Calibration device and calibration method for three-dimensional force sensors applied to dexterous hands

Abstract

This application provides a calibration device and method for a three-dimensional force sensor applied to a dexterous hand, belonging to the field of sensor calibration technology. The calibration device includes: a central base; two three-dimensional force calibration sensors fixed opposite to each other on both sides of the central base, the force-bearing surfaces of the two sensors facing opposite directions for contact with two fingers or grippers of the dexterous hand or gripper; and a rotating outer shell rotatably mounted on the outside of the central base, the rotating outer shell having a suspension part for suspending weights or connecting a tension source; wherein, when the calibration device is vertically grasped, the suspension part rotates to a vertically downward position under the action of gravity. This application enables rapid, on-site calibration of the three-dimensional force measurement performance of the dexterous hand without disassembling the three-dimensional force sensor.

Description

Technical Field

[0001] This application relates to the field of sensor calibration technology, and in particular to a calibration device and calibration method for a three-dimensional force sensor applied to a dexterous hand. Background Technology

[0002] In the application of robotic dexterous hands and various intelligent grippers, three-dimensional force sensors integrated into the fingertips are key components for achieving precise grasping and force control feedback. As robotics technology advances towards miniaturization and integration, thin-film pressure sensors that can be embedded in the fingertips have gained widespread attention due to their compact structure and ease of deployment. These sensors are typically based on multi-point thin-film piezoresistive or capacitive principles, calculating the magnitude and direction of the three-dimensional force by detecting the force differences at multiple sensing points on a plane, thereby providing the dexterous hand with information on the normal and tangential forces during the grasping process.

[0003] Currently, calibration methods for such integrated three-dimensional force sensors mainly rely on dedicated calibration workbenches. The specific procedure involves detaching the three-dimensional force sensor from the fingertips and installing it onto a high-precision multi-dimensional force calibration device. Zero-point correction and sensitivity calibration of the three-dimensional force sensor are then performed by applying standard forces in multiple directions. For multi-point thin-film pressure sensors, due to significant drift in the pressure curve caused by temperature changes, continuous pressure, and material creep after long-term use or storage, a calibration process is typically required periodically to maintain a certain level of force feedback accuracy.

[0004] While this calibration method can obtain high-precision calibration parameters, it also has significant drawbacks. Firstly, the process of disassembling the dexterous hand's fingers and reinstalling the sensor is time-consuming and requires specialized tools and a stable workbench environment, making it difficult to conduct in practical applications such as exhibitions, outdoor work, or rapid debugging. Secondly, the force feedback accuracy of multi-point thin-film pressure sensors integrated into the fingertips is inherently lower than that of load cells; their calibration needs are more about correcting deviations caused by environmental and time-related factors rather than pursuing ultimate absolute accuracy. Existing calibration methods are high in accuracy but low in efficiency, which does not match the calibration requirements of multi-point thin-film pressure sensors, severely limiting the deployment and maintenance of dexterous hands in dynamic, non-laboratory environments.

[0005] Therefore, how to achieve rapid, on-site calibration of the three-dimensional force measurement performance of the dexterous hand without disassembling the three-dimensional force sensor has become an urgent technical problem to be solved. Summary of the Invention

[0006] The purpose of this application is to provide a calibration device and calibration method for a three-dimensional force sensor applied to a dexterous hand, so as to solve the above-mentioned problems.

[0007] To achieve the above objectives, in a first aspect, this application proposes a calibration device for a three-dimensional force sensor applied to a dexterous hand, the calibration device comprising: Central base; Two three-dimensional force calibration sensors are fixed to both sides of the central base, with their force-bearing surfaces facing opposite directions, for contact with two fingers or grippers of a dexterous hand or clamp. A rotating outer shell is rotatably fitted onto the outside of the central base, and the rotating outer shell is provided with a suspension part for suspending weights or connecting a tension source; When the calibration device is vertically grasped, the suspension part rotates to a vertically downward position under the action of gravity.

[0008] In some embodiments, the rotating housing is mounted on the outside of the central base via bearings, and the rotating housing is rotatable relative to the central base about the axis of the bearings, wherein the axis of the bearings is perpendicular to the normal direction of the force-bearing surfaces of the two three-dimensional force calibration sensors.

[0009] In some embodiments, the central base includes a first base and a second base disposed opposite to each other, the bearing includes an inner ring and an outer ring, the first base and the second base are respectively fixed to both sides of the inner ring, and the rotating housing includes a first housing and a second housing disposed opposite to each other, the first housing and the second housing are respectively fixed to both sides of the outer ring.

[0010] In some embodiments, a receiving space is formed between the first base and the second base, and the receiving space integrates a test communication circuit and a battery for transmitting measurement data from the two three-dimensional force calibration sensors.

[0011] In some embodiments, both the first housing and the second housing are cylindrical structures. The first housing and the second housing are joined together by the bearing to form a cylindrical or drum-shaped housing body, and the axis of the housing body coincides with the axis of the bearing.

[0012] In some embodiments, the calibration device further includes: Two gripping outer shells are respectively fixed to the force-bearing surfaces of the two three-dimensional force calibration sensors, for contact with the two fingers or grippers of a dexterous hand or clamp.

