Planar Vehicle Research Articles

Reliable Vehicle Pose Estimation Using Vision and a Single-Track Model

This paper examines the problem of estimating vehicle position and direction, i.e., pose, from a single vehicle-mounted camera. A drawback of pose estimation using vision only is that it fails when image information is poor. Consequently, other information sources, e. g., motion models and sensors, may be used to complement vision to improve the estimates. We propose to combine standard in-vehicle sensor data and vehicle motion models with the accuracy of local visual bundle adjustment. This means that pose estimates are optimized with regard not only to observed image features but also to a single-track vehicle model and standard in-vehicle sensors. The described method has been experimentally tested on challenging data sets at both low and high vehicle speeds as well as a data set with moving objects. The vehicle motion model in combination with in-vehicle sensors exhibit good accuracy in estimating planar vehicle motion. Results show that this property is preserved, when combining these information sources with vision. Furthermore, the accuracy obtained from vision-only in direction estimation is improved, primarily in situations in which there are few matched visual features.

Lyapunov and Minimum-Time Path Planning for Drones

In this paper, we study the problem of controlling an unmanned aerial vehicle (UAV) to provide a target supervision and/or to provide convoy protection to ground vehicles. We first present a control strategy based upon a Lyapunov-LaSalle stabilization method to provide supervision of a stationary target. The UAV is expected to join a predesigned admissible circular trajectory around the target which is itself a fixed point in the space. Our strategy is presented for both high altitude long endurance (HALE) and medium altitude long endurance (MALE) types of UAVs. A UAV flying at a constant altitude (HALE type) is modeled as a Dubins vehicle (i.e., a planar vehicle with constrained turning radiusand constant forward velocity). For a UAV that might change its altitude (MALE type), we use the general kinematic model of a rigid body evolving in \(\mathbb {R}^{3}\). Both control strategies presented are smooth, and unlike what is usually proposed in the literature, these strategies asymptotically track a circular trajectory of exact minimum turning radius. We also present the time-optimal control synthesis for tracking a circle by a Dubins vehicle. This optimal strategy is very rich, although much simpler than the point-to-point time-optimal strategy studied in the 1990s. Finally, we propose control strategies to provide supervision of a moving target, which are based upon theprevious ones.

Integrated chassis control of active front steering and yaw stability control based on improved inverse nyquist array method.

An integrated chassis control (ICC) system with active front steering (AFS) and yaw stability control (YSC) is introduced in this paper. The proposed ICC algorithm uses the improved Inverse Nyquist Array (INA) method based on a 2-degree-of-freedom (DOF) planar vehicle reference model to decouple the plant dynamics under different frequency bands, and the change of velocity and cornering stiffness were considered to calculate the analytical solution in the precompensator design so that the INA based algorithm runs well and fast on the nonlinear vehicle system. The stability of the system is guaranteed by dynamic compensator together with a proposed PI feedback controller. After the response analysis of the system on frequency domain and time domain, simulations under step steering maneuver were carried out using a 2-DOF vehicle model and a 14-DOF vehicle model by Matlab/Simulink. The results show that the system is decoupled and the vehicle handling and stability performance are significantly improved by the proposed method.

Finite-time optimal formation tracking control of vehicles in horizontal plane

This paper studies the problem of finite-time optimal formation tracking for planar vehicles which are considered as rigid bodies, under the condition that the tracking time is given according to task requirements in advance. By using Pontryagin’s maximum principle (PMP) on a Lie group, an optimal control law is designed for vehicles with holonomic dynamics to track a desired reference trajectory at the given tracking time in the manner of rigid formation which is also specified by task requirements. Simultaneously, a corresponding cost function is considered and guaranteed to be optimal. Then, the above mentioned result of tracking is extended to the case of multi-vehicle systems with a directed-tree communication topology. Furthermore, some conditions are proposed to ensure the adjoint orbits of vehicles to be non-holonomic. Finally, the numerical simulations are provided to illustrate the effectiveness of the theoretical results.

Design of Modular Shape-Transition Inlets for a Conical Hypersonic Vehicle

For a hypersonic vehicle, propelled by scramjet engines, integration of the engines and airframe is critical for generation of positive net thrust. To design inlets that integrate well with planar vehicle bodies, a method was developed by Smart to produce rectangular-to-elliptical shape transition inlets. However, these inlets lose their advantage of tight integration when used on nonplanar bodies such as a conical vehicle. In this paper, that design technique is generalized to produce inlets that integrate with arbitrary body shapes. As an example, the design of a body-integrated hypersonic inlet on a winged-cone vehicle is shown, typical of what might be used in a three-stage orbital launch system.

