JP7388282B2 - Lifting/tilting device for unmanned transportation - Google Patents

Description

The present invention relates to the transportation of luggage by an automated guided vehicle (AGV), and particularly to a device that can control the elevation and inclination of luggage.

Automatic guided vehicles such as those disclosed in Patent Document 1 are equipped with a motor for lifting and lowering cargo in addition to a driving motor. In the platform stabilizing device disclosed in Patent Document 2, the inclination (progressive direction and lateral direction) of the top plate (base) is controlled by two elevating shafts using servo motors.

In Patent Document 3, although the device is not for unmanned transportation but for a stage, a plurality of linear actuators are used to drive the top plate.

JP2019-204538A JP2019-093981A Japanese Patent Application Publication No. 2005-150615

Automated guided vehicles perform tasks in the following order: (1) lifting cargo, (2) transporting cargo, and (3) unloading cargo. Lifting and unloading requires lifting and lowering, and tilt control of the top plate is required when transporting on uneven floors such as slopes and uneven ground.

Automatic guided vehicles such as those disclosed in Patent Document 1 can perform vertical movement, but cannot control inclination. The platform stabilizing device disclosed in Patent Document 2 can control the inclination of the top plate, but cannot move the top plate up and down.

In Patent Document 3, a plurality of linear actuators are used to drive the top plate, but the applications are different and the methods for preventing the top plate from collapsing are different.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a lifting/tilting device for unmanned transportation that can control both lifting/lowering and tilting.

（ただし、ｘ _１ ～ｘ _４ は天板における第１～第４のアクチュエータの各出力軸の先端部の位置、Ｘ _１ は天板の昇降に対応するモード変数でありＸ _１ ＝（ｘ _１ ＋ｘ _２ ＋ｘ _３ ＋ｘ _４ ）／４で定義され、Ｘ _２ は天板のロール方向（ｘ軸を回転軸とする回転方向）の傾斜に対応するモード変数でありＸ _２ ＝（ｘ _１ －ｘ _２ ＋ｘ _３ －ｘ _４ ）／４で定義され、ロール方向の傾斜Ｓ _ｘ と比例関係Ｘ _２ ＝（ｄ _１２ ／２）Ｓ _ｘ （ｄ _１２ は第１のアクチュエータの出力軸の先端部と第２のアクチュエータの出力軸の先端部の間の距離）にあり、Ｘ _３ は天板のピッチ方向（ｙ軸を回転軸とする回転方向）の傾斜に対応するモード変数でありＸ _３ ＝（ｘ _１ ＋ｘ _２ －ｘ _３ －ｘ _４ ）／４で定義され、ピッチ方向の傾斜Ｓ _ｙ と比例関係Ｘ _３ ＝（ｄ _１３ ／２）Ｓ _ｙ （ｄ _１３ は第１のアクチュエータの出力軸の先端部と第３のアクチュエータの出力軸の先端部の間の距離）にあり、Ｘ _４ は天板の歪みに対応するモード変数であり、Ｈ ^ｃｍｄ は天板の中心高さ指令、Ｓ _ｘ ^ｃｍｄ は天板のロール方向の傾斜指令、Ｓ _ｙ ^ｃｍｄ は天板のピッチ方向の傾斜指令、ｘ _１ ^ｃｍｄ ～ｘ _４ ^ｃｍｄ は第１～第４のアクチュエータの長さ指令）、
前記指令値生成部により変換された第１～第４のアクチュエータの各出力軸の長さ指令と、第１～第４のアクチュエータに対して位置制御を行ったことによる各アクチュエータの出力軸の長さの応答値とに基づいて、第１～第４のアクチュエータの位置制御量を求める位置制御器と、
備えていることを特徴とする。 The lifting/tilting device for unmanned transportation according to claim 1 for solving the above problem,
A base mounted on a movable running body,
first to fourth actuators, each of which is an actuator installed at each of the four corners of the base, and whose output shaft is movable in a direction perpendicular to the installation surface of the actuator with respect to the base;
a top plate disposed to be supported by the tip of each output shaft of the first to fourth actuators;
a position control unit that controls the position of each output shaft of the first to fourth actuators ;
The position control section includes:
Using the following equations (2), (3), (4), and (5), the center height command of the top board and the tilt command of the top board are determined by each output of the first to fourth actuators. a command value generation unit that converts into an axis length command;

