System and method for measuring a relative distance between vehicle components using ultra-wideband techniques

A system for measuring relative distance between a first component on a vehicle and a second component on the vehicle is provided. The system includes a wireless ultra-wideband (UWB) transceiver attached to the first component. The wireless UWB transceiver transmits a UWB measurement pulse toward the second component, and receives a reflected UWB pulse from a reflective surface of the second component. The reflected UWB pulse represents a reflected version of the UWB measurement pulse. The system also includes a processor coupled to the wireless UWB transceiver. The processor derives a relative distance between the first component and the second component, based upon characteristics of the UWB measurement pulse and the reflected UWB pulse. The system further includes a power generating system for the wireless UWB transceiver. The power generating system generates operating voltage for the wireless UWB transceiver from kinetic energy associated with motion of the first component relative to the second component.

TECHNICAL FIELD

Embodiments of the subject matter described herein relate generally to onboard vehicle sensor systems. More particularly, embodiments of the subject matter relate to systems and methods for measuring a relative distance between two vehicle components, such as the height between the unsprung vehicle mass and the sprung vehicle mass.

BACKGROUND

Modern automobiles utilize a variety of sensors to detect various operating parameters, conditions, and quantities associated with the operation of the automobiles. For example, a vehicle may utilize onboard sensors and a related control module or processor to measure the height between the sprung and unsprung vehicle mass. Such height measurements can be used in connection with an electronic stability control subsystem, an anti-roll subsystem, a dynamic suspension control subsystem, or the like.

One existing system that measures the height between the sprung and unsprung vehicle mass uses a mechanical linkage assembly that is physically coupled between an unsprung suspension component and a sprung suspension component. The linkage assembly moves with the unsprung suspension component along with the respective wheel. Movement of the linkage assembly influences the reading of a position sensor. Unfortunately, the mechanical linkage assembly is prone to damage, which increases maintenance cost. In addition, the electromechanical linkage is time consuming to install, and its components are relatively expensive.

BRIEF SUMMARY

A first embodiment of a system for measuring relative distance between a first component on a vehicle and a second component on the vehicle is provided. The system includes a wireless ultra-wideband (UWB) transceiver attached to the first component. The wireless UWB transceiver is configured to transmit a UWB measurement pulse toward the second component, and to receive a reflected UWB pulse from a reflective surface of the second component. The reflected UWB pulse represents a reflected version of the UWB measurement pulse. The system also includes a processor coupled to the wireless UWB transceiver. The processor is configured to derive a relative distance between the first component and the second component, based upon characteristics of the UWB measurement pulse and the reflected UWB pulse. The system also has a power generating system for the wireless UWB transceiver. The power generating system is configured to generate operating voltage for the wireless UWB transceiver from kinetic energy associated with motion of the first component relative to the second component.

Also provided is a second embodiment of a system for measuring relative distance between a first component on a vehicle and a second component on the vehicle. This system includes a UWB transceiver coupled to the first component. The UWB transceiver is configured to operate in a measurement mode and a reporting mode. The system also includes a reflector on the second component. The reflector is configured to reflect UWB measurement pulses generated by the UWB transceiver. The system also has a processor coupled to the UWB transceiver. The processor is configured to control operation of the UWB transceiver in the measurement mode and the reporting mode. While operating in the measurement mode, the UWB transceiver transmits a UWB measurement pulse toward the reflector, and receives a reflected UWB pulse from the reflector, where the reflected UWB pulse represents a reflected version of the UWB measurement pulse. Moreover, while operating in the measurement mode, the processor calculates a relative distance between the first component and the second component, based upon characteristics of the UWB measurement pulse and the reflected UWB pulse. While operating in the reporting mode, the UWB transceiver transmits one or more signals that convey information associated with the relative distance.

A method of measuring relative distance between a first component on a vehicle and a second component on the vehicle is also provided. The method involves generating electrical current in response to movement of the first component, and converting the electrical current into a DC operating voltage for a UWB transceiver that is attached to the first component. The method also involves transmitting a UWB measurement pulse from the UWB transceiver, such that the UWB measurement pulse is directed toward a reflective element of the second component. The UWB transceiver receives a reflected UWB pulse from the reflected element. The method continues by determining a distance measurement based upon a propagation time associated with the UWB measurement pulse and the reflected UWB pulse. The distance measurement indicates a distance between the first component and the second component.

