AGV portal motion speed control method and AGV

Abstract

The invention discloses an AGV portal motion speed control method and an AGV, and the method comprises the steps: receiving a portal motion speed instruction, and obtaining a needed portal motion speed in the portal motion speed instruction; based on the action speed of the portal frame, a speed-rotating speed formula is used for calculating the required rotating speed of the pump; if the required rotating speed is larger than or equal to the minimum rotating speed of the pump motor, the rotating speed of the pump motor is adjusted to the pump required rotating speed, the current corresponding to the opening degree of a multi-way valve port enabling the output flow allowed by the multi-way valve to be larger than the real-time output flow of the pump is calculated, and the opening degree of the multi-way valve port is controlled based on the current; otherwise, the rotating speed of the pump motor is adjusted to the minimum rotating speed, the current corresponding to the opening degree of the valve port of the multi-way valve enabling the output flow allowed by the multi-way valve to be smaller than the real-time output flow of the pump is calculated, and the opening degree of the valve port of the multi-way valve is controlled based on the current. According to the method, different flow control modes are selected based on the required rotating speed of the pump, the low-speed lifting micro-motion performance is optimized, the pressure loss generated by rapid lifting is reduced, and the energy consumption is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of AGV, and particularly relates to an AGV gantry action speed control method and an AGV. BACKGROUND

[0002] At present, AGV hydraulic action is directly controlled by pump speed based on speed instruction demand to control the flow demand of gantry related action. The flow of gantry action is determined by the gear pump speed, but at present, the gear pump has no reliable pressure building rate, stable pressure performance and flow at low speed. Such control requires the pump to build pressure at very low speed, such as tens of revolutions, otherwise it cannot meet the requirement of gantry micro-motion. The overall layout of the gear pump and the hydraulic system is required to be high, and the cost of the pump is high. In addition, there is no real-time detection of oil pressure to calculate a value close to the actual volumetric efficiency, which will bring a large deviation of speed instruction and lifting speed. In summary, the existing control method has high performance requirements for the gear pump and affects the micro-motion of the gantry. SUMMARY

[0003] The main purpose of the present application is to overcome the problems of the prior art, and provide an AGV gantry action speed control method and an AGV, which can reduce the performance requirements of the gear pump and take into account the micro-motion.

[0004] The present application adopts the following technical scheme:

[0005] On the one hand, an AGV gantry action speed control method comprises:

[0006] receiving a gantry action speed instruction, and obtaining a required gantry action speed in the gantry action speed instruction;

[0007] calculating a pump required speed based on the gantry action speed using a speed-speed formula;

[0008] if the required speed is greater than or equal to the minimum speed of the pump motor, adjusting the pump motor speed to the pump required speed, and calculating a current corresponding to the valve port opening of the multi-way valve that allows the output flow of the multi-way valve to be greater than the real-time output flow of the pump, and controlling the valve port opening of the multi-way valve based on the current; otherwise, adjusting the pump motor speed to the minimum speed, and calculating a current corresponding to the valve port opening of the multi-way valve that allows the output flow of the multi-way valve to be less than the real-time output flow of the pump, and controlling the valve port opening of the multi-way valve based on the current.

[0009] Preferably, the current corresponding to the valve port opening of the multi-way valve that allows the output flow of the multi-way valve to be greater than the real-time output flow of the pump is calculated, and the valve port opening of the multi-way valve is controlled based on the current, which specifically comprises:

[0010] The current corresponding to the valve opening degree of the multi-way valve, which makes the output flow allowed to pass through the multi-way valve less than the real-time output flow of the pump, is calculated based on the real-time output flow of the pump, the minimum flow allowed to pass through the multi-way valve, the minimum output flow of the pump, the current corresponding to the minimum output flow of the pump, and the current corresponding to the minimum flow allowed to pass through the multi-way valve, and the valve opening degree of the multi-way valve is controlled based on the current corresponding to the valve opening degree of the multi-way valve.

[0011] The current corresponding to the valve opening degree of the multi-way valve, which makes the output flow allowed to pass through the multi-way valve less than the real-time output flow of the pump, is calculated based on the real-time output flow of the pump, the minimum flow allowed to pass through the multi-way valve, the minimum output flow of the pump, the current corresponding to the minimum output flow of the pump, and the current corresponding to the minimum flow allowed to pass through the multi-way valve, and the valve opening degree of the multi-way valve is controlled based on the current corresponding to the valve opening degree of the multi-way valve.

[0012] The current corresponding to the valve opening degree of the multi-way valve, which makes the output flow allowed to pass through the multi-way valve less than the real-time output flow of the pump, is calculated based on the real-time output flow of the pump, the minimum flow allowed to pass through the multi-way valve, the minimum output flow of the pump, the current corresponding to the minimum output flow of the pump, and the current corresponding to the minimum flow allowed to pass through the multi-way valve, and the valve opening degree of the multi-way valve is controlled based on the current corresponding to the valve opening degree of the multi-way valve.

[0013] The current corresponding to the valve opening degree of the multi-way valve, which makes the output flow allowed to pass through the multi-way valve less than the real-time output flow of the pump, is calculated based on the real-time output flow of the pump, the minimum flow allowed to pass through the multi-way valve, the minimum output flow of the pump, the current corresponding to the minimum output flow of the pump, and the current corresponding to the minimum flow allowed to pass through the multi-way valve, and the valve opening degree of the multi-way valve is controlled based on the current corresponding to the valve opening degree of the multi-way valve.

