JP7047659B2 - Control device and control method for automatic guided vehicle - Google Patents

Description

The present invention relates to a control device and a control method for an automatic guided vehicle.

As an automatic guided vehicle, there is a vehicle that detects a guide line installed on a traveling surface by a sensor and travels along the detected guide line. The guide line is composed of a straight line or a curved line, and there is a place where two guide lines extending in the straight line intersect. At the intersection of such two guide lines, the automatic guided vehicle may change from one guide line to the other guide line, causing the automatic guided vehicle to make a right turn or a left turn. However, there is a lower limit (minimum turning radius) in the turning radius of the automatic guided vehicle, and the automatic guided vehicle cannot be driven by tracing the guide line as it is at the intersection as described above. Therefore, it is necessary to calculate the trajectory (hereinafter referred to as a turning trajectory) for interpolation of the traveling route from leaving the guide line before the transfer (one side) to reaching the guide line after the transfer (the other side). Become.

Conventionally, the method described in Patent Document 1 is known as a method for automatically generating a traveling track of an automatic guided vehicle. In the same document, a traveling track between two designated points is obtained as a triple clothoid curve connecting three clothoid curves.

Japanese Unexamined Patent Publication No. 2011-145977

However, in order to obtain the turning trajectory at the intersection by the method described in the same document 1, it is necessary to determine the start point and the ending point of the turning trajectory in advance. No disclosure has been made as to what is required. Further, even if both points are determined, there is no guarantee that the obtained turning track will be a track that the automatic guided vehicle can actually travel.

The present invention has been made in view of such circumstances, and the problem to be solved thereof is an automatic guided vehicle control device capable of traveling an automatic guided vehicle on an accurate track when shifting a traveling track between straight tracks. And to provide a control method.

When the automatic guided vehicle control device that solves the above problems shifts the travel track of the automatic guided vehicle from the first straight track that extends straight to the second straight track that intersects the first straight track and extends straight. It is provided with a turning track calculation unit that calculates the turning trajectory of the automatic guided vehicle, and a traveling control unit that controls the traveling of the automatic guided vehicle so as to travel along the turning track calculated by the turning track calculation unit. Then, the turning orbit calculation unit is a first clothoid that becomes a cloth along a clothoid curve whose curvature increases in proportion to the curve length from the turning start point, which is a point on the first straight orbit where the turning orbit starts. A section, a second clothoid section that is an orbit along a clothoid curve whose curvature increases in proportion to the curve length from the turning end point, which is a point on the second straight track where the turning orbit ends, and a section. The orbit consisting of three sections, that is, an arc section that is smoothly connected to the end point of the first clothoid section at the start point and is a trajectory along an arc that is smoothly connected to the second clothoid section at the end point of the section, is described above. It is calculated as a swivel trajectory, and the calculation of the swivel trajectory is performed by the proportional constant of the curvature with respect to the curve length in the clothoid curve of the first clothoid section, and the curve length in the clothoid curve of the second clothoid section. To the proportional constant of the curvature with respect to, the radius of curvature of the arc in the arc section, the position of the intersection between the first straight orbit and the second straight orbit, and the intersection angle between the first straight orbit and the second straight orbit. It is based on.

Further, the control method of the unmanned carrier that solves the above-mentioned problems is a turning when shifting the traveling track from the first straight track extending in a straight line to the second straight track crossing the first straight line and extending in a straight line. As the orbit, the first clothoid section which becomes the orbit along the clothoid curve whose curvature increases in proportion to the curve length from the turning start point which is the point on the first straight orbit where the turning orbit starts, and the turning. The second clothoid section, which is an orbit along a clothoid curve whose curvature increases in proportion to the curve length from the turning end point, which is a point on the second straight-ahead orbit where the orbit ends, and the second clothoid section at the start point of the section. The first clothoid section is an orbit consisting of three sections: an arc section that is smoothly connected to the end point of one clothoid section and is an orbit along an arc that is smoothly connected to the second clothoid section at the end point of the section. The proportionality constant of the curvature to the cloth length in the clothoid curve, the proportionality constant of the curvature to the curve length in the clothoid curve of the second clothoid section, the radius of curvature of the arc in the arc section, the first straight trajectory and the first. Calculation is performed based on the position of the intersection with the 2 straight-ahead track and the intersection angle between the 1st straight-ahead track and the 2nd straight-ahead track, and the traveling control of the unmanned carrier so as to travel along the calculated turning track. It is carried out.

In the above-mentioned automatic guided vehicle control device and control method, a feasible track is calculated as a turning track when the traveling track is transferred between straight tracks, and the traveling track can be smoothly transferred.
The turning track calculation unit in the control device of the unmanned carrier has a constant of proportionality of the curvature with respect to the curve length in the clothoid curve of the first clothoid section, and the curvature with respect to the curve length in the clothoid curve of the second clothoid section. The proportional constant of the above and the radius of curvature of the arc in the arc section are constants whose values are predetermined, and the position of the intersection between the first straight orbit and the second straight orbit, and the first straight orbit. The intersection angle between the cloth and the second straight path can be configured to acquire a value for each calculation of the turning track and perform the calculation of the turning track. Further, the control method of the unmanned carrier is a constant of proportionality of the curvature to the curve length in the clothoid curve of the first clothoid section, a proportionality constant of the curvature to the curve length in the clothoid curve of the second clothoid section, and The radius of curvature of the arc in the arc section is a constant whose value is predetermined, the position of the intersection between the first straight orbit and the second straight orbit, and the first straight orbit and the second straight orbit. The intersection angle of can be obtained by acquiring a value for each calculation of the turning trajectory, and the calculation of the turning trajectory can be performed. In such a case, it becomes easy to set the turning radius of the turning track according to the turning ability of the automatic guided vehicle.

