Control system and control method for a lifting platform

Abstract

This invention provides a control method for a lifting platform, comprising the following steps: S1. The control box receives position detection commands and flow detection commands from the main control computer; S2. The control box controls the position detector to detect the stroke of the hydraulic cylinder according to the position detection commands; S3. The control box controls the hydraulic oil flow detector to detect the hydraulic oil flow of the hydraulic cylinder according to the flow detection commands; S4. The control box receives position information fed back by the position detector and flow information fed back by the hydraulic oil flow detector; S5. The control box uses PID control or fuzzy control to calculate the position and flow information; S6. The control box controls the hydraulic cylinder movement by adjusting the opening of the servo valve according to the calculation results. This invention employs dual-loop PID control and fuzzy control of position and hydraulic flow, which can continuously correct the opening of the servo valve based on real-time closed-loop control according to the load, thereby ensuring the consistency of the lifting cylinder movement.

Description

Technical Field

[0001] This invention relates to the field of lifting platform technology, and more specifically to a control system and control method for a lifting platform. Background Technology

[0002] Currently, in sanitation equipment using four-post lifting compression units, the lifting and lowering of the lifting platform is generally controlled by synchronous lifting using four hydraulic cylinders. The control method typically employs a synchronous motor to ensure smooth lifting. The electrical control system controls the platform's lifting and lowering through electrical logic, while the hydraulic system uses the synchronous motor to force one hydraulic oil stream to be evenly divided into four streams, which then act on the four hydraulic cylinders, thereby driving the lifting platform's movement.

[0003] Because synchronous motors operate via gear meshing, they inherently possess a certain degree of operational error. Using electrically controlled synchronous motors can ensure a 3% stability rate in equipment operation (maximum error ≤30mm per 1000mm stroke of the four cylinders). However, since synchronous motor control is open-loop, the error will gradually increase over time with prolonged heavy operation. Existing technology has certain drawbacks, which can be categorized into, but are not limited to, the following three:

[0004] a. Error defects: The stability only reaches 3%. The longer the lifting platform stroke, the greater the error. When the stroke exceeds 4200mm, the maximum deviation of the four pillars of the platform reaches 126mm. When the platform is in place, the entire platform is tilted and not level with the ground, thus affecting the operation of the next process of the equipment.

[0005] b. Operational defects: Due to the continuous accumulation of errors caused by the synchronous motor with the load, the platform often experiences shaking and jerking during operation.

[0006] Risk and defect: If the error exceeds a certain level, the entire equipment may collapse during the platform's lifting and lowering process. Summary of the Invention

[0007] This invention provides a control system and control method for a lifting platform to reduce flatness error and improve equipment operating accuracy.

[0008] One aspect of the embodiments of this specification discloses a control method for a lifting platform, including the following steps:

[0009] S1. The control box receives position detection commands and flow detection commands from the main control computer;

[0010] S2. The control box controls the position detector to detect the stroke of the hydraulic cylinder according to the position detection command;

[0011] S3. The control box controls the hydraulic oil flow detector to detect the hydraulic oil flow of the oil cylinder according to the flow detection command;

[0012] S4. The control box receives the position information fed back by the position detector and the flow information fed back by the hydraulic oil flow detector;

[0013] S5. The control box uses PID control or fuzzy control to calculate the location information and flow information;

[0014] S6. The control box controls the movement of the hydraulic cylinder by adjusting the opening of the servo valve according to the calculation results.

[0015] In one embodiment disclosed in this specification, S1 includes:

[0016] S101. After receiving the position detection command and the flow detection command, the control box analyzes and processes the position detection command and the flow detection command to determine how many sampling cycles and the interval time of the sampling cycles are contained in the position detection command and the flow detection command.

[0017] S102. If both the position detection command and the flow detection command have only one sampling period, the control box sends a working command to the position detector and the hydraulic oil flow detector;

[0018] S103. If both the position detection command and the flow detection command have multiple sampling periods, the control box determines whether the number of sampling periods and the interval time of both are consistent. If they are consistent, the control box sends a synchronization command to the position detector and the hydraulic oil flow detector; otherwise, the control box sends a command error message to the main control computer.

[0019] In one embodiment disclosed in this specification, S2 includes:

[0020] The control box sends a timing sampling command to the position detector according to the number of sampling cycles and the interval time, so that the position detector performs timing detection on the stroke of the hydraulic cylinder.

[0021] In one embodiment disclosed in this specification, S3 includes:

[0022] The control box sends a timing sampling command to the hydraulic oil flow detector according to the number of sampling cycles and the interval time, so that the hydraulic oil flow detector can perform timing detection of the hydraulic oil flow of the oil cylinder.

[0023] In one embodiment disclosed in this specification, S4 includes:

[0024] S401. The control box receives location information and flow information;

[0025] S402. The control box arranges the location information and flow information sequentially based on the sampling time sequence;

[0026] S403. The control box binds the location information and flow information of the same sampling time sequence into detection data to obtain multiple detection data of different time sequences.

