JP6872465B2 - Control method of cargo carrier - Google Patents

Description

The present invention relates to a method for controlling a cargo handling machine that smoothly cuts the ground by using an encoder in controlling the raising and lowering of the cargo handling machine when the weight of the cargo handling object is not constant.

In Patent Document 1, the bending motion of the arm before ground cutting is detected by an acceleration sensor arranged in the middle of the arm to control ground cutting.

However, the bending motion of the arm may move in a swaying manner, and the calculated ascending / descending command value is not smooth, and there are times when smooth ground cutting cannot be controlled.

In Cited Document 2, a speed detector detects the moment of ground cutting at the speed of the point of effort. However, since it is detected immediately after the ground cutting, it is controlled after the tip of the arm jumps up a little, and the amount of jumping up is larger than that of Cited Document 1, and it is difficult to operate.

For example, the speed detector of Cited Document 2 can be converted into speed by distance and time using an encoder. Although the present invention uses an encoder, it is not used to detect speed.

Japanese Unexamined Patent Publication No. 2015-129045 Japanese Unexamined Patent Publication No. 2000-169100

The problem to be solved is that the acceleration detector detects the shaking of the arm in the control using the deflection of the arm before the ground cutting, and the ground cutting control cannot be performed smoothly. In addition, in the control that detects immediately after the ground cutting, the amount of bounce is large.

In the present invention, the predicted movement distance of the force point between the gripping of the cargo handling object and the ground cutting is set in advance by using the encoder, and the limit value of the operation unit electric signal is lowered as the force point approaches the ground cutting prediction point. The most important feature is to reduce the ground cutting control power just before the ground cutting.

The control method of the cargo handling machine of the present invention has an advantage that smooth ground cutting with a suppressed amount of jumping can be performed even when the weight of the cargo handling object is unknown.

FIG. 1 is an overall view of a cargo handling machine. (Example 1) FIG. 2 is a conceptual diagram showing control and configuration. (Example 1) FIG. 3 is a graph of the electric signal of the operation unit and the magnitude of the force on the lever. (Example 1) FIG. 4 is a graph of the encoder movement distance and the limit value of the operation unit electric signal. (Example 1) FIG. 5 is a graph of the movement distance of the encoder and the command force of the drive source. (Example 1) FIG. 6 is a graph of elapsed time and drive source command force. (Example 1) FIG. 7 is a control flow diagram. (Example 1)

Using an encoder, the predicted movement distance of the force point between gripping the cargo and cutting the ground is set in advance, and as the force point approaches the predicted ground cutting point, the limit value of the electric signal of the operation unit is lowered to control the ground cutting. Achieves smooth ground cutting with reduced force and reduced amount of bounce.

FIG. 1 is an overall view of a cargo handling machine. The cargo handling machine 1 includes a pedestal 2, a swivel base 3, an elevating mechanism unit 5 having an arm 4, and an operation unit 6. The elevating mechanism portion 5 includes a main body portion 7 and a pantograph type arm 4. The operation unit 6 is arranged at the tip of the arm 4 and gives a force in the direction in which the operator 8 wants to move up and down to command the up and down. A lever 9 is provided on the operation unit 6. A strain gauge (not shown) is attached to the lever 9, and a command is given to the drive source (not shown) according to the force applied to the lever 9. If the force on the lever 9 is weak, it moves slowly, and if it is strong, it moves up and down according to the amount of force. The attachment 10 is attached under the operation unit 6. The attachment 10 grips the cargo handling object 11. The cargo handling object 11 is placed on the table 12. By grasping the cargo handling object 11 and raising and lowering it by the operator 8 and turning it, the cargo handling object 11 can be three-dimensionally transported within the movable range of the arm 4.

FIG. 2 is a conceptual diagram showing control and configuration. The cargo handling machine 1 includes an elevating mechanism unit 5 and an operation unit 6 provided with an arm 4. The elevating mechanism portion 5 includes a main body portion 7 and a pantograph type arm 4. A horizontal rail 13, an encoder 14, a drive source 15, a calculation unit 16, and an output converter 17 are fixed to the main body 7. The drive source 15 is an air cylinder 18, the tube 19 side is fixed to the main body 7, and the rod 20 moves up and down. The arm 4 of the elevating mechanism portion 5 has a fulcrum 21, a force point 22, and an action point 23. The fulcrum 21 is engaged with the horizontal rail 13. Since the horizontal rail 13 is fixed, the fulcrum 21 does not move up and down. The force point 22 is engaged with the tip of the rod 20, and the force point 22 is driven by the drive source 15 to raise and lower the cargo handling object 11. The encoder 14 is engaged with the force point 22, and the encoder 14 detects the moving distance above and below the force point 22. The calculation unit 16 is connected to the encoder 14, the operation unit 6, the drive source 15, the output converter 17, and the power supply 24. The output converter 17 is an electropneumatic regulator in the embodiment and is connected to the air source 25. The calculation unit 16 has a ground cutting mode and an elevating mode. In the embodiment, the drive source 15 uses an air cylinder 18, but an electric motor, a hydraulic cylinder, or an electric cylinder may be used, and the drive source is not limited.

