Aerial work vehicle precision control method and system based on proportional valve

Abstract

This invention discloses a precise control method and system for aerial work platforms based on a proportional valve. The method includes inputting preset control parameters into a control device and operating it to output an initial current signal; acquiring the current signal in real time and converting it into a digital signal for transmission to an ARM processor; sequentially performing filtering, piecewise linearization, and PID dynamic compensation adjustment on the converted digital signal to generate a high-precision current command; based on the high-precision current command and combined with a preset piecewise mapping relationship between the current and the proportional valve opening degree, calculating and generating a control signal and outputting it to the drive module; the drive module analyzes the signal duty cycle and converts it into a drive current adapted to the proportional valve coil, inputting it to the proportional valve coil to precisely adjust the proportional valve opening degree; the proportional valve controls the precise movement of the aerial work platform, while the monitoring and protection module automatically locks the proportional valve and stops adjusting the opening degree when an abnormality is detected. This invention achieves precise control of the aerial work platform, improving operational stability, accuracy, and safety.

Description

Technical Field

[0001] This invention belongs to the field of engineering machinery control technology, and more specifically, relates to a precise control method and system for aerial work platforms based on proportional valves. Background Technology

[0002] As a crucial piece of equipment in the construction machinery field, the control precision and stability of aerial work platforms directly impact operational safety and efficiency. Traditional aerial work platforms often employ on / off solenoid valves, with a binary "on / off" control mode that cannot achieve continuous adjustment of valve opening and closing. This leads to sudden changes in hydraulic flow during start-up and shutdown, generating strong mechanical shocks and affecting the stability of the work platform. Furthermore, the lack of fine-tuning capabilities makes fine-tuning difficult in scenarios requiring precise positioning (such as equipment installation and high-altitude maintenance), failing to meet the demands of high-precision operations. While some existing aerial work platforms utilize proportional valve control systems, these largely rely on dedicated controllers for signal processing and valve actuation. The research and development and procurement costs of dedicated controllers are high, increasing the overall equipment cost; moreover, the signal transmission and processing flow of dedicated controllers is complex, prone to response delays, which may affect operational safety in emergency situations. Summary of the Invention

[0003] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a precise control method and system for aerial work platforms based on proportional valves. By establishing a linear mapping relationship between current and valve opening degree, introducing a dynamic compensation algorithm and an overload protection mechanism, precise control of the aerial work platform is achieved, improving its operational stability, accuracy, and safety.

[0004] To achieve the above objectives, according to one aspect of the present invention, a method for precise control of an aerial work platform vehicle based on a proportional valve is provided, comprising the following specific steps:

[0005] S100: Input preset control parameters into the HMI interface of the control device with current output function, and operate the control device to output the initial current signal.

[0006] S200: The initial current signal output in step S100 is acquired in real time with high precision, and the acquired analog initial current signal is converted into a digital signal and then transmitted to the ARM processor.

[0007] S300: 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.

[0008] S400: Based on the high-precision current command of S300, combined with the preset segmented mapping relationship between current and proportional valve opening degree, calculates the PWM duty cycle corresponding to the target opening degree to generate a PWM control signal and outputs it to the PWM drive module.

[0009] S500: The PWM drive module receives the PWM signal output by S400, analyzes the signal duty cycle and converts it into a drive current that adapts to the proportional valve coil, and inputs it to the proportional valve coil to accurately adjust the opening degree of the proportional valve.

[0010] S600: The proportional valve controls the actuator of the aerial work platform to achieve precise movement based on the drive adjustment results of S500. At the same time, 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 an abnormality is found after analysis and comparison by the ARM processor module, it triggers automatic locking of the current valve position of the proportional valve and stops its opening and closing adjustment.

[0011] Furthermore, the preset control parameters in step S100 include the output initial current range, the slope parameters of each segment in the piecewise linear mapping relationship between current and proportional valve opening degree, the signal sampling frequency threshold of the current acquisition and conversion module, the abnormal judgment threshold for the monitoring and protection module to trigger the valve position locking, and the adjustment range of the proportional valve opening degree; the abnormal judgment threshold for the electrical monitoring and protection module to trigger the valve position locking includes the upper current threshold, the lower current threshold, the upper limit value of the proportional valve coil current, and the upper limit value of the hydraulic system pressure.

[0012] Further, in step S200, when the current acquisition and conversion module converts the initial current signal into a digital current signal, it uses an ADC converter with a resolution of 12 bits or higher, and considers dynamic compensation. The conversion calculation model expression is as follows:

[0013]

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

[0015] Further, step S300 achieves filtering by constructing a multimodal fusion adaptive weighted filtering model: the interference type is identified by the instantaneous rate of change and periodic similarity of the signal, the interference type includes 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 allocation principle to output a filtered stable signal.

[0016] Further, the piecewise linearization process in step S300 includes:

[0017] Oil temperature and load pressure are collected by sensors and then normalized.

[0018] The initial current range is divided into k segments. Based on the normalized oil temperature and load pressure, and combined with the coupling variables, the preset basic compensation coefficients for each segment are dynamically corrected to eliminate nonlinear deviations. The calculation formula is as follows:

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

[0020] Among them, a j (n) represents the dynamic compensation coefficient for segment j, a j0 Let δ be the basic compensation coefficient for the j-th segment. T δ is the oil temperature correction factor. P T*(n) is the pressure correction factor, T*(n) is the normalized oil temperature, and P*(n) is the normalized load pressure.

