Fiber optic system with helical core structure for detecting forces during crash testing

Abstract

A fiber optic system for a body part of an anthropomorphic test device is disclosed, the fiber optic system comprising at least one body part and at least one optical fiber having a plurality of cores spaced apart from each other and in a spiral relationship, the cores extending between ends of the optical fibers to sense the position of the at least one body part. Each core has a plurality of grating sensors arranged along its length, the grating sensors being capable of determining the position and orientation of the body part.

Description

[0001] Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 808,039, filed on February 20, 2019, which is incorporated herein by reference. Technical Field

[0003] The present invention relates generally to systems for detecting forces during impact testing using an anthropomorphic test device, and more particularly to fiber optic systems for body parts of anthropomorphic test devices. Background Art

[0004] Automobile, aviation, and other vehicle manufacturers perform a variety of crash tests to measure the effects of a crash on the vehicle and its occupants. Through crash testing, vehicle manufacturers gain valuable information that can be used to improve the vehicle.

[0005] Crash testing typically involves the use of an anthropomorphic test device (ATD), commonly referred to as a "crash test dummy". The ATD is formed by multiple body parts that are interconnected to simulate the human body. Each body part includes many discrete components intended to represent the joints of the human body. In other words, many body parts are able to move, twist and bend in multiple directions in different ways. During a crash test, the ATD is placed inside a vehicle and the vehicle undergoes a simulated collision (sled test) or a physical collision. The collision exposes the ATD to high inertial loads, and sensors inside the ATD (such as accelerometers, strain gauges and other sensors) generate electrical signals of data corresponding to the load. Cables transmit the electrical signals of these data to a data acquisition system (DAS) for subsequent processing. This data reveals information about the impact of the collision on the anthropomorphic test device and can be correlated with the impact that a similar collision may have on a human occupant.

[0006] The movement and deformation of the ATD during crash testing has also been visually monitored in the past using high-speed cameras. However, some tests cannot be monitored in this way due to the construction of the structure surrounding the ATD, the presence of other dummies, or the inflation of airbags. In addition, the positioning or shape of various body parts of the ATD may be difficult to estimate, such as limbs and internal organs. It is particularly difficult to monitor simulated soft organs using traditional strain gauges because it is difficult to measure the strain of low Young's modulus materials using high Young's modulus sensing elements.

[0007] In order to develop the bone structure, organs or flesh of an ATD, it is necessary to create or form shapes and materials to adjust the various possible stiffnesses that the human body may have in different parts or components. To adjust these components, it is only possible to change the geometry of the body part or ATD or use different materials and adjust as close as possible to the material stiffness requirements. These systems are very time-consuming to set up and only represent certain aspects of the human body when subjected to forces.

[0008] The ATD is highly adjustable to allow for many different configurations. Therefore, it is difficult to reposition the ATD to the exact same position and orientation for subsequent testing. A camera can be used to realign the ATD, but there is less certainty that the position and orientation will be the same, especially for internal body parts, such as organs or bones, and body parts obscured by other mounting hardware. If the position and orientation of the ATD is different from the position and orientation of the ATD in subsequent testing, the results may be different. Summary of the invention

[0009] Therefore, the present invention provides a system for detecting forces during a crash test. The system includes a plurality of components and at least one optical fiber, the plurality of components forming part of at least one of a vehicle, a test bench and / or an anthropomorphic test device, the at least one optical fiber being supported by and in contact with at least one of the plurality of components, the optical fiber extending along a fiber axis between a first end and a second end. The optical fiber has a plurality of cores extending between a first end and a second end and each core has a plurality of grating sensors integrally inscribed therein, wherein the sensors are spaced apart along the length between the first end and the second end. A transmitter communicates with the optical fiber to transmit light having a predetermined wavelength band reflected by the sensor through the plurality of cores of the optical fiber, and an interrogator communicates with the optical fiber to detect reflected light from the plurality of grating sensors, such that changes in the reflected light indicate strain on the optical fiber. The plurality of cores are further defined as having at least one position along the respective lengths at which the plurality of cores are spirally coiled around each other along the fiber axis.

