Patent Description:
With the recent spread of the Internet and the faster communication speed, efforts are being made to build remote control systems in various fields such as automobiles, drones, robots, and work machines for remote control via communication networks.

Among them, a work machine is remotely controlled as follows: a camera mounted on the work machine, which is the target device to be controlled, is used to capture an image of the target device and its surroundings, and the captured image is transmitted from the target device to a remote controller. An operator then monitors the image displayed on the remote controller for operation, and transmits the operated control signal from the remote controller to the target device to remotely control the target device. When the target device is used outdoors, a wireless communication network is often used between the target device and the communication network.

In the wireless communication network, however, data packet loss, a communication delay, and communication speed fluctuations may occur due to changes in received signal quality and communication line congestion. In this case, the stability or the operability of a remote control system for real-time control may deteriorate. For example, when the operator wants a front unit of a hydraulic excavator to move along the desired trajectory, a large communication delay in the wireless communication network, if any, may delay the image displayed on the monitor. In that case, the operator will not be able to accurately understand the actual state of the front unit. This makes it difficult to move the front unit accurately in real time, which may reduce the work efficiency. Studies have been made to enable stable remote control even when a communication delay or fluctuations in communication speed occur between the remote controller and the target device.

Patent Literature <NUM> describes a technique of solving the communication delay of a remote control system. This conventional technology describes a remote controller that remotely controls a target device via a communication network. The remove controller calculates the amount of overshoot, which may occur due to the communication delay time, from the communication delay time and the operating speed of the target device, and limits the operating speed so that the overshoot amount is less than a preset threshold.

When the technique described in Patent Literature <NUM> is applied to a work machine that needs to operate a plurality of actuators at the same time, the overshoot amount due to the communication delay is calculated and the threshold is set for each of the actuators. This means that if only one of the actuators has to be limited in the operating speed in a certain communication delay state, then only the specific actuator is decelerated, which causes off-balance in the combined operation of the work machine. That is, in the case of remote control of a plurality of actuators of a work machine, if an overshoot only for a specific actuator occurs due to a communication delay, the work machine will inefficiently operate in an unintended manner of the operator.

For example, assume that the work machine is performing excavation work with the boom, the arm, and the bucket. If an overshoot of the actual speed occurs only for the arm speed relative to the speed intended by the operator due to a communication delay time, only the commanded speed of the arm is limited so that the overshoot amount of the arm speed is less than a predetermined value. In this case, assuming that no overshoot due to the communication delay time occurs for the boom and the bucket, the commanded speeds of the boom and the bucket are not limited. As a result, only the arm speed is limited relative to the intended speed of the operator, which makes it impossible to operate the work machine as the operator intends, and worsens the operability.

Further, the remote control has a general problem: when the communication delay time becomes large, the difference between the state of the work machine viewed by the operator through the communication network with the camera and the state of the actual work machine becomes large. Therefore, the work machine may operate in a significantly different manner from the intention of the operator.

In view of the above problems, the present invention provides a remote control system for work machine capable of enhancing the stability and efficiently improving the operability.

To solve the above problems, a remote control system for a work machine according to the present invention includes: an operation lever to let an operator operate a plurality of actuators of the work machine; an operator-side remote controller configured to transmit command signals for operating the plurality of actuators via a communication network, the command signals being generated in response to operation with the operation lever; a work-machine side remote controller configured to receive the command signals via the communication network and transmit the command signals to the work machine; a delay state determination device configured to determine a communication delay state of the command signals that the work-machine side remote controller receives relative to the command signals transmitted from the operator-side remote controller; and a command signal correction device configured to, when it is determined that the communication delay state is worse than a preset delay state determination threshold, correct all the command signals of the plurality of actuators being operated so as to maintain a ratio among the command signals.

According to the present invention, a remote control system for a work machine having a plurality of actuators corrects all command signals for the actuators being operated when a communication delay time occurs during operation with the actuators. This limits the operation of the actuators while keeping the ratio of the command signals (operation signals) of the actuators, and thus keeps the operating balance of the actuators that the operator intends and facilitates the operation. Limiting the command signals in this way reduces the deviation between the operating state of the work machine that the operator can understand on the monitor and the actual operating state of the work machine, so that the operator is able to input accurate feedback to the operation levers based on the visual result on the work machine displayed on the monitor for efficient work.

Other problems, configurations and advantageous effects also will be clear from the following descriptions of the embodiments.

The following describes some embodiments of the present invention, with reference to the attached drawings. In the attached drawings, like numbers indicate like components having the same functions to omit their duplicated descriptions. This embodiment exemplifies a work machine by way of a hydraulic excavator. The work machine is not limited to a hydraulic excavator, and is applicable to construction machines such as wheel loaders, cranes, bulldozers, dumps, and road machines, and general work machines other than construction machines, as long as the operator can operate a plurality of actuators of the work machine by remote control.

<FIG> and <FIG> show a remote control system for hydraulic excavator that is one example of the work machine according to a first embodiment, where <FIG> schematically shows the structure, and <FIG> is a block diagram of the structure.

As shown in <FIG>, the hydraulic excavator (work machine) <NUM> includes a crawler-type lower traveling body <NUM>, an upper turning body <NUM> mounted to be able to turn relative to the lower traveling body <NUM>, and a front unit <NUM> attached to the front of the upper turning body <NUM> to be able to move up and down and perform works such as excavation.

The lower traveling body <NUM> includes a pair of left and right driving motors <NUM> (hereinafter, they may be referred to as a right driving motor <NUM> and a left driving motor <NUM>). The upper turning body <NUM> includes a prime mover such as an engine, a hydraulic pump, and a turning motor <NUM>. The front unit <NUM> has a boom <NUM>, an arm <NUM>, and a bucket <NUM>, which are driven by a boom cylinder, an arm cylinder, and a bucket cylinder, respectively, that are hydraulic cylinders driven by hydraulic oil. The boom <NUM>, the arm <NUM>, the bucket <NUM>, the turning motor <NUM>, and the driving motor <NUM> constitute actuators <NUM> of the work machine of the present embodiment (see <FIG>).

The hydraulic excavator <NUM> includes a work-machine side remote controller <NUM> provided with units such as a command information transmitter/receiver <NUM> for transmitting/receiving command information (command signal). An operator-side remote controller (this may be called a wireless remote controller) <NUM> is provided outside the hydraulic excavator <NUM>, for example in the control room, and this operator-side remote controller <NUM> includes a command information transmitter/receiver <NUM> for transmitting/receiving command information (command signal). The remote control system of the present embodiment is wireless communicable of (transmitting and receiving) information and signals between the operator-side remote controller <NUM> (the command information transmitter/receiver <NUM> thereof) and the work-machine side remote controller <NUM> (the command information transmitter/receiver <NUM> thereof) via a communication network <NUM>.