DETAILED DESCRIPTION

The subject matter described herein relates to a self-powered and cost effective system that is capable of performing highly precise and highly reliable measurements of absolute relative position between sprung and unsprung mass of a vehicle, while using an energy harvesting system or device to provide the energy needed to power the measurement system. In certain embodiments, the measurement system employs a high precision ultra-wideband (UWB) device, mounted on sprung and/or unsprung mass of the vehicle, to measure the absolute relative distance between sprung and unsprung mass components. The UWB transceiver transmits a pulse, which reflects off a reflector or a reflective surface, and is subsequently detected and recovered at the UWB transceiver node. The delay time between the transmitted and received pulse is determined, and the absolute relative distance between sprung and unsprung mass is calculated from this delay time.

In certain embodiments, the UWB transceiver is powered by an electromagnetic energy harvesting device that is integrated into a damper assembly of the vehicle. In addition, the UWB transceiver could transmit the measured information wirelessly to a vehicle controller or control module using UWB techniques. In one preferred embodiment, a permanent magnet is mounted on the damper body and a magnetic coil is mounted inside the dust cover of the damper. Current is induced in the coil when the magnet moves (due to movement of the damper body relative to the dust cover). Alternatively, a permanent magnet can be mounted on the inside of the dust cover, and the coil can be mounted around the damper tube. The system may include a rectifier to convert the induced current into DC power that can be used to recharge an energy source for the measurement system. The energy source may, in turn, be used to operate the UWB transceiver.

The measurement system described herein is advantageous because it leverages non-contact position sensing with reduced cost, and increased reliability and accuracy. Moreover, the measurement system is self-powered, transmits the measurement data wirelessly, and eliminates the need for data and power transmission wires to and from the vehicle controller.

The distance and height measurement systems described here can be suitably configured to measure, detect, or estimate the distance between a first component and a second component, where the two components exhibit movement or motion relative to one another. Although the preferred embodiments relate to the measurement of a distance between two components on a host vehicle, the techniques and technologies described here need not be so limited. In this regard,FIGS. 1-3are diagrams that illustrate relative motion and distance between two components.FIG. 1depicts a situation where a first (upper) component102can move up and down relative to a second (lower) component104, which represents or is connected to a stationary reference location. The distance106between upper component102and lower component104is indicated inFIG. 1. Of course, the distance106will vary in accordance with the current absolute position of upper component102.

FIG. 2depicts a situation where an upper component112represents or is connected to a stationary reference location. InFIG. 2, a lower component114can move up or down relative to the fixed position of upper component112. The distance116between upper component112and lower component114at any given moment in time will be defined in accordance with the current absolute position of lower component114.

FIG. 3depicts a situation where an upper component122is free to move relative to a lower component124, and vice versa. In other words, upper component122and lower component124are each able to move independently, and neither is fixed or stationary. For this scenario, the distance126between upper component122and lower component124at a given time will be dictated by both the current absolute position of upper component122and the current absolute position of lower component124.

As mentioned previously, the measurement systems described herein are suitable for use with onboard vehicle applications. In this regard,FIG. 4is a diagram that illustrates relative displacement between sprung and unsprung mass of a vehicle200. As used herein, “unsprung” refers to mass, components, features, or elements of a vehicle that are coupled to the ground202or some other reference location in a substantially rigid manner (i.e., coupled to the ground202with no dampers, springs, cushions, or the like therebetween). Thus, the tires, brake rotors, axles, and undamped suspension links are typically deployed as unsprung components. In contrast, “sprung” refers to mass, components, features, or elements of a vehicle that are coupled to the ground202or some other reference location via one or more spring, damper, cushion, or resilient components. Thus, the passenger cabin, engine, and most body panels are typically deployed as sprung components. The simplified diagram ofFIG. 4assumes that the wheels204are unsprung components, and that the body206of vehicle200is a sprung component. Vehicle200may include any number of spring and damper assemblies208, which couple the sprung mass to the unsprung mass.

FIG. 4represents a scenario that is similar to that depicted inFIG. 1. In this regard, the sprung mass of vehicle200is analogous to first component102in that it can move up and down relative to the ground202and relative to the unsprung mass of vehicle200. On the other hand, the ground202, the wheels204, and other unsprung mass of vehicle200are analogous to second component104inFIG. 1. As described above, it is desirable to detect the height between sprung and unsprung components of a vehicle in real-time (or substantially real-time) for purposes of improved ride and handling, vehicle height control, stability control, traction control, and the like.

