Gurkan Erdogan

Estimation of Tire-Road Friction Coefficient Using a Novel Wireless Piezoelectric Tire Sensor

A tire-road friction coefficient estimation approach is proposed which makes use of the uncoupled lateral deflection profile of the tire carcass measured from inside the tire through the entire contact patch. The unique design of the developed wireless piezoelectric sensor enables the decoupling of the lateral carcass deformations from the radial and tangential deformations. The estimation of the tire-road friction coefficient depends on the estimation of slip angle, lateral tire force, aligning moment, and the use of a brush model. The tire slip angle is estimated as the slope of the lateral deflection curve at the leading edge of the contact patch. The portion of the deflection profile measured in the contact patch is assumed to be a superposition of three types of lateral carcass deformations, namely, shift, yaw, and bend. The force and moment acting on the tire are obtained by using the coefficients of a parabolic function which approximates the deflection profile inside the contact patch and whose terms represent each type of deformation. The estimated force, moment, and slip angle variables are then plugged into the brush model to estimate the tire-road friction coefficient. A specially constructed tire test rig is used to experimentally evaluate the performance of the developed estimation approach and the tire sensor. Experimental results show that the developed sensor can provide good estimation of both slip angle and tire-road friction coefficient.

Tyre-road friction coefficient estimation based on tyre sensors and lateral tyre deflection: modelling, simulations and experiments

The estimation of the tyre–road friction coefficient is fundamental for vehicle control systems. Tyre sensors enable the friction coefficient estimation based on signals extracted directly from tyres. This paper presents a tyre–road friction coefficient estimation algorithm based on tyre lateral deflection obtained from lateral acceleration. The lateral acceleration is measured by wireless three-dimensional accelerometers embedded inside the tyres. The proposed algorithm first determines the contact patch using a radial acceleration profile. Then, the portion of the lateral acceleration profile, only inside the tyre–road contact patch, is used to estimate the friction coefficient through a tyre brush model and a simple tyre model. The proposed strategy accounts for orientation-variation of accelerometer body frame during tyre rotation. The effectiveness and performance of the algorithm are demonstrated through finite element model simulations and experimental tests with small tyre slip angles on different road surface conditions.

A novel wireless piezoelectric tire sensor for the estimation of slip angle

This paper introduces a simple approach for the analysis of tire deformation and proposes a new piezoelectric tire sensor for physically meaningful measurements of tire deformations. Tire deformation measurements in the contact patch can be used for the estimation of slip angle, tire forces, slip ratio and tire–road friction coefficient. The specific case of a wireless tire deformation sensor for the estimation of slip angle is taken up in this paper. A sensor in which lateral sidewall deformation can be decoupled from radial deformation is designed. The slope of the lateral deflection curve in the contact patch is used to calculate slip angle. A specially constructed tire test rig is used to experimentally evaluate the performance of the developed sensor. Results show that the developed sensor can accurately estimate slip angles up to values of 5°.

Friction coefficient measurement for autonomous winter road maintenance

Real-time measurement of tyre–road friction coefficient is extremely valuable for winter road maintenance operations, since knowledge of tyre–road friction coefficient can be used to optimise application of deicing chemicals to the roadway. In this paper, a wheel-based tyre–road friction coefficient measurement system is developed for snowploughs. Unlike a traditional Norse meter, this system is based on measurement of lateral tyre forces, has minimal moving parts and does not use a brake actuator. Hence, it is reliable and inexpensive. A key challenge is quickly detecting changes in the estimated tyre–road friction coefficient while rejecting the high levels of vibratory noise in the measured force signal. Novel filtering and signal processing algorithms are developed to address this challenge, including a biased quadratic mean filter and an accelerometer-based vibration removal filter. Detailed experimental results are presented on the performance of the friction estimation system on different types of road surfaces. It is also shown that disturbances due to lateral and longitudinal vehicle manoeuvres on the estimated friction coefficient can be removed by using accelerometer-based filtering.

Adaptive Vibration Cancellation for Tire-Road Friction Coefficient Estimation on Winter Maintenance Vehicles

This paper focuses on the development and experimental evaluation of a novel adaptive feedforward vibration cancellation based friction estimation system. The friction estimation utilizes a small instrumented redundant wheel on the vehicle. Unlike other systems previously documented in literature, the developed system can provide a continuous measurement of the friction coefficient under all vehicle maneuvers, even when the longitudinal and lateral accelerations are both zero. A key challenge in the development of the estimation system is the need to remove the influence of vibrations and the influence of vehicle maneuvers from the measured signal of a force sensor. An adaptive feedforward algorithm based on the use of accelerometer signals as reference inputs is developed. The parameters of the feedforward model estimated by the adaptive algorithm themselves serve to determine the value of the friction coefficient. At the same time, the influence of vibrations and of vehicle maneuvers is removed. Detailed experimental results are presented on a skid pad wherein the road surface changes from dry asphalt to ice. Results are presented at different speeds and with and without lateral and longitudinal maneuvers. Excellent performance is obtained in estimation of the friction coefficient. The performance of the adaptive feedforward algorithm is shown to be significantly superior to that of a simple cross-correlation based algorithm for friction estimation.

