Precise control method and system for overhead working truck based on proportional valve

Abstract

The invention discloses an accurate control method and system for an overhead working truck based on a proportional valve, and the method comprises the steps: inputting a preset control parameter in a control device, and operating the control device to output an initial current signal; collecting current signals in real time, converting the current signals into digital signals, and transmitting the digital signals to the ARM processor; sequentially performing filtering, piecewise linearization processing and PID dynamic compensation adjustment on the converted digital signal to generate a high-precision current instruction; based on the high-precision current instruction, a control signal is calculated and generated by combining a preset segmentation mapping relation between current and the opening degree of the proportional valve and is output to the driving module; the driving module analyzes the signal duty ratio, converts the signal duty ratio into driving current matched with a proportional valve coil, and inputs the driving current into the proportional valve coil to accurately adjust the opening and closing degree of the proportional valve; the proportional valve controls the high-altitude operation vehicle to move accurately, and meanwhile, the monitoring and protecting module automatically locks the proportional valve when monitoring abnormity, and opening and closing degree adjustment is stopped. Accurate control over the overhead working truck is achieved, and operation stability, accuracy and safety are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of engineering machinery control, and more particularly relates to a precise control method and system for a high-altitude operation vehicle based on a proportional valve. BACKGROUND

[0002] As an important equipment in the field of engineering machinery, the control precision and stability of the high-altitude operation vehicle directly affect the operation safety and efficiency. The traditional high-altitude operation vehicle adopts a switch type electromagnetic valve, and its control mode is a binary mode of "on-off", which cannot realize continuous adjustment of the opening degree of the valve. This leads to a sudden change in hydraulic flow during the start-stop process of the equipment, resulting in strong mechanical impact and affecting the stability of the operation platform. At the same time, due to the lack of fine adjustment capability, it is difficult to fine-tune in scenes requiring precise positioning (such as equipment installation and high-altitude maintenance), and it is difficult to meet the high-precision operation demand. Some high-altitude operation vehicles in the prior art use proportional valve control systems, but most of them rely on special controllers to realize signal processing and valve driving. The development and procurement cost of the special controller is high, which increases the overall cost of the equipment; and the signal transmission and processing process of the special controller is complex, which is easy to cause response delay and may affect the operation safety in emergency conditions. SUMMARY

[0003] In view of the above defects or improvement needs of the prior art, the present application provides a precise control method and system for a high-altitude operation vehicle based on a proportional valve, which realizes precise control of the high-altitude operation vehicle by establishing a linear mapping relationship between current and valve opening degree, introducing a dynamic compensation algorithm and an overload protection mechanism, and improves the operation stability, precision and safety of the high-altitude operation vehicle.

[0004] To achieve the above purpose, according to one aspect of the present application, the present application provides a precise control method for a high-altitude operation vehicle based on a proportional valve, comprising the following specific steps:

[0005] S100: inputting preset control parameters on the HMI interface of a control device with current output function, and outputting an initial current signal by operating the control device;

[0006] S200: collecting the initial current signal output by step S100 in real time with high precision, and transmitting the collected initial current signal in analog form to an ARM processor after converting it into a digital signal;

[0007] S300: the ARM processor receives the converted digital signal of step S200 and sequentially performs filtering, piecewise linearization processing and PID dynamic compensation adjustment to generate a high-precision current instruction;

[0008] S400: Based on the high-precision current instruction of S300, combined with the preset segmented mapping relationship of current and proportional valve opening degree, the PWM duty cycle corresponding to the target opening degree is calculated to generate a PWM control signal output to the PWM driving module;

[0009] S500: The PWM driving module receives the PWM signal output by S400, parses the signal duty cycle and converts it into a driving current suitable for the proportional valve coil, and inputs it to the proportional valve coil to accurately adjust the proportional valve opening degree;

[0010] S600: The proportional valve controls the actuator of the aerial work platform according to the driving adjustment result of S500 to realize precise motion, while the monitoring and protection module monitors the current safety threshold, proportional valve coil current upper limit value and hydraulic system pressure upper limit value in real time. When an abnormality is found through ARM processor module analysis and comparison, the current valve position is automatically locked and the opening degree adjustment is stopped.

[0011] Further, the preset control parameters in step S100 include the output initial current range, the slope parameters of each segment in the segmented linear mapping relationship of current and proportional valve opening degree, the signal sampling frequency threshold of the current acquisition and conversion module, the abnormality determination threshold for triggering the lock valve position of the monitoring and protection module, and the adjustment range of the proportional valve opening degree. The abnormality determination threshold for triggering the lock valve position of the monitoring and protection module includes the current upper limit threshold, the current lower limit threshold, the proportional valve coil current upper limit value and the hydraulic system pressure upper limit value.

[0012] Further, in step S200, when the current acquisition and conversion module converts the initial current signal into a digital current signal, a 12-bit or higher resolution ADC converter is used, and dynamic compensation is considered. The conversion calculation model expression is:

[0013]

[0014] where D(n) is the digital signal of the nth sampling point after conversion; I in (n) is the initial current signal output by the control device at the nth sampling time; I in (n-1) is the initial current analog signal output by the control device at the (n-1)th sampling time; I min is the minimum rated value of the output current of the control device; I max is the maximum rated value of the output current of the control device; N≥12 is the resolution of the ADC converter; k is the dynamic compensation coefficient; is the floor function.

[0015] Further, the step S300 implements the filtering processing by constructing a multi-modal fusion adaptive weighting filtering model: identifying the interference types including high-frequency electromagnetic interference, operation jitter interference and load fluctuation interference through signal instantaneous change rate and cycle similarity; starting wavelet threshold denoising, recursive average filtering and exponential smoothing filtering modes respectively for different interference types, and weighting and fusing the output signals of each mode according to a preset weight distribution principle to output the filtered stable signal.

