An automatic calibration device and method for a six-dimensional force sensor

Abstract

This invention relates to the field of sensor calibration technology, specifically to an automatic calibration device and method for a six-dimensional force sensor. The calibration device includes a loading fixture, at least three guiding devices, at least three loading devices, and a control system. The loading fixture is connected to the loading end of the six-dimensional force sensor to be calibrated. The guiding device includes a rotating body, the horizontal plane containing the central axis of the rotating body is aligned with the horizontal plane containing the center of the loading fixture, and the rotating body is provided with pulleys in two perpendicular directions. The loading device includes an automatic loading mechanism and a flexible loading element, one end of which is connected to the automatic loading mechanism, and the other end, after passing around the pulleys on the rotating body, is connected to an extension of the loading fixture. The control system is used to calculate the calibration angle and calibration load, control the rotating body to rotate to the calibration angle, and control the automatic loading mechanism to apply the calibration load to the loading fixture. This invention offers high calibration accuracy, high efficiency, convenient operation, and strong structural versatility.

Description

Technical Field

[0001] This invention relates to the field of sensor calibration technology, specifically to an automatic calibration device and method for a six-dimensional force sensor. Background Technology

[0002] Six-dimensional force sensors are widely used in robot control, materials testing, biomechanical research, and industrial automation to accurately measure force and torque components in three-dimensional space. To ensure the accuracy of six-dimensional force sensors, precise calibration is typically required. Existing technologies for six-dimensional force sensor calibration devices mainly include the following typical schemes:

[0003] Static weight-based joint calibration device: For example, Chinese patent application No. 202410742079.9 discloses a static weight-based six-dimensional force sensor joint calibration device and its calibration method. This device uses a structure consisting of a loading cap, steel wire rope, and loading disk. By changing the calibration load on the loading disk, it simulates the actual use scenario of the sensor, thereby achieving the loading and calibration of multi-dimensional forces or torques. The disadvantages of this method are that the device structure is relatively complex, the operation is complex, the time cost of suspending the weights is high due to the need for manual operation, and the applied force and torque depend on the weight specifications, making it impossible to apply arbitrary forces and torques.

[0004] Electric cylinder closed-loop loading device: Chinese patent application No. 201410610402.3 discloses a six-dimensional force sensor calibration device, which uses six electric cylinders with single-dimensional force sensors to construct three sets of orthogonal loading structures, and combines closed-loop force feedback control to achieve high-precision six-dimensional force loading. Although this system has the advantages of high automation and excellent loading accuracy, it suffers from complex structure, high manufacturing cost, cumbersome debugging and maintenance process, and can only be adapted to specific models of fixed six-dimensional force sensors, making it incompatible with many different specifications of sensors on the market.

[0005] Force measuring beam structure calibration device: Chinese patent application No. 202410879664.3 discloses a six-dimensional force sensor calibration device and calibration method, which uses a force measuring beam and guide part in conjunction with standard weights and pull ropes to achieve six-dimensional force calibration. In this device, it is difficult to accurately control the included angle of the pull rope, and the deviation of the pull rope angle may reduce the calibration accuracy. At the same time, frequent replacement or adjustment of the pull rope direction will increase the error and time cost in the calibration process.

[0006] In summary, existing technologies suffer from problems such as complex structure, insufficient adaptability, and cumbersome operation, leading to difficulties in guaranteeing calibration accuracy. Therefore, there is an urgent need for a six-dimensional force sensor calibration device and method that features high calibration accuracy, convenient operation, strong adaptability, and simple structure to improve calibration efficiency and precision. Summary of the Invention

[0007] The purpose of this invention is to solve the problems of low calibration accuracy, cumbersome operation, and poor adaptability, and to propose an automatic calibration device and method for a six-dimensional force sensor. It has advantages such as high calibration accuracy, high efficiency, convenient operation, and strong structural versatility, and can realize individual and combined loading of each force / torque component, thereby quickly and accurately completing the full-dimensional calibration of the six-dimensional force sensor.

[0008] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0009] In the first aspect, an automatic calibration device for a six-dimensional force sensor is provided, including a horizontal calibration base plate, a loading fixture, at least three guiding devices, at least three loading devices, and a control system;

[0010] The loading fixture is connected to the loading end of the six-dimensional force sensor to be calibrated. The loading fixture has at least three outwardly extending extension sections. The number of the guiding device and the loading device is the same as the number of extension sections.

[0011] The guide device is mounted on a horizontal calibration base plate. The guide device includes a rotating body, on which are arranged pulley groups in two vertical directions. Each pulley group includes at least two pulleys.

[0012] The loading device is mounted on the horizontal calibration base plate. The loading device includes an automatic loading mechanism and a flexible loading component. One end of the flexible loading component is connected to the automatic loading mechanism, and the other end passes around a pulley on the rotating body and is connected to the extension of the loading fixture.

[0013] The control system is electrically connected to the six-dimensional force sensor, the guide device and the loading device. It is used to calculate a calibration data set including the calibration angle and the calibration load according to the preset calibration data set, control the rotating body to rotate to the calibration angle, and control the automatic loading mechanism to apply the calibration load to the loading fixture through the flexible loading component.

[0014] Furthermore, it also includes a lifting device, which is set on a horizontal calibration base plate, and the six-dimensional force sensor to be calibrated is placed on the lifting device.

