks, or as multiple cartridge valves in a manifold 148). Said another way, each of the drive motor 128, the tilt cylinder 120, and the sweep cylinder 122 may be selectively controlled using the valves 144 to direct fluid to and from different portions of the hydraulic circuit and thereby control the movement of the cutter wheel 102. The valves 144 also direct the flow of lower pressure fluid back towards the base machine 104. It will be appreciated that at least a portion of the plurality of valves 144 may additionally be adjustable between 0% (fully closed) and 100% (fully open) positions to proportionally vary the flow rate of hydraulic fluid passing through the valve. For example, to sweep the boom 118 at a partial speed (e.g., 50%), the sweep valves may be adjusted to a 50% (partially open) position.

[0039] In the illustrated constructions including the removable stump cutter attachment 106, the manifold 148 (including all the valves 144 controlling the rotation and movement operations of the cutter wheel 102) is provided as part of the stump cutter attachment 106. The manifold 148 can receive hydraulic fluid supplied from the base machine 104 at a working pressure configured to operate the stump cutter attachment 106. It will be understood that, during times of non-operation of the stump cutter attachment 106, hydraulic fluid can be supplied at a lower nominal pressure, or no hydraulic fluid can be supplied from the base machine 104 to the stump cutter attachment 106. The stump cutter attachment 106 may be provided without any means of generating a supply of pressurized hydraulic fluid. The base machine 104 can additionally have a variety of hydraulic functions and corresponding hydraulic consumers. The base machine 104 can be provided with an auxiliary hydraulic output configured to couple to and power hydraulic implements separate from but attached to the base machine 104, such as a hydraulicallyAttorney Docket No. 489825-0019-W001 controlled push blade 103 as shown in Fig. 3. As such, the manifold 148 selectively connects to the auxiliary output of the base machine 104.

[0040] Although aspects of the invention can be embodied in a stump cutter attachment 106 attachable to a multi-purpose base machine 104 to provide improved functionality, aspects of the disclosure may also be applied to stump cutters of other constructions. For example, Fig. 3 illustrates a standalone stump cutter 100’ in which the base machine 104 is manufactured as an integral unit operable exclusively and / or permanently as a stump cutter. Said another way, the stump cutter 100’ is not configured to support multiple attachments. The stump cutter 100’ is similar to the stump cutter 100 and includes similar components such as a cutter wheel 102, a boom 118, and actuators 120, 122 operable to move the cutter wheel 102 relative to a work piece during a cutting operation. Thus, reference is made to the description of the stump cutter 100 to avoid repetition. More specifically, the construction illustrated in Fig. 3 includes a stump cutter apparatus 106’ including a cutter wheel 102 and drive motor 128 attached to base machine 104, with no loader structure intervening between the base machine 104 and stump cutter apparatus 106’. For example, in the construction of Fig. 3 the boom 118 is comprised of a subframe 116 pivotally attached to the base machine 104 about a vertical axis B to allow a sweep path S of the cutter wheel 102 in a horizontal plane though actuation of a sweep cylinder 122. Continuing down the boom 118, the subframe 116 has a first end of linkages 119 pivotally attached about horizontal axis similar to axis A and a second end of linkages 119 pivotally attached to the cutter wheel support frame 121, which allow an actuator 120 (connected at a first end to the subframe 116 and at a second end to a linkage 119) to raise and lower cutter wheel 102. The illustrated stump cutter 100’ also includes a base machine control 126 operable to control a ground drive system 108 and operable to control the movements of the cutter wheel 102. The base machine control 126 can be a unified control system providing communication and centralized control of components separate from stump cutting operations (e.g., engine and engine-driven hydraulic pump) while also monitoring parameters and / or controlling any / all of the cutter wheel 102, the boom 118, and the hydraulic drive motor 128. Both stump cutter 100’ and stump cutter 100 are operable to laterally sweep a cutter wheel 102 across the face of the stump in a horizontal sweeping movement to reduce the stump material by cutting and / or grinding. Instead of the interface with an auxiliary hydraulic output, the standalone stump cutter 100’ provides direct hydraulic connections between the hydraulic system of the base machine 104 and the fluidAttorney Docket No. 489825-0019-W001 consumers (motor 128 and the cylinders 120, 122 for tilt and sweep) operable during stump cutting. Except where expressly precluded, the detailed disclosure of the stump cutter 100 and particularly its control system may apply equally to, or may be adapted to, the stump cutter 100’, among others not explicitly illustrated herein.

[0041] Returning to Fig. 4A, the hydraulic circuit may also include additional valves inside and / or outside the manifold 148 necessary to regulate the flow of fluid to and from the drive motor 128. For example, a valve may selectively control the engagement between the drive motor 128 and the cutter wheel 102. In some constructions, the hydraulic circuit may also be configured to regulate the flow of multiple types of fluid including water, coolant, and oil. In some constructions, the hydraulic circuit may include additional, fewer, or different components. For example, the base machine 104 may include additional hydraulic components operable to control and protect the drive system 108, the loader 112, other components of the base machine not disclosed, and / or other attachments that may require additional fluid inputs. In another example, the base machine 104 and / or the stump cutter attachment may include additional pressure sensors configured to determine an overall or average pressure of the entire hydraulic circuit. The hydraulic circuit may also include additional fluid lines 130 configured to direct fluid between components illustrated and / or not shown.

[0042] The hydraulic circuit further includes a relief valve 152 disposed near the drive motor 128 and at least one pressure sensor 154 disposed in the fluid path (e.g., in the pressure manifold 148) configured to monitor the pressure of the hydraulic circuit at the hydraulic drive motor 128. During cutting operations, the pressure within the hydraulic circuit near the drive motor 128 may increase due to the resistance of the stump. A cutting operation can be defined as an operation of the stump cutter 100 where the cutter wheel 102 is rotating and moved in a horizontal sweeping motion to reduce the stump material. In other words, the cutter wheel 102 penetrates the stump by moving through or across the stump. It will be appreciated that merely moving the cutter wheel 102 without removing stump material or otherwise encountering resistance may not affect the pressure within the hydraulic circuit. Similarly, increasing the sweep speed during a cutting operation represents an increased penetration intensity that causes the cutting wheel 102 to cut / grind material at a higher rate and accordingly encounter additional resistance or load. In a construction using two pressure sensors 154, a first sensor is configured to measure the drivingAttorney Docket No. 489825-0019-W001 pressure of the drive motor 128 (i.e., pressure of hydraulic fluid supplied to the drive motor 128) and a second sensor is configured to measure the back pressure of the hydraulic circuit (i.e., pressure of hydraulic fluid expelled from the drive motor 128). The back pressure sensor can be dedicated for each sub-circuit, or it can be shared for all sub-circuits. As such, the back pressure can be measured directly adjacent an outlet port of the drive motor 128 or further downstream, e.g., pressure of hydraulic fluid returned to the base machine 104. With the two sensors 154, the pressure drop across the drive motor 128, or “drive pressure,” is measured. Drive pressure is indicative of the resistance to the cutter wheel 102 performing work upon the stump, the drive pressure or the drive speed can be modified to optimize the work being performed by the rotary tool. The drive motor 128 is one example of a hydraulic actuator, the cutter wheel 102 is one example of a rotary tool, and the stump is one example of a workpiece acted upon by the rotary tool. Other alternatives using some of the same systems, components, and / or methodologies are also envisioned, some of which are directly addressed further below.

[0043] During some cutting operations, variations in the stump (e.g., knots, nails, etc.) may also cause additional resistance. When the fluid provided to the drive motor 128 reaches a certain threshold pressure, the relief valve 152 is configured to open, which relieves pressure and causes the drive motor 128 and the cutter wheel 102 to stall. The relief valve 152 is configured to protect the components of the stump cutter 100 within the hydraulic circuit and maintain machine stability. After stalling, the drive motor 128 and the cutter wheel 102 can restart once the cutting load is sufficiently reduced to drop the pressure below the threshold pressure. This may be done by the operator manually stopping and reversing the horizontal sweeping movement of the cutter wheel 102. As described below, aspects of the present disclosure greatly reduce or eliminate the instances of stalling during sweeping by selectively overriding (reducing) a sweep input command so that the cutting load and associated hydraulic pressure generally remains below the threshold pressure, particularly when the sweep input command (e.g., human operator’s command) corresponds to a sweep speed and cutting load that would otherwise trip the relief valve 152. Aside from overriding to maintain cutting load below the stall condition, the control system can allow the cutter wheel 102 sweep speed to be freely (dynamically) controlled by the operator’s sweep input command. Aspects of the hydraulic circuit illustrated in Fig. 4A are not limited to a stump cutter. For example, with attention to Fig. 4B, the stump cutter 100 is merely one example of a rotary tool 100b that can be driven at a drive pressure andAttorney Docket No. 489825-0019-W001 whose movement (e g., relative to a work piece) can be controlled through the control of one or more actuators 120 using a plurality of valves 144.

