JP7083445B2 - Autonomous driving system - Google Patents

Description

The present invention relates to an autonomous traveling system.

Conventionally, there has been known an autonomous traveling system that acquires position information of a work vehicle based on radio waves received from a GNSS satellite and autonomously travels the work vehicle along a preset route. Patent Document 1 discloses this kind of autonomous traveling system (travel control system). The autonomous traveling system described in Patent Document 1 autonomously travels by arranging a work vehicle to be autonomously traveled with respect to a preset start position of a route in a state in which the forward direction thereof is directed to a predetermined direction. Can be started. In order to realize such autonomous travel, it is considered necessary that the orientation of the work vehicle is grasped by the autonomous travel control device for autonomously traveling the work vehicle.

As one of the methods for acquiring the orientation of the work vehicle, it is conceivable to provide the work vehicle with a known inertial measurement unit including three gyro sensors (angular velocity sensors) and three acceleration sensors. In this inertial measurement unit, the angular velocity of rotation about each of the three axes orthogonal to each other can be detected by the gyro sensor, and the acceleration in the direction along the three axes can be detected by the acceleration sensor. The inertial measurement unit is attached so that the above three axes are parallel to the pitch axis, roll axis, and yaw axis of the vehicle. With this configuration, by integrating the angular velocities obtained from a certain point in time to the present, it is possible to obtain the amount of change in the direction of the current work vehicle with respect to the point in time.

When the autonomous driving control device performs autonomous driving, the position of the work vehicle is basically obtained from the position information obtained by GNSS positioning, but the positioning may be performed well depending on the reception status of GNSS radio waves and the like. It may not be possible. However, if the above-mentioned inertial measurement unit is provided in the work vehicle, the position of the work vehicle can be obtained by inertial navigation using the detection result of the inertial measurement unit even when GNSS positioning cannot be performed.

By the way, the gyro sensor of the inertial measurement unit can detect the change in the direction of the work vehicle, but cannot detect the direction itself. Therefore, it is necessary for the inertial measurement unit to know the posture of the vehicle at a certain point in time, specifically, the pitch angle, the roll angle, and the yaw angle. In the following, the process of obtaining at least the yaw angle among the above three angles may be referred to as an initialization process.

As mentioned above, the inertial measurement unit is equipped with an acceleration sensor. Therefore, by utilizing the fact that the gravitational acceleration always faces the center of the earth, for example, the pitch angle and the roll angle of the vehicle can be obtained by obtaining the direction of the gravitational acceleration using an acceleration sensor while the vehicle is stationary. can. On the other hand, the yaw angle of the vehicle cannot be obtained by the sensor provided in the inertial measurement unit in principle.

A technique for finding the yaw angle by detecting the rotation of the earth with a gyro sensor has also been put into practical use (gyro compass), but this method requires a high-precision gyro sensor, so the cost of the inertial measurement unit is high. It will increase. Further, it is conceivable to provide the directional sensor in the work vehicle as in Patent Document 1, but this also causes an increase in cost.

Therefore, taking advantage of the fact that the work vehicle is equipped with a configuration that can receive radio waves from the GNSS satellite, the user is manually driven to move the work vehicle forward, and the change in the position of the vehicle with respect to the earth at this time is the radio wave of the GNSS satellite. It is conceivable to detect based on the above, and to obtain the yaw angle of the vehicle by regarding the direction in which this position is changed as the direction of the vehicle.

International Publication No. 2015/119265

However, in the above configuration, when the user actually moves the work vehicle for the initialization process, due to various circumstances such as an obstacle in front of the user, the user must temporarily move backward instead of moving forward. It may be necessary. In this case, there is a risk of erroneous initialization in which the orientation of the work vehicle is grasped in a direction that is 180 ° different from the actual orientation, and there is room for improvement in that it causes unintended control. rice field.

The present invention has been made in view of the above circumstances, and an object of the present invention is the orientation of the work vehicle when performing predetermined processing of the inertial measurement unit while intentionally changing the position of the work vehicle in the autonomous traveling system. The purpose is to prevent false detections.

Means and effects to solve problems

The problem to be solved by the present invention is as described above, and next, the means for solving this problem and its effect will be described.

According to the first aspect of the present invention, an autonomous traveling system having the following configuration is provided. That is, this autonomous travel system includes a position information acquisition unit, an autonomous travel control unit, a forward / backward movement detection unit, and an inertial measurement unit. The position information acquisition unit acquires the position information of the work vehicle based on the radio waves received from the satellite. The autonomous travel control unit can autonomously drive the work vehicle along a preset route based on the position information. The forward / backward detection unit can detect the forward movement or reverse movement of the work vehicle. The inertial measurement unit detects the angular velocity and acceleration of the work vehicle. Each time the work vehicle is started, the inertial measurement unit executes an initialization process for the direction of the work vehicle based on the position information when the forward / backward movement detection unit detects the forward movement.

As a result, the reliability of the detection result by the inertial measurement unit can be improved.

According to the second aspect of the present invention, an autonomous traveling system having the following configuration is provided. That is, this autonomous travel system includes a position information acquisition unit, an autonomous travel control unit, a forward / backward movement detection unit, and an inertial measurement unit. The position information acquisition unit acquires the position information of the work vehicle based on the radio waves received from the satellite. The autonomous travel control unit can autonomously drive the work vehicle along a preset route based on the position information. The forward / backward detection unit can detect the forward movement or reverse movement of the work vehicle. The inertial measurement unit detects the angular velocity and acceleration of the work vehicle. When the forward / backward movement detection unit detects the reverse movement each time the work vehicle is started, the inertial measurement unit reverses the direction of the position information and regards the work vehicle as a forward movement state. It is possible to execute the conversion process.

