An excavator electrical circuit virtual connection fault online detection method and system

Abstract

This application discloses an online detection method and system for loose connections in excavator electrical circuits. The method includes: identifying the current working condition based on the acquired excavator operating status signal, and determining an adaptive threshold for the working condition, including a detection cycle and a high-frequency energy threshold; based on the detection cycle, calculating five characteristic parameters for each circuit based on the acquired multi-circuit signals, including the proportion of high-frequency energy, signal fluctuation coefficient, equivalent contact resistance change rate, voltage change rate extreme value, and amplitude jump amplitude; performing a preliminary loose connection judgment based on the characteristic parameters and corresponding thresholds, generating a suspected loose connection flag bit for the corresponding circuit, and obtaining a preliminary loose connection judgment result; based on the preliminary loose connection judgment result, performing a secondary verification based on the electrical topology to distinguish between loose connections at common nodes and single-circuit loose connections; if it is a single-circuit loose connection, determining the type of single-circuit loose connection based on the five characteristic parameters, namely, a contact oxidation type loose connection, a contact insufficient pressure type loose connection, or a terminal loose type loose connection.

Description

Technical Field

[0001] This application belongs to the field of lighting control technology for engineering machinery, and relates to an online detection method and system for loose connection faults in the electrical circuits of excavators. Background Technology

[0002] Excavators, as core equipment in engineering construction, operate in complex environments, enduring harsh conditions of strong vibration, heavy loads, and high dust levels. Their electrical circuits are highly susceptible to problems such as loose terminals, contact oxidation, and insufficient clamping force. Loose electrical connections can lead to signal transmission distortion, abnormal control commands, and intermittent equipment malfunctions. These can range from minor construction interruptions to serious equipment malfunctions, loss of control, and safety accidents, severely impacting operational efficiency and safety.

[0003] In related technologies, excavator electrical fault detection mostly involves simple monitoring of voltage and current for a single circuit, and using fixed thresholds to identify faults. Summary of the Invention

[0004] Objective: In view of at least one of the above technical problems, this application provides an online detection method and system for loose electrical wiring faults in excavators.

[0005] Technical solution: To solve the above-mentioned technical problems, the technical solution adopted in this application is as follows:

[0006] Firstly, a method for online detection of loose connections in the electrical circuits of excavators is provided, including:

[0007] S1. Identify the current working condition based on the acquired excavator operation status signal, and determine the working condition adaptive threshold based on the current working condition; wherein, the working condition adaptive threshold includes the detection cycle and the high-frequency energy threshold;

[0008] S2. Based on the detection period, calculate five characteristic parameters for each loop according to the acquired multi-loop signals; wherein the characteristic parameters include the high-frequency energy ratio E. HF Signal fluctuation coefficient C v Equivalent contact resistance change rate δR, amplitude jump amplitude ΔA max and the extreme value of the rate of change of voltage dV / dt max ;

[0009] S3, E, the proportion of high-frequency energy in each circuit HF Signal fluctuation coefficient C v The equivalent contact resistance change rate δR is related to the high-frequency energy threshold E. th Preset signal fluctuation coefficient threshold C th By comparing the equivalent contact resistance change rate with the normal range, a preliminary loose connection judgment is made, a suspected loose connection flag bit for the corresponding circuit is generated, and a preliminary loose connection judgment result is obtained.

[0010] S4. Based on the initial loose connection determination results, perform secondary verification according to the electrical topology to distinguish between loose connections at common nodes and single-circuit loose connections.

[0011] S5. If it is a single-circuit loose connection, the single-circuit loose connection type is determined according to the five characteristic parameters of the corresponding circuit, and the single-circuit loose connection type is determined to be contact oxidation type loose connection, insufficient contact pressure type loose connection or terminal loose type loose connection.

[0012] In some embodiments, the operating condition types include at least idling, digging / slewing, and crushing conditions.

[0013] Furthermore, the adaptive threshold for the operating condition is determined based on the current operating conditions, including:

[0014] If the current operating condition is idling, the detection cycle T is determined to be the first detection cycle T1, and the high-frequency energy threshold E is... th The first high-frequency energy threshold E1 was determined.

[0015] If the current working condition is excavation / rotation, the detection cycle T is determined to be the second detection cycle T2, and the high-frequency energy threshold E... th It was determined to be the second high-frequency energy threshold E2;

[0016] If the current operating condition is a crushing condition, the detection cycle T is determined to be the third detection cycle T3, and the high-frequency energy threshold E... th It was determined to be the third high-frequency energy threshold, E3;

[0017] Where T1 > T2 > T3, E1 <E2<E3。

[0018] Secondly, a vehicle controller is provided, including a processor and a storage medium;

[0019] The storage medium is used to store instructions;

[0020] The processor is configured to operate according to the instructions to execute the method.

[0021] Thirdly, an online detection system for loose electrical connections in excavators is provided, including:

[0022] The vehicle controller is configured to execute the above-described online detection method for loose electrical wiring faults in excavators.

[0023] Fourthly, an engineering machine is provided, equipped with the aforementioned online detection system for loose electrical wiring faults in excavators.