[0014] Preferably, for a standard two-stage gantry, the pump demand speed is calculated using a speed-speed formula, including: based on the corresponding parameters of the side cylinder, the pump demand speed is calculated using a speed-speed formula, as follows:

[0015] N=D1 2 / 4*π*V1*r*q*60 / λ / η0

[0016] Wherein, N represents the pump demand speed; D1 represents the diameter of the side cylinder of the gantry; V1 represents the required speed of the gantry action; r represents the speed ratio of the fork and the oil cylinder; q represents the number of oil cylinders; λ represents the displacement of the pump; η0 represents the real-time volumetric efficiency of the pump, η0=η2-(η2-η1) / (P2-P1)*(P0-P1), η1 represents the full load volumetric efficiency, η2 represents the no-load volumetric efficiency, P2 represents the full load pressure, P1 represents the no-load pressure, and P0 represents the real-time pressure.

[0017] Preferably, for a two-stage full-freedom gantry or a three-stage gantry, the pump demand speed is calculated using a speed-speed formula, including: based on the corresponding parameters of the middle cylinder, the pump demand speed is calculated using a speed-speed formula, as follows:

[0018] N=D2 2 / 4*π*V1*r*q*60 / λ / η0

[0019] Wherein, N represents the pump demand speed; D2 represents the mast middle cylinder diameter; V1 represents the demand mast action speed; r represents the speed ratio of the fork and the oil cylinder; q represents the number of oil cylinders; λ represents the pump displacement; η0 represents the real-time volumetric efficiency of the pump, η0 = η2 - (η2 - η1) / (P2 - P1) * (P0 - P1), η1 represents the full load volumetric efficiency, η2 represents the no-load volumetric efficiency, P2 represents the full load pressure, P1 represents the no-load pressure, and P0 represents the real-time pressure.

[0020] Preferably, before calculating the current corresponding to the multi-way valve port opening degree that makes the output flow allowed by the multi-way valve greater than the real-time output flow of the pump, the method further comprises: comparing the pump demand speed with the maximum speed of the pump motor, and if the pump demand speed is greater than or equal to the maximum speed of the pump motor, adjusting the pump motor speed to the maximum speed; otherwise, adjusting the pump motor speed to the pump demand speed.

[0021] Preferably, after controlling the multi-way valve port opening degree based on the current, the method further comprises:

[0022] Comparing the mast fork speed with the demand mast action speed, if the absolute value of the speed difference ratio of the two is greater than or equal to a preset ratio, or the absolute value of the speed difference of the two is greater than or equal to a preset value, it is determined that the side cylinder is currently in action, and the pump demand speed is calculated using the speed-speed formula based on the corresponding parameters of the side cylinder.

[0023] Preferably, for a two-stage full-freedom mast or a three-stage mast, before calculating the pump demand speed using the speed-speed formula based on the mast action speed, the method further comprises: determining whether the middle cylinder or the side cylinder is currently in action, as follows:

[0024] Determining the real-time position H of the mast fork, if the real-time position H of the mast fork is within the stroke height of the calibrated middle cylinder, it is determined that the middle cylinder is currently in action; if the real-time position H of the mast fork is within the stroke height of the calibrated side cylinder, it is determined that the side cylinder is currently in action.

[0025] If it is determined that the middle cylinder is currently in action, the pump demand speed is calculated using the speed-speed formula based on the corresponding parameters of the middle cylinder; if it is determined that the side cylinder is currently in action, the pump demand speed is calculated using the speed-speed formula based on the corresponding parameters of the side cylinder.

[0026] Preferably, for mast tilting and tool action, the pump demand speed is calculated using the speed-speed formula, comprising: calculating the pump demand speed using the speed-speed formula based on the mast action speed, the corresponding parameters of the oil cylinder and preset parameter values, as follows:

[0027] N = D3 2 / 4*π*V1*r*q*60 / λ / η0

[0028] Where N represents the required pump speed; D3 represents the diameter of the rodless chamber of the tilting cylinder or the diameter of the attachment cylinder; V1 represents the required gantry movement speed; η0 represents the real-time volumetric efficiency of the pump, η0=η2-(η2-η1) / (P2-P1)*(P0-P1), where η1 represents the full-load volumetric efficiency, η2 represents the no-load volumetric efficiency, P2 represents the full-load pressure, P1 represents the no-load pressure, and P0 represents the real-time pressure; r takes the preset parameter value; q represents the number of cylinders; and λ represents the pump displacement.

[0029] On the other hand, an AGV includes: a control module; the control module implements the AGV gantry movement speed control method.