[0010] The present invention also provides another system for detecting forces during a crash test. The system includes a plurality of body parts forming an anthropomorphic test device and simulating at least a portion of a human body, wherein at least one first optical fiber is supported by at least one of the body parts. The first optical fiber extends between a first end and a second end and has a plurality of cores extending between the first end and the second end. Each core has a plurality of grating sensors integrally inscribed therein, wherein the sensors are spaced apart along the length between the first end and the second end. The system also includes a plurality of components that form a portion of at least one of a vehicle and / or a test bench, wherein at least one second optical fiber is supported by at least one of the plurality of components. The second optical fiber extends between a first end and a second end and includes a plurality of cores extending between the first end and the second end. Each core has a plurality of grating sensors integrally inscribed therein, wherein the sensors are spaced apart along the length between the first end and the second end. A transmitter communicates with the first optical fiber and the second optical fiber for emitting light having a predetermined wavelength band reflected by the sensor through the plurality of cores of the first optical fiber and the second optical fiber. An interrogator communicates with the first and second optical fibers for detecting reflected light from the plurality of grating sensors, such that changes in the reflected light indicate strain on the optical fiber. The plurality of cores of at least one of the first and second optical fibers are further defined as having at least one location along the respective length where the plurality of cores are helically coiled about one another along the fiber axis.

[0011] The present invention also provides an anthropomorphic test device, which includes at least one of the body parts simulating at least a part of a human body and at least one optical fiber supported by the at least one body part, the optical fiber extending between a first end and a second end. The optical fiber has a plurality of cores extending between the first and second ends and each core has a plurality of grating sensors integrally inscribed therein along the length thereof, the sensors being spaced apart along the length between the first end and the second end. The plurality of cores are further defined as having at least one position along the respective lengths at which the plurality of cores are spirally coiled around each other along the fiber axis.

[0012] One advantage of the present invention is that a new fiber optic system is provided for the body parts of an anthropomorphic test device. The fiber optic system utilizes multi-core optical fibers positioned throughout a specific body part of the ATD. The optical fibers are also small and lightweight, thereby minimizing interference with the test. The optical fibers are typically formed from quartz-based fibers that are very stable and provide repeatable test results. Using optical fibers as sensing elements also has the advantage of keeping the electronics away from the sensing location. Another advantage is that the optical fibers are insensitive to electromagnetic noise in the environment.

[0013] The subject invention allows the ATD to be used in tests other than crash or collision tests, including falls, parachuting, spacecraft launches, etc., which require precise positioning of the body part before the test and subsequent tests to ensure the repeatability of the test and the accuracy of the test results. The precise positioning is assisted by multiple cores, which provide additional positioning data for various body parts. Multiple cores also improve the sensitivity of the optical fiber and the system as a whole. Multiple cores placed side by side can be used for bending measurement, and spirally spaced cores can be used to detect the direction of rotation. The center core in the neutral axis of the optical fiber can be used to measure or compensate for total strain or temperature. The optical fiber of the subject invention can be used to measure the strain of large displacements and / or related velocities or accelerations of the body part of the ATD. One possible way to measure displacement, deformation, shape or orientation using an optical fiber according to the subject invention is to fix a section of the optical fiber to a reference material and use a lever to cause local torsion, thereby enhancing the torsion effect in the section of the optical fiber.

[0014] One advantage of this new fiber optic system is that it measures stress, strain and deformation of skeletal structures, organs and flesh so that ATD forms a component that can change simultaneously in structure, material and shape. Another advantage of the present invention is that the biofidelity of ATD used now and in the future is improved due to the better measurement of structural strain, stress and shape brought by multi-core optical fiber. Another advantage of the present invention is that the fiber optic system allows better vehicle constraint assessment to predict possible injuries. Existing measurement systems rely on individual load sensors placed in the ATD and the metal structure of the ATD inhibits the ability to measure using such load sensors. Fiber optic measurement systems can be transmitted through areas where current load sensors cannot be placed. In addition, optical fibers can be threaded through metal structures to provide a complete analysis of the forces acting on the desired body part. Other existing systems rely on images taken by cameras at discrete impact points, which require a lot of calculations and extrapolations to determine the force. The subject invention overcomes these inaccuracies and provides real-time measurement.

