JP2018014963A - Self-propelled work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-propelled work machine capable of accurately carrying out contact detection by a contact detection mechanism for detecting contact of foreign matter with a body.SOLUTION: There is provided a self-propelled work machine having a body chassis 10 for holding a motor for travel and a motor for work, a body cover 2 for covering them, and a contact detection mechanism for detecting contact of a foreign matter with the body cover 2, which carries out work while autonomously travelling in a work area. The contact detection mechanism is composed of magnets 6 and 7 fixed to the body cover 2 in a state of being longitudinally offset, and Hall sensors 46 and 47 provided adjacent to them. A control device can accurately detect a collision state not only during straight advancing but also during turning by changing detection thresholds of the Hall sensors 46 and 47 depending on whether a grass mower 1 is advancing straight or turning.SELECTED DRAWING: Figure 3

Description

The present invention relates to a self-propelled working machine that performs a desired work while traveling autonomously in a work area by operating a work device using an electric motor as a drive source.

2. Description of the Related Art Self-propelled working machines that perform various operations by automatically traveling in a work area partitioned by wires and walls that generate a magnetic field are known. This self-propelled working machine is applied to mowing work is a self-propelled mower. A self-propelled mower is a tool that cuts grass while automatically running in a mowing area defined by wires, etc., for a wheel motor for driving wheels and a cutting blade for driving a mowing blade for mowing. These motors are provided independently, and a secondary battery for supplying electric power to these motors is mounted, and the autonomous running is controlled by the control device. As such a self-propelled mower, a technique shown in Patent Document 1 is known. Here, an example of use of a conventional self-propelled mower will be described with reference to FIG. In FIG. 13, a lawn (not shown) is planted in a garden 210 adjacent to the house 200, and this is a mowing area 290 that is a target for mowing. In the mowing area 290, a self-propelled mower 3 on the lawn
01 is arranged. A charging station 270 for charging the mower 301 is disposed in the mowing area 290. Charging station 270 is installed in the corner of the lawn mowing area, and is connected to AC adapter 250 by cable 260. The AC adapter 250 is connected to an outlet (not shown) such as a commercial AC power source, and converts an AC voltage (for example, 230 V) supplied from the outlet into a DC voltage (for example, 21 V). The charging station 270 has a DC output terminal (positive electrode, negative electrode). When the mower 301 reaches the charging position of the charging station 270, the power receiving terminal (not shown) of the mower 301 is connected to the DC output terminal of the charging station 270 ( (Not shown) to stop and contact the mower 301 from the charging station 270 side.
Power is supplied to the side, and the mower 301 charges the mounted secondary battery.

In order to help the mower 301 autonomously travel, boundary notification means using a boundary cable, a fence, radio, light, or the like is arranged in advance at the boundary portion between the grass cutting area 290 and other areas in the garden 210. The In FIG. 13, a guide wire (guide wire) 280 formed in a loop shape is disposed (for example, embedded) as a boundary notification means. The arrangement of the guide wire 280 is performed in advance by the user of the mower 301 before mowing, and the self-propelled mower 301 performs the mowing work in an inner region having the guide wire 280 as an outer edge. An induction signal generator (not shown) in the charging station 270 is connected to the guide wire 280, and a pulsed current flows at a predetermined interval. The mower 301 detects a magnetic field generated by the current flowing through the guide wire 280 to determine whether it is inside or outside the guide wire 280, and performs mowing work while traveling automatically and autonomously.

Japanese Patent Laid-Open No. 2015-15922

The mowing area 290 on which the mowing machine travels is not necessarily a flat area without an obstacle, and may hit a curb or a figurine. In a self-propelled work machine, when it comes in contact with an obstacle during forward / backward movement, the control device detects the contact and controls to avoid the obstacle by moving it in the direction opposite to the collision direction. To do. In addition, when the main body cover climbs while colliding with an obstacle, the main body cover moves upward with respect to the main body chassis, or when a mowing machine that is running is lifted by a human hand, mowing is performed. Since the work is hindered, the rotation of the cutting blade as the work equipment is immediately stopped, and in some cases, the traveling motor is also stopped. In this way, a contact detection mechanism for detecting the contact of the mower with a foreign object is provided, and an appropriate avoidance operation or a return action to normal work is performed after the contact. In order to realize the contact detection mechanism, in the conventional self-propelled mower, the main body cover that is covered on the upper side of the main body chassis is held in a movable state within a predetermined range via a cushioning material such as a leaf spring. I made it. And
A magnet is provided on the main body cover side, and a magnetic detection element is provided on the main body chassis side, thereby realizing a contact detection mechanism that detects whether the main body cover has touched any object.

The objective of this invention is providing the self-propelled working machine which can perform the contact detection by the contact detection mechanism which detects the contact of the foreign material to a main body with sufficient precision.
Another object of the present invention is a self-propelled type in which contact detection is performed with high accuracy by changing a threshold for detection in accordance with a control state of a motor in contact detection processing using a plurality of contact detection mechanisms. It is to provide a working machine.
Still another object of the present invention is to provide a self-propelled working machine that uses a plurality of sets of magnets and magnetic sensors to accurately detect not only the collision state during straight traveling but also the collision state during turning. There is.

The characteristics of representative ones of the inventions disclosed in the present application will be described as follows.
According to one aspect of the present invention, a traveling motor that drives wheels, a working motor that drives work equipment, a secondary battery that supplies power to these motors, a traveling motor, and a working motor. In a self-propelled working machine that includes a control device that performs control and a contact detection mechanism that detects contact of a foreign object with the main body and autonomously travels in a work area, the contact detection mechanism detects The threshold for determining contact from the output can be changed. In addition, the self-propelled working machine has a main body chassis that holds the traveling motor and the working motor, and a main body cover that covers these, the contact detection mechanism detects an external force applied to the main body cover, and the control device At least two threshold values for determining contact from the output detected by the detection mechanism are provided. These threshold values are changed by the control device in accordance with the control status of the traveling motor and / or the working motor. For example, the threshold values are changed when the main body goes straight and turns.

