Patent Publication Number: US-2023133090-A1

Title: Devices and Methods for Overloading Protection of Piezoelectric Material Mounted on Wheels

Description:
PRIORITY AND RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 63/273,907, filed Oct. 30, 2021, entitled “Devices and Methods for Overloading Protection of Piezoelectric Material Mounted on Wheels,” which is incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     This application relates generally to energy harvesters and strain sensors, and more particularly to energy harvesters and strain sensors with piezoelectric materials. 
     BACKGROUND 
     Advances in distributed sensor networks have improved the safety and performance of various systems, which has led to a greater demand for advanced sensing applications to complement existing systems. 
     SUMMARY 
     Such demand has led to measurements of temperature, pressure, acceleration, and forces (static and dynamic) exerted on tires, wheels, and vehicles. Some of these sensors include a piezoelectric material, which may be used to detect mechanical strain or deformation. For example, a sensor with the piezoelectric material may provide electrical signals that contain information about the movement and/or deformation of a portion of an object (e.g., tire, wheel, vehicle, etc.) onto which the sensor is mounted. However, overloading (application of a stress above a certain threshold) of the piezoelectric material may cause excessive strain in the piezoelectric material, which can lead to damages (e.g., formation of cracks) to the piezoelectric material. 
     The devices and methods described herein address challenges associated with conventional devices with piezoelectric materials. A piezoelectric sensor is coupled with an elastic support, which reduces overloading of the piezoelectric sensor. In some configurations, the elastic support has a loop or hoop structure. In some implementations, the piezoelectric sensor may be used also as an energy-harvesting device (e.g., an electrical power generator that converts kinetic, thermal, optical, and mechanical energy available from a vehicle, such as rotation, acceleration, deceleration, and/or vibration, of the wheels, into electrical energy). Such energy-harvesting devices may replace conventional energy storage devices or, when used in conjunction, prolong the life expectancy of such energy storage devices. 
     In accordance with some embodiments, a sensor module mountable adjacent to a rim of a wheel includes a first set of one or more piezoelectric sensors; and a first elastic support with the first set of one or more piezoelectric sensors coupled thereon so that the first set of one or more piezoelectric sensors are spaced apart from the rim of the wheel. 
     In accordance with some embodiments, a wheel includes a rim and any sensor module described herein. 
     In accordance with some embodiments, a method includes receiving a force on a tire mounted on a rim of a wheel. The tire is in contact with an elastic support with one or more piezoelectric sensors coupled thereon so that the force causes strain in the elastic support and the one or more piezoelectrical sensors. The method also includes, in response to receiving the force, generating electrical signals from the one or more piezoelectric sensors. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a better understanding of the various described embodiments, reference should be made to the Description of Embodiments below, in conjunction with the following drawings in which like reference numerals refer to corresponding parts throughout the figures. 
         FIG.  1    is a schematic diagram illustrating parts of a bicycle in accordance with some embodiments. 
         FIG.  2 A  is a cross-sectional view of a wheel in accordance with some embodiments. 
         FIG.  2 B  is a sectional view of the wheel shown in  FIG.  2 A  in accordance with some embodiments. 
         FIG.  2 C  is a cross-sectional view of a wheel in accordance with some embodiments. 
         FIG.  3    is a schematic diagram illustrating deformation of an elastic support and a piezoelectric sensor mounted thereon in accordance with some embodiments. 
         FIGS.  4 A and  4 B  illustrate mounting of a sensor module on a rim of a wheel in accordance with some embodiments. 
         FIG.  5    illustrates mounting of a tire with a tube and a tubeless tire on a wheel for in accordance with some embodiments. 
         FIG.  6    illustrates example locations for mounting piezoelectric sensors in accordance with some embodiments. 
         FIGS.  7 A- 7 E  illustrate example configurations of a wheel with one or more sensor modules in accordance with some embodiments. 
