Work Machine, System Including Work Machine, and Method of Controlling Work Machine

The present disclosure relates to a work machine, a system including a work machine, and a method of controlling a work machine.

WO2016/152994 (PTL 1) discloses control to move a boom and a bucket to target positions obtained in accordance with a moving distance of a wheel loader when the wheel loader is in a state of unloaded rearward travel in which the wheel loader travels rearward with the bucket being unloaded.

PTL 1: WO2016/152994

A wheel loader that repeatedly performs an excavation work and a loading work has been demanded to reliably eject loads loaded in a bucket from the bucket in the loading work.

The present disclosure proposes a work machine, a system including a work machine, and a method of controlling a work machine that allow reliable ejection of loads loaded in a bucket in a loading work.

Each of a work machine and a system including the work machine according to one aspect of the present disclosure includes a main body of a work machine, a work implement, a work implement actuator, a travel sensor, a work implement posture sensor, an object sensor, and a controller. The main body of the work machine includes a travel unit. The work implement is attached in front of the main body of the work machine. The work implement includes a bucket at a tip end. The work implement actuator drives the work implement with respect to the main body of the work machine. The travel sensor detects a state of travel of the travel unit. The work implement posture sensor detects a posture of the work implement. The object sensor detects an object around the main body of the work machine. The controller provides a command to drive the work implement actuator based on detection values from the travel sensor, the work implement posture sensor, and the object sensor. The controller recognizes a loading target into which loads in the bucket are to be loaded, based on detection of the object. The controller controls the work implement actuator and the travel unit such that the bucket is in a full dump state while a feature point of the bucket is located above the loading target and such that the travel unit travels rearward with the full dump state being maintained.

A method of controlling a work machine according to one aspect of the present disclosure includes recognizing a loading target into which loads in a bucket are to be loaded, based on an object detection signal, moving a feature point of the bucket to above the loading target, setting the bucket into a full dump state while the feature point is located above the loading target, and controlling a travel unit to travel rearward with the full dump state being maintained.

According to the work machine, the system including the work machine, and the method of controlling the work machine in the present disclosure, loads loaded in the bucket can reliably be ejected in the loading work.

An embodiment will be described below with reference to the drawings. The same components and constituent elements in the description below have the same reference characters allotted and their labels and functions are also the same. Therefore, detailed description thereof will not be repeated. Extraction of any features from the embodiment and any combination thereof are also originally intended.

In an embodiment, a wheel loaderas an exemplary work machine will be described.is a side view of wheel loaderas an exemplary work machine.

As shown in, wheel loaderincludes a vehicular body frame, a work implement, a travel apparatus, and a cab. A vehicular body of wheel loaderis composed of vehicular body frame, cab, and the like. Work implementand travel apparatusare attached to the vehicular body of wheel loader. A main body of wheel loaderincludes the vehicular body and travel apparatus.

Travel apparatusserves for travel of the vehicular body of wheel loaderand includes running wheelsandWheel loaderis a wheeled vehicle provided with running wheelsandas rotational bodies for travel, on opposing sides in a lateral direction of the vehicular body. Wheel loaderis self-propelled as running wheelsandare rotationally driven and can perform desired works with work implement. Travel apparatuscorresponds to an exemplary “travel unit.”

A direction in which wheel loadertravels straight is herein referred to as a fore/aft direction of wheel loader. In the fore/aft direction of wheel loader, a side where work implementis arranged with respect to vehicular body frameis defined as the fore direction and a side opposite to the fore direction is defined as the aft direction. The lateral direction of wheel loaderrefers to a direction orthogonal to the fore/aft direction when wheel loaderon a flat ground is viewed in a plan view.

A right side and a left side in the lateral direction when one faces the fore direction are defined as a right direction and a left direction, respectively. An upward/downward direction of wheel loaderis a direction orthogonal to the plane defined by the fore/aft direction and the lateral direction. A side where the ground is located and a side where the sky is located in the upward/downward direction are defined as a lower side and an upper side, respectively.

Vehicular body frameincludes a front frameand a rear frameFront frameis arranged in front of rear frameFront frameand rear frameare attached to each other as being laterally swingable.

A pair of steering cylindersis attached across front frameand rear frameSteering cylinderis a hydraulic cylinder. As steering cylinderextends and contracts with hydraulic oil from a steering pump, a direction of travel of wheel loaderlaterally changes. Vehicular body framein an articulated structure is composed of front frameand rear frameWheel loaderis an articulated work machine in which front frameand rear frameare coupled to allow a flection operation.

Work implementand a pair of running wheels (front wheels)are attached to front frameWork implementis attached in front of the main body of wheel loader. Work implementis supported by the vehicular body of wheel loader. Work implementincludes a boomand a bucket. Bucketis arranged at a tip end of work implement. Bucketis a work tool for excavation and loading. A cutting edgeis a tip end portion of bucket. A rear surfaceis a part of an outer surface of bucket. Rear surfaceis formed from a plane. Rear surfaceextends rearward from cutting edge

Boomhas a base end portion rotatably attached to front frameby a boom pin. Bucketis rotatably attached to boomby a bucket pinlocated at a tip end of boom. Boom pinand bucket pincorrespond to “a plurality of articulations” of work implement.