[0027] In one embodiment disclosed in this specification, S5 includes:

[0028] S501. The control box determines the deviation between the actual stroke and the set stroke of the hydraulic cylinder based on the detection data;

[0029] S502. If the deviation is less than or equal to 3mm, use PID control and execute S504;

[0030] S503. If the deviation is greater than 3mm, fuzzy control is adopted and S505 is executed;

[0031] S504. Calculation is performed using the PID formula, which is as follows:

[0032]

[0033] Performing the Z-transform yields:

[0034]

[0035] The transfer function of PID control is:

[0036]

[0037] Z-inverse yields:

[0038]

[0039] Where C(n) is the system control quantity, which is the opening degree of the servo valve; e(n) is the nth deviation of the platform position; T is the control period; Ti is the integral time; Td is the derivative time; and Kp is the proportional coefficient.

[0040] S505. The individual deviations of the real-time positions of the hydraulic cylinders are e(n) = actual position - program setting, and the individual deviation rates are ec(n) = e(n) - e(n-1). The deviation e is divided into nine fuzzy quantities NL, NM, NS, N0, Z0, P0, PS, PM and PL, which are defined as set E; the deviation rate ec is divided into five fuzzy quantities NL, NS, Z0, PS and PL, which are defined as set EC.

[0041] Transforming e(n) into the universe of discourse [-2, +2] and ec(n) into the universe of discourse [-1, +1], we obtain the discrete E(n) and EC(n) as shown below:

[0042] E(n) = INT[K1e(n) + 0.5];

[0043] EC(n) = INT[K2ec(n) + 0.5];

[0044] The rule expression for fuzzy control is then obtained as follows:

[0045] IFE i AND Ecj THENΔU ij;

[0046] And by introducing integral control, we obtain:

[0047]

[0048] Where Uf(n) is the control output value obtained by looking up the fuzzy control table based on the deviation E and deviation rate EC obtained from the nth sampling, and then multiplying it by the proportional factor KU; KI is the integral coefficient of the fuzzy controller. This represents the integral control quantity in the fuzzy controller during the (n-1)th sampling.

[0049] In one embodiment disclosed in this specification, when the nth sampling is switched from fuzzy control to PID control, the control output value C(n-1) of the (n-1)th sampling and the deviation value between the (n-1)th and (n-2)th samplings are saved, and the (n-1)th output Uf i(n-1) of the fuzzy control is assigned to the output value C(n-1) of the PID.

[0050] When the nth sampling switches from PID control to fuzzy control, the output value C(n-1) of the (n-1)th PID control is assigned to Uf i(n-1).

[0051] Another aspect of the embodiments of this specification discloses a control system for a lifting platform, comprising:

[0052] The main control computer has a built-in CPU module, which is used to issue location detection commands and flow detection commands;

[0053] The control box has a built-in PLC component for receiving position detection commands and flow detection commands;

[0054] A position detector is connected to the control box and is controlled by the control box to detect the stroke of the hydraulic cylinder and obtain position information;

[0055] A hydraulic oil flow detector is connected to the control box so that it can be controlled by the control box to detect the hydraulic oil flow of the oil cylinder and obtain flow information.

[0056] A hydraulic pump station, connected to the control box, is equipped with a servo valve, the opening of which is controlled by the control box based on position and flow information.

[0057] The hydraulic cylinder is connected to the servo valve.

[0058] In one embodiment disclosed in this specification, the main control computer is provided with a memory, which is connected to the CPU module and stores a computer program that can run on the CPU module; when the CPU module executes the computer program, the CPU module controls the PLC module to work in order to implement the lifting platform control method described above.

[0059] The embodiments described in this specification can achieve at least the following beneficial effects:

[0060] This invention abandons the conventional synchronous motor control method and adopts a brand-new electro-hydraulic closed-loop control method. It can adjust the oil flow rate of the cylinder in real time according to different real-time loads, thereby ensuring the stable operation of the equipment. Moreover, it adopts dual-loop PID control and fuzzy control of position and hydraulic flow, which can continuously correct the opening of the servo valve according to the real-time closed-loop control of the load, thereby ensuring the consistency of the lifting cylinder action, achieving smooth lifting and lowering of the platform with less error, and even a stability of 1.5%. Attached Figure Description

[0061] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0062] Figure 1 This is a schematic diagram illustrating the steps of the control method for the lifting platform involved in some embodiments of the present invention.

[0063] Figure 2 This is a schematic diagram of the control system of the lifting platform involved in some embodiments of the present invention.

[0064] Figure 3 This is a partial schematic diagram of the circuit of the control box involved in some embodiments of the present invention.

[0065] Figure 4 This is a partial schematic diagram of the circuit of the control box involved in some embodiments of the present invention.

[0066] Figure 5 This is a partial schematic diagram of the circuit of the control box involved in some embodiments of the present invention.

[0067] Figure 6 This is a partial schematic diagram of the circuit of the control box involved in some embodiments of the present invention.

[0068] Figure 7 This is a partial schematic diagram of the circuit of the control box involved in some embodiments of the present invention.

[0069] Figure 8 This is a partial schematic diagram of the circuit of the control box involved in some embodiments of the present invention.

[0070] Figure 9 This is a partial schematic diagram of the circuit of the control box involved in some embodiments of the present invention.

[0071] Figure 10 This is a partial schematic diagram of the circuit of the control box involved in some embodiments of the present invention.

[0072] Figure 11 This is a schematic diagram of the measurement results of three batches at different locations involved in some embodiments of the present invention.

[0073] Figure 12 This is a partial schematic diagram of the circuit of the hydraulic oil flow detector involved in some embodiments of the present invention.

