Lifting and tilting device for unmanned transport

Abstract

To provide a lifting and tilting apparatus for unmanned transportation, which can prevent luggage on a to-be-controlled object from slipping at the time of acceleration / deceleration.SOLUTION: A lifting and tilting apparatus for unmanned transportation comprises: a base 20 mounted on a movable unmanned carrier 10; first to fourth actuators 31-34, each of which is arranged at the four corners on the base 20 and is configured to be freely movable in a vertical direction; an acceleration sensor 101 mounted on the base 20; a to-be-controlled object 40 arranged so as to face a tip part of each output shaft of the actuators 31-34; and a position-control unit (controller 60) for creating a tilting command [Sxcmd, Sycmd] for the to-be-controlled object 40 by calculating [-ax / g, -ay / g] using an acceleration ax in an x direction, an acceleration ay in a y direction, and a gravitational acceleration g.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to the transportation of luggage by an automated guided vehicle (hereinafter sometimes referred to as AGV), and more particularly to a device that enables the luggage to be kept horizontal when stationary and prevents slipping during acceleration and deceleration. [Background technology]

[0002] The following technologies are cited as conventional methods for preventing cargo from shifting on transport vehicles. Patent Document 1 invents a device for preventing cargo from shifting on an unmanned transport vehicle, which is equipped with multiple elastic pressing members (rubber tubes 23). Patent Document 2 proposes technology that uses a sensor to detect abnormalities and control the steering system to bring the vehicle to an emergency stop. Patent Document 3 deals with a driving method that compensates for cargo shifting, with the aim of eliminating the need to abnormally stop transport due to minor shifts in the cargo. Patent Document 4 employs a fall prevention body (103) like a housing shown in FIG. 1 of Patent Document 4 in order to prevent cargo from falling during transport. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 1995-285434 A [Patent Document 2] JP 2001-344020 A [Patent Document 3] JP 2009-292560 A [Patent Document 4] JP 2012-158445 A Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 2, an emergency stop is performed when a sensor detects an abnormality, but there is a risk of the load shifting during the emergency stop. Patent Document 1 and Patent Document 4 deal with preventing the load from shifting, but the hardware approach requires the addition of large mechanical elements, which is time-consuming. Patent Document 1 prevents the load from shifting by pressing with a spring (a pressing member (rubber tube 23) made of an elastic body, but the pressing force may change depending on the height of the luggage, and the pressing force of the spring may deteriorate. With the structure of the housing in Patent Document 4, it is difficult to prevent the luggage from slipping inside the housing.

[0005] As described above, prior art approaches include those that do not allow acceleration / deceleration that may cause slippage due to abnormality detection, and those that add mechanical elements, but there are no approaches yet that rely on tilt control of the controlled body, such as the cart or tabletop on which the luggage is carried.

[0006] The present invention is devised to solve the above-mentioned problems, and its object is to provide a lifting and tilting device for unmanned transport that can prevent slippage of cargo on a controlled object during acceleration and deceleration. [Means for solving the problem]

[0007] To solve the above problems First aspect The lifting and tilting device for unmanned transport is A base mounted on a movable traveling body; The actuator is installed at each of the four corners of the base, and the output shaft is The above on the base Installation was done First to fourth actuators configured to be movable in a direction perpendicular to the surface; a controlled body disposed opposite to a tip end of each of the output shafts of the first to fourth actuators; a position control unit that extends the first to fourth actuators by a force sufficiently smaller than the load of the controlled body, and controls the position of each of the output shafts of the first to fourth actuators while controlling the inclination of the controlled body after the tip of the output shaft of each actuator comes into contact with the controlled body and stops. The position control unit is configured to control the tilt command [Sx cmd ,S y cmd The lifting / tilting device for unmanned transport is characterized in that it controls the inclination of a controlled object based on the position of the controlled object.

[0008]

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[0009] (However, S x cmd is the tilt command in the roll direction of the controlled object (rotation direction around the x-axis), S y cmd is the tilt command in the pitch direction of the controlled object (the direction of rotation about the y-axis), x is the acceleration in the x direction, a y is the acceleration in the y direction, and g is the acceleration due to gravity) Second aspect The lifting and tilting device for unmanned transport is The first aspect In An acceleration sensor is provided on the base, The position control unit detects the acceleration measurement value (a x ,a y ) in the above formula (1) x ,a y The present invention is characterized in that it has a command value generating unit that generates a tilt command by substituting the command value into

[0010] Third aspect The lifting and tilting device for unmanned transport is The first aspect In A tilt sensor is provided on the base and uses acceleration as a measurement principle, The position control unit converts the tilt angle measured by the tilt sensor into a value θ x ,θ y Then, tanθ x (=a x / g), tanθ y (=a y / g) in the above formula (1) x / g,a y / g to generate a tilt command.

