An Adaptive Tire Model for Enhanced Vehicle Control Systems

Advanced vehicle dynamics control systems, such as integrated chassis control systems, are generally designed in a two layers structure: a tire force determination layer, and a tire force generation layer. The tire force generation layer works as a servo function that follows the force commands from the force determination layer. Therefore, the tire force generation layer should not require a lot of computing resources. This paper presents an inverse tire model that calculates required slip ratios and slip angles when tire forces are commanded. The inverse tire model is based on a nonlinear tire model that is sufficiently complex and, thus, can capture the nonlinear characteristics of tires. Because mathematical inversion of the nonlinear tire model is challenging, recursive methods can be considered for an inverse model. However, recursive methods, such as Newton Raphson method, do not guarantee the fixed time span required for finishing the computation. This paper presents a method for inverse tire model that does not require recursive computations.

<div class="section abstract"><div class="htmlview paragraph">Accurate parameters of vehicle motion state are very important to the active safety of a vehicle. Currently the extended Kalman filter and unscented Kalman filter are widely used in estimation of the key state parameters, such as speed. In this situation, tire model must be used. The Magic Formula Tire Model is widely used in vehicle dynamics simulation because of its high versatility and accuracy. However, it requires a large number of parameters, which make the key state parameters of a real vehicle difficult to accurately obtain. Therefore, it is limited in real-time control of a vehicle. Firstly, the original Magic Formula Tire Model is simplified in this paper; then Jin Chi's Tire Model is introduced; thirdly, parameters of both the simplified Magic Formula and Jin Chi's Tire Model are identified using PSO (Particle Swarm Optimization) algorithm. Finally, Jin Chi's Tire Model is also used in parameters identification of experimental data.</div></div>

Many vehicle state parameters will be used in the electronic stability control (ESC) system. ESC system must estimate some important parameters based on a few sensors and help to develop the control strategies. ESC can estimate the work state of vehicle with tire forces based on the estimating of adhesion coefficient and wheel slip ratio, then determine the control strategy on wheels. The tire forces to be estimated include vertical force, lateral force and longitudinal force on tires. In this article, a method of estimating vertical tire force based on vehicle geometric parameters and vehicle working state, a method of estimating tire lateral force based on vehicle yaw rate and the change of tire longitudinal forces caused by the change of vertical forces and lateral forces have researched. Co-simulation shows that the trend of the tire forces changing is correct and small error on high and low adhesive pavement. The ESC system is available on HIL bench and testing vehicle, so the estimates of tire forces are practical methods.

<div class="htmlview paragraph">In February of 1987, Dresser introduced a pair of new mechanical drive, off-highway trucks designed to operate in the 35 to 60 ton, rear-dump, classes. These trucks, designated 140M and 210M, replaced three previous models while covering the same payload range. One distinctive feature of these new vehicles was their hydraulic system and in particular the brake control portion of this system.</div> <div class="htmlview paragraph">This new hydraulic brake control system can be described as a closed-center arrangement using a pressure-compensated, variable displacement pump as an energy source with accumulator-based energy reserves for independent and redundant circuits. In the basic version, a pair of pressure regulating valves are used to control system pressure at the brakes. These valves can be actuated in</div> <div class="htmlview paragraph"> <figure id="F1" class="figure"> <div class="graphic-wrapper"><img class="article-figure figure" src="911834_fig0001.jpg" alt="No Caption Available"/></div> </figure> </div> <div class="htmlview paragraph">tandem by a treadle (foot pedal) or separately by hydraulic pilot pressure. A single, filtered hydraulic fluid is used throughout the system and is stored in a single reservoir vented to atmosphere.</div> <div class="htmlview paragraph">The basic system is capable of accommodating multiple-axle (i.e. more than two) arrangements but was originally applied to a two-axle vehicle using dry, disc-type (caliper and rotor) brakes on all wheels. In February of 1990, the Model 140M and 210M trucks were revised to offer rear axle oil-cooled brakes as an option. The brake control system was subsequently modified to provide for this change primarily by the use of an additional pressure regulating valve and redundant circuitry.</div> <div class="htmlview paragraph">Both the original and latest versions of this system are characterized by their use of a unique emergency brake control system. Through the use of logic-type control valves, a loss of hydraulic pressure in one circuit is used to force the remaining high pressure circuits into actuating the brakes. This paper will describe the arrangement and operation of this hydraulic brake control system and its function as an integral part of the overall vehicle hydraulic system.</div>