The operator-side remote controller <NUM> of the present embodiment includes a plurality of remote-control operation levers (hereinafter, simply referred to as operation levers) <NUM> to let the operator operate each of the plurality of actuators <NUM> (boom <NUM>, arm <NUM>, bucket <NUM>, left and right driving motors <NUM>, and turning motor <NUM>). In response to the operation of these operation levers <NUM> by the operator, a command signal corresponding to the operation of each operation lever <NUM> (displacement of the operation lever) is generated to operate the actuator <NUM> (boom <NUM>, arm <NUM>, bucket <NUM>, left and right driving motors <NUM>, or turning motor <NUM>) corresponding to the operation lever <NUM>, and is output to the command information transmitter/receiver <NUM>.

As shown in <FIG>, the hydraulic excavator <NUM> has a basic configuration including: a plurality of solenoid valves <NUM> that generate hydraulic signals for operating the plurality of actuators <NUM>; and a controller <NUM> that controls the operation (status) of the plurality of actuators <NUM>. To this end, the controller <NUM> converts a command signal input from the outside (in this case, the command information transmitter/receiver <NUM> of the work-machine side remote controller <NUM>) into a current for a command to the solenoid valves <NUM>.

The following describes the embodiment of applying the remote control system of the present embodiment to a typical hydraulic excavator <NUM> having an electric lever system that is configured so that a command signal generated in response to the operation with the operation levers <NUM> in the operation room as shown in <FIG> and <FIG> is sent to the solenoid valves <NUM> via the controller <NUM>, and the actuators <NUM> (boom <NUM>, arm <NUM>, bucket <NUM>, left and right driving motors <NUM>, and turning motor <NUM>) are operated based on the hydraulic pressure from the solenoid valves <NUM> via a control valve.

A detailed description on the configuration of such a typical hydraulic excavator <NUM> is omitted here.

As shown in the drawing, the operation levers <NUM> and the operator-side remote controller <NUM> may be configured as one device (in other words, the operator-side remote controller <NUM> includes the operation levers <NUM>), or they may configured as separate devices. As shown in the drawing, the hydraulic excavator (work machine) <NUM> and the work-machine side remote controller <NUM> may be configured as separate devices, or may be configured as one device (in other words, the hydraulic excavator <NUM> internally includes the work-machine side remote controller <NUM>).

Although not shown, the operator-side remote controller <NUM> and the work-machine side remote controller <NUM> described above are configured as a microcomputer that includes a central processing unit (CPU) that performs various calculations, a memory such as a read only memory (ROM) or a hard disk drive (HDD) that stores programs for executing calculations by the CPU, and a random access memory (RAM) that is a work area where the CPU executes programs. Various functions of the operator-side remote controller <NUM> and the work-machine side remote controller <NUM> are implemented by the CPU loading various programs stored in the memory into the RAM for execution.

The operator operates the actuators <NUM> (boom <NUM>, arm <NUM>, bucket <NUM>, left and right driving motors <NUM>, and turning motor <NUM>) of the work machine with the operation levers <NUM> in the operator-side remote controller <NUM> shown in <FIG>.

Specifically, a monitor <NUM> displays the video of the operating state of the hydraulic excavator <NUM> (actuators <NUM>) taken by a camera <NUM> from the outside, for example, in the control room, via the communication network <NUM>. Then, the operator operates the operation levers <NUM> in the operator-side remote controller <NUM> while viewing the video on the monitor <NUM> for remote control of the actuators <NUM> of the work machine. That is, the camera <NUM> is an operation state confirmation device for confirming the operation state of the hydraulic excavator <NUM> (actuators <NUM>) from the outside, and the monitor <NUM> is an operation state display device that receives the output (video) of the camera (operation state confirmation device) <NUM> via the communication network <NUM> to let the operator view the video.

As shown in <FIG>, the operator-side remote controller <NUM> includes: a command signal correction unit (command signal correction device) <NUM> that corrects command signals generated in response to the operation of the operation levers <NUM> based on the output of a delay state determination unit (delay state determination device) <NUM>; a command information transmitter/receiver <NUM> that transmits command information (specifically, command signals output from the command signal correction unit <NUM>) via the communication network <NUM>; a communication state determination unit <NUM> that determines the communication state of the operator-side remote controller <NUM>; and the delay state determination unit <NUM> that determines a communication delay state (hereinafter this may be simply referred to as a delay state) with the work-machine side remote controller <NUM> based on the output of a communication state determination unit <NUM> that determines the communication state of the work-machine side remote controller <NUM> and the output of the communication state determination unit <NUM> that determines the communication state of the operator-side remote controller <NUM>.

The work-machine side remote controller <NUM> of the hydraulic excavator <NUM> includes: a command information transmitter/receiver <NUM> that receives command information (command signals) from the operator-side remote controller <NUM> (command information transmitter/receiver <NUM> thereof) via the communication network <NUM> and transmits the command signals to the controller <NUM> of the hydraulic excavator <NUM>; and the communication state determination unit <NUM> that determines a communication state of the work-machine side remote controller <NUM>.

As described above, the delay state determination unit <NUM> determines the communication delay state with the work-machine side remote controller <NUM> based on the outputs of the communication state determination unit <NUM> of the operator-side remote controller <NUM> and of the communication state determination unit <NUM> of the work-machine side remote controller <NUM>. Specifically, the delay state determination unit <NUM> determines the communication delay state of the command signal that the command information transmitter/receiver <NUM> of the work-machine side remote controller <NUM> receives relative to the command signal transmitted from the command information transmitter/receiver <NUM> of the operator-side remote controller <NUM>, based on the outputs of the communication state determination unit <NUM> of the operator-side remote controller <NUM> and of the communication state determination unit <NUM> of the work-machine side remote controller <NUM>.

Specifically, the delay state determination unit <NUM> determines the communication delay state as follows: the communication state determination units <NUM> and <NUM> monitor the radio wave strengths of the remote controllers (<NUM>, <NUM>) on the operator side and the work machine side, respectively, and the delay state determination unit <NUM> outputs an overall communication delay state based on the two results.