[0013] In some embodiments, each of the gripping surface housings has a groove in its inner central region that matches the force-receiving surface of the three-dimensional force calibration sensor, and the force-receiving surface of the three-dimensional force calibration sensor is embedded in the groove; there are gaps between the edge region of the gripping surface housing and the central base and the rotating housing, so that the gripping surface housing contacts the force-receiving surface of the three-dimensional force calibration sensor only through the groove.

[0014] In some embodiments, the three-dimensional force calibration sensor includes: A base, the upper surface of which forms a mounting surface, the mounting surface including a bottom surface and at least three side slopes that are angled to the bottom surface; A thin-film pressure sensor with multiple sensing units is fixed to the mounting surface in a bent state, such that the multiple sensing units are respectively distributed on the bottom surface and the side inclined surface; A flexible shell is installed on top of the base. The inner side of the flexible shell is provided with force guides corresponding to the positions of each of the sensing units. Each force guide abuts against the corresponding sensing unit. When the flexible shell is subjected to a three-dimensional force, it is used to transmit the three-dimensional force through each of the force guide columns to the sensing units distributed on the bottom surface and the side slope surface, thereby realizing the measurement of the three-dimensional force.

[0015] In some embodiments, the included angles between each of the side slopes and the bottom surface are equal, the shapes and areas of each of the side slopes are the same, the side slopes are distributed at equal angular intervals around the central axis of the bottom surface, and the tops of each of the side slopes are at the same horizontal height.

[0016] Secondly, to achieve the above objectives, this application also proposes a calibration method based on the above-mentioned calibration device, the method comprising: The dexterous hand is controlled to have two fingers that fit into the two gripping surfaces of the calibration device, and the zero-position outputs of the two three-dimensional force calibration sensors and the three-dimensional force sensor on the fingers are collected. The dexterous hand or gripper controls two fingers or claws to output clamping forces of different gradients in the horizontal direction in sequence. Simultaneously, the normal force measurement values ​​of the two three-dimensional force calibration sensors and the normal force output values ​​of the three-dimensional force sensors are collected. Based on the normal force measurement values, the normal force output values ​​and the zero-position output, a normal force calibration model is established, and the normal force calibration parameters are obtained by solving the model. The calibration device is clamped by two fingers or grippers of a dexterous hand or clamp, and standard weights of different masses are suspended sequentially on the suspension part. The tangential force measurement values ​​of the two three-dimensional force calibration sensors and the tangential force output values ​​of the three-dimensional force sensors are collected simultaneously. Based on the tangential force measurement values, the tangential force output values ​​and the zero-position output, a tangential force calibration model is established, and the tangential force calibration parameters are obtained by solving the model.

[0017] Compared with the prior art, the beneficial effects of this application include: This application is based on two three-dimensional force calibration sensors arranged in opposite directions. By holding the three-dimensional force calibration sensors on both sides of the calibration device with two fingers of the dexterous hand or the gripper of the clamp, the normal clamping force applied by the fingers can be measured simultaneously for calibration without removing the three-dimensional force sensor to be calibrated from the dexterous hand or the clamp.

[0018] Furthermore, the suspension part on the rotating shell can automatically remain vertically downward under the action of gravity, so that the operator only needs to suspend weights of different masses on the suspension part to apply a tangential force of known direction and magnitude to the calibration device. This ensures the accuracy and repeatability of the tangential force loading direction and avoids human error caused by manually adjusting the suspension direction.

[0019] Since the entire calibration process does not require removing the dexterous hand from the work position, disassembling the finger structure, or using a complex multidimensional force calibration workbench, it significantly reduces the time cost of calibration operations and the requirements for the site environment. It enables rapid calibration of integrated three-dimensional force sensors under non-laboratory conditions such as exhibition sites, outdoor operations, or rapid debugging. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0021] Figure 1 This is a schematic diagram of the overall structure of a calibration device for a three-dimensional force sensor applied to a dexterous hand in one embodiment; Figure 2 This is a schematic diagram of the calibration device for a three-dimensional force sensor applied to a dexterous hand in one embodiment, viewed from a first-person perspective. Figure 3 This is a schematic diagram of the calibration device for a three-dimensional force sensor applied to a dexterous hand in one embodiment, viewed from a second perspective. Figure 4 This is a schematic diagram of the calibration device for a three-dimensional force sensor applied to a dexterous hand in one embodiment, viewed from a third-person perspective. Figure 5 This is a cross-sectional structural schematic diagram of a calibration device for a three-dimensional force sensor applied to a dexterous hand in one embodiment; Figure 6 This is a schematic diagram of the overall structure of a calibration device for a three-dimensional force sensor applied to a dexterous hand in another embodiment; Figure 7 This is a schematic diagram of the calibration device for a three-dimensional force sensor applied to a dexterous hand in another embodiment, viewed from a fourth perspective. Figure 8 This is a schematic diagram of the calibration device for a three-dimensional force sensor applied to a dexterous hand in another embodiment, viewed from a fifth-person perspective. Figure 9 This is a schematic diagram of the calibration device for a three-dimensional force sensor applied to a dexterous hand in another embodiment, viewed from a sixth-person perspective. Figure 10 This is a cross-sectional schematic diagram of a calibration device for a three-dimensional force sensor applied to a dexterous hand in another embodiment; Figure 11 This is a schematic diagram of the overall structure of a three-dimensional force calibration sensor in one embodiment; Figure 12 This is a schematic cross-sectional view of a three-dimensional force calibration sensor in one embodiment; Figure 13 This is a schematic diagram of the overall structure of the base in one embodiment; Figure 14 This is a schematic diagram of the overall structure of a thin-film pressure sensor mounted on a base in one embodiment; Figure 15 This is a schematic diagram of the overall structure of the flexible shell in one embodiment; Figure 16 This is a schematic flowchart of a calibration method for a calibration device in one embodiment.