[0024] Compared with the prior art, the beneficial effects achieved by this application are as follows: The online detection method and system for loose connections in excavator electrical circuits provided by this application have the following advantages:

[0025] (1) Predictive maintenance: detection and early warning can be achieved in the early stage of poor connection deterioration before it causes downtime, realizing the transformation from "post-event maintenance" to "predictive maintenance" and greatly reducing unplanned downtime.

[0026] (2) Adaptive detection based on working conditions: Automatically match the corresponding detection cycle and high-frequency energy threshold according to different working conditions (idling, excavation / slewing, crushing conditions) to avoid false detection caused by changes in working conditions and improve detection accuracy.

[0027] (3) Dynamic characteristic frequency band: There is no need to pre-fix the characteristic frequency band. The frequency band with the most concentrated energy is automatically locked through real-time spectrum analysis, which is adaptive to different models and different wire harness types, and has a wider range of applications.

[0028] (4) Strong anti-interference ability: The multi-cycle continuous judgment and steady-state and transient parameter differentiation judgment mechanism effectively filter instantaneous interference such as vibration shock and electromagnetic pulse, and significantly reduce the false alarm rate.

[0029] (5) Accurate fault classification: Based on the combination of characteristic parameters of five dimensions such as high frequency energy, fluctuation coefficient, rate of change, jump amplitude, and equivalent resistance, it can automatically distinguish three kinds of loose connection faults with different mechanisms, namely oxidation, insufficient pressure and loose terminals, to guide accurate maintenance.

[0030] (6) Graded alarm and maintenance guidance: Graded alarms are set according to the severity of the fault and targeted maintenance guidance is provided to improve maintenance efficiency.

[0031] (7) Low cost and easy deployment: Utilizing the sampling and computing capabilities of the excavator's original VCU, only software upgrades are required, without the need for additional hardware. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a flowchart illustrating an online detection method for loose electrical wiring faults in excavators according to an embodiment of this application.

[0034] Figure 2 This is a schematic diagram of a system block diagram according to an embodiment of this application. Detailed Implementation

[0035] The present application will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and should not be used to limit the scope of protection of the present application.

[0036] In the description of this application, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0037] In the description of this application, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0038] The term "and / or" simply describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Additionally, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0039] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0040] Excavators operate in harsh environments (vibration, dust, and large temperature and humidity fluctuations), making connectors, terminals, and relay contacts in the electrical circuits prone to poor contact, also known as "loose connections." Loose connections can lead to abnormally high and unstable contact resistance, which in turn can cause signal jumps, power drops, actuator malfunctions, or even complete machine malfunction.

[0041] The relevant testing methods have the following shortcomings:

[0042] Poor adaptability to working conditions: The differences in signal fluctuation characteristics under different working conditions such as excavator idling, digging, and crushing are not taken into account, and fixed thresholds are prone to missed detections or false alarms.

[0043] The type of loose connection cannot be distinguished: the specific causes such as oxidation, loosening, and insufficient pressure cannot be identified, and maintenance personnel cannot handle them in a targeted manner, often resulting in the wrong replacement of sensors or wiring harness assemblies.

[0044] Lack of secondary verification mechanism: Single-loop anomalies and common node (power supply, grounding) anomalies cannot be effectively distinguished, and fault location is inaccurate.

[0045] Alarm Only, No Classification Guidance: Only indicates the fault, without providing specific types or repair suggestions.

[0046] Therefore, this application provides an online detection method and system for loose electrical wiring faults in excavators.

[0047] Example 1: This application provides an online detection method for loose connections in the electrical circuits of an excavator, such as... Figure 1 As shown, the method includes:

[0048] S1. Identify the current working condition based on the acquired excavator operation status signal, and determine the working condition adaptive threshold based on the current working condition; wherein, the working condition adaptive threshold includes the detection cycle and the high-frequency energy threshold;

[0049] The excavator's operating status signals include, but are not limited to: handle signals, pump pressure signals, engine speed signals, pressure sensor signals, and solenoid valve signals. The vehicle control unit (VCU) acquires these excavator operating status signals in real time and identifies the machine's current operating condition based on them.

[0050] It should be noted that the operating conditions include at least idling, digging / slewing, and crushing conditions; the mechanical vibration intensity, electromagnetic interference level, and signal fluctuation characteristics vary significantly under different operating conditions, so differentiated detection parameters need to be configured.

[0051] Therefore, determining the adaptive threshold based on the current operating conditions includes:

[0052] If the current operating condition is idling, the detection cycle T is determined to be the first detection cycle T1, and the high-frequency energy threshold E is... th The first high-frequency energy threshold E1 was determined.

[0053] If the current working condition is excavation / rotation, the detection cycle T is determined to be the second detection cycle T2, and the high-frequency energy threshold E... th It was determined to be the second high-frequency energy threshold E2;

[0054] If the current working condition is the crushing condition, the detection period T is determined as the third detection period T3, and the high-frequency energy threshold E th is determined as the third high-frequency energy threshold E3;

[0055] where, T1 > T2 > T3, E1 < E2 < E3.