[0016] Further, the segmented linearization processing of the step S300 includes:

[0017] The oil temperature and load pressure are collected by the sensor and normalized;

[0018] The initial current range is divided into k segments, and based on the normalized oil temperature and load pressure, the dynamic correction of the preset basic compensation coefficient of each interval is combined with the coupling variable to eliminate the nonlinear deviation, and the calculation formula is as follows:

[0019] a j (n)=a j0 ×[1+δ T ×T * (n)-δ P ×P * (n)];

[0020] Wherein, a j (n) is the jth dynamic compensation coefficient, a j0 is the jth basic compensation coefficient, δ T is the oil temperature correction coefficient, δ P is the pressure correction coefficient, T*(n) is the normalized oil temperature, and P*(n) is the normalized load pressure.

[0021] The theoretical current is obtained by backstepping from the filtered signal using the corrected compensation coefficient:

[0022]

[0023] Wherein, D f (n) is the filtered signal;

[0024] According to the interval [I j-1 ,I j ] to which the theoretical current I th (n) belongs, the segmented linearization correction is performed on the theoretical current backstepped from the filtered signal to calculate the linearized digital signal of the current segment, and the correction formula is as follows:

[0025] I l (n)=I th (n)+a j (n)×(I th (n)-Ij-1 ) x [1 + ε x (T * (n) + P * (n))] ;

[0026] wherein ε is a coupling enhancement coefficient,

[0027] Final output linearized digital signal:

[0028]

[0029] Further, in step S300, the PID dynamic compensation adjustment fuses PID control, fuzzy control and immune control three mechanisms, establishes a PID-fuzzy immune fusion adaptive compensation model for adjustment, including the following steps:

[0030] Step one: collect the proportional valve coil actual current and aerial work vehicle boom posture angle, calculate the comprehensive control deviation:

[0031] e(n) = w I x e I，norm (n) + w θ x e θ，nor m(n) ;

[0032] wherein e(n) is the comprehensive control deviation; w I is the current deviation weight coefficient; w θ is the posture angle deviation weight coefficient; e I , norm(n) is the normalized current deviation; e θ , norm(n) is the normalized current deviation.

[0033] Step two: divide the deviation e(n) and the deviation rate into 7 fuzzy subsets, dynamically adjust the PID parameters through Mamdani reasoning method:

[0034] K p (n) = K p0 + ΔK p (n), K i (n) = K i0 + ΔK i (n), K d (n) = K d0 + ΔK d (n) ;

[0035] wherein K p0 , K i0 , K d0 are PID reference parameters.

[0036] Step three: through the immune control mechanism, the immune factor is calculated based on the deviation accumulation amount, and the integral term of the PID is dynamically attenuated and corrected:

[0037]

[0038] wherein Int(n) is a regulation coefficient reflecting the correlation between the deviation size and the integral term suppression intensity, I m (n) is the immune factor at time n, β is the immune coefficient, γ is the deviation accumulation threshold, T s is the sampling period, and the unit is s.

[0039] Then, the expression of the final current signal after compensation and adjustment is:

[0040]

[0041] Further, step S400 includes safety verification on the compensated current command I c (n), and if it exceeds the range [I min ,I max ], a safety guard PWM signal is output, otherwise it is converted into a standardized digital signal through the following formula:

[0042]

[0043] Based on the standardized digital signal, a segmented linear mapping table configured by HMI is called, and the target opening degree O(n) is calculated according to the current interval [I c ,I j-1 ] to which I j (n) belongs:

[0044]

[0045] The target opening degree is converted into a corresponding PWM duty cycle to generate a PWM control signal through the following calculation formula, which is output to the driving module after timing synchronization and edge sharpening processing, and at the same time, through closed-loop verification, it is ensured that the deviation between the feedback duty cycle analysis value and the calculation value is ≤±1%:

[0046]

[0047] wherein O max is the maximum opening degree of the proportional valve, Duty min , Duty max is the effective duty cycle range of the proportional valve.

[0048] Further, in step S500, the driving current is calculated as follows:

[0049]

[0050] wherein Imin_drive Imin is the minimum drive current for starting the proportional valve max_drive Icoil is the coil rated current.

[0051] According to another aspect of the present application, the present application provides a proportional valve-based aerial work platform precision control system for implementing the above-mentioned proportional valve-based aerial work platform precision control method, characterized in that the system comprises:

[0052] a wireless remote control module, which is configured as a human-machine interface, receives operation instructions of an operator, generates an initial current signal, is provided with an HM interface, can set various parameters, and can display current values, opening degrees of the proportional valve, oil temperatures, load pressures, and fault information;

[0053] a current acquisition and conversion module, which receives the initial current signal output by the wireless remote control module, performs high-precision sampling, and converts the analog initial current signal into a digital signal through an ADC converter and transmits the digital signal to the ARM processor module;

[0054] an ARM processor module, which is a core control unit of the system, receives the digital signal transmitted by the current acquisition and conversion module, performs multi-modal fusion adaptive filtering, double-variable coupled segmented linearization processing, and PID-fuzzy immune dynamic compensation algorithm to generate PWM control signal parameters;

[0055] a PWM drive module, which receives the PWM parameters output by the ARM processor module, converts a weak current signal into a drive current required by a proportional valve coil through a power amplification circuit;

[0056] a proportional valve execution module, which adopts a pilot proportional valve with a response time of <50 ms, converts the drive current into a spool displacement, controls a hydraulic oil flow, and drives an aerial work platform actuator to move; and the proportional valve execution module is compatible with a main hydraulic circuit interface;

[0057] a monitoring and protection module, which is internally provided with a current sensor and a pressure sensor, acquires control current signals output by a control device, drive currents output by the PWM drive module to proportional valve coils, and main oil path pressure data transmitted by a hydraulic system pressure sensor in real time, analyzes the data through the ARM processor module, respectively compares the data with corresponding preset threshold values, and triggers a protection mechanism to lock the proportional valve and cut off a drive signal when an over-threshold value is detected.

[0058] Further, the proportional valve execution module is compatible with a hydraulic circuit interface.