Assume that the radio wave strength of the operator-side remote controller <NUM> (monitored by the communication state determination unit <NUM>) is α and the radio wave strength of the work-machine side remote controller <NUM> (monitored by the communication state determination unit <NUM>) is β. Then, the delay state determination unit <NUM> calculates the delay state as Ls = α×β. The higher the radio wave strengths α and β, the better the communication condition, and the smaller the radio wave strengths α and β, the worse the communication condition.

As shown in <FIG>, the command value correction unit <NUM> includes a correction value calculation unit <NUM> and a correction value multiplication unit <NUM>. The correction value calculation unit <NUM> outputs a command correction value to correct the command signals output from the operation levers <NUM>. The command correction value is determined based on the delay state Ls, which is the output result of the delay state determination unit <NUM>, in accordance with the graph (calculation table) shown in <FIG>. The graph of <FIG> shows the command correction value calculated based on the delay state Ls. For example, during the delay state Ls=<NUM> to <NUM>, which is determined a good communication state, the command correction value of <NUM> is output, which means that the command signals are not corrected. During the delay state Ls=<NUM> to <NUM>, as the delay state Ls decreases (that is, the communication state worsens), the command correction value decreases gradually from <NUM> to <NUM>. <NUM> (proportionately in this example). That is, Ls=<NUM> is set as the threshold to determine whether the correction is necessary or not based on the delay state Ls output from the delay state determination unit <NUM>. If the delay state determination unit <NUM> outputs the delay state Ls that is smaller (that is, worsening) than the delay state determination threshold Ls=<NUM>, a command correction value less than <NUM> is output for correcting the command signals. Further, when the delay state is less than Ls=<NUM>, it is determined that the communication state is extremely bad, and the command correction value for the delay state is immediately lowered to <NUM>. In other words, Ls=<NUM> is set as the threshold to determine whether the communication state is extremely poor and the communication is disrupted. If the delay state Ls output from the delay state determination unit <NUM> is smaller (i.e., worsening) than Ls=<NUM> as the communication disruption determination threshold, it is determined that the communication is disrupted. Then the command correction value of <NUM> is output to correct the command signals so that the plurality of actuators <NUM> do not operate.

The correction value multiplication unit <NUM> multiplies all of the command signals output from the operation levers <NUM> being operated (i.e., all the command signals of the plurality of actuators <NUM> being operated with the operation levers <NUM>) by the command correction value calculated by the correction value calculation unit <NUM> for (uniform) correction. This operation uniformly corrects all command signals in the operator-side remote controller <NUM> (i.e., before the command signals output from the operation levers <NUM> are transmitted from the operator-side remote controller <NUM> to the work-machine side remote controller <NUM>), which keeps the ratio of the multiple operation-lever displacements input to the operation levers <NUM> by the operator.

The command information transmitter/receiver <NUM> transmits the (corrected) command signals output from the correction value multiplication unit <NUM> of the command value correction unit <NUM> to the command information transmitter/receiver <NUM> of the work-machine side remote controller <NUM> via the communication network <NUM>. The command information transmitter/receiver <NUM> of the work-machine side remote controller <NUM> then transmits the command signal s received from the command information transmitter/receiver <NUM> of the operator-side remote controller <NUM> via the communication network <NUM> to the controller <NUM> of the hydraulic excavator <NUM>. The controller <NUM> controls the operation (state) of the plurality of actuators <NUM> according to the method described above.

As a result, during Ls = <NUM> to <NUM> where the communication state between the operator-side remote controller <NUM> and the work-machine side remote controller <NUM> is determined to be in good condition, the operation speed of the actuators <NUM> (boom <NUM>, arm <NUM>, bucket <NUM>, left and right driving motors <NUM>, and turning motor <NUM>) of the work machine is not limited (decelerated), and during Ls = <NUM> to <NUM> (i.e., it is determined that the delay state Ls output from the delayed determination unit <NUM> is worse than the delay state determination threshold Ls=<NUM>), the operating speed of the actuators <NUM> (boom <NUM>, arm <NUM>, bucket <NUM>, left and right driving motors <NUM>, turning motor <NUM>) of the work machine is (uniformly) limited (decelerated) in accordance with the degree of worsening of the delay state Ls. If the delay state Ls is less than Ls=<NUM> (i.e., it is determined that the delay state Ls output from the delay state determination unit <NUM> is worse than Ls=<NUM>, which is the threshold for determining communication disruption), the communication is determined disrupted. In this case, the actuators <NUM> (boom <NUM>, arm <NUM>, bucket <NUM>, left and right driving motors <NUM>, and turning motor <NUM>) of the work machine will not operate in response to the operation by the operator with the operation levers <NUM>.

In general, if a communication delay occurs when operating a plurality of actuators <NUM>, the actual operation of the work machine will be delayed compared with the command signals input by the operator via the operation levers <NUM>. In this case, the operator who observes the movement of the work machine displayed on the monitor <NUM> may recognize that the actuators <NUM> are not moving as intended, and may increase the displacement of the operation levers <NUM> (that is, the command signal).

As a result, the actual speed of the actuators <NUM> becomes faster than the speed of the actuators <NUM> aimed at by the operator, resulting in an overshoot. When the work machine is performing excavation, including boom raising, arm crowding, and bucket crowding operations, if an overshoot occurs for the boom raising speed, the boom will rise too high and the operator fails to excavate earth and sand as intended, resulting in poor efficiency. If an overshoot occurs for the arm crowding speed, this causes excessive arm crowding to excavate too much, leading to deterioration of efficiency if corrective work is required.

For an overshoot of boom raising, the control of Patent Literature <NUM> acts to correct a command signal only for boom raising. In this case, the boom will not rise, and the work machine excavates too much, leading to deterioration of efficiency.

In this case, the present embodiment allows (uniform) multiplication of all of the command signals for boom raising, arm crowding, and bucket crowding by the command correction value according to the delay state, and thus allows the command signals to keep the operation balance as intended by the operator according to the delay state and suppresses the overshoot of the actual speed of the actuators <NUM> of the work machine compared with the speed of the actuators <NUM> that the operator intends, making it easier for the work machine to perform the operator's intended motion. As a result, if a communication delay occurs in remote control of the work machine with the plurality of actuators <NUM>, this configuration prevents deterioration of efficiency.

As described above, the first embodiment includes: the operation levers <NUM> for the operator to operate the plurality of actuators <NUM> of the work machine; the operator-side remote controller <NUM> that transmits command signals for operating the plurality of actuators <NUM> via the communication network <NUM>, the command signals being generated in response to the operation with the operation levers <NUM>; the operator-side remote controller <NUM> that receives the command signals via the communication network <NUM> and transmits the command signals to the work machine; the delay state determination unit (delay state determination device) <NUM> that determines a communication delay state of the command signals that the work-machine side remote controller <NUM> receives relative to the command signals transmitted from the operator-side remote controller <NUM>; and the command signal correction unit (command signal correction device) <NUM> that, when it is determined that the communication delay state is worse than a preset delay state determination threshold, corrects all the command signals of the plurality of actuators <NUM> being operated so as to maintain their ratio.

