Work machine

1. A work machine including

an articulated work implement including work equipment,

an actuator that drives the work implement,

an operation device that makes an instruction of operation of the actuator,

a controller configured to calculate a position of the work implement and calculate a distance between the work equipment and a predetermined target surface and calculate a positional relationship between the work equipment and the target surface, and

an informing device that informs the positional relationship between the work equipment and the target surface,

the work machine including an actuator state sensor that detects a state of the actuator, wherein

the controller

calculates a velocity of the work equipment based on the position of the work implement and an operation amount of the operation device,

determines whether or not there is a possibility of entry of the work equipment into a lower side of the target surface due to operation based on the velocity of the work equipment, the distance between the work equipment and the target surface, and the state of the actuator detected by the actuator state sensor, and

changes contents of informing by the informing device when determining that there is the possibility of entry of the work equipment into the lower side of the target surface, thereby making a warning by the informing device.

2. The work machine according to claim 1 , wherein

the controller calculates an angle formed by the work equipment and the target surface and changes the contents of informing by the informing device further according to the angle formed by the work equipment and the target surface.

3. The work machine according to claim 2 , wherein

the actuator state sensor detects a load acting on the actuator, and

the controller

employs an excess of the operation amount of the operation device as the contents of informing by the informing device when the velocity of the work equipment has such a direction as to come closer to the target surface and the distance between the work equipment and the target surface is equal to or shorter than a predetermined threshold and the load acting on the actuator detected by the actuator state sensor is equal to or lower than a predetermined threshold and the angle formed by the work equipment and the target surface is equal to or larger than a predetermined threshold, and

does not employ an excess of the operation amount of the operation device as the contents of informing by the informing device when the velocity of the work equipment has such a direction as to come closer to the target surface and the distance between the work equipment and the target surface is equal to or shorter than the predetermined threshold and the load acting on the actuator detected by the actuator state sensor is equal to or lower than the predetermined threshold and the angle formed by the work equipment and the target surface is smaller than the predetermined threshold.

4. The work machine according to claim 1 , wherein

the actuator state sensor detects a load acting on the actuator, and

the controller

employs an excess of the operation amount of the operation device as the contents of informing by the informing device when the velocity of the work equipment has such a direction as to come closer to the target surface and the distance between the work equipment and the target surface is equal to or shorter than a predetermined threshold and the load acting on the actuator detected by the actuator state sensor is equal to or lower than a predetermined threshold, and

does not employ an excess of the operation amount of the operation device as the contents of informing by the informing device when the velocity of the work equipment has such a direction as to come closer to the target surface and the distance between the work equipment and the target surface is equal to or shorter than the predetermined threshold and the load acting on the actuator detected by the actuator state sensor is higher than the predetermined threshold.

5. The work machine according to claim 1 , wherein

an arm is included in the work implement, and

the controller changes the contents of informing by the informing device further according to whether or not operation of the arm through the operation device exists.

6. The work machine according to claim 1 , wherein

a boom is included in the work implement, and

when operation of the boom through the operation device exists, the controller computes an intersection of a movement locus of the work equipment and the target surface, carries out predictive calculation of a velocity vector of the work equipment at the intersection and changes the contents of informing by the informing device according to a component perpendicular to the target surface in the velocity vector of the work equipment at the intersection.

7. The work machine according to claim 1 , wherein

the informing device is a display device, and

the controller changes a position at which the work equipment is displayed on the display device, according to the velocity of the work equipment, the distance between the work equipment and the target surface, and the state of the actuator detected by the actuator state sensor.

8. The work machine according to claim 7 , wherein

the actuator state sensor detects a load acting on the actuator, and

the controller

changes the position at which the work equipment is displayed on the display device from a reference position according to the velocity of the work equipment when the distance between the work equipment and the target surface is equal to or shorter than a predetermined threshold and operation is being input to the operation device and the load acting on the actuator detected by the actuator state sensor is equal to or lower than a predetermined threshold, and

sets the position at which the work equipment is displayed on the display device to the reference position when the distance between the work equipment and the target surface is equal to or shorter than the predetermined threshold and operation is being input to the operation device and the load acting on the actuator detected by the actuator state sensor is higher than the predetermined threshold.

9. The work machine according to claim 1 , wherein

the informing device is a display device that displays either one of a first screen in which the work equipment and the target surface are displayed and a second screen in which at least whole of the work machine and the target surface are displayed, the second screen including a wider range than the first screen, and

the controller decides which of the first screen and the second screen is to be displayed on the display device according to the velocity of the work equipment, the distance between the work equipment and the target surface, and the state of the actuator detected by the actuator state sensor.

10. The work machine according to claim 9 , wherein

the actuator state sensor detects a load acting on the actuator, and

the controller

decides to display the first screen on the display device when the distance between the work equipment and the target surface is equal to or shorter than a predetermined threshold and the velocity of the work equipment has such a direction as to come closer to the target surface and the load acting on the actuator detected by the actuator state sensor is equal to or lower than a predetermined threshold, and

decides to display the second screen on the display device when the distance between the work equipment and the target surface is equal to or shorter than the predetermined threshold and the velocity of the work equipment has such a direction as to come closer to the target surface and the load acting on the actuator detected by the actuator state sensor is higher than the predetermined threshold.