[0011] Fourth aspect The lifting and tilting device for unmanned transport is The first aspect In an acceleration calculation device that is installed on the movable traveling body and calculates an acceleration from a traveling command of the traveling body; The position control unit converts the acceleration calculated by the acceleration calculation device into a x The present invention is characterized in that it has a command value generating unit that generates a tilt command by substituting the command value into

[0012] Fifth aspect The lifting and tilting device for unmanned transport is The first aspect In an acceleration sensor installed on the base; and an acceleration calculation device installed on the movable running body and configured to calculate an acceleration from a running command of the running body; The position control unit is The acceleration a in the straight line direction calculated by the acceleration calculation device ax and the acceleration a in the x direction measured by the acceleration sensor. x sen and acceleration in the z direction a z sen Then, the slope angle estimate θ is calculated using equation (8). s Seeking

[0013]

number

[0014] Calculate equations (9), (10), and (11) to obtain horizontal acceleration / deceleration a wx , tilt command S from the horizontal plane wx cmd , Tilt command S from the base x cmd The present invention is characterized in that it has a command value generating unit that generates a tilt command by calculating

[0015]

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[0016]

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[0017]

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[0018] Sixth aspect The lifting and tilting device for unmanned transport is The first aspect In a tilt sensor that measures acceleration and is installed on the base; and an acceleration calculation device that is installed on the movable running body and calculates acceleration from a running command of the running body; The position control unit is The tilt angle θ measured by the tilt sensor sen From the acceleration in the x direction, a x sen and acceleration in the z direction a z sen is calculated as equation (12),

[0019]

number

[0020] (where g is the acceleration due to gravity) The acceleration a in the straight line direction calculated by the acceleration calculation device ax and the acceleration a in the x direction calculated by the above equation (12) x sen and acceleration in the z direction a z sen Then, the slope angle estimate θ is calculated using equation (8). s Seeking

[0021]

number

[0022] Calculate equations (9), (10), and (11) to obtain horizontal acceleration / deceleration a wx , tilt command S from the horizontal planewx cmd , Tilt command S from the base x cmd The present invention is characterized in that it has a command value generating unit that generates a tilt command by calculating

[0023]

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[0024]

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[0025]

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[0026] Seventh aspect The lifting and tilting device for unmanned transport is The first to sixth aspects Either one of t In The position control unit is The present invention is characterized in that it has a variable conversion unit that converts the center height command of the controlled body and the tilt command of the tabletop into length commands of the output shafts of the first to fourth actuators using the following equations (2), (3), (4), and (5).

[0027]

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[0028]

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[0029]

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[0030]

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[0031] (where x1 to x4 are the positions of the tips of the output shafts of the first to fourth actuators in the controlled body, X1 is a mode variable corresponding to the elevation of the controlled body and is defined as X1 = (x1 + x2 + x3 + x4) / 4, X2 is a mode variable corresponding to the inclination of the controlled body in the roll direction (the direction of rotation about the x-axis) and is defined as X2 = (x1-x2 + x3-x4) / 4, and the inclination in the roll direction S x and the proportional relationship X2=(d 12 / 2)S x (d 12 is the distance between the tip of the output shaft of the first actuator and the tip of the output shaft of the second actuator), X3 is a mode variable corresponding to the tilt of the controlled object in the pitch direction (the direction of rotation about the y-axis) and is defined as X3 = (x1 + x2 - x3 - x4) / 4, and the tilt in the pitch direction S y and the proportional relationship X3=(d 13 / 2)S y (d 13 is the distance between the tip of the output shaft of the first actuator and the tip of the output shaft of the third actuator), X4 is a modal variable corresponding to the strain of the controlled body, and H cmd is the center height command of the controlled object, S x cmd is the tilt command in the roll direction of the controlled object, S y cmd is the tilt command in the pitch direction of the controlled object, x1 cmd ~x4 cmd is the length command for the 1st to 4th actuators) Eighth aspect The lifting and tilting device for unmanned transport is The first to seventh aspects Either one of t In The position control unit calculates position command values ​​x cmd , the position response value x of the output shaft of each actuator obtained by performing position control on the first to fourth actuators res , calculate the thrust reference value f of the output shaft of each actuator by calculating equation (6) based on the position control gain Cp(s). ref Calculate the thrust reference value f refThe present invention is characterized by having a position controller that outputs the signal to the drive motors of the first to fourth actuators.