<div class="section abstract"><div class="htmlview paragraph">A digital twin is a digital representation of a real physical system, product, or process that functions as its practically identical digital counterpart for tasks such as testing, integration, monitoring, and maintenance. Creating digital twins allows the ‘digital system’ or ‘digital product’ to be tested at faster-than-real-time which improves overall program efficiency and shortens the programme duration.</div><div class="htmlview paragraph">The HORIBA Intelligent Lab virtual engineering toolset was used to generate an Empirical Digital Twin (EDT) of a contemporary off-highway diesel Internal Combustion Engine (ICE) from physical testing, accounting for the effects of altitude and combustion air temperature. The EDT was subsequently used to predict engine performance and emissions for several synthetic off-highway machine cycles at sea-level and 3000m altitude. The synthetic agricultural cycles which included ploughing, seeding, spraying, fertilising, and roading were generated using a machine simulation programme created by Soluzioni Ingegneria and IPG Automotive. This combined physical testing and simulation approach to off-highway machine development and calibration is expected to support Original Equipment Manufacturers (OEMs) with In Service Monitoring (ISM) within the Stage V emissions period and supplement powertrain development for future emissions standards.</div><div class="htmlview paragraph">The off-highway simulations were conducted using semi-empirical Magic Formula (MF) tyre models which accounted for the tyre-soil elastoplastic working relationship. These models incorporated the coefficients of longitudinal traction and forward resistance on plastic soil and were developed from ASAE standards and extensive field testing with instrumented vehicles. This new off-highway simulation platform developed by Soluzioni Ingegneria and IPG Automotive allows the generation of complex off-highway scenarios which can be used to estimate loading of machine components such as hydraulics, pneumatics, and accessories and right-sizing of powertrains for given machine applications.</div></div>