FIG. 5is a cross sectional view of a first embodiment of a suspension damper assembly300that incorporates a system for measuring distance between two components of the damper assembly.FIG. 5represents a longitudinal sectional view of damper assembly300. In practice, at least one damper assembly300is used for each wheel of the host vehicle. In typical deployments, one damper assembly300is located near each corner of the host vehicle, proximate each wheel.

Damper assembly300generally includes a first component and a second component coupled to the first component in a way that accommodates relative movement between the two components. One of the two components represents, corresponds to, is attached to, or is connected to a sprung component of the host vehicle, while the other component represents, corresponds to, is attached to, or is connected to an unsprung component of the host vehicle. Although the specific configuration of damper assembly300may vary from one implementation to another, this exemplary embodiment generally includes, without limitation: an outer cover302; a damper tube304; an upper mounting element306; a lower mounting element308; a bumper310; and a rod312. These features of damper assembly300cooperate with each other in a well-known and conventional manner, and a practical implementation of damper assembly300may include additional elements, components, or features that are not depicted inFIG. 5.

Upper mounting element306is used to mount damper assembly300to one component of the host vehicle, and lower mounting element308is used to mount damper assembly300to another component of the host vehicle. For this particular example, upper mounting element306is designed to be attached to a sprung mass component of the host vehicle (e.g., the frame or a body side rail), and lower mounting element308is designed to be attached to an unsprung mass component of the host vehicle (e.g., a lower control arm or a solid axle that, in turn, is attached to a wheel). Accordingly, outer cover302and other components that are rigidly attached to, and are stationary with respect to, outer cover302may be considered to be a sprung portion of damper assembly300. Conversely, damper tube304and other components that are rigidly attached to, and are stationary with respect to, damper tube304may be considered to be an unsprung portion of damper assembly300.

As understood by those familiar with suspension damper assemblies, damper tube304can move back and forth relative to (and at least partially within) outer cover302. Damper tube304includes a damping fluid314enclosed therein, and a piston316coupled to rod312. Piston316and damping fluid314cooperate to inhibit or impede free movement of damper tube304relative to outer cover302, in a known manner. Bumper310, which is optional, is located in the interior space defined by outer cover302, mounted toward the upper mounting element306. Bumper310is a resilient element that compresses to further damp the travel of damper tube304as it nears the end of its range. The lower end318of bumper310could engage a stopper plate320or, in alternate embodiments, the top end322of damper tube304itself.

Damper assembly300incorporates certain features, elements, and components of a system that measures the relative distance between sprung and unsprung components of damper assembly300. In this regard, the exemplary embodiment depicted inFIG. 5includes, without limitation: a magnet350; a coil352; a wireless ultra-wideband (UWB) transceiver354; and an interface module356. Coil352is electrically coupled to interface module356using, for example, one or more wires. Interface module356is electrically coupled to UWB transceiver354using, for example, one or more wires. For the sake of clarity and simplicity, these electrical couplings are not depicted inFIG. 5.

Magnet350may be realized as a ring-shaped permanent magnet that is attached to damper tube304. In this embodiment, magnet350wraps around the outside of damper tube304at a location that resides within outer cover302. Notably, magnet350is fixed to damper tube304such that it moves in concert with damper tube304. In other words, any translation of damper tube304relative to outer cover302will result in the same translation of magnet350. The specific size, shape, electromagnetic characteristics, and longitudinal mounting position of magnet350on damper tube304may vary from one embodiment to another, as needed to accommodate the operating requirements of the particular application.

Coil352may be realized using one or more electrical conductors (e.g., copper wire) that are wound in an appropriate manner. Coil352may be packaged as a ring or annular sleeve that is attached to outer cover302at a location that accommodates electromagnetic coupling with magnet350. In this embodiment, coil352is positioned around the inner wall of outer cover302at location adjacent to magnet350and in a manner that provides physical clearance between magnet350and coil352. In preferred embodiments, the longitudinal dimension of coil352accommodates the travel range of magnet350. In other words, the magnetic field generated by magnet350should have an influencing effect on coil352regardless of the position of damper tube304relative to outer cover302. Notably, coil352is fixed to outer cover302such that it moves in concert with outer cover302. In other words, any translation of outer cover302relative to damper tube304will result in the same translation of coil352. The specific size, shape, electromagnetic characteristics, and longitudinal mounting position of coil352on outer cover302may vary from one embodiment to another, as needed to accommodate the operating requirements of the particular application.

