Nikolai K. Moshchuk

Vehicle Rollover Avoidance

This article presented an overview of vehicle rollover testing standard and control development. Government testing procedures are first described. Necessary vehicle state estimation for rollover control is then developed. An energy-based RDI is then investigated. Finally, a control strategy based on state estimation and the RDI is developed and verified in vehicle tests. A 1DOF vehicle model, together with standard inertia sensors for the stability control system, provides state estimation needed for RDI and rollover avoidance control.

Estimation of longitudinal speed robust to road conditions for ground vehicles

ABSTRACT This article seeks to develop a longitudinal vehicle velocity estimator robust to road conditions by employing a tyre model at each corner. Combining the lumped LuGre tyre model and the vehicle kinematics, the tyres internal deflection state is used to gain an accurate estimation. Conventional kinematic-based velocity estimators use acceleration measurements, without correction with the tyre forces. However, this results in inaccurate velocity estimation because of sensor uncertainties which should be handled with another measurement such as tyre forces that depend on unknown road friction. The new Kalman-based observer in this paper addresses this issue by considering tyre nonlinearities with a minimum number of required tyre parameters and the road condition as uncertainty. Longitudinal forces obtained by the unscented Kalman filter on the wheel dynamics is employed as an observation for the Kalman-based velocity estimator at each corner. The stability of the proposed time-varying estimator is investigated and its performance is examined experimentally in several tests and on different road surface frictions. Road experiments and simulation results show the accuracy and robustness of the proposed approach in estimating longitudinal speed for ground vehicles.

Optimal braking and steering control for active safety

The paper summarizes the development of an optimal braking and steering control for collision avoidance maneuver. The goal is to minimize the distance to the target vehicle ahead of the host vehicle subject to vehicle and environment constraints. Comparative study of standalone steering versus braking in a collision avoidance maneuver is given and results are discussed. The collision avoidance steering maneuver is effective only when the forward velocity is above a certain limit dictated by the surface friction coefficient and vehicle/tire characteristics. The algorithms were implemented in Simulink and verified in CarSim. The results indicate that there is an optimal braking and steering control resulting in minimal distance needed for collision avoidance maneuvers.

A comparative study on identification of vehicle inertial parameters

This paper presents a comparative analysis of different analytical methods for identification of vehicle inertial parameters. The effectiveness of four different identification methods namely Recursive Least Squares (RLS), Recursive Kalman Filter (RKF), Gradient, and Extended Kalman Filter (EKF) for estimation of mass, moment of inertia and location of center of gravity of a vehicle is investigated. Requirements, capabilities and drawbacks of each method for real time applications are highlighted based on a comprehensive simulation analysis using CarSim. The Extended Kalman Filter method is shown to be the most reliable method for online identification of vehicle inertial parameters for active vehicle control, vehicle stability, and driver assistant systems.

Integrated vehicle control based on tire force reserve optimization concept

Integrated vehicle control (IVC) (also known as Integrated Chassis Control (ICC)) is a key technology for vehicle active safety. The basic concept of IVC is to allocate chassis actuations coherently to control vehicle dynamics in longitudinal and lateral directions simultaneously. Even when only the four brake inputs are considered, the IVC problem is over-determinant. In other words, it must be solved as an optimization problem. In this paper, the optimization goal is to achieve best “tire force reserve”, defined as the difference between the tire force capacity and the resultant tire force. This optimization formulation achieves uniform utilization of tire forces and thus better robustness against normal force and road roughness disturbances. Simulation results are presented to demonstrate the basic idea of this approach.© 2011 ASME

Path Planning for Collision Avoidance Maneuver

This paper summarizes the development of an optimal path planning algorithm for collision avoidance maneuver. The goal of the optimal path is to minimize distance to the target vehicle ahead of the host vehicle subject to vehicle and environment constraints. Such path constrained by allowable lateral (centripetal) acceleration and lateral acceleration rate (jerk). Two algorithms with and without lateral jerk limitation, are presented.The algorithms were implemented in Simulink and verified in CarSim. The results indicate that the lateral jerk limitation increases time-to-collision threshold and leads to a larger distance to the target required for emergency lane change. Collision avoidance path without lateral jerk limitation minimizes the distance to the target vehicle and is suitable for path tracking control in real-time application; however tracking such a path requires very aggressive control.Copyright

