A mechanical property testing system for a drop-resistant phone case structure

Abstract

This invention discloses a test system for the structural mechanical performance of drop-resistant mobile phone cases, mainly relating to the field of mobile phone case performance testing technology. It includes a gripping and management module, a posture adjustment module, a data sample acquisition module, a sample processing module, and a diagnostic output module. This invention achieves fully automated drop mechanical testing of drop-resistant mobile phone cases. A robotic arm and angle plate automatically adjust the drop posture, accurately locking the four corners of the fall. A positioning suction cup automatically picks up and releases the case, ensuring consistent and controllable drop conditions for each fall. Simultaneously, it collects impact acceleration and acoustic signals. After preprocessing, key features are extracted, outlier removal is performed on five repeated tests at a single corner, and the coefficient of variation is calculated to determine the protection level of each corner. The system then evaluates the consistency of protection based on the data from all four corners, quantifies the cushioning mechanical performance and structural uniformity, and automatically outputs a pass / fail result, significantly improving the efficiency and objectivity of the drop-resistant mechanical testing of mobile phone cases.

Description

Technical Field

[0001] This invention relates to the field of mobile phone case performance testing technology, and in particular to a test system for the structural mechanical performance of a drop-resistant mobile phone case. Background Technology

[0002] With the rapid iteration of smartphones towards thinner and lighter designs and unibody construction, phone cases, as core protective accessories, play a crucial role. Their corner cushioning and overall impact resistance are key indicators of the phone's safety under drop and impact conditions. They are also core testing items for product quality inspection, structural optimization, and reliability rating. Currently, drop tests for phone cases often use simple, manually assisted drop devices, which have significant technical limitations. Firstly, traditional equipment lacks automated and precise positioning and attitude calibration mechanisms, relying on manual placement and fixing of the phone case. The drop height, corner tilt, and verticality cannot be precisely unified, resulting in poor consistency of the drop attitude of the four corners of the phone case. Repeated test conditions have large deviations, and the test data has high dispersion, making it impossible to achieve standardized comparative testing. Secondly, the lack of standardized data preprocessing, validity screening, and intelligent judgment system makes it impossible to eliminate abnormal test data, making it difficult to achieve single-angle protection performance grading and overall structure consistency testing, and failing to meet the needs of high-precision, standardized industrial quality inspection and R&D testing.

[0003] Therefore, there is an urgent need to design an automated, high-precision, quantifiable, and detectable structural consistency testing system for the mechanical properties of drop-resistant mobile phone cases to address the aforementioned technical deficiencies. Summary of the Invention

[0004] The purpose of this invention is to provide a test system for the structural mechanical performance of a drop-resistant mobile phone case, which realizes automated drop testing of the mobile phone case at fixed points, heights, and postures. Through the acquisition of mechanical and acoustic dual signals, standardized data processing, intelligent grading and discrimination, and consistency detection, the system accurately quantifies the structural mechanical drop resistance of the mobile phone case, thereby improving the testing accuracy, repeatability, and standardization.

[0005] The objective of this invention can be achieved through the following technical solution: a test system for the structural mechanical performance of a drop-resistant mobile phone case, including a test platform, an adjustment rod fixedly connected to the upper surface of the test platform, a protective cover fixedly connected to the center of one side of the upper surface of the test platform located on the adjustment rod, a positioning rod fixedly connected to the end of the adjustment rod away from the test platform, and a robotic arm provided on the lower surface of the positioning rod; An angle plate is rotatably connected to the end of the robotic arm away from the positioning rod. Electric telescopic rods are fixedly inserted into both sides of the angle plate. A crank rod is hinged to one side of the electric telescopic rod. A positioning column is fixedly connected to the side of the angle plate away from the robotic arm. The positioning column is symmetrically slidably connected to a guide slider, and the guide slider cooperates with the crank rod. A positioning suction cup is fixedly connected to the side of the positioning column away from the angle plate. A piston is fixedly connected to one end of the guide slider inside the positioning column. A pressure relief valve is provided on one side of the positioning suction cup. A control panel is fixedly connected to one side of the adjustment rod. The control panel contains a grasping management module, a posture adjustment module, a data sample acquisition module, a sample processing module, and a diagnostic output module.