FIG. 3 is a graph of the electric signal of the operation unit and the magnitude of the force on the lever. The X-axis is the magnitude of the force on the lever 9, and the Y-axis is the operation unit electrical signal of the operation unit 6. The solid line is the ground cutting mode, and the dotted line is the elevating mode. In the ground cutting mode, the output of the electric signal of the operation unit is increased to shorten the ground cutting time. In the ascending / descending mode, the output of the electric signal of the operation unit is made smaller than that in the ground cutting mode. When the operator 8 increases the force on the lever 9, the output of the electric signal of the operation unit also increases according to the force. In the ascending / descending mode, if the force on the lever 9 is weak, the force is slow, and if the force is strong, the force is fast. While gripping the cargo handling object 11 and cutting the ground, the ground cutting mode is used. It is in the elevating mode except while gripping the cargo handling object 11 and cutting the ground. As will be described later, in the ground cutting mode, the output of the operation unit electric signal is limited.

FIG. 4 is a graph of the encoder movement distance and the limit value of the operation unit electric signal. In the ground cutting mode, the operation unit electric signal of the operation unit 6 is limited. The vertical dotted line in FIG. 4 is an auxiliary line. The X-axis is the moving distance of the encoder 14 of the force point, and the Y-axis is the limit value of the operation unit electric signal of the operation unit 6. In FIG. 3, even if the value of the operation unit electric signal is 15, in the ground cutting mode, the value of the operation unit electric signal is limited by the position of the encoder 14. For example, when the value of the moving distance of the encoder 14 is 9 mm, the electric signal of the operating unit is 5 even if the value of the electric signal of the operating unit is 15. The reason for limiting the value of the electric signal of the operation unit is that if the operator 8 exerts more force on the lever 9 than necessary when the value is not limited, the drive source command force described later becomes too large and the cargo handling object 11 becomes too large. Because it jumps up. If the electrical signal of the operation unit is less than or equal to the limit value, that value is adopted. In the embodiment, the movement of the force point 22 from gripping the cargo handling object 11 to cutting the ground is set to 10 mm. This distance of 10 mm is preset as a ground cutting predicted distance between the force point at the moment of gripping the cargo handling object 11 and the force point at the moment of ground cutting at the time of the maximum weight of the cargo handling object 11. The reason why the force point 22 moves from the moment of gripping to the moment of cutting the ground is that there is a slight backlash such as a joint between the arms 4 and the arm 4 and a bending amount of the arm 4. By setting the maximum weight of the cargo handling object 11 in advance, it is possible to handle even the minimum weight of the cargo handling object 11. The moving distance of the encoder 14 is a point set to cut the ground at 10 mm at the moment when the point at 0 mm is gripped. From 0 mm to 9 mm, the limit value of the operation unit electric signal gradually decreases, and from 9 mm to 10 mm, the limit value suddenly decreases. By suddenly descending from 9 mm to 10 mm, it is controlled to suppress the jumping just before the ground cutting.