[0015] Furthermore, the guiding device also includes an automatic rotating mechanism and a transmission device. The transmission device includes a worm and a worm wheel. The automatic rotating mechanism is connected to the worm, the worm is connected to the worm wheel, and the worm wheel is connected to the rotating body.

[0016] Furthermore, the guiding device also includes a positioning detection mechanism for detecting the rotation angle of the rotating body.

[0017] Furthermore, the positioning detection mechanism includes an infrared emitting module, a lens, and an infrared receiving module. The infrared emitting module and the infrared receiving module are fixed on the rotating body and are used to emit infrared rays to the lens and receive infrared rays reflected by the lens.

[0018] Furthermore, the loading device also includes a tension sensor, which is connected in series in the loading path of the flexible loading member.

[0019] Furthermore, the automatic loading mechanism includes a first automatic loading mechanism and a second automatic loading mechanism. The first automatic loading mechanism and the second automatic loading mechanism apply calibrated loads in two directions by means of flexible loading members that pass through pulley groups in the two directions respectively.

[0020] Secondly, an automatic calibration method for a six-dimensional force sensor is provided, which uses the aforementioned automatic calibration device for the six-dimensional force sensor and includes the following steps:

[0021] Adjust the height of the six-dimensional force sensor to be calibrated so that the horizontal plane containing the central axis of the rotating body is aligned with the central horizontal plane of the loading fixture;

[0022] Input one or more sets of target six-dimensional force and torque setting calibration data;

[0023] The control system calculates one or more sets of calibration data based on the set calibration data set. The number of calibration data sets is consistent with the number of set calibration data sets. The calibration data sets include the calibration angle required for the rotation of the rotating body of each guide device, and the calibration load applied to each flexible loading element.

[0024] The control system sends control commands to each group, controlling the rotating body of each guide device to rotate to the corresponding calibrated angle, and controlling each loading device to apply the corresponding calibrated load to the loading fixture.

[0025] After each set of calibration data is loaded, it is determined whether there are any unloaded calibration data sets. If so, the next set of calibration data sets is loaded; otherwise, the loading process is terminated.

[0026] Furthermore, the control system calculates one or more sets of calibration data based on a set of calibration data, including:

[0027] The measurement space of the six-dimensional force sensor is divided into a three-dimensional force space and a three-dimensional torque space;

[0028] The three-dimensional force space and three-dimensional torque space are uniformly divided from multiple directions and multiple vectors. The multiple directions refer to the horizontal plane being divided into several directional regions at equal angles according to the number of extension segments, with the installation center of the six-dimensional force sensor as the reference, in the top view direction of the calibration device. The multiple vectors refer to multiple force points or force directions implemented in different directions.

[0029] A transformation matrix is ​​generated based on the number of orientations of the calibration device. The calibration load in each loading vector direction is calculated based on the transformation matrix. The calibration angle required for the rotating body to rotate is calculated based on the angle analysis formula.

[0030] Furthermore, controlling the rotating body of each guide device to rotate to the corresponding calibrated angle includes:

[0031] The automatic rotation mechanism in the control guide device drives the transmission device to adjust the rotating body to the calibrated angle;

[0032] The positioning and detection mechanism uses a lens to reflect infrared light. When the rotating body reaches the calibrated angle, the positioning and detection mechanism sends a signal, and the control system controls the rotating body to stop rotating.

[0033] Compared with existing technologies, this invention has the following significant advantages: By introducing a flexible loading structure and a high-precision guiding control mechanism, the mechanical structure of the six-dimensional force sensor calibration device is simplified, and the calibration process is optimized. It enables one-time installation, one-button start, and automatic completion of the entire calibration process, significantly improving automation and operational efficiency. This invention supports the system automatically generating loading paths based on set parameters, applying precise and controllable loading forces and torques to the six-dimensional force sensor in any spatial direction, improving calibration coverage and data accuracy. The loading device combines a high-precision tension sensor with closed-loop control to achieve dynamic error correction and high-response force control, ensuring the stability and consistency of the loading process. Compared to traditional rigid loading structures, which suffer from complex layout, difficult adjustment, and poor impact resistance, the rope-pulley flexible transmission structure offers excellent impact buffering capacity and layout flexibility, reducing device size and making it suitable for multi-directional, multi-channel loading scenarios. This invention, through a multi-hole connection structure with an adjustable lifting mechanism and a sensor top connecting plate, adapts to six-dimensional force sensors of different thicknesses and interface types, supports rapid assembly by replacing connecting components, and possesses good structural versatility and engineering adaptability. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure of the present invention in a side view.

[0035] Figure 2 This is a first-view structural diagram of the loading device and guiding device in this invention;

[0036] Figure 3 This is a schematic diagram of the structure of the sensor top connecting plate in this invention;

[0037] Figure 4 This is a schematic diagram of the lifting device and sensor fixing device in this invention;

[0038] Figure 5 This is a second-view structural diagram of the loading device and guiding device in this invention.