As a result, the initialization process can be performed even when the work vehicle is moved backward. Therefore, the convenience of the user can be improved.

The side view which shows the overall structure of the robot tractor provided in the autonomous traveling system which concerns on one Embodiment of this invention. Top view of the robot tractor. A block diagram showing the main electrical configurations of a robot tractor. In the first embodiment, the flowchart explaining the determination and processing performed in the initialization process of the inertial measurement unit. In the second embodiment, the flowchart explaining the determination and processing performed in the initialization process of the inertial measurement unit.

Next, an embodiment of the present invention will be described with reference to the drawings. In the following, the same members may be designated by the same reference numerals in each of the drawings, and duplicate description may be omitted. In addition, the names of members and the like corresponding to the same reference numerals may be simply paraphrased, or may be paraphrased by the names of higher-level concepts or lower-level concepts.

In the present invention, for example, as shown in the following embodiment, when one or a plurality of work vehicles are run in a predetermined field to perform all or part of the farm work in the field, the work is performed. It is applied to an autonomous driving system that drives a vehicle autonomously. In the present embodiment, a tractor will be described as an example of a work vehicle, but the work vehicle includes a tractor, a rice transplanter, a combine, a civil engineering / construction work device, a snowplow, and other passenger-type work machines, as well as a walking type work. Machines are also included. In the present specification, the autonomous traveling means that the configuration related to the traveling provided by the tractor is controlled by the control unit (ECU) provided in the tractor, and the tractor travels along a predetermined route, and the autonomous work means the tractor. It means that the configuration related to the work provided by the tractor is controlled by the control unit provided with the tractor, and the tractor performs the work along a predetermined route. On the other hand, the manual running / manual work means that each configuration of the tractor is operated by the user to perform the running / work.

In the following description, a tractor that is autonomously driven or operated autonomously may be referred to as an "unmanned tractor" or a "robot tractor", and a tractor that is manually driven or manually operated is referred to as a "manned tractor". Sometimes. If part of the farm work is carried out by an unmanned tractor in the field, the rest of the farm work is carried out by a manned tractor. Performing farm work in a single field with unmanned tractors and manned tractors may be referred to as cooperative work, follow-up work, accompanying work, etc. of farm work. In the present specification, the difference between the unmanned tractor and the manned tractor is the presence or absence of operation by the user, and each configuration is basically common. That is, even if it is an unmanned tractor, the user can board (board) and operate it (that is, it can be used as a manned tractor), or even if it is a manned tractor, the user gets off and runs autonomously. -It is possible to work autonomously (that is, it can be used as an unmanned tractor). In addition, as cooperative work of farm work, in addition to "performing farm work in a single field with automatic guided vehicles and manned vehicles", "unmanned vehicles and manned vehicles perform farm work in different fields such as adjacent fields at the same time. "To do" may be included.

<First Embodiment>
Next, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing an overall configuration of a robot tractor 1 provided in an autonomous traveling system 100 according to an embodiment of the present invention. FIG. 2 is a plan view of the robot tractor 1. FIG. 3 is a block diagram showing a main electrical configuration of the robot tractor 1.

The robot tractor 1 of the present embodiment is configured to perform autonomous work while autonomously traveling along an autonomous traveling route (route) generated in the autonomous traveling system 100.

The robot tractor 1 is operated by performing wireless communication with the wireless communication terminal 46 via a short-range wireless network. The user operates the touch panel 39 of the wireless communication terminal 46 to appropriately exchange signals with the control unit (autonomous travel control unit) 4 of the tractor 1 to cause the tractor 1 to autonomously travel and perform autonomous work. Can be done.

The tractor 1 includes a traveling machine body 2 capable of autonomously traveling in a field. The working machine 3 shown in FIGS. 1 and 2 is detachably attached to the traveling machine body 2. As the working machine 3, for example, there are various working machines such as a tiller, a plow, a fertilizer application machine, a grass mower, a sowing machine, etc., and a desired working machine 3 is selected from these as necessary and a traveling machine. Can be attached to 2. The traveling machine body 2 is configured so that the height and posture of the mounted working machine 3 can be changed.

The configuration of the tractor 1 will be described in more detail with reference to FIGS. 1 and 2. As shown in FIG. 1, the traveling machine body 2 of the tractor 1 is supported by a pair of left and right front wheels 7 and 7 and a rear portion supported by a pair of left and right rear wheels 8 and 8.

A bonnet 9 is arranged at the front portion of the traveling machine body 2. The engine 10 and the like, which are the drive sources of the tractor 1, are housed in the bonnet 9. The engine 10 can be configured by, for example, a diesel engine, but is not limited to this, and may be configured by, for example, a gasoline engine. Further, as the drive source, an electric motor may be used in addition to or instead of the engine 10.

Behind the bonnet 9, a cabin 11 for a user to board is arranged. Inside the cabin 11, a steering handle 12 for the user to steer, a seat 13 for the user to sit on, and various operating devices for performing various operations are mainly provided. However, the work vehicle is not limited to the one with the cabin 11, and may be the one without the cabin 11.

Examples of the operation device include the monitor device 14, the throttle lever 15, the main shift lever 27, a plurality of hydraulic operation levers 16, the PTO switch 17, the PTO shift lever 18, the auxiliary shift lever 19, and the work equipment elevating switch shown in FIG. 28 etc. can be mentioned as an example. These operating devices are arranged in the vicinity of the function of the seat 13 or the steering wheel 12.

