Volume measuring device based on force sensor and binocular vision measuring system

Abstract

The present application relates to a kind of volume measuring device based on force sensor and binocular vision measurement system, including binocular vision imaging system, also including the container for containing water, the bottom of container is sealed and guided to move along up and down direction and is equipped with working rod, the lower side of container is provided with the rotation driving mechanism for driving the rotation of working rod and the lifting driving mechanism for driving the up and down movement of working rod, the upper end of working rod is connected with the tray for object placement, the bottom of tray is connected with force sensor, the bottom of force sensor is connected on sensor support, binocular vision imaging system is fixed on the top of container and is used for shooting object on tray.The present application solves the technical problem that only relying on binocular stereo vision measurement system in prior art cannot guarantee the volume accurate measurement of irregular shape object.

Description

Technical Field

[0001] This invention relates to the field of object volume measurement, and more particularly to a volume measurement device based on a force sensor and a binocular vision measurement system. Background Technology

[0002] In many fields, there is a need to measure the volume of objects. A common method for volume measurement is a binocular stereo vision measurement system, which uses two parallel cameras to photograph a rotating object to obtain the coordinates of its endpoints, thereby calculating the object's volume.

[0003] Binocular stereo vision measurement systems are modeled after the human visual system. They obtain three-dimensional information in actual space by processing and calculating two-dimensional images. This belongs to the field of computer vision research. Vision-based measurement methods are usually non-contact, with short measurement time, high accuracy, and the ability to acquire rich three-dimensional information. With these advantages, as well as improvements in camera and software performance, the advantages of vision measurement are further highlighted, making it one of the most effective means of achieving on-site and online measurement.

[0004] Binocular stereo vision measurement systems are based on the principle of parallax and utilize the principle of similar triangles to acquire three-dimensional information of an object from multiple images. The binocular measurement system employs the principle of similar triangles, using proportional relationships to calculate the distance from a point in space to the camera's imaging plane.

[0005] Significant progress has been made in volume measurement based on binocular stereo vision. Mi Yizhou of Hefei University of Technology designed a method for measuring the volume of express delivery packages. This method utilizes binocular vision to perform 3D reconstruction of the package. By measuring the coordinates of the four corners of the top surface of a cuboid in the image, the coordinates of four points in the world coordinate system are reconstructed using a disparity map. The area of ​​the top surface is then calculated, and the volume of the package is determined. This method primarily measures the coordinates of the four vertices of the object's surface to calculate the area of ​​the rectangular surface, which is then multiplied by the height to obtain the object's volume. It is effective for measuring the volume of regular objects but not suitable for measuring the volume of irregular objects.

[0006] Therefore, the advantages of binocular stereo vision measurement systems are that they can measure volume quickly and ensure measurement accuracy for objects with regular shapes (such as cuboids and cubes), but cannot guarantee measurement accuracy for objects with irregular shapes. Summary of the Invention

[0007] The purpose of this invention is to provide a volume measurement device based on a force sensor and binocular vision measurement, so as to solve the technical problem that the existing technology cannot guarantee accurate volume measurement of irregularly shaped objects by relying solely on binocular stereo vision measurement systems.

[0008] To solve the above-mentioned technical problems, the technical solution of the volume force measuring device based on a force sensor and a binocular vision force measuring system in this invention is as follows:

[0009] A volume measurement device based on a force sensor and a binocular vision measurement system includes a binocular vision imaging system and a container for holding water. A working rod is sealed and guided to move along the bottom of the container in a vertical direction. A rotation drive mechanism for driving the working rod to rotate and a lifting drive mechanism for driving the working rod to move up and down are provided on the lower side of the container. A tray for placing objects is connected to the upper end of the working rod. A force sensor is connected to the bottom of the tray. The bottom of the force sensor is connected to a sensor support. The binocular vision imaging system is fixed to the top of the container and is used to photograph the objects on the tray.

[0010] Furthermore, the container has inlet and outlet ports at the bottom, and a thermometer is attached to the outer wall of the container.

[0011] Furthermore, the lifting drive mechanism has a lifting plate at its actuation output end. The lifting plate is located on the lower side of the container, the working rod is rotatably mounted on the lifting plate, and the rotation drive mechanism is mounted on the lifting plate.