Movement of magnet350relative to coil352induces electrical current in coil352, in accordance with well known electromagnetic induction principles. Thus, motion of damper tube304relative to outer cover302will establish current in coil352. In a vehicle deployment as described here, the current induced in coil352may vary in magnitude and frequency, depending upon the operating conditions. For example, if the vehicle is stationary and the suspension is completely passive, then little or no electrical current will be established in coil352. Conversely, if the vehicle is driving at a high velocity and over a very rough or bumpy road, then electrical current with relatively high magnitude and frequency will be generated.

Coil352is electrically coupled to interface module356such that any induced electrical current can be provided to interface module356for conditioning, processing, handling, etc. Depending upon the embodiment, interface module356may be located outside of outer cover302(as shown) or inside of outer cover302. Moreover, preferred embodiments utilize a hermetically sealed package for interface module356that is suitable for typical vehicle operating environments. Interface module356is suitably configured to convert the induced electrical current into one or more useable DC voltages. The one or more DC voltages may then be used to charge at least one energy storage element and/or be used to power interface module356and UWB transceiver354. An exemplary implementation of interface module356is described in more detail below with reference toFIG. 6.

UWB transceiver354is electrically coupled to interface module356in a manner that accommodates signal and/or data transmission between UWB transceiver354and interface module356. Notably, UWB transceiver354is realized as a device or component that is attached, rigidly connected, or fixed to outer cover302such that it moves in concert with outer cover302. In other words, any translation of outer cover302relative to damper tube304will result in the same translation of UWB transceiver354. In the illustrated embodiment, the mounting location for UWB transceiver354is a cap358(which may also serve as a retaining element for bumper310). Preferred embodiments utilize a hermetically sealed package for UWB transceiver354that is suitable for typical vehicle operating environments.

UWB transceiver354, which preferably operates under the control of interface module356, is suitably configured to transmit and receive UWB signals as needed to support the distance measuring system. UWB transceivers and technologies are known to those familiar with radio frequency (RF) communication techniques, and UWB technology will not be described in detail here. UWB transceiver354preferably includes at least one antenna, a receiver element, a transmitter element, and other RF front end elements that are typically found in RF transceiver devices.

UWB transmissions are characterized by very low power levels that utilize a very large portion of the RF spectrum. The UWB signals generated by UWB transceiver354may be considered to be very low power pulses that are very narrow in the time domain, but are very wide in the frequency domain. Typical UWB signals may contain frequency content that is spread within the frequency band of 3.1 GHz to 10.6 GHz. The characteristics of UWB signals make them particularly suitable for onboard vehicle applications that might otherwise introduce high amounts of signal interference, signal reflections, etc. UWB technology can deliver high quality of service in relatively harsh electromagnetic interference environments, e.g., an automobile deployment.

UWB transceiver354is suitably configured to transmit UWB measurement pulses toward damper tube304, and to receive corresponding UWB pulses that have been reflected from a reflective surface associated with damper tube304. In other words, each UWB measurement pulse propagates from UWB transceiver354, to the reflective surface, and back to UWB transceiver354. In this description, a “reflected UWB pulse” represents a reflected version of a corresponding UWB measurement pulse. Thus, a reflected UWB pulse is actually a UWB measurement pulse that has propagated along a certain path, and a reflected UWB pulse received at UWB transceiver354is actually a UWB measurement pulse that has returned to UWB transceiver354.

Notably, the reflective surface of damper is realized on a feature or component that is attached, rigidly connected, or fixed to damper tube304such that it moves in concert with damper tube304. In other words, any translation of damper tube304relative to outer cover302will result in the same translation of the reflective surface. In the illustrated embodiment, the reflective surface is realized on stopper plate320(accordingly, stopper plate320may be considered to be a reflector for UWB transceiver354). Alternatively, the reflective surface could be realized on the top end322of damper tube304. Alternatively, the reflective surface could be realized elsewhere on damper tube304or on another component that is rigidly attached to damper tube304.