(However, x ₁ to x ₄ are the positions of the tips of the output shafts of the first to fourth actuators on the top plate, X ₁ is the mode variable corresponding to the elevation of the top plate, and X ₁ = (x ₁ + x ₂ + x _{3 +} _ _{_} _ _{_} _ _{_} _ _{_} _ ₃ - x _{4 )} / ₄ , _{and is} proportional to the inclination S x in the _roll direction . ), and X ₃ is a mode variable corresponding to the inclination of the top plate in the pitch direction (direction of rotation with the y-axis as the rotation axis), and X 3 ₌ (x ₁ + x ₂ -x ₃ -x _{4 )} /4, and has a _{proportional relationship} with the slope S _{y in} the pitch direction . (distance between the tips of the output shafts of the actuators), X ₄ is a mode variable corresponding to the distortion of the top plate, H ^cmd is the center height command of the top plate, and S _x ^cmd is the roll of the top plate. direction inclination command, S _y ^cmd is a tilt command in the pitch direction of the top plate, x ₁ ^cmd to x ₄ ^cmd are length commands of the first to fourth actuators),
The length command of each output shaft of the first to fourth actuators converted by the command value generation unit and the length of the output shaft of each actuator obtained by performing position control on the first to fourth actuators. a position controller that calculates the position control amount of the first to fourth actuators based on the response value of the
It is characterized by having

（ただし、Ｓ _Ｂｘ ^ｃｍｄ は基台座標系での天板のロール方向の傾斜指令、Ｓ _Ｂｙ ^ｃｍｄ は基台座標系での天板のピッチ方向の傾斜指令、Ｓ _Ｗｘ ^ｃｍｄ は世界座標系での天板のロール方向の傾斜指令、Ｓ _Ｗｙ ^ｃｍｄ は世界座標系での天板のピッチ方向の傾斜指令、Ｓ _Ｗｘ ^Ｂ は前記傾斜センサにより検出された世界座標系での天板のロール方向の傾斜、Ｓ _Ｗｙ ^Ｂ は前記傾斜センサにより検出された世界座標系での天板のピッチ方向の傾斜） The lifting/tilting device for unmanned transportation according to claim 2 has the following features in claim 1:
comprising a tilt sensor installed on the base;
The position control unit includes a coordinate conversion unit that calculates a tilt command in the base coordinate system by calculating the following equation (6), and converts the determined tilt command in the base coordinate system into the command value. It is characterized in that it is a tilting command of the top plate in the generating section.

(However, S _Bx ^cmd is the tilt command in the roll direction of the top board in the base coordinate system, S _By ^cmd is the tilt command in the pitch direction of the top board in the base coordinate system, and S _Wx ^cmd is the tilt command in the pitch direction of the top board in the base coordinate system. S _Wx ^B is the tilt command in the roll direction of the top board in the world coordinate system, S _Wx ^B is the tilt command in the roll direction of the top board in the world coordinate system, which is detected by the tilt sensor. , S _Wy ^B is the tilt in the pitch direction of the top board in the world coordinate system detected by the tilt sensor)

The lifting/tilting device for unmanned transportation according to claim 3 has the following features in claim 1 or 2:
a spherical seat nut provided at the tip of each output shaft of the first to fourth actuators;
a spherical seat support disposed between each of the spherical seat nuts and the top plate;
a screw whose one end is inserted into a portion of the top plate opposite to the location where the spherical seat nut, the spherical seat support, and the spherical seat support are installed;
The present invention is characterized by comprising a top plate detachment prevention device provided at the other end of each of the screws .

(1) According to the invention described in claims 1 to 3 , by controlling the positions of the respective output shafts of the first to fourth actuators, both the elevation and the inclination (in the traveling direction and the lateral direction) of the top plate can be controlled. movements and can be controlled. In addition, since it has a command value generation unit that calculates the actuator length command from the commands for the center height, inclination, and distortion of the top plate, it is possible to obtain the desired center height and inclination of the top plate using general actuator position control.・It is possible to realize distortion.
(2) According to the invention set forth in claim 2, by using the inclination information from the inclination sensor, it is possible to control the inclination of the top plate even when the base mounted on the traveling object is inclined. . For example, even when the base tilts due to running on a slope, the tilt of the top plate can be kept horizontal. Incidentally, the inclination is not limited to zero (horizontal), but can also be set to a constant inclination so that the load on the top plate does not shift when making a curve.
(3) According to the invention set forth in claim 3, since the top plate detachment prevention device is provided, the top plate will not come off from the device.