[0074] Figure 13 This is a partial schematic diagram of the circuit of the hydraulic oil flow detector involved in some embodiments of the present invention.

[0075] Figure 14 This is a partial schematic diagram of the circuit of the hydraulic oil flow detector involved in some embodiments of the present invention.

[0076] Figure 15 This is a partial schematic diagram of the circuit of the hydraulic oil flow detector involved in some embodiments of the present invention.

[0077] Figure 16 This is a schematic diagram of dual-loop PID control and fuzzy control for position PID control and hydraulic flow PID control involved in some embodiments of the present invention.

[0078] Figure label:

[0079] 1. Main control computer;

[0080] 2. Control box;

[0081] 3. Position detector;

[0082] 4. Hydraulic oil flow detector;

[0083] 5. Hydraulic pump station; 51. Servo valve;

[0084] 6. Hydraulic cylinder. Detailed Implementation

[0085] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0086] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0087] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0088] Furthermore, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0089] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0090] like Figure 1 As shown, one aspect of the embodiments of this specification discloses a control method for a lifting platform, including the following steps:

[0091] S1. Control box 2 receives position detection commands and flow detection commands from main control computer 1.

[0092] In some embodiments, S1 includes:

[0093] S101. After receiving the position detection command and the flow detection command, the control box 2 analyzes and processes the position detection command and the flow detection command to determine how many sampling cycles and the interval time of the sampling cycle are contained in the position detection command and the flow detection command.

[0094] S102. If both the position detection command and the flow detection command have only one sampling cycle, the control box 2 sends a working command to the position detector 3 and the hydraulic oil flow detector 4.

[0095] S103. If both the position detection command and the flow detection command have multiple sampling cycles, the control box 2 determines whether the number of sampling cycles and the interval time of both are consistent. If they are consistent, the control box 2 sends a synchronous working command to the position detector 3 and the hydraulic oil flow detector 4; otherwise, the control box 2 sends a command error message to the main control computer 1.

[0096] S2. Control box 2 controls position detector 3 to detect the stroke of hydraulic cylinder 6 according to position detection command.

[0097] In some embodiments, S2 includes:

[0098] The control box 2 sends a timing sampling command to the position detector 3 according to the number of sampling cycles and the interval time, so that the position detector 3 performs timing detection on the stroke of the hydraulic cylinder 6.

[0099] S3. Control box 2 controls hydraulic oil flow detector 4 to detect the hydraulic oil flow of cylinder 6 according to the flow detection command.

[0100] In some embodiments, S3 includes:

[0101] The control box 2 sends a timing sampling command to the hydraulic oil flow detector 4 according to the number of sampling cycles and the interval time, so that the hydraulic oil flow detector 4 performs timing detection on the hydraulic oil flow of the oil cylinder 6.

[0102] S4. Control box 2 receives position information from position detector 3 and flow information from hydraulic oil flow detector 4.

[0103] In some embodiments, S4 includes:

[0104] S401. Control box 2 receives location information and flow information;

[0105] S402. Control box 2 arranges the location information and flow information sequentially based on the sampling time sequence;

[0106] S403. Control box 2 binds the location information and flow information of the same sampling time sequence into detection data to obtain multiple detection data of different time sequences.

[0107] S5. Control box 2 uses PID control or fuzzy control to calculate position and flow information.

[0108] In some embodiments, S5 includes:

[0109] S501. Based on the detection data, the control box 2 determines the deviation between the actual stroke and the set stroke of the hydraulic cylinder 6;

[0110] S502. If the deviation is less than or equal to 3mm, use PID control and execute S504;

[0111] S503. If the deviation is greater than 3mm, fuzzy control is adopted and S505 is executed;

[0112] S504. Calculation is performed using the PID formula, which is as follows:

[0113]

[0114] Performing the Z-transform yields:

[0115]

[0116] The transfer function of PID control is:

[0117]

[0118] Z-inverse yields:

[0119]

[0120] Where C(n) is the system control quantity, which is the opening degree of servo valve 51; e(n) is the nth deviation of the platform position; T is the control period; Ti is the integral time; Td is the derivative time; and Kp is the proportional coefficient.

[0121] S505. The individual deviations of the real-time position of cylinder 6 are e(n) = actual position - program setting, and the individual deviation rates are ec(n) = e(n) - e(n-1). The deviation e is divided into nine fuzzy quantities NL, NM, NS, N0, Z0, P0, PS, PM and PL, which are defined as set E; the deviation rate ec is divided into five fuzzy quantities NL, NS, Z0, PS and PL, which are defined as set EC.

[0122] Transforming e(n) into the universe of discourse [-2, +2] and ec(n) into the universe of discourse [-1, +1], we obtain the discrete E(n) and EC(n) as shown below:

[0123] E(n) = INT[K1e(n) + 0.5];

[0124] EC(n) = INT[K2ec(n) + 0.5];

[0125] The rule expression for fuzzy control is then obtained as follows:

[0126] IFE i AND Ecj THENΔU ij;

[0127] And by introducing integral control, we obtain:

[0128]

[0129] Where Uf(n) is the control output value obtained by looking up the fuzzy control table based on the deviation E and deviation rate EC obtained from the nth sampling, and then multiplying it by the proportional factor KU; KI is the integral coefficient of the fuzzy controller. This represents the integral control quantity in the fuzzy controller during the (n-1)th sampling.