[0059] Overall, the above technical solutions conceived by the present application can achieve the following beneficial effects compared with the prior art:

[0060] 1. A precise control method for an aerial work platform based on a proportional valve, which comprises the following steps: after the current signal is digitized, it is filtered through multi-modal fusion adaptive filtering, and composite noise such as high-frequency electromagnetic interference, operation jitter and load fluctuation is filtered out, so that a stable signal is output, the starting is smooth, and the impact on the hydraulic system is reduced; then, the signal is compensated by piecewise linearization in combination with oil temperature and load pressure, so that the non-linear deviation of the current-opening degree is eliminated; finally, the signal fluctuation caused by load mutation and pressure fluctuation is corrected through PID-fuzzy immune fusion dynamic compensation, so that the opening degree of the proportional valve accurately follows the control instruction, the control precision is ensured, the control precision is improved by more than 40%, the problems of poor starting and stopping stability and difficult fine adjustment of the traditional aerial work platform are solved, and the operation stability, precision and safety of the aerial work platform are greatly improved.

[0061] 2. The precise control method for an aerial work platform based on a proportional valve, which comprises the following steps: a general control device with current output is used as an instruction input device, the core operations such as signal filtering, linearization compensation and PID adjustment are completed by relying on an ARM processor with low cost and mature technology, and a standardized PWM driving module is used to realize proportional valve driving, so that the whole control link does not need a special controller for transfer, the control process is simplified, and the cost is reduced.

[0062] 3. The precise control method for an aerial work platform based on a proportional valve, wherein the opening degree of the proportional valve and the current value have a piecewise linear relationship, and the slope of each linear relationship can be configured through an HMI interface of a remote controller, so that the user can flexibly adjust it according to different operation scenes, and the adaptability of the system is improved.

[0063] 4. The precise control method for an aerial work platform based on a proportional valve, which comprises the following steps: a current acquisition and conversion module is used to acquire the current signal in real time, an ARM core control unit continuously monitors the signal, and when it is detected that the current exceeds a preset threshold, a monitoring and protection module is triggered immediately, the current valve position of the proportional valve is automatically locked, and the opening degree adjustment is stopped, so that operation accidents under abnormal conditions are avoided, and double protection is provided for the safety of aerial work personnel and equipment.

[0064] 5. The precise control system for an aerial work platform based on a proportional valve, wherein the proportional valve of the proportional valve execution module is directly compatible with the hydraulic circuit of the aerial work platform, and the main oil circuit of the aerial work platform does not need to be modified, so that the adaptability is improved. BRIEF DESCRIPTION OF DRAWINGS

[0065] Figure 1 The flowchart of the precise control method for an aerial work platform based on a proportional valve according to the embodiment of the present application;

[0066] Figure 2 The current-opening degree characteristic curve diagram according to the embodiment 2 of the present application;

[0067] Figure 3 FIG. 1 is a structural schematic diagram of a proportional valve-based aerial work platform precise control system according to an embodiment of the present application. DETAILED DESCRIPTION

[0068] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0069] It should be understood that when used in the specification and the appended claims, the terms "comprise" and "include" indicate the presence of described features, integers, steps, operations, elements, and / or components, but do not exclude one or more other features, integers, steps, operations, elements, components, and / or sets thereof.

[0070] Embodiment 1

[0071] As shown in FIG. 1, the present application provides a proportional valve-based aerial work platform precise control method, which comprises the following specific steps: Figure 1

[0072] Step S100: signal input and initial generation: input preset control parameters on the HMI interface of the operating device with current output function, and output initial current signal by operating the operating device;

[0073] The initial current signal is used to associate the target opening degree of the proportional valve;

[0074] The preset control parameters include the output initial current range, the slope parameters of each segment in the segmented linear mapping relationship between current and proportional valve opening degree, the signal sampling frequency threshold of the current acquisition and conversion module, the abnormality determination threshold of the monitoring and protection module triggering the lock valve position, and the adjustment range of the proportional valve opening degree. The abnormality determination threshold of the monitoring and protection module triggering the lock valve position includes the upper limit threshold of the current, the lower limit threshold of the current, the upper limit value of the proportional valve coil current, and the upper limit value of the hydraulic system pressure.

[0075] Step S200: signal acquisition and conversion: the current acquisition and conversion module acquires the initial current signal output by step S100 in real time with high precision, and converts the acquired initial current signal in analog form into a digital signal;

[0076] ​The current acquisition and conversion module adopts a digital calculation model based on high-precision analog-to-digital conversion (ADC) for initial current signal conversion, and introduces a dynamic sampling compensation term in combination with the timing characteristics of signal acquisition and error correction requirements. The conversion calculation model expression is as follows:

[0077]

[0078] Wherein, D(n) is the digital signal of the nth sampling point after conversion; I in (n) is the initial current signal output by the control device at the nth sampling time, with units of mA; I in (n-1) is the initial current analog signal output by the control device at the (n-1)th sampling time, used for dynamic compensation of current fluctuations of adjacent sampling points, with units of mA; I min is the minimum rated value of the output current of the control device, with units of mA; I max is the maximum rated value of the output current of the control device, with units of mA; N is the resolution of the ADC converter, N≥12; k is the dynamic compensation coefficient, used to correct the influence of current fluctuations of adjacent sampling points on conversion accuracy, to avoid digital signal jumping due to current transient changes, with a value range of 0.1-0.3; is a floor function that converts the floating-point calculation result after ADC conversion to an integer-type digital signal.

[0079] Further, the current acquisition and conversion module captures the analog current signal output by the control device in real time at a sampling frequency of ≥1 kHz, determines the effective conversion interval through I min and I max to avoid saturation distortion caused by signals exceeding the ADC range, quantizes the analog current signal to a digital signal using the ADC conversion bit number N, and corrects the current fluctuations of adjacent sampling points through the previous-time current signal I in (n-1) and the dynamic compensation coefficient k, filters current transient fluctuations caused by remote controller operation jitter and hydraulic system electromagnetic interference, and outputs a high-precision, low-fluctuation digital signal to improve the motion stability of the aerial work platform.

[0080] Step S300: Signal optimization processing: the ARM processor receives the digital signal converted in step S200 and sequentially performs filtering, piecewise linearization processing, and PID dynamic compensation adjustment to generate a high-precision current command; including the following steps:

[0081] S301: For the digital signal converted in step S200, a multi-modal fusion adaptive weighted filtering model is constructed to achieve precise denoising, aiming to eliminate composite interference such as high-frequency electromagnetic interference, operation jitter interference, and load fluctuation interference.

