A robot motor housing polishing control method and system

Abstract

The application relates to the technical field of robot motor shell polishing, in particular to a robot motor shell polishing control method and system, which specifically comprises the following steps: constructing contact force oscillation degrees of each collection time period by the fluctuation trend change of the contact force extreme value point and the difference between the contact force at each moment and the expected value; constructing an extreme value position sequence by the sampling moment corresponding to the contact force extreme value point, constructing comprehensive oscillation degrees of each collection time period based on the difference between adjacent extreme value points, the corresponding time difference and the trend change of the elements in the extreme value position sequence, and combining the contact force oscillation degrees; and adjusting the proportional term of a PD controller according to the comprehensive oscillation degrees to perform robot motor shell polishing control. The robot motor shell polishing control method and system can avoid the over-polishing or under-polishing problems caused by traditional fixed parameters, significantly reduce the inconsistency defects of the shell surface roughness, and improve the polishing efficiency and the surface integrity of the motor shell.

Description

Technical Field

[0001] This application relates to the field of robot motor housing polishing technology, specifically to a robot motor housing grinding control method and system. Background Technology

[0002] As a core component of robot motion, the robot motor provides sufficient power for the robot's movement. During robot operation, the motor housing protects the motor from external damage such as dust, liquids, and mechanical impacts. Therefore, in the production of robot motor housings, fine polishing can effectively remove burrs and scratches from the housing surface, making the surface smooth, reducing air resistance and friction, and thus improving the motor's operating efficiency.

[0003] For grinding the casing of equipment, the first step is to plan the grinding trajectory and then grind the casing along the planned path. During the grinding process, the contact force needs to be controlled. Traditionally, this is done using a fixed-parameter PD (Power Distribution) controller. However, because the surface smoothness of the robot motor casing is crucial, traditional fixed-parameter PD control is prone to overshoot or slow response, making it difficult to maintain a stable contact force. This results in inconsistent smoothness across different areas of the robot motor casing, leading to poor grinding results. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this application is to provide a method and system for controlling the grinding of robot motor housings. The specific technical solution adopted is as follows:

[0005] In a first aspect, embodiments of this application provide a method for controlling the grinding of a robot motor housing, the method comprising the following steps:

[0006] During the grinding process of the robot motor housing, data on the contact force between the grinding tool and the workpiece are collected at various times.

[0007] Based on the fluctuation trend of extreme points in the contact force data during each collection period, and the difference between the contact force at each moment and the preset expected contact force, the contact force oscillation degree for each collection period is constructed.

[0008] The temporal contact force data within each acquisition period is smoothed. Based on the differences between adjacent extreme points, the differences in sampling time of adjacent extreme points, and the trend changes in the sampling time of extreme points in the smoothed temporal contact force data, combined with the contact force oscillation, a comprehensive oscillation of each acquisition period is constructed.

[0009] The proportional term of the PD controller is adjusted based on the comprehensive oscillation degree to control the grinding of the robot motor housing.

[0010] In one embodiment, the process of obtaining the contact force oscillation degree is as follows:

[0011] The sequence of all maxima in the contact force data within each collection period is denoted as the maxima sequence, and the sequence of all minima is denoted as the minima sequence. The number of positive elements in the first-order difference sequence of the maxima sequence and the number of negative elements in the first-order difference sequence of the minima sequence are obtained respectively.

[0012] Calculate the mean of the difference between the contact force at all times and the desired contact force;

[0013] The contact force oscillation degree for each collection time period is determined based on the number of positive elements, the number of negative elements, and the mean. The contact force oscillation degree is positively correlated with the number of positive elements, the number of negative elements, and the mean.

[0014] In one embodiment, the process of obtaining the overall oscillation degree is as follows:

[0015] The fitting curves of the time-series contact force data within each collection time period are obtained by the SG filtering algorithm, and the sequence of sampling times corresponding to the extreme points on the fitting curve is recorded as the extreme value sequence.

[0016] Based on the differences between adjacent elements in the extreme value sequence and the differences between adjacent elements in the fitted curve, combined with the contact force oscillation, the overall contact force oscillation for each collection time period is determined.