The monitoring device 14 is configured to be able to display various information of the tractor 1. The throttle lever 15 is an operating tool for setting the output rotation speed of the engine 10. The main shift lever 27 is an operating tool for steplessly changing the traveling of the tractor 1. The PTO switch 17 is an operating tool for switching between transmission / disconnection of power to the PTO shaft (power take-off shaft) of the figure shown protruding from the rear end of the transmission 22. That is, when the PTO switch 17 is in the ON state, power is transmitted to the PTO shaft to rotate the PTO shaft, and the work equipment 3 is driven, while when the PTO switch 17 is in the OFF state, the power to the PTO shaft is cut off. Then, the PTO shaft does not rotate and the working machine 3 is stopped. The PTO shift lever 18 is for changing the power input to the working machine 3, and specifically, is an operating tool for changing the rotational speed of the PTO shaft. The auxiliary transmission lever 19 is an operating tool for switching the gear ratio of the traveling auxiliary transmission gear mechanism in the transmission 22. The work machine elevating switch 28 is an operating tool for raising and lowering the height of the work machine 3 mounted on the traveling machine body 2 within a predetermined range.

As shown in FIG. 1, a chassis 20 of the tractor 1 is provided at the lower part of the traveling machine body 2. The chassis 20 is composed of an airframe frame 21, a transmission 22, a front axle 23, a rear axle 24, and the like.

The airframe frame 21 is a support member in the front portion of the tractor 1 and supports the engine 10 directly or via an anti-vibration member or the like. The transmission 22 changes the power from the engine 10 and transmits it to the front axle 23 and the rear axle 24. The front axle 23 is configured to transmit the power input from the transmission 22 to the front wheels 7. The rear axle 24 is configured to transmit the power input from the transmission 22 to the rear wheels 8.

As shown in FIG. 3, the tractor 1 includes a control unit 4 for controlling the operation of the traveling machine 2 (forward, reverse, stop, turn, etc.) and the operation of the work machine 3 (elevation, drive, stop, etc.). .. The control unit 4 includes a CPU, ROM, RAM, I / O, etc. (not shown), and the CPU can read various programs and the like from the ROM and execute them. The control unit 4 includes a controller for controlling each configuration (for example, engine 10 and the like) included in the tractor 1, a wireless communication device for wireless communication with other wireless communication devices, and the like according to a standard such as CAN. It is electrically connected.

As the above controller, the tractor 1 includes at least an engine controller 41, a vehicle speed controller 42, a steering controller 43, and an elevating controller 44. Each controller can control each configuration of the tractor 1 according to an electric signal from the control unit 4.

The engine controller 41 controls the rotation speed of the engine 10 and the like. The engine controller 41 is electrically connected to a common rail device (not shown) as a fuel injection device provided in the engine 10. The common rail device injects fuel into each cylinder of the engine 10. In this case, by controlling the opening and closing of the fuel injection valve of the injector for each cylinder of the engine 10, high-pressure fuel pumped from the fuel tank to the common rail device by the fuel supply pump is injected from each injector to each cylinder of the engine 10. , The injection pressure, injection timing, and injection period (injection amount) of the fuel supplied from each injector are controlled with high accuracy. By controlling the common rail device, the engine controller 41 can, for example, stop the supply of fuel to the engine 10 and stop the driving of the engine 10.

The vehicle speed controller 42 controls the vehicle speed of the tractor 1. Specifically, the transmission 22 is provided with, for example, a movable diagonal plate type hydraulic continuously variable transmission (not shown). The vehicle speed controller 42 can change the gear ratio of the transmission 22 and realize a desired vehicle speed by changing the angle of the swash plate of the hydraulic continuously variable transmission by an actuator.

The steering controller (traveling device) 43 controls the rotation angle of the steering handle 12. Specifically, a steering actuator is provided in the middle of the rotation angle (steering shaft) of the steering handle 12. In this configuration, when the tractor 1 travels on a predetermined route (as an unmanned tractor), the controller 4 calculates an appropriate rotation angle of the steering handle 12 so that the tractor 1 travels along the route. Then, a control signal is output to the steering controller 43 so that the rotation angle is obtained. The steering controller 43 drives the steering actuator based on the control signal input from the control unit 4, and controls the rotation angle (steering angle) of the steering handle 12. The steering controller 43 may not adjust the rotation angle of the steering handle 12, but may directly adjust the steering angle of the front wheels 7 of the tractor 1. In that case, it is assumed that the steering wheel has been turned. However, the steering handle 12 does not rotate.

The elevating controller 44 controls the elevating and lowering of the working machine 3. Specifically, the tractor 1 is provided with an elevating actuator (not shown) including a hydraulic cylinder or the like in the vicinity of a three-point link mechanism connecting the working machine 3 to the traveling machine body 2. In this configuration, the elevating controller 44 drives the elevating actuator based on the control signal input from the control unit 4 to appropriately raise and lower the working machine 3, so that the working machine 3 can perform agricultural work at a desired height. Can be done. By this control, the working machine 3 can be supported at a desired height such as a retracted height (height at which farm work is not performed) and a working height (height at which farm work is performed).

Since the plurality of controllers 41, 42, 43, 44 described above control each part such as the engine 10 based on the signal input from the control unit 4, the control unit 4 substantially grasps each part. You can know that you are doing it.

The tractor 1 provided with the control unit 4 as described above controls each part of the tractor 1 (traveling machine 2, working machine 3, etc.) by the control unit 4 when the user gets on the cabin 11 and performs various operations. Therefore, it is configured so that farm work can be performed while traveling in the field. In addition, the tractor 1 of the present embodiment can perform autonomous traveling and autonomous work based on a predetermined control signal output from the wireless communication terminal 46 without the user getting on the tractor 1. There is.

