Hollow multi-dimensional force sensor and measuring method thereof

Abstract

The invention belongs to the technical field of sensors for force detection, and particularly relates to a hollow multi-dimensional force sensor and a measuring method thereof, and the force sensor comprises an elastic body, a top end fixing piece, a connecting piece, a base, an optical fiber and a connecting medium. Wherein the elastic body comprises a plurality of flexible beam structures, and the flexible beam structures are uniformly distributed along the circumference. And the elastic body is fixed with the middle support through the connecting piece to form a multi-layer parallel structure. The optical fiber is fixed on the elastic body and the base. When the sensor is stressed, the elastic body deforms to cause stretching or contraction of the internal optical fiber, so that the reflection wavelength of the grating point is changed. The magnitude and the direction of the acting force are obtained by measuring and analyzing the light reflection wavelength and combining a measuring method. The device has the advantages of being large in hollow instrument channel, compact in structure, wide in measurement range, high in linearity, simple and reliable in structure, resistant to electromagnetic interference and the like, the device can be conveniently integrated into an instrument, and accurate multi-dimensional force sensing is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of force detection sensors, and specifically relates to a hollow multi-dimensional force sensor and a measurement method thereof, which can be used in situations where multi-dimensional force detection is required, such as in the fields of medical devices and the like. Background Art

[0002] Minimally invasive interventional surgery has been widely used in clinical practice due to its significant advantages such as small trauma, fast recovery, and low risk of infection. This type of surgery achieves precise treatment of target lesions through small abdominal incisions or through the natural cavity of the human body. However, due to the long rod of the surgical instrument or the soft surgical catheter, and the complex and curved path in the body, it is difficult for doctors to truly feel the force at the end of the instrument, which greatly increases the difficulty and risk of operation. In recent years, breakthroughs in surgical robot technology have provided a new solution for surgical operations, which has the advantages of high dexterity, high-precision positioning, and remote control. However, the existing master-slave control system generally lacks an accurate force feedback mechanism, cutting off the doctor's intuitive perception, which not only increases the risk of complications such as bleeding and perforation, but may also lead to functional failure. As surgical robots develop towards autonomy, accurate force perception has become a key factor in ensuring surgical safety and operational flexibility.

[0003] To address this challenge, researchers have tried to directly integrate various sensor units at the distal end of the instrument to detect tiny strains. Common technologies include strain gauges, MEMS (micro-electromechanical systems), capacitive sensors, and Bragg fiber gratings (FBGs). Among them, FBGs have unique advantages such as small size, anti-electromagnetic interference, and high-temperature sterilization, and are widely used in the field of surgical force sensing. For sensor design, the design of the elastic structure is particularly important, which directly determines the sensor performance and its adaptability to surgical instruments. In particular, the balanced design of the elastic body stiffness can effectively reduce the stiffness matrix condition number of the sensor. A lower matrix condition number can not only effectively suppress the amplification of measurement noise and system errors, but also balance the sensitivity of each measurement axis, thereby improving the accuracy and performance of the sensor. However, it is still difficult to integrate multi-dimensional precise force sensing on surgical instruments. Some existing solutions use complex structures to achieve decoupling of axial force measurement and radial force measurement. These structures are often difficult to process, too large in size, and occupy the middle channel of the instrument. Considering the limited surgical operation space in the human body, the practical application of these solutions in miniaturized surgical instruments is greatly limited. Summary of the invention

[0004] In view of the problem that the prior art lacks accurate force feedback in minimally invasive surgery, the purpose of the present invention is to provide a hollow multi-dimensional force sensor and a measurement method thereof. The sensor has a hollow instrument channel, a compact structure and high precision, which improves the safety and treatment effect during robot-assisted diagnosis and treatment. The present invention realizes highly sensitive force sensing feedback based on the mutual cooperation of Bragg fiber grating and force-sensing elastomer. When an external force acts on the force-sensing structure, the structure undergoes a slight deformation, causing the internal optical fiber to stretch or compress. By accurately detecting the change in the wavelength of the reflected light and combining the force measurement method, information such as the direction and magnitude of the force can be accurately obtained.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] The hollow multi-dimensional force sensor of the present invention includes optical fiber, and also includes an elastomer, a connector and a base, wherein the elastomer is multi-layered, and adjacent elastomers are connected by connectors, the interior of each layer of the elastomer is fixed to the same base for connecting the instrument rod, the exterior of each layer of the elastomer and the connector can be deformed under the action of external force, and the interior and exterior of each layer of the elastomer are connected by a flexible deformation beam that can be deformed; optical fiber is penetrated inside the elastomer, the connector and the base.