[0039] Explanation of reference numerals in the attached drawings: 1. Horizontal calibration base plate; 2. Lifting device; 21. Sensor bottom fixing plate; 22. Lifting mechanism; 3. Loading fixture; 31. Sensor top connecting plate; 311. Extension section; 32. Loading part end cover; 33. Six-dimensional force sensor; 4. Guide device; 41. Transmission device; 411. Worm gear; 412. Worm; 42. Automatic rotation mechanism; 421. Coupling; 422. Rotation mechanism base; 43. Rotating body; 431. First pulley; 432. Second pulley; 4 33. Third pulley; 434. Fourth pulley; 435. Rotating shaft; 44. Positioning detection mechanism; 441. Lens; 45. End cap; 5. Loading device; 51. First automatic loading mechanism; 511. First winding wheel; 512. First wire rope; 513. First tension sensor; 514. First loading mechanism base; 52. Second automatic loading mechanism; 521. Second winding wheel; 522. Second wire rope; 523. Second tension sensor; 524. Second loading mechanism base; 6. Control system. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] To achieve rapid and accurate calibration of the force components of a six-dimensional force sensor 33 in various spatial directions, improve calibration accuracy and efficiency, and enhance the applicability and flexibility of the calibration system, this invention provides an automatic calibration device and calibration method for a six-dimensional force sensor.

[0042] Example 1:

[0043] An automatic calibration device for a six-dimensional force sensor is provided, such as Figures 1-5 As shown, it includes: a horizontal calibration base plate 1, a lifting device 2, a loading fixture 3, four guiding devices 4, four loading devices 5, and a control system 6.

[0044] The horizontal calibration base plate 1 is fixedly connected to the integral support frame constructed of aluminum profiles by screws. The lifting device 2 is fixedly installed on the horizontal calibration base plate 1, and the lifting device 2 includes a sensor bottom fixing plate 21 and a lifting mechanism 22. The lower end of the six-dimensional force sensor 33 to be calibrated is connected to the top of the lifting mechanism 22 through the sensor bottom fixing plate 21 and kept on the same vertical central axis to realize the vertical position adjustment function.

[0045] The loading fixture 3 is connected to the loading end (top cover) of the six-dimensional force sensor 33 to be calibrated, and is used to transmit external loading force to the body of the six-dimensional force sensor 33. A sensor top connecting plate 31 is provided on the top of the loading fixture 3. This sensor top connecting plate 31 extends outward to form four extension segments 311, which are evenly distributed in the circumferential direction of the six-dimensional force sensor 33. A loading end cap 32 is installed at the end of each extension segment 311. A bearing assembly is provided inside the loading end cap 32 to ensure smooth rotation or angle adjustment during the loading process.

[0046] Guide devices 4 and loading devices 5, in the same number as the four extension sections 311 mentioned above, are fixed on the horizontal calibration base plate 1 and correspond one-to-one with the extension sections 311. The guide device 4 includes a transmission device 41, an automatic rotation mechanism 42, a rotating body 43, a positioning detection mechanism 44, and an end cap 45. The transmission device 41 includes a worm gear 412 and a worm wheel 411. The automatic rotation mechanism 42 is connected to the worm gear 412, which is drively connected to the worm wheel 411. The worm wheel 411 is connected to the rotating body 43 via a rotating shaft 435. The horizontal plane containing the central axis of the rotating body 43 is aligned with the central horizontal plane of the loading fixture 3. The central horizontal plane of the loading fixture is the horizontal plane passing through the center point of the extension section. The rotating body 43 is equipped with pulley sets in two vertical directions, each pulley set including two pulleys. The guide device 4 responds to the calibration angle command provided by the control system 6 and drives the internal rotating body 43 to rotate. The positioning detection mechanism 44 monitors it in real time. When the rotating body 43 rotates to the calibration angle, the control system 6 sends a signal to drive the automatic rotation mechanism 42 (stepper motor) to stop running, thereby ensuring that the rotating body 43 accurately reaches the calibration angle. Then, based on the received calibration force data, the loading device 5 drives the loading device 5 to apply a pulling force of a specified direction and magnitude to the loading end cap 32 on the extension section 311, thereby realizing the composite loading of the six-dimensional force sensor 33.

[0047] In this embodiment, the positioning detection mechanism 44 includes an infrared emitting module, four lenses 441, and an infrared receiving module. The infrared emitting module and the infrared receiving module are fixed on the rotating body 43. The four lenses 441 are attached to end caps 45 on the base supporting the rotating body 43. The infrared emitting module emits infrared light to the lenses 441, and the infrared receiving module receives the infrared light reflected by the lenses 441. The position of the lenses 441 can be adjusted according to the installation position of the infrared receiving module, so that the signal strength is maximized when the infrared light emitted by the infrared emitting module is reflected by the lenses 441 and aligned with the infrared receiving module.

[0048] The loading device 5 includes an automatic loading mechanism, flexible loading elements (a first wire rope 512 and a second wire rope 522), and tension sensors (a first tension sensor 513 and a second tension sensor 523). One end of the flexible loading element is connected to the automatic loading mechanism, and the other end, after passing through a pulley on the rotating body 43, is connected to the loading end cap 32 on the extension section 311 of the loading fixture 3. The tension sensors are connected in series in the loading path of the flexible loading element. The automatic loading mechanism includes a first automatic loading mechanism 51 and a second automatic loading mechanism 52. The first automatic loading mechanism 51 is equipped with a first winding wheel 511, and the second automatic loading mechanism 52 is equipped with a second winding wheel 521, for winding the first wire rope 512 and the second wire rope 522, respectively. The first automatic loading mechanism 51 and the second automatic loading mechanism 52 apply calibrated loads in two directions by passing through pulley sets in two directions via the flexible loading element. The first pulley 431 and the second pulley 432 form a pulley group in one direction, while the third pulley 433 and the fourth pulley 434 form a pulley group in another direction.