Low‐profile planar roof‐mounted vehicle antenna for monopole vertical polarization reception

AbstractA low‐profile planar vehicle antenna for the roof of a car is proposed for use with terrestrial services. Despite its low configuration, the proposed antenna can realize a vertical polarization. To demonstrate its performance, the proposed antenna is mounted on the roof of a mid‐sized vehicle, and the radiation patterns are measured at three different positions. The omnidirectional patterns are observed in an azimuth plane with 2 dBi of peak gain at 2.3 GHz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:91–94, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26513

The Determination of Vehicle Speeds from Delta-V in Two Vehicle Planar Collisions

The change of a vehicle's velocity, delta-V (Δ v), due to an impact is often calculated and used in the scientific investigation of road traffic collisions. In isolation, however, this figure does not yield any information concerning the actual velocities of the vehicles and such information is often of prime concern to those investigating collisions. In this paper a method is developed which uses the change in velocity sustained by a vehicle in a planar collision to estimate the velocities of the vehicle before and after a collision. The key equations are derived from conservation of momentum, conservation of energy, and restitution. As with the calculation of Δ v, the method requires an initial estimate of the principal directions of force. The pre- and post-impact angles of the vehicles' velocities can be used to obtain better estimates of the principal directions of force and of the coefficient of restitution. In collisions where it is difficult to analyse the vehicles' post-impact motion, this method provides a way to estimate the actual speeds of vehicles. To demonstrate the method, it is used to analyse one of the RICSAC collisions. The results of an analysis of other staged collisions illustrate the accuracy of the method.

Robust overwhelming control of a hydraulically driven three-degrees-of-freedom parallel manipulator through a simplified fast inverse model

An overwhelming controller-based implicit system inversion scheme is proposed in this work to control a hydraulically driven planar (three-degrees-of-freedom) parallel manipulator. The physical model-based design of the controller is developed by using bond graphs. The electro-hydraulic actuator in the leg is modelled by including the dynamics of the servo-valve and the cylinder. A leg-space force-feedback controller is proposed for controlling the hydraulic pressures acting on the pistons of the actuators. The objective is to develop a fast inverse model which is suitable for real-time implementation in the controller. It is shown that an approximate inverse model which correctly represents the kinematics of motion but has incorrect representation of inertias is sufficient for the controller design because of the high feedback gains used in the overwhelming control strategy. This controller, based on the approximate simple inverse model, generates the right driving forces for the actual system whose model is much more complicated and uncertain. Finally, the controller design for a planar vehicle simulator is considered as an example and the corresponding simulation results are used to validate the robustness of the model-based overwhelming controller to the modelling uncertainties.

Pitch dynamic study of a vehicle with a planar suspension system

The suspension system of a vehicle is commonly designed such that the longitudinal connection between the vehicle chassis and the wheels is always very stiff compared with the vertical connection. Such a mechanism can isolate the vibration and absorb the shock efficiently in the vertical direction but it cannot attenuate the impact caused by road obstacles in the longitudinal direction. In order to overcome this limitation, a concept design of a planar vehicle suspension was proposed in which the rather stiff linkages in the longitudinal direction between the chassis and wheel were replaced by elastic connections so that the vibration along any direction in the wheel plane can be isolated. This paper presents the study of pitch dynamic performance of a vehicle with such a conceptual planar suspension in frequency and time domains. The comparison with a conventional suspension is also performed to exhibit the potential of the conceptual design.

Formation control for nonholonomic agents using passivity techniques

This paper studies the problem of the formation control for the multiple nonholonomic agents on a plane. A dynamic feedback linearization method is used to transform the dynamical model of each agent into two third-order integrator chains. A decentralized formation control law with the inter-agent damping injection is derived. The asymptotical stability of the overall system is proven using the Lyapunov method. The simulation of the formation maneuver of a planar vehicle shows the effectiveness of the proposed method.

