Patent Description:
There is proposed a work machine operation circuit capable of preventing, in a work machine such as a hydraulic excavator, a malfunction after a gate lock lever is operated to release shutoff by an operation stop device (see, for example, Patent Literature <NUM>).

There is proposed a construction machine emergency stop system capable of grasping a situation of a machine and determining whether or not it is an emergency shutoff even at emergency stop (see, for example, Patent Literature <NUM>). According to this system, power is supplied to each piece of electronic equipment if an ignition switch is in a closed state. Further, a second piece of electronic equipment is capable of making a work machine stop instruction to cause a work machine stop unit to stop operation of a work machine and an engine stop instruction to cause a first piece of electronic equipment to stop its engine in a state in which power is supplied to each piece of electronic equipment.

There is proposed a novel work machine remote manipulation system capable of, when an abnormality occurs in a communication unit, quickly and easily identifying a position where the abnormality has occurred (see, for example, Patent Literature <NUM>). According to this system, if a piece of equipment for which it is diagnosed that an abnormality has occurred is a piece of equipment that does not influence operations of a hydraulic system and an engine system, the work machine is controlled to be into a stand-by state. Therefore, if the piece of equipment is a piece of video/audio equipment, such a situation that an operator operates the work machine in a state of not being able to see video is avoided. Furthermore, when the stand-by state continues for a predetermined time, the engine of the work machine is stopped, so it is avoided that an unexpected situation occurs in a state that there is a possibility that the stand-by state continues for a long time. Another assistance method is described in <CIT>.

However, if an engine stop instruction is made for an unexpected reason, and the engine of a work machine is stopped even if an operator has an intention to continue a remote operation of the work machine, it is necessary for the operator to restart the engine, and there is a possibility that work efficiency is reduced accordingly.

Therefore, an object of the present invention is to provide a technology capable of improving work efficiency of a work machine that is remotely operated by an operator through a remote operation apparatus.

A remote operation assistance server of the present invention comprises: a first assistance processing element which, based on communication with a remote operation apparatus for remotely operating a work machine, recognizes satisfiability of each of a first condition that an engine stop instruction for the work machine has been made through an input interface of the remote operation apparatus and a second condition that a probability of an intention of an operator of the remote operation apparatus to cause an engine of the work machine to stop being reflected on the engine stop instruction is high; and a second assistance processing element which, if it is recognized by the first assistance processing element that the first and second conditions are satisfied, executes first stop processing for causing operation of a work mechanism to stop without causing operation of the engine of the work machine to stop, based on communication with the work machine, and, if it is recognized by the first assistance processing element that the first condition is satisfied but the second condition is not satisfied, executes second stop processing for causing the operation of each of the work mechanism and the engine of the work machine to stop, based on communication with the work machine.

According to the remote operation assistance server in the above configuration, if the first condition is satisfied, that is, if the engine stop instruction for the work machine has been made through the input interface of the remote operation apparatus, the operation of the engine is stopped in principle, but the operation of the engine is exceptionally not stopped.

Specifically, if the second condition is not satisfied, that is, if the probability of the operator's intention to cause the engine to stop and, therefore, the operator's intention to interrupt the remote operation being reflected on the engine stop instruction is high, the operation of the engine is stopped according to the engine stop instruction. Thereby, such a situation is certainly avoided that the operation stop state of the work mechanism is accidentally released by a third person other than the operator, and work by the work machine is resumed.

On the other hand, if the second condition is satisfied, that is, if the probability of the operator's intention to cause the engine to stop and, therefore, the operator's intention to interrupt the remote operation being reflected on the engine stop instruction is low, the operation of the engine is continued without being stopped even though the engine stop operation instruction is made. Thereby, the operation stop state of the work mechanism is released by the operator in that state, and the work by the work machine can be quickly resumed. Thus, efficiency of work using the work machine can be improved.

