Unmanned aerial vehicle charging power adjustment method based on foot stand contact resistance detection

Abstract

The application discloses a method for adjusting the charging power of a UAV based on the detection of the contact resistance of the landing gear contact, and belongs to the technical field of UAV charging control. In response to a landing gear contact docking readiness signal, a DC detection current with an alternating amplitude is injected into each contact pair, and the voltage response is collected. The voltage jump amplitude at the rising and falling edges of the current is extracted, the transient contact impedance base value is calculated, and the cumulative amount of deviation from the mean is calculated. When the cumulative amount of deviation from the mean exceeds the upper limit of the preset acceptance window, the output power is switched to a safe power level defined by the lowest transient contact impedance base value, and the abnormal contact pair is subjected to multi-frequency impedance sweep. The stability of the contact form is determined according to the slope of the imaginary part of the impedance, and a power correction coefficient indexed by the real part of the impedance is generated. The safe power level is gradually adjusted using the power correction coefficient until the real-time temperature rise rate reaches the temperature rise constraint boundary, and the final charging power is locked.

Description

Technical Field

[0001] This invention relates to the field of drone charging control technology, specifically a drone charging power adjustment method based on landing gear contact resistance detection. Background Technology

[0002] After the drone lands on the charging platform, the landing gear contacts transmit the charging current. The actual contact state of the contacts is affected by surface oxidation, dirt, elastic pressure, local wear, and landing attitude, resulting in differences in the contact impedance of each contact pair. Existing charging platforms typically apply a constant DC current after the contacts are connected, measure the steady-state voltage across the contacts to obtain the DC contact resistance, and then select the charging power level according to the preset range of the resistance. Some platforms monitor the contact temperature during charging and reduce or cut off the charging power when the temperature exceeds a threshold.

[0003] The above methods rely primarily on the absolute resistance of a single or all contacts, making it difficult to detect situations where the contact impedance of individual contacts deviates from the overall distribution but does not exceed the absolute threshold. Contact resistance obtained under constant DC conditions does not include the capacitive and inductive characteristics of the contact interface under high-frequency excitation, failing to distinguish between contacts with similar DC resistance but unstable high-frequency contact patterns. Temperature monitoring suffers from response lag; by the time localized temperature rise at a contact reaches the protection condition, the contact interface may already be damaged. Directly using the fixed derating level corresponding to the worst contact, without considering dynamic changes in contact pattern and impedance real-part drift, can easily lead to overly conservative or dangerous power level settings, making it difficult to simultaneously meet charging safety and efficiency requirements.

[0004] To address the aforementioned shortcomings, a method for adjusting charging power under conditions of inconsistent contact impedance distribution and dynamic changes in contact morphology at the tripod contact points is needed. This would limit thermal risks when abnormal contact conditions occur, while also reducing unnecessary power derating. Summary of the Invention

[0005] To address the shortcomings of existing drone charging platforms in power adjustment under conditions of inconsistent contact impedance distribution and dynamic changes in contact morphology at landing gear contacts, a drone charging power adjustment method based on landing gear contact resistance detection is proposed. When an abnormal transient contact impedance dispersion is detected between contacts, the method first switches to a safe power level. Then, the stability of the contact morphology of the abnormal contacts is determined by multi-frequency impedance sweep. Based on the change in the real part of the impedance, a power correction coefficient is generated, and the power level is adjusted step by step to limit the thermal risk of abnormal contacts and reduce unnecessary power derating during charging.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a method for adjusting the charging power of a drone based on the detection of the contact resistance of the landing gear contacts, comprising: after the drone lands on the charging platform and the landing gear contacts are ready for docking, executing a first scanning sequence, injecting alternating amplitude DC detection current into each landing gear contact pair, and synchronously acquiring the voltage response sequence of each contact pair; extracting the voltage jump amplitude of each contact pair at the rising and falling edges of the current based on the voltage response sequence, calculating the transient contact impedance base value of each contact pair, and statistically calculating the cumulative deviation of the transient contact impedance base value of all contact pairs from the mean; when the deviation from the mean... When the accumulated amount exceeds the preset acceptance window limit, the output power of the charging platform is switched to a safe power level defined by the lowest transient contact impedance base value, and a multi-frequency impedance sweep is initiated for abnormal contact pairs. Based on the slope of the imaginary part of the impedance change at each frequency point obtained from the multi-frequency impedance sweep, the contact stability of the abnormal contact pair is determined, and a power correction coefficient indexed by the real part of the impedance is generated. The safe power level is then progressively increased using the power correction coefficient until the real-time temperature rise rate of any contact pair reaches the temperature rise constraint boundary determined by the initial contact resistance of that contact pair, at which point the current power level is locked as the final charging power. This method, through contact resistance detection and impedance sweep to identify the contact state, adjusts the charging power while ensuring contact safety, thereby improving the reliability of the drone charging process.

[0007] As a technical solution of the present invention, in the first scanning sequence, each tripod contact pair is sequentially encode into a scanning queue according to its physical arrangement number. A forward-amplitude DC current and a reverse-amplitude DC current are applied sequentially to each contact pair in the scanning queue at a fixed time interval. The absolute value of the reverse amplitude is a set multiple of the forward amplitude. Within each current injection step, instantaneous voltage values ​​at both ends of the contact pair are continuously acquired at a sampling rate higher than the current switching frequency. After being aligned by timestamps, two voltage subsequences corresponding to the forward and reverse amplitudes are formed, and the two voltage subsequences are merged into the voltage response sequence. Obtaining identifiable rising and falling edges through forward and reverse current switching helps improve the stability and accuracy of transient impedance extraction.