[0049] The control system 6 establishes communication connections with the six-dimensional force sensor 33 to be calibrated, the positioning detection mechanism 44, each automatic rotation mechanism 42, and each automatic loading mechanism. The control system 6 is used to calculate a calibration data set containing the calibration angle of the rotating body 43 and the load values ​​of each loading vector direction according to the preset calibration data set, control the rotating body 43 to rotate to the calibration angle, and control the automatic loading mechanism to apply the calibration load to the loading fixture 3 through the flexible loading member.

[0050] In this embodiment, after a single setup, the control system 6 can control all the guiding devices 4 and loading devices 5 to communicate and perform precise calibration of the six-dimensional force sensor. This effectively reduces operational complexity and improves calibration accuracy. Various communication methods are available, such as using the Modbus protocol, or other protocols. The appropriate method can be selected based on the specific needs of those skilled in the art. The specific structure and working principle of the control system 6 are well-known to those skilled in the art and will not be described in detail here.

[0051] The horizontal calibration base plate 1 can be square, or it can be designed as circular or other polygonal structures according to different installation requirements, and has a certain degree of shape adjustability. In order to reduce the overall space occupied by the device and optimize the installation layout, this embodiment preferably adopts a compact horizontal calibration base plate 1, and the six-dimensional force sensor 33 is installed on the upper end of the sensor bottom fixing plate 21.

[0052] To ensure the vertical positioning accuracy of the six-dimensional force sensor 33, positioning holes are provided on the upper and lower surfaces of the sensor bottom fixing plate 21, respectively, so that the sensor bottom fixing plate 21 can be accurately connected to the six-dimensional force sensor 33 and the lifting mechanism 22, thereby ensuring that the six-dimensional force sensor 33, the sensor bottom fixing plate 21 and the lifting mechanism 22 are installed collinearly and kept on the same vertical central axis.

[0053] Based on the existing positioning holes on the upper surface of the six-dimensional force sensor 33, matching positioning holes can be provided on the top connecting plate 31 of the sensor. Precise positioning is achieved through pin engagement, thus ensuring the coaxial installation relationship between the six-dimensional force sensor 33 and the top connecting plate 31. This design effectively ensures the accuracy of the installation position and the consistency of the installation direction of the six-dimensional force sensor 33 in the calibration device, contributing to improved accuracy and data consistency in subsequent loading calibration.

[0054] To ensure the precise installation of the automatic rotation mechanism 42 in the guide device 4 and the loading device 5 with the first automatic loading mechanism 51 and the second automatic loading mechanism 52, preferably, mounting holes for positioning are provided in the corresponding mounting areas of the horizontal calibration base plate 1. These mounting holes cooperate with the corresponding bases (including the first loading mechanism base 514 of the first automatic loading mechanism 51, the second loading mechanism base 524 of the second automatic loading mechanism 52, and the rotation mechanism base 422 of the automatic rotation mechanism 42) to define the installation direction and position of the device, thereby improving the assembly accuracy and consistency of the overall system.

[0055] When installing the first pulley 431 and the fourth pulley 434, it should be ensured that after the first wire rope 512 and the second wire rope 522 are connected to the first tension sensor 513 and the second tension sensor 523, they can form effective tangential contact with the first pulley 431 and the fourth pulley 434, and the central axis of the cross section of the wire rope can intersect with the axis of the through hole provided on the side of the loading end cover 32, thereby ensuring the accuracy of the loading direction and the efficiency of force transmission.

[0056] When installing the positioning detection mechanism 44, the four lenses 441 attached to the circumference of the end cover 45 should correspond to the positions of the infrared emitting module and the infrared receiving module when the rotating body 43 drives the infrared emitting module and the infrared receiving module to rotate together, so as to ensure the accuracy of the angle control of the rotating body 43.

[0057] To avoid spatial interference between the first wire rope 512 and the second wire rope 522 during arrangement, the positions of the second pulley 432 and the third pulley 433 need to be optimized and adjusted to ensure that they operate without interference within the range of motion angles (-90° to 180°) of the rotating body 43. Therefore, in practical implementation, the positions of the shaft holes used to fix the pulleys in each branch of the rotating body 43 need to be specifically adjusted based on the pulley's external dimensions and arrangement to adapt to different loading paths and motion space requirements, thereby achieving a reasonable arrangement and reliable operation of the system structure.

[0058] Example 2:

[0059] An automatic calibration method for a six-dimensional force sensor is provided, including the following steps:

[0060] Step 1: The control system 6 detects whether the six-dimensional force sensor automatic calibration device is in its initial state. The initial state means that the two "branches" of the rotating body are vertical and horizontal respectively, while the lifting device is in the middle of its extension / retraction range. If it is not in the initial state, it automatically performs a return-to-center operation. After initial return-to-center, one or more sets of calibration data are input and stored in the system.

[0061] Step 2: Based on the external dimensions (especially the thickness) of the six-dimensional force sensor 33 to be calibrated, the control system 6 sends a height adjustment command to drive the lifting mechanism 22 so that the center horizontal plane of the sensor top connecting plate 31 is on the same horizontal plane as the central axis of the rotating body 43, thereby ensuring the spatial consistency of the loading direction.