According to another feature of the present invention, the traveling motor has two independent motors for driving the right wheel and the left wheel. The two motors are synchronously rotated when traveling straight, and the two motors are rotated when turning. Rotate asynchronously. Asynchronous means that only one motor is rotated to stop one motor, one motor is rotated and the other motor is rotated in the reverse direction, or both motors are rotated in the same direction at different speeds. In either case. In addition, when the control device determines that contact has occurred during travel by the contact detection mechanism, the control device controls the self-propelled work machine to travel slightly in the direction opposite to the direction of movement during the collision to avoid contact. To do. The main body cover is held in a movable state via a cushioning material such as a leaf spring with respect to the main body chassis, and a pair of sensors are provided on the main body cover and the main body chassis, and contact with the front side is performed using one of the pair of sensors. Detection was performed, contact with the rear side was detected using the other, and the lift state was detected using the detection results of both sensors. The pair of sensors includes a magnetic detection element attached to the main body chassis and a magnet provided on the main body cover, and the output of the magnetic detection element is transmitted to the control device.

According to still another feature of the present invention, at least two types of sensors having different detection methods are provided, and the control device can make a difference in detection sensitivity with respect to a signal from each sensor. Moreover, in addition to the contact detection mechanism using a magnetic detection element and a magnet, the impact sensor provided in the main body cover was provided.

ADVANTAGE OF THE INVENTION According to this invention, the contact detection mechanism which can detect the contact of the foreign material with a main body cover accurately can be implement | achieved, making the sensor which detects the collision of the front-back direction and the sensor which detects the collision of the left-right direction common.
In addition, since the detection threshold of the contact detection mechanism is changed when the self-propelled work machine goes straight and turns, optimal contact detection according to the self-propelled work machine operation mode such as the travel mode and work mode is performed. It can be carried out.
The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

1 is a side view of a self-propelled mower 1 according to an embodiment of the present invention at a normal time (only a cover portion is a longitudinal sectional view). It is a side view in the state where body cover 2 of mower 1 concerning an example of the present invention was lifted (only a cover part is a longitudinal section). It is a top view of the main body chassis 10 of the mower 1 which concerns on the Example of this invention. It is a top view which shows the state which the main body cover 2 of the mower 1 contacted from the front. It is a top view which shows the state which the main body cover 2 of the mower 1 contacted from back. It is a top view which shows the state which the main body cover 2 of the mower 1 contacted from the right side. It is a top view which shows the state which the main body cover 2 of the mower 1 contacted from the left. 1 is a block diagram of a mower 1 according to an embodiment of the present invention. It is a flowchart which shows the control procedure which detects the contact state and lift state of the mower. It is a figure which shows the relationship between the output of a Hall sensor, and a threshold value at the time of the straightening of the mower 1 (1st operation state). It is a figure which shows the relationship between the output of a Hall sensor at the time of turning of the mower 1 (2nd operation state), and a threshold value. It is a longitudinal cross-sectional view of the self-propelled mower 101 according to the second embodiment of the present invention. It is a figure for demonstrating the operation | movement outline | summary of the mower 301 in a prior art.

Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the self-propelled mower 1 is used as an example of the self-propelled working machine, the same portions are denoted by the same reference numerals, and repeated description is omitted. Further, in this specification, description will be made assuming that the front, rear, left, right, and up and down directions are directions shown in the drawing.

FIG. 1 is a side view of a mower 1 according to an embodiment of the present invention, and only a main body cover 2 is shown in a sectional view. The mower 1 is provided with a small-diameter front wheel 12 that is swingable along the traveling direction and a large-diameter rear wheel 13 that is a drive wheel on the left and right of the main body chassis 10, respectively. The mower 1 is made of synthetic resin. The main body cover 2 covers the entire upper part and most of the sides. The power source of the mower 1 is a detachable battery pack (described later), and a microcomputer (
Hereinafter, the wheel motor (not shown) is driven by the “microcomputer”) to run autonomously. A cutting blade motor (not shown) is disposed near the center of the main body chassis 10, and a rotating cutting blade 35 is provided at the lower end of the rotating shaft of the cutting blade motor extending in the vertical direction. Cutting blade 3
Reference numeral 5 denotes a swingable blade portion 35b disposed at a plurality of locations on the outer peripheral side of the synthetic resin disc portion 35a. The blade portion 35 is moved by moving the attachment position of the motor for the cutting blade in the vertical direction.
The height of b from the ground, that is, the height of grass cutting can be adjusted. The cutting blade 35 is rotated while the mower 1 is traveling, so that traveling and mowing work are performed simultaneously.
The front lower end of the main body cover 2 has a predetermined gap, and the grass that has entered the main body cover 2 through this gap is cut by a cutting blade 35 disposed on the lower side of the main body chassis 10.

The main body cover 2 is connected to the main body chassis 1 via leaf springs 16b, 18b, which are metal cushioning materials.
It is held in a movable state while floating from 0. The lower end of the leaf spring 16b is held by a mounting member 17b movable in a predetermined range in the vertical direction, and the upper end is fixed to a support member 4a formed on the inner peripheral side of the main body cover 2. The fixing method on the leaf spring 16a (described later) side not shown in FIG. 1 is also the same. Similarly, the upper end of the leaf spring 18 b is fixed to a support member 4 c formed on the inner peripheral side of the main body cover 2. Thus, the leaf | plate springs 16b and 18b deform | transform and the main body cover 2
Is movable in the front-rear direction with respect to the main body chassis 10. Here, leaf springs 16a and 16b (16a will be described later with reference to FIG. 3) are disposed on the left and right sides on the front side of the main chassis 10, and leaf springs 18a and 18b (18a will be described with reference to FIG. 3) on the left and right sides on the rear side. Is done. Leaf spring 16a,
The shapes of 16b, 18a, and 18b are plate-like so that the surfaces face in the front-rear direction. By holding the main body cover 2 via the cushioning material in this way, when the main body cover 2 collides with some object or receives an external force that lifts the main body cover 2 from the outside, the main body cover 2
Move relative to the main body chassis 10 instantaneously. In order to detect the relative movement between the main body cover 2 and the main body chassis 10 by a control device, a contact detection mechanism is provided. The contact detection mechanism detects a change in the relative positional relationship between the main body cover 2 and the main body chassis 10 to thereby detect the main body cover 2.
Is detected to be in contact with some external object, or some sort of impact is applied to the main body cover 2, and here it is configured using a magnet and a Hall sensor (magnetic detection element). Magnets 6 and 7 (6 will be described later) are provided on the main body cover 2 side, Hall sensors 46 and 47 (46 will be described later) are provided on the main body chassis 10 side, and the magnets 6 and 7 are adjacent to the hall sensors 46 and 47. In addition, they are arranged in a non-contact state. A magnet holder 2c extending from the upper wall portion to the lower wall portion on the inner wall surface of the main body cover 2 and having a rectangular cross section is formed, and the magnets 6 and 7 are disposed on the inner circumferential wall surface. The hall sensors 46 and 47 are mounted on rectangular sensor boards 36 and 37 (the sensor board 36 is not visible in the figure), and the sensor boards 36 and 37 are substantially pedestals when viewed from the front held on the body chassis 10 side. The support member 38 formed in a shape is fixed to the left side surface and the right side surface.