[0044] Fig. 5 illustrates an exemplary schematic diagram of the electronic control system for the stump cutter attachment 106. As discussed in further detail below, in the illustrated construction the electronic control system of the stump cutter attachment 106 is configured to receive power (e.g., hydraulic and / or electrical power) from the base machine 104 but does not communicate with the base machine 104. In other constructions, such as stump cutter 100’, the power supply and electronic control system of the stump cutter attachment 106 may be integrated into the base machine 104. The electronic control system includes an electronic processor 150 configured to control the operation of the hydraulic circuit. The electronic processor 150 includes combinations of hardware and software that are operable to, among other things, control and monitor the operation of the stump cutter 100. The electronic processor 150 is electrically and / or communicatively connected to the plurality of valves 144 to control fluid flow throughout the hydraulic circuit and thereby control movement the cutter wheel 102. The electronic processor 150 is also connected to the control panel 124, the pressure sensor 154, and other sensors 158 (e.g., flow sensors, temperature sensors, etc.) used to monitor the stump cutter attachment 106. The electronic processor 150 is powered by an energy source 162 such as a battery. The electronic processor 150 may be a microprocessor, a microcontroller, or another suitable programmable device. The electronic processor 150 may include a memory 160 and a control unit 164. The memory 160 is a non-transitory computer readable medium and includes, for example, a program storage area and a data storage area. The control unit 164 is configured to retrieve from the memory 160 and execute, among other things, software or instructions related to the control processes and methods described herein. In other constructions, the electronic processor 150 may include additional, fewer, or different components. For example, in constructions where the stump cutter is an attachment, the processor 150 may receive signals from the sensors disposed in the stump cutter attachment 106 and may only control the valves 144 disposed in the pressure manifold 148. Said another way, an attachment may not be able to communicate with the pump 132 or the power source 136 that supply the hydraulic fluid to the drive motor 128 for spinning the cutter wheel 102. In other constructions, the electronic processor 150 may be a main controller operable to control the speed of the power source 136, the drive system 108, and the cutter wheel 102.Attorney Docket No. 489825-0019-W001

[0045] In the prior art it is known to control the boom sweep speed in relation to a load detected on the engine. In constructions using a hydraulic drive circuit, engine load may not be an accurate indicator for the pressure at the drive motor as the engine load may not change as a result of a pressure change at the drive motor. Additionally, determining the cutting load by measuring the motor / engine torque may not work for attachment systems as different attachments may require different operating characteristics. As discussed in further detail below, it may be advantageous to control the cutting operation of a tool using a measured pressure.

[0046] Fig. 6 is an exemplary flow chart illustrating a control method 200 for automatically adjusting the sweep speed of a stump cutter 100 based on a measured pressure. At step 205, the electronic processor 150 is configured to drive rotation of the cutter wheel 102 by directing hydraulic fluid to a hydraulic motor connected to the cutter wheel. More specifically, the electronic processor 150 controls the valves 144 to selectively enable pressurized flow from the pump 132 to provide energy to the drive motor 128. In some constructions the electronic processor 150 may also determine whether the drive motor 128 is receiving pressurized fluid using the pressure sensor 156 and / or if the pressurized fluid is providing enough pressure to drive the cutter wheel 102. In response to determining that the drive motor 128 is not receiving pressurized fluid or the fluid is not providing enough pressure, the electronic processor 150 may return an error (e.g., through the control panel 124) as the cutter wheel 102 is not ready to cut a stump.

[0047] At step 210, the electronic processor 150 is configured to receive a sweep input command (hereinafter, “sweep input”) corresponding with the sweep speed of the cutter wheel 102. In some constructions the sweep input may be a manual control entered by an operator through the control panel 124. The sweep input may be a joystick, a button, a dial, a switch, a touchscreen input, or another device operable by a user. In other constructions the sweep input may be automatically determined by the electronic processor 150 using a preprogrammed algorithm such as an “smart sweep” program. In some constructions the sweep input may be received by the electronic processor 150 as a voltage, according to a prescribed map. For example, when an operator moves the joystick fully to the left, the electronic processor 150 may receive a first voltage. Similarly, when an operator moves the joystick fully to the right, the electronic processor 150 may receive a second voltage. No movement of the joystick may resultAttorney Docket No. 489825-0019-W001 in a third voltage (e.g., half-way between the first and second voltages) corresponding to a sweep input of zero. In constructions where sweep input is binary (e.g., a button to sweep left) the sweep input may only be used to indicate a sweep direction. In other constructions, the sweep input may include a magnitude. For examplejoystick positions between the unactuated position and both the full-left and full-right can further be mapped to additional voltages to the electronic processor 150, according to a prescribed scale (e.g., linear scale). It will be appreciated that the electronic processor 150 may receive a sweep input using other parameters than voltage known in the art including a percentage, current, contact setpoints, and / or data communication signals.

[0048] At step 215, the electronic processor 150 is configured to initiate sweeping of the cutter wheel 102 at a first speed via a drive signal for an actuator based on the sweep input. The drive signal may be an analog voltage, a binary logic signal, a digital input, or another type of signal known in the art. For example, in response to receiving a negative voltage, the electronic processor 150 may send a drive signal to control the valves 144 to provide hydraulic fluid flow to the sweep cylinder 122 and thereby cause the cutter wheel 102 to sweep towards the left. Similarly, when an operator moves the joystick towards the right, the electronic processor 150 may receive a positive voltage and the electronic processor 150 may send a drive signal to control the valves 144 to provide hydraulic fluid flow the sweep cylinder 122 and thereby cause the cutter wheel 102 to sweep to the right. A sweeping input of zero (e.g., 0V) may not cause the electronic processor 150 to send a drive signal. The magnitude of the drive signal (and thereby the sweep speed) may be proportional to the sweep input. For example, in response to receiving a sweep input of IV, the electronic processor 150 may provide a drive signal to the sweep valves to provide a fluid to the sweep cylinder 122 at a first flow rate. Upon receiving fluid at a first flow rate, the sweep cylinder 122 may sweep the cutter wheel 102 to the right at a first rate. Continuing the previous example, in response to receiving a sweep input of 0.5V, the electronic processor 150 may provide a drive signal to the sweep valves to provide fluid to the sweep cylinder 122 at a second, slower, flow rate. Because the sweep valves receive less flow, the resulting speed at which the cutter wheel 102 sweeps is also lower. Similarly, if the sweep input value was negative (e.g., -0.5V) the electronic processor 150 may provide a drive signal to the sweep valves such that the sweep cylinder 122 controls the cutter wheel 102 to sweep left. In some constructions, the valves 144 may provide hydraulic fluid flow to the rod end of the sweep cylinder 122 to sweep the cutter wheel 102 left and to the base end of the sweep cylinder 122 toAttorney Docket No. 489825-0019-W001 sweep the cutter wheel 102 right. In some constructions, the sweep input may only be used to indicate a sweep direction (e.g., a sweep input of left or right) or not to sweep (e.g., a sweep input of zero).

[0049] At step 220, upon sweeping the cutter wheel 102, the electronic processor 150 is configured to receive a measurement signal from a pressure sensor (e.g., pressure sensor 154) indicative of a pressure of the hydraulic fluid near (e.g., hydraulic line 145) the drive motor 128 and the relief valve 152. For example, the electronic processor 150 may receive a signal from the pressure sensor 154 disposed within the flow path between the pump 132 and the drive motor 128. The signal from the pressure sensor 154 may correspond to the drive pressure of the flow of fluid to and / or through the drive motor 128. The pressure signal is representative of the dynamic cutting load between the cutter wheel 102 and the stump. In some constructions, the pressure sensor 154 may be disposed adjacent to the relief valve 152. In some constructions, the electronic processor 150 may receive signals from a plurality of pressure sensors and may calculate a measured pressure based on a fdtered average of the plurality of pressure sensors. In some constructions, the electronic processor 150 may also determine whether the measured hydraulic pressure is greater than a reset pressure corresponding with the minimum pressure in the drive system 108 required to drive the cutter wheel 102. In response to determining that the hydraulic pressure is less than the reset pressure the electronic processor 150 may return an error and alert an operator. In some embodiments, the electronic processor 150 may be configured to receive a measurement signal from a pressure sensor continuously or at regular intervals, including whether the cutter wheel is rotating or not or whether the cutter wheel 102 is sweeping or not.