[0062] Step 3: Establish a communication connection between the control system 6 and the six-dimensional force sensor 33 to be calibrated, so that the six-dimensional force sensor 33 and the control system 6 can interact with each other and realize the effective transmission of loading control commands and sensor feedback data.

[0063] Step 4: The control system 6 calculates and generates one or more sets of calibration data for calibration based on the input set of calibration data. The number of calibration data sets is the same as the number of set calibration data sets, including the calibration angle required for the rotating body 43 to rotate and the calibration load in each loading vector direction (the calibration force value required to be applied by each automatic loading mechanism).

[0064] Step 5: The control system 6 sends control commands according to one or more sets of calibration data generated in the previous step.

[0065] Step 6: After each set of loading is completed, the control system 6 determines whether there is a next set of calibration data. If there is, the next round of control commands is executed, and the process from Step 5 to Step 6 is repeated; if all calibration data has been executed, the loading process is terminated, and all devices are returned to their initial state.

[0066] The process of generating multiple sets of data in Step 4 is as follows:

[0067] Step 4.1: Divide the measurement space of the six-dimensional force sensor 33 into a three-dimensional force space and a three-dimensional torque space;

[0068] Step 4.2: Use multiple orientations and multiple vectors to uniformly divide the measurement space, but it is necessary to modify matrix B and matrix F in the following calculation process;

[0069] Step 4.3: Based on the calibration data set given and stored in Step 2, use the formula to calculate the magnitude of the force required for the loading vector direction at each orientation and the calibration angle of the rotating body 43. Note that the calibration data set in Step 2 refers to the input... The six-dimensional array can be used to determine the collection of these data through program development.

[0070] "Multi-directional" refers to dividing the horizontal plane into several directional regions at predetermined angles, using the installation center of the six-dimensional force sensor 33 as a reference, from the top view of the calibration device. For example, a four-directional division corresponds to the four directions of east, south, west, and north, with an included angle of 90°. A three-directional division corresponds to three directions, with an included angle of 120°. This invention can also be extended to six-directional, eight-directional, etc., to meet different loading uniformity and distribution requirements.

[0071] In each azimuth direction, one or more loading vectors can be set, acting on different positions and directions of the six-dimensional force sensor 33 respectively. "Multiple vectors" refers to multiple force points or force directions applied in different azimuth directions. By reasonably arranging the loading points and loading directions in each direction, the three force components of the six-dimensional force sensor 33 ( ) and three torque components ( This generates a sufficient response, forming a structurally complete loading assembly.

[0072] In Step 5, control commands are sent to groups as follows:

[0073] Step 5.1: Control the automatic rotation mechanism 42 in the guide device 4 to drive the transmission device 41, so that the rotating body 43 is adjusted to the calibrated angle;

[0074] Step 5.2: The positioning detection mechanism 44 will reflect infrared light through the lens 441. Once the rotating body 43 reaches the calibrated angle, the positioning detection mechanism 44 will send a feedback signal to the control system 6 to stop the stepper motor that controls the rotation of the rotating body 43, so as to ensure that the rotating body 43 stops accurately at the calibrated angle position.

[0075] Step 5.3: The two automatic loading mechanisms in the synchronous control loading device 5 adjust their rotation angles according to the feedback signal from the tension sensor to accurately match the target loading force.

[0076] For each extension 311 on the sensor top connecting plate 31, its loading end cap 32 can apply tensile force in two mutually perpendicular directions, thereby generating two sets of force vectors on each loading end cap 32. In a preferred embodiment, a total of four loading end caps 32 are provided, thus forming a tensile force distribution in eight directions. After the above eight tensile force vectors are combined, a resultant force and torque in any direction can be constructed in space, and effectively transmitted to the six-dimensional force sensor 33 through the sensor top connecting plate 31. The six-dimensional force sensor 33 can fully sense and respond to the composite force applied by the loading fixture 3 in each direction in its own coordinate system, thereby establishing a load mapping relationship. The expressions for the two loads generated in each orientation and the angle of rotation required for each orientation rotating body 43 are as follows:

[0077]

[0078]

[0079]

[0080]

[0081]

[0082] Converted to matrix representation, it is as follows:

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091] Here, it is assumed that a Cartesian coordinate system is established with the center of the sensor top connecting plate 31 as the origin. Indicates the angle between each direction. Indicates the first one direction As the reference orientation, it is located on the negative x-axis. This indicates the vertical distance from the loading position to the central axis of the six-dimensional force sensor 33. Indicates the first The vertical distance from the loading position in each direction to the central axis of the six-dimensional force sensor 33. express The unit vector is used to calculate the lever arm length, and thus the torque. express Components on the x, y, and z axes, Indicates the first Horizontal component force in each direction unit vector, Indicates the first Two component forces in each direction express Components in the global x, y, and z directions, express The vector sum of the components in the x, y, and z directions in a Cartesian coordinate system. This represents the force component along the x-axis. This represents the force component along the y-axis. This represents the force component along the z-axis. express The vector sum of the moments produced about the x, y, and z axes in a Cartesian coordinate system. Represents the torque component in the x-axis direction. This represents the torque component along the y-axis. This represents the torque component along the z-axis. and This represents the general solution matrix and the optimal matrix for the forces in the two loading vector directions of the body of revolution 43 at each position. The optimal matrix is ​​obtained by using the minimum L2 norm in all cases that satisfy the condition. In the general solution matrix, there is To find the most reasonable solution That is, to ensure that the two force values ​​in each direction are not excessively large and are relatively evenly distributed. It sets the calibration data set, representing the calibration force data of the forces and torques that actually need to be applied in the system. It is a transformation matrix, representing the set calibration data set. Transform into the optimal matrix The transformation relationship, the columns of matrix N constitute The zero-space basis; For any vector, This represents a multi-faceted index within the system. Indicates the first The calibrated angle of rotation of the 43 rotating bodies in each direction. Indicates the number of directions.

