A force measurement system with weak rigidity support

Abstract

The present invention relates to the field of precision measurement technology, and specifically provides a force measurement system with a weak rigidity support, comprising: a bearing mechanism, comprising a load platform and a rigid support, wherein the lines connecting the vertices on the load plane of the rigid support form a regular polygon, and the cross section of the load platform has the same shape as the load plane; an elastic force measurement mechanism, which elastically connects the connection points of the vertices on the load plane to the load platform, thereby causing the elastic force measurement mechanism to produce elastic deformation and obtain disturbance parameters in the connection directions with the vertices; a solution unit, which calculates the resultant force of the load platform in three directions in a three-dimensional rectangular coordinate system and the distance from the resultant force point to the center point of the load platform based on the disturbance parameters; and calculates the torque of the load platform in three directions in the three-dimensional rectangular coordinate system based on the distance to the center point and the component forces in the three directions. The present invention utilizes the elastic force measurement mechanism to establish a flexible boundary, isolate the interference of environmental noise, and improve measurement accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical measurement, and in particular to a force measurement system with weak rigidity support. Background Art

[0002] In the field of vibration testing and mechanical measurement, weak stiffness measurement systems are widely used to simulate high-flexibility installation conditions to analyze the disturbing force characteristics of vibration sources (such as aerospace momentum wheels, precision instruments, etc.) under flexible supports.

[0003] Traditional systems typically perform measurements directly using a rigid boundary measurement system or by simulating a flexible boundary through design. These systems are susceptible to environmental noise and have poor interference immunity. Adjusting system stiffness by adjusting or replacing boundary components requires manual assembly and disassembly, which is complex and time-consuming.

[0004] This approach is not only inefficient but also difficult to achieve stepless adjustment of boundary stiffness. It can only achieve a specified design stiffness by replacing boundary flexible elements. Furthermore, existing systems are typically designed for specific test scenarios and cannot implement multi-dimensional stiffness coupling adjustment. Expanding to multi-axis torque measurement or complex stiffness conditions requires redesigning the flexible structure, which is costly and incompatible. Summary of the Invention

[0005] The purpose of the present invention is to provide a force measurement system with a weak rigidity support, which can solve at least one of the above-mentioned technical problems. The specific solution is as follows:

[0006] According to a specific embodiment disclosed in the present invention, a first aspect of the present invention discloses a force measurement system with a weak stiffness support, comprising:

[0007] Carrying mechanism,

[0008] Used to carry a vibration source, the carrying vibration source is suspended on a rigid boundary by a first elastic rope, the carrying mechanism includes: a load platform and a rigid bracket, the rigid bracket has a regular polygonal load plane, the cross-section of the load platform has the same shape as the load plane, and the load platform is parallel to the load plane;

[0009] an elastic force measuring mechanism comprising a plurality of second elastic cords and a plurality of sensor assemblies, wherein the plurality of second elastic cords are respectively connected to the load plane and each vertex of the load platform, and the plurality of sensor assemblies are respectively disposed on the plurality of second elastic cords. In response to the vibration of the vibration source, the plurality of second elastic cords are elastically deformed, and the plurality of sensor assemblies respectively obtain disturbance force parameters of the plurality of second elastic cords based on the elastic deformation;

[0010] A solving unit calculates the moments of the load platform in the directions of the three coordinate axes in a spatial rectangular coordinate system according to the disturbance force parameters.

[0011] Optionally, each of the sensor components includes: a single force sensor and a displacement sensor.

[0012] Optionally, it further includes: a pre-tightening component, which is connected to the second elastic rope, and adjusts the disturbance force parameter by adjusting the length of the second elastic rope so that the stiffness of the elastic force measuring mechanism meets a preset value.

[0013] Optionally, the pre-tightening assembly includes: a control motor and a winding wheel, and the control motor is used to drive the winding wheel to rotate to adjust the length of the second elastic rope.