[0006] Preferably, the grasping management module is used to acquire images of the phone case exterior, identify the outer contour of the phone case, solve the two-dimensional pixel coordinates of the plane center based on the outer contour, convert and output the target reference point of the robotic arm by combining the acquired depth information, and output the grasping route by combining the retrieved preset route planning model. The attitude adjustment module is used to control the height of the adjustment rod and the falling posture of the robotic arm, while simultaneously acquiring feature images of the four corner areas of the phone case to complete the attitude adjustment of the first detection angle. The data sample acquisition module is used to collect the instantaneous acceleration and acoustic signals of five impacts at each of the four corners of the phone casing, and to construct the detection angle-height-data sample. The sample processing module is used to preprocess and extract features from the collected detection angle-height data samples. Feature extraction includes: impact transmission rate T, acoustic dominant frequency f0, and high frequency attenuation rate HFR. The extracted features are summarized to construct a single drop record list. The diagnostic output module is used to perform data calculation and dual-linkage discrimination analysis on the single drop record list, output the output results of single-corner protection performance discrimination processing and consistency discrimination results, and conduct in-depth overall product discrimination processing to obtain the result of whether the mobile phone shell meets the standard or not.

[0007] Preferably, the analysis process of the crawling management module is as follows: The system acquires images of the phone case's exterior, identifies the outer contour of the phone case using a preset contour recognition model, solves for the intersection of the two diagonals of the rectangle, obtains the two-dimensional pixel coordinates of the center of the phone case's plane, and then converts them into three-dimensional spatial center coordinates by combining the phone case's depth information, which serve as the target reference point for the robotic arm's grasping path. Simultaneously, the three-dimensional coordinates of the center of the positioning suction cup on the robotic arm are obtained. Combined with the joint rotation constraints of the robotic arm, the target reference point, and the three-dimensional coordinate information of the center, the data is input into the preset route planning model and the gripping route of the robotic arm is output. Once the end face of the positioning suction cup is fully attached to the back of the phone case, the electric telescopic rod drives the crank to push the guide slider outward, pulling the piston inside the positioning column to draw air outward. At this time, the pressure relief valve is closed, and the pressure sensor monitors the vacuum level inside the positioning suction cup in real time. When the negative pressure value reaches the set threshold, it is determined that the grip is firm, and the current negative pressure state is locked to complete the phone case pickup.

[0008] Preferably, the analysis process of the attitude adjustment module is as follows: The height of the control rod and the falling posture of the robotic arm are adjusted to the preset falling posture, which is the initial fixed posture when the phone case falls off. The feature images of the four corner areas of the mobile phone shell are obtained. The upper left corner of the feature image is taken as the first detection angle. The angle between the long side and the base plane normal and the short side and the base plane normal of the first detection angle are obtained and marked as long-base angle and short-base angle, respectively. Based on the target long-base angle and the target short-base angle, the compensation angle of the angle plate is obtained. Based on the compensation angle, the angle plate is rotated to complete the attitude adjustment of the first detection angle. The external feature image of the phone case is acquired again. The deviation between the long-base angle and the short-base angle and the target long-base angle and the target short-base angle is calculated and judged. The output is whether the position meets the standard or not. If the position does not meet the standard, the angle plate and the robotic arm are adjusted until the position meets the standard. When the position is determined to be up to standard, the height value between the lower end of the first detection angle of the phone case and the detection platform is obtained, the reference design height of the phone case is obtained, and the height of the adjustment rod is adjusted based on the reference design height. When the height value equals the reference design height, the unlock command is triggered. The pressure relief valve responds to the unlock command and opens. The negative pressure in the positioning suction cup cavity is released instantaneously, and the phone case falls freely with its corners facing down, completing the fixed-point impact. When the acceleration signal and acoustic signal at the moment of impact are collected, the electric telescopic rod is controlled to drive the crank rod to push the guide slider inward, waiting for the next adsorption and locking of the phone case.

[0009] Preferably, the analysis process of the data sample acquisition module is as follows: The system triggers the data acquisition of the accelerometer and acoustic microphone, records the acceleration and acoustic signals at the moment of impact, and constructs a detection angle-height-data sample.

[0010] Preferably, the analysis process of the sample processing module is as follows: The detection angle-height data samples collected from the four corners of the phone case are set as the initial sampling data. Based on the initial sampling data, the acceleration signal a(t) and acoustic signal y(t) are preprocessed one by one. A sampling window is set. Based on the preprocessed acceleration signal a(t) and acoustic signal y(t), the features within the preset sampling window are extracted. The features include the peak acceleration of the outer wall ae, the peak acceleration of the inner wall an, the acceleration impact duration ta, the acoustic dominant frequency f0, the high frequency attenuation rate HFR, and the acoustic impact duration ty. The impact transmissibility T is calculated based on the ratio of the peak inner wall acceleration an to the peak outer wall acceleration ae. The impact time difference is calculated based on the acceleration impact duration ta - acoustic impact duration ty. A preset time difference threshold is retrieved for validity determination, and the result is output as valid or invalid impact. If it is a valid impact, a single drop record list is constructed based on the extracted features.

