Jointed coordinate measuring machine operation evaluation method and system based on stage division

Abstract

The application discloses a kind of joint coordinate measuring machine operation evaluation methods based on stage division;The method is as follows: one, data acquisition.Two, operation stage division.Three, the measurement operation of operation is evaluated.Four, according to the score obtained in step three, the operator is evaluated.The application collects acceleration signal in measurement operation, each time sampling point operation is divided according to time sequence, and each time sampling point operation is divided into measurement arm swing stage and measurement contact stage, and measurement operation characteristic signal is recorded in database in stages, to provide basis for the evaluation of measurement operation.In addition, the application is based on acceleration, measurement force signal and operation stage division, and a plurality of evaluation indexes are constructed in each measurement operation stage, the process evaluation of the operator measurement operation is realized, and the warning prompt of the three types of improper operation, such as excessive swing acceleration, unstable measurement contact and excessive measurement force, is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coordinate measurement, in particular to a joint coordinate measuring machine operator measurement operation evaluation system and method based on operation stage division. BACKGROUND

[0002] The joint coordinate measuring machine is composed of a measuring arm and a rotating joint in series, and is a non-orthogonal coordinate measuring machine with small volume, large range, flexible operation and convenient on-site measurement. Precision and efficiency are two very important indicators of measuring equipment. Current scholars mainly study from the hardware aspects of the equipment itself to improve the precision and efficiency of the measuring machine, such as structure parameter calibration, angle encoder error compensation, and high-efficiency calibration method design, but the current research ignores the human factor of the operator. In fact, whether in the calibration stage or in the contact measurement stage, the use of the joint coordinate measuring machine cannot be separated from the manual operation of the operator.

[0003] The contact measurement of the joint coordinate measuring machine requires the operator to hold and move the measuring arm and the measuring head, so that the ruby ball on the measuring needle of the measuring head is in contact with the measured surface, and then the point sampling key is pressed to perform point sampling measurement. In the process of manual measurement, factors such as measurement force, swing acceleration and measurement stability generated by humans will affect the quality of the obtained measurement points, and some improper measurement operations may even damage the measuring machine. In addition, the proficiency of the operator's measurement operation is directly related to the efficiency of the measurement work and affects the enterprise's revenue. Therefore, it is necessary to evaluate the operator's measurement operation level.

[0004] The current operator's measurement operation level is mainly evaluated by expert observation and result evaluation, which has certain subjectivity and ignores the measurement process. Therefore, it is necessary to build an operator measurement operation evaluation system to objectively evaluate the operator's operation level. In addition, by evaluating the operator's measurement operation, suggestions can be provided to help the operator improve the operation level quickly. SUMMARY

[0005] The purpose of the present application is to provide a joint coordinate measuring machine operator measurement operation evaluation system and method based on operation stage division.

[0006] A joint coordinate measuring machine operation evaluation method based on stage division, comprising the following steps:

[0007] Step one, the operator uses the joint coordinate measuring machine to collect data on a plurality of measured positions on a feature standard part. An acceleration sensor and a force sensor are installed on the measuring head of the joint coordinate measuring machine. The acceleration sensor detects the acceleration change of the measuring head during operation; the force sensor detects the change of the measurement force received by the measuring needle of the measuring head during operation.

[0008] Step two, operation phase division

[0009] According to the acceleration change of the measuring head, the whole measuring operation process is divided into multiple measuring sampling point operations, and each measuring sampling point operation is divided into a measuring arm swing stage and a measuring contact stage.

[0010] The division process is: extracting the time when the mutation peak and the moving signal appear in the acceleration change curve; taking the time when the mutation peak appears to the time when the next moving signal appears as a measuring contact stage; taking the time when the moving signal appears to the time when the next mutation peak appears as a measuring arm swing stage.

[0011] The identification method of the mutation peak is: first, identify the wave peak and wave trough of the acceleration according to the difference algorithm. The acceleration curve between the wave trough on each side of the wave peak is a first fluctuation. The first fluctuation is identified as a mutation peak, which needs to meet the following conditions: condition 1, the time between the previous wave trough and the wave peak is less than the first judgment threshold, and the slope of the line connecting the previous wave trough and the wave peak is greater than the second judgment threshold. Condition 2, the time between the next wave trough and the wave peak is less than the third judgment threshold; the absolute value of the slope of the line connecting the next wave trough and the wave peak is greater than the fourth judgment threshold. Condition 3, the standard deviation of the acceleration absolute value signal within the first judgment duration after the next wave trough is less than the fifth judgment threshold.

[0012] The identification method of the moving signal is: starting from the measuring start time, find the first stable contact interval on the acceleration change curve; the stable contact interval is an interval with an acceleration standard deviation lower than the sixth judgment threshold and a duration equal to the second judgment duration. After finding the stable contact interval, take the first time when the moving speed threshold is reached after the stable contact interval as the time when the moving signal is detected. Continue to find the stable contact interval from the time of the moving signal, and alternately reciprocate in this way to obtain all the moving signals. The moving speed threshold is 1.4-1.6 times the average acceleration of the previous stable contact interval.