[0050] At step 225, the electronic processor 150 is configured to calculate an adjusted sweep input command (hereinafter, “adjusted sweep input”) based on the measured pressure of the cutter wheel hydraulic circuit. The adjusted sweep input is the drive input that correlates with one of the speeds the cutter wheel 102 can sweep without stalling. The target pressure is a predetermined pressure setpoint that may be lower than the relief pressure of the relief valve 152 to ensure that the relief pressure is not reached during cutting, thereby preventing a stall in rotation of cutter wheel 102. It will be appreciated that the target pressure provides a buffer such that even if the cutter wheel 102 undergoes unexpected resistance during a cutting operationAttorney Docket No. 489825-0019-W001 while sweeping at the adjusted sweep input, the buffer will allow for the pressure of the hydraulic circuit to further increase without causing the cutter wheel 102 to stall and for the electronic processor 150 to calculate a new adjusted sweep input. To calculate the adjusted sweep input, the electronic processor 150 calculates a difference between the measured pressure and a target pressure (hereinafter referred to as the “pressure error”) and determines an adjusted sweep input.

[0051] The pressure error is input into a control scheme configured to output the adjusted sweep input. In some constructions, the control scheme may be a closed loop control scheme such as a Proportional Integral Derivative (PID) control algorithm. The output of a PID control algorithm is the sum of three multiples: a multiple of an error and a P gain, a multiple of an integral of the error and an I gain, and a multiple of a derivative of the error and a D gain. Generally, the P gain influences how quickly the control loop adjusts the system to reach a target value, the I gain influences settling time and steady state behavior, and the D gain, or damping coefficient, influences the stability of the control loop and reduces the likelihood of or amount by which the control algorithm overshoots the target value. As discussed in further detail below, other constructions may additionally or alternatively utilize an open loop control scheme and / or another type of closed loop control scheme.

[0052] In the context of using a PID control algorithm with the calculated pressure error, the electronic processor 150 may implement any one of a P, I, D, PI, PD, ID, or a PID control algorithm to calculate the adjusted sweep output. In this disclosure, a PID control algorithm generically refers to any closed loop control algorithm using at least one proportional, integral, or derivative control such as a PD control loop. The gains of each of the proportional, integral, or derivative control portions may be referred to generally as control characteristics. Some control characteristics may have a larger effectiveness in determining an adjusted sweep input. For example, the I gain portion of a closed loop control scheme may have a minimal effect on the control algorithm. In contrast, because the target pressure of the control loop corresponds with a failure point (e.g., the relief pressure) it is important that any pressure overshoot is minimized. Therefore, a closed loop control scheme using a D gain may prevent the cutter wheel 102 from stalling during a sweeping operation.Attorney Docket No. 489825-0019-W001

[0053] In some constructions, more than one closed loop control scheme may be utilized. For example, the control algorithm may have different characteristic behaviors depending on whether the measured pressure is below or above the target pressure and may accordingly use one control scheme when the measured pressure is above the target pressure and may use another control scheme when the measured pressure is below the target pressure. In such a construction, a positive pressure error may establish that the measured pressure is greater than the target pressure, and conversely, a negative pressure error may establish that the measured pressure is below the target pressure. The electronic processor 150 may utilize one control scheme tuned for when the measured pressure is above the target pressure and another control scheme tuned for when the measured pressure is below the target pressure. For example, when the measured pressure is below the target pressure, the electronic processor 150 may utilize a PD control algorithm tuned to limit an overshoot of the target pressure. Specifically, the PD control algorithm may be tuned (e.g., with a proportionally large D gain) to prevent large spikes in pressure from overshooting the target pressure to the point of reaching the relief pressure and causing the stump cutter 100 to stall. Continuing the previous example, when the measured pressure is above the target pressure the electronic processor 150 may utilize a P control algorithm or a PD control algorithm tuned with a proportionally smaller D gain to quickly adjust the measured pressure below the target pressure. In some constructions, when the measured pressure is above the target pressure the electronic processor 150 may utilize a different PID algorithm tuned to stabilize the pressure of the hydraulic system above the target pressure but below the relief pressure.

[0054] In some constructions, the control scheme and / or the characteristics of the control scheme may also change according to sweep direction or actuator type. In constructions using PID control algorithms, the control scheme may use different P, I, and / or D gains for each sweep direction and / or actuator. For example, the sweep cylinder 122 may be a double acting hydraulic cylinder with a rod end and a base end that requires a larger volume of fluid to move at the base end. The electronic processor 150 may utilize one PID control algorithm for filling the base end of the sweep cylinder 122 and another PID control algorithm for filling the rod end of the sweep cylinder 122. Other adjustment methods or their equivalents are also known in the art such as multiplying the output of a PID control algorithm by an adjustment constant to account for the asymmetric behavior within the system. In the illustrated construction, each PID control loop isAttorney Docket No. 489825-0019-W001 tuned with predetermined gains. In other constructions the gains may be updated over time or automatically calculated. Alternatively, a lookup table could be utilized for the P, I, and D gain values based on the pressure error.

[0055] The output of the control scheme may be additionally processed to correspond with the adjusted sweep input. For example, the electronic processor 150 may communicate a percentage to the valves 144 representing a flow rate. Accordingly, the electronic processor 150 may calculate the adjusted sweep input by converting the output of the control scheme to a percentage or control voltage. The adjusted sweep input may also be compared to minimum and maximum limits to ensure the adjusted joystick command will fall within the operational parameters of sweep control logic. For example, the electronic processor 150 may adjust the adjusted sweep input to a maximum ceiling value such as 95% or 0.95V. The electronic processor 150 may also adjust the sweep input to a minimum floor value such as 0% to prevent the cutter wheel 102 from unexpectedly changing direction. In some constructions, the control method 200 cannot adjust the adjusted sweep input to a value greater than the sweep input. Said another way, the control method 200 may only adjust the sweep input when the adjusted sweep input is lower than the sweep input. In other constructions, such as an automatic sweeping program, the control method 200 may be adapted to output an adjusted sweep input greater than the sweep input.

[0056] At step 230, upon determining that the adjusted sweep input is less than the sweep input, the electronic processor 150 is configured to update the drive signal to the valve to sweep the cutter wheel at a second speed based on the adjusted sweep input. As previously discussed, the electronic processor 150 may send a drive signal to control the valves 144 to adjust the hydraulic fluid flow to the sweep cylinder 122 and cause the cutter wheel 102 to sweep based on the magnitude and direction of the adjusted sweep input. The control method 200 may run, for example, one hundred times a second, allowing for dynamic adjustment of the sweep speed of the cutter wheel without additional input from an operator.

[0057] Fig. 7 is another exemplary flow chart illustrating a control method 300 for automatically adjusting the sweep speed of a stump cutter 100 based on a measured pressure. The control method 300 includes similar operations to the control method 200 discussed in Fig.Attorney Docket No. 489825-0019-W0015. At step 305, the electronic processor 150 is configured to sweep the cutter wheel at a first speed based on a sweep input delivered through an electronic processor. Similar to step 215, the electronic processor 150 may control the valves 144 to control hydraulic fluid flow to the sweep cylinder 122 and thereby cause the cutter wheel 102 to sweep in a particular direction.

[0058] At step 310, upon sweeping the cutter wheel, a hydraulic pressure is measured using a pressure sensor. A signal corresponding to the measured pressure is sent to the electronic processor 150, similar to step 220 of the method 200. The pressure sensor 154 may be disposed within the flow path in the hydraulic circuit that drives the cutter wheel motor 128.

[0059] At step 315, the electronic processor 150 is configured to compare the hydraulic pressure to a predetermined reference pressure. In some constructions, the electronic processor 150 may determine a difference between the measured hydraulic pressure and a predetermined reference or target pressure. The difference may represent a pressure error and be used in a closed loop control system as described in method 200. In other constructions, instead of determining an analog difference value, the electronic processor 150 may determine a binary value corresponding with whether the hydraulic pressure is greater or less than the predetermined reference pressure.

