Battery box bench impact test method for mine car

Abstract

The present disclosure provides a battery box bench impact test method for mine cars, which is suitable for battery box impact test of vehicles such as automatic driving mine cars. The battery box is tested by a battery box bench impact test bench comprising an impact platform. The method comprises: collecting vehicle operation data and obtaining the warranty period of the corresponding battery box; determining the required number of impacts according to the vehicle operation data and the warranty period, determining the required impact acceleration and test interval according to the vehicle operation data; and controlling the impact platform to perform impact test on the battery box according to the number of impacts, impact acceleration and test interval. The test method of the present disclosure uses the actual vehicle operation data and warranty period of the vehicle in the mining area as the basis to determine the required number of impacts and other test parameters, and uses the battery box bench impact test bench according to the test parameters to make the test data more accurate and shorten the test cycle.

Description

Technical Field

[0001] This disclosure relates to the field of testing, and in particular to a bench impact test method for a battery box for mining trucks. Background Technology

[0002] Currently, mechanical impact tests, such as battery impact tests, are mainly completed using mechanical impact testing machines. These machines have limited sample weight capacity, long stroke, and long test cycles, making them suitable for short-cycle tests such as national standard verification. However, they cannot meet the needs of tests with a large number of impacts, especially for new energy mining vehicles operating in mining areas. The loading and unloading steps during operation have a certain probability of generating significant impacts, which can affect the reliability of the battery box structure. Testing the battery boxes of new energy vehicles in mining areas using existing testing methods would require a long test cycle. Summary of the Invention

[0003] To address at least one technical problem in the prior art, this disclosure provides a bench impact test method for a battery box for mining trucks.

[0004] According to a first aspect of this disclosure, a method for testing the impact of a battery box on a mining truck is provided, wherein the battery box is tested using a battery box impact test bench, the battery box impact test bench comprising an impact table, and the method comprising:

[0005] Collect vehicle operation data and obtain the corresponding warranty period for the battery box;

[0006] The number of impacts required for the test is determined based on the vehicle operation data and the warranty period, and the impact acceleration and test interval required for the test are determined based on the vehicle operation data.

[0007] The impact test bench is controlled to perform an impact test on the battery box based on the number of impacts, the impact acceleration, and the test interval.

[0008] Optionally, determining the number of impacts required for the test based on the vehicle operating data and the warranty period includes:

[0009] The service life is determined based on the vehicle's operating data and the warranty mileage within the warranty period;

[0010] The number of impacts per year is determined based on the vehicle operation data.

[0011] The number of impacts required for the test is determined based on the smaller value between the service life and the warranty period, and the number of impacts per year.

[0012] Optionally, determining the service life based on the vehicle's operating data and the warranty mileage within the warranty period includes:

[0013] Based on the warranty mileage S and the vehicle's daily operating mileage M and annual operating days D contained in the vehicle's operating data, the service life Y1 is determined using the formula Y1 = S / (M*D).

[0014] Optionally, based on the vehicle operation data, the number of impacts per year can be determined, including:

[0015] The number of impacts per year is determined based on the number of daily trips per vehicle and the number of days the vehicle operates per year contained in the vehicle operation data.

[0016] or,

[0017] The number of impacts per day per vehicle is determined based on the number of days the vehicle operates per year, detected by the acceleration sensor, contained in the vehicle operation data.

[0018] Optionally, the number of impacts required for the test is the average number of impacts for each mining area during the warranty period;

[0019] The number of impacts in each mining area during the warranty period is equal to the product of the smaller value between the corresponding service life and the warranty period and the corresponding number of impacts per year.

[0020] Optionally, determining the required impact acceleration for the test based on the vehicle operating data includes:

[0021] Based on the impact acceleration signals generated by the vehicle during loading contained in the vehicle operation data, the maximum values ​​of the impact acceleration signals in the X, Y, and Z directions are used as the impact acceleration required for the test.

[0022] Optionally, the required test interval is determined based on the vehicle operation data, including:

[0023] Based on the impact acceleration signals generated by the vehicle during loading contained in the vehicle operation data, the test interval is determined according to the decay time of the impact acceleration signal of a single pulse.