[0011] Preferably, the analysis process of the diagnostic output module is as follows: Based on the single drop record list, the number of drops from the same height is set as i, where i equals 1, 2, 3, 4, 5. The mean TJ and standard deviation SD of the 5 impact transmissibility T are calculated. The data value G is calculated based on |Ti-TJ| / SD. An effective value threshold is set for discrimination. The output results are: automatically triggering supplementary testing or calculating the mean, standard deviation, and coefficient of variation of the impact transmissibility of the retained data. Based on the single drop record list, the mean acoustic dominant frequency and the mean high-frequency attenuation rate are calculated in the same way. The single-angle protection performance is judged by the coefficient of variation of transmissivity, the mean of acoustic main frequency and the mean of high frequency attenuation rate, and the output is excellent single-angle protection performance / good single-angle protection performance / poor single-angle protection performance; Calculate the average value SJP and standard deviation SJB of the impact transmission rate at the four corners of the mobile phone casing. Based on the standard deviation SJB / average value SJP, calculate the coefficient of variation of the transmission rate at the four corners. Set the threshold for the coefficient of variation of the four-corner transmission rate, perform consistency judgment on the coefficient of variation of the four-corner transmission rate, and output the result of consistency failure or consistency qualification; perform overall product judgment processing based on the output result of the single-corner protection performance judgment processing and the consistency judgment result, and output the result of compliance or non-compliance.

[0012] The beneficial effects of this invention are as follows: This invention enables fully automated drop force detection for durable phone cases. It relies on visual hand-eye calibration to accurately locate the center of the case, and uses a robotic arm and angle plate to automatically adjust the drop posture, precisely locking the four corners of the drop position. The negative pressure suction cup automatically completes the pickup and instantaneous release, ensuring that the conditions for each drop are consistent and controllable.

[0013] This invention also simultaneously collects impact acceleration and acoustic signals. After bias removal and zero-phase filtering preprocessing, it extracts key indicators such as impact transmissibility, acoustic main frequency, and high-frequency attenuation rate. It also filters valid test data based on impact timing difference, removes outliers from five repeated tests at a single corner, calculates the coefficient of variation to determine the protection level of a single corner, and then evaluates the protection consistency based on the data from the four corners. The equipment operates fully automatically with minimal human interference and high repeatability of test data. It can simultaneously quantify the buffer mechanical performance and structural uniformity, and automatically outputs the qualified judgment result, which greatly improves the efficiency and objectivity of the test of the phone case's drop resistance mechanical properties, and provides reliable data for product structure optimization and factory quality inspection. Attached Figure Description

[0014] The invention will now be further described with reference to the accompanying drawings; Figure 1 This is a three-dimensional view of the angle plate structure of the present invention; Figure 2 This is a side view of the structure of the present invention; Figure 3 This is a flowchart of the system of the present invention; Figure 4 This is a schematic diagram of the effectiveness judgment and analysis of the present invention.

[0015] Legend: 1. Testing table; 2. Adjusting rod; 3. Protective cover; 4. Positioning rod; 5. Robotic arm; 6. Angle plate; 7. Electric telescopic rod; 8. Crank rod; 9. Guide slider; 10. Positioning column; 11. Positioning suction cup. Detailed Implementation

[0016] 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, and 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.