[0012] Furthermore, the rotation drive mechanism includes a drive motor, a working rod gear fixed on the working rod, and a motor shaft gear fixed on the motor shaft of the drive motor that meshes with the working rod gear for transmission.

[0013] Furthermore, the force sensor is an S-shaped tension / compression sensor capable of measuring tension and compression.

[0014] Furthermore, there are at least three force sensors, which are arranged at intervals along the circumference. The sensor support is a ring disk structure surrounding the working rod, and the bottom of each force sensor is connected to the ring disk structure.

[0015] Furthermore, each force sensor has a pin structure at its top, and the bottom of the tray has a vertical pin hole for the corresponding pin structure to be inserted vertically. The pin structure has a horizontal pin hole. The bottom of the tray is equipped with a sensor locking pin that is radially guided and installed along the working rod to be inserted into the horizontal pin hole of the corresponding pin. A locking pin return spring is provided between the sensor locking pin and the tray to force the corresponding sensor locking pin to move toward the horizontal pin hole of the corresponding pin. The bottom of the tray is also equipped with a locking pin drive gear corresponding to the sensor locking pin. A winding wheel is fixed coaxially on the locking pin drive gear, and a pull rope connected to the corresponding sensor locking pin is wound on the winding wheel. The top of the working rod has a working rod rack corresponding to each locking pin drive gear on its side. The working rod has a square inner hole with its axis extending vertically. The bottom of the tray is fixed with a tray square shaft whose lower end is inserted into the square inner hole. When the working rod moves upward, the working rod rack meshes with the corresponding locking pin drive gear, and the winding wheel pulls the sensor locking pin out of the horizontal pin hole of the pin through the pull rope.

[0016] Furthermore, when the working rod moves downward, it moves to a position that is spaced apart from the bottom of the tray, with the tray supported on top of the pin structure; when the working rod moves upward, it moves to a position that contacts the bottom of the tray and disengages the tray from the top of each pin structure.

[0017] The beneficial effects of this invention are as follows: In this invention, when measuring the volume of regularly shaped objects (cubes, cuboids), the working rod moves upward, lifting the object to a high position via a tray. The working rod rotates, and the tray rotates with the object. The binocular vision measurement system takes a picture of the object, thereby obtaining its volume, ensuring efficient measurement of the object's volume. When encountering irregular objects, the tray moves downward, and a force sensor measures the weight of the object in the container without water. Then, water is added to the container, and the reading of the force sensor at this time is the sum of the object's weight and buoyancy. The volume of the object can then be accurately calculated based on the buoyancy formula.

[0018] Furthermore, when using a binocular vision force measurement system to detect the volume of regular objects, the tray needs to rotate at least one revolution with the object. Since the force sensor measures force vertically, if the force sensor remains connected to the tray during rotation, this rotational torque will damage the sensor. To avoid this problem, when the working rod moves upward, the working rod rack on the working rod meshes with the corresponding locking pin drive gear. The locking pin drive gear rotates the winding wheel, and the winding wheel, through the pull rope, causes the sensor locking pin to disengage from the transverse pin hole of the pin rod. The sensor locking pin is no longer locked to the pin rod structure, and the working rod can lift the tray from the top of the pin rod structure. At this point, the tray is detached from the force sensor, and the rotation of the tray will not affect the force sensor. When using water to utilize buoyancy to measure the volume of an object, the working rod moves downward, the tray is supported again on the pin rod structure, and the working rod continues to move downward, detaching from the tray. At this point, the force sensor can normally measure the weight of the object on the tray. Attached Figure Description

[0019] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments with reference to the accompanying drawings. In the drawings, several embodiments of this disclosure are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding portions, wherein:

[0020] Figure 1 This is a schematic diagram of the state of the working rod when it is in the low position in an embodiment of a volume force measuring device based on a force sensor and a binocular vision force measuring system in this invention;

[0021] Figure 2 This is a schematic diagram showing the state of the working rod when it is in the high position in this embodiment;

[0022] Figure 3 This is a schematic diagram showing the state of the working rod as it moves from its lower position to its higher position.