<div class="section abstract"> <div class="htmlview paragraph">This Recommended Practice provides a taxonomy for motor vehicle <i>driving automation systems</i> that perform part or all of the <i>dynamic driving task</i> (<i>DDT</i>) on a <i>sustained</i> basis and that range in level from <i>no driving automation</i> (level 0) to <i>full driving automation</i> (level 5). It provides detailed definitions for these six levels of <i>driving automation</i> in the context of <i>motor vehicles</i> (hereafter also referred to as “<i>vehicle</i>” or “<i>vehicles</i>”) and their <i>operation</i> on roadways. These level definitions, along with additional supporting terms and definitions provided herein, can be used to describe the full range of <i>driving automation features</i> equipped on <i>motor vehicles</i> in a functionally consistent and coherent manner. “On-road” refers to publicly accessible roadways (including parking areas and private campuses that permit public access) that collectively serve users of <i>vehicles</i> of all classes and <i>driving automation</i> levels (including no <i>driving automation</i>), as well as motorcyclists, pedal cyclists, and pedestrians.</div> <div class="htmlview paragraph">The levels apply to the <i>driving automation feature(s)</i> that are engaged in any given instance of on-road <i>operation</i> of an equipped <i>vehicle</i>. As such, although a given <i>vehicle</i> may be equipped with a <i>driving automation system</i> that is capable of delivering multiple <i>driving automation features</i> that perform at different levels, the level of <i>driving automation</i> exhibited in any given instance is determined by the <i>feature(s)</i> that are engaged.</div> <div class="htmlview paragraph">This document also refers to three primary actors in <i>driving</i>: the (human) <i>driver</i>, the <i>driving automation system</i>, and other <i>vehicle</i> systems and components. These other <i>vehicle</i> systems (or the <i>vehicle</i> in general terms) do not include the <i>driving automation system</i> in this model, even though as a practical matter a <i>driving automation system</i> may actually share hardware and software components with other <i>vehicle</i> systems, such as a processing module(s) or operating code.</div> <div class="htmlview paragraph">The levels of <i>driving automation</i> are defined by reference to the specific role played by each of the three primary actors in performance of the <i>DDT</i>. “Role” in this context refers to the expected role of a given primary actor, based on the design of the <i>driving automation system</i> in question and not necessarily to the actual performance of a given primary actor. For example, a <i>driver</i> who fails to <i>monitor</i> the roadway during engagement of a level 1 adaptive cruise control (ACC) system still has the role of <i>driver</i>, even while s/he is neglecting it.</div> <div class="htmlview paragraph"><i>Active safety systems</i>, such as electronic stability control and automated emergency braking, and certain types of driver assistance systems, such as lane keeping assistance, are excluded from the scope of this <i>driving automation</i> taxonomy because they do not perform part or all of the <i>DDT</i> on a <i>sustained</i> basis and, rather, merely provide momentary intervention during potentially hazardous situations. Due to the momentary nature of the actions of <i>active safety systems</i>, their intervention does not change or eliminate the role of the <i>driver</i> in performing part or all of the <i>DDT,</i> and thus are not considered to be <i>driving automation</i>.</div> <div class="htmlview paragraph">It should, however, be noted that crash avoidance features, including intervention-type <i>active safety systems</i>, may be included in <i>vehicles</i> equipped with <i>driving automation systems</i> at any level. For <i>ADS</i>-equipped <i>vehicles</i> (i.e., levels 3-5) that perform the complete <i>DDT</i>, crash avoidance capability is part of <i>ADS</i> functionality.</div></div>

<div class="htmlview paragraph">The Columbus laboratory module, developed by Astrium Bremen as prime contractor and Alenia Spazio as co-prime, is the European contribution to the International Space Station (ISS) program and as such it will support, once in orbit, micro-gravity and space based research activities of the member states.</div> <div class="htmlview paragraph">Columbus Environmental Control System (ECS) employs an Environmental Control and Life Support System (ECLSS) providing atmosphere pressure, cabin ventilation and temperature humidity control inside the module in conjunction with an autonomous Active Thermal Control System (ATCS) that provides the heat collection capability. The ATCS, based on software controlled water loop, provides also the cooling capability for Payloads and Subsystem equipment. The ECS is completed with the Passive Thermal Control System based on software controlled shell heating system plus passive fixtures such as Multi-Layers Insulation (MLI) blankets.</div> <div class="htmlview paragraph">Generally, both, the Columbus ATCS as well as the ECLSS are qualified via simplified but representative tests and concluding analyses. Complete verification of the module thermal and environmental control design however, will be performed via analysis supported by ECS System Level Integrated Test as well as the predictions for flight.</div> <div class="htmlview paragraph">With respect to responsibility sharing, Alenia is responsible for all verification by test related to thermal/environmental aspects, i.e. Alenia will define the test requirements and cases to be performed via the establishment of a dedicated test specification. On the other side, definition and production of the test set-up as well as the performance of the test is assigned to the Columbus prime Astrium SI Bremen.</div> <div class="htmlview paragraph">In order to get confidence on the functional performance of the Columbus ECS and to validate the Integrated Overall Thermal Mathematical Model (IOTMM) on system level the module will be subjected to an Integrated System Test (IST).</div> <div class="htmlview paragraph">Purpose of the ECS IST is to provide the first verification of the thermal/environmental interrelation between the active cooling (ATCS) and environmental control system (ECLSS) hardware and software and to collect as much characteristic thermal data as possible for the validation of the flight configuration IOTMM. This test will represent the second and last test in series on the flight configuration of the Columbus module.</div> <div class="htmlview paragraph">Previous tests, for verification of the functional interfaces of the ATCS and ECLSS, have been performed already in the frame of the Electrical Test Model (ETM) utilization. However, this test did not provide information on environmental and thermal parameters of the system but rather on the functional interrelations of the relevant units of the subsystems. Presently, the subject test will be performed in the integration hall of Astrium SI Bremen (Class 100.000 clean room conditions) and the pressurized shell is planned to be covered by the flight multi-layer insulation only located beneath the meteoroid debris panels (MDPS) of the module. However, in order to get as much as possible characteristic data of the system not only the test cases have to be selected very carefully but also additional test supporting equipment (TSE) has to be evaluated.</div> <div class="htmlview paragraph">The present paper summarizes the efforts generated to establish the Environmental/Thermal test in the frame of the system level IST of the Columbus module, describes the interrelation aspects of the thermal/environmental subsystem verification by test and analysis and presents the derived methodologies and expected results.</div>