[0022] Explanation of reference numerals in the attached drawings: 100, calibration device; 10, central base; 11, first base; 12, second base; 20, three-dimensional force calibration sensor; 21, base; 211, bottom surface; 212, side slope; 22, thin-film pressure sensor; 221, sensing unit; 23, flexible housing; 231, force guide column; 30, rotating housing; 31, suspension part; 32, first housing; 33, second housing; 40, bearing; 50, gripping surface housing. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0024] All terms used in this application (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0025] For example, the terms "first," "second," etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For instance, without departing from the scope of this application, a first base may be referred to as a second base, and similarly, a second base may be referred to as a first base. Both the first base and the second base are bases, but they are not the same base.

[0026] For example, the terms "comprising" or "including" used in this application indicate the presence of features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0027] As mentioned earlier, current calibration methods for integrated 3D force sensors primarily rely on dedicated calibration workbenches. The specific procedure involves detaching the 3D force sensor from the fingertip and installing it onto a high-precision multi-dimensional force calibration device. Zero-point correction and sensitivity calibration of the 3D force sensor are then performed by applying standard forces in multiple directions. For multi-point thin-film pressure sensors, the pressure curves often drift significantly after long-term use or storage due to factors such as temperature changes, continuous pressure, and material creep. Therefore, a calibration process is typically required periodically to maintain a certain level of force feedback accuracy. While this calibration method can obtain high-precision calibration parameters, it also has significant drawbacks. Firstly, disassembling the fingertip and reinstalling the sensor is time-consuming and requires specialized tools and a stable workbench environment, making it difficult to perform in practical applications such as exhibitions, outdoor work, or rapid debugging. Secondly, the force feedback accuracy of multi-point thin-film pressure sensors integrated into the fingertip is inherently lower than that of load cells; their calibration needs are more about correcting deviations caused by environmental and time-related factors rather than pursuing ultimate absolute accuracy. Existing calibration methods are highly accurate but inefficient, and do not meet the calibration requirements of multi-point thin-film pressure sensors, severely limiting the deployment and maintenance of dexterous hands in dynamic, non-laboratory environments.

[0028] Therefore, how to achieve rapid, on-site calibration of the three-dimensional force measurement performance of the dexterous hand without disassembling the dexterous hand's three-dimensional force sensor has become an urgent technical problem to be solved. To this end, this application proposes a calibration device and calibration method for a three-dimensional force sensor applied to a dexterous hand, which can achieve rapid, on-site calibration of the three-dimensional force measurement performance without disassembling the dexterous hand's three-dimensional force sensor.

[0029] like Figures 1 to 10 As shown, this application embodiment provides a calibration device 100 for a three-dimensional force sensor applied to a dexterous hand. The calibration device 100 includes: Central base 10; Two three-dimensional force calibration sensors 20 are fixed to both sides of the central base 10 with their force-bearing surfaces facing opposite directions, and are used to contact the two fingers or grippers of the dexterous hand or clamp. A rotating housing 30 is rotatably fitted onto the outside of the central base 10. The rotating housing 30 is provided with a suspension part 31 for suspending weights or connecting a tension source. When the calibration device 100 is vertically grasped, the suspension part 31 rotates to a vertically downward position under the action of gravity.

[0030] In this embodiment, the core of the calibration device 100 lies in integrating two three-dimensional force calibration sensors 20 with known accuracy, facing each other back-to-back, into a rotatable structure. When calibrating a three-dimensional force sensor on a dexterous hand or fixture, the operator only needs to control two fingers of the dexterous hand to grasp the two force-bearing surfaces of the calibration device 100 from both sides, so that the three-dimensional force sensor on the fingers and the three-dimensional force calibration sensor 20 in the calibration device 100 form a force transmission path. In this way, the three-dimensional force calibration sensor 20 in the calibration device 100 serves as a reference, and the force applied to it can be measured in real time, thereby calibrating the three-dimensional force sensor to be calibrated. By suspending weights of different masses on the suspension part 31 or connecting a tension source, a tangential force of known magnitude can be applied, thereby completing the multi-dimensional calibration of the three-dimensional force sensor to be calibrated.