[0007] Wherein: each layer of the elastomer is ring-shaped, the inner ring is the inside of the elastomer, and the outer ring is the outside of the elastomer, one end of the flexible deformation beam is fixedly connected to the inner ring of the elastomer or is an integral structure, the other end of the flexible deformation beam is fixedly connected to the outer ring of the elastomer or is an integral structure, and the other end of the flexible deformation beam is provided with a structure for fixing the optical fiber, and the structure and foundation for fixing the optical fiber are used to fix the optical fiber that can be deformed.

[0008] There are multiple flexible deformation beams, which are distributed at equal angles along the axis of the force sensor. The flexible deformation beams are arc-shaped beams or straight beams. The structure for fixing the optical fiber is a connecting medium, and an optical fiber fixing hole or a connecting groove is opened at the other end of the flexible deformation beam.

[0009] The foundation is a base with a hollow structure, one end of the base is larger than the other end, thereby forming a deformation boss between the two ends, and the other end with a smaller size is an intermediate support for fixing the inside of each layer of elastomer; the end of the base with a larger size is provided with an optical fiber fixing hole for fixing the optical fiber; the optical fiber is divided into strain optical fiber and temperature optical fiber, the strain optical fiber is respectively fixed to the foundation and the last layer of elastomer, and the temperature optical fiber is only fixed to the foundation, and the strain optical fiber and the temperature optical fiber have no contact with the remaining layers of elastomer except the last layer of elastomer, and a gap is left.

[0010] The hollow multi-dimensional force sensor of the present invention includes an optical fiber, an elastomer and a base, wherein there is one elastomer, the interior of the elastomer is fixed to the base, the exterior of the elastomer can be deformed under the action of external force, grooves are cut on the side walls of the elastomer to form a flexible deformation beam, the interior and exterior of the elastomer are connected by a flexible deformation beam that can be deformed; optical fibers are passed through the interior of the elastomer and the base.

[0011] Among them: the elastomer is a hollow sidewall grooved elastomer, and a plurality of layers of grooves are cut along the axial direction on the side wall, and the number of grooves in each layer is two that are not cut through in the circumferential direction, and the flexible deformation beam is formed between the two grooves, and one end of the flexible deformation beam is provided with an elastomer support as the inside of the sidewall grooved elastomer, and the elastomer support realizes a stable connection between the sidewall grooved elastomer and the base; each layer of the flexible deformation beam is also connected to a plurality of optical fiber fixing seats for fixing optical fibers.

[0012] The foundation is a base with a hollow structure, one end of the base is larger than the other end, thereby forming a deformation boss between the two ends, and the other end with a smaller size is an intermediate support member for fixing the inside of the elastomer, and the intermediate support member and the flexible deformation beam are both provided with a connecting groove; the end of the base with a larger size is provided with an optical fiber fixing hole for fixing the optical fiber; a gap is left between the side wall grooved elastomer and the end of the base with a larger size; the optical fiber is divided into strain optical fiber and temperature optical fiber, the strain optical fiber is respectively fixed to the foundation and the side wall grooved elastomer, and the temperature optical fiber is only fixed to the foundation.

[0013] The measuring method of the hollow multi-dimensional force sensor of the present invention comprises the following steps:

[0014] When the force sensor is subjected to an axial force, the outside of the elastic body is axially offset; the optical fiber segment between the elastic body and the base is deformed, so that the grating pitch on the optical fiber segment changes, and then the grating reflection wavelength inside the optical fiber segment changes;

[0015] When the force sensor is subjected to radial force, the outside of the elastic body is deformed or the outside of the elastic body and the connecting piece are deformed as a whole, and the optical fiber segment between the elastic body and the base is deformed, so that the grating pitch on the optical fiber segment changes, and then the grating reflection wavelength inside the optical fiber segment changes;

[0016] The magnitude and direction of the force are calculated based on the change in the reflected wavelength through measurement methods.

[0017] Wherein: the magnitude and direction of the force are obtained by measuring the change of the reflected wavelength, including the following steps:

[0018] According to the obtained multiple real force reference values, they are applied to the hollow multi-dimensional force sensor; when the hollow multi-dimensional force sensor is subjected to forces of different directions and magnitudes, the optical fiber wavelength change value corresponding to the real force reference value is collected;

[0019] After removing the temperature influence from the optical fiber wavelength change value, the value is used as the input data of the random forest model, and the obtained real force reference value is used as the output data of the random forest model. The mapping relationship between the optical fiber wavelength change value and the applied force is obtained through model training.

[0020] When using a hollow multi-dimensional force sensor for measurement, the magnitude and direction of the force can be obtained based on the change in reflection wavelength and the mapping relationship between the optical fiber wavelength change value and the force.