[0092] This example uses the four directions to illustrate that... And it can be calculated using a formula. hour It represents the orientation corresponding to the negative x-axis in the plane xoy; hour It indicates the orientation corresponding to the negative y-axis in the plane xoy; hour It represents the orientation corresponding to the positive x-axis in the plane xoy; hour It represents the orientation corresponding to the positive y-axis in the plane xoy. The 1 in the figure represents the direction of the vertical loading vector. The 2 in the figure represents the direction of the horizontal loading vector. to These represent the calibration angles required for the four rotating bodies 43 to rotate. to These represent the forces required to be applied in the two loading vector directions of the rotating body 43 in the four directions.

[0093] During the calibration process, the control system 6 uses the receipt of feedback data from the tension sensor and the six-dimensional force sensor 33 as the basis for determining whether each calibration loading is successfully completed. If communication interruptions or data loss occur during multiple calibration rounds, and the cumulative number of communication failures exceeds the set fault tolerance threshold, the system automatically determines it as a communication anomaly and triggers an anomaly handling process or issues a fault warning signal.

[0094] The loading fixture 3 of this invention can be configured to include at least three extension segments 311 according to actual needs. The number of these extension segments determines the number of guide devices 4 and loading devices 5 required, and a one-to-one correspondence must be maintained. That is, the number of guide devices 4 and loading devices 5 should be equal to the number of extension segments 311 to ensure the symmetry of the loading path and the stability of the force synthesis. This embodiment uses a four-directional and eight-load vector arrangement as an example. If other types of multi-directional arrangements are changed, under this structure, the sensor top connecting plate 31 is provided with a corresponding number of extension segments 311 and corresponding guide devices 4 and loading devices 5. To adapt to this structural change, a transformation matrix is ​​used to calculate the force relationship between the loading force and the loading vector direction. Adjustments are needed to ensure the accuracy of the force distribution logic and calibration algorithm.

[0095] It is worth noting that in a multi-directional, multi-load vector structure, theoretically, multiple load vectors can share a single automatic loading mechanism to achieve force loading in the direction of the load vectors. For example, one loading mechanism controls one load vector to bear the combined force of two load vectors, resulting in a four-directional, four-load vector arrangement. This reduces the number of execution units and eliminates the need for the positioning and detection mechanism 44, thus simplifying the structure. However, this approach has the following significant drawbacks in engineering practice: Since the combined loading force needs to be controlled by a single mechanism simultaneously in two directions, achieving independent force control in each direction during the application of the calibration load requires adjusting the rotation angle of the rotating body 43. Errors in the combined angle affect the accuracy of the final loading direction. If a slight deviation occurs in the angle, the load in one direction will deviate, and the force control in the other direction will also be simultaneously disturbed, leading to severe coupling in the loading process, resulting in inaccurate loading direction, and consequently affecting the calibration consistency and overall accuracy of the sensor. However, if the accuracy requirement is not high, it is also acceptable to use a single loading vector as an equivalent loading vector to multiple loading vectors. Alternatively, if precise control of the rotation angle of the rotating body 43 can be achieved, this scheme can also achieve very high calibration accuracy.

[0096] Preferably, this embodiment adopts a four-directional and eight-load vector arrangement scheme with dual automatic loading mechanisms, that is, each loading vector direction corresponds to an independent automatic loading mechanism, thereby ensuring that the loading force in the two loading vector directions in each directional position can be independently controlled and adjusted in real time closed loop, fully guaranteeing the high precision, stability and repeatability of the calibration process.

[0097] This invention employs a flexible loading system composed of a steel wire rope and pulleys, combined with a high-precision automatic rotation mechanism 42 and a transmission device 41 to achieve automatic adjustment of the loading direction, and real-time force control is achieved through a control system 6. During the loading process, the control system 6 sends control commands to the automatic loading mechanism and the corresponding tension sensor, and receives feedback signals in real time to complete closed-loop control of the loading force. In this embodiment, the calibration device uses a steel wire rope transmission structure to achieve tension loading, which has the characteristics of fast response speed, wide adjustable range, and lightweight structure, and is suitable for multi-directional, multi-channel composite loading scenarios.