FIG. 5 is a graph of the movement distance of the encoder and the command force of the drive source. This is the change in the drive source command force in the ground cutting mode. The vertical and horizontal dotted lines in FIG. 5 are auxiliary lines. The X-axis is the moving distance of the encoder 14 of the force point, and the Y-axis is the drive source command force to the drive source 15. The drive source command force is the sum of the ground cutting control force 31 and the work weight basic force 32. The work is the cargo handling object 11. Although 20 kgf is described on the Y-axis of the drive source command force, it indicates the drive source command force required to lift the 20 kg cargo handling object 11. The calculation unit 16 calculates at regular time intervals, and calculates the ground cutting control force 31 according to the moving distance between the operation unit electric signal and the force point 22. The calculation unit 16 calculates at regular time intervals, and the work weight basic force 32 is calculated by adding the value obtained by multiplying the ground cutting control force 31 by a coefficient and the value of the work weight basic force 32 before the fixed time. The transition of the work weight basic force 32 is shown by a dotted line 33 rising to the right from the origin. The work weight basic force 32 and the ground cutting control force 31 are added together as the drive source command force, and the calculation unit 16 commands the drive source 15 to the drive source command force. The origin of 0 is the moment when the cargo handling object 11 is gripped by the attachment 10, and the point where the movement distance of the encoder 14 is 10 mm is the moment of ground cutting. The point where the encoder 14 has a moving distance of 9 mm is immediately before the ground cutting, and the drive source command force is sharply lowered to suppress the jumping up after the ground cutting. The change in the increase / decrease of the ground cutting control force 31 is that the worker 8 applies force to the lever 9 on the ascending side at the same time as grasping the cargo handling object 11 to try to cut the ground, so that the ground cutting control force 31 increases sharply, and Since the limit value of the operation unit electric signal in FIG. 4 is set, the moving distance of the encoder 14 is drastically reduced from the point of 9 mm. After the point where the movement distance of the encoder 14 is 10 mm or later, the elevator mode is set after the ground is cut. The reason why the drive source command force is once increased to 20 kgf or more and then set to 20 kgf is to softly cut the cargo handling object 11 at the moment of ground cutting.

FIG. 6 is a graph of elapsed time and drive source command force. This is the change in the drive source command force in the ground cutting mode. The vertical and horizontal dotted lines in FIG. 6 are auxiliary lines. The X-axis is the elapsed time, and the Y-axis is the drive source command force to the drive source 15. The drive source command force is the sum of the ground cutting control force 41 and the work weight basic force 42. The work is the cargo handling object 11. Although 20 kgf is described on the Y-axis of the drive source command force, it indicates the drive source command force required to lift the 20 kg cargo handling object 11. The calculation unit 16 calculates at regular time intervals, and calculates the ground cutting control force 41 according to the operation unit electric signal of the operation unit 6 and the moving distance of the force point 22. Every fixed time is 1 ms (= 1/1000 second). The calculation unit 16 calculates at regular time intervals, and the work weight basic force 42 is calculated by adding the value obtained by multiplying the ground cutting control force 41 by a coefficient and the value of the work weight basic force 42 before the fixed time. The transition of the work weight basic force 42 is shown by a dotted line 43 rising to the right from the origin. The work weight basic force 42 and the ground cutting control force 41 are added together as the drive source command force, and the calculation unit 16 commands the drive source 15 to the drive source command force. The origin of 0 is the moment when the cargo handling object 11 is gripped by the attachment 10, and the time when the elapsed time is 1000 ms (= 1 second) is the moment of ground cutting. The time point of the elapsed time of 900 ms is immediately before the ground cutting, and the drive source command force is sharply lowered to suppress the jumping up after the ground cutting. The change in the increase / decrease of the ground cutting control force 41 is that the worker 8 applies force to the lever 9 on the ascending side at the same time as grasping the cargo handling object 11 to try to cut the ground, so that the ground cutting control force 41 increases sharply, and Since the limit value of the operation unit electric signal in FIG. 4 is set, the elapsed time is drastically reduced from the time of 900 ms. After the elapsed time of 1000 ms or later, the elevating mode is set after the ground is cut. For example, if the ground cutting control force 41 is 8 kgf and the work weight basic force 42 is 7 kgf at 300 ms, the drive source command force is 15 kgf. At the time of 301 ms after 1 ms, when the ground cutting control force 41 becomes 7.999 kgf, the work weight basic force 42 is 7 kgf for the previous 300 ms work weight basic force 42 + 7.999 kgf × 0.006 for the ground cutting control force 41. The calculation is 7.047994 kgf, and the drive source command force is 15.046994 kgf. Every 1 ms, it is calculated as "ground cutting control force 41" + "work weight basic force 42 1 ms before" + "ground cutting control force 41 x 0.006" = "drive source command force". Every 1 ms, the ground cutting control force 42 is calculated according to the operation unit electric signal of the operation unit 6 and the moving distance of the force point 22. 0.006 is a coefficient.
In other words,
Ground cutting control force 41 = A
Work weight fundamental force 42 = b 1 ms ago
Work weight basic force 42 = B = b + A x 0.006
Drive source command force = C = A + B
Coefficient = 0.006
A + (b + A × 0.006) = C.
The ground cutting control force 41 is calculated according to the electric signal of the operation unit and the moving distance of the force point 22, and the work weight basic force 42 is obtained by multiplying the ground cutting control force 41 by a coefficient and before a certain time of the work weight basic force 42. The value of is added and calculated, and the sum of the work weight basic force 42 and the ground cutting control force 41 is used as the drive source command force, and the calculation unit 16 commands the drive source 15 to the drive source command force. Since it is calculated every 1 ms, it becomes as shown in FIG. The reason why the drive source command force is once increased to 20 kgf or more and then set to 20 kgf is to softly cut the cargo handling object 11 at the moment of ground cutting.