Work implementfurther includes a bell crankand a link. Bell crankis rotatably supported on boomby a support pinlocated substantially in a center of boom. Linkis coupled to a coupling pinprovided at a tip end portion of bell crank. Linkcouples bell crankand bucketto each other.

Front frameand boomare coupled to each other by a pair of boom cylinders. Boom cylinderis a hydraulic cylinder. Boom cylinderrotationally drives boomupward and downward around boom pin. Boom cylinderhas a base end attached to front frameBoom cylinderhas a tip end attached to boom. Boom cylinderis a hydraulic actuator that operates boomupward and downward with respect to front frameWith movement upward and downward of boom, bucketattached at the tip end of boomalso moves upward and downward.

A bucket cylindercouples bell crankand front frameto each other. Bucket cylinderhas a base end attached to front frameBucket cylinderhas a tip end attached to a coupling pinprovided at a base end portion of bell crank. Bucket cylinderis a hydraulic actuator to cause bucketto pivot upward and downward with respect to boom. Bucket cylinderis a work tool cylinder that drives bucket. Bucket cylinderrotationally drives bucketaround bucket pin. Bucketis constructed as being operable with respect to boom. Bucketis constructed as being operable with respect to front frame

Boom cylinderand bucket cylindercorrespond to an exemplary “work implement actuator” that drives work implement.

Cabon which an operator rides and a pair of running wheels (rear wheels)are attached to rear frameCabin a box shape is arranged in the rear of boom. Cabis carried on vehicular body frame. In cab, a seat where the operator of wheel loaderis seated, an operation apparatuswhich will be described later, and the like are arranged.

is a block diagram showing an overall configuration of a control system that controls wheel loader.

An engineis a drive source that generates drive force to drive work implementand travel apparatus, and it is, for example, a diesel engine. A motor driven by a power storage, instead of engine, may be employed as the drive source, or both of the engine and the motor may be employed. Output from engineis controlled by adjustment of an amount of fuel to be injected into a cylinder of engine.

Drive force generated by engineis transmitted to a transmission. Transmissionconverts drive force into appropriate torque and a rotation speed. An axleis connected to an output shaft of transmission. Drive force converted by transmissionis transmitted to axle. Drive force is transmitted from axleto running wheelsand(). Wheel loaderthus travels. In wheel loaderin the embodiment, both of running wheeland running wheelimplement drive wheels for travel of wheel loaderupon receiving drive force.

Some of drive force from engineis transmitted to a work implement pump. Work implement pumpis a hydraulic pump driven by engineto activate work implementwith hydraulic oil it delivers. Work implementis driven by hydraulic oil from work implement pump. Hydraulic oil delivered by work implement pumpis supplied to boom cylinderand bucket cylinderthrough a main valve. As boom cylinderextends and contracts upon receiving supply of hydraulic oil, boommoves upward and downward. As bucket cylinderextends and contracts upon receiving supply of hydraulic oil, bucketpivots upward and downward.

Wheel loaderincludes a vehicular body controller. Vehicular body controllerincludes an engine controller, a transmission controller, and a work implement controller.

Vehicular body controlleris generally implemented by reading of various programs by a central processing unit (CPU). Vehicular body controllerincludes a not-shown memory. The memory functions as a work memory, and various programs for performing functions of wheel loaderare stored in the memory.

Operation apparatusis provided in cab. Operation apparatusis operated by an operator. Operation apparatusincludes a plurality of types of operation members operated by the operator to operate wheel loader. Operation apparatusincludes an accelerator pedaland a work implement control lever. Operation apparatusmay include a steering wheel, a shift lever, and the like which are not shown.

Accelerator pedalis operated to set the target number of rotations of engine. Engine controllercontrols output from enginebased on an amount of operation onto accelerator pedal. With increase in amount of operation (amount of pressing) onto accelerator pedal, output from engineincreases. With decrease in amount of operation onto accelerator pedal, output from enginedecreases. Transmission controllercontrols transmissionbased on the amount of operation onto accelerator pedal.

Work implement control leveris operated to operate work implement. Work implement controllercontrols electromagnetic proportional control valvesandbased on the amount of operation onto work implement control lever.

Electromagnetic proportional control valveswitches main valvesuch that bucket cylindercontracts to move bucketin a dump direction (a direction in which the cutting edge of bucketis lowered). Electromagnetic proportional control valveswitches main valvesuch that bucket cylinderextends to move bucketin a tilt direction (a direction in which the cutting edge of bucketis raised). Electromagnetic proportional control valveswitches main valvesuch that boom cylindercontracts to lower boom. Electromagnetic proportional control valveswitches main valvesuch that boom cylinderextends to raise boom.