[0015] Other features and advantages of the present invention will be readily appreciated as they become better understood after reading the following description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1A is a perspective view of one embodiment of a fiber optic system according to the present invention having a plurality of body parts forming an anthropomorphic test device (ATD) with a plurality of optical fibers supported on the body parts.

[0017] Figure 1B is a side view of a fiber optic system in operative relationship with an ATD in a vehicle undergoing crash testing.

[0018] Figure 2is a partially cutaway perspective view of an optical fiber used in the optical fiber system of the subject invention.

[0019] Figure 3 is a schematic diagram of an optical fiber communicating with a control box according to one embodiment of the subject invention.

[0020] Figure 4 is a schematic diagram of an optical fiber according to one embodiment of the subject invention.

[0021] Figure 5 is a perspective view of one embodiment of an optical fiber in accordance with the subject invention.

[0022] Fig. 6A and Figure 6B is an end view of another embodiment of an optical fiber for use with the subject invention.

[0023] Figure 7 is a partial cross-sectional perspective view of yet another embodiment of an optical fiber with a lever for use with the subject invention.

[0024] Figure 8 is a side view of an embodiment of an optical fiber with a lever for use with the subject invention.

[0025] Fig. 9 is a side view of another embodiment of an optical fiber forming a lever for use with the subject invention.

[0026] Fig.10 is a side view of a lever with a mass engaging an optical fiber for use with the subject invention.

[0027] Fig.11 is a side view of one embodiment of an optical fiber forming a lever with an attached mass for use with the subject invention.

[0028] Fig.12 is a side view of another embodiment of an optical fiber.

[0029] Figure 13-Figure 17 is a side view of a body portion of an anthropomorphic test device that undergoes a deformation or change through rotation that is detectable by the subject invention.

[0030] Fig.18 is a perspective view of another embodiment of an optical fiber system according to the present invention. DETAILED DESCRIPTION

[0031] With reference to the accompanying drawings, and in particular Figure 1A , shows one embodiment of a fiber optic system 100 in accordance with the present invention in operative relationship with an anthropomorphic test device (ATD), generally indicated at 102 . Figure 1BAn optical fiber system 100 is shown for use in a vehicle undergoing a crash test. The system 100 includes a plurality of body parts forming an anthropomorphic test device 102 and simulating at least a portion of a human body. The body parts are articulated to simulate the movement of a human body. According to the present invention, the optical fiber system 100 includes at least one optical fiber 122 extending between a first end 126 and a second end 128. The optical fiber 122 is supported by and in contact with at least one of the ATD or the vehicle.

[0032] exist Figure 1A In the example shown, the anthropomorphic test device 102 is a fifty percent (50%) male type and is shown in a sitting position. It should be understood that the fiber optic system 100 can be used with all types of ATDs 102. The system 100 can be used to sense the shape or orientation of a body part so that the orientation can be maintained or accurately realigned for subsequent testing.

[0033] In one embodiment, the system 100 is primarily, but not limited to, used to test the performance of interiors and systems for seat occupants subjected to impact or collision. In another embodiment, the fiber optic system 100 can be used to test multiple components that form part of at least one of a vehicle and a test bench. This can also include specifically testing the performance of automotive interiors and the performance of restraint systems for adult front and rear seat occupants. In terms of automotive interior components, this can include seats, restraints, consoles, steering columns, steering wheels, or any interior components that are impacted. Other vehicles that can be tested include, but are not limited to, aircraft and related interior components, which can include seats, restraints, shells, head linings, seat trays, and the like.

