Contact pressure distribution method and system for moving and static contacts of miniature relay

Abstract

The invention provides a contact pressure distribution method and system for moving and static contacts of a miniature relay, and relates to the technical field of control, and the method comprises the steps: obtaining the state information of a contact system, building a contact infinitesimal force-displacement response characteristic, recognizing a stress concentration region, and adjusting a moving contact driving force application path to redistribute the contact pressure. And generating a segmented motion control instruction based on the fatigue life constraint. The contact surface stress concentration phenomenon can be effectively reduced, the contact pressure distribution is optimized, the service life of the contact is prolonged, and the reliability of the relay is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of control, in particular to a contact pressure distribution method and system for moving and static contacts of a micro relay. BACKGROUND

[0002] As a core switching element in electronic control systems, the reliability of a micro relay directly affects the stable operation of the entire system. In a micro relay, the contact quality between the moving and static contacts is a key factor determining its working performance and service life. The distribution state of the contact pressure not only affects the contact resistance of the contacts, but is also closely related to the wear, electrical erosion and mechanical fatigue of the contact materials. Traditional micro relays usually use spring mechanisms or electromagnetic driving devices to form contact between the moving and static contacts to realize the on and off functions of the circuit. With the development of the trend of miniaturization and integration of electronic devices, the size of micro relays is continuously reduced, while the working reliability requirements are continuously improved, which makes the design and control of the contact system face greater challenges.

[0003] The current micro relay contact pressure distribution technology has the following main defects: the existing technology cannot accurately obtain the actual pressure distribution of the contact interface, and usually uses macroscopic average pressure for design, ignoring the non-uniformity of the pressure distribution at the microscopic scale, which may cause excessive stress concentration in local areas and accelerate the fatigue failure of the contact materials. The existing moving contact driving mode usually uses constant force or simple linear variation driving mode, lacks adaptive control ability for different contact stages, cannot dynamically adjust the driving parameters according to the actual contact state of the contact surface, and is difficult to realize the optimal distribution of the contact pressure. The control of the contact process in the existing technology mainly focuses on the final contact state, ignores the dynamic characteristics in the contact formation process, cannot effectively suppress the bouncing phenomenon and impact wear generated in the contact process, and affects the service life and reliability of the relay. SUMMARY

[0004] The micro relay moving and static contact contact pressure distribution method and system provided by the embodiments of the present application can solve the problems in the prior art.

[0005] In a first aspect, the present application provides a micro relay moving and static contact contact pressure distribution method, comprising:

[0006] Obtaining contact system state information of a micro relay, dividing the micro relay into a plurality of contact microelements according to the moving contact displacement and the static contact deformation in the contact system state information, and establishing the force-displacement response characteristics of each contact microelement; correlating and mapping the force-displacement response characteristics with the contact resistance in the contact system state information to obtain an initial contact pressure distribution.

[0007] According to the initial contact pressure distribution, a stress concentration area of the contact surface is identified, and spatial position features and stress gradient features corresponding to the stress concentration area are extracted;

[0008] According to the spatial position features and the stress gradient features, the initial contact pressure distribution is redistributed by adjusting a driving force application path of the moving contact, so as to obtain a target contact pressure distribution;

[0009] Based on the target contact pressure distribution and a fatigue life constraint condition of the contact material, a segmented motion control instruction of the moving contact is generated, and the segmented motion control instruction specifies a speed variation law and a pressure loading time sequence of the moving contact at different stages in a contact stroke;

[0010] The segmented motion control instruction is sent to a driving mechanism, and the driving mechanism is controlled to drive the moving contact to complete a contact process with the stationary contact according to the segmented motion control instruction.

[0011] According to the displacement amount of the moving contact and the deformation amount of the stationary contact in the contact system state information, the micro relay is divided into a plurality of contact micro elements, and a force-displacement response characteristic of each contact micro element is established, and the force-displacement response characteristic is associated and mapped with the contact resistance in the contact system state information, to obtain an initial contact pressure distribution, including:

[0012] According to the displacement amount of the moving contact and the deformation amount of the stationary contact in the contact system state information, a normal distance distribution between the surface of the moving contact and the surface of the stationary contact is calculated, to obtain a gap field of a contact interface;

[0013] The area with a gap value of zero in the gap field is taken as an actual contact area, and the actual contact area is divided into a plurality of contact micro elements;

[0014] For each contact micro element, a constitutive relation between a local stress tensor and a local strain tensor of the contact micro element is established, and the constitutive relation determines the deformation response of the contact micro element under a three-dimensional stress state based on the elastic modulus and the Poisson's ratio of the contact material;

[0015] According to the constitutive relation, a virtual normal displacement load is applied to each contact micro element, and a normal reaction force and a tangential reaction force generated by the contact micro element under the action of the virtual normal displacement load are calculated, to obtain a force-displacement response characteristic of each contact micro element;

[0016] The force-displacement response characteristic is associated and mapped with the contact resistance in the contact system state information, to establish a coupling relationship between a contact pressure distribution and a conductive contact area;

[0017] Based on the coupling relationship, taking the measured value of the contact resistance between the contacts as a boundary condition, the normal pressure value of each contact microelement satisfying the boundary condition is reversely solved to obtain the initial contact pressure distribution.

[0018] According to the initial contact pressure distribution, a stress concentration region of the contact surface is identified, and spatial position features and stress gradient features corresponding to the stress concentration region are extracted, including:

[0019] The normal pressure value of each contact microelement in the initial contact pressure distribution is converted into a normal stress value to construct a stress field distribution of the contact surface; and spatial derivation operation is performed on the normal stress value of each contact microelement in the stress field distribution to obtain a stress spatial gradient at the position of each contact microelement.

[0020] When the stress spatial gradient of a contact microelement exceeds a gradient statistical threshold value, the contact microelement is marked as a stress concentration microelement; spatially adjacent stress concentration microelements are clustered to form a stress concentration microelement cluster, and each stress concentration microelement cluster corresponds to a stress concentration region.

[0021] For each stress concentration region, the coordinate average value of the stress concentration microelements in the stress concentration region is calculated to obtain a geometric center coordinate, a coordinate sequence of a stress concentration microelement located at an edge position is identified to form a boundary contour, and the geometric center coordinate and the boundary contour are combined to obtain spatial position features corresponding to the stress concentration region.

[0022] For each stress concentration region, the rate of change of the stress value with respect to the spatial distance is extracted from a plurality of radial paths extending to the boundary contour starting from the geometric center coordinate of the stress concentration region, a stress gradient vector field of the stress concentration region is synthesized, and the gradient amplitude corresponding to the maximum principal direction is extracted as a stress gradient feature corresponding to the stress concentration region.

[0023] According to the spatial position features and the stress gradient features, the initial contact pressure distribution is redistributed by adjusting a driving force application path of the moving contact to obtain a target contact pressure distribution, including:

[0024] According to the spatial position features, the geometric center coordinates of each stress concentration region in the contact surface coordinate system are extracted.

[0025] Based on the stress gradient features, a stress concentration region with the maximum stress gradient amplitude is identified as a dominant stress concentration region, and the maximum principal direction of the stress gradient vector field of the dominant stress concentration region is extracted as a stress concentration principal direction.

[0026] a direction opposite to the main direction of the stress concentration is determined as a stress release direction, and a driving force action position of the movable contact point is traced back to the geometric center coordinate as a target point along the stress release direction to obtain a driving force application path;

[0027] According to the driving force application path, the contact posture between the movable contact point and the static contact point is adjusted, and the movable contact point moves along the driving force application path to the static contact point under the action of the driving force;

[0028] Based on the adjusted contact posture, each contact microelement is re-divided, and the normal pressure value of the contact microelement under the adjusted contact posture is calculated according to the constitutive relation to obtain a redistributed contact pressure distribution;

[0029] The redistributed contact pressure distribution is taken as the target contact pressure distribution.