[0130] In some embodiments, when the nth sampling is switched from fuzzy control to PID control, the control output value C(n-1) of the (n-1)th sampling and the deviation value between the (n-1)th and (n-2)th samplings are saved, and the (n-1)th output Ufi(n-1) of the fuzzy control is assigned to the output value C(n-1) of the PID.

[0131] When the nth sampling switches from PID control to fuzzy control, the output value C(n-1) of the (n-1)th PID control is assigned to Ufi(n-1).

[0132] Among them, dual-loop PID control and fuzzy control, such as position PID control and hydraulic flow PID control, are as follows: Figure 16 As shown, PID control and fuzzy control can be switched by the switch of the built-in software of the main control computer 1 or the control box 2.

[0133] S6. Based on the calculation results, the control box 2 controls the action of the hydraulic cylinder 6 by adjusting the opening of the servo valve 51.

[0134] like Figure 2 As shown, another aspect of the embodiments of this specification discloses a control system for a lifting platform, including:

[0135] The main control computer 1 has a built-in CPU module, which is used to issue location detection commands and flow detection commands;

[0136] Control box 2 has a built-in PLC component for receiving position detection commands and flow detection commands;

[0137] Position detector 3 is connected to control box 2 and is controlled by control box 2 to detect the stroke of hydraulic cylinder 6 and obtain position information;

[0138] The hydraulic oil flow detector 4 is connected to the control box 2 and is controlled by the control box 2 to detect the hydraulic oil flow of the oil cylinder 6 and obtain flow information.

[0139] The hydraulic pump station 5 is connected to the control box 2 and is equipped with a servo valve 51. The control box 2 adjusts the opening degree of the servo valve 51 based on the position information and flow information.

[0140] Hydraulic cylinder 6 is connected to servo valve 51.

[0141] In some embodiments, the main control computer 1 is provided with a memory connected to the CPU module and stores a computer program that can run on the CPU module; when the CPU module executes the computer program, the CPU module controls the PLC module to work in order to implement the lifting platform control method described in any of the above.

[0142] In some embodiments, such as Figures 3 to 10 As shown, the circuit of control box 2 includes surge protector U1, phase sequence relay U2, circuit breaker QF1, soft starter U3, circuit breaker QF2, main oil pump M1, circuit breaker QF3, thermal relay FR4, circulating pump M2, cooling fan M3, circuit breaker QF4, circuit breaker QF5, circuit breaker QF6, power supply DY, key switch SA8, emergency stop switch SJT1, PLC module U4, phase sequence protection switch K1, workstation proximity switch K2, workstation proximity switch K3, workstation proximity switch K4, workstation proximity switch K5, maintenance workstation proximity switch K6, upper limit proximity switch K7, upper deceleration position proximity switch K8, lower limit proximity switch K9, lower deceleration position proximity switch K10, oil tank low level proximity switch K11, return oil blockage proximity switch K12, digital module U5, and fault reset switch SB. 1. Main oil pump remote start / stop switch SB2, up remote control switch SB3, down remote control switch SB4, open tank remote control switch SB5, close tank remote control switch SB6, emergency stop switch SJT2, up button S1, down button S2, open tank button S3, close tank button S4, analog input module U6, analog output module U7, high pressure valve F1, low pressure valve F2, up valve F3, down valve F4, open tank valve F5, close tank valve F6, signal drive board U8, servo valve P1, servo valve P2, servo valve P3, servo valve P4, relay KA1, relay KA2, relay KA3, relay KA4, relay KA5, relay KA6, relay KA7, relay KA8, relay KA27, relay KA28, relay KA29, relay KM1 and relay KM4.

[0143] Circuit breaker QF1 is connected to three-phase power (phase lines L1 to L3). Surge protector U1 is connected to circuit breaker QF1 and neutral line N. Phase sequence relay U2 is connected to circuit breaker QF1. One end of circuit breaker QF2 is connected to circuit breaker QF1 (L1, L2, L3), and the other end is connected to the power supply terminal (pins 1, 3, and 5) of soft starter U3 through the normally open contact KM1-1 of relay KM1. Pins 2, 4, and 6 of soft starter U3 are connected to pins U1, V1, and W1 of main oil pump M1, respectively. The +24V pin of soft starter U3 is connected to pin LI1. I2 is connected to the +24V pin of the soft starter U3 through the normally open contact KA1-1 of the relay KA1. One end of the built-in switch RK1 of the soft starter U3 is connected to one end of the coil of the relay KA27, and the other end is connected to an external voltage terminal of 0V. The other end of the coil of the relay KA27 is connected to an external voltage terminal of 24V+. One end of the built-in switch RK2 of the soft starter U3 is connected to one end of the coil of the relay KA28, and the other end is connected to an external voltage terminal of 0V. The other end of the coil of the relay KA28 is connected to an external voltage terminal of 24V+.

[0144] One end of circuit breaker QF3 is connected to circuit breaker QF1 (L1, L2, L3), and the other end is connected to circulating pump M2 through normally open contact KM4-1 of relay KM4 and thermal relay FR4. One end of circuit breaker QF4 is connected to circuit breaker QF1 (L1 and neutral line N), and the other end is connected to cooling fan M3 through normally open contact KA29-1 of relay KA29. One end of circuit breaker QF5 is connected to circuit breaker QF1 (L2 and neutral line N), and the other end is connected to pins CL1 and Cl2 of soft starter U3 and one end of circuit breaker QF6 through key switch SA8. The other end of circuit breaker QF6 is connected to power supply DY. The output of power supply DY serves as voltage terminal 0V and voltage terminal 24V+.