A remote operation assistance system as an embodiment of the present invention shown in <FIG> comprises a remote operation assistance server <NUM> and a work machine <NUM>. A remote operation apparatus <NUM> (a client) for performing a remote operation of the work machine <NUM> may be a component of the remote operation assistance system. The remote operation assistance server <NUM>, the remote operation apparatus <NUM> and the work machine <NUM> are configured to be capable of mutually performing network communication. A mutual communication network between the remote operation assistance server <NUM> and the remote operation apparatus <NUM> and a mutual communication network between the remote operation assistance server <NUM> and the work machine <NUM> may be the same or may be different.

The remote operation assistance server <NUM> comprises a database <NUM>, a first assistance processing element <NUM> and a second assistance processing element <NUM>. The database <NUM> stores and holds picked-up image data and the like. The database <NUM> may be constituted by a database server separate from the remote operation assistance server <NUM>. Each assistance processing element is constituted by an arithmetic processing device (a single-core processor, a multi-core processor or a processor core constituting the multi-core processor), and reads necessary data and software from a storage device such as a memory and executes arithmetic processing described later according to the software for the data. The remote operation assistance server <NUM> may be constituted by the remote operation apparatus <NUM>. In this case, a remote control device <NUM> comprises the first assistance processing element <NUM> and the second assistance processing element <NUM>.

The remote operation apparatus <NUM> comprises the remote control device <NUM>, a remote input interface <NUM> and a remote output interface <NUM>. The remote operation apparatus <NUM> functions as at least one of "a first client" and "a second client". The remote control device <NUM> is constituted by an arithmetic processing device (a single-core processor, a multi-core processor or a processor core constituting the multi-core processor), and reads necessary data and software from a storage device such as a memory and executes arithmetic processing according to the software for the data. The remote input interface <NUM> comprises a remote operation mechanism <NUM> and an operator state sensor <NUM>. The remote output interface <NUM> comprises an image output device <NUM> and remote wireless communication equipment <NUM>.

The remote operation mechanism <NUM> includes a travel operation device, a turning operation device, a boom operation device, an arm operation device and a bucket operation device. Each operation device has an operation lever to receive a rotation operation. The operation lever of the travel operation device (a travel lever) is operated to move a lower travel body <NUM> of the work machine <NUM>. The travel lever may also serve as a travel pedal. For example, a travel pedal fixed to the base or lower end part of the travel lever may be provided. The operation lever of the turning operation device (a turning lever) is operated to move a hydraulic turning motor constituting a turning mechanism <NUM> of the work machine <NUM>. The operation lever of the boom operation device (a boom lever) is operated to move a boom cylinder <NUM> of the work machine <NUM>. The operation lever of the arm operation device (an arm lever) is operated to move an arm cylinder <NUM> of the work machine <NUM>. The operation lever of the bucket operation device (a bucket lever) is operated to move a bucket cylinder <NUM> of the work machine <NUM>.

The operation levers constituting the remote operation mechanism <NUM> are arranged, for example, around a seat St for an operator to be seated as shown in <FIG>. Though the seat St is in a form like a high back chair with armrests, it may be a seating part in an arbitrary form on which an operator can sit, such as a form like a low back chair without a headrest or a form like a chair without a backrest.

In front of the seat St, a pair of left and right travel levers <NUM> corresponding to left and right crawlers are arranged left and right, side by side. One operation lever may serve as a plurality of operation levers. For example, a left-side operation lever <NUM> provided in front of a left-side frame of the seat St shown in <FIG> may function as an arm lever when operated in a front/back direction and function as a turning lever when operated in a left-right direction. Similarly, a right-side operation lever <NUM> provided in front of a right-side frame of the seat St shown in <FIG> may function as a boom lever when operated in the front/back direction and function as a bucket lever when operated in the left-right direction. The lever patterns may be arbitrarily changed by an operation instruction by an operator.

A shutoff lever <NUM> provided below the left-side operation lever <NUM> in front of the left-side frame of the seat St functions as an operation lever for, when being raised, locking the work machine <NUM> so that the work machine <NUM> does not move even if each of the operation levers <NUM>, <NUM> and <NUM> is operated and, when being lowered, releasing the lock.