The command signal correction unit (command signal correction device) <NUM> corrects all the command signals of the plurality of actuators <NUM> being operated so that the operating speed of the plurality of actuators <NUM> becomes slower as the communication delay state worsens.

When the communication delay state is determined to be worse than a preset communication disruption determination threshold, the command signal correction unit (command signal correction device) <NUM> determines that communication is disrupted and corrects all the command signals of the plurality of actuators <NUM> being operated so that the plurality of actuators <NUM> will not operate.

In other words, when an overshoot of the operating speed of the actuators <NUM> occurs due to the communication delay time, the first embodiment limits a plurality of command speeds so as not to cause off-balance of the operating speeds of the actuators <NUM> being operated. The method for limiting a command speed so as not to cause off-balance of the operator's intended operation speed is uniformly correcting all of the operation signals in the operator-side remote controller <NUM> so as to keep the ratio of the plurality of operation lever displacements input by the operator with the operation levers <NUM>.

According to the first embodiment, a remote control system for a work machine having a plurality of actuators <NUM> corrects all command signals for the actuators <NUM> being operated when a communication delay time occurs during operation with the actuators <NUM>. This limits the operation of the actuators <NUM> while keeping the ratio of the command signals (operation signals) of the actuators <NUM>, and thus keeps the operating balance of the actuators <NUM> that the operator intends and facilitates the operation. Limiting the command signals in this way reduces the deviation between the operating state of the work machine that the operator can understand on the monitor <NUM> and the actual operating state of the work machine, so that the operator is able to input accurate feedback to the operation levers <NUM> based on the visual result on the work machine displayed on the monitor <NUM> for efficient work.

In the first embodiment, the delay state determination unit (delay state determination device) <NUM> and the command signal correction unit (command signal correction device) <NUM> are provided in the operator-side remote controller <NUM>, and the command signal correction unit (command signal correction device) <NUM> corrects all the command signals for the plurality of actuators <NUM> being operated before the command signals are transmitted from the operator-side remote controller <NUM> to the work-machine side remote controller <NUM>.

The first embodiment enables correction with consideration given to a delay of a command signal that the operator-side remote controller <NUM>, which is a wireless remote controller, transmits to the work-machine side remote controller <NUM> (via the communication network <NUM>). One operator-side remote controller <NUM> may control the operation of a plurality of hydraulic excavators <NUM> while switching them. In this case, the number of components of each hydraulic excavator <NUM> (i.e., of the work-machine side remote controller <NUM>) can be reduced, so that this embodiment reduces the cost as compared with a second embodiment described later, for example.

In another example, the delay state determination unit <NUM> may determine a communication delay state as follows: the communication state determination units <NUM> and <NUM> monitor the transmission time when the operator-side remote controller <NUM> transmits a command signal and the reception time when the work-machine side remote controller <NUM> receives the command signal, and the delay state determination unit <NUM> outputs a communication delay based on the two results.

Assume that the time when the operator-side remote controller <NUM> transmits a signal is T1 (monitored by the communication state determination unit <NUM>) and the time when the work-machine side remote controller <NUM> receives the signal is T2 (monitored by the communication state determination unit <NUM>). Then, the delay state determination unit <NUM> calculates the delay time as Lt = T2-T1. The smaller the delay time Lt, the better the communication condition, and the larger the delay time Lt, the worse the communication condition.

In this case, the correction value calculation unit <NUM> of the command value correction unit <NUM> outputs a command correction value to correct the command signals output from the operation levers <NUM>. The command correction value is determined based on the delay time Lt, which is the output result of the delay state determination unit <NUM>, in accordance with the graph (calculation table) shown in <FIG>. The graph of <FIG> shows the command correction value calculated based on the delay time Lt. For example, during the time Lt=<NUM> to <NUM> second, which is determined a good communication state, the command correction value of <NUM> is output, which means that the command signals are not corrected. During the time Lt=<NUM> to <NUM>, as the delay time Lt increases (i.e., the communication state worsens), the command correction value decreases gradually from <NUM> to <NUM>. <NUM> (proportionately in this example). That is, Lt=<NUM> is set as the threshold to determine whether the correction is necessary or not based on the delay time Lt output from the delay state determination unit <NUM>. If the delay state determination unit <NUM> outputs the delay time Lt that is larger (that is, worsening) than the delay state determination threshold Lt=<NUM>, a command correction value less than <NUM> is output for correcting the command signals. Further, when the delay time is Lt=<NUM> or more, it is determined that the communication state is extremely bad, and the command correction value for the delay state is immediately lowered to <NUM>. In other words, Lt=<NUM> is set as the threshold to determine whether the communication state is extremely poor and the communication is disrupted. If the delay time Lt output from the delay state determination unit <NUM> is larger (i.e., worsening) than Lt=<NUM> as the communication disruption determination threshold, it is determined that the communication is disrupted. Then the command correction value of <NUM> is output to correct the command signals so that the plurality of actuators <NUM> do not operate.

The correction value multiplication unit <NUM> of the command correction unit <NUM> multiplies all of the command signals output from the operation levers <NUM> being operated (i.e., all the command signals of the plurality of actuators <NUM> being operated with the operation levers <NUM>) by the command correction value calculated by the correction value calculation unit <NUM> for (uniform) correction. This operation uniformly corrects all command signals in the operator-side remote controller <NUM> (i.e., before the command signals output from the operation levers <NUM> are transmitted from the operator-side remote controller <NUM> to the work-machine side remote controller <NUM>), which keeps the ratio of the multiple operation-lever displacements input to the operation levers <NUM> by the operator.