[0014] Optionally, the pre-tensioning assembly includes: a torque compensation mechanism, the torque compensation mechanism includes: a plurality of torque constraint sensors and a plurality of third elastic ropes, the plurality of torque constraint sensors are respectively arranged on the third elastic ropes; the two ends of each of the third elastic ropes are respectively connected to the two adjacent second elastic ropes, and the plurality of third elastic ropes are combined to form the regular polygon.

[0015] Optionally, it further includes: a compensation solving unit, which calculates the compensation torque in the direction of gravity based on the data of the multiple torque constraint sensors.

[0016] Optionally, the regular polygon is a regular quadrilateral, a regular pentagon, a regular hexagon, a regular heptagon or a regular octagon.

[0017] Optionally, the torques of the load platform in three directions in a three-dimensional rectangular coordinate system are expressed as:

[0018] 、 、

[0019] in, L is the distance from the resultant force point to the center point of the load platform;

[0020] and They respectively represent the components of force on the load platform in the x, y, and z directions after adjusting the stiffness.

[0021] Optionally, the torque expression for compensation in the gravity direction is:

[0022]

[0023] in, n is the number of torque constraint sensors;

[0024] For the i data returned by the torque constraint sensor;

[0025] R is the distance between the known torque constraint sensor and the torsion center.

[0026] Compared with the prior art, the above solution of the embodiment disclosed in the present invention has at least the following beneficial effects:

[0027] The present invention utilizes an elastic force measuring mechanism to establish a flexible boundary, which can isolate the interference of environmental noise and improve measurement accuracy. By adjusting the length of the elastic rope, any system stiffness can be simulated, and the simulated flexible boundary can be steplessly adjusted within the designed stiffness range. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are incorporated into and constitute a part of the specification, illustrating embodiments consistent with the present disclosure and, together with the specification, serving to explain the principles of the present disclosure. Obviously, the drawings described below are merely some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on these drawings without inventive effort. In the accompanying drawings:

[0029] Figure 1 A schematic diagram of the overall structure of a force measurement system with weak rigidity support provided by an embodiment of the present invention;

[0030] Figure 2 for Figure 1 AA cross-section of

[0031] Figure 3 A schematic structural diagram of a pre-tightening assembly provided in an embodiment of the present invention;

[0032] Figure 4 This is a flow chart of measuring a momentum wheel using a force measuring system with a weak stiffness support provided by an embodiment of the present invention.

[0033] Reference numerals:

[0034] 1-vibration source, 2-rigid bracket, 21-support column, 22-support beam, 3-load platform,

[0035] 41-first elastic rope, 42-second elastic rope, 43-third elastic rope,

[0036] 5-sensor assembly, 6-torque constraint sensor, 71-control motor, 72-winding wheel. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages disclosed in the present invention more clearly apparent, a force measurement system with a weak rigidity support disclosed in the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a portion of the embodiments disclosed in the present invention, and not all of them. Based on the embodiments disclosed in the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative effort are within the scope of protection disclosed in the present invention.

[0038] The terms used in the examples of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms "a," "the," and "the" used in the examples of this application and the appended claims are also intended to include plural forms, and unless the context clearly indicates otherwise, "a plurality" generally includes at least two.

[0039] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0040] It should be understood that although the terms first, second, third, etc. may be used to describe in the embodiments of the present application, these should not be limited to these terms. These terms are only used to distinguish. For example, without departing from the scope of the embodiments of the present application, the first may also be referred to as the second, and similarly, the second may also be referred to as the first.

[0041] It should also be noted that the terms "include," "comprises," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a product or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such product or device. In the absence of further limitations, an element defined by the phrase "comprising a" does not exclude the presence of other identical elements in the product or device comprising the element.

[0042] In the aerospace field, a satellite's momentum and reaction wheels are typically mounted on a support system to mitigate the effects of vibrations generated by the source on the satellite's attitude control and instrument imaging. When subjected to the source's perturbation forces, the support system can experience coupled vibrations in multiple modes, leading to attitude control errors, image blur, and other issues, impacting mission success and data quality. Therefore, analyzing the perturbation forces on the support system helps predict and control these dynamic responses, optimize the satellite's support structure, and minimize the impact of vibration on attitude control.