[0034] The dimensions and weight of the ATD 102 are based on anthropometric studies, typically conducted by the following organizations: the University of Michigan Transportation Research Institute (UMTRI), the U.S. Military Anthropometric Survey (ANSUR), and the U.S. Civilian and European Surface Anthropometric Resources (CESAR). It should be understood that the range of motion, center of gravity, and segmented mass simulate those human subjects defined by anthropometric data. The ATD 102 can also be used to directly test the impact forces on the simulated human body on various test benches, such as neck twist fixtures, chest impact fixtures, and the like. Similarly, the optical fiber 122 can be supported by such a test bench and in contact with such a test bench to test the impact on such a test bench.

[0035] Referring back to the ATD 102, the body parts generally include rigid body parts and flexible body parts. The rigid body parts of the ATD 102 are intended to mimic and / or simulate rigid body parts of the human body, such as bones. The flexible body parts are intended to mimic and / or simulate flexible body parts of the human body, such as flesh, muscles, tissues, organs, and the like. The ATD 102 combines rigid and flexible body parts to more accurately represent the human body. For example, an arm assembly includes rigid body parts corresponding to bones and flexible body parts corresponding to flesh, muscles, and tissues. With respect to the flexible body parts, it should be understood that various materials (e.g., urethane or plastic) can be used to form the flexible body parts to improve coupling with the rigid body parts of the anthropomorphic test device.

[0036] like Figure 1A and Figure 1B As generally shown, the ATD 102 includes a head assembly 104, left and right arm assemblies 106, left and right thigh assemblies 108, left and right calf assemblies 110, a thorax assembly 112, and a pelvis assembly 114. The instrument core can be installed in various body parts and can be removable to access the body parts. It should be understood that the left and right assemblies are generally constructed in a similar manner. It should be understood by those of ordinary skill in the art that the various components that form the ATD 102 are well known and can be varied based on a specific ATD 102 without departing from the subject invention.

[0037] Figure 1A Also shown is a neck assembly 116 that connects the head assembly 104 to the thorax assembly 112. The thorax assembly 112 also includes a spine assembly 118 having an upper end mounted to the head assembly 104 and a lower end extending into the torso region of the ATD 102. The thorax assembly 112 also includes a rib cage assembly 120 connected to the spine assembly 118. Figure 1AIn the embodiment of the present invention, one optical fiber 122' is arranged in the head assembly 104 (either embedded or surface mounted), and another optical fiber 122" is wrapped around the rib 124. However, the rib 124 can also be tested as an independent body part to determine the response to various impacts. The optical fiber 122" directly contacts the rib 124 to sense the strain on the rib 124. Another optical fiber 122'" is disposed in the arm assembly 106, and yet another optical fiber 122"" is disposed in the shank assembly 110. It should be understood that the optical fibers can all have the same configuration, or each can be different while still practicing the subject invention. In addition, the optical fiber 122 can be a continuous fiber that extends throughout the ATD 102, even though it is shown as a discrete fiber. The optical fiber 122 can be mounted directly to the surface of the body part or embedded within the body part. It should be understood that the mounting can be achieved using an adhesive, glue, tape, or the like. It should be understood that the embedding of the optical fiber can be achieved by various methods, such as by molding or casting the body part around the optical fiber. The body part can also be 3D printed around the optical fiber, or vice versa.

[0038] Reference Figure 2 , the optical fiber 122 has a plurality of cores 130, i.e., a plurality of cores 130 extending between a first end 126 and a second end 128. The optical fiber 122 also defines a longitudinally extending fiber axis 132. The plurality of cores 130 may include one core (e.g., a central core) disposed along the fiber axis and other cores (e.g., satellite cores) spaced apart from the central core. Alternatively, the plurality of cores 130 may include only satellite cores. The plurality of cores 130 are spaced apart from one another and are in a spiral relationship such that the plurality of cores 130 are spirally wound around one another along the fiber axis 132 at at least one position along the respective lengths. The spiral relationship of the cores 130 may be located at different locations throughout the optical fiber 122 or may extend throughout, i.e., the plurality of cores 130 are spirally wound continuously between the first end 126 and the second end 128.