[0145] One end of emergency stop switch SJT1 is connected to circuit breaker QF5 via key switch SA8. The other end of emergency stop switch SJT1 is connected in series with the normally open contact KA27-1 of relay KA27, the normally closed contact KA28-1 of relay KA28, and the coil of relay KM1. After being connected in series, they are connected to the neutral line N through circuit breaker QF5 to form a circuit. The other end of emergency stop switch SJT1 is connected in series with the normally open contact KA2-1 of relay KA2, the normally closed contact FR4-1 of thermal relay FR4, and the coil of relay KM4. After being connected in series, they are connected to the neutral line N through circuit breaker QF5 to form a circuit. The other end of emergency stop switch SJT1 is connected in series with the normally open contact KM4-2 of relay KM4 and the coil of relay KA29. After being connected in series, they are connected to the neutral line N through circuit breaker QF5 to form a circuit.

[0146] The power supply terminals of PLC module U4 are externally connected to a voltage terminal of 24V+ and a voltage terminal of 0V. The pins of PLC module U4 are DI0.0, DI0.1, DI0.2, DI0.3, DI0.4, DI0.5, DI0.6, DI0.7, DI1.0, DI1.1, DI1.4, and DI... 1.5 is connected to the phase sequence protection switch K1, station proximity switch K2, station proximity switch K3, station proximity switch K4, station proximity switch K5, maintenance station proximity switch K6, upper limit proximity switch K7, upper deceleration position proximity switch K8, lower limit proximity switch K9, lower deceleration position proximity switch K10, oil tank low level proximity switch K11, and return oil blockage proximity switch K12 in a corresponding manner. The pins DQ0.0, DQ0.1, DQ0.2, DQ0.3, DQ0.4, DQ0.5, DQ0.6, and DQ0.7 of the PLC module U4 are connected to the coils of relays KA1, KA2, KA3, KA4, KA5, KA6, KA7, and KA8 in a corresponding manner.

[0147] A circuit is formed by connecting the 24V+ voltage terminal, the normally open contact KA3-1 of relay KA3, the high-pressure valve F1, and the 0V voltage terminal in series; a circuit is formed by connecting the 24V+ voltage terminal, the normally open contact KA4-1 of relay KA4, the low-pressure valve F2, and the 0V voltage terminal in series; a circuit is formed by connecting the 24V+ voltage terminal, the normally open contact KA5-1 of relay KA5, the rising valve F3, and the 0V voltage terminal in series; a circuit is formed by connecting the 24V+ voltage terminal, the normally open contact KA6-1 of relay KA6, the falling valve F4, and the 0V voltage terminal in series; a circuit is formed by connecting the 24V+ voltage terminal, the normally open contact KA7-1 of relay KA7, the opening valve F5, and the 0V voltage terminal in series; and a circuit is formed by connecting the 24V+ voltage terminal, the normally open contact KA8-1 of relay KA8, the closing valve F6, and the 0V voltage terminal in series.

[0148] Pins DI 12.0, DI 12.1, DI 12.2, DI 12.3, DI 12.4, and DI 12.5 of digital module U5 are respectively connected to fault reset switch SB1, main oil pump remote start / stop switch SB2, up remote switch SB3, down remote switch SB4, open remote switch SB5, and close remote switch SB6. Pins DI 13.0, DI 13.1, DI 13.2, DI 13.3, and DI 13.4 of digital module U5 are respectively connected to emergency stop switch SJT2, up button S1, down button S2, open button S3, and close button S4.

[0149] The power supply terminal of the analog input module U6 is connected to the external voltage terminal 24V+ and the voltage terminal 0V. The pins AI0+, AI1+, AI2+ and AI3+ of the analog input module U6 are connected one-to-one with the four hydraulic oil flow detectors 4 corresponding to the four cylinders 6 of the lifting platform. The pins AI4+ and AI5+ of the analog input module U6 are connected to the system pressure detection output terminal and the system temperature output terminal of the hydraulic pump station 5, respectively. The pins AI0-, AI1-, AI2-, AI3-, AI4- and AI5- of the analog input module U6 are connected to the voltage terminal 0V.

[0150] The power supply terminals of analog output module U7 are connected to external voltage terminals 24V+ and 0V. The pins AO0+, AO0-, AO1+, A10-, AO2+, AO2-, AO3+, and AO3- of analog output module U7 are connected to the pins I0+, I0-, I1+, I1-, I2+, I2-, I3+, and I3- of signal driver board U8, respectively. The pins A+ and A- of signal driver board U8 are connected to the two ends of servo valve P1, B+ and B- of signal driver board U8 are connected to the two ends of servo valve P2, C+ and C- of signal driver board U8 are connected to the two ends of servo valve P3, and D+ and D- of signal driver board U8 are connected to the two ends of servo valve P4.

[0151] It is clear that PLC module U4, digital input module U5, analog input module U6, and analog output module U7 can be integrated into a single-chip microcomputer control component, serving as the PLC component within control box 2 to achieve the aforementioned functions of control box 2.