[0017] References to embodiments herein mean that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments; Example 1: Please refer to Figures 1 to 4As shown, the present invention is a test system for the structural mechanical performance of a drop-resistant mobile phone case, including a test platform 1, an adjustment rod 2 fixedly connected to the upper surface of the test platform 1, a protective cover 3 fixedly connected to the center of one side of the upper surface of the test platform 1 located on the adjustment rod 2, a positioning rod 4 fixedly connected to the end of the adjustment rod 2 away from the test platform 1, and a robotic arm 5 provided on the lower surface of the positioning rod 4. An angle plate 6 is rotatably connected to the end of the robotic arm 5 away from the positioning rod 4. Electric telescopic rods 7 are fixedly inserted into both sides of the angle plate 6. A crank rod 8 is hinged to one side of the electric telescopic rod 7. A positioning column 10 is fixedly connected to the side of the angle plate 6 away from the robotic arm 5. The positioning column 10 is symmetrically slidably connected to a guide slider 9, and the guide slider 9 cooperates with the crank rod 8. The side of the positioning column 10 away from the angle plate 6 is fixedly connected to a positioning suction cup 11. The end of the guide slider 9 located inside the positioning column 10 is fixedly connected to a piston. A pressure relief valve is provided on one side of the positioning suction cup 11. A control panel is fixedly connected to one side of the adjustment rod 2. The control panel contains a grasping management module, an attitude adjustment module, a data sample acquisition module, a sample processing module, and a diagnostic output module. During the structural mechanical performance testing of the phone case, the robotic arm 5 is controlled by the control panel to pick up the phone case on the testing table 1 and adjust its height to test the four corners of the phone case. The grasping management module is used to acquire images of the phone case's exterior, identify the phone case's outer contour, calculate the two-dimensional pixel coordinates of the plane center based on the outer contour, and combine the acquired depth information to output the target reference point of the robotic arm 5. It also combines this with a pre-defined route planning model to output the grasping route, specifically including: An industrial vision camera is installed inside the top of the protective cover 3. Hand-eye calibration is completed in advance, and a transformation matrix is ​​established between the image pixel coordinate system and the robot arm Cartesian space coordinate system. After the phone case falls onto the table, the industrial camera captures an image of the phone case's appearance. The camera then identifies the outer contour of the phone case using a preset contour recognition model, calculates the intersection of the two diagonals of the rectangle, and obtains the two-dimensional pixel coordinates of the center of the phone case's plane. These coordinates are then combined with the phone case's depth information to convert them into three-dimensional spatial center coordinates (Xc, Yc, Zc), which serve as the target reference point for the robotic arm's grasping path. Simultaneously, the three-dimensional coordinates of the center of the positioning suction cup on the robotic arm 5 are obtained. Combined with the joint rotation constraints of the robotic arm 5, the target reference point, the three-dimensional coordinates of the center, and other information, the data are input into the preset route planning model and the grasping route of the robotic arm 5 is output. Once the end face of the positioning suction cup 11 is fully attached to the back of the phone case, the electric telescopic rod 7 drives the crank rod 8 to push the guide slider 9 outward (away from the phone case), pulling the internal piston of the positioning column 10 to draw air outward. At this time, the pressure relief valve is closed, and the pressure sensor monitors the vacuum degree of the cavity inside the positioning suction cup 11 in real time. When the negative pressure value reaches the set threshold, it is determined that the grip is firm, the current negative pressure state is locked, and the phone case is picked up. The attitude adjustment module controls the height of the adjustment rod 2 and the drop posture of the robotic arm 5. Simultaneously, it acquires feature images of the four corner areas of the phone casing to complete the attitude adjustment of the first detection angle, specifically including: The height of the control rod 2 and the falling posture of the robotic arm 5 are controlled to adjust the robotic arm 5 to the preset falling posture, which is the initial fixed posture when the mobile phone case falls off. The feature images of the four corner areas of the mobile phone shell are obtained. The upper left corner of the feature image is taken as the first detection angle. The angle between the long side and the base plane normal and the short side and the base plane normal of the first detection angle are obtained and marked as long-base angle and short-base angle, respectively. Based on the target long-base angle and the target short-base angle, the compensation angle of the angle plate 6 is obtained (with clockwise rotation as the main direction). The angle plate 6 is rotated based on the compensation angle to complete the attitude adjustment of the first detection angle. The appearance feature image of the phone case is acquired again. The deviation between the long-base angle and the short-base angle and the target long-base angle and the target short-base angle is calculated. If the deviation of both is less than the preset threshold, the position is determined to be up to standard. If the deviation of both is not less than the preset threshold, the position is determined to be down to standard. The angle plate 6 and the robotic arm 5 are then adjusted until the position is up to standard. When the position is determined to be up to standard, the height value between the lower end of the first detection angle of the mobile phone case and the detection platform is obtained, the reference design height of the mobile phone case is obtained, and the height of the adjustment rod 2 is adjusted based on the reference design height. When the height value equals the reference design height, the unlock command is triggered. The pressure relief valve responds to the unlock command and opens. The negative pressure in the inner cavity of the positioning suction cup 11 is released instantaneously. The phone case falls freely with its corners facing down, completing the fixed-point impact. When the acceleration signal and acoustic signal at the moment of impact are collected, the electric telescopic rod 7 is controlled to drive the crank rod 8 to push the guide slider 9 to slide inward, waiting for the next adsorption and locking of the phone case.