[0017] Based on the trend measurement value of the first-order difference sequence of the extreme value sequence and the contact force oscillation degree, the comprehensive oscillation degree of each collection time period is determined. The comprehensive oscillation degree is positively correlated with the contact force oscillation degree and negatively correlated with the trend measurement value.

[0018] In one embodiment, the process of obtaining the overall oscillation degree of the contact force is as follows:

[0019] Obtain the maximum difference between all adjacent elements in the extreme value sequence;

[0020] Obtain the mean of the differences between all adjacent extreme points in the fitted curve, and denote it as the first mean.

[0021] The overall oscillation of the contact force in each collection period is determined based on the maximum value, the first mean value, and the contact force oscillation degree. The overall oscillation degree of the contact force is directly proportional to the first mean value and the contact force oscillation degree, and inversely proportional to the maximum value.

[0022] In one embodiment, the overall oscillation degree of the contact force is calculated as follows: the product of the absolute value of the difference between the last element and the first element in the extreme value sequence, the first mean, and the oscillation degree of the contact force is used as the numerator, and the product of the preset expected contact force and the maximum value is used as the denominator.

[0023] In one embodiment, the trend measure is the slope of the fitted line obtained by fitting the first-order difference sequence using a fitting algorithm.

[0024] In one embodiment, the expression for the overall oscillation is:

[0025]

[0026] In the formula, This indicates the overall vibration level during the polishing of the robot motor housing; This indicates the overall oscillation degree of the contact force during the polishing of the robot motor housing; This represents a measure of the changing trend of the first-order difference sequence of the extreme value position sequence; represents the normalization function; b represents the preset adjustment factor.

[0027] In one embodiment, the step of controlling the grinding of the robot motor housing specifically involves:

[0028] The dividing point between two adjacent data acquisition time periods is used as the adjustment time point for the proportional term of the PD controller;

[0029] Based on the difference in overall oscillation between the current acquisition time period and the previous acquisition time period, and combined with the proportional term of the current acquisition time period, the proportional term of the next acquisition time period is obtained; the difference between the contact force at the adjustment time point and the expected contact force is calculated; the difference and the proportional term of the next acquisition time period are used as inputs to the dual PD controller, and the grinding trajectory of the next acquisition time period is adjusted by the output correction displacement.

[0030] In one embodiment, the ratio of the next acquisition time period is the ratio of the combined oscillation of the current acquisition time period to that of the previous acquisition time period, multiplied by the ratio of the current acquisition time period.

[0031] Secondly, embodiments of this application also provide a robot motor housing grinding control system, including a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of any of the methods described above.

[0032] The embodiments of this application have at least the following beneficial effects:

[0033] This application constructs the contact force oscillation degree for each acquisition time period based on the fluctuation trend of extreme points in the contact force sequence and the difference between the contact force at each moment and the preset expected contact force. This can accurately identify the convergence of the actual contact force relative to the expected force in the time domain, and can quickly determine the convergence degree and oscillation intensity of the contact force in each time period. By constructing an extreme value sequence at the sampling time corresponding to the extreme point of the contact force, and based on the differences between adjacent extreme points and the corresponding time differences, as well as the trend changes of elements in the extreme value sequence, combined with the contact force oscillation degree, a comprehensive oscillation degree for each acquisition time period is constructed. This can characterize the system overshoot or response lag caused by fixed PD control parameters. The proportional term of the PD controller is adjusted according to the comprehensive oscillation degree to control the grinding of the robot motor shell. This can accelerate the convergence speed, shorten the steady-state adjustment time, avoid the over-grinding or under-grinding problems caused by traditional fixed parameters, and significantly reduce the defects of inconsistent surface roughness of the shell, thereby improving grinding efficiency and the surface integrity of the motor shell. Attached Figure Description

[0034] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A flowchart illustrating the steps of a robot motor housing polishing control method according to one embodiment of this application;

[0036] Figure 2 This is a schematic diagram illustrating the process of obtaining the overall oscillation. Detailed Implementation

[0037] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a robot motor housing grinding control method and system proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0039] The following description, in conjunction with the accompanying drawings, details the specific scheme of the robot motor housing grinding control method and system provided in this application.

