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Passive wireless strain monitoring of tyres using capacitance and tuning frequency changes
Abstract
In-service strain monitoring of tyres of automobiles is quite effective for improving the reliability of tyres and anti-lock braking systems (ABS). Conventional strain gauges have high stiffness and require lead wires. Therefore, they are cumbersome for tyre strain measurements. In a previous study, the authors proposed a new wireless strain monitoring method that adopts the tyre itself as a sensor, with an oscillating circuit. This method is very simple and useful, but it requires a battery to activate the oscillating circuit. In the present study, the previous method for wireless tyre monitoring is improved to produce a passive wireless sensor. A specimen made from a commercially available tyre is connected to a tuning circuit comprising an inductance and a capacitance as a condenser. The capacitance change of the tyre alters the tuning frequency. This change of the tuned radio wave facilitates wireless measurement of the applied strain of the specimen without any power supply. This passive wireless method is applied to a specimen and the static applied strain is measured. Experiments demonstrate that the method is effective for passive wireless strain monitoring of tyres.
... Finally, the third challenge is to characterize the sensor in order to be useful for practical applications. In the literature, some alternatives to address this issue use piezoelectric sensors mounted in the tire [3][4][5][6][7]. All the tire sensors previously mentioned share some common problems: manufacturing these specialized sensors is expensive; these sensors need to be replaced at the same time as the tire is replaced, thus reducing the tire useful life because of the smaller life expectancy of the electronic components inside the tire; and finally, neither of this solutions have been fully implemented for practical use. ...
... In standard training, the input of the first layer and the network output are known, and the synaptic weights and biases are adapted to obtain an appropriate mapping from input to output. The standard adaptation is carried out by minimizing the network error function shown in Eq. (7). ...
... Since we have a set of experiments, the error value used in the selection process is computed by the following equation: (14) where N exp is the number of timelines and E exp is the error for each timeline using Eq. (7). ...
... We have also developed a battery-less wireless communication system composed of a tuning circuit, external transmitter and external receiver [15]. Since the tuning circuit acts as a frequency filter, the tuning frequency of the sensor can be wirelessly measured, without use of batteries in the sensor circuit. ...
... Therefore, braking torque can also be obtained from the compressive strain ratio obtained from the strain curve of the sensor. Figure 12 shows a schematic illustration of the proposed intelligent tire system including the sensing [14,23] and wireless transmission [13,15,25] proposed by the authors. The flexible sensor has advantages in that it is simple and easy to attach to existing tires. ...
From a traffic safety point-of-view, there is an urgent need for intelligent tires as a warning system for road conditions, for optimized braking control on poor road surfaces and as a tire fault detection system. Intelligent tires, equipped with sensors for monitoring applied strain, are effective in improving reliability and control systems such as anti-lock braking systems (ABSs). In previous studies, we developed a direct tire deformation or strain measurement system with sufficiently low stiffness and high elongation for practical use, and a wireless communication system between tires and vehicle that operates without a battery. The present study investigates the application of strain data for an optimized braking control and road condition warning system. The relationships between strain sensor outputs and tire mechanical parameters, including braking torque, effective radius and contact patch length, are calculated using finite element analysis. Finally, we suggested the possibility of optimized braking control and road condition warning systems. Optimized braking control can be achieved by keeping the slip ratio constant. The road condition warning would be actuated if the recorded friction coefficient at a certain slip ratio is lower than a 'safe' reference value.
... We have also developed a battery-less wireless communication system composed of a tuning circuit, external transmitter and external receiver (15) . Since the tuning circuit acts as a frequency filter, the tuning frequency of the sensor can be wirelessly measured, without use of batteries in the sensor circuit. ...
... Therefore, braking torque can also be obtained from the compressive strain ratio obtained from the strain curve of the sensor. Figure 12 shows a schematic illustration of the proposed intelligent tire system including the sensing (14, 23) and wireless transmission (13,15,25) proposed by the authors. The flexible sensor has advantages in that it is simple and easy to attach to existing tires. ...
From a traffic safety point-of-view, there is an urgent need for intelligent tires as a warning system for road conditions, for optimized braking control on poor road surfaces and as a tire fault detection system. Intelligent tires, equipped with sensors for monitoring applied strain, are effective in improving reliability and control systems such as anti-lock braking systems (ABSs). In previous studies, we developed a direct tire deformation or strain measurement system with sufficiently low stiffness and high elongation for practical use, and a wireless communication system between tires and vehicle that operates without a battery. The present study investigates the application of strain data for an optimized braking control and road condition warning system. The relationships between strain sensor outputs and tire mechanical parameters, including braking torque, effective radius and contact patch length, are calculated using finite element analysis. Finally, we suggested the possibility of optimized braking control and road condition warning systems. Optimized braking control can be achieved by keeping the slip ratio constant. The road condition warning would be actuated if the recorded friction coefficient at a certain slip ratio is lower than a `safe' reference value.