[0018] Example 2: The data sample acquisition module is used to collect the instantaneous acceleration and acoustic signals of five impacts at each of the four corners of the phone casing, constructing a detection angle-height-data sample, specifically including: The data acquisition of the accelerometer and acoustic microphone is triggered synchronously to record the acceleration signal and acoustic signal at the moment of impact, and to construct the detection angle-height-data sample. After the drop is completed, an image of the phone case is acquired, the coordinates of the three-dimensional center of the case are calculated, and the gripping path of the robotic arm 5 is generated again. Based on the gripping path, the positioning suction cup 11 is aligned with the center of the case to complete the attachment. The electric telescopic rod 7 is controlled to complete the piston suction and negative pressure positioning and locking. The height of the adjusting rod 2 and the drop posture of the robotic arm 5 are controlled to adjust the robotic arm 5 to the preset drop posture. Then the first detection angle is adjusted until the position is determined to be reached, and the subsequent detections at the same height are completed. After completing the fifth test, rotate clockwise around the first test angle to set the next corner of the phone case as the second test angle. Then, collect the data sample of the second test angle, height, and data sample simultaneously. The sample processing module is used to preprocess and extract features from the collected detection angle-height data samples. Feature extraction includes: impact transmissibility T, acoustic dominant frequency f0, high-frequency attenuation rate HFR, etc. The extracted features are summarized to construct a single drop record list, specifically including: The detection angle-height data samples collected from the four corners of the phone case are set as the initial sampling data. Based on the initial sampling data, the acceleration signal a(t) and acoustic signal y(t) are preprocessed one by one. The preprocessing includes removing DC bias and filtering. t is a natural number greater than zero and t is the sampling timestamp. For example: Remove DC bias: For the acquired acceleration signal a(t), calculate the signal mean aj within the 100ms window before the impact, and then subtract this mean from the whole signal: a(t) - acceleration mean aj equals ad(t). Filtering: Filter type: 4th order Butterworth IIR digital filter, zero phase distortion processing (forward + reverse filtering), passband range: outer wall acceleration 100Hz-5kHz; internal acceleration 100Hz-3kHz, stopband attenuation: 40dB, the filtered signal is denoted as af(t). Set a sampling window (e.g., [t0, t0+100ms], where t0 is the impact time). Based on the preprocessed acceleration signal a(t), extract the peak value of the outer wall acceleration ae, the peak value of the inner wall acceleration an, and the acceleration impact duration ta within the preset sampling window. Calculate the impact transmission rate T based on the ratio of the peak value of the inner wall acceleration an to the peak value of the outer wall acceleration ae. Peak inner wall acceleration an: collected by the outer wall acceleration sensor at the intersection of the two adjacent side walls of the corner to be measured, about 5mm from the corner apex, avoiding the area of ​​the reinforcing ribs and air cushion structure; Peak external wall acceleration (ae): collected by attaching to the phone's frame or battery surface at the center of the motherboard area inside the phone (near the CPU or camera module). Acceleration impact duration ta: The time interval during which the waveform amplitude rises from a preset percentage (e.g., 10%) of the peak value to the peak value and then falls back to the preset percentage; Based on the processed acoustic signal y(t), the acoustic dominant frequency f0, high-frequency attenuation rate HFR and acoustic impact duration ty within the preset sampling window are extracted. The acoustic dominant frequency f0 represents the frequency corresponding to the maximum amplitude of the amplitude spectrum within the set frequency range of 50Hz to 15kHz; High-frequency attenuation rate (HFR) represents the percentage of high-frequency energy (e.g., E5k-20k) to total energy (e.g., E20-20k). The acoustic impact duration ty represents the difference between the moment when the envelope rises to its peak value (1 + preset ratio) and the moment when it falls to its peak value (1 - preset ratio) within the sampling window; The impact time difference is calculated based on |acceleration impact duration ta - acoustic impact duration ty|. A preset time difference threshold is retrieved for validity determination. If the impact time difference is within the preset time difference threshold, the timing is matched and it is determined to be a valid impact. Based on the above key features, a single drop record list is constructed. If the impact time difference is greater than the preset time difference threshold, the timing is mismatched, the impact is determined to be invalid, and the test is repeated. The diagnostic output module performs data calculations and dual-linkage discriminant analysis on the single drop record list, outputting the results of single-corner protection performance discrimination and consistency discrimination, and further performing overall product discrimination to determine whether the phone case meets or does not meet the standards, specifically including: Based on the single drop record list, the number of drops from the same height is set as i, where i equals 1, 2, 3, 4, 5. The mean TJ and standard deviation SD of the impact transmissibility T of the 5 drops are calculated. The data value G is calculated based on |Ti-TJ| / SD. An effective value threshold is set. If the data value G is within the effective value threshold, the data of the corresponding number of drops is removed. If the removed data is greater than or equal to 3 drops, the entire set of data is invalidated and a retest is automatically triggered. If the removed data is less than 3 drops, the mean, standard deviation, and coefficient of variation of the impact transmissibility of the retained data are calculated. The coefficient of variation of transmissibility is expressed as the standard deviation divided by the mean of the shock transmissibility. Based on the list of single drop records, the average acoustic dominant frequency and the average high-frequency attenuation rate were calculated using the same method. Set the preset ranges for the coefficient of variation of the transfer rate [CBmin, CBmax], the average range of the main frequency [Fmin, Fmax], and the average range of the high-frequency attenuation rate [GPmin, GPmax]. The single-angle protection performance is judged by the transmissivity coefficient of variation, the mean acoustic frequency, and the mean high-frequency attenuation rate. If the following conditions are met simultaneously: transmissivity coefficient of variation < CBmin, mean acoustic frequency < Fmin, and mean high-frequency attenuation rate < GPmin, then the single-angle protection performance is judged as excellent. If the following conditions are met simultaneously: transmissivity coefficient of variation [CBmin, CBmax], mean acoustic frequency [Fmin, Fmax], and mean high-frequency attenuation rate [GPmin, GPmax], then the single-angle protection performance is judged as good. If any of the following conditions are met: transmissivity coefficient of variation > CBmax, mean acoustic frequency > Fmax, and mean high-frequency attenuation rate > GPmax, then the single-angle protection performance is judged as poor. The average impact transmission rate of the four corners of the phone case is obtained, and then the average value SJP and standard deviation SJB of the average impact transmission rate of the four corners of the phone case are calculated. The coefficient of variation of the transmission rate of the four corners is calculated based on the standard deviation SJB / average value SJP. Set a threshold for the coefficient of variation of the four-corner transmission rate, and judge the consistency of the coefficient of variation of the four-corner transmission rate. If the coefficient of variation of the four-corner transmission rate is less than the threshold, it is judged as unqualified in terms of consistency. If the coefficient of variation of the four-corner transmission rate is less than the threshold, it is judged as qualified in terms of consistency. The overall product is judged based on the output results of the single-corner protection performance discrimination processing and the consistency discrimination results. The output results include excellent / good / poor single-corner protection performance, and the consistency discrimination results include unqualified / qualified consistency. If both the single-corner protection performance is excellent / good and the consistency is qualified, it is judged to be compliant. If any of the following conditions are met: poor single-corner protection performance or unqualified consistency, it shall be deemed as substandard; The control panel immediately displays preset warning text corresponding to compliance / non-compliance, so as to intuitively understand whether the mechanical performance test of the phone casing structure has met the standard, and to provide data support for subsequent management; Among them, the preset time difference threshold, effective value threshold, preset transmission rate variation coefficient range [CBmin, CBmax], main frequency average range [Fmin, Fmax], high frequency attenuation rate average range [GPmin, GPmax], etc. mentioned above are all obtained by simulating with a standard mobile phone and stored locally; Furthermore, the above-mentioned inspection and analysis of the impact time difference is to initially determine whether the impact was effective and whether the relevant data collection was retained. Then, the data value G is analyzed, that is, the data validity analysis is performed on the data collected through impact verification to determine whether the collected data is abnormal and whether it will affect the subsequent performance analysis, so as to further ensure the availability of the data. In other words, the overall data reliability diagnosis is carried out in a progressive manner to ensure the accuracy of subsequent performance evaluation. In summary, this fully automated drop test for durable phone cases relies on visual hand-eye calibration to accurately locate the center of the case. A robotic arm and angle plate automatically adjust the drop posture, precisely locking the four corners' drop positions. A negative pressure suction cup automatically picks up and releases the case, ensuring consistent and controllable drop conditions for each test. Simultaneously, impact acceleration and acoustic signals are collected. After bias removal and zero-phase filtering preprocessing, key indicators such as impact transmissibility, acoustic frequency, and high-frequency attenuation rate are extracted. Valid test data is filtered based on impact timing differences, and outliers are removed from five repeated tests at a single corner. The coefficient of variation is calculated to determine the protection level for each corner. Finally, the protection consistency is evaluated based on the data from all four corners. This system can simultaneously quantify cushioning mechanical performance and structural uniformity, automatically outputting a pass / fail result. This significantly improves the efficiency and objectivity of the phone case drop test, providing reliable data for product structure optimization and factory quality inspection.