FIG. 1 is a schematic diagram of a lifting/tilting device according to an embodiment of the present invention. 1 is a perspective view of essential parts of a lifting/tilting device according to a first embodiment of the present invention; FIG. FIG. 4 is an explanatory diagram showing an example of the connection between the actuator output shaft and the top plate in Embodiment 1 of the present invention. 1 shows the configuration of a base and an actuator of a lifting/tilting device according to Embodiment 1 of the present invention, in which (a) is a perspective view, (b) is a front view, (c) is a plan view, and (d) is a side view. 1 is a configuration diagram of the entire system according to Embodiment 1 of the present invention. 1 is a configuration diagram of a controller according to a first embodiment of the present invention. 1 is a block diagram of a control system according to a first embodiment of the present invention. FIG. FIG. 2 is an explanatory diagram showing the correspondence between numbers of automatic guided vehicles (AGV) and actuators in Embodiment 1 of the present invention. FIG. 3 is an explanatory diagram showing the results of an experiment on control performance of Example 1 of the present invention. FIG. 2 is a configuration diagram of the entire system according to Embodiment 2 of the present invention. FIG. 2 is a configuration diagram of a controller according to a second embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the following embodiments.

FIG. 1 shows an outline of the lifting/tilting device (hereinafter also referred to as a 4-axis table) of the present invention. In FIG. 1, a base 20 is mounted and fixed on an automatic guided vehicle (movable traveling body) 10, and each stator of the first to fourth actuators 31 to 34 is mounted at the four corners of the base 20. Fixed.

Each of the output shafts of the first to fourth actuators 31 to 34 has a degree of freedom of movement in the vertical direction, and the tip of each output shaft has a A top plate 40 for loading luggage is provided.

Note that the automatic guided vehicle 10 is equipped with a driving motor, a motor for raising/lowering/tilting the top plate 40 (a motor for driving the actuators 31 to 34), etc., but these are not shown. Further, the actuators 31 to 34 of this embodiment employ a ball screw mechanism as an example.

FIG. 2 shows a perspective view of the entire four-axis table that is mounted on the automatic guided vehicle 10 in FIG. Shown in FIGS. 3 and 4.

In FIG. 3 showing an example of the connection between the output shaft 31a of the first actuator 31 and the top plate 40, a spherical seat nut 51-1 is attached to the tip of the output shaft 31a.

A spherical bearing 52-1 is arranged between the spherical bearing nut 51-1 and the top plate 40.

One end of the full screw (screw) 53-1 is inserted into the part of the top plate 40 that faces the arrangement position of the spherical seat nut 51-1, the spherical seat holder 52-1, and the spherical seat holder 52-1. A seat nut 51-1, a spherical seat support 52-1, and a top plate 40 are connected.

A spherical joint may be used in place of the spherical seat nut 51-1 and the spherical seat support 52-1.

With the connection configuration shown in FIG. 3, even when the top plate 40 is tilted, the output shaft of the actuator can be in contact with the top plate 40, and the tilt of the top plate can be mechanically tolerated.

In addition, the full screw 53-1 prevents the top plate 40 from collapsing, and the other end of the full screw 53-1 is covered with a cap nut 54-1 (a top plate detachment prevention tool). This prevents the top plate 40 from coming off the full screws 53-1.

The second to fourth actuators 32 to 34 also have a connection configuration similar to that shown in FIG. 3.

FIG. 4 shows a configuration in which the top plate 40 in FIG. 2 and the connecting parts between the top plate 40 and the output shafts of each actuator are removed.

In FIG. 4, 21a and 21b are long side frames (aluminum frames) arranged in parallel with each other at a predetermined interval below the base 20, and 22a connects one end of the long side frames 21a and 21b. The short side frame 22b is a short side frame that connects the other ends of the long side frames 21a and 21b.