On the other hand, the turning track calculation unit in the control device of the unmanned carrier has a proportional constant of the curvature with respect to the curve length in the clothoid curve of the first clothoid section, and the curve length in the clothoid curve of the second clothoid section. The proportional constant of the curvature is a constant whose value is predetermined, and the radius of curvature of the arc in the arc section, the position of the intersection of the first straight orbit and the second straight orbit, and the first straight. The intersection angle between the orbit and the second straight-ahead orbit can be configured even if a value is acquired for each calculation of the turning orbit and the calculation of the turning orbit is performed. Further, in the control method of the unmanned carrier, the proportionality constant of the curvature to the curve length in the clothoid curve of the first clothoid section and the proportionality constant of the curvature to the curve length in the clothoid curve of the second clothoid section are , The value is set to a predetermined constant, the radius of curvature of the arc in the arc section, the position of the intersection of the first straight track and the second straight track, and the first straight track and the second straight track. The intersection angle of can be obtained by acquiring a value for each calculation of the turning trajectory, and the calculation of the turning trajectory can be performed. In such a case, it becomes easy to set the turning radius according to the situation around the turning trajectory.

Further, the turning track calculation unit in the control device of the unmanned carrier calculates the turning track as a function of the mileage from the turning start point and the curvature of the traveling track, and the traveling control unit calculates the turning track. It is desirable to perform the travel control by controlling the steering angle according to the travel distance from the turning start point so that the relationship between the travel distance and the curvature in the function calculated by the calculation unit is maintained. Further, in the automatic guided vehicle control method, the turning track is calculated as a function of the mileage from the turning start point and the curvature of the traveling track, and the traveling control is the mileage and the curvature in the function. It is desirable that the steering angle is controlled according to the mileage from the turning start point so that the relationship is maintained. In such a case, it is possible to easily control the automatic guided vehicle to travel along the calculated turning track.

According to the present invention, the automatic guided vehicle can travel on an accurate track when the traveling track shifts between straight tracks.

The side view of the reach type unmanned forklift to which the control device and the control method of 1st Embodiment are applied. The figure which shows the plane structure of the forklift schematically. A block diagram schematically showing the configuration of the control device of the forklift. The figure which shows an example of the setting mode of the turning trajectory at the intersection of the straight track. The figure which shows the calculation mode of a turning trajectory. A graph showing the relationship between the mileage and the curvature in the turning track calculated by the turning track calculation unit. The figure which showed the 2nd clothoid curve in the x'-y'coordinate system. The figure which shows the calculation mode of a turning trajectory. (A) is a figure which shows the setting mode of preferable turning orbit in each case where an obstacle does not exist near a turning orbit, and (b) is a figure which shows the setting mode of the turning orbit in the case where the same obstacle exists. The block diagram schematically showing the structure of the control apparatus of 3rd Embodiment.

(First Embodiment)
Hereinafter, the first embodiment of the control device and the control method for the automatic guided vehicle will be described in detail with reference to FIGS. 1 to 8. In the control device and the control method of the present embodiment, the reach type unmanned forklift (in the following description, simply referred to as "forklift") is an automatic guided vehicle to be controlled.

As shown in FIG. 1, the forklift 10 includes a vehicle body body 11 and a pair of left and right legs 12 projecting forward from the front surface of the vehicle body body 11. A pair of left and right masts 13 that can be moved in the front-rear direction by a reach cylinder (not shown) are arranged between the left and right legs 12. A lift bracket 15 is arranged between the left and right masts 13 so as to be movable in the vertical direction along the mast 13 by a lift cylinder 14. A pair of left and right forks 16 are attached to the lift bracket 15.

As shown in FIG. 2, driven wheels 17 are arranged on the lower surfaces of the tip portions of the left and right legs 12, respectively. Further, a steering drive wheel 18 is arranged on the left side of the lower surface of the vehicle body 11. A caster wheel 19 is arranged on the lower right surface of the vehicle body 11.

A traveling motor 20 is provided inside the vehicle body 11, and the steering drive wheels 18 are rotationally driven by the traveling motor 20. Further, a steering motor 21 is provided inside the vehicle body 11, and the steering drive wheels 18 are rotated in the horizontal direction by the steering motor 21. That is, the steering motor 21 changes the steering angle of the steering drive wheels 18. A steering angle sensor 22 for detecting the steering angle of the steering drive wheel 18 is provided inside the vehicle body 11.

A support arm 23 extends forward at the center position of the lower front portion of the vehicle body 11. The forklift 10 is provided with a guide wire detection sensor 24 at the tip of the support arm 23 and the lower surface of the vehicle body body 11. Further, a pair of left and right mark detection sensors 25 are provided on the lower surface of the vehicle body body 11.

The guide wire detection sensor 24 is a sensor that detects a guide wire installed on the traveling surface of the forklift 10. The guide wire is a line indicating the traveling track of the forklift 10 on the traveling surface. For example, a magnetic tape having a certain width attached to the traveling surface, an electric coil embedded in a straight line at regular intervals on the traveling surface, or the like is used. It is formed. The two guide wire detection sensors 24 provided before and after the forklift 10 detect the position of the guide wire by the magnetic field generated by the guide wire, the electric field, and the like. Then, from the detection information of the front and rear guide line detection sensors 24, the deviation from the guide line and the inclination of the front and rear of the vehicle can be recognized. A plurality of guide lines extending in a straight line are installed on the traveling surface.

