Brush cutter with safety device

Abstract

To ensure the safety of people and objects around a brush cutter during a work.SOLUTION: A brush cutter with a safety device comprises a doppler sensor and a processing device that processes the output of the Doppler sensor. The Doppler sensor includes an approaching object detection sensor whose detection direction is a specific direction around the brush cutter and a noise cancellation sensor whose detection direction is a direction different from that of the approaching object detection sensor. The processing device performs processing to remove noise associated with the working operation of the brush cutter which is detected by the noise cancellation sensor from the output of the approaching object detection sensor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a brush cutter with a safety device. [Background technology]

[0002] Brush cutters equipped with safety devices are known. In this prior art, an acceleration sensor is mounted on the brush cutter, and the safety device is activated when the detected value of the acceleration sensor is greater than a threshold value. The acceleration sensor is attached to the brush cutter with its detection axis tilted relative to the left-right direction of the brush cutter (see Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-268732 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the above-mentioned conventional technology, an acceleration sensor is used to detect forces acting on the brush cutter in various directions, and this can detect situations that the operator does not anticipate, such as the brush cutter falling or the blade hitting an obstacle (kickback), and stop the brush cutter from operating. This ensures the safety of the operator working with the brush cutter.

[0005] In contrast, brush cutters have a structural feature in which the cutting blade is mounted at the tip of a long operating rod, so it is necessary to ensure safety not only for the worker using the brush cutter, but also for people and objects around the brush cutter while it is in use.

[0006] During brush cutting, operators have difficulty identifying surrounding sounds due to noises such as the engine's operating sound and the blade's contact sound. In addition, they wear protective gear such as earplugs or earmuffs to block out these noises, making it difficult to hear surrounding sounds. Furthermore, concentrating on the position of the blade while working can narrow the operator's field of vision. This can lead to situations where operators do not notice a person or object approaching and, as they turn around, point the tip of the long operating rod at the approaching person or object. To avoid such situations, there is a need for a brush cutter safety device that can detect people or objects approaching the brush cutter while in operation.

[0007] The present invention has been proposed to address these issues, and aims to ensure the safety of people and objects around a brush cutter in operation by effectively detecting people and objects approaching the brush cutter in operation. [Means for solving the problem]

[0008] In order to solve such problems, the present invention has the following configuration. A brush cutter with a safety device, comprising a main body, an operating rod connected at one end to the main body, and a brush cutting working part attached to the tip of the operating rod, and further comprising a safety device having a Doppler sensor and a processing device for processing the output of the Doppler sensor, wherein the Doppler sensor comprises an approaching object detection sensor whose detection direction is a specific direction around the brush cutter, and a noise cancellation sensor whose detection direction is a direction different from that of the approaching object detection sensor, and wherein the processing device performs processing to remove noise associated with the working operation of the brush cutter, which is detected by the noise cancellation sensor, from the output of the approaching object detection sensor. [Effects of the Invention]

[0009] The present invention, which has these characteristics, can provide a brush cutter with a safety device that, by installing a Doppler sensor in the brush cutter, can effectively detect people or objects approaching the brush cutter while it is in use. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an explanatory diagram showing a brush cutter with a safety device according to an embodiment of the present invention; [Figure 2] FIG. 1 is an explanatory diagram showing the working state of a brush cutter equipped with a safety device. [Figure 3] FIG. 4 is an explanatory diagram showing the function of a processing device in the safety device. [Figure 4] FIG. 4 is an explanatory diagram showing an example of processing by a noise removal unit. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals in different drawings denote parts with the same functions, and duplicated descriptions in each drawing will be omitted as appropriate.

[0012] 1, a brush cutter 10 comprises a main body 11, an operating rod 12 connected at one end to the main body 11, and a cutting unit 13 attached to the tip of the operating rod 12. The cutting unit 13 can be driven in a variety of ways, including by transmitting the rotation of a prime mover (engine or electric motor) mounted on the main body 11 to the cutting unit 13 via a transmission shaft inside the operating rod 12, or by mounting a prime mover (electric motor) on the cutting unit 13 and connecting the prime mover to a battery mounted on the main body 11 via wiring inside the operating rod 12. The cutting unit 13 itself can also be in any form, such as a rotary blade, a reciprocating blade, or a resin cord.