[0023] Figure 4 yes Figure 1 A schematic diagram illustrating the interaction between a binocular vision measurement system and containers / pallets;

[0024] Figure 5 yes Figure 1 Enlarged view of point A in the image;

[0025] Figure 6 yes Figure 2 Enlarged view of point B in the image;

[0026] Figure 7 yes Figure 3 Enlarged view of point C in the image;

[0027] Explanation of reference numerals in the attached diagram: 1. Binocular vision measurement system; 2. Tray; 3. Tray square shaft; 4. Container; 5. Force sensor; 6. Sensor support; 7. Working rod; 8. Working rod gear; 9. Motor shaft gear; 10. Drive motor; 11. Lifting plate; 12. Lifting cylinder; 13. Working rod rack; 14. Pin structure; 15. Pin transverse pin hole; 16. Sensor locking pin; 17. Locking pin return spring; 19. Pull rope; 20. Locking pin drive gear; 21. Tray square shaft; 22. Object; 23. Thermometer; 24. Inlet and outlet; 25. Tray vertical pin hole. Detailed Implementation

[0028] To facilitate understanding of the present invention, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0029] It should be noted that, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0030] An example of an embodiment of the volume force measuring device based on a force sensor and a binocular vision force measuring system in this invention is as follows: Figures 1-7 As shown:

[0031] It includes a container 4 for holding water, and a binocular vision imaging system 1 is fixed to the top of the container wall. The binocular vision imaging system includes two cameras arranged in parallel and corresponding image processing software. The binocular vision imaging system is existing technology, and its structure will not be described in detail here.

[0032] The bottom of the container is rotatably fitted with a working rod 7 whose rotation axis extends vertically. The working rod 7 can move vertically relative to the bottom of the container, and the working rod is sealed to the bottom of the container. The lower side of the container is provided with a rotation drive mechanism for driving the working rod to rotate and a lifting drive mechanism for driving the working rod to move vertically.

[0033] The upper end of the working rod is connected to a tray 2 for placing objects. The volume measuring device also includes a force sensor 5 for connecting to the bottom of the tray. The bottom of the force sensor 5 is connected to a sensor support 6. The binocular vision imaging system is used to photograph the object 22 on the tray 2.

[0034] In this embodiment, an inlet / outlet 24 is provided at the bottom of the side wall of the container, and a thermometer 23 is attached to the outer wall of the container.

[0035] The lifting drive mechanism includes a vertically arranged lifting cylinder 12. The piston rod of the lifting cylinder constitutes the action output end of the lifting drive mechanism. A lifting plate 11 is provided on the action output end of the lifting drive mechanism. The lifting plate is located on the lower side of the bottom of the container. The lower end of the working rod 7 is rotatably mounted on the lifting plate. The rotation drive mechanism is provided on the lifting plate.

[0036] The rotation drive mechanism includes a drive motor 10, the motor housing of the drive motor 10 is fixed on the lifting plate 11, the motor shaft of the drive motor is arranged vertically, a working rod gear 8 is fixed on the working rod, and a motor shaft gear 9 that meshes with the working rod gear is fixed on the motor shaft.

[0037] In this embodiment, there are three force sensors 5, which are spaced apart along the circumference of the working rod. Each force sensor is an S-shaped tension / compression sensor capable of measuring tension and compression. The sensor support 6 is a ring-shaped structure surrounding the working rod. The sensor support is fixed to the bottom of the container, and the bottom of each force sensor is fixed to the ring-shaped structure. The force sensors are arranged vertically, allowing for the measurement of vertical tension and compression.

[0038] Each force sensor has a pin structure 14 at the top. The bottom of the tray is provided with a vertical pin hole 25 for the corresponding pin structure to be inserted in the vertical direction. The top of the pin structure is provided with a horizontal pin hole 15. The bottom of the tray is equipped with a sensor locking pin 16 for being inserted into the horizontal pin hole of the corresponding pin in the radial direction of the working rod. The number of sensor locking pins 16 corresponds one-to-one with the number of force sensors 5.