[0008] As a technical solution of the present invention, when calculating the transient contact impedance base value, the rising edge index and falling edge index corresponding to the DC detection current switching time are located in the voltage response sequence, and a predetermined number of voltage sampling points are extracted before and after the rising edge and the falling edge, respectively. The absolute value of the difference between the average voltage before the rising edge and the average voltage after the rising edge is calculated as the rising edge jump amplitude, and the absolute value of the difference between the average voltage before the falling edge and the average voltage after the falling edge is calculated as the falling edge jump amplitude. The arithmetic mean of the rising edge jump amplitude and the falling edge jump amplitude is taken, and combined with the current value of the positive amplitude DC current, the transient contact impedance base value of the contact pair is obtained. The method of joint calculation of rising and falling edges can suppress single-edge noise interference and make the impedance base value more stable.

[0009] As a technical solution of this invention, when calculating the cumulative deviation of the transient contact impedance base value of all contact pairs from the mean, the arithmetic mean of the transient contact impedance base values ​​of all contact pairs is calculated. The difference between the transient contact impedance base value and the arithmetic mean for each contact pair is then calculated to obtain the individual deviation from the mean for each contact pair. The absolute values ​​of all individual deviations are then summed, and the sum is divided by the total number of contact pairs to obtain the cumulative deviation. The cumulative deviation reflects the degree of deviation of the contact impedance of each contact pair from the overall mean, facilitating the identification of poor contact consistency or abnormalities in individual contacts.

[0010] As a technical solution of this invention, when switching the output power of the charging platform to a safe power level, the transient contact impedance base values ​​of all contact pairs are traversed, and the transient contact impedance base value with the smallest value is selected as the reference impedance value. The rated output voltage of the charging platform is obtained, and the upper limit of the safe power is calculated based on the rated output voltage, the reference impedance value, and the set safety factor. The highest level not exceeding the upper limit of the safe power is selected from the preset power level table of the charging platform as the safe power level, and the output power of the charging platform is adjusted to this safe power level. Reducing the output power in a timely manner when the contact dispersion is large can prevent overheating of abnormal contacts due to excessive contact resistance.

[0011] As a technical solution of this invention, when initiating a multi-frequency impedance sweep for abnormal contact pairs, the contact pairs corresponding to those whose cumulative deviation exceeds the upper limit of a preset acceptance window are marked as abnormal contact pairs. The injection of detection current into non-abnormal contact pairs is paused, and only the abnormal contact pairs are subjected to AC sweep signals with progressively increasing frequencies. At each sweep frequency, the effective value of the AC voltage across the abnormal contact pair and the effective value of the AC current flowing through the abnormal contact pair are measured. The impedance amplitude and phase angle at that frequency are calculated, and the real and imaginary parts of the impedance at that frequency are obtained by decomposing the impedance amplitude and phase angle. By focusing on sweep detection of abnormal contact pairs, their impedance frequency response characteristics can be quickly obtained.

[0012] As a technical solution of the present invention, when determining the contact morphology stability of abnormal contact pairs, the imaginary parts of impedance at each frequency point are arranged in ascending order of frequency. The difference in the imaginary parts of impedance between adjacent frequencies is divided by the corresponding frequency difference to obtain the slope of the change in the imaginary parts of impedance in each frequency band. The number of frequency bands with positive slopes in the slopes of the change in the imaginary parts of impedance in all frequency bands is counted. When the number of frequency bands with positive slopes exceeds a set percentage threshold of the total number of frequency bands, the contact morphology of the abnormal contact pair is determined to be unstable, and the abnormal contact pair is marked as a morphologically unstable contact. By observing the trend of the change in the imaginary part of impedance with frequency, it is possible to identify whether there are unstable morphologies such as local loosening or micro-motion at the contact interface.

[0013] As a technical solution of the present invention, when generating a power correction coefficient indexed by the real part of impedance, the real parts of impedance corresponding to the start and end frequencies of the frequency sweep of the morphologically unstable contact are extracted. The ratio of the real part of impedance at the end frequency to the real part of impedance at the start frequency is calculated to obtain the real part drift ratio. The reciprocal of this real part drift ratio is taken as the initial correction base. The ratio of the transient contact impedance base value of the morphologically unstable contact to the median of the transient contact impedance base values ​​of all contacts is obtained as the instability weighting factor. The initial correction base is multiplied by the instability weighting factor to obtain the power correction coefficient. This power correction coefficient is corrected according to the degree of real part impedance drift and the relative impedance level of the unstable contact, so that the subsequent power increase is adapted to the actual load-bearing capacity of the contact.