A large opening is formed on the upper side of the main body cover 2, and the opening / closing cover 3 is provided so as to cover the opening. The opening / closing cover 3 is configured to be opened / closed by a hinge 3a around a rotation axis on the front side, and an opening / closing sensor 21 detects whether or not the opening / closing cover 3 is open. Open / close cover 3
Is constituted by, for example, a translucent resin member, and the rear side lock of the opening / closing cover 3 is released by pressing a stop button 9 disposed on the rear side, so that the opening / closing cover 3 can be opened. The stop button 9 is a button for emergency stop of the mower 1, and when the operator pushes it, the motor for traveling and the motor for working (for cutting blade) can be stopped instantaneously. The stop button 9 also serves as a function of releasing the lock of the opening / closing cover 3.
When the opening / closing cover 3 is opened, the operator can access a dial 20 that adjusts the vertical position of the motor for cutting blades, and a keyboard and display described later. In front of the main body cover 2, a substantially rectangular opening 5 elongated in the lateral direction in the front view is provided. The opening 5 is an opening provided so that a power receiving terminal (not shown) of the mower 1 and a power transmission terminal of the charging station 270 can come into contact with each other when the mower 1 reaches the charging station 270.

A container portion 22 that houses a battery pack is provided on the rear side of the main body chassis 10. The container portion 22 can be opened and closed at an upper lid portion by a hinge 23 on the front side. The main board on which the control circuit including the microcomputer is mounted is provided inside the container portion 22 of the main body chassis 10 or in the vicinity thereof. The battery pack is compatible with those widely used in electric tools such as impact drivers, and a plurality of secondary battery cells (not shown) are accommodated therein.

A brush blade DC motor (not shown) is housed in the motor cylinder 34, and a brushless DC motor in which a rotor core (not shown) having a permanent magnet rotates inside a stator (not shown) wound with an exciting coil. Used. A circular circuit board (not shown) is provided inside the motor cylinder 34 and above the cutting blade motor, and there are a plurality of Hall ICs (not shown) and an inverter circuit (not shown). Is installed. The inverter circuit is a known inverter circuit configured by including a plurality of switching circuits such as FETs (field effect transistors) and IGBTs (insulated gate bipolar transistors).

FIG. 2 is a view showing a state where the front side of the main body cover 2 of the mower 1 is lifted. Here, the state in which the main body cover 2 is lifted may be that the main body cover 2 is lifted upward as indicated by an arrow 28a by a human hand, or the front lower end of the main body cover 2 rides on an obstacle such as a stone. In some cases, a force such as an arrow 28a is applied. On the front side of the main body cover 2, the leaf spring 1 is attached by mounting members 17 a and 17 b (17 a is not visible) that can move in a predetermined range in the vertical direction.
In order to hold 6a and 16b (16a is not visible), the attachment member 17b is fully extended upward as indicated by an arrow 28b. For this reason, the magnet 7 is largely moved upward with respect to the hall sensor 47 fixed to the main body chassis 10. Mounting members 17a, 17
b (17a is not visible) is a cylindrical member in which flanges for preventing slipping are formed at both ends inserted into holes (not shown) of the main chassis 10, and plate springs 16a, 16b (
16a is not visible). When an external force such as an arrow 28a is not applied to the main body cover 2, the upper flange portion is brought into contact with the main body chassis 10 by gravity (FIG. 1).
The position shown in FIG. As described above, the main body cover 2 has a shape that covers almost the entire body chassis 10 except for the ground side, and is held in a floating state with respect to the main body chassis 10 by a spring or the like. It can move slightly in the vertical direction. The main body cover 2 may collide with obstacles such as rocks, protrusions, and walls, and the relative position fluctuation of the main body cover 2 at that time is detected by a contact detection mechanism described later using a hall sensor and a magnet.

FIG. 3 is a top view of the main body chassis 10 portion of the mower 1 according to the embodiment of the present invention. Here, the outer edge position of the main body cover 2 is indicated by a dotted line, and the magnet holder 2c provided on the main body cover 2 side and the magnets 6 and 7 attached to the magnet holder 2c are shown in a sectional view. The main body chassis 10 has a convex tip and is narrowed down into a triangle when viewed from above, and the mounting arms 11 (11a, 11b) of the wheels are provided on both the left and right sides of the slope so as to extend toward the front outer side. Front wheels 12 (12a, 12b) are pivotally supported on the mounting arms 11a, 11b by a rotating shaft extending in the vertical direction, and are respectively held so that the direction of the wheels can follow the moving direction of the mower 1. Is done. Rear wheels 13 (13 a, 13 b) are provided on the rear side of the main body chassis 10. Here, a large-diameter wheel is used for the rear wheel 13, and each is driven by an independent traveling wheel motor (right wheel motor 15a, left wheel motor 15b). The two wheel motors enable steering control by a microcomputer included in the control device by being driven synchronously or asynchronously. The rotation shaft of the wheel motor 15a is directly connected to the right wheel 13a, and the rotation shaft of the wheel motor 15b is directly connected to the left wheel 13b. The wheel motor and wheels 13a, 1
3b may be rotated via a speed reduction mechanism. In this structure, the rear wheel 13a,
The mower 1 moves straight forward or backward by rotating 13b in the same direction in synchronization. On the other hand, by rotating the rear wheels 13a and 13b so as to cause a rotation difference, a turning operation for turning the mower 1 in a specific direction can be performed. Right wheel motor 15a, left wheel motor 15b
For example, a brushless DC motor is used, and is driven via an inverter circuit (not shown).

The leaf springs 16a, 16b are located near the base of the main body chassis 10 of the mounting arms 11a, 11b.
In order to hold b, the mounting member 17a is slidably held within a limited range in the vertical direction.
, 17b are provided. The attachment members 17a and 17b are parts made of synthetic resin such as plastic, and are held so as not to fall out of the attachment arms 11a and 11b. Similarly, mounting members 19 are provided on both rear sides of the main body chassis 10 in order to hold the leaf springs 18a and 18b.
a and 19b are provided. The mounting members 19a and 19b may be slidably held within a limited range in the vertical direction. However, since the mounting members 19a and 19b are located away from the contact detection mechanism such as the hall sensors 46 and 47, the mounting member 19a. , 19b may be fixed so as not to move relative to the main body chassis 10 in the vertical direction.