[0152] It should be understood that the lifting platform is raised and lowered by four hydraulic cylinders 6. The PLC component in the control box 2 acts as the main controller, collecting the position signals of the four corners of the lifting platform and the flow rate of the four hydraulic oil channels. Through dual-loop PID control and fuzzy control of position and hydraulic flow, the opening degree of the servo valves 51 of the four hydraulic cylinders 6 is output, ensuring the smooth operation of the lifting platform and achieving precise control.

[0153] The specific work process is as follows:

[0154] The system starts to operate by sequentially closing circuit breakers QF1, QF2, QF3, QF4, QF5, and QF6, as well as key switch SA8.

[0155] The soft starter U3 receives voltage signals (from circuit breaker QF5) on pins CL1 and CL2. Simultaneously, the main oil pump remote start / stop switch SB2 is closed. The digital module U5 receives the start signal and transmits it to the PLC module U4. The PLC module U4 supplies power to the coils of relays KA1 and KA2, causing the normally open contact KA1-1 to close. This closes the built-in switch RK1 of the soft starter U3, energizing the coil of relay KA27 and closing its normally open contact KA27-1. The coil of relay KM1 is also energized, and its normally open contact KM1-1 closes. Circuit breaker QF2 supplies power to the main oil pump M1 through the soft starter U3, starting the main oil pump M1 and putting the system into standby mode.

[0156] When the coil of relay KA2 is energized, the normally open contact KA1-1 closes. When the coil of relay KM4 is energized, the normally open contact KM4-1 closes. When the circulating pump M2 starts, the normally open contact KM4-2 closes. When the coil of relay KA29 is energized, the normally open contact KA29-1 closes. When the cooling fan M3 (inside hydraulic pump station 5) starts, it is activated.

[0157] The four hydraulic cylinders can be controlled to move, thus controlling the lifting platform to rise or fall, via the up remote switch SB3 and down remote switch SB4 (remote control), or the up button S1 and down button S2 (operation panel).

[0158] When the PLC components (digital module U5 and PLC module U4) in control box 2 receive an up or down command, based on the flow signal received by analog input module U6 (pins AI0+, AI1+, AI2+, and AI3+) and the position signal received by PLC module U4 (pins DI0.1, DI0.2, DI0.3, and DI0.4), a dual-loop PI controller is used to measure the position and hydraulic flow. D-control and fuzzy control output signals to the corresponding relays KA3, KA4, KA5, and KA6. The normally open contacts KA3-1, KA4-1, KA5-1, and KA6-1 close, causing the corresponding high-pressure valve F1, low-pressure valve F2, rising valve F3, and falling valve F4 to operate. Simultaneously, the analog output module U7 outputs drive signals to the signal drive board U8. The signal drive board U8 drives the corresponding servo valves P1, P2, P3, and P4 to operate with the same or different opening degrees to regulate the action of the four hydraulic cylinders 6, so that the lifting platform can rise or fall stably. That is, the output signals are sent to the corresponding switching valves: high-pressure valve F1, low-pressure valve F2, and directional valves (rising valve F3 and falling valve F4), as well as the corresponding analog valves (real-time valve opening degree): servo valves P1, P2, P3, and P4.

[0159] The collected position signals are obtained from the signals of four position detectors 3 (workstation proximity switch K2, workstation proximity switch K3, workstation proximity switch K4, and workstation proximity switch K5). The signals are input to the PLC module U4 and, after high-speed counting, the specific positions of the four corners of the lifting platform can be obtained.

[0160] The collected flow signals are: the standard 4-20mA signals from the four hydraulic oil flow detectors are input to the analog input module U6. After A / D conversion, the specific real-time flow of the four hydraulic oil channels can be obtained (the hydraulic oil flow supplied by the hydraulic pump station 5, i.e., the main oil pump M1, to the four oil cylinders 6 through four servo valves 51: servo valve P1, servo valve P2, servo valve P3, and servo valve P4).

[0161] By collecting position and flow signals, and based on real-time deviations, when the deviation between the given stroke and the actual stroke is within 3mm, dual-loop PID control of position and flow is used within the PLC component; when the deviation is greater than 3mm, fuzzy control is used within the PLC component. The real-time control data is mainly reflected in the opening degree of the servo valve 51, specifically the output signals of pins AO0+, AO0-, AO1+, A10-, AO2+, AO2-, AO3+, and AO3- of the analog output module U7.

[0162] This solution ensures normal operation while incorporating protective control measures such as phase sequence, liquid level, and blockage prevention. It also adds limit protection for the lifting platform's upper and lower limits, as well as upper and lower deceleration, guaranteeing system stability and reliability. Furthermore, a main control computer (1) is configured, which monitors the system's real-time status and operational data via its built-in CPU module. It employs digital sensing and analog adjustment to participate in the entire process of cylinder 6's movement; and utilizes dual-selection closed-loop control, allowing for program correction of long-term operating conditions. Compared to similar products in the industry, it reduces flatness error and improves equipment operating accuracy; flatness error has been reduced from 3% in the industry to 1.5%; equipment operation is smoother, effectively suppressing vibration and jerking during operation; service life is increased; and the risk of equipment collapse during operation is reduced.