[0030] Based on the target contact pressure distribution and the fatigue life constraint condition of the contact point material, a segmented motion control instruction of the movable contact point is generated, including:

[0031] According to the target contact pressure distribution, the normal pressure value of each contact microelement in the target contact pressure distribution is extracted, and the contact stress value of each contact microelement is calculated based on the normal pressure value and the area of the contact microelement;

[0032] The contact stress value of each contact microelement is compared with the fatigue strength limit value of the contact point material, and the contact microelement whose contact stress value exceeds the fatigue strength limit value is identified as a fatigue risk microelement, and the distribution density of the fatigue risk microelement on the contact point surface is counted;

[0033] According to the stress-life curve of the contact point material, a mapping relationship between the contact stress value and the fatigue cycle number is established;

[0034] Based on the mapping relationship and the contact stress value of each contact microelement, the allowable fatigue cycle number of each contact microelement under the current contact stress level is calculated, and the minimum value of the allowable fatigue cycle number of all contact microelements is determined as the fatigue life constraint value of the contact point system;

[0035] According to the distribution density of the fatigue risk microelement and the fatigue life constraint value, the complete motion stroke of the movable contact point is divided into multiple stages, and the corresponding segmented motion control instruction is set for each stage.

[0036] The complete motion stroke of the movable contact point is divided into multiple stages, and the corresponding segmented motion control instruction is set for each stage, including:

[0037] The complete motion stroke includes a pre-contact section, a contact establishment section and a steady-state contact section, wherein the pre-contact section corresponds to a stage in which the moving contact approaches the stationary contact from the static position but no contact occurs, the contact establishment section corresponds to a stage in which the moving contact and the stationary contact are initially contacted to establish a target contact pressure distribution, and the steady-state contact section corresponds to a stage in which the target contact pressure distribution is maintained stably;

[0038] For the pre-contact section, a constant-speed motion instruction is generated to control the moving contact to move towards the stationary contact at a preset approach speed;

[0039] For the contact establishment section, a speed attenuation curve of the contact establishment section is calculated according to the distribution density of the fatigue risk element, the speed attenuation curve describes a change process in which the speed of the moving contact gradually decreases from the preset approach speed to zero, and a variable-speed motion instruction is generated to control the moving contact to move according to the speed attenuation curve;

[0040] For the steady-state contact section, an upper limit of the duration of the steady-state contact section is calculated according to the fatigue life constraint value, and a holding motion instruction is generated to control the moving contact to maintain the contact state with the stationary contact within the upper limit of the duration;

[0041] The constant-speed motion instruction, the variable-speed motion instruction and the holding motion instruction are combined in time sequence to obtain a segmented motion control instruction of the moving contact.

[0042] The second aspect of the embodiment of the application provides a contact pressure distribution system of a moving and stationary contact of a micro relay, which comprises:

[0043] A first unit is configured to acquire contact system state information of the micro relay, divide the micro relay into a plurality of contact elements according to a displacement amount of the moving contact and a deformation amount of the stationary contact in the contact system state information, establish a force-displacement response characteristic of each contact element, and associate and map the force-displacement response characteristic with a contact resistance in the contact system state information to obtain an initial contact pressure distribution;

[0044] A second unit is configured to identify a stress concentration area of a contact surface according to the initial contact pressure distribution, and extract spatial position features and stress gradient features corresponding to the stress concentration area;

[0045] A third unit is configured to redistribute the initial contact pressure distribution by adjusting a driving force application path of the moving contact according to the spatial position features and the stress gradient features to obtain a target contact pressure distribution;

[0046] A fourth unit is configured to generate a segmented motion control instruction of the moving contact based on the target contact pressure distribution and a fatigue life constraint condition of a contact material, and the segmented motion control instruction specifies a speed variation law and a pressure loading time sequence of the moving contact at different stages in a contact stroke.

[0047] a fifth unit configured to send the segmented motion control instruction to the driving mechanism, and control the driving mechanism to drive the moving contact to complete the contact process with the stationary contact according to the segmented motion control instruction.

[0048] a third aspect of the embodiment of the application,

[0049] An electronic device is provided, comprising:

[0050] a processor;

[0051] a memory for storing processor-executable instructions;

[0052] The processor is configured to invoke the instructions stored in the memory to execute the method described above.

[0053] a fourth aspect of the embodiment of the application,

[0054] A computer-readable storage medium is provided, which stores computer program instructions, and the computer program instructions are executed by a processor to implement the method described above.

[0055] The beneficial effects of the present application are as follows:

[0056] By acquiring the contact system state information and establishing the micro-element force-displacement response characteristics, the accurate analysis of the contact pressure is realized, the contact stress distribution is visualized and quantified, and the problem that the complex contact interface pressure distribution is difficult to accurately characterize in the traditional method is overcome.

[0057] Based on the identified stress concentration area features, the path of the moving contact driving force is intelligently adjusted, the uniform redistribution of the contact pressure is realized, the stress concentration phenomenon in the local area is effectively alleviated, the service life of the contact is prolonged, and the reliability of the relay is improved.

[0058] The segmented motion control strategy is adopted, the fine moving contact motion instruction is generated according to the contact material fatigue life constraint condition, the speed change and pressure loading time sequence of the moving contact in the contact process are optimized, the contact impact damage is reduced, the electrical life and mechanical life of the relay are improved, and the contact bounce phenomenon is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 Fig. 1 is a flowchart of the contact pressure distribution method for the micro relay moving and stationary contacts of the embodiment of the application;

[0060] Figure 2 Fig. 2 is a flowchart for generating the segmented motion control instruction of the moving contact. DETAILED DESCRIPTION

[0061] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0062] The technical solutions of the present application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes can not be described in some embodiments.

[0063] Figure 1 The flowchart of the contact pressure distribution method for the micro relay moving contact and stationary contact of the embodiments of the present application is shown in FIG. 1, which comprises the following steps. Figure 1

[0064] The contact system state information of the micro relay is obtained, and the micro relay is divided into multiple contact microelements according to the moving contact displacement and the stationary contact deformation in the contact system state information, and the force-displacement response characteristics of each contact microelement are established. The force-displacement response characteristics are associated and mapped with the contact resistance in the contact system state information to obtain an initial contact pressure distribution.

[0065] The stress concentration area of the contact surface is identified according to the initial contact pressure distribution, and the spatial position characteristics and stress gradient characteristics corresponding to the stress concentration area are extracted.

[0066] According to the spatial position characteristics and stress gradient characteristics, the initial contact pressure distribution is redistributed by adjusting the driving force application path of the moving contact to obtain a target contact pressure distribution.

[0067] Based on the target contact pressure distribution and the fatigue life constraint condition of the contact material, a segmented motion control instruction of the moving contact is generated, which specifies the speed variation law and pressure loading time sequence of the moving contact at different stages in the contact stroke.

[0068] The segmented motion control instruction is sent to the driving mechanism to control the driving mechanism to drive the moving contact to complete the contact process with the stationary contact according to the segmented motion control instruction.

[0069] ​In an alternative embodiment, the micro relay is divided into a plurality of contact micro elements according to the moving contact displacement and the static contact deformation in the contact system state information, and a force-displacement response characteristic of each contact micro element is established. The force-displacement response characteristic is associated and mapped with the contact resistance in the contact system state information to obtain the initial contact pressure distribution, including:

[0070] According to the moving contact displacement and the static contact deformation in the contact system state information, the normal distance distribution between the moving contact surface and the static contact surface is calculated to obtain the gap field of the contact interface.

[0071] The region with a zero gap value in the gap field is taken as the actual contact region, and the actual contact region is divided into a plurality of contact micro elements.

[0072] For each contact micro element, a constitutive relation between the local stress tensor and the local strain tensor of the contact micro element is established. The constitutive relation determines the deformation response of the contact micro element under a three-dimensional stress state based on the elastic modulus and Poisson's ratio of the contact material.

[0073] According to the constitutive relation, a virtual normal displacement load is applied to each contact micro element, and the normal reaction force and the tangential reaction force generated by the contact micro element under the action of the virtual normal displacement load are calculated to obtain the force-displacement response characteristic of each contact micro element.

[0074] The force-displacement response characteristic is associated and mapped with the contact resistance in the contact system state information to establish a coupling relationship between the contact pressure distribution and the conductive contact area.

[0075] Based on the coupling relationship, the measured value of the contact resistance between the contacts is taken as the boundary condition, and the normal pressure value of each contact micro element that satisfies the boundary condition is reversely solved to obtain the initial contact pressure distribution.

[0076] For example, the contact system state information is obtained, including the moving contact displacement, the static contact deformation, and the contact resistance. For example, for a typical micro relay, the moving contact displacement is 15 μm, the static contact deformation is 3 μm, and the initial contact resistance is 20 mΩ. Based on these state information, the normal distance distribution between the moving contact surface and the static contact surface is calculated to obtain the gap field of the contact interface. The calculation process can be realized by calculating the point-to-point distance of the moving contact surface and the static contact surface in the common coordinate system. For example, in a contact area of 100 μm x 100 μm, 5000 x 5000 grid points can be established, and the vertical distance between the two surfaces is calculated for each grid point to form a gap field matrix.