A display 24 such as a liquid crystal display panel, a main switch 25, and a keyboard 26 are provided on the upper surface of the container portion 22 provided near the center of the main body chassis 10. The operator can set a mowing schedule by operating the keyboard 26. A rotary dial 20 is provided on the front side of the container portion 22. Here, the height of the cutting blade 35 from the ground can be adjusted by rotating the dial 20, and the distance (cutting height) between the blade portion 35b and the ground is 20 to 20 as indicated by the numerical value on the dial scale. It can be set within a range of 60 mm.

Two hall sensors (a right hall sensor 46 and a left hall sensor 47) are provided near the front end of the main body chassis 10 and on the front side of the dial 20. The right hall sensor 46 and the left hall sensor 47 are fixed to the main body chassis 10 through a small sensor board.
The main body chassis 10 is disposed at a position that is plane-symmetrical from the left-right center vertical plane. Outputs of the right hall sensor 46 and the left hall sensor 47 are connected to a control device described later via wiring. on the other hand,
The inner wall portion of the main body cover 2 has a magnet holder 2c which is a cylindrical member having a rectangular cross-sectional shape.
Is arranged so as to extend from the upper wall portion to a position close to the main body chassis 10. Two magnets 6 and 7 are fixed inside the magnet holder 2c. The magnets 6 and 7 are arranged so that the center heights of the right hall sensor 46 and the left hall sensor 47 coincide with each other, but the right magnet 6 is arranged closer to the front than the right hall sensor 46 in the front-rear direction. The left magnet 7 is arranged behind the left hall sensor 47. Since the right magnet 6 and the left magnet 7 are offset in the front-rear direction with respect to the hall sensors 46 and 47 in this way, the contact direction received by the main body cover 2 is detected (collision from the front direction or rear direction). Can be performed with high accuracy.

FIG. 4 is a top view showing a state in which the main body cover 2 of the mower 1 is in contact from the front (state 1).
. Here, a state in which the mower 1 traveling straight forward collides with a foreign object is shown. When the mower 1 traveling straight forward collides with a foreign object, the main body cover 2 as indicated by an arrow 56.
An external force that pushes the back side is applied. Since the rear wheel 13 (13a, 13b) provided on the main body chassis 10 is driven against the force of the arrow 56, the main body cover 2 moves relative to the rear side with respect to the main body chassis 10. . The magnet holder 2c at this time is indicated by an arrow 2
It moves in the direction approaching the dial 20 as in 8c. (2) is the elements on larger scale of the contact detection mechanism part of (1). As shown in (2), since the magnet holder 2c moves relative to the rear side of the main body chassis 10, the center position of the right magnet 6 is relative to the center position in the front-rear direction of the right hall sensor 46 and the left hall sensor 47. Although it leaves | separates back only the distance 56a, since the magnet 6 is located on the axis line of the right hall sensor 46, there is almost no output fall of the right hall sensor 46. On the other hand, the center position of the left magnet 7 is far away rearward from the axis of the left Hall sensor 47 as shown by a distance 56b. Therefore, the magnet 7 is not positioned on the axis of the left hall sensor 47, and the output signal of the left hall sensor 47 is greatly reduced.

Here, the output relationship between the right hall sensor 46 and the left hall sensor 47 will be described with reference to FIG. The magnets 6 and 7 used in the mower 1 are, for example, ferrite magnets having opposite polarities on one surface and the other surface. The magnets 6 and 7 used are not limited to ferrite magnets but may be any magnets having magnetic poles. The right hall sensor 46 and the left hall sensor 47 output 4.4 V, for example, when the specific polarity approaches, and drop to an output voltage of about 2.7 V, for example, when the magnet is separated and the influence of the magnetic field is eliminated. From this characteristic, by monitoring the output voltage of the right hall sensor 46 and the left hall sensor 47, the microcomputer included in the control circuit has the magnets 6 and 7 facing the right hall sensor 46 and the left hall sensor 47. Whether or not and the distance can be determined by the voltage. However, it can be determined how far the distance is, but it cannot be determined in which direction. Therefore, in this embodiment, the two magnets 6 and 7 are arranged so as to be shifted in the front-rear direction so that the output of the hall sensor on one side is lowered when a collision occurs from the front direction or the rear direction. Thus, the relative movement of the main body cover 2 in the front-rear direction can be detected.

In FIG. 10, the horizontal axis is the output voltage (unit V) of the right hall sensor 46, and the vertical axis is the output of the left hall sensor 47. The black circle 70 is a state when the main body cover 2 is at the reference position with respect to the main body chassis 10 as shown in FIG. 3, that is, a state where no foreign matter collides with or comes into contact with the main body cover 2. In this case, as shown in FIG. 3, the magnets 6, 7 are adjacently opposed to each other on the axis of the right hall sensor 46 and the left hall sensor 47.
And the output of the left Hall sensor 47 are both about 4.4 V, and when they are plotted, a black circle 70 is obtained. When the main body cover 2 is moved rearward relative to the main body chassis 10 as shown in FIG. 4 (1) from this state, the distance 56b between the left Hall sensor 47 and the magnet 7 is separated as shown in FIG. 4 (2). Therefore, the output of the left hall sensor 47 drops to about 2.7V.
On the other hand, since the distance 56a seen in the front-rear direction of the right hall sensor 46 and the magnet 7 is not so far away, the output of the right hall sensor 46 remains at about 4.4V. When this is plotted, a black circle 71 in FIG. 10 is obtained, and the plot position is moved from the black circle 70 to the black circle 71. Here, in the present embodiment, the outputs of the right hall sensor 46 and the left hall sensor 47 are set to 3.0 V as a threshold value for determining whether the main body cover 2 is in contact or not in straight travel (forward, backward). did. If any of the outputs of the right hall sensor 46 and the left hall sensor 47 falls below the threshold voltage, the microcomputer determines that the main body cover 2 is in contact. That is, since the state of the black circle 71 is within the area 82a, the microcomputer determines that the collision has occurred from the front side.

