Closed-loop force control size measuring mechanism

Abstract

The utility model discloses a closed-loop force-controlled dimension measuring mechanism, comprising a force sensor, one end of which is a fixed end and the other end of which is an induction end; the linear motor comprises a stator and a rotor which can move relatively, the stator is connected with the sensing end of the force sensor, and the rotor is connected with a measuring head; the first displacement sensor is used for acquiring the moving distance of the rotor or the measuring head; and the force sensor, the linear motor and the first displacement sensor are electrically connected with the controller. According to the utility model, abnormity can be found in time, errors are reduced, and measurement precision is ensured.

Description

Technical Field

[0001] This utility model relates to the technical field of mechatronics and sensing measurement, specifically to a closed-loop force-controlled dimension measurement mechanism. Background Technology

[0002] In the scenario of measuring the dimensions of soft workpieces, the workpiece will be flattened under force, resulting in different workpiece dimensions measured under different forces. Therefore, when measuring the dimensions of soft workpieces, it is necessary to control the measurement pressure to obtain the workpiece dimension under a certain pressure.

[0003] Chinese invention patent application CN201610066597.9, filed earlier by the applicant, discloses a controllable force-based dimension measuring device and its usage method. It involves inputting a measuring force F into a controller, which then controls a driver to output a corresponding current value. A direct-drive motor receives this current value and drives a moving body in a linear motion. This motion of the moving body drives the measuring head, ultimately causing the measuring head to press against the surface of the object being measured with the measuring force F. A displacement sensor transmits the position data of the measuring scale to the controller via the driver, which processes the data to obtain the dimension value. This application employs an open-loop force control method, offering advantages such as simple structure and high speed. However, in the aforementioned application, during measurement, the data of the measuring force F is input to the controller, the controller controls the driver to output the corresponding current value, and the direct drive motor receives the current value and drives the moving body to move in a straight line. The movement of the moving body drives the measuring head to move, and finally the measuring head presses on the object being measured with the measuring force F. In this process, the work done by the current is converted into the power of the measuring head. The conversion rate is easily affected by factors such as inductance, frequency, and voltage, which ultimately affects the magnitude of the measuring force F applied to the object being measured and the measurement accuracy.

[0004] Furthermore, controlling the force for dimensional measurement requires not only accurate force measurement but also a certain level of mechanical precision, particularly a tight fit between the slider and guide rail, and between the stator and mover of the direct drive motor. In this situation, friction and other resistance exist between the slider and guide rail, and between the stator and mover, complicating force control. Ideally, this resistance should remain constant, but in actual measurement, factors such as wear and dust can cause changes in resistance. The controllable force dimensional measurement device may struggle to detect these abnormalities in a timely manner, leading to dimensional errors and affecting measurement accuracy.

[0005] Therefore, it is necessary to develop a closed-loop force-controlled dimension measurement mechanism to overcome the shortcomings in current practical applications. Utility Model Content

[0006] To address the shortcomings of existing technologies, this invention proposes a closed-loop force-controlled dimension measuring mechanism that can promptly detect anomalies, reduce errors, and ensure measurement accuracy.

[0007] The technical solution of this utility model is implemented as follows:

[0008] A closed-loop force-controlled dimensional measurement mechanism, comprising:

[0009] A force sensor, wherein one end of the force sensor is a fixed end and the other end of the force sensor is a sensing end;

[0010] A linear motor, comprising a stator and a mover capable of relative movement, wherein the stator is connected to the sensing end of the force sensor, and a measuring head is connected to the mover;

[0011] A first displacement sensor is used to obtain the moving distance of the mover or the measuring head;

[0012] Furthermore, the force sensor, linear motor, and first displacement sensor are all electrically connected to the controller.

[0013] In a preferred embodiment, a second displacement sensor is further included to obtain the movement distance of the sensing end of the stator or the force sensor, and the second displacement sensor is electrically connected to the controller.

[0014] In a preferred embodiment, the device further includes a housing, with the end of the force sensor away from the linear motor fixedly connected to the housing, the linear motor being movably disposed inside the housing, and a measuring port being provided at the end of the housing away from the force sensor, with the end of the measuring head away from the linear motor extending out of the housing through the measuring port.

[0015] In a preferred embodiment, a guide rail is provided inside the housing, and the measuring head slides in conjunction with the housing via the guide rail.