[0014] As a technical solution of this invention, when progressively increasing the safe power level using a power correction coefficient, the power value corresponding to the safe power level is multiplied by the power correction coefficient to obtain the first-level increased power value. The highest power level in the preset power level table of the charging platform, whose value does not exceed the first-level increased power value, is selected as the current power level, and this is maintained for a set observation period. After the set observation period ends, the transient contact impedance base value of all contact pairs under the current power level is recalculated. If the recalculated cumulative deviation from the mean does not exceed the upper limit of the preset acceptance window, the increase operation is repeated; otherwise, the increase is stopped. This progressive increase method can continuously verify contact consistency while improving charging efficiency, preventing localized overheating caused by excessively rapid power increases.

[0015] As a technical solution of the present invention, when the current power level is locked to the final charging power, the initial contact resistance of the contact pair whose real-time temperature rise rate touches the temperature rise constraint boundary is obtained. This initial contact resistance is the transient contact impedance base value of the contact pair first measured after the drone lands on the charging platform. The temperature rise constraint boundary value is obtained by multiplying the initial contact resistance by a set temperature rise ratio coefficient. When the real-time temperature rise rate of any contact pair exceeds the temperature rise constraint boundary value for a consecutive number of times, the current power level is written into the power lock register of the charging platform, and the output power of the charging platform is maintained at this level until charging is completed. By using the initial contact resistance of the contacts to determine the temperature rise constraint boundary, personalized safety boundaries can be formed for different contact states, taking into account both charging safety and charging efficiency.

[0016] The technical effects and advantages provided by the present invention in the above technical solution are as follows: By injecting alternating DC detection currents into each tripod contact pair and capturing voltage sampling points at the rising and falling edges of the current, the amplitude of the voltage jumps along both edges is extracted. The arithmetic mean of these amplitudes is then divided by the positive amplitude DC current to obtain the transient contact impedance baseline. This method calculates contact impedance using the voltage change at the moment of current switching. Compared to measuring only the steady-state DC voltage, this method suppresses interference from contact potential, thermoelectric potential, and low-frequency drift, making the transient contact impedance baseline closer to the true state at the moment of contact conduction. After obtaining the transient contact impedance baselines for all contact pairs, the individual deviations from the arithmetic mean for each contact pair are calculated. The absolute values ​​of these individual deviations are then accumulated and divided by the total number of contact pairs to obtain the cumulative deviation. The cumulative deviation reflects the overall dispersion of the contact impedance of multiple contacts. When the contact impedance of an individual contact deviates significantly from the overall distribution but the absolute resistance does not exceed a fixed threshold, this cumulative deviation can trigger an anomaly detection. After an abnormality is triggered, the output power of the charging platform is switched to a safe power level limited by the lowest transient contact impedance base value. This can limit the current flowing through the weakest contact pair before the contact pattern of the abnormal contact is clear, thus reducing the probability of local overheating.

[0017] An AC sweep frequency signal with progressively increasing frequency is applied to the abnormal contact pair. The impedance amplitude and phase angle at each frequency are measured, and the real and imaginary parts of the impedance are decomposed. The ratio of the difference in the imaginary part of the impedance between adjacent frequencies to the frequency difference is calculated to obtain the slope of the change in the imaginary part of the impedance in each frequency band. The proportion of frequency bands with positive slopes to the total number of frequency bands is counted. When this proportion exceeds a set threshold, the abnormal contact pair is identified as a morphologically unstable contact. This identification method utilizes the capacitive and inductive responses of the contact interface under high-frequency excitation to distinguish contact pairs with similar DC resistance but different contact morphological stability, avoiding misjudging contacts with degraded high-frequency characteristics as capable of carrying higher power. The real part of the impedance of the morphologically unstable contact is extracted at the start and end frequencies of the sweep frequency, the real part drift ratio is calculated and its reciprocal is taken, and then multiplied by the instability weighting factor to obtain the power correction coefficient. A power correction factor is used to progressively increase the safe power level, and the real-time temperature rise rate is observed at each level. The power is stopped and locked when the temperature rise rate of any contact pair reaches the temperature rise constraint boundary determined by the initial contact resistance. The power correction factor varies with the impedance real part drift and relative dispersion of the abnormal contact, making the increase magnitude related to the actual load-bearing capacity of the contact. Using the temperature rise rate as the termination condition prevents the contact temperature from rising too quickly during the progressive increase. The final power level is determined based on the actual load-bearing capacity of the abnormal contact, rather than a fixed derating. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0019] Figure 1 This is a flowchart of a drone charging power adjustment method based on the detection of contact resistance at the landing gear contacts; Figure 2 This is a flowchart of the safe power level switching method for the charging platform; Figure 3 This is a flowchart of the charging platform's power level adjustment control process. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] See Figure 1This invention provides a method for adjusting the charging power of a drone based on the detection of the contact resistance of the landing gear contacts, comprising: responding to a landing gear contact docking readiness signal when the drone lands on the charging platform, executing a first scanning sequence, injecting alternating amplitude DC detection current into each landing gear contact pair, and simultaneously acquiring the voltage response sequence of each contact pair; extracting the voltage jump amplitude of each contact pair at the rising and falling edges of the current based on the voltage response sequence, calculating the transient contact impedance base value of each contact pair, and calculating the cumulative deviation of the transient contact impedance base value of all contact pairs from the mean; when the cumulative deviation exceeds a preset acceptance value... When the window reaches its upper limit, the output power of the charging platform is switched to a safe power level defined by the lowest transient contact impedance base value, and a multi-frequency impedance sweep is initiated for abnormal contact pairs. Based on the slope of the change of the imaginary part of the impedance at each frequency point obtained by the multi-frequency impedance sweep, the contact mode stability of the abnormal contact pairs is determined, and a power correction coefficient indexed by the real part of the impedance is generated. The safe power level is gradually increased using the power correction coefficient until the real-time temperature rise rate of any contact pair reaches the temperature rise constraint boundary determined by the initial contact resistance of the contact pair, and the current power level is locked as the final charging power.