[0060] At step 320, the electronic processor 150 is configured to calculate an adjusted sweep input based on the comparison between the hydraulic pressure and the reference pressure. In some constructions, the electronic processor 150 may use a closed loop control method such as a PID control algorithm to calculate an adjusted sweep input using the measured hydraulic pressure as described in method 200. In other constructions, the electronic processor 150 may use a lookup table to determine a sweep speed corresponding with the measured hydraulic pressure or automatically slow or stop the sweep speed upon determining that the measured hydraulic pressure is greater than the reference pressure. For example, in response to determining whether the hydraulic pressure is greater than a reference pressure, the lookup table may include an adjusted sweep input of 0 to prevent the stump cutter 100 from sweeping until the pressure is below the target pressure.

[0061] At step 325, upon determining that the adjusted sweep input is less than the sweep input, the electronic processor 150 is configured to sweep the cutter wheel at a second speedAttorney Docket No. 489825-0019-W001 based on the adjusted sweep input. Similar to step 230, the electronic processor 150 may control the valves 144 to drive the sweep cylinder 122 and cause the cutter wheel 102 to sweep based on the magnitude and direction of the adjusted sweep input.

[0062] Fig. 8 is another exemplary flow chart illustrating a control method 400 for creating a smooth transition between multiple control algorithms. The control method 400 may be run concurrently with any of the methods 200, 300 previously discussed. Additionally, the control method 400 may receive inputs from one of the control methods 200, 300 and / or send outputs such as an adjusted sweep input to the control methods 200, 300.

[0063] At step 405, the electronic processor 150 is configured to calculate an error based on the difference between a target pressure and a measured pressure. For example, the error may be calculated by subtracting the measured pressure from the target pressure.

[0064] At step 410, the electronic processor 150 is configured to calculate a first correction signal based on the error using a first control loop. For example, the first control loop may be a PID control algorithm tuned to output a correction signal configured to control the sweep speed of the cutter wheel 102 when the measured pressure is above the target pressure.

[0065] At step 415, the electronic processor 150 is configured to calculate a second correction signal based on the error using a second control loop. For example, the second control loop may be a PID control algorithm tuned to output a correction signal configured to control the sweep speed of the cutter wheel 102 when the measured pressure is below the target pressure.

[0066] At step 420, the electronic processor 150 is configured to calculate a weighted sum of the first correction signal and the second correction signal, wherein the weighting is based on the error. Instead of transitioning between the first correction signal and the second correction signal whenever the measured pressure crosses the target pressure, combining the first and second correction signals allows for a smoother transition between an above pressure condition and a below pressure condition. Each of the first correction signal and the second correction signal are given a weight, or proportion, based on the error. For example, when the measured pressure is at a minimum pressure below the target pressure, the control loop tuned for an above pressure condition should have less of an impact on the overall control loop. Accordingly, the electronicAttorney Docket No. 489825-0019-W001 processor 150 may multiply the first correction signal by a first weight and the second correction signal by a second, larger, weight, causing the weighted sum to primarily represent the second correction signal. When the measured pressure is equal to the target pressure, both the first control loop and the second control loop may have an equal weight. Accordingly, the control characteristics of the closed loop control scheme may be adjusted based on the error value. For example, in one construction the weight may be determined using an inverted percentage. Specifically, the electronic processor 150 may calculate a first weight by converting the error into a percentage, such as 0.25 for 25%, then multiply the first control loop by the reciprocal of the percentage, such as 4. In another construction, the weights of the weighted sum may be limited between 0 and 1 such that the sum of the weights is equal to 1. For example, when the measured pressure is at a minimum pressure below the target pressure value, the electronic processor 150 may multiply the first control signal by 0.1 and the second control number by 0.9. When the measured pressure is equal to the target pressure, the electronic processor 150 may multiply both the first correction signal and the second correction signal by 0.5 causing the weighted sum to represent an average between first and second correction signals.

[0067] At step 425, the electronic processor 150 is configured to calculate an adjusted sweep input based on the weighted sum. For example, the weighted sum may be converted to a percentage or reference voltage as discussed in step 225. Also similar to step 225, the adjust sweep input calculated at step 425 may be used by the electronic processor 150 to control the sweep speed of the cutter wheel 102.

[0068] Figs. 9-12 contain graphs illustrating experimental data taken during a stump cutting operation of a stump cutter 100 over time. Figs 9-12 include pressure graphs 500a-500d including respective plots 505a-505d of the measured pressure within the cutter wheel hydraulic circuit over time and sweep input graphs 600a-600d including respective plots 605a-605d of the sweep input, received from an operator. The illustrated pressure graphs 5OOa-5OOd represent pressure in kilopascals (kPa) in the Y axis and time in seconds in the X axis. The input graph 600a-600d illustrate a user input in terms of a data communication signal ranging between - 10,000 to 10,000 (corresponding to -100.00% and +100.00%) in the Y axis and time in seconds in the X axis. Eacj pressure graph 500a-500d also includes a relief pressure 507, a pressure setpoint value 510 and a reset pressure value 515. Pressure values illustrated are for exemplaryAttorney Docket No. 489825-0019-W001 purposes and may vary depending on the stump cutter used. For example, in the exemplary graphs 500a-500d, the pressure setpoint value is 15,000kPa and the reset pressure value 515 is 10,000kPa. In the illustrated construction, the pressure setpoint value corresponds to the target pressure described in the methods 200, 300, 400. The reset pressure may be used by the electronic processor for certain control features such as a minimum starting pressure before the hydraulic motor 128 engages the cutter wheel 102. In some constructions, the reset pressure is used as a setpoint to begin or restart the calculation of the integral and / or derivative of the measured pressure error used in the PID control loop. The reset pressure may correspond with the free spinning pressure of the cutter wheel 102 and accordingly is an indicator that the stump cutter 100 is not currently cutting a stump. In some constructions, the electronic processor 150 may additionally disable the adjusted sweep control methods of 200, 300, 400 when measured pressure is below the reset pressure. The sweep input graphs 600a-600d range between a full speed to the right command 610 (e.g., 100%), a no movement command 620 (e.g., 0%), and a full speed to the left command 630 (e.g., -100%). The data communication signals illustrated are for exemplary purposes and may vary depending on the control system used.

[0069] Fig. 9 contains two graphs 500a and 600a illustrating experimental data taken during a stump cutting operation of the stump cutter 100 on a mulberry tree stump without using the methods described in Figs. 6-8. As shown at regions 520 of plot 505a, the free spinning hydraulic pressure within the cutter wheel hydraulic circuit is relatively low compared to the hydraulic pressure when the cutter wheel 102 is engaged with the stump and may be about, for example, 10,000kPa or less. The free spinning pressure of the cutting wheel 102 is near the reset pressure value 515. The free spinning pressure of the cutting wheel 102 corresponds to when the cutter wheel 102 is rotating but has not contacted the stump, including: during startup of the cutter wheel, when the cutter wheel has swept beyond the edge of stump at the end of sweep pass, at the beginning of sweep pass when the cutter wheel has not yet contacted the stump, when sweep movement is halted, or during a change in sweep direction. As shown at points 525, the pressure may reach the relief pressure 507 and, as a result of the relief valve activating and the cutter wheel 102 stalling, the cutter wheel hydraulic circuit pressure plateaus around 18,600kPa. In some constructions, the hydraulic relief valve 152 may begin to leak around 15,000kPa. As a nonlimiting example of stump cutter 100 operation without the methods described in Figs. 6-8, starting between 75 and 80 seconds, plot 605a of graph 600a illustrates aAttorney Docket No. 489825-0019-W001 user inputting a sweep command from the maximum speed to the left to a maximum speed to the right. As illustrated in the graph 500a, the change in movement begins a cutting operation where the pressure in the hydraulic circuit increases and eventually trips the relief valve 152 to stall the cutter wheel 102. Due to the stall, the operator responds by reducing and then reversing the sweep command, which allows the cutter wheel to be unloaded and return to free speed. At about 87 seconds the operator again commands maximum sweep of the cutter wheel 102 to the left until around 90 seconds when the pressure again rises sufficiently to trigger the relief valve 152 and stall the cutter wheel 102.