In the present embodiment, the operator state sensor <NUM> comprises a load sensor (for example, a strain gauge) provided on a part of the seat St (for example, the seating part, an armrest or the backrest) or on a support member of the seat St. It can be determined whether an operator is seated on or away from the seat St according to whether a load detected by the load sensor is large or small or whether there is a load or not. In addition, the operator state sensor <NUM> may comprise contact sensors or load sensors provided on at least a part of the operation levers constituting the remote operation mechanism <NUM>. The operator state sensor <NUM> may comprise an image pickup sensor for recognizing the face or facial expression of a person who is seated on the seat St.

For example, as shown in <FIG>, the image output device <NUM> comprises a central image output device <NUM>, a left-side image output device <NUM> and a right-side image output device <NUM> that are arranged in front of, diagonally forward left of and diagonally forward right of the seat St, respectively, each of the image output devices having an almost rectangular-shaped screen. The shapes and sizes of the screens (image display areas) of the central image output device <NUM>, the left-side image output device <NUM> and the right-side image output device <NUM> may be the same or may be different.

As shown in <FIG>, the right edge of the left-side image output device <NUM> adjoins the left edge of the central image output device <NUM> such that the screen of the central image output device <NUM> and the screen of the left-side image output device <NUM> form a tilt angle θ1 (for example, <NUM>°≤θ1≤<NUM>°). As shown in <FIG>, the left edge of the right-side image output device <NUM> adjoins the right edge of the central image output device <NUM> such that the screen of the central image output device <NUM> and the screen of the right-side image output device <NUM> form a tilt angle θ2 (for example, <NUM>°≤θ2≤<NUM>°). The tilt angles θ1 and θ2 may be the same or different.

Each of the screens of the central image output device <NUM>, the left-side image output device <NUM> and the right-side image output device <NUM> may be parallel to the vertical direction or may be inclined relative to the vertical direction. At least one image output device among the central image output device <NUM>, the left-side image output device <NUM> and the right-side image output device <NUM> may comprise a plurality of divided image output devices. For example, the central image output device <NUM> may comprise a pair of image output devices that vertically adjoin each other, each of the image output devices having an almost rectangular-shaped screen. Each of the image output devices <NUM> to <NUM> may further comprise a speaker (a voice output device).

The work machine <NUM> comprises a work machine control device <NUM>, a work machine input interface <NUM>, a work machine output interface <NUM>, a work mechanism <NUM> and an engine <NUM>. The work machine control device <NUM> is constituted by an arithmetic processing device (a single-core processor, a multi-core processor or a processor core constituting the multi-core processor), and reads necessary data and software from a storage device such as a memory and executes arithmetic processing according to the software for the data.

The work machine <NUM> is, for example, a crawler shovel (a construction machine) and comprises the crawler-type lower travel body <NUM>, an upper turning body <NUM> that is turnably mounted on the lower travel body <NUM> via the turning mechanism <NUM> as shown in <FIG>. On the front left side part of the upper turning body <NUM>, a cab <NUM> (a driving room) is provided. On the front center part of the upper turning body <NUM>, the work mechanism <NUM> is provided.

The work machine input interface <NUM> comprises a work machine operation mechanism <NUM>, a work machine image-pickup device <NUM> and a positioning device <NUM>. The work machine operation mechanism <NUM> comprises a plurality of operation levers arranged similarly to those of the remote operation mechanism <NUM> around a seat arranged inside the cab <NUM>. A driving mechanism or a robot that receives a signal corresponding to an operation aspect of a remote operation lever and moves a work machine operation lever based on the received signal is provided in the cab <NUM>. The work machine image-pickup device <NUM> is installed, for example, inside the cab <NUM> and picks up an image of an environment that includes at least a part of the work mechanism <NUM> through a front window and a pair of left and right side windows. A part or all of the front window and the side windows may be omitted. The positioning device <NUM> comprises a GPS, and, as necessary, a gyro sensor and the like.

The work machine output interface <NUM> comprises work machine wireless communication equipment <NUM>.