... Thank you. 8 The dissertation would not be possible in this form without Pekka Martelius. I want to thank Pekka for designing the tyre sensor components, keeping the data acquisition running, and fixing all the electrics that I all too often broke. ...
... • measuring tyre deflections with a sensor in suspension [7,8] and ...
Active safety systems would benefit from tyre force and friction potential information. Different sensor concepts, including, among others, the EU–funded Apollo–project developed tyre sensor based on optical position detection, are being studied. The sensor can measure tyre carcass deflections with respect to the rim. The carcass deflections can be used to calculate tyre forces and they may be exploited in the estimation of friction potential. The waveforms of the sensor signal are illustrated. The vertical and lateral force estimations are presented with unavoidable compensation parts. The tyre sensor measurements were compared to the measurement–vehicle results and good correlations achieved. Continuing activities are concerned with the estimation of friction potential and the detection of aquaplaning.
... Capacitance increases as the steel wire layer shrinks and vice versa. We can measure the strain by keeping track of the change in the capacitance [11]. ...
... Additionally, this method may not be able to provide enough resolution of strain signal to differentiate between a normal strain and a catastrophic failure [11]. ...
Structural Health Monitoring (SHM) of automobile tires is an active area of research. Within this area, the monitoring of strain on tires using wireless devices and networks is gaining prominence because these techniques do not require any wired connection to a base station. In this paper we discuss a wireless sensor network based strain monitoring architecture for aircraft/automobile tires present some initial results, and outline future plans.
... Advanced tire sensor systems are currently under development . Named " intelligent tires, " they are equipped with sensors to monitor strain and temperature, etc., in addition to the air pressure of tires in order to improve automobile safety101112131415161718192021 [22] has been started for the purpose of developing intelligent tires. Tire strain monitoring enables one to know the amount of friction between tires and the road surface, which can then be used for the optimization of automobile tire control systems such as ABS. ...
... The key technology, therefore, for intelligent tire sensors comprises direct measurement, low stiffness, and high elongation . In previous studies15161718, we proposed a strain measurement method for tires using changes in the capacitance of the tire itself. In this method, the capacitance between two adjacent steel wires originally embedded in a tire belt is adopted as a strain sensor. ...
The measurement of strain of tires in-service is effective in improving the reliability of tires and ABS systems. Since conventional strain gages have high stiffness and require lead wires, conventional strain gages are cumbersome for the strain measurement of tires. The present study proposes a novel flexible patch-type strain sensor utilizing electric capacitance change. The sensor is made from flexible polyimide substrates and ultra-flexible epoxy resin, which makes the sensor low in stiffness and high in elongation as a whole structure. The sensor utilizes capacitance changes due to the applied strain, and wireless measurements are conducted using amplitude modulation. The sensor is applied to an automobile tire, and compression tests are performed. The effects of the temperature changes are also measured. The proposed sensor is found to successfully measure the applied strain of the tire wirelessly, and the effects of the temperature changes are minimized using a dummy sensor in a self-temperature compensation circuit.
... Since the sensor is not in contact with the tire rubber, the inconvenience associated with tire replacement is avoided. Without attaching sensors, Matsuzaki et al.78798081 presented a self-sensing method using the tire structure itself as a parallel circuit of a capacitor and resistor as shown inFigure 4. Since the actual tire structure acts as a sensor, no additional sensor is required. Therefore, there is no debonding of the sensor, even during prolonged service, because there is no stiffness difference between the sensor and tire rubber. ...
... This problem also causes the short wireless range. Without magnetic coupling, Matsuzaki et al.7980 proposed a battery-less sensor using frequency filtering by a tire sensor. The method comprises the sensor or tuning circuit, an external transmitter that emits white noise, and an external receiver as shown inFigure 6. ...
This review discusses key technologies of intelligent tires focusing on sensors and wireless data transmission. Intelligent automobile tires, which monitor their pressure, deformation, wheel loading, friction, or tread wear, are expected to improve the reliability of tires and tire control systems. However, in installing sensors in a tire, many problems have to be considered, such as compatibility of the sensors with tire rubber, wireless transmission, and battery installments. As regards sensing, this review discusses indirect methods using existing sensors, such as that for wheel speed, and direct methods, such as surface acoustic wave sensors and piezoelectric sensors. For wireless transmission, passive wireless methods and energy harvesting are also discussed.