[0056] In this embodiment, a working condition parameter library is pre-built, and the following two key parameters are set for different models, different working conditions, and different hardware configurations of the vehicle control unit:

[0057]

[0058] The parameter configuration satisfies the following rules:

[0059] (1) Detection period: T1 > T2 > T3; The vibration in the crushing condition is the strongest. Shortening the detection period and increasing the detection frequency can enhance the ability to capture weak faults.

[0060] (2) High-frequency energy threshold: E1 < E2 < E3; The background noise in the crushing condition is the largest, and the allowable high-frequency energy threshold is correspondingly increased.

[0061] S2. Based on the detection period, calculate five characteristic parameters of each loop according to the acquired multi-loop signals, including: high-frequency energy ratio E HF , signal fluctuation coefficient C v , equivalent contact resistance change rate δR, amplitude jump amplitude ΔA max and voltage change rate extreme value dV / dt max .

[0062] In some embodiments, the VCU synchronously acquires the following multi-loop signals:

[0063] Resistive input port: Resistance signal (such as PT1000, thermistor);

[0064] Analog acquisition unit: Sensor analog voltage signal;

[0065] Digital input unit: Digital signal;

[0066] Power supply voltage monitoring unit: Vehicle power supply voltage, internal reference voltage of VCU;

[0067] Digital output drive monitoring unit: Drive level, loop current;

[0068] Analog output monitoring unit: Output signal drift, jump, interruption;

[0069] PWM proportional valve output monitoring unit: Current fluctuation, load loss, instantaneous zeroing.

[0070] Then, based on the acquired multi-loop signals, the five characteristic parameters of each loop are calculated:

[0071] (1) High-frequency energy proportion E HF (Selection of dynamic characteristic frequency bands)

[0072] Perform a Fast Fourier Transform (FFT) on the signal to obtain the spectral distribution U(f). Search for the continuous frequency band with the highest energy amplitude in the spectrum as the characteristic frequency band, and calculate the ratio of the energy of this characteristic frequency band to the total energy:

[0073] ;

[0074] in, For signal frequency The maximum value, [ , The selected characteristic frequency bands are dynamically chosen as follows: a sliding window scan is performed on the spectrum, with the window width preset so that the frequency difference Δf is no greater than 1 / 2 of the sampling frequency, ensuring that the window contains complete spectrum information. The energy integral within each window is calculated, and the window with the largest energy integral is selected as the characteristic frequency band.

[0075] (2) Signal fluctuation coefficient C v

[0076] Calculate the ratio of the standard deviation σ to the mean μ of the signal sequence within the detection period T:

[0077] ;

[0078] (3) Equivalent contact resistance change rate δR

[0079] This algorithm prioritizes adaptation to the constant current power supply circuit of the sensor and the steady-state power supply circuit of the solenoid valve; the VCU, combined with the inherent load parameters of the circuit, calculates the relative change of the equivalent contact resistance under steady-state conditions by comparing the voltage difference between the signal source output terminal and the controller acquisition terminal.

[0080] ;

[0081] in, R is the equivalent contact resistance. normal This is a pre-stored standard room temperature resistance reference value for the wire harness terminals; in dynamic load circuits, this parameter is only used as an auxiliary judgment feature.

[0082] (4) Amplitude jump amplitude ΔA max

[0083] Perform a sliding window scan on the voltage signal and calculate the maximum amplitude of the signal within the window. With minimum amplitude The difference between the full-scale value and the full-scale value A FS The ratio:

[0084] ;

[0085] (5) Extreme value of voltage change rate dV / dt max

[0086] Calculate the maximum difference between adjacent sampling points:

[0087] ;

[0088] in, , The voltage at two adjacent sampling points. The time interval between two adjacent sampling points.

[0089] It should be noted that in the subsequent determination process, only the proportion of high-frequency energy E is considered. HF The corresponding threshold (high-frequency energy threshold E) th The adaptive threshold needs to be determined based on the current operating conditions, while the remaining feature parameters use uniformly calibrated global thresholds that do not change with the operating conditions.

[0090] Signal fluctuation coefficient C v The corresponding threshold is the signal fluctuation coefficient threshold C. th Based on the statistical distribution of signal fluctuation coefficients under normal operating conditions, it is used to determine whether the signal stability is abnormal.

[0091] The threshold corresponding to the equivalent contact resistance change rate δR includes the normal range of the equivalent contact resistance change rate: preset according to the standard resistance value and allowable deviation of the wire harness terminal.

[0092] Extreme value of voltage change rate dV / dt max The corresponding thresholds include the low-order voltage change rate threshold V. th1 and higher-order voltage change rate threshold V th Based on the statistical characteristics of voltage change rate under normal operating conditions, it is preset to distinguish between gradual changes, moderate fluctuations, and transient changes.

[0093] Amplitude jump ΔA max Preset amplitude jump classification boundaries are used, including: first boundary, second boundary, and third boundary, to distinguish between no jump, medium jump, and full-scale jump.

[0094] S3, E, the proportion of high-frequency energy in each circuit HF Signal fluctuation coefficient C v The equivalent contact resistance change rate δR is related to the high-frequency energy threshold E. th Preset signal fluctuation coefficient threshold C thBy comparing the equivalent contact resistance change rate with the normal range, a preliminary loose connection judgment is made, a suspected loose connection flag bit for the corresponding circuit is generated, and a preliminary loose connection judgment result is obtained.

