An automatic point picking method for a jointed coordinate measuring machine probing process

Abstract

This invention discloses an automatic point acquisition method for the probing process of an articulated coordinate measuring machine (ACM). The method is as follows: 1. The operator moves the probe to the position on the workpiece where coordinates need to be acquired. 2. During the operator's movement of the ACM probe, the absolute values ​​of the measuring force, acceleration, and angular velocity of the probe are continuously acquired. 3. When the absolute values ​​of the measuring force, acceleration, and angular velocity meet the automatic point acquisition conditions, the ACM switches from a moving state to an automatic point acquisition state; in the automatic point acquisition state, the ACM automatically acquires the spatial coordinates of the probe tip. 4. The ACM leaves the automatic point acquisition state and enters the moving state. This invention employs a multi-sensor information fusion scheme, integrating force, acceleration, and angular velocity signals to identify appropriate point acquisition opportunities and automatically acquire points, improving the accuracy of point acquisition during the ACM's probing process and reducing human error.

Description

Technical Field

[0001] This invention belongs to the field of coordinate measurement technology, specifically an automatic point acquisition method for the detection process of an articulated coordinate measuring machine. Background Technology

[0002] Contact measurement (i.e., probing) using an articulated coordinate measuring machine requires the operator to hold and move the measuring arm and probe, bringing the contact ball on the probe stylus into contact with the surface being measured. Once the appropriate position is reached, the operator manually presses the sampling button to collect the sample. During this process, excessive measuring force or unstable operation that causes the contact ball on the probe to fail to maintain good contact with the surface being measured can lead to errors in the measurement results.

[0003] When operators are novice or performing difficult measurement tasks, it is difficult to manually control the measuring force and probe stability within a suitable range. This can easily lead to measurement errors due to sampling at inappropriate times. The operator's need to judge the timing of sampling and manually press buttons also increases the difficulty of the probe operation. In view of these problems, it is necessary to change the traditional method of manual button sampling and provide an automatic sampling method for the probe process of an articulated coordinate measuring machine. Summary of the Invention

[0004] The purpose of this invention is to provide an automatic point acquisition method for the detection process of an articulated coordinate measuring machine. By integrating information from multiple sensors, the method automatically acquires points based on the timing of the acquisition. This addresses the technical problem in the prior art where the articulated coordinate measuring machine requires manual operation for point acquisition, which easily introduces human error. Furthermore, it poses challenges for novices or those performing difficult measurement tasks, resulting in high operational difficulty and intensity.

[0005] This invention provides an automatic point acquisition method for the probing process of an articulated coordinate measuring machine (ACM). The measuring equipment includes an ACM, an inertial sensor, and a triaxial force sensor. The inertial sensor and the triaxial force sensor are mounted on the probe of the ACM; the inertial sensor can sense the motion state of the probe, and the triaxial force sensor can detect the pressure on the probe.

[0006] The automatic point acquisition method for the detection process of this articulated coordinate measuring machine includes the following steps:

[0007] Step 1: The operator holds the probe of the articulated coordinate measuring machine and moves it to the position on the workpiece where coordinates need to be acquired. The articulated coordinate measuring machine has two working states: automatic point acquisition state and moving state; initially, the articulated coordinate measuring machine is in the moving state.

[0008] Step 2: During the process of the operator moving the probe of the articulated coordinate measuring machine, the absolute value of the measuring force f of the probe is continuously collected. i absolute value of acceleration a iangular velocity absolute value ω i .

[0009] Step 3: When measuring the absolute value of the force f i absolute value of acceleration a i angular velocity absolute value ω i When the automatic point sampling conditions are met, the articulated coordinate measuring machine switches from the moving state to the automatic point sampling state; the articulated coordinate measuring machine in the automatic point sampling state automatically collects the spatial coordinates of the probe tip once or multiple times.

[0010] Automatic point sampling conditions include the following two conditions:

[0011] Condition 1. The absolute value of the measured force f i The first judgment duration T before the current moment a The force remained within the measured force threshold range.