[0030] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) This invention determines the required speed by judging the speed command and compares it with the minimum speed of the pump motor (including the set idle speed value of the gear pump or the set minimum speed). If the required speed is greater than the set minimum speed, it is determined that the flow demand is large, and the flow output is controlled by the pump. Specifically, the flow allowed by the multi-way valve is greater than or equal to the flow output of the pump motor. The flow required for the lifting speed of the gantry is completely determined by the speed of the pump motor. This can reduce the pressure loss caused by the multi-way valve and save energy. If the required speed is less than the set minimum speed, based on the stability of the pump, the set minimum speed is maintained unchanged. The flow required for the speed of the gantry is controlled by the opening of the multi-way valve, i.e., valve control. Specifically, the flow allowed by the multi-way valve is less than the flow output of the pump motor. This can control the flow output of the gantry by controlling the current of the multi-way valve and then controlling the valve opening (opening ratio) of the multi-way valve.

[0032] (2) The present invention uses a lifting pressure sensor to judge the pressure in real time, calculate a more accurate volumetric efficiency value, reduce the deviation between the gantry action speed command and the actual speed, and improve the control accuracy.

[0033] (3) This invention can not only control the operating speed of a standard secondary gantry, but also control the operating speed of a secondary fully free gantry or a tertiary gantry. Specifically, it can determine whether the current action is of the middle cylinder or the side cylinder based on the speed or position, and then perform corresponding control.

[0034] (4) This invention can not only control the lifting speed, but also control the tilting or attachment movement. Specifically, after determining the current movement of the gate frame, control can be achieved by adjusting the corresponding parameter values ​​in the preset speed-rotation formula. Attached Figure Description

[0035] Figure 1This is a flowchart illustrating the standard two-stage gantry hoisting speed control method according to Embodiment 1 of the present invention;

[0036] Figure 2 This is a schematic diagram showing the relationship between the current I corresponding to the valve opening degree of the multi-way valve in Embodiment 1 of the present invention and the output flow rate QI allowed to pass through the multi-way valve.

[0037] Figure 3 This is a flowchart (speed determination method) of the lifting action speed control method for a two-stage fully free gate or a three-stage gantry according to Embodiment 2 of the present invention;

[0038] Figure 4 This is a flowchart (position determination method) of the lifting speed control method for a two-stage fully free gate or a three-stage gantry according to Embodiment 3 of the present invention.

[0039] Figure 5 This is a flowchart illustrating the gantry tilting / attachment movement speed control method of Embodiment 4 of the present invention. Detailed Implementation

[0040] To make the features and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] The technical solutions in this application will be clearly and thoroughly described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0042] In the description of this invention, it should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the step identifiers S101, S102, S103, etc. are only used for convenience of description and do not indicate the execution order. The corresponding execution order can be adjusted as needed.

[0044] Table 1 below lists the meanings of the parameters involved in this application and their corresponding example units.

[0045] Table 1

[0046]

[0047] Example 1

[0048] See Figure 1 As shown in the figure, this embodiment of an AGV gantry movement speed control method includes the following steps:

[0049] S101, Receive gantry movement speed command, and obtain the required gantry movement speed from the gantry movement speed command;

[0050] S102, based on the gantry action speed and the corresponding parameters of the side cylinder, the required pump speed is calculated using the speed-speed formula;

[0051] S103, if the required speed is greater than or equal to the minimum speed of the pump motor, adjust the pump motor speed to the required speed of the pump, and calculate the current corresponding to the opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve greater than the real-time output flow rate of the pump, and control the opening degree of the multi-way valve based on the current; otherwise, adjust the pump motor speed to the minimum speed, and calculate the current corresponding to the opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve less than the real-time output flow rate of the pump, and control the opening degree of the multi-way valve based on the current.

[0052] The AGV gantry movement speed control method of this embodiment is mainly used for controlling the lifting movement speed of a standard two-stage gantry. The standard two-stage gantry mentioned in this embodiment refers to a gantry that only includes the side cylinders.

[0053] Specifically, in step S102, based on the gantry operating speed and the corresponding parameters of the side cylinder, the required pump speed is calculated using the speed-speed formula, as follows:

[0054] N = D1 2 / 4*π*V1*r*q*60 / λ / η0

[0055] Where N represents the required pump speed; D1 represents the diameter of the mast side cylinder; V1 represents the required mast action speed; r represents the speed ratio formed by the forks and the cylinders (mast side cylinders); q represents the number of cylinders (number of side cylinders), such as 2; λ represents the pump displacement; and η0 represents the pump's real-time volumetric efficiency.

[0056] Specifically, η0 = η2 - (η2 - η1) / (P2 - P1) * (P0 - P1), where η1 represents the full-load volumetric efficiency, η2 represents the no-load volumetric efficiency, P2 represents the full-load pressure, P1 represents the no-load pressure, and P0 represents the real-time pressure. P0 can be the real-time pressure on the gantry side or the real-time pressure of the pump.

[0057] It should be noted that the real-time volumetric efficiency η0 can be calculated using the pressure shown in the above formula, or a preset fixed value can be given. However, the disadvantage of giving a fixed value is that there will be a large deviation between the gantry movement speed command and the actual lifting speed when different pressures exist. This invention uses a lifting pressure sensor to collect real-time pressure and calculate a more accurate volumetric efficiency value, thereby reducing the deviation between the gantry movement speed command and the actual speed and improving control accuracy.