... In 1967, Collins [13] implemented an implantable intraocular pressure sensor using miniature spiral inductors and pressure-sensitive capacitors. Passive wireless sensors based on LC resonance have undergone rapid development in the past few decades and have been widely used in industrial (tire-pressure monitoring [14], [15], radiofrequency identification [16]) and medical (ocular-pressure monitoring [17]- [19], bone-healing monitoring [20], physiological monitoring [21]- [25]) applications. LC passive wireless sensors use inductive coupling of coils for energy transfer and data transmission, on the basis of the shift of the resonance frequency, i.e., the detuning changes in the inductive or capacitive elements to be measured (pressure [15], [17]- [19], [26], stress [27], temperature [28], [29], humidity [29], [30], etc.) [7], [31]. ...
The challenge in using fully mechanized caving mining technology for thick coal seam mining is monitoring the mixing ratio of coal gangue during the top coal caving process. In this paper, we propose a passive wireless sensing system based on the second-order parity-time symmetric system operated around the exceptional point for the monitoring of coal gangue mixing, which has an LC resonance structure consisting of a spiral resonant coil and a parallel-plate capacitor at the wireless sensing end of the system. The parallel capacitor was designed as a sampling platform. When different proportions of the coal gangue mixture are placed on it, the capacitance value of the capacitor changes, changing the resonance frequency of the system. Our results indicated that the passive wireless sensing system could clearly distinguish the degree of mixing of the coal and gangue and has a higher sensitivity than the conventional system. The proposed system was compared with a mosquito resonant coil system of the same order, and the results indicated that the spiral resonant coil wireless sensing system has more significant advantages in the enhancement of sensitivity. This passive wireless sensing system provides an accurate method for the automatic identification of coal gangue in the top coal caving process; furthermore, it is inexpensive and highly operable.
... Matsuzaki et al. [290] proposed a wireless strain sensor based on the oscillation circuit method to monitor car tires, where the steel wires were employed as electrodes to measure the changes in tire capacitance. The LC sensor presented in Figure 13.e was developed for realtime pipeline integrity monitoring [281] . ...
Sensing the motion of objects and humans is essential for various applications,
including human-machine interfaces. Over the past few years, motion
sensing has been extensively studied using capacitive strain sensors that can
be utilized for wireless communications. The performance and functionality
of capacitive strain sensors have been improved by achieving high sensitivity,
large-area sensing, ultra-stretchability, and simplicity in design, measurement
methods, and wireless integration. This review article highlights recent
developments in capacitive strain sensors, including their characteristics and
applications. First, the mechanisms and techniques employed to enhance
the sensitivity of capacitive strain sensors are reviewed. Then, the notable
features of this sensing strategy are highlighted, such as its ability to cover a
wide area, properties of the required electronic interface, and sensor implementation
inside a remote measurement system via an oscillating circuit.
Therefore, a global review of the capacitive strain sensor that has been previously
attempted can participate in developing an effective sensing method to
meet the market need.
... Matsuzaki et al. [290] proposed a wireless strain sensor based on the oscillation circuit method to monitor car tires, where the steel wires were employed as electrodes to measure the changes in tire capacitance. The LC sensor presented in Figure 13.e was developed for realtime pipeline integrity monitoring [281] . ...
Sensing the motion of objects and humans is essential for various applications, including human-machine interfaces. Over the past few years, motion sensing has been extensively studied using capacitive strain sensors that can be utilized for wireless communications. The performance and functionality of capacitive strain sensors have been improved by achieving high sensitivity, large-area sensing, ultra-stretchability, and simplicity in design, measurement methods, and wireless integration. This review article highlights recent developments in capacitive strain sensors, including their characteristics and applications. First, the mechanisms and techniques employed to enhance the sensitivity of capacitive strain sensors are reviewed. Then, the notable features of this sensing strategy are highlighted, such as its ability to cover a wide area, properties of the required electronic interface, and sensor implementation inside a remote measurement system via an oscillating circuit. Therefore, a global review of the capacitive strain sensor that has been previously attempted could participate in developing an effective sensing method to meet the market need.
... In addition to traditional polyimide film strain sensors, low stiffness strain sensors have been developed for compatibility with tire rubber [9]. Tire strain sensing has also been proposed using changes in the electrical properties of the tire itself, including impedance between the steel belts [10] and capacitance changes extracted using a wireless oscillator circuit [11]. ...
Polyvinylidene fluoride (PVDF) sensors are attractive for use in tires due to their high sensitivity, fast response time, low cost, and ability to operate without power supplies or signal amplification. Based on sensor design, placement, and signal processing techniques, they may be used to determine tire parameters such as tire revolutions, footprint size, and cornering and traction conditions. PVDF sensors generate a voltage output that is related to the average stress acting on the sensor. For non-uniform distributions of stress over the sensor area, there can be a significant difference between the stress at a point and the average sensor stress calculated from the measured voltage. Understanding the effects of sensor geometry on sensor output is important for designing sensors for specific applications, such as tires. This paper presents analytical and numerical models for PVDF voltage output that are developed from the linear piezoelectric constitutive equations, with the average sensor stress modeled using a convolution of the stress input and the PVDF electrode shape. Parametric studies on rectangular, stepped, and triangular sensor shapes show the effects of sensor geometry on voltage output for PVDF sensors under sinusoidal and tire stress inputs.