         FIG.  8 A  is a plot showing a pulse frequency generated based on electrical signals from a piezoelectric sensor in accordance with some embodiments. 
         FIG.  8 B  is a plot showing electrical power generated by a piezoelectric sensor in accordance with some embodiments. 
         FIG.  9    is a flow diagram illustrating a method of generating electrical signals with one or more piezoelectric sensors coupled on an elastic support, in accordance with some embodiments. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Reference will be made to embodiments, examples of which are illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the various described embodiments. However, it will be apparent to one of ordinary skill in the art that the various described embodiments may be practiced without these particular details. In other instances, methods, procedures, components, circuits, and networks that are well-known to those of ordinary skill in the art are not described in detail so as not to unnecessarily obscure aspects of the embodiments. 
     It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first end could be termed a second end, and, similarly, a second end could be termed a first end, without departing from the scope of the various described embodiments. The first end and the second end are both ends, but they are not the same end. Similarly, a first elastic support could be termed a second elastic support, and, similarly, a second elastic support could be termed a first elastic support, without departing from the scope of the various described embodiments. The first elastic support and the second elastic support are both elastic supports, but they are not the same elastic support. 
     The terminology used in the description of the embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the scope of claims. As used in the description and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and/or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
       FIG.  1    is a schematic diagram illustrating parts of a bicycle  100  (also called herein a vehicle) in accordance with some embodiments. Although the bicycle  100  is used as an example throughout this application, the piezoelectric devices described herein may be used in other vehicles, such as an automobile, any other automotive vehicles, or any personal transportation vessels or vehicles. 
     The bicycle  100  includes a frame and one or more wheels  110  (e.g., in  FIG.  1   , the bicycle  100  includes two wheels  110 ). 
     The wheel  110  includes a rim  120  and a tire  124  mounted on the rim  120 . The rim  120  is coupled with a plurality of spokes  122 , which extend to a hub  140  of the wheel  110 . In some embodiments, the spokes  122  are coupled to hub holes  142  (also called spoke holes) of the hub  140  (e.g., using a hub hook). 
     A cross-sectional view of a wheel (e.g., a bicycle wheel) is shown in  FIG.  2 A . In some embodiments, the wheel shown in  FIG.  2 A  corresponds to the wheel  110  shown in  FIG.  1   . 
       FIG.  2 A  shows a rim  210  on which a tire  220  and a sensor module are mounted. The sensor module shown in  FIG.  2 A  includes an elastic support  230  and a piezoelectric sensor  240  coupled (e.g., mounted) on the elastic support  230 . The sensor module shown in  FIG.  2 A  also includes a base  250 . 
     In some embodiments, the piezoelectric sensor  240  includes a thin layer of a piezoelectrical material. Examples of piezoelectric materials include gallium nitride, indium nitride, aluminum nitride, zinc oxide, barium titanate, lead zirconate titanate, potassium niobate, sodium tungstate, Ba 2 NaNb 5 O 5 , Pb 2 KNb 5 O 5 , single crystalline zinc oxide, langasite, gallium orthophosphate, lithium niobate, lithium tantalite, sodium potassium niobate, bismuth ferrite, sodium niobate, bismuth titanate, sodium bismuth titanate, quartz, berlinite, topaz, lead titanate, and piezoelectric polymers, such as polyvinylidene fluoride, polyamides, paralyne-C, polyimide, and polyvinylidene chloride. Piezoelectric materials are capable of generating electrical charge in response to applied mechanical stress. Thus, when the piezoelectric sensor  240  bends, the piezoelectric material provides charges that are indicative of the amplitude of how much the piezoelectric sensor  240  is bent (e.g., a displacement of a free end of the piezoelectric sensor  240 ). Similarly, when the piezoelectric sensor  240  vibrates, the piezoelectric material in the piezoelectric sensor  240  provides an (oscillating) electrical signal that corresponds to the vibration of the piezoelectric sensor  240 . 