[0022] In practice, after the drone lands on the charging platform and generates a landing gear contact docking ready signal, all landing gear contact pairs are sequentially entered into a scanning queue according to their physical arrangement on the charging platform. The first landing gear contact pair, the second landing gear contact pair, up to the m-th landing gear contact pair are arranged sequentially in the scanning queue, where m is the total number of landing gear contact pairs. A forward-amplitude DC current and a reverse-amplitude DC current are applied sequentially to each landing gear contact pair in the scanning queue at fixed time intervals. The forward-amplitude DC current value is pre-configured, and the absolute value of the reverse-amplitude DC current is equal to the forward-amplitude DC current value multiplied by a set factor. The set factor is stored in the detection parameter table of the charging platform. In this embodiment, the set factor is set to 1, making the absolute value of the reverse-amplitude DC current equal to the forward-amplitude DC current value, using symmetrical current to counteract the thermoelectric effect at the contact interface.

[0023] Within each current injection step, instantaneous voltage values ​​across the tripod contact pair receiving the DC detection current are continuously acquired at a sampling rate higher than the current switching frequency. The sampling rate is set to 16 times the current switching frequency, which is the frequency at which forward-amplitude DC current switches between forward and reverse-amplitude DC currents. Instantaneous voltage values ​​acquired during each forward-amplitude DC current injection period are timestamped to form a forward voltage subsequence; instantaneous voltage values ​​acquired during each reverse-amplitude DC current injection period are timestamped to form a reverse voltage subsequence. The forward and reverse voltage subsequences are then merged into a voltage response sequence. Each voltage sampling point in the voltage response sequence is timestamped and includes a corresponding current direction marker.

[0024] For each tripod contact pair, locate the rising edge index and falling edge index corresponding to the DC detection current switching moment from the merged voltage response sequence. The rising edge index is the voltage sampling point number corresponding to the moment when the positive amplitude DC current begins to be injected, and the falling edge index is the voltage sampling point number corresponding to the moment when the reverse amplitude DC current begins to be injected. Extract a predetermined number of voltage sampling points before and after the rising edge, and a predetermined number of voltage sampling points before and after the falling edge, respectively. The predetermined number before and after the rising edge is the same, set to 8 voltage sampling points. The predetermined number before and after the falling edge is also set to 8 voltage sampling points.

[0025] Calculate the average voltage before the rising edge, which is the sum of the voltage amplitudes of a predetermined number of voltage sampling points before the rising edge, divided by a predetermined number. Calculate the average voltage after the rising edge, which is the sum of the voltage amplitudes of a predetermined number of voltage sampling points after the rising edge, divided by a predetermined number. Take the absolute value of the difference between the average voltage before and after the rising edge as the rising edge transition amplitude. Calculate the average voltage before the falling edge, which is the sum of the voltage amplitudes of a predetermined number of voltage sampling points before the falling edge, divided by a predetermined number. Calculate the average voltage after the falling edge, which is the sum of the voltage amplitudes of a predetermined number of voltage sampling points after the falling edge, divided by a predetermined number. Take the absolute value of the difference between the average voltage before and after the falling edge as the falling edge transition amplitude.

[0026] For the nth tripod contact pair, the rising edge jump amplitude is denoted as The drop-edge jump amplitude is denoted as The value of the positive amplitude DC current is denoted as... The transient contact impedance base value of the nth tripod contact pair is denoted as The transient contact impedance base value of the nth tripod contact pair is calculated according to the following formula:

[0027] in, This represents the voltage jump amplitude of the nth tripod contact pair at the rising edge of the current. This represents the voltage jump amplitude of the nth tripod contact pair at the falling edge of the current. The value of the positive amplitude DC current. This represents the basic value of the transient contact impedance of the nth tripod contact pair. The basic value of the transient contact impedance of the nth tripod contact pair is used for the calculation of the cumulative deviation from the mean.

[0028] In specific implementation, please refer to Figure 2 The charging platform acquires the transient contact impedance baseline values ​​of all contact pairs, which have already been calculated using voltage jump amplitude values ​​during the first scan timing. The transient contact impedance baseline values ​​of all contact pairs are then grouped into a data set according to the physical sequence number of the stand contact pairs. The data set contains the... The transient contact impedance base value of each contact pair is denoted as: The total number of transient contact impedance base values ​​for all contact pairs is denoted as . Calculate the arithmetic mean of the transient contact impedance base values ​​for all contact pairs. The arithmetic mean of the transient contact impedance base values ​​for all contact pairs is denoted as... The arithmetic mean of the transient contact impedance base values ​​of all contact pairs is obtained by... Sum the transient contact impedance base values ​​of each contact pair and divide by . Obtain the result. Calculate the difference between the transient contact impedance baseline value of each contact pair and the arithmetic mean of the transient contact impedance baseline values ​​of all contact pairs to obtain the individual deviation from the mean for each contact pair. The individual mean deviation of each contact pair is denoted as . , No. The individual mean deviation of the nth contact pair is equal to the nth The arithmetic mean of the transient contact impedance base values ​​of each contact pair minus the transient contact impedance base values ​​of all contact pairs.