The mark detection sensor 25 is a sensor that detects marks installed in various places on the traveling surface. The mark notifies the forklift 10 of a position where a pre-commanded operation such as a temporary stop or a change of a traveling guide line is executed, and is formed of, for example, a rectangular magnetic tape attached to a traveling surface. The mark detection sensor 25 detects the position of the mark by the magnetic field generated by the mark or the like. The mark is installed on either the left or right side of the guide wire, and any of the pair of left and right mark detection sensors 25 can detect the mark regardless of whether the mark is installed on the left or right side.

An electronic control unit 26 as a control device is provided inside the vehicle body 11. As shown in FIG. 3, the detection signals of the steering angle sensor 22, the guide line detection sensor 24, and the mark detection sensor 25 described above are input to the electronic control unit 26, respectively. Then, the electronic control unit 26 has a traveling motor 20 and a steering motor 21 so that the forklift 10 travels in accordance with the command based on a command input from the outside before the start of traveling of the forklift 10 and their detection signals. To control. The command to the forklift 10 is composed of the number of detected marks after the start of running and the operation to be executed. For example, at the position of the third mark detected after the start of running, a command to stop for a predetermined time is given. , And so on.

As such a command, at the intersection I of two guide lines as shown in FIG. 4, another guide line intersecting the guide line from the straight track along the guide line running on the travel track of the forklift 10. There is an instruction to change the traveling track to the straight track along the line. The command at this time includes the number of detected marks after the start of running until the mark M corresponding to the command is detected, the distance L0 from the position of the mark M to the intersection I, and the intersection of the straight tracks before and after the switching. Information on the angle θ is included. In the following description, the straight track before the transfer of the traveling track is described as the first straight track S1, and the straight track after the transfer is described as the second straight track S2.

At this time, the forklift 10 changes the traveling track from the first straight track S1 to the second straight track S2 through the turning track S3 that can travel smoothly as shown by the broken line in the figure. The electronic control unit 26 includes a turning orbit calculation unit 27 that calculates such a turning orbit S3 based on each information acquired at the time of the above command and the detection signals of the guide line detection sensor 24 and the mark detection sensor 25. Further, the electronic control unit 26 controls the traveling motor 20 and the steering motor 21 so that the forklift 10 travels along the turning trajectory S3 based on the calculation result of the turning track S3 and the detection signal of the steering angle sensor 22. It is provided with a traveling control unit 28.

Subsequently, with reference to FIG. 5, the calculation of the turning trajectory S3 performed by the turning trajectory calculation unit 27 will be described. The turning orbit calculation unit 27 calculates an orbit including three sections of a first clothoid section, a second clothoid section, and an arc section as a turning orbit S3. The orbit of the first clothoid section is an orbit along a curve (clothoid curve) in which the curvature changes at a constant ratio with respect to the locus length from the turning start point P0, which is a point on the first straight orbit S1. The orbit of the arc section is an orbit along the arc following the first clothoid section. The orbit of the second clothoid section is an orbit along a clothoid curve whose curvature changes at a constant ratio to the locus length from the turning end point P3, which is a point on the second straight orbit S2 following the arc section. .. In the following description, the clothoid curve of the first clothoid section will be referred to as a first clothoid curve, and the clothoid curve of the second clothoid section will be referred to as a second clothoid curve. The clothoid curve is a curve whose curvature increases in proportion to the curve length. Therefore, the traveling locus when traveling while expanding the steering angle in proportion to the traveling distance becomes a clothoid curve.

In the present embodiment, the calculation of the turning trajectory S3 is performed after the proportional constant of the curvature of the clothoid curve in the first and second clothoid sections and the turning radius R in the arc orbit of the arc section are predetermined. Once the proportionality constant, the turning radius R, and the crossing angle θ are determined, the relationship between the traveling distance from the turning start point P0 in the turning track S3 and the curvature of the traveling track can be determined.

FIG. 6 shows the relationship between the mileage from the turning start point P0 on the turning track S3 and the curvature of the turning track S3. As shown in the figure, the mileage of the forklift 10 in the first clothoid section and the mileage of the forklift 10 in the second clothoid section are known. On the other hand, the mileage of the forklift 10 in the arc section is the product (= α × R) of the center angle α of the arc trajectory and the turning radius R in the arc section. Then, the center angle α can be obtained as a value indicating the relationship of the following equation.

なお、τ１、τ２はそれぞれ、第１クロソイド曲線、第２クロソイド曲線の曲線形状を決めるパラメータとなっている。幾何学的には、τ１は、第１クロソイド区間の終了点Ｐ１における第１クロソイド曲線の接線と第１直進軌道Ｓ１との交差角度を表している。τ１の値は、旋回半径Ｒと第１クロソイド曲線の曲線長に対する曲率の比例定数とにより一義に定まる値となっている。また、τ２は、第２クロソイド区間の開始点Ｐ２における第２クロソイド曲線の接線と第２直進軌道Ｓ２との交差角度を表している。τ２の値は、旋回半径Ｒと第２クロソイド曲線の曲線長に対する曲率の比例定数とにより一義に定まる値となっている。

Note that τ1 and τ2 are parameters that determine the curve shapes of the first clothoid curve and the second clothoid curve, respectively. Geometrically, τ1 represents the intersection angle between the tangent line of the first clothoid curve and the first straight trajectory S1 at the end point P1 of the first clothoid section. The value of τ1 is a value uniquely determined by the turning radius R and the constant of proportionality of the curvature to the curve length of the first clothoid curve. Further, τ2 represents the intersection angle between the tangent line of the second clothoid curve and the second straight track S2 at the start point P2 of the second clothoid section. The value of τ2 is a value uniquely determined by the turning radius R and the constant of proportionality of the curvature to the curve length of the second clothoid curve.