[0021] The optical fiber wavelength variation value is obtained by removing the temperature influence through the following formula:

[0022] [Δλ 1F Δλ 2F Δλ 3F ] T =[Δλ1Δλ2Δλ3] T -[k 1T k 2T k 3T ] T Δλ4

[0023] Among them, Δλ iF k is the wavelength change of the ith optical fiber caused by external force after removing the temperature effect, iT is the temperature correlation coefficient between the i-th strain measuring fiber and the temperature measuring fiber, i = 1, 2, 3; Δλ j is the total wavelength change of the j-th optical fiber caused by external force and temperature, j = 1, 2, 3, 4.

[0024] The advantages and positive effects of the present invention are:

[0025] 1. The force sensor of the present invention has the characteristics of a hollow channel, a compact structure and high-precision measurement. Specifically: the components of the force sensor have a simple structure and high reliability, which is conducive to mass production and convenient installation. The hollow structure design provides a larger instrument channel, which can be adapted to various types of surgical instruments, such as coaxial interventional instruments, instruments requiring intermediate drive devices, and instruments that can pass through other sensors. The compact structural design enables surgical instruments to be flexibly operated in narrow human cavities, improving the operability of the operation. The high-precision and high-resolution performance characteristics enable the sensing unit to provide accurate force feedback during the soft tissue interaction process, effectively improving the safety and accuracy of the operation. Through the compensation mechanism of the temperature optical fiber, the influence of temperature drift on the measurement accuracy of the sensor is effectively eliminated, further improving the reliability of the measurement.

[0026] 2. The present invention adopts an innovative measurement method, specifically: using the random forest (RF) model to calibrate the sensor, which can effectively handle the nonlinear characteristics of the sensor. Through training with a large amount of calibration data, the method can establish an accurate mapping relationship between the optical fiber wavelength change value and the force data. This measurement method significantly improves the measurement accuracy of the sensor, enabling it to adapt to complex surgical environments and diverse operation requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of a three-dimensional structure of an integrated force sensor and an apparatus according to a first embodiment of the present invention;

[0028] Figure 2 This is a front view of the structure of the force sensor and the device integrated in the first embodiment of the present invention;

[0029] Figure 3 A top view of the structure of the force sensor and the device integrated in the first embodiment of the present invention;

[0030] Figure 4 for Figure 3 A-A section view in FIG.

[0031] Figure 5A is a schematic diagram of the three-dimensional structure of a force sensor according to the first embodiment of the present invention;

[0032] Figure 5B It is a schematic diagram of the three-dimensional structure of the force sensor according to the first embodiment of the present invention without the connecting piece;

[0033] Figure 5C It is a schematic diagram of the structure of the force sensor according to the first embodiment of the present invention;

[0034] Figure 6 A top view of the structure of the force sensor according to the first embodiment of the present invention;

[0035] Figure 7 It is a structural schematic diagram of a base in a force sensor according to the first embodiment of the present invention;

[0036] Figure 8 is a schematic diagram of the three-dimensional structure of a force sensor according to the second embodiment of the present invention;

[0037] Fig. 9 is a schematic diagram of the three-dimensional structure of a force sensor according to Embodiment 3 of the present invention;

[0038] Fig. 10A is a schematic diagram of the three-dimensional structure of a force sensor according to a fourth embodiment of the present invention;

[0039] Fig. 10B It is a top view of the structure of the force sensor according to the fourth embodiment of the present invention;

[0040] Fig. 10C This is a schematic structural diagram of a sidewall grooved elastic body in a force sensor according to a fourth embodiment of the present invention;

[0041] Fig. 10D Schematic diagram of the structure of a base in a force sensor according to a fourth embodiment of the present invention;

[0042] Among them: 1 is the end effector, 2 is the force sensor, 3 is the instrument rod, 201 is the top fixing part, 202 is the upper elastic body, 203 is the connecting part, 204 is the lower elastic body, 205 is the base, 2061 is the first optical fiber, 2062 is the second optical fiber, 2063 is the third optical fiber, 2064 is the fourth optical fiber, 207 is the middle supporting part, 208 is the upper connecting medium, 209 is the lower connecting medium, 210 is the first connecting part, 211 is the middle elastic body, 212 is the second connecting part, 213 is the optical fiber fixing seat, 214 is the elastic body supporting part, 215 is the side wall grooved elastic body, 216 is the deformation boss, 217 is the strain optical fiber fixing hole A, 218 is the temperature optical fiber fixing hole, 219 is the strain optical fiber fixing hole B, 220 is the flexible beam, 221 is the straight beam, and 222 is the connecting groove. DETAILED DESCRIPTION

[0043] The present invention will be further described below in conjunction with the accompanying drawings.

[0044] Embodiment 1

[0045] In this embodiment, the multi-dimensional force sensor 2 is integrated into the surgical instrument. Figures 1 to 7 As shown, the end effector 1 is integrated at the end of the force sensor 2, and is used to directly contact the tissue and transmit the force to the force sensor 2. The end effector 1 can be a contact or a surgical forceps or other instruments; the instrument rod 3 is connected to the head end of the force sensor 2, and the instrument rod 3 can be a rigid straight rod of a surgical instrument, a soft catheter, etc. The hollow instrument channel of the force sensor 2 is convenient for the guide wire, instrument drive device, other sensors, etc. to pass through.