... the inductance or capacitance is changed by environmental variations, the LC circuit can act as a LC sensor. Most of the previous LC sensors have been based on the capacitance variations caused by, for example, pressure [1, 4–9], strain [10] [11], humidity [1, 5, 12–14], temperature [1] [12] [15], pH [16], bacteria [17] or specific gases [18]. Only a few designs have utilized the effect from inductance changes, including gap change between two planar inductors [19], a magnetoelastic material [20], cross-sectional area change [21], or position change of a ferrite mass in the inductor [22]. ...
This paper presents a LC strain sensor with a novel encapsulated serpentine helical inductor. The helical coil of the inductor is formed by serpentine wire to reduce the radial rigidity. Also the inductor is encapsulated by material with high Poisson's ratio. When an axial deformation is applied to this encapsulated inductor, the cross-sectional area of the helical coil will have more evident change due to lower radial rigidity and encapsulation. Therefore, the variation of inductance or LC resonant frequency can be enhanced to provide better sensitivity of the LC strain sensor. By using PDMS as encapsulated material, it is shown that the sensitivity of the conventional helical inductor with or without encapsulation are both about 73.0 kHz/0.01ε, which means that encapsulation on the conventional helical inductor does not help to improve the sensitivity due to high radial rigidity of the conventional helical coil. It is also found that the encapsulated serpentine helical inductor has better sensitivity (121.9 kHz/0.01ε) than the serpentine helical inductor without encapsulation (62.7 kHz/0.01ε), which verifies the sensitivity enhancing capability of the proposed encapsulated serpentine helical inductor design. The error between simulation and measurement results on sensitivity of LC strain sensor with the encapsulated serpentine inductor is about 5.57%, which verifies the accuracy of the simulation model. The wireless sensing capability is also successfully demonstrated.
... The in-plane strain and out-of-plane displacement are calculated using image processing with an image of the interior surface of a tire that is taken with a single CCD camera fixed on the wheel rim. We have also developed a battery-less wireless communication system (10,16,17) . However, a practical model of strain used for improved tire safety has not yet been presented and is urgently needed. ...
From a traffic safety point of view, there is an urgent need for intelligent tires which can optimize braking control by estimating the slip ratio and friction coefficient between road surface and tire. In previous studies, we have proposed an application of strain data for estimating a friction coefficient. However, it only investigated the condition when the vertical or frictional loads changed but the other load remained constant. Since both of the frictional and vertical loads alter the measured strain data, an independent applied load estimation method is needed. This study develops a concurrent method for estimating the frictional and vertical loads applied to the tires from the measured strain data when both loads change. The method decomposes the measured circumferential strain to the frictional and vertical strain components using their symmetrical and anti-symmetrical characteristics. FEM analysis is used for simulating tire deformation under various wheel loads and braking torques and the relationship between the strain distribution at the sensing point and the applied loads are calculated. When the estimated and true applied loads were compared, it was confirmed that the vertical and frictional loads can be estimated independently from the circumferential strain with sufficient accuracy. Using this method, one can represent the slip slope curve during driving, which enables the optimization of vehicle control and implementation of a road condition warning system.
... A sidewall torsion sensor [4] measured the magnetic field generated by the magnetic tire sidewall markings. Another approach which does not actually need a sensor on the tire itself was introduced in [5]. It was proposed that tire deformation changes the capacitance of the tire, which can be used to monitor tire strain. ...
Tire sensors are powerful tools to study tire behavior and to evaluate the tire operating state. A laser tire sensor (LTS) is introduced in this paper. It is based on a laser triangulation sensor, which can measure the carcass deflections of a rolling tire. The sensor principle is explained and a special tire sensor module is introduced. The results are shown for several wheel loads and inflation pressures, which have linear influence on both the tire radius mean value and radius amplitude. Results from more complex driving situations are also covered, including soil deformation and aquaplaning. It was possible to observe tire penetration into the soft soil. An aquaplaning study shows significant influence of hydrodynamics forces on tire carcass behavior. Also the influence of inflation pressure on aquaplaning is shown.
... We can for the discussion here assume that the wheel angular speed ω i (t) is available in continuous time for each wheel i. The wheels can also be equipped with additional sensors for strain measurements [44] or tire pressure [14], for instance. ...