[0032]

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[0033] (1) The first to eighth aspects According to the invention, it is possible to prevent slippage of the luggage on the controlled body during acceleration and deceleration. Since the control is performed to bring the sliding force itself close to zero, it is possible to prevent slippage even under physical conditions where the friction coefficient of the luggage on the controlled body is close to zero and the luggage is prone to slippage. (2) The third aspect According to the invention, since the tilt information is fed back from the tilt sensor, two functions, namely anti-slip control when there is acceleration / deceleration on a horizontal plane, and horizontal maintenance control when at a stationary (or constant speed) state, can be realized with the same control device. (3) The fourth aspect According to the invention, the acceleration is calculated from the travel command of the traveling body (AGV) and fed back, so that slip prevention control can be realized without adding an acceleration sensor or tilt sensor. (4) The fifth and sixth aspects According to this invention, it is possible to realize horizontal control when stationary or moving at a constant speed on a slope, and anti-slip control when accelerating or decelerating. [Brief description of the drawings]

[0034] [Figure 1] 1 is a schematic diagram of a lifting / tilting device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an explanatory diagram showing an example of a connection between an actuator output shaft and a controlled object in an embodiment of the present invention. [Diagram 3] FIG. 1 is a diagram showing the overall configuration of a system according to a first embodiment of the present invention. [Figure 4] FIG. 2 is a configuration diagram of a controller according to the first embodiment of the present invention. [Diagram 5] FIG. 2 is a block diagram of a position control system according to the first embodiment of the present invention. [Figure 6] FIG. 2 is an explanatory diagram showing the correspondence between numbers of automatic guided vehicles (AGVs) and actuators in the first embodiment of the present invention. [Figure 7] FIG. 11 is a diagram showing the overall configuration of a system according to a second embodiment of the present invention. [Figure 8] FIG. 11 is a configuration diagram of a controller according to a second embodiment of the present invention. [Figure 9] FIG. 4 is an explanatory diagram showing the force acting on a controlled object during acceleration. [Figure 10] FIG. 11 is a diagram showing the overall configuration of a system according to a third embodiment of the present invention. [Figure 11] FIG. 11 is a configuration diagram of a controller according to a third embodiment of the present invention. [Figure 12] FIG. 11 is a diagram showing the overall configuration of a system according to a fourth embodiment of the present invention. [Figure 13] FIG. 11 is a configuration diagram of a controller according to a fourth embodiment of the present invention. [Figure 14] FIG. 4 is an explanatory diagram of acceleration during running on a slope. [Figure 15] FIG. 13 is a diagram showing the overall configuration of a system according to a fifth embodiment of the present invention. [Figure 16] FIG. 13 is a configuration diagram of a controller according to a fifth embodiment of the present invention. [Figure 17] FIG. 2 is a diagram showing an experimental apparatus for verifying the effect of the present invention. [Figure 18] FIG. 11 is a waveform diagram of time-series data obtained when a verification experiment was carried out on Example 2 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiment example.

[0036] An overview of the lifting / tilting device (hereinafter sometimes referred to as a four-axis lifter) of the present invention is shown in Fig. 1. In Fig. 1, a base 20 is mounted and fixed on an unmanned guided vehicle (a movable traveling body) 10, and stators of first to fourth actuators 31 to 34 equipped with servo motors are fixed to the four corners of the base 20.

[0037] The output shafts of the first to fourth actuators 31 to 34 are each oriented in the vertical direction. (As shown in FIG. 1, the direction is perpendicular to the surface on which the first to fourth actuators 31 to 34 are placed on the base 20) This vertical movement is achieved by the action of a servo motor which moves the output shaft (shown as a) of the actuator in the vertical direction.

[0038] A controlled object 40 such as a top plate, a dolly, a cage dolly, etc. for carrying luggage is disposed at the tip of each output shaft of the first to fourth actuators 31 to 34 so as to be supported by the tip. In the following embodiment, the controlled object 40 is illustrated in the form of a top plate.

[0039] In addition, the actuators 31 to 34 in this embodiment employ a ball screw mechanism as an example.

[0040] Of the actuators 31 to , an example of connection between the output shaft 31a of the first actuator 31 and the controlled body 40 is shown in Fig. 2. In Fig. 2, a spherical seat nut 51-1 is attached to the tip of the output shaft 31a.

[0041] A spherical seat receiver 52-1 is disposed between the spherical seat nut 51-1 and the controlled body 40.

[0042] One end of a full thread (screw) 53-1 is inserted into a portion of the controlled body 40 opposite the arrangement positions of the spherical seat nut 51-1, the spherical seat holder 52-1, and the spherical seat holder 52-1, connecting the spherical seat nut 51-1, the spherical seat holder 52-1, and the controlled body 40.

[0043] A spherical joint may be used in place of the spherical seat nut 51-1 and the spherical seat receiver 52-1.

[0044] 2, even if the controlled object 40 tilts, the output shaft of the actuator and the controlled object 40 can come into contact with each other, and the tilt of the controlled object can be mechanically tolerated.