[0046] The shape of the force sensor 2 can be circular or square. The force sensor 2 of this embodiment is circular. The force sensor 2 includes an elastic body, a connector 203, a base and an optical fiber. The elastic body is multi-layered. Adjacent elastic bodies are connected by connectors 203. The inside of each layer of elastic body is fixed to the same base for connecting the instrument rod 3. The inside and outside of each layer of elastic body are connected by a flexible deformation beam 220. The flexible deformation beam 220 can be deformed sensitively after being subjected to force. Under the deformation of the flexible deformation beam 220, the outside of each layer of elastic body and the connector 203 can be deformed under the action of external force; optical fibers are penetrated in the elastic body, the connector 203 and the base. When the force sensor 2 is subjected to external force, the force starts from the top layer of elastic body, and is transmitted downward in sequence through the outside of each layer of elastic body and the connector 203, while the internal structure of each layer of elastic body remains relatively fixed; the overall structure forms a multi-layer parallel configuration.

[0047] The elastic body of this embodiment is composed of two layers, namely, the upper elastic body 202 and the lower elastic body 204. The end effector 1 is integrated on the upper elastic body 202. A connector 203 is provided between the upper elastic body 202 and the lower elastic body 204. The connector 203 is used to connect the outer rings of the upper elastic body 202 and the lower elastic body 204. The foundation of this embodiment is a base 205 with a hollow structure. The size of one end of the base 205 is larger than the other end, and a deformation boss 216 is formed between the two ends. The other end with a small size is an intermediate support 207 for fixing the upper elastic body 202 and the lower elastic body 204. The end with a large size of the base 205 is provided with an optical fiber fixing hole for fixing the optical fiber. The instrument rod 3 is connected to the end with a large size of the base 205. The design of the deformation boss 216 and the optical fiber fixing hole is used to ensure that when the force sensor is subjected to force, the upper elastic body 202 and the lower elastic body 204 have a certain deformation space when they are deformed. The upper elastic body 202, the connecting member 203, the lower elastic body 204 and the base 205 of this embodiment are all hollow structures and are bonded in sequence.

[0048] The upper elastic body 202 and the lower elastic body 204 of this embodiment are both annular, the inner ring is the inside of the upper elastic body 202 and the lower elastic body 204, and the outer ring is the outside of the upper elastic body 202 and the lower elastic body 204. The inner ring of the upper elastic body 202 and the inner ring of the lower elastic body 204 are fixed on the middle support member 207 to form a stable internal support structure; a plurality of flexible deformation beams 220 are arranged along the circumferential direction between the inner ring and the outer ring, and each flexible deformation beam 220 is distributed at equal angles along the axis of the axis of the force sensor 2; the flexible deformation beam 220 of this embodiment is an arc beam, and the flexible deformation beam 220 and the inner ring and the outer ring are all hollow structures. One end of each flexible deformable beam 220 on the upper elastic body 202 is fixedly connected to the inner ring or is an integral structure, and the other end of each flexible deformable beam 220 on the upper elastic body 202 is fixedly connected to the outer ring or is an integral structure. The other end of each flexible deformable beam 220 on the upper elastic body 202 is provided with a structure for fixing the optical fiber, and the structure and foundation for fixing the optical fiber (i.e., the end with a larger size of the base 205) are used to fix the optical fiber that can be deformed. One end of each flexible deformable beam 220 on the lower elastic body 204 is fixedly connected to the inner ring or is an integral structure, and the other end of each flexible deformable beam 220 on the lower elastic body 204 is fixedly connected to the outer ring or is an integral structure, and a space is left for the optical fiber to pass through. There are three flexible deformable beams 220 in this embodiment, and accordingly, there are also three optical fibers that can be deformed.

[0049] In this embodiment, the structure for fixing the optical fiber is a connecting medium. The other end of each flexible deformation beam 220 on the upper elastic body 202 is provided with an upper connecting medium 208, and the optical fiber fixing hole on the base 205 is provided with a lower connecting medium 209. The upper connecting medium 208 and the lower connecting medium 209 of this embodiment can be high-strength adhesives, epoxy resins, or in the form of capillary steel tube welding.