[0077] According to the calculated gap field, the region where the gap value is zero is determined as the actual contact region. In practical applications, gap values less than 0.01 μm can be considered as zero, taking into account measurement errors and numerical calculation accuracy. For example, in the above calculation, it is found that the gap values in the central region of about 30 μm x 30 μm are less than the threshold value, and this region can be determined as the actual contact region.

[0078] The actual contact region is divided into a plurality of contact microelements. In this embodiment, the contact region can be uniformly divided into 5 μm x 5 μm square microelements, forming about 36 contact microelements. For each contact microelement, a constitutive relationship between the local stress tensor and the local strain tensor of the contact microelement is established. The constitutive relationship determines the deformation response of the contact microelement under a three-dimensional stress state based on the elastic modulus and Poisson's ratio of the contact material. For example, for a gold contact material, the elastic modulus is 78 GPa and the Poisson's ratio is 0.42, and an isotropic linear elastic constitutive relationship can be established accordingly.

[0079] After the constitutive relationship is established, a virtual normal displacement load is applied to each contact microelement, and the normal reaction force and the tangential reaction force generated by the contact microelement under the action of the virtual normal displacement load are calculated to obtain the force-displacement response characteristics of each contact microelement. Specifically, different displacement loads of 0.1 μm, 0.2 μm, 0.3 μm, etc. can be applied to each microelement in turn, and the corresponding reaction force response is recorded. For example, for a typical microelement in the central region, when a displacement of 0.1 μm is applied, a normal reaction force of 1.2 mN is generated, and when a displacement of 0.2 μm is applied, the normal reaction force increases to 2.5 mN.

[0080] Based on the force-displacement response characteristics of each contact microelement obtained as described above, the contact force of each microelement under a given displacement can be obtained. According to the contact mechanics theory, the microelement contact force F is in a proportional relationship with the contact pressure P of the microelement: P = F / S, where S is the area of the microelement. At the same time, according to the electrical contact theory, the real conductive contact area A is in a proportional relationship with the contact pressure P: A = k x P, where k is a material-related coefficient, which can be obtained by k = π / (4H), and H is the hardness of the contact material. For a gold contact material (hardness about 1000 MPa), k is about 0.00025 mm 2 / N. Further, the resistance Ri of the microelement is inversely proportional to its conductive contact area A: Ri = p / A, where p is the contact resistivity. Through this series of relationships, the mapping of the force-displacement response characteristics to the contact resistance is realized, and the coupling relationship between the contact pressure distribution and the conductive contact area is established.

[0081] Based on the coupling relationship, the normal pressure value of each contact microelement satisfying the boundary condition is reversely solved with the measured contact resistance between the contacts as the boundary condition, to obtain the initial contact pressure distribution. Specifically, assuming that the total resistance of the contact is R, according to the parallel circuit principle, the resistance Ri of each contact microelement is inversely proportional to the conductive contact area Ai of the microelement: Ri = p / Ai, wherein p is the contact resistivity. The parallel value of the resistance of each microelement should be equal to the total resistance R. Through an iterative optimization algorithm, the pressure distribution of each microelement that makes the total resistance equal to the measured value can be solved.

[0082] For example, for the aforementioned micro relay, the measured contact resistance is 20 mΩ, and through reverse solving, the normal pressure of the microelement in the central region is about 10 MPa, and the normal pressure of the microelement in the edge region is about 5 MPa. The pressure distribution of the entire contact region presents the characteristics of high center and low edge, which is consistent with the actual contact situation. This pressure distribution can be used as the initial condition for subsequent dynamic contact analysis, and provides a basis for accurately predicting the contact performance of the relay.

[0083] The present application can accurately reflect the real contact state of the contact interface by accurately calculating the normal distance distribution between the moving and static contacts, dividing the actual contact area into microelements, and establishing the constitutive relationship. Through virtual normal displacement load calculation and reverse solving of the measured contact resistance value, a coupling relationship between the pressure distribution and the conductive area is established, so that the initial contact pressure distribution is more accurate, and a reliable foundation is provided for subsequent optimization.

[0084] In an optional implementation, identifying a stress concentration region on the contact surface according to the initial contact pressure distribution, and extracting spatial position features and stress gradient features corresponding to the stress concentration region include:

[0085] Converting the normal pressure value of each contact microelement in the initial contact pressure distribution into a normal stress value, and constructing a stress field distribution of the contact surface; performing spatial derivation operation on the normal stress value of each contact microelement in the stress field distribution to obtain the stress spatial gradient at the position of each contact microelement;

[0086] When the stress spatial gradient of a contact microelement exceeds a gradient statistical threshold, marking the contact microelement as a stress concentration microelement; clustering spatially adjacent stress concentration microelements to form a stress concentration microelement cluster, and each stress concentration microelement cluster corresponds to a stress concentration region;

[0087] For each stress concentration region, calculating the coordinate average value of the stress concentration microelements in the stress concentration region to obtain a geometric center coordinate, identifying a coordinate sequence of the stress concentration microelements located at the edge position to form a boundary contour, and combining the geometric center coordinate and the boundary contour to obtain the spatial position features corresponding to the stress concentration region;

[0088] For each stress concentration region, the rate of change of stress value with spatial distance is extracted from a plurality of radial paths extending from the geometric center coordinates of the stress concentration region along the boundary contour, a stress gradient vector field of the stress concentration region is synthesized and the gradient amplitude corresponding to the maximum principal direction is extracted as the stress gradient characteristic corresponding to the stress concentration region.

[0089] Exemplarily, after obtaining the initial contact pressure distribution of the micro relay, it is necessary to further identify the stress concentration regions of the contact surface and extract the key characteristics of these regions to provide a basis for subsequent pressure redistribution. For each contact micro element in the initial contact pressure distribution, the normal stress value σ of the micro element can be obtained by dividing the normal pressure value P of the micro element by the actual contact area S of the micro element, i.e. σ = P / S. For example, for a micro element with an area of 25 μm 2 , if the normal pressure value is 0.25 mN, the calculated normal stress value is 10 MPa. In this way, the normal pressure values of all contact micro elements are converted into corresponding normal stress values to form a complete stress field distribution of the contact surface.

[0090] The spatial derivation operation is performed on the normal stress values of each contact micro element in the constructed stress field distribution, and the central difference method is adopted. For a contact micro element with position coordinates (x, y), the component of the stress spatial gradient in the x direction is calculated as G x =(σ(x+Δx,y)-σ(x-Δx,y)) / (2Δx), and the component in the y direction is calculated as G y =(σ(x,y+Δy)-σ(x,y-Δy)) / (2Δy), where Δx and Δy are the spacings of adjacent micro elements in the x and y directions, and the values are the side lengths of the micro elements, for example 5 μm. By integrating the gradient components in the x and y directions, the modulus G of the stress spatial gradient at the position of the micro element can be obtained, which is equal to the square root of the sum of the squares of the gradient components in the x and y directions. This spatial derivation operation is performed on all contact micro elements on the contact surface to generate a complete stress gradient field.

[0091] After the stress gradient field is generated, the stress concentration regions are identified. The determination of the gradient statistical threshold value is based on the statistical characteristics of the global stress gradient distribution, and the average value of the stress gradient values of all contact micro elements plus 2 times the standard deviation is taken as the gradient statistical threshold value. For example, assuming that the average value of the stress gradient of all contact micro elements is 0.5 MPa / μm and the standard deviation is 0.2 MPa / μm, the gradient statistical threshold value is set to 0.9 MPa / μm. For the contact micro elements with a stress gradient exceeding 0.9 MPa / μm, they are marked as stress concentration micro elements.

[0092] The distance-based region growing algorithm is used to cluster the spatially adjacent stress concentration elements. Starting from any unclassified stress concentration element, it is set as a seed point, and the elements in its four or eight neighborhoods are checked. If the neighboring element is also a stress concentration element, it is added to the current element cluster and used as a new seed point to continue the expansion. When the expansion cannot continue, the formation of an element cluster is completed, corresponding to a stress concentration region. The process is repeated for the remaining unclassified stress concentration elements until all stress concentration elements are assigned to a certain element cluster. In practical applications, a minimum cluster size threshold, for example, 3 elements, can be set. Element clusters smaller than this threshold are considered noise and ignored.

