Bump / lift mechanism for robotic ground care machine

Abstract

A robotic work vehicle includes a movable work implement; and a shroud that covers the chassis. A linkage couples the shroud to the chassis. The linkage includes a rotating link that allows horizontal displacement between the shroud and the chassis and a lifting link that allows vertical displacement between the shroud and the chassis. A lift sensor detects the vertical displacement via one or both of the lifting link and the rotating link. A controller of the work vehicle is operable to, in response to detection of the vertical displacement, stop the work implement. The linkage may also include a second sensor that detects the horizontal displacement. In response to the detection of the horizontal displacement, the controller may register a bump event.

Description

BUMP / LIFT MECHANISM FOR ROBOTIC GROUND CARE MACHINERELATED PATENT DOCUMENTS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 535,133, filed on August 29, 2023, which is incorporated herein by reference in its entirety.SUMMARY

[0002] The present disclosure is directed to a bump / lift mechanism of an autonomous ground care machine. In one embodiment, a robotic work vehicle includes: a movable work implement; a chassis with a motor that propels the work vehicle; a shroud that covers the chassis; and a linkage that couples the shroud to the chassis. The linkage includes: a rotating link that allows horizontal displacement between the shroud and the chassis; a lifting link that allows vertical displacement between the shroud and the chassis; a first sensor that detects the horizontal displacement via the rotating link; and a second sensor that detects the vertical displacement via the lifting link. The vehicle further includes a controller coupled to the work implement and the first and second sensors. The controller operable to in response to detection of the vertical displacement, stop the work implement; and in response to detecting the horizontal displacement, register a bump event with a navigation system.

[0003] In another embodiment, a robotic work vehicle includes a movable work implement; a chassis with a motor that propels the work vehicle; a shroud that covers the chassis; and a linkage that couples the shroud to the chassis. The linkage includes: a rotating link that allows horizontal displacement between the shroud and the chassis; a lifting link that allows vertical displacement between the shroud and the chassis, the lifting link is pivotably attached to the rotating link and to the chassis; and a lift sensor that detects the vertical displacement via the lifting link and the rotating link. The vehicle further includes a controller coupled to the work implement and the lift sensor. The controller is operable to, in response to detection of the vertical displacement, stop the work implement.

[0004] These and other features and aspects of various embodiments may be understood in view of the following detailed discussion and accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The discussion below makes reference to the following figures, wherein the same reference number may be used to identify the similar / same component in multiple figures. The drawings are not necessarily to scale.

[0006] FIGS. 1 and 2 are perspective views of a ground care vehicle according to various example embodiments;

[0007] FIG. 3 is a perspective view of a shroud linkage according to an example embodiment;

[0008] FIGS. 4-8 are cutaway views of the shroud linkage of FIG. 3 showing various displacements;

[0009] FIGS. 9 and 10 are perspective and side views of a shroud linkage according to another example embodiment;

[0010] FIGS. 11 and 12 cutaway views of the shroud linkage of FIG. 9 showing various displacements;

[0011] FIG. 13 is an exploded view of the shroud linkage of FIG. 9;

[0012] FIG. 14 is a block diagram of an apparatus according to an example embodiment; and

[0013] FIGS. 15-16 are flowcharts showing methods according to example embodiments.DETAILED DESCRIPTION

[0014] In the following detailed description of illustrative embodiments, reference is made to the accompanying figures of the drawing which form a part hereof. It is to be understood that other equivalent embodiments, which may not be described and / or illustrated herein, are also contemplated.

[0015] The present disclosure relates generally to ground care machines, which may be variously referred to herein as ground care vehicles, ground maintenance machines, ground maintenance vehicles, and the like. Ground care machines, such as lawn and garden machines, are known for performing a variety of tasks. For instance, powered lawn mowers are used by both homeowners and professionals alike to maintain grass areas within a property or yard. The same or different machines may be used for maintenance on the turf areas (and sometimes away from the turf), performing operations such as debris collection, spraying, dethatching, edging, rolling, towing, snow / ice treatment and removal, etc.

[0016] Embodiments of the present disclosure relate to features of a robotic work vehicle, such as an autonomous ground maintenance machine. Generally, an autonomous machine may perform a defined set of operations without human input. The autonomous inputs are generated by a computer processor and cause and / or effect a physical action performed by the machine. One example of autonomous operation is autonomous navigation, where the machine can maneuver around a work region without user input, or with minimal user input (e.g., initial placement and initiating a start command). Robotic work vehicles do not need to be fully autonomous, e.g., may be remote controlled by a human, however some actions may still be autonomously guided or halted based on sensor inputs to the machine. For example, a bump sensor may detect an obstacle that may not be visible by the operator, and the machine can autonomously take an action based on this, e.g., stop moving, alert the operator, back up and re-route, etc.