[0021] The theoretical current is derived from the filtered signal using the corrected compensation coefficients:

[0022]

[0023] Among them, D f (n) represents the filtered signal;

[0024] According to the theoretical current I th (n) belongs to the interval [I j-1 ,I j The theoretical current derived from the filtered signal is then corrected by piecewise linearization. The linearized digital signal for this segment is calculated using the following formula:

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

[0026] Where ε is the coupling enhancement coefficient,

[0027] The final output is a linearized digital signal:

[0028]

[0029] Furthermore, in step S300, the PID dynamic compensation adjustment integrates the three mechanisms of PID control, fuzzy control, and immune control to establish a PID-fuzzy immune fusion adaptive compensation model for adjustment, including the following steps:

[0030] Step 1: Collect the actual current of the proportional valve coil and the attitude angle of the aerial work platform boom, and calculate the overall control deviation.

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

[0032] Where e(n) is the overall control deviation; w I The current deviation weighting coefficient; w θ e is the attitude angle deviation weighting coefficient; I norm(n) is the normalized current deviation; e θ norm(n) is the normalized current deviation.

[0033] Step 2: Combine the deviation e(n) and the rate of change of deviation. Divided into 7 fuzzy subsets, the PID parameters are dynamically adjusted using the Mamdani inference 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] Among them, K p0 K i0 K d0 These are the PID reference parameters;

[0036] Step 3: Calculate immune factors based on the accumulated deviation using the immune control mechanism, and dynamically decay and correct the PID integral term:

[0037]

[0038] Where Int(n) is the adjustment coefficient reflecting the relationship between the magnitude of the deviation and the intensity of the integral term suppression, I m (n) represents the immune factor at time n, β is the immune coefficient, γ is the cumulative bias threshold, and T s The sampling period is expressed in seconds (s).

[0039] The expression for the final current signal after compensation and adjustment is:

[0040]

[0041] Further, step S400 includes issuing a compensated current command I. c (n) Perform a security check; if it exceeds [I min ,I max If the output is within the specified range, a safe PWM signal will be output; otherwise, it will be converted to a standardized digital signal using the following formula:

[0042]

[0043] Based on the standardized digital signal, the piecewise linear mapping table configured by the HMI is invoked, according to I c (n) belongs to the current range [I j-1 ,I j ] Calculate the target opening degree O(n):

[0044]

[0045] The target opening degree is converted into the corresponding PWM duty cycle using the following calculation formula to generate a PWM control signal. After timing synchronization and edge sharpening, the signal is output to the drive module. At the same time, closed-loop verification ensures that the deviation between the feedback duty cycle analytical value and the calculated value is ≤±1%.

[0046]

[0047] Among them, O max Duty is the maximum opening degree of the proportional valve. min Duty max This refers to the effective duty cycle range of the proportional valve.

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

[0049]

[0050] Among them, Imin_drive I is the minimum drive current for starting the proportional valve. max_drive This is the rated current of the coil.

[0051] According to another aspect of the present invention, the present invention provides a precision control system for an aerial work platform based on a proportional valve, used to implement the steps of the above-described precision control method for an aerial work platform based on a proportional valve, characterized in that it includes:

[0052] Wireless remote control module: As a human-machine interface, it receives the operator's operation instructions and generates an initial current signal. It is equipped with an HM interface, which can set various parameters and display the current current value, proportional valve opening degree, oil temperature, load pressure and fault information.

[0053] 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 via an ADC converter, which is then transmitted to the ARM processor module.

[0054] ARM processor module: The core control unit of the system, which receives digital signals transmitted by the current acquisition and conversion module, and performs multimodal fusion adaptive filtering, bivariate coupling piecewise linearization processing, and PID-fuzzy immune dynamic compensation algorithm to generate PWM control signal parameters;

[0055] PWM drive module: Receives the PWM parameters output by the ARM processor module and converts the weak signal into the drive current required by the proportional valve coil through a power amplifier circuit;

[0056] Proportional valve actuator module: It adopts a pilot-operated proportional valve with a response time of <50ms, which converts the drive current into valve core displacement, controls the hydraulic oil flow, and drives the actuator of the aerial work platform to move; its mainstream hydraulic circuit interface is compatible.

[0057] Monitoring and Protection Module: Equipped with current and pressure sensors, it collects control current signals output by the control device, drive current output to the proportional valve coil from the PWM drive module, and main oil circuit pressure data transmitted by the hydraulic system pressure sensor in real time. The ARM processor module analyzes these data and compares them with corresponding preset thresholds. When an over-threshold is detected, a protection mechanism is triggered to lock the proportional valve and cut off the drive signal.

[0058] Furthermore, the interface of the hydraulic circuit of the proportional valve actuator module is compatible.