[0082] When the aerial work platform is working, the current signal is affected by high-frequency electromagnetic interference (high-frequency pulse), operation jitter interference (low-frequency periodicity) and load fluctuation interference (slowly changing non-periodicity). Firstly, the signal instantaneous change rate and the period similarity are quantified to dynamically identify the interference type of the current signal by two interference identification indexes, specifically,

[0083] The instantaneous change rate of the signal ΔD1(n) = |D(n) - D(n-1)|;

[0084] The period similarity ΔD2(n) = |D(n) - D(n-T)|;

[0085] The interference type is identified based on the instantaneous change rate and the period similarity of the signal as follows:

[0086] If ΔD1(n) > λ1, it is determined that the high-frequency electromagnetic interference;

[0087] If ΔD2(n) < λ2, it is determined that the operation jitter interference;

[0088] If λ3 < ΔD1(n) ≤ λ1 and ΔD2(n) ≥ λ2, it is determined that the load fluctuation interference.

[0089] Wherein, λ1 is the high-frequency interference threshold, which is 2-3 times the standard deviation of the signal, λ2 is the period interference threshold, which is 0.5 times the standard deviation of the signal, and λ3 is the slowly changing interference threshold, which is 0.8 times the standard deviation of the signal. The thresholds are dynamically set based on the signal statistical characteristics, the associated sampling frequency and the proportional valve response time, which are suitable for different working conditions.

[0090] Based on the identified interference type, three filtering modes are started, including wavelet threshold denoising for high-frequency interference, recursive average filtering for low-frequency interference and exponential smoothing filtering for slowly changing interference, and the weights of each mode are allocated according to the interference type;

[0091] For the wavelet threshold denoising mode for high-frequency interference: the signal is decomposed by db4 wavelet for 2 layers, the high-frequency coefficients are processed by soft threshold, and D w (n) is calculated as follows:

[0092] D w (n) = Σ j，k ω j，k · ψ j，k (n) + ω 0,k · φ 0,k (n);

[0093] Wherein, ω j,k is the high-frequency wavelet coefficient after threshold processing, ω 0,k is the low-frequency wavelet coefficient, ψ j,k (n) and φ 0,k(n) are respectively wavelet basis function and scale function.

[0094] For low-frequency interference recursive average filtering mode: take m sampling points to calculate mean, D a (n) is calculated as follows:

[0095]

[0096] Where D(i) is the digital signal of the i-th sampling point (i = n, n-1, n-2,..., n-m+1).

[0097] For slowly varying interference exponential smoothing filtering mode: introduce smoothing coefficient α e s(0.2≤α e s≤0.5), the smoothing filtering result D e (n) is calculated as follows:

[0098] D e (n) = α e s×D(n)+(1-α e s)×D e (n-1);

[0099] According to the interference type identification result, assign the weights w w , w a , w e (w w +w a +w e =1) of each mode, dynamically adjust the contribution degree of each filtering mode, realize the matching of "interference type-filtering strategy", and finally the filtering output Df(n) is:

[0100] D f (n) = w w ×D w (n) + w a ×D a (n) + w e ×D e (n);

[0101] Wherein, the weight allocation rules of three kinds of interference types are:

[0102] High-frequency electromagnetic interference: w w =0.7, w a =0.2, w e =0.1;

[0103] Operation jitter interference: w w =0.1, w a =0.7, w e =0.2;

[0104] Load fluctuation interference: w w = 0.2, w a = 0.1, w e = 0.7.

[0105] By weighted fusion of the output filtered signal, both the instantaneous control characteristics of the useful signal are retained, and the signal fluctuation amplitude is reduced by more than 85%, providing a high stability input for subsequent linearization processing.

[0106] S302: For the coupling interference of the oil temperature and the load pressure on the "current-opening degree" linear relationship, a "current-oil temperature-pressure-opening degree" four-dimensional mapping relationship is constructed, and the nonlinear deviation caused by the multivariable coupling is eliminated through piecewise linearization compensation, so as to ensure the precise matching of "current-opening degree" under all working conditions, specifically,

[0107] Considering the coupling interference of the high-altitude operation vehicle oil temperature and the load pressure on the linear relationship, the oil temperature affects the hydraulic oil viscosity, and the oil temperature rise will cause the small current section valve position response lag, the load affects the proportional valve thrust, and the pressure increase will cause the valve position saturation in the large current section. The oil temperature and the load pressure are taken as the coupling variables, the oil temperature and the load pressure are collected by sensors and normalized, and they are converted into unified quantitative coupling variables:

[0108]

[0109] Where, T min , T min are the minimum and maximum values of the oil temperature, respectively, in ℃; P min , P min are the minimum and maximum values of the load pressure, respectively, in MPa;

[0110] The initial current range of the preset control parameter is divided into k sections, and the basic compensation coefficient of each interval is dynamically corrected combined with the coupling variable, so as to eliminate the nonlinear deviation:

[0111] a j (n) = a j0 × [1 + δ T × T * (n) - δ P × P * (n)];

[0112] Where, a j (n) is the jth dynamic compensation coefficient, a j0 is the jth basic compensation coefficient, δ T = 0.05-0.1 is the oil temperature correction coefficient (the compensation amount increases with the increase of the oil temperature), and δ P = 0.03-0.08 is the pressure correction coefficient (the compensation amount decreases with the increase of the pressure).

[0113] Based on the dynamic compensation coefficient, the theoretical current of the filtered signal is corrected by the compensation formula, specifically, according to the theoretical current I th (n) of the interval [I j-1 , I j ], the linearized digital signal of the interval is calculated by the following compensation formula:

[0114] I l (n) = I th (n) + a j (n) × (I th (n) - I j -1) × [1 + ε × (T * (n) + P * (n)];

[0115] Wherein, ε = 0.02-0.05 is the coupling enhancement coefficient, which strengthens the compensation effect of multivariable on linearization,

[0116] The theoretical current is obtained by the filtered signal as follows:

[0117]

[0118] The final linearized digital signal D l (n) is:

[0119]

[0120] Wherein, N is the resolution of ADC converter.

[0121] Through the above linearization processing, the current-opening degree linearity error under all working conditions is controlled within 0.3%, and the basic compensation coefficient can be adjusted flexibly through HMI to adapt to different proportional valve hardware characteristics.