Longitudinal and lateral forces acting on tyres are known to be closely related to tractive ability, braking characteristics, handling stability and manoeuvrability of ground vehicles. However, it is not feasible in the operating vehicles to measure the tyre forces directly because of the high cost of sensors, the limitations in sensor technology, interference with tyre rotation and the harsh environment. Another approach is the indirect monitoring technique that can estimate the tyre forces based on remote sensor outputs and vehicle dynamics models. In this paper, in order to develop tyre force-monitoring systems, a monitoring model is proposed utilizing not only the yawing motion but also the roll motion. Based on the monitoring model, a monitoring system is designed to estimate the lateral tyre force acting on each tyre. The monitoring system is constructed on the basis of a new scaled Kalman filter with model error compensator (SKFMEC) technique that is developed in this study to improve the robustness performance of Kalman filter methods. The SKFMEC technique adopts both the well-conditioned observer and the model error compensator concepts. Tyre force estimation performance of the monitoring system is evaluated in the MATLAB simulations where true tyre force data are generated from a 14-degree-of-freedom vehicle model with the combined-slip ‘magic formula’ tyre model.

<div class="htmlview paragraph">This paper describes the development process for acceleration sensors used on automobiles and acceleration evaluation system especially for the acceleration in super low range frequency.</div> <div class="htmlview paragraph">Acceleration sensor is indispensable not only for good vehicle motion control system, for example, active suspension control system, antiskid control system and four wheel steering control system, but also for safety system like air bag control system. This work focused on the development process of acceleration sensor which applied piezo ceramics.</div> <div class="htmlview paragraph">Features of newly developed sensor are as follows.</div> <div class="htmlview paragraph"> <ol class="list nostyle"> <li class="list-item"> <span class="li-label">1)</span> <div class="htmlview paragraph">Achievement of self-diagnostic function to detect sensor failure utilizing the characteristics of piezo ceramics</div> </li> <li class="list-item"> <span class="li-label">2)</span> <div class="htmlview paragraph">Addition of piezo ceramic to cancel the pyro-effect achieved stabilization of sensor characteristics and enabled to detect acceleration of 0.0025G in super low range frequency of 0.05Hz.</div> </li> <li class="list-item"> <span class="li-label">3)</span> <div class="htmlview paragraph">Incorporates impedance conversion, filtering and temperature characteristics compensation circuitry.</div> </li> </ol> </div> <div class="htmlview paragraph">Frequency range of acceleration for good vehicle motion control is considered to be from DC to about 50Hz.</div> <div class="htmlview paragraph">But the measurement of acceleration in thus super low range frequency near DC had been difficult because of its mechanical and electrical noise interruption.</div> <div class="htmlview paragraph">This had delayed the development of acceleration sensor for automotive use.</div> <div class="htmlview paragraph">We succeeded in the development of acceleration measurement system for super low range frequency from 0.01Hz to 2Hz with detecting acceleration range from 0.0002 (0.2 gal) G to 1G as well as the development of piezo type acceleration sensor for automotive use.</div>