[0093] For each stress concentration region, the sum of the horizontal coordinates of all stress concentration elements in the region is divided by the total number of elements to obtain the horizontal coordinate of the center point. The sum of the vertical coordinates of all elements is divided by the total number of elements to obtain the vertical coordinate of the center point, thereby determining the geometric center position of the stress concentration region. At the same time, the edge position stress concentration element is defined as: at least one directly adjacent element does not belong to the current stress concentration region. By checking the neighborhood state of each stress concentration element, the edge element can be identified, and its coordinates can be arranged in a clockwise or counterclockwise direction to form a closed boundary contour. The geometric center coordinates and the boundary contour are combined to obtain the spatial position characteristics corresponding to the stress concentration region.

[0094] For each stress concentration region, the rate of change of stress value with respect to spatial distance is extracted along multiple radial paths extending from the geometric center coordinates of the region to the boundary contour. In specific implementation, multiple radial lines are extended from the geometric center to different angles, with an angle interval of 15° or 30°, forming 12 or 24 radial paths. Along each radial path, the stress value is sampled at a fixed step (e.g., 1 μm), and the ratio of the stress difference between adjacent sampling points to the distance is calculated to obtain the stress change rate on the path. The change rate calculation method is the difference between the stress values of adjacent sampling points divided by the distance between the two points, where the difference between the stress values of the first and second sampling points is the numerator, and the sampling step between the two points is the denominator, to obtain the stress change rate on the path.

[0095] Based on the stress change rate on each radial path, the stress gradient vector field of the stress concentration area is synthesized. In the polar coordinate system, the stress change rate on each radial path corresponds to a gradient component of a specific angle. By combining these components, the gradient vector field distribution of the entire stress concentration area can be obtained. The maximum principal direction is found from the gradient vector field, that is, the direction with the maximum gradient amplitude. The specific operation is as follows: the average amplitude of the gradient on each radial path is calculated, and the angle corresponding to the path with the maximum amplitude is determined, which is the maximum principal direction. The gradient amplitude corresponding to the maximum principal direction is extracted as the stress gradient characteristic of the stress concentration area. For example, if the average gradient amplitude in the 45° direction is 1.2 MPa / μm, and it is the maximum value in all radial paths, then 45° is the maximum principal direction, and 1.2 MPa / μm is the stress gradient characteristic value of the stress concentration area.

[0096] The present application can accurately identify the stress concentration area by converting the normal pressure into stress value and calculating the spatial gradient. By clustering to form micro-element clusters and extracting geometric features, combined with radial path analysis and principal direction gradient extraction, the accurate positioning and feature quantization of the stress concentration area are realized.

[0097] In an optional implementation, according to the spatial position feature and the stress gradient feature, the initial contact pressure distribution is redistributed by adjusting the driving force application path of the moving contact, to obtain a target contact pressure distribution.

[0098] According to the spatial position feature, the position of the geometric center coordinates of each stress concentration area in the contact surface coordinate system is extracted.

[0099] Based on the stress gradient feature, the stress concentration area with the maximum stress gradient amplitude is identified as the dominant stress concentration area, and the maximum principal direction of the stress gradient vector field of the dominant stress concentration area is extracted as the stress concentration principal direction.

[0100] The reverse direction of the stress concentration principal direction is determined as the stress release direction, and the driving force application path is obtained by tracing back to the driving force action position of the moving contact along the stress release direction with the geometric center coordinates as the target point.

[0101] According to the driving force application path, the contact posture between the moving contact and the static contact is adjusted, so that the moving contact moves towards the static contact along the driving force application path under the action of the driving force.

[0102] Based on the adjusted contact posture, each contact micro-element is redivided, and the normal pressure value of the contact micro-element under the adjusted contact posture is calculated according to the constitutive relation, to obtain the redistributed contact pressure distribution.

[0103] The redistributed contact pressure distribution is taken as the target contact pressure distribution.

[0104] Exemplarily, after the spatial location features and stress gradient features of the contact surface stress concentration regions are obtained, the driving force application path of the moving contact needs to be adjusted according to these features, so as to realize the redistribution of the contact pressure. The contact surface coordinate system is defined as a straight angle coordinate system with the center of the contact surface as the origin and parallel to the contact surface. The geometric center coordinates of each stress concentration region are obtained by the foregoing calculation, and these coordinate data are stored in a position information array. The structure of the position information array is a two-dimensional array, each row containing an identifier of a stress concentration region and the coordinate values of the geometric center thereof. For a typical micro relay contact system, 3 to 5 stress concentration regions are identified, and the geometric center coordinates thereof are located at different positions of the contact surface. For example, in a contact area of 100 μm x 100 μm, the geometric center of a main stress concentration region is located at coordinates (35 μm, 42 μm), and another secondary concentration region is located at (-20 μm, -15 μm).

[0105] The stress gradient amplitudes of the stress concentration regions are compared, and the one with the maximum amplitude is selected as the dominant stress concentration region. The comparison of the stress gradient amplitudes is performed in a direct numerical comparison manner without setting a threshold value. For example, assuming that three stress concentration regions are detected, and the stress gradient amplitudes thereof are 1.2 MPa / μm, 0.8 MPa / μm and 0.5 MPa / μm respectively, the first region (1.2 MPa / μm) is selected as the dominant stress concentration region. The maximum principal direction is extracted from the stress gradient vector field data of the dominant region, that is, the angle at which the gradient vector points. The angle is expressed in polar coordinates, and the clockwise rotation is positive with the positive direction of the x axis of the contact surface coordinate system as 0°. For example, the maximum principal direction of the dominant stress concentration region is 135°, indicating that the pressure gradient is the largest in the left-up direction from the origin.

[0106] The stress release direction is 180° different from the stress concentration main direction. If the stress concentration main direction is 135°, the stress release direction is 315° (or -45°). A straight line is extended from the geometric center coordinates along the stress release direction, and the intersection of the straight line and the feasible driving region of the moving contact is the recommended driving force action position. The feasible driving region is usually the edge region of the moving contact or a specially designed driving force receiving structure. The driving force application path is defined as a straight line path from the action position to the geometric center coordinates. The path is expressed by the start point coordinates, the end point coordinates and the path direction angle. For the foregoing example, if the geometric center coordinates of the dominant stress concentration region are (35 μm, 42 μm), the stress release direction is 315°, and the boundary of the feasible driving region of the moving contact is located at the intersection of the straight line and the coordinates (-25 μm, -18 μm), the start point of the driving force application path is (-25 μm, -18 μm), the end point is (35 μm, 42 μm), and the path direction angle is 135°.

[0107] According to the determined driving force application path, the contact posture adjustment includes both position offset and angle deflection of the moving contact. The position offset refers to the relative displacement of the moving contact center with respect to the stationary contact center, and the angle deflection refers to the adjustment of the included angle between the moving contact plane and the stationary contact plane. The specific adjustment method depends on the structural type of the relay. For a planar micro relay, the position offset can be achieved by fine-tuning the support structure or the driving electrode position of the moving contact; for a rotating micro relay, the angle deflection can be achieved by adjusting the position of the rotating shaft or the limiting structure. The adjustment amount is determined by the direction and length of the driving force application path, and generally the position offset is in the range of 1 μm to 5 μm, and the angle deflection is in the range of 0.1° to 0.5°. For the aforementioned example, according to the driving force application path, the moving contact center needs to be offset by 3 μm in the direction of 135°, and the moving contact plane needs to be rotated counterclockwise by 0.2° around the axis perpendicular to the direction of 135°.

[0108] The contact micro-element redivision uses the same grid size and method as the initial division, but is based on the adjusted contact posture. The micro-element size is usually maintained at 5 μm x 5 μm to ensure consistency in calculation. For each newly divided contact micro-element, the normal pressure value of the micro-element in the new posture is calculated by applying the established constitutive relation. The calculation process takes into account the elastic deformation characteristics of the material and the influence of surface roughness. For gold contact material, the elastic modulus is 78 GPa and the Poisson's ratio is 0.42. In the calculation, the virtual displacement method is applied, and a virtual displacement corresponding to the contact depth is applied to each contact micro-element, and the corresponding normal reaction force is solved through the constitutive relation, and the normal pressure value is obtained by dividing the micro-element area. For example, under the adjusted contact posture, the contact depth of a certain micro-element originally in the stress concentration area decreases by 20%, resulting in a decrease in the normal pressure value from the original 10 MPa to about 6 MPa; while in the area of insufficient contact, the contact depth increases by 30%, causing the normal pressure value to increase from the original 2 MPa to about 4 MPa.