[0013] Step three, evaluating the measuring operation of the operation.

[0014] 3-1. Calculate the evaluation index for each measuring arm swing stage respectively

[0015] 3-1-1. Calculate the swing smoothness score A1 as shown in the following formula:

[0016]

[0017] Wherein, J max is the maximum value of the jerk of each acceleration sampling point in the measuring arm swing stage; J0 is a preset excellent smoothness parameter.

[0018] 3-1-2. The swing phase time score A2 is calculated as shown in the following formula:

[0019]

[0020] wherein T bd is the length of the swing phase of the measuring arm, T 10 is a preset swing time excellent parameter.

[0021] 3-1-3. The swing acceleration score A3 is calculated as shown in the following formula:

[0022]

[0023] wherein a max is the maximum acceleration value of the swing phase of the measuring arm, a 10 is a preset swing acceleration threshold value.

[0024] 3-2. The evaluation indexes are calculated for each measuring contact phase respectively.

[0025] 3-2-1. The measuring contact stability score A4 is calculated as shown in the following formula:

[0026]

[0027] wherein a is the average acceleration value of the measuring contact phase, a0 is a preset measuring acceleration average excellent parameter. a 20 is a preset measuring acceleration threshold value.

[0028] 3-2-2. The measuring force fluctuation score A5 is calculated as shown in the following formula:

[0029]

[0030] wherein S max is the maximum value of the measuring force fluctuation values of each measuring force sampling point in the measuring contact phase, the measuring force fluctuation value of one measuring force sampling point is equal to the absolute value of the difference between the measured measuring force value of the measuring force sampling point and the measured measuring force value of the next measuring force sampling point divided by the measuring force sampling interval. S0 is a preset measuring force fluctuation value excellent parameter.

[0031] 3-2-3. The measuring phase time score A6 is calculated as shown in the following formula:

[0032]

[0033] wherein T jc is the length of the measuring contact phase, T 20 is a preset measuring time excellent parameter.

[0034] 3-2-4. The maximum measurement force score A7 is calculated as follows:

[0035]

[0036] wherein f max is the maximum probe measurement force of the measurement contact phase; f0 is the preset maximum measurement force threshold.

[0037] If the calculated values of scores A1-A7 are greater than 100, the values are set to 100; if the calculated values of scores A1-A7 are less than 0, the values are set to 0.

[0038] Step four, evaluating the operator according to the scores A1-A7 obtained in step three.

[0039] The average values of scores A1-A3 of all measurement arm swing phases are calculated respectively as three evaluation index total scores B1-B3 for the measurement arm swing. The average values of scores A4-A7 of all measurement contact phases are calculated respectively as three evaluation index total scores B4-B7 for the measurement contact.

[0040] The comprehensive score M is calculated as follows:

[0041] M = k1B1 + k2B2 + k3B3 + k4B4 + k5B5 + k6B6 + k7B7

[0042] wherein k1-k7 are the weight coefficients of the seven evaluation indexes; k1 + k2 + k3 + k4 + k5 + k6 + k7 = 1.

[0043] The higher the comprehensive score M is, the better the operator's operation of the articulated coordinate measuring machine is.

[0044] As preferred, the acceleration signals measured by the acceleration sensor and the measurement force signals measured by the force sensor are preprocessed; the specific process of the preprocessing is to unify the acceleration signals and the measurement force signals in time, and to perform low-pass filtering on the acceleration signals and the measurement force signals.

[0045] As preferred, the first time when the probe exceeds the starting threshold is taken as the starting time of the first measurement arm swing phase. The starting threshold is taken as 0.08-0.12 m / s 2 .

[0046] As preferred, the first judgment threshold is taken as 0.03-0.04 s; the second judgment threshold is taken as 25-30 m / s 3 ; the third judgment threshold is taken as 0.06-0.08 s; and the fourth judgment threshold is taken as 20-25 m / s 3; the first judgment duration is 0.3-0.5s; the fifth judgment threshold is 0.055-0.060m / s 2 .

[0047] Preferably, the sixth judgment threshold is 0.05-0.065m / s 2 . The second judgment duration is 0.4-0.6s.

[0048] Preferably, when no mutation peak is identified between two adjacent movement signals, the start time of a stable contact interval between the two movement signals is taken as the start time of a measurement contact phase.

[0049] Preferably, the preset acceleration excellent parameter a 10 is 25-35m / s 2 .

[0050] Preferably, the preset measurement acceleration mean excellent parameter a0 is 0.15-0.2m / s 2 . The preset measurement acceleration maximum threshold a 20 is 0.35-0.45m / s 2 .

[0051] Preferably, the maximum measurement force threshold f0 is 10-15N.