[0017] A robotic work vehicle may have a variety of sensors to interact with its environment, particularly for autonomous vehicles. Those sensors include cameras, proximity sensors, bump sensors, inertial navigation sensors, wheel speed encoders, geolocation sensors, etc. The work vehicle may use the sensors to halt operation if an event is detected which could damage the machine or cause the machine to damage something else. For example, if the machine detects (e.g., via an accelerometer) that it is oriented (e.g., tilted) such that a cutting blade or other turf cutter is exposed, then the power to the cutting blade may be cut off as a precaution.

[0018] In the following enclosure, a bump / lift mechanism is described that can detect bumping of a shroud (or other outward-facing body part) of a robotic work vehicle,e.g., due to hitting a boundary or obstacle. In response to bump detection, the work vehicle may back away from the obstacle but may continue working, e.g., attempt to maneuver around the obstacle. The same mechanism can also detect if the shroud is being lifted from a chassis, e.g., by a bystander (e.g., person proximate the vehicle) attempting to lift up the vehicle. In this case, a work implement (e.g., turf cutting blade) may be disabled. In this context, the disabling may also include stopping the work implement if it is moving. Even if the work implement is not moving when a lift is detected, a shutoff may be activated (e.g., power cutoff relay) to preventing the work implement from inadvertently being activated while the lift condition is detected. In some embodiments, a disabling or warning device may be activated (e.g., a shaft brake, flashing light) in the event the lift condition is detected.

[0019] In FIGS. 1 and 2, perspective views show a robotic work vehicle 100 according to one or more embodiments. As best seen in FIG. 2, the robotic work vehicle 100 includes a chassis 104 with a motor coupled to drive wheels 101 that propels the work vehicle 100. The vehicle 100 also has front wheels 103 that can be used for steering, e.g., actively controlled. In other embodiments, the front wheels 103 may freely rotate, e.g., caster wheels, such that the vehicle 100 is steered by differential rotation of the drive wheels 101. A work implement (not seen in this view) performs work on or near the ground such as cutting, scraping, spraying, aerating, etc. In this example, the work implement includes a rotary, turf-cutting, blade underneath the chassis 104 that faces the ground and is driven by a rotating electric motor to cut grass.

[0020] A shroud 102 covers the chassis 104 and, among other things, protects internal components from damage from water, dust, flying debris, etc. Mounted near four outward comers of the chassis 104 are linkages 106 that couple the shroud 102 to the chassis 104. More or fewer linkages 106 can be used in some embodiments. In FIG. 2, the linkages 106 are concealed by covers 107, which may be flexible waterproof covers that keep out dirt and moisture. The linkages 106 will be described in greater detail further below.

[0021] In reference again to FIG. 1, arrows indicate a longitudinal direction 110, a vertical direction 111, and a lateral direction 112. Generally, these three directions 110-112 are defined relative to the work vehicle 100 and are orthogonal to each other. Thelongitudinal direction 110 corresponds to direction the vehicle 100 moves when going in a forward or reverse straight line. The longitudinal direction 110 may also be referred to as a down-path direction. The lateral direction 112 is aligned with the axles of the drive wheels 101, and may also be referred to as a transverse or cross-path direction. The vertical direction 111 is normal to the ground in which the work vehicle 100 is positioned, and may be aligned with or slightly offset from the gravitational vector depending on whether the work vehicle 100 is on level ground or a on a slope.

[0022] The work vehicle 100 is designed so that the linkages 106 provide some amount of relative motion between the shroud 102 and the chassis 104. This relative motion allows the shroud 102 to move in the event the work vehicle 100 bumps / impacts an obstacle, for example, such that the vehicle can back off or otherwise deal with the obstacle. The relative vertical movement can also prevent the shroud 102 from getting stuck on obstacles (e.g., rocks, soil mounds) that are slightly larger than the shroud-to- ground clearance. By integrating one or more sensors into the linkages 106, the displacement of the shroud 102 relative to the chassis 104 can also be detected and used for one or both of bump and lift detection. If a lift is detected, this may be indicative that a bystander is attempting to lift the vehicle by the shroud, in which case the work implement is stopped.

[0023] In FIG. 3, a perspective view shows a linkage 300, which in some embodiments corresponds to at least one of the linkages 106 shown in FIGS. 1 and 2. The linkage 300 includes a rotating link 302 that allows horizontal displacement (in the longitudinal and / or lateral directions 110, 112) between the shroud 102 and the chassis 104 (both not shown in FIG. 3). A bracket 301 couples the linkage 300 to the chassis 104. A lifting link 304 allows vertical displacement (in the vertical direction 111) between the shroud 102 and the chassis 104. In some embodiments, orienting the lifting link 304 in the lateral direction 112 (such that the major dimensions of arms 306 are aligned with the lateral direction 112) makes the lifting link 304 less prone to being lifted during a bump event. Nonetheless, various embodiments may orient the lifting link 304 in a longitudinal orientation, an orientation between longitudinal and lateral, or a combination of orientations (e.g., longitudinal in some locations on the machine, lateral in other locations).