[0012] Condition 2. The second judgment time T before the current time t1 is the standard deviation of acceleration δ1. b Within a range that is consistently less than or equal to the acceleration standard deviation sampling threshold, and where the angular velocity standard deviation δ2 is within the second judgment duration T prior to the current moment. b The value remains within the threshold of the standard deviation of angular velocity.

[0013] Step 4: After completing automatic point acquisition, the articulated coordinate measuring machine continuously calculates the second standard deviation analysis duration T before the current time t1. d The standard deviation of internal acceleration δ3; when the standard deviation δ3 is greater than or equal to the acceleration standard deviation movement threshold, the articulated coordinate measuring machine disengages from the automatic point acquisition state and enters the movement state.

[0014] Step 5: Repeat steps 3 and 4 until all target locations on the workpiece have been sampled.

[0015] Preferably, the measuring device further includes a controller. The controller is a PC computer. The signal output interfaces of the inertial sensor and the triaxial force sensor are both connected to the controller. The controller communicates with the articulated coordinate measuring machine (ACM), enabling the controller to control the ACM to perform automatic point acquisition.

[0016] Preferably, the measuring device also includes an audio prompt module. In step four, after the articulated coordinate measuring machine automatically completes the spatial coordinates, the audio prompt module emits a prompt sound, prompting the operator to move the probe to the next target location where a point needs to be sampled.

[0017] Preferably, the sound prompt module uses a buzzer.

[0018] Preferably, the measured absolute value of force f i absolute value of acceleration ai angular velocity absolute value ω i The triaxial force signals are acquired by a triaxial force sensor, and the triaxial acceleration and angular velocity signals are acquired by an inertial sensor. These signals are then processed by low-pass filtering.

[0019] Preferably, the measured force threshold range is 0.5N to 10N; the first judgment duration T a The value can be any value between 0.2s and 0.4s.

[0020] Preferably, the acceleration standard deviation sampling threshold is 0.03 m / s². 2 ~0.05m / s 2 Any value in the range; the threshold range for the standard deviation of angular velocity is any value within the range of 0.25° / s to 0.45° / s; the second judgment duration T b The value can be any value between 0.05s and 0.15s.

[0021] Preferably, in condition 2 of step 3, the acceleration standard deviation δ1 is specifically taken as the first standard deviation analysis duration T before the current time t1. c The standard deviation of internal acceleration is expressed as:

[0022]

[0023] Where n is the duration T of the first standard deviation analysis before the current time t1. c Number of samplings within; a k The duration T of the first standard deviation analysis before the current time t1. c The acceleration obtained from the kth sample within the interval; The duration T of the first judgment before the current time t1 a The average acceleration obtained from the nth sampling is expressed as follows:

[0024]

[0025] Preferably, in condition 2 of step 3, the standard deviation of angular velocity δ2 is specifically taken as the analysis time T of the first standard deviation before the current time t1. c The standard deviation of the interior angular velocity is expressed as:

[0026]

[0027] Where, ω k The duration T of the first standard deviation analysis before the current time t1. c The angular velocity obtained from the k-th sample; The duration T of the first standard deviation analysis before the current time t1. c The average angular velocity obtained from the inner n samplings is expressed as follows:

[0028]

[0029] As a preferred option, the duration T of the first standard deviation analysis is... c The value can be any value between 0.2s and 0.4s.

[0030] As a preferred option, the duration T of the second standard deviation analysis is... d The value can be any value between 0.2s and 0.3s. The aforementioned acceleration standard deviation shift threshold is 0.07m / s². 2 ~0.09m / s 2 Any value in the range.

[0031] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0032] 1. This invention provides a multi-sensor information fusion scheme that integrates force, acceleration, and angular velocity signals to identify appropriate sampling timing and automatically collect data, thereby improving the accuracy of data collection during the detection process of the articulated coordinate measuring machine and reducing the impact of human error on the measurement results.

[0033] 2. The automatic point sampling method provided by this invention eliminates the need for operators to judge the timing of point sampling or press buttons to sample points, thereby changing the interactive mode of the joint coordinate measuring machine's detection operation and greatly reducing the operational difficulty and intensity of the detection process.