[0052] In a second aspect, the application provides a stage-divided articulated coordinate measuring machine operation evaluation system for performing the above-mentioned evaluation method; the evaluation system comprises an information acquisition module, a signal processing module, a database module and an operation evaluation module. The information acquisition module comprises an acceleration signal acquisition module and a measurement force signal acquisition module. The acceleration signal acquisition module comprises a three-axis acceleration sensor installed at the end of the probe for acquiring three-axis acceleration signals; the measurement force signal acquisition module comprises a three-axis force sensor installed at the end of the probe for acquiring three-axis measurement force signals.

[0053] The signal processing module is used for signal preprocessing and operation stage division. The signal preprocessing module unifies the acceleration signals and the measurement force signals in time, performs low-pass filtering on the acceleration signals and the measurement force signals, and then generates absolute value signals by processing the three-axis data of the acceleration signals and the measurement force signals. The operation stage division module divides the entire measurement operation process into multiple measurement sampling operations according to the acceleration signals, and then divides each measurement sampling operation into a measurement arm swing phase and a measurement contact phase, and transmits the timing results of the stage division to the database module and the operation evaluation module.

[0054] The database module includes a signal storage database and a measurement operation evaluation rule database. The signal storage database is used to store the acceleration, measurement force triaxial signal and absolute value signal; the measurement operation evaluation rule database is used to store the measurement operation evaluation rule data.

[0055] The operation evaluation module is used to evaluate the measurement operation according to the rule data.

[0056] Preferably, the information acquisition module includes a data input module and a data input module. The data input module is used to input the operator number, measurement start time and measurement end time on the computer.

[0057] In a third aspect, the present invention provides an articulated coordinate measuring machine operation alarm system, comprising the aforementioned evaluation system and an alarm module. During the evaluation process, if any of the total evaluation index scores (B1-B7) falls below the acceptable value, the alarm module issues a warning indicating that the corresponding index needs improvement. If the swing acceleration score (A3), measurement contact stability score (A4), or maximum measurement force score (A7) during the swing phase of any measuring arm reaches 0, the alarm module issues a warning indicating that the corresponding index needs improvement.

[0058] Compared with the prior art, the beneficial effects of the present invention are embodied in:

[0059] 1. The present invention implements phased recording of characteristic signals of measurement operations. By collecting acceleration signals during measurement operations and identifying sudden acceleration spikes, movement signals, variance, and mean values, the present invention can identify the operating status for both standard and continuous contact sampling methods. This allows for the temporal division of each sampling operation, as well as the division of each sampling operation into a measuring arm swing phase and a measuring contact phase. This allows for the phased recording of characteristic signals of measurement operations in a database, providing a basis for the evaluation of measurement operations and, in turn, supporting the analysis of the measurement process and the tracing of human error.

[0060] 2. The present invention realizes the process evaluation of the operator's measurement operation. Based on the acceleration, measurement force signal and operation stage division, the present invention constructs various evaluation indicators in each measurement operation stage, realizes the process evaluation of the operator's measurement operation, and realizes warning prompts for three types of improper operations: excessive swing acceleration, unstable measurement contact and excessive measurement force. This evaluation system and method can avoid the subjectivity of human evaluation, and is more detailed and has higher evaluation efficiency than the method of evaluating the operation only by the results. In addition, the present invention can also provide the operator with suggestions for improving the operation level by evaluating the operator's operation, so as to help quickly improve the operation level. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 System block diagram of the evaluation system provided by the present application.

[0062] Figure 2 Connection diagram of the information collection module and the articulated coordinate measuring machine in the present application.

[0063] Figure 3 Workflow diagram of the evaluation method provided by the present application.

[0064] Figure 4 Diagram for dividing the measuring arm swing stage and the measuring contact stage in the present application. DETAILED DESCRIPTION

[0065] The present application is further described below in combination with the accompanying drawings.

[0066] Example 1

[0067] As shown in the figure, the articulated coordinate measuring machine operator measurement operation evaluation system based on operation stage division includes an information collection module, a signal processing module, a database module and an operation evaluation module. Figure 1

[0068] As shown in the figure, the information collection module includes a data input module, an acceleration signal collection module and a measurement force signal collection module. The data input module is used to input the operator number, the measurement start time and the measurement end time on the computer 1. The acceleration signal collection module includes a three-axis acceleration sensor 2 installed at the end of the measuring head, which is used to collect three-axis acceleration signals; the measurement force signal collection module includes a three-axis force sensor 3 installed at the end of the measuring needle, which is used to collect three-axis measurement force signals. Figure 2 The signal processing module is used for signal preprocessing and operation stage division. The signal preprocessing module unifies the collected signals in time, performs low-pass filtering processing on the acceleration signals and the measurement force signals, and then generates absolute value signals by processing the three-axis data of the acceleration signals and the measurement force signals. The operation stage division module divides the entire measurement operation process into multiple measurement sampling operations according to the acceleration signals, and then divides each measurement sampling operation into a measuring arm swing stage and a measuring contact stage, and transmits the stage division time sequence results to the database module and the operation evaluation module.