[0095] During excavator operation, mechanical vibration and electromagnetic interference can cause momentary signal anomalies. A single instance of a parameter exceeding the limit cannot determine the true fault and can easily lead to false alarms. Therefore, continuous multi-cycle judgment is required.

[0096] S3.1 Exception Marking Rules:

[0097] Within a single detection cycle T, if the proportion of high-frequency energy E HF Greater than the high-frequency energy threshold E th Signal fluctuation coefficient C v The signal fluctuation coefficient is greater than the preset threshold C. th If the equivalent contact resistance change rate δR exceeds the normal range of equivalent contact resistance change rate, the corresponding characteristic parameter will be marked as an abnormal characteristic parameter.

[0098] S3.2 Continuous Judgment Rule: When the proportion of high-frequency energy E HF Signal fluctuation coefficient C v If any characteristic parameter, such as the equivalent contact resistance change rate δR, is marked as an abnormal characteristic parameter for more than three consecutive detection cycles, it is determined that the line is suspected of having a loose connection or deterioration, generating a suspected loose connection flag bit, and entering the S4 secondary verification. This rule effectively filters out transient interference (such as vibration, shock, and electromagnetic pulse), significantly improving detection accuracy.

[0099] S4. Secondary verification: Based on the preliminary loose connection judgment results, secondary verification is performed according to the electrical topology to distinguish between loose connections at common nodes and loose connections in single loops.

[0100] In some embodiments, a preset electrical topology model library is invoked to analyze the power supply, grounding, and terminal relationships of multiple abnormal signals, perform common node verification on suspected locations, and record the abnormal circuit number based on abnormal characteristic parameters.

[0101] The second verification performs the following verification items in sequence:

[0102] (1) Read the vehicle power supply voltage and the internal reference voltage of the VCU to determine whether there is a global fluctuation;

[0103] (2) Detect the voltage difference between the VCU ground terminal and the negative terminal of the battery;

[0104] (3) At the same time, check the signal stability of other unrelated loops (at least 2 different loops).

[0105] The secondary verification decision logic includes:

[0106] If a suspected loose connection flag appears but all secondary verifications are normal for more than 3 consecutive detection cycles, it is determined to be a transient interference. The suspected loose connection flag is cleared and no alarm is triggered.

[0107] If multiple input / output circuits malfunction simultaneously, accompanied by VCU power supply / grounding synchronization fluctuations, it is determined to be a loose connection at the common node;

[0108] If a single-loop input / output is abnormal, and the VCU power supply / grounding is stable while other loops are normal, it is determined that the single loop is loosely connected and enters the S5 loose connection fault category.

[0109] It should be noted that the secondary verification cycle needs to be carried out for more than 3 consecutive testing cycles, and the secondary verification result is output after confirming that the judgment conclusion is stable.

[0110] S5 Loose Connection Fault Classification: If it is a single-circuit loose connection, the single-circuit loose connection type is determined according to the five characteristic parameters of the corresponding circuit. The single-circuit loose connection type includes contact oxidation type loose connection, insufficient contact pressure type loose connection and terminal loose type loose connection.

[0111] The criteria for determining S5.1 contact oxidation type indirect connection are as follows:

[0112] All of the following conditions must be met simultaneously:

[0113] (1) E HF ≤E th This indicates that the high-frequency energy is low and there is no arc noise.

[0114] (2) C v >C th And D≤2D0, where D is the signal fluctuation coefficient C. v The variance during the detection period, D0 is the variance of the signal fluctuation coefficient under normal operating conditions; indicating that the fluctuation is slow, small in amplitude, and continuous.

[0115] (3) δR th <δR≤m×δR th ,δR th This represents the upper limit of the normal range for the rate of change of equivalent contact resistance, where m is a preset multiple (e.g., 10 times); indicating that the resistance is stably high.

[0116] (4) ΔA max The first boundary indicates that there are no significant jumps; the current and voltage changes in contact oxidation and loose connection are small and there will be no drastic fluctuations.

[0117] (5) dV / dt max <V th1 This indicates that the voltage change is gradual and without sudden changes.

[0118] The criteria for determining insufficient contact pressure type of poor connection in S5.2 are as follows:

[0119] All of the following conditions shall be satisfied simultaneously:

[0120] (1) E HF > E th , indicating that the high-frequency energy is high;

[0121] (2) C v > C th and 2D0 < D ≤ 5D0, indicating medium-amplitude fluctuations; the contact state of the contact is unstable, and the signal will show continuous medium-amplitude fluctuations, which is neither a completely stable state nor an extremely violent jump, so it exceeds the threshold and is medium.

[0122] (3) δR > δR th and 2B0 < B ≤ 5B0, where B is the variance within the detection period of the equivalent contact resistance change rate, and B0 is the variance of the equivalent contact resistance change rate under normal working conditions; indicating that insufficient pressure will cause an increase in resistance, and the shaking of the contact will cause irregular fluctuations in the contact resistance, so the equivalent contact resistance shows irregular fluctuations, so the resistance exceeds the normal upper limit, and at the same time, the variance within the detection period is large, reflecting the instability of the resistance.