[0031] In some implementations, such as Figure 5 and Figure 10 As shown, the rotating housing 30 is mounted on the outside of the central base 10 via a bearing 40. The rotating housing 30 can rotate relative to the central base 10 about the axis of the bearing 40, wherein the axis of the bearing 40 is perpendicular to the normal direction of the force-bearing surfaces of the two three-dimensional force calibration sensors 20. In this embodiment, by setting the bearing 40, the rotational resistance between the rotating housing 30 and the central base 10 can be effectively reduced, ensuring that when the calibration device 100 is vertically grasped, the suspension part 31 can rotate sensitively and smoothly to a vertically downward position under the action of gravity, thereby ensuring that the direction of the applied tangential force is always perpendicular to the horizontal plane, improving the accuracy of tangential force calibration. At the same time, the limitation that the axis of the bearing 40 is perpendicular to the normal direction of the force-bearing surface of the three-dimensional force calibration sensor 20 ensures that the rotation plane of the suspension part 31 is orthogonal to the measurement plane of the sensor, avoiding interference of the sensor measurement by the torque generated by rotation.

[0032] In some implementations, such as Figure 5 and Figure 10 As shown, the central base 10 includes a first base 11 and a second base 12 disposed opposite to each other. The bearing 40 includes an inner ring and an outer ring (not shown in the figure). The first base 11 and the second base 12 are respectively fixed to both sides of the inner ring. The rotating housing 30 includes a first housing 32 and a second housing 33 disposed opposite to each other. The first housing 32 and the second housing 33 are respectively fixed to both sides of the outer ring. In this embodiment, by designing both the central base 10 and the rotating housing 30 as separate structures and fixing them to both sides of the inner and outer rings of the bearing 40 respectively, the assembly process is simplified and the processing difficulty is reduced. On the other hand, the structure of the entire calibration device 100 is more compact and symmetrical, ensuring that the force-bearing surfaces of the two three-dimensional force calibration sensors 20 are balanced, thus improving the accuracy and consistency of the calibration.

[0033] In some embodiments, a receiving space (not shown in the figure) is formed between the first base 11 and the second base 12. The receiving space integrates a test communication circuit and a battery for transmitting measurement data from the two three-dimensional force calibration sensors 20. This embodiment, by reserving a receiving space inside the central base 10 and integrating the test communication circuit (such as a signal conditioning circuit, analog-to-digital conversion circuit, wireless communication module, etc.) and the power supply battery therein, makes the calibration device 100 an independent intelligent calibration tool with wireless data transmission capabilities. During calibration, the measurement data from the three-dimensional force calibration sensors 20 can be transmitted in real time to electronic devices (such as computers, tablets, or dexterous hand controllers) via wireless means such as Bluetooth, without the need for external wiring. This avoids interference from cables on force loading and improves the convenience of calibration and the reliability of data acquisition.

[0034] In some implementations, such as Figure 1 and Figure 6 As shown, both the first outer shell 32 and the second outer shell 33 are cylindrical structures. After being joined by the bearing 40, they form a cylindrical or drum-shaped outer shell, with the axis of the outer shell coinciding with the axis of the bearing 40. In this embodiment, designing the rotating outer shell 30 as cylindrical or drum-shaped facilitates stable contact with the fingers or grippers of a dexterous hand during grasping. Furthermore, when the calibration device 100 is grasped vertically, the smooth shape helps reduce wind resistance and unnecessary interference. The design of the outer shell axis coinciding with the bearing 40 axis ensures that the center of mass of the entire rotating part is located on the rotation axis, allowing the suspension part 31 to rotate more sensitively under gravity and preventing eccentric vibration during rotation, thus ensuring the stability of tangential force loading.

[0035] In some implementations, such as Figures 1 to 10As shown, the calibration device 100 further includes two gripping surface housings 50, which are respectively fixed to the force-bearing surfaces of the two three-dimensional force calibration sensors 20, for contact with the two fingers or grippers of the dexterous hand or fixture. In this embodiment, the gripping surface housings 50, as components that directly contact the fingers of the dexterous hand or the grippers of the fixture, form a standard contact surface, providing a unified mechanical interface for calibration operations of different dexterous hands and different batches, so that the calibration results only reflect the characteristics of the sensor to be calibrated itself, and are independent of the gripping conditions. The material can be selected as a material with a certain degree of hardness and wear resistance (such as metal, hard plastic, etc.) to withstand repeated gripping and loading. At the same time, the design of the gripping surface housings 50 can effectively protect the force-bearing surfaces of the internal three-dimensional force calibration sensors 20 from scratches or damage, extending the service life of the calibration device 100.

[0036] In some implementations, such as Figure 4 and Figure 5 As shown, each gripping surface housing 50 has a groove in its inner central region that matches the force-receiving surface of the three-dimensional force calibration sensor 20, and the force-receiving surface of the three-dimensional force calibration sensor 20 is embedded in the groove. Gaps exist between the edge region of the gripping surface housing 50 and the central base 10 and the rotating housing 30, ensuring that the gripping surface housing 50 only contacts the force-receiving surface of the three-dimensional force calibration sensor 20 through the groove. This embodiment achieves precise alignment and fixation between the gripping surface housing 50 and the force-receiving surface of the three-dimensional force calibration sensor 20, guaranteeing the uniqueness and directness of the force transmission path. Furthermore, gaps are maintained between the edge of the gripping surface housing 50 and the central base 10 and the rotating housing 30, forming a suspended connection structure. This effectively prevents forces outside the measurement direction (such as additional torque or friction generated by edge contact) from being transmitted to the three-dimensional force calibration sensor 20 through the edge of the gripping surface housing 50, thereby ensuring that the force value measured by the three-dimensional force calibration sensor 20 comes entirely from the force applied by the dexterous hand's fingers, improving the accuracy of the calibration.