[0069] The database module includes a signal storage database and a measurement operation evaluation rule database. The signal storage database is used to store the three-axis signals and absolute value signals of acceleration and measurement force; the measurement operation evaluation rule database is used to store the rule data of measurement operation evaluation.

[0070]

[0071] ​​The operation evaluation module is used to evaluate the measurement operation according to the measurement operation scoring rules in the measurement operation evaluation rule database and output an evaluation report.

[0072] Example 2

[0073] like Figure 3 As shown, a method for evaluating the measurement operation of an articulated coordinate measuring machine operator based on the division of operation stages is performed on the basis of the evaluation system described in Example 1, and the specific steps are as follows:

[0074] 1) Preparation and start of measurement

[0075] This step mainly performs some preparatory work and then prompts the operator to start measuring.

[0076] Before starting measurement, you need to enter the articulated coordinate measuring machine model, operator number, and select the corresponding measurement object. The measurement object is a feature standard part with multiple geometric features, and then the operator is prompted to start the measurement operation.

[0077] Feature standard parts must meet the following requirements: in terms of size, their maximum length must reach two-thirds of the arm length of the articulated coordinate measuring machine, and they must contain three or more different geometric features such as planes, spheres, cylinders, cones, etc., with a number of sizes reaching 10 or more. They must be placed within the range of 20%-80% of the measurement space of the articulated coordinate measuring machine, and the placement posture must maintain an angle between -30° and 30° with the horizontal plane.

[0078] 2) Signal acquisition

[0079] The operator uses an articulated coordinate measuring machine to collect data from different sampling points of the characteristic standard part; the information acquisition module collects and records the data required for the evaluation of the measurement operation, including the measurement start time, measurement end time, three-axis acceleration signal and three-axis measurement force signal.

[0080] 3) Signal preprocessing

[0081] First, the collected three-axis acceleration signal and the three-axis measurement force signal are unified in time, and the three-axis acceleration signal and the measurement force signal are low-pass filtered to eliminate the high-frequency noise of the signal.

[0082] Then the absolute values ​​of the three-axis acceleration signal and the three-axis measurement force signal are calculated to obtain the absolute value signals of acceleration and measurement force:

[0083] Located in T i The three-axis acceleration at the moment is a xi 、a yi 、a zi , then in T i Absolute value of acceleration at a moment ifor:

[0084]

[0085] Located in T i The triaxial measurement force at the moment is f xi 、f yi 、f zi , then in T i Absolute value of acceleration at a moment f i for:

[0086]

[0087] 4) Operation phase division

[0088] The entire measurement operation process is divided into multiple measurement point sampling operations according to the acceleration absolute value signal, and each measurement point sampling operation is divided into a measurement arm swing phase and a measurement contact phase.

[0089] The measurement process consists of a series of point-sampling operations. Each point-sampling operation begins with the arm swing phase, followed by the contact phase. When the contact phase ends, the current point-sampling phase ends and the next begins, repeating this cycle until the operation is complete. During the arm swing phase, the operator swings the arm to move the probe. When the stylus's ruby ​​ball contacts the surface to be measured, the two collide, creating a sudden spike in the acceleration curve. At the onset of this spike, the arm swing phase of the measurement operation ends and the contact phase begins. Once point-sampling is complete, the operator moves the probe away from the surface to be measured, generating a gradually increasing acceleration. At the moment the acceleration begins to increase, the current measurement operation ends and the arm swing phase of the next operation begins.

[0090] The specific method for dividing the operation phases is as follows: starting from the measurement start time and in accordance with the time sequence, when the absolute value of the acceleration exceeds the starting threshold, the measurement arm swing phase of the first point sampling operation begins. When a sudden spike is identified, the measurement arm swing phase of each point sampling operation is divided from the start time of the measurement arm swing phase to the moment the sudden spike is generated. When a motion signal is identified, the measurement contact phase of this point sampling operation ends, so the measurement contact phase is divided from the moment the sudden spike is generated to the moment the motion signal is generated. The moment the motion signal is detected is used as the start time of the measurement arm swing phase of the next point sampling operation, and the next operation phase division begins. This process repeats until a point sampling operation ends and no signal is identified to end the next measurement operation. The measurement end time is reached, and the operation division ends.

[0091] The starting threshold is 0.08-0.12m / s 2 .

[0092] The mutation peak recognition method: first, according to the difference algorithm, the wave peak and wave trough of the acceleration absolute value signal are recognized. A fluctuation of the signal experiences left wave trough, wave peak and right wave trough in turn. The following conditions are met to recognize the fluctuation as a mutation peak:

[0093] Condition 1: the time interval between the left wave trough and the wave peak is less than the first judgment threshold (the value of the first judgment threshold is 0.03-0.04s), and the slope of the line connecting the left wave trough and the wave peak is greater than the second judgment threshold (the value of the second judgment threshold is 25-30m / s 3 )。

[0094] Condition 2: the time interval between the right wave trough and the wave peak is less than the third judgment threshold (the value of the third judgment threshold is 0.06-0.08s), and the absolute value of the slope of the line connecting the right wave trough and the wave peak is greater than the fourth judgment threshold (the value of the fourth judgment threshold is 20-25m / s 3 )。

[0095] Condition 3: the standard deviation of the acceleration absolute value signal within the first judgment duration (the value of the first judgment duration is 0.3-0.5s) after the right wave trough is less than the fifth judgment threshold. The value of the fifth judgment threshold is 0.055-0.060m / s 2 .