[0029] After taking the absolute values ​​of the individual deviations from the mean for all contact pairs, sum them up to obtain the total sum of absolute deviations. Divide this total sum of absolute deviations by the total number of contact pairs to obtain the cumulative deviation. The cumulative deviation is denoted as . The cumulative deviation from the mean is calculated using the following formula:

[0030] in, This represents the cumulative deviation from the mean. This represents the total number of transient contact impedance base values ​​for all contact pairs. Indicates the first The transient contact impedance base value of each contact pair This represents the arithmetic mean of the transient contact impedance baseline values ​​for all contact pairs. The cumulative deviation from the mean measures the overall deviation of the transient contact impedance baseline values ​​for all contact pairs from the arithmetic mean.

[0031] In practice, the charging platform reads the upper limit of the preset acceptance window pre-written in the parameter table. When the accumulated deviation from the mean exceeds the upper limit of the preset acceptance window, a safe power level switch is executed. The transient contact impedance base values ​​of all contact pairs are iterated, and the transient contact impedance base value with the smallest value is selected as the reference impedance value, which is denoted as [reference impedance value]. Obtain the rated output voltage of the charging platform, denoted as . Read the pre-configured safety factor from the parameter table, and record the safety factor as [value]. The safety factor is set to 3. This value is chosen to ensure the upper limit of safe power is at one-third of the maximum power corresponding to the minimum transient contact impedance base value, allowing for a safety margin for contact temperature rise. The upper limit of safe power is obtained by dividing the square of the rated output voltage by the reference impedance value and then dividing by the set safety factor. This upper limit is denoted as [missing value]. .

[0032] Select the highest power level (not exceeding the safe power limit) from the preset power level table of the charging platform as the safe power level. The preset power level table is stored in the non-volatile memory of the charging platform, and the levels in the table are arranged from low to high power values. Adjust the output power of the charging platform to the safe power level.

[0033] In practice, when the accumulated deviation from the mean difference exceeds the upper limit of the preset acceptance window, the charging platform reads the individual deviations from the mean difference of all contact pairs. Contact pairs whose absolute values ​​of individual deviations exceed the arithmetic mean of the absolute values ​​of all individual deviations from the mean difference are marked as abnormal contact pairs. The charging platform suspends the injection of detection current into non-abnormal contact pairs and applies only an AC sweep frequency signal with progressively increasing frequency to the abnormal contact pairs. The sweep start frequency, sweep end frequency, and sweep step frequency of the AC sweep signal are stored in the sweep parameter table of the charging platform. The AC sweep signal starts at the sweep start frequency and increases by one sweep frequency step frequency each time it passes until the sweep end frequency is reached. At each sweep frequency level, the AC sweep signal is continuously applied to the abnormal contact pair for a set stabilization time. Measurement is performed after the AC response enters a stable state.

[0034] At each sweep frequency, the charging platform measures the effective value of the AC voltage across the abnormal contact pair using a voltage sampling circuit, and measures the effective value of the AC current flowing through the abnormal contact pair using a current sampling circuit. The voltage and current sampling circuits acquire data synchronously, and the acquired effective values ​​of AC voltage and current are stored in the sweep frequency data table according to the current sweep frequency. For the [number]th [level] sweep frequency... The sweep frequency is denoted as the current sweep frequency. The effective value of the AC voltage across the abnormal contact is denoted as... The effective value of the alternating current flowing through the abnormal contact pair is denoted as The charging platform calculates the first... The impedance amplitude at the sweep frequency is equal to the effective value of the AC voltage divided by the effective value of the AC current. The charging platform calculates the first... The phase angle at the sweep frequency is the phase difference between the AC voltage signal and the AC current signal. The phase difference is calculated by multiplying the time difference between the voltage zero-crossing point and the current zero-crossing point by the current sweep frequency, and then multiplying by the current sweep frequency. get.

[0035] For the The sweep frequency and impedance amplitude are denoted as . The phase angle is denoted as The real part of the impedance is denoted as The imaginary part of the impedance is denoted as . No. The real and imaginary parts of the impedance at the sweep frequency are calculated according to the following formula:

[0036]

[0037] in, Indicates the first The real part of the impedance of the abnormal contact pair at the sweep frequency. Indicates the first The imaginary part of the impedance of abnormal contact pairs at the sweep frequency. Indicates the first Impedance amplitude of abnormal contact pairs at the sweep frequency. Indicates the first Phase angle of abnormal contact pairs at the sweep frequency.