By the way, in order to drive the forklift 10 along the turning track S3, the traveling motor 20 and the steering motor 21 are controlled so that the curvature changes by satisfying the above relationship with respect to the traveling distance from the turning start point P0. do it. However, at this point, the position of the turning start point P0 is unknown.

In order to obtain the position of the turning start point P0, the turning start point P0 is set as the origin (0,0), the traveling direction of the first straight trajectory S1 is the positive direction of the x-axis, orthogonal to the x-axis, and the first straight going. The start point and end point of each section are used as coordinates in a Cartesian coordinate system (hereinafter referred to as xy coordinate system) in which the direction toward the inside of the turning of the turning orbit S3 as viewed from the orbit S1 is the positive direction of the y-axis. Define the coordinates of. In the following, the coordinates of the end point P1 of the first clothoid section at this time are (x1, y1), the coordinates of the start point P2 of the second clothoid section are (x2, y2), and the coordinates of the turning end point P3 are (x3, y1). It is expressed as y3). Further, the coordinates of the turning center O of the arc orbit in the arc section are expressed as (xr, yr).

At this time, the coordinate values x1 and y1 of the end point P1 of the first clothoid section can be obtained as a value indicating the relationship of the following equation from the approximate equation of the clothoid curve.

一方、図７に示すように、下記のｘ’－ｙ’座標系における第２クロソイド区間の開始点Ｐ２の座標（ｘ２’，ｙ２’）を定義する。ｘ’－ｙ’座標系は、旋回終了点Ｐ３を原点（０，０）とするとともに、第２直進軌道Ｓ２の進行方向の逆方向をｘ’軸の正方向、ｘ’軸に直交し、且つ第２直進軌道Ｓ２から見て旋回軌道Ｓ３の旋回内側に向う方向をｙ’軸の正方向とする直交座標系である。ｘ’－ｙ’座標系での第２クロソイド区間の開始点Ｐ２の座標値ｘ２’，ｙ２’は、ｘ－ｙ座標系での第１クロソイド区間の終了点Ｐ１の座標値ｘ１，ｙ１と同様に求めることができる。すなわち、ｘ’－ｙ’座標系における開始点Ｐ２の座標値ｘ２’，ｙ２’は、下式の関係を満たす値となる。

On the other hand, as shown in FIG. 7, the coordinates (x2', y2') of the start point P2 of the second clothoid section in the following x'-y' coordinate system are defined. In the x'-y'coordinate system, the turning end point P3 is set as the origin (0,0), and the direction opposite to the traveling direction of the second straight trajectory S2 is orthogonal to the positive direction of the x'axis and the x'axis. Moreover, it is a Cartesian coordinate system in which the direction toward the inside of the turning of the turning orbit S3 when viewed from the second straight orbit S2 is the positive direction of the y'axis. The coordinate values x2'and y2'of the start point P2 of the second clothoid section in the x'-y' coordinate system are the same as the coordinate values x1 and y1 of the end point P1 of the first clothoid section in the xy coordinate system. Can be asked for. That is, the coordinate values x2'and y2' of the starting point P2 in the x'-y' coordinate system are values that satisfy the relationship of the following equation.

ここで、第１クロソイド区間の終了点Ｐ１における第１クロソイド曲線の接線が、下式の関係を満たす直線であるとする。

Here, it is assumed that the tangent line of the first clothoid curve at the end point P1 of the first clothoid section is a straight line satisfying the relationship of the following equation.

このとき、ｘ－ｙ座標系における旋回中心Ｏの座標値ｘｒ，ｙｒは、幾何学的関係から、下式の関係を満たす値として求めることができる。

At this time, the coordinate values xr and yr of the turning center O in the xy coordinate system can be obtained as values satisfying the relationship of the following equation from the geometrical relationship.

ｘ－ｙ座標系での第２クロソイド区間の開始点Ｐ２の座標値ｘ２，ｙ２は、第１クロソイド区間の終了点Ｐ１の座標値ｘ１、ｙ１、旋回中心Ｏの座標値ｘｒ，ｙｒ、及び回転行列Ｒ（α）に対して、下式の関係を満たす値となる。

The coordinate values x2 and y2 of the start point P2 of the second crossoid section in the xy coordinate system are the coordinate values x1, y1 of the end point P1 of the first crossoid section, the coordinate values xr, yr, and the rotation of the turning center O. It is a value that satisfies the relationship of the following equation with respect to the matrix R (α).

ｘ－ｙ座標系における旋回終了点Ｐ３の座標値ｘ３，ｙ３は、ｘ’－ｙ’座標系における第２クロソイド区間の開始点Ｐ２の座標値ｘ２’，ｙ２’、ｘ－ｙ座標系における第２クロソイド区間の開始点Ｐ２の座標値ｘ２，ｙ２、回転行列Ｒ（π－θ）に対して下式の関係を満たす値となる。

The coordinate values x3 and y3 of the rotation end point P3 in the xy coordinate system are the coordinate values x2', y2'and the second in the xy coordinate system of the start point P2 of the second crossoid section in the x'-y' coordinate system. It is a value that satisfies the relationship of the following equation with respect to the coordinate values x2 and y2 of the start point P2 of the two crossoid sections and the rotation matrix R (π−θ).