Specifically, as shown in FIG. 3 and the like, the tractor 1 has various configurations for enabling autonomous traveling and autonomous work. For example, the tractor 1 obtains a positioning antenna 6 or the like necessary for momentarily acquiring position information of itself (traveling aircraft 2) based on radio waves received from satellites (positioning satellites) 105, 105, .... Be prepared. With such a configuration, the tractor 1 can acquire its own position information based on the radio waves received from the satellites 105, 105, ..., And autonomously travel on the preset route of the field. It has become.

Next, the configuration included in the tractor 1 to enable autonomous traveling will be described in more detail. Specifically, as shown in FIG. 3, the tractor 1 of the present embodiment has a positioning antenna 6, a position information acquisition unit 52, a wireless communication antenna 48, a short-range wireless communication device 51, a camera 56, and an inertial measurement unit. It includes a device 54, a storage unit 55, and the like.

The positioning antenna 6 receives radio waves from satellites 105, 105, ... That constitute a satellite positioning system (GNSS). In this embodiment, the Global Positioning System (GPS) is used as the GNSS. As shown in FIG. 1, the positioning antenna 6 is attached to the upper surface of the roof 26 of the cabin 11 of the tractor 1.

The position information acquisition unit 52 acquires position information (latitude / longitude information) by using a known GNSS-RTK method based on the input positioning signal. Since the GNSS-RTK method is well known, detailed description thereof will be omitted, but the position information acquisition unit 52 acquires position information by positioning itself and positions acquired (calculated) by a reference station whose position is known. The correction information is received moment by moment by wireless communication, and the position information is corrected based on this positioning correction information. Further, in the position information acquisition unit 52 and the reference station, not only the measurement based on the data (navigation message) received by the GNSS radio wave but also the measurement based on the phase detection of the GNSS radio wave (carrier wave) as a wave is performed. As a result, the position information of the traveling machine 2 can be acquired with an accuracy considerably higher than that of the normal GNSS positioning, specifically, with an accuracy of about several centimeters. The position information acquired by the position information acquisition unit 52 is stored in the storage unit 55, is read out from the storage unit 55 in a timely manner, is input to the control unit 4, and is used for autonomous traveling.

The wireless communication antenna 48 is an antenna corresponding to the standard of the short-range wireless network used for communication with the wireless communication terminal 46 used by the user. The wireless communication antenna 48 is arranged on the upper surface of the roof 26 included in the cabin 11 of the tractor 1. The signal from the wireless communication terminal 46 received by the wireless communication antenna 48 is signal-processed by the short-range wireless communication device 51 and then input to the control unit 4. Further, the signal transmitted from the control unit 4 or the like to the wireless communication terminal 46 is signal-processed by the short-range wireless communication device 51, then transmitted from the wireless communication antenna 48 and received by the wireless communication terminal 46.

The short-range wireless communication device 51 demodulates and extracts the signal from the wireless communication terminal 46 received by the wireless communication antenna 48, and inputs the signal to the control unit 4. As a result, an instruction or the like issued by the user using the wireless communication terminal 46 is input to the control unit 4, and is used to control each unit of the tractor 1.

The camera 56 captures the environment around the tractor 1. Although not shown in FIGS. 1 and 2, the camera 56 is attached to the roof 26 of the tractor 1. The video data captured by the camera 56 is modulated by the short-range wireless communication device 51, transmitted from the wireless communication antenna 48, and received by the wireless communication terminal 46. Based on the received video data, the display control unit 31 of the wireless communication terminal 46 generates display data, and based on the display data, the video captured by the camera 56 is displayed on the display 37.

The storage unit 55 stores a predetermined route (traveling route) for autonomously traveling the tractor 1, and positions information (position information, speed vector information, etc.) of the tractor 1 (strictly speaking, the positioning antenna 6). ) Is a memory.

The inertial measurement unit 54 is a sensor unit capable of specifying the posture, acceleration, and the like of the traveling machine body 2 of the tractor 1. Specifically, the inertial measurement unit 54 includes a sensor group in which an angular velocity sensor and an acceleration sensor are attached to each of the first axis, the second axis, and the third axis orthogonal to each other.

More specifically, the inertial measurement device 54 includes a first acceleration sensor that detects acceleration in the first axis direction, a second acceleration sensor that detects acceleration in the second axis direction, and a second acceleration sensor that detects acceleration in the third axis direction. Three acceleration sensors, a first angular velocity sensor that detects the angular velocity around the first axis, a second angular velocity sensor that detects the angular velocity around the second axis, and a third angular velocity sensor that detects the angular velocity around the third axis. And.

In the inertial measurement unit 54, the traveling of the tractor 1 is such that the first angular velocity sensor can detect the roll angular velocity of the tractor 1, the second angular velocity sensor can detect the pitch angular velocity of the tractor 1, and the third angular velocity sensor can detect the yaw angular velocity of the tractor 1. The direction is determined with respect to the machine body 2, and the traveling machine body 2 is attached at the position of the center of gravity. In other words, the first axis is arranged so as to coincide with the front-rear direction of the traveling machine body 2, that is, to be a roll rotation axis. The second axis is arranged so as to coincide with the left-right direction of the traveling machine body 2, that is, to be a pitch rotation axis. The third axis is arranged so as to coincide with the vertical direction of the traveling machine body 2, that is, to be a yaw rotation axis.