Development of a New Lateral Stability Control System Enhanced With Accelerometer Based Tire Sensors

Vehicles are usually equipped with driver assistance systems such as anti-lock brake, traction control and lateral stability control systems. Although the forces maneuvering a vehicle are generated inside the tire contact patch, state of the art control systems have no feedback directly from the tires. Instead, observers based on indirect measurements are employed to close the control loop. Wireless sensors embedded inside the tires can be used to extract valuable information from the tire deformations such as forces. These forces can be used to develop adaptive stability control systems which update their parameters in real-time depending on the road and vehicle conditions. Furthermore, controllers can selectively regulate tire forces by changing brake/drive torques at each tire. This paper examines the integration of accelerometer based tire sensors with lateral stability control system (ESP). Its aim is to present the main components of a smart-tire enabled ESP and a preliminary study on potential performance improvements.Copyright

Closed-loop snowplow applicator control using road condition measurements

Closed-loop control of a snowplow applicator, based on direct measurement of the road surface condition, is a valuable technology for the optimisation of winter road maintenance costs and for the protection of the environment from the negative impacts of excessive usage of de-icing chemicals. To this end, a novel friction measurement wheel is designed to provide a continuous measurement of road friction coefficient, which is, in turn, utilised to control the applicator automatically on a snowplow. It is desired that the automated snowplow applicator deploy de-icing materials right from the beginning of any slippery surface detected by the friction wheel, meaning that no portion of the slippery road surface should be left untreated behind, as the snowplow travels over it at a reasonably high speed. This paper describes the developed wheel-based measurement system, the friction estimation algorithm and the expected performance of the closed-loop applicator system. Conventional and zero velocity applicators are introduced and their hardware time delays are measured in addition to the time delay of the friction estimation algorithm. The overall performance of the closed-loop applicator control system is shown to be reliable at typical snowplowing speeds if the zero velocity applicator is used.

Measurement of Uncoupled Lateral Carcass Deflections With a Wireless Piezoelectric Sensor and Estimation of Tire Road Friction Coefficient

A new tire-road friction coefficient estimation approach based on lateral carcass deflection measurements is proposed. The unique design of the developed wireless piezoelectric sensor decouples lateral carcass deformations from radial and tangential carcass deformations. The estimation of the tire-road friction coefficient depends on the estimation of the slip angle and the lateral tire force. The tire slip angle is estimated as the slope of the lateral deflection curve at the leading edge of the contact patch. The lateral tire force is obtained by using a parabolic relationship with the lateral deflections in the contact patch. The estimated slip angle and lateral force are then plugged into a tire brush model to estimate the tire-road friction coefficient. A specially constructed tire test-rig is used to experimentally evaluate the performance of the tire sensor and the developed approach. Experimental results show that the proposed tire-road friction coefficient estimation approach is quite promising.Copyright

Friction coefficient measurement system for winter maintenance vehicles

Real-time measurement of tire-road friction coefficient is extremely valuable for winter road maintenance operations. In winter maintenance, knowledge of tire-road friction coefficient can be used to optimize application of deicing and anti-icing chemicals to the roadway. In this paper, a wheel based tire-road friction coefficient measurement system is developed for snowplows. Unlike a traditional Norse meter, this system is based on measurement of lateral tire forces, has minimal moving parts and does not use any actuators. Hence, it is reliable and inexpensive. A key challenge is quickly detecting changes in estimated tire-road friction coefficient while rejecting the high levels of noise in measured force signals. Novel filtering and signal processing algorithms are developed to address this challenge including a biased quadratic mean filter and an accelerometer based vibration removal filter. Detailed experimental results are presented on the performance of the friction estimation system on different types of road surfaces. Experimental results show that the biased quadratic mean filter works very effectively to eliminate the influence of noise and quickly estimate changes in friction coefficient. Further, the use of accelerometers and an intelligent algorithm enables elimination of the influence of driver steering maneuvers, thus providing a robust friction measurement system under all operating conditions.

Wireless Piezoelectric Sensor for the Measurement of Tire Deformations and the Estimation of Slip Angle

This paper introduces a wireless piezoelectric tire sensor whose readings can be utilized for the estimation of various tire variables such as slip angle, slip ratio, tire forces and tire road friction coefficient. In this paper, the proposed sensor is demonstrated for the estimation of tire slip angle. Lateral deformation of the tire is decoupled from radial and longitudinal tire deformations using a special sensor design. The decoupled lateral deflection profile of the tire is employed to estimate the slip angle. A new tire test rig is constructed to experimentally evaluate the performance of the developed sensor. Results show that the tire sensor can accurately estimate slip angles up to values of 5.0 degrees.Copyright