[0058] In S103, the current corresponding to the valve opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve greater than the real-time output flow rate of the pump is calculated. Based on this current, the valve opening degree of the multi-way valve is controlled, specifically including:

[0059] Based on the pump's real-time output flow rate, the pump's minimum speed output flow rate, the multi-way valve's maximum allowable flow rate, the current corresponding to the pump's minimum speed output flow rate, and the current corresponding to the multi-way valve's maximum allowable flow rate, calculate the current corresponding to the multi-way valve's orifice opening that makes the multi-way valve's allowable output flow rate greater than the pump's real-time output flow rate.

[0060] The calculated current corresponding to the opening degree of the multi-way valve is increased by a preset current value or a preset ratio, and the opening degree of the multi-way valve is controlled based on the increased current.

[0061] For the table reading method, the corresponding values ​​of QI are stored in the form of a table. After calculating the rotational speed N, the required flow rate can be deduced. Then, based on the required flow rate, the current I corresponding to the opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve greater than the real-time output flow rate of the pump can be found.

[0062] When using pump control, to eliminate errors caused by bench data, an additional current value can be added to the current obtained through meter reading or technical means. This prevents throttling, which could affect flow output and increase energy consumption. The preset current value 'a' can be set as needed, such as 50mA, resulting in an increased current of I+50mA. Alternatively, the preset percentage can be set as needed, such as approximately 5-10%, resulting in an increased current of I+I*(5-10%).

[0063] For the interpolation method, a reference current I2 needs to be added so that the output flow rate allowed by the multi-way valve is greater than the real-time output flow rate of the pump. The formula for calculating the current I corresponding to the valve opening degree of the multi-way valve is as follows:

[0064] I=I2+(Q0-Q2)*(I3-I2) / (Q3-Q2)

[0065] To eliminate errors caused by benchtop data, an additional current value can be added to the current obtained through meter reading or other technical means. This prevents throttling, which could affect flow output and increase energy consumption. The preset current value 'a' can be set as needed, such as 50mA, resulting in an increased current of I+50mA. Alternatively, the preset percentage can be set as needed, such as approximately 5-10%, resulting in an increased current of I+I*(5-10%).

[0066] In S103, the current corresponding to the valve opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve less than the real-time output flow rate of the pump is calculated. Based on this current, the valve opening degree of the multi-way valve is controlled, specifically including:

[0067] Based on the pump's real-time output flow rate, the minimum flow rate through which the multi-way valve operates, the flow rate output at the pump's minimum speed, the current corresponding to the flow rate output at the pump's minimum speed, and the current corresponding to the minimum flow rate allowed by the multi-way valve, the current corresponding to the multi-way valve's orifice opening that makes the multi-way valve's allowed output flow rate less than the pump's real-time output flow rate is calculated. The multi-way valve's orifice opening is then controlled based on the current corresponding to the multi-way valve's orifice opening.

[0068] For the table reading method, the corresponding values ​​of QI are stored in the form of a table. After calculating the rotational speed N, the required flow rate can be deduced. Then, based on the required flow rate, the current corresponding to the valve opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve less than the real-time output flow rate of the pump can be found.

[0069] For the interpolation method, a reference current I1 needs to be added so that the output flow rate allowed by the multi-way valve is greater than the real-time output flow rate of the pump. The formula for calculating the current I corresponding to the valve opening degree of the multi-way valve is as follows:

[0070] I=I1+(Q0-Q1))*(I2-I1) / (Q2-Q1).

[0071] As mentioned above, the multi-way valve controls the flow output by adjusting the valve opening ratio. Therefore, the multi-way valve's opening ratio is controlled by adjusting the current of the multi-way valve. The relationship between these three factors can be obtained from bench data. The specific process is: "The controller controls the current to the multi-way valve - the multi-way valve controls the valve opening ratio based on the current value - the multi-way valve's valve opening controls the flow output to the actuator." After obtaining the relationship between these three factors, the corresponding relationship value of QI is pre-input into the controller. Subsequently, the corresponding current I can be obtained by reading the table according to the actual needs of Q. Of course, the corresponding current value can also be obtained by taking the midpoint of the relationship and fitting a function relationship, but there will be some error. See the diagram showing the relationship between the current I corresponding to the multi-way valve's valve opening and the multi-way valve's allowable output flow rate QI. Figure 2 As shown. Figure 2 In the diagram, one curve represents the multi-way valve port moving from closed to maximum, while the other curve represents the multi-way valve port moving from maximum to closed.

[0072] This embodiment also discloses an AGV, including: a control module; the control module implements the AGV gantry movement speed control method.

[0073] Example 2

[0074] The difference between this embodiment and Embodiment 1 is that this embodiment uses a speed determination method to control the lifting speed of a two-stage fully free-moving gantry or a three-stage gantry. In this embodiment, the two-stage fully free-moving gantry and the three-stage gantry refer to a gantry including a central cylinder and side cylinders.

[0075] For details, see Figure 3 As shown, an AGV gantry movement speed control method includes:

[0076] S301, Receive gantry movement speed command, and obtain the required gantry movement speed from the gantry movement speed command;

[0077] S302, based on the gantry action speed and the corresponding parameters of the cylinder, uses the speed-speed formula to calculate the required pump speed;

[0078] S303: Determine if the required speed is greater than or equal to the minimum speed of the pump motor. If yes, proceed to S304; otherwise, proceed to S306.