[0019] The threshold is set for result comparison and analysis to determine whether it is good or bad. The value of the threshold is determined by a combination of large-scale model analysis of the sample data and human experience, and can also be adjusted appropriately based on seasonal or common-sense influencing factors. The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A test system for the structural mechanical properties of a drop-resistant mobile phone case, comprising a test platform (1), characterized in that, An adjusting rod (2) is fixedly connected to the upper surface of the testing platform (1). A protective cover (3) is fixedly connected to the center of one side of the adjusting rod (2) on the upper surface of the testing platform (1). A positioning rod (4) is fixedly connected to the end of the adjusting rod (2) away from the testing platform (1). A robotic arm (5) is provided on the lower surface of the positioning rod (4). An angle plate (6) is rotatably connected to the end of the robotic arm (5) away from the positioning rod (4). Electric telescopic rods (7) are fixedly inserted into both sides of the angle plate (6). A crank rod (8) is hinged to one side of the electric telescopic rod (7). A positioning column (10) is fixedly connected to the side of the angle plate (6) away from the robotic arm (5). The positioning column (10) is symmetrically connected to a guide slider (9), and the guide slider (9) cooperates with the crank rod (8). The positioning column (10) is fixedly connected to a positioning suction cup (11) on the side away from the angle plate (6). The guide slider (9) is fixedly connected to a piston at one end inside the positioning column (10). A pressure relief valve is provided on one side of the positioning suction cup (11). The control panel is fixedly connected to one side of the adjustment rod (2). The control panel is equipped with a grasping management module, a posture adjustment module, a data sample acquisition module, a sample processing module, and a diagnostic output module.