[0043] The following is combined with Figure 1-4Alternative embodiments of the present invention are described in detail.

[0044] According to a specific embodiment of the present invention, the present invention provides a force measurement system with weak rigidity support, such as Figure 1-Figure 2 The overall structural diagram shown includes:

[0045] The support mechanism is used to support the vibration source 1, which is suspended from the rigid boundary via a first elastic rope 41. The support mechanism includes a load platform 3 and a rigid support 2. The lines connecting the vertices on the load plane of the rigid support 2 form a regular polygon. The cross-section of the load platform 3 is the same as the load plane, and the load platform 3 is parallel to the load plane.

[0046] The rigid support 2 includes multiple support columns 21 and support beams 22. The plane formed by the multiple support beams 22 is the load plane. The cross-section of the load platform 3 is the same as the load plane, both of which are regular polygons. The regular polygon design enables multi-dimensional force measurement without redesigning the flexible structure. Examples of regular polygons include regular quadrilaterals, regular pentagons, regular hexagons, regular heptagons, or regular octagons.

[0047] In an optional embodiment of the present invention, the cross-sections of the load plane and the load platform 3 are both regular hexagons.

[0048] The elastic force measuring mechanism includes a plurality of second elastic ropes 42 and a plurality of sensor assemblies 5. The plurality of second elastic ropes 42 are respectively connected to the load plane and each vertex of the load platform 3, and the plurality of sensor assemblies 5 are respectively arranged on the plurality of second elastic ropes 42. In response to the vibration of the vibration source 1, the plurality of second elastic ropes 42 produce elastic deformation, and the plurality of sensor assemblies 5 respectively obtain the disturbance force parameters of the plurality of second elastic ropes 42 based on the elastic deformation.

[0049] Specifically, the elastic force-measuring mechanism includes a sensor assembly 5 and second elastic cords 42 connected at both ends of the sensor assembly 5. The other ends of the second elastic cords 42 are connected to a vertex of the regular hexagonal rigid support and a vertex of the regular hexagonal load platform 3, respectively. The connected elastic force-measuring mechanism is axially symmetrical with respect to the load platform.

[0050] Furthermore, when the vibration source 1 is set on the load platform 3 and generates vibration, the load platform 3 will generate disturbances within a certain range due to the elastic deformation of the second elastic rope 42. Figure 2 With the vibration source 1 as the center, the multiple sensor components 5 are used to obtain the disturbance force parameters along the axis of the elastic rope, and based on this, multi-dimensional disturbance force parameters in multiple directions are obtained.

[0051] Furthermore, the sensor assembly 5 includes a single force sensor and a displacement sensor. Therefore, the single force sensor can be used to obtain the bearing force on the second elastic cord 42 along the extension and contraction direction of the second elastic cord 42, while the displacement sensor can be used to obtain the displacement of the second elastic cord 42 along the extension and contraction direction.

[0052] In an optional embodiment of the present invention, the elastic force measuring mechanism is connected to the rigid support 2 via a pre-tightening assembly. A plurality of pre-tightening assemblies can be provided at each vertex of the rigid support 2, and the length of the second elastic cord 42 can be adjusted by the pre-tightening assemblies.

[0053] Specifically, such as Figure 3 As shown, the pretensioning assembly includes a control motor 71 and a winding reel 72. The second elastic cord 42 is wound around the winding reel 72. The control motor 71 drives the winding reel 72 to rotate and adjust the length of the second elastic cord 42. Compared to traditional systems that adjust system stiffness by adjusting and replacing boundary elements, this method avoids the complexity of manual operation and improves adjustment efficiency. Furthermore, it enables stepless adjustment of the flexible boundary based on the required stiffness of the force measurement system.

[0054] In other optional embodiments, the length of the second elastic cord 42 can be adjusted by a remotely controlled pre-tightening assembly to match the stiffness requirement of the force measurement system.

[0055] A solving unit calculates the moments of the load platform in the directions of the three coordinate axes in a spatial rectangular coordinate system according to the disturbance force parameters.