[0013] The safety device 1 provided on the brush cutter 10 includes a Doppler sensor 1A mounted on the brush cutter 10 and a processing device 1B that processes the output of the Doppler sensor 1A. The Doppler sensor 1A emits a transmitted wave within a predetermined detection range, receives a reflected wave returning from the detection range, and outputs a signal including a Doppler signal. The Doppler signal becomes a signal with a different frequency depending on the change in the distance to a moving object within the detection range, based on the phase difference between the transmitted wave and the reflected wave. The processing device 1B removes noise and determines the presence or absence of an approaching object based on the output of the Doppler sensor 1A.

[0014] The Doppler sensor 1A includes an approaching object detection sensor 1A1 whose detection direction is a specific direction around the brush cutter 10, and a noise cancellation sensor 1A2 whose detection direction is a different direction from that of the approaching object detection sensor 1A1. In the illustrated example, the approaching object detection sensor 1A1 is disposed on the side of the brush cutter body 11 opposite to the side to which the operating lever 12 is connected. As a result, the transmission wave emitted by the approaching object detection sensor 1A1 is emitted in the direction opposite to the extension direction of the operating lever 12. Because the operator M of the brush cutter 10 works while looking at the brush cutting working part 13 attached to the tip of the operating lever 12 in the extension direction, the provision of this approaching object detection sensor 1A1 allows the transmission wave to be effectively emitted behind the operator M.

[0015] Furthermore, it is preferable to arrange the approaching target detection sensor 1A1 on the main body 11 below the center line O that passes through the center of the operating stick 12. By arranging the approaching target detection sensor 1A1 below the center line O in this way, it is possible to prevent a part of the main body 11 from interfering with the transmission wave in the working posture shown in FIG.

[0016] In this case, it is preferable to arrange the approaching object detection sensor 1A1 above the bottom 11A of the main body 11. By arranging the approaching object detection sensor 1A1 above the bottom 11A of the main body 11, it is possible to prevent the approaching object detection sensor 1A1 from receiving a direct impact from the ground when the brush cutter 10 is placed on the ground or when the main body 11 of the brush cutter 10 is dropped to the ground, and it is also possible to expect a waterproof effect for the approaching object detection sensor 1A1 when there is a shallow puddle on the ground or water droplets on the grass.

[0017] Furthermore, if a heat source is present in the main body 11, it is preferable to place the approaching object detection sensor 1A1 away from the heat source. More specifically, in the case of an engine-powered brush cutter 10, it is preferable to place the approaching object detection sensor 1A1 below the recoil starter of the main body 11 equipped with the engine. By placing the approaching object detection sensor 1A1 away from the heat source in this way, it is possible to avoid adverse effects caused by exposure to high temperatures.

[0018] As shown in Figure 1, the approaching object detection sensor 1A1 is preferably positioned so that the direction of transmission waves faces approximately parallel to the ground when the operator M is holding the handle 12A of the operating stick 12 and performing brush cutting work, and to achieve this, the approaching object detection sensor 1A1 is preferably positioned on the main body 11 so that the transmission waves are emitted along the central axis O of the operating stick 12, in a direction perpendicular to the rotation axis 13A of the brush cutting working part 13. Furthermore, since reflected waves that return when the transmitted waves hit the ground become noise in detecting approaching objects, to prevent this, it is more preferable to position the approaching object detection sensor 1A1 horizontally or slightly upward with respect to a plane parallel to the ground during brush cutting work.

[0019] More specifically, in those brush cutters in which the angle θa between the operating rod 12 of the brush cutter 10 and the rotation axis 13A of the brush cutting working part 13 is adjustable, it is preferable that the orientation of the approaching object detection sensor 1A1 mounted on the main body 11 can be changed in accordance with the adjustment of the angle θa.