[0038] After completing the measurements of all sweep frequencies, the charging platform arranges the imaginary parts of the impedance at each frequency point in ascending order of the sweep frequency. For the first... The frequency of the first sweep frequency and the first For the frequency band between the sweep frequencies, the charging platform calculates the slope of the imaginary part of the impedance change in that band. The slope of the imaginary part of the impedance change in that band is equal to the first sweep frequency. The imaginary part of the impedance at the sweep frequency minus the first The difference in the imaginary parts of the impedance at each sweep frequency is then divided by the first sweep frequency. The frequency of the first sweep frequency and the first The difference in frequency sweep rates. The charging platform counts the number of frequency bands with positive slopes among the slopes of the imaginary part of impedance changes across all frequency bands. When the number of frequency bands with positive slopes exceeds a set percentage threshold for the total number of frequency bands, the charging platform determines that the contact pattern of the abnormal contact pair is unstable and marks the abnormal contact pair as a pattern-instable contact. The set percentage threshold is stored in the contact pattern determination parameter table of the charging platform, and the set percentage threshold is set to 50%.

[0039] In specific implementation, please refer to Figure 3 The charging platform extracts the real part of the impedance at the starting frequency of the frequency sweep from the sweep data table obtained by multi-frequency impedance sweep, denoted as Extract the real part of the impedance at the sweep termination frequency of the unstable contact, denoted as . The sweep start and end frequencies are determined by the sweep parameter table of the charging platform. The sweep data table stores the real and imaginary parts of the impedance measured at each sweep frequency. The ratio of the real part of the impedance at the end frequency to the real part of the impedance at the start frequency is calculated to obtain the real part drift ratio, which is equal to... Divide by The reciprocal of the real part drift ratio is taken as the initial correction base, which is equal to... Divide by The initial correction base is greater than 0.

[0040] Obtain the transient contact impedance baseline value of the morphologically unstable contact point, denoted as The transient contact impedance baseline value of the morphologically unstable contact is derived from the transient contact impedance baseline value calculated in the first scan timing sequence. The median of the transient contact impedance baseline values ​​for all contact pairs is obtained and denoted as . The median of the transient contact impedance baseline values ​​for all contact pairs is obtained as follows: All contact pairs are arranged in ascending order of their transient contact impedance baseline values. If the total number of contact pairs is odd, the median is taken as the middle value after arrangement. If the total number of contact pairs is even, the median is taken as the arithmetic mean of the two middle values ​​after arrangement. The ratio of the transient contact impedance baseline value of the morphologically unstable contact to the median of the transient contact impedance baseline values ​​for all contact pairs is calculated to obtain the instability weighting factor. The instability weighting factor is equal to... Divide by The instability weighting factor is greater than 0.

[0041] The charging platform calculates the power correction factor using the following formula:

[0042] in, This represents the power correction factor, which is greater than 0. This represents the real part of the impedance at the sweep frequency starting frequency of the morphologically unstable contact. This represents the real part of the impedance at the sweep termination frequency of the morphologically unstable contact. This represents the basic value of transient contact impedance at a morphologically unstable contact point. This represents the median of the transient contact impedance base value for all contacts.

[0043] In practice, the charging platform reads the power value corresponding to the safe power level, multiplies it by a power correction coefficient, and obtains the first-level power adjustment value. The charging platform then selects the highest power level from the preset power level table, whose value does not exceed the first-level power adjustment value, as the current power level. The platform adjusts its output power to this current power level and maintains it for the set observation period. This set observation period is pre-configured by the charging platform's adjustment parameter table and is determined based on the charging platform's thermal time constant.

[0044] After the set observation period ends, the charging platform re-executes the first scan sequence, injecting alternating DC detection currents into all tripod contact pairs, synchronously acquiring the voltage response sequence of each contact pair, calculating the transient contact impedance baseline value of each contact pair based on the voltage response sequence, and calculating the cumulative deviation of the transient contact impedance baseline value of all contact pairs from the mean. If the recalculated cumulative deviation does not exceed the upper limit of the preset acceptance window, the operation of increasing the power value calculated by the power correction coefficient is repeated. The power value corresponding to the current power level is multiplied by the power correction coefficient to obtain the next level of increased power value. The highest level that does not exceed the next level of increased power value is selected as the new current power level, and the set observation period continues to be maintained. If the recalculated cumulative deviation exceeds the upper limit of the preset acceptance window, the increase stops, and the current power level remains unchanged.

[0045] In practice, the charging platform uses temperature sensors placed near each landing gear contact pair to collect the temperature values ​​of the contact pairs in real time. The temperature sensors output temperature values ​​at a fixed sampling period. The charging platform calculates the real-time temperature rise rate based on the temperature values ​​output by the sensors; the real-time temperature rise rate represents the amount of temperature change per unit time. When the real-time temperature rise rate of a particular landing gear contact pair exceeds the corresponding temperature rise constraint boundary value, the charging platform obtains the initial contact resistance of that contact pair. The initial contact resistance is the transient contact impedance baseline value of the landing gear contact pair first measured after the drone lands on the charging platform. This transient contact impedance baseline value comes from the detection results of the first scan sequence and is stored in the charging platform's detection data table.

[0046] In practice, the charging platform reads the set temperature rise ratio coefficient from the adjustment parameter table, and the set temperature rise ratio coefficient is denoted as... The temperature rise ratio is preset in the adjustment parameter table, and the value range of the temperature rise ratio is set to 0.2 to 1.0. In this embodiment, the temperature rise ratio is set to 0.5. The basis for setting the temperature rise ratio to 0.5 is to make the temperature rise constraint boundary value at half the upper limit of the steady-state temperature rise rate corresponding to the initial contact resistance, thus retaining a safety margin for contact temperature rise.