[0070] Fig. 10 contains two graphs 500b and 600b illustrating experimental data taken during a cutting operation of the stump cutter 100 on a mulberry tree stump. The graphs 500b, 600b are similar to those of Fig. 9, but Fig. 10 illustrates the effects of using the methods described in Figs. 6-8. The graph 600b further includes a dotted line 615b representing the adjusted sweep value. Using the adjusted sweep value, the measured pressure does not reach the stall pressure. As a nonlimiting example of stump cutter 100 operation using the methods described in Figs. 6-8, starting around 145 seconds an operator controls the stump cutter 100 not to sweep allowing the cutter wheel 102 to free spin. Then, at approximately 150 seconds the operator gradually increases the sweep command to the right to a maximum value. As illustrated, the adjusted sweep value (line 615b) varies greatly between a no sweep value and the sweep command, allowing the measured pressure 505b to fluctuate around the pressure setpoint value 510. After 160 seconds, the operator moves the sweep input from maximum right to the maximum left. Again, the adjusted sweep value 615b selectively overrides the maximum left input so that the pressure 505b fluctuates around the pressure setpoint value 510 and avoids reaching the stall pressure, as the full sweep is completed. In contrast to the graphs 500a, 600a, the cutting operation does not cause the cutter wheel 102 to stall. Accordingly, it will be appreciated that the methods described in Figs. 6-8 increase the effectiveness and efficiency of cutting operations by allowing the stump cutter 100 to cut with a sweep command up to the operators input without stalling.

[0071] Fig. 11 contains two graphs 500c and 600c illustrating experimental data taken during a cutting operation of the stump cutter 100 on an ash tree without using the methods described in Figs. 6-8. Ash wood is much harder than mulberry, and accordingly may result inAttorney Docket No. 489825-0019-W001 the measured pressure to quickly reach the pressure at which the drive motor 128 stalls. As a nonlimiting example, at around 60 seconds an operator controls the cutter wheel 102 to sweep to the left as fast as possible, and the pressure climbs from the free-spinning pressure to the stall pressure very quickly. Between 62 to 66 seconds the operator then controls the cutter wheel 102 to reverse the sweep direction (maximum command to the right) to reset the cutter wheel pressure. Once the pressure drops, the operator again applies the maximum left sweep input as they reattempt to cut the stump.

[0072] Fig. 12 contains two graphs 500d and 600d illustrating experimental data taken during a cutting operation of the stump cutter 100 on an ash tree using the methods described in Figs. 6-8. The graph 600d also includes a dotted line 615d representing the adjusted sweep value. As a nonlimiting example, starting from around 55 seconds an operator command the cutter wheel 102 to sweep as fast as possible to the right. The adjusted sweep value 615d selectively overrides the maximum right input so that the pressure 505d fluctuates around the pressure setpoint value 510 and avoids reaching the stall pressure, as the full sweep is completed. The sweep input is then set to maximum left around 62 seconds, and the adjusted sweep value 615d again selectively overrides the maximum input to limit pressure and allow completion of the sweep. The sequence continues multiple times. In contrast to the graphs 500c and 600c, graphs 500d and 600d illustrate that the stump cutter 100 stalling despite using similar operator commands. Accordingly, it will be appreciated that the methods described in Figs. 5-7 are effective for multiple types of wood and a variety of use situations. As previously discussed, the control characteristics of the methods described in Figs. 5-7 may be additionally adjusted based on the measured error or another factor such as the type of wood or ambient temperature.

[0073] It will be appreciated that the discussed control methods 200, 300, 400 may be incorporated entirely or in part in other control systems and using the rotary attachment of the stump cutter wheel 202 or other rotary attachments powered by hydraulics. For example, alternate rotary attachments can include core saws with a hydraulically powered rotating saw, augers with a hydraulically powered rotating auger, trenchers with a rotating shaft for driving a trenching chain, root cutters with a rotating cutting wheel, rotary brooms with a hydraulically powered rotating broom, soil tillers having rotating tillage tool, and others. Many of these areAttorney Docket No. 489825-0019-W001 examples of cutting machines in which the penetration intensity against or through a work piece can be selectively controlled on the basis of measured pressure.

[0074] Figs. 13 to 17 illustrate a core saw 700 for cutting a core in a pavement surface with a rotatable core saw bit 702. The core saw bit 702 is a rotary tool element having a hollow cylindrical shape with a plurality of saw teeth provided at the bottom end thereof. When operated on the pavement surface, the core saw bit 702 cuts a circular hole to a desired depth.Cutting through a layer of pavement produces a cylindrical core that can be removed to access an area beneath the pavement (e.g., one or more utility lines). As illustrated, the core saw 700 includes a core saw attachment 706 and a base machine 104 (e.g., the same as shown in Figs. 1 and 2 of the stump cutter 100). The base machine 104 may be a skid steer, tractor, compact tool carrier, or another vehicle configured to support various attachments, such as the core saw attachment 706. The base machine’s loader 112 has two arms 110 and a mounting plate 113 pivotally attached to the arms 110. The mounting plate 113 is configured to couple to and support various attachments (e.g., the stump cutter attachment 106 and the core saw attachment 706, among others) that are carried by and powered by the base machine 104. The hydraulic interface I l l is configured to support the flow of working hydraulic fluid between the base machine 104 and the core saw attachment 706. Due to the nature of the core saw attachment 706 being a removable attachment and not an integral portion of the base machine 104, the electronic control system of the core saw attachment 706 may be configured with no signal communication with the base machine 104 (e.g., independent CAN bus networks). In some constructions, the core saw attachment 706 can only receive control inputs (like the stump cutter attachment 106) but otherwise does not communicate with the base machine 104. Although not separately illustrated, it is noted that the features of the core saw attachment 706 can be provided in a standalone core saw tool, rather than a removable attachment for the base machine 104.

[0075] Rotation of the core saw bit 702 can be driven by a hydraulic drive motor 728. The core saw 700 works by pressing the rotating core saw bit 702 in a working direction with an actuator 722. The illustrated core saw bit 702 is configured for rotation about an axis that is vertical, and the actuator 722 operates to apply downforce that advances the core saw bit 702 downward in the working direction to gradually penetrate the pavement surface. The drive motor 728 and the core saw bit 702 are movably supported on a base frame 714 of the core sawAttorney Docket No. 489825-0019-W001 attachment 706. The base frame 714 can extend to and rest on the ground during use. The base frame 714 can include or support a cover or shield 715 (removed in Figs. 13-15) that at least partially encloses the core saw bit 702. The base frame 714 can further include an upstanding mast or tower 714A that provides a vertical track. A subframe 716 is guided for movement along the vertical track of the tower 714A. The drive motor 728 and the core saw bit 702 are mounted to the subframe 716 to render them movable (vertically) relative to the base frame 714 by actuation of the actuator 722.

[0076] In the illustrated construction, the actuator 722 is a hydraulic cylinder including an extendable and retractable rod 722A (Fig. 15). The rod 722A moves in response to a pressure differential between two hydraulic fluid ports 725A, 725B that are in fluid communication with opposite sides of a piston connected to the captive end of the rod 722A (i .e., a base end port 725 A and a rod end port 725B). An operator input (joystick) of an operator interface or control panel 724 can control one or more valves 744 that selectively apply hydraulic fluid pressure (from the base machine 104) to one of the ports 725 A, 725B and allow hydraulic fluid drained from the other port 725A, 725B to return to tank (in the base machine 104). Turning to Fig. 17, the core saw 700 can include a lubrication and / or cooling system to supply lubricant or cooling liquid (e.g., water or water-based solution) to the core saw bit 702. The lubrication and / or cooling system can include pump(s), hose(s), nozzle(s), and a liquid tank 727.