[0050] The optical fiber of this embodiment is divided into strain optical fiber and temperature optical fiber. There are three strain optical fibers, namely the first optical fiber 2061, the second optical fiber 2062 and the third optical fiber 2063, and one temperature optical fiber, namely the fourth optical fiber 2064. Accordingly, four optical fiber fixing holes are opened on the larger end of the base 205, namely three strain optical fiber fixing holes A217 and one temperature optical fiber fixing hole 218. In order to accurately and sensitively detect the strain of the optical fiber, the first optical fiber 2061, the second optical fiber 2062 and the third optical fiber 2063 pass through the three strain optical fiber fixing holes A217 respectively, and then pass through the lower elastic body 204 and the upper elastic body 202 in sequence. The fourth optical fiber 2064 passes through the temperature optical fiber fixing hole 218 and then passes through the lower elastic body 204. One end of the first optical fiber 2061, the second optical fiber 2062 and the third optical fiber 2063 are respectively fixed to the upper connection medium 208 on the three flexible deformation beams 220 of the upper elastic body 202, and the other ends of the first optical fiber 2061, the second optical fiber 2062 and the third optical fiber 2063 are respectively fixed to the lower connection medium 209 in the three strain optical fiber fixing holes A217 on the base 205; one end of the temperature optical fiber is located between the upper elastic body 202 and the lower elastic body 204, and the other end of the temperature optical fiber is only fixed to the lower connection medium 209 in the temperature optical fiber fixing hole 218 on the base 205. The three strain optical fibers and one temperature optical fiber all pass through the space reserved on the lower elastic body 204, and do not contact the lower elastic body 204, but leave a gap. This fixing method ensures that the optical fiber can accurately sense the deformation of the uppermost elastic body, while avoiding the interference of the remaining layers of elastic body on the optical fiber measurement, thereby improving the measurement accuracy and reliability of the force sensor. The strain optical fiber and temperature optical fiber of this embodiment are provided with Bragg gratings (FBG) on the section between the upper elastic body 202 and the base 205. The grating points of the Bragg grating on the strain optical fiber for detecting strain are located between the upper elastic body 202 and the lower elastic body 204. When subjected to external force, the wavelength of the grating points will change, which is used to calculate the magnitude of the external multi-dimensional force. The grating points of the Bragg grating on the temperature optical fiber for compensating for temperature changes are only fixed at one end on the temperature optical fiber fixing hole 218 of the base, which is used to detect the ambient temperature. The change of ambient temperature will affect the wavelength of the reflected light of the optical fiber. In order to ensure the accurate measurement of the external force by the force sensor, the ambient temperature needs to be compensated.

[0051] The upper elastic body 202 and the lower elastic body 204 of this embodiment can be made of superelastic materials (such as nickel-titanium alloy) so that they can easily deform after being subjected to force. Other connecting and fixing parts can be made of materials with greater rigidity (such as stainless steel) to ensure accurate force transmission. The structural design of this embodiment not only ensures the high sensitivity of the force sensor, but also realizes a compact hollow structure, meeting the dual needs of minimally invasive surgery for accurate force perception and instrument channels.

[0052] In this embodiment, a top fixing member 201 is provided at the top of the middle supporting member 207 . The top fixing member 201 is connected to the middle supporting member 207 or is an integral structure, and is used for axially limiting the upper elastic body 202 .

[0053] Embodiment 2

[0054] like Figure 8 As shown, the difference between this embodiment and the first embodiment is that the flexible deformation beam 220 of this embodiment is a straight beam 221, and the other ends of the three straight beams 221 are provided with strain fiber fixing holes B219. This structural design makes the overall rigidity larger, which can not only significantly improve the measurement range of the sensor, but also has better processing performance.

[0055] One end of the first optical fiber 2061, the second optical fiber 2062 and the third optical fiber 2063 of this embodiment is respectively fixedly connected to the upper connection medium 208 in the strain optical fiber fixing hole B219 on the three straight beams 221 of the upper elastic body 202, and the other ends of the first optical fiber 2061, the second optical fiber 2062 and the third optical fiber 2063 are respectively fixedly connected to the lower connection medium 209 in the three strain optical fiber fixing holes A217 on the base 205; one end of the temperature optical fiber is located between the upper elastic body 202 and the lower elastic body 204, and the other end of the temperature optical fiber is only fixedly connected to the lower connection medium 209 in the temperature optical fiber fixing hole 218 on the base 205. The three strain optical fibers and one temperature optical fiber all pass through the space reserved on the lower elastic body 204, and do not contact the lower elastic body 204, but leave a gap.

[0056] The rest is the same as that of the first embodiment.

[0057] Embodiment 3

[0058] like Fig. 9 As shown, the difference between this embodiment and the first embodiment is that the elastic body of this embodiment has three layers, namely, upper, middle and lower, which are upper elastic body 202, middle elastic body 211 and lower elastic body 204. The upper elastic body 202 and the middle elastic body 211 are connected by a first connecting member 210, and the middle elastic body 211 and the lower elastic body 204 are connected by a second connecting member 212, forming a multi-layer parallel structure, that is, the inner rings of the three-layer elastic body are fixed together on the same middle support member 207. This innovative design not only increases the overall stiffness of the force sensor, but also significantly improves the measurement range of the force sensor.