The amount of software in general and safety systems in particular increases rapidly in the automotive industry. The trend is that functionality is decentralized, so new safety functions are distributed to common shared computer hardware, sensors and actuators using central data buses. This paper overviews recent and future safety systems, and high-lights the big challenges for researchers in the signal processing area
... Capacitance sensors allow for a range of different designs to be easily produced, making them suitable for use in investigating the characteristics of tire rubber. In addition, wireless measurement, which is crucial for the development of intelligent tires, can be easily achieved with the use of capacitance sensors [14] [15] [17] [18]. ...
From a traffic safety point-of-view, there is an urgent need for intelligent tires equipped with strain sensors as a warning system for road conditions and for optimized braking control on poor road surfaces. However, since a conventional foil strain gage has high stiffness, it causes the analyzed region to behave unnaturally. The present study proposes a novel rubber-based strain sensor fabricated using photolithography. The rubber base has the same mechanical properties as the tire surface; thereby the sensor does not interfere with the tire deformation and can accurately monitor the behavior of the tire. This investigation details the design and manufacture of the rubber-based sensor. For verification, the sensor was attached to a beam specimen and found to have a fatigue life of over 106 and a measurable strain range up to 14%. The sensor was applied to a commercially available automobile tire and found to successfully measure the strain of the tire.
... In the previous study [15] [16] [17] [18] [19] [20], we have demonstrated dynamic strain monitoring of tires using a change in capacitance of a tire itself. The proposed sensor module using tuning circuit is passive type and does not need any power supply [20]. ...
To improve reliability of automobile tires and anti-lock braking system (ABS), intelligent tires that measure strain of tires are increasingly demanded. The high stiffness of an embedded sensor like a strain gage, however, causes debonding of a sensor from tire rubber. In a previous study, the authors proposed a wireless strain monitoring method that adopts a rectangular tire specimen as a sensor with a tuning circuit. Compared to the tire specimen, an actual tire has a large hysteresis between the measured strain of the inner tire surface and the capacitance in a tire belt. The large hysteresis in the actual tire makes it difficult to measure a tire strain precisely. In the present study, to measure the strain precisely, multiple power spectrum features of the sensor output are used to estimate the strain with a statistical method. As the spectral features, a peak power spectrum and a sharpness of the resonance in addition to a tuning frequency are used for the estimating. As a result the experiments demonstrate that the method is effective for the passive wireless strain monitoring of actual radial tires.
... Many other passive wireless sensors were developed. Other examples of passive wireless sensor applications include monitoring strain, temperature, stress, corrosion, and humidity [3][4][5]. ...
Passive wireless sensors have been studied by many groups as means of sensing chemical and physical properties in inaccessible locations without the need to include a power source at the sensor location. Indium tin oxide (ITO) thin films are attractive for gas sensing. In this work, we show that laser scribing can be effectively used to fabricate an antenna structure from ITO thin films. This structure is suitable for a wireless chemical sensor.
In this paper, a novel application of a soft sensor via Neural Networks is proposed. One of the most critical issues in the car is the area where the tires are in contact with the ground, these are the only points of contact between the vehicle and the road. The importance lies in the fact that keeping the tire contact patch within the operational parameters ensures the safety, comfort and maneuverability of the vehicle. There are some techniques to measure the tire contact patch, but the operating conditions of the car make impossible the implementation; so in this work the tire contact patch is obtained by the frustrated total internal reflection phenomenon and with the measures of 12 sensors in the car, a Neural Network is trained and tested. Thus, a soft sensor that accurately estimates this variable is the main contribution of this work.
Inductor-capacitor (LC) passive wireless sensors use a transformer with loose coupling between an external readout coil and an inductor that receives power through this inductive coupling. Changes in the sensor are wirelessly and remotely detected by the readout coil, which makes them highly useful in applications that require the sensor to be powered remotely and to occupy a small volume, such as harsh and sealed environments, where physical access to the sensor is difficult. Although the sensor to accomplish this function dates from the 1960's, its rapid extension over the past decades has benefited from microelectromechanical systems. This paper provides an overview of the status and challenges in the $LC$ passive wireless sensor toward a wireless sensing platform. The basic sensing principles are first categorized into detecting changes of the sensor in response to the capacitance, resistance, inductance, or coupling distance due to the parameter of interest through monitoring the impedance magnitude and phase spectrum. The present state of the art in sensor applications for pressure, strain, temperature, humidity, biochemical, gas, and so on is then reviewed and compared. For emerging applications from many Internet of Things scenarios, geometrical constraints, such as small and non-invasive coils, reduce the magnetic coupling between the sensor and the readout coil, resulting in a limited interrogation distance. Furthermore, an increasing number of applications also require the simultaneous measurement of multiple parameters. Recent efforts to increase the interrogation distance and to extend the measurement of single parameter to multiple parameters are finally outlined. [2016-0093]
Tires perform important roles, such as supporting weight and generating forces during accelerating or braking. However, the direct acquisition of valuable data from tires is limited because of the nonlinearity and complex composition of tires. Recently, an intelligent tire system was developed to obtain tire-related variables directly from tire strain. The strain of the tire is measured using a strain sensor; strain is then transformed to other valuable variables, such as the vertical load and the road friction coefficient. However, to develop the conversion logic needed to obtain tire-related variables from the strain, costly and extensive experiments are needed. In this study, we propose a novel tire model and an intelligent tire simulation to reduce the effort and cost for developing an intelligent tire system. Based on experimental data, a tire model, one that can reflect the relationships between driving conditions and tire strain, was derived. And, using a set of polynomial equations comprised of the decisive parameters, a simple algebraic model was developed to yield light computational load. Finally, it was verified that the proposed tire model can correctly estimate not only the tire strain but also the 1st differential values of tire strain.