[0039] A locking pin return spring 17 is provided between the sensor locking pin 16 and the tray 2 to force the sensor locking pin to move toward the corresponding pin rod transverse pin hole. In this embodiment, along the radial direction of the working rod, the pin rod transverse pin hole is located outside the corresponding sensor locking pin. The locking pin return spring 17 is a compression spring, so the locking pin return spring is located inside the sensor locking pin. The locking pin return spring applies an outward force to the sensor locking pin.

[0040] The bottom of the tray is also provided with a locking pin drive gear 20 corresponding to the sensor locking pin. A winding wheel is fixed coaxially on the locking pin drive gear 20. A pull rope 19 connected to the corresponding sensor locking pin is wound on the winding wheel. The pull rope 19 is connected to the end of the sensor locking pin near the tray axis. The top of the working rod is provided with a working rod rack 13 corresponding to each locking pin drive gear. In this embodiment, there are three drive gears, so there are also three working rod racks 13. The three working rod racks 13 are spaced apart along the circumference of the working rod. The working rod has a square inner hole with its axis extending in the vertical direction. The bottom of the tray is fixed with a tray square shaft 21 whose lower end is anti-rotation and is inserted into the square inner hole. The length of the tray square shaft is less than the length of the square inner hole. When the working rod moves upward, the working rod rack meshes with the corresponding locking pin drive gear, and the winding wheel pulls the sensor locking pin out of the pin rod transverse pin hole 15 through the pull rope.

[0041] When the working rod moves downward, it moves to a position that is spaced apart from the bottom of the tray, with the tray supported on the top of the pin structure. When the working rod moves upward, it moves to a position that contacts the bottom of the tray and disengages the tray from the top of each pin structure.

[0042] In this embodiment, when performing volume detection on a regular object, such as Figure 2 As shown, the working rod moves upward to its highest position. At this point, the top of the working rod contacts the bottom of the tray, and the bottom of the tray disengages from the top of the force sensor. The drive motor then rotates the tray one revolution, and the binocular vision measurement system captures an image of the object, thus obtaining its volume. The tray does not contact the force sensor during rotation, therefore it does not exert any non-vertical force on the force sensor, ensuring its lifespan.

[0043] When performing volume detection on irregular objects, the bottom of the object can be connected to the tray via a suction cup. The working rod moves downwards. First, the tray contacts the top of the force sensor; that is, the pin structure at the top of the force sensor inserts into the vertical pin hole at the bottom of the tray. As the working rod continues to move downwards, the tray, supported by the force sensor, cannot move further downwards. Therefore, the top of the working rod will detach from the bottom of the tray. Figure 1 As shown, the working rod will not affect the normal force measurement of the force sensor. When the working rod rack disengages from the locking pin drive gear, the sensor locking pin is reset and inserted into the corresponding pin rod transverse pin hole under the action of the locking pin reset spring, thus completing the connection between the tray and the force sensor.

[0044] Without water, record the object's weight in air as F0 = m0 * g (mass m0). F0 is obtained from the force sensor reading. Continue adding water until the object is completely submerged by 5cm. After the liquid level stabilizes, record the force value F1 of the force sensor and the temperature t1. (At this time, F1 may be the pressure exerted by the object on the force sensor (gravity is greater than buoyancy), or it may be the pulling force exerted by the object on the force sensor (gravity is less than buoyancy)).

[0045] The force sensor reading changes before and after liquid injection. Force analysis shows that: F1 = F0 - F 浮 ,

[0046] F 浮 =ρ 液 gV 排 (ρ) 液 The density of the liquid is expressed in kilograms per cubic meter; g is a constant, the ratio of gravity to mass, g = 9.8 N / kg, which can be taken as 10 N / kg for rough calculations; V 排 This indicates the volume of liquid displaced, expressed in cubic meters.

[0047] By referring to the table, we can find that at temperature t1, the density value ρ of the liquid is... 液 Given the gravitational acceleration g at the location of the laboratory, then V 排 = F 浮 / ρ 液 g = (F1 - F0) / ρ 液 g.