[0109] The redistributed contact pressure distribution is taken as a target contact pressure distribution, and the target contact pressure distribution is stored in a two-dimensional matrix form, and the matrix size is consistent with the microelement division of the contact area. For example, for a 5x5 microelement division mode, a 20x20 pressure distribution matrix is formed in a 100 μm x 100 μm contact area. Each element in the matrix represents the normal pressure value of the corresponding position microelement, and the unit is MPa. The pressure distribution can be converted into a heat map through a visualization technology to intuitively display the pressure distribution condition. In an ideal case, the target contact pressure distribution should present a relatively uniform feature, and the ratio of the maximum pressure value to the minimum pressure value is not more than 3:1. For example, the pressure distribution before adjustment reaches 12 MPa in the main stress concentration area, and only 1 MPa in the edge area, and the target distribution after adjustment is distributed between 3 MPa and 9 MPa in the whole contact area, which significantly improves the pressure uniformity. The evaluation index of pressure uniformity can adopt the ratio of pressure standard deviation to average value, that is, the coefficient of variation. The coefficient of variation of the target contact pressure distribution should generally be less than 0.5, and the coefficient of variation before adjustment is as high as 0.8 or more.

[0110] The present application realizes the redistribution of the contact pressure between the moving and stationary contacts of the micro relay based on stress analysis, effectively improves the uniformity of the contact pressure distribution, reduces the local stress concentration phenomenon, and prolongs the service life of the contact system.

[0111] In an optional embodiment, based on the target contact pressure distribution and the fatigue life constraint condition of the contact material, the segmented motion control instruction of the moving contact is generated, including:

[0112] According to the target contact pressure distribution, the normal pressure value of each contact microelement in the target contact pressure distribution is extracted; and based on the normal pressure value and the area of the contact microelement, the contact stress value of each contact microelement is calculated;

[0113] The contact stress value of each contact microelement is compared with the fatigue strength limit value of the contact material, the contact microelement whose contact stress value exceeds the fatigue strength limit value is identified as a fatigue risk microelement, and the distribution density of the fatigue risk microelement on the contact surface is counted;

[0114] According to the stress-life curve of the contact material, a mapping relationship between the contact stress value and the fatigue cycle number is established;

[0115] Based on the mapping relationship and the contact stress value of each contact microelement, the allowable fatigue cycle number of each contact microelement under the current contact stress level is calculated; and the minimum value of the allowable fatigue cycle number of all contact microelements is determined as the fatigue life constraint value of the contact system;

[0116] According to the distribution density of the fatigue risk microelement and the fatigue life constraint value, the complete motion stroke of the moving contact is divided into multiple stages, and corresponding segmented motion control instructions are set for each stage.

[0117] In combination Figure 2 The segmented motion control instruction generation flowchart of the moving contact is described. When generating the segmented motion control instruction of the moving contact according to the target contact pressure distribution and the fatigue life constraint condition of the contact material, the system needs to consider the stress state of the contact microelement and the material fatigue characteristics. This process extracts the normal pressure value of each contact microelement from the target contact pressure distribution data obtained as described above. The target contact pressure distribution is stored in the form of a two-dimensional matrix, and each element of the matrix corresponds to the normal pressure value of a contact microelement. The microelement size is usually set to 5 μm × 5 μm, which ensures the calculation accuracy and controls the calculation amount within a reasonable range. The data extraction adopts a matrix scanning method, which traverses each element in the 20 × 20 pressure distribution matrix and reads the pressure value into the contact pressure array. The array adopts a plane array structure, and each element contains the coordinate index of the microelement and the corresponding normal pressure value. For example, for the contact microelement located at the matrix coordinate (8, 12), the normal pressure value is 6.5 MPa, and this information is stored as a record.

[0118] Based on the extracted normal pressure value and the area of the contact microelement, for a contact microelement with a constant size, the area is the square of the microelement side length, that is, 25 μm 2 . The calculation of the contact stress value takes into account the micro characteristics of the contact interface, especially the influence of surface roughness. The actual contact area is usually smaller than the nominal contact area, so the surface roughness correction coefficient is applied to adjust the calculation. The value of this coefficient ranges from 0.6 to 0.9, depending on the surface processing technology and roughness grade of the contact, and for an electrolytic polished metal contact surface, the correction coefficient is usually 0.8. The contact stress value is equal to the normal pressure value divided by the microelement area and then divided by the surface roughness correction coefficient. For example, the contact stress value of a microelement with a normal pressure value of 6.5 MPa is calculated as 6.5 / (25 × 10 -12 ) ÷ 0.8 = 325 MPa. The calculation precision is retained to 0.1 MPa, and the rounding method is used for processing.

[0119] The fatigue strength limit is the maximum stress value under which a material does not fail due to fatigue under infinite cyclic loading, also known as fatigue limit. For commonly used contact materials, such as silver alloy, the fatigue strength limit is about 150 MPa; for gold alloy, about 200 MPa; for copper alloy, about 175 MPa. The identification of fatigue risk elements uses a direct comparison method, i.e. if the contact stress value of an element exceeds the fatigue strength limit of the material used, the element is marked as a fatigue risk element and recorded in the risk element index array. The distribution density calculation uses a region division method, which divides the contact surface into 4x4 regions, counts the number of fatigue risk elements in each region, and divides by the total number of elements in the region to obtain the fatigue risk element density of the region. For example, for a certain region, if it contains 25 elements, of which 8 are fatigue risk elements, the fatigue risk element density of the region is 32%.

[0120] According to the stress-life curve of the contact material, the Basquin equation is used to describe the fatigue cycle number, which is equal to the material coefficient multiplied by the negative power of the contact stress value. The power is usually between 10 and 15, and the material coefficient depends on the specific contact material. For silver alloy contacts, the material coefficient is about 5x10 30 , and the power is 12; for gold alloy contacts, the material coefficient is about 8x10 32 , and the power is 13.5; for copper alloy contacts, the material coefficient is about 2x10 31 , and the power is 12.5. This mapping relationship is realized using a lookup table, which pre-calculates and stores the corresponding fatigue cycle number for common stress levels and uses linear interpolation to handle intermediate values. The stress resolution of the lookup table is 5 MPa, covering a range from 50 MPa to 600 MPa. For example, for gold alloy contacts, the fatigue cycle number corresponding to a stress value of 325 MPa is about 7.2x10

[0121] For each contact element, the corresponding fatigue cycle number is obtained by querying the mapping table according to its contact stress value. The query uses the nearest principle, and if the contact stress value is between two table entries, the corresponding fatigue cycle number is calculated using linear interpolation. For elements with a stress value below the fatigue strength limit, the allowable fatigue cycle number is considered to be infinite, and in actual calculation, a large enough value is used, such as 1x10 5 . The minimum value of the allowable fatigue cycle number of all contact elements is determined as the fatigue life constraint value of the contact system. The search process of the minimum value excludes elements with extremely low contact pressure, which may cause abnormal fatigue life prediction due to numerical calculation errors. Specifically, a contact pressure lower limit of 0.5 MPa is set, and only elements with a pressure higher than this value are considered. For example, if the minimum allowable fatigue cycle number calculated is 4.5x10 5 , then the fatigue life constraint value of the contact system is this value.

[0122] According to the distribution density of fatigue risk microelement and the fatigue life constraint value, the complete motion stroke of the moving contact is divided into multiple stages, which is based on the displacement of the moving contact from the initial position to the final contact position, which depends on the specific structure of the relay, usually between 50 pm and 300 pm. The stroke division adopts a risk density oriented strategy, that is, according to the distribution density of fatigue risk microelement, the stroke is divided into several stages, and the stroke segment corresponding to the region with high risk density should adopt lower motion speed and slower pressure loading rate. Typically, the stroke is divided into three to five stages, and the length of each stage is not equal, but is determined according to the risk density distribution. If the risk density shows an increasing trend, the stroke segment of the subsequent stage should be shortened; if it shows a decreasing trend, the stroke segment of the subsequent stage can be appropriately lengthened.