[0098] After the installation and positioning of the six-dimensional force sensor 33 and its calibration device are completed, the calibration procedure can be started. During the calibration process, the control system 6 sends a control command containing the calibration angle to the guide device 4 according to the preset calibration strategy. The automatic rotation mechanism 42 responds to the control command, drives the transmission device 41 through the coupling 421, and then drives the rotating body 43 to rotate. The positioning detection mechanism 44 monitors in real time. When the calibration angle is reached, the positioning detection mechanism 44 receives the infrared light reflected by the lens 441, and sends a signal to the control system 6, which then sends a signal to drive the automatic rotation mechanism 42 to stop, thereby ensuring that the rotating body 43 reaches the calibration angle. The rotation angle of the rotating body 43 can cover the range of -90° to 180°, and can be loaded by two loading vectors set in each orientation to achieve composite loading in any direction in space. Subsequently, the loading device 5 drives the first automatic loading mechanism 51 and the second automatic loading mechanism 52 to rotate according to the received loading force signal. The first winding wheel 511 and the second winding wheel 521 in the first automatic loading mechanism 51 and the second automatic loading mechanism 52 respectively wind up the steel wire rope 512 and 522, thereby applying tension at the fixed point on the side of the loading part end cap 32 connected to the extension section 311. The tension sensors 513 and 523 detect the actual tension in the steel wire rope in real time and feed it back to the control system 6. The control system 6 judges the loading error based on the feedback information and sends angle correction commands to the first automatic loading mechanism 51 and the second automatic loading mechanism 52 in real time until each loading vector direction reaches the predetermined calibration force, thereby realizing closed-loop control and precise application of the loading force. After the calibration program is started, the entire calibration process will automatically execute multiple loading-acquisition-calibration steps according to the set loading path and force value parameters, realizing multiple rounds of high-precision data acquisition and error correction. All operations can be completed automatically with a single click, greatly improving the calibration efficiency and accuracy of the six-dimensional force sensor 33.

[0099] It should be understood that the specific structures and working principles of the lifting mechanism 22, transmission device 41, automatic rotation mechanism 42, positioning detection mechanism 44, first tension sensor 513, and second tension sensor 523 in this embodiment are well known to those skilled in the art. The lifting mechanism 22 can employ an electric cylinder system, a pneumatic cylinder system, a mechanical guide rail, an electric slide, a lead screw-servo combination module, etc. The transmission device 41, the first automatic loading mechanism 51, and the second automatic loading mechanism 52 can be selected from stepper motors, rotary electric cylinders, rotary pneumatic cylinders, and rotary hydraulic cylinders, etc. The positioning detection mechanism 44 can employ infrared sensors, capacitive proximity sensors, Hall effect sensors, etc. The first tension sensor 513 and the second tension sensor 523 can be selected from various structural forms such as high-precision S-type tension sensors, column-type tension sensors, or capacitive tension sensors.

[0100] Regarding the lifting mechanism 22, in addition to electric cylinder systems, pneumatic cylinder systems, and mechanical guide rails, electric slides, lead screw-servo combination modules, or leveling platforms based on differential hydraulic control can also be used to achieve precise displacement adjustment and automatic alignment. For experimental platforms that require high-frequency, multiple installation and adjustment, a quick-plug positioning device combined with a self-locking limit structure can also be used to improve the initial positioning and height adjustment efficiency and reproduction accuracy of the six-dimensional force sensor 33.

[0101] The internal transmission structure of the transmission device 41 is not limited to the worm gear 411 and worm 412 transmission. It can also be a synchronous belt pulley transmission mechanism, a planetary reducer transmission system or other structural methods that can achieve deceleration and transmission functions.

[0102] In practical applications, for scenarios requiring extremely high precision in loading direction and force control (such as testing precision aerospace components), the first automatic loading mechanism 51 and the second automatic loading mechanism 52 in the loading device 5 are preferably driven by servo motors because servo motors can provide high-precision position and speed control. For cost-sensitive scenarios that allow for a certain margin of accuracy (such as rapid calibration in general industrial settings), stepper motors, rotary electric cylinders, rotary pneumatic cylinders, and rotary hydraulic cylinders can be selected. These solutions have significant advantages in terms of cost and control complexity. The automatic rotation mechanism 42 in the guiding device 4 should preferably be driven by a stepper motor, and the addition of an infrared sensor can also obtain highly accurate angular positioning of the rotating body 43.

[0103] The sensors in the positioning detection mechanism 44 are not limited to infrared sensors, but can also be capacitive proximity sensors, Hall effect sensors, etc. As long as they can achieve the purpose of detecting a fixed position, they should be considered as optional embodiments of the present invention.

[0104] The type of tension sensor applicable to this invention is not limited to one. Depending on the different requirements for loading accuracy and dynamic response, various structural forms such as high-precision S-type tension sensor, column-type tension sensor or capacity-type tension sensor can be selected to meet the different requirements of the system for loading accuracy and dynamic response. Among them, the S-type sensor is more suitable for high-precision calibration, while column-type and capacity-type sensors are suitable for environments with compact structures or limited installation space.

[0105] Regarding loading control methods, in addition to closed-loop force control systems, open-loop control algorithms based on position feedforward and compensation can be used, or intelligent control strategies such as integrated model predictive control (MPC), adaptive control, and fuzzy control can be employed as alternatives to adapt to different control accuracy and system structural complexity requirements. For large-scale application scenarios, a cloud-based remote calibration and collaboration system can be introduced to transfer control decisions from local to centralized management, enabling cross-device data sharing and parameter synchronization.

[0106] At the data acquisition and control level, in addition to conventional control systems, it can be replaced by embedded systems (such as STM32, FPGA control units), industrial-grade PLC control systems, ROS system integration platforms, and can even integrate advanced control interfaces based on LabVIEW or MATLAB to realize an automated process of data acquisition, analysis, visualization and feedback closed loop.