The reflective surface has certain characteristics that make it a good reflector of UWB signals and UWB energy. This allows the reflector to efficiently reflect UWB measurement pulses generated by UWB transceiver354. For example, the reflective surface can be a smooth surface of an electrically conductive material such as metal. Ideally, the reflective surface can effectively and efficiently reflect UWB signals with little loss in energy, thus improving the detection capability of UWB transceiver354. In this regard, UWB transceiver354and the reflective surface are configured, arranged, and located so as to maximize the energy of the reflected signal. In certain embodiments, the reflective surface can be constructed so as to focus the reflected energy toward the UWB transceiver354.

Operation of damper assembly300and its integrated distance measurement system will be further described with reference toFIG. 6, which is a schematic representation of an embodiment of a system400for measuring relative distance between two components. This embodiment of system400includes a magnet402, a coil404, a rectifier/regulator406, at least one energy source408, at least one processor410, and a UWB transceiver412. These elements of system400can be coupled together in an appropriate manner to accommodate the transfer of signals, voltage, current, data, control commands, and the like. System400may also include a reflector414and a control module416. In practice, interface module356(seeFIG. 5) may include or otherwise be associated with rectifier/regulator406, energy source408, and processor410. Indeed, interface module356may be realized using any number of distinct circuits, devices, processor elements, electrical components, or the like.

Referring again toFIG. 6, magnet402, coil404, UWB transceiver412, and reflector414can be configured and arranged as described above for damper assembly300, and these elements will not be redundantly described in detail here. The two leads of coil404are coupled to rectifier/regulator406such that the induced current in coil404can be received by rectifier/regulator406. Rectifier/regulator406is suitably configured to convert the induced coil current or voltage (which may be considered to be an AC voltage) into one or more DC voltages, using very well known voltage rectification techniques. In addition, rectifier/regulator406regulates the DC voltage or voltages to provide relatively stable and constant DC output. In certain embodiments, rectifier/regulator406converts the induced coil current into a DC operating voltage that is used to power UWB transceiver412. This DC operating voltage can also be used to power processor410and/or other electronic components of system400. The DC voltage generated by rectifier/regulator406may be within the range of about 100 mV to about 300 mV, depending upon the needs of system400. In practice, this voltage range may vary as needed to accommodate the needs of the intended application.

Energy source408is preferably realized as a rechargeable energy storage element that can provide DC operating voltage to processor410, UWB transceiver412, and/or other electronic components of system400. In practice, energy source408can be recharged with the DC voltage output of rectifier/regulator406, as depicted inFIG. 6. In other words, energy source408is recharged in response to the electrical current induced in coil404. Although more than one energy source408could be deployed, preferred embodiments use one rechargeable energy source408, which may be realized using a battery, a capacitor, a super-capacitor, or the like.

It should be appreciated that magnet402, coil404, and rectifier/regulator406cooperate to form one embodiment of a power generating system for certain components of system400(e.g., processor410and/or UWB transceiver412). Such a power generating system may also be referred to herein as an energy harvesting system. As explained herein, such a power generating system generates operating voltage from kinetic energy that is associated with motion or movement of a first component (e.g., the component to which magnet402is attached) relative to a second component (e.g., the component to which coil404is attached). At least some of this kinetic energy is converted into the induced electrical current, which in turn can be converted into the DC operating voltage.

Processor410may be implemented or performed with a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination designed to perform the functions described here. A processor may be realized as a microprocessor, a controller, a microcontroller, or a state machine. Moreover, a processor may be implemented as a combination of computing devices, e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration.

Generally, processor410is suitably configured to control the operation of UWB transceiver412. As described in more detail below, UWB transceiver412may be designed for operation in a plurality of different modes, including a measurement mode and a reporting mode. Accordingly, processor410can regulate and switch the operating modes, and otherwise control the operation of system400as needed to support the different operating modes. As described in more detail below, while operating in the measurement mode, processor410derives or calculates the distance between the two monitored components (e.g., the damper and outer cover of a damper assembly), where the distance is based upon certain characteristics of the UWB measurement pulse and the corresponding UWB reflected pulse. Moreover, while operating in the reporting mode, processor410controls the transmission of information from UWB transceiver412to a receiving element or component, such as control module416.