[0037] In some embodiments, the gripping surface housing 50 is configured with a geometry adapted to the gripping surface of the fingers or grippers of a dexterous hand or jig. Specifically, the side of the gripping surface housing 50 facing the fingers of the dexterous hand is set as any one of a plane, an arc surface, or a contoured surface. For example, when the fingertips of the dexterous hand are planes, the contact surface of the gripping surface housing 50 is correspondingly set as a plane; when the fingertips of the dexterous hand are arc surfaces with a certain curvature, the contact surface of the gripping surface housing 50 is correspondingly set as an arc surface with matching curvature. Through this adaptive design, it can be ensured that the gripping surface housing 50 forms a surface contact rather than a point contact or line contact with the fingers of the dexterous hand or the grippers, so that the applied normal force and tangential force can be uniformly and stably transmitted to the three-dimensional force calibration sensor 20, avoiding measurement errors caused by local stress concentration.

[0038] In some embodiments, the gripping surface housing 50 employs a modular design, meaning that the gripping surface housing 50 is detachably fixed to the force-bearing surface of the three-dimensional force calibration sensor 20. This allows operators to quickly replace the gripping surface housing 50 with a corresponding contact surface shape according to the contact surface shape and size of different dexterous hand fingers, without having to replace the entire calibration device 100.

[0039] The specific implementation of the three-dimensional force calibration sensor 20 in this embodiment is not limited to a particular structure. For example, the three-dimensional force calibration sensor 20 can be an optical multidimensional force sensor, which uses optical principles to sense changes in force and has advantages such as resistance to electromagnetic interference and high accuracy; it can also be a capacitive three-dimensional force sensor, which calculates the magnitude and direction of the three-dimensional force by detecting the capacitance changes between multiple capacitor nodes; it can also be a piezoresistive, piezoelectric, or MEMS-based three-dimensional force sensor. As long as it can realize the measurement of three-dimensional force and meet the requirements of miniaturization and integration, it can be used as the three-dimensional force calibration sensor 20 in this application. Those skilled in the art can flexibly select the appropriate sensor type according to the requirements of accuracy, cost, response speed, and other indicators in the actual application scenario.

[0040] exist Figures 1 to 5 The image exemplarily illustrates a three-dimensional force calibration sensor based on a thin-film pressure sensor bending and bonding structure. Figures 6 to 10 The diagram shows a schematic of a light-based multidimensional force sensor. Both of these implementations can be well integrated into the calibration device 100 of this application and serve as a reference sensor to provide a high-precision reference force value for the sensor to be calibrated on a dexterous hand or clamp.

[0041] Taking the three-dimensional force calibration sensor 20 based on the bending and bonding structure of a thin-film pressure sensor as an example, such as Figures 11 to 15 As shown, the three-dimensional force calibration sensor 20 includes: a base 21, a thin-film pressure sensor 22, and a flexible housing 23.

[0042] Among them, such as Figure 13 As shown, the upper surface of the base 21 forms a mounting surface, which includes a bottom surface 211 and at least three side slopes 212 that are angled to the bottom surface 211. The base is made of a rigid material (such as plastic or metal) to provide stable support and geometric constraints.

[0043] In some implementations, such as Figure 13As shown, the upper surface of the base 21 has a concave structure. Specifically, the bottom surface 211 is the bottom plane of the concave structure, and the side slope 212 is an inclined surface extending upward and outward from the edge of the bottom plane. Alternatively, the upper surface of the base 21 has a convex structure (not shown in the figure), in which case the bottom surface 211 is the top plane of the convex structure, and the side slope 212 is an inclined surface extending downward and outward from the edge of the top plane. The concave or convex structure of the base can realize the decomposition and detection of multi-directional forces.

[0044] To ensure isotropy or computational simplicity in three-dimensional force measurement, in some embodiments, the included angles between each side slope 212 and the bottom surface 211 are equal. Simultaneously, each side slope 212 has the same shape and area, and is distributed at equal angular intervals around the central axis of the bottom surface 211, with the tops of each side slope 212 at the same horizontal height. This symmetrical design ensures consistent sensitivity and calibration characteristics for tangential force measurement in the horizontal direction.

[0045] like Figure 14 As shown, the thin-film pressure sensor 22 is a flexible thin-film sensor based on the piezoresistive or capacitive principle, and it has multiple sensing units 221. The thin-film pressure sensor 22 is fixed to the mounting surface of the base 21 in a bent state, so that the multiple sensing units 221 are distributed on the bottom surface 211 and each side inclined surface 212. Specifically, a part of the thin-film pressure sensor 22 is attached to the bottom surface 211, and another part is bent and attached along the direction of the side inclined surface 212, so that the multiple sensing units that were originally on the same plane are redistributed to different spatial planes (a part is located on the horizontal bottom surface, and the other part is located on the inclined side surface).