[0059] The advantages of the multi-layer parallel structure are mainly reflected in the following aspects: First, it can disperse the force more evenly, so that the stress on each layer of the elastomer is more balanced, greatly increasing the radial stiffness. The increased stiffness enables the force sensor to withstand greater external forces, expand the measurement range, and be suitable for a wider range of surgical scenarios. Finally, this structural design also enhances the overall stability of the force sensor, reduces the interference of environmental factors on the measurement results, and further improves the reliability of the measurement.

[0060] One end of the first optical fiber 2061, the second optical fiber 2062 and the third optical fiber 2063 of this embodiment is respectively fixed to the upper connection medium 208 at the other end of the three flexible deformation beams 220 of the upper elastic body 202, and the other ends of the first optical fiber 2061, the second optical fiber 2062 and the third optical fiber 2063 are respectively fixed to the lower connection medium 209 in the three strain optical fiber fixing holes A217 on the base 205; one end of the temperature optical fiber is located between the upper elastic body 202 and the middle elastic body 211, and the other end of the temperature optical fiber is only fixed to the lower connection medium 209 in the temperature optical fiber fixing hole 218 on the base 205. The three strain optical fibers and one temperature optical fiber all pass through the space reserved on the lower elastic body 204 and the middle elastic body 211, and do not contact the lower elastic body 204 and the middle elastic body 211, but leave a gap.

[0061] The rest is the same as that of the first embodiment.

[0062] Embodiment 4

[0063] This embodiment adopts an innovative integrated design, and performs precise cutting directly on the elastic body to form an elastic body structure with sidewall grooves. Specifically:

[0064] like Figures 10A to 10D As shown, the difference between this embodiment and embodiment 1 is that this embodiment has an elastomer, so there is no top fixing piece 201 and connecting piece 203; the elastomer of this embodiment is a hollow sidewall grooved elastomer 215, and a plurality of layers of grooves are cut along the axial direction on the side wall, and the number of grooves in each layer is two that are not cut through in the circumferential direction, and a flexible deformation beam 220 is formed between the two grooves, and an elastomer support 214 is provided at one end of the flexible deformation beam 220 as the inside of the sidewall grooved elastomer 215, and the elastomer support 214 realizes a stable connection between the sidewall grooved elastomer 215 and the middle support 207 on the base 205; each layer of the flexible deformation beam 220 is also connected to a plurality of optical fiber fixing seats 213 for fixing optical fibers.

[0065] The basis of this embodiment is a hollow structure base 205, one end of the base 205 is larger than the other end, thereby forming a deformation boss 216 between the two ends, and the other end with a smaller size is an intermediate support member 207 for fixing the inside of the side wall groove elastomer 215, and the intermediate support member 207 and the flexible deformation beam 220 are both provided with a connecting groove 222; the end with a larger size of the base 205 is provided with an optical fiber fixing hole for fixing the optical fiber; a gap is left between the side wall groove elastomer 215 and the end with a larger size of the base 205.

[0066] The sidewall grooved elastic body 215 of this embodiment is cylindrical, and two layers of grooves are cut at the upper and lower ends of the sidewall of the sidewall grooved elastic body 215. Each layer of grooves is three groups evenly arranged along the circumferential direction. Each group has two upper and lower grooves that are not cut through along the circumferential direction, that is, one end of the upper and lower grooves of each group is connected and the other end is not connected; a flexible deformation beam 220 is formed between the upper and lower grooves of each group, and a connecting groove 222 is provided near the connecting end of the two grooves of each flexible deformation beam 220. There are six connecting grooves 222 on the sidewall grooved elastic body 215, and three connecting grooves 222 on the upper and lower ends of the intermediate support member 207 (a total of six) correspond to each other. The two ends of each elastic body support member 214 are respectively located in the connecting grooves 222 on the flexible deformation beam 220 and the connecting grooves 222 on the intermediate support member 207. A hole for installing the optical fiber fixing seat 213 is provided on the side wall between two adjacent groups. In this embodiment, the strain optical fiber is fixedly connected to the optical fiber fixing base 213 and the base 205 , and the temperature optical fiber is only fixedly connected to the base 205 .

[0067] The rest is the same as that of the first embodiment.