[0024] Optionally, determining the test interval based on the decay time of the impact acceleration signal of a single pulse includes:

[0025] Determine the decay time of the impact acceleration signals acquired by acceleration acquisition devices located at different positions in the battery box during the application of a single impact pulse signal;

[0026] The test interval is determined based on the maximum decay time of the impact acceleration signal at each location during the application of a single impact pulse signal.

[0027] Optionally, the decay time is the time it takes for the impact acceleration signal to decay from its strongest value to 0 during the application of a single impact pulse signal.

[0028] Optionally, controlling the impact table to perform an impact test on the battery box based on the number of impacts, the impact acceleration, and the test interval includes:

[0029] The impact test bench is controlled to perform an impact test on the battery box based on the number of impacts, the impact acceleration, the test interval, and the percentage of impacts. The percentage of impacts is the proportion of the number of impacts in the mining area that exceed a preset value to the total number of loading times.

[0030] One or more technical solutions provided in this disclosure use actual vehicle operation data and warranty period in the mining area as a basis to determine test parameters such as the number of impacts required for the test. The test is conducted using a battery box impact test bench based on the test parameters, which makes the test data more accurate and shortens the test cycle. Attached Figure Description

[0031] The accompanying drawings illustrate exemplary embodiments of the present disclosure and, together with the description thereof, serve to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification.

[0032] Figure 1 A flowchart of a bench impact test method for a battery box for a mining truck according to an exemplary embodiment of the present disclosure is shown;

[0033] Figure 2 A schematic diagram of an impact test bench for a mining truck battery box according to an exemplary embodiment of the present disclosure is shown.

[0034] Figure 3 A sub-flowchart of a bench impact test method for a battery box for a mining truck, according to an exemplary embodiment of the present disclosure, is shown.

[0035] Figure 4 A logic flowchart of a bench impact test method for a battery box for a mining truck according to an exemplary embodiment of the present disclosure is shown. Detailed Implementation

[0036] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0037] It should be understood that the steps described in the method embodiments of this disclosure may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of this disclosure is not limited in this respect.

[0038] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the description below. It should be noted that the concepts of "first", "second", etc., used in this disclosure are only used to distinguish different devices, modules, or units, and are not intended to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0039] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0040] The names of messages or information exchanged between multiple devices in the embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of such messages or information.

[0041] The present disclosure is described below with reference to the accompanying drawings.

[0042] See Figure 1 and Figure 2 A method for testing the impact of a battery box on a mining truck, comprising: testing the battery box using a battery box impact test bench; the method includes:

[0043] S101, collect vehicle operation data and obtain the warranty period for the corresponding battery box.

[0044] See Figure 2 , Figure 2This schematic diagram illustrates an exemplary embodiment of a battery box impact test bench for mining trucks. The battery box impact test bench includes an impact platform, which comprises an impact platform body 201 and an impact platform surface 202. An impact testing fixture 203 is connected to a battery box 204 and the impact platform surface 202. The impact platform surface 202 and the impact testing fixture 203 are fixed together using bolts, as are the battery box 204 and the impact testing fixture 203. The battery box impact test bench utilizes vibration to simulate impact and perform impact tests on the corresponding battery box 204. The impact signal is transmitted to the battery box 204 through the fixture. It is known that the battery box 204 contains the battery sample to be tested.

[0045] In step S101, vehicle operation data can be collected by autonomous mining trucks and other vehicles during operation in the mining area. Specifically, vehicle operation data can be collected from multiple mining areas to ensure that the data more accurately reflects the actual operating conditions of the vehicles and to provide greater fault tolerance for other data derived from the vehicle operation data. This vehicle operation data is used to determine the number of impacts, impact acceleration, and test intervals required for the experiment. It may include the annual operating days of the vehicle, the number of trips per vehicle per day, the daily operating mileage of the vehicle, and the impact acceleration signals generated by the vehicle during loading. The impact acceleration signals can be acceleration signals in three directions, specifically collected by acceleration acquisition equipment during vehicle operation.