[0059] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0060] 1. This invention discloses a precise control method for aerial work platforms based on a proportional valve. After digital conversion of the current signal, it first uses multi-modal fusion adaptive filtering to specifically filter out composite noise such as high-frequency electromagnetic interference, operational jitter, and load fluctuations, outputting a stable signal to ensure smooth start-up and reduce hydraulic system shock. Then, it combines oil temperature and load pressure as dual variables for piecewise linearization compensation to eliminate the nonlinear deviation of "current-opening degree". Finally, it uses PID-fuzzy immune fusion dynamic compensation to correct signal fluctuations caused by load changes and pressure fluctuations. The three-level optimization is progressive to ensure that the opening degree of the proportional valve accurately follows the control command, guaranteeing control accuracy and improving operation precision by more than 40%. This solves the problems of poor start-stop stability and difficulty in fine-tuning of traditional aerial work platforms, and significantly improves the operational stability, accuracy, and safety of aerial work platforms.

[0061] 2. The present invention provides a precise control method for aerial work platforms based on a proportional valve. It uses a general-purpose control device with current output as the command input device, and relies on a low-cost and technologically mature ARM processor to complete core calculations such as signal filtering, linearization compensation, and PID adjustment. It is paired with a standardized PWM drive module to drive the proportional valve. The entire control link does not require a dedicated controller, which simplifies the control process and reduces costs.

[0062] 3. The present invention provides a precise control method for aerial work platforms based on a proportional valve. The opening degree of the proportional valve and the current value have a segmented linear relationship, and the slope of each segment of the linear relationship can be configured through the HMI interface of the remote controller. Users can flexibly adjust the system according to different work scenarios, thereby improving the adaptability of the system.

[0063] 4. The present invention provides a precise control method for aerial work platforms based on a proportional valve. The current acquisition and conversion module acquires current signals in real time, and the ARM core control unit continuously monitors the signal. When the current exceeds a preset threshold, the monitoring and protection module is immediately triggered to automatically lock the current valve position of the proportional valve and stop the opening and closing adjustment, thereby avoiding operational accidents under abnormal working conditions and providing dual protection for the safety of aerial workers and equipment.

[0064] 5. The present invention provides a precision control system for aerial work platforms based on a proportional valve. The proportional valve of the proportional valve execution module is directly compatible with the hydraulic circuit of the aerial work platform, eliminating the need to modify the main oil circuit of the aerial work platform and improving adaptability. Attached Figure Description

[0065] Figure 1 This is a flowchart of a precise control method for an aerial work platform vehicle based on a proportional valve, according to an embodiment of the present invention.

[0066] Figure 2 This is a current-opening characteristic curve of Embodiment 2 of the present invention;

[0067] Figure 3 This is a schematic diagram of the structure of a precision control system for an aerial work platform based on a proportional valve, according to an embodiment of the present invention. Detailed Implementation

[0068] To make the objectives, technical solutions, and advantages of this invention clearer, the invention 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 merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention 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 this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0070] Example 1

[0071] like Figure 1 As shown, this embodiment of the invention provides a precise control method for an aerial work platform vehicle based on a proportional valve, comprising the following specific steps:

[0072] Step S100: Signal Input and Initial Generation: Input preset control parameters into the HMI interface of the control device with current output function, and operate the control device to output the initial current signal;

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

[0074] The preset control parameters include the initial output current range, the slope parameters of each segment in the piecewise linear mapping relationship between current and proportional valve opening degree, the signal sampling frequency threshold of the current acquisition and conversion module, the abnormal judgment threshold for the monitoring and protection module to trigger valve position locking, and the adjustment range of the proportional valve opening degree. The abnormal judgment threshold for the electrical monitoring and protection module to trigger valve position locking includes the upper current limit threshold, the lower current limit threshold, 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 performs real-time high-precision acquisition of the initial current signal output in step S100, and converts the acquired analog initial current signal into a digital signal;

[0076] The current acquisition and conversion module uses a high-precision analog-to-digital converter (ADC)-based digital calculation model to convert the initial current signal. In addition, considering the timing characteristics of the signal acquisition and the error correction requirements, a dynamic sampling compensation term is introduced. The conversion calculation model expression is as follows:

[0077]

[0078] Where D(n) is the digital signal of the nth sampling point obtained after conversion; I in (n) represents the initial current signal output by the control device at the nth sampling moment, in mA; I in (n-1) is the initial current analog signal output by the control device at the (n-1)th sampling time, used to dynamically compensate for current fluctuations at adjacent sampling points, with units of mA; I min This refers to the minimum rated output current of the control device, measured in mA; I max The maximum rated output current of the control device is given in 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 at adjacent sampling points on the conversion accuracy, and to avoid digital signal jumps caused by instantaneous changes in current, with a value range of 0.1-0.3. This is a floor function that converts the floating-point calculation result after ADC conversion into an integer digital signal.

[0079] Furthermore, the current acquisition and conversion module captures the analog current signal output by the control device in real time at a sampling frequency of ≥1kHz, and converts it through I... min and I max To determine the effective conversion range and avoid saturation distortion caused by the signal exceeding the ADC range, the analog current signal is quantized into a digital signal using the ADC's conversion bit depth N, and then converted using the previous current signal I. in (n-1) and dynamic compensation coefficient k are used to correct the current fluctuations of adjacent sampling points, filter the instantaneous current fluctuations caused by remote control operation jitter and electromagnetic interference of hydraulic system, and output high-precision, low-fluctuation digital signals to improve the stability of aerial work vehicle movement.

[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 by step S200, with the goal of eliminating composite interference such as high-frequency electromagnetic interference, operation jitter interference and load fluctuation interference, it achieves accurate noise reduction by constructing a multi-modal fusion adaptive weighted filtering model.