A rectangular frame is formed by these long side frames 21a, 21b and short side frames 22a, 22b, and a bottom plate 23 made of an aluminum plate is arranged in the rectangular frame.

Vertical frames 24a and 24b are vertically erected at both ends of the short side frame 22a, and vertical frames 24c and 24d are vertically erected at both ends of the short side frame 22b.

A rectangular frame above the base 20 is formed by connecting the upper ends of the vertical frames 24a to 24d to form long side frames 21c, 21d and short side frames 22c, 22d in the same manner as described above.

A side plate 25L made of an aluminum plate is disposed in the frame formed by the short side frames 22a, 22c and the vertical frames 24a, 24b, and an aluminum plate is provided in the frame formed by the short side frames 22b, 22d and the vertical frames 24c, 24d. A side plate 25R is provided.

First to fourth actuators 31 to 34 are respectively disposed at portions corresponding to the four corners of the bottom plate 23, and each stator of the first to fourth actuators 31 to 34 is attached to the bottom plate 23 by bolts (not shown). Fixed.

The tip end side of each output shaft 31a to 34a of the first to fourth actuators 31 to 34 extends upward from a frame formed by the long side frames 21c, 21d and the short side frames 22c, 22d on the upper side of the base 20. It is prominent.

Next, FIG. 5 shows the overall configuration of the system of the lifting/tilting device including the position control section of the present invention. The bold line portions in FIG. 5 indicate mechanical connections. In FIG. 5, 61 is a controller having the function of a position control section. The controller 61 applies thrust to the actuators 31 to 34, and the value of the thrust is determined by feeding back information on the actuator length.

The configuration of the controller 61 is shown in FIG. In FIG. 6, 65 is a command value generation unit, which converts command values for the center height and inclination of the top plate 40 into variables based on kinematics, and calculates an actuator length command x ^cmd .

In the case of a direct drive linear motor, the actuator length response value x ^res is directly measured by a position sensor. When using a transmission mechanism such as a ball screw instead of a direct drive, calculate the actuator length using a constant such as lead. A position control system is constructed by the position controller 70 based on the command value x ^cmd of the actuator length and the response value x ^res , and in the case of a direct drive linear motor, a thrust command f ^ref is applied to the actuators 31 to 34.

Furthermore, when a transmission mechanism such as a ball screw is used, a motor torque command is calculated using a constant such as a lead and is given to the motor.

The simplest method for constructing a control system is to independently control the positions of the output shafts 31a to 34a of the actuators 31 to 34 for each axis. The thrust reference value f ^ref in this control system is calculated as in equation (1) as a general position control system.

However, f ^ref is a thrust reference value, C _p (s) is a position control gain, x ^cmd is a position command value, and x ^res is a position response value. A block diagram of the control system of the first embodiment is shown in FIG. In FIG. 7, 81 in the controller 61 is a subtracter that takes the deviation between the position command value x ^cmd of the output shaft of the actuator and the position response value x ^res of the output shaft, and C _p (s) is the position of the position controller 70. It is a control gain.

82 is a motor driver for each actuator, and f _a ^ref represents the thrust of the output shaft of the actuator. The deviation between the thrust force f _a ^ref and the disturbance f ^ext of the plant (top plate 40, cargo on the top plate, etc.) is taken by a subtractor 83, and the deviation is given a force-position conversion coefficient 1 of a coefficient assigning unit 84. By adding /Ms ² , the position response value x ^res of the output shaft is output.

FIG. 8 shows the positional relationship of each actuator on the top plate 40, and Actuators 1 to 4 in the figure indicate the positions of the first to fourth actuators 31 to 34.

Next, the operations of the command value generation section 65 and the position controller 70 in FIG. 6 will be specifically described using the actuator numbers in FIG. 8. Equations for converting the position and inclination of the actuator can be expressed as equations (2) and (3).

However, mode variable X ₁ corresponds to elevation, X ₂ corresponds to inclination in the roll direction (direction of rotation about the x-axis), and X ₃ corresponds to inclination in the pitch direction (direction of rotation about the y-axis).