[0046] For example, as shown in Table 1, vehicle operation data includes: mining area, number of daily single-vehicle transport trips Nt, total daily mileage M, average transport distance LD, average number of loadings S / LD, annual vehicle operating days D, Z-axis impact acceleration a(z), Y-axis impact acceleration a(Y), Y-axis impact acceleration a(X), and the proportion of maximum impact to total loadings C, etc. It can be seen that the above vehicle operation data can be direct data or indirect data used to calculate the corresponding data. The selection and labeling methods for vehicle operation data can be as follows: The daily single-vehicle transport trips in the mining area are selected as the maximum daily single-vehicle transport trips for the corresponding mining area, taken as the maximum daily single-vehicle transport trips since the start of operation, denoted as Nt. The maximum daily single-vehicle transport trips for mining area n are denoted as Ntn. The total daily mileage is selected as the total daily mileage corresponding to the maximum number of transport trips, denoted as M. The total daily mileage for mining area n is denoted as Mn. The average transport distance is the average distance from the loading point to the unloading point, denoted as LD. The average transport distance for mining area n is denoted as LDn. The warranty mileage is the total mileage traveled by the vehicle within the warranty period, denoted as S. The warranty period is the time for which the warranty is provided, in years. Let Y be the average number of loadings; S / LD is the ratio of the warranty mileage to the average distance, also known as the average number of loadings. The average number of loadings in mining area n is denoted as S / LDn; the annual operating days of vehicles are selected as the maximum annual operating days of vehicles, i.e., the maximum number of operating days in a year, denoted as D. The annual operating days of vehicles in mining area n are denoted as Dn; the Z-axis impact acceleration of mining area n is denoted as an(Z); the Y-axis impact acceleration of mining area n is denoted as an(Y); the Y-axis impact acceleration of mining area n is denoted as an(X); the pulse width corresponding to the impact acceleration is the duration of a single impact, denoted as PWo, which can be obtained by screenshotting the time domain signal. Table 1 also includes the number of impacts ST and the average number of impacts ST. average The number of impacts, ST, is calculated based on whichever comes first, the warranty mileage or the number of years. The number of impacts in mining area n is denoted as STn; the average number of impacts, ST... average The average number of impacts in each mining area can be used as the number of impacts required for the test.

[0047] Table 1

[0048]

[0049] S102, determine the number of impacts required for the test based on vehicle operation data and warranty period, and determine the impact acceleration and test interval required for the test based on vehicle operation data.

[0050] The number of impacts, impact acceleration, and test interval are the main parameters involved in the impact test. Using these parameters, experiments are conducted on a battery box impact test bench to obtain the test results for the battery box. The number of impacts required for the test is the number of impacts the vehicle will experience within the warranty period, determined based on vehicle operating data (whichever comes first, warranty mileage or warranty period). The required impact acceleration is the impact acceleration determined by vehicle operating data, which can include X, Y, and Z-axis impact accelerations. Generally, the maximum values ​​of the maximum X, Y, and Z-axis impact accelerations for each mining area can be selected. For example, the required Z-axis impact acceleration is the maximum Z-axis impact acceleration value for each mining area. The direction used for X, Y, and Z can be determined by those skilled in the art using conventional methods, and will not be detailed in this embodiment. The required test interval is determined based on vehicle operating data. The test interval is set to prevent the impact signals from overlapping due to excessively short time intervals and to prevent the test cycle from being too long due to excessive time intervals, ensuring that the impact signals are not distorted. Specific options for setting or calculating the test interval can be found in subsequent content.

[0051] Specifically, the number of impacts required for the test can be determined according to the following steps:

[0052] S301 determines the service life based on vehicle operating data and the warranty mileage within the warranty period.

[0053] The service life Y1 can be determined using the formula Y1 = S / (M*D), based on the warranty mileage S and the vehicle's daily operating mileage M and annual operating days D contained in the vehicle's operating data.

[0054] S302 determines the number of impacts per year based on vehicle operation data.