[0082] When an aerial work platform vehicle is operating, the current signal is simultaneously affected by high-frequency electromagnetic interference (high-frequency pulsed), operational jitter interference (low-frequency periodic), and load fluctuation interference (slowly varying non-periodic). First, two interference identification indicators—signal instantaneous rate of change and periodic similarity—are used to quantify the instantaneous changes and periodic characteristics of the signal, dynamically identifying the type of interference currently affecting the signal. Specifically,

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

[0084] Periodic similarity ΔD2(n)=|D(n)-D(nT)|;

[0085] Interference types are identified based on the instantaneous rate of change and periodic similarity of the signal as follows:

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

[0087] If ΔD2(n) < λ2, it is determined to be an operation jitter interference;

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

[0089] Wherein, λ1 is the high-frequency interference threshold, taken as 2-3 times the signal standard deviation; λ2 is the periodic interference threshold, taken as 0.5 times the signal standard deviation; and λ3 is the slowly varying interference threshold, taken as 0.8 times the signal standard deviation. Each threshold is dynamically set based on the signal statistical characteristics, relating to the sampling frequency and the proportional valve response time, to adapt to different operating conditions.

[0090] Based on the identified interference type, three filtering modes are activated in a targeted manner: 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 weights of each mode are then assigned according to the interference type.

[0091] For high-frequency interference wavelet threshold denoising mode: the signal is decomposed into 2-level db4 wavelets, and soft thresholding is applied to the high-frequency coefficients. w The formula for calculating (n) is as follows:

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

[0093] Where, ω j,k For the high-frequency wavelet coefficients after thresholding, ω 0,k For low-frequency wavelet coefficients, ψ j,k (n), φ 0,k(n) represent the wavelet basis function and the scaling function, respectively.

[0094] For low-frequency interference recursive average filtering modes: calculate the mean value using m sampling points, D a The formula for calculating (n) is 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 the exponentially smoothed filtering mode with slowly varying disturbances: a smoothing coefficient α is introduced. e s(0.2≤α e (s≤0.5), smoothing filter result D e The formula for calculating (n) is as follows:

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

[0099] Based on the interference type identification results, assign weights w to each modality. w w a w e (w w +w a +w e =1), dynamically adjust the contribution of each filtering mode to achieve "interference type - filtering strategy" matching, and finally filter output Df(n) is:

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

[0101] The weight allocation rules for the three types of interference are as follows:

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

[0103] Operational 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] The filtered signal after weighted fusion not only retains the instantaneous control characteristics of the useful signal, but also reduces the signal fluctuation amplitude by more than 85%, providing a highly stable input for subsequent linearization processing.

[0106] S302: To address the coupling interference of oil temperature and load pressure on the linear relationship between "current-opening degree," a four-dimensional mapping relationship of "current-oil temperature-pressure-opening degree" is constructed. Piecewise linearization compensation eliminates the nonlinear deviation caused by multi-variable coupling, ensuring accurate matching of "current-opening degree" under all operating conditions. Specifically,

[0107] Considering the coupling interference of two key variables—oil temperature and load pressure—on the linear relationship of the aerial work platform, oil temperature affects hydraulic oil viscosity, and increased oil temperature leads to lag in valve position response in the low-current range; load affects the proportional valve thrust, and increased pressure leads to valve position saturation in the high-current range. Oil temperature and load pressure are treated as coupling variables. Data from sensors are collected and normalized to transform them into unified, quantified coupling variables.

[0108]

[0109] Among them, T min T min These are the minimum and maximum oil temperatures, respectively, in °C; P min P min These are the minimum and maximum load pressures, respectively, in MPa.

[0110] The initial current range of the preset control parameters is divided into k segments, and the preset basic compensation coefficients of each segment are dynamically corrected in combination with the coupling variables to eliminate nonlinear deviations.

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

[0112] Among them, a j (n) represents the dynamic compensation coefficient for segment j, a j0 Let δ be the basic compensation coefficient for the j-th segment. T =0.05-0.1 is the oil temperature correction factor (the compensation amount increases with the increase in oil temperature), δ P =0.03-0.08 is the pressure correction factor (the amount of compensation for pressure decreases as pressure increases).

[0113] Based on the dynamic compensation coefficient, the theoretical current derived from the filtered signal is corrected in segments using a compensation formula. Specifically, based on the theoretical current I... th (n) belongs to the interval [I j-1 I j The linearized digital signal for this section is calculated using the following compensation formula:

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

[0115] Where ε = 0.02-0.05 is the coupling enhancement coefficient, which strengthens the compensation effect of multiple variables on linearization.

[0116] The theoretical current is derived from the filtered signal as follows:

[0117]

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

[0119]

[0120] Where N is the resolution of the ADC converter.

[0121] The above linearization process controls the linearity error of "current-opening degree" to within 0.3% under all operating conditions. At the same time, the basic compensation coefficient can be flexibly adjusted through HMI to adapt to the hardware characteristics of different proportional valves.

[0122] S303: Converts the linearized digital signal into the corresponding target current command, combines it with the real-time acquired actual current signal of the proportional valve coil (reflecting the actual opening and closing state of the proportional valve), calculates the deviation between the two, runs the PID control algorithm through the ARM processor, dynamically adjusts according to the magnitude of the deviation, and outputs the PID-compensated signal after dynamically compensating and correcting the target command signal.