FIG. 5 is a top view showing a state in which the main body cover 2 of the mower 1 is in contact with the rear (state 2).
. Here, a state in which the mower 1 collides against some foreign object while going straight backward is shown, and (1) is a top view. Here, because the vehicle is moving backward, right front wheel 12a and left front wheel 12b
Is located on the front side of the mounting arms 11a, 11a and is driven. Mower 1 straight ahead
When an object collides with a foreign object, an external force is applied to push the main body cover 2 forward as indicated by an arrow 57. Then, since the rear wheel 13 provided in the main body chassis 10 is retracted against the force of the arrow 57, the main body cover 2 moves relative to the front side with respect to the main body chassis 10. The magnet holder 2c at this time moves in a direction away from the dial 20 as can be seen from the positional relationship near the arrow 28d. In addition, as shown in the partial enlarged view of (2), the magnet holder 2
Since c moves relatively to the front side of the main body chassis 10, the center position of the right magnet 6 is greatly separated from the center position of the right hall sensor 46 and the left hall sensor 47 to the front side as a distance 57a. The center position of the left magnet 7 is slightly separated from the front side as a distance 57b. Accordingly, the right hall sensor 46 and the left hall sensor 47 at this time.
The output relationship moves from a black circle 70 to a black circle 72 in FIG. Since the position of the black circle 72 is lower than the threshold voltage 3.0V of the right hall sensor 46, it belongs to the area 82b, and the microcomputer determines that the main body cover 2 has collided from behind.

As described above, by using the two Hall sensors 46 and 47, it is possible to easily identify the case where the mower 1 collides from the front side and the case where the mower 1 collides from the rear side. FIG. 4
The external force shown by the arrow 56 in FIG. 5 and the external force shown by the arrow 57 in FIG. 5 are relative, so that the foreign matter that has moved with respect to the mower 1 that is almost stopped (however, the cutting blade motor 30 is movable) Arrow 56,
Even in the case of a collision in the direction 57, the microcomputer performs the same detection. In this embodiment, the magnet 6
, 7 are displaced in the front-rear direction, and a front-side or rear-side collision can be detected efficiently. This detection method can also be applied to determine whether a lift condition has occurred. Although the magnets 6 and 7 are arranged to be shifted in the front-rear direction, the height direction is arranged in accordance with the height of the hall sensors 46 and 47. Therefore, when the operator lifts the main body cover 2 as shown in FIG. 2, the magnets 6 and 7 are both configured to be displaced upward, so that they are separated upward from the axes of the two hall sensors 46 and 47. As a result, the outputs of both the Hall sensors 46 and 47 are reduced to about 2.7V. A black circle 73 in FIG. 10 plots the output voltage at this time. In the area 83, since the outputs of both the hall sensors 46 and 47 are equal to or less than the threshold value, the main body cover 2 is determined to be in the lift state. In this embodiment, the hall sensor that detects the collision in the front-rear direction and the hall sensor that detects the collision in the left-right direction are common, and the black circle position plotted using the detection results of both the hall sensors 46 and 47 is determined. Since the collision state and the lift state are determined depending on whether the region (82a, 82b, 83) has moved, the contact detection mechanism using the Hall sensors 46 and 47 serves not only as a contact detection in the front-rear direction but also as a lift sensor. Can also fulfill.

As described above, the contact between the two driving wheels is detected using the two Hall sensors 46 and 47 in a state where the mower 1 advances straight forward or rearward (straight forward state). In the case of the mower 1 that performs the turning steering using the rotation difference, there is a possibility that the collision state cannot be detected with high sensitivity when it collides during turning. Therefore, in this embodiment, the mower is switched between the detection threshold of the Hall sensors 46 and 47 in the straight traveling state (first state) and the detection threshold of the Hall sensors 46 and 47 in the turning state (second state). The contact detection mechanism is appropriately operated according to the operation status of 1. In other words, the mower 1 includes a plurality of tables for determining the detection values of the hall sensors 46 and 47 according to the operation status.

FIG. 6 is a top view showing a state where the mower 1 at the time of turning contacts the right side. In this state, the left wheel motor 15b rotates in the forward direction and the right wheel motor 15a rotates in the stop or reverse direction, so that the mower 1 is turning in the right direction. It shows a state of collision with an obstacle. This driving state can be recognized by the positions of the right front wheel 12a and the left front wheel 12b, and the turning center is near the center of the right front wheel 12a and the left front wheel 12b. If a collision occurs during the turning, an external force is applied to the main body cover 2 from the right side as indicated by an arrow 58. Then, the main body cover 2 moves to the left with respect to the main body chassis 10, and the magnet holder 2 c moves to the left of the left and right center line of the main body chassis 10 as can be seen from the positional relationship near the arrow 28 e. As shown in the partial enlarged view of (2), the magnet holder 2
Although c does not move relative to the main body chassis 10 when viewed in the front-rear direction, it moves to the left as viewed in the left-right direction. As a result, the magnet 6 and the hall sensor 46 approach (or collide) while the magnet 7 and the hall sensor 47 are separated. As described above, the output voltage of the Hall sensor 47 is lowered due to the change in the position of the magnets 6 and 7 with respect to the axial direction of the Hall sensors 46 and 47, and the output voltage of the Hall sensor 46 is slightly increased.

Here, the output relationship between the right hall sensor 46 and the left hall sensor 47 will be described with reference to FIG. The relationship between the vertical axis and the horizontal axis is as described with reference to FIG. 10, but the threshold voltages of the hall sensors 46 and 47 are changed in the relationship shown in FIG. A black circle 70 is an output signal at the reference time, and the outputs of the right hall sensor 46 and the left hall sensor 47 are both about 4.4V. When the collision shown in FIG. 6 occurs from this state, the output of the left hall sensor 47 decreases, but the output of the right hall sensor 46 hardly changes. Therefore, when the position is plotted, a black circle 73 is obtained. The reason why the output of the right Hall sensor 46 hardly changes is that the detected magnetic field has already reached the saturation amount at the reference position shown in FIG. Here, the threshold voltages of the right hall sensor 46 and the left hall sensor 47 during turning are both set to 4.0 V, and when the voltage falls below any of these, the microcomputer determines that a contact state has occurred. In FIG. 11, the microcomputer determines that “no contact” only when it is within the narrow range of the area 86, and determines that it is “contacted” from the right when it is within the area 87a, and is within the area 87b. In some cases, it is determined that “touched” from the left. If it is determined that the contact has occurred, the microcomputer reverses the direction of rotation of the wheel motor 15 to eliminate the collision state of the mower 1. When the plotted black circle falls within the range of the area 88, the microcomputer determines that “the lift state is in effect”.