[0107] In this embodiment, the lifting mechanism 22 uses an electric cylinder, the first automatic loading mechanism 51 and the second automatic loading mechanism 52 in the loading device 5 use servo motors, the automatic rotation mechanism 42 of the transmission device 41 in the guide device 4 uses a stepper motor, and the positioning detection mechanism 44 uses an infrared sensor. Commonly used first tension sensor 513 and second tension sensor 523 are high-precision S-shaped force sensors. The above structure is merely an example; those skilled in the art can use other equivalent structures without departing from the spirit of the invention, which are also within the scope of protection of this invention.

[0108] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An automatic calibration device for a six-dimensional force sensor, characterized in that, It includes a horizontal calibration base plate, loading fixtures, at least three guiding devices, at least three loading devices, and a control system; The loading fixture is connected to the loading end of the six-dimensional force sensor to be calibrated. The loading fixture has at least three outwardly extending extension sections. The number of the guiding device and the loading device is the same as the number of extension sections. The guide device is mounted on a horizontal calibration base plate. The guide device includes a rotating body, on which are arranged pulley groups in two vertical directions. Each pulley group includes at least two pulleys. The loading device is disposed on the horizontal calibration base plate. The loading device includes an automatic loading mechanism and a flexible loading member. The automatic loading mechanism includes a first automatic loading mechanism and a second automatic loading mechanism. The first automatic loading mechanism and the second automatic loading mechanism apply calibration loads in two directions by passing the flexible loading member around the pulley groups in the two directions respectively. One end of the flexible loading member is connected to the automatic loading mechanism, and the other end passes around the pulley on the rotating body and is connected to the extension section of the loading fixture. The control system is electrically connected to the six-dimensional force sensor, the guide device and the loading device. It is used to calculate a calibration data set including the calibration angle and the calibration load according to the preset calibration data set, control the rotating body to rotate to the calibration angle, and control the automatic loading mechanism to apply the calibration load to the loading fixture through the flexible loading component.

2. The automatic calibration device for a six-dimensional force sensor according to claim 1, characterized in that, It also includes a lifting device, which is set on a horizontal calibration base plate, and the six-dimensional force sensor to be calibrated is placed on the lifting device.

3. The automatic calibration device for a six-dimensional force sensor according to claim 1, characterized in that, The guiding device also includes an automatic rotating mechanism and a transmission device. The transmission device includes a worm and a worm wheel. The automatic rotating mechanism is connected to the worm, the worm is connected to the worm wheel, and the worm wheel is connected to the rotating body.

4. The automatic calibration device for a six-dimensional force sensor according to claim 1, characterized in that, The guiding device also includes a positioning detection mechanism for detecting the rotation angle of the rotating body.

5. The automatic calibration device for a six-dimensional force sensor according to claim 4, characterized in that, The positioning detection mechanism includes an infrared emitting module, a lens, and an infrared receiving module. The infrared emitting module and the infrared receiving module are fixed on the rotating body and are used to emit infrared light to the lens and receive the infrared light reflected by the lens.

6. The automatic calibration device for a six-dimensional force sensor according to claim 1, characterized in that, The loading device also includes a tension sensor, which is connected in series in the loading path of the flexible loading member.

7. An automatic calibration method for a six-dimensional force sensor, characterized in that, Calibration using the automatic calibration device for a six-dimensional force sensor as described in any one of claims 1 to 6 includes the following steps: Adjust the height of the six-dimensional force sensor to be calibrated so that the horizontal plane containing the central axis of the rotating body is aligned with the central horizontal plane of the loading fixture; Input one or more sets of target six-dimensional force and torque setting calibration data; The control system calculates one or more sets of calibration data based on the set calibration data set. The number of calibration data sets is consistent with the number of set calibration data sets. The calibration data sets include the calibration angle required for the rotation of the rotating body of each guide device, and the calibration load applied to each flexible loading element. The control system sends control commands to each group, controlling the rotating body of each guide device to rotate to the corresponding calibrated angle, and controlling each loading device to apply the corresponding calibrated load to the loading fixture. After each set of calibration data is loaded, it is determined whether there are any unloaded calibration data sets. If so, the next set of calibration data sets is loaded; otherwise, the loading process is terminated.

8. The automatic calibration method for a six-dimensional force sensor according to claim 7, characterized in that, The control system calculates one or more sets of calibration data based on a set of calibration data, including: The measurement space of the six-dimensional force sensor is divided into a three-dimensional force space and a three-dimensional torque space; The three-dimensional force space and three-dimensional torque space are uniformly divided from multiple directions and multiple vectors. The multiple directions refer to the horizontal plane being divided into several directional regions at equal angles according to the number of extension segments, with the installation center of the six-dimensional force sensor as the reference, in the top view direction of the calibration device. The multiple vectors refer to multiple force points or force directions implemented in different directions. A transformation matrix is ​​generated based on the number of orientations of the calibration device. The calibration load in each loading vector direction is calculated based on the transformation matrix. The calibration angle required for the rotating body to rotate is calculated based on the angle analysis formula.

9. The automatic calibration method for a six-dimensional force sensor according to claim 7, characterized in that, The control of the rotating body of each guide device to rotate to the corresponding calibrated angle includes: The automatic rotation mechanism in the control guide device drives the transmission device to adjust the rotating body to the calibrated angle; The positioning and detection mechanism uses a lens to reflect infrared light. When the rotating body reaches the calibrated angle, the positioning and detection mechanism sends a signal, and the control system controls the rotating body to stop rotating.

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