[0039] The coating material 136 surrounds the cladding material 134 to provide strength to the core 130 and the cladding material 134. Preferably, although not required, a strength member 140 and an outer jacket 142 may also surround the coating material 136 to provide additional strength to the optical fiber 122. However, it should be understood that the various layers may depend on the configuration of the multiple cores 130.

[0040] Figure 3A schematic diagram of a system 100 communicating with one of the cores 130 is shown. Each core 130 has a plurality of grating sensors 144 arranged along its length, so that the system 100 can determine the position and orientation of the body part. It will be appreciated by those of ordinary skill in the art that the grating sensor 144 is typically a longitudinal variation in the refractive index of the core 130. The number of grating sensors 144 can be selected based on a particular body part. For example, the optical fiber 122 can have 7 to 25 sensors 144 arranged between the ends. Other embodiments can have up to 100 sensors 144. The sensors 144 can be located near joints, such as elbows, hips, shoulders, knees, or ankles. For certain body parts, the sensors 144 can be arranged equidistantly from each other along the optical fiber 122 and around the body part. For other body parts, the sensors 144 can be placed closer to each other. Multiple grating sensors 144 can be placed in a position where multiple cores 130 are spirally coiled around each other. Additionally, the plurality of grating sensors 144 of each core 130 may be coplanar with one another, with the plurality of cores 130 being spirally wound around one another. The pitch of the grating sensors 144 determines the specific wavelength that will be reflected by the grating sensors 144. As is well known, each grating sensor 144 has its own period and thus its own unique reflected wavelength, such that each sensor can be distinguished by the detected reflection.

[0041] The system 100 includes an interrogator 146 in communication with the optical fiber 122 and a transmitter 148 in communication with the optical fiber 122, the transmitter 148 being used to transmit light having a predetermined wavelength band reflected by the sensor 144 through the optical fiber 122. The interrogator 146 and the transmitter 148 emit light of different wavelengths in the band so that the light covers a wide spectrum. The light propagates through the optical fiber 122, is reflected by the sensor 144 at a certain point and returns to the interrogator 146. The sensors 144 have different periods, so the signals of different sensors can be distinguished. The optical signal returned from the sensor 144 can deduce the actual strain and thus the stress on the body part. The detection of strain can be provided by fiber Bragg grating (FBG), Brillouin scattering, Rayleigh scattering, interferometer or any other optical technology known to those skilled in the art. Although the grating sensor 144 is described as being integrally formed with the optical fiber 122, it should be understood by those skilled in the art that an optical time domain reflectometer (OTDR) can be used with Brillouin or Rayleigh scattering to determine the location of the strain by using the pulse time to implement the subject invention.

[0042] The subject invention may enclose the interrogator 146 and the transmitter 148 in a control box (FIG. 1 and Figure 2150 ). The control box 150 may also house a controller 152. A suitable control box 150, transmitter 148, and interrogator 146 are disclosed in co-pending application PCT / US19 / 14878 filed on January 24, 2019, which is incorporated herein by reference. As an example, the transmitter 148 emits light having a predetermined band wavelength from 50 nanometers to 450 nanometers. In one embodiment, the wavelength band may be in the range of 1510-1595 nanometers. In another embodiment, the wavelength band may be in the range of 1275-1345 nanometers. In yet another embodiment, the wavelength band may be in the range of 780-850 nanometers. The wavelength band may also be applicable to red diode lasers. It should be understood that these wavelength bands are exemplary and are not intended to limit the subject invention.