[0123] (4) The first boundary ≤ ΔA max < the second boundary, indicating that the amplitude will not return to zero but is also unstable.

[0124] (5) V th1 ≤ dV / dt max ≤ V th , indicating that the voltage signal fluctuates slightly and rapidly, with a weak arc mutation, which is a voltage mutation phenomenon caused by weak arc discharge between contacts.

[0125] S5.3 The judgment conditions for terminal loose virtual connection are:

[0126] (1) E HF ≥ a × E th , where a is a preset first multiple, with a value ≥ 1.8 (such as 2 times), indicating that the high-frequency energy is significantly exceeded and the gap discharge noise is prominent; this is a typical feature of severe instability in the contact due to loose terminals and intense arc discharge.

[0127] (2) C v ≥ b × C th and D > 5D0, where b is a preset second multiple (such as 5 times); indicating intense and irregular fluctuations; C v is extremely large and the variance is extremely large, indicating that both the signal fluctuation amplitude and the instability of the fluctuation are at a very high level, corresponding to the situation where the contact state changes repeatedly and violently when the terminal is loose.

[0128] (3) The jump between adjacent sampling points of δR > c × δRth c is a preset third multiple (e.g., 5 times); indicating: intermittent open circuit; equivalent resistance change rate, the jump between adjacent sampling points exceeds the multiple, indicating that the contact resistance changes drastically and abruptly, which is a direct manifestation of the connection and disconnection caused by the loose terminal.

[0129] (4) ΔA max ≥ The third boundary indicates that the amplitude is close to zero at full scale, which means that there is a large jump in the amplitude, or even close to a completely disconnected state.

[0130] (5) dV / dt max >V th This indicates that the maximum voltage change rate is greater than the higher-order voltage change rate threshold V. th This indicates that there is an extremely rapid and violent change in the voltage signal, corresponding to the strong voltage transient phenomenon caused by arc discharge when the connection is loose;

[0131] Among them, the first boundary < the second boundary < the third boundary.

[0132] In some embodiments, it further includes: S6 fault alarm and maintenance guidance: classifying alarms according to the type of loose connection and providing maintenance suggestions, specifically including:

[0133] If the problem is determined to be a contact oxidation type of loose connection, a Level II alarm will be triggered (fault code will be displayed and the maintenance indicator light will illuminate), and it is recommended to address the issue during the next maintenance.

[0134] If the problem is determined to be a loose connection due to insufficient contact pressure, a Level II alarm will be triggered (fault code will be displayed and the maintenance indicator light will illuminate), and it is recommended to have it inspected soon.

[0135] If the problem is determined to be a loose terminal connection or a loose connection at a common node, a Level I alarm will be triggered (audio and visual alarm + instrument text prompt). It is recommended to stop the machine immediately for inspection.

[0136] In this embodiment, a tiered alarm is executed based on the severity and urgency of the fault:

[0137]

[0138] Furthermore, all loose connection fault events (including fault type, occurrence time, corresponding operating condition, and characteristic parameters) are stored in the VCU local memory. Uploading to the maintenance management platform via a remote communication module (T-BOX) enables predictive maintenance.

[0139] Application Example 1: Early detection of contact oxidation-related loose connections (idling condition)

[0140] Operating condition description: An excavator was started after being parked in a humid environment for a period of time. It was in idling mode. The pressure sensor signal showed a slow decay, and the controller reading was about 12% lower. However, the signal did not fluctuate drastically, and the equipment could still operate normally.

[0141] Example of a preset threshold:

[0142] (1) Determine the adaptive threshold based on the current operating conditions: Idle condition, detection cycle T is T1=200ms, high frequency energy threshold E th Use E1=0.15;

[0143] (2) The thresholds for the remaining characteristic parameters are fixed: the signal fluctuation coefficient threshold C th =0.08;

[0144] Low-order voltage change rate threshold V th1 =1V / s, higher-order voltage change rate threshold V th =2V / s;

[0145] Amplitude jump ΔA max Classification boundaries: First boundary = 0.1, Second boundary = 0.3, Third boundary = 0.9;

[0146] The upper limit of the normal range of the equivalent contact resistance change rate δR th The value is 0.2, and the abnormal range is 0.2~2.0 (the preset multiple is 10 times).

[0147] The preset first multiple a for determining terminal looseness is 2 times, the preset second multiple b is 5 times, and the preset third multiple c for the jump between adjacent sampling points of δR is 5 times.

[0148] Testing process:

[0149] S1 Condition Recognition: The VCU recognizes the current condition as "idling" and automatically calls the detection cycle T1=20ms, with a high-frequency energy threshold E1=0.15.

[0150] S2 signal acquisition: The VCU acquires the sensor signal at a fixed sampling frequency with a detection period of 20ms.

[0151] S2 Feature Calculation: The signal undergoes an FFT transform; the spectrum shows that the energy is mainly concentrated in the low-frequency band. Dynamic scanning is used to select characteristic frequency bands, and E is calculated. HF =0.04 (less than E) th =0.15); C v =0.13 (greater than C) th =0.08), δR=0.9 (stable in the range of 0.2~2.0), ΔA max =0.02 (less than the first boundary of 0.1), dV / dt max =0.5V / s (less than V) th1 =1V / s).