[0123] By employing a PID-fuzzy immune fusion adaptive compensation model, which integrates three mechanisms—PID control, fuzzy control, and immune control—the influence of load changes and continuous disturbances on the control accuracy of the proportional valve is eliminated. Fuzzy control adjusts PID parameters in real time to cope with sudden load changes, while immune control dynamically corrects the integral term to avoid integral saturation. Simultaneously, a multi-feedback closed loop of "current-valve position-operating posture" is introduced to achieve a triple effect of rapid response, precise suppression, and stable control against complex dynamic disturbances. Specifically,

[0124] Step 1: Collect multiple feedback signals to calculate deviation: Integrate two types of feedback signals: the actual current of the proportional valve (reflecting the valve position) and the boom attitude angle of the aerial work platform (reflecting the working state). After normalizing each signal, calculate the overall control deviation by weighting them together.

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

[0126] Where e(n) is the overall control deviation; w I The current deviation weighting coefficient; w θ e is the attitude angle deviation weighting coefficient; I norm(n) is the normalized current deviation; e θ norm(n) is the normalized current deviation.

[0127]

[0128] Among them, I fb (n) represents the actual current of the proportional valve at time n, in mA; θ(n) represents the boom attitude angle of the aerial work platform at time n, in radians; I ref (n)=I l (n) represents the target current at time n after linearization, in mA; θ ref (n) represents the target attitude angle at time n, in radians.

[0129] Step 2: Adjust the PID parameters using a fuzzy control mechanism to construct a fuzzy control rule base, where the input variables are the deviation e(n) and the rate of change of deviation. The output variable is the PID parameter correction amount ΔK p ΔK i ΔK d The deviation and its rate of change are divided into seven fuzzy subsets to adjust the PID baseline parameters (proportional, integral, and derivative coefficients) in real time, enabling rapid response to deviation fluctuations caused by sudden load changes. Specifically:

[0130] The fuzzy subset of the deviation and the rate of change of deviation is: e(n). (Negative large, negative medium, negative small, zero, positive small, positive medium, positive large);

[0131] Using the Mamdani inference method, the output correction is:

[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] Among them, K p0 K i0 K d0 These are the PID reference parameters, with units of mA, mA / s, and mA·s, respectively.

[0134] Step 3: Through the immune control mechanism, calculate the immune factor based on the cumulative deviation, dynamically decay and correct the PID integral term to avoid integral saturation caused by continuous interference. The calculation formula is as follows:

[0135]

[0136] Wherein, Int(n) is the adjustment coefficient reflecting the relationship between the magnitude of the deviation and the intensity of the integral term's suppression; m (n) represents the immune factor at time n, β is the immune coefficient, γ is the cumulative bias threshold, and T s The sampling period is expressed in seconds (s).

[0137] The expression for the final current signal after compensation and adjustment is:

[0138]

[0139] Step S400: Control Signal Generation: Based on the high-precision current command in S300, and combined with the preset piecewise mapping relationship between current and proportional valve opening degree, the PWM duty cycle corresponding to the target opening degree is calculated to generate a PWM (Pulse Width Modulation) control signal, which is then output to the PWM drive module. The mapping relationship is a piecewise linear relationship, and the slope of each segment is configured through the human-machine interface of the control device in step S100; specifically, it includes:

[0140] S401: Compensated current command I output from S303 c (n) Perform parsing and standardization; specifically,

[0141] Judgment 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 the error occurs, 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; if I 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 %; 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). Considering the hardware characteristics of the pilot-operated proportional valve (response time < 50ms), the conversion formula is as follows:

[0148]

[0149] Among them, O max Duty is the maximum opening degree (100%) of the proportional valve. min =5%, Duty max =95% is the effective duty cycle range of the proportional valve (to avoid the valve failing to operate due to an excessively low duty cycle, or the coil overheating due to an excessively high duty cycle), ensuring that the converted Duty(n) can both drive the proportional valve to accurately achieve the target opening and closing degree and meet the hardware safety operation requirements.

[0150] S403: Based on the calculated duty cycle, generate control signals adapted to the PWM drive module and perform timing calibration. Specifically,

[0151] The ARM processor generates a fixed-frequency PWM digital signal based on Duty(n) using its built-in PWM timer. This signal is output in alternating high and low digital form, and based on a timing reference of "sampling frequency ≥ 1kHz", it ensures that the period of the PWM signal is synchronized with the current sampling period (Ts ≤ 1ms), avoiding lag in the proportional valve opening adjustment due to timing misalignment. The generated PWM signal undergoes edge sharpening processing to reduce edge jitter during signal transmission and prevent high-frequency interference from causing current fluctuations in the proportional valve coil. This edge sharpening processing is achieved through the use of a filter capacitor and a freewheeling diode in the hardware driver circuit.

[0152] S404: Outputs the generated PWM control signal and performs adaptability verification. Specifically,

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

[0154] After receiving the signal, the PWM drive module feeds back the "signal reception status" and "current duty cycle resolution value" to the ARM processor in real time. The core control unit compares the feedback duty cycle resolution value with the calculated Duty(n). If the deviation is ≤±1%, the signal is considered to be properly adapted and proceeds to the next step of proportional valve driving. 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" to ensure the accuracy and stability of the signal drive.