[0043] The control box 150 is coupled to the optical fiber 122, and the light from the transmitter 148 is reflected by the sensor 144. The reflected light can be used to determine the force (e.g., strain) experienced by the optical fiber 122 and ultimately determine the amount of deformation of the body part. In other words, when the optical fiber 122 is placed on the body part in the initial state, the sensor 144 reflects a specific pattern of light. When a force is applied to the body part, the optical fiber 122 is subjected to stress or strain, which causes the sensor 144 to undergo a change, such as by expansion or contraction. The expansion or contraction sensor 144 changes the reflected light pattern. As an example, the change in the reflected light pattern is detected and then compared with a known change to determine the amount of movement or deformation of the body part. The applied force can cause the body part and / or the optical fiber 122 to deform. These forces can also include changes in the environment, such as temperature or pressure, which can cause changes in the optical fiber 122 sufficient to change the reflected light pattern. However, in a crash test, the subject invention undergoes significant deformation in a very short time span (i.e., in an impact simulation). The deformation causes significant strain on the optical fiber 122, resulting in areas being stretched and other areas being compressed. In addition, the system 100 is subjected to repeated deformations.

[0044] Reference Figure 4, another schematic diagram of one of the optical fibers 122 and the sensor 144 is shown, as will be understood by those of ordinary skill in the art, the light reflected by the fiber Bragg grating is directed to the core 130. The sensor 144 has a length L and the light has a wavelength l. The core 130 has a refractive index nc selected for a particular application. It is well known to those of ordinary skill in the field of optical fibers to associate the reflected light from the sensor 144 with the wavelength l, the length L, and the refractive index nc. The optical fiber 122 may have a diameter from 30 microns to 1000 microns. In one embodiment, the optical fiber 122 has a diameter from 100 microns to 300 microns. Each core 130 may have the same diameter or different diameters. In one embodiment of the system 100, each of the cores 130 has a diameter from 2 microns to 900 microns. In another embodiment, each core has a diameter of 2-300 microns. Alternatively, the diameter of the core 130 is typically less than 30 microns, and in particular 5-20 microns. A preferred optical fiber 122 has a core 130 with a diameter of about 8 microns. The cladding material 134 is typically about 75-200 microns, and more particularly 100-150 microns. In another embodiment, the optical fiber 122 has a diameter from 100 microns to 200 microns. The size of the optical fiber 122 can be set for a specific body part. A common diameter of the optical fiber 122 is about 75-150 microns.

[0045] The optical fiber 122 provided by the subject invention is capable of tracking the precise shape, position, and movement of the ATD 102 in real time. Figure 5 yes Figure 2 1 and 12. A perspective view of the core 130 and cladding material 134 of the optical fiber 122 is shown. The two cores 130 are twisted helically along the main axis 132 of the optical fiber 122. A similar effect can be achieved by twisting two optical fibers having a single core and attaching them to each other (i.e., as a bundle of juxtaposed fibers). When the optical fiber 122 is subjected to a twist T, the core 130 will experience a tensile strain if the twist is applied in the same direction as the original twist, and the core 130 will experience a compressive strain if the twist is applied in the opposite direction to the original twist. By measuring the strain in each core, the twist of the optical fiber system 100 can be measured. In this embodiment, the amount of twist can be determined, but the direction of the twist is unknown.

[0046] Reference Fig. 6A , a cross-sectional view of another embodiment of an optical fiber 122 is shown having five cores 130. The optical fiber 122 has one core 131 centrally located along the axis 132 and having a larger diameter, and the other cores 130 are placed around the central core 131. The use of the central core 131 is expected to allow strain measurement in the neutral axis 132 of the optical fiber 122. A counterclockwise torsion Tccw is applied to the optical fiber 122 and the central core 131 allows the torsion direction to be determined. Figure 6BA clockwise twist Tcw applied to the optical fiber 122 is shown.

[0047] Figure 7 is a perspective view of an optical fiber 122 having a lever 154 attached thereto which can be used to convert displacement into torsion T. Figure 8 An optical fiber 122 is shown secured to a reference material 156 (e.g., one of the body parts of the ATD 102). The optical fiber 122 is secured to the reference material 156 at a point 158 ​​and a lever 154 extends from the optical fiber 122 so that a concentration of torsional strain can be created between the two points 158. The displacement at the end of the lever 154 exerts a force on the core 130 to twist or twist apart. The subject invention allows the sensor 144 along these points to detect the strain caused by the force. One of ordinary skill in the art can convert the strain measurement value into the displacement of the lever 154 using a transfer function.