FIG. 7 is a top view showing a state in which the mower 1 at the time of turning contacts the left side. This state is a state where the right wheel motor 15a rotates in the forward direction and the left wheel motor 15b rotates in the stop or reverse direction, so that the mower 1 is turning leftward. It shows a state of collision with an obstacle. At this time, an external force is applied to the main body cover 2 from the left side as indicated by an arrow 59. Then, the main body cover 2 moves to the right side with respect to the main body chassis 10, and the magnet holder 2 c moves to the right of the left and right center line of the main body chassis 10 as can be seen from the positional relationship near the arrow 28 f. As shown in the partial enlarged view of (2), the magnet holder 2c is not relatively moved relative to the main body chassis 10 when viewed in the front-rear direction, but is relatively moved in the left-right direction. As a result, the magnet 7 and the hall sensor 47 approach (or collide), while the magnet 6 and the hall sensor 46 separate. The positional relationship in the front-rear direction is that the center position of the right hall sensor 46 and the magnet 6 is a distance 59a, and the center position of the left hall sensor 47 and the magnet 7 is a distance 59b. The magnets 6 and 7 do not deviate from the axis line. Due to this positional relationship, the output voltage of the hall sensor 46 slightly decreases, and the output voltage of the left hall sensor 47 maintains substantially the same voltage.

When this state is shown in FIG. 11, the output of the right hall sensor 46 decreases from the black circle 70 and the output of the left hall sensor 47 does not change, so the plot position moves from the black circle 70 to the black circle 74. Therefore, since the position of the black circle 74 falls below the threshold value of the right hall sensor 46 and is located in the area 87b, the microcomputer reverses the rotation direction of the wheel motor 15 to eliminate the collision state even if the contact state occurs. I tried to do it. As described above, the microcomputer switches the detection threshold value of the hall sensors 46 and 47 when changing the steering of the wheel motor from straight to turning, or when changing from turning to straight. The collision at the time can be detected accurately.

FIG. 8 is a block diagram showing various functional components provided in the main body chassis 10 of the mower 1. A control device 50 that controls the operation of the mower 1 is mounted on the main circuit board. Control device 5
0 includes a microcomputer, a storage device (not shown), a charging circuit, and other electronic elements. The microcomputer of the control device 50 includes a power receiving terminal 41 having a positive terminal and a negative terminal that can be connected to the two power transmission terminals (positive and negative) of the charging station 270, and a terminal of the battery pack attached to the battery mounting portion. A battery terminal 29 to be freely connected is connected. The main switch 25 is inserted into the connection line between the battery terminal 29 and the control device 50.
Or a power supply switch to a motor or the like. The control device 50 includes a cutting blade motor 30 and wheel motors (right wheel motor 15a and left wheel motor 15b).
a to 27c. The motor drive circuits 27a to 27c include inverter circuits, and generate a three-phase alternating current excitation current from a direct current voltage according to a PWM control signal controlled by the control device 50 to produce a cutting blade motor 30, a right wheel motor 15a, a left The wheel motor 15b is rotated. The microcomputer included in the control device 50 rotates the cutting blade motor 30 to rotate the cutting blade 3.
5 is rotated. In addition, the control device 50 causes the mower 1 to move straight by rotating the right wheel motor 15a and the left wheel motor 15b at the same speed, and turns the mower 1 by rotating at different speeds. Further, the control device 50 detects the load currents of the cutting blade motor 30, the right wheel motor 15a, and the left wheel motor 15b flowing through the motor drive circuits 27a to 27c, thereby detecting the magnitude of the load related to each motor. .

A display / keyboard board 43 and a stop switch 49 are connected to the control device 50, and various types such as a first guide wire sensor 44, a second guide wire sensor 45, a right hall sensor 46, a left hall sensor 47, and a tilt sensor 48 are provided. Sensor output is input. The first and second guide wire sensors 44 and 45 have a coil for detecting a change in the magnetic field generated by the guide wire 280 (see FIG. 13), and the signal detected by the coil is the control device 5.
Output to 0. The control device 50 identifies the boundary of the mowing area from the outputs of the two guide wire sensors 44 and 45, and performs driving and steering control of the mower 1. The stop switch 49 is a manual stop means, and the stop button 9
(See FIG. 1) is provided, and the user can manually stop the mower 1 during automatic traveling or mowing. The display / keyboard board 43 holds a liquid crystal display 24 (see FIG. 3) that is an output device for information on mowing and a keyboard 26 (see FIG. 3) that is an input device that can be manually operated by the operator. Circuit board.

The right hall sensor 46 and the left hall sensor 47 are used to detect that the main body cover 2 of the mower 1 has collided with an object and to detect a state in which the main body cover 2 of the mower 1 is lifted. The left and right Hall sensors may be used as contact sensors and the other Hall sensor may be used as a lift sensor. However, in this embodiment, the lift state and contact state can be accurately adjusted by combining two Hall sensors. It was configured to detect well. The tilt sensor 48 is a sensor that detects how much the mower 1 is tilted with respect to the ground. When the mower 1 tilts more than a predetermined angle, the microcomputer controls the right wheel motor 1.
5a and reverse rotation of the left wheel motor 15b prevents the mower 1 from entering the large inclined surface.

In the above configuration, the mower 1 leaves the charging station 270 according to the operation program and performs mowing work according to the autonomous traveling program. When the contact state as shown in FIGS. 4 to 7 is detected during the mowing operation, the vehicle is turned to change the direction of movement after avoiding the collision state by reversing the rotation of the wheel motors 15a and 15b. Continue mowing work. The mower 1 autonomously returns to the charging station 270 when the requested mowing time ends or when the voltage of the battery pack decreases. Next, a control procedure for detecting the contact state and the lift state during the mowing operation of the mower 1 will be described using the flowchart of FIG. Here, a right hall sensor 46 and a left hall sensor 47 provided in the main body chassis 10.
9 is executed by software by the microcomputer executing a program stored in advance in the control device 50 using the output of FIG.