Based on the detection result of the inertial measurement unit 54 having such a configuration, the angular velocity (roll angular velocity, pitch angular velocity, and yaw angular velocity) of the attitude change of the traveling machine body 2 of the tractor 1 and the acceleration in the front-rear direction, the left-right direction, and the up-down direction. Can be identified. Then, the result of integrating the obtained angular velocities is used to acquire the posture of the traveling machine body 2. Information regarding the posture of the traveling machine body 2 is input to the control unit 4, and is used to correct the position information acquired by the position information acquisition unit 52, or is used for other control.

Further, by performing a known inertial navigation calculation using the information on the attitude change and acceleration of the traveling aircraft 2 acquired by the inertial measurement unit 54, the radio waves from the satellites 105, 105, ... Are temporarily interrupted, etc. When the position information cannot be calculated, the position of the tractor 1 in the meantime can be obtained.

In order for the tractor 1 having such a configuration to appropriately perform autonomous traveling, it is not enough that the position information of the tractor 1 is accurately grasped by the control unit 4, and the orientation of the tractor 1 (traveling machine 2) is not sufficient. It is necessary that it is accurately grasped by the control unit 4. In this respect, the angular velocity sensor of the inertial measurement unit 54 can detect the change in the orientation of the tractor 1, but cannot detect the orientation of the tractor 1 itself.

Here, as described above, the roll angle and pitch angle of the traveling machine body 2 can be obtained by detecting the direction of the gravitational acceleration acting while the tractor 1 is stopped (stationary) with three acceleration sensors. , The yaw angle cannot be obtained by using the gravitational acceleration as a clue. It is conceivable to equip the tractor 1 with a known compass such as an electronic compass or a mechanical gimbal type compass in order to obtain the yaw angle, but this causes an increase in cost.

Therefore, in the present embodiment, the tractor 1 is actually advanced by the manual operation of the user, the position change of the tractor 1 at this time is obtained by using the GNSS radio wave, and the yaw angle is obtained based on the direction of the position change. It is supposed to be. The details of this predetermined process (hereinafter, may be referred to as an initialization process) will be described later.

If the initial values of the posture (roll angle, pitch angle and yaw angle) of the tractor 1 are given in this way, the initial values will be used as long as the subsequent change in the orientation of the tractor 1 is continuously detected by the angular velocity sensor. On the other hand, by adding the integration result of the detection value of the angular velocity sensor, the current posture of the tractor 1 can be obtained in real time. Then, even when GNSS positioning is not possible, the position of the tractor 1 can be estimated by the known inertial navigation based on the attitude of the tractor 1 and the detection result of the acceleration sensor.

Hereinafter, the configuration provided in the autonomous traveling system 100 in order to perform various determinations associated with the initialization process of the inertial measurement unit 54 will be described in detail with reference to FIG. Specifically, the autonomous traveling system 100 of the present embodiment includes a forward / backward detection unit 53, a steering angle detection unit (turning detection unit) 57, a vibration detection unit 58, and a vehicle speed detection unit 59.

By detecting the rotation of the front wheel 7, the forward / backward detection unit 53 detects that the tractor 1 is moving forward, backward, and in a neutral state (neither forward nor backward). ) Can be detected. The detection result of the forward / backward detection unit 53 is input to the control unit 4.

The steering angle detecting unit 57 detects the steering angle of the steering wheel 12. As the steering angle detection unit 57, various known sensors can be adopted, and for example, a rotary potentiometer can be used. The detection result of the steering angle detection unit 57 is input to the control unit 4.

The vibration detection unit 58 detects the vibration of the traveling machine body 2 of the tractor 1. Specifically, the vibration detection unit 58 of the present embodiment reads the detection values of the three acceleration sensors of the inertial measurement unit 54 from the storage unit 55 and comprehensively evaluates them to detect the vibration of the traveling machine body 2. do. The detection result of the vibration detection unit 58 is input to the control unit 4.

The vehicle speed detecting unit (vehicle speed specifying unit) 59 detects the vehicle speed (traveling speed) of the tractor 1. There are various methods for detecting the vehicle speed. For example, a rotation sensor (not shown) is provided so as to face the outer periphery of a gear (not shown) arranged inside the transmission 22, and the rotation sensor detects and outputs the gear teeth. It is conceivable to count the pulse signals to be generated. The vehicle speed information acquired by the vehicle speed detection unit 59 is input to the control unit 4.

Hereinafter, the initialization process of the inertial measurement unit 54 performed in the autonomous traveling system 100 of the present embodiment will be described in detail with reference to FIG. FIG. 4 is a flowchart illustrating a determination and processing performed in the initialization processing of the inertial measurement unit 54 of the present embodiment. The series of determinations and processes shown in FIG. 4 is performed with the tractor 1 being activated (specifically, the engine switch (not shown) being turned on). In other words, the series of determinations and processes shown in FIG. 4 are performed each time the tractor 1 is activated. As a result, for example, even if the orientation of the tractor 1 changes due to transportation or the like without power supply to the inertial measurement unit 54, the inertial measurement unit 54 can be appropriately initialized with respect to the changed orientation of the tractor 1. Can be done.

When the tractor 1 is activated, the control unit 4 causes the monitoring device 14 included in the tractor 1 to display the message "Please advance the tractor as straight as possible for initialization". The user who sees this operates the throttle lever 15, the main shift lever 27, and the like to move the tractor 1 forward.

First, the control unit 4 acquires the detection result of the forward / backward movement detection unit 53 and determines whether or not the advance of the traveling machine body 2 is detected (step S101).