The work mechanism <NUM> comprises a boom <NUM> fitted to the upper turning body <NUM> in a manner of being capable of being raised and fallen, an arm <NUM> rotatably coupled with the tip of the boom <NUM> and a bucket <NUM> rotatably coupled with the tip of the arm <NUM>. To the work mechanism <NUM>, the boom cylinder <NUM>, the arm cylinder <NUM> and the bucket cylinder <NUM> that comprise telescopic hydraulic cylinders are fitted.

The boom cylinder <NUM> is interposed between the boom <NUM> and the upper turning body <NUM> so as to, by extending and retracting by receiving supply of hydraulic oil, cause the boom <NUM> to rotate in a direction of being raised and fallen. The arm cylinder <NUM> is interposed between the arm <NUM> and the boom <NUM> so as to, by extending and retracting by receiving supply of hydraulic oil, cause the arm <NUM> to rotate around a horizontal axis relative to the boom <NUM>. The bucket cylinder <NUM> is interposed between the bucket <NUM> and the arm <NUM> so as to, by extending and retracting by receiving supply of hydraulic oil, cause the bucket <NUM> to rotate around a horizontal axis relative to the arm <NUM>.

In a state in which the engine <NUM> is ON, hydraulic oil can be supplied from a main pump to a plurality of direction control valves, and primary pressure oil can be supplied from a pilot pump to the work machine operation mechanism <NUM>. By secondary pressure oil being supplied to a direction control valve according to a movement corresponding to a remote operation instruction of the work machine operation mechanism <NUM> and hydraulic oil being supplied to a hydraulic cylinder corresponding to operation of the direction control valve, the turning mechanism <NUM> and the work mechanism <NUM> operate.

A first function of the remote operation assistance system in the above configuration will be described using a flowchart shown in <FIG>. In the flowchart, each block indicated by "C•" is used to simplify description, means transmission and/or reception of data and means such a conditional branch that processing in a branch direction is executed on condition of transmission and/or reception of the data.

In the remote operation apparatus <NUM>, it is determined whether a specification operation through the remote input interface <NUM> by an operator has been performed or not (<FIG>/STEP <NUM>). The "specification operation" is, for example, an operation such as tapping on the remote input interface <NUM> for specifying the work machine <NUM> that the operator intends to remotely operate. If a result of the determination is negative (<FIG>/STEP <NUM>: NO), a process after the determination about whether the specification operation has been performed or not is repeated. On the other hand, if the result of the determination is positive (<FIG>/STEP <NUM>: YES), an environment confirmation request is transmitted to the remote operation assistance server <NUM> through the remote wireless communication equipment <NUM> (<FIG>/STEP <NUM>).

In the remote operation assistance server <NUM>, when the environment confirmation request is received, the environment confirmation request is transmitted to the corresponding work machine <NUM> by the first assistance processing element <NUM> (<FIG>/C110).

In the work machine <NUM>, when the environment confirmation request is received through the work machine wireless communication equipment <NUM> (<FIG>/C410), the work machine control device <NUM> acquires a picked-up image through the work machine image-pickup device <NUM> (<FIG>/STEP <NUM>). Picked-up image data indicating the picked-up image is transmitted to the remote operation apparatus <NUM> by the work machine control device <NUM> through the work machine wireless communication equipment <NUM> (<FIG>/STEP <NUM>).

In the remote operation assistance server <NUM>, when the picked-up image data is received by the first assistance processing element <NUM> (<FIG>/C111), environment image data according to the picked-up image is transmitted to the remote operation apparatus <NUM> by the second assistance processing element <NUM> (<FIG>/STEP <NUM>). The environment image data is, in addition to the picked-up image data itself, image data indicating a simulated environment image generated based on the picked-up image.

In the remote operation apparatus <NUM>, when the environment image data is received through the remote wireless communication equipment <NUM> (<FIG>/C210), an environment image corresponding to the environment image data is outputted to the image output device <NUM> by the remote control device <NUM> (<FIG>/STEP <NUM>).

Thereby, for example, as shown in <FIG>, an environment image with the boom <NUM>, the arm <NUM> and the bucket <NUM>, which are parts of the work mechanism <NUM>, being reflected therein is outputted to the image output device <NUM>.