     The length, width, and thickness of the piezoelectric sensor  240  are selected to obtain a desired performance for sensing or energy harvesting applications. In some embodiments, for use with a bicycle wheel, the length may be selected between 1 mm and 30 mm, between 1 mm and 10 mm, between 5 mm and 15 mm, between 10 mm and 20 mm, between 15 mm and 25 mm, between 20 mm and 30 mm, between 1 mm and 5 mm, between 5 mm and 10 mm, between 10 mm and 15 mm, between 15 mm and 20 mm, between 20 mm and 25 mm, between 25 mm and 30 mm, between 1 mm and 3 mm, between 2 mm and 4 mm, between 3 mm and 5 mm, between 4 mm and 6 mm, between 5 mm and 7 mm, between 6 mm and 8 mm, between 7 mm and 9 mm, or between 8 mm and 10 mm. In some embodiments, for use with a bicycle wheel, the length is approximately 1 mm, approximately 2 mm, approximately 3 mm, approximately 4 mm, approximately 5 mm, approximately 6 mm, approximately 7 mm, approximately 8 mm, approximately 9 mm, approximately 10 mm, approximately 15 mm, approximately 20 mm, approximately 25 mm, or approximately 30 mm. In some embodiments, for use with a bicycle wheel, the width is selected between 1 mm and 10 mm, between 5 mm and 15 mm, between 10 mm and 20 mm, between 1 mm and 5 mm, between 5 mm and 10 mm, between 10 mm and 15 mm, between 15 mm and 20 mm, between 1 mm and 4 mm, between 2 mm and 5 mm, between 3 mm and 6 mm, between 4 mm and 7 mm, between 5 mm and 8 mm, between 6 mm and 9 mm, or between 7 mm and 10 mm. In some embodiments, for use with a bicycle wheel, the width is approximately 1 mm, approximately 2 mm, approximately 3 mm, approximately 4 mm, approximately 5 mm, approximately 6 mm, approximately 7 mm, approximately 8 mm, approximately 9 mm, approximately 10 mm, approximately 15 mm, or approximately 20 mm. In some embodiments, for use with a bicycle wheel, the thickness of the piezoelectric sensor  240  is 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, or within a range between any two of the aforementioned values. In some embodiments, the thickness of the piezoelectric sensor  240  is approximately 100 μm, approximately 200 μm, approximately 300 μm, approximately 400 μm, approximately 500 μm, approximately 600 μm, approximately 1 mm, approximately 2 mm, approximately 3 mm, approximately 4 mm, or approximately 5 mm. For wheels of different sizes, the piezoelectric sensor may have any other length, width, and thickness. 
     In some embodiments, the piezoelectric sensor  240  includes a single layer of piezoelectric material. In some embodiments, the piezoelectric sensor  240  includes two or more layers of piezoelectric material. In some embodiments, the two or more layers of piezoelectric material are separated by one or more interleaving layers of an insulating material or a conductive material. 
     In some embodiments, the piezoelectric sensor  240  is electrically coupled to an electrical circuit (e.g., an electrical circuit in the base  250 ) for providing electrical signals to an electrical circuit. One or more electrical wires may be used for electrically coupling the piezoelectric sensor  240  to the electrical circuit. Such electrical wires are not shown in  FIGS.  2 A- 2 C  so as not to obscure other aspects of the sensor module. 
     The elastic support is made of an elastic material. In some embodiments, the elastic support includes steel (e.g., carbon steel and spring steel), titanium, or a composite material (e.g., carbon composite, such as carbon-fiber-reinforced polymers). 
     In some embodiments, the elastic material has an elasticity so that the shape (or a curvature) of the elastic support  230  is defined by the tire  220  when the sensor module and the tire  220  are mounted on the rim  210 . For example, the elastic support  230  may have a shape that corresponds to the shape of the internal surface of the tire  220 . 