The mode variable X ₁ =(x ₁ +x ₂ +x ₃ +x ₄ )/4 is the average of the positions of the output shafts of the four actuators, and corresponds to the position of the center of the top plate 40. Therefore, by controlling _X1 , the position of the center of the top plate can be controlled, and the function of raising and lowering can be provided.

The mode variable X ₂ =(x ₁ −x ₂ +x ₃ −x ₄ )/4 satisfies the slope S _x in the roll direction and the proportional relationship X ₂ =(d ₁₂ /2)S _x . However, d ₁₂ is the distance between actuators 1 and 2 (of each output shaft) in FIG. Similarly, the mode variable X ₃ =(x ₁ +x ₂ −x ₃ −x ₄ )/4 satisfies the slope S _y in the pitch direction and the proportional relationship X ₃ =(d ₁₃ /2)S _y . However, d ₁₃ is the distance between actuators 1 and 3 (of each output shaft) in FIG.

Regarding the transformation of the output axis position x from the mode variable X, the inverse transformation to x can be performed by multiplying X by the inverse matrix T ^-1 .

Using _these relationships ^, _the ^actuator length command x ^cmd = [x ₁ ^cmd , _x ^{2 cmd} , x ₃ ^cmd , x ₄ ^cmd ] can finally be expressed as equations (4) and (5).

The experimental results of position control in Example 1 are shown in FIG. In the experiment shown in Fig. 9, lifting and lowering took 0-4s, tilting in the roll direction (around the x-axis) at 4-8s, tilting in the pitch direction (around the y-axis) at 8-12s, lifting + tilting in the roll direction at 12-16s, and tilting in the roll direction at 16-16s. Elevation and pitch direction tilt control is performed in 20 seconds. In each section, only the desired function changes, and its response follows the command value (the command value curve and the response curve match). From these results, it was confirmed that the desired functions were achieved independently and simultaneously.

In the second embodiment, a function is added to control the tilt even when the automatic guided vehicle 10 is tilted, such as keeping the top plate 40 horizontal even when the automatic guided vehicle 10 is tilted. In the second embodiment, in addition to the system of the first embodiment, a tilt sensor 90 is installed on the base 20 as shown in FIG. 10, and the measured value of the tilt is fed back to the controller 62.

The configuration of the controller 62 is shown in FIG. In FIG. 11, the same parts as those in FIG. 6 are designated by the same reference numerals. Since the controller 61 of the first embodiment assumes running on a horizontal plane, the inclination of the base coordinate system (orthogonal coordinate system with the base as the origin) and the inclination of the world coordinate system (orthogonal coordinate system with the ground as the origin) It is assumed that the slopes are equal. In the second embodiment, since these may be different, a block for coordinate transformation between the world coordinate system and the base coordinate system is added in the command calculation. The tilt sensor 90 installed on the base 20 can measure the tilt of the base in the world coordinate system, making it possible to calculate coordinate transformation.

The difference between the second embodiment (FIG ^. 11) and ^the first embodiment _{(FIG. 6) is that the tilt commands of the base coordinate system [S Bx cmd ,} ^S _By The reason is that a coordinate conversion unit 91 that converts to ^cmd ] has been added.

"(Top tilt command in world coordinate system [S _Wx ^cmd , S _Wy ^cmd ]) = (Base tilt command in world coordinate system [S _Wx ^B , S _Wy ^B ]) + (In base coordinate system The tilt command of the top board [S _Bx ^cmd , S _By ^cmd ])" holds true, but it is transformed to "(The tilt command of the top board in the base coordinate system [S _Bx ^cmd , S _By ^cmd ]) = ( Using the formula: tilt command of the top plate in the world coordinate system [S _Wx ^cmd , S _Wy ^cmd ]) - (tilt of the base plate in the world coordinate system [S _Wx ^B , S _Wy ^B ]), Calculate the tilt command [S _Bx ^cmd , S _By ^cmd ] of the top board in the system. Since the slope needs to be converted to an angle and then the difference is taken, specifically

The tilt command in the base coordinate system can be obtained as follows.