[0079] S304 compares the required pump speed with the maximum pump motor speed. If the required pump speed is greater than or equal to the maximum pump motor speed (Nmax), the pump motor speed is adjusted to the maximum speed; otherwise, the pump motor speed is adjusted to the required pump speed.

[0080] S305, calculate the current corresponding to the opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve greater than the real-time output flow rate of the pump; increase the current corresponding to the opening degree of the multi-way valve by a preset current value or a preset ratio, and control the opening degree of the multi-way valve based on the increased current; go to S307.

[0081] S306, Calculate the current corresponding to the valve opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve less than the real-time output flow rate of the pump, and control the valve opening degree of the multi-way valve based on this current; go to S307.

[0082] S307, determine whether the absolute value of the speed difference ratio between the mast fork speed and the required mast action speed is greater than or equal to the preset ratio. If yes, go to S308; if no, go to S302.

[0083] S308, based on the gantry action speed and the corresponding parameters of the side cylinder, uses the speed-speed formula to calculate the required pump speed;

[0084] S309: If the required speed is greater than or equal to the minimum speed of the pump motor, adjust the pump motor speed to the required speed, and calculate the current corresponding to the opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve greater than the real-time output flow rate of the pump. Increase the current corresponding to the opening degree of the multi-way valve by a preset current value or a preset ratio, and control the opening degree of the multi-way valve based on the increased current. Otherwise, adjust the pump motor speed to the minimum speed, and calculate the current corresponding to the opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve less than the real-time output flow rate of the pump. Control the opening degree of the multi-way valve based on this current.

[0085] As mentioned above, the biggest problem for two-stage and three-stage masts is determining whether the lifting operation is being performed by the center cylinder or the side cylinder. Therefore, compared to the standard two-stage mast, a judgment logic is added to identify whether the lifting operation is within the stroke range of the center or side cylinder. The mast's movement speed command is obtained, and the required speed is calculated, similar to the standard two-stage mast. However, the default cylinder count is 1, meaning it's assumed to be within the center cylinder's working stroke. The speed is then judged to be greater than or equal to the minimum speed, including the set gear pump idle speed or the set minimum speed. If the speed is greater than or equal to the minimum speed, pump control is used, and the flow rate required by the mast's required speed is directly controlled by the pump, ensuring that the flow rate allowed by the multi-way valve is greater than the pump's output flow rate. If the speed is lower than the idle speed, valve control is used, and the flow rate required by the mast is controlled by the multi-way valve, maintaining the motor speed at the idle speed, similar to the flow control of the standard mast.

[0086] In S302 shown, based on the gantry operating speed and the corresponding parameters of the cylinder, the required pump speed is calculated using the speed-speed formula, as follows:

[0087] N = D2 2 / 4*π*V1*r*q*60 / λ / η0

[0088] Where N represents the required pump speed; D2 represents the diameter of the mast cylinder; V1 represents the required mast action speed; r represents the speed ratio formed by the forks and cylinders; q represents the number of cylinders (number of cylinders), such as 1; λ represents the pump displacement; and η0 represents the real-time volumetric efficiency of the pump.

[0089] Specifically, η0 = η2 - (η2 - η1) / (P2 - P1) * (P0 - P1), where η1 represents the full-load volumetric efficiency, η2 represents the no-load volumetric efficiency, P2 represents the full-load pressure, P1 represents the no-load pressure, and P0 represents the real-time pressure. P0 can be the real-time pressure on the gantry side or the real-time pressure of the pump.

[0090] It should be noted that the real-time volumetric efficiency η0 can be calculated using the pressure shown in the above formula, or a preset fixed value can be given. However, the disadvantage of giving a fixed value is that there will be a large deviation between the gantry movement speed command and the actual lifting speed when different pressures exist. This invention uses a lifting pressure sensor to collect real-time pressure and calculate a more accurate volumetric efficiency value, thereby reducing the deviation between the gantry movement speed command and the actual speed and improving control accuracy.

[0091] Similar to Embodiment 1, in S305, the current corresponding to the opening degree of the multi-way valve that allows the output flow rate of the multi-way valve to be greater than the real-time output flow rate of the pump is calculated; the current corresponding to the calculated opening degree of the multi-way valve is increased by a preset current value or a preset ratio, and the opening degree of the multi-way valve is controlled based on the increased current, specifically including:

[0092] Based on the pump's real-time output flow rate, the pump's minimum speed output flow rate, the multi-way valve's maximum allowable flow rate, the current corresponding to the pump's minimum speed output flow rate, and the current corresponding to the multi-way valve's maximum allowable flow rate, calculate the current corresponding to the multi-way valve's orifice opening that makes the multi-way valve's allowable output flow rate greater than the pump's real-time output flow rate.

[0093] The calculated current corresponding to the opening degree of the multi-way valve is increased by a preset current value or a preset ratio, and the opening degree of the multi-way valve is controlled based on the increased current.