[0046] like Figure 15As shown, a flexible shell 23 covers the base 21. The flexible shell 23 is made of elastic materials such as silicone, rubber, or TPU, with a Shore hardness range of 30A-60A. Guide pillars 231 are respectively arranged on the inner side of the flexible shell 23 corresponding to the positions of each sensing unit 221, and each guide pillar 231 abuts against its corresponding sensing unit 221. When the flexible shell 23 is subjected to an external three-dimensional force (including normal and tangential forces), the flexible shell 23 deforms, transmitting the received three-dimensional force through the guide pillars 231 to the different sensing units 221 distributed on the bottom surface 211 and the side slope 212. Since the bottom surface 211 and the side slope 212 are oriented differently in space, the sensing units 221 distributed on them can sense the force components of the three-dimensional force in different directions, thereby realizing the direct measurement of the three-dimensional force. Specifically, when the flexible shell 23 is subjected to a three-dimensional force, the bottom pressure value detected by the sensing unit 221 distributed on the bottom surface 211 and the side slope pressure value detected by the sensing unit distributed on each side slope 212 are obtained. Based on the angle between each side slope 212 and the bottom surface 211 and the azimuth angle of each side slope 212, the bottom pressure value and the side slope pressure value are vector-summed, and the summation result is compensated according to a preset calibration coefficient to obtain the three-dimensional force measurement value.

[0047] The three-dimensional force calibration sensor 20 in this embodiment, by taking advantage of the flexible thin-film characteristics of the thin-film pressure sensor itself, fundamentally breaks through the physical bottleneck of thickness compression of traditional rigid elastomer structures (such as cross beam type, Stewart platform type, etc.), and can easily reduce the overall thickness of the sensor to the millimeter level or even below, so that the calibration device 100 has the advantages of small size and high integration, and is particularly suitable for on-site calibration services.

[0048] The calibration device 100 for a three-dimensional force sensor in a dexterous hand, as proposed in this embodiment, utilizes two back-to-back three-dimensional force calibration sensors. By clamping the three-dimensional force calibration sensors on both sides of the calibration device with two fingers of the dexterous hand or the gripper of a jig, the normal clamping force applied by the fingers can be measured simultaneously for calibration without removing the three-dimensional force sensor to be calibrated from the dexterous hand or jig. Furthermore, the suspension part on the rotating housing automatically maintains a vertically downward position under gravity, allowing the operator to apply a tangential force of known direction and magnitude to the calibration device simply by suspending weights of different masses on the suspension part. This ensures the accuracy and repeatability of the tangential force loading direction and avoids human error introduced by manually adjusting the suspension direction. Since the entire calibration process does not require removing the dexterous hand from its working position, disassembling the finger structure, or using a complex multi-dimensional force calibration workbench, it significantly reduces the time cost and environmental requirements of the calibration operation. It enables rapid calibration of integrated three-dimensional force sensors under non-laboratory conditions such as exhibition sites, outdoor operations, or rapid debugging.

[0049] like Figure 16 As shown in the figure, this application embodiment provides a calibration method based on a calibration device 100, the method including the following steps: Step S10: Control the two fingers of the dexterous hand to fit against the two gripping surfaces of the calibration device, and collect the zero-position output of the two three-dimensional force calibration sensors and the three-dimensional force sensor on the fingers.

[0050] In this embodiment, the two gripping surfaces of the calibration device 100 correspond to the force-bearing surfaces of the two three-dimensional force calibration sensors 20, or the outer surfaces of the two gripping surface shells. Zero-point output refers to the original electrical signal output value of the sensor when it is not subjected to any external force (i.e., no-load state), which can be used for subsequent zero-point compensation to eliminate the influence of initial sensor drift and tooling preload.

[0051] Specifically, the calibration device 100 is placed on a dedicated support, with the support only contacting the rotating outer shell 30 of the calibration device 100. This ensures that the suspension part 31 hangs naturally and does not contact any object, thus guaranteeing that the two three-dimensional force calibration sensors are in an unloaded state. Two fingers of the dexterous hand are controlled to adhere to the two gripping surfaces of the calibration device 100 with minimal force (just enough to contact but not exert pressure), ensuring that both the three-dimensional force sensors on the fingers and the three-dimensional force calibration sensors 20 of the calibration device 100 are in an unloaded state. The zero-point outputs of the two three-dimensional force calibration sensors 20 are simultaneously acquired. ,in, To provide the normal force zero-point output for the three-dimensional force calibration sensor 20, This is used to calibrate the tangential force zero-point output of the three-dimensional force calibration sensor 20. The zero-point output of the three-dimensional force sensor to be calibrated. Among them, the normal force zero-position output of the three-dimensional force sensor is The tangential force zero-point output of the three-dimensional force sensor is .

[0052] Step S20: Control the two fingers or grippers of the dexterous hand or clamp to output clamping forces of different gradients in the horizontal direction in sequence, simultaneously collect the normal force measurement values ​​of the two three-dimensional force calibration sensors and the normal force output values ​​of the three-dimensional force sensors, and establish a normal force calibration model based on the normal force measurement values, the normal force output values ​​and the zero-position output, and solve for the normal force calibration parameters.