[0123] The segmented motion control instruction contains four core parameters of start-stop position, motion speed, acceleration-deceleration characteristics and pressure loading rate of each stage. The start-stop position is expressed in percentage of displacement relative to the initial position, such as 0%-30% for the first stage, 30%-70% for the second stage, and 70%-100% for the third stage. The motion speed parameter is in units of millimeters per second, which is determined according to the fatigue risk density, the higher the risk density, the lower the speed setting. For example, for low-risk areas (density <10%), the speed can be set to 5 mm / s; for medium-risk areas (density 10%-30%), the speed is set to 2 mm / s; for high-risk areas (density >30%), the speed is set to 0.5 mm / s. The acceleration-deceleration characteristics describe the speed change law, which usually uses a trapezoidal speed curve, that is, a combination of uniform acceleration-uniform speed-uniform deceleration. The proportion of acceleration-deceleration segment is set to 15% to 20% of the total stroke, to smooth the speed change and reduce the impact. The pressure loading rate parameter describes the increase rate of contact pressure per unit time, in units of megapascal per second. The higher the risk density, the lower the pressure loading rate should be, in order to slow down the stress accumulation speed. The typical setting is: 100 MPa / s for low-risk areas, 50 MPa / s for medium-risk areas, and 20 MPa / s for high-risk areas.

[0124] The format of the control instruction is represented by time series, i.e. the position, velocity and loading pressure of the moving contact at discrete time points. The time resolution is 1 millisecond, and the time span of the entire contact process is usually between 50 milliseconds and 200 milliseconds. The data is stored as a three-column time series, with the first column being the time stamp, the second column being the position value, the third column being the velocity value, and the fourth column being the pressure value. For example, at time point t = 15 ms, the control instruction specifies a position of 45 μm, a velocity of 2 mm / s, and a pressure of 30 MPa. The control instruction is transmitted to the execution driver through a communication interface, and the driver calculates the control parameters at intermediate time points using an interpolation algorithm to achieve smooth control. The communication uses RS-485 or CAN bus, and the data frame format is start identifier (1 byte), time stamp (4 bytes), position value (4 bytes), velocity value (4 bytes), pressure value (4 bytes) and checksum (2 bytes). The communication rate is set to 115200 bps, which is sufficient to meet the millisecond-level control accuracy requirement.

[0125] The present application identifies the fatigue risk microelement by calculating the stress value of the contact microelement and comparing it with the material fatigue strength, establishes a stress-life mapping relationship, and determines the fatigue life constraint of the contact system. This motion control strategy based on material properties and fatigue mechanism can effectively prevent premature failure of the contact, prolong the service life of the relay, and improve the reliability and stability of the system.

[0126] In an alternative embodiment, the complete motion stroke of the moving contact is divided into multiple stages, and corresponding segmented motion control instructions are set for each stage, including:

[0127] The complete motion stroke includes a pre-contact segment, a contact establishment segment and a steady-state contact segment, wherein the pre-contact segment corresponds to the stage where the moving contact approaches the stationary contact from the static position without contact, the contact establishment segment corresponds to the stage where the moving contact and the stationary contact initially contact to establish the target contact pressure distribution, and the steady-state contact segment corresponds to the stage where the target contact pressure distribution is maintained stable;

[0128] For the pre-contact segment, a constant speed motion instruction is generated to control the moving contact to move towards the stationary contact at a preset approach speed;

[0129] For the contact establishment segment, a velocity decay curve of the contact establishment segment is calculated according to the distribution density of the fatigue risk microelement, the velocity decay curve describes the change process of the moving contact velocity gradually decreasing from the preset approach speed to zero, a variable speed motion instruction is generated to control the moving contact to move according to the velocity decay curve;

[0130] For the steady-state contact segment, an upper limit of the duration of the steady-state contact segment is calculated according to the fatigue life constraint value, a holding motion instruction is generated to control the moving contact to maintain the contact state with the stationary contact within the upper limit of the duration;

[0131] The constant speed motion instruction, the variable speed motion instruction and the holding motion instruction are combined in time sequence to obtain a segmented motion control instruction of the moving contact.

[0132] Exemplarily, the complete motion stroke of the moving contact is divided into multiple stages, and a corresponding segmented motion control instruction is set for each stage, which is a core technology to realize high reliability and long service life of the contact system. The complete motion stroke of the moving contact is subdivided into three main stages: a pre-contact segment, a contact establishment segment and a steady-state contact segment. The pre-contact segment refers to the motion stage of the moving contact approaching the stationary contact from the static position but not yet physically contacting, which usually accounts for 40%-60% of the entire stroke, and the distance range is usually 30 μm to 150 μm, depending on the size grade of the relay or switch. The contact establishment segment corresponds to the process of the moving contact first contacting the stationary contact until the target contact pressure distribution is completely established, and this stage is the most critical stage in the contact system, usually accounting for 30%-50% of the entire stroke, and the distance range is 15 μm to 80 μm. The steady-state contact segment refers to the stage where the target contact pressure distribution has been completely established and maintained stable, at which time the moving contact is kept at a specific position to make the contact state stable and continuous to meet the electrical connection requirement.

[0133] For the pre-contact segment, the moving contact is controlled to move towards the stationary contact at a preset approach speed, which is a configurable parameter, and the value range is usually 0.5 mm / s to 10 mm / s, and the default value is 3 mm / s. The selection of the speed value needs to consider multiple factors: for a micro relay, the approach speed is preferably set in a lower range, i.e. 0.5-2 mm / s; for a medium-sized relay, the approach speed can be taken in a medium range, i.e. 2-5 mm / s; and for a large-sized relay, the approach speed can be taken in a higher range, i.e. 5-10 mm / s. The constant speed motion instruction is generated in a time-sharing sampling manner, i.e. the position sequence of the moving contact is calculated at a fixed time interval, usually 1 ms. The position calculation adopts a linear interpolation method, and the position value at each time is equal to the initial position plus the product of the speed and the time. The data structure of the constant speed motion instruction includes an instruction type field, the value of which is 0x01, indicating a constant speed instruction; an initial position field, a 32-bit floating point number, with units of microns; a target position field, a 32-bit floating point number, with units of microns; a speed field, a 32-bit floating point number, with units of millimeters per second; and a motion direction field, the value of which is 0x01 indicating forward, and 0x02 indicating reverse.

[0134] For the contact establishment segment, a velocity decay curve describes the gradual decrease of the moving contact velocity from the preset approach velocity to zero. The calculation of the decay curve is based on the spatial distribution characteristics of the fatigue risk elements, using a partition weighted average method. The contact area is divided into multiple sub-regions, usually a 4x4 grid, and the density of fatigue risk elements in each sub-region is calculated, and then the corresponding velocity decay coefficient is determined according to the density value. The decay coefficient is proportional to the density of fatigue risk elements, the higher the density, the faster the decay. Specifically, the decay curve uses an exponential decay model, where the decay constant is determined by the density of fatigue risk elements. For areas with a risk density below 10%, the decay constant is set to 0.05; for areas with a risk density between 10% and 30%, the decay constant is set to 0.10; for areas with a risk density above 30%, the decay constant is set to 0.20. The contact establishment segment is usually divided into 10-20 discrete sampling points, each corresponding to a velocity value, and the velocity between sampling points is calculated by linear interpolation.

[0135] Based on the calculated velocity decay curve, a variable speed motion instruction is generated to control the moving contact to move according to the curve. The data structure of the variable speed motion instruction includes an instruction type field with a value of 0x02, indicating a variable speed instruction; an initial position field, a 32-bit floating point number; a velocity sequence length field, a 16-bit unsigned integer; and a velocity sequence field, consisting of multiple speed-displacement pairs. Each element in the velocity sequence contains a relative displacement value, a 16-bit signed integer, in microns, and a corresponding speed value, a 16-bit signed integer, in microns per second. The execution of the variable speed instruction uses a segmented acceleration control strategy, i.e. the system calculates the required acceleration based on the current position and target speed, allowing the moving contact to smoothly transition to the target speed. To ensure motion accuracy, the acceleration rate of change, i.e. jerk, is limited to within 1000 mm / s³ to avoid mechanical impact and vibration.