[0016] In a preferred embodiment, the guide rail includes a fixed rail and a moving rail, wherein the fixed rail is fixedly connected to the housing, the moving rail is fixedly connected to the measuring head, the fixed rail and the moving rail are slidably engaged, and the length directions of the fixed rail and the moving rail are parallel to the moving direction of the measuring head.

[0017] In a preferred embodiment, an end plate is connected to the end of the measuring head away from the linear motor, and the area of ​​the end plate is larger than the area of ​​the measuring port.

[0018] In a preferred embodiment, the side of the end plate away from the linear motor is perpendicular to the direction of movement of the measuring head.

[0019] In a preferred embodiment, both the first displacement sensor and the second displacement sensor are optical grating rulers.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] This invention uses a linear motor to drive a measuring head for measuring the dimensions of soft workpieces. The stator of the linear motor is connected to the sensing end of a force sensor. During the measurement process, the measuring head contacts the surface of the soft workpiece and generates a corresponding reaction force. The force sensor detects the reaction force in real time until the force value obtained by the force sensor equals the preset calibration value. At this point, the value obtained by the first displacement sensor is the moving distance of the measuring head under force control, which can achieve the effect of closed-loop force control, effectively reducing the influence of current conversion rate on measurement and reducing measurement errors.

[0022] Furthermore, during the process of the linear motor driving the measuring head to move, the force sensor can detect the corresponding force value under the reaction action of friction and other resistances. Once the force value measured by the force sensor exceeds the preset normal value range, it can be determined that the resistance at this time has changed compared with the resistance under ideal conditions. This allows the user to detect and deal with the abnormality in time, thereby ensuring the accuracy of the measurement and reducing the error of the dimensional data obtained in subsequent measurements. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model 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 utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a front view of the present invention;

[0025] Figure 2 This is a rear view of the present invention;

[0026] Figure 3 This is a side view of the present invention.

[0027] Reference numerals: Force sensor-1, Stator-2, Mover-3, Measuring head-4, First displacement sensor-5, Housing-6, Guide rail-7, End plate-8. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0029] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," "third," and "fourth," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0030] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0031] Please refer to Figures 1-3 This utility model embodiment provides a closed-loop force-controlled dimension measuring mechanism, comprising:

[0032] Force sensor 1, one end of which is a fixed end and the other end of which is a sensing end;

[0033] A linear motor, comprising a stator 2 and a mover 3 capable of relative movement, wherein the stator 2 is connected to the sensing end of the force sensor 1, and a measuring head 4 is connected to the mover 3;

[0034] The first displacement sensor 5 is used to obtain the moving distance of the mover 3 or the measuring head 4;

[0035] Furthermore, the force sensor 1, the linear motor, and the first displacement sensor 5 are all electrically connected to the controller.

[0036] When the linear motor is energized, it generates a magnetic field, which drives the measuring head 4 to move towards the soft workpiece via the mover 3. When the end of the measuring head 4 away from the linear motor comes into contact with the soft workpiece, the reaction force generated by the contact between the measuring head 4 and the soft workpiece is applied to the sensing end of the force sensor 1 in sequence via the measuring head 4, the mover 3, and the stator 2. The force sensor 1 senses and feeds back to the controller until the force value measured by the force sensor 1 is equal to the calibration value stored in the controller. At this time, the value detected by the first displacement sensor 5 is the moving distance of the measuring head 4 under force control, thereby achieving the effect of closed-loop force control, effectively reducing the influence of current conversion rate on measurement, and reducing measurement error.

[0037] In addition, as the mover 3 and measuring head 4 move toward the soft workpiece, the reaction force generated by the mover 3 and measuring head 4 overcoming friction and other resistance will also act on the sensing end of the force sensor 1 through the stator 2, thereby generating a corresponding force value. Once the above force value exceeds the normal value range stored in the controller, it can be determined that the resistance at this time has changed compared with the resistance under ideal conditions, so that the user can detect the abnormality in time and deal with it, thereby ensuring the accuracy of the measurement and reducing the error of the dimensional data obtained in subsequent measurements.

[0038] In some preferred embodiments, the closed-loop force-controlled dimension measuring mechanism further includes a second displacement sensor for obtaining the moving distance of the sensing end of the stator 2 or the force sensor 1, and the second displacement sensor is electrically connected to the controller.