[0048] Fig. 9 Another embodiment of an optical fiber 122 is shown having a loop 160 that acts as a lever 154. The optical fiber 122 is secured at point 158, such as by an adhesive material 162 to hold the loop 160 closed. The loop 160 can be secured to the reference material 156 similarly as before. Movement of the loop 160 induces torsional strain on the optical fiber 122, which can be optically detected as discussed above. Fig.10 15 is another embodiment of an optical fiber according to the subject invention that can be used to detect velocity or acceleration, which can be converted to torsion. The optical fiber is fixed at point 158 ​​and a lever 154 extends from the optical fiber 122. A mass 164 is attached to the lever 154 so that changes in displacement of a reference material 156 relative to the inertial mass 164 can be converted to torsion. Fig.11 An alternative embodiment is shown having a mass 164 attached to the ring 160 for determining torsion. The advantage of using the optical fiber 122 as both sensor and spring is the simplicity of manufacturing and the benefit of the high stability of quartz as a material.

[0049] refer to Fig.12 , shows a side view of one embodiment of an optical fiber 122. The optical fiber 122 has sensors 144 as fiber Bragg gratings (FBGs) written into different cores 130. The sensors 144 of each core 130 are shown to be coplanar with each other.

[0050] Figure 13-Figure 17An embodiment of the subject invention for determining the orientation and movement of a joint in an ATD 102 is shown. It should be understood that the subject invention can be used to monitor any joint present in an ATD using a single or multiple optical fibers 122 to link all sensing points. In addition, more than one rotation or torsion attachment can be used for a single joint.

[0051] In a specific example, the bending and rotation of arms and legs can be monitored by attaching base plates and levers to different parts of the joints. Fig.13 , a side perspective view of the ATD 102 is shown with the arm assembly 106 in a starting position A. As the ATD 102 is subjected to forces or accelerated, the arm assembly 106 moves in at least one plane to a position B about the shoulder joint 170. The subject invention is capable of sensing the precise position of the arm assembly 106 about the shoulder joint 170, including rotation. Fig.14 , the arm assembly 106 moves about the shoulder joint 170 in a plane different from orientation C. Fig.15 is a side perspective view of ATD 102 showing arm assembly 106 in a starting orientation D and as ATD 102 is subjected to forces or accelerated, arm assembly 106 moves to an orientation E about elbow joint 172. The subject invention is capable of sensing the precise orientation of arm assembly 106 about elbow joint 172, including rotation.

[0052] refer to Fig.16 , the thigh assembly 108 and the shank assembly 110 are shown in a starting orientation F and the shank assembly is moved to orientation G. The fiber optic system 100 of the subject invention is capable of detecting rotation about the knee joint 174 . Fig.17 A calf assembly 110 is shown having a foot 178 that pivots about an ankle joint 176 .

[0053] The subject invention allows shape information to be extracted from differential strain measurements from different cores 130. In one embodiment, the optical fiber 122 has a length that extends through the body part of the ATD 102. Preferably, the length is sufficient for one optical fiber 122 to extend through the head, neck, arm, chest, pelvis, and thigh and calf components. Alternatively, each body part can receive its own optical fiber 122. For example, shape sensing can be used to detect the orientation of each limb, head, body, or organ relative to the spine or relative to the surrounding environment, where the surrounding environment can be a car or a seat. The subject invention is capable of undergoing significant deformations in a very short time span (i.e., in an impact simulation). The deformation causes strain on the optical fiber 122, causing areas to be stretched and other areas to be compressed. In addition, the system 100 undergoes repeated deformations.

