TECHNICAL FIELD

The present invention relates to a work machine.

BACKGROUND ART

Work sites where work machines such as hydraulic excavators, wheel loaders, etc. are used need to take on various tasks about safety of work operations. For example, it is an important duty to be performed for industrial safety to prevent physical contact between work machines and workers. There has been known, as a technology for preventing physical contact between work machines and workers, a system in which an infrared sensor or an ultrasonic sensor installed on a work machine detects distance between the work machine and a worker positioned around the work machine, and an alert is issued based on the detected distance. However, since infrared rays and ultrasonic waves are susceptible to sunlight, air pressure, humidity, etc. in the work environment of the work machine, the system is liable to cause detection errors. Furthermore, as it is difficult for the system to identify detected objects as workers or materials or structures, concerns are raised about the accuracy of detection and the frequency of alerts. In view of these difficulties, there have been developed systems that detect a worker by reading an ID (identification) signal from an RFID tag carried by the worker via wireless communications that are less subject to the work environment.

Patent Document 1, for example, discloses a system for detecting a worker using an RFID (Radio Frequency IDentification) tag. In the disclosed system, a worker carries an RFID tag that emits radio waves over a predetermined communication distance, and a receiver disposed on a work machine receives radio waves from the RFID tag. The system issues an alert by detecting the worker who has approached the work machine within the predetermined communication distance. Furthermore, Patent Document 2 reveals a system in which an RFID tag carried by a worker has a function to change magnetic field detection sensitivities, and identifies the distance between a work machine and the worker as several stages, so that alert levels are changed depending on the distance.

Furthermore, Patent Documents 3 and 4 disclose a system in which a GNSS (Global Navigation Satellite System) receiver for receiving signals from positioning satellites of a GNSS is mounted on a work machine, a GNSS signal reception terminal having a GNSS signal receiving function is carried by a worker, and the work machine and the worker as they are in close proximity to each other are detected by acquiring respective positional information of the work machine and the worker using the GNSS, indicating the nearness to the operator of the work machine.

PRIOR ART DOCUMENT

Patent Documents

Patent Document 1: Japanese Patent No. 5009139

Patent Document 2: Japanese Patent No. 5835577

Patent Document 3: Japanese Patent No. 3085662

Patent Document 4: Japanese Patent No. 5520688

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

Incidentally, in case a worker who is approaching a work machine is to be indicated to an operator of the work machine by an alert or the like, it is necessary to adequately detect the worker in close proximity to the work machine and also to be careful enough not to excessively alert and bother the operator.

For preventing the operator from being excessively alerted, it is important, for example, to appropriately adjust an area where the presence of a worker with respect to the work machine is to be detected and a worker presence alert is to be issued to the work machine, in various situations. According to the prior art disclosed in Patent Documents 1 and 2, nothing is taken into consideration about adjusting the area where the presence of a worker is to be detected and a worker presence alert is to be issued to the work machine, so that the operator tends to be excessively alerted and felt bothered, possibly resulting in a reduction in working efficiency. According to Patent Document 1, it is detected whether a worker has entered a predetermined distance from the work machine or not. According to Patent Document 2, the distance of a worker from the work machine is detected. However, since the positional relationship between the work machine and the worker, i.e., information about the distance and direction, is not obtained, the area where a worker presence is to be detected and a worker presence alert is to be issued cannot be adjusted to a nicety.

Furthermore, according to the prior art disclosed in Patent Documents 3 and 4, information about the positional relationship between the work machine and the worker (the distance and direction) can be obtained. However, if at least one of the GNSS receiving section on the work machine and the GNSS reception terminal carried by the worker is unable to receive signals from positioning satellites, then no positional information is obtained, and the worker who is in close proximity to the work machine cannot be detected. Moreover, the positional information that is obtained may possibly suffer large errors due to delays in propagation of radio waves owing to a satellite layout and characteristics of radio-wave propagation routes, and reflections of radio waves caused by walls, buildings, other machines, materials, and so on. Such errors of the positional information may lead to a failure of worker detection and notification and also notice errors.

The present invention has been made in view of the above problems. It is an object of the present invention to provide a work machine which is capable of accurately detecting a worker approaching the work machine and also of preventing itself from excessively alerting the operator thereof.

Means for Solving the Problems

The present application includes a plurality of means for achieving the above objects. According to one example, there is provided a work machine having a machine body with a propulsive device, a multi-joint work implement mounted on the machine body and including a plurality of front members that are angularly movably interconnected, and an operating device for outputting operating signals for operating the work implement, including a GNSS receiving device mounted on the machine body for acquiring positional information of the work machine, at least one magnetic field generating device fixed to the machine body at a predetermined position, for generating a magnetic field signal including a magnetic field ID for identifying a source for generating the magnetic field signal, a tag information receiving device for receiving a radio-wave signal sent from at least one worker tag carried by the operator of the work machine and a worker working outside of the work machine and having a GNSS receiving section for acquiring positional information of the worker tag, the worker tag being responsive to the magnetic field signal generated by the magnetic field generating device for sending the radio-wave signal that includes at least the magnetic field ID included in the received magnetic field signal, a tag ID for allowing the worker tag that has received the magnetic field signal to identify itself, and positional information of the worker tag, a tag detecting device controller for controlling the magnetic field generating device with a detection command, acquiring information included in the radio-wave signal received by the tag information receiving device, and outputting the acquired information as detected tag information, and a controller for determining a detection target area where a position of a worker tag with respect to the work machine is a detection target, and a proximity notification target area where proximity of a worker tag is a proximity notification target in the detection target area, calculating the position of a worker tag based on the positional information of the work machine, the positional information of the worker tag, the detected tag information acquired by the tag detecting device control section, and the detection target area, and generating a notification command and outputting the generated notification command to a notification device to notify the operator of the work machine of the detection of the worker tag in case the worker tag is detected in the proximity notification target area.

Advantages of the Invention

According to the present invention, a work machine is capable of accurately detecting a worker who is in proximity to the work machine and also of preventing itself from excessively alerting an operator thereof.