[0045] In addition, the full thread 53-1 prevents the controlled body 40 from collapsing, and the other end of the full thread 53-1 is covered with a cap nut 54-1 (a top plate removal prevention device), which prevents the controlled body 40 from coming off the full thread 53-1.

[0046] The second to fourth actuators 32 to 34 have the same connection configuration as that shown in FIG.

[0047] In order to prevent slippage of the load (50) on the controlled body 40 when the traveling body accelerates or decelerates, the present invention performs control to reduce the slippage itself to near zero, and the principle thereof will be described with reference to Fig. 3. Fig. 3 shows the forces acting on the automated guided vehicle 10 in Fig. 1 when accelerating or decelerating while the automated guided vehicle 10 is traveling on a horizontal plane, where (a) shows the case where the controlled body 40 is not tilted and (b) shows the case where the controlled body 40 is tilted.

[0048] 3, the automated guided vehicle 10 and base 20 in FIG. 1 are illustrated in a simplified manner, 30 is an actuator (31 to 34), 50 is a load on the controlled body 40, and m is the mass of the load 50.

[0049] In FIG. 3, by making the inclination of the controlled body 40 perpendicular to the resultant force of inertial forces ma and mg, the force in the sliding direction parallel to the surface of the controlled body can be made zero, preventing slippage. An illustration explaining this principle is shown in FIG. 13, where m represents the mass of the luggage. By making the inclination perpendicular to the resultant force of inertial forces ma and mg in this way, the sliding force itself becomes zero as shown in FIG. 3(b), so ideally there will be no slippage even if the coefficient of friction between the luggage 50 and the controlled body 40 is nearly zero. Sliding force F s is given by equation (7) using the inertial force ma, gravity mg, tilt angle θ, and acceleration a.

[0050]

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[0051] In order to make the sliding force zero, tan θ=-a / g should be used. Therefore, the tilt command [S x cmd ,S y cmd ] is given mathematically as equation (1).

[0052]

number

[0053] where a x is the running acceleration in the x direction, a y is the acceleration in the y direction, g is the gravitational acceleration, and S x cmd is the tilt command in the roll direction (rotation direction about the x-axis) of the controlled body 40, S y cmd is a tilt command in the pitch direction (rotation direction about the y-axis) of the controlled body 40.

[0054] Therefore, in the position control unit of the present invention, the tilt command [S x cmd ,S y cmd ], the inclination of the controlled object is controlled as in the following embodiment. EXAMPLES

[0055] The overall system configuration of the lifting / tilting device in Example 1, including the position control unit of the present invention, is shown in Fig. 4. In Fig. 4, the same parts as in Fig. 1 are designated by the same reference numerals. The thick lines in Fig. 4 indicate mechanical connections. In Fig. 4, 60 is a controller equipped with the function of a position control unit. The controller 60 applies thrust to the actuators 31-34, and the thrust value is determined by feeding back information on the actuator lengths and the acceleration measurement value of the acceleration sensor 101 provided on the base 20.

[0056] The configuration of the controller 60 is shown in Fig. 5. In Fig. 5, 61 indicates a measurement value a of acceleration of the acceleration sensor 101 provided on the base 20. x ,ay a in Eq. (1) x ,a y and the tilt command [S x cmd ,S y cmd ] is a command value generating unit that generates

[0057]

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[0058] 66 is the center height command H cmd and the tilt command [S x cmd ,S y cmd ] is calculated by using the equations (2) to (5) described later to obtain the length command (position command value) x cmd This is the variable transformation section that transforms

[0059] 70 is a position command value x of each output shaft of the actuator cmd and the position response value x of the output shaft of each actuator obtained by performing position control on the first to fourth actuators (31 to 34). res Based on the position control gain (described later), the thrust reference value f of the output shaft of each actuator is calculated using equation (6) (described later). ref This is a position controller that calculates:

[0060] Thrust reference value f of the position controller 70 ref are output to the drive motors of the first to fourth actuators 31 to .

[0061] In Figure 5, the response value of the actuator length x res In the case of a direct drive linear motor, the actuator length is measured directly by a position sensor. In the case of a transmission mechanism such as a ball screw instead of a direct drive, the actuator length is calculated using a constant such as lead. The actuator length command value x cmd and the response value x resBased on this, a position control system is constructed by the position controller 70, and in the case of a direct drive linear motor, a thrust command f ref is applied to the actuators 31 to 34.

[0062] When a transmission mechanism such as a ball screw is used, a motor torque command is calculated using a constant such as lead and is given to the motor.

[0063] The simplest method for configuring a control system is to independently control the positions of the output shafts 31a to a of the actuators 31 to .

[0064] Here, the positional relationship of each actuator in the controlled object 40 is shown in Fig. 6. In Fig. 6, Actuators 1 to 4 indicate the positions of the first to fourth actuators 31 to 34, and the x-axis is the traveling direction of the AGV. The equations for converting the position and inclination of the actuators can be expressed as equations (2) and (3).