[0054] The sensing system 100 may be attached to a portion of the ATD 102, such as the neck, spine, joints, internal organs, bones, ribs, or any portion thereof. Figure 1A , optical fiber 122 is placed in different parts throughout to monitor its shape by sensing different parts (such as trunk, limbs and head). Therefore, the subject invention allows the accurate positioning of body parts before ATD 102 is tested or any movement. Once the initial position and orientation of the body part are known, the body part can be repositioned in the same position and orientation for subsequent testing. The subject invention also allows the detection of the bending of joints (such as elbows, knees or neck) before, during and after the test. The ability to repeatedly place the body part in the correct or same position before and in subsequent tests is important, and the present invention will significantly assist this operation.

[0055] Reference Figure 1B , the second optical fiber 123 is arranged in an internal component (eg, instrument panel 121). Fig.18 Another embodiment is shown for testing an aircraft interior having two ATDs 102 with Figure 1B The same as shown. Each ATD 102 has a first optical fiber 122, 122', 122". extending throughout the body portion. The second optical fiber 123 extends through the seat back 133 and the small table 135. Each of the first optical fiber 122, 122', 122" and the second optical fiber 123 includes a core 130 having a grating sensor 144 as discussed above.

[0056] The present invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.

[0057] Numerous modifications and variations of the present invention are possible in light of the above teachings. Thus, the present invention may be practiced in ways other than those specifically described.

Claims

1. A system for detecting forces during a crash test, wherein the system experiences a sudden impact causing deformation within a short time span, the system comprising: a plurality of components forming part of at least one of a vehicle, a test bench, and / or an anthropomorphic test apparatus, wherein at least one of the plurality of components includes a joint between adjacent components; at least one optical fiber supported by and in direct contact with at least one of the components, wherein the optical fiber extends along a fiber axis between a first end and a second end, the at least one optical fiber extending across the joint and secured at a plurality of points adjacent the joint; The optical fiber has a plurality of cores extending between the first end and the second end, each of the cores having a plurality of grating sensors integrally inscribed therein, the sensors being spaced apart along a length between the first end and the second end; a transmitter in communication with the optical fiber for transmitting light having a predetermined wavelength band through the plurality of cores of the optical fiber to be reflected by the sensor; as well as an interrogator in communication with the optical fiber for detecting reflected light from the plurality of grating sensors such that changes in the reflected light are indicative of strain on the optical fiber; wherein the plurality of cores are further defined as having at least one location along a respective length at which the plurality of cores are spirally coiled about each other along the fiber axis, and wherein the location extends across the joint such that movement at the joint due to experiencing the sudden impact induces strain on the optical fiber, the strain stretching and compressing the grating sensor, thereby changing the reflection of light from each of the plurality of cores, the strain being used to measure torsion of the plurality of components about the joint. 2 . The system of claim 1 , wherein the plurality of cores are spirally wound continuously between the first end and the second end.

3. The system of claim 1, wherein the plurality of grating sensors are located where the plurality of cores are spirally wound around each other. 4 . The system of claim 3 , wherein the plurality of grating sensors of each of the cores are coplanar with one another, wherein the plurality of cores are spirally wound around one another.

5. The system of claim 3, wherein the plurality of cores comprises at least three cores.

6. The system of claim 5, wherein one of the cores is placed along the fiber axis to detect the direction of twist applied to the optical fiber, wherein the other of the cores is helically coiled around the axis.

7. The system of claim 3, further comprising a lever extending from the optical fiber at the at least one location to convert displacement into torsion of the optical fiber.

8. The system of claim 3, further comprising a lever extending from the optical fiber between fixed points.

9. The system of claim 8, wherein the lever is further defined as a loop of the optical fiber to detect torsional strain on the optical fiber.

10. The system of claim 8, wherein the lever further comprises a mass supported by the lever.

11. The system of claim 1, wherein the plurality of grating sensors are further defined as fiber Bragg grating sensors.

12. The system of claim 1, wherein the plurality of cores are further defined as being spaced apart from one another.

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