In FIG. 9, the mower 1 sets the initial detection threshold values of the right hall sensor 46 and the left hall sensor 47 when starting operation (step 61). In the present embodiment, when the mower 1 goes straight forward (forward), or when going straight backward (backward), and when the mower 1 turns right or left. The threshold value in the second state was switched.
The wheel motors (15a, 15b) of the mower 1 are driven by the microcomputer included in the control device 50 controlling the motor drive circuits 27b, 27c. Accordingly, the microcomputer always recognizes whether the traveling state is the forward or rearward straight traveling state (first state) or the turning state (second state). Here, the turning state is realized by driving the right wheel motor 15a and the left wheel motor 15b at different rotational speeds in this embodiment. For example, by rotating the right wheel motor 15a in the normal direction and rotating the left wheel motor 15b in the reverse direction at the same speed, the center position of the right wheel 13a and the left wheel 13b can be quickly turned around the axis. The wheel may be turned by stopping the wheel on one side and rotating the wheel on the other side, or may be turned slowly by rotating the two wheels in the same direction at different rotational speeds.
In any turning state, since the microcomputer controls the rotation of the two wheel motors 15a and 15b, it is possible to identify whether the mower 1 is in a straight traveling state or a turning state.

In step 62, the microcomputer drives the wheel motors 15a and 15b. At this time, the cutting blade motor 30 is driven in the same manner, so that the mowing operation by the cutting blade 35 can be performed. Next, the microcomputer has finished the mowing work in the program operation, whether there has been a stop instruction from the operator by operating the stop button 9, or whether there has been a situation where the mowing work should be terminated for some other reason In the case of termination, the wheel motors 15a and 15b and the blade motor 30 are stopped, and the process is terminated (step 63). If not finished in step 63, the microcomputer detects that the right hall sensor 46 and the left hall sensor 47.
Is detected (step 64), and it is determined whether or not the output exceeds a set threshold value (step 65). Here, when one of the right hall sensor 46 and the left hall sensor 47 exceeds a set threshold value, a recovery operation is performed because a collision state has occurred. When a collision state occurs, after performing a reversing operation to turn the driving direction of the wheel motors 15a and 15b to the opposite side, the operation is continued by turning in another direction and proceeding to step 67 (step 66). Further, when both the right hall sensor 46 and the left hall sensor 47 exceed the set threshold value, a lift state has occurred, so the cutting blade motor 30 is immediately stopped. The stopped blade motor 30 is
It is good to restart when the lift condition disappears.

In step 67, the microcomputer determines whether or not the traveling mode is changed. For example, if the vehicle collides with any object while traveling straight, the vehicle moves backward from steps 65 to 66 and temporarily leaves the obstacle. Then, after performing a turning operation, the wheel motor 15a,
15b is driven. When this turning operation is performed, since the running state is switched from the straight traveling state to the turning state, the threshold value is switched to the threshold value for the changed state, and then the process returns to Step 62 (Steps 67 and 68). If it is determined in step 67 that there is no mode change from the straight traveling state to the turning state or from the turning state to the straight traveling state, the process returns to step 62. In this way, steps 62 to 6 are performed.
By repeating 8, the microcomputer included in the control device 50 performs highly accurate collision detection and lift state detection by setting appropriate threshold values for the right hall sensor 46 and the left hall sensor 47 in accordance with the steering state. be able to.

As described above, in this embodiment, the control device that controls the traveling motor and the working motor switches the threshold for determining contact by the contact detection mechanism during straight traveling and turning, so the traveling motor It is now possible to accurately detect contact according to the control status. Here, the threshold value is changed in two states (operation mode), when going straight, and when turning, but further divided into four states: forward straight, backward straight, right turn, and left turn. Each threshold value may be set separately. Moreover, you may comprise so that a threshold value may be changed according to the travel speed of the mower 1. FIG. For example, an area 8 shown in FIG.
The threshold value for determining 2a and 82b may be changed. Furthermore, the threshold values of the right hall sensor and the left hall sensor may be set to different values in each state.

In this embodiment, in addition to the electrical control of changing the threshold values of the right hall sensor and the left hall sensor, a guide tilt for assisting the movement of the magnets 6 and 7 in a specific direction at the time of collision or lift. The surface may be provided on the main body chassis 10. In this embodiment, a trapezoidal support member 38 is formed on the main body chassis 10 when viewed from the front.
In the event of a collision as shown in FIG. 7, the wall portion of the magnet holder 2c may be brought into contact with the inclined surface of the support member 38 so that the magnet on the side in contact with the wall may move upward. In this way, by providing a guiding inclined surface on the main body chassis side that increases the physical movement distance, detection by the Hall sensor can be facilitated. Further, the offset positions of the two magnets may be arranged so as to be offset not only in the front-rear direction but also in the vertical direction with respect to the hall sensor. As described above, in order to facilitate the detection of the lift state by the right hall sensor and the left hall sensor, the guide inclined surface that guides the magnet holder 2c to move in a specific direction (particularly upward) during turning is provided on the main body chassis. If it is provided at 10, the magnet holder 2c portion can be moved greatly, so that the detection accuracy by the Hall sensor can be improved.

Next, a second embodiment of the present invention will be described with reference to FIG. In the mower 101 of the second embodiment, in addition to the contact detection mechanism using the Hall sensors 46 and 47 and the magnets 6 and 7,
An acceleration sensor 162 is added to the main body cover 2. The acceleration sensor 162 is XYZ
MEMS (Micro Electro Mechani) that measures acceleration in three directions of the axis
This is a known impact sensor using the (cal Systems) technology. The acceleration sensor 162 is mounted on the sensor substrate 161, converts a change in position when acceleration is applied to electrical energy, and outputs the electrical energy to the control device 50 (see FIG. 8). The sensor substrate 161 is provided at a position where the impact of the main body cover 2 is most easily transmitted, for example, an inner wall portion on the upper side of the front opening 5, and is wired from the sensor substrate 161 to the control device 50 by lead wires 163.

According to the verification by the inventors, when the collision state is detected using the acceleration sensor 162, the detection sensitivity is good, and therefore vibrations due to bumps or the like on the road surface during normal traveling are picked up.
Therefore, it is effective to reduce the threshold level for detection and reduce the sensitivity, but in that case, there is a possibility that a collision or the like during turning cannot be detected well. Therefore, in the second embodiment, not only the acceleration sensor 162 but also the detection threshold value of the acceleration sensor 162 can be switched according to the motor control status and the operation mode of the self-propelled working machine. For example, the detection sensitivity of the acceleration sensor 162 is set to be low when moving forward or backward in the straight direction, and is set so as to increase sensitivity when turning, so that a collision during turning is easily detected. Thus, depending on the operation mode of the self-propelled work machine, the detection sensitivity (
The idea of the present invention of switching the threshold value) can be widely applied to self-propelled working machines using various detection sensors. When moving forward or backward in the straight direction, contact detection by the hall sensor and magnet is performed, and control is performed so that contact detection by the acceleration sensor 162 is used in addition to or instead of contact detection by the hall sensor and magnet only during turning. You may do it. Further, the threshold value of the hall sensor and the threshold value of the acceleration sensor 162 may be changed in consideration of the traveling speed.