[0055] The annual impact count ST can be determined based on the daily single-vehicle transport trips Nt and the annual operating days D contained in the vehicle operation data. The specific calculation formula is ST = Y * D * Nt. To include vehicle extreme conditions during the test, the daily single-vehicle transport trips can be the maximum daily single-vehicle transport trips, and the annual operating days can be the corresponding maximum annual operating days. For example, taking mine area 1 as an example, the impact count for mine area 1 can be calculated as ST1 = Y1 * D1 * Nt1 (Y1 ≤ Y) or ST1 = Y * D1 * Nt1 (Y1 > Y). In practical applications, the required impact count can be determined based on the average impact count for each mine area to reduce the impact of individual data anomalies on the impact count value. Taking the data in Table 1 as an example, the impact count ST1 to STn of each mine area (mine area 1 to mine area N) can be used as the basis for the calculation. average =average(ST1,ST2,…,STn) represents the number of impacts.

[0056] The annual impact count ST can also be determined based on the daily impact count N of a single vehicle detected by the acceleration sensor in the vehicle operation data and the number of days the vehicle operates in a year D. The specific calculation formula can be ST = Y * D * N.

[0057] S303, determine the required number of impacts for the test based on the smaller of the service life and the battery warranty period, as well as the number of impacts per year.

[0058] When the service life is less than the warranty period, it means that the mileage is reached first. The number of impacts required for the test is ST = Y1 * D * Nt. Based on the vehicle operation data of multiple mining areas, the number of impacts for each mining area can be calculated using the formula ST = Y1 * D * Nt, and then the average value is used as the number of impacts required for the test.

[0059] When the warranty period is less than the service life, it means that the service life will expire first. The number of impacts required for the test is ST = Y * D * Nt. Based on the vehicle operation data of multiple mining areas, the number of impacts for each mining area can be calculated using the formula ST = Y * D * Nt, and then the average value can be used as the number of impacts required for the test.

[0060] As we know, the number of impacts required for the test here represents the number of impacts that the battery pack 204 will be subjected to throughout its entire life cycle (warranty period). By conducting the test using this number of impacts, it can be determined whether the battery can operate normally under the corresponding operating conditions during the warranty period.

[0061] The impact acceleration required for the test can be determined according to the following steps: the maximum values ​​of the impact acceleration signal in the X, Y, and Z directions are taken as the required impact acceleration for the test. The impact acceleration values ​​in the X, Y, and Z directions are derived from statistical analysis of the impact acceleration values ​​collected from various mining areas. The maximum impact acceleration value appearing in each direction is taken as the standard value, i.e., a(Z) = MAX[a1(Z), a2(Z), ... an(Z)], a(Y) = MAX[a1(Y), a2(Y), ... an(Y)], a(X) = MAX[a1(X), a2(X), ... an(X)]. Taking the data in Table 1 as an example, the maximum value a1(Z) ~ an(Z) of the corresponding maximum acceleration values ​​in the Z direction for each mining area (mining area 1 to mining area N) can be taken. max (Z) = MAX(a1, a2, ..., an) is the Z-axis impact acceleration required for the test; the maximum value of the corresponding Y-axis maximum acceleration values ​​a1(Y) to an(Y) for each mining area (e.g., mining area 1 to mining area N) can be taken as a. max(Y) = MAX(a1, a2, ..., an) is used as the Y-axis impact acceleration required for the test; the maximum value of the corresponding X-axis maximum acceleration values ​​a1(X) to an(X) for each mining area (e.g., mining area 1 to mining area N) can be taken as a. max (X) = MAX(a1, a2, ..., an) represents the required Y-axis impact acceleration for the experiment. The proportion of the number of times the maximum impact occurred in each mining area to the total number of loading operations is calculated, and the maximum proportion C is taken. max =MAX(C1,C2,…Cn) represents the percentage of impacts. Taking the maximum percentage has the advantage of covering the current mining market. The pulse width can be obtained by truncating the time-domain signal, and the waveform is a half-sine wave.