[0065]

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[0066]

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[0067] Here, the mode variable X1 corresponds to ascent and descent, X2 corresponds to tilt in the roll direction (rotation direction about the x-axis), and X3 corresponds to tilt in the pitch direction (rotation direction about the y-axis).

[0068] The mode variable X1 = (x1 + x2 + x3 + x4) / 4 is the average of the positions of the output shafts of the four actuators, and corresponds to the central position of the controlled object 40. Therefore, by controlling X1, the central position of the controlled object can be controlled, and it can be given the function of raising and lowering.

[0069] The mode variable X2=(x1-x2+x3-x4) / 4 is the inclination S in the roll direction. xand the proportional relationship X2=(d 12 / 2)S x where d satisfies 12 is the distance between actuators 1 and 2 (of each output shaft) in FIG. 6. Similarly, the mode variable X3=(x1+x2-x3-x4) / 4 is the inclination S in the pitch direction. y and the proportional relationship X3=(d 13 / 2)S y where d satisfies 13 is the distance between actuators 1 and 3 (of their respective output shafts) in FIG.

[0070] To convert the mode variable X to the output shaft position x, use the inverse matrix T -1 It can be converted back to x by multiplying it by X.

[0071] Using these relationships, the center height / tilt command [H cmd ,S x cmd ,S y cmd ] to actuator length command x cmd =[x1 cmd ,x2 cmd ,x3 cmd ,x4 cmd The variable transformation up to ] can finally be expressed as equations (4) and (5).

[0072]

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[0073]

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[0074] The thrust reference value f in this control system ref is calculated as shown in equation (6) for a general position control system.

[0075]

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[0076] However, f ref is the thrust reference value, C p (s) is the position control gain, x cmd is the position command value, x res is a position response value. A block diagram of the control system of the first embodiment is shown in FIG. 7. In FIG. 7, 81 in the position controller 70 is a position command value x of the output shaft of the actuator. cmd and the output shaft position response value x res It is a subtractor that takes the deviation of C p (s) is the position control gain of the position controller 70.

[0077] 82 is a motor driver for each actuator, and f a ref represents the thrust of the actuator output shaft. a ref and the disturbance f of the plant (the controlled body 40 and the luggage on the controlled body, etc.) ext The deviation from the force is taken by the subtractor 83, and the deviation is multiplied by the force-position conversion coefficient 1 / Ms 2 is applied to the output shaft position response value x res is output (where M represents the inertia of the actuator).

[0078] In addition to the tilt control described above, the position control unit of the present invention extends the first to fourth actuators 31 to 34 with a force sufficiently small compared to the load of the controlled body 40, and after the tip of the output shaft of each actuator comes into contact with the controlled body and stops, controls the position of each output shaft of the first to fourth actuators while controlling the tilt of the controlled body. EXAMPLES

[0079] The overall system configuration of the lifting / tilting device in the second embodiment is shown in Fig. 8. In Fig. 8, the same parts as in Fig. 4 are denoted by the same reference numerals. The difference between Fig. 8 and Fig. 4 is that instead of the acceleration sensor 101, a tilt sensor 102 that measures acceleration is provided on the base 20, and the value of the thrust applied by the controller 60 to the actuators 31 to 34 is calculated based on information on the actuator lengths and the sensor output (θ) of the tilt sensor 102. x ,θ y ) is fed back to determine the target value.

[0080] The controller 60 in the system of Fig. 8 is configured as shown in Fig. 9. The inclination sensor 102, which uses acceleration as a measurement principle, outputs the inclination angle when the vehicle is stationary. However, when the vehicle is traveling on a horizontal plane with acceleration and deceleration as shown in Fig. 3, the inclination angle is also measured by the force of gravity m g and the inertial force m a and gravity m g Outputs the included angle with the resultant force of .

[0081] Sensor output θ of the tilt sensor 102 x ,θ y is the inclination S of the base input to the command value generating unit 62 in FIG. x ,S y From Figure 3, [tanθ x , tan θ y ) is [a x / g,a y / g] is equal to (a x is the running acceleration in the x direction, a y is the acceleration in the y direction, and g is the acceleration due to gravity).

[0082] Therefore, the command value generating unit 62 calculates [tanθ x , tan θ y ) in (1) x / g,a y / g] to obtain the tilt command value [S x cmd ,S y cmd ] is obtained.

[0083]

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[0084] The variable conversion section 66 and the position controller 70 in FIG. 9 are configured in the same manner as those in FIG. 5 of the first embodiment.

[0085] According to the second embodiment, since the tilt sensor 102 is used when implementing horizontal control, there is an advantage that no additional sensor is required.