図８に示すように、旋回開始点Ｐ０と旋回終了点Ｐ３の距離Ｄは、下式の関係を満たす値として求められる。

As shown in FIG. 8, the distance D between the turning start point P0 and the turning end point P3 is obtained as a value satisfying the relationship of the following equation.

一方、同図に示す角度θ１、θ２はそれぞれ、下式の関係を満たす値として求められる。

On the other hand, the angles θ1 and θ2 shown in the figure are obtained as values satisfying the relationship of the following equations, respectively.

これらより、交差点Ｉから旋回開始点Ｐ０までの距離（旋回開始距離Ｌ）は、下式の関係を満たす値として求められる。

From these, the distance from the intersection I to the turning start point P0 (turning start distance L) is obtained as a value satisfying the relationship of the following equation.

上述の通り、マークＭの位置から交差点Ｉまでの距離Ｌ０は既知である。よって、旋回開始距離Ｌが求まれば、マークＭの位置から第１直進軌道Ｓ１に沿って距離（Ｌ０－Ｌ）だけ走行した位置として旋回開始点Ｐ０の位置を求めることができる。

As described above, the distance L0 from the position of the mark M to the intersection I is known. Therefore, if the turning start distance L is obtained, the position of the turning start point P0 can be obtained as the position traveled by the distance (L0-L) from the position of the mark M along the first straight track S1.

Actually, for the sake of simplicity of the calculation, the turning trajectory calculation unit 27 uses τ1 as a parameter for determining the curve shapes of the first clothoid curve and the second clothoid curve, instead of the proportional constants N1 and N2 of the curvature with respect to the trajectory length. , Τ2 is used to calculate the turning trajectory S3. τ1 and τ2 are values uniquely determined by the proportionality constants N1 and N2 and the turning radius R. That is, the turning trajectory calculation unit 27 only performs a part of the calculation in advance, and substantially performs the calculation of the turning track S3 based on the proportional constants N1 and N2. Incidentally, the values of the turning radius R and τ1 and τ2 are stored in the electronic control unit 26 as constants whose values are predetermined.

Then, the turning trajectory calculation unit 27 determines the values of the turning radii R, τ1, and τ2 stored as constants, the distance L0 from the position of the mark M acquired through the command before the start of travel to the intersection I, and the intersection angle θ. Based on the value, a function of the mileage from the turning start point P0 in the turning track S3 and the radius of the traveling track is calculated. Further, the turning trajectory calculation unit 27 calculates the turning start distance L. Then, the turning trajectory calculation unit 27 outputs those calculation results to the traveling control unit 28.

The travel control unit 28 has the travel distance of the function calculated by the rotation trajectory calculation unit 27 from the position (turning start point P0) traveled along the first straight track S1 from the position of the mark M. The steering angle is controlled according to the mileage from the turning start point P0 so that the relationship with the curvature is maintained. As a result, the forklift 10 is driven so as to shift the traveling track from the first straight track S1 through the turning track S3 to the second straight track S2.

In the present embodiment, the turning trajectory S3 is calculated after determining the turning radius R of the arc section, the rate of change of the curvature with respect to the mileage in the first clothoid section and the second clothoid section. Once the rate of change in curvature with respect to the mileage is determined, the rate of change in the steering angle with respect to the mileage is also determined. On the other hand, the minimum turning radius of the forklift 10 and the speed at which the steering angle is changed have a limit determined by the performance of the steering motor 21. In that respect, if the turning radius S3 is calculated after determining the turning radius R and the rate of change of the curvature in advance, the turning track S3 can be calculated as an actually travelable track that does not require unreasonable steering exceeding the limit.

Further, in the present embodiment, the turning track calculation unit 27 calculates the turning track S3 as a function of the mileage and the curvature, and commands the traveling control unit 28. On the other hand, the traveling control unit 28 can realize traveling along the turning track S3 only by determining the operation amount of the steering angle so as to maintain the relationship between the traveling distance and the curvature. On the other hand, when the turning trajectory S3 is commanded using the two-dimensional coordinates of the traveling surface, a complicated calculation is required to determine the operation amount of the steering angle, and the calculation for the traveling control of the traveling control unit 28 is required. The load will increase.

According to the control device and control method for the automatic guided vehicle of the present embodiment described above, the following effects can be obtained.
(1) As the turning track S3 when shifting the traveling track from the first straight track S1 to the second straight track S2, it is possible to reliably set a track that can actually be traveled.

(2) Since the turning track S3 is calculated as a function of the mileage and the curvature, it is possible to easily control the vehicle for traveling the forklift 10 along the turning track S3.
(Second Embodiment)
Next, a second embodiment of the control device and the control method of the automatic guided vehicle will be described with reference to FIG. 9. In the present embodiment and the third embodiment described later, the same reference numerals are given to the configurations common to the above-described embodiments, and detailed description thereof will be omitted.