Tire-Force Based Holistic Corner Control

This paper describes an analytical methodology and the related algorithms for controlling the vehicle tire forces. The purpose of the control is to provide the driver with a normal driving feel and keep the vehicle on a target path even under demanding road conditions. All the control variables are calculated in real time by minimizing a weighted cost function of the errors between actual and target CG forces and moments. Such real time optimization is possible due to the availability of analytical solutions for the tire force adjustments. A key ingredient of the approach is the idea of making the weights in the cost function dependent on tire states after the optimal linear solution is obtained. When the tire reserve approaches its upper limit, the corresponding weighted element increases exponentially. As a result, the stability element in the cost function dominates the gradient of the target function regardless of CG force error magnitudes. Once the tire state becomes normal then the CG force error correction becomes the dominant component in the control solutions.Copyright

Robust Estimation and Experimental Evaluation of Longitudinal Friction Forces in Ground Vehicles

A longitudinal force estimation based on wheel dynamics and unscented Kalman filter is proposed in this report to address the difficulties in the conventional tire-based approaches. Although it seems that implementation of a tire model in the estimation procedure should result in more accurate results, especially for non-linear regions, complexities in identifying the tire parameters due to the variation of the road and tire conditions leads to inaccurate results for harsh maneuvers on slippery roads. Moreover, the estimation process requires reliable measurements and this necessitates utilizing dynamic models with feasible measurements. Consequently, wheel dynamics is employed to extend the fidelity of the algorithm. For such a model, wheel speeds as reliable and feasible measurements are available. In this strategy, the complex tire-road interaction can be discarded since the wheel speeds are being observed by wheel sensors and the values of the effective torques are provided by motor drives then the longitudinal forces at each individual corner of the vehicle can be estimated independently. Experimental and simulation results confirm the validity of the algorithm in slippery road conditions as well as normal conditions. The newly developed structure has a strong potential to be integrated with other state estimation, such as longitudinal/lateral velocities and lateral forces.Copyright

Modeling of range sensing and object detection, for vehicle active safety

This paper presents a generic range sensing model and method for object detection in 3D space. Due to the complexity and stochastic nature of the physics involved, modeling the physics of sensor and sensing is often very difficult, if not impossible, in particular under unstructured environments. This paper presents a geometric approach that provides an abstraction on the functions of range sensing and objects detection. This is to enable modeling and simulation of vehicle interactions among one another under traffic and with surrounding environment for research and development, early testing and verification of many active safety, driver-assistance and sensor-guided autonomous driving features and functions.

Modelling of Tire Overturning Moment and Loaded Radius

For evaluation of vehicle handling, subjective assessment is currently almost the only criterion. For the purpose of reducing cycle time and avoiding error of subjective assessment, the close-loop objective evaluation system through computer simulations has become an inevitable choice [Gwanghun, G.I.M. and Yongchul, C.H.O.I., 2001, Role of tire modeling on the design process of a tire and vehicle system. ITEC ASIA 2001, Busan, Korea, September 18–20; Guo, K., Ding, H., Zhang, J., Lu, J. and Wang, R., 2003, Development of longitudinal and lateral driver model for autonomous vehicle control. International Journal of Vehicle Design, 36(1), 50–65]. For this reason, the more accurate models of vehicle, tire and driver are necessary. Since structure and operating conditions of tires are very complicated, many researchers have paid more attention to the modeling of tire properties and varieties of tire model have been done to describe the tire behaviour of longitudinal, lateral forces and aligning moment [Pacejka, H.B., 2002, Tyre and Vehicle Dynamics. Butterworth-Heinemann, an imprint of Elsevier Science, ISBN 0-7506-5141-5]. However, there are few studies for the tire overturning moment (TOM), especially under large slip angle and camber angle. For the simulation of vehicle rollover, the expression accuracy of TOM is rather important. In addition, the difference of the loaded radius of left and right tires yields tire roll angle and that also affects vehicle roll behavior. In this paper, the modeling of TOM and loaded radius are presented first, and then the modeling results are compared with tire test data.