[0056] That is, the components of the three coordinate axes of the load platform 3 in the spatial rectangular coordinate system and the distance from the resultant point to the center point of the load platform 3 are calculated based on the disturbance force parameters; the torque of the load platform 3 in the three coordinate axes in the spatial rectangular coordinate system is calculated based on the distance to the center point and the components of the three coordinate axes.

[0057] Specifically, a spatial rectangular coordinate system is established based on the load plane and the direction of gravity. By acquiring data from each individual force sensor and displacement sensor, the bearing force on the second elastic cord 42 along each elastic cord's extension and contraction direction can be calculated. The bearing force of each elastic cord is projected onto the three coordinate axes of the spatial rectangular coordinate system. The bearing force components along each coordinate axis are then summed to determine the force components of the force measurement system along the three coordinate axes in the spatial rectangular coordinate system.

[0058] Furthermore, software can be used to obtain the position of the resultant force point after the second elastic rope 42 is stretched and retracted, as well as the distance from the resultant force point to the center point of the load platform carrying the vibration source, and the torque of the load platform in the x-axis direction, y-axis direction and z-axis direction in the spatial rectangular coordinate system can be further calculated based on the torque formula.

[0059] Insufficient torsional stiffness during measurement due to the flexible boundary can seriously affect the measurement results. As an optional embodiment, the force measurement system of the present invention further includes a torque compensation mechanism. The torque compensation mechanism includes multiple torque constraint sensors 6 and multiple third elastic cords 43. The multiple torque constraint sensors 6 are respectively disposed on the third elastic cords 43. Each of the third elastic cords 43 has two ends connected to two adjacent second elastic cords 42. The multiple third elastic cords 43 together form the regular polygon.

[0060] Specifically, such as Figure 2 As shown, the third elastic cord 43 is connected to the second elastic cords 42 in two adjacent elastic force-measuring mechanisms. Multiple third elastic cords 43 are connected end-to-end, forming a regular hexagon with the same cross-section as the load platform. By acquiring and fitting data from the six torque constraint sensors 6, the torque compensation value in the direction of gravity can be calculated. Combined with the load platform's torque in the direction of gravity in a three-dimensional rectangular coordinate system, the final torque is obtained.

[0061] Compared to the conventional method of compensating torque by adding a rigid auxiliary bracket, this embodiment compensates for the insufficient torque constraint caused by the flexible boundary by adding a torque constraint sensor. Combined with the tension data of the second elastic cord, the measurement error is corrected using the torque balance equation.

[0062] The following is based on Figure 4 The process shown, combined with Figure 1-Figure 2 The force measuring system of the weak rigidity support of the present invention is used to measure the vibration of the aerospace momentum wheel, and obtains the force components of the force measuring system on the three coordinate axes in the spatial rectangular coordinate system. and , the torque in the three coordinate axis directions and The method of six-dimensional force data is explained as follows:

[0063] Step S101: Fix the momentum wheel on the load platform. The momentum wheel is suspended on the rigid boundary above the rigid support 2 through four first elastic ropes 41. The load platform is connected to the rigid support through symmetrically arranged elastic force measuring mechanisms.

[0064] The momentum wheel is suspended from a rigid boundary above the rigid support via a first elastic rope 41, achieving a flexible connection in the direction of gravity. The load plane and load platform, formed by the crossbeams of the rigid support, both have regular hexagonal cross-sections. The load platform is aligned with the center of the rigid support's load plane via an elastic force-measuring mechanism, ensuring uniform force across the elastic force-measuring mechanisms and resetting the force-measuring system to its initial state.

[0065] Step S102: Adjust the length of the second elastic rope of the elastic force measuring mechanism so that the force measuring system meets the system stiffness requirements of the momentum wheel test, and obtain the single force sensor measurement data of each sensor assembly. and displacement sensor measurement data .in, i Indicates the sensor component number.

[0066] Specifically, by using six symmetrically arranged sensor components, six groups of bearing forces on each second elastic rope in six directions can be obtained, with the momentum wheel and the load platform as the center. And displacement data in six directions .

[0067] Step S102-1, calculating the stiffness of the force measurement system according to the data of the sensor assembly.