[0062] The required test interval can be determined as follows: Based on the impact acceleration signal generated by the vehicle during loading, contained in the vehicle operation data, the test interval is determined according to the decay time of the impact acceleration signal of a single pulse. The decay time is the time it takes for the impact acceleration signal to decay from its strongest value to 0 during the application of a single impact pulse signal. Specifically, the decay time of the impact acceleration signal collected by acceleration acquisition devices located at different positions of the battery box 204 during the application of a single impact pulse signal can be determined; the test interval is determined based on the maximum value of the decay time of the impact acceleration signal at each position during the application of a single impact pulse signal. More specifically, control sensors and monitoring sensors can be attached to different positions of the tooling and battery box 204 to monitor the duration of the acceleration signal during the impact test. Using the monitoring sensors at different positions of the battery box 204 during the application of a single impact pulse signal, the time taken for the signal to decay from its strongest value to 0 is detected as Δt1, Δt2, ..., Δtn, respectively. Then, the test interval t of a single impact is ≥ MAX(Δt1, Δt2, ..., Δtn). The test interval setting must ensure that two adjacent impact signals do not overlap, thus preventing distortion of the single impact signal.

[0063] This step can also calculate the proportion C1, C2, ... Cn of the number of impacts exceeding the preset value in each mining area out of the total number of loadings, with the maximum proportion C... max =MAX(C1, C2, ..., Cn) represents the percentage of impacts. The purpose of using the maximum percentage is to cover the current mining market. The preset value can be set according to actual needs, using the proportion of larger impacts in the total number of loads as the impact percentage.

[0064] The technical solution disclosed herein utilizes actual vehicle operating data to determine the number of impacts, impact acceleration, and test intervals required for the test, making the data required for the relevant tests closer to the actual operating conditions of the vehicle, and making the test results based on the data more accurate, thereby improving the test effect.

[0065] S103 controls the impact table to perform an impact test on the battery box based on the number of impacts, impact acceleration, and test interval.

[0066] This step can be performed using a battery box impact test bench, specifying the number of impacts, impact acceleration, and test intervals. For an example, see [link to example]. Figure 2 and Figure 4 The bench impact test method for the battery box of the mining truck disclosed herein determines the number of impacts ST. average Z-axis impact acceleration a max (Z), Y-shaped impact acceleration a max (Y) Impact acceleration a in the X direction max (X), test interval t, and percentage of impacts C max Subsequently, based on the number of impacts, impact acceleration, test interval, and percentage of impacts, the impact test bench is controlled to perform impact tests on the battery. The percentage of impacts serves as a correction value for the number of impacts, representing the proportion of significant impacts out of the total number of loading cycles. Initially, this coefficient can be set to 1, and it can be adjusted downwards as the amount of collected sample data increases. Before controlling the impact test bench to perform impact tests on the battery, according to... Figure 2 The impact test fixture 203 and battery box 204 (battery sample) are sequentially fixed to the impact table using bolts. The impact table includes an impact table surface 202 and an impact table body 201. The impact test fixture 203 is fixed to the impact table surface 202, and the battery box 204 is fixed to the impact test fixture 203. Accelerometers are arranged as required, including a control-type accelerometer on the impact table surface 202 and a monitoring-type accelerometer on the battery sample and the impact test fixture 203. The number of sensors is determined according to requirements to ensure that the signal is transmitted from the impact table to the battery sample through the impact test fixture 203 without distortion during the impact test. The impact test is carried out in the order of Z-axis, Y-axis, and X-axis, with an interval of t between each impact test and a pulse width of PW. A frequency sweep test is required on the battery sample before and after each impact test in each direction to monitor the change in the main frequency of the battery sample. After the impact test, the battery sample is tested for capacity, airtightness, insulation resistance, etc., to determine the state of the battery sample.

[0067] The impact test method disclosed herein is based on statistical analysis of vehicle operation data in mining areas, collection of vibration road spectrum acceleration time-domain information from various mining areas, and refinement of bench test data. After verification, it is finally finalized and can quickly conduct bench impact verification for battery boxes used in mining trucks. The parameter settings are based on actual working conditions, ensuring the rationality of the verification method. At the same time, this test method can be carried out on a vibration table (impact table), which greatly reduces the cycle and improves equipment utilization compared to mechanical impact test benches.