[0040] Please see Figure 1 The diagram illustrates a flowchart of a robot motor housing grinding control method according to an embodiment of this application. The method includes the following steps:

[0041] Step S1: During the grinding process of the robot motor housing, collect the contact force data between the grinding tool and the workpiece at each moment.

[0042] First, a 3D model of a standard robot motor housing is obtained. In this embodiment, the robot motor housing drawing is used as input to CAD software to output a 3D model of the standard robot motor housing. In other embodiments of this application, a standard robot motor housing can be manually polished, and a 3D laser scanner can be used to perform point cloud scanning on the standard robot motor housing. The data volume is reduced by downsampling, and the downsampled point cloud data is used as input to the Poisson reconstruction algorithm to output a 3D model of the standard robot motor housing. Implementers may also use other 3D model construction methods to obtain a 3D model of the standard robot motor housing; this application does not impose specific limitations. Downsampling and the Poisson reconstruction algorithm are well-known technologies, and the specific process will not be described in detail.

[0043] Next, point cloud data of the robot motor shell to be polished is obtained. The robot motor shell to be polished is placed on the polishing platform, and point cloud data of the robot motor shell to be polished is collected using a 3D laser scanner. Background point cloud is eliminated by pass-through filtering, and the filtered point cloud data is downsampled to reduce the data volume, thus obtaining the point cloud data of the robot motor shell to be polished. Among them, pass-through filtering is a well-known technology, and the specific process will not be described in detail.

[0044] Furthermore, a coarse-planned trajectory for the grinding process is generated. The downsampled point cloud data of the robot motor housing to be ground and the 3D model of a standard robot motor housing are used as inputs to the ICP algorithm (Iterative Closest Point Algorithm) for spatial matching. The matched spatial data is then used as input to the isoparametric method, and the algorithm's output is the coarse-planned trajectory for the grinding of the robot motor housing. Both pass-through filtering and the isoparametric method are well-known techniques, and their specific processes will not be elaborated upon.

[0045] Furthermore, the coarse-planned trajectory of the grinding path is used as the input to the grinding equipment. The grinding equipment controls the running trajectory of the grinding robot arm through the coarse-planned trajectory, thereby grinding the motor shell of the robot to be ground. During the grinding process, a six-dimensional force sensor is installed between the flange at the end of the grinding equipment and the grinding tool. The contact force between the grinding tool and the motor shell of the robot to be ground is determined at each moment by collecting the six-dimensional force data at each moment from the sensor. The process of acquiring the contact force is a well-known technology and will not be described in detail here. A collection time period is set. In this embodiment, the duration of the collection time period is set to 5 seconds, and the data collection frequency is 100Hz. The sequence formed by arranging all the contact force data in each collection time period according to the corresponding sampling time sequence is recorded as the contact force sequence of each collection time period. The missing data in this sequence is filled in by linear interpolation. If there is no missing data, no interpolation is performed. The linear interpolation method is a well-known technology and will not be described in detail here. The implementer can set the data collection frequency and collection time period according to the actual situation. This application does not impose specific restrictions.

[0046] Step S2: Based on the fluctuation trend of extreme points in the contact force data during each collection period, and the difference between the contact force at each moment and the preset expected contact force, construct the contact force oscillation degree for each collection period.

[0047] Because the robot motor housing may develop defects such as burrs, flash, and scratches after molding, it needs to be polished. During polishing, a stable contact force is required to ensure uniform smoothness across all areas of the housing. In this implementation, the desired contact force is 20N, where N represents Newton, a unit of mechanical strength. During polishing, the smaller the difference between the actual and desired contact force, the better the oscillation. Furthermore, a decreasing difference over time indicates continuous and effective convergence of the oscillation. Taking any data acquisition period as the current period, the following processing is performed:

[0048] Therefore, the contact force sequence of the current time period is used as the input to the extreme point detection algorithm, and the output is all the maxima and minima in the contact force sequence. All maxima and minima are then arranged in ascending order according to the sampling time to obtain the maximum and minimum value sequences of the contact force sequence. These maximum and minimum value sequences are then used as the input to the first-order difference algorithm, and the output is the first-order difference sequence of the maximum and minimum value sequences, respectively. The number of positive elements in the first-order difference sequence of the maximum value sequence and the number of negative elements in the first-order difference sequence of the minimum value sequence are counted, and the contact force oscillation state is characterized by the number of positive and negative elements. Both the extreme point detection algorithm and the first-order difference algorithm are well-known techniques, and their specific processes will not be elaborated further.