[0068] First, a spatial rectangular coordinate system is established with any beam on the rigid support as the y-axis direction, a vertex connecting the beam and the load platform as the origin, the direction perpendicular to the beam on the load plane as the z-axis direction, and the direction of gravity as the positive x-axis direction. Decomposing in the x-axis direction, y-axis direction and z-axis direction, the bearing force of each second elastic rope in the three coordinate axis directions in the spatial rectangular coordinate system can be obtained. , i =1~6. Among them, the angle between the second elastic rope and the x-axis is , No. i The angle between the projection of the second elastic rope on the yz plane and the y axis is . Among them, each angle Can be the same or different.

[0069] Similarly, the displacement data obtained by each displacement sensor By decomposing in the x-axis direction, y-axis direction and z-axis direction, the displacement of each second elastic rope in the three coordinate axis directions in the spatial rectangular coordinate system can be obtained respectively. .

[0070] Specifically, the bearing capacity data of the second elastic rope obtained by six single force sensors Respectively expressed as: and .by Figure 2 As an example, for any load Decomposing in the x-axis direction, y-axis direction and z-axis direction, the bearing force in the three directions can be expressed as:

[0071]

[0072]

[0073]

[0074] Thus, the component forces of the load platform in the x-axis direction, y-axis direction and z-axis direction of the spatial rectangular coordinate system are obtained, which can be expressed as:

[0075] 、 、 。

[0076] Similarly, the displacement data of the second elastic rope obtained by the six displacement sensors , for any load Decomposing in the x-axis direction, y-axis direction and z-axis direction, the displacement force in the three directions can be expressed as:

[0077]

[0078]

[0079]

[0080] Thus, the average displacement of the load platform in the x-axis direction, y-axis direction and z-axis direction is obtained 、 , expressed as:

[0081]

[0082]

[0083]

[0084] in, n is the number of sensor components. In this embodiment, n =6.

[0085] Then the stiffness of the force measurement system in the x-axis direction, y-axis direction and z-axis direction in the spatial rectangular coordinate system are expressed as:

[0086] 、 、 .

[0087] Step S102-2: Based on the calculated stiffness of the force measurement system in each direction, the length of each second elastic rope is adjusted to meet the known test stiffness requirement.

[0088] The known test stiffness is obtained by measuring the actual conditions of the product under test in an assembly environment, for example, through software simulation or actual measurement. The stiffness requirements of the product under test in an assembly environment are obtained in real time through the above steps. The stiffness of the force measurement system in the x-axis, y-axis, and z-axis directions in a spatial rectangular coordinate system is then obtained in real time. The stiffness of the force measurement system is adjusted using a preload assembly until it meets the target stiffness requirements. The force components in the x-axis, y-axis, and z-axis directions of the spatial rectangular coordinate system at this point in time are then determined as the final target force component data.

[0089] Step S103: Obtain the resultant force point of the load platform in the three-dimensional rectangular coordinate system and the distance from the resultant force point to the center point of the load platform, and combine the measurement data of the single force sensor and the displacement sensor to obtain the torque in three directions of the vibration source to be measured in the three-dimensional rectangular coordinate system.

[0090] The steps include: step S103-1, recalculating the components of the load platform in the x-axis direction, y-axis direction and z-axis direction after the stiffness is adjusted to the preset value; and .

[0091] Step S103-2: The software can be used to obtain the position of the resultant force point after the second elastic rope is stretched and the distance from the resultant force point to the center point of the load platform carrying the vibration source. L , combined with the force component obtained in step S103-1 and The torque formula is used to further calculate the torque of the load platform in three directions in the three-dimensional rectangular coordinate system. It can be expressed as:

[0092] 、 、 .

[0093] In summary, the force components of the force measuring system on the three coordinate axes in the spatial rectangular coordinate system are obtained and , and the moments in the three coordinate axes and Six-dimensional force data.

[0094] In other optional embodiments, since insufficient torsional stiffness during measurement due to the flexible boundary may seriously affect the measurement result, the method further includes a step of torque compensation:

[0095] Step S104 : Compensating the moment in the gravity direction in the spatial rectangular coordinate system according to the data of the moment constraint sensor.