Various obstacles may exist around the track on which the automatic guided vehicle travels. And, such an obstacle may limit the turning trajectory as described above.
In the case of FIG. 9A, the obstacle E is separated from the intersection I of the first straight track S1 and the second straight track S2 on which the forklift 10 tries to shift the traveling track, and the turning track S3 having a relatively large turning radius. Obstacle E does not interfere with driving even if it passes through. On the other hand, in the case of FIG. 9B, the obstacle E exists near the intersection I, and the turning track S3 that can travel while avoiding the obstacle E has a small turning radius. Become. On the other hand, even in the range above the minimum turning radius of the forklift 10, if the turning radius is made smaller than a certain level, there may be an adverse effect that the traveling speed must be reduced. In this way, flexible adjustment of the turning radius of the turning track S3 may be required depending on the surrounding conditions.

In the first embodiment, the turning radius R of the turning track S3 is set to a constant. On the other hand, in the present embodiment, the turning radius R is instructed together with the distance L0 from the position of the mark M to the intersection I and the intersection angle θ in the command before the start of traveling, and the turning trajectory calculation unit 27 is instructed to do so. It is configured to calculate the turning trajectory S3 based on the turning radius R.

In such a case, since the values of τ1 and τ2 change depending on the value of the instructed turning radius R, the values of τ1 and τ2 cannot be calculated in advance as in the case of the first embodiment. Therefore, in the present embodiment, the proportionality constant of the curvature with respect to the curve length is used as a parameter for determining the curve shapes of the first clothoid curve and the second clothoid curve. These proportional constants are stored in the electronic control unit 26 as constants having predetermined values. Then, the turning trajectory calculation unit 27 calculates the values of τ1 and τ2 based on the proportionality constant of each clothoid curve and the value of the designated turning radius R, and then performs the same calculation of the turning trajectory S3 as in the first embodiment. I try to do it. In such an embodiment, the turning track S3 can be calculated as an appropriate track according to the surrounding conditions such as the presence or absence of an obstacle that interferes with the running.

(Third Embodiment)
Subsequently, the third embodiment of the control device and the control method of the automatic guided vehicle will be described with reference to FIG. The control devices and control methods of the first and second embodiments have been applied to automatic guided vehicles operated by a so-called guide method, in which guided traveling is performed using guide lines and marks installed in a traveling environment. As an operation mode of the automatic guided vehicle, in addition to the guide method, there is a guideless method in which the vehicle is independently driven in a driving environment in which a guide line, a mark, or the like is not installed. In the present embodiment, a case where the calculation logic of the turning track and the running control at the time of changing the running track in the first and second embodiments are applied to a forklift that runs unmanned by a guideless method will be described.

FIG. 10 shows a configuration of an electronic control unit 26'as a control device of the present embodiment mounted on a forklift that travels unmanned by a guideless system. Instead of the guide line detection sensor 24 and the mark detection sensor 25, the guided vehicle is provided with a range sensor 30 that scans the surrounding environment (obstacles, etc.) of the forklift. In the present embodiment, as the range sensor 30, a laser scanning type range sensor that scans a laser to detect the distance and direction of an obstacle or the like is adopted.

The electronic control unit 26'in the present embodiment stores information on the surrounding environment map information 32, which is information on the traveling environment of the forklift. The surrounding environment map information 32 includes position information of obstacles and the like in the traveling environment of the forklift, and location information of the traveling track of the forklift corresponding to the guide line (hereinafter, referred to as a virtual guide line).

Further, the electronic control unit 26'is provided with a vehicle position identification unit 31. The vehicle position identification unit 31 collates the detection result of the range sensor 30 with the surrounding environment map information 32, and performs a process of identifying the current position of the forklift. Then, the traveling control unit 28'provided to the electronic control unit 26'of the present embodiment is traveling, which is registered in the current forklift position identified by the own vehicle position identification unit 31 and the surrounding environment map information 32. By collating with the position information of the virtual guide line, the traveling motor 20 and the steering motor 21 are controlled so that the forklift travels along the virtual guide line.

Further, the electronic control unit 26'in the present embodiment is also provided with a turning track calculation unit 27'that calculates the turning track S on which the forklift travels when changing the traveling track (virtual guide line). The turning orbit calculation unit 27 in the first and second embodiments has calculated the turning orbit S in response to the detection of the mark M corresponding to the transfer command. On the other hand, in the case of the present embodiment in which the mark M does not exist in the traveling environment of the forklift, the turning track S is calculated by the turning track calculation unit 27'in the following manner.

That is, in the present embodiment, the surrounding environment map information 32 includes the position information of the road marker point (hereinafter referred to as a virtual mark) corresponding to the mark M. Then, the forklift is instructed to run in a form associated with such a virtual mark. The turning track calculation unit 27'combines the position of the forklift truck identified by the vehicle position identification unit 31 with the position information of the virtual mark registered in the surrounding environment map information 32, and shifts to a virtual mark corresponding to the transfer command. We are confirming the arrival of the forklift truck. Then, the turning trajectory calculation unit 27'calculates the turning trajectory S according to the confirmation. Incidentally, the calculation itself of the turning trajectory S3 is performed in the same manner as in the case of the first and second embodiments.

The above embodiment can also be modified and implemented as follows.
In addition to identifying the position of the forklift, the vehicle position identification unit 31 in the third embodiment updates the surrounding environment map information 32 according to the scanning result of the surrounding environment by the range sensor 30, so-called SLAM (Simultaneous). It may be configured to perform Localization and Mapping).

-The identification of the vehicle position (update of the surrounding environment map information 32) in the third embodiment is performed by a sound wave type such as a microphone array that scans the surrounding environment using sound waves instead of the laser scanning type range sensor 30. It may be performed by using a range sensor of the above, an image processing system that recognizes the surrounding environment based on the image pickup data of a stereo camera, or the like.