[0047] For the There are one pair of tripod contacts, and the initial contact resistance is denoted as... The temperature rise constraint boundary value is denoted as The charging platform is calculated according to the following formula. Temperature rise constraint boundary values ​​for each tripod contact pair:

[0048] in, As a reference resistor, For reference temperature rise rate, and The adjustment parameters are pre-stored in the charging platform's adjustment parameter table; Indicates the first Temperature rise constraint boundary value for each tripod contact pair; Indicates the first The initial contact resistance of each tripod contact pair; This indicates the set temperature rise ratio coefficient.

[0049] In practice, the charging platform acquires the real-time temperature rise rate of all tripod contact pairs within each monitoring cycle, with the monitoring cycle matching the fixed sampling cycle of the temperature sensor. For each tripod contact pair, the charging platform compares the real-time temperature rise rate with its temperature rise constraint boundary value. When the real-time temperature rise rate of a tripod contact pair exceeds its temperature rise constraint boundary value, the charging platform increments the over-limit count for that pair; when the real-time temperature rise rate of a tripod contact pair is less than or equal to its temperature rise constraint boundary value, the charging platform resets the over-limit count to zero. The charging platform reads a set number of times from the adjustment parameter table, which is set to 3. This setting of 3 is based on the requirement that the real-time temperature rise rate exceeds the limit for three consecutive monitoring cycles, avoiding misjudgments caused by instantaneous temperature fluctuations or measurement noise. When the over-limit count of any tripod contact pair reaches the set number of consecutive times, the charging platform determines that the power lockout condition is met.

[0050] In some embodiments, when the power lock condition is met, the charging platform writes the level number corresponding to the current power level into the charging platform's power lock register. The current power level is the final power level determined after the power is progressively increased. The level number stored in the power lock register is used to control the power output stages of the charging platform. The output power of the charging platform is maintained at the level indicated by the power lock register until the charging process status signal ends. The charging process status signal is generated by the charging management module. When the charging management module detects that the charging current is lower than the charging cutoff current or the charging voltage reaches the charging cutoff voltage, the charging process status signal is set to end, and the charging platform stops outputting power.

[0051] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for adjusting the charging power of a drone based on the detection of contact resistance at the landing gear contacts, characterized in that, The method includes: In response to the landing gear contact docking ready signal when the drone lands on the charging platform, the first scanning sequence is executed, injecting DC detection current with alternating amplitude into each landing gear contact pair, and simultaneously acquiring the voltage response sequence of each contact pair; Based on the voltage response sequence, the voltage jump amplitude of each contact pair at the rising and falling edges of the current is extracted, the transient contact impedance base value of each contact pair is calculated, and the cumulative deviation of the transient contact impedance base value of all contact pairs from the mean is statistically analyzed. When the cumulative deviation exceeds the upper limit of the preset acceptance window, the output power of the charging platform is switched to a safe power level limited by the lowest transient contact impedance base value, and a multi-frequency impedance sweep is started for abnormal contact pairs. Based on the slope of the change of the imaginary part of impedance at each frequency point obtained by multi-frequency impedance sweep, the contact mode stability of abnormal contact pairs is determined, and a power correction coefficient indexed by the real part of impedance is generated. The power correction coefficient is used to gradually increase the safe power level until the real-time temperature rise rate of any contact pair reaches the temperature rise constraint boundary determined by the initial contact resistance of that contact pair, and the current power level is locked as the final charging power.

2. The method for adjusting UAV charging power based on tripod contact resistance detection according to claim 1, characterized in that, The execution of the first scan sequence involves injecting alternating amplitude DC detection currents into each tripod contact pair and simultaneously acquiring the voltage response sequence of each contact pair, including: Each tripod contact pair is sequentially numbered into the scanning queue according to its physical arrangement. With a fixed time interval as the step size, a forward amplitude DC current and a reverse amplitude DC current are sequentially applied to each contact pair in the scanning queue. The absolute value of the reverse amplitude is a set multiple of the forward amplitude. Within each current injection step, the instantaneous voltage values ​​at both ends of the contact pair are continuously acquired at a sampling rate higher than the current switching frequency. After being aligned by timestamps, two voltage subsequences corresponding to the positive amplitude and the reverse amplitude are formed, and the two voltage subsequences are merged into the voltage response sequence.

3. The method for adjusting the charging power of a drone based on the contact resistance detection of the tripod contact points according to claim 2, characterized in that, The step of extracting the voltage jump amplitude values ​​of each contact pair at the rising and falling edges of the current based on the voltage response sequence, and calculating the transient contact impedance base value of each contact pair, includes: Locate the rising edge index and falling edge index of the current corresponding to the switching time of the DC detection current in the voltage response sequence, and extract a set number of voltage sampling points before and after the rising edge and a set number of voltage sampling points before and after the falling edge, respectively. Calculate the absolute value of the difference between the average voltage before the rising edge and the average voltage after the rising edge, and use it as the rising edge jump amplitude. Calculate the absolute value of the difference between the average voltage before the falling edge and the average voltage after the falling edge, and use it as the falling edge jump amplitude. Take the arithmetic mean of the rising edge jump amplitude and the falling edge jump amplitude, and divide it by the current value of the positive amplitude DC current to obtain the transient contact impedance base value of the contact pair.