     The length, width, and thickness of the elastic support  230  are selected to obtain desired overloading protection to the piezoelectric sensor  240 . In some embodiments, the elastic support  230  has a shape of a strip. In some embodiments, the elastic support  230  has a width that matches the width of the piezoelectric sensor  240 . In some embodiments, the elastic support  230  has a width that is greater than the width of the piezoelectric sensor  240 . In some embodiments, the length of the elastic support  230  is selected so that the elastic support  230  substantially fills an inner circumference of the tire  240  (e.g., the length of the elastic support  230  is equal to, or greater than the inner circumference of the tire  240 ). In some embodiments, the length of the elastic support  230  is selected so that the elastic support  230  contacts one or more portions of an inner surface of the tire  240  but does not substantially fill the inner circumference of the tire  240 . 
     The elastic support  230  has two ends: first end  196  and second end  198 , which may be coupled to the base  250 . 
     In some embodiments, the base  250  includes an energy storage device (e.g., a battery or a capacitor). In some embodiments, the base  250  includes electrical circuit for energy harvesting from the electrical signals provided by the piezoelectric sensor  240 . 
     In some embodiments, the base  250  includes electrical circuit for analyzing electrical signals from the piezoelectric sensor  240 . For example, the base  250  may include one or more processors (e.g., microprocessors). In some embodiments, the one or more processors receive electrical power from the piezoelectric sensor  240  for operation of the one or more processors. In some embodiments, the one or more processors (also) receive electrical power from the energy storage device. In some embodiments, the one or more processors analyze the received electrical signals (e.g., for determining forces on the tire, movement of the vehicle, and/or the road condition). 
     In some embodiments, the base  250  also includes one or more communication interfaces (e.g., wired communication circuit and/or wireless communication circuit) for transmitting the electrical signals from the piezoelectric sensor  240  and/or information obtained by analyzing the electrical signals to another wireless communication circuit located in another part of the wheel or away from the wheel. 
       FIG.  2 A  also shows that, in some embodiments, the rim  210  includes, or is coupled to, a spoke coupler  212  (e.g., a threaded coupler) for coupling with a spoke. 
       FIG.  2 B  is a sectional view of the wheel shown in  FIG.  2 A  in accordance with some embodiments. 
       FIG.  2 C  is a cross-sectional view of a wheel in accordance with some embodiments. The cross section shown in  FIG.  2 C  is similar to the cross-section shown in  FIG.  2 A , except that in  FIG.  2 C , the sensor module includes an elastic support  232  instead of the elastic support  230  shown in  FIG.  2 A . The elastic support  232  is sized and shaped so that the elastic support  232  does not fill the inner surface of the tire  220 . This allows the elastic support  232  to have a line contact with the tire  220  instead of a planar contact. In addition, the elastic support  232  has a shape of a loop or a hoop in the cross section (which corresponds to a shape of a tube in the three dimension). 
       FIG.  3    is a schematic diagram illustrating deformation of an elastic support and a piezoelectric sensor mounted thereon in accordance with some embodiments. 
       FIG.  3    shows an elastic support with two ends: first end  196  and second end  198 . In some embodiments, the first end  196  is rigidly fixed. For example, the first end  196  may be rigidly coupled with a base so that there is no relative movement between the first end  196  and the base. In some embodiments, the first end  196  is rotatably fixed. For example, the first end  196  may be rotatably coupled with the base so that the first end  196  may rotate relatively to the base but not laterally relative to the base. In some embodiments, the second end  198  is rigidly fixed. For example, the second end  198  may be rigidly coupled with a base so that there is no relative movement between the second end  198  and the base. In some embodiments, the second end  198  is rotatably fixed. For example, the second end  198  may be rotatably coupled with the base so that the second end  198  may rotate relatively to the base but not laterally relative to the base. In some embodiments, the second end  198  is movably (e.g., slidably) coupled with the base. This allows the second end  198  to move relatively to the base (e.g., slide along a top surface of, or a track defined in, the base). In some embodiments, the second end  198  is not coupled with the base. This allows the second end  198  to move freely (within the confinement of the tire). In some embodiments, the second end  198  is releasably coupled with the base. In some embodiments, the first end  196  is also releasably coupled with the base. 