[0086] In addition, since the system is configured to feed back tilt information from the tilt sensor, the same control device can achieve two functions: anti-slip control when there is acceleration / deceleration on a horizontal plane, and horizontal maintenance control when the vehicle is stationary (or at a constant speed). EXAMPLES

[0087] The overall system configuration of the lifting / tilting device in the third embodiment is shown in Fig. 10. In Fig. 10, the same parts as in Fig. 4 are designated by the same reference numerals. What differs from Fig. 4 in that, instead of the acceleration sensor 101, an acceleration calculation device 103 that calculates acceleration from a travel command for the AGV is provided in the automatic guided vehicle 10 (AGV), and the values ​​of the thrust force that the controller 60 applies to the actuators 31-34 are determined by feeding back information on the actuator lengths and the acceleration calculated by the acceleration calculation device 103.

[0088] The controller 60 in the system of Fig. 10 is configured as shown in Fig. 11. The command value generating unit 63 in Fig. 11 receives the acceleration a calculated from the AGV travel command from the acceleration calculation device 103. ax ,a ay is input, but for simplicity, only the acceleration in the straight line is considered, and the acceleration in the straight line a ax a in Eq. (1) x By substituting the tilt command value [S x cmd ,S y cmd ] is obtained.

[0089]

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[0090] The variable conversion section 66 and the position controller 70 in FIG. 11 are configured in the same manner as those in FIG. 5 of the first embodiment.

[0091] According to the third embodiment, the acceleration is calculated from the travel command of the traveling body (AGV) and fed back, so that slip prevention control can be realized without adding an acceleration sensor or tilt sensor. EXAMPLES

[0092] The overall system configuration of the lifting / tilting device in the fourth embodiment is shown in Fig. 12. In Fig. 12, the same parts as in Fig. 4 are designated by the same reference numerals. What differs from Fig. 4 in that, in addition to the acceleration sensor 101, an acceleration calculation device 103 that calculates acceleration from a travel command for the AGV is provided in the automatic guided vehicle 10 (AGV), and the values ​​of the thrust forces that the controller 60 applies to the actuators 31-34 are determined by feeding back information on the actuator lengths, the acceleration measurement values ​​of the acceleration sensor 101, and the acceleration calculated by the acceleration calculation device 103.

[0093] The controller 60 in the system of Fig. 12 is configured as shown in Fig. 13. The command value generating unit 64 in Fig. 13 receives the acceleration a x ,a y and the acceleration a calculated from the AGV travel command from the acceleration calculation device 103. ax ,a ay is input, and the tilt command [S x cmd ,S y cmd ] is generated.

[0094] First, in order to use the acceleration calculated from the travel command of the AGV, it is assumed that the AGV travels only in a straight line, as in the third embodiment. The acceleration sensor 101 is a MEMS (Micro Electro Mechanical Systems) sensor or the like that outputs a signal including the acceleration of gravity.

[0095] When on a slope, the procedure is to first accurately determine the inclination angle and perform horizontal control, and then implement anti-slip control by feeding back horizontal acceleration and deceleration.

[0096] First, the derivation of the inclination angle will be described with reference to an explanatory diagram of acceleration during travel on a slope shown in Fig. 14. Fig. 14 shows a simplified illustration of the automated guided vehicle 10, base 20, acceleration sensor 101, and acceleration calculation device 103 shown in Fig. 1, in which 30 indicates actuators (31 to 34) and 50 indicates a load on the controlled object 40.

[0097] θ slope is the slope angle, a ax is the acceleration in the straight line calculated from the travel command of the AGV (output from the acceleration calculation device 103), a gx ,a gz are the x-axis and z-axis outputs of the acceleration sensor 101, and g is the gravitational acceleration included in the acceleration sensor output.

[0098] When the vehicle is stationary or moving at a constant speed, as shown in Figure 14(a), the output of the acceleration sensor is a gz The angle θ between g and the inclination sensor output angle is the inclination angle θ of the slope slope On the other hand, in the case of acceleration / deceleration as shown in Fig. 14(b), the acceleration in the straight line a ax affects the acceleration sensor output a gx The angle θ is the inclination angle of the slope slope The measured acceleration of each axis is a x sen ,a z sen Then, from Fig. 14(b), the estimated slope angle θ s can be calculated using equation (8).

[0099]

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[0100] Therefore, horizontal control can be realized by using the tilt angle calculated by equation (8) as the command value.

[0101] Next, we will explain the slip prevention control during acceleration and deceleration. wx can be calculated using equation (9).

[0102]

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[0103] The rest is the same as the anti-slip control during horizontal control on a horizontal plane, and the tilt command S from the horizontal plane is wx cmd is expressed as (10), and the tilt command S x cmd can be calculated using equation (11).