This paper presents a passive shock recorder to record shock events for tens of Gs with wireless reading and wireless resetting capabilities through the integration of LC circuits and two MEMS devices. With a micro mechanical-latch shock switch electrically connected to the sensing LC circuit, the shock event that leads to different latching states can be recorded and wirelessly read through the LC resonant frequency. With a micro electro-thermal actuator electrically connected to a wirelessly powered actuating LC circuit, the energy can be wirelessly sent to the micro actuator to provide the necessary unlatched force. By integrating the mechanical-latch shock switch and actuator with LC circuits, the latching state can be reset through the wireless actuation. Therefore, the shock recorder can be used repeatedly. Here, the mechanical-latch shock switch is designed to have a two-level shock recording capability. The fabrication of the shock switch and actuator are achieved by a Ni-based surface micromachining process. When the acceleration reaches 28.06 G, the latching state changes from the original state to the first latching state. The resonant frequency of sensing for the LC circuit is found to switch from 10.14 MHz to 9.16 MHz, correspondingly. By further applying acceleration up to 37.10 G, the latching state changes from the first latching state to the second state, and the resonant frequency shifts to 7.83 MHz. Then, with a current of 2.07 AAC wirelessly induced in the actuating LC circuit, the micro electro-thermal actuator is shown to provide sufficient displacement to reset the shock switch from a latched state back to the original unlatched state, and the resonant frequency is switched back to 10.14 MHz. The fabricated shock recorder is repeatedly tested five times. The wireless reading, resetting and shock recording capabilities are successfully verified.
From a traffic safety point-of-view, there is an urgent need for intelligent tires as a warning system for road conditions, for optimized braking control on poor road surfaces and as a tire fault detection system. Intelligent tires, equipped with sensors for monitoring applied strain, are effective in improving reliability and control systems such as anti-lock braking systems (ABSs). In previous studies, we developed a direct tire deformation or strain measurement system with sufficiently low stiffness and high elongation for practical use, and a wireless communication system between tires and vehicle that operates without a battery. The present study investigates the application of strain data for an optimized braking control and road condition warning system. The relationships between strain sensor outputs and tire mechanical parameters, including braking torque, effective radius and contact patch length, are calculated using finite element analysis. Finally, we suggested the possibility of optimized braking control and road condition warning systems. Optimized braking control can be achieved by keeping the slip ratio constant. The road condition warning would be actuated if the recorded friction coefficient at a certain slip ratio is lower than a 'safe' reference value.
Intelligent tires, equipped with sensors for monitoring applied strain, are effective in improving reliability and control systems such as anti-lock braking systems (ABSs). However, since a conventional foil strain gage has high stiffness, it causes the analyzed region to behave unnaturally. The present study proposes a novel rubber-based strain sensor fabricated using photolithography. The rubber base has the same mechanical properties as the tire surface; thereby the sensor does not interfere with the tire deformation and can accurately monitor the behavior of the tire. We also investigate the application of strain data for an optimized braking control and road condition warning system. Finally, we suggested the possibility of optimized braking control and road condition warning systems. Optimized braking control can be achieved by keeping the slip ratio constant. The road condition warning would be actuated if the recorded friction coefficient at a certain slip ratio is lower than a 'safe' reference value.