FIG. 7 is a control flow diagram. It is a flow chart of the control of the ground cutting mode, the step 51 of starting the ground cutting mode, the step 52 of receiving the operation unit electric signal, the step 53 of receiving the moving distance of the force point, and the step of calculating the ground cutting control force. 54, the work weight basic force is calculated in step 55, the drive source command force is calculated in step 56, the drive source command force is output to the output converter in step 57, and the ground cutting determination step 58 is performed. It includes step 59 for ending the mode and step 60 for shifting to the ascending / descending mode. The flow is performed from step 52 of receiving the operation unit electric signal to step 58 of the ground cutting determination every 1 ms (= 1/1000 second). In step 52 of receiving the operation unit electric signal, the degree of force of the operation unit 6 on the lever 9 is output as an electric signal, and the electric signal is received by the calculation unit 16 as the operation unit electric signal. In step 53 of receiving the moving distance of the force point, the calculation unit 16 receives the moving distance of the force point 22 from the position of the force point 22 at the moment when the cargo handling object 11 is gripped. In step 54 of calculating the ground cutting control force, the ground cutting control force is calculated by the calculation unit 16 according to the moving distance between the operation unit electric signal and the force point 22. In step 55 for calculating the work weight basic force, the calculation unit 16 calculates the work weight basic force obtained by multiplying the ground cutting control force by a coefficient and adding the value before a certain time of the work weight basic force as the work weight basic force. In step 56 of calculating the drive source command force, the calculation unit 16 calculates the sum of the ground cutting control force and the work weight basic force as the drive source command force. The step 57 of outputting the drive source command force to the output converter outputs the drive source command force calculated in step 56 of the calculation of the drive source command force of the previous step to the output converter 17. The output converter 17 directs the drive source command force to the drive source 15. In step 58 of the ground cutting determination, the encoder 14 detects the moving distance of the power point 22 and determines whether or not the ground cutting is performed. In the ground cutting determination, if the ground cutting is not performed, the operation unit electric signal is restarted from the receiving step 52. If it is determined by the ground cutting determination that the ground has been cut, the process proceeds to step 59 at the end of the ground cutting mode. The criterion for determining the ground cutting is whether the moving distance of the force point 22 exceeds 10 mm from the moment when the cargo handling object 11 is gripped. For example, if the maximum weight of the cargo handling object 11 is 20 kg and the moving distance of the force point 22 is set to 10 mm in the ground cutting mode, in the case of the cargo handling object 11 of 10 kg, the moving distance of the force point 22 is less than 10 mm and the ground cutting is performed. However, even if the ground is cut with less than 10 mm, it can be judged as a ground cut because it passes the point of 10 mm immediately after the ground is cut. Following step 59 of ending the ground cutting mode, step 60 of shifting to the ascending / descending mode is performed.

The ground cutting predicted distance of the power point at the moment of gripping the cargo handling object and the power point at the moment of ground cutting will be described in advance. The distance of the force point 22 at the time of ground cutting always occurs due to a slight backlash in assembling components such as the arm 4 or bending of the arm 4. The predicted distance of the force point 22 at the time of ground cutting is determined based on the maximum weight of the cargo handling object 11, but it may be assumed or actually measured. In the embodiment, in the case of the cargo handling object 11 of 20 kg, the moving distance of the force point 22 at the ground cutting is 10 mm. For example, when the moving distance of the force point 22 of the ground cutting of 10 kg is measured by the same cargo handling machine 1, it is less than 10 mm, but the difference from the moving distance of the force point 22 of the 20 kg cargo handling object is small, and the ground cutting determination in FIG. 7 It can be controlled without any problem in step 58 of the determination, and even if the weight of the cargo handling object 11 is not constant, smooth ground cutting is possible. Even if the weight of the cargo handling object 11 is different, the change in the moving distance of the force point 22 is small because the arm 4 and the attachment 10 itself are heavy and the influence of the change in the weight of the cargo handling object 11 is small. The predicted ground cutting distance of the emphasis point 22 is set in advance when the assembly of the cargo handling machine 1 before shipping to the customer is completed. In addition, it is possible to change the predicted ground cutting distance of the emphasis point 22 even after delivery to the customer.