[0024] In this embodiment, the lifting link 304 includes at least two parallel arms 306 having first ends 306a pivotably attached to the shroud 102 via and second ends 306b pivotably attached to the chassis 104. This example shows four arms 306 which are formed of mirror image parts, however the top and bottom arms 306 may each be a single, interchangeable part, e.g., the same arm part could be used on either the top or bottom. The first ends 306a of the parallel arms 306 are attached, via pins 307, to an end housing 308 that holds the rotating link 302. In this way, the parallel arms 306 are attached to the shroud via the rotating link 302. The rotating link 302 is attached to the shroud 102 via mount end 310a of elongated member 310. The second ends 306a of the parallel arms 306 are attached, via pins 312, to an intermediate bracket 314 that is fixably mounted to bracket 301.

[0025] In FIG. 4, a partial cutaway view shows additional details of the linkage 300 of FIG. 3. The elongated member 310 of the rotating link 302 includes a middle part 310c rotatably attached to the end housing 308 via a ball and socket joint 406. A distal end 310b of the elongated member 310 is opposed to the mount end 310a. A first sensor 402 detects a horizontal displacement of the rotating link 302 by detecting movement of the distal end 310b in response to the horizontal displacement. The distal end 310b may include a sensor target 403 that is detected by the first sensor 402. For example, the sensor target 403 may be a magnet if the first sensor 402 is a Hall-effect sensor. In other embodiments, the distal end 310b itself may server as the target, e g., if a touch or reflective sensor is used.

[0026] A second sensor 404 detects the vertical displacement of the shroud 102 via the lifting link 304. A lower one of the at least two parallel arms 306 is proximate the chassis 104. The second sensor 404 detects movement of the lower arm 306 towards and away from the chassis 104. The second sensor 404 may be of the same or different type than the first sensor 402. As with the first sensor 402, the second sensor 404 may also detect a sensor target 405 (e.g., a magnet) that is attached to the lower arm 306. Note that because the upper and lower arms 306 are the same in this embodiment, the upper arm or arms 306 also include a feature (e.g., mounting cavity) for the sensor target 405 even though it is not used on the upper arm or arms 306.

[0027] The sensors 402, 404 may be able to detect a range of distances that the rotating link 302 and lifting link 304 respectively move. For example, a sensor thatmeasures time of flight of a signal (e.g., audio, radio, optical) can detect how far away the sensor target 403, 405 is from the respective sensor 402, 404. An optical sensor can estimate distances based on optical power of a direct or reflected light source. A Hall effect sensor may also be able to estimate distance based on magnetic field strength, e.g., in the range of around 0-4cm. In other embodiments, one or more of the sensors 402, 404 may operate as a threshold sensor that detects whether the target-to-sensor separation satisfies a threshold, which is converted to a binary value, e.g., contact, no-contact. The previously described sensor types (e.g., time of flight, Hall effect, optical) can be configured in this way, and other sensors may also provide threshold detection, e.g., a mechanical limit switch, electric eye.

[0028] Generally, the linkage 300 can be provided as a single mechanism / assembly that can be used to detect both lifting of the shroud 102 and impact of the shroud 102 on obstacles, and be able to distinguish between the two. For example, a pure vertical displacement may be due to an operator lifting the work vehicle 100 by the shroud 102. This may be accompanied by a horizontal (e.g., longitudinal and / or lateral) displacement depending on how the lift occurs. However, a bump, e.g., into a wall, may not cause a significant vertical displacement, and so the existence of the horizontal displacement without vertical displacement can be assumed to be impact with an obstacle and can be treated appropriately, e.g., machine backs up. In the same context, the detection of the vertical displacement with or without a horizontal displacement may be used to trigger other actions, e.g., stopping a work implement, stopping the drive wheels, sending an alert.

[0029] Also seen in FIG. 4 are a compression spring 408, a centering disc 409, and a ball interface 410. The ball interface 410 mates with a socket of a retainer bearing (not shown) to form a second ball-and-socket joint. The retainer bearing attaches to the shroud 102 and couples both the rotating link 302 and the lifting link 304 to the shroud 102 and allows rotation at the link-to-shroud interface via the second ball-and-socket joint. The compression spring 408 (or other compressive biasing member) and centering disc 409 return the rotating link 302 to center (e.g., aligned with vertical direction) once any horizontal forces applied to the rotating link 302 are removed. The force of gravity returns the lifting link 304 to its resting position once any vertical lifting forces are removed.

[0030] In FIGS. 5-7, cutaway views show the linkage 300 being subjected to horizontal forces that affect the rotating link 302. In FIG. 5, a horizontal force deflects the shroud 102 causing a displacement 502 of mount end 310a of the elongated part 310. Because the elongated part 310 can rotate about the ball and socket joint 406, the displacement 502 results in a rotation of angle 504 and a displacement 506 between the distal end 310b of the elongated part 310 and the first sensor 402. The displacement 506 results in a bump event being detected. In FIG. 6, a horizontal displacement 602 is shown, but in the opposite direction from what is shown in FIG. 5.