[0152] S3 Preliminary discrimination: In 5 consecutive detection cycles, if E HF , Cv, and δR all exceed their corresponding thresholds for 3 consecutive cycles, a suspected loose connection flag bit is generated.

[0153] S4 Secondary verification: When the power supply voltage of the VCU is read as stable, the grounding voltage difference is 0.02V, and the signals of other circuits are stable, it is determined as a single-circuit loose connection.

[0154] S5 Fault classification: If E HF ≤E th , C v >C th and the variance D between detection cycles is ≤ 2D0, δR th <δR ≤ 10 δR th (within the range of 0.2 - 2.0 and stable), ΔA max < the first boundary 0.1 and dV / dt max <V th1 , it is determined as an oxidation type of loose connection due to contact.

[0155] S6 Alarm and guidance: Level II alarm, store the fault code, and the instrument displays a maintenance prompt: "Oxidation loose connection in the pressure sensor circuit, clean the terminals during the next maintenance".

[0156] Application example 2: Early detection of insufficient contact pressure type of loose connection (crushing working condition)

[0157] Working condition description: When an excavator is in crushing operation, the proportional solenoid valve has small irregular fluctuations, the actuator response is sluggish, the control accuracy decreases, but the signal does not return to zero, and the equipment can still continue to operate.

[0158] Detection process:

[0159] S1 Working condition identification: The VCU identifies the current as the "crushing working condition" and automatically calls the detection cycle T3 = 5ms and the high-frequency energy threshold E3 = 0.25.

[0160] S2 Signal acquisition: The VCU acquires the control signal of the proportional solenoid valve at a fixed sampling rate, with a detection cycle of 5ms.

[0161] S2 Feature calculation: The FFT spectrum shows obvious energy peaks in the frequency band of 800kHz - 2MHz. The characteristic frequency band is selected by dynamic scanning, and E HF = 0.38 (greater than E3 = 0.25); C v = 0.16 (greater than C th = 0.08), the fluctuation amplitude of 2D0 < D ≤ 5D0 is about 22%; δR = 1.2 but the variance between detection cycles is large, 2B0 < B ≤ 5B0; ΔA max = 0.19; dV / dt max = 1.2V / s, between Vth1 Between V th and

[0162] S3 Preliminary discrimination: In five consecutive detection cycles, E HF , C v continuously exceed the corresponding thresholds, generating a suspected loose connection flag bit.

[0163] S4 Secondary verification: With stable power supply and normal other circuits, it is determined as a single-circuit loose connection.

[0164] S5 Fault classification: E HF > E th , C v > C th and 2D0 < D ≤ 5D0; The first boundary 0.1 ≤ ΔA max < the second boundary 0.3, V th1 ≤ dV / dt max ≤ V th The voltage change rate is in the middle range, δR is greater than δR th but the variance between detection cycles is large 2B0 < B ≤ 5B0, it is determined as a loose connection of insufficient contact pressure type.

[0165] S6 Alarm and guidance: Level II alarm, storing the fault code, the instrument displays: "Proportional solenoid valve pressure insufficient loose connection, it is recommended to check the mother terminal recently".

[0166] Application example 3: Emergency alarm for loose connection of terminal (excavation / rotation working condition)

[0167] Working condition description: When an excavator is in excavation operation, the actuator fails intermittently. Each time after severe vibration, it fails briefly and then resumes by itself. The electronic monitor fault alarm appears and disappears frequently, and the equipment operation efficiency drops significantly.

[0168] Detection process:

[0169] S1 Working condition identification: The VCU identifies it as "excavation / rotation working condition", calling the detection cycle T2 = 10ms, and the high-frequency energy threshold E2 = 0.20.

[0170] S2 Signal acquisition: The VCU acquires the actuator control signal, with a detection cycle of 10ms.

[0171] S2 Feature calculation: The FFT spectrum shows extremely high energy in the frequency band of 2MHz to 5MHz. Dynamically scan and select the characteristic frequency band, E HF = 0.78 (≥ 2 × E2 = 0.40); C v = 0.45 (greater than 5 times C th ); The jump of adjacent sampling points of δR exceeds 10 times (≥ 5 × δR th ); ΔA max=0.95; dV / dt max =18V / s (greater than V) th =2V / s).

[0172] S3 Preliminary Judgment: Combining high-frequency energy and amplitude jump judgment, significant anomalies occurred in three consecutive cycles, and a suspected loose connection flag was immediately generated.

[0173] S4 secondary verification: power supply is stable, other circuits are normal, and it is determined to be a single circuit with a loose connection.

[0174] S5 Fault Classification: E HF ≥2E th C v ≥5C th And D > 5D0, the jump between adjacent sampling points of δR exceeds 5 × δR. th ΔA max ≥ Third boundary 0.9, and dV / dt max >V th The connection was determined to be loose or faulty.

[0175] S6 Alarm and Guidance: Level I Emergency Alarm, audible and visual alarm + instrument text prompt: "Actuator circuit terminal is loose, please stop the machine immediately and check the connector latch".