-In the above embodiment, the values necessary for the calculation of the turning track S3 such as the position of the intersection I (distance L0 from the position of the mark M) and the intersection angle θ are acquired through the command before the start of traveling, but the intersection I It is also possible to acquire those values by other timings and means, such as acquiring those values from a transmitter installed in front of.

-In the above embodiment, the turning trajectory S3 is calculated as a function of the traveling distance and the curvature, but the turning trajectory S3 may be calculated based on the coordinate value of the trajectory in the two-dimensional coordinates of the traveling surface.

-The control for the reach type automatic forklift in the above embodiment can be similarly applied to other automatic guided vehicles.

10 ... Forklift (unmanned carrier), 18 ... Steering drive wheel, 20 ... Driving motor, 21 ... Steering motor, 22 ... Steering angle sensor, 24 ... Guide line detection sensor, 25 ... Mark detection sensor, 26, 26' ... Electronic control unit, 27, 27'... Turning trajectory calculation unit, 28, 28' ... Travel control unit, 30 ... Range sensor, 31 ... Own vehicle position identification unit, 32 ... Surrounding environment map information, S1 ... First straight ahead Orbit, S2 ... second straight orbit, S3 ... turning orbit, I ... intersection, θ ... intersection angle.

Claims (10)

A mark detection sensor that detects marks installed on the running surface,
The turning track when shifting the traveling track of the automatic guided vehicle from the first straight track extending in a straight line to the second straight track crossing the first straight track and extending in a straight line, and the turning from the position of the mark. A turning orbit calculation unit that calculates the turning start distance, which is the distance to the turning start point, which is a point on the first straight track where the orbit starts .
After going straight along the first straight track for the turning start distance from the position of the mark, the automatic guided vehicle is controlled to run along the turning track calculated by the turning track calculation unit. The driving control unit to be performed and
Equipped with
The turning orbit calculation unit includes a first clothoid section that is an orbit along a clothoid curve whose curvature increases in proportion to the curve length from the turning start point, and the second straight orbit at which the turning orbit ends. The second clothoid section, which is a trajectory along the clothoid curve whose curvature increases in proportion to the curve length from the turning end point, which is the upper point, and the end point of the first clothoid section at the start point of the section are smooth. The orbit consisting of three sections, that is, an arc section that is connected and is an orbit along an arc that is smoothly connected to the second clothoid section at the end point of the section, is calculated as the turning orbit , and the turning start distance is calculated. It ’s a thing,
Moreover, the calculation of the turning trajectory and the turning start distance is performed by the proportionality constant of the curvature to the curve length in the clothoid curve of the first clothoid section and the proportionality of the curvature to the curve length in the clothoid curve of the second clothoid section. The constant, the radius of curvature of the arc in the arc section , the distance from the position of the mark to the intersection of the first straight track and the second straight track, and the intersection angle between the first straight track and the second straight track. A control device for an unmanned transport vehicle, which is based on this. Stores peripheral environment map information that is information on the traveling environment of the automatic guided vehicle, including the position information of the virtual guide line that indicates the traveling track of the automatic guided vehicle and the position information of the virtual mark that serves as the road marker point.
The turning track when shifting the traveling track of the automatic guided vehicle from the first straight track extending in a straight line to the second straight track crossing the first straight track and extending in a straight line, and the position of the virtual mark. A turning orbit calculation unit that calculates the turning start distance, which is the distance to the turning start point, which is a point on the first straight track where the turning orbit starts .
Travel control of the automatic guided vehicle so that it travels straight along the first straight track for the turning start distance from the position of the virtual mark and then travels along the turning track calculated by the turning track calculation unit. And the driving control unit that performs
Equipped with
The turning orbit calculation unit is on a first clothoid section that is an orbit along a clothoid curve whose curvature increases in proportion to the curve length from the turning start point and on the second straight orbit at which the turning orbit ends. The second clothoid section, which is a trajectory along the clothoid curve whose curvature increases in proportion to the curve length from the turning end point, which is a point, and the end point of the first clothoid section at the start point of the section are smoothly connected. The orbit consisting of three sections, that is, an arc section that is an orbit along an arc smoothly connected to the second clothoid section at the end point of the section, is calculated as the turning orbit.
Moreover, the calculation of the turning trajectory and the turning start distance is performed by the proportionality constant of the curvature to the curve length in the clothoid curve of the first clothoid section and the proportionality of the curvature to the curve length in the clothoid curve of the second clothoid section. A constant, the radius of curvature of the arc in the arc section , the distance from the position of the virtual mark to the intersection of the first straight orbit and the second straight orbit, and the intersection angle between the first straight orbit and the second straight orbit. A control device for an unmanned transport vehicle, which is based on the above. The turning trajectory calculation unit is
The proportionality constant of the curvature to the curve length in the clothoid curve of the first clothoid section, the proportionality constant of the curvature to the curve length in the clothoid curve of the second clothoid section, and the radius of curvature of the arc in the arc section are set in advance. As well as making it a constant with a fixed value,
Further, the position of the intersection between the first straight track and the second straight track and the intersection angle between the first straight track and the second straight track are obtained for each calculation of the turning track. The control device for an automatic guided vehicle according to claim 1 or 2 , which calculates a turning track. The turning trajectory calculation unit is
The proportionality constant of the curvature to the curve length in the clothoid curve of the first clothoid section and the proportionality constant of the curvature to the curve length in the clothoid curve of the second clothoid section are constants having predetermined values.