[0039] The force sensor 1 is a pressure sensor with a free end. When subjected to force, it will move towards its fixed end and drive the stator 2 connected to it to move synchronously. The second displacement sensor monitors the change value of the stator 2 or the sensing end of the force sensor 1 under force in real time. Once it is found that the movement distance of the stator 2 or the sensing end of the force sensor 1 exceeds the normal value range stored in the controller, it can be determined that the force sensor 1 is faulty. This allows the user to detect and deal with the problem in time, reducing the dimensional error caused by the failure of the force sensor 1.

[0040] It is understood that the force sensor 1, linear motor, first displacement sensor 5, and second displacement sensor are all electrically connected to a controller to achieve centralized control. Alternatively, the force sensor 1, linear motor, first displacement sensor 5, and second displacement sensor can be controlled separately by multiple controllers, and the information acquired by the force sensor 1, first displacement sensor 5, and second displacement sensor can be displayed through a display screen or speaker or other transmission device.

[0041] In some preferred embodiments, the closed-loop force-controlled dimension measuring mechanism further includes a housing 6, the end of the force sensor 1 away from the linear motor is fixedly connected to the housing 6, the linear motor is movably disposed inside the housing 6, and a measuring port is provided at the end of the housing 6 away from the force sensor 1, and the end of the measuring head 4 away from the linear motor extends out of the housing 6 through the measuring port.

[0042] In this specific embodiment, the housing 6 is used to protect its internal parts, and during the measurement process, the relative position between the housing 6 and the soft workpiece is fixed. The housing 6, force sensor 1, linear motor, and measuring head 4 are sequentially fixedly connected.

[0043] When the linear motor is powered on, it drives the measuring head 4 to move toward the soft workpiece. When the end of the measuring head 4 away from the linear motor comes into contact with the soft workpiece, the reaction force generated by the contact between the measuring head 4 and the soft workpiece is applied sequentially through the measuring head 4 and the linear motor to the sensing end of the force sensor 1 until the force value measured by the force sensor 1 is equal to the preset calibration value. At this time, the value detected by the first displacement sensor 5 is the moving distance of the measuring head 4 under force control.

[0044] In some optional implementations, the shape of the measuring port is adapted to the cross-sectional shape of the measuring head 4, and the measuring port and the measuring head 4 are slidably sleeved together, which can guide the movement direction of the measuring head 4.

[0045] In some preferred embodiments, both the first displacement sensor 5 and the second displacement sensor are grating rulers, including a scale grating and a grating reading head. The scale grating is fixedly mounted on the housing 6 and extends along the moving direction of the measuring head 4. The grating reading head for obtaining the moving distance of the mover 3 or the measuring head 4 is fixedly mounted on the measuring head 4. The grating reading head for obtaining the moving distance of the sensing end of the stator 2 or the force sensor 1 is fixedly mounted on the sensing end of the stator 2 or the force sensor 1. As the grating reading head moves with the sensing end of the measuring head 4, the stator 2, or the force sensor 1, it reads the position information on the scale grating to obtain the corresponding moving distance.

[0046] In some alternative implementations, the first displacement sensor 5 and the second displacement sensor may also be magnetic scales, laser displacement sensors, or infrared displacement sensors, etc.

[0047] In some preferred embodiments, a guide rail 7 is provided inside the housing 6, and the measuring head 4 slides with the housing 6 through the guide rail 7.

[0048] In this specific embodiment, the guide rail 7 includes a fixed rail and a moving rail. The fixed rail is fixedly connected to the housing 6, and the moving rail is fixedly connected to the measuring head 4. The fixed rail and the moving rail are slidably engaged, and the length directions of both the fixed rail and the moving rail are parallel to the moving direction of the measuring head 4. This design can further guide the moving direction of the measuring head 4, ensuring that the moving direction of the measuring head 4 is consistent with the moving direction of the mover 3.

[0049] In some preferred embodiments, an end plate 8 is connected to the end of the measuring head 4 furthest from the linear motor, and the area of ​​the end plate 8 is larger than the area of ​​the measuring port. The end plate 8 and the measuring head 4 are integrally connected to form an L-shaped plate structure, which on the one hand can limit the movement distance of the measuring head 4 and prevent the measuring head 4 from retracting completely into the housing 6; on the other hand, it can also increase the force balance when contacting soft workpieces.