[0068] The sidewall grooved elastic body 215 processed in an integrated manner in this embodiment significantly reduces the assembly requirements between parts and improves the overall stability and reliability of the force sensor. Multiple layers of flexible deformation beams 220 can be accurately cut on the sidewall grooved elastic body 215, and each layer of flexible deformation beams 220 is provided with a connection groove 222 for fixing and stress transmission of optical fibers. In addition, this embodiment realizes a stable connection between the sidewall grooved elastic body 215 and the intermediate support 207 of the base 205 through a carefully designed elastic body support 214. A certain gap is left between the lower end surface of the sidewall grooved elastic body 215 and the base 205. This connection method not only ensures the integrity of the structure, but also provides the necessary space for the deformation of the sidewall grooved elastic body 215. Finally, this embodiment introduces an optical fiber fixing seat 213 for reliably fixing the optical fiber on the sidewall grooved elastic body 215. This design not only simplifies the installation process of the optical fiber, but also improves the accuracy of the optical fiber position, thereby enhancing the measurement accuracy of the force sensor. This integrated design not only simplifies the structure of the force sensor, but also improves the overall assembly accuracy.

[0069] The measuring method of the hollow multi-dimensional force sensor of the present invention can accurately measure the magnitude and direction of the force acting on the force sensor. The specific steps are as follows:

[0070] Obtain force and wavelength changes. When the force sensor is subjected to axial force, the outside of the elastomer will be axially offset. This offset causes the fiber segment between the elastomer and the base to be stretched or compressed, causing the grating pitch inside the fiber segment to change, and then the grating reflection wavelength inside the fiber segment to change. When the force sensor is subjected to radial force, the outside of the elastomer will be deformed or the outside of the elastomer and the connector will be deformed as a whole. This deformation will also cause the fiber segment between the elastomer and the base to be stretched or compressed, causing the grating reflection wavelength to change.

[0071] Force calculation. The magnitude and direction of the force are calculated by measuring the change in the reflected wavelength, including the following steps:

[0072] a) Use standard force sensors or electronic scales and other measuring tools to obtain the true force reference value and direction;

[0073] b) When the hollow multi-dimensional force sensor is subjected to forces of different directions and magnitudes, the optical fiber wavelength change value corresponding to the real force reference value is collected;

[0074] c) removing the temperature influence from the optical fiber wavelength change value and using it as the input data of the random forest model, using the obtained real force reference value as the output data of the random forest model, and obtaining the mapping relationship between the optical fiber wavelength change value and the force through model training;

[0075] d) When using a hollow multi-dimensional force sensor for measurement, the magnitude and direction of the force can be obtained based on the change in reflection wavelength through the mapping relationship between the optical fiber wavelength change value and the force.

[0076] Temperature compensation is performed. The optical fiber wavelength change value is obtained by removing the temperature influence through the following formula:

[0077] [Δλ 1F Δλ 2F Δλ 3F ] T =[Δλ1Δλ2Δλ3] T -[k 1T k 2T k 3T ] T Δλ4

[0078] Among them, Δλ iF k is the wavelength change of the ith optical fiber caused by external force after removing the temperature effect, iTis the temperature correlation coefficient between the i-th strain measuring fiber and the temperature measuring fiber, i = 1, 2, 3; Δλ j is the total wavelength change of the jth optical fiber caused by external force and temperature, j = 1, 2, 3, 4. The temperature correlation coefficient k between the strain measurement optical fiber and the temperature measurement optical fiber iT , can be obtained through heating experiments and linear regression, thus achieving accurate temperature compensation.

Claims

1. A hollow multi-dimensional force sensor, comprising an optical fiber, characterized in that: It also includes an elastomer, a connector (203) and a base, wherein the elastomer is multi-layered, adjacent elastomers are connected by connectors (203), the interior of each layer of the elastomer is fixed to the same base for connecting the instrument rod (3), the exterior of each layer of the elastomer and the connector (203) can be deformed under the action of external force, and the interior and exterior of each layer of the elastomer are connected by a deformable flexible deformation beam (220); optical fibers are penetrated inside the elastomer, the connector (203) and the base.

2. The hollow multi-dimensional force sensor according to claim 1, characterized in that: Each layer of the elastomer is annular, the inner ring is the inside of the elastomer, and the outer ring is the outside of the elastomer. One end of the flexible deformable beam (220) is fixedly connected to the inner ring of the elastomer or is an integral structure, and the other end of the flexible deformable beam (220) is fixedly connected to the outer ring of the elastomer or is an integral structure. The other end of the flexible deformable beam (220) is provided with a structure for fixing the optical fiber, and the structure and foundation for fixing the optical fiber are used to fix the optical fiber that can be deformed.

3. The hollow multi-dimensional force sensor according to claim 2, characterized in that: The flexible deformable beams (220) are multiple and are distributed at equal angles along the axis of the force sensor; the flexible deformable beams (220) are arc-shaped beams or straight beams (221); the structure for fixing the optical fiber is a connecting medium, and an optical fiber fixing hole or a connecting groove is provided at the other end of the flexible deformable beam (220).