The reporting mode of system400can be utilized to send measurement data to control module416, which in turn can receive, interpret, analyze, and initiate an appropriate response. The measurement data is preferably sent with an appropriate identifier or data that uniquely identifies the measured location or component (unique at least within the monitored vehicle environment). For example, if the vehicle has four dampers, then the measurement data transmitted by each of the four UWB transceivers will include a respective identifier, e.g., a Damper ID. Thus, control module416preferably includes or cooperates with a UWB receiver or transceiver that is capable of receiving UWB signals or pulses generated by UWB transceiver412. The UWB receiver will be located within the operating or transmit range of UWB transceiver412. In practical embodiments, control module416may be an onboard electronic controller of the host vehicle, and control module416may include additional functionality that is unrelated to the operation of system400. For example, control module416may be associated with an active stability control subsystem, a traction control subsystem, an anti-roll subsystem, a dynamic active suspension subsystem, or other subsystem of the vehicle, where such a subsystem can process and react to the dynamically changing distance/height between the sprung and unsprung mass components of the vehicle.

It should be appreciated that certain operations and functions may be distributed among the various elements of system400, and that the above description is merely one possible implementation. For example, UWB transceiver412may include some processing capability that allows it to convert the raw sensor data (e.g., the pulse propagation time) into a more usable format, such as a distance measurement. As another example, the raw sensor data could be transmitted to control module416, which in turn may be responsible for converting and/or reformatting the raw sensor data. As yet another example, processor410may be suitably configured to perform most of the post-measurement processing on behalf of control module416, such that useful data can be sent to control module416, which can react immediately when it receives that useful data.

Moreover, the elements depicted inFIG. 6need not be packaged or arranged as shown. For instance, energy source could be integrated into rectifier/regulator406. As another example, processor410could be integrated into UWB transceiver354. Indeed, as described below with reference toFIG. 8, many of the elements shown inFIG. 6could be integrated into a single component.

Operation of damper assembly300and system400will now be described with reference toFIG. 7(a flow chart that illustrates a method of generating electrical energy while measuring distance between two components on a vehicle). The various tasks of the distance measurement process500depicted inFIG. 7may be performed by software, hardware, firmware, or any combination thereof. For illustrative purposes, the following description of process500may refer to elements mentioned above in connection withFIGS. 1-6. In practice, portions of process500may be performed by different elements of the described system, e.g., the coil, the energy source, the processor, or the UWB transceiver. It should be appreciated that process500may include any number of additional or alternative tasks, the tasks shown inFIG. 7need not be performed in the illustrated order, and process500may be incorporated into a more comprehensive procedure or process having additional functionality not described in detail herein.

FIG. 7depicts several tasks that are carried out continuously while the vehicle is operating. For example, process500generates electrical current in response to the movement of the damper component relative to the outer cover component (task502). As mentioned above, the electrical current is induced in the coil when the magnet translates relative to the coil, and such electrical current generation may occur at any time and continuously during vehicle operation. The induced electrical current is converted into a DC operating voltage (task504) that is suitable for the UWB transceiver, and that same DC operating voltage can be used to charge one or more energy storage elements (task506). Process500can operate the UWB transceiver, the processor, and possibly other components with the stored energy and/or with the DC operating voltage itself (task508). Notably, tasks502,504,506, and508represent “background” tasks that can be performed continuously and regardless of the operating mode of the distance measurement system. In practice, tasks502,504,506, and508will be performed in parallel with the remaining tasks depicted inFIG. 7.

Process500is arranged in accordance with an exemplary embodiment that cycles through at least two different operating modes: a measurement mode and a reporting mode. During the measurement mode, the distance between the two components is measured. Tasks510,512,514, and516can be performed during the measurement mode. Thereafter, during the following reporting mode, the previously measured distance is reported or transmitted to a control module (such as the control module416shown inFIG. 6). Tasks518,520, and522can be performed during the reporting mode. In preferred embodiments that utilize a single UWB transceiver, the measurement mode and the reporting mode are sequential in time. In practice, a distance measurement could be taken once every 1.0 to 10.0 ms, depending on the application. Such a high sample rate is desirable to ensure that the distance is monitored and measured in virtually real-time.