[0155] Step S500: Proportional Valve Driving and Adjustment: The PWM drive module receives the PWM signal output from S400, analyzes the signal duty cycle, and converts it into a drive current adapted to the proportional valve coil. This current is then input to the proportional valve coil, driving the pilot-operated proportional valve with a response time of less than 50ms to adjust its opening degree. The proportional valve is directly compatible with the hydraulic circuit of the aerial work platform vehicle, requiring no modification to the main oil circuit of the vehicle. Specifically,

[0156] The PWM driver 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 into the PWM driver module performs real-time duty cycle analysis on the received PWM signal and calculates the high-level duty cycle (Duty) of the current PWM signal through high-frequency sampling (sampling frequency ≥ 10 times the PWM signal frequency). real (n), and calculate the target drive current I based on the "duty cycle-current mapping relationship". drive (n), specifically:

[0157]

[0158] Among them, I min_drive I is the minimum drive current for starting the proportional valve. max_drive This is the rated current of the coil.

[0159] The target current signal, after analysis, is amplified into a high-voltage drive signal for the adapter coil by the built-in power amplifier unit (using MOSFET or IGBT power devices) of the PWM drive module. This signal is then input to the pilot coil of the proportional valve to drive the proportional valve to quickly and accurately adjust its opening degree.

[0160] Step S600: Work vehicle motion control and protection: Based on the drive adjustment results of S500, the proportional valve controls the actuator of the aerial work vehicle to achieve precise movement. At the same time, 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 an abnormality is found after analysis and comparison by the ARM processor module, the monitoring and protection module is triggered to automatically lock the current valve position of the proportional valve and stop its opening and closing adjustment.

[0161] Example 2

[0162] In this embodiment of the invention, the aerial work platform is raised and lowered, and precise positioning is achieved using the method in Embodiment 1, including the following steps:

[0163] S1: Configure core parameters via the HMI interface of the wireless remote control: Set the remote control current output range to 16-80mA, corresponding to a proportional valve opening degree of 0-100%, where the slope k1 for the 16-32mA segment is 0.02 / 1mA, the slope k2 for the 32-48mA segment is 0.03 / 1mA, and the slope k3 for the 48-80mA segment is 0.025 / 1mA (e.g., ...). Figure 2 ); a preset speed mapping relationship is established where 16mA corresponds to a platform rise speed of 0.3m / s and 40mA corresponds to 0.8m / s, and the PID reference parameters (K) are configured synchronously. p =5.2mA, K i =0.8mA / s, K d =0.3mA·s).

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

[0165] S3: The ARM processor module performs three-level processing on the digital current signal: it uses multi-modal fusion filtering (wavelet denoising weight of 70% for high-frequency interference) to output a stable signal; it combines real-time oil temperature (-10℃-60℃) and load pressure (0-25MPa) for piecewise linearization compensation to correct the current-opening nonlinear deviation; and it dynamically adjusts parameters through PID-fuzzy immune algorithm to output the compensated current command.

[0166] S4: Perform safety verification on the compensated current command (limited to 16-80mA), and convert it into a standardized digital quantity D through inverse operation of ADC. c (n); Call the HMI's preset three-segment slope mapping table to calculate the target opening degree and the corresponding PWM duty cycle (5%-95%); Generate a PWM signal with a frequency of 1kHz, and output it to the PWM drive module after timing synchronization (matching the sampling period). Ensure that the duty cycle deviation is ≤±1% through closed-loop verification.

[0167] S5: The PWM drive module converts the signal into a 1-5A drive current, controls the pilot-operated proportional valve (response time < 50ms) to operate according to the target opening degree, and adjusts the hydraulic oil flow into the boom cylinder of the work vehicle;

[0168] S6: The actuator drives the platform to rise and fall at a set speed (0.3m / s or 0.8m / s), and monitors and protects the real-time current and main oil circuit pressure of the module; the ARM processor module dynamically optimizes the control parameters based on feedback, and finally achieves a platform positioning accuracy of ±2cm, which is 80% higher than the traditional system.

[0169] Example 3

[0170] like Figure 3 As shown in the figure, this embodiment of the invention provides a precision control system for an aerial work platform based on a proportional valve, used to implement the steps of the precision control method for an aerial work platform based on a proportional valve described in Embodiment 1. The system includes: a wireless remote control module, a current acquisition and conversion module, an ARM processor module, a PWM drive module, a proportional valve execution module, and a monitoring and protection module. The initial current signal generated by the wireless remote control module is acquired and converted into a digital signal by the current acquisition and conversion module. The ARM processor module performs signal optimization processing to generate a PWM control signal. The PWM drive module receives the control signal and converts it into a drive current. The proportional valve execution module adjusts the opening degree of the proportional valve to achieve precise control of the aerial work platform operation.

[0171] The wireless remote control module serves as a human-machine interface, receiving operation commands from the operator, generating an initial current signal, and equipped with an HM interface. It allows setting the initial current range, the slope parameters of each segment in the piecewise linear mapping relationship between the current and the proportional valve opening degree, the signal sampling frequency threshold of the current acquisition and conversion module, the current anomaly judgment threshold for the monitoring and protection module to trigger the valve position lock, and the adjustment range of the proportional valve opening degree, etc. The parameter configuration response time is ≤500ms, and it can display the current current value, proportional valve opening degree, oil temperature, load pressure, and fault information, etc.