Vehicle Planar Motion Stability Study for Tyres Working in Extremely Nonlinear Region

Many researches on vehicle planar motion stability focus on two degrees of freedom(2DOF) vehicle model, and only the lateral velocity (or side slip angle) and yaw rate are considered as the state variables. The stability analysis methods, such as phase plane analysis, equilibriums analysis and bifurcation analysis, are all used to draw many classical conclusions. It is concluded from these researches that unbounded growth of the vehicle motion during unstable operation is untrue in reality thus one limitation of the 2DOF model. The fundamental assumption of the 2DOF model is that the longitudinal velocity is treated as a constant, but this is intrinsically incorrect. When tyres work in extremely nonlinear region, the coupling between the vehicle longitudinal and lateral motion becomes significant. For the purpose of solving the above problem, the effect of vehicle longitudinal velocity on the stability of the vehicle planar motion when tyres work in extremely nonlinear region is investigated. To this end, a 3DOF model which introducing the vehicular longitudinal dynamics is proposed and the 3D phase space portrait method is employed for visualization of vehicle dynamics. Through the comparisons of the 2DOF and 3DOF models, it is discovered that the vehicle longitudinal velocity greatly affects the vehicle planar motion, and the vehicle dynamics represented in phase space portrait are fundamentally different from that of the 2DOF model. The vehicle planar motion with different front wheel steering angles is further represented by the corresponding vehicle route, yaw rate and yaw angle. These research results enhance the understanding of the stability of the vehicle system particularly during nonlinear region, and provide the insight into analyzing the attractive region and designing the vehicle stability controller, which will be the topics of future works.

振動軌道上における高速鉄道車両の走行安全性に関する解析的研究 : 輪軸ヨーイングを考慮するモデルでの検討(<特集>D&D 2008)

Recent reports imply that railway vehicles could be derailed solely by the ground motions of earthquakes without fatal damages of vehicles or tracks. Based on the reports and facts, we believe that we should further study the derailment mechanism of a high speed railway vehicle excited by large seismic motions, to pursue to minimize the risk of railway system safety against large earthquakes. We improved our original planar vehicle dynamics simulation model to a model to allow yaw motion of wheel-set, which enable to estimate the influence of the attack angle of wheel/rail and steering effort of the wheel contacting to rail at flange and yielding large radial difference. Through the analyses based on the new model, the following outcomes were obtained. (1) Most of derailments are brought as the result of the rocking motion of a vehicle by track excitations underneath. The excitation amplitudes for derailment are influenced by vehicle speed particularly in lower input frequencies. (2) Wheel climb derailment is not observed. We attribute it to the negative attack angle of wheel/rail during wheel/rail flange contact. (3) At the moment just before derailment when wheel is contacting on rail at flange top, the steering effort of wheel-set, which may contribute to avoid or delay derailment, is not observed.

Classification Scheme for Random Longitudinal Road Unevenness Considering Road Waviness and Vehicle Response

A novel approach to the road unevenness classification based on the power spectral density with consideration of vehicle vibration response and broad interval of road waviness (road elevation PSD slope) is presented. This approach enables transformation of two basic parameters of road profile elevation PSD (unevenness index, C, and waviness, w) into a single-number indicator Cw when using a correction factor Kw accounting for w. For the road classification proposal two planar vehicle models (passenger car and truck), ten responses (reflecting ride comfort, dynamic load of road and cargo, ride safety) and three different vehicle velocities have been considered. The minimum of ten estimated vibration response ranges sum for a broad waviness interval typical for real road sections (w = 1.5 to 3.5) has been used for the correction factor estimation. The introduced unevenness indicator, Cw, reflects the vehicle vibration response and seems to be a suitable alternative to the other currently used single-number indicators or as an extension of the road classification according to the ISO 8608: 1995, which is based on constant waviness value, w = 2.

Classification Scheme for Random Longitudinal Road Unevenness Considering Road Waviness and Vehicle Response

A novel approach to the road unevenness classification based on the power spectral density with consideration of vehicle vibration response and broad interval of road waviness (road elevation PSD slope) is presented. This approach enables transformation of two basic parameters of road profile elevation PSD (unevenness index,C, and waviness,w) into a single-number indicatorCwwhen using a correction factorKwaccounting forw. For the road classification proposal two planar vehicle models (passenger car and truck), ten responses (reflecting ride comfort, dynamic load of road and cargo, ride safety) and three different vehicle velocities have been considered. The minimum of ten estimated vibration response ranges sum for a broad waviness interval typical for real road sections (w= 1.5 to 3.5) has been used for the correction factor estimation. The introduced unevenness indicator,Cw, reflects the vehicle vibration response and seems to be a suitable alternative to the other currently used single-number indicators or as an extension of the road classification according to the ISO 8608: 1995, which is based on constant waviness value,w= 2.

LTV-MPC for Yaw Rate Control and Side Slip Control with Dynamically Constrained Differential Braking

In this paper a novel vehicle lateral dynamic control approach is presented. A differential braking control law based on vehicle planar motion has been designed using a two-degrees-of-freedom vehicle model. On the basis of the estimate of tire longitudinal forces we estimate the range of lateral forces which the tire can exert. Using this constraints a model predictive control (MPC) based on a two-track model is designed in order to stabilize the vehicle. The performances are estimated comparing the results with standard manoeuvers. Simulation results show the benefits of the control methodology used: in particular we show how very effective distribution of braking torque are obtained as a result of this feedback policy.