[0122] S303: Convert the linearized digital signal into the corresponding target current command, combine the real-time collected proportional valve coil actual current signal (reflecting the real opening and closing state of the proportional valve), calculate the deviation between the two; run the PID control algorithm through the ARM processor, dynamically adjust according to the deviation size, and output the PID compensated signal after dynamically compensating and correcting the target command signal.

[0123] Through the PID-fuzzy immune fusion adaptive compensation model, the PID control, fuzzy control and immune control three mechanisms are fused to eliminate the influence of load change, continuous disturbance and the like on the control accuracy of the proportional valve, the PID parameters are adjusted in real time through the fuzzy control to respond to the sudden load, the integral term is dynamically corrected through the immune control to avoid integral saturation, and the "current-valve position-operation posture" multi-feedback closed loop is introduced to realize the triple effects of fast response, accurate suppression and stable control on the complex dynamic disturbance, specifically,

[0124] Step one: collect multi-feedback signals to calculate deviation: two types of feedback signals, i.e., the actual current of the proportional valve (reflecting the valve position) and the arm posture angle of the aerial work vehicle (reflecting the operation state), are normalized and then fused to calculate the comprehensive control deviation through a weighting coefficient:

[0125] e(n)=w I ×e I,norm (n)+w θ ×e θ,norm (n);

[0126] Wherein, e(n) is the comprehensive control deviation; w I is the current deviation weight coefficient; w θ is the posture angle deviation weight coefficient; e I , norm(n) is the normalized current deviation; e θ , norm(n) is the normalized current deviation.

[0127]

[0128] Wherein, I fb (n) is the actual current of the proportional valve at n time, in mA; θ(n) is the arm posture angle of the aerial work vehicle at n time, in rad; I ref (n)=I l (n) is the target current after linearization at n time, in mA; θ ref (n) is the target posture angle at n time, in rad.

[0129] Step two: adjust the PID parameters through the fuzzy control mechanism to build a fuzzy control rule base, wherein the input variables are the deviation e(n) and the deviation change rate The output variables are the PID parameter correction amounts ΔK p , ΔK i , ΔK d , the deviation and the deviation change rate are divided into 7 fuzzy subsets to adjust the PID reference parameters (proportion, integral and differential coefficients) in real time, to quickly respond to the deviation fluctuation caused by the sudden load, specifically:

[0130] The deviation and the deviation change rate fuzzy subsets are: e(n), (negative large, negative medium, negative small, zero, positive small, positive medium, positive large);

[0131] The output correction amount is obtained by using the Mamdani reasoning method:

[0132] K p (n) = K p0 + ΔK p (n), K i (n) = K i0 + ΔK i (n), K d (n) = K d0 + ΔK d (n);

[0133] wherein K p0 , K i0 , K d0 are PID reference parameters, with units of mA, mA / s, and mA·s, respectively.

[0134] Step three: Based on the deviation accumulation amount, the immune factor is calculated through the immune control mechanism, and the integral term of the PID is dynamically attenuated and corrected to avoid integral saturation caused by continuous disturbance. The calculation formula is as follows:

[0135]

[0136] wherein Int(n) is a regulation coefficient reflecting the correlation between the deviation size and the suppression strength of the integral term; I m (n) is the immune factor at time n, β is the immune coefficient, γ is the deviation accumulation threshold, T s is the sampling period, with a unit of s.

[0137] Then the expression of the final current signal after compensation adjustment is:

[0138]

[0139] Step S400: Control signal generation: Based on the high-precision current instruction of S300, the PWM duty cycle corresponding to the target opening and closing degree is calculated to generate a PWM (pulse width modulation) control signal output to the PWM drive module, combined with the pre-set segmented mapping relationship between the current and the proportional valve opening and closing degree. The mapping relationship is a segmented linear relationship, and the slope of each segment is configured through the human-computer interaction interface of the control device in step S100. Specifically, it includes:

[0140] S401: Analyze and standardize the compensated current instruction I c (n) output by S303; specifically,

[0141] determine I c(n) Whether it is within the preset effective current range [I min ,I max ](I min I max (These are the rated upper and lower limits of the remote control's output current, determined by hardware parameters.) If I c (n) min or I c (n)>I max If I is not found, the abnormal signal handling mechanism is triggered, and a safety-maintaining PWM signal is output (to maintain the current valve position of the proportional valve) to prevent malfunction of the proportional valve due to out-of-range commands; c (n) Within the valid interval, I within the valid interval c (n) is converted into a normalized digital signal D. c (n), the ARM controller determines D c The digital range to which (n) belongs can be directly matched with the corresponding "current-opening linear formula" conversion formula. The ADC inverse operation in step S200 is as follows:

[0142]

[0143] S402: Based on the preset linear piecewise slope parameter in step S100, the ARM processor uses the standardized digital signal D c (n) Call the "current-opening degree piecewise linear mapping table" pre-stored in the system, according to I c (n) belongs to the current range [I j-1 ,I j The target opening degree O(n) is calculated by matching the corresponding linear mapping formula:

[0144]

[0145] Where O(n) is the target opening degree of the proportional valve at time n, in percentage; this formula ensures I c The precise correspondence between O(n) and O(n) adapts to the control accuracy requirements under different operating conditions.

[0146] The "current-opening degree piecewise linear mapping table" is generated by the slope parameters of each segment configured in the HMI interface in step S100, and includes the current range [I j-1 ,I j ] and the corresponding opening interval [O j-1 O j The mapping relationship is given by ], where j = 1, 2, ..., k, and k ≥ 2 is the number of segments.

[0147] ​Since the opening degree of the proportional valve is linearly controlled by the duty cycle of the PWM signal, the target opening degree O(n) is converted into the corresponding PWM duty cycle Duty(n). In combination with the hardware characteristics (response time < 50 ms) of the pilot proportional valve, the conversion formula is:

[0148]

[0149] wherein O max is the maximum opening degree of the proportional valve (100%), Duty min = 5%, Duty max = 95% is the effective duty cycle range of the proportional valve (to avoid too low duty cycle leading to valve inaction and too high duty cycle leading to coil overheating), ensuring that the converted Duty(n) can not only drive the proportional valve to accurately reach the target opening degree, but also meet the hardware safety operation requirements.