[0172] The current acquisition 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. Its sampling frequency is ≥1kHz and the sampling accuracy is ±0.05mA.

[0173] The ARM processor module is the core control unit of the system. It receives the digital signals transmitted by the current acquisition and conversion module and performs multimodal fusion adaptive filtering, bivariate coupling piecewise linearization processing, and PID-fuzzy immune dynamic compensation algorithm to generate PWM control signal parameters. The multimodal 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 bivariate coupling piecewise linearization processing eliminates the nonlinear deviation caused by the bivariate 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 signal into the drive current required by the proportional valve coil through the MOSFET full-bridge power amplifier circuit.

[0175] The proportional valve actuator module uses a pilot-operated proportional valve with a response time of <50ms, which converts the drive current into valve core displacement, controls the hydraulic oil flow, and drives the boom and other actuators of the aerial work platform to move; its mainstream hydraulic circuit interface is compatible and directly compatible with the hydraulic circuit of the aerial work platform.

[0176] The monitoring and protection module is equipped with a current sensor and a pressure sensor to collect control current signals output by the control device, drive current output by the PWM drive module to the proportional valve coil, and main oil circuit pressure data transmitted by the hydraulic system pressure sensor in real time. These data are compared with corresponding preset thresholds. When an over-threshold is detected, a protection mechanism is triggered to lock the proportional valve and cut off the drive signal.

[0177] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A precise control method for an aerial work platform vehicle based on a proportional valve, characterized in that, The specific steps include the following: S100: Input preset control parameters into the HMI interface of the control device with current output function, and operate the control device to output the initial current signal. S200: The initial current signal output in step S100 is acquired in real time with high precision, and the acquired analog initial current signal is converted into a digital signal and then transmitted to the ARM processor. S300: 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. In step S300, the PID dynamic compensation adjustment integrates three mechanisms: PID control, fuzzy control, and immune control, and establishes a PID-fuzzy immune fusion adaptive compensation model for adjustment, including the following steps: Step 1: Collect the actual current of the proportional valve coil and the attitude angle of the aerial work platform boom, and calculate the overall control deviation: ； in, e ( n This represents the overall control deviation. w I This is the current deviation weighting coefficient; w θ This is the attitude angle deviation weighting coefficient; e I norm( n () represents the normalized current deviation; e θ norm( n () represents the normalized current deviation; Step 2: Adjust the deviation e ( n ) and rate of change of deviation ( n )= e ( n )− e ( n -1) Divide into 7 fuzzy subsets, and dynamically adjust PID parameters using the Mamdani inference method: ； in, K p0 , K i0 , K d0 These are the PID reference parameters; Step 3: Calculate immune factors based on the accumulated deviation using the immune control mechanism, and dynamically decay and correct the PID integral term: ； ； Where Int(n) is an adjustment coefficient reflecting the relationship between the magnitude of the deviation and the intensity of the integral term's suppression. I m ( n )for n Immunological factors at all times β For the immune coefficient, γ This is the cumulative deviation threshold. T s The sampling period is expressed in seconds (s). The expression for the final current signal after compensation and adjustment is: ； S400: Based on the high-precision current command of S300, combined with the preset segmented mapping relationship between current and proportional valve opening degree, calculates the PWM duty cycle corresponding to the target opening degree to generate a PWM control signal and outputs it to the PWM drive module. S500: The PWM drive module receives the PWM signal output by S400, analyzes the signal duty cycle and converts it into a drive current that adapts to the proportional valve coil, and inputs it to 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 to achieve precise movement based on the drive adjustment results of S500. At the same time, 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 an abnormality is found after analysis and comparison by the ARM processor module, it triggers automatic locking of the current valve position of the proportional valve and stops its opening and closing adjustment.

2. The method for precise control of an aerial work platform based on a proportional valve 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 piecewise linear mapping relationship between current and proportional valve opening degree, the signal sampling frequency threshold of the current acquisition and conversion module, the abnormal judgment threshold for the monitoring and protection module to trigger valve position locking, and the adjustment range of the proportional valve opening degree; the abnormal judgment threshold for the monitoring and protection module to trigger valve position locking includes the upper current threshold, the lower current threshold, the upper limit value of the proportional valve coil current, and the upper limit value of the hydraulic system pressure.

3. The method for precise control of an aerial work platform based on a proportional valve according to claim 2, characterized in that, In step S200, when the current acquisition and conversion module converts the initial current signal into a digital current signal, it uses an ADC converter with a resolution of 12 bits or higher, and considers dynamic compensation. The conversion calculation model expression is as follows: ； in, D ( n ) is the first one obtained after conversion n The digital signal at each sampling point; I in ( n ) is the output of the control device n The initial current signal at each sampling time is expressed in mA. I in ( n -1) is the output of the control device. n -1 initial current analog signal at sampling time, in mA; I min This is the minimum rated output current of the control device, in mA. I max This is the maximum rated output current of the control device, in mA. N ≥12 represents the resolution of the ADC converter; k is the dynamic compensation coefficient; ⌊⋅⌋ is the floor function.

4. The method for precise control of an aerial work platform based on a proportional valve according to claim 3, characterized in that, Step S300 achieves filtering by constructing a multimodal fusion adaptive weighted filtering model: the interference type is identified by the instantaneous rate of change and periodic similarity of the signal, the interference type includes 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 allocation principle to output a stable filtered signal.