[0136] For the steady-state contact segment, the upper limit of the duration of the steady-state contact segment is calculated based on the fatigue life constraint value. The fatigue life constraint value is the expected number of fatigue cycles of the contact system under the current contact pressure distribution calculated in the previous process. The calculation of the upper limit of the duration takes into account the fatigue accumulation effect, using the linear fatigue accumulation theory. The upper limit of the duration is proportional to the fatigue life constraint value, but also needs to consider the safety factor. Generally, the safety factor is set to 2-5, and a higher safety factor is suitable for situations requiring high reliability. For a fatigue life constraint value of 106 times, if the rated contact time for each operation is 50 ms, and the safety factor is 3, then the upper limit of the duration is calculated as 106 divided by 3 multiplied by 50 ms, which is approximately 16,667 seconds. Considering that the actual application rarely reaches the theoretical upper limit of the duration, the system usually sets a reasonable upper limit of time, such as 30-120 seconds. When this time is exceeded, the system will trigger a warning or protection mechanism.

[0137] Based on the calculated upper limit of the duration, a holding motion instruction is generated, and the data structure of the holding motion instruction includes an instruction type field with a value of 0x03, indicating a holding instruction; a position field, a 32-bit floating-point number, with units of microns; a holding time field, a 32-bit unsigned integer, with units of milliseconds; and a contact pressure field, a 16-bit unsigned integer, with units of kilopascals. During the execution of the holding instruction, the system monitors the contact pressure distribution in real time to ensure its stability. If it is detected that the contact pressure fluctuation exceeds the set threshold, which is usually ±10% of the rated pressure, the moving contact position is automatically adjusted for compensation. The compensation adopts a proportional-integral control strategy, and the response time is usually less than 5 ms to ensure that the contact state quickly recovers to stability.

[0138] The constant speed motion instruction, the variable speed motion instruction, and the holding motion instruction are combined in time sequence to generate a complete moving contact segmented motion control instruction. The instruction combination adopts a sequential execution mechanism, and three consecutive execution stages are set: a pre-contact stage, a contact establishment stage, and a steady-state contact stage. The stage transition is controlled by explicit trigger conditions, for example, the transition from the pre-contact stage to the contact establishment stage is triggered by a contact detection signal, which can be realized by resistance detection, photoelectric detection, or a force sensor. During the instruction combination process, the smooth transition at the stage junction needs to be handled to avoid motion discontinuity caused by instruction switching. The smooth transition is realized by boundary parameter matching, that is, the position, speed, and acceleration of adjacent instruction stages at the junction are ensured to be continuous. During the execution process of the control system, the constant speed motion instruction is first read and executed until the contact signal is detected, then the variable speed motion instruction is switched to execute the contact establishment process, and when the moving contact reaches the target position, the holding motion instruction is switched to maintain the contact state until the time upper limit is reached. During the entire process, the identification variable of the current execution stage, the completion progress percentage, and the start and end time stamps of each stage are maintained for running state monitoring and abnormality handling.

[0139] The complete segmented motion control instruction is organized as an instruction package, including an instruction header and multiple instruction segments. The instruction header includes an instruction package identifier, a 32-bit integer; an instruction package length, a 16-bit integer, with units of bytes; an instruction segment number, an 8-bit integer; and a checksum, a 16-bit integer. Each instruction segment corresponds to a motion stage and is arranged in time sequence. The instruction package is transmitted to the motion control execution unit through the system communication bus, using the CAN or SPI communication protocol, with a communication rate not less than 1 Mbps to ensure the real-time nature of the instruction. After receiving the instruction, the motion control execution unit performs integrity verification and parameter boundary checking, and then executes each instruction segment according to the specified time sequence.

[0140] Taking silver alloy contact as an example, the complete motion stroke is 100 μm, wherein the pre-contact section is 0-60 μm, the contact establishment section is 60-90 μm, and the steady-state contact section is 90-100 μm. The fatigue risk microelement distribution density is: 15% in the early contact establishment stage (60-70 μm), 28% in the middle stage (70-80 μm), and 38% in the later stage (80-90 μm). The fatigue life constraint value is 5*10^5 times. The generated segmented motion control instruction is as follows: the pre-contact section adopts constant speed 3 mm / s, and the motion time is 20 ms; the contact establishment section adopts variable speed instruction, and the speed gradually decreases from 3 mm / s to 0 mm / s, and the specific speed sequence is: the speed is 3 mm / s at the displacement of 60 μm, 2.5 mm / s at 65 μm, 1.8 mm / s at 70 μm, 1.2 mm / s at 75 μm, 0.7 mm / s at 80 μm, 0.3 mm / s at 85 μm, and 0 mm / s at 90 μm, and the motion time of this section is about 50 ms; the steady-state contact section adopts a holding instruction, and the position is kept at 90 μm for 60 seconds, and the contact pressure is 250 kPa. The total length of the whole instruction package is 128 bytes, including 3 instruction sections.

[0141] In the process of executing the segmented motion control instruction, a closed-loop control strategy is adopted to ensure that the actual motion is consistent with the instruction requirements. Position feedback uses a high-precision photoelectric encoder with a resolution of 0.1 μm; speed feedback is calculated by position differentiation, with a sampling frequency of 1 kHz; pressure feedback uses a micro pressure sensor array with an accuracy of 1 kPa. The control algorithm adopts a combination of feedforward and feedback, and the feedforward control is based on the pre-computed control amount based on the system dynamics model, and the feedback control is adjusted according to the actual deviation. The system response time is less than 2 ms, the position accuracy is better than ±0.5 μm, the speed accuracy is better than ±0.1 mm / s, and the pressure accuracy is better than ±5 kPa.

[0142] The application divides the motion of the moving contact into three stages and sets corresponding control instructions, especially using a speed decay curve based on fatigue risk in the contact establishment section and controlling the duration in the steady-state contact section based on fatigue constraints. This segmented control strategy reduces the contact impact, optimizes the stress distribution process, realizes the precise control of dynamic pressure loading, and effectively improves the contact life and the reliability of the relay.

[0143] In a second aspect of the embodiment of the application, a contact pressure distribution system for micro relays is provided, which comprises:

[0144] The first unit is used for obtaining contact system state information of the micro relay, dividing the micro relay into a plurality of contact micro elements according to a moving contact displacement amount and a static contact deformation amount in the contact system state information, establishing force-displacement response characteristics of each contact micro element, and correlating and mapping the force-displacement response characteristics with a contact resistance in the contact system state information to obtain an initial contact pressure distribution.

[0145] The second unit is used for identifying a stress concentration area of a contact surface according to the initial contact pressure distribution, and extracting spatial position characteristics and stress gradient characteristics corresponding to the stress concentration area.

[0146] The third unit is used for redistributing the initial contact pressure distribution by adjusting a driving force application path of the moving contact according to the spatial position characteristics and the stress gradient characteristics, to obtain a target contact pressure distribution.

[0147] The fourth unit is used for generating segmented motion control instructions of the moving contact based on the target contact pressure distribution and a fatigue life constraint condition of the contact material, wherein the segmented motion control instructions define a speed variation law and a pressure loading time sequence of the moving contact at different stages in a contact stroke.

[0148] The fifth unit is used for sending the segmented motion control instructions to a driving mechanism to control the driving mechanism to drive the moving contact to complete a contact process with the static contact according to the segmented motion control instructions.

[0149] The third aspect of the embodiment of the present application provides an electronic device, comprising:

[0150] a processor;

[0151] a memory for storing processor-executable instructions;

[0152] The processor is configured to invoke the instructions stored in the memory to execute the method described above.

[0153] The fourth aspect of the embodiment of the present application provides a computer readable storage medium, which stores computer program instructions, and the computer program instructions are executed by a processor to implement the method described above.

[0154] The present application can be a method, device, system and / or computer program product. The computer program product can include a computer readable storage medium having computer readable program instructions loaded thereon for executing various aspects of the present application.

[0155] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of distributing contact pressure of moving and stationary contacts of a micro relay, characterized by, The method comprises the following steps: acquiring contact system state information of a micro relay, dividing the micro relay into a plurality of contact micro elements according to a moving contact displacement and a static contact deformation in the contact system state information, establishing force-displacement response characteristics of each contact micro element, correlating and mapping the force-displacement response characteristics with a contact resistance in the contact system state information to obtain an initial contact pressure distribution; identifying a stress concentration area on a contact surface according to the initial contact pressure distribution, and extracting spatial position characteristics and stress gradient characteristics corresponding to the stress concentration area; redistributing the initial contact pressure distribution by adjusting a driving force application path of the moving contact according to the spatial position characteristics and the stress gradient characteristics to obtain a target contact pressure distribution; generating segmented motion control instructions of the moving contact based on the target contact pressure distribution and a fatigue life constraint condition of the contact material, the segmented motion control instructions defining a speed variation law and a pressure loading time sequence of the moving contact at different stages in a contact stroke; sending the segmented motion control instructions to a driving mechanism to control the driving mechanism to drive the moving contact to complete a contact process with the static contact according to the segmented motion control instructions.