[0020] In contrast, the noise cancellation sensor 1A2 has a detection direction different from that of the approaching object detection sensor 1A1. In the illustrated example, the noise cancellation sensor 1A2 is attached to the operating stick 12 of the brush cutter 10 and faces in the opposite direction to the approaching object detection sensor 1A1, but the noise cancellation sensor 1A2 may also face to the side (sideways) of the brush cutter 10, and the noise cancellation sensor 1A2 may be attached in any manner as long as it moves simultaneously with the approaching object detection sensor 1A1 due to the working operation of the brush cutter 10 and faces in a different direction from the approaching object detection sensor 1A1.

[0021] If the approaching object detection sensor 1A1 is placed on the side opposite to the side to which the operating rod 12 is connected on the main body 11 of the brush cutter 10, the detection range of the approaching object detection sensor 1A1 can be directed behind the worker M while he or she is cutting brush, so that the transmission wave can be effectively emitted into the blind spot behind the worker M.

[0022] As shown in Figure 2, during brush cutting, the brush cutting unit 13 attached to the tip of the operating stick 12 is swung left and right while the work is being performed, so the transmission direction of the approaching object detection sensor 1A1, which is in the opposite direction to the extension direction of the operating stick 12, moves left and right in response to the left and right swing of the operating stick 12. This makes it possible to detect the presence or absence of approaching objects over a wide detection range behind the worker M. In other words, by utilizing the swinging motion of the operating stick during normal work, the detection range can be expanded without the worker having to perform any additional operations.

[0023] However, when the operating stick 12 is swung left and right during brush cutting, the Doppler signal output by the approaching object detection sensor 1A1 provided on the main body 11 contains noise in the Doppler signal due to the movement of the approaching object detection sensor 1A1 in conjunction with the working operation of the brush cutter 10. In contrast, the output of the noise cancellation sensor 1A2 contains a Doppler signal due to the movement of the noise cancellation sensor 1A2 in conjunction with the working operation of the brush cutter 10. However, because the noise cancellation sensor 1A2 moves at the same time as the approaching object detection sensor 1A1, the noise due to the working operation of the brush cutter 10 can be effectively removed by removing the component that changes in synchronization with the output of the noise cancellation sensor 1A2 from the output of the approaching object detection sensor 1A1.

[0024] The processing device 1B of the safety device 1 may be installed on the brush cutter 10 in the same manner as the Doppler sensor 1A, or may be installed at a location separate from the brush cutter 10, for example, on the worker M's clothing (such as work clothes or a harness), as shown in Fig. 1. The output signal from the Doppler sensor 1A to the processing device 1B can be transmitted by wire or wirelessly.

[0025] The function of the processing device 1B will be explained with reference to Fig. 3. The outputs from the approaching object detection sensor 1A1 and the noise cancellation sensor 1A2 of the Doppler sensor 1A are amplified by the signal amplifier 20. The output of the signal amplifier 20 is input to the noise removal unit 21, where noise is removed. The output of the approaching object detection sensor 1A1 and the output of the noise cancellation sensor 1A2 are input to the noise removal unit 21, where noise caused by the working operation of the brush cutter 10 is removed.

[0026] The Doppler signal generated by the movement of the Doppler sensor 1A is generated by the period of the lateral swing of the operating lever 12 during brush cutting, and therefore has a frequency significantly lower than that of the transmitted wave. Furthermore, the noise generated by the working operation of the brush cutter 10 and contained in the output of the approaching object detection sensor 1A1 is a signal synchronized with the time-series change in the output of the noise cancellation sensor 1A2. Therefore, by removing the low-frequency components synchronized with the output of the noise cancellation sensor 1A2 from the output of the approaching object detection sensor 1A1, the noise generated by the working operation of the brush cutter 10 can be removed.