[0163] After actual small-batch installation verification, the installed lifting platform dimensions are 4500mm*2500mm, with a maximum lifting height of 4200mm. Through continuous debugging and optimization, the control algorithm parameters (PID control + fuzzy control) were improved. After three days of batch measurements, data was measured at different positions during both the lifting and lowering processes. The measurement results are shown below. Figure 11 .

[0164] pass Figure 11According to the analysis of the table data, the flatness error of the lifting platform throughout the entire working stroke is basically distributed between 3mm and 12mm, which can ensure that the stability of the equipment operation reaches 1.5%. The operation process is basically stable, without shaking, jerking or other phenomena.

[0165] In some embodiments, such as Figures 12 to 15 As shown, the circuit of the hydraulic oil flow detector 4 includes an ultrasonic analog front end U9, a microcontroller unit U10, a display module U11, an analog switch U12, crystal oscillators Y1 and Y2, an inductor L1, a magnetic bead FB1, switches SW1, SW2, SW3, SW4, and SW5, resistors R1, R2, R4, and R5, capacitors C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C20, C21, C22, C23, C24, C25, C29, and C30, a resistance temperature detector (RTD1) and a resistance temperature detector (RTD2), and an interface J1.

[0166] Pin 16 of the ultrasonic analog front-end U9 is connected to one end of switch SW1 and grounded resistor R2. The other end of switch SW1 is connected to the external power supply terminal VBAT. Pin 21 of the ultrasonic analog front-end U9 is connected to one end of resistor R1, one end of RTD1, one end of RTD2 and grounded capacitor C9. The other end of resistor R1 is connected to pins 19 and 20 of the ultrasonic analog front-end U9. The other end of RTD1 is connected to pin 17 of the ultrasonic analog front-end U9. The other end of RTD2 is connected to pin 18 of the ultrasonic analog front-end U9. Pin 23 of the ultrasonic analog front-end U9 is connected to one end of crystal oscillator Y2 and grounded capacitor C8. Pin 24 of the ultrasonic analog front-end U9 is connected to the other end of crystal oscillator Y2 and grounded capacitor C7. Pin 31 of the ultrasonic analog front-end U9 is connected to one end of crystal oscillator Y1 and grounded capacitor C6. Pin 32 of the ultrasonic analog front-end U9 is connected to the other end of crystal oscillator Y1 and grounded capacitor C5.

[0167] Pin 5 of the ultrasonic analog front-end U9 is connected to one end of resistor R4. The other end of resistor R4 is connected to one end of capacitor C23 and the grounded transmitting transducer UPSTREAM PI EZO. The other end of capacitor C23 is connected to pin 27 of the ultrasonic analog front-end U9. Pins 3, 6, and 29 of the ultrasonic analog front-end U9 are connected to one end of inductor L1, and the grounded capacitors C3, C2, C1, C29, C17, and C18. The other end of inductor L1 is connected to the external power supply terminal VBAT. Pin 2 of the ultrasonic analog front-end U9 is connected to the grounded capacitor C4. Pin 7 of the ultrasonic analog front-end U9 is connected to one end of resistor R5. The other end of resistor R5 is connected to one end of capacitor C24 and the grounded receiving transducer DOWNSTREAM PI EZO. The other end of capacitor C24 is connected to pin 26 of the ultrasonic analog front-end U9.

[0168] Pins 8, 15, 9, 14, 13, and 10 of the ultrasonic analog front-end U9 are connected one-to-one with pins 18, 23, 21, 24, 4, and 6 of the microcontroller U10. Pin 12 of the ultrasonic analog front-end U9 is connected to pin 6 of the analog switch U12 and pin 3 of the microcontroller U10. Pin 11 of the ultrasonic analog front-end U9 is connected to pin 5 of the microcontroller U10 and pin 2 of the analog switch U12. Pin 7 of the microcontroller U10 is connected to pins J1-2 of interface J1. Pins 8 and... Pin 10 is connected to pins 38 and 39 of display module U11 in a one-to-one correspondence. Pin 13 of microcontroller U10 is connected to pins 30, 31, 32, 33, 34, 35, 36, 40, 25 and 26 of display module U11, pins 3 and 7 of analog switch U12, one end of capacitor C12 is connected to grounded capacitor 10, and the other end of capacitor C12 is connected to pin 24 of display module U11. Pins 20 and 19 of microcontroller U10 are connected to pins J1-1 and J1-3 of interface J1 in a one-to-one correspondence.

[0169] Pin 2 of microcontroller U10 is connected to grounded capacitor C13 and then connected to the external power supply terminal VBAT. Pin 22 of microcontroller U10 is connected to grounded capacitor C12 and then connected to the external power supply terminal VBAT. Pins 9 and 12 of microcontroller U10 are connected to one end of ferrite bead FB1, grounded capacitors C14, C15, and C16. The other end of ferrite bead FB1 is connected to the external power supply terminal VBAT. Pin 15 of microcontroller U10 is connected to grounded capacitor C20 and then connected to the external power supply terminal VBAT. Pin 16 of microcontroller U10 is connected to grounded capacitor C21. Pin 1 of microcontroller U10 is connected to pins 1 and 2 of switch SW2. Pins 3 and 4 of switch SW2 are grounded. Pin 14 of microcontroller U10 is connected to pins 1 and 2 of switch SW4. Pins 3 and 4 of switch SW4 are grounded. Pin 17 of microcontroller U10 is connected to pins 1 and 2 of switch SW3. Pins 3 and 4 of switch SW3 are grounded.