[0048] This integrated volume measurement system can quickly measure the volume of objects (initial screening), improving work efficiency. For irregularly shaped objects that may have volume errors, it uses precise temperature sensors and S-shaped tension / compression sensors to calculate the volume of liquid displaced by the object, thus obtaining the actual volume of the object. It possesses extremely high accuracy, greatly reducing measurement uncertainty, and its values ​​can be effectively traced back to national weight standards.

[0049] In the foregoing description of this specification, unless otherwise expressly specified and limited, the terms "fixed," "installed," "connected," or "linked" should be interpreted broadly. For example, the term "linked" can refer to a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; or it can refer to the internal communication of two components or the interaction between two components. Therefore, unless otherwise expressly limited in this specification, those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] Based on the above description in this specification, those skilled in the art will also understand that terms used, such as "upper," "lower," "front," "rear," "left," "right," "length," "width," "thickness," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," "center," "longitudinal," "transverse," "clockwise," or "counterclockwise," are terms indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings of this specification. They are only for the purpose of facilitating the explanation of the present invention and simplifying the description, and do not imply that the devices or elements involved must have the specific orientation, or be constructed and operated in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms should not be understood or interpreted as limitations on the present invention.

[0051] Furthermore, the terms "first" or "second," etc., used in this specification to refer to numbers or ordinal numbers are for descriptive purposes only and should not be construed as indicating, explicitly or implicitly, relative importance or specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this specification, "a plurality of" means at least two, such as two, three, or more, unless otherwise explicitly specified.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A volume measuring device based on a force sensor and a binocular vision measuring system, comprising a binocular vision imaging system, characterized in that: It also includes a container for holding water, with a working rod sealed and guided to move vertically along the bottom of the container. A rotation drive mechanism for rotating the working rod and a lifting drive mechanism for moving the working rod up and down are located on the lower side of the container. A tray for placing objects is connected to the upper end of the working rod, and a force sensor is connected to the bottom of the tray. The bottom of the force sensor is connected to a sensor support. A binocular vision imaging system is fixed to the top of the container to capture images of objects on the tray. A lifting plate is provided at the output end of the lifting drive mechanism, located on the lower side of the container. The working rod is rotatably mounted on the lifting plate, and the rotation drive mechanism is located on the lifting plate. There are at least three force sensors, arranged circumferentially. The sensor support is a ring-shaped structure surrounding the working rod, and the bottom of each force sensor is connected to the ring-shaped structure. Each force sensor has a pin structure at its top. The bottom of the tray has a vertical pin hole for the corresponding pin structure to be inserted vertically. The pin structure has a horizontal pin hole. A sensor locking pin is mounted on the bottom of the tray, which moves radially along the working rod, for inserting into the horizontal pin hole of the corresponding pin. A locking pin return spring is provided between the sensor locking pin and the tray to force the corresponding sensor locking pin to move toward the horizontal pin hole. The bottom of the tray also has a locking pin drive gear corresponding to the sensor locking pin. A winding wheel is coaxially fixed on the locking pin drive gear, and a pull rope connected to the corresponding sensor locking pin is wound on the winding wheel. The top of the working rod has a working rod rack corresponding to each locking pin drive gear. The working rod has a square inner hole with its axis extending vertically. A tray square shaft with its lower end anti-rotation inserted into the square inner hole is fixed on the bottom of the tray. When the working rod moves upward, the working rod rack meshes with the corresponding locking pin drive gear, and the winding wheel, through the pull rope, pulls the sensor locking pin out of the horizontal pin hole. When the working rod moves downward, it moves to a position that is spaced apart from the bottom of the tray, with the tray supported on the top of the pin structure. When the working rod moves upward, it moves to a position that contacts the bottom of the tray and detaches the tray from the top of each pin structure.

2. The volume measuring device of claim 1, wherein: The container has an inlet and outlet at the bottom, and a thermometer is attached to the outer wall of the container.

3. The volume measuring device according to claim 1, characterized in that: The rotation drive mechanism includes a drive motor, a working rod gear fixed on the working rod, and a motor shaft gear fixed on the motor shaft of the drive motor that meshes with the working rod gear for transmission.

4. The volume measuring device of claim 1, wherein: The force sensor is an S-shaped tension and compression sensor capable of measuring tension and compression.

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