[0049] It should be noted that this application only provides one extreme point detection method for extreme points in the contact force sequence. There are many existing extreme point detection methods, and implementers may also use other extreme point detection algorithms to obtain extreme points in the contact force sequence. This application does not impose any specific restrictions.

[0050] Based on the differences between the values ​​of each element in the contact force sequence and the desired contact force, as well as the number of positive and negative elements, the contact force oscillation degree of the robot motor housing during the polishing process is calculated. Preferably, in this embodiment, the expression for the contact force oscillation degree is:

[0051]

[0052] In the formula, This indicates the oscillation degree of the contact force during the grinding of the robot motor housing within the current time period; This indicates the number of elements in the contact force sequence for the current time period; This represents the i-th element in the contact force sequence for the current time period; This represents the preset desired contact force, which is 20N in this embodiment; This represents the sum of the number of positive and negative elements in the contact force sequence.

[0053] The difference between the actual contact force and the desired contact force can characterize the degree of deviation of the actual contact force. The average deviation between the contact force and the desired state can be characterized by the mean of this deviation at different times. The number of times the maximum value changes towards the larger direction, combined with the number of times the minimum value changes towards the smaller direction, can characterize the oscillation state. Therefore, these two characteristics are combined to characterize the degree of deviation caused by oscillation when the actual contact force converges to the desired contact force during the polishing process of the robot motor housing.

[0054] The better the convergence effect between the actual contact force and the expected contact force at the grinding end, the smaller the difference between the actual contact force and the expected contact force. At the same time, the smaller the number of positive and negative elements, the smaller the contact force oscillation during the grinding process of the robot motor housing. The more stable the contact force is during the grinding process of the robot motor housing, the better the smoothness of the grinding effect.

[0055] In other embodiments of this application, the expression for the contact force oscillation degree can also be: In the formula, S represents the number of extreme points in the contact force sequence during the current time period.

[0056] Step S3: Smooth the time-series contact force data within each acquisition time period. Based on the differences between adjacent extreme points, the differences in sampling times of adjacent extreme points, and the trend changes in the sampling times of extreme points in the smoothed time-series contact force data, and in conjunction with the contact force oscillation, construct the comprehensive oscillation of each acquisition time period.

[0057] When adjusting the contact force at the grinding end via PD control, the smaller the amplitude of the contact force change after reaching the desired contact force, the better the control effect on the actual contact force. Simultaneously, the fewer the number of changes in the overall trend direction of the actual contact force, the stronger the PD parameters' ability to suppress system inertia. After grinding, the grinding device and the workpiece surface maintain uniform pressure, resulting in consistent surface roughness and high dimensional accuracy of the robot motor housing. Here, system inertia refers to the contact force adjustment process. For example, if the contact force needs to be adjusted from 15N to the desired 20N, the adjustment will not be a direct jump from 15N to 20N, but rather a gradual approach. At any given adjustment, the initial contact force may be less than 20N, while the adjusted contact force may exceed 20N.

[0058] Therefore, the contact force sequence is used as the input to the SG filtering algorithm, and the output is the contact force curve of the contact force sequence, which is used to eliminate local fluctuations in the contact force. The SG filtering algorithm is a well-known technique, and its specific process will not be elaborated further.

[0059] It should be noted that this application only provides one smoothing method for the smoothing of the contact force sequence. There are many existing smoothing methods, and implementers may also use other smoothing algorithms to smooth the contact force sequence. This application does not impose any specific restrictions.

[0060] All extreme points in the contact force curve are obtained by calculating the first derivative, and the sampling time corresponding to each extreme point is also obtained. The sampling times of all extreme points are arranged in chronological order, and the resulting sequence is denoted as the extreme value sequence, which is used to characterize the time point when the trend of contact force change. The method of determining extreme points by the first derivative is well known, and the specific process will not be elaborated here.