The work and control flow will be explained. As shown in FIG. 1, the operator 8 grips the cargo handling object 11 with the attachment 10. Next, a force is applied to the ascending side of the lever 9 of the operation unit 6 in order to cut the cargo handling object 11 from the base 12. Depending on how much force is applied to the lever 9 of the worker 8, the ground cutting control force 31.41 and the work weight basic force 32.42 rapidly increase as shown in FIGS. 5 and 6. When the moving distance of the encoder 14 becomes 9 mm, the ground cutting control force 31.41 sharply decreases due to the limit value of the electric signal of the operation unit shown in FIG. Then, the ground cutting is completed at the point where the encoder 14 is 10 mm. The reason why the ground cutting control force 31.41 is sharply reduced when the moving distance of the encoder 14 is 9 mm is to suppress the jumping of the cargo handling object 11. After cutting the ground, the ascending / descending mode is set, and the ascending / descending speed changes depending on how much force is applied to the lever 9 of the operator 8. Even if the weight of the cargo handling object 11 is not constant, smooth ground cutting is possible.

In the first embodiment, the structure of the arm is a pantograph type, but a cargo handling machine of a scalar type arm may also be used. Further, although the drive source is an air cylinder, any electric motor or hydraulic cylinder may be used as long as the power point is driven.

1 Cargo carrier 2 Pedestal 3 Swing stand 4 Arm 5 Elevating mechanism 6 Operation unit 7 Main body 8 Worker 9 Lever 10 Attachment 11 Cargo handling 12 13 Horizontal rail 14 Encoder 15 Drive source 16 Calculation unit 17 Output converter 18 Air cylinder 19 Tube 20 Rod 21 fulcrum 22 Force point 23 Action point 24 Power supply 25 Air source 31 Ground cutting control force 32 Work weight basic force 33 Point line 41 Ground cutting control force 42 Work weight basic force 43 Point line 51 Step 52 for starting ground cutting mode Operation unit Step of receiving electric signal 53 Step of receiving movement distance of force point 54 Step of calculating ground cutting control force 55 Step of calculating basic work gravity force 56 Step of calculating drive source command force 57 Step of calculating drive source command force Output to output converter Step 58 Ground cutting judgment step 59 Ground cutting mode end step 60 Elevating mode transition step

Claims (3)

An elevating mechanism unit provided with an arm for elevating and lowering a cargo handling object, a drive source for driving a force point of the elevating mechanism unit, an operation unit for commanding elevating and lowering, an encoder for detecting the elevating position of the force point, and the encoder. In a cargo handling machine having the operation unit and the calculation unit connected to the drive source, the calculation unit has a ground cutting mode and an elevating mode, and the moment of gripping the cargo handling object and the moment of ground cutting. The predicted ground cutting distance of the power point is set in advance, and in the ground cutting mode, the output of the drive source is calculated by the calculation unit according to the operation unit electric signal of the elevating command of the operation unit and the movement distance of the power point. It is characterized in that the cargo handling object is to be grounded, and in the calculation process of the calculation unit, the limit value of the electric signal of the operation unit is lowered as the predicted distance for ground cutting is approached, and when the ground cutting determination is made, the mode shifts to the elevating mode. Control method of the cargo handling machine. The calculation unit calculates at regular time intervals, calculates the ground cutting control force according to the movement distance between the operation unit electric signal and the power point, and the work weight basic force is the ground cutting control force multiplied by a coefficient. It is calculated by adding the value of the work weight basic force before a certain period of time, and the sum of the work weight basic force and the ground cutting control force is used as the drive source command force, and the drive source command force is used by the calculation unit. The method for controlling a cargo handling machine according to claim 1, wherein a command is given to the drive source. Operation unit The step of receiving the electric signal, the step of receiving the moving distance of the force point, the step of calculating the ground cutting control force, the step of calculating the basic work weight force, and the step of calculating the drive source command force. The method for controlling a cargo handling machine according to claim 1, wherein the output converter is provided with a step of outputting a drive source command force and a step of determining ground cutting.

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