[0034] 3. This invention changes the detection speed by adjusting the preset judgment time, acceleration, and angular velocity standard deviation thresholds, which can meet the efficiency requirements of different measurement tasks. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the articulated coordinate measuring machine used in this invention. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings.

[0037] like Figure 1 As shown, an automatic point-collecting method for the detection process of an articulated coordinate measuring machine (ACM) is described. The measuring equipment includes an ACM 1, an inertial sensor 2, a triaxial force sensor 3, a controller 4, and an audio prompt module. The controller 4 is a PC computer. The audio prompt module uses a buzzer.

[0038] Inertial sensor 2 is mounted on the probe of the articulated coordinate measuring machine (CMM); triaxial force sensor 3 is mounted between the probe stylus and the main body of the CMM, enabling it to detect the pressure exerted when the stylus contacts the workpiece. Inertial sensor 2 collects the triaxial acceleration signals of the probe during measurement by the CMM; triaxial force sensor 3 collects the triaxial force signals between the probe and the workpiece during measurement by the CMM. The controller processes and analyzes the collected sensor signals and communicates with the CMM.

[0039] This automatic point acquisition method for the detection process of an articulated coordinate measuring machine includes the following steps:

[0040] Step 1: Activate Automatic Point Acquisition Mode. The operator holds the probe of the articulated coordinate measuring machine and moves it to the position on the workpiece where coordinates need to be acquired. The articulated coordinate measuring machine has two working states: automatic point acquisition mode and moving mode; initially, the articulated coordinate measuring machine is in moving mode.

[0041] Step 2: During the process of the operator moving the probe of the articulated coordinate measuring machine, the triaxial force sensor 3 and the inertial sensor 2 collect the triaxial force signal, triaxial acceleration signal and triaxial angular velocity signal and transmit them to the controller 4.

[0042] Step 3: Signal Preprocessing

[0043] The controller performs low-pass filtering on the received triaxial force, acceleration, and angular velocity signals to eliminate high-frequency noise.

[0044] Then, the absolute values ​​of the triaxial force signal, triaxial acceleration signal, and triaxial angular velocity signal are calculated to obtain the absolute values ​​of the acceleration, angular velocity, and force signals.

[0045] At any time T i In measuring the absolute value of force f i The expression is:

[0046]

[0047] Among them, f xi f yi f zi The three-axis force sensor 3 is located at time T. i The measured force signals along the x, y, and z axes.

[0048] At any time T i In the absolute value of acceleration a i The expression is:

[0049]

[0050] Among them, a xi a yi a zi These are the inertial sensor 2 at time T. i The measured acceleration signals along the x, y, and z axes.

[0051] At any time T i At the absolute value of angular velocity ω i The expression is:

[0052]

[0053] Where, ω xi ω yi ω zi These are the inertial sensor 2 at time T. i The measured angular velocity signals around the x, y, and z axes.

[0054] Step 4: When measuring the absolute value of the force f i absolute value of acceleration a i angular velocity absolute value ω i When the automatic point sampling conditions are met, the articulated coordinate measuring machine switches from the moving state to the automatic point sampling state; the articulated coordinate measuring machine in the automatic point sampling state automatically collects the spatial coordinates of the probe tip once or multiple times.

[0055] Automatic point sampling conditions include the following two conditions:

[0056] Condition 1. The absolute value of the measured force f i The first judgment duration T before the current moment a The force remains within the measured force threshold range. The measured force threshold range is 0.5N to 10N; the first judgment time T a The value can be any value between 0.2s and 0.4s.

[0057] Condition 2. The second judgment time T before the current time t1 is the standard deviation of acceleration δ1. b Within a range that is consistently less than or equal to the acceleration standard deviation sampling threshold, and where the angular velocity standard deviation δ2 is within the second judgment duration T prior to the current moment. b The acceleration standard deviation is consistently less than or equal to the threshold value of the angular velocity standard deviation. The threshold value for sampling the acceleration standard deviation is 0.03 m / s². 2 ~0.05m / s 2 Any value in the range; the threshold range for the standard deviation of angular velocity is any value within the range of 0.25° / s to 0.45° / s; the second judgment duration T b The value can be any value between 0.05s and 0.15s.