As a result, during Lt = <NUM> to <NUM> where the communication state between the operator-side remote controller <NUM> and the work-machine side remote controller <NUM> is determined to be in good condition, the operation speed of the actuators <NUM> (boom <NUM>, arm <NUM>, bucket <NUM>, left and right driving motors <NUM>, and turning motor <NUM>) of the work machine is not limited (decelerated), and during Lt = <NUM> to <NUM> (i.e., it is determined that the delay time Lt output from the delayed determination unit <NUM> is worse than the delay state determination threshold Lt = <NUM>), the operating speed of the actuators <NUM> (boom <NUM>, arm <NUM>, bucket <NUM>, left and right driving motors <NUM>, turning motor <NUM>) of the work machine is (uniformly) limited (decelerated) in accordance with the degree of worsening of the delay time Lt. If the delay time Lt is more than Lt=<NUM> (i.e., it is determined that the delay time Lt output from the delay state determination unit <NUM> is worse than Lt=<NUM>, which is the threshold for determining communication disruption), the communication is determined disrupted. In this case, the actuators <NUM> (boom <NUM>, arm <NUM>, bucket <NUM>, left and right driving motors <NUM>, and turning motor <NUM>) of the work machine will not operate in response to the operation by the operator with the operation levers <NUM>.

The relationship between the delay state Ls and the command correction value used in the command value correction unit <NUM> (correction value calculation unit <NUM> thereof) may be set as shown in <FIG>. In the graph (calculation table) of <FIG>, the threshold LsX of the delay state Ls (the threshold to determine whether correction is required or not, hereinafter also referred to as the correction state threshold), from which the command correction value starts to decrease from <NUM>, is determined based on the graph (calculation table) in <FIG> shows the relationship between the largest operation command signal (hereinafter referred to as maximum operation command signal) for the command signals of the actuators <NUM> being operated in the work machine and the correction state threshold LsX. According to the graph in <FIG>, the larger the maximum operation command signal, the larger the correction state threshold LsX from which the command correction value starts to fall from <NUM>, and the smaller the maximum operation command signal, the smaller the correction state threshold LsX from which the command correction value starts to fall from <NUM>.

This is because when the maximum operation command signal is large, that is, when the operating speed of the actuators <NUM> of the work machine is high, the deviation per unit time caused by the communication delay between the operation amount of the actuators <NUM> of the work machine and the operation amount of the actuators <NUM> of the work machine intended by the operator is large, and setting a large correction state threshold LsX, from which the command correction value starts to decrease, enables the correction of a command signal when a communication delay occurs even a little. This way, if a communication delay, if small, occurs when the actuator operating speed of the work machine is high, the command signal will be corrected to be small, which reduces the deviation per unit time caused by the communication delay between the amount of operation of the actuators <NUM> of the work machine and the amount of operation of the actuators <NUM> of the work machine intended by the operator.

According to the graph in <FIG>, the smaller the maximum operation command signal, the smaller the correction state threshold LsX from which the command correction value starts to fall from <NUM>. This is because when the maximum operation command signal is small, that is, when the operating speed of the actuators <NUM> of the work machine is slow, the deviation per unit time caused by the communication delay between the operation amount of the actuators <NUM> of the work machine and the operation amount of the actuators <NUM> of the work machine intended by the operator is small. That is, when the operating speed of the actuators <NUM> is small, a small correction state threshold LsX, from which the command correction value starts to decrease, is set. This means that the command signals are not corrected until the communication is largely delayed. This way, if a communication delay occurs when the actuator operating speed of the work machine is slow, the work machine can be operated without correcting the command signals and lowering the speed in the range where the deviation per unit time caused by the communication delay between the amount of operation of the actuators <NUM> of the work machine and the amount of operation of the actuators <NUM> of the work machine intended by the operator is assumed to be small.

In this way, the correction state threshold (delay state determination threshold) LsX of the delay state Ls from which the command correction value starts to decrease from <NUM> can be set according to the operating speed of the plurality of actuators <NUM> of the work machine. This enhances the stability of the work machine and efficiently improves the operability.

In another example, the delay state determination unit <NUM> may determine a communication delay state as follows: the communication state determination units <NUM> and <NUM> monitor the transmission time when the operator-side remote controller <NUM> transmits a command signal and the reception time when the work-machine side remote controller <NUM> receives the command signal, and the delay state determination unit <NUM> outputs a communication delay state based on the two results. In this method, similarly to <FIG> and <FIG> above, the correction time threshold (delay state determination threshold) LtX of the delay time Lt from which the command correction value starts to decrease from <NUM> is set depending on the operating speed of multiple actuators <NUM> of the work machine. The relationship between the delay time Lt and the command correction value is as shown in <FIG>, and the relationship between the maximum operation command signal and the correction state threshold LtX is as shown in <FIG>.

<FIG> is a block diagram of the structure of a remote control system for hydraulic excavator that is one example of the work machine according to a second embodiment.

As described above, in the first embodiment, the operator-side remote controller <NUM> includes the delay state determination unit <NUM> that determines the communication delay state between the operator-side remote controller <NUM> and the work-machine side remote controller <NUM>, and the command signal correction unit <NUM> that corrects command signals generated in response to the operation with the operation levers <NUM> based on the output from the delay state determination unit <NUM>. With this configuration, all of the command signals output from the operation levers <NUM> are corrected before the operator-side remote controller <NUM> transmits the command signals to the work-machine side remote controller <NUM>.

In contrast, in the second embodiment, a work-machine side remote controller <NUM> includes a delay state determination unit (delay state determination device) <NUM> and a command signal correction unit (command signal correction device) <NUM>. With this configuration, all of the command signals output from the operation levers <NUM> and transmitted from the command information transmitter/receiver <NUM> of the operator-side remote controller <NUM> to the command information transmitter/receiver <NUM> of the work-machine side remote controller <NUM> via the communication network <NUM> are corrected before the command information transmitter/receiver <NUM> of the work-machine side remote controller <NUM> transmits the command signals to the controller <NUM> of the hydraulic excavator <NUM>.

The delay state determination unit <NUM> functions in the same manner as the delay state determination unit <NUM> described in the first embodiment. Note that the delay state determination unit <NUM> receives signals from the communication state determination unit <NUM> of the operator-side remote controller <NUM> via the communication network <NUM>, and directly receives signals from the communication state determination unit <NUM> of the work-machine side remote controller <NUM> within the device.

As described above, the delay state determination unit <NUM> determines the communication delay state with the operator-side remote controller <NUM> based on the outputs of the communication state determination unit <NUM> of the operator-side remote controller <NUM> and of the communication state determination unit <NUM> of the work-machine side remote controller <NUM>. Specifically, the delay state determination unit <NUM> determines the communication delay state of the command signal that the command information transmitter/receiver <NUM> of the work-machine side remote controller <NUM> receives relative to the command signal transmitted from the command information transmitter/receiver <NUM> of the operator-side remote controller <NUM>, based on the outputs of the communication state determination unit <NUM> of the operator-side remote controller <NUM> and of the communication state determination unit <NUM> of the work-machine side remote controller <NUM>.