[0176] Application Example 4: Determining a Virtual Connection in a Common Node (Idle Condition)

[0177] Operating condition description: When an excavator is idling, multiple sensor signals are abnormal at the same time, multiple values ​​on the electronic monitor fluctuate, and the VCU power supply voltage monitoring shows fluctuations.

[0178] Testing process:

[0179] S1-S3: Multiple signals simultaneously trigger the suspected loose connection flag.

[0180] S4 secondary verification: Reading the VCU power supply voltage revealed that it was synchronized with the signal fluctuation (fluctuating between 23.2V and 24.8V), and the voltage difference between the ground terminal and the negative terminal of the battery reached 0.8V (normal <0.1V). Other unrelated circuits also showed abnormalities.

[0181] Conclusion: The common node is loosely connected. It will not be classified as a single-loop loose connection in S5. Instead, a fault code will be output directly.

[0182] S6 Alarm: Level I Emergency Alarm: "Public node loose connection, please check VCU power supply line and main grounding point."

[0183] Example 2: Based on Example 1, this application provides an online detection device for loose electrical wiring faults in excavators (i.e., vehicle controller), including a processor and a storage medium;

[0184] The storage medium is used to store instructions;

[0185] The processor is configured to operate according to the instructions to execute the method according to Embodiment 1.

[0186] Example 3: Based on Examples 1 and 2, this application provides an online detection system for loose electrical wiring faults in excavators, including the vehicle controller 100. The vehicle controller includes a processor and a storage medium; the storage medium is used to store instructions; the processor is used to operate according to the instructions to perform the online detection method for loose electrical wiring faults in excavators as described in Example 1.

[0187] In some embodiments, such as Figure 2 As shown, the vehicle controller 100 includes:

[0188] The working condition identification unit is used to identify the current working condition based on the excavator's operating status signal, and adaptively configure the detection cycle and high-frequency energy threshold according to the current working condition;

[0189] The multi-loop signal acquisition unit is used to synchronously acquire the electrical multi-loop signals of the entire vehicle and calculate five characteristic parameters of each loop. The multi-loop signals include resistive input, analog input, switch input, power supply voltage, digital output, analog output, and PWM proportional valve output loop signals.

[0190] The preliminary virtual connection discrimination unit is used to determine the high-frequency energy ratio E. HF Signal fluctuation coefficient C v The duration of abnormal equivalent contact resistance change rate δR, combined with high-frequency energy threshold and global threshold, is used to make a preliminary judgment of loose connection.

[0191] The secondary verification unit is used to verify the power supply circuit and ground circuit of suspected virtual connection points according to the electrical topology, and to distinguish between single-circuit virtual connection and common node fault.

[0192] The loose connection type classification unit is used to determine the type of loose connection in a single circuit based on five characteristic parameters of the corresponding circuit, and to determine whether the loose connection in a single circuit is a contact oxidation type, an insufficient contact pressure type, or a loose terminal type.

[0193] Furthermore, the online detection system for loose connections in the excavator's electrical circuits also includes:

[0194] The electrical circuit and sensor assembly 200 under test is used to monitor and collect multi-circuit electrical signals of the whole vehicle and upload them to the vehicle controller 100.

[0195] The electronic monitor 300 is connected to the vehicle controller 100 and is used to display fault information, alarm information, and maintenance instructions.

[0196] In some embodiments, the sensor includes at least one of a water temperature sensor (PT1000 type), a pressure sensor, a switch, a solenoid valve, and a proportional valve.

[0197] Example 4: Based on Example 3, this application provides an engineering machine equipped with the aforementioned online detection system for loose electrical wiring faults in excavators.

[0198] In some embodiments, the construction machinery may be an excavator.

[0199] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0200] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0201] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0202] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1The steps of the function specified in one or more boxes.

[0203] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. An online detection method for loose connections in the electrical circuits of an excavator, characterized in that, include: S1. Identify the current working condition based on the acquired excavator operation status signal, and determine the working condition adaptive threshold based on the current working condition; wherein, the working condition adaptive threshold includes the detection cycle and the high-frequency energy threshold; S2. Based on the detection period, calculate five characteristic parameters for each loop according to the acquired multi-loop signals; wherein the characteristic parameters include high-frequency energy ratio, signal fluctuation coefficient, equivalent contact resistance change rate, amplitude jump amplitude, and voltage change rate extreme value; S3. Compare the high-frequency energy ratio, signal fluctuation coefficient, and equivalent contact resistance change rate of each circuit with the high-frequency energy threshold, the preset signal fluctuation coefficient threshold, and the normal range of the equivalent contact resistance change rate, respectively, to make a preliminary judgment on the loose connection, generate the suspected loose connection flag bit of the corresponding circuit, and obtain the preliminary loose connection judgment result. S4. Based on the initial loose connection determination results, perform secondary verification according to the electrical topology to distinguish between loose connections at common nodes and single-circuit loose connections. S5. If it is a single-circuit loose connection, the single-circuit loose connection type is determined according to the five characteristic parameters of the corresponding circuit, and the single-circuit loose connection type is determined to be contact oxidation type loose connection, insufficient contact pressure type loose connection or terminal loose type loose connection.