[0068] The impact testing method disclosed herein is conducted using a battery box impact testing bench, which significantly reduces the testing time compared to conventional impact testing machines. Compared to the indicators in the original mechanical impact method, this method is derived from actual working conditions, is more closely aligned with the product, and can quickly verify battery structural failure issues caused by impact loads.

[0069] The impact test method disclosed herein determines the interval between two adjacent impact signals by collecting the decay time of acceleration signals at different locations of the battery during the impact test, thereby ensuring that the impact signal is not distorted.

Claims

1. A bench impact test method for a battery box used in mining trucks, characterized in that, Testing a battery box using a battery box impact test bench, wherein the battery box impact test bench includes an impact table, the method comprising: Collect vehicle operation data and obtain the corresponding warranty period for the battery box; The number of impacts required for the test is determined based on the vehicle operation data and the warranty period, and the impact acceleration and test interval required for the test are determined based on the vehicle operation data. The impact test bench is controlled to perform an impact test on the battery box based on the number of impacts, the impact acceleration, and the test interval. The determination of the required number of impacts for the test based on the vehicle operating data and the warranty period includes: The service life is determined based on the vehicle's operating data and the warranty mileage within the warranty period; The number of impacts per year is determined based on the vehicle operation data. The number of impacts required for the test is determined based on the smaller value between the service life and the warranty period, and the number of impacts per year.

2. The bench impact test method for a battery box for a mining truck according to claim 1, characterized in that, The determination of the service life based on the vehicle's operating data and the warranty mileage within the warranty period includes: Based on the warranty mileage S and the vehicle's daily operating mileage M and annual operating days D contained in the vehicle operation data, the formula Y1=S / (M) is used. D) Determine the service life Y1.

3. The bench impact test method for a battery box for a mining truck according to claim 1, characterized in that, Based on the vehicle operation data, the number of impacts per year is determined, including: The number of impacts per year is determined based on the number of daily trips per vehicle and the number of days the vehicle operates per year contained in the vehicle operation data. or, The number of impacts per day per vehicle is determined based on the number of days the vehicle operates per year, detected by the acceleration sensor, contained in the vehicle operation data.

4. The bench impact test method for a battery box for a mining truck according to claim 1, characterized in that, The number of impacts required for the test is the average number of impacts in each mining area during the warranty period; The number of impacts in each mining area during the warranty period is equal to the product of the smaller value between the corresponding service life and the warranty period and the corresponding number of impacts per year.

5. The bench impact test method for a battery box for a mining truck according to claim 1, characterized in that, Determining the required impact acceleration for the test based on the vehicle operating data includes: Based on the impact acceleration signals generated by the vehicle during loading contained in the vehicle operation data, the maximum values ​​of the impact acceleration signals in the X, Y, and Z directions are used as the impact acceleration required for the test.

6. The bench impact test method for a battery box for a mining truck according to claim 1, characterized in that, The required test intervals are determined based on the vehicle operation data, including: Based on the impact acceleration signals generated by the vehicle during loading contained in the vehicle operation data, the test interval is determined according to the decay time of the impact acceleration signal of a single pulse.

7. The bench impact test method for a battery box for a mining truck according to claim 6, characterized in that, The determination of the test interval based on the decay time of the impact acceleration signal of a single pulse includes: Determine the decay time of the impact acceleration signals acquired by acceleration acquisition devices located at different positions in the battery box during the application of a single impact pulse signal; The test interval is determined based on the maximum decay time of the impact acceleration signal at each location during the application of a single impact pulse signal.

8. The bench impact test method for a battery box for a mining truck according to claim 6, characterized in that, The decay time is the time it takes for the impact acceleration signal to decay from its strongest value to 0 during the application of a single impact pulse signal.

9. The bench impact test method for a battery box for a mining truck according to claim 1, characterized in that, The step of controlling the impact table to perform an impact test on the battery box based on the number of impacts, the impact acceleration, and the test interval includes: The impact test table is controlled to perform an impact test on the battery box based on the number of impacts, the impact acceleration, the test interval, and the percentage of impacts. The percentage of impacts is the proportion of the number of impacts in the mining area that exceed a preset value to the total number of loading times.

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