The specific method of determining the communication state by the delay state determination unit <NUM> is the same as in the first embodiment.

The command value correction unit <NUM> has the same configuration as the command signal correction unit <NUM> (including the correction value calculation unit <NUM> and the correction value multiplication unit <NUM>) shown in <FIG>. The correction value calculation unit <NUM> outputs a command correction value to correct the command signals output from the operation levers <NUM>. The command correction value is determined based on the delay state Ls, which is the output result of the delay state determination unit <NUM>, in accordance with the graph (calculation table) shown in <FIG>.

The correction value multiplication unit <NUM> multiplies all of the command signals output from the operation levers <NUM> being operated and received from the operator-side remote controller <NUM> (the command information transmitter/receiver <NUM> thereof) via the communication network <NUM> (i.e., all the command signals of the plurality of actuators <NUM> being operated with the operation levers <NUM>) by the command correction value calculated by the correction value calculation unit <NUM> for (uniform) correction. With this configuration, all of the operation signals are uniformly corrected within the work-machine side remote controller <NUM> (i.e., before the command signals output from the operation levers <NUM> and transmitted from the command information transmitter/receiver <NUM> of the operator-side remote controller <NUM> to the command information transmitter/receiver <NUM> of the work-machine side remote controller <NUM> via the communication network <NUM> are transmitted from the command information transmitter/receiver <NUM> of the work-machine side remote controller <NUM> to the controller <NUM> of the hydraulic excavator <NUM>) so as to keep the ratio of the plurality of operation lever displacements input by the operator with the operation levers <NUM>.

The correction value multiplication unit <NUM> transmits the (corrected) command signals as the output result to the controller <NUM> of the hydraulic excavator <NUM>.

When an overshoot of the operating speed of the actuators <NUM> occurs due to the communication delay time, the second embodiment also limits a plurality of command speeds so as not to cause off-balance of the operating speeds of the actuators <NUM> being operated. The method for limiting a command speed so as not to cause off-balance of the operator's intended operation speed is uniformly correcting all of the operation signals in the work-machine side remote controller <NUM> so as to keep the ratio of the plurality of operation lever displacements input by the operator with the operation levers <NUM>. This embodiment therefore leads to the same advantageous effects as those described in the first embodiment.

In the second embodiment, the delay state determination unit (delay state determination device) <NUM> and the command signal correction unit (command signal correction device) <NUM> are provided in the work-machine side remote controller <NUM>, and the command signal correction unit (command signal correction device) <NUM> corrects all the command signals for the plurality of actuators <NUM> being operated before the command signals are transmitted from the work-machine side remote controller <NUM> to the work machine (controller <NUM> thereof).

According to the second embodiment, when the communication delay is detected, the correction information (corrected command signals) is transmitted to the controller <NUM> of the hydraulic excavator (work machine) <NUM> without going through the communication network <NUM>. This allows the correction to be immediately reflected in the operation of the actuators <NUM>. Further, one hydraulic excavator <NUM> may be operated while switching a plurality of operator-side remote controllers <NUM>. In this case, the number of components of each operator-side remote controller <NUM> as the wireless remote controllers can be reduced, so that this embodiment reduces the cost as compared with the first embodiment described above, for example.

Note that the second embodiment can include the contents described above based on <FIG> in addition to <FIG>.

<FIG> is a block diagram of the structure of a command value correction unit in a remote control system for hydraulic excavator that is one example of the work machine according to a third embodiment. In the following description, the third embodiment will be described as a modification of the command value correction unit <NUM> of the operator-side remote controller <NUM> in the first embodiment. Needless to say, the configuration is applicable to the command value correction unit <NUM> of the work-machine side remote controller <NUM> in the second embodiment.

In the third embodiment, the configuration of the command value correction unit <NUM> in the first embodiment (or the command value correction unit <NUM> in the second embodiment) is as shown in <FIG>. Specifically, the command value correction unit <NUM> functions as a correction calculation unit that calculates a command correction value to correct command signals output from the operation levers <NUM> based on the delay state Ls as the output result of the delay state determination unit <NUM>, and outputs the command correction value. To this end, the command value correction unit <NUM> includes: a correction value A calculation unit <NUM>, which calculates a command correction value A for correcting the command signals of the boom <NUM>, arm <NUM>, and bucket <NUM> (boom command signal, arm command signal, and bucket command signal) based on the delay state Ls; a correction value B calculation unit <NUM>, which calculates a command correction value B for correcting the command signal of the turning motor <NUM> (turning command signal) based on the delay state Ls; and a correction value C calculation unit <NUM>, which calculates a command correction value C for correcting the command signals of the right driving motor <NUM> and the left driving motor <NUM> (driving-right command signal and driving-left command signal) based on the delay state Ls.

The correction value A calculation unit <NUM>, the correction value B calculation unit <NUM>, and the correction value C calculation unit <NUM> calculate the command correction value A, the command correction value B, and the command correction value C, respectively, based on the delay state Ls in accordance with the calculation table as shown in <FIG> (details will be explained later).

A correction value A multiplication unit <NUM> multiplies the command signals of the boom <NUM>, arm <NUM>, and bucket <NUM> (boom command signal, arm command signal, and bucket command signal) by the command correction value A calculated by the correction value A calculation unit <NUM>. A correction value B multiplication unit <NUM> multiplies the command signal of the turning motor <NUM> (turning command signal) by the command correction value B calculated by the correction value B calculation unit <NUM>. A correction value C multiplication unit <NUM> multiplies the command signals of the right driving motor <NUM> and the left driving motor <NUM> (driving-right command signal and driving-left command signal) by the command correction value C calculated by the correction value C calculation unit <NUM>.

When the correction value A calculation unit <NUM>, the correction value B calculation unit <NUM>, and the correction value C calculation unit <NUM> calculate the command correction value A, the command correction value B, and the command correction value C, respectively, based on the graph (calculation table) shown in <FIG>, they can change the command correction value for each of the actuators <NUM> depending on the communication delay state Ls.