4. The hollow multi-dimensional force sensor according to claim 1, characterized in that: The foundation is a base (205) with a hollow structure, one end of the base (205) is larger than the other end, thereby forming a deformation boss (216) between the two ends, and the other end with a smaller size is an intermediate support member (207) for fixing the inside of each layer of elastomer; the end of the base (205) with a larger size is provided with an optical fiber fixing hole for fixing the optical fiber; the optical fiber is divided into a strain optical fiber and a temperature optical fiber, the strain optical fiber is respectively fixed to the foundation and the last layer of elastomer, the temperature optical fiber is only fixed to the foundation, and the strain optical fiber and the temperature optical fiber are not in contact with the remaining layers of elastomer except the last layer of elastomer, and a gap is left.

5. A hollow multi-dimensional force sensor, comprising an optical fiber, characterized in that: It also includes an elastic body and a base, wherein the elastic body is one, the inside of the elastic body is fixed to the base, the outside of the elastic body can be deformed under the action of an external force, a groove is cut on the side wall of the elastic body, thereby forming a flexible deformable beam (220), the inside and outside of the elastic body are connected by the flexible deformable beam (220) that can be deformed; and optical fibers are inserted into the inside of the elastic body and the base.

6. The hollow multi-dimensional force sensor according to claim 5, characterized in that: The elastic body is a hollow sidewall grooved elastic body (215), with multiple layers of grooves cut along the axial direction on the sidewall, and the number of grooves in each layer is two that are not cut through in the circumferential direction, and the flexible deformation beam (220) is formed between the two grooves, and one end of the flexible deformation beam (220) is provided with an elastic body support (214) as an interior of the sidewall grooved elastic body (215), and the elastic body support (214) realizes a stable connection between the sidewall grooved elastic body (215) and a base; and each layer of the flexible deformation beam (220) is also connected to a plurality of optical fiber fixing seats (213) for fixing optical fibers.

7. The hollow multi-dimensional force sensor according to claim 5, characterized in that: The foundation is a base (205) with a hollow structure, one end of the base (205) is larger than the other end, thereby forming a deformation boss (216) between the two ends, and the other end with a smaller size is an intermediate support member (207) for fixing the inside of the elastic body, and the intermediate support member (207) and the flexible deformation beam (220) are both provided with a connection groove (222); the end with a larger size of the base (205) is provided with an optical fiber fixing hole for fixing the optical fiber; a gap is left between the side wall groove elastic body (215) and the end with a larger size of the base (205); the optical fiber is divided into a strain optical fiber and a temperature optical fiber, the strain optical fiber is respectively fixed to the foundation and the side wall groove elastic body (215), and the temperature optical fiber is only fixed to the foundation.

8. A method for measuring a hollow multi-dimensional force sensor according to any one of claims 1 to 7, characterized in that: The following steps are included When the force sensor is subjected to an axial force, the outer portion of the elastic body is axially offset; the optical fiber segment between the elastic body and the base is deformed, so that the grating pitch on the optical fiber segment changes, thereby changing the grating reflection wavelength inside the optical fiber segment; When the force sensor is subjected to radial force, the outside of the elastic body is deformed or the outside of the elastic body and the connecting member are deformed as a whole, and the optical fiber segment between the elastic body and the base is deformed, so that the grating pitch on the optical fiber segment changes, and then the grating reflection wavelength inside the optical fiber segment changes; The magnitude and direction of the force are calculated based on the change in the reflected wavelength through measurement methods.

9. The method for measuring a hollow multi-dimensional force sensor according to claim 8, characterized in that: The method of obtaining the magnitude and direction of the force by measuring the change in the reflected wavelength includes the following steps: According to the obtained multiple real force reference values, they are applied to the hollow multi-dimensional force sensor; when the hollow multi-dimensional force sensor is subjected to forces of different directions and magnitudes, the optical fiber wavelength change value corresponding to the real force reference value is collected; After removing the temperature influence from the optical fiber wavelength change value, the value is used as the input data of the random forest model, and the obtained real force reference value is used as the output data of the random forest model. The mapping relationship between the optical fiber wavelength change value and the applied force is obtained through model training. When using a hollow multi-dimensional force sensor for measurement, the magnitude and direction of the force can be obtained based on the change in reflection wavelength and the mapping relationship between the optical fiber wavelength change value and the force.

10. The hollow multi-dimensional force sensor measurement method according to claim 9, characterized in that: The optical fiber wavelength variation value is obtained by removing the temperature influence through the following formula: [Dl 1F Dl 2F Dl 3F ] T =[Δλ1Δλ2Δλ3] T -[k 1T k 2T k 3T ] T Dl4 Among them, Δλ iF k is the wavelength change of the ith optical fiber caused by external force after removing the temperature effect, iT is the temperature correlation coefficient between the i-th strain measuring fiber and the temperature measuring fiber, i = 1, 2, 3; Δλ j is the total wavelength change of the j-th optical fiber caused by external force and temperature, j = 1, 2, 3, 4.

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