[0031] In FIG. 7, a horizontal displacement 702 is shown, but in a direction normal to the directions shown in in FIGS. 5 and 6. For example if the force causing the displacement in FIG. 5 was in the lateral direction, the force causing the displacement in FIG. 7 would be in the longitudinal direction. The ball joint 406 allows displacements in any horizontal direction with corresponding rotations, and any of these displacements and rotations will result in a sensor-to-target displacement similar to displacement 506 in FIG. 5. Note that the spring 408 is compressed in FIGS. 5-7 compared to the undeflected orientation in FIG. 4. The force of the compressed spring 408, together with the rounded shape of the centering disc 409 and chamfers 308a on the top of the housing 308 act to bias the elongated part 310 to a vertical orientation.

[0032] In FIG. 8, a cutaway view shows the linkage 300 being subjected to a vertical force from the shroud 102 that affects the lifting link 304. The vertical force causes a displacement 802 of the housing 308, which rotates arms 306. Due to the arrangement and geometry of the arms 306 and rotating links (pins 307 and 312), the housing 308 maintains a vertical orientation in response to a vertical displacement. The rotation of the lower arm 306 results in a displacement 804 of the sensor target 405 away from the second sensor 404, resulting in a lift event being detected.

[0033] In FIGS. 9 and 10, perspective and side views show a linkage 900, which in some embodiments corresponds to at least one of the linkages 106 shown in FIGS. 1 and 2. The linkage 900 includes a rotating link 902 that allows horizontal displacement between the shroud 102 and the chassis 104. A lifting link 904 allows vertical displacement between the shroud 102 and the chassis 104. The lifting link 904 is pivotably attached to the rotating link 902, e.g., via bolts 905 (or other fasteners such as pins), and is pivotablyattached to the chassis 104, e.g., via bracket 901 and bolts 915 (or other fasteners such as pins).

[0034] The lifting link 904 includes at least two parallel arms 906 having first ends 906a (see FIG. 10) pivotably attached to the shroud and second ends 906b pivotably attached to the chassis via bracket 901. The first ends 906a of the parallel arms 906 are attached to an end housing 908 that holds the rotating link 902, the rotating link 902 being attached to the shroud 102 via retainer bearing 903. In this way, the lifting link 904 is attached to the shroud 102 via the rotating link 902, as with the previous embodiment. A cover 907 encloses the arms 906 and also acts to limit vertical movement of the arms 906 away from the bracket 901.

[0035] The rotating link 902 includes an elongated member 910 with a mount end 910a attached to the shroud 102, e g., via retainer bearing 903. The rotating link 902 includes a distal end 910b opposed to the mount end 910a. The distal end 910b is rotatably attaches to the end housing 908 via a ball and socket joint 1006 (see FIG. 10). A compression spring 912 and centering disc 914 perform similar functions as the spring 408 and disc 409 shown in FIGS. 4-7.

[0036] The embodiment shown in FIGS. 9 and 10 is configured to sense lift, via lift sensor 1002 seen in FIG. 10. The lift sensor 1002 is mounted on a hollow, lower protrusion 901a of the bracket 901. A tapered portion 908a of the end housing 908 (see FIGS. 11 and 12) fits within the lower protrusion 901a where it can be seated and unseated by lifting and lowering of the shroud 102. A rotation / bump sensor is not used in this embodiment. Note that the linkage 300 as shown in FIG. 4 can also be used for lift-only sensing, e.g., by removing the sensor 402.

[0037] In FIGS. 11 and 12, partial cutaway views shows operation of the linkage 900 in response to horizontal and vertical displacements. In FIG. 13, an exploded view shows additional details of the linkage 900. In FIG. 11, a lift sensor target 1102 is shown facing the lift sensor 1002. The lift sensor 1002 detects vertical movement of the rotating link 902 in response to a vertical displacement. The lift sensor 1002 does not, however, detect a rotation of the rotating link 902, which is shown in FIG. 11.

[0038] In FIG. 11, end 910a of the rotating link 902 is moved horizontally, resulting in the elongated part 910 being rotated by angle 1103. Note that, due to a secondball and socket joint 1104 coupling the retainer bearing to the elongated member 910, the retainer bearing 903 still maintains the orientation shown in FIG. 10 even when the rotating link 902 is rotated / displaced. Also note compression of the spring 912 in FIG. 11, which asserts a return-to-start (e.g., return to zero angle) force on the centering disk 914.[0039J In FIG. 12, the rotating link 902 is subjected to a vertical force with no horizontal component, resulting in a displacement 1202 between the sensor target 1102 and sensor 1002. As described with other embodiments, the displacement could be detected by the sensor 1002 (and associated processing electronics) as a range of displacement and / or a binary indicator. Note that the cover 907 prevents further vertical motion of the arms 906, limiting the amount that the rotating link 902 can move upwards. This limit distance can be adjusted by changing dimensions of the cover 907 that contacts the top arm 906, or by providing a sliding bracket or the like in place of the top of the cover 907 to provide a field-adjustable mechanical limit. A similar cover could be used in the embodiments shown in FIGS. 3-8.