A machine monitorshows various types of information upon receiving input of a command signal from vehicular body controller. The various types of information shown on machine monitormay be, for example, information on works performed by wheel loader, vehicular body information such as an amount of remaining fuel, a temperature of coolant, and a temperature of hydraulic oil, an image of surroundings obtained by image pick-up of the surroundings of wheel loader, and the like. Machine monitormay be implemented by a touch panel, and in this case, a signal generated by touching by the operator onto a part of machine monitoris outputted from machine monitorto vehicular body controller.

Wheel loaderin the present embodiment performs excavation and loading works to scoop an excavation target such as soil and to load the excavation target onto a loading target such as a dump truck.is a plan view of wheel loaderthat performs excavation and loading works.illustrates wheel loaderthat performs what is called a V shape work.

(A) illustrates wheel loaderthat performs what is called unloaded forward travel. Wheel loadertravels forward along an excavation path Rtoward an excavation targetsuch as soil. Wheel loaderplunges bucketinto excavation targetand stops forward travel. By raising bucketwith cutting edgeof bucketdug into excavation target, the excavation work to scoop excavation targetin bucketis performed.

(B) illustrates wheel loaderthat performs what is called loaded rearward travel. Excavation targethas been loaded in bucket. Wheel loadertravels rearward along excavation path Rto a position from which it started forward travel in(A).

(C) illustrates wheel loaderthat performs what is called loaded forward travel. With excavation targethaving been loaded in bucket, wheel loadertravels forward toward a vesselof a dump truck. Wheel loadertravels forward along a loading path Rfrom the position where it started forward travel in(A) toward dump truck. When wheel loaderapproaches dump truckand reaches a prescribed position, it loads excavation targetin bucketinto vessel. Vesselcorresponds to an exemplary “loading target” into which loads in bucketare to be loaded.

(D) illustrates wheel loaderthat performs what is called unloaded rearward travel. While bucketis empty as a result of full ejection of excavation targetin bucketinto vesselof dump truck, wheel loadertravels rearward along loading path Rto the position where it started forward travel in(C).

Wheel loadercan thus repeatedly perform a series of works including excavation, rearward travel, dump approach, soil ejection, and rearward travel.

In automating a loading work for loading onto dump truckby wheel loader, in order to more quickly perform the loading work while an amount of works is ensured without contact of bucketwith vessel, reproduction of operations of work implementby a skilled operator under automatic control has been desired.is a block diagram showing a configuration of an automatic control system that controls wheel loader.

An automation controlleris configured to transmit and receive a signal to and from vehicular body controllerdescribed with reference to. Automation controlleris configured to transmit and receive a signal to and from an external information obtaining unit. External information obtaining unitincludes a perception deviceand a positional information obtaining device. Perception deviceand positional information obtaining deviceare mounted on wheel loader.

Perception deviceobtains information on surroundings of wheel loader. Perception deviceis attached, for example, to an upper front surface of cab. Perception devicecorresponds to an exemplary “object sensor” that detects an object around the main body of wheel loader.

Perception devicecontactlessly detects a direction of an object outside wheel loaderand a distance to the object. Perception deviceis implemented, for example, by light detection and ranging (LiDAR) that obtains information on an object by emission of laser beams. Perception devicemay be implemented by a visual sensor including a camera. Perception devicemay be implemented by radio detection and ranging (Radar) that obtains information on an object by emission of radio waves. Perception devicemay be implemented by an infrared sensor.

Positional information obtaining deviceobtains information on a current position of wheel loader. Positional information obtaining deviceobtains, for example, positional information of wheel loaderin a global coordinate system with the Earth being defined as a reference, with the use of a satellite positioning system.

Positional information obtaining deviceuses, for example, global navigation satellite systems (GNSS) and includes a GNSS receiver. The satellite positioning system calculates a position of wheel loaderby computing a position of an antenna of the GNSS receiver based on a positioning signal received from a satellite by the GNSS receiver.

External information on the outside of wheel loaderobtained by perception deviceand positional information of wheel loaderobtained by positional information obtaining deviceare inputted to automation controller.

Vehicular body controlleris configured to transmit and receive a signal to and from a vehicle information obtaining unit, and receives input of information on wheel loaderobtained by vehicle information obtaining unit. Vehicle information obtaining unitis composed of various sensors mounted on wheel loader. Vehicle information obtaining unitincludes an articulation angle sensor, a vehicle speed sensor, a boom angle sensor, a bucket angle sensor, and a boom cylinder pressure sensor.

Articulation angle sensordetects an articulation angle which is an angle formed between front frameand rear frameand generates a signal indicating the detected articulation angle. Articulation angle sensoroutputs a signal indicating the articulation angle to vehicular body controller.

Vehicle speed sensordetects a speed of movement of wheel loaderby travel apparatus, for example, by detection of a rotation speed of an output shaft of transmissionand generates a signal indicating the detected vehicle speed. Vehicle speed sensoroutputs the signal indicating the vehicle speed to vehicular body controller. Vehicle speed sensorcorresponds to an exemplary “travel sensor” that detects a status of travel of travel apparatus(travel unit).