Structural Health Monitoring (SHM) of automobile tires has been an active area of research in the last few years. Within this area, the monitoring of strain on tires using wireless devices and networks is gaining prominence because these techniques do not require any wired connections. Various tire manufacturers are looking into SHM of automobile tires due to the Transportation Recall Enhancement, Accountability and Documentation (TREAD) act which demands installation of tire pressure monitoring devices within the tire. Besides measuring tire pressures, tire manufactures are also examining ways to measure strain and temperature as well to enhance overall safety of an automobile. In other words, tire manufacturers are looking to develop a sensor system that can monitor the health of an automobile tire. A sensor system that can measure the overall strain of a tire is known as a centralized strain sensing system. However, a centralized strain sensing system cannot find the location and severity of the damage on the tire, which is a basic requirement. Various sensors such as acceleration and optical sensors have also been proposed to be used together to get more local damage information on the tire but a tire equipped with multiple sensors is neither practical nor cost effective. In this thesis we have developed a strain sensing system that performs accurate
An account of a tire pressure monitoring system for motorcycles was presented. The pressure monitoring system was capable of alerting the driver to the quick loss of air pressure inside the tires. Thus it proved to be a fuel efficient measure by placing a check on the under-inflated tire.
We measured the resonant frequency of a mechanical harmonic oscillator without external excitation, by measuring its thermal motion. Making use of the maximum-entropy method, we could determine the resonant frequency of the oscillator (about 450 Hz) from the stochastic time-series data of 8.192-s length with a standard uncertainty of 0.014 Hz, while its Fourier limit (inverse of the measurement time) was about 0.12 Hz. The feasibility to apply this method to a force-probe microscope is discussed.
This paper presents the experimental results of wireless passive IDT strain microsensors, which consist of inter-digital transducers (IDTs) on piezoelectric wafers to transmit and receive surface acoustic waves. By connecting the IDTs to a small microwave antenna, the IDT microsensors are wirelessly readable by a microwave reading system. The sensors are calibrated on a static cantilever beam and used to measure the dynamic strain of a vibrating beam wirelessly. The calibrated sensitivity compares reasonably with the theoretical estimation. The feasibility of compensating for temperature variations and reading multiple sensors simultaneously and the ability to combine the sensor and the wireless recognition systems are discussed.
Strain monitoring of tires in-service of automobiles is quite effective for improving reliability of tires and an anti-lock braking system (ABS). A previous study by the authors presented a new wireless strain monitoring method that adopts the tire itself as a sensor with an oscillator circuit. This method is simple and useful, but it requires a battery to activate the oscillator circuit. The present study proposes and investigates a new passive wireless strain measurement system using capacitance change of tires. The system consists of external antennas and strain sensor with an inductance-capacitance (LC) resonant circuit. This wireless system uses electromagnetic coupling between two inductors of the antenna and the sensor. This method allows use of a part of an actual tire as a capacitor of the LC circuit. Tire deformation changes the sensor's resonant frequency. This resonant frequency change is measured as a change in the phase angle of the antenna using electromagnetic induction. Tensile tests are performed and the antenna phase angles are measured during the tests. Consequently, experiments show that this method is effective for passive wireless strain monitoring of tires.
In recent years the automobile industry has been adopting ever-higher safety standards. Under this light, the development of a tyre pressure monitoring system that aims to overcome the difficulties faced by the already present systems becomes even more important. In order to meet that specific need, a system which is capable of relaying the status of tyre pressure from a sensor at the wheel to a display unit in the vehicle cab was constructed. This new system employs the CAN bus network technique, as well as a novel method of relaying the tyre pressure status off the wheel without using any power or transmitter system, thus overcoming many of the obstacles faced by systems of the same scope. The purpose of this paper is to give an account of the in-field trials performed in order to assess the behaviour of the system in a ‘real world’ environment.
A method for using windowing on a current signal is presented as a means of obtaining amplitude and phase information from electrochemical data transformed from the time domain into the frequency domain. A test method also has been developed to check the reliability of the peak-heights extracted from the data. The limitations have been assessed from both simulations and real experimental data. Additionally, an efficient method for removal of the dc-component in a power-spectrum is presented.
When processing a signal or image using the discrete Fourier transform (DFT), a typical approach is to extract a portion of the signal by windowing and then form the DFT of the window contents. By shifting the window point by point over the signal, the entire signal may be processed. The algorithms developed in this paper “update” the DFT to reflect the modified window contents, using less computation than directly evaluating the modified transform via the FFT algorithm. This reduces the computational order by a factor of log 2 N for both the 1-D and 2-D cases. Algorithms are derived for use with the boxcar, split triangular, Hanning, Hamming and Blackman windows, and implementations in the C language are given. The approach generalizes to piecewise linear and piecewise polynomial windows.
This work reports on integrated highly sensitive InAs/GaSb 3D position sensors for the detection of tire tread deformation. The use of the InAs/GaSb heterostructures provides higher electron mobilities (26,000 cm2/V); this results in increased voltage related Hall sensitivities (0.6 T−1 ) for 5 V bias voltage. Reduced power consumption of such sensors makes them attractive for their implementation within battery-operated measurement systems.