[0040] In FIG. 14, a block diagram shows an apparatus 1400 according to an example embodiment. The apparatus 1400 is a robotic work machine, such as an autonomous ground care machine. The apparatus 1400 includes one or more main boards 1402 that house electronic components, such as computer processing circuits, power conditioning and management circuits, sensor signal processing circuits, motor controllers, etc. The processing circuits are represented by System on a Chip (SoC) 1404, which combines components such as central processing units (CPUs), memory, input-output busses, power management, network interfaces, etc., into a single package. At least some of these components may be provided in separate packages in some embodiments.

[0041] The SoC 1404 is programmable by computer instructions 1403 that may be embodied as any combination fixed logic (e.g., field programmable gate array, or FPGA), firmware, and software. The instructions 1403 include functional modules such as a navigation / work module 1406 that governs machine operations when moving and / or working in a work region. This module 1406 may access stored maps and work instructions, interpret inputs from sensors 1410-1411, and utilize controller logic to activate electro-mechanical devices such as one or more work implement motors 1414 and one or more drive motors 1416. The instructions 1403 include a shutoff module 1408 thatdetermines whether circuitry that affects the work implement motor 1414 should be set to stop the work implement while a lift condition is detected.

[0042] A motor controller 1418 facilitates driving the motors 1414, 1416, e.g., by taking a digital input from SoC 1404 and converting it to an analog output, e.g., an electrical current. Note that the embodiments described herein need not use electrical motors and actuators. For example, internal combustion, hydraulic, and / or pneumatic motors may be used instead of or in addition to electric motors. Nonetheless, such nonelectric motors may still be controlled via the SoC 1404 by electric means, e.g., valves, relays, fuel injectors / throttles, etc.

[0043] The apparatus includes one or more vertical displacement sensors 1410 that are integrated into a shroud-to-chassis linkage as previously described. The vertical displacement sensors 1410 provide either a binary or multivariable (e.g., integer from 0- 255) indication of shroud-to-chassis vertical displacement at a location on the apparatus. The apparatus 1400 may have multiple such linkages (e.g., four linkages) but not all of the linkages need be equipped with vertical displacement sensors 1410.

[0044] For example, a machine with two or more linkage located between the shroud and the chassis at different first and second locations may have vertical displacement sensors 1410 respectively detecting two or more vertical displacements at the different first and second locations. Detection of the vertical displacement may involve combining the two or more vertical displacements. For example, if the vertical displacement sensors 1410 are configured to produce a binary signal (e.g., 0=not lifted, l=lifted), then the combination may involve a logical operation such as AND, OR and / or a mathematical operation, e.g., sum of the number of lift detections. If the vertical displacement sensors 1410 are configured to produce a measurement of displacement (e.g., an integer or floating point value within a range), then the combination may involve averaging, using a maximum one of the values, etc.

[0045] In some embodiments, the apparatus includes one or more horizontal displacement sensors 1411 that are integrated into a shroud-to-chassis linkage as previously described. The horizontal displacement sensors 1411 provide either a binary or multivariable (e.g., integer from 0-255) indication of shroud-to-chassis horizontal displacement at a location on the apparatus. The apparatus 1400 may have multiple suchlinkages (e.g., four linkages) but not all of the linkages need be equipped with horizontal displacement sensors 1411, and some linkages may have both vertical displacement sensors 1410 and horizontal displacement sensors 1411.

[0046] Similar to the vertical displacement sensors 1410, outputs from two or more horizontal displacement sensors 1411 may be combined, such as a logical combination of binary outputs or statistical combination of measurement values. Further, the measurements of horizontal and vertical displacement at the same and different linkages can be combined. For example, if a linkage provides measurement values of both horizontal and vertical displacement, then the measurement can be combined to form vector that represents a total displacement and / or an angle of displacement. This can provide a more detailed profile of particular lift / impact events, allowing for a more varied response.

[0047] The readings obtained from the vertical displacement sensors 1410 and horizontal displacement sensors 1411 can be combined with readings from other sensor 1412, such as an accelerometer, inertial measurement unit, gyroscope, proximity detector, etc. This can provide a more detailed representation of bump / lift events, and can also be used to cross check sensor readings, e.g., determine anomalous readings due to a sensor malfunction. These measurements and characterizations can be used by the shutoff module to pause, stop, disable, a mechanism such as a cutting implement. The measurements and characterizations can also be used by the navigation / work module 1406, e.g., to detect obstacles, stuck condition, machine malfunctions, etc. The other sensors 1412 may also include navigation sensors such as cameras, radar, LIDAR, RTK, contact sensors, proximity sensors, beacon detectors, boundary wire detectors, etc., that are used by the navigation / work module 1406.