[0058] Set the first standard deviation analysis duration T c The value can be any value between 0.2s and 0.4s; the standard deviation of acceleration δ1 at the current time t1 is specifically taken as the first standard deviation analysis time T before the current time t1. c The standard deviation of internal acceleration is expressed as:

[0059]

[0060] Where n is the duration T of the first standard deviation analysis before the current time t1. c Number of samplings within; a k The duration T of the first standard deviation analysis before the current time t1. c The acceleration obtained from the kth sample within the interval; The duration T of the first judgment before the current time t1 a The average acceleration obtained from the nth sampling is expressed as follows:

[0061]

[0062] The standard deviation δ2 of the angular velocity at the current time t1 is specifically taken as the first standard deviation analysis time T before the current time t1. c The standard deviation of the interior angular velocity is expressed as:

[0063]

[0064] Where, ω k The duration T of the first standard deviation analysis before the current time t1. c The angular velocity obtained from the k-th sample; The duration T of the first standard deviation analysis before the current time t1. c The average angular velocity obtained from the inner n samplings is expressed as follows:

[0065]

[0066] Step 5: After the articulated coordinate measuring machine automatically completes the spatial coordinate acquisition, the sound prompt module emits a beep, prompting the operator to move the probe to the next target position that needs to be sampled for automatic point acquisition.

[0067] After completing automatic point acquisition, the articulated coordinate measuring machine continuously calculates the second standard deviation analysis duration T up to the current time t1. d The standard deviation of the internal acceleration, δ3, is set to 0.07 m / s². When δ3 is greater than or equal to the acceleration standard deviation shift threshold, the articulated coordinate measuring machine (ACM) disengages from automatic point-sampling mode and enters a shift mode, waiting for the next automatic point-sampling condition to be met before re-entering automatic point-sampling mode. The acceleration standard deviation shift threshold is 0.07 m / s².2 ~0.09m / s 2 Any value in the range. Duration T of the second standard deviation analysis. d The value can be any value between 0.2s and 0.3s.

[0068] Step 6: Repeat steps 5 and 6 until all target locations on the workpiece have been sampled.

[0069] In this embodiment, the operator can adjust the preset first judgment duration, second judgment duration, acceleration standard deviation sampling threshold, and angular velocity standard deviation sampling threshold to change the detection speed, adapting to the efficiency requirements of different measurement tasks. Recommended values ​​for the first judgment duration, second judgment duration, acceleration standard deviation sampling threshold, and angular velocity standard deviation sampling threshold for rapid detection are 0.2s, 0.05s, and 0.05m / s, respectively. 2 And 0.45° / s. The recommended values ​​for the first and second decision times, acceleration standard deviation threshold, and angular velocity standard deviation threshold for slow detection are 0.4s, 0.15s, and 0.03m / s, respectively. 2 and 0.25° / s.