However, in equation (6), S _Bx ^cmd is a tilt command in the roll direction of the top board in the base coordinate system, S _By ^cmd is a tilt command in the pitch direction of the top board in the base coordinate system, and S _Wx ^cmd is S Wx B is the tilt command in the roll direction of the top board in the world coordinate system, S _Wy ^cmd is the tilt command in the pitch direction of the top board in the world coordinate system, and S _Wx ^B is the tilt command in the world coordinate system of the top board detected by the tilt sensor. The inclination in the roll direction, S _Wy ^B is the inclination in the pitch direction of the top plate in the world coordinate system detected by the inclination sensor.

10...Automated guided vehicle 20...Base 21a to 21d...Long side frame 22a to 22d...Short side frame 23...Bottom plate 24a to 24d...Vertical frame 25R, 25L...Side plate 31 to 34...First to fourth actuators 31a to 34a...Output shaft 40...Top plate 51-1~51-4...Spherical bearing nut 52-1~52-4...Spherical bearing 53-1~53-4...Fully threaded 54-1~54-4...Cap nut 61, 62...Controller 65...Command value generation unit 70...Position controller 81, 83...Subtractor 82...Motor driver 84...Coefficient assigning unit 91...Coordinate conversion unit

Claims (3)

A base mounted on a movable running body,
first to fourth actuators, each of which is an actuator installed at each of the four corners of the base, and whose output shaft is movable in a direction perpendicular to the installation surface of the actuator with respect to the base;
a top plate disposed to be supported by the tip of each output shaft of the first to fourth actuators;
a position control unit that controls the position of each output shaft of the first to fourth actuators ;
The position control section includes :
Using the following equations (2), (3), (4), and (5), the center height command of the top board and the tilt command of the top board are determined by each output of the first to fourth actuators. a command value generation unit that converts into an axis length command;

(However, x ₁ to x ₄ are the positions of the tips of the output shafts of the first to fourth actuators on the top plate, X ₁ is the mode variable corresponding to the elevation of the top plate, and X ₁ = (x ₁ + x _{2 + x 3 + _ _ 3 -} x ₄ )/ ₄ , _and is _proportional to the inclination S _x in the roll direction. ), and X ₃ is a mode variable corresponding to the inclination of the top plate in the pitch direction (direction of rotation with the y-axis as the rotation axis), and X ₃ = (x ₁ + x ₂ -x ₃ -x _{4 )} /4, and has _a proportional _relationship with the slope S _{y in} the pitch direction. (distance between the tips of the output shafts of the actuators), X ₄ is a mode variable corresponding to the distortion of the top plate, H ^cmd is the center height command of the top plate, and S _x ^cmd is the roll of the top plate. direction inclination command, S _y ^cmd is a tilt command in the pitch direction of the top plate, x ₁ ^cmd to x ₄ ^cmd are length commands of the first to fourth actuators),
The length command of each output shaft of the first to fourth actuators converted by the command value generation unit and the length of the output shaft of each actuator obtained by performing position control on the first to fourth actuators. a position controller that calculates the position control amount of the first to fourth actuators based on the response value of the
A lifting/tilting device for unmanned transportation. comprising a tilt sensor installed on the base;
The position control unit includes a coordinate conversion unit that calculates a tilt command in the base coordinate system by calculating the following equation (6), and converts the determined tilt command in the base coordinate system into the command value. 2. The lifting/tilting device for unmanned transportation according to claim 1, wherein the generation unit issues a tilt command for the top plate.

(However, S _Bx ^cmd is the tilt command in the roll direction of the top board in the base coordinate system, S _By ^cmd is the tilt command in the pitch direction of the top board in the base coordinate system, and S _Wx ^cmd is the tilt command in the pitch direction of the top board in the base coordinate system. S _Wx ^B is the tilt command in the roll direction of the top board in the world coordinate system, S _Wx ^B is the tilt command in the roll direction of the top board in the world coordinate system, which is detected by the tilt sensor. , S _Wy ^B is the tilt in the pitch direction of the top board in the world coordinate system detected by the tilt sensor) a spherical seat nut provided at the tip of each output shaft of the first to fourth actuators;
a spherical seat support disposed between each of the spherical seat nuts and the top plate;
a screw whose one end is inserted into a portion of the top plate opposite to the location where the spherical seat nut, the spherical seat support, and the spherical seat support are installed;
The lifting/tilting device for unmanned transportation according to claim 1 or 2 , further comprising a top plate separation prevention device provided at the other end of each of the screws.

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