In the remote operation apparatus <NUM>, an operation aspect of the remote operation mechanism <NUM> is recognized by the remote control device <NUM> (<FIG>/STEP <NUM>), and a remote operation instruction corresponding to the operation aspect is transmitted to the remote operation assistance server <NUM> through the remote wireless communication equipment <NUM> (<FIG>/STEP <NUM>).

In the remote operation assistance server <NUM>, when the remote operation instruction is received by the second assistance processing element <NUM>, the remote operation instruction is transmitted to the work machine <NUM> by the first assistance processing element <NUM> (<FIG>/C112).

In the work machine <NUM>, when the remote operation instruction is received by the work machine control device <NUM> through the work machine wireless communication equipment <NUM> (<FIG>/C412), operations of the work mechanism <NUM> and the like are controlled (<FIG>/STEP <NUM>). Thereby, a remote operation of the work machine <NUM> is started. For example, work of scooping dirt in front of the work machine <NUM> by the bucket <NUM>, causing the upper turning body <NUM> to turn and dropping the dirt from the bucket <NUM> is executed.

A second function of the remote operation assistance system in the configuration described before will be described using a flowchart shown in <FIG>. In the flowchart, each block indicated by "C•" is used to simplify description, means transmission and/or reception of data and means such a conditional branch that processing in a branch direction is executed on condition of transmission and/or reception of the data.

In the remote operation apparatus <NUM>, it is determined whether a first specification operation through the remote input interface <NUM> by an operator has been performed or not (<FIG>/STEP <NUM>). The "first specification operation" is, for example, an operation such as tapping on the remote input interface <NUM> for causing the engine <NUM> of the work machine <NUM> to start, such as switching an IGN switch from OFF to ON. If a result of the determination is negative (<FIG>/STEP <NUM>: NO), a process after the determination about whether the first specification operation has been performed or not is repeated. On the other hand, if the result of the determination is positive (<FIG>/STEP <NUM>: YES), an engine operation instruction is transmitted to the remote operation assistance server <NUM> through the remote wireless communication equipment <NUM> (<FIG>/STEP <NUM>). The engine operation instruction includes a work machine identifier for identifying the work machine <NUM> specified through the remote input interface <NUM>.

In the remote operation assistance server <NUM>, when the engine operation instruction is received, the engine operation instruction is transmitted to the work machine <NUM> identified by the work machine identifier by the first assistance processing element <NUM> (<FIG>/C120).

In the work machine <NUM>, when the engine operation instruction is received through the work machine wireless communication equipment <NUM> (<FIG>/C420), the engine <NUM> of the work machine <NUM> is switched from OFF to ON by the work machine control device <NUM>, and the work mechanism <NUM> is switched from a locked state in which operation is impossible to an unlocked state in which operation is possible, according to the operation instruction (<FIG>/STEP <NUM>). Thereby, for example, the primary pressure oil supplied from the pilot pump can be supplied to a direction control valve as the secondary pressure oil (by the operation aspect of the work machine operation mechanism <NUM> being adjusted by an actuator) according to the remote operation instruction, and, therefore, the work mechanism <NUM> is into the state in which operation is possible as described above (see <FIG>/STEP <NUM>→STEP <NUM>→. →STEP <NUM>, and <FIG>).

In the remote operation apparatus <NUM>, it is determined whether a second specification operation through the remote input interface <NUM> by the operator has been performed or not (<FIG>/STEP <NUM>). The "second specification operation" is, for example, an operation such as tapping on the remote input interface <NUM> for causing operation of the engine <NUM> of the work machine <NUM> to stop, such as switching the IGN switch from ON to OFF. If a result of the determination is negative (<FIG>/STEP <NUM>: NO), a process after the determination about whether the first specification operation has been performed or not is repeated. On the other hand, if the result of the determination is positive (<FIG>/STEP <NUM>: YES), an engine stop instruction is transmitted to the remote operation assistance server <NUM> through the remote wireless communication equipment <NUM> (<FIG>/STEP <NUM>). The engine stop operation instruction includes the work machine identifier for identifying the work machine <NUM> specified through the remote input interface <NUM>.