As a result of the determination in step S101, when the forward / backward movement detection unit 53 does not detect the advance of the traveling aircraft 2 (steps S101, No), the control unit 4 makes the determination until the advance of the traveling aircraft 2 is detected. Repeat and wait.

As a result of the determination in step S101, when the forward / backward movement detection unit 53 detects the forward movement of the traveling aircraft 2 (steps S101, Yes), the control unit 4 subsequently acquires the detection result of the vehicle speed detection unit 59. It is determined whether or not the vehicle speed of the traveling machine body 2 exceeds the threshold value (step S102).

As a result of the determination in step S102, when the vehicle speed detected by the vehicle speed detection unit 59 is equal to or less than the threshold value (step S102, No), the influence of the error described later on the direction of the detected vehicle speed becomes relatively large, so that the vehicle travels. It is considered that the orientation of the aircraft 2 cannot be obtained accurately. In this case, the control unit 4 returns to step S101 and repeats the above determination.

As a result of the determination in step S102, when the vehicle speed detected by the vibration detection unit 58 exceeds the threshold value (step S102, Yes), the control unit 4 subsequently acquires the detection result of the vibration detection unit 58, and the traveling machine body 2 It is determined whether or not the magnitude of the vibration of the above is less than the threshold value (step S103).

As a result of the determination in step S103, when the magnitude of the vibration detected by the vibration detection unit 58 is equal to or greater than the threshold value (step S103, No), the behavior of the traveling machine 2 is unstable, so that the traveling machine 2 has an unstable behavior. It may not be possible to obtain the correct orientation. In this case, the control unit 4 returns to step S101 and repeats the above determination.

As a result of the determination in step S103, when the magnitude of the vibration detected by the vibration detection unit 58 is less than the threshold value (step S103, Yes), the control unit 4 subsequently acquires the detection result of the steering angle detection unit 57. Then, it is determined whether or not the steering angle of the steering handle 12 is less than the threshold value (step S104).

As a result of the determination in step S104, when the steering angle detected by the steering angle detection unit 57 is equal to or greater than the threshold value (step S104, No), the direction of the traveling aircraft 2 is suddenly changed, so that the traveling aircraft is concerned. It may not be possible to obtain the exact orientation of 2. In this case, the control unit 4 returns to step S101 and repeats the above determination.

As a result of the determination in step S104, when the magnitude of the steering angle detected by the steering angle detection unit 57 is less than the threshold value (step S104, Yes), it is said that the conditions for accurately detecting the direction of the traveling machine body 2 are satisfied. be able to. Therefore, the control unit 4 performs an initialization process (step S105).

To specifically explain the process of step S105, the control unit 4 obtains the satellites 105, 105, ... From the satellite orbit information of the navigation message carried on the GNSS radio waves received from the satellites 105, 105, ... The speed of the traveling aircraft 2 based on the speed of the traveling aircraft 2 and the relative speed of the traveling aircraft 2 with respect to the satellites 105, 105, ... Calculate the vector.

When GPS is used as GNSS, there are a plurality of types of GPS carrier waves. For example, when measuring a carrier wave (1575.42 MHz) called L1, the wavelength is about 19 cm. Therefore, by measuring the wave nature (Doppler effect) of the carrier wave as described above, the change in the distance between the satellites 105, 105, ... And the traveling aircraft 2 can be measured with an error of several centimeters per second. It can be measured with high accuracy. Therefore, if the traveling machine 2 is driven at a vehicle speed higher than a certain level (step S102), the speed vector can be obtained with sufficiently high accuracy.

Here, as described above, the user should originally move the tractor 1 forward according to the display of the monitoring device 14, but there may be a case where the tractor 1 is moved backward due to circumstances such as avoidance of obstacles. However, in the present embodiment, since the control unit 4 controls so that the initialization process is not performed when the reverse movement is detected (step S101), the direction of the speed vector and the direction of the traveling machine 2 are opposite to each other. No initialization is done. Therefore, the reliability of the detection result of the inertial measurement unit 54 can be improved.

The obtained velocity vector can be represented by a northward velocity component, an eastward velocity component, and a downward velocity component. By calculating the inverse tangent for the ratio of the velocity component in the east direction to the velocity component in the north direction, the yaw angle (initial yaw angle) for initializing the inertial measurement unit 54 can be calculated.

As described above, in the present embodiment, the yaw angle for initializing the inertial measurement unit 54 can be obtained with high accuracy by utilizing the Doppler effect of the GPS radio wave. Therefore, it is expected that the attitude of the traveling aircraft 2 output by the inertial measurement unit 54 will be highly accurate based on this, and the position can be specified by inertial navigation when GNSS-RTK positioning becomes impossible. It can be performed with an accuracy that can replace RTK positioning.

As described above, the autonomous traveling system 100 of the present embodiment includes a position information acquisition unit 52, a control unit 4, a forward / backward detection unit 53, and an inertial measurement unit 54. The position information acquisition unit 52 acquires the position information of the tractor 1 based on the radio waves received from the satellites 105, 105, .... The control unit 4 can autonomously drive the tractor 1 along a preset route based on the position information. The forward / backward detection unit 53 can detect the forward movement or the reverse movement of the tractor 1. The inertial measurement unit 54 detects the angular velocity and acceleration of the tractor 1. The inertial measurement unit 54 executes the initialization process while moving the tractor 1, so that the direction of the tractor 1 at the time of executing the initialization process is set to the radio wave received from the satellites 105, 105, ... It is possible to obtain it based on the direction of the position change of the tractor 1 obtained based on the above. The inertial measurement unit 54 executes the initialization process when the forward / backward detection unit 53 detects forward movement, but does not execute the initialization process when the forward / backward movement detection unit 53 detects forward movement.