[0048] In view of the above, it will be readily apparent that the functionality of the controllers of the system may be implemented in any manner known to one skilled in the art. For instance, the memory may include any volatile, non-volatile, magnetic, optical, and / or electrical media, such as a random-access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory, and / or any other digital media.

[0049] The processors used in the controllers may include any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), and / or equivalent discrete or integrated logic circuitry. In some embodiments, the processor may include multiple components, such as any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, and / or one or more FPGAs, as well as other discrete or integrated logic circuitry. The functions attributed to the controller and / or processor herein may be embodied as software, firmware, hardware, or any combination of these. Certain functionality of the controller may also be performed in the cloud or other distributed computing systems operably connected to the processor.

[0050] The inter-device and intra-device communications may use any combination of wired and wireless communications. Examples of wireless data interfaces include WiFi, Bluetooth, cellular modem, inductive data interface, and NFC. Examples of wired interfaces include Universal Serial Bus (USB), Ethernet, Controller Area Network (CAN), Inter-Integrated Circuit (I2C), and serial line (e.g., RS-232, IEEE 1394).

[0051] In FIG. 15, a flowchart illustrates a method according to an example embodiment. The method is performed in a work mode 1500, e.g., the machine is moving through a work area and operating a work implement. The method may be adapted for other modes, e.g., training, retum-to-base, etc. Horizontal and vertical sensors are polled 1501, e.g., a value of the sensors is read at repeated intervals. Other ways of obtaining sensor readings, e.g., processor interrupts, may be used.

[0052] At block 1502 the vertical displacement is tested, e.g., returns ‘yes’ if the vertical displacement exceeds a threshold. If so, the work implement is stopped as indicated at block 1503. If block 1502 returns ‘no,’ the work implement is released (e.g., allowed to operate as needed for the work) as indicated at block 1504. At block 1505 the horizontal displacement is tested, e.g., returns ‘yes’ if the horizontal displacement exceeds a threshold. If so, a bump condition is registered, e.g., with the navigation system, as indicated at block 1506. If block 1505 returns ‘no,’ the bump condition is cleared as indicated at block 1507. The process runs in an infinite loop until the machine is no longer in work mode.

[0053] In FIG. 16, a flowchart illustrates a method according to another example embodiment. The method involves, coupling 1600 a shroud to a chassis of a robotic work vehicle via a linkage. The linkage includes a rotating link and a lifting link that respectively allow horizontal and vertical displacement between the shroud and the chassis. The horizontal displacement is detected 1601 via a first sensor of the linkage and the vertical displacement is detected 1602 via a second sensor of the linkage. In response to detection of the vertical displacement, a work implement of the robotic work vehicle is stopped 1603. In response to detecting the horizontal displacement, a bump event is registered 1604 with a navigation system. Note that steps 1601 and 1604 are shown as optional, e.g., may use a linkage as in FIGS. 11 and 12 without a sensor to detect rotation of the rotating link.

[0054] While the present disclosure is not so limited, an appreciation of various aspects of the disclosure will be gained through a discussion of the specific illustrative aspects provided below. Various modifications of the illustrative aspects, as well as additional aspects of the disclosure, will become apparent herein.

[0055] Example 1 is robotic work vehicle, comprising: a movable work implement; a chassis with a motor that propels the work vehicle; a shroud that covers the chassis; a linkage that couples the shroud to the chassis, the linkage comprising: a rotating link that allows horizontal displacement between the shroud and the chassis; a lifting link that allows vertical displacement between the shroud and the chassis; a first sensor that detects the horizontal displacement via the rotating link; and a second sensor that detects the vertical displacement via the lifting link; and a controller coupled to the work implement and the first and second sensors, the controller operable to: in response to detection of the vertical displacement, stop the work implement; and in response to detecting the horizontal displacement, register a bump event with a navigation system.

[0056] Example 2 includes the work vehicle of example 1, wherein the lifting link comprises at least two parallel arms having first ends pivotably attached to the shroud and second ends pivotably attached to the chassis. Example 3 includes the work vehicle of example 2, wherein the first ends of the parallel arms are attached to the shroud via the rotating link, the rotating link being attached to the shroud.

[0057] Example 4 includes the work vehicle of example 2 or 3, wherein the first ends of the parallel arms are attached to an end housing that holds the rotating link, the rotating link being attached to the shroud. Example 5 includes the work vehicle of example 4, wherein the rotating link comprises an elongated member, the elongated member comprising: a mount end attached to the shroud; a middle part rotatably attached to the end housing via a ball and socket joint; and a distal end opposed to the mount end, the first sensor detecting movement of the distal end in response to the horizontal displacement. Example 6 includes the work vehicle of any one of examples 2-5, wherein a lower one of the at least two parallel arms is proximate the chassis, and wherein the second sensor detects movement of the lower arm towards and away from the chassis.