[0104]

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[0105]

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[0106] Therefore, the command value generating unit 64 in FIG. 13 calculates the above-mentioned expressions (8) to (11) to obtain the tilt command value [S x cmd ,S y cmd ] is generated and input to the variable conversion unit 66.

[0107] The variable conversion section 66 and the position controller 70 in FIG. 13 are configured in the same manner as those in FIG. 5 of the first embodiment.

[0108] According to the fourth embodiment, horizontal control can be achieved when the vehicle is stationary or moving at a constant speed on a slope, and anti-slip control can be achieved when the vehicle is accelerating or decelerating. EXAMPLES

[0109] The overall system configuration of the lifting / tilting device in the fifth embodiment is shown in Fig. 15. In Fig. 15, the same parts as in Fig. 4 are denoted by the same reference numerals. The differences between Fig. 15 and Fig. 4 are that instead of the acceleration sensor 101, an inclination sensor 102 that measures acceleration is installed on the base 20, an acceleration calculation device 103 that calculates acceleration from a travel command for the AGV is installed on the automatic guided vehicle 10 (AGV), and the value of the thrust applied to the actuators 31 to 34 by the controller 60 is calculated based on information on the actuator length and the sensor output (θ) of the inclination sensor 102. x ,θ y ) and the acceleration calculated by acceleration calculation device 103 are fed back to determine the acceleration.

[0110] The controller 60 in the system of Fig. 15 is configured as shown in Fig. 16. The command value generating unit 65 of Fig. 16 includes a base tilt S x ,S y (The sensor output θ of the tilt sensor 102 x ,θ y ) and the acceleration a calculated from the AGV travel command from the acceleration calculation device 103 ax ,a ay is input, and the tilt command value [S x cmd ,S y cmd ] is generated.

[0111] As in the third and fourth embodiments, the acceleration in the straight line direction only is taken into consideration, and the inclination sensor output θ sen Acceleration in the x direction from x sen and the acceleration in the z direction a z sen can be obtained as equation (12).

[0112]

number

[0113] Thereafter, in the same manner as in the fourth embodiment, equations (8) to (11) are calculated to generate a tilt command, which is input to the variable conversion unit 66. The variable conversion unit 66 and the position controller 70 in FIG. 16 are configured in the same manner as those in FIG. 5 of the first embodiment.

[0114] According to the fifth embodiment, horizontal control can be achieved when the vehicle is stationary or moving at a constant speed on a slope, and anti-slip control can be achieved when the vehicle is accelerating or decelerating.

[0115] <Experimental Verification (Example 2)> Here, the device of the second embodiment was applied, and an experiment was carried out using the experimental device of FIG. 17 in which a tilt command was given when the automated guided vehicle 10 (AGV) accelerated with a load placed on the controlled object 40 .

[0116] 17, a slippery load 110 is placed on the controlled object 40 (top plate), and the base 20, actuators 31 to 34, etc. are shown in a simplified form.

[0117] The time series data of the experiment is shown in Fig. 18. In Fig. 18, the acceleration and deceleration of the AGV are 0.7 m / s 2 Accelerates to 3.5m / s for 5 seconds 2 It slows down for one second and then stops.

[0118] FIG. 18(a) shows the tilt command and tilt response, and FIG. 18(b) shows the AGV's speed command. It can be seen that the tilt command changes during acceleration and deceleration, and the tilt response value follows suit. [Explanation of symbols]

[0119] 10…Automated guided vehicle 20…Foundation 31-34: 1st to 4th actuators 31a~34a...Output shaft 40...Controlled object 50…Luggage 51-1~51-4...Spherical seat nut 52-1~52-4…Spherical bearing 53-1~53-4...Full thread 54-1~54-4...Cap nuts 60…Controller 61 to 65: Command value generation section 66…Variable conversion section 70...Position controller 81, 83…Subtractor 82...Motor driver 84...Coefficient assignment section 101...Accelerometer 102...Tilt sensor 103...Acceleration calculation device

Claims

1. A base mounted on a movable traveling body; First to fourth actuators are respectively installed at the four corners of the base, and the output shafts of the actuators are configured to be movable in a direction perpendicular to the surface on the base where the actuators are installed; a controlled body disposed opposite to a tip end of each of the output shafts of the first to fourth actuators; a position control unit that extends the first to fourth actuators by a force that is sufficiently smaller than the load of the controlled body, and controls the position of each of the output shafts of the first to fourth actuators while controlling the inclination of the controlled body after the tip of the output shaft of each actuator comes into contact with the controlled body and stops. The position control unit 100 calculates a tilt command [S x cmd , S y cmd ] to control the tilt of the controlled object based on [0010] (However, S x cmd is the tilt command in the roll direction of the controlled object (the direction of rotation about the x-axis), S y cmd is the tilt command in the pitch direction (rotation direction about the y-axis) of the controlled object, x is the acceleration in the x direction, a y is the acceleration in the y direction, and g is the acceleration of gravity) an acceleration sensor installed on the base; and an acceleration calculation device installed on the movable running body and configured to calculate an acceleration from a running command of the running body; The position control unit is The acceleration a in the straight line direction calculated by the acceleration calculation device ax and the acceleration a in the x direction measured by the acceleration sensor. x sen and acceleration in the z direction a z sen Then, the slope angle estimate θ is calculated by the formula (8). s Seeking [0080] The horizontal acceleration / deceleration a is calculated by the equations (9), (10), and (11). wx , tilt command S from the horizontal plane wx cmd , tilt command S from the base x cmd a command value generating unit that generates a tilt command by calculating the command value. [0090] [0010] ##EQU00011##