While operating in the measurement mode, process500transmits a UWB measurement pulse or signal from the UWB transceiver (task510). The UWB measurement pulse is directed toward the reflective element, which then reflects the UWB measurement pulse back to the UWB transceiver (in the form of a reflected UWB pulse). The UWB transceiver receives the reflected UWB pulse (task512) from the reflective element. Thereafter, process500may calculate the pulse propagation time (task514) associated with the UWB measurement pulse and the reflected UWB pulse. As used here, the pulse propagation time is derived from the transmit time of the UWB measurement pulse and the receipt time of the reflected UWB pulse. In preferred embodiments, the pulse propagation time is simply calculated as the difference between the receipt time and the transmit time.

As is well understood, the pulse propagation time will be dependent upon the current distance between the UWB transceiver and the reflective surface. Consequently, the pulse propagation time will be indicative of the distance between the two monitored components of interest (e.g., the damper and the outer cover). Accordingly, process500may continue by calculating, deriving, or otherwise determining a distance measurement, such as the relative distance between the two components (task516). Again, this distance measurement will be based upon or otherwise influenced by the pulse propagation time. It should be appreciated that the distance measurement may be expressed in any convenient scale, and that the distance measurement may indicate the distance between any two reference points associated with the monitored system. For example, the distance measurement may indicate the actual real-world distance between the UWB transceiver and the reflective surface. Alternatively, the distance measurement may indicate the actual real-world distance between a first reference location on the damper component and a second reference location on the outer cover. In other words, the distance measurement may represent a translated, offset, transformed, or scaled distance that is merely based upon the pulse propagation time. The distance measurement need not be strictly linked to the two features or surfaces used to obtain the pulse propagation time. Moreover, the distance measurement can be expressed using any arbitrary and convenient scale that is appropriate for the intended application. In general, the system can implement an algorithm that converts time of flight of the UWB signal into a number or expression that represents the derived separation distance (d) as a function of the time difference: d=f(Δt).

After the processor determines the distance measurement, process500may enter the reporting mode. While operating in the reporting mode, the distance measurement can be formatted, configured, packaged, modulated, or otherwise prepared for UWB transmission (task518). An example could involve a packet data based transmission scheme where the header associated with the packet data indicates the vehicle damper location and/or a unique node identification, along with derived measured data. The packet data could also contain various data transmission error detection and correction schemes that are well known to those skilled in the art. It should be appreciated that process500could leverage a number of well known wireless data communication techniques and modulation technologies during task518. Once the distance measurement information is ready for transmission, the UWB transceiver can transmit one or more distance measurement signals or pulses that convey information or data that is associated with the distance measurement (task520).

FIG. 7assumes that the distance measurement signals or pulses transmitted during task520are successfully received with a UWB receiver of an onboard control module (task522). Once received, the distance measurement signals or pulses can be processed with the onboard control module in an appropriate manner and as needed (task524). For example, the control module might demodulate, extract or otherwise obtain the distance measurement and apply that distance measurement in accordance with whatever control scheme or data processing scheme is required by the particular vehicle system. The post-reception processing carried out during task524need not be performed during the reporting mode. Rather, task524could be executed during subsequent distance measurement and/or subsequent reporting cycles.

Referring again toFIG. 5, damper assembly300utilizes magnet350and coil352to generate electrical current in a self-powering manner. Alternatively, the power generating system could employ an electromagnetic energy harvester that is attached to one of the moving components (or two harvesters, each attached to a respective one of the two moving components). In this regard,FIG. 8is a cross sectional view of a second embodiment of a suspension damper assembly600that incorporates a system for measuring distance between two of its components. Damper assembly600is similar to damper assembly300in many respects, and common features and characteristics will not be redundantly described here.

Damper assembly600includes an outer cover602, a damper604, an upper mounting element606, an upper structural element608coupled to upper mounting element606and/or to outer cover602, and a lower structural element610coupled to damper604. In some embodiments, upper structural element608is configured to function as an upper spring seat for damper assembly600, and lower structural element610is configured to function as a lower spring seat for damper assembly600. The spring seats cooperate with a coil spring or air spring (not shown) that surrounds damper604and outer cover602. The spring seats maintain the coil spring in place and the lower spring seat moves in concert with damper604.

Damper assembly600preferably includes a distance measurement module620that is connected to lower structural element610. Notably, distance measurement module620is fixed to damper604such that it moves in concert with damper604. In other words, any translation of damper604relative to outer cover602will result in the same translation of distance measurement module620.