2. The method according to claim 1, characterized in that, The operating conditions include at least idling, digging / slewing, and crushing.

3. The method according to claim 2, characterized in that, Determine the adaptive threshold for the operating condition based on the current operating conditions, including: If the current operating condition is the idling operating condition, the detection period T is determined as a first detection period T1, and the high-frequency energy threshold E th is determined as a first high-frequency energy threshold E1; If the current working condition is the excavating / turning working condition, the detection period T is determined as a second detection period T2, the high-frequency energy threshold E th is determined as a second high-frequency energy threshold E2; If the current working condition is the crushing working condition, the detection period T is determined as a third detection period T3, and the high-frequency energy threshold E th is determined as a third high-frequency energy threshold E3; Where T1 > T2 > T3, E1 <E2<E3。 4. The method according to claim 1, characterized in that, Step S3 includes: S3.1 Abnormal marking rule: if the high-frequency energy proportion E HF is greater than the high-frequency energy threshold E th , the signal fluctuation coefficient C v is greater than the preset signal fluctuation coefficient threshold C th , or the equivalent contact resistance change rate δR exceeds the normal range of the equivalent contact resistance change rate, the corresponding characteristic parameter is marked as an abnormal characteristic parameter. S3.2 Continuous determination rule: when the high-frequency energy proportion E HF , signal fluctuation coefficient C v , equivalent contact resistance change rate δR Any characteristic parameter is marked as an abnormal characteristic parameter for more than 3 consecutive detection periods, and a suspected virtual connection flag bit is generated.

5. The method according to claim 1, characterized in that, Step S4 includes: If multiple input / output circuits malfunction simultaneously, accompanied by VCU power supply / grounding synchronization fluctuations, it is determined to be a loose connection at the common node; If a single circuit input / output is abnormal, and the VCU power supply / grounding is stable while other circuits are normal, it is determined that the single circuit has a loose connection. If a suspected loose connection flag appears but all secondary verifications are normal for more than three consecutive detection cycles, it is determined to be transient interference, and the suspected loose connection flag is cleared.

6. The method according to claim 1, characterized in that, Step S5 includes: The criteria for determining S5.1 contact oxidation type indirect connection are that the following conditions must be met simultaneously: (1) E HF ≤E th E HF E represents the proportion of high-frequency energy. th High-frequency energy threshold; (2) C v >C th And D≤2D0, C th D is the threshold for signal fluctuation coefficient, and C is the signal fluctuation coefficient. v The variance during the detection period, where D0 is the variance of the signal fluctuation coefficient under normal operating conditions; (3) δR th <δR≤m×δR th ,δR th δR represents the upper limit of the normal range of the equivalent contact resistance change rate, and m is a preset multiple. (4) ΔA max <First boundary, ΔA ma This refers to the amplitude jump. (5) dV / dt max <V th1 dV / dt ma V is the extreme value of the rate of change of voltage. th1 This is the threshold for the low-order voltage change rate; The criteria for determining a poor connection due to insufficient contact pressure in S5.2 are that the following conditions must be met simultaneously: (1)And HF >And th ; (2) C v >C th And 2D0 <D≤5D0; (3)δR>δR th and 2B0 < B ≤ 5B0, where B is the variance of the equivalent contact resistance change rate during the detection period, and B0 is the variance of the equivalent contact resistance change rate under normal conditions; (4) First boundary ≤ ΔA max <Second boundary; (5) V th1 ≤dV / dt max ≤V th V th This is the threshold for the higher-order voltage change rate; The criteria for determining a loose connection at terminal S5.3 are that the following conditions must be met simultaneously: (1) E HF ≥a×E th 'a' is the preset first multiple; (2) C v ≥b×C th And D > 5D0, b is a preset second multiple; (3) The jump between adjacent sampling points of δR > c×δR th c is a preset third multiple; (4) ΔA max ≥ Third boundary; (5) dV / dt max >V th ; Among them, the first boundary < the second boundary < the third boundary.

7. The method according to claim 1, characterized in that, Also includes: Based on the determined type of loose connection, a tiered alarm system is implemented, specifically including: If the problem is determined to be a contact oxidation type of loose connection, a Level II alarm will be triggered, a fault code will be displayed, and the maintenance indicator light will illuminate. If the problem is determined to be a loose connection due to insufficient contact pressure, a Level II alarm will be triggered, a fault code will be displayed, and the maintenance indicator light will illuminate. If the problem is determined to be a loose connection due to a terminal looseness or a loose connection at a common node, a Level I alarm will be triggered, accompanied by an audible and visual alarm and a text message notification on the instrument.

8. A vehicle controller, characterized in that, Including processor and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the method according to any one of claims 1 to 7.

9. An online detection system for loose connections in the electrical circuits of an excavator, characterized in that, The vehicle controller as described in claim 8 is configured to perform the online detection method for loose electrical wiring faults in excavators according to any one of claims 1 to 7.

10. An engineering machinery, characterized in that, The excavator is equipped with the online detection system for loose electrical wiring faults as described in claim 9.

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