Claims

1. An automatic point picking method for a probing process of an articulated coordinate measuring machine; characterized by: The measuring equipment used includes an articulated coordinate measuring machine (1), an inertial sensor (2), and a triaxial force sensor (3); the inertial sensor (2) and the triaxial force sensor (3) are mounted on the probe of the articulated coordinate measuring machine; the triaxial force sensor (3) can detect the pressure on the probe. The spatial coordinate measurement method for automatic point acquisition using this articulated coordinate measuring machine includes the following steps: Step 1: The operator holds the probe of the articulated coordinate measuring machine and moves it to the position on the workpiece where coordinates need to be acquired. The articulated coordinate measuring machine has two working states: automatic point acquisition state and moving state. Initially, the articulated coordinate measuring machine is in the moving state. Step 2: During the process of the operator moving the probe of the articulated coordinate measuring machine, the absolute value of the measuring force of the probe is continuously collected. absolute value of acceleration absolute value of angular velocity The absolute value of the measured force absolute value of acceleration absolute value of angular velocity The triaxial force signals are collected by the triaxial force sensor (3); the triaxial acceleration signals and triaxial angular velocity signals of the probe are collected by the inertial sensor (2) and calculated respectively; the triaxial force signals, triaxial acceleration signals and triaxial angular velocity signals are processed by low-pass filtering. Step 3: When measuring the absolute value of the force absolute value of acceleration absolute value of angular velocity When the conditions for automatic point acquisition are met, the articulated coordinate measuring machine switches from the moving state to the automatic point acquisition state; the articulated coordinate measuring machine in the automatic point acquisition state automatically acquires the spatial coordinates of the probe tip once or multiple times; Automatic point sampling conditions include the following two conditions: Condition 1. Measuring the absolute value of the force The first judgment duration T before the current moment a The force remained within the measured force threshold range throughout. Condition 2. Acceleration standard deviation The second judgment duration T before the current time t1 b The acceleration standard deviation is consistently less than or equal to the sampling threshold, and the angular velocity standard deviation is... The second judgment duration T before the current moment b The angular velocity remains consistently less than or equal to the standard deviation threshold. Acceleration standard deviation Specifically, the analysis time T of the first standard deviation before the current time t1 is taken. c The standard deviation of internal acceleration is expressed as: ； Where n is the duration T of the first standard deviation analysis before the current time t1. c Number of samplings within; The duration T of the first standard deviation analysis before the current time t1. c The acceleration obtained from the kth sample within the interval; The duration T of the first judgment before the current time t1 a The average acceleration obtained from the nth sampling is expressed as follows: ； Angular velocity standard deviation Specifically, the analysis time T of the first standard deviation before the current time t1 is taken. c The standard deviation of the interior angular velocity is expressed as: ； in, The duration T of the first standard deviation analysis before the current time t1. c The angular velocity obtained from the k-th sample; The duration T of the first standard deviation analysis before the current time t1. c The average angular velocity obtained from the inner n samplings is expressed as follows: ； Step 4: After completing automatic point acquisition, the articulated coordinate measuring machine continuously calculates the second standard deviation analysis duration T before the current time t1. d Standard deviation of internal acceleration Standard deviation When the acceleration standard deviation movement threshold is greater than or equal to the joint coordinate measuring machine, the automatic point acquisition state is disengaged and the movement state is entered. Step 5: Repeat steps 3 and 4 until all target locations on the workpiece have been sampled.

2. The automatic point acquisition method for the detection process of an articulated coordinate measuring machine according to claim 1, characterized in that: The measuring device also includes a controller (4); the controller (4) is a PC computer; the signal output interfaces of the inertial sensor (2) and the triaxial force sensor (3) are connected to the controller (4); the controller (4) communicates with the articulated coordinate measuring machine (1) so that the controller (4) can control the articulated coordinate measuring machine (1) to perform automatic point sampling.

3. The automatic point acquisition method for the detection process of an articulated coordinate measuring machine according to claim 1, characterized in that: The measuring device also includes a sound prompt module; in step four, after the articulated coordinate measuring machine automatically completes the spatial coordinates, the sound prompt module emits a prompt sound to prompt the operator to move the probe to the next target position where a point needs to be collected.

4. The automatic point acquisition method for the detection process of an articulated coordinate measuring machine according to claim 1, characterized in that: The measurement force threshold range is 0.5N-10N; the first judgment time T a is any value in 0.2s-0.4s.

5. The automatic point acquisition method for the detection process of an articulated coordinate measuring machine according to claim 1, characterized in that: The acceleration standard deviation sampling point threshold is 0.03 m / s 2 ~ 0.05 m / s 2 Any value in the range of 0.25 ° / s ~ 0.45 ° / s; the second judgment time T b Any value in the range of 0.2 s ~ 0.4 s.

6. The automatic point acquisition method for the detection process of an articulated coordinate measuring machine according to claim 1, characterized in that: The first standard deviation analysis duration T c The value of the first standard deviation analysis duration T is any value in the range of 0.2s to 0.4s.

7. The automatic point acquisition method for the detection process of an articulated coordinate measuring machine according to claim 1, characterized in that: Second standard deviation analysis duration T d The value can be any value between 0.2s and 0.3s; the acceleration standard deviation shift threshold is 0.07m / s². 2 ~0.09m / s 2 Any value in the range.

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