[0077] The flow of hydraulic fluid within the core saw attachment 706 is controlled, at least in part, by a plurality of valves 744 (e.g., implemented as individual valves with separate bodies or blocks, or as multiple cartridge valves in a manifold 748 as shown in Fig. 18). Said another way, each of the drive motor 728 and the hydraulic cylinder 722 may be selectively controlled using the valves 744 to direct fluid to and from different portions of the hydraulic circuit and thereby control the movement of the core saw bit 702. The valves 744 also direct the flow of lower pressure fluid back towards the base machine 104. It will be appreciated that at least a portion of the plurality of valves 744 may additionally be adjustable between 0% (fully closed) and 100% (fully open) positions to proportionally vary the pressure of hydraulic fluid passing through the valve. For example, to force the core saw bit 702 down with a partial downforce (e.g., 50%), the downforce valves may be adjusted to a 50% (partially open) position.Attomey Docket No. 489825-0019-W001

[0078] In the illustrated constructions including the removable core saw attachment 706, the manifold 748 (including all the valves 744 controlling the rotation and movement operations of the core saw bit 702) is provided as part of the core saw attachment 706. The manifold 748 can receive hydraulic fluid supplied from the base machine 104 at a working pressure configured to operate the core saw attachment 706. It will be understood that, during times of non-operation of the core saw attachment 706, hydraulic fluid can be supplied at a lower nominal pressure, or no hydraulic fluid can be supplied from the base machine 104 to the core saw attachment 706. The core saw attachment 706 may be provided without any means of generating a supply of pressurized hydraulic fluid. The base machine 104 can additionally have a variety of hydraulic functions and corresponding hydraulic consumers. The base machine 104 can be provided with an auxiliary hydraulic output configured to couple to and power hydraulic implements separate from but attached to the base machine 104, such as a hydraulically controlled push blade 103 as shown in Fig. 3. As such, the manifold 748 selectively connects to the auxiliary output of the base machine 104.

[0079] Before operating the core saw 700, the base machine 104 may be moved to set the desired position for coring the pavement. The base machine 104 then remains stationary as the operator utilizes the core saw attachment 706 to energize the core saw bit 702 and control the downward drive of the core saw bit 702. Aside from the base machine 104 acting to provide the power (flow of pressurized hydraulic fluid created from the power source 136), the functions of the core saw attachment 706 can be controlled independently of the base machine 104. As such, the control panel 724 can be a dedicated control panel of core saw attachment 706, similar to the control panel 124 of the stump cutter 100. Further constructions may use the controls of the base machine 104 to control the attachment 706, obviating the dedicated control panel 724. Unlike the stump cutter control panel 124, the control panel 724 of the core saw 700 can be provided at a distal end of the core saw 700, generally opposite a proximal end having the control panel for operating the base machine 104. In other constructions, the control panel 724 is located elsewhere on the core saw 700 or remote. The control panel 724 communicates with an electronic processor 750 (Fig. 15) that forms an electronic control system that communicates with and controls a hydraulic control system described in further detail below. The control panel 724 can include a switch to power on the core saw attachment 706, and a separate switch to start / stop the drive motor 728. The switch for starting / stopping the drive motor 728 can be a 3-Attorney Docket No. 489825-0019-W001 way switch for stop / start / reverse. The control panel 724 can further include an adjustable operator input, such as a multi-position switch or a dial with infinite adjustability within a prescribed range, operable to control the rotation speed of the drive motor 728. The control panel 724 can further include an operator input (e.g., joystick 729) to control the downforce. The control panel 724 can further include a display.

[0080] In some constructions, operation of the drive motor 728 and downforce control can be integrated into a single operator input (e.g., the joystick 729). The control system can be configured so that, in response to the joystick 729 being moved out of the center position (either up or down) the drive motor 728 automatically rotates the core saw bit 702. As such, the core saw 700 may be provided without a dedicated bit rotation control (i.e., no separate button, switch etc. to selectively turn the drive motor 728 ON / OFF). The core saw bit 702 may continue to rotate when the hydraulic cylinder 722 changes directions (from extending to retracting or vice versa). When the hydraulic cylinder 722 changes direction, the core saw bit 702 may momentarily stop rotating, or in some configurations, a delay may be included in the control system such that core saw bit does not stop until the joystick 729 remains in the centered position for a predetermined period of time. Due to the rotation stop delay, the core saw bit 702 may not stop rotation when the joystick 729 is moved from one actuation direction to the other, despite momentarily passing through the center position.

[0081] The control systems can be similar in many respects to those of the stump cutter 100, including the electronic processor 150 of the stump cutter 100. In general, the electronic processor 750 operates to automatically and selectively reduce the penetration intensity on the basis of a measured parameter during action on the work piece. The penetration intensity, which is the downforce applied by the actuator 722, can initially be input or commanded by a human operator. Alternately, the initial downforce is set as part of an automated cutting cycle that operates without continued operator commands. Conventional machines may rely on an experienced operator to “feather” the input to appropriately manage the downforce on the core saw bit 702. The operator manually mitigates situations where too little downforce is applied (resulting in little or no cutting action) or too much downforce is applied (resulting in bucking, chattering, stalling, or unintended lifting / tilting of the core saw 700 with respect to the ground). The control system disclosed herein eliminates this requirement for active feathering by anAttorney Docket No. 489825-0019-W001 experienced operator and allows the penetration intensity to be kept at or near a target value. The target value may correspond to penetration intensity that produces maximum productivity.

[0082] Cutting performance for the core saw bit 702 may be highly dependent on maintaining a prescribed rotation speed from the drive motor 728. As such, there may be an optimal rotation speed for the core saw bit 702 on a particular pavement surface. The electronic processor 150 or a separate dedicated control system may operate to maintain the prescribed operating speed of the drive motor 728 and the core saw bit 702. The prescribed operating speed may vary for different cutting setups - an alternate core saw bit having a different size and / or different teeth and / or a different pavement surface. The prescribed operating speed can be input via the control panel 724, or preprogramed. Likewise, the control panel 724 may be configured to receive an operator input for a target penetration intensity.

[0083] Without repeating duplicative description of the stump cutter 100, it should be appreciated that the core saw 700 may be operated according to a control method that is functionally similar to the sweep speed control of the stump cutter 100. Specific reference is made to the control methods of Figs. 6-8. Instead of the control system managing sweep speed in response to the measured pressure at the motor 128, the core saw 700 is controlled to automatically control the downforce applied by the actuator 722 in response to pressure measured by a pressure sensor at the drive motor 728. However, similar PID control principles and gain factors can be employed. The control system can operate on the basis of a target pressure and may allow the operator’s input to directly control the downforce when below the target pressure. At or approaching the target pressure at the drive motor 728, the control system operates to override or replace the input to a lower setting that allows operation at or below the target pressure. In practice, this allows an operator to set and hold the input at full or maximum, and the control system will automatically apply the maximum allowable downforce with respect to the target drive motor pressure. In other words, the penetration intensity is automatically managed by the control system, and highly skilled operator input need not be provided to keep the intensity at an optimum range or setting.

[0084] As described above, the control system provides an indirect control scheme for controlling the penetration intensity because the downforce from the actuator 722 is set on theAttorney Docket No. 489825-0019-W001 basis of the fluid pressure measured at the drive motor 728. Pressure at the drive motor 728 may act as a suitable surrogate parameter for the actual downforce, since drive motor pressure may measurably increase when the applied downforce becomes excessive. In another embodiment, penetration intensity is controlled directly in response to pressure(s) measured at the actuator 722 rather than using pressure at the drive motor 728 as a surrogate or indirect indicator.

[0085] In particular, as indicated in Fig. 18, there may be pressure sensors 755 provided and configured to measure fluid pressure at both of the ports 725A, 725B of the cylinder 722. One pressure sensor 755 is configured to measure fluid actuation pressure, in other words the pressure on the side to which fluid is being actively directed. The other pressure sensor 755 is configured to measure fluid back pressure, in other words the residual pressure of fluid leaving the cylinder 722 (and routed back to the base machine 104). Back pressure may vary for a variety of reasons, including the function or operability of other hydraulic components within the overall hydraulic system of the core saw 700. By measuring pressure at both ports 725A, 725B, the electronic processor 750 can determine the acting pressure difference (AP) across the cylinder” to determine the net effective pressure that produces downforce on the core saw bit 702.Fig. 19 schematically depicts a control method 800 for controlling the core saw 700. Whether or not explicitly stated, the steps of the control method 800 can all be carried out by the electronic processor 750, alone or in conjunction with the devices (e.g., valves 744, pressure sensors 755, control panel 724) connected therewith. In the control method 800, at step 805, rotation of the core saw bit 702 is driven by directing hydraulic fluid to the drive motor 728. At step 810, an input for downforce pressure on the core saw bit 702 is received (e.g., from the operator via the control panel 724). At step 815, downforce pressure on the core saw bit 702 is initiated at a first actuator pressure via a drive signal for the cylinder 722 based on the input received at step 810. This may be achieved via control of the valves 744. At step 820, upon applying the downforce to the core saw bit 702, signals are received from the pressure sensors 755 at both ports 725A, 725B of the cylinder 722. From the measured pressures, the electronic processor 750 calculates the pressure difference (AP) to determine the actual amount of fluid pressure being converted into downforce on the core saw bit 702. A similar methodology can be used in the context of any / all of the hydraulic actuators of the stump cutter 100. In such a construction of the stump cutter 100, penetration intensity is controlled directly in response toAttorney Docket No. 489825-0019-W001 pressure(s) measured at the actuator(s) 120, 122 rather than using pressure at the drive motor 128. For this purpose, there may be pressure sensors provided and configured to measure fluid pressure at both of the ports of the cylinder 120 and / or at both of the ports of the cylinder 122. The pressure sensors are configured to measure fluid actuation pressure and fluid back pressure, respectively, so that the electronic processor 150 can determine the acting pressure difference (AP) across the cylinder to determine the net effective pressure (to selectively reduce the sweep speed).