The graph of <FIG> shows the command correction value A, command correction value B, and command correction value C calculated based on the delay state Ls. For example, for the command correction value A, during the delay state Ls=<NUM> to <NUM>, which is determined a good communication state, the command correction value of <NUM> is output for the command correction value A, which means that the command signals are not corrected. During the delay state Ls=<NUM> to <NUM>, as the delay state Ls decreases (that is, the communication state worsens), the command correction value A decreases gradually. For the command correction value B, during the delay state Ls=<NUM> to <NUM>, which is determined a good communication state, the command correction value of <NUM> is output for the command correction value B, which means that the command signals are not corrected. During the delay state Ls=<NUM> to <NUM>, as the delay state Ls decreases (that is, the communication state worsens), the command correction value B decreases gradually. For the command correction value C, at the delay state Ls=<NUM>, the command correction value of <NUM> is output for the command correction value C, which means that the command signals are not corrected. During the delay state Ls=<NUM> to <NUM>, as the communication delay state Ls decreases (that is, the communication state worsens), the command correction value C decreases gradually. When the delay state Ls=<NUM>, the command correction value A, the command correction value B, and the command correction value C are <NUM>, <NUM>, and <NUM>, respectively, and the command signals of the boom <NUM>, arm <NUM>, and bucket <NUM> are reduced to <NUM> time, the command signal of the turning motor <NUM> is reduced to <NUM> time, and the command signals of the right driving motor <NUM> and the left driving motor <NUM> are reduced to <NUM> time. Further, when the delay state is less than Ls=<NUM>, it is determined that the communication state is extremely bad, the command correction values A and B also are immediately lowered to <NUM>.

The correction value A multiplication unit <NUM>, the correction value B multiplication unit <NUM>, and the correction value C multiplication unit <NUM> multiply all the command signals output from the operation levers <NUM> being operated (i.e., all the command signals of the plurality of actuators <NUM> being operated via the operation levers <NUM>) by the command correction value A, the command correction value B, and the command correction value C calculated by the correction value A calculation unit <NUM>, the correction value B calculation unit <NUM>, and the correction value C calculation unit <NUM> for correction, that is, correct the command signal for each of the plurality of actuators <NUM> being operated via the operation levers <NUM>. In this way, if a communication delay time exceeds a corresponding threshold, the system of this embodiment changes the degree of limitation (deceleration) for the specific actuator <NUM>.

In this way, this embodiment changes the command correction value based on the delay state depending on the actuators <NUM>, which changes the behavior of the operation restriction of each actuator <NUM> according to the communication state.

For example, when the delay state Ls=<NUM>, it is determined that the communication delay state is very bad. Then, the command correction value A, the command correction value B, and the command correction value C are set to <NUM>, <NUM>, and <NUM>, respectively, meaning that the boom <NUM>, the arm <NUM> and the bucket <NUM> operate with half the operation command, and the turning motor <NUM> operates with the <NUM>/<NUM> operation command. For the right driving motor <NUM> and the left driving motor <NUM>, the command signal is multiplied by zero, meaning that these motors will not operate in response to the operation by the operator with the operation levers <NUM>.

If the deviation is large between the operation of the work machine displayed on the monitor <NUM> and the actual operation of the work machine, this configuration sets some actuators <NUM> to slow down the operation and other actuators <NUM> that do not operate (or extremely slow down). This reduces the possibility that the work machine falls into a dangerous state when the communication state is poor while keeping the work efficiency without stopping some works that do not become a dangerous state.

As described above, in the third embodiment, the command signal correction unit (command signal correction device) <NUM> corrects the command signal for each of the plurality of actuators <NUM> being operated.

The command signal correction unit (command signal correction device) <NUM> is configured so that the delay state determination threshold and a command correction value in accordance with the communication delay state to correct the command signal are set for each of the plurality of actuators <NUM>.

In other words, when an overshoot of the operating speed of the actuators <NUM> occurs due to the communication delay time, the third embodiment limits a plurality of command speeds so as not to cause off-balance of the operating speeds of the actuators <NUM> being operated. Further, when the communication delay time exceeds a certain threshold, this embodiment gives priority to limiting the speed of a specific actuator <NUM> rather than keeping the operating speed balance of the actuators <NUM> being operated, for example, to prevent the falling of the hydraulic excavator <NUM> during traveling. The method for limiting a command speed so as not to cause off-balance of the operator's intended operation speed is, when the communication delay time exceeds a certain threshold, changing the way of applying limitations for a specific actuator <NUM>.

Similarly to the first and second embodiments, according to the third embodiment, a remote control system for a work machine having a plurality of actuators <NUM> corrects all command signals for the actuators <NUM> being operated when a communication delay time occurs during operation with the actuators <NUM>. This limits the operation of the actuators <NUM> while keeping the ratio of the command signals (operation signals) of the actuators <NUM>, and thus keeps the operating balance of the actuators <NUM> that the operator intends and facilitates the operation. Limiting the command signals in this way reduces the deviation between the operating state of the work machine that the operator can understand on the monitor <NUM> and the actual operating state of the work machine, so that the operator is able to input accurate feedback to the operation levers <NUM> based on the visual result on the work machine displayed on the monitor <NUM> for efficient work.

According to the third embodiment, if a communication delay time becomes large, the system changes the degree of limitation for a specific actuator <NUM>, which prevents the falling of the hydraulic excavator <NUM> during traveling, for example.

The delay state determination unit <NUM> may determine a communication delay state as follows: the communication state determination units <NUM> and <NUM> monitor the transmission time when the operator-side remote controller <NUM> transmits a command signal and the reception time when the work-machine side remote controller <NUM> receives the command signal, and the delay state determination unit <NUM> determines the communication delay state using the communication delay time Lt output based the two results. In this method, the correction value A calculation unit <NUM>, the correction value B calculation unit <NUM>, and the correction value C calculation unit <NUM> of the command value correction unit <NUM> calculate the command correction value A, the command correction value B, and the command correction value C, respectively, based on the graph (calculation table) shown in <FIG> based on the delay time Lt. The graph of <FIG> shows the command correction value A, command correction value B, and command correction value C calculated based on the delay time Lt. For example, for the command correction value A, during the delay time Lt=<NUM> to <NUM>, which is determined a good communication state, the command correction value of <NUM> is output for the command correction value A, which means that the command signals are not corrected. During the delay time Lt=<NUM> to <NUM>, as the delay time Lt increases (that is, the communication state worsens), the command correction value A decreases gradually. For the command correction value B, during the delay time Lt=<NUM> to <NUM>, which is determined a good communication state, the command correction value of <NUM> is output for the command correction value B, which means that the command signals are not corrected. During the delay time Lt=<NUM> to <NUM>, as the delay time Lt increases (that is, the communication state worsens), the command correction value B decreases gradually. For the command correction value C, during the delay time Lt=<NUM> to <NUM>, which is determined a good communication state, the command correction value of <NUM> is output for the command correction value C, which means that the command signals are not corrected. During the delay time Lt=<NUM> to <NUM>, as the delay time Lt increases (that is, the communication state worsens), the command correction value C decreases gradually. When the delay time Lt=<NUM>, the command correction value A, the command correction value B, and the command correction value C are <NUM>, <NUM>, and <NUM>, respectively, and the command signals of the boom <NUM>, arm <NUM>, and bucket <NUM> are reduced to <NUM> time, the command signal of the turning motor <NUM> is reduced to <NUM> time, and the command signals of the right driving motor <NUM> and the left driving motor <NUM> are reduced to <NUM> time. Further, when the delay time Lt=<NUM> or more, it is determined that the communication state is extremely bad, the command correction values A and B also are immediately lowered to <NUM>.