[0094] In S306, the current corresponding to the valve opening degree of the multi-way valve that makes the allowed output flow rate of the multi-way valve less than the real-time output flow rate of the pump is calculated. Based on this current, the valve opening degree of the multi-way valve is controlled, specifically including:

[0095] Based on the pump's real-time output flow rate, the minimum flow rate through which the multi-way valve operates, the flow rate output at the pump's minimum speed, the current corresponding to the flow rate output at the pump's minimum speed, and the current corresponding to the minimum flow rate allowed by the multi-way valve, the current corresponding to the multi-way valve's orifice opening that makes the multi-way valve's allowed output flow rate less than the pump's real-time output flow rate is calculated. The multi-way valve's orifice opening is then controlled based on the current corresponding to the multi-way valve's orifice opening.

[0096] S307 specifically includes:

[0097] The speed of the mast forks is compared with the required mast action speed. If the absolute value of the speed difference ratio is greater than the preset ratio, or if the absolute value of the speed difference ratio is greater than the preset value, it is determined that the side cylinder is in motion. Based on the corresponding parameters of the side cylinder, the required pump speed is calculated using the speed-speed formula, and the pump is switched to S308; otherwise, the pump is switched to S302.

[0098] Because the AGV mast is equipped with a cable sensor or other type of speed sensor, the real-time mast fork speed V2 can be compared with the required mast action speed V1. If the speed difference ratio |V2-V1| / V1*100% ≥ X, which is greater than the set value X% (e.g., 5%), or if the speed difference |V2-V1| is greater than the preset value, it is assumed that the side cylinder is performing work at this time. Because of the two-stage fully free mast and the three-stage mast, to ensure the action sequence is first the middle cylinder and then the side cylinders, the pressure of the middle cylinder must be less than the pressure of the side cylinders. Therefore, the cross-sectional area of ​​the middle cylinder is designed to be greater than the sum of the two side cylinders with a certain margin. At this time, based on the number of cylinders being 2 and the corresponding parameters, the required rotational speed N for V1 is calculated to control the relevant actions of the mast. If the speed difference ratio is less than the set value X%, the current control scheme is maintained, and the process switches to S302.

[0099] This embodiment also discloses an AGV, including: a control module; the control module implements the AGV gantry movement speed control method.

[0100] Example 3

[0101] The difference between this embodiment and embodiment two is that this embodiment is used to control the lifting speed of a two-stage fully free gate or a three-stage gantry by using a position determination method.

[0102] See Figure 4 As shown, this embodiment of an AGV gantry movement speed control method includes:

[0103] S401, Receive gantry movement speed command, and obtain the required gantry movement speed from the gantry movement speed command;

[0104] S402: Based on the real-time position of the mast forks, determine whether the current action is the center cylinder or the side cylinder. If it is the side cylinder, proceed to S403; if it is the center cylinder, proceed to S404.

[0105] S403, based on the gantry action speed and the corresponding parameters of the side cylinder, the required pump speed is calculated using the speed-speed formula, then S405;

[0106] S404, based on the gantry action speed and the corresponding parameters of the cylinder, the required pump speed is calculated using the speed-speed formula, turn to S405;

[0107] S405: If the required speed is greater than or equal to the minimum speed of the pump motor, adjust the pump motor speed to the required speed, and calculate the current corresponding to the opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve greater than the real-time output flow rate of the pump. Increase the current corresponding to the opening degree of the multi-way valve by a preset current value or a preset ratio, and control the opening degree of the multi-way valve based on the increased current. Otherwise, adjust the pump motor speed to the minimum speed, and calculate the current corresponding to the opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve less than the real-time output flow rate of the pump. Control the opening degree of the multi-way valve based on this current.

[0108] It should be noted that if it is determined that the cylinder is the middle cylinder, after executing S404 and S405, it will return to S402 for loop judgment. If it is determined that the current action is the side cylinder, the loop can be exited after executing S403 and S405. Of course, the loop can also continue as needed.

[0109] In this embodiment, the AGV is equipped with a pull-wire sensor to acquire other position sensors, which can identify the specific position of the gantry forks in real time. Therefore, a position determination and response control scheme can be added on the basis of the standard two-level gantry.

[0110] To determine the position H of the gantry forks, the parameters of the configured secondary fully free gantry or tertiary gantry crane can be pre-calibrated, such as the stroke height of the center cylinder and the side cylinders. If H is detected to be at the corresponding height, the corresponding q (number of cylinders) and cylinder diameter parameters are selected.

[0111] Specifically, based on the gantry's operating speed and the corresponding parameters of the side cylinders, the required pump speed is calculated using the speed-speed formula, as follows:

[0112] N = D1 2 / 4*π*V1*r*q*60 / λ / η0

[0113] Where N represents the required pump speed; D1 represents the diameter of the mast side cylinder; V1 represents the required mast action speed; r represents the speed ratio formed by the forks and the cylinders (mast side cylinders); q represents the number of cylinders (number of side cylinders), such as 2; λ represents the pump displacement; and η0 represents the pump's real-time volumetric efficiency.

[0114] Based on the gantry operating speed and the corresponding parameters of the cylinder block, the required pump speed is calculated using the speed-speed formula, as follows:

[0115] N = D2 2 / 4*π*V1*r*q*60 / λ / η0

[0116] Where N represents the required pump speed; D2 represents the diameter of the mast cylinder; V1 represents the required mast action speed; r represents the speed ratio formed by the forks and cylinders; q represents the number of cylinders (number of cylinders), such as 1; λ represents the pump displacement; and η0 represents the real-time volumetric efficiency of the pump.