[0096] The standard deviation of the acceleration absolute value signal within a period of time is calculated according to the following formula:

[0097] Let the acceleration absolute value from time T i to time T i+n be a i -a i+n , then the mean acceleration absolute value is

[0098]

[0099] The standard deviation δ of the acceleration absolute value signal is:

[0100]

[0101] The moving signal recognition method: first, the first stable contact interval is found, then the mean acceleration absolute value of the stable contact interval is calculated; the first time point after the stable contact interval that reaches the moving speed threshold is taken as the time point of detecting the moving signal. The stable contact interval is continuously searched from the time point of the moving signal, and the above steps are alternately repeated to obtain all the moving signals.

[0102] The stable interval is an interval in which the standard deviation of the acceleration absolute value is lower than the sixth judgment threshold (the value of the sixth judgment threshold is 0.05-0.065m / s 2) and the time length is equal to the second judgment time length (the value of the second judgment time length is 0.4-0.6s). The moving speed threshold is 1.4-1.6 times of the average value of the absolute value of the acceleration in the initial stable contact interval of the current sampling point.

[0103] As shown in Figure 4 the acceleration absolute value signals collected in the first two sampling point operations, according to the operation stage division method, the time ① to the time ② can be divided into the first measurement arm swing stage, and the time ② to the time ③ can be divided into the first measurement contact stage; the time ③ to the time ④ can be divided into the second measurement arm swing stage, and the time ④ to the time ⑤ can be divided into the second measurement contact stage. The time ① is the time when the acceleration absolute value is greater than the starting threshold, the time ② is the time when the first mutation peak occurs, the time ③ is the time when the first moving signal occurs, the time ④ is the time when the second mutation peak occurs, and the time ⑤ is the time when the second moving signal occurs. ⑥ is the first mutation peak, ⑦ is the second mutation peak, and ⑧ and ⑨ are the stable contact intervals found.

[0104] In addition, some operators sometimes use continuous contact sampling point mode, so that the ruby ball of the measuring head is always in contact with a certain measurement surface for multiple sampling points. In this sampling point operation, the measurement arm swing stage and the measurement contact stage cannot be distinguished by identifying the mutation peak. If no mutation peak is identified between the two adjacent moving signals, the start time of the measurement contact stage is determined by the difference between the standard deviations of the measurement arm swing stage and the measurement contact stage: the start time of the stable contact interval between the two moving signals is taken as the start time of the measurement contact stage.

[0105] 5) Score the measurement operation according to the measurement operation scoring rule

[0106] An operator with high operation level of articulated coordinate measuring machine can make smooth motion in the stage of swinging the measurement arm to move the measuring head to the sampling point position, that is, the acceleration change curve of the measuring head end is smooth, and the maximum value of the acceleration is kept within a certain range. In the stage of contacting the ruby ball at the end of the measuring head with the surface to be measured, stable contact should be maintained without relative movement, and the maximum value of the measurement force is within a reasonable range. In addition, the operator with high operation level should spend less time in each operation stage, and the frequency of improper operation is low, and the measurement result does not introduce too large human error.

[0107] Therefore, the whole measurement operation process is divided into multiple measurement sampling point operations, each sampling point operation is divided into a measurement arm swing stage and a measurement contact stage, and an evaluation model is established according to the acceleration, measurement force and time spent in each stage as follows:

[0108] 1. Measurement arm swing stage evaluation index:

[0109] 1.1 Swing stability

[0110] The swing stability is mainly reflected by the acceleration change rate of the probe end. The jerk J is obtained by differentiating the acceleration. Therefore, the jerk J is used as an indicator to evaluate the swing stability.

[0111] Located in T i The three-axis acceleration at the moment is a xi 、a yi 、a zi , in T i+1 The three-axis acceleration at the moment is a x(i+1) 、a y(i+1) 、a z(i+1) , then

[0112]

[0113] Take the maximum value J of the jerk in the swing phase max for:

[0114] J max =MAX(J i )

[0115] The evaluation rule for swing stability is that the smaller the maximum jerk, the smoother the swing and the better the operating effect.

[0116] Therefore, the swing stability score A1 is:

[0117]

[0118] Among them, J0 is the preset stability optimization parameter, and its value is based on the pre-test and jerk optimization value formulated by the expert team.

[0119] 1.2 Swing phase time

[0120] According to the operation phase division of the previous step, the swing phase time T of each measurement can be obtained bd .

[0121] The evaluation rule for the swing phase time is that the shorter the swing phase time, the higher the score.