4. The method for adjusting the charging power of a drone based on the detection of contact resistance at the landing gear contact points according to claim 1, characterized in that, The cumulative deviation from the mean of the transient contact impedance base value of all contact pairs includes: Calculate the arithmetic mean of the transient contact impedance base values ​​of all contact pairs, and calculate the difference between the transient contact impedance base value of each contact pair and the arithmetic mean to obtain the individual deviation from the mean for each contact pair. The absolute values ​​of all individual deviations from the mean are summed to obtain the total absolute value of the deviations from the mean. The total absolute value of the deviations from the mean is then divided by the total number of contact pairs to obtain the cumulative deviation.

5. The method for adjusting the charging power of a drone based on the detection of contact resistance at the landing gear contact points according to claim 1, characterized in that, Switching the output power of the charging platform to a safe power level defined by the lowest transient contact impedance base value includes: Traverse all transient contact impedance base values ​​of all contact pairs, select the transient contact impedance base value with the smallest value as the reference impedance value, obtain the rated output voltage of the charging platform, and divide the square of the rated output voltage by the set safety multiple of the reference impedance value to obtain the safe power upper limit value. Select the highest power level from the preset power level table of the charging platform, whose value does not exceed the upper limit of the safe power, as the safe power level, and adjust the output power of the charging platform to the safe power level.

6. The method for adjusting the charging power of a drone based on the detection of contact resistance at the landing gear contact points according to claim 1, characterized in that, The initiation of multi-frequency impedance sweep for abnormal contact pairs includes: When the cumulative deviation exceeds the upper limit of the preset acceptance window, the corresponding contact pair is marked as an abnormal contact pair. The injection of detection current into non-abnormal contact pairs is suspended, and only the abnormal contact pairs are subjected to AC sweep frequency signals with frequency gradually increasing from low to high. At each sweep frequency, the effective value of the AC voltage across the abnormal contact pair and the effective value of the AC current flowing through the abnormal contact pair are measured. The impedance amplitude and phase angle at that frequency are calculated, and the real part and imaginary part of the impedance at that frequency are obtained by decomposing the impedance amplitude and phase angle.

7. The method for adjusting UAV charging power based on tripod contact resistance detection according to claim 6, characterized in that, The slope of the imaginary part of the impedance change at each frequency point obtained based on multi-frequency impedance sweep is used to determine the contact morphology stability of abnormal contact pairs, including: Arrange the imaginary parts of impedance at each frequency point in ascending order of frequency. Divide the difference of the imaginary parts of impedance between adjacent frequencies by the corresponding frequency difference to obtain the slope of the change of the imaginary parts of impedance in each frequency band. Count the number of frequency bands with positive slopes in the slope of the change of the imaginary parts of impedance in all frequency bands. When the number of frequency bands with positive slopes exceeds the set percentage threshold of the total number of frequency bands, the contact pattern of the abnormal contact pair is determined to be unstable, and the abnormal contact pair is marked as a morphologically unstable contact.

8. The method for adjusting the charging power of a drone based on the detection of contact resistance at the landing gear contact points according to claim 7, characterized in that, The generation of power correction coefficients indexed by the real part of impedance includes: Extract the real part of the impedance corresponding to the start frequency and end frequency of the frequency sweep of the unstable contact, calculate the ratio of the real part of the impedance at the end frequency to the real part of the impedance at the start frequency, obtain the real part drift ratio, and take the reciprocal of the real part drift ratio as the initial correction base. The ratio of the transient contact impedance base value of the morphologically unstable contact to the median of the transient contact impedance base values ​​of all contacts is obtained as the instability weighting factor. The initial correction base is multiplied by the instability weighting factor to obtain the power correction coefficient.

9. The method for adjusting the charging power of a drone based on the detection of contact resistance at the landing gear contact points according to claim 1, characterized in that, The step of progressively increasing the safe power level using the power correction coefficient includes: Multiply the power value corresponding to the safe power level by the power correction coefficient to obtain the first-level upward power value. Select the highest level in the preset power level table of the charging platform whose value does not exceed the first-level upward power value as the current power level and maintain the operation for the set observation time. After the set observation period ends, the transient contact impedance base value of all contact pairs under the current power level is recalculated. If the cumulative deviation from the mean value after recalculation does not exceed the upper limit of the preset acceptance window, the upward adjustment operation is repeated; otherwise, the upward adjustment is stopped.

10. The method for adjusting the charging power of a drone based on the detection of contact resistance at the landing gear contact points according to claim 9, characterized in that, Locking the current power level to the final charging power includes: The initial contact resistance of the contact pair that reaches the temperature rise constraint boundary at the real-time temperature rise rate is obtained. The initial contact resistance is the transient contact impedance base value of the contact pair first measured after the UAV lands on the charging platform. The temperature rise constraint boundary value is obtained by multiplying the initial contact resistance by a set temperature rise ratio coefficient. When the real-time temperature rise rate of any contact pair exceeds the temperature rise constraint boundary value for a number of consecutive times, the current power level is written into the power lock register of the charging platform, and the output power of the charging platform is maintained at the level indicated by the power lock register until the charging is completed.

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