[0061] Therefore, the overall oscillation degree of the contact force on the robot motor housing during the polishing process is calculated. Preferably, in this embodiment, the expression for the overall oscillation degree of the contact force is:

[0062]

[0063] In the formula, This indicates the overall oscillation of the contact force during the grinding of the robot motor housing within the current time period; This indicates the oscillation degree of the contact force during the grinding of the robot motor housing within the current time period; The first mean is the average difference between all adjacent extreme points in the contact force curve corresponding to the current time period. This represents the maximum value among all the differences between adjacent elements in the extreme value sequence corresponding to the current time period; wherein the difference between adjacent extreme points is the absolute value of the difference between adjacent extreme points, and the difference between adjacent elements is the absolute value of the difference between adjacent elements in the extreme value sequence; This represents the preset desired contact force, which is 20N in this embodiment; It represents the absolute value of the difference between the last element and the first element in the extreme value sequence corresponding to the current time period.

[0064] When the actual contact force fluctuates around the desired contact force, the difference between adjacent extreme points in the contact force curve can characterize the amplitude of the actual contact force fluctuation. The smaller the difference between adjacent extreme points, the smaller the amplitude, the more stable the contact force, and the smaller the overall oscillation of the contact force. The elements in the extreme value sequence can characterize the steady state of the contact force. To characterize the actual contact force oscillation state, The smaller the value, the faster the contact force fluctuates around the expected value, and the more pronounced the oscillation. The larger the value, the less frequently the contact force fluctuates around the expected value, the more stable the contact force is, and the smaller the overall oscillation of the contact force. The smaller the oscillation of the contact force, the more stable the contact force is during the polishing process of the robot motor shell, and the smaller the overall oscillation of the contact force during the polishing of the robot motor shell.

[0065] Preferably, in other embodiments of this application, the expression for the overall oscillation degree of the contact force may also be: In the formula, This represents the division-by-zero adjustment factor, which is used to prevent the denominator from being 0. In this embodiment, it will be... The value is set to 0.1.

[0066] Furthermore, regarding the time of change in the trend direction of the robot's contact force, the longer the time that the same trend is maintained, the more stable the robot's contact force is, and the smaller the systematic oscillation of the contact force. Therefore, the extreme value sequence is used as the input to the first-order difference algorithm, and the output is the first-order difference sequence of the extreme value sequence, used to characterize the length of the contact force in the same trend. Further, the trend metric of the first-order difference sequence of the extreme value sequence is calculated, denoted as the trend quantity. The calculation of the trend quantity includes, but is not limited to, slope, Mann-Kendall trend test, left-right mean ratio, etc. In this embodiment, the slope is used to characterize the trend quantity of the first-order difference sequence of the extreme value sequence. The calculation method is as follows: the first-order difference sequence of the extreme value sequence is used as the input to the linear least squares method, the slope of the output fitted line is obtained, and this slope is used as the trend quantity of the first-order difference sequence of the extreme value sequence. The calculation of the linear least squares method is a well-known technique, and the specific process will not be elaborated further.

[0067] It should be noted that this application provides only one linear fitting method for linear fitting of first-order difference sequences. There are many existing linear fitting methods, and implementers may also use other linear fitting algorithms to perform linear fitting of first-order difference sequences. This application does not impose any specific restrictions.

[0068] Therefore, the overall oscillation degree of the robot motor housing during the polishing process is calculated. Preferably, in this embodiment, the expression for the overall oscillation degree is:

[0069]

[0070] In the formula, This indicates the overall oscillation degree of the robot motor housing polishing during the current time period; This indicates the overall oscillation of the contact force during the grinding of the robot motor housing within the current time period; This represents the trend quantity of the first-order difference sequence of the extreme value sequence corresponding to the current time period; denoted by , b represents the normalization function; b represents the adjustment factor, which is a real number greater than 1, and in this embodiment, it is set to 1.1. Since k may be negative, the adjustment factor is added after normalizing k to avoid a denominator of 0. In this embodiment, the normalization method for k is to normalize the trend of the extreme value sequence across all data collection periods using the maximum-minimum normalization method.

[0071] It should be noted that this application provides only one normalization method for the normalization of the trend quantity. There are many existing normalization methods, and implementers may also use other normalization algorithms to normalize the trend quantity. This application does not impose any specific restrictions.