In the remote operation assistance server <NUM>, when the engine stop instruction is received (<FIG>/C121), an operator state request is transmitted to the remote operation apparatus <NUM> by the first assistance processing element <NUM> (<FIG>/STEP <NUM>). The engine stop instruction being received is synonymous with the first condition being satisfied.

In the remote operation apparatus <NUM>, when the operator state request is received through the remote wireless communication equipment <NUM> (<FIG>/C221), an operator state is detected by the remote control device <NUM> based on an output signal of the operator state sensor <NUM> (<FIG>/STEP <NUM>). For example, whether or not the operator exists at a specified position where the operator should exist at the time of operating the remote operation mechanism <NUM>, such as whether or not the operator is seated on the seat St, is detected as the operator state. Then, the detected operator state is transmitted to the remote operation assistance server <NUM> through the remote wireless communication equipment <NUM> (<FIG>/STEP <NUM>).

When it is determined that the second specification operation has been performed (<FIG>/STEP <NUM>: YES), the operator state may be detected by the remote control device <NUM> based on an output signal of the operator state sensor <NUM> even if the operator state request is not made (<FIG>/STEP <NUM>), and the detected operator state may be transmitted to the remote operation assistance server <NUM> together with an engine stop instruction through the remote wireless communication equipment <NUM> (<FIG>/STEP <NUM>).

In the remote operation assistance server <NUM>, when the operator state is received (<FIG>/C122), it is determined by the first assistance processing element <NUM> whether a second condition is satisfied or not based on the operator state (<FIG>/STEP <NUM>). That is, it is determined whether or not the operator exists at a specified position where the operator should exist at the time of operating the remote operation mechanism <NUM>.

If a result of the determination is positive, that is, if the first and second conditions are satisfied (<FIG>/STEP <NUM>: YES), a first stop instruction is transmitted to the work machine <NUM> by the second assistance processing element <NUM> (<FIG>/STEP <NUM>).

In the work machine <NUM>, when the first stop instruction is received through the work machine wireless communication equipment <NUM> (<FIG>/C421), the engine <NUM> of the work machine <NUM> is kept ON, but the work mechanism <NUM> is switched from the unlocked state to the locked state, by the work machine control device <NUM> (<FIG>/STEP <NUM>). Thereby, supply of the primary pressure oil from the pilot lamp to the work machine operation mechanism <NUM> is prevented by a corresponding hydraulic circuit being shut off. Therefore, the work mechanism <NUM> is into the state in which operation is impossible even if a remote operation instruction is made.

If the result of the determination is negative, that is, if the first condition is satisfied but the second condition is not satisfied (<FIG>/STEP <NUM>: NO), a second stop instruction is transmitted to the work machine <NUM> by the second assistance processing element <NUM> (<FIG>/STEP <NUM>).

In the work machine <NUM>, when the second stop instruction is received through the work machine wireless communication equipment <NUM> (<FIG>/C422), the engine <NUM> of the work machine <NUM> is switched from ON to OFF, and the work mechanism <NUM> is switched from the unlocked state to the locked state, by the work machine control device <NUM> (<FIG>/STEP <NUM>). Thereby, the primary pressure oil is not supplied from the pilot pump to the work machine operation mechanism <NUM>, and the work mechanism <NUM> (and the turning mechanism <NUM>) is into the state in which operation is impossible even if the work machine operation mechanism <NUM> is moved according to a remote operation instruction.

According to the remote operation assistance server <NUM> in the above configuration, if the first condition is satisfied, that is, if an engine stop instruction for the work machine <NUM> has been made through the remote input interface <NUM> of the remote operation apparatus <NUM>, operation of the engine <NUM> is stopped in principle, but the operation of the engine <NUM> is exceptionally not stopped.