[0050] In some preferred embodiments, the side of the end plate 8 away from the linear motor is perpendicular to the direction of movement of the measuring head 4, so that when the end plate 8 contacts the soft workpiece, each area of ​​the end side can be effectively made to simultaneously adhere to the surface of the soft workpiece, thereby improving the uniformity of force distribution.

[0051] Working principle:

[0052] When using this utility model embodiment for the first time, calibration is required. The calibration method is as follows:

[0053] S1. Fix the standard force sensor for calibration on the workpiece platform, fix the housing 6, and at the same time, the measuring port is opposite to the standard force sensor. Power on the linear motor to drive the measuring head 4 to move and press on the standard force sensor. The standard force sensor is subjected to force and measures the corresponding force value until the force value measured by the standard force sensor reaches the force value required for measuring soft workpieces. The controller synchronously records the force value measured by the force sensor 1 at this time and uses it as the calibration value.

[0054] S2. Fix the standard workpiece (hard workpiece) on the workpiece platform, power on the linear motor, drive the measuring head 4 to move and press on the standard workpiece until the force value displayed by the force sensor 1 reaches the calibration value. At this time, the distance between the measuring head 4 and the workpiece platform can be calculated by the formula D = L1 + A1, where D is the distance between the measuring head 4 and the workpiece platform, L1 is the size of the standard workpiece, and A1 is the value detected by the first displacement sensor 5 during calibration.

[0055] After calibration, this embodiment of the invention can be used to measure the size of an object. The specific measurement method is as follows:

[0056] The soft workpiece to be measured is fixed on the workpiece platform. The linear motor is powered on to drive the measuring head 4 to move and press on the soft workpiece until the force value displayed by the force sensor 1 reaches the calibrated value. At this time, the size of the soft workpiece is calculated by the formula L2 = L1 + A1 - A2, where L2 is the size of the soft workpiece to be measured, L1 is the size of the standard workpiece, A1 is the value detected by the first displacement sensor 5 during calibration, and A2 is the value detected by the first displacement sensor 5 during measurement.

[0057] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A closed-loop force-controlled dimensional measurement mechanism, characterized in that, include: Force sensor (1), one end of the force sensor (1) is a fixed end and the other end of the force sensor (1) is a sensing end; A linear motor, comprising a stator (2) and a mover (3) capable of relative movement, wherein the stator (2) is connected to the sensing end of the force sensor (1), and a measuring head (4) is connected to the mover (3); The first displacement sensor (5) is used to obtain the moving distance of the mover (3) or the measuring head (4); Furthermore, the force sensor (1), the linear motor, and the first displacement sensor (5) are all electrically connected to the controller.

2. The closed-loop force-controlled dimension measuring mechanism according to claim 1, characterized in that: It also includes a second displacement sensor for obtaining the moving distance of the sensing end of the stator (2) or the force sensor (1), and the second displacement sensor is electrically connected to the controller.

3. The closed-loop force-controlled dimension measuring mechanism according to claim 1 or 2, characterized in that: It also includes a housing (6), the end of the force sensor (1) away from the linear motor is fixedly connected to the housing (6), the linear motor is movably disposed inside the housing (6), and a measuring port is provided at the end of the housing (6) away from the force sensor (1), and the end of the measuring head (4) away from the linear motor extends out of the housing (6) through the measuring port.

4. The closed-loop force-controlled dimension measuring mechanism according to claim 3, characterized in that: The housing (6) is provided with a guide rail (7), and the measuring head (4) slides with the housing (6) through the guide rail (7).

5. The closed-loop force-controlled dimension measuring mechanism according to claim 4, characterized in that: The guide rail (7) includes a fixed rail and a moving rail. The fixed rail is fixedly connected to the housing (6), and the moving rail is fixedly connected to the measuring head (4). The fixed rail and the moving rail are slidably engaged, and the length directions of the fixed rail and the moving rail are parallel to the moving direction of the measuring head (4).

6. The closed-loop force-controlled dimension measuring mechanism according to claim 3, characterized in that: The end of the measuring head (4) away from the linear motor is connected to an end plate (8), the area of ​​which is larger than the area of ​​the measuring port.

7. The closed-loop force-controlled dimension measuring mechanism according to claim 6, characterized in that: The side of the end plate (8) away from the linear motor is perpendicular to the moving direction of the measuring head (4).

8. The closed-loop force-controlled dimension measuring mechanism according to claim 1 or 2, characterized in that: Both the first displacement sensor (5) and the second displacement sensor are grating rulers.

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