2. The test system for the structural mechanical properties of a drop-resistant mobile phone case according to claim 1, characterized in that, The grasping management module is used to collect images of the phone case exterior, identify the outer contour of the phone case, solve the two-dimensional pixel coordinates of the plane center based on the outer contour, convert the collected depth information to output the target reference point of the robotic arm (5), and output the grasping route based on the retrieved preset route planning model. The attitude adjustment module is used to control the height of the adjustment rod (2) and the falling posture of the robotic arm (5), while acquiring feature images of the four corner areas of the mobile phone casing to complete the attitude adjustment of the first detection angle. The data sample acquisition module is used to collect the instantaneous acceleration and acoustic signals of five impacts at each of the four corners of the phone casing, and to construct the detection angle-height-data sample. The sample processing module is used to preprocess and extract features from the collected detection angle-height data samples. Feature extraction includes: impact transmission rate T, acoustic dominant frequency f0, and high frequency attenuation rate HFR. The extracted features are summarized to construct a single drop record list. The diagnostic output module is used to perform data calculation and dual-linkage discrimination analysis on the single drop record list, output the output results of single-corner protection performance discrimination processing and consistency discrimination results, and conduct in-depth overall product discrimination processing to obtain the result of whether the mobile phone shell meets the standard or not.

3. The test system for the structural mechanical properties of a drop-resistant mobile phone case according to claim 2, characterized in that, The analysis process of the crawling management module is as follows: Collect images of the phone case exterior, identify the outer contour of the phone case through a preset contour recognition model, solve the intersection of the two diagonals of the rectangle, obtain the two-dimensional pixel coordinates of the center of the phone case plane, and then convert the phone case depth information into three-dimensional space center coordinates, which are used as the target reference point for the robotic arm (5) to grasp the path. At the same time, the center three-dimensional coordinates of the positioning suction cup on the robotic arm (5) are obtained. Combined with the joint rotation angle constraint, target reference point, and center three-dimensional coordinate information of the robotic arm (5), the preset route planning model is retrieved and the grasping route of the robotic arm (5) is output. When the end face of the positioning suction cup (11) is fully attached to the back of the phone case, the electric telescopic rod (7) drives the crank rod (8) to push the guide slider (9) to slide outward, pulling the piston inside the positioning column (10) to draw air outward. At this time, the pressure relief valve is closed, and the pressure sensor monitors the vacuum degree inside the positioning suction cup (11) in real time. When the negative pressure value reaches the set threshold, it is determined that the grip is firm, and the current negative pressure state is locked to complete the phone case pickup.