[0086] At step 825, an adjusted downforce pressure input is calculated based on AP and a preset reference or target value. At step 830, upon determining that the adjusted downforce pressure input is less than the input, the drive signal to the cylinder 722 (via the valves 744) is updated to automatically reduce pressure to the cylinder 722 to a second pressure. It is noted here that the control method 800 may explicitly ignore a difference at step 825 where the adjusted downforce pressure input is greater than the input so that the machine will not increase the downforce pressure beyond what the operator is inputting at a given time. The control method 800 may operate with the only automatic adjustment being automatic reduction of downforce pressure, and only selectively in relation to nearing or exceeding the target. The electronic processor 750 may use a single PID loop for the control method 800. Alternately, it is possible to use multiple PID loops, as per the disclosure of the stump cutter 100. Such PID loop(s) can operate to avoid surpassing the target and / or control the rate at which the downforce pressure approaches the target.

[0087] The downforce pressure input of step 810 can be provided in terms of pressure at the cylinder 722 or in terms of a force value, which correlates to cylinder pressure based on the mechanical arrangement. In other constructions, the input can be provided in terms of an arbitrary scale (e.g., 1-10) that correlates to downforce on the core saw bit 702. Similarly, the target value and the calculations of the electronic processor 750 can be in terms of pressure at or across the cylinder 722, or representative numerical values that correspond to the pressure.

[0088] Given in a broadened or simplified context, the control method 900 of Fig. 20 may provide similar performance. Whether or not explicitly stated, the steps of the control method 900 can all be carried out by the electronic processor 750, alone or in conjunction with theAttorney Docket No. 489825-0019-W001 devices (e ., valves 744, pressure sensors 755, control panel 724) connected therewith. At step 905, downforce is applied to the core saw bit 702 at a first penetration intensity based on an input. At step 910, one or more parameters representative of the penetration intensity is / are measured. At step 915, the measured parameter(s) is compared to a predetermined reference value. At step 920, an adjusted penetration intensity is calculated based on the comparison. At step 925, the penetration intensity input is reduced to the adjusted penetration intensity input if it is determined that the adjusted penetration intensity input is less than the penetration intensity input. The electronic processor 750 may use a single PID loop for the control method 900. Alternately, it is possible to use multiple PID loops, as per the disclosure of the stump cutter 100.

[0089] Given in a further broadened or simplified context, the control method 1000 of Fig. 21 may provide similar performance. Whether or not explicitly stated, the steps of the control method 900 can all be carried out by the electronic processor 750, alone or in conjunction with the devices (e.g., valves 744, pressure sensors 755, control panel 724) connected therewith. At step 1005, current penetration intensity is measured and / or calculated. At step 1010, an error is calculated based on the difference between current penetration intensity and a preset target. At step 1015, an adjusted penetration intensity input signal is calculated and applied to an actuator based on the error using a control loop. The electronic processor 750 may use a single PID loop for the control method 1000. Alternately, it is possible to use multiple PID loops, as per the disclosure of the stump cutter 100.

[0090] In some constructions, the PID control loop of the electronic processor 750 for the core saw 700 can use primarily the proportional (P) and integral (I) portions of PID controls. In some constructions, the control loop may use none of the derivative (D) portion of the PID controls.

[0091] Although not limiting to the scope of the disclosure, an exemplary operating range for downforce pressure (of the actuating cylinder 722) on a core saw bit 702 of 12 inches cutting concrete can be 50 psi (starting) to 700 psi (max). In some constructions, the normal operating range may be from 400 psi to 600 psi. In some constructions, the maximum setting of the pressure can be nearly equivalent to the system relief, for example, 2500 psi.Attorney Docket No. 489825-0019-W001

[0092] Although the invention has been described in detail with reference to certain embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described. For example, it will be appreciated that the control system could be used in any system where speed control and / or pressure control affects the operating pressure of a hydraulic circuit.

Claims

Attorney Docket No. 489825-0019-W001CLAIMSWhat is claimed is:

1. A stump cutter comprising: a hydraulic system including a hydraulic motor and a relief valve, the relief valve operable to open at a threshold pressure; a cutter wheel connected to the hydraulic system, the cutter wheel drivable by a flow of hydraulic fluid through the hydraulic motor; a pressure sensor configured to measure a pressure of hydraulic fluid supplied to the hydraulic motor to drive the cutter wheel; a first actuator configured to move the cutter wheel for horizontally sweeping the cutter wheel with respect to a stump; and an electronic processor in communication with the pressure sensor and the first actuator, the electronic processor configured to: initiate sweeping of the cutter wheel at a first speed via a drive signal for the first actuator based on a sweep input command, receive a signal from the pressure sensor indicative of the measured pressure of the hydraulic fluid during the sweeping operation using the pressure sensor, compare the measured pressure to a predetermined reference pressure that is less than the threshold pressure, calculate an adjusted sweep input command based on the comparison of the measured pressure to the predetermined reference pressure, and upon determining that the adjusted sweep input command is less than the sweep input command, update the drive signal to the first actuator to automatically reduce sweeping of the cutter wheel to a second speed based on the adjusted sweep input command.

2. The stump cutter of claim 1, wherein the adjusted sweep input command is calculated using a first closed loop control scheme and a difference between the reference pressure and the measured pressure.Attorney Docket No. 489825-0019-W0013. The stump cutter of claim 2, wherein the calculation of the adjusted sweep input command further includes calculating the adjusted sweep input command using a second closed loop control scheme upon determining that the measured pressure is greater than the reference pressure.

4. The stump cutter of claim 2, wherein the first closed loop control scheme is a proportional derivative (PD) control scheme.

5. The stump cutter of claim 2, wherein control characteristics of the first closed loop control scheme are adjustable based on a difference between the measured pressure and the reference pressure.

6. The stump cutter of claim 5, wherein the control characteristics of the first closed loop control scheme are determined using a lookup table.

7. The stump cutter of claim 1, wherein the stump cutter is a stump cutter attachment having a mechanical connection interface and a hydraulic connection interface for a configurable work machine.

8. The stump cutter of claim 1, wherein the first actuator is a double acting hydraulic cylinder with a rod end and a base end, and the adjusted sweep command is a first adjusted sweep command in response to detecting the cutter wheel is sweeping a first direction, and wherein the electronic processor calculates a second adjusted sweep command, different than the first adjusted sweep command, in response to detecting the cutter wheel is sweeping in a second direction opposite the first direction.

9. The stump cutter of claim 1, wherein the pressure sensor is disposed adjacent to the hydraulic motor and the relief valve.

10. The stump cutter of claim 1, wherein the sweeping input is received by a user input device including one of: a joystick, a button, a dial, and a switch.Attorney Docket No. 489825-0019-W00111. The stump cutter of claim 1, wherein the sweep input command is calculated by the electronic processor using a preprogrammed control algorithm.

12. The stump cutter of claim 1, wherein the pressure sensor is a first pressure sensor, and the stump cutter further comprises a second pressure sensor configured to measure a pressure of hydraulic fluid expelled from the hydraulic motor, and the electronic processor being configured to calculate the adjusted sweep input command based on a difference between the pressure measured by the first pressure sensor and the pressure measured by the second pressure sensor.