5. The method for precise control of an aerial work platform based on a proportional valve according to claim 4, characterized in that, The piecewise linearization process in step S300 includes: Oil temperature and load pressure are collected by sensors and then normalized. The initial current range is divided into k The segment, based on normalized oil temperature and load pressure, and combined with coupled variables, dynamically corrects the preset basic compensation coefficients for each interval to eliminate nonlinear deviations. The calculation formula is as follows: ； in, a j ( n )for j Segment dynamic compensation coefficient, a j0 For the first j Segment basic compensation coefficient, δ T This is the oil temperature correction factor. δ P This is the pressure correction factor. T* ( n (This refers to the normalized oil temperature.) P* ( n The normalized load pressure is denoted as . The theoretical current is derived from the filtered signal using the corrected compensation coefficients: ； in, D f ( n () represents the filtered signal; According to theoretical current I th ( n ) The interval to which [ I j−1 , I j The theoretical current derived from the filtered signal is then corrected by piecewise linearization. The linearized digital signal for this segment is calculated using the following formula: ； in, ε For coupling enhancement coefficient, The final output is a linearized digital signal: 。 6. The method for precise control of an aerial work platform based on a proportional valve according to claim 5, characterized in that, Step S400 includes issuing a command for the compensated current. I c ( n Perform a security check; if it exceeds [ I min , I max If the output is within the specified range, a safe PWM signal will be output; otherwise, it will be converted to a standardized digital signal using the following formula: ； Based on the standardized digital signal, the piecewise linear mapping table configured by the HMI is invoked, according to... I c ( n The current range to which it belongs [ I j−1 , I j ] Calculate the target opening degree O ( n ): ； The target opening degree is converted into the corresponding PWM duty cycle using the following calculation formula to generate a PWM control signal. After timing synchronization and edge sharpening processing, the signal is output to the drive module. At the same time, closed-loop verification is used to ensure that the deviation between the feedback duty cycle analytical value and the calculated value is ≤±1%. ； in, O max This represents the maximum opening degree of the proportional valve. Duty min , Duty max This refers to the effective duty cycle range of the proportional valve.

7. The method for precise control of an aerial work platform based on a proportional valve according to claim 6, characterized in that, In step S500, the drive current is calculated as follows: ； in, I min_drive This is the minimum drive current for starting the proportional valve. I max_drive This is the rated current of the coil.

8. A precision control system for an aerial work platform based on a proportional valve, used to implement the steps of a precision control method for an aerial work platform based on a proportional valve as described in any one of claims 1-7, characterized in that, include: Wireless remote control module: As a human-machine interface, it receives the operator's operation instructions and generates an initial current signal. It is equipped with an HM interface, which can set various parameters and 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 via an ADC converter, which is then transmitted to the ARM processor module. ARM processor module: The core control unit of the system, which receives digital signals transmitted by the current acquisition and conversion module, and performs multimodal fusion adaptive filtering, bivariate coupling piecewise linearization processing, and PID-fuzzy immune dynamic compensation algorithm to generate PWM control signal parameters; The PID-fuzzy dynamic compensation adjustment integrates three major mechanisms: PID control, fuzzy control, and immune control. A PID-fuzzy immune fusion adaptive compensation model is established for adjustment, including the following steps: Step 1: Collect the actual current of the proportional valve coil and the attitude angle of the aerial work platform boom, and calculate the overall control deviation: ； in, e ( n This represents the overall control deviation. w I This is the current deviation weighting coefficient; w θ This is the attitude angle deviation weighting coefficient; e I norm( n () represents the normalized current deviation; e θ norm( n () represents the normalized current deviation; Step 2: Adjust the deviation e ( n ) and rate of change of deviation ( n )= e ( n )− e ( n -1) Divide into 7 fuzzy subsets, and dynamically adjust PID parameters using the Mamdani inference method: ； in, K p0 , K i0 , K d0 These are the PID reference parameters; Step 3: Calculate immune factors based on the accumulated deviation using the immune control mechanism, and dynamically decay and correct the PID integral term: ； ； Where Int(n) is an adjustment coefficient reflecting the relationship between the magnitude of the deviation and the intensity of the integral term's suppression. I m ( n )for n Immunological factors at all times β For the immune coefficient, γ This is the cumulative deviation threshold. T s The sampling period is expressed in seconds (s). The expression for the final current signal after compensation and adjustment is: ； PWM drive module: Receives the PWM parameters output by the ARM processor module and converts the weak signal into the drive current required by the proportional valve coil through a power amplifier circuit; Proportional valve actuator module: It adopts a pilot-operated proportional valve with a response time of <50ms, which converts the drive current into valve core displacement, controls the hydraulic oil flow, and drives the actuator of the aerial work platform to move. Monitoring and protection module: It is equipped with current sensor and pressure sensor to collect control current signal output by control device in real time, drive current output to proportional valve coil by PWM drive module, and main oil circuit pressure data transmitted by hydraulic system pressure sensor. These are compared with corresponding preset thresholds. When the threshold is exceeded, the protection mechanism is triggered to lock proportional valve and cut off drive signal.

9. A precision control system for an aerial work platform based on a proportional valve according to claim 8, characterized in that, The interface of the hydraulic circuit of the proportional valve actuator module is compatible.

Images