<div class="htmlview paragraph">Various vehicle dynamic simulation software programs have been developed for use in reconstructing accidents. Typically these are used to analyze and reconstruct preimpact and postimpact vehicle motion. These simulation programs range from proprietary programs to commercially available packages. While the basic theory behind these simulations is Newton's laws of motion, some component modeling techniques differ from one program to another. This is particularly true of the modeling of tire force mechanics. Since tire forces control the vehicle motion predicted by a simulation, the tire mechanics model is a critical feature in simulation use, performance and accuracy. This is particularly true for accident reconstruction applications where vehicle motions can occur over wide ranging kinematic wheel conditions. Therefore a thorough understanding of the nature of tire forces is a necessary aspect of the proper formulation and use of a vehicle dynamics program.</div> <div class="htmlview paragraph">This paper includes a discussion of tire force terminology, tire force mechanics, the measurement and modeling of tire force components and combined tire force models currently used in simulation software for the reconstruction of accidents. The paper discusses the difference between the idealized tire force ellipse and an actual tire friction ellipse. Equations are presented for five tire force models from three different simulation programs. Each model uses a different method for computing tire forces for combined braking and steering. Some experimentally measured light vehicle tire properties are examined.</div> <div class="htmlview paragraph">Some tire force models begin with a specified level of braking force and use the friction ellipse to determine the corresponding steering force; this produces steering forces and a resultant tire force equal in magnitude to full skidding for combined steering and braking. Comparisons are presented of results from simulation programs using different tire models for vehicle motions involving two types of severe yaw. The comparisons in this paper are not of reconstructions where the user seeks initial conditions to match an existing trajectory. The first comparison is a hypothetical postimpact motion with a given initial velocity and initial angular velocity and the other is a sudden steer maneuver. In some cases, the simulations and their tire models predict the vehicle motion closely. In most cases, however, the results differ significantly between simulation programs.</div> <div class="htmlview paragraph">The example simulations presented in this paper are not intended to reflect the way vehicle dynamic simulation programs are used typically in accident reconstruction.</div>

<div class="section abstract"><div class="htmlview paragraph">For modern vehicle development, on-board vehicle Mass and road Gradient Estimation (MGE) can offer great benefit to many sub-systems on the vehicle, such as vehicle control system, transmission control system, and active safety system etc. However, there are still several challenges that need to be solved. Firstly, thanks to good accuracy, reliability, and robustness, regression analysis-based approaches: Recursive Least Squares (RLS) and Kalman Filter (KF) are very popular for MGE, but the trade-off between estimator’s accuracy and converge time is challenging. Furthermore, depending on vehicle and powertrain types, the implementation of MGE function could be very different. It is desired to have a structured approach for various vehicle applications’ MGE development. Lastly, good reliability of MGE does not always satisfy for complicated real-world driving maneuvers and road conditions.</div><div class="htmlview paragraph">This paper introduced a mature MGE development approach which utilizes an innovative Series Kalman Filter (S-KF) structure with a 3-axis accelerometer to address the challenges above, leading to the demonstration on 3 different types of vehicles with different powertrain applications: a truck with Internal Combustion Engine (ICE) and Automated Manual Transmission (AMT) gearbox, a mid-size Plug-in Hybrid Electric Vehicle (PHEV) SUV, and an A-segment Battery Electric Vehicles (BEV) mini car. They are tested under wide range real-world driving maneuvers and road conditions. Moreover, to improve the converge time whilst keeping the same accuracy of MGE, several dedicated designed engineering features are implemented and introduced in this paper. The vehicle-based experimental result and structured development approach showed good performance and maturity of the production oriented MGE, and good efficiency and flexibility to adapt it to various applications.</div></div>