[0117] The specific implementation of S405 is the same as that of S103, and will not be described again in this embodiment.

[0118] This embodiment also discloses an AGV, including: a control module; the control module implements the AGV gantry movement speed control method.

[0119] Example 4

[0120] The difference between this embodiment and Embodiment 1 is that this embodiment is used for controlling the tilt of the gantry and the speed of attachment movement.

[0121] See Figure 5 As shown, this embodiment of an AGV gantry movement speed control method includes:

[0122] S501, Receive gantry movement speed command, and obtain the required gantry movement speed from the gantry movement speed command;

[0123] S502, based on the gantry action speed, corresponding cylinder parameters and preset parameter values, uses the speed-speed formula to calculate the required pump speed;

[0124] S503: If the required speed is greater than or equal to the minimum speed of the pump motor, adjust the pump motor speed to the required speed, and calculate the current corresponding to the opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve greater than the real-time output flow rate of the pump. Increase the current corresponding to the opening degree of the multi-way valve by a preset current value or a preset ratio, and control the opening degree of the multi-way valve based on the increased current. Otherwise, adjust the pump motor speed to the minimum speed, and calculate the current corresponding to the opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve less than the real-time output flow rate of the pump. Control the opening degree of the multi-way valve based on this current.

[0125] The difference between this embodiment and Embodiment 1 lies in S502, where the required pump speed is calculated using the speed-speed formula based on the gantry movement speed, corresponding cylinder parameters, and preset parameter values, including:

[0126] N = D3 2 / 4*π*V1*r*q*60 / λ / η0

[0127] Where N represents the required pump speed; D3 represents the diameter of the rodless chamber of the tilting cylinder or the diameter of the attachment cylinder; V1 represents the required mast movement speed; η0 represents the real-time volumetric efficiency of the pump, η0=η2-(η2-η1) / (P2-P1)*(P0-P1), where η1 represents the full-load volumetric efficiency, η2 represents the no-load volumetric efficiency, P2 represents the full-load pressure, P1 represents the no-load pressure, and P0 represents the real-time pressure; r represents the speed ratio formed by the forks and cylinders. For tilting and attachment control, r takes a preset parameter value; q represents the number of cylinders; and λ represents the pump displacement.

[0128] When tilting forward, the preset parameter value of r is set to, for example, 1. When tilting backward, because the area of ​​the rod chamber of the hydraulic cylinder is relatively small, the preset parameter value of r is less than that for tilting forward, and can be set to, for example, 0.75. These preset parameter values ​​can be pre-stored. When the acquired gantry speed command is tilting forward or backward, the corresponding parameter will be mainly adjusted.

[0129] It should be noted that r can also be replaced by area s. When tilting forward, oil enters the rodless chamber, and the preset parameter value of area s is set to, for example, 1. Then, when tilting backward, the effective area of ​​the rod chamber of the cylinder can be set to, for example, 0.75 or other values, relative to the effective area of ​​the rodless chamber. When the attachment performs work, such as lateral movement, r or s is set to equal 1, because the area ratio of the two chambers is the same.

[0130] The specific implementation of S503 is the same as that of S103, and will not be described again in this embodiment.

[0131] This embodiment also discloses an AGV, including: a control module; the control module implements the AGV gantry movement speed control method.

[0132] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. A method for controlling the movement speed of an AGV gantry, characterized in that, include: Receive the gantry movement speed command and obtain the required gantry movement speed from the gantry movement speed command; Based on the gantry's operating speed, the required pump speed is calculated using the speed-speed formula. If the required speed is greater than or equal to the minimum speed of the pump motor, adjust the pump motor speed to the required speed of the pump, and calculate the current corresponding to the opening degree of the multi-way valve that makes the output flow allowed by the multi-way valve greater than the real-time output flow of the pump. Control the opening degree of the multi-way valve based on this current. Otherwise, adjust the pump motor speed to the minimum speed, and calculate the current corresponding to the opening degree of the multi-way valve that makes the output flow rate allowed by the multi-way valve less than the real-time output flow rate of the pump, and control the opening degree of the multi-way valve based on this current.

2. The AGV gantry movement speed control method according to claim 1, characterized in that, Calculate the current corresponding to the valve opening degree of the multi-way valve that allows the output flow rate to pass through to be greater than the real-time output flow rate of the pump, and control the valve opening degree of the multi-way valve based on this current, specifically including: Based on the pump's real-time output flow rate, the pump's minimum speed output flow rate, the multi-way valve's maximum allowable flow rate, the current corresponding to the pump's minimum speed output flow rate, and the current corresponding to the multi-way valve's maximum allowable flow rate, calculate the current corresponding to the multi-way valve's orifice opening that makes the multi-way valve's allowable output flow rate greater than the pump's real-time output flow rate. The calculated current corresponding to the opening degree of the multi-way valve is increased by a preset current value or a preset ratio, and the opening degree of the multi-way valve is controlled based on the increased current.