As mentioned above, although this invention was demonstrated based on the Example, this invention is not limited to the above-mentioned Example, A various change is possible within the range which does not deviate from the meaning. For example, the self-propelled working machine is configured to change the detection threshold according to the difference in operation mode between straight traveling and turning, but the detection threshold is changed during mowing work and when returning to the charging station. It may be.
Further, the detection threshold value may be changed at the time of forward movement and backward movement when traveling straight, or at the time of turning right and turning left during turning. Further, it may be arbitrarily changed according to the work contents by the operation of the keyboard or the like by the operator. Furthermore, the contact detection mechanism used for the self-propelled working machine is not limited to the above, and may be realized using at least two types of sensors having different detection methods such as other contact sensors and vibration sensors. Even in such a case, the detection threshold value may be changed according to the operation mode such as when going straight and turning. In addition, the self-propelled working machine is not limited to a mower, but may be any equipment as long as it is a working equipment that performs a predetermined work using the power of the motor while running on its own, such as a vacuum cleaner or a floor polisher.

DESCRIPTION OF SYMBOLS 1 Mower 2 Body cover 2c Magnet holder 3 Opening / closing cover 3a Hinge 4a, 4c Support member 5 Opening 6, 7 Magnet 9 Stop button 10 Main body chassis 11, 11a, 11b Mounting arm 12 Front wheel 12a Right front wheel 12b Left front wheel 13 Rear wheel 13a right wheel 13b left wheel 15 wheel motor 15a right wheel motor 15b left wheel motor 16a, 16b leaf spring 17a, 17b attachment member 18a, 18b leaf spring 19a, 19b attachment member 20 dial 21 opening / closing sensor 22 container part 23 hinge 24 display 25 Main switch 26 Keyboard 27a to 27c Motor drive circuit 29 Battery terminal 30 Cutting blade motor 34 Motor cylinder portion 35 Cutting blade 35a Disk portion 35b Blade portion 36, 37 Sensor substrate 38 Support member 41 Power receiving terminal 43 Disp Play keyboard substrate 44 First guide wire sensor 45 Second guide wire sensor 46 (Right) Hall sensor 47 (Left) Hall sensor 48 Tilt sensor 49 Stop switch 50 Control device 101 Mower 102 Main body cover 102c Magnet holder 161 Sensor substrate 162 Acceleration sensor 163 Lead wire 200 House 210 Garden 250 Adapter 260 Cable 270 Charging station 280 Guide wire 290 Mowing area 301 Mower

Claims (13)

A traveling motor for driving the wheels; a working motor for driving the work equipment; a secondary battery for supplying power to these motors; a control device for controlling the traveling motor and the working motor; A self-propelled working machine that performs a work while autonomously traveling in a work area.
The said control apparatus has at least two threshold values for determining with a contact from the output detected by the said contact detection mechanism, The self-propelled working machine characterized by the above-mentioned. The self-propelled working machine according to claim 1, wherein the control device changes the threshold value according to a control state of the traveling motor and / or the working motor. The self-propelled working machine according to claim 2, wherein the control device changes the threshold value when the main body goes straight and turns. The traveling motor has two independent motors for driving a right wheel and a left wheel,
The self-propelled working machine according to claim 3, wherein the two motors are rotated synchronously during straight traveling, and the two motors are rotated asynchronously during turning. The said control apparatus is made to drive | work to the direction opposite to the moving direction of the said self-propelled work machine at the time of a collision, when it is judged that the contact has arisen at the time of driving | running | working by the said contact detection mechanism. Self-propelled working machine. A main body chassis that holds the traveling motor and the working motor, and a main body cover that covers them,
The said contact detection mechanism detects the external force added to the said main body cover from the relative movement of the said main body chassis and the said main body cover, The self-propelled of any one of Claim 1 to 5 characterized by the above-mentioned. Type work machine. The body cover is held in a movable state with respect to the body chassis,
A pair of sensors is provided on the main body cover and the main body chassis,
One of the pair of sensors is used to detect the contact to the front side, the other is used to detect the contact to the rear side, and the detection of the lift state is performed using the detection results of both sensors. The self-propelled working machine according to claim 6 characterized by things. The pair of sensors is constituted by a magnetic detection element attached to the main body chassis and a magnet provided on the main body cover,
The self-propelled working machine according to claim 7, wherein the output of the magnetic detection element is transmitted to the control device. Provide at least two types of sensors with different detection methods,
The self-propelled working machine according to claim 8, wherein the control device can make a difference in detection sensitivity with respect to a signal from each sensor. A traveling motor for driving the wheels, a working motor for driving the work equipment, a secondary battery for supplying electric power to these motors, a body chassis for holding the traveling motor and the working motor, and A self-propelled working machine that has a body cover that covers the surroundings and performs work while traveling autonomously in the work area,
The body cover is held in a movable state with respect to the body chassis,
A contact detection mechanism for detecting a movable state of the main body cover with respect to the main body cover;
The threshold for detection in the contact detection mechanism when the self-propelled working machine is moving straight or backward and when the self-propelling working machine is turning is switched. Self-propelled work machine. The contact detection mechanism is a magnet provided on one of the main body chassis or the main body cover, and a magnetic detection element provided on the other and close to the magnet,
The control device for driving the traveling motor and the working motor is configured to compare a change in voltage that the magnetic detection element changes with the approach or separation of the magnet with the threshold value, so that The self-propelled working machine according to claim 10, wherein presence or absence of contact is detected. 12. The detection sensitivity of the magnetic detection element when the vehicle travels straight forward or backward by the traveling motor is set lower than the detection sensitivity of the magnetic detection element during turning.
The self-propelled work machine described in 1. Two sets of the magnet and the magnetic detection element are provided so as to face in the left-right direction at the left-right position of the main body chassis,
The self-propelled type according to claim 12, wherein the magnet on one side is offset from the front side of the magnetic detection element, and the magnet on the other side is offset from the rear side of the magnetic detection element. Work machine.

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