[0122] Therefore, the score A2 for the swing phase time is:

[0123]

[0124] Among them, T 10 It is a preset optimal parameter for swing time, and its value is based on the optimal value of swing phase time developed by the expert team based on the tests conducted in advance.

[0125] 1.3 Swing acceleration

[0126] This scoring method evaluates the swing force applied by the operator. Excessive swing force should be avoided, as this can cause excessive deformation of the measuring arm and rotary joint, potentially damaging the measuring machine. The absolute value of acceleration during the swing process can reflect the magnitude of the swing force. Therefore, the scoring rule for swing acceleration is as follows: a threshold for the absolute value of acceleration is set. If the maximum absolute value of acceleration during the swing process exceeds the threshold, no points are awarded for this item, and a warning indicating excessive swing acceleration was applied during this point acquisition operation is included in the evaluation report. If the threshold is not exceeded, full marks are awarded for this item.

[0127] Therefore, the score A3 for the oscillation acceleration is:

[0128]

[0129] Among them, a max is the maximum absolute value of acceleration during the swing process, a 10 The swing acceleration threshold is set, the optional value is 25-35m / s 2 .

[0130] 2. Measuring contact phase evaluation indicators

[0131] 2.1 Measuring contact stability

[0132] Contact stability is evaluated by measuring the average absolute acceleration value during the contact phase. The scoring rule is that the smaller the average absolute acceleration value during the contact phase, the higher the score. If the average absolute acceleration value exceeds the set threshold, the operation is judged to have failed to maintain good contact, and a warning indicating that good contact was not maintained during this sampling operation is output in the evaluation report.

[0133] Assume that the absolute value of acceleration at time T1 is a 1jc , in T n The absolute value of acceleration at a moment is njc , then the mean of the absolute values ​​of acceleration during the contact phase is for:

[0134]

[0135] Therefore, the score A4, which measures contact stability, is:

[0136]

[0137] Among them, a0 is the preset measurement acceleration average excellent parameter, and its value is set to 0.15-0.2m / s 2 . a 20 The acceleration threshold is set to 0.35-0.45m / s. 2 .

[0138] 2.2 Measuring force fluctuations

[0139] The measurement force fluctuation is mainly obtained by taking the derivative of the three-axis measurement force with respect to time to obtain the change of the measurement force.

[0140] In this method, let T i The triaxial measurement force at the moment is f xi 、f yi 、f zi , set at T i+1 The triaxial measurement force at the moment is f x(i+1) 、f y(i+1) 、f z(i+1) , get the maximum fluctuation value S max .

[0141]

[0142] S max =MAX(S i )

[0143] The evaluation rule for measuring force fluctuations is: S max The smaller the value, the higher the score.

[0144] Therefore, the score A5 for the measured force fluctuation is:

[0145]

[0146] Among them, S0 is the preset measurement force fluctuation value excellent parameter, and its value is based on the excellent measurement force fluctuation value formulated by the pre-test and the expert team.

[0147] 2.3 Measuring contact phase time

[0148] According to the operation phase division of the previous steps, the time T of the measurement contact phase of each measurement can be obtained jc .

[0149] The evaluation rule for the swing phase time is that the shorter the contact phase time is, the higher the score is.

[0150] Therefore, the contact phase time score A6 is:

[0151]

[0152] Among them, T 20 It is a preset measurement time optimization parameter, and its value is based on the optimal value of the measurement contact phase time developed by the expert team based on the previous tests.

[0153] 2.4 Maximum measuring force

[0154] Excessive force applied by the operator during operation can cause significant deformation of the probe tip, affecting the measurement results. Therefore, the scoring rule for maximum force is to set a threshold for force. If the maximum force applied during contact exceeds the threshold, no points are awarded, and a warning indicating excessive force is generated in the evaluation report. If the threshold is not exceeded, full points are awarded for this item.

[0155] The maximum measuring force rating A7 is therefore:

[0156]

[0157] Among them, f max To measure the maximum value of the measurement force during the contact process, f0 is the set maximum measurement force threshold, and its value is 10-15N.

[0158] The scoring system for each indicator is 100 points, with the highest score not exceeding 100 and the lowest score not less than 0.

[0159] Often a sampling operation is repeated n times, and the total scores B1-B7 of the evaluation indicators in the two stages are obtained by the weighted average of the indicator scores corresponding to each operation.

[0160] For example, the expression of the swing stability index score B1 is as follows:

[0161]

[0162] Among them A 1i is the score of the swing smoothness index of the i-th sampling operation.

[0163] The total scores of the seven evaluation indicators B1-B7 are added together with a certain weight coefficient to obtain the comprehensive score M:

[0164] M=k1B1+k2B2+k3B3+k4B4+k5B5+k6B6+k7B7

[0165] Among them, k1+k2+k3+k4+k5+k6+k7=1; k1-k7 are the weight coefficients of the seven evaluation indicators. Their values ​​are determined based on the differences in the importance of the seven evaluation indicators under the current working conditions and the evaluation of the expert team. They can also be further modified based on the actual operation conditions of operators of different levels.