[0072] The overall oscillation of the contact force during the polishing process of the robot motor housing can characterize the convergence characteristics of the actual contact force to the desired contact force, while the trend of the extreme value sequence can characterize the change in the convergence time of the actual contact force. When polishing the robot motor housing, better control of the contact force results in a smaller difference between the actual and desired contact force, a longer trend change time, and consequently, a smaller overall oscillation of the contact force and a larger trend of the extreme value sequence. This leads to a smaller overall oscillation of the robot motor housing during polishing and a better polishing effect.

[0073] Step S4: Adjust the proportional term of the PD controller based on the comprehensive oscillation degree to control the grinding of the robot motor housing.

[0074] This application employs dual PD controllers for feedback control of the contact force. The first PD controller calculates the error compensation term for the contact force to correct for contact force deviations caused by disturbances during grinding, thereby improving response speed and tracking accuracy. The second PD controller is an impedance controller. A larger proportional term in the PD controller results in stronger and faster adjustment capability, but also a higher risk of overshoot; a smaller proportional term leads to slower adjustment. The impedance controller is a well-known technology, and its specific implementation will not be detailed here.

[0075] Therefore, the proportional term of the PD controller is adjusted based on the overall oscillation. The time point between two adjacent acquisition time periods is used as the adjustment time point for the proportional term of the PD controller. Any adjustment time point of the proportional term is used as the current adjustment time point. The preceding acquisition time period adjacent to the current adjustment time point is the current acquisition time period, and the following acquisition time period is the next acquisition time period. The ratio between the overall oscillation of the current acquisition time period and the overall oscillation of the previous acquisition time period is calculated, and then multiplied by the proportional term of the PD controller for the current acquisition time period to obtain the proportional term of the PD controller for the next acquisition time period.

[0076] Furthermore, the error between the contact force at the current adjustment time point and the desired contact force is calculated, where the error is the difference between the contact force and the desired contact force. This error, along with the calculated proportional term for the next data acquisition time period, is used as the input to the first PD controller, and the output is the error compensation term for the contact force in the next data acquisition time period.

[0077] Next, the error compensation term, the error itself, and the proportional term for the next acquisition time period are used as inputs to the impedance controller, and the output is the corrected displacement of the grinding end in the next acquisition time period. This corrected displacement is superimposed on the grinding trajectory in the current acquisition time period to obtain a new grinding trajectory. In the next acquisition time period, the grinding equipment controls the grinding end to move according to this new grinding trajectory to grind the robot motor housing. The grinding trajectory in the first acquisition time period is the coarsely planned trajectory.

[0078] A schematic diagram of the process for obtaining the overall oscillation is shown below. Figure 2 As shown.

[0079] Based on the same inventive concept as the above method, this application embodiment also provides a robot motor housing grinding control system, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above-described robot motor housing grinding control methods.

[0080] In summary, this application provides a robot motor housing grinding control method. Based on the fluctuation trend of extreme points in the contact force sequence and the difference between the contact force at each moment and the preset expected contact force, the contact force oscillation degree of each acquisition time period is constructed. This can accurately identify the convergence of the actual contact force relative to the expected force in the time domain, and can quickly determine the convergence degree and oscillation intensity of the contact force in each time period. By constructing an extreme value sequence at the sampling time corresponding to the extreme point of the contact force, and based on the difference between adjacent extreme points and the corresponding time difference, as well as the trend change of elements in the extreme value sequence, combined with the contact force oscillation degree, a comprehensive oscillation degree of each acquisition time period is constructed. This can characterize the system overshoot or response lag caused by fixed PD control parameters. The proportional term of the PD controller is adjusted according to the comprehensive oscillation degree to control the grinding of the robot motor housing. This can accelerate the convergence speed, shorten the steady-state adjustment time, avoid the over-grinding or under-grinding problems caused by traditional fixed parameters, and significantly reduce the defects of inconsistent surface roughness of the housing, thereby improving grinding efficiency and the surface integrity of the motor housing.