     The top portion of  FIG.  3    shows that the elastic support has a radius of R1 at a first time (e.g., when no external force is applied on the tire)., and the bottom portion of  FIG.  3    shows that the elastic support has a radius of R2, which is less than R1, at a second time (e.g., when an external force is applied on the tire, which is, in turn, applied on the elastic support). This reduction in the radius of curvature of the elastic support also causes the bending of the piezoelectric sensor mounted on the elastic support, thereby causing generation of electrical signals. Thus, the electrical signals generated by the piezoelectrical sensor can indicate the application of an external force on the tire and the corresponding deformation of the tire, the elastic support, and the piezoelectric sensor. 
       FIGS.  4 A and  4 B  illustrate mounting of a sensor module on a rim of a wheel in accordance with some embodiments. 
       FIG.  4 A  shows a sensor module  410  with the elastic support  230  and the piezoelectric sensor  240  mounted on the base  250 . The base  250  of the sensor module  410  may be shaped to mate with the rim  210  of the wheel so that the sensor module  410  may be mounted directly onto the rim  210  as shown in  FIG.  4 B . 
       FIG.  5    illustrates mounting of a tire with a tube and a tubeless tire on a wheel for in accordance with some embodiments. 
     For mounting a tire with a tube, one end (e.g., the second end  198 ) of the elastic support  230  is released from the base  250  (or alternatively, at least one end of the elastic support is free—not coupled to the base at all), as shown in section A of  FIG.  5   . Subsequently, a tube  510  is placed around the rim  210  and the elastic support  230  at least partially encircles the tube  510 , as shown in section B of  FIG.  5   . In some configurations, this allows the piezoelectric sensor on an inner surface of the elastic support  230  to come into contact with the tube  510 . In some implementations, the one end (e.g., the second end  198 ) of the elastic support  230  is coupled to the base  250 . A tire  220  is mounted on the rim  210  over the tube  510  and the elastic support  230 , as shown in section C of  FIG.  5   . The bead of the tire  220  is seated and the tube  510  is inflated so that the wheel is may be used for driving a vehicle. 
     For mounting a tubeless tire, the tire  220  is mounted directly over the elastic support  230 , as shown in section D of  FIG.  5   . The bead of the tire  220  is seated and the tube  510  is inflated so that the wheel is may be used for driving a vehicle. 
       FIG.  6    illustrates example locations for mounting piezoelectric sensors in accordance with some embodiments. As shown in  FIG.  6   , piezoelectric sensors may be located on an inner surface of the elastic support  230  (e.g., a surface opposite to an outer surface facing the tire). In some embodiments, a piezoelectric sensor is located away from the base  250  (or the rim  210 )(e.g., the piezoelectric sensor is located adjacent to an apex  610 - 1  of an internal surface of the elastic support  230 ). In some embodiments, a piezoelectric sensor is located adjacent to the base  250  (or the rim  210 )(e.g., at location  610 - 3  or  610 - 5 ). In some embodiments, a piezoelectric sensor is located laterally (e.g., at location  610 - 2 ). In some embodiments, only one piezoelectric sensor is coupled on the elastic support  230 . In some embodiments, two or more piezoelectric sensors are coupled on the elastic support  230 . For example, in some configurations, a first piezoelectric sensor is located at location  610 - 1  and a second piezo-electric sensor is located at location  610 - 3 . In some configurations, a first piezoelectric sensor is located at a lateral location  610 - 2  and a second piezo-electric sensor is located at an opposite lateral location  610 - 4  (on an inside surface of the elastic support  230  or an external surface of the elastic support  230 ). In some configurations, three piezoelectric sensors are located at locations  610 - 1 ,  610 - 2 , and  610 - 3 , or at locations  610 - 1 ,  610 - 2 , and  610 - 4 , or at locations  610 - 2 ,  610 - 3 , and  610 - 4 , or at any other locations. In some configurations, four piezoelectric sensors are located at locations  610 - 1 ,  610 - 2 ,  610 - 3 , and  610 - 4 . In some configurations, five or more piezoelectric sensors are coupled on the elastic support  230  (e.g., at locations  610 - 1  through  610 - 5 ). In some configurations, at least some piezoelectric sensors are located on the outer surface of the elastic support  230  (e.g., location  610 - 5  may be on the outer surface of the elastic support  230 ). 