<div class="htmlview paragraph">This paper describes a tire model designed for the full range of operating conditions under both on- and off-road surface conditions. The operating conditions include longitudinal and lateral slip, camber angle and normal load. The model produces tire forces throughout the adhesion range up through peak coefficient of friction, and throughout the saturation region to limit slide coefficient of friction. Beyond the peak coefficient of friction region, the off-road portion of the model simulates plowing of deformable surfaces at large side slip angles which can result in side forces significantly above the normal load (e.g., equivalent coefficients of friction greatly exceeding unity).</div> <div class="htmlview paragraph">The model allows changing the saturation function depending the surface currently encountered by a given tire in the vehicle dynamics model. Saturation functions can vary from the sharp peak function associated with radial tires on paved surfaces, to the exponential like saturation associated with various off-road surfaces. Smooth transition functions are provided between the adhesion and saturation regions, and logic is provided to ensure that tire force always opposes slip velocity no matter what operating condition is encountered.</div> <div class="htmlview paragraph">This paper describes the model functional characteristics and response to a range of operating conditions. Data sources for the model are discussed. Cases are run with a vehicle dynamics model to illustrate model response to changing surface conditions.</div>

<div class="htmlview paragraph">This paper describes the development and validation of an advanced microcomputer based simulation developed to investigate the complex dynamic responses of light vehicles in a variety of maneuvers. These maneuvers include cornering with braking or acceleration as well as vehicle skidding, spinning, and rolling over.</div> <div class="htmlview paragraph">A three-dimensional, non-linear vehicle dynamic model having eight degrees-of-freedom is generated according to user specifications. Multiple masses are connected through suspension elements to properly account for vehicle forward, lateral, vertical, roll, pitch, and yaw directional dynamics. To build an accurate model, any one of 8 different commonly used front suspension systems can be employed in conjunction with any one of 19 different rear independent, semi-independent, and dependent suspension systems. The capability of implementing various suspension systems allows the utilization of important kinematic and dynamic effects of these suspensions on vehicle response. The tire model utilized is based on the non-dimensional slip angle approach and is capable of working over a wide range of normal to extreme operating conditions. These conditions include normal loads of up to 400% of standard load, slip angles from -90 to 90 degrees, slip ratios from -1 to 1, camber angles to 60 degrees, and an unlimited friction regime. The tire forces and moments generated are non-linear functions of actual normal load, longitudinal slip, slip angle, camber angle, and tire-roadway frictional characteristics. The tire model predicts wheel locking, spinning and/or saturation, and automatically simulates the changes in tire behavior caused by these conditions.</div> <div class="htmlview paragraph">The results presented in this paper demonstrate that the Light Vehicle Dynamics Simulation (LVDS) is capable of accurately predicting a wide spectrum of light vehicle maneuvers ranging from low “g” cornering to severe spin out and rollover. The LVDS simulation was successfully validated using experimental results obtained from several vehicles (cars, utility vehicles, vans, and pickup trucks) in a variety of handling and rollover maneuvers and in both unloaded and loaded conditions. It has proven to be a reliable tool for the investigation of the dynamic behavior of light vehicles.</div>

<div class="htmlview paragraph">Automatic headway control is an evolutionary step towards an automatic vehicle guidance and control system. This system expands the capability of the currently available production option-speed control.</div> <div class="htmlview paragraph">This paper describes the system from a theoretical and hardware viewpoint, with emphasis on the control logic. The electronic and electromechanical hardware design based on the theory presented is fully described.</div> <div class="htmlview paragraph">The limitations and advantages of the system are explained, based on test results from actual trial runs on an implemented vehicle.</div> <div class="htmlview paragraph">Capacity and safety benefits are made somewhat tangible by direct comparison with test results obtained on a roadway similar to that for which this system is recommended, under test conditions directly analogous to the operating characteristics of the automatic headway control system.</div>

In order to prevent severity traffic accident on freeway caused by tire blowout, it is necessary to monitor the tire pressure in real time. This paper established a linear model between the force and the slip to estimate the tire radius through least square ,where only ABS wheel speed sensors were used. The result of the simulation about this method is perfect ,it is a effective method for indirect tire pressure monitoring.