[0081] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this application. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0082] The various embodiments in this application are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0083] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. A robot motor housing polishing control method, characterized by, The method includes the following steps: During the grinding process of the robot motor housing, data on the contact force between the grinding tool and the workpiece are collected at various times. Based on the extreme point fluctuation trend of contact force data in each collection period, and the difference between the contact force at each moment and the preset expected contact force, the contact force oscillation degree of each collection period is constructed. The temporal contact force data within each acquisition period is smoothed. Based on the differences between adjacent extreme points, the differences in sampling time of adjacent extreme points, and the trend changes in the sampling time of extreme points in the smoothed temporal contact force data, combined with the contact force oscillation, a comprehensive oscillation of each acquisition period is constructed. The proportional term of the PD controller is adjusted based on the comprehensive oscillation degree to control the grinding of the robot motor housing; The process for obtaining the contact force oscillation degree is as follows: The sequence of all maximum values ​​in the contact force data within each collection time period is denoted as the maximum value sequence, and the sequence of all minimum values ​​is denoted as the minimum value sequence. The number of positive elements in the first-order difference sequence of the maximum value sequence and the number of negative elements in the first-order difference sequence of the minimum value sequence are obtained respectively. Calculate the mean of the difference between the contact force at all times and the desired contact force; The contact force oscillation degree for each collection time period is determined based on the number of positive elements, the number of negative elements, and the mean value. The contact force oscillation degree is positively correlated with the number of positive elements, the number of negative elements, and the mean value, respectively. The process for obtaining the overall oscillation degree is as follows: The fitting curves of the time-series contact force data within each collection time period are obtained by the SG filtering algorithm, and the sequence of sampling times corresponding to the extreme points on the fitting curve is recorded as the extreme value sequence. Based on the differences between adjacent elements in the extreme value sequence and the differences between adjacent elements in the fitted curve, combined with the contact force oscillation, the overall contact force oscillation for each collection time period is determined. Based on the trend measurement value of the first-order difference sequence of the extreme value sequence and the contact force oscillation degree, the comprehensive oscillation degree of each collection time period is determined. The comprehensive oscillation degree is positively correlated with the contact force oscillation degree and negatively correlated with the trend measurement value.

2. The method for controlling the grinding of a robot motor housing as described in claim 1, characterized in that, The process for obtaining the overall oscillation degree of the contact force is as follows: Obtain the maximum difference between all adjacent elements in the extreme value sequence; Obtain the mean of the differences between all adjacent extreme points in the fitted curve, and denote it as the first mean. The overall oscillation of the contact force in each collection period is determined based on the maximum value, the first mean value, and the contact force oscillation degree. The overall oscillation degree of the contact force is directly proportional to the first mean value and the contact force oscillation degree, and inversely proportional to the maximum value.

3. A method of robot motor housing polishing control as claimed in claim 2, wherein, The overall oscillation degree of the contact force is calculated as follows: the product of the absolute value of the difference between the last element and the first element in the extreme value sequence, the first mean, and the oscillation degree of the contact force is used as the numerator, and the product of the preset expected contact force and the maximum value is used as the denominator.

4. The method of claim 1, wherein, The measure of the trend of change is the slope of the fitted line obtained by the fitting algorithm for the first-order difference sequence.

5. The method of claim 1, wherein, The expression for the overall oscillation is: In the formula, This indicates the overall vibration level during the polishing of the robot motor housing; This indicates the overall oscillation degree of the contact force during the polishing of the robot motor housing; This represents a measure of the changing trend of the first-order difference sequence of the extreme value position sequence; represents the normalization function; b represents the preset adjustment factor.

6. A method of robot motor housing polishing control as claimed in claim 1, wherein, The specific steps for controlling the polishing of the robot motor housing are as follows: The dividing point between two adjacent data acquisition time periods is used as the adjustment time point for the proportional term of the PD controller; Based on the difference in overall oscillation between the current data collection period and the previous data collection period, and combined with the proportional term of the current data collection period, the proportional term of the next data collection period is obtained. Calculate the difference between the contact force at the adjustment time point and the desired contact force; The difference and the ratio of the next acquisition time period are used as inputs to the dual PD controller, and the grinding trajectory of the next acquisition time period is adjusted by the output correction displacement.

7. A method of robot motor housing polishing control as claimed in claim 6, wherein, The proportional term for the next data collection period is: the ratio of the combined oscillation of the current data collection period to that of the previous data collection period, multiplied by the proportional term for the current data collection period.

8. A robotic motor housing polishing control system comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1-7.

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