[0150] S403: Based on the calculated duty cycle, a control signal suitable for the PWM driving module is generated, and timing calibration is performed. Specifically,

[0151] The ARM processor generates a frequency-fixed PWM digital signal according to Duty(n) through the built-in PWM timer, the signal is output in the form of digital high-low level alternation, and based on the timing reference of "sampling frequency ≥ 1 kHz", the period of the PWM signal is synchronized with the current sampling period (Ts ≤ 1 ms), avoiding the proportional valve opening degree adjustment lag caused by timing misalignment; the generated PWM signal is subjected to edge sharpening processing to reduce the edge jitter in the signal transmission process and avoid high-frequency interference leading to proportional valve coil current fluctuation. The edge sharpening processing is realized through the cooperation of the filter capacitor and the freewheeling diode of the hardware driving circuit.

[0152] S404: The generated PWM control signal is output and adaptability verification is performed. Specifically,

[0153] The ARM processor outputs the calibrated PWM digital signal to the PWM driving module, and at the same time sends a "signal ready" instruction through a hardware interface (such as SPI, GPIO) to trigger the driving module to enter the signal receiving state, ensuring the reliability of signal transmission.

[0154] After receiving the signal, the PWM driving module feeds back the "signal receiving state" and "current duty cycle analysis value" to the ARM processor, and the core control unit compares the feedback duty cycle analysis value with the calculated Duty(n). If the deviation is ≤ ± 1%, it is determined that the signal adaptation is normal, and the next proportional valve driving is entered; if the deviation is > ± 1%, the PWM signal is immediately regenerated and output until the deviation meets the requirements, forming a closed loop of "generation-output-verification-correction", ensuring the accuracy and stability of signal driving.

[0155] Step S500: proportional valve driving and adjusting: the PWM driving module receives the PWM signal output by S400, analyzes the duty cycle of the signal and converts it into a driving current input to the proportional valve coil, drives the pilot proportional valve with a response time of less than 50ms to adjust its opening degree, and the proportional valve is directly compatible with the hydraulic circuit of the aerial work platform, without the need to modify the main oil circuit of the aerial work platform; specifically,

[0156] The PWM driving module receives the PWM signal output by the ARM processor through a hardware interface (such as GPIO, SPI or a dedicated PWM interface), the microcontroller (MCU) built-in the PWM driving module analyzes the duty cycle of the received PWM signal in real time, calculates the high-level duty cycle Duty real (n) of the current PWM signal through high-frequency sampling (sampling frequency ≥ 10 times the PWM signal frequency), and converts the target driving current I drive (n) according to the "duty cycle-current mapping relationship", specifically:

[0157]

[0158] Where, I min_drive is the minimum driving current for starting the proportional valve, and I max_drive is the rated current of the coil.

[0159] The PWM driving module built-in power amplification unit (using MOSFET or IGBT power devices) amplifies the analyzed target current signal into a high-voltage driving signal suitable for the coil, and inputs it to the proportional valve pilot coil to drive the proportional valve to quickly and accurately adjust the opening degree.

[0160] Step S600: aerial work vehicle motion control and protection: the proportional valve controls the actuator of the aerial work vehicle to realize precise motion according to the driving and adjusting results of S500, and the monitoring and protection module monitors the current safety threshold, the upper limit of the proportional valve coil current and the upper limit of the hydraulic system pressure in real time; when the ARM processor module analyzes and compares and an abnormality occurs, the monitoring and protection module is triggered to automatically lock the current valve position of the proportional valve and stop the adjustment of its opening degree.

[0161] Example 2

[0162] In the embodiment of the application, the aerial work platform is lifted and precisely positioned by the method in Example 1, including the following steps:

[0163] S1: Through the HMI interface of the wireless remote controller, configure the core parameters: set the remote controller current output range 16-80 mA corresponding to the proportional valve 0-100% opening degree, wherein the 16-32 mA segment has a slope k1=0.02 / 1 mA, the 32-48 mA segment has a slope k2=0.03 / 1 mA, and the 48-80 mA segment has a slope k3=0.025 / 1 mA (for example Figure 2 ); preset the 16 mA corresponding to the platform rising speed 0.3 m / s and the 40 mA corresponding to the speed mapping relationship 0.8 m / s, and synchronously configure the PID reference parameters (K p =5.2 mA, K i =0.8 mA / s, K d =0.3 mA·s).

[0164] S2: The wireless remote controller outputs a control current, which is collected by a high-precision sensor (precision 0.1% FS) of a current collection and conversion module, and is converted into a digital signal (16 mA corresponding to D=1024, and 80 mA corresponding to D=4095) by a 12-bit ADC converter (sampling frequency 1 kHz).

[0165] S3: The ARM processor module performs three-level processing on the digitized current signal: adopts a multi-modal fusion filter (wavelet denoising weight 70% when high-frequency interference) to output a stable signal; performs segmented linear compensation in combination with real-time oil temperature (-10℃-60℃) and load pressure (0-25 MPa) to correct the current-opening degree nonlinearity deviation; and dynamically adjusts parameters through a PID-fuzzy immune algorithm to output the compensated current command.

[0166] S4: The compensated current command is subjected to safety verification (limited to 16-80 mA), is converted into a standardized digital quantity D c (n) through ADC inverse operation; a three-segment slope mapping table preset by the HMI is called to calculate the target opening degree and the corresponding PWM duty cycle (5%-95%); a PWM signal with a frequency of 1 kHz is generated, is output to the PWM drive module after time sequence synchronization (matching the sampling period), and the duty cycle deviation is ensured to be ≤±1% through closed-loop verification.

[0167] S5: The PWM drive module converts the signal into a 1-5 A drive current to control the pilot proportional valve (response time <50 ms) to act according to the target opening degree, so as to adjust the hydraulic oil flow into the working vehicle boom cylinder.

[0168] S6: The actuator drives the platform to rise according to the set speed (0.3 m / s or 0.8 m / s), and the real-time current and main oil line pressure are monitored and protected by the monitoring and protection module; the ARM processor module dynamically optimizes the control parameters according to the feedback, and finally realizes the platform positioning accuracy ±2 cm, which is improved by 80% compared with the traditional system.