       FIGS.  7 A- 7 E  illustrate example configurations of a wheel with one or more sensor modules in accordance with some embodiments. 
       FIG.  7 A  shows a configuration in which a single elastic support  230  (of a single sensor module) is mounted on the rim. 
       FIG.  7 B  shows a configuration in which two elastic supports  230 - 1  and  230 - 2  are mounted on the rim. In some configurations, the two elastic supports  230 - 1  and  230 - 2  are mounted on a single base. In some configurations, the two elastic supports  230 - 1  and  230 - 2  are mounted on separate bases (e.g., the elastic support  230 - 1  is mounted on a first base and the elastic support  230 - 1  is mounted on a second base that is distinct and separate from the first base). 
       FIG.  7 C  shows a configuration in which more than twenty (e.g., twenty-five) elastic supports are mounted on the rim. In some configurations, the more than twenty elastic supports are mounted on a single base. In some configurations, the more than twenty elastic supports are mounted on two or more bases. In some configurations, each elastic support of the more than twenty elastic supports is mounted on a respective base (e.g., twenty-five bases for twenty-five elastic supports). 
       FIGS.  7 A- 7 C  show elastic supports that extend radially by less than five degrees, four degrees, three degrees, two degrees, or one degree. In some embodiments, an elastic support may extend radially by more than five degrees (e.g., six degrees, seven degrees, eight degrees, nine degrees, ten degrees, fifteen degrees, twenty degrees, thirty degrees, forty degrees, forty-five degrees, sixty degrees, ninety degrees, or more). For example,  FIG.  7 D  shows an elastic support that extends radially by between ten and twenty degrees and  FIG.  7 E  shows an elastic support that extends radially by ninety degrees. Although  FIGS.  7 D and  7 E  show single elastic supports, in some configurations, two or more elastic supports may be used as shown in  FIGS.  7 B and  7 C . 
       FIG.  8 A  is a plot showing a pulse frequency generated based on electrical signals obtained from a road test using a piezoelectric sensor mounted on a bicycle wheel in accordance with some embodiments.  FIG.  8 B  is a plot showing electrical power generated by a piezoelectric sensor in accordance with some embodiments.  FIG.  8 B  shows the difference in the electrical power generated by the sensor module at a high speed of travel (left box) and at a low speed of travel (right box). Thus, the sensor module described herein has provided both information associated with the driving condition (e.g., pulse frequency) and electrical power. 
       FIG.  9    is a flow diagram illustrating a method  900  of generating electrical signals with one or more piezoelectric sensors coupled on an elastic support, in accordance with some embodiments. 
     The method  900  includes ( 910 ) receiving a force on a tire (e.g., tire  220  in  FIG.  5   ) mounted on a rim (e.g., rim  210  in  FIG.  5   ) of a wheel. The tire is in contact with an elastic support (e.g., section C or D of  FIG.  5   ) with one or more piezoelectric sensors coupled thereon so that the force causes strain in the elastic support and the one or more piezoelectrical sensors (e.g.,  FIG.  3   ); and, ( 920 ) in response to receiving the force, generating electrical signals from the one or more piezoelectric sensors. 
     In some embodiments, the method  900  includes ( 930 ) determining a driving condition of the wheel based on the electrical signals generated from the one or more piezoelectric sensors (e.g., the pulse frequency may be obtained from the electrical signals). 