2. A base mounted on a movable traveling body; First to fourth actuators are respectively installed at the four corners of the base, and the output shafts of the actuators are configured to be movable in a direction perpendicular to the surface on the base where the actuators are installed; a controlled body disposed opposite to a tip end of each of the output shafts of the first to fourth actuators; a position control unit that extends the first to fourth actuators by a force that is sufficiently smaller than the load of the controlled body, and controls the position of each of the output shafts of the first to fourth actuators while controlling the inclination of the controlled body after the tip of the output shaft of each actuator comes into contact with the controlled body and stops. The position control unit 100 calculates a tilt command [S x cmd , S y cmd ] to control the tilt of the controlled object based on [0010] (However, S x cmd is the tilt command in the roll direction of the controlled object (the direction of rotation about the x-axis), S y cmd is the tilt command in the pitch direction (rotation direction about the y-axis) of the controlled object, x is the acceleration in the x direction, a y is the acceleration in the y direction, and g is the acceleration of gravity) a tilt sensor that measures acceleration and is installed on the base; and an acceleration calculation device that is installed on the movable running body and calculates acceleration from a running command of the running body; The position control unit is The tilt angle θ measured by the tilt sensor sen From the acceleration in the x direction, a x sen and acceleration in the z direction a z sen is calculated as equation (12), ##EQU00012## (where g is the acceleration due to gravity) The acceleration a in the straight line direction calculated by the acceleration calculation device ax and the acceleration a in the x direction calculated by the above equation (12) x sen and acceleration in the z direction a z sen Then, the slope angle estimate θ is calculated by the formula (8). s Seeking [0080] The horizontal acceleration / deceleration a is calculated by the equations (9), (10), and (11). wx , tilt command S from the horizontal plane wx cmd , tilt command S from the base x cmd a command value generating unit that generates a tilt command by calculating the command value. [0090] [0089] ##EQU00011##

3. The position control unit is The lifting and tilting device for an unmanned transporter according to claim 1 or 2, further comprising a variable conversion unit that converts a center height command of the controlled body and a tilt command of the top plate into length commands of the output shafts of the first to fourth actuators using the following equations (2), (3), (4), and (5): [0025] [0030] [0045] [0050] (However, x 1 ~x 4 are the positions of the tips of the output shafts of the first to fourth actuators in the controlled body, and X 1 is a mode variable corresponding to the elevation of the controlled object, and X 1 = (x 1 +x 2 +x 3 +x 4 ) / 4, and X 2 is a mode variable corresponding to the tilt of the controlled object in the roll direction (the direction of rotation about the x-axis) and X 2 = (x 1 -x 2 +x 3 -x 4 ) / 4, and the roll direction tilt S x and proportional relationship X 2 = (d 12 / 2) S x (d 12 is the distance between the tip of the output shaft of the first actuator and the tip of the output shaft of the second actuator), and X 3 is a mode variable corresponding to the tilt of the controlled object in the pitch direction (the direction of rotation about the y-axis) and X 3 = (x 1 +x 2 -x 3 -x 4 ) / 4, and the pitch direction tilt S y and proportional relationship X 3 = (d 13 / 2) S y (d 13 is the distance between the tip of the output shaft of the first actuator and the tip of the output shaft of the third actuator), and X 4 is a modal variable corresponding to the distortion of the controlled object, and H cmd is the center height command of the controlled object, S x cmd is the tilt command in the roll direction of the controlled object, S y cmd is the tilt command in the pitch direction of the controlled object, x 1 cmd ~x 4 cmd are the length commands for the first to fourth actuators)

4. The position control unit controls the position command value x of each output shaft of the first to fourth actuators. cmd , the position response value x of the output shaft of each actuator obtained by performing position control on the first to fourth actuators res , the thrust reference value f of the output shaft of each actuator is calculated based on the position control gain Cp(s) using the formula (6). ref and calculating the thrust reference value f ref 4. The lifting and tilting device for unmanned transport according to claim 1, further comprising a position controller which outputs the above-mentioned to drive motors of the first to fourth actuators. [006]

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