[0166] 6) Evaluation report output

[0167] A. Give an overall evaluation of the operator's operation based on the size of the comprehensive score M:

[0168] M≤C1: Unqualified.

[0169] C2≥M≥C1: qualified.

[0170] M≥C2: Excellent.

[0171] Among them, C1<C2, and the specific values ​​of C1 and C2 are determined by the expert team, and can also be divided into multiple levels according to the size of the M value.

[0172] B. Output the total score of each evaluation indicator B1-B7, and remind the operator that the indicators with scores below the qualified value need to be improved. The qualified value can be 40-60.

[0173] C. Output the evaluation index score A for each sampling operation 1i -A 7i , for the swing acceleration A 3i , measure contact stability A 4i , Maximum measuring force A 7i These three items contain alarm prompt indicators. If the score is 0, the score will be marked in red and a corresponding warning will be output.

[0174] For the point sampling operation that outputs a warning, the operator is prompted to repeat the measurement of the geometric features formed by the points sampled this time to reduce the introduction of human factors.

Claims

1. A method for evaluating the operation of an articulated coordinate measuring machine based on stage division, characterized in that: The following steps are involved: Step 1: The operator uses an articulated coordinate measuring machine to collect data from multiple measured locations on the characteristic standard part; The probe of the articulated coordinate measuring machine is equipped with an acceleration sensor and a force sensor. The axis acceleration sensor detects the acceleration change of the probe during operation; The force sensor detects changes in the measuring force applied to the stylus during operation. The acceleration signal measured by the acceleration sensor and the measurement force signal measured by the force sensor are preprocessed; the specific process of the preprocessing is to unify the acceleration signal and the measurement force signal in time, and perform low-pass filtering on the acceleration signal and the measurement force signal; Step 2: Operation Phase Division According to the acceleration change of the probe, the entire measurement operation process is divided into multiple measurement point sampling operations, and each measurement point sampling operation is divided into a measurement arm swing phase and a measurement contact phase; The division process is as follows: extract the moment when the sudden change peak and the movement signal appear in the acceleration change curve; take the moment when the sudden change peak appears to the moment when the next movement signal appears as a measurement contact stage; The time from the appearance of the moving signal to the appearance of the next sudden spike is regarded as a swing phase of the measuring arm; The method for identifying sudden spikes is as follows: first, the peaks and troughs of acceleration are identified according to a differential algorithm; the acceleration curve between the troughs on both sides of each peak is considered a fluctuation; the following conditions must be met to identify a fluctuation as a sudden spike: Condition 1: the time interval between the previous trough and the peak is less than a first judgment threshold, and the slope of the line connecting the previous trough and the peak is greater than a second judgment threshold; Condition 2: the time interval between the next trough and the peak is less than a third judgment threshold; the absolute value of the slope of the line connecting the next trough and the peak is greater than a fourth judgment threshold; Condition 3: the standard deviation of the acceleration absolute value signal within the first judgment time period after the next trough is less than a fifth judgment threshold; The motion signal recognition method comprises the following steps: starting from the measurement start time, searching for the first stable contact interval on the acceleration change curve; the stable contact interval is an interval in which the acceleration standard deviation is lower than the sixth judgment threshold and the duration is equal to the second judgment duration; after finding the stable contact interval, taking the first moment after the stable contact interval that reaches the movement speed threshold as the moment when the motion signal is detected; starting from the moment of the movement signal, continue searching for stable contact intervals backward, alternating back and forth, to obtain all motion signals; the movement speed threshold is 1.4-1.6 times the acceleration mean of the previous stable contact interval; When no sudden peak is identified between two adjacent movement signals, the start time of the stable contact interval between the two movement signals is used as the start time of a contact measurement phase; Step 3: Evaluate the measurement operation of the operation; 3-1. Calculate the evaluation index for each measurement arm swing stage 3-1-1. Calculate the swing stability score A1 as follows: Among them, J max is the maximum value of the jerk of each acceleration sampling point during the swing phase of the measuring arm; J0 is the preset excellent stability parameter; 3-1-2. Calculate the swing phase time score A2 as follows: Among them, T bd is the duration of the arm swing phase, T 10 Excellent parameters for preset swing timing; 3-1-3. Calculate the swing acceleration score A3 as follows: Among them, a max is the maximum acceleration of the measuring arm during the swing phase; a 10 is the preset swing acceleration threshold; 3-2. Calculate the evaluation index for each measurement contact stage; 3-2-1. Calculate the contact stability score A4 as follows: in, is the average acceleration value during the contact phase; a0 is the preset excellent parameter for the average acceleration value; a 20 It is the preset maximum threshold value of measured acceleration; 3-2-2. Calculate the measurement force fluctuation score A5 as follows: Among them, S max The maximum value of the measurement force fluctuation value of each measurement force sampling point in the contact phase; the measurement force fluctuation value of a measurement force sampling point is equal to the absolute value of the difference between the measurement force value measured at the measurement force sampling point and the measurement force value measured at the next measurement force sampling point divided by the measurement force sampling interval; S0 is a preset measurement force fluctuation value optimal parameter; 3-2-3. Calculate the measurement phase time score A6 as follows: Among them, T jc To measure the duration of the contact phase, T 20 Excellent parameters for preset measurement time; 3-2-4. Calculate the maximum measurement force score A7 as follows: Among them, f max is the maximum measuring force of the probe during the contact phase; f0 is the preset maximum measuring force threshold; When the calculated values ​​of scores A1 to A7 are greater than 100, the values ​​are set to 100; when the calculated values ​​of scores A1 to A7 are less than 0, the values ​​are set to 0; Step 4: Evaluate the operator based on the scores A1 to A7 obtained in step 3; The average values ​​of the scores A1 to A3 of all the measurement arm swing stages are calculated as the total scores B1 to B3 of the three evaluation indicators for the measurement arm swing; the average values ​​of the scores A4 to A7 of all the measurement contact stages are calculated as the total scores B4 to B7 of the three evaluation indicators for the measurement contact; The comprehensive score M is calculated as follows: M=k1B1+k2B2+k3B3+k4B4+k5B5+k6B6+k7B7 Among them, k1-k7 are the weight coefficients of the seven evaluation indicators; k1+k2+k3+k4+k5+k6+k7=1; The higher the comprehensive score M is, the better the operator's operation of the articulated coordinate measuring machine is.