[0058] Example 7 includes the work vehicle of any one of examples 1-6, wherein the detection of the vertical displacement is due to a bystander lifting the work vehicle by the shroud. Example 8 includes the work vehicle of any one of examples 1-7, wherein the rotating link allows the horizontal displacement between the shroud and the chassis in both a longitudinal direction and a lateral direction. Example 9 includes the work vehicle of any one of examples 1-8, wherein one or both of the first and second sensors comprise a proximity sensor. Example 10 includes the work vehicle of any one of examples 1-9, wherein one or both of the first and second sensors comprise an optical sensor. Example 11 includes the work vehicle of any one of examples 1-10, wherein the work implement comprises a turf cutter. Example 12 includes the work vehicle of example 11, wherein the turf cutter comprises a rotating blade.

[0059] Example 13 includes the work vehicle of any one of examples 1-12, wherein the linkage comprises two more linkages that are located between the shroud and the chassis at different first and second locations, the second sensors of the two or more linkages respectively detecting two or more vertical displacements at the different first and second locations, and wherein the detection of the vertical displacement comprises combining the two or more vertical displacements.

[0060] Example 14 is a robotic work vehicle, comprising: a movable work implement; a chassis with a motor that propels the work vehicle; a shroud that covers the chassis; a linkage that couples the shroud to the chassis, the linkage comprising: a rotating link that allows horizontal displacement between the shroud and the chassis; a lifting linkthat allows vertical displacement between the shroud and the chassis, the lifting link pivotably attached to the rotating link and to the chassis; a lift sensor that detects the vertical displacement via the lifting link and the rotating link; and a controller coupled to the work implement and the lift sensor, the controller operable to, in response to detection of the vertical displacement, stop the work implement.

[0061] Example 15 includes the work vehicle of example 14, wherein the lifting link comprises at least two parallel arms having first ends pivotably attached to the shroud and second ends pivotably attached to the chassis. Example 16 includes the work vehicle of example 15, wherein the first ends of the parallel arms are attached to the shroud via the rotating link, the rotating link being attached to the shroud. Example 17 includes the work vehicle of example 15 or 16, wherein the first ends of the parallel arms are attached to an end housing that holds the rotating link, the rotating link being attached to the shroud.

[0062] Example 18 includes the work vehicle of example 17, wherein the rotating link comprises an elongated member, the elongated member comprising: a mount end attached to the shroud; and a distal end opposed to the mount end and rotatably attached to the end housing via a ball and socket joint, the lift sensor detecting movement of the end housing in response to the vertical displacement.

[0063] Example 19 is a method, comprising: coupling a shroud to a chassis of a robotic work vehicle via a linkage, the linkage comprising a rotating link and a lifting link that respectively allow horizontal and vertical displacement between the shroud and the chassis; detecting the vertical displacement via a first sensor of the linkage; in response to detection of the vertical displacement, stop a work implement of the robotic work vehicle. Example 20 includes the method of example 19, further comprising: detecting the horizontal displacement via a second sensor of the linkage; and in response to detecting the horizontal displacement, register a bump event with a navigation system.

[0064] It is noted that the terms “have,” “include,” “comprises,” and variations thereof, do not have a limiting meaning, and are used in their open-ended sense to generally mean “including, but not limited to,” where the terms appear in the accompanying description and claims. Further, “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably herein. Moreover, relative terms such as ’’left,” “right,” “front,” “fore,” “forward,” “rear,” “aft,” “rearward,” “top,” “bottom,” “side,” “upper,”“lower,” “above,” “below,” “horizontal,” “vertical,” and the like may be used herein and, if so, are from the perspective shown in the particular figure, or while the machine is in an operating configuration. These terms are used only to simplify the description, however, and not to limit the interpretation of any embodiment described. As used herein, the terms “determine” and “estimate" may be used interchangeably depending on the particular context of their use, for example, to determine or estimate a position or pose of a vehicle, boundary, obstacle, etc.

[0065] Further, it is understood that the description of any particular element as being connected to or coupled to another element can be directly connected or coupled, or indirectly coupled / connected via intervening elements.

[0066] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. The use of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range.

[0067] The various embodiments described above may be implemented using circuitry, firmware, and / or software modules that interact to provide particular results. One of skill in the arts can readily implement such described functionality, either at a modular level or as a whole, using knowledge generally known in the art. For example, the flowcharts and control diagrams illustrated herein may be used to create computer-readable instructions / code for execution by a processor. Such instructions may be stored on a non- transitory computer-readable medium and transferred to the processor for execution as is known in the art. The structures and procedures shown above are only a representative example of embodiments that can be used to provide the functions described hereinabove.

[0068] Note that any components described herein using terms such as “processor,” “controller,” “logic circuit,” “CPU,” or the like may be implemented using a plurality of discrete units operating together. For example, a processer that performs a series of steps or operations may be construed as two or more processors operating cooperatively to performthe steps. Similarly, other processing hardware such as memory and input-output may perform the described functions with multiple discrete units operating cooperatively or being coordinated by another unit, e.g., by a central processor or processors.