In-service strain monitoring of automobile tires is quite effective to improve reliability of tires and design tools. Conventional strain gages have high stiffness and require lead wires. For those reasons, they are cumbersome for strain measurement of tires. Therefore, a new low cost wireless sensor is required for tires. The present study proposes and experimentally investigates a new wireless strain measurement system using the electric capacitance change of steel-wire reinforced tires. A small CR oscillating circuit is embedded in the tire. Thereby, tire deformation engenders a capacitance change of the tire, which comprises steel wire and rubber. In turn, these changes in capacitance alter the oscillating frequency of the oscillating circuit. Measurement of the oscillating circuit frequency indicates the tire strain wirelessly. A rectangular specimen cut from a truck tire is adopted as a specimen for this study. Finally, feasibility of the proposed system is examined using a commercially available passenger car tire through performing static compression and a dynamic rotation test. Experimental results prove that the method is effective for wireless strain monitoring of tires.
This paper deals with an estimation method of parameter variations of dynamic systems based on the disturbance observer. The disturbance observer is designed to estimate the parameter variations as disturbances. The simple least squares method can extract the parameter variations from the estimated disturbances which include external disturbances and noise. The proposed method is applied to the tyre pressure diagnosis system which can detect underinflated tyres in every situation such as a puncture and natural leaks using wheel speed sensors already provided for anti-lock brake system. Several experimental results are shown to confirm the effectiveness of the method.
This paper investigates the problem of tire burst, and how to mitigate its adverse effects in an AHS environment. The problem is approached by first modeling the tire burst. A feed-forward controller is designed, based on inverting the nonlinear tire-burst dynamics for controlling the car after the tire burst. The feed-forward term is approximated by the output of a second-order filter. The approximation also provides a way to characterize the feed-forward term for different road curvature and different tires (front/rear, left/right). Two different tire blow-out detection algorithms are discussed. This is followed by the experimental phase. Open-loop experiments were conducted to verify the tire-burst model. Closed-loop tests were then carried out to validate the automatic lane-following performance after a tire burst. The results have shown that the burst controller enables the car to follow the lane, even after a front tire blow-out.
The authors propose and have realised, highly sensitive 2DEG Hall
crosses for the measurement of tyre tread deformation in automotive
research. Monolithically integrated three-dimensional position sensors
with a sensitivity of S<sub>1</sub>=699 V/AT have been fabricated and
used for the measurement and analysis of tyre parameters. A complete
telemetry system for the wireless transmission of sensor signals has
been realised. The passive transponder concept is discussed
Micromechanical in-plane strain sensors were fabricated and
embedded in fiber-reinforced laminated composite plates. Three different
strain sensor designs were evaluated: a piezoresistive filament
fabricated directly on the wafer; a rectangular cantilever beam; and a
curved cantilever beam. The cantilever beam designs were off surface
structures, attached to the wafer at the root of the beam. The composite
plate with embedded sensor was loaded in uniaxial tension and bending.
Sensor designs were compared for repeatability, sensitivity and
reliability. The effects of wafer geometry and composite plate stiffness
were also studied. Typical sensor sensitivity to a uniaxial tensile
strain of 0.001 (1000 με) ranged from 1.2 to 1.5% of the nominal
resistance (dR/R). All sensors responded repeatably to uniaxial tension
loading. However, for compressive bending loads imposed on a
2-3-mm-thick composite plate, sensor response varied significantly for
all sensor designs. This additional sensitivity can be attributed to
local buckling and subsequent out of plane motion in compressive
loading. The curved cantilever design, constructed with a hoop geometry,
showed the least variation in response to compressive bending loads. All
devices survived and yielded repeatable responses to uniaxial tension
loads applied over 10 000 cycles
The term “intelligent tire” describes tires equipped
with sensor systems to monitor thermal and mechanical parameters while
driving. Information about temperature, tire pressure, tread wear, etc.,
is collected and used for car operation and maintenance support. The
contact between tire and road surface is a key parameter when
characterizing the ability to accelerate, decelerate and steer a
vehicle, therefore making contact monitoring important for modern car
control systems. Following numerous previous theoretical works, the
friction coefficient can be measured by evaluating the mechanical strain
in the tire surface contacting the road-utilizing the deformation of the
tread elements. A new monitoring method using passive radio requestable
SAW sensors is presented. The principle, measurement setup and
experimental results are shown
Common sense? The latest in vehicle safety comes courtesy of continental with its potentially life-saving tread deformation sensor Tire Technol
- A Gavine
Gavine A 2001 Common sense? The latest in vehicle safety comes courtesy of continental with its potentially life-saving tread deformation sensor Tire Technol. Int. (September) 32–3
- V V Varadan
- V K Varadan
- X Bao
- S Ramanathan
- D Piscotty
Varadan V V, Varadan V K, Bao X, Ramanathan S and
Piscotty D 1997 Wireless passive IDT strain microsensor
Smart Mater. Struct. 6 745–51