2. The method of claim 1, wherein, The method comprises the following steps: According to the moving contact displacement and the static contact deformation in the contact system state information, the normal distance distribution between the moving contact surface and the static contact surface is calculated to obtain the gap field of the contact interface. The region with a zero gap value in the gap field is regarded as an actual contact area, and the actual contact area is divided into a plurality of contact micro elements. For each contact micro element, a constitutive relation between a local stress tensor and a local strain tensor of the contact micro element is established, and the constitutive relation determines the deformation response of the contact micro element under a three-dimensional stress state based on the elastic modulus and the Poisson's ratio of the contact material. According to the constitutive relation, a virtual normal displacement load is applied to each contact micro element, and the normal reaction force and the tangential reaction force generated by the contact micro element under the action of the virtual normal displacement load are calculated to obtain the force-displacement response characteristics of each contact micro element. The force-displacement response characteristics are correlated and mapped with the contact resistance in the contact system state information to establish a coupling relationship between the contact pressure distribution and the conductive contact area. Based on the coupling relationship, the measured value of the contact resistance between the contacts is taken as a boundary condition, and the normal pressure value of each contact micro element satisfying the boundary condition is reversely solved to obtain the initial contact pressure distribution.

3. The method of claim 1, wherein, The method comprises the following steps: The normal stress value of each contact micro-element in the initial contact pressure distribution is converted into a normal stress value to construct a stress field distribution of the contact surface; the normal stress value of each contact micro-element in the stress field distribution is subjected to a spatial derivation operation to obtain a stress spatial gradient at the position of each contact micro-element; When the stress spatial gradient of the contact micro-element exceeds a gradient statistical threshold value, the contact micro-element is marked as a stress concentration micro-element; spatially adjacent stress concentration micro-elements are clustered to form a stress concentration micro-element cluster, and each stress concentration micro-element cluster corresponds to a stress concentration region; For each stress concentration region, the coordinate average value of the stress concentration micro-elements in the stress concentration region is calculated to obtain a geometric center coordinate, a coordinate sequence of the stress concentration micro-elements located at the edge position is identified to form a boundary contour, and the geometric center coordinate and the boundary contour are combined to obtain a spatial position feature corresponding to the stress concentration region; For each stress concentration region, the rate of change of the stress value with respect to the spatial distance is extracted along multiple radial paths extending to the boundary contour from the geometric center coordinate of the stress concentration region, a stress gradient vector field of the stress concentration region is synthesized, and the gradient amplitude corresponding to the maximum principal direction is extracted as a stress gradient feature corresponding to the stress concentration region.

4. The method of claim 1, wherein, According to the spatial position feature and the stress gradient feature, the initial contact pressure distribution is redistributed by adjusting a driving force application path of the moving contact to obtain a target contact pressure distribution, including: According to the spatial position feature, the geometric center coordinates of each stress concentration region in the contact surface coordinate system are extracted; Based on the stress gradient feature, a stress concentration region with the maximum stress gradient amplitude is identified as a dominant stress concentration region, and the maximum principal direction of the stress gradient vector field of the dominant stress concentration region is extracted as a stress concentration principal direction; The reverse direction of the stress concentration principal direction is determined as a stress release direction, the geometric center coordinate is taken as a target point, and the driving force application path is obtained by tracing back to the driving force action position of the moving contact in the reverse direction along the stress release direction; According to the driving force application path, the contact posture between the moving contact and the static contact is adjusted, and the moving contact moves towards the static contact along the driving force application path under the action of the driving force; Based on the adjusted contact posture, each contact micro-element is re-divided, the normal pressure value of the contact micro-element under the adjusted contact posture is calculated according to the constitutive relation, and a redistributed contact pressure distribution is obtained; The redistributed contact pressure distribution is taken as the target contact pressure distribution.

5. The method of claim 1, wherein, Based on the target contact pressure distribution and the fatigue life constraint condition of the contact, a segmented motion control instruction of the moving contact is generated, including: According to the target contact pressure distribution, the normal pressure value of each contact micro-element in the target contact pressure distribution is extracted; based on the normal pressure value and the area of the contact micro-element, the contact stress value of each contact micro-element is calculated; The contact stress value of each contact micro-element is compared with the fatigue strength limit value of the contact, and the contact micro-element with the contact stress value exceeding the fatigue strength limit value is identified as a fatigue risk micro-element, and the distribution density of the fatigue risk micro-element on the contact surface is counted. According to a stress-life curve of the contact material, a mapping relationship between a contact stress value and a fatigue cycle number is established; Based on the mapping relationship and the contact stress value of each contact microelement, a permissible fatigue cycle number of each contact microelement under a current contact stress level is calculated; and a minimum value of the permissible fatigue cycle numbers of all the contact microelements is determined as a fatigue life constraint value of the contact system; According to the distribution density of the fatigue risk microelement and the fatigue life constraint value, a complete motion stroke of the moving contact is divided into multiple stages, and a corresponding segmented motion control instruction is set for each stage.

6. The method of claim 5, wherein, The complete motion stroke of the moving contact is divided into multiple stages, and a corresponding segmented motion control instruction is set for each stage, including: The complete motion stroke includes a pre-contact segment, a contact establishment segment and a steady-state contact segment, wherein the pre-contact segment corresponds to a stage in which the moving contact approaches the stationary contact from a static position but does not contact, the contact establishment segment corresponds to a stage in which the moving contact initially contacts the stationary contact to establish a target contact pressure distribution, and the steady-state contact segment corresponds to a stage in which the target contact pressure distribution is maintained stable; For the pre-contact segment, a constant speed motion instruction is generated to control the moving contact to move towards the stationary contact at a preset approach speed; For the contact establishment segment, a speed attenuation curve of the contact establishment segment is calculated according to the distribution density of the fatigue risk microelement, the speed attenuation curve describes a change process in which the speed of the moving contact gradually decreases from the preset approach speed to zero, and a variable speed motion instruction is generated to control the moving contact to move according to the speed attenuation curve; For the steady-state contact segment, an upper limit of a duration of the steady-state contact segment is calculated according to the fatigue life constraint value, and a holding motion instruction is generated to control the moving contact to maintain the contact state with the stationary contact within the upper limit of the duration; The constant speed motion instruction, the variable speed motion instruction and the holding motion instruction are combined in time sequence to obtain the segmented motion control instruction of the moving contact.

7. A contact pressure distribution system for moving and stationary contacts of a micro relay for implementing the method according to any one of claims 1 to 6, characterized in that It includes: A first unit is configured to obtain contact system state information of a micro relay, divide the micro relay into multiple contact microelements according to a displacement amount of a moving contact and a deformation amount of a stationary contact in the contact system state information, establish force-displacement response characteristics of each contact microelement, and associate and map the force-displacement response characteristics with a contact resistance in the contact system state information to obtain an initial contact pressure distribution; A second unit is configured to identify a stress concentration area of a contact surface according to the initial contact pressure distribution, and extract spatial position characteristics and stress gradient characteristics corresponding to the stress concentration area; A third unit is configured to redistribute the initial contact pressure distribution by adjusting a driving force application path of the moving contact according to the spatial position characteristics and the stress gradient characteristics to obtain a target contact pressure distribution; A fourth unit is configured to generate a segmented motion control instruction of the moving contact based on the target contact pressure distribution and a fatigue life constraint condition of a contact material, wherein the segmented motion control instruction specifies a speed variation law and a pressure loading time sequence of the moving contact in different stages of a contact stroke. A fifth unit is configured to send the segmented motion control instruction to the driving mechanism, so that the driving mechanism drives the moving contact to complete the contact process with the static contact according to the segmented motion control instruction.

8. An electronic device, comprising: The computer program instructions are executed by the processor to implement the method in any one of claims 1 to 6. The computer program instructions are executed by the processor to implement the method in any one of claims 1 to 6. The computer program instructions are executed by the processor to implement the method in any one of claims 1 to 6. ​ 9. A computer-readable storage medium having stored thereon computer program instructions, wherein, ​

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