[0053] In this embodiment, the normal force refers to the force perpendicular to the gripping surface (i.e., perpendicular to the finger contact surface). Different gradients of clamping force refer to the dexterous hand controller instructing the finger to output a series of force values ​​(e.g., 0N, 1N, 2N, 3N…10N) that increase in size and are evenly spaced; each force value is called a gradient. The measured normal force value is the normal force value measured by the two three-dimensional force calibration sensors 20 inside the calibration device 100. Since the two sensors are back-to-back, the pressure on each sensor is equal in magnitude and opposite in direction when the finger clamps; the average of the two values ​​is taken as the measured normal force value. The normal force output value refers to the original reading (uncorrected value) output by the three-dimensional force sensor to be calibrated under the same clamping force. The normal force calibration model can be a linear relationship. ,in, This is the measured value of the normal force. This is the normal force output value. , The parameters to be solved for the normal force calibration are (scale coefficients and offsets). Substituting the collected sets of normal force measurements and output values ​​into the normal force calibration model, and then using the least squares method for fitting, yields the normal force calibration parameters.

[0054] Step S30: Control the two fingers or grippers of the dexterous hand or clamp to clamp the calibration device, and suspend standard weights of different masses on the suspension part in sequence. Simultaneously collect the tangential force measurement values ​​of the two three-dimensional force calibration sensors and the tangential force output values ​​of the three-dimensional force sensors. Based on the tangential force measurement values, the tangential force output values ​​and the zero-position output, establish a tangential force calibration model and solve for the tangential force calibration parameters.

[0055] In this embodiment, tangential force refers to the force parallel to the grasping surface (i.e., parallel to the finger contact surface). On the calibration device 100, it manifests as a vertically downward force generated by the friction of the fingers due to the gravity of the suspended weight. A standard weight is an object with a known precise mass, typically converted to a force value based on standard gravitational acceleration (e.g., 1 kg weight corresponds to 9.8 N). The weight is suspended on the suspension part 31 at the lower end of the calibration device 100, generating a vertically downward pulling force. The measured tangential force value refers to the tangential force value measured by the two three-dimensional force calibration sensors 20 inside the calibration device 100. Since the two sensors are back-to-back, when the weight is suspended, the tangential force experienced by each sensor is equal in magnitude and opposite in direction. However, in reality, the sum of the frictional forces provided by the two fingers equals the total gravity; therefore, the tangential force experienced by each finger is half of the total gravity. The average of the two is taken as the measured tangential force value. The tangential force output value refers to the original reading (uncorrected value) output by the three-dimensional force sensor to be calibrated under the same tangential force. The tangential force calibration model can be a linear relationship. ,in, This is the measured value of the tangential force. This is the tangential force output value. , The tangential force calibration parameters (scale coefficients and offsets) are to be solved. Substituting the collected multiple sets of tangential force measurements and output values ​​into the tangential force calibration model, and using the least squares method for fitting, the tangential force calibration parameters can be obtained.

[0056] If coupling is found between the normal force and the tangential force (i.e., the tangential channel also shows a significant output when the normal force is applied), the normal force calibration model and the tangential force calibration model can be extended into a coupled linear model: Then, a joint solution is performed to obtain the normal force calibration parameters and the tangential force calibration parameters.

[0057] It should be noted that when calibrating tangential forces in different directions, it is only necessary to ensure that the gripping surface of the calibration device 100 is perpendicular to the ground, and change the direction in which the dexterous hand grips the calibration device 100 to achieve tangential force testing and calibration in different directions.

[0058] In the calibration method based on the calibration device 100 proposed in this application embodiment, it is not necessary to remove the three-dimensional force sensor to be calibrated from the fingers of the dexterous hand throughout the entire process. Instead, the dexterous hand's own fingers are used as the actuator to hold the calibration device 100 provided in this application and complete all calibration operations in situ.

[0059] First, by pre-acquiring the zero-point output, the zero drift effect caused by long-term use or temperature changes of the sensor is effectively eliminated, providing accurate baseline correction for subsequent loading data. Second, by using gradient clamping force loading, the two back-to-back three-dimensional force calibration sensors 20 inside the calibration device 100 provide accurate normal force measurements. Combined with the synchronously acquired normal force output values ​​of the three-dimensional force sensor to be calibrated, the scale coefficients and offset parameters of the normal force calibration model can be quickly fitted. Finally, by using a suspended standard weight to generate a precisely known tangential force, with the automatic vertical alignment assistance of the rotating housing 30 of the calibration device 100, the direction of the tangential force is always vertically downward, thus obtaining a stable and reliable tangential force measurement value, thereby completing the tangential force calibration. The entire process does not rely on an external multi-dimensional force calibration stage, nor does it require complex disassembly and assembly tools. Only a dexterous hand needs to perform the clamping and weight suspension actions in sequence, and the on-site calibration of normal and tangential forces can be completed simultaneously within a few minutes.

[0060] Compared with traditional methods, this application significantly reduces the time cost of calibration operations and the requirements for site environment, enabling dexterous hands and other fixtures to conveniently maintain sensor accuracy under non-laboratory conditions such as exhibition sites, outdoor operations, or rapid debugging, greatly improving the maintainability and deployment flexibility of the equipment.