13. A stump cutter comprising: a cutter wheel; a boom supporting the cutter wheel for rotation; a base portion supporting the boom for articulation by a first actuator configured to move the boom for sweeping the cutter wheel with respect to a stump; a hydraulic system including the first actuator, a hydraulic motor, and a plurality of valves, a pressure sensor configured to measure the pressure of a hydraulic fluid supplied to the hydraulic motor at the cutter wheel; and an electronic processor in communication with the pressure sensor and the first actuator, the electronic processor configured to: selectively enable rotation of the cutter wheel, initiate sweeping of the cutter wheel via a drive signal for the first actuator at a first speed based on a sweep input command, upon sweeping the cutter wheel, receive a pressure signal from the pressure sensor indicative of the pressure of the hydraulic fluid supplied to the hydraulic motor, calculate a second sweep input command based on the pressure signal, and upon determining that the second sweep input command is lower than the sweep input command, update the drive signal to the first actuator to automatically reduce sweeping of the cutter wheel to a second speed based on the second sweep input command.Attorney Docket No. 489825-0019-W00114. The stump cutter of claim 13, wherein the stump cutter is a stump cutter attachment having a mechanical connection interface and a hydraulic connection interface for a configurable work machine.

15. The stump cutter of claim 13, wherein the sweep input command is received by a user input device including a joystick.

16. The stump cutter of claim 13, wherein the sweep input command is calculated by the electronic processor based on a preprogrammed control algorithm.

17. The stump cutter of claim 13, wherein the calculation of the second sweep speed includes calculating the second sweep speed using a first closed loop control scheme and a difference between a reference pressure and the measured pressure.

18. The stump cutter of claim 17, wherein the calculation of the second sweep speed includes using a second closed loop control scheme upon determining that the measured pressure is greater than the reference pressure.

19. The stump cutter of claim 17, wherein the first closed loop control scheme is a proportional derivative (PD) control scheme.

20. The stump cutter of claim 17, wherein control characteristics of the first closed loop control scheme are adjustable based on a sweep direction of the boom.

21. The stump cutter of claim 13, wherein the pressure sensor is a first pressure sensor, and the stump cutter further comprises a second pressure sensor configured to measure a pressure of hydraulic fluid expelled from the hydraulic motor, and the electronic processor being configured to calculate the second sweep input command based on a difference between the pressure measured by the first pressure sensor and the pressure measured by the second pressure sensor.Attorney Docket No. 489825-0019-W00122. A method for controlling a stump cutter with a cutter wheel supported for rotation on a boom, the method comprising: driving rotation of the cutter wheel by directing hydraulic fluid at a drive pressure to a hydraulic motor connected to the cutter wheel; initiate sweeping of the cutter wheel at a first speed via a drive signal for a first actuator based on a sweep input command received by an electronic processor; upon sweeping the cutter wheel, the electronic processor receiving a signal from a pressure sensor that measures the drive pressure; calculating, using the electronic processor, an adjusted sweep input command based on the measured drive pressure from the pressure sensor; and upon determining that the adjusted sweep input command is less than the sweep input command, updating the drive signal to the first actuator to automatically reduce sweeping of the cutter wheel to a second speed.

23. The method of claim 22, wherein the adjusted sweep input command is calculated using a closed loop control algorithm and a difference between the measured pressure and a reference pressure.

24. The method of claim 23, wherein upon determining that the hydraulic pressure is greater than the reference pressure, the closed loop control algorithm calculates the adjusted sweep input command using a first gain.

25. The method of claim 24, wherein upon determining that the measured pressure is less than the reference pressure, the closed loop control algorithm calculates the adjusted sweep input command using a second gain different than the first gain.

26. The method of claim 25, wherein the adjusted sweep input command is calculated using a weighted sum of an output of the closed loop control algorithm using both the first gain and the second gain.

27. The method of claim 22, wherein upon sweeping the cutter wheel, the electronic processor further receives a signal from an additional pressure sensor indicative of the pressureAttorney Docket No. 489825-0019-W001 of hydraulic fluid expelled from the hydraulic motor, and wherein the electronic processor calculates the adjusted sweep input command based on the measured drive pressure and the pressure measured by the additional pressure sensor.

28. A hydraulic rotary tool comprising: a rotatable tool element operable on a work piece; a hydraulic motor operable to drive rotation of the rotatable tool element; a base portion supporting the rotatable tool element for rotation, the base portion further including an actuator configured to move the rotatable tool element to penetrate the work piece; a pressure sensor configured to measure a pressure of hydraulic fluid supplied to the hydraulic motor or the actuator and output a pressure signal corresponding to the measured pressure and indicative of resistance to penetration of the work piece by the rotatable tool element; and an electronic processor in communication with the pressure sensor and the actuator, the electronic processor configured to: initiate movement of the rotatable tool element, via a drive signal to the actuator, at a first penetration intensity based on a first input command, following the drive signal to the actuator, monitor the pressure signal from the pressure sensor, calculate a second input command based on the pressure signal, and upon determining that the second input command is lower than the first input command, update the drive signal to the actuator to automatically reduce the first penetration intensity to a second penetration intensity based on the second input command.

29. The hydraulic rotary tool of claim 28, wherein the second input command is calculated using a first closed loop control scheme and a difference between a reference pressure and a measured pressure from the pressure signal.

30. The hydraulic rotary tool of claim 29, wherein the calculation of the second input command further includes calculating the second input command using a second closed loopAttorney Docket No. 489825-0019-W001 control scheme upon determining that the measured pressure is greater than the reference pressure.

31. The hydraulic rotary tool of claim 29, wherein the first closed loop control scheme is a proportional derivative (PD) control scheme.

32. The hydraulic rotary tool of claim 29, wherein the first closed loop control scheme is a proportional integral (PI) control scheme33. The hydraulic rotary tool of claim 29, wherein control characteristics of the first closed loop control scheme are adjustable based on the difference between the reference pressure and the measured pressure from the pressure signal.

34. The hydraulic rotary tool of claim 33, wherein the control characteristics of the first closed loop control scheme are determined using a lookup table.

35. The hydraulic rotary tool of claim 28, wherein the rotatable tool element is a hollow cylindrical core saw bit, wherein the actuator is a hydraulic cylinder configured to selectively press the core saw bit into a pavement surface, and wherein the first penetration intensity is a first downforce applied to the core saw bit by the actuator.

36. The hydraulic rotary tool of claim 28, wherein the rotatable tool element is a stump cutter wheel, wherein the actuator is a sweep actuator configured to selectively sweep the stump cutter wheel across a stump, and wherein the first penetration intensity is a first sweep speed.

37. The hydraulic rotary tool of claim 28, further comprising a base machine including a power source configured to supply power to the hydraulic motor and the actuator, wherein the base portion of the hydraulic rotary tool is removably couplable as an attachment to the base machine.

38. The hydraulic rotary tool of claim 28, wherein the electronic processor is configured to calculate the second input command based on a difference between the pressure signal and anAttorney Docket No. 489825-0019-W001 additional pressure signal from an additional pressure sensor, wherein the pressure sensor and the additional pressure sensor are configured to measure pressure at respective opposite actuation ports of the actuator.

39. A core saw comprising: a rotatable hollow cylindrical core saw bit; a base portion supporting the hollow cylindrical core saw bit for rotation, the base portion further including a hydraulic cylinder configured to move the hollow cylindrical core saw bit to penetrate the ground; a pressure sensor configured to measure a pressure of hydraulic fluid at the hydraulic cylinder and output a pressure signal corresponding to the measured pressure and indicative of resistance to penetration of the ground by the hollow cylindrical core saw bit; and an electronic processor in communication with the pressure sensor and the hydraulic cylinder, the electronic processor configured to: initiate movement of the hollow cylindrical core saw bit, via a drive signal to the hydraulic cylinder, at a first penetration intensity based on a first input command, following the drive signal to the hydraulic cylinder, monitor the pressure signal from the pressure sensor, calculate a second input command based on the pressure signal, and upon determining that the second input command is lower than the first input command, update the drive signal to the hydraulic cylinder to automatically reduce the first penetration intensity to a second penetration intensity based on the second input command.

40. The core saw of claim 39, wherein the pressure sensor is a first pressure sensor, and the core saw further comprises a second pressure sensor, the first and second pressure sensors configured to measure pressure at respective opposite actuation ports of the hydraulic cylinder,Attorney Docket No. 489825-0019-W001 and the electronic processor being configured to calculate the second input command based on a difference between the pressure signal from the first pressure sensor and a pressure signal from the second pressure sensor.

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