Artificial cognition for autonomous planar vehicles: modelling collision avoidance and collective manoeuvre

A hierarchical cognitive robotics model for a team of unattended robotic ground vehicles (UGVs) is proposed. The first level rigorously defines conflict resolution for a couple of UGVs, using dynamical games on SE(2)-groups of plane motion. The second level extends it to n UGVs, using Nash-equilibrium approach. The third provides adaptive guidance for several groups of UGVs. The fourth, collective manoeuvre level, proposes a combination of an attractor neural model and a fuzzy-neural 'supervisor', to perform an adaptive path definition and waypoints selection, as well as chaos control. The fifth, cognitive level, performs overall mission planning/feedback control.

Dimensional analysis for robust control of planar vehicle dynamics

AbstractMost engineered systems with similar functions, which are designed under strict external constraints, share similar dynamics. Using a dimensionless model as system representation, a dimensionless robust controller can be designed and implemented for a class of dynamically similar systems that are different in physical dimension. Dimensionless transformations of timescale, inputs and outputs determine a nominal plant model and plant‐to‐plant uncertainties in a dimensionless form. Using parameter‐dependent normalization, a normalized dimensionless model can be derived that has lower levels of plant‐to‐plant uncertainty than previous formulations (IEEE Trans. Contr. Syst. Technol. 2005; 13(4):624–630). The benefit of this dimensional analysis is demonstrated by the dynamic analysis of different types of planar vehicle systems. Numerical results show that, by using dimensional analysis, it is possible to obtain a controller that is robust to plant‐to‐plant parametric uncertainties among specific classes of systems designed with widely varying physical dimensions. Copyright © 2007 John Wiley & Sons, Ltd.

Nonlinear dynamics and stability analysis of vehicle plane motions

In this article, the problems of dynamics and stability for vehicle planar motion systems have been investigated. By introducing a so-called joint-point locus approach, equilibria of the system and their associated stability properties are given geometrically. With this method, it is discovered that the difference between the front and the rear steering angles plays a key role in vehicle system dynamics and that the topological structure of the phase portrait and the types of bifurcations are different from those published previously. In particular, the vehicle system could still be stabilized even when pushed to work in a certain severely nonlinear region, by applying extremely large steering angles. However, it is worth noticing that the attractive domain of the stable equilibrium is very narrow. These developments might prove to be important in active steering control design. Numerical experiments are carried out to illustrate the potentials of the proposed techniques.

Design and evaluation of side slip angle-based vehicle stability control scheme on a virtual test track

This paper describes the development of side slip angle-based vehicle stability control (VSC) schemes and the evaluation of the control schemes on a virtual test track. A differential braking control law based on vehicle planar motion has been designed using a three-degree-of-freedom yaw plane vehicle model. The control threshold for the VSC is designed based on the vehicle body side slip angle. Since VSC always works with the driver, the overall vehicle performance will depend not on how well the VSC works but rather on its interaction with the human driver. Vehicle behavior and interactions between the vehicle, the controller, and the human driver are investigated using a vehicle simulator on a virtual test track (VTT). The VTT consists of a real-time vehicle simulator, a visual animation engine, a visual display, and human-vehicle interfaces. The VTT has been developed and used for the evaluation of the VSC under various realistic conditions in the laboratory. In this paper, the effects of the different control threshold on the vehicle-driver-controller interaction for a novice and expert driver are compared. Test results obtained using the VTT establish the need for a variable control threshold. The VTT makes it possible to perform exhaustive design trials and evaluations in the laboratory without risk of injury before field testing and promises to significantly reduce development cost and cycle time.

Longitudinal road unevenness with periodic components: Characterization and effects on people in a traversing vehicle and the loading of the pavement

Firstly, the effect of periodic components (undulation) appearing in the otherwise random longitudinal profile of road on standard indicators of random unevenness is studied. The power spectral density characterized by its parameters, i.e. the unevenness index and waviness, three band variances, and international roughness index are considered. Secondly, a series of simulation examples is given of the response of two planar vehicle models (a passenger car and a truck) traversing along the road with periodic components of longitudinal unevenness. The effects on people sitting in the vehicle and on the loading of the vehicle undercarriage and pavement structure are studied. The wavelengths of undulation and the running speeds that appear as most inconvenient are emphasized