Moreover, the radius of curvature of the arc in the arc section, the position of the intersection of the first straight track and the second straight track, and the intersection angle between the first straight track and the second straight track are the same as that of the turning track. The control device for an automatic guided vehicle according to claim 1 or 2 , wherein a value is acquired for each calculation and the turning trajectory is calculated. The turning trajectory calculation unit calculates the turning trajectory as a function of the mileage from the turning start point and the curvature of the traveling track.
The traveling control unit controls the steering angle according to the traveling distance from the turning start point so that the relationship between the traveling distance and the curvature in the function calculated by the turning trajectory calculation unit is maintained. The control device for an automatic guided vehicle according to any one of claims 1 to 4 , wherein the traveling control is performed. It is a method of controlling the running of an automated guided vehicle based on the detection result of the mark installed on the running surface.
As a turning trajectory when shifting the traveling track from the first straight track extending straight to the second straight track crossing the first straight track and extending straight.
A first clothoid section that is an orbit along a clothoid curve whose curvature increases in proportion to the curve length from the turning start point, which is a point on the first straight orbit where the turning orbit starts, and a first clothoid section.
A second clothoid section that is an orbit along a clothoid curve whose curvature increases in proportion to the curve length from the turning end point, which is a point on the second straight orbit at which the turning orbit ends, and a second clothoid section.
An arc section that is a trajectory along an arc that smoothly connects to the end point of the first clothoid section at the start point of the section and smoothly connects to the second clothoid section at the end point of the section.
The orbit consisting of the three sections is the proportionality constant of the curvature to the curve length in the clothoid curve of the first clothoid section, the proportionality constant of the curvature to the curve length in the clothoid curve of the second clothoid section, and the arc section. Calculated based on the radius of curvature of the arc in the cloth, the distance from the position of the mark to the intersection of the first straight orbit and the second straight orbit, and the intersection angle between the first straight orbit and the second straight orbit.
Based on the distance from the position of the mark to the intersection and the calculation result of the turning trajectory, the turning start distance, which is the distance from the position of the mark to the turning start point, is calculated.
A method for controlling an automatic guided vehicle, which controls traveling so as to travel along the calculated turning track after traveling straight along the first straight track for the turning start distance from the position of the mark . It is a method of controlling the running of an automated guided vehicle based on the information of the surrounding environment map stored in advance.
The information on the traveling environment of the automatic guided vehicle is stored in the peripheral environment map information, including the position information of the virtual guide line indicating the traveling track of the automated guided vehicle and the position information of the virtual mark serving as a road marker point. And
As a turning trajectory when shifting the traveling track from the first straight track extending straight to the second straight track crossing the first straight track and extending straight.
A first clothoid section that is an orbit along a clothoid curve whose curvature increases in proportion to the curve length from the turning start point, which is a point on the first straight orbit where the turning orbit starts, and a first clothoid section.
A second clothoid section that is an orbit along a clothoid curve whose curvature increases in proportion to the curve length from the turning end point, which is a point on the second straight orbit at which the turning orbit ends, and a second clothoid section.
An arc section that is a trajectory along an arc that smoothly connects to the end point of the first clothoid section at the start point of the section and smoothly connects to the second clothoid section at the end point of the section.
The orbit consisting of the three sections is the proportionality constant of the curvature to the curve length in the clothoid curve of the first clothoid section, the proportionality constant of the curvature to the curve length in the clothoid curve of the second clothoid section, and the arc section. Calculated based on the radius of curvature of the arc in the cloth, the distance from the position of the virtual mark to the intersection of the first straight orbit and the second straight orbit, and the intersection angle between the first straight orbit and the second straight orbit. ,
Based on the distance from the position of the virtual mark to the intersection and the calculation result of the turning trajectory, the turning start distance, which is the distance from the position of the virtual mark to the turning start point, is calculated.
A method for controlling an automatic guided vehicle, which controls traveling so as to travel straight along the first straight track for the turning start distance from the position of the virtual mark and then travel along the calculated turning track. The proportionality constant of the curvature to the curve length in the clothoid curve of the first clothoid section, the proportionality constant of the curvature to the curve length in the clothoid curve of the second clothoid section, and the radius of curvature of the arc in the arc section are set in advance. As well as making it a constant with a fixed value,
The position of the intersection between the first straight track and the second straight track, and the intersection angle between the first straight track and the second straight track are obtained for each calculation of the turning track, and the turning The method for controlling an automatic guided vehicle according to claim 6 or 7 , wherein the track is calculated. The proportionality constant of the curvature to the curve length in the clothoid curve of the first clothoid section and the proportionality constant of the curvature to the curve length in the clothoid curve of the second clothoid section are constants having predetermined values.
The radius of curvature of the arc in the arc section, the position of the intersection of the first straight track and the second straight track, and the intersection angle between the first straight track and the second straight track are determined for each calculation of the turning track. The automatic guided vehicle control method according to claim 6 or 7 , wherein the value is acquired in 1 and the calculation of the turning track is performed. The turning trajectory is calculated as a function of the mileage from the turning start point and the curvature of the traveling track.
Any of claims 6 to 9 , wherein the traveling control is performed by controlling the steering angle according to the traveling distance from the turning start point so that the relationship between the traveling distance and the curvature in the function is maintained. The method for controlling an automatic guided vehicle according to item 1.

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