2. The method for evaluating the operation of an articulated coordinate measuring machine based on stage division according to claim 1, characterized in that: The moment when the probe exceeds the starting threshold for the first time is regarded as the starting moment of the first measuring arm swing phase; the starting threshold is 0.08-0.12m / s 2 .

3. The method for evaluating the operation of an articulated coordinate measuring machine based on stage division according to claim 1, characterized in that: The first judgment threshold is 0.03-0.04s; the second judgment threshold is 25-30m / s 3 The third judgment threshold is 0.06-0.08s; the fourth judgment threshold is 20-25m / s 3 The first judgment time is 0.3-0.5s; the fifth judgment threshold is 0.055-0.060m / s 2 ; The value of the sixth judgment threshold is 0.05-0.065m / s 2 ; The second judgment time is 0.4-0.6s.

4. The method for evaluating the operation of an articulated coordinate measuring machine based on stage division according to claim 1, characterized in that: Preset acceleration excellent parameter a 10 The value is 25-35m / s 2 The preset value of the measured acceleration average excellent parameter a0 is 0.15-0.2m / s 2 ; The preset maximum threshold value of measured acceleration a 20 The value is 0.35-0.45m / s 2 .

5. The method for evaluating the operation of an articulated coordinate measuring machine based on stage division according to claim 1, characterized in that: The maximum measurement force threshold f0 is 10-15N.

6. An articulated coordinate measuring machine operation evaluation system based on stage division, characterized by: Used to perform an articulated coordinate measuring machine operation evaluation method based on stage division as described in any one of claims 1 to 5; the evaluation system includes an information acquisition module, a signal processing module, a database module and an operation evaluation module; the information acquisition module includes an acceleration signal acquisition module and a measurement force signal acquisition module; the acceleration signal acquisition module includes a three-axis acceleration sensor installed at the end of the probe for collecting three-axis acceleration signals; the measurement force signal acquisition module includes a three-axis force sensor installed at the end of the stylus for collecting and measuring three-axis measurement force signals; The signal processing module is used for signal preprocessing and operation stage division; the signal preprocessing module unifies the collected acceleration signal and measurement force signal in time, performs low-pass filtering on the acceleration signal and measurement force signal, and then processes the three-axis data of the acceleration signal and measurement force signal to generate an absolute value signal; the operation stage division module divides the entire measurement operation process into multiple measurement point sampling operations based on the acceleration signal, and then divides each measurement point sampling operation into a measurement arm swing phase and a measurement contact phase, and transmits the timing results of the phase division to the database module and the operation evaluation module; The database module includes a signal storage database and a measurement operation evaluation rule database; the signal storage database is used to store the acceleration, the measurement force triaxial signal and the absolute value signal; the measurement operation evaluation rule database is used to store the measurement operation evaluation rule data; The operation evaluation module is used to evaluate the measurement operation according to the rule data.

7. The articulated coordinate measuring machine operation evaluation system based on stage division according to claim 6, characterized in that: The information acquisition module includes a data input module and a data input module; the data input module is used to input the operator number, measurement start time and measurement end time on the computer.

8. An articulated coordinate measuring machine operation alarm system, characterized in that: It includes an alarm module and an evaluation system as described in claim 6; during the evaluation process of the evaluation system, when any one of the total scores of the evaluation indicators B1 to B7 is lower than the qualified value, the alarm module issues a prompt that the corresponding indicator needs to be improved; when the value of the swing acceleration score A3, the measurement contact stability score A4, and the maximum measurement force score A7 in any swing stage of the measuring arm is 0, the alarm module issues a prompt that the corresponding indicator needs to be improved.

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