4. The test system for the structural mechanical properties of a drop-resistant mobile phone case according to claim 3, characterized in that, The analysis process of the attitude adjustment module is as follows: Control the height of the adjustment rod (2) and the falling posture of the robotic arm (5) to adjust the robotic arm (5) to the preset falling posture, which is the initial fixed posture when the mobile phone case falls off. The feature images of the four corner areas of the mobile phone shell are obtained. The upper left corner of the feature image is taken as the first detection angle. The angle between the long side and the base plane normal and the short side and the base plane normal of the first detection angle are obtained and marked as long-base angle and short-base angle respectively. Based on the target long-base angle and the target short-base angle, the compensation angle of the angle plate (6) is obtained. Based on the compensation angle, the angle plate (6) is rotated to complete the attitude adjustment of the first detection angle. The appearance feature image of the mobile phone case is acquired again. The deviation between the long-base angle and the short-base angle and the target long-base angle and the target short-base angle is calculated and judged. The position is output as qualified or unqualified. If the position is unqualified, the angle plate (6) and the robotic arm (5) are adjusted until the position is qualified. When the position is determined to be up to standard, the height value between the lower end of the first detection angle of the mobile phone case and the detection platform is obtained, the reference design height of the mobile phone case is obtained, and the height of the adjustment rod (2) is adjusted based on the reference design height. When the height value is equal to the reference design height, the unlock command is triggered. The pressure relief valve responds to the unlock command and opens. The negative pressure in the cavity of the positioning suction cup (11) is released instantaneously. The phone case keeps its corners facing down and falls freely, completing the fixed-point impact. When the acceleration signal and acoustic signal at the moment of impact are collected, the electric telescopic rod (7) is controlled to drive the crank rod (8) to push the guide slider (9) to slide inward, waiting for the next adsorption and locking of the phone case.

5. The test system for the structural mechanical properties of a drop-resistant mobile phone case according to claim 4, characterized in that, The analysis process of the data sample acquisition module is as follows: The system triggers the data acquisition of the accelerometer and acoustic microphone, records the acceleration and acoustic signals at the moment of impact, and constructs a detection angle-height-data sample.

6. The test system for the structural mechanical properties of a drop-resistant mobile phone case according to claim 5, characterized in that, The analysis process of the sample processing module is as follows: The detection angle-height data samples collected from the four corners of the phone case are set as the initial sampling data. Based on the initial sampling data, the acceleration signal a(t) and acoustic signal y(t) are preprocessed one by one. A sampling window is set. Based on the preprocessed acceleration signal a(t) and acoustic signal y(t), the features within the preset sampling window are extracted. The features include the peak acceleration of the outer wall ae, the peak acceleration of the inner wall an, the acceleration impact duration ta, the acoustic dominant frequency f0, the high frequency attenuation rate HFR, and the acoustic impact duration ty. The impact transmissibility T is calculated based on the ratio of the peak inner wall acceleration an to the peak outer wall acceleration ae. The impact time difference is calculated based on the acceleration impact duration ta - acoustic impact duration ty. A preset time difference threshold is retrieved for validity determination, and the result is output as valid or invalid impact. If it is a valid impact, a single drop record list is constructed based on the extracted features.

7. The test system for the structural mechanical properties of a drop-resistant mobile phone case according to claim 6, characterized in that, The analysis process of the diagnostic output module is as follows: Based on the single drop record list, the number of drops from the same height is set as i, where i equals 1, 2, 3, 4, 5. The mean TJ and standard deviation SD of the 5 impact transmissibility T are calculated. The data value G is calculated based on |Ti-TJ| / SD. An effective value threshold is set for discrimination. The output results are: automatically triggering supplementary testing, or calculating the mean, standard deviation, and transmissibility coefficient of the retained data. Based on the single drop record list, the mean acoustic frequency and the mean high-frequency attenuation rate are calculated in the same way. The single-angle protection performance is judged by the coefficient of variation of transmissivity, the mean of acoustic main frequency and the mean of high frequency attenuation rate, and the output is excellent single-angle protection performance / good single-angle protection performance / poor single-angle protection performance; Calculate the average value SJP and standard deviation SJB of the impact transmission rate at the four corners of the mobile phone casing. Based on the standard deviation SJB / average value SJP, calculate the coefficient of variation of the transmission rate at the four corners. Set the threshold for the coefficient of variation of the four-corner transmission rate, perform consistency judgment on the coefficient of variation of the four-corner transmission rate, and output the result of consistency failure or consistency qualification; perform overall product judgment processing based on the output result of the single-corner protection performance judgment processing and the consistency judgment result, and output the result of compliance or non-compliance.

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