     In light of these examples and principles explained herein, we now turn to certain embodiments. 
     In accordance with some embodiments, a sensor module mountable adjacent to a rim of a wheel includes a first set of one or more piezoelectric sensors (e.g., piezoelectric sensor  240  in  FIG.  4 A ); and a first elastic support (e.g., elastic support  230  in  FIG.  4 A ) with the first set of one or more piezoelectric sensors coupled thereon so that the first set of one or more piezoelectric sensors are spaced apart from the rim of the wheel (e.g., in  FIG.  4 B , the piezoelectric sensor is not in contact with, and is spaced apart from, the rim  210 ). 
     In some embodiments, the first elastic support has a cross-section (e.g., a radial cross-section that is perpendicular to an axis defined by a portion of the rim where the sensor module is mounted as shown in  FIG.  2 A , and not a cross-section that is perpendicular to an axis of the wheel) that includes at least a partially closed curve (e.g., the first elastic support has a shape of a partially-open tube). For example, the first elastic support may have the second end  198  that is not in contact with the first end  196  as shown in the top portion of  FIG.  3   . 
     In some embodiments, the cross-section includes a fully enclosed curve (e.g., both ends of the first elastic support meet with, or overlap, each other, or the first elastic support has a shape of a loop or a hoop as shown in  FIG.  2 C ). 
     In some embodiments, the sensor module includes a base (e.g., the base  250  in  FIG.  4 A ) onto which the first elastic support is coupled. 
     In some embodiments, the first elastic support has a first end and a second end that is opposite to the first end (e.g., the first end  196  and the second end  198 ), and the first end is rigidly coupled with the base (e.g., in  FIG.  2 A , the first end  196  may be rigidly coupled to the base  250 ). 
     In some embodiments, the first elastic support has a first end and a second end that is opposite to the first end; and the first end is rotatably coupled with the base (e.g., in  FIG.  2 A , the first end  196  may be rotatably coupled to the base  250  so that the first end  196  does not slide relative to the base  250  but may rotate along the contact between the first end  196  and the base  250 ). 
     In some embodiments, the second end is rigidly coupled with the base. In some embodiments, the second end is movably coupled with the base. In some embodiments, the second end is not coupled with the base. 
     In some embodiments, the base includes electrical circuit electrically coupled with the first set of one or more piezoelectric sensors. 
     In some embodiments, the first elastic support includes an inner surface and an outer surface that is opposite to the inner surface; and the first set of one or more piezoelectric sensors include at least one piezoelectric sensor mounted on the inner surface (e.g., see  FIG.  6   ). 
     In some embodiments, the sensor module includes a second set of one or more piezoelectric sensors; and a second elastic support with the second set of one or more piezoelectric sensors coupled thereon so that the second set of one or more piezoelectric sensors are spaced apart from the rim of the wheel (e.g., see  FIG.  7 B ). 
     In accordance with some embodiments, a wheel includes a rim and any sensor module described herein (e.g., see  FIG.  4 B ). 
     In some embodiments, the wheel includes a tire mounted on the rim (e.g., see  FIG.  5   ). 
     In some embodiments, the first elastic support of the sensor module has a point or line contact with the tire (e.g., see  FIG.  2 C ). 
     In some embodiments, the first elastic support of the sensor module has a plane contact with the first elastic support (e.g., see  FIG.  2 A ). 
     In some embodiments, the wheel includes a tube. The first elastic support substantially encircles the tube (e.g., see section C of  FIG.  5   ). 
     In some embodiments, the first set of one or more piezoelectric sensors includes at least one piezoelectric sensor in contact with the tube (e.g., see section C of  FIG.  5   ). 
     The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the scope of claims to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the various described embodiments and their practical applications, to thereby enable others skilled in the art to best utilize the principles and the various described embodiments with various modifications as are suited to the particular use contemplated.