[0170] Pins 21 and 22 of display module U11 are connected to the two ends of capacitor C11 respectively. Pins 28 and 29 of display module U11 are connected to pins 5 and 1 of analog switch U12. Pins J1-6 of interface J1 are connected to the external power supply terminal VBAT. Pin 8 of analog switch U12 is connected to the grounded capacitor C25 and then connected to the external power supply terminal VBAT. Pins 2 and 5 of switch SW5 are connected to the power supply BAT. Pins 1 and 4 of switch SW5 are connected to the grounded capacitor C30 and then used as the power supply terminal VBAT. Pins 3 and 6 of switch SW5 are connected together.

[0171] In this embodiment, the ultrasonic analog front-end U9 is model MAX35101, the microcontroller unit U10 is model EFM32ZG110, the display module U11 is model EA DOGM163L-A, and the analog switch U12 is model MAX4721 EUA+.

[0172] The ultrasonic simulation front-end U9 is started by switch SW1, and the operating voltage is provided by switch SW5. Thermistors RTD1 and RTD2 provide temperature compensation, and crystal oscillators Y1 and Y2 provide the operating frequency. The microcontroller U10 controls the operation of the ultrasonic simulation front-end U9. The ultrasonic simulation front-end U9 outputs pulses to the transmitting transducer UPSTREAM PI EZO, which emits ultrasonic waves. The receiving transducer DOWNSTREAM PI EZO receives the ultrasonic waves and converts them into electrical signals, which are then transmitted to the microcontroller U10 through the ultrasonic simulation front-end U9. The microcontroller U10 displays the detection results through the display module U11.

[0173] In summary, several specific embodiments of the present invention have been disclosed. Without contradiction, the various embodiments can be freely combined to form new embodiments. That is, embodiments that are alternative solutions can be freely substituted for each other, but cannot be combined with each other; embodiments that are not alternative solutions can be combined with each other. These new embodiments are also part of the substantive content of the present invention.

[0174] The above embodiments describe several specific implementations of the present invention. However, those skilled in the art should understand that various changes or modifications can be made to these implementations without departing from the principles and essence of the present invention, but all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A control method for a lifting platform, characterized in that, Includes the following steps: S1. The control box receives position detection commands and flow detection commands from the main control computer; S2. The control box controls the position detector to detect the stroke of the hydraulic cylinder according to the position detection command; S3. The control box controls the hydraulic oil flow detector to detect the hydraulic oil flow of the oil cylinder according to the flow detection command; S4. The control box receives the position information fed back by the position detector and the flow information fed back by the hydraulic oil flow detector; S5. The control box uses PID control or fuzzy control to calculate the location information and flow information; S6. The control box controls the movement of the hydraulic cylinder by adjusting the opening of the servo valve according to the calculation results; S1 includes: S101. After receiving the position detection command and the flow detection command, the control box analyzes and processes the position detection command and the flow detection command to determine how many sampling cycles and the interval time of the sampling cycles are contained in the position detection command and the flow detection command. S102. If both the position detection command and the flow detection command have only one sampling period, the control box sends a working command to the position detector and the hydraulic oil flow detector; S103. If both the position detection command and the flow detection command have multiple sampling periods, the control box determines whether the number of sampling periods and the interval time of both are consistent. If they are consistent, the control box sends a synchronization command to the position detector and the hydraulic oil flow detector; otherwise, the control box sends a command error message to the main control computer.

2. The control method for the lifting platform according to claim 1, characterized in that, S2 include: The control box sends a timing sampling command to the position detector according to the number of sampling cycles and the interval time, so that the position detector performs timing detection on the stroke of the hydraulic cylinder.

3. The control method for the lifting platform according to claim 2, characterized in that, S3 includes: The control box sends a timing sampling command to the hydraulic oil flow detector according to the number of sampling cycles and the interval time, so that the hydraulic oil flow detector can perform timing detection of the hydraulic oil flow of the oil cylinder.

4. The control method for the lifting platform according to claim 3, characterized in that, S4 includes: S401. The control box receives location information and flow information; S402. The control box arranges the location information and flow information sequentially based on the sampling time sequence; S403. The control box binds the location information and flow information of the same sampling time sequence into detection data to obtain multiple detection data of different time sequences.

5. A control system for a lifting platform using the control method for a lifting platform according to any one of claims 1 to 4, characterized in that, include: The main control computer has a built-in CPU module, which is used to issue location detection commands and flow detection commands; The control box has a built-in PLC component for receiving position detection commands and flow detection commands; A position detector is connected to the control box and is controlled by the control box to detect the stroke of the hydraulic cylinder and obtain position information; A hydraulic oil flow detector is connected to the control box so that it can be controlled by the control box to detect the hydraulic oil flow of the oil cylinder and obtain flow information. A hydraulic pump station, connected to the control box, is equipped with a servo valve, the opening of which is controlled by the control box based on position and flow information. The hydraulic cylinder is connected to the servo valve.

6. The control system of the lifting platform according to claim 5, characterized in that, The main control computer is equipped with a memory, which is connected to the CPU module and stores a computer program that can run on the CPU module. When the CPU module executes the computer program, the CPU module controls the PLC component to work in order to implement the control method of the lifting platform as described in any one of claims 1 to 4.

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