3. The AGV gantry movement speed control method according to claim 1, characterized in that, Calculate the current corresponding to the valve opening degree of the multi-way valve that makes the allowable output flow rate of the multi-way valve less than the real-time output flow rate of the pump, and control the valve opening degree of the multi-way valve based on this current, specifically including: Based on the pump's real-time output flow rate, the minimum flow rate through which the multi-way valve operates, the flow rate output at the pump's minimum speed, the current corresponding to the flow rate output at the pump's minimum speed, and the current corresponding to the minimum flow rate allowed by the multi-way valve, the current corresponding to the multi-way valve's orifice opening that makes the multi-way valve's allowed output flow rate less than the pump's real-time output flow rate is calculated. The multi-way valve's orifice opening is then controlled based on the current corresponding to the multi-way valve's orifice opening.

4. The AGV gantry movement speed control method according to claim 1, characterized in that, For a standard two-stage mast, the required pump speed is calculated using the speed-speed formula, including: based on the corresponding parameters of the side cylinders, the required pump speed is calculated using the speed-speed formula, as follows: N=D1 2 / 4*π*V1*r*q*60 / λ / η0 Where N represents the required pump speed; D1 represents the diameter of the mast side cylinder; V1 represents the required mast action speed; r represents the speed ratio formed by the forks and cylinders; q represents the number of cylinders; λ represents the pump displacement; η0 represents the pump's real-time volumetric efficiency, η0=η2-(η2-η1) / (P2-P1)*(P0-P1), where η1 represents the full-load volumetric efficiency, η2 represents the no-load volumetric efficiency, P2 represents the full-load pressure, P1 represents the no-load pressure, and P0 represents the real-time pressure.

5. The AGV gantry movement speed control method according to claim 1, characterized in that, For a two-stage or three-stage mast, the required pump speed is calculated using the speed-speed formula, including: based on the corresponding parameters of the cylinder block, the required pump speed is calculated using the speed-speed formula, as follows: N=D2 2 / 4*π*V1*r*q*60 / λ / η0 Where N represents the required pump speed; D2 represents the diameter of the mast cylinder; V1 represents the required mast operating speed; r represents the speed ratio formed by the forks and cylinders; q represents the number of cylinders; λ represents the pump displacement; η0 represents the pump's real-time volumetric efficiency, η0=η2-(η2-η1) / (P2-P1)*(P0-P1), where η1 represents the full-load volumetric efficiency, η2 represents the no-load volumetric efficiency, P2 represents the full-load pressure, P1 represents the no-load pressure, and P0 represents the real-time pressure.

6. The AGV gantry movement speed control method according to claim 5, characterized in that, Before calculating the current corresponding to the valve opening degree of the multi-way valve that allows the output flow rate of the multi-way valve to be greater than the real-time output flow rate of the pump, the following steps are also included: comparing the pump's required speed with the pump motor's maximum speed. If the pump's required speed is greater than or equal to the pump motor's maximum speed, the pump motor speed is adjusted to the maximum speed; otherwise, the pump motor speed is adjusted to the pump's required speed.

7. The AGV gantry movement speed control method according to claim 5, characterized in that, Following the current-controlled valve orifice opening degree, the following is also included: The speed of the mast forks is compared with the required mast movement speed. If the absolute value of the speed difference ratio is greater than or equal to a preset ratio, or if the absolute value of the speed difference ratio is greater than or equal to a preset value, it is determined that the side cylinder is in motion. Based on the corresponding parameters of the side cylinder, the required pump speed is calculated using the speed-speed formula.

8. The AGV gantry movement speed control method according to claim 1, characterized in that, For two-stage or three-stage masts, before calculating the required pump speed using the speed-speed formula based on the mast's operating speed, the following steps are also taken: determining whether the current cylinder being operated is the central cylinder or a side cylinder, as follows: Determine the real-time position H of the mast forks. If the real-time position H of the mast forks is at the calibrated stroke height of the middle cylinder, then the current action is determined to be the middle cylinder; if the real-time position H of the mast forks is at the calibrated stroke height of the side cylinder, then the current action is determined to be the side cylinder. If the current action is determined to be the center cylinder, the required pump speed is calculated using the speed-speed formula based on the corresponding parameters of the center cylinder; if the current action is determined to be the side cylinder, the required pump speed is calculated using the speed-speed formula based on the corresponding parameters of the side cylinder.

9. The AGV gantry movement speed control method according to claim 1, characterized in that, For gantry tilting and attachment movement, the required pump speed is calculated using the speed-speed formula, including: based on the gantry movement speed, corresponding cylinder parameters, and preset parameter values, the required pump speed is calculated using the speed-speed formula, as follows: N=D3 2 / 4*π*V1*r*q*60 / λ / η0 Where N represents the required pump speed; D3 represents the diameter of the rodless chamber of the tilting cylinder or the diameter of the attachment cylinder; V1 represents the required gantry movement speed; η0 represents the real-time volumetric efficiency of the pump, η0=η2-(η2-η1) / (P2-P1)*(P0-P1), where η1 represents the full-load volumetric efficiency, η2 represents the no-load volumetric efficiency, P2 represents the full-load pressure, P1 represents the no-load pressure, and P0 represents the real-time pressure; r takes the preset parameter value; q represents the number of cylinders; and λ represents the pump displacement.

10. An AGV, characterized in that, include: Control module; the control module implements the AGV gantry movement speed control method as described in any one of claims 1 to 9.

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