[0069] The foregoing description of the example embodiments has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. Any or all features of the disclosed embodiments can be applied individually or in any combination and are not meant to be limiting, but purely illustrative. It is intended that the scope of the invention be limited not with this detailed description, but rather determined by the claims appended hereto.

Claims

CLAIMS:

1. A robotic work vehicle, comprising: a movable work implement; a chassis with a motor that propels the work vehicle; a shroud that covers the chassis; a linkage that couples the shroud to the chassis, the linkage comprising: a rotating link that allows horizontal displacement between the shroud and the chassis; a lifting link that allows vertical displacement between the shroud and the chassis; a first sensor that detects the horizontal displacement via the rotating link; and a second sensor that detects the vertical displacement via the lifting link; and a controller coupled to the work implement and the first and second sensors, the controller operable to: in response to detection of the vertical displacement, stop the work implement; and in response to detecting the horizontal displacement, register a bump event with a navigation system.

2. The work vehicle of claim 1, wherein the lifting link comprises at least two parallel arms having first ends pivotably attached to the shroud and second ends pivotably attached to the chassis.

3. The work vehicle of claim 2, wherein the first ends of the parallel arms are attached to the shroud via the rotating link, the rotating link being attached to the shroud.

4. The work vehicle of claim 2 or 3, wherein the first ends of the parallel arms are attached to an end housing that holds the rotating link, the rotating link being attached to the shroud.

5. The work vehicle of claim 4, wherein the rotating link comprises an elongated member, the elongated member comprising: a mount end attached to the shroud; a middle part rotatably attached to the end housing via a ball and socket joint; and a distal end opposed to the mount end, the first sensor detecting movement of the distal end in response to the horizontal displacement.

6. The work vehicle of any one of claims 2-5, wherein a lower one of the at least two parallel arms is proximate the chassis, and wherein the second sensor detects movement of the lower arm towards and away from the chassis.

7. The work vehicle of any one of claims 1-6, wherein the detection of the vertical displacement is due to a bystander lifting the work vehicle by the shroud.

8. The work vehicle of any one of claims 1-7, wherein the rotating link allows the horizontal displacement between the shroud and the chassis in both a longitudinal direction and a lateral direction.

9. The work vehicle of any one of claims 1-8, wherein one or both of the first and second sensors comprise a proximity sensor.

10. The work vehicle of any one of claims 1-9, wherein one or both of the first and second sensors comprise an optical sensor.

11. The work vehicle of any one of claims 1-10, wherein the work implement comprises a turf cutter.

12. The work vehicle of claim 11, wherein the turf cutter comprises a rotating blade.

13. The work vehicle of any one of claims 1-12, wherein the linkage comprises two more linkages that are located between the shroud and the chassis at different first and second locations, the second sensors of the two or more linkages respectively detecting two or more vertical displacements at the different first and second locations, and wherein the detection of the vertical displacement comprises combining the two or more vertical displacements.

14. A robotic work vehicle, comprising: a movable work implement; a chassis with a motor that propels the work vehicle; a shroud that covers the chassis; a linkage that couples the shroud to the chassis, the linkage comprising: a rotating link that allows horizontal displacement between the shroud and the chassis; a lifting link that allows vertical displacement between the shroud and the chassis, the lifting link pivotably attached to the rotating link and to the chassis; a lift sensor that detects the vertical displacement via the lifting link and the rotating link; and a controller coupled to the work implement and the lift sensor, the controller operable to, in response to detection of the vertical displacement, stop the work implement.

15. The work vehicle of claim 14, wherein the lifting link comprises at least two parallel arms having first ends pivotably attached to the shroud and second ends pivotably attached to the chassis.

16. The work vehicle of claim 15, wherein the first ends of the parallel arms are attached to the shroud via the rotating link, the rotating link being attached to the shroud.

17. The work vehicle of claim 15 or 16, wherein the first ends of the parallel arms are attached to an end housing that holds the rotating link, the rotating link being attached to the shroud.

18. The work vehicle of claim 17, wherein the rotating link comprises an elongated member, the elongated member comprising: a mount end attached to the shroud; and a distal end opposed to the mount end and rotatably attached to the end housing via a ball and socket joint, the lift sensor detecting movement of the end housing in response to the vertical displacement.

19. A method, comprising: coupling a shroud to a chassis of a robotic work vehicle via a linkage, the linkage comprising a rotating link and a lifting link that respectively allow horizontal and vertical displacement between the shroud and the chassis; detecting the vertical displacement via a first sensor of the linkage; in response to detection of the vertical displacement, stop a work implement of the robotic work vehicle.

20. The method of claim 19, further comprising: detecting the horizontal displacement via a second sensor of the linkage; and in response to detecting the horizontal displacement, register a bump event with a navigation system

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