[0061] Meanwhile, this method separates the calibration of normal force and tangential force, establishing independent linear or coupled models for each, which ensures calibration accuracy and reduces computational complexity, fully meeting the actual needs of multi-point thin-film pressure sensors that require periodic deviation correction due to factors such as temperature and creep.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0063] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, any of the embodiments or implementations claimed above can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A calibration device for a three-dimensional force sensor applied to a dexterous hand, characterized in that, The calibration device includes: Central base; Two three-dimensional force calibration sensors are fixed to both sides of the central base, with their force-bearing surfaces facing opposite directions, for contact with two fingers or grippers of a dexterous hand or clamp. A rotating outer shell is rotatably fitted onto the outside of the central base, and the rotating outer shell is provided with a suspension part for suspending weights or connecting a tension source; When the calibration device is vertically grasped, the suspension part rotates to a vertically downward position under the action of gravity.

2. The calibration device for a three-dimensional force sensor applied to a dexterous hand according to claim 1, characterized in that, The rotating housing is mounted on the outside of the central base via bearings. The rotating housing can rotate relative to the central base about the axis of the bearings, wherein the axis of the bearings is perpendicular to the normal direction of the force-bearing surfaces of the two three-dimensional force calibration sensors.

3. The calibration device for a three-dimensional force sensor applied to a dexterous hand according to claim 2, characterized in that, The central base includes a first base and a second base arranged opposite to each other. The bearing includes an inner ring and an outer ring. The first base and the second base are respectively fixed to both sides of the inner ring. The rotating housing includes a first housing and a second housing arranged opposite to each other. The first housing and the second housing are respectively fixed to both sides of the outer ring.

4. The calibration device for a three-dimensional force sensor applied to a dexterous hand according to claim 3, characterized in that, A receiving space is formed between the first base and the second base, and the receiving space integrates a test communication circuit and a battery for transmitting measurement data from the two three-dimensional force calibration sensors.

5. The calibration device for a three-dimensional force sensor applied to a dexterous hand according to claim 3, characterized in that, Both the first and second outer shells are cylindrical structures. After the first and second outer shells are joined together by the bearing, they form a cylindrical or drum-shaped outer shell. The axis of the outer shell coincides with the axis of the bearing.

6. The calibration device for a three-dimensional force sensor applied to a dexterous hand according to claim 1, characterized in that, The calibration device further includes: Two gripping outer shells are respectively fixed to the force-bearing surfaces of the two three-dimensional force calibration sensors, for contact with the two fingers or grippers of a dexterous hand or clamp.

7. The calibration device for a three-dimensional force sensor applied to a dexterous hand according to claim 6, characterized in that, Each of the gripping surface housings has a groove in its inner central region that matches the force-receiving surface of the three-dimensional force calibration sensor, and the force-receiving surface of the three-dimensional force calibration sensor is embedded in the groove; there are gaps between the edge region of the gripping surface housing and the central base and the rotating housing, so that the gripping surface housing contacts the force-receiving surface of the three-dimensional force calibration sensor only through the groove.

8. The calibration device for a three-dimensional force sensor applied to a dexterous hand according to claim 1, characterized in that, The three-dimensional force calibration sensor includes: A base, the upper surface of which forms a mounting surface, the mounting surface including a bottom surface and at least three side slopes that are angled to the bottom surface; A thin-film pressure sensor with multiple sensing units is fixed to the mounting surface in a bent state, such that the multiple sensing units are respectively distributed on the bottom surface and the side inclined surface; A flexible shell is installed on top of the base. The inner side of the flexible shell is provided with force guides corresponding to the positions of each of the sensing units. Each force guide abuts against the corresponding sensing unit. When the flexible shell is subjected to a three-dimensional force, it is used to transmit the three-dimensional force through each of the force guide columns to the sensing units distributed on the bottom surface and the side slope surface, thereby realizing the measurement of the three-dimensional force.

9. The calibration device for a three-dimensional force sensor applied to a dexterous hand according to claim 8, characterized in that, The included angles between each of the side slopes and the bottom surface are equal, the shape and area of ​​each of the side slopes are the same, the side slopes are distributed at equal angular intervals around the central axis of the bottom surface, and the tops of each of the side slopes are at the same horizontal height.

10. A calibration method based on the calibration device according to any one of claims 1 to 9, characterized in that, The method includes: The dexterous hand is controlled to have two fingers that fit into the two gripping surfaces of the calibration device, and the zero-position outputs of the two three-dimensional force calibration sensors and the three-dimensional force sensor on the fingers are collected. The dexterous hand or gripper controls two fingers or claws to output clamping forces of different gradients in the horizontal direction in sequence. Simultaneously, the normal force measurement values ​​of the two three-dimensional force calibration sensors and the normal force output values ​​of the three-dimensional force sensors are collected. Based on the normal force measurement values, the normal force output values ​​and the zero-position output, a normal force calibration model is established, and the normal force calibration parameters are obtained by solving the model. The calibration device is clamped by two fingers or grippers of a dexterous hand or clamp, and standard weights of different masses are suspended sequentially on the suspension part. The tangential force measurement values ​​of the two three-dimensional force calibration sensors and the tangential force output values ​​of the three-dimensional force sensors are collected simultaneously. Based on the tangential force measurement values, the tangential force output values ​​and the zero-position output, a tangential force calibration model is established, and the tangential force calibration parameters are obtained by solving the model.

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