Specifically, if the second condition is not satisfied, that is, if the operator exists at the specified position at the time of operating the remote operation mechanism <NUM> in the remote operation apparatus <NUM>, the probability of the operator's intention to cause the engine <NUM> to stop and, therefore, the operator's intention to interrupt a remote operation being reflected on the engine stop instruction is high. Therefore, in this case, the operation of the engine <NUM> is stopped according to the engine stop instruction, and, thereby, such a situation is certainly avoided that the operation stop state of the work mechanism <NUM> (including the turning mechanism <NUM>) is accidentally released by a third person other than the operator, and work by the work machine <NUM> is resumed (see <FIG>/STEP <NUM>: NO→STEP <NUM>→. STEP <NUM>).

On the other hand, if the second condition is satisfied, that is, if the operator does not exist at the specified position at the time of operating the remote operation mechanism <NUM> in the remote operation apparatus <NUM>, the probability of the operator's intention to cause the engine <NUM> to stop and, therefore, the operator's intention to interrupt the remote operation being reflected on the engine stop instruction is low. Therefore, in this case, the operation of the engine <NUM> is continued without being stopped even though the engine stop operation instruction has been made, and, thereby, the operation stop state of the work machine <NUM> is released by the operator in that state, and the work by the work machine <NUM> can be quickly resumed. Thus, efficiency of work using the work machine <NUM> can be improved (see <FIG>/STEP <NUM>: YES->STEP <NUM>->. STEP <NUM>).

In the above embodiment, it is defined as the second condition that: (a) an operator does not exist at the specified position at the time of operating the remote operation mechanism <NUM> in the remote operation apparatus <NUM>. As another embodiment, however, at least one of the following may be defined alternatively or additionally as the second condition: an emergency stop switch provided on the remote operation apparatus <NUM> has been operated; (c) an operation abnormality has occurred in the remote operation apparatus <NUM>, the remote operation assistance server <NUM> or the work machine <NUM>; and (d) communication disconnection has occurred in the remote operation apparatus <NUM>, the remote operation assistance server <NUM> or the work machine <NUM>.

The first assistance processing element <NUM> recognizes satisfiability of the second condition that an operator does not exist at the specified position at the time of operating the remote operation mechanism <NUM> in the remote operation apparatus <NUM>, based on an output signal from a sensor for detecting that the operator is in contact with or applying a load on a specified structure provided at the specified position in the remote operation apparatus <NUM>.

When the operator is in contact with or applying a load on the specified structure provided at the specified position at the time of operating the remote operation mechanism <NUM> in the remote operation apparatus <NUM>, the probability of the operator's intension to cause the engine <NUM> to stop and, therefore, the operator's intension to interrupt a remote operation being reflected on an engine stop instruction is low. Therefore, in this case, the operation of the engine <NUM> is continued without being stopped even though the engine stop operation instruction has been issued, and, thereby, the operation stop state of the work mechanism is released by the operator in that state, and the work by the work machine <NUM> can be quickly resumed. Thus, efficiency of work using the work machine can be improved.

The first assistance processing element <NUM> recognizes the satisfiability of the second condition based on an output signal from the sensor <NUM> for detecting that the operator is seated on the seat St as the specified structure and applies a load. The first assistance processing element <NUM> recognizes the satisfiability of the second condition that the operator does not exist at the specified position at the time of operating the remote operation mechanism <NUM> in the remote operation apparatus <NUM>, based on an output signal from an image-pickup sensor for recognizing a face or facial expression of a person seated on the seat St provided at the specified position in the remote operation apparatus <NUM>.

Claim 1:
A remote operation assistance server comprising:
a first assistance processing element which, based on communication with a remote operation apparatus for remotely operating a work machine, recognizes satisfiability of each of a first condition that an engine stop instruction for the work machine has been made through an input interface of the remote operation apparatus and a second condition that a probability of an intention of an operator of the remote operation apparatus to cause an engine of the work machine to stop being reflected on the engine stop instruction is low; and
a second assistance processing element which, if it is recognized by the first assistance processing element that the first and second conditions are satisfied, executes first stop processing for causing operation of a work mechanism to stop without causing operation of the engine of the work machine to stop, based on communication with the work machine, and, if it is recognized by the first assistance processing element that the first condition is satisfied but the second condition is not satisfied, executes second stop processing for causing the operation of each of the work mechanism and the engine of the work machine to stop, based on communication with the work machine.