Distance measurement module620may be realized using any number of distinct circuits, devices, processor elements, electrical components, or the like. In practice, distance measurement module620may include or otherwise be associated with an electromagnetic energy harvester, a rectifier/regulator, at least one energy source, a processor, and a UWB transceiver. As used here, an electromagnetic energy harvester is a device or a small self-contained unit that is suitably configured to produce electrical current in response to shaking, vibration, movement, or motion thereof. In practice, an electromagnetic energy harvester may include a spring-mounted permanent magnet that is surrounded by an electrically conductive coil. When the energy harvester is shaken or vibrated, the magnet moves relative to the coil, thus inducing electrical current in the coil. Accordingly, the energy harvester functions in a manner similar to that described above for damper assembly300and system400. Indeed, distance measurement module620represents a self-contained package that incorporates all of the elements depicted inFIG. 6(excluding reflector414and control module416).

Referring again toFIG. 8, distance measurement module620is positioned such that it can transmit UWB measurement pulses toward upper structural element608. Notably, upper structural element608serves as a reflector for the UWB measurement pulses. Distance measurement module620and upper structural element608are preferably arranged and configured such that a path622can be established between distance measurement module620and upper structural element608. The operation of damper assembly600and its integrated distance measuring system are similar to that described above for damper assembly600and system400.

FIG. 9is a cross sectional view of a third embodiment of a suspension damper assembly700that incorporates a system for measuring distance between two of its components. Damper assembly700is similar to damper assembly300in some respects, and similar to damper assembly600in some respects. For the sake of brevity, common features and characteristics will not be redundantly described here.

Damper assembly700includes an outer cover702, a damper704, an upper mounting element706, an upper structural element708coupled to upper mounting element706and/or to outer cover702, and a lower structural element710coupled to damper704. Damper assembly700also includes a magnet712attached to outer cover702, and a coil714attached to damper704. Note that the locations of magnet712and coil714are opposite to that utilized by damper assembly300.

Damper assembly700preferably includes a distance measurement module720that is connected to lower structural element710. Notably, distance measurement module720is fixed to damper704such that it moves in concert with damper704. Distance measurement module720can be electrically coupled to coil714using one or more wires721or conduits. Distance measurement module720may be realized using any number of distinct circuits, devices, processor elements, electrical components, or the like. In practice, distance measurement module720may include or otherwise be associated with a rectifier/regulator, at least one energy source, a processor, and a UWB transceiver. In certain embodiments, distance measurement module720represents a self-contained package that incorporates these elements.

Distance measurement module720is positioned such that it can transmit UWB measurement pulses toward upper structural element708. Notably, upper structural element708serves as a reflector for the UWB measurement pulses. Distance measurement module720and upper structural element708are preferably arranged and configured such that a propagation path722can be established between distance measurement module720and upper structural element708. The operation of damper assembly700and its integrated distance measuring system are similar to that described above for damper assembly600and system400.

FIGS. 5,8, and9illustrate preferred deployments that involve damper assemblies. However, a distance measuring system as described herein could be incorporated into other assemblies for use with different applications. For example,FIG. 10is a side view of a portion of a vehicle suspension assembly800that incorporates a system for measuring distance between two of its components. In particular, suspension assembly800includes a frame or body side rail802, a suspension link or component804, a damper assembly806, and a distance measuring module808. Frame or body side rail802is considered to be a sprung mass component, and suspension link or component804is considered to be an unsprung mass component.

During vehicle operation, the distance between frame or body side rail802and suspension link or component804will vary. Distance measuring module808can be used to measure the instantaneous height810between frame or body side rail802and suspension link or component804, using the techniques and technologies described in more detail above. In this regard, distance measuring module808is preferably configured as described above for distance measurement module620, which includes an energy harvester device (seeFIG. 8).

In alternate embodiments, a suitably arranged distance measuring system could be deployed to measure a distance, height, length, width, depth, or any specified dimension associated with various onboard vehicle systems, components, or devices. For example, embodiments of a distance measuring system could be modified for use with one or more of the following applications: a lifting gate strut assembly; a hood lift mechanism; a convertible top assembly; a sunroof, a passenger door; a pedal mechanism; or the like.