As a result, since the inertial measurement unit 54 does not execute the initialization process when the tractor 1 is moving backward, it is possible to prevent an erroneous initialization process in which the orientation of the tractor 1 is grasped 180 ° different from the actual orientation. .. As a result, the reliability of the detection result by the inertial measurement unit 54 can be improved.

Further, the autonomous traveling system 100 of the present embodiment includes a steering angle detecting unit 57 that detects the degree of turning of the tractor 1. The inertial measurement unit 54 does not execute the initialization process when the degree of turning (specifically, the steering angle) detected by the steering angle detecting unit 57 exceeds the threshold value.

As a result, for example, when a turn is performed to avoid an obstacle and the direction of the tractor 1 changes suddenly and it is difficult to obtain the direction of the tractor 1 accurately, the inertial measurement unit 54 performs the initialization process. It can be prevented. Therefore, it is possible to prevent the initialization process based on the inaccurate orientation of the work vehicle.

Further, the autonomous traveling system 100 of the present embodiment includes a vibration detection unit 58 that detects the vibration of the tractor 1. The inertial measurement unit 54 does not execute the initialization process when the vibration detected by the vibration detection unit 58 exceeds the threshold value.

As a result, it is possible to prevent the inertial measurement unit 54 from performing the initialization process when the vibration generated in the tractor 1 is large and it is difficult to accurately obtain the direction of the tractor 1.

Further, the autonomous traveling system 100 of the present embodiment includes a vehicle speed detecting unit (vehicle speed specifying unit) 59 that specifies the vehicle speed of the tractor 1. The inertial measurement unit 54 does not execute the initialization process when the vehicle speed specified by the vehicle speed detection unit 59 is less than the threshold value.

This makes it possible to prevent the inertial measurement unit 54 from performing the initialization process when the vehicle speed is slow and it is difficult to accurately obtain the direction of the position change of the tractor 1.

<Second Embodiment>
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a flowchart illustrating a determination and processing performed in the initialization processing of the inertial measurement unit 54 in the second embodiment. In the description of the present embodiment, the same reference numerals may be given to the drawings for the same or similar members as those in the above-described embodiment, and the description may be omitted.

In the autonomous traveling system 100 according to the second embodiment, the first aspect is that the initialization process can be performed not only when the user moves the traveling machine 2 forward but also when the user moves it backward. It is different from the autonomous traveling system 100 according to the embodiment.

The series of determinations and processes shown in FIG. 5 are performed each time the tractor 1 is activated, as in the first embodiment.

First, the control unit 4 performs the processes from step S201 to step S203 in order to determine whether or not the condition for starting the initialization process is satisfied. Since step S201 is the same as the above step S102, step S202 is the same as the above step S103, and step S203 is the same as the above step S104, the description thereof will be omitted.

In step S204, the control unit 4 calculates the speed vector of the traveling machine body 2 by using the frequency change of the carrier wave due to the Doppler effect of the GNSS radio wave, as described in the first embodiment (step S105).

Next, the control unit 4 acquires the detection result of the forward / backward movement detection unit 53 and determines whether or not the advance of the traveling machine body 2 is detected (step S205).

As a result of the determination in step S205, when the reverse movement of the traveling aircraft 2 is detected by the forward / backward movement detecting unit 53 (steps S205, No), the change in the position of the traveling aircraft 2 that has occurred in step S204 is backward. Become. Therefore, the control unit 4 reverses the direction of the velocity vector obtained in step S204 (step S206). On the other hand, when the forward / backward movement detection unit 53 has detected the forward movement of the traveling machine body 2 (steps S205, Yes), the process of the above step S206 is skipped. After that, the control unit 4 obtains the yaw angle based on the velocity vector (step S207).

In the present embodiment, the initialization process can be appropriately performed not only when the user moves the traveling machine 2 forward but also when the traveling machine 2 is moved backward. Therefore, the initialization process of the inertial measurement unit 54 can be flexibly performed according to the state of the field and the like, and the convenience of the user can be improved.

As described above, the autonomous traveling system 100 of the present embodiment includes a position information acquisition unit 52, a control unit 4, a forward / backward detection unit 53, and an inertial measurement unit 54. The position information acquisition unit 52 acquires the position information of the tractor 1 based on the radio waves received from the satellites 105, 105, .... The control unit 4 can autonomously drive the tractor 1 along a preset route based on the position information. The forward / backward detection unit 53 can detect the forward movement or the reverse movement of the tractor 1. The inertial measurement unit 54 detects the angular velocity and acceleration of the tractor 1. By executing the initialization process while moving the tractor 1, the inertial measurement unit 54 directs the tractor 1 at the time of executing the initialization process to the radio waves received from the satellites 105, 105, ... It is possible to obtain it based on the direction of the position change of the tractor 1 obtained based on the above. When the forward / backward detection unit 53 detects forward movement during the execution of the initialization process, the inertial measurement unit 54 sets the direction of the position change as the direction of the tractor 1, while the inertial measurement unit 54 moves forward / backward during the execution of the initialization process. When the detection unit 53 detects the reverse movement, the direction opposite to the position change is set as the direction of the tractor 1.

As a result, the inertial measurement unit 54 can correctly grasp the direction of the tractor 1 and perform the initialization process regardless of whether the tractor 1 is moved forward or backward. Therefore, the convenience of the user can be improved.

Although the preferred embodiment of the present invention has been described above, the above configuration can be changed as follows, for example.