The correction value A multiplication unit <NUM>, the correction value B multiplication unit <NUM>, and the correction value C multiplication unit <NUM> of the command correction unit <NUM> multiply all the command signals output from the operation levers <NUM> being operated (i.e., all the command signals of the plurality of actuators <NUM> being operated via the operation levers <NUM>) by the command correction value A, the command correction value B, and the command correction value C calculated by the correction value A calculation unit <NUM>, the correction value B calculation unit <NUM>, and the correction value C calculation unit <NUM> for correction, that is, correct the command signal for each of the plurality of actuators <NUM> being operated via the operation levers <NUM>. In this way, if a communication delay time exceeds a corresponding threshold, the system of this embodiment changes the degree of limitation (deceleration) for the specific actuator <NUM>.

The relationship between the delay state Ls and the command correction value used in the command value correction unit <NUM> (the correction value A calculation unit <NUM>, the correction value B calculation unit <NUM>, and the correction value C calculation unit <NUM> thereof) may be set as shown in <FIG>. In the graph (calculation table) of <FIG>, the thresholds LsXA, LsXB, and LsXC of the delay state Ls (the threshold to determine whether correction is required or not, hereinafter also referred to as the correction state thresholds), from which the command correction values A, B, and C start to decrease from <NUM>, are determined based on the graph (calculation table) in <FIG> shows the relationship between the largest operation command signal (maximum operation command signal) for the command signals of the actuators <NUM> being operated in the work machine and the correction state thresholds LsXA, LsXB, and LsXC. According to the graph in <FIG>, the larger the maximum operation command signal, the larger the correction state thresholds LsXA, LsXB, and LsXC, from which the command correction value starts to fall from <NUM>, and the smaller the maximum operation command signal, the smaller the correction state thresholds LsXA, LsXB, and LsXC, from which the command correction value starts to fall from <NUM>.

This is because when the maximum operation command signal is large, that is, when the operating speed of the actuators <NUM> of the work machine is high, the deviation per unit time caused by the communication delay between the operation amount of the actuators <NUM> of the work machine and the operation amount of the actuators <NUM> of the work machine intended by the operator is large, and setting large correction state thresholds LsXA, LsXB, and LsXC, from which the command correction value starts to decrease, enables the correction of a command signal when a communication delay occurs even a little. This way, if a communication delay, if small, occurs when the actuator operating speed of the work machine is high, the command signal will be corrected to be small, which reduces the deviation per unit time caused by the communication delay between the amount of operation of the actuators <NUM> of the work machine and the amount of operation of the actuators <NUM> of the work machine intended by the operator.

According to the graph in <FIG>, the smaller the maximum operation command signal, the smaller the correction state thresholds LsXA, LsXB, and LsXC, from which the command correction value starts to fall from <NUM>. This is because when the maximum operation command signal is small, that is, when the operating speed of the actuators <NUM> of the work machine is slow, the deviation per unit time caused by the communication delay between the operation amount of the actuators <NUM> of the work machine and the operation amount of the actuators <NUM> of the work machine intended by the operator is small. That is, when the operating speed of the actuators <NUM> is small, small correction state thresholds LsXA, LsXB, and LsXC, from which the command correction value starts to decrease, are set. This means that the command signals are not corrected until the communication is largely delayed. This way, if a communication delay occurs when the actuator operating speed of the work machine is slow, the work machine can be operated without correcting the command signals and lowering the speed in the range where the deviation per unit time caused by the communication delay between the amount of operation of the actuators <NUM> of the work machine and the amount of operation of the actuators <NUM> of the work machine intended by the operator is assumed to be small.

In this way, the correction state thresholds (delay state determination thresholds ) LsXA, LsXB, and LsXC of the delay state Ls from which the command correction values A, B, and C start to decrease from <NUM> can be set according to the operating speeds of the plurality of actuators <NUM> of the work machine. This enhances the stability of the work machine and efficiently improves the operability.

In another example, the delay state determination unit <NUM> may determine a communication state as follows: the communication state determination units <NUM> and <NUM> monitor the transmission time when the operator-side remote controller <NUM> transmits a command signal and the reception time when the work-machine side remote controller <NUM> receives the command signal, and the delay state determination unit <NUM> outputs a communication delay state based on the two results. In this method, similarly to <FIG> and <FIG> above, the correction time thresholds (delay state determination thresholds) LsXA, LsXB, LsXC of the delay time Lt from which the command correction values A, B, and C start to decrease from <NUM> are set depending on the operating speed of multiple actuators <NUM> of the work machine. The relationship between the delay time Lt and the command correction values A, B, and C is as shown in <FIG>, and the relationship between the maximum operation command signal and the correction state thresholds LtXA, LtXB, and LtXC is as shown in <FIG>.

The present invention is not limited to these embodiments, and may include various modifications. The entire detailed configuration of the embodiments described above for explanatory convenience is not always necessary for the present invention.

Claim 1:
A remote control system for work machine (<NUM>) having a plurality of actuators (<NUM>), the remote control system comprising:
an operation lever (<NUM>) to let an operator operate the plurality of actuators (<NUM>);
an operator-side remote controller (<NUM>) configured to transmit command signals for operating the plurality of actuators (<NUM>) via a communication network (<NUM>), the command signals being generated in response to operation with the operation lever (<NUM>);
a work-machine side remote controller (<NUM>) configured to receive the command signals via the communication network (<NUM>) and transmit the command signals to the work machine (<NUM>);
a delay state determination device (<NUM>,<NUM>) configured to determine a communication delay state of the command signals that the work-machine side remote controller (<NUM>) receives relative to the command signals transmitted from the operator-side remote controller (<NUM>); characterised in that it further comprises
a command signal correction device (<NUM>,<NUM>) configured to, when it is determined that the communication delay state is worse than a preset delay state determination threshold, correct all the command signals of the plurality of actuators (<NUM>) being operated so as to maintain a ratio among the command signals.