[0096] Specifically, set i The data returned by the torque constraint sensor is , then the compensation torque in the direction of gravity is:

[0097]

[0098] in, n is the number of torque constraint sensors, n =6; R is the distance between the known torque constraint sensor and the torsion center.

[0099] Therefore, the moment in the direction of gravity after compensation is: Similarly, the torque in other directions can be compensated.

[0100] This invention utilizes an elastic force-measuring mechanism to establish a flexible boundary, effectively isolating environmental noise interference and improving measurement accuracy. Adjusting the length of the elastic cord allows simulation of any system stiffness, and the simulated flexible boundary is infinitely adjustable within the designed stiffness range. Through multi-dimensional force measurement and torque compensation, the device achieves ideal simulation results for the object under test, making it suitable for applications in aerospace, precision manufacturing, and other fields.

[0101] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. References to the common and similar parts between the various embodiments will be sufficient. For the systems or devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, their descriptions are relatively simple; for relevant details, refer to the descriptions of the methods.

[0102] The above embodiments are only used to illustrate the technical solutions disclosed in the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments disclosed in the present invention.

Claims

1. A force measurement system with weak rigidity support, characterized in that: include: A bearing mechanism for bearing a vibration source, wherein the bearing vibration source is suspended from a rigid boundary via a first elastic rope, the bearing mechanism comprising: a load platform and a rigid support, the rigid support having a regular polygonal load plane, the cross-section of the load platform being the same as the shape of the load plane, and the load platform being parallel to the load plane; an elastic force measuring mechanism comprising a plurality of second elastic cords and a plurality of sensor assemblies, wherein the plurality of second elastic cords are respectively connected to the load plane and each vertex of the load platform, and the plurality of sensor assemblies are respectively disposed on the plurality of second elastic cords. In response to vibration of the vibration source, the plurality of second elastic cords are elastically deformed, and the plurality of sensor assemblies respectively obtain disturbance force parameters of the plurality of second elastic cords based on the elastic deformation; A solving unit, which calculates the moments of the load platform in the directions of three coordinate axes in a spatial rectangular coordinate system according to the disturbance force parameters; The torque compensation mechanism includes: a plurality of torque constraint sensors and a plurality of third elastic ropes, wherein the plurality of torque constraint sensors are respectively disposed on the third elastic ropes; the two ends of each third elastic rope are respectively connected to two adjacent second elastic ropes, and the plurality of third elastic ropes together form the regular polygon; a compensation calculation unit, configured to calculate a compensation torque in the direction of gravity based on data from the plurality of torque constraint sensors; The torque obtained by the solving unit is combined with the compensation torque to obtain the final torque.

2. The force measurement system with weak rigidity support according to claim 1, characterized in that: Each of the sensor components includes: a single force sensor and a displacement sensor.

3. The force measurement system with weak rigidity support according to claim 1, characterized in that: Also includes: A pre-tightening component is connected to the second elastic rope, and the disturbing force parameter is adjusted by adjusting the length of the second elastic rope so that the stiffness of the elastic force measuring mechanism meets a preset value.

4. The force measurement system with weak rigidity support according to claim 3, characterized in that: The pre-tightening assembly includes: a control motor and a winding wheel, and the control motor is used to drive the winding wheel to rotate to adjust the length of the second elastic rope.

5. The force measurement system with weak rigidity support according to claim 1, characterized in that: The regular polygon is a regular quadrilateral-regular octagon.

6. The force measurement system with weak rigidity support according to claim 1, characterized in that: The torque of the load platform in three directions in the spatial rectangular coordinate system is expressed as: 、 、 ； in, L is the distance from the resultant force point to the center point of the load platform; and They respectively represent the components of force on the load platform in the x, y, and z directions after adjusting the stiffness.

7. The force measurement system with weak rigidity support according to claim 6, characterized in that: The torque expression for compensation in the gravity direction is: in, n is the number of torque constraint sensors; For the i data returned by the torque constraint sensor; R is the distance between the known torque constraint sensor and the torsion center.

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