In the initialization process of the inertial measurement unit 54, instead of the method of obtaining the velocity vector based on the Doppler effect as described above, the position information before and after the movement of the tractor 1 is obtained by GNSS positioning, respectively, and the two position information. The method may be performed by obtaining the direction of the position change from the transition of the tractor 1 and obtaining the direction of the tractor 1. Since the positions before and after the movement can be accurately obtained by using the GNSS-RTK method, the inertial measurement unit 54 can be initialized by obtaining the accurate orientation of the tractor 1 by the above method as well. .. However, the method using the Doppler effect as in the above embodiment can increase the speed of the tractor 1 with high accuracy without using a reference station and without waiting for the process of determining the so-called integer bias by the GNSS-RTK method. It is advantageous in that it can be obtained early.

The forward / backward detection unit 53 can be changed to a configuration that detects the operation position of the operation member that instructs the forward / backward movement instead of the configuration that detects the rotation of the front wheel 7.

In the above embodiment, the vehicle speed detecting unit (vehicle speed specifying unit) 59 specifies the vehicle speed of the tractor 1 by detecting the rotation of the gear shown in the figure, but the present invention is not limited to this. For example, instead of this, the vehicle speed specifying unit may be a vehicle speed sensor or the like that detects the vehicle speed by detecting the rotation speed of the front wheels 7 or the rear wheels 8.

The calculation process of the speed vector of the tractor as described in step S105 of FIG. 4 is configured to be repeated at short time intervals, and the change of the speed vector is a threshold value as to whether or not vibration is generated in the tractor 1. It may be determined by whether or not it is the above. Further, the degree of turning can also be determined by the change of the speed vector.

The degree of turning of the tractor 1 may be determined by detecting the steering angle of the front wheels 7 with a turning angle sensor instead of detecting the steering angle of the steering handle 12.

The start condition of the initialization process of the inertial measurement unit 54 shown in the above embodiment is only an example, and some of these start conditions may be omitted. Alternatively, other starting conditions may be further added. For example, the tractor 1 may be configured to include a predetermined operation tool to be operated when the user wants to start the initialization process of the inertial measurement unit 54, and the operation of this operation tool may be added to one of the start conditions. good.

Further, the order of determining the start condition of the initialization process of the inertial measurement unit 54 shown in the above embodiment is only an example, and the order may be changed.

Inertial navigation by the inertial measurement unit 54 has the property that position detection errors accumulate over time. In consideration of this, the initialization process of the inertial measurement unit 54 may be configured not only immediately after the start of the tractor 1 but also at an appropriate timing after the start of the tractor 1.

In the above embodiment, a high-precision satellite positioning system using the so-called GNSS-RTK method, which appropriately corrects the position information obtained by the GNSS method, is used, but is not limited to this, and is high. Other positioning systems may be used as long as accurate position coordinates can be obtained. For example, it is conceivable to use a relative positioning method (DGPS) or a geostationary satellite type satellite navigation augmentation system (SBAS).

When the predetermined process is not performed even after a certain period of time has passed since the engine 10 was turned on, the display control unit 31 causes the user to display a warning screen on the display 37 of the wireless communication terminal 46. On the other hand, the initialization process of the inertial measurement unit 54 may be promoted.

In the above embodiment, the determination and processing of FIGS. 4 and 5 are performed with the activation of the tractor 1 as a trigger, but the trigger is not limited to this. For example, in the first embodiment, after the tractor 1 is activated, the forward / backward detection unit 53 detects the advance of the tractor 1, and in the second embodiment, after the tractor 1 is activated, the forward / backward detection unit 53 is used as a trigger. The trigger may be that the forward or backward movement of the tractor 1 is detected by the tractor 1. In this case, in the flowchart of FIG. 4, after the determination of steps S102 to S104 is performed, the initialization process is executed when the start conditions of the initialization process are satisfied, and in the flowchart of FIG. 5, after that, step S201 After the determination of S203 is performed, the initialization process is appropriately executed according to whether the detection result of the forward / backward detection unit 53 is forward or backward by satisfying the start conditions of these initialization processes. By not starting the IMU initialization process when the tractor 1 must be moved backward or when a predetermined operation is performed without moving, the control unit 4 performs various processes other than the IMU initialization process. It will be possible to execute with priority.

1 Tractor (robot tractor, work vehicle)
4 Control unit (autonomous driving control unit)
52 Position information acquisition unit 53 Forward / backward detection unit 54 Inertial measurement unit 100 Autonomous traveling system 105 Satellite (positioning satellite)

Claims (2)

A location information acquisition unit that acquires location information of work vehicles based on radio waves received from satellites,
An autonomous travel control unit capable of autonomously traveling the work vehicle along a preset route based on the position information.
A forward / backward detection unit capable of detecting the forward movement or reverse movement of the work vehicle,
An inertial measurement unit that detects the angular velocity and acceleration of the work vehicle,
Equipped with
When the forward / backward movement detection unit detects the forward movement each time the work vehicle is started, the inertial measurement unit executes an initialization process for the direction of the work vehicle based on the position information. An autonomous driving system that features it. A location information acquisition unit that acquires location information of work vehicles based on radio waves received from satellites,
An autonomous travel control unit capable of autonomously traveling the work vehicle along a preset route based on the position information.
A forward / backward detection unit capable of detecting the forward movement or reverse movement of the work vehicle,
An inertial measurement unit that detects the angular velocity and acceleration of the work vehicle,
Equipped with
When the forward / backward movement detection unit detects the reverse movement each time the work vehicle is started, the inertial measurement unit reverses the direction of the position information and regards the work vehicle as a forward movement state. An autonomous driving system characterized in that it is possible to execute a conversion process.

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