[0169] Example 3

[0170] As Figure 3 shown, the embodiment of the application provides a high-altitude work vehicle precision control system based on a proportional valve, which is used to realize the steps of the high-altitude work vehicle precision control method based on a proportional valve described in embodiment 1, and includes a wireless remote control module, a current collection and conversion module, an ARM processor module, a PWM drive module, a proportional valve execution module, and a monitoring and protection module. The wireless remote control module generates an initial current signal, the current collection and conversion module collects and converts the signal into a digital signal, the ARM processor module generates a PWM control signal after signal optimization processing, the PWM drive module receives the control signal and converts it into a driving current, and the proportional valve execution module adjusts the opening degree of the proportional valve to realize precise control of the high-altitude work vehicle operation.

[0171] The wireless remote control module serves as a human-computer interaction interface, receives operation instructions of an operator, generates an initial current signal, is equipped with an HM interface, and can set the initial current range, the slope parameters of each segment in the piecewise linear mapping relationship between the current and the opening degree of the proportional valve, the signal sampling frequency threshold of the current collection and conversion module, the current abnormality judgment threshold for triggering the lock valve position of the monitoring and protection module, and the adjustment range of the opening degree of the proportional valve, etc. The parameter configuration response time is ≤500 ms, and the current value, the opening degree of the proportional valve, the oil temperature, the load pressure, and fault information, etc. can be displayed.

[0172] The current collection and conversion module receives the initial current signal output by the wireless remote control module, and performs high-precision sampling. The analog initial current signal is converted into a digital signal by a 12-bit or higher ADC converter and transmitted to the ARM processor module. The sampling frequency is ≥1 kHz, and the sampling accuracy is ±0.05 mA.

[0173] The ARM processor module is the core control unit of the system, receives the digital signal transmitted by the current collection and conversion module, performs multi-modal fusion adaptive filtering, double-variable coupled piecewise linearization processing, and PID-fuzzy immune dynamic compensation algorithm to generate PWM control signal parameters. The multi-modal fusion adaptive filtering includes three filtering modes: wavelet threshold denoising to suppress high-frequency interference, recursive average filtering to suppress low-frequency interference, and exponential smoothing filtering to suppress slowly varying interference. The double-variable coupled piecewise linearization processing eliminates the nonlinear deviation caused by the double-variable coupling of oil temperature and load pressure.

[0174] The PWM drive module receives the PWM parameters (duty cycle 5%-95%) output by the ARM processor module, and converts the weak electric signal into the driving current required by the proportional valve coil through the MOSFET full-bridge structure power amplification circuit.

[0175] The proportional valve execution module adopts a pilot proportional valve with a response time < 50 ms, converts the driving current into a spool displacement, controls the hydraulic oil flow, and drives the boom of the aerial work platform and other execution mechanisms to move; the main hydraulic circuit interface is compatible with the hydraulic circuit of the aerial work platform.

[0176] The monitoring and protection module is internally provided with a current sensor and a pressure sensor, which collect the control current signal output by the control device, the driving current output by the PWM driving module to the proportional valve coil, and the main oil way pressure data transmitted by the hydraulic system pressure sensor, and respectively compare them with the corresponding preset threshold value, and when the threshold value is detected, the protection mechanism is triggered to lock the proportional valve and cut off the driving signal.

[0177] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present application and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A proportional valve-based precision control method for an aerial work platform, characterized in that, Comprise the following specific steps: S100: input the preset control parameters on the HMI interface of the operating device with current output function, and output the initial current signal by operating the operating device; S200: real-time high-precision collection is carried out to the initial current signal output by step S100, and the collected initial current signal in analog form is converted into digital signal and then transmitted to the ARM processor; S300: the ARM processor receives the digital signal converted by step S200, and sequentially performs filtering, segmented linearization processing and PID dynamic compensation adjustment to generate high-precision current instruction; S400: based on the high-precision current instruction of S300, combining the preset segmented mapping relationship between current and proportional valve opening degree, the PWM duty cycle corresponding to the target opening degree is calculated to generate PWM control signal and output to the PWM driving module; S500: the PWM driving module receives the PWM signal output by S400, analyzes the signal duty cycle and converts it into driving current suitable for the proportional valve coil, and inputs it into the proportional valve coil to accurately adjust the opening degree of the proportional valve; S600: the proportional valve controls the actuator of the aerial work platform vehicle to realize accurate motion according to the driving adjustment result of S500, and the monitoring and protection module monitors the current safety threshold, the proportional valve coil current upper limit value and the hydraulic system pressure upper limit value in real time; when the ARM processor module analyzes and compares and an abnormality occurs, the current valve position is automatically locked and the opening degree adjustment is stopped.

2. The precise control method of a proportioning valve-based aerial work vehicle according to claim 1, characterized in that, The preset control parameters in step S100 include the output initial current range, the slope parameters of each segment in the segmented linear mapping relationship between current and proportional valve opening degree, the signal sampling frequency threshold of the current collection and conversion module, the abnormality judgment threshold for triggering the lock valve position of the monitoring and protection module, and the adjustment range of the proportional valve opening degree; the abnormality judgment threshold for triggering the lock valve position of the monitoring and protection module includes the current upper limit threshold, the current lower limit threshold, the proportional valve coil current upper limit value and the hydraulic system pressure upper limit value.

3. The precise control method of a proportioning valve-based aerial work vehicle according to claim 2, characterized in that, In step S200, when the current collection and conversion module converts the initial current signal into digital current signal, an ADC converter with 12-bit or more resolution is used, and dynamic compensation is considered, and the conversion calculation model expression is: Wherein, D(n) is the digital signal of the nth sampling point after conversion; I in (n) is the initial current signal of the nth sampling time output by the control device, with mA as the unit; I in (n-1) is the initial current analog signal of the n-1th sampling time output by the control device, with mA as the unit; I min is the minimum rated value of the output current of the control device, with mA as the unit; I max is the maximum rated value of the output current of the control device, with mA as the unit; N≥12 is the resolution of the ADC converter; k is the dynamic compensation coefficient; is the floor function.