[0027] 4, the noise removal unit 21 can perform the noise removal process described above by calculating the difference between the sensor output of the approaching object detection sensor 1A1 and the sensor output of the noise cancellation sensor 1A2. This process takes advantage of the fact that noise caused by the working operation of the brush cutter 10 is detected by both the approaching object detection sensor 1A1 and the noise cancellation sensor 1A2 as a similar time-series change, and by calculating the difference between the two, the remaining waveform is recognized as the waveform of an object approaching the brush cutter 10.

[0028] The output signal from which noise has been removed by the noise removal unit 21 is subjected to a fast Fourier transform in the FFT calculation unit 22 as needed, and the intensity for each frequency of the output of the noise removal unit 21 is determined. By using the FFT calculation unit 22, it becomes possible to recognize the approach speed of an approaching object, and the approach determination unit 23 can make a more accurate determination.

[0029] In the determination process of the approach determination unit 23, it is determined whether or not an object approaching the brush cutter 10 is present within the detection range of the approaching object detection sensor 1A1. If it is determined that an approaching object is present within the detection range, a determination output is sent to the alarm device 1C or the like.

[0030] The alarm device 1C is a device that alerts the worker M performing brush cutting work of the presence of an approaching object, and issues the alert by, for example, a warning sound, vibration, light-emitting display, etc. Instead of the alarm device 1C, a control device may be provided that has a drive control section to which a judgment output is input, and control is performed to stop the drive of the brush cutting working part 13 in response to the judgment output.

[0031] As described above, the brush cutter safety device 1 according to the embodiment of the present invention has the approaching object detection sensor 1A1 of the Doppler sensor 1A located on the side of the brush cutter body 11 opposite to the side where the operating stick 12 is connected. This enables the detection range of the approaching object detection sensor 1A1 to be directed behind the operator M, which is in the blind spot, and effectively detects people or objects approaching the brush cutter 10 while the brush cutter 10 is in use. This ensures the safety of people and objects around the brush cutter 10 while the brush cutter 10 is in use.

[0032] The Doppler sensor 1A uses an approaching object detection sensor 1A1 and a noise cancellation sensor 1A2, and these are both installed on the brush cutter 10, with the orientation of the noise cancellation sensor 1A2 set to a different direction from that of the approaching object detection sensor 1A1. This allows the process of removing the synchronous component of the output of the noise cancellation sensor 1A2 from the output of the approaching object detection sensor 1A1 to effectively remove noise associated with the working operation of the brush cutter 10.

[0033] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configurations are not limited to these embodiments, and the present invention also includes design changes within the scope of the present invention. Furthermore, the above-described embodiments can be combined by utilizing each other's technologies as long as there are no particular contradictions or problems in their purposes, configurations, etc. [Explanation of symbols]

[0034] 1: Safety device, 1A: Doppler sensor, 1A1: Sensor for detecting approaching objects, 1A2: Sensor for noise cancellation, 1B: Processing device, 1C: Notification device, 10: Brush cutter, 11: Main body, 11A: Bottom, 12: Operating rod, 12A: Handle, 13: brush cutting working part, 13A: rotating shaft, 20: signal amplifier, 21: noise removal unit, 22: FFT calculation section, 23: Approach judgment section, M: Worker

Claims

1. A brush cutter comprising a main body, an operating rod connected at one end to the main body, and a brush cutting unit provided at the tip of the operating rod, a safety device including a Doppler sensor and a processing device for processing an output of the Doppler sensor; the Doppler sensor includes an approaching object detection sensor whose detection direction is a specific direction around the brush cutter, and a noise cancellation sensor whose detection direction is a direction different from that of the approaching object detection sensor, The processing device performs processing to remove noise associated with the working operation of the brush cutter, which is detected by the noise cancellation sensor, from the output of the approaching object detection sensor.

2. The approaching object detection sensor includes:

2. The brush cutter with a safety device according to claim 1, wherein the safety device is disposed on the side of the main body opposite to the side to which the operating rod is connected.

3. 2. A brush cutter with a safety device as described in claim 1, wherein the orientation of the approaching object detection sensor is such that, when the operating stick is tilted relative to the ground while working, the sensor is installed in a direction substantially parallel to the ground or facing upward from that direction.

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