4. The precise control method of a proportioning valve-based aerial work vehicle according to claim 3, characterized in that, In step S300, filtering is realized by constructing a multi-modal fusion adaptive weighted filtering model: the interference types are identified by signal instantaneous change rate and cycle similarity, including high-frequency electromagnetic interference, operation jitter interference and load fluctuation interference; for different interference types, wavelet threshold denoising, recursive average filtering and exponential smoothing filtering modes are started respectively, and the output signals of each mode are weighted and fused according to the preset weight distribution principle to output the filtered stable signal.

5. The precise control method of a proportioning valve-based aerial work vehicle according to claim 4, characterized in that, The segmented linearization processing in step S300 includes: The oil temperature and load pressure are collected by the sensor and normalized; The initial current range is divided into k segments, and based on the normalized oil temperature and load pressure, the coupling variable is used to dynamically correct the preset basic compensation coefficient of each interval to eliminate nonlinear deviation, and the calculation formula is as follows: a j (n) = a j0 × [1 + δ T × T * (n) - δ P × P * (n)] ; wherein a j (n) is a j-segment dynamic compensation coefficient, a j0 is a j-segment base compensation coefficient, δ T is an oil temperature correction coefficient, δ P is a pressure correction coefficient, T*(n) is a normalized oil temperature, and P*(n) is a normalized load pressure. The theoretical current is obtained by backstepping from the filtered signal using the corrected compensation coefficient: where D f (n) is the filtered signal; The theoretical current I th (n) is linearized in the interval [I j-1 , I j ] in which the filtered signal is located, and the linearized digital signal is calculated by the following formula: I l (n) = I th (n) + a j (n) x (I th (n) - I j-1 ) x [1 + ε x (T * (n) + P * (n))] ; Wherein, ε is the coupling enhancement coefficient, The final output linearized digital signal is:

6. The precise control method of a proportioning valve-based aerial work vehicle according to claim 5, characterized in that, In step S300, the PID dynamic compensation adjustment fuses PID control, fuzzy control and immune control, establishes a PID-fuzzy immune fusion adaptive compensation model for adjustment, including the following steps: Step one: collect the actual current of the proportional valve coil and the attitude angle of the aerial work platform, and calculate the comprehensive control deviation: e(n) = w I x e I,norm (n) + w θ x e θ,norm (n); where e(n) is the integrated control error; w I is the current error weight coefficient; w θ is the attitude angle error weight coefficient; e I is the normalized current error; e θ is the normalized current error; Step two: the deviation e(n) and the deviation rate of change PID parameters are dynamically adjusted by Mamdani reasoning method through 7 fuzzy subsets K p (n) = K p0 + ΔK p (n), K i (n) = K i0 + ΔK i (n), K d (n)) = K d0 + ΔK d (n); wherein K p0 , K i0 , K d0 are PID reference parameters; Step three: through the immune control mechanism, calculate the immune factor based on the deviation accumulation, and dynamically attenuate and correct the PID integral term: Wherein, Int(n) is the adjustment coefficient reflecting the correlation between the deviation size and the integral term suppression strength, I m (n) is the immune factor at time n, β is the immune coefficient, γ is the deviation accumulation threshold, T s is the sampling period, with s as the unit; The expression of the final current signal after compensation adjustment is:

7. The precise control method of a proportioning valve-based aerial work vehicle according to claim 6, characterized in that, Step S400 includes compensating the current command I c (n) performing a safety check, if exceeding the range [I min ,I max ] output a safety protection PWM signal, otherwise convert to a normalized digital signal through the following formula: The piecewise linear mapping table configured by the HMI is called based on the normalized digital signal, and the target opening degree O(n) is calculated according to the I c (n) of the current interval to which the user belongs j-1 ,I j ​ The target opening degree is converted into the corresponding PWM duty ratio through the following calculation formula to generate a PWM control signal, which is then output to the drive module after timing synchronization and edge sharpening processing. At the same time, through closed-loop verification, the deviation between the feedback duty ratio analytical value and the calculated value is ensured to be ≤±1%: Where, O max Duty min Duty max is the effective duty range of the proportional valve.

8. The proportional valve-based precision control method for a high-altitude work vehicle according to claim 7, characterized in that, In step S500, the drive current is calculated as follows: where I min_drive is the minimum drive current for the proportional valve to start, I max_drive is the coil rated current.

9. A proportional valve based aerial work platform precision control system for implementing the steps of a proportional valve based aerial work platform precision control method according to any one of claims 1 to 8, characterized in that, Including: Wireless remote control module: as a human-computer interaction interface, it receives the operation instructions of the operator, generates an initial current signal, is equipped with an HM interface, can set various parameters, and can display the current current value, proportional valve opening degree, oil temperature, load pressure and fault information; Current acquisition and conversion module: receives the initial current signal output by the wireless remote control module, performs high-precision sampling, and converts the analog initial current signal into a digital signal through an ADC converter and transmits it to the ARM processor module; ARM processor module: as the core control unit of the system, it receives the digital signal transmitted by the current acquisition and conversion module, performs multi-modal fusion adaptive filtering, double-variable coupled segmented linearization processing, and PID-fuzzy immune dynamic compensation algorithm to generate PWM control signal parameters; PWM drive module: receives the PWM parameters output by the ARM processor module, and converts the weak current signal into the drive current required by the proportional valve coil through a power amplification circuit; Proportional valve execution module: uses a pilot proportional valve with a response time < 50 ms to convert the drive current into a valve core displacement, control the hydraulic oil flow, and drive the aerial work platform actuator to move; Monitoring and protection module: equipped with current sensors and pressure sensors, real-time acquisition of control current signals output by the control device, drive current output to the proportional valve coil by the PWM drive module, main oil line pressure data transmitted by the hydraulic system pressure sensor, etc. are compared with the corresponding preset threshold value respectively, when the threshold value is detected, the protection mechanism is triggered to lock the proportional valve and cut off the drive signal.

10. The proportional valve-based overhead working truck precision control system according to claim 9, characterized in that, The interface of the proportional valve execution module hydraulic circuit is compatible.

Images