Mobility Of Wheeled Vehicles Research Articles

Validation of a new road and contact model for vehicle–soft soil terrain interaction through an elaborate modelling of the FED-Alpha vehicle

Employing multibody dynamic simulations with semi-empirical tyre models is widely recognised as a cost-effective approach. A recent development introduces a novel road and tyre–soil contact model that is not only swift and memory-efficient but also addresses limitations in classical semi-empirical models. This study conducts a thorough validation of the new road and contact model by creating a detailed multibody model of the four-wheeled vehicle, Fuel Efficiency Demonstrator – Alpha, integral to NATO’s Next-Generation reference mobility model. The comprehensive model encompasses the chassis, suspension, tyres, engine, transmission and various other components. Through simulations of various driving scenarios, accounting for complex terrain geometries, spatially varying soil properties and multi-pass phenomena, the model’s performance is evaluated. The simulation results are compared with physical measurements, providing a detailed assessment of the tyre–soil model’s predictive accuracy for wheeled vehicle mobility on deformable terrains.

Developing a model for measuring the spatial disability level of cities within the framework of barrier-free pedestrian accessibility: the case of Kırklareli City centre

The problem of disability is directly related to the physical barriers encountered in urban spaces. Pedestrian accessibility performance is a notable urban quality indicator. Universal design principles and barrier-free design standards are important in making urban spaces usable for everyone. However, projects in this context generally cover specific areas of cities. Bringing an entire city into compliance with barrier-free design standards requires high cost and time. Therefore, determining the spatial disability level of the urban texture and planning project stages constitute a critical process for local governments. This study proposes a model to measure the pedestrian accessibility performance of medium-sized cities with relatively walkable distances within the framework of spatial barriers and to identify priority intervention points. In this context, Kırklareli city centre was selected as a case study area. According to the model developed with the support of GIS, the “ideal accessibility network” is determined for the citizens, and the performance level is calculated by identifying the spatial barriers on this network. The model was developed using components that can be applied to any city and tested in a sample urban environment. This conceptual model contributes to urban science and local government policy by providing a monitoring mechanism for spatial disability that can be constantly tracked by citizens, and by supplying an information base for projects to be developed by local governments. It is hoped that this study will popularise pedestrian-oriented spatial design and control in cities where walkability is postponed due to the focus on wheeled vehicle mobility and where spatial barriers are felt only by disabled individuals.

Calibration of an expeditious terramechanics model using a higher‐fidelity model, Bayesian inference, and a virtual bevameter test

AbstractThe soil contact model (SCM) is widely used in practice for off‐road wheeled vehicle mobility studies when simulation speed is important and highly accurate results are not a main concern. In practice, the SCM parameters are obtained via a bevameter test, which requires a complex apparatus and experimental procedure. Here, we advance the idea of running a virtual bevameter test using a high‐fidelity terramechanics simulation. The latter employs the “continuous representation model” (CRM), which regards the deformable terrain as an elasto‐plastic continuum that is spatially discretized using the smoothed particle hydrodynamics method. The approach embraced is as follows: a virtual bevameter test is run in simulation using CRM terrain to generate “ground truth” data; in a Bayesian framework, this data is subsequently used to calibrate the SCM terrain. We show that (i) the resulting SCM terrain, while leading to fast terramechanics simulations, serves as a good proxy for the more complex CRM terrain; and (ii) the SCM‐over‐CRM simulation speedup is roughly one order of magnitude. These conclusions are reached in conjunction with two tests: a single wheel test, and a full rover simulation. The SCM and CRM simulations are run in the open‐source software Chrono. The calibration is performed using PyMC, which is a Python package that interactively communicates with Chrono to calibrate SCM. The models and scripts used in this contribution are available as open source for unfettered use and distribution in a public repository.

Comparing the physical principles of action of suspension damping devices based on their influence on the mobility of wheeled vehicles

This paper reports the comparison of two physical principles of action of suspension damping devices based on their influence on the mobility indicators for an 8×8 wheeled machine. A radical difference between these principles of action is the dependence of resistance forces on the speed of the relative movement of working bodies (internal friction: hydraulic shock absorbers) or on the relative movement of working bodies (external friction: friction shock absorbers). Widespread hydraulic shock absorbers have certain disadvantages that do not make it possible to further increase the mobility of wheeled or tracked vehicles without the use of control and recuperation systems. In turn, in friction shock absorbers, the use of new materials has eliminated many of their shortcomings and thus can provide significant advantages. It was established that the application of friction shock absorbers for a given wheeled vehicle did not significantly affect the speed compared to hydraulic ones. The main factor that prevented the implementation of the advantages of friction shock absorbers was the insufficient suspension travel. However, friction shock absorbers absorbed 1.76...2.3 times less power, which reduced the load on nodes and increased efficiency (autonomy). In addition, a more uniform load on suspensions was ensured, which improved their resource, and, due to the prevailing vertical oscillations of the suspended body over the longitudinal-angular ones, the geometric passability improved as well. The comparison of two physical principles of action of damper suspension devices in a wheeled vehicle has shown that the use of friction shock absorbers could provide significant advantages in resolving the task relates to improving the mobility and would fundamentally affect the choice of the suspension energy recuperation system if it is applied.

Experimental study on wheel-soil interaction mechanics using in-wheel sensor and particle image velocimetry part II. Analysis and modeling of shear stress of lightweight wheeled vehicle

Wheeled vehicle mobility on loose sand is highly subject to shear deformation of sand around the wheel because the shear stress generates traction force of the wheel. The main contribution of this paper is to improve a shear stress model for a lightweight wheeled vehicle on dry sand. This work exploits two experimental approaches, an in-wheel sensor and a particle image velocimetry that precisely measure the shear stress and shear deformation generated at the interaction boundary. Further, the paper improves a shear stress model. The model proposed in this paper considers a force chain generated inside the granular media, boundary friction between the wheel surface and sand, and velocity dependency of the friction. The proposed model is experimentally validated, and its usefulness is confirmed through numerical simulation of the wheel traction force. The simulation result confirmed that the proposed model calculated the traction force with an accuracy about 70%, whereas the conventional one overestimated the force, and its accuracy was 13% at the best.

Оценка показателей криволинейного движения автопоезда с помощью имитационного математического моделирования

Introduction: a widespread approach to the transportation of large-sized and heavy-weight indi-visible cargo on roads and terrain is the use of multi-axle wheeled transport complexes, which are road trains. At the same time, due to the significant overall dimensions, one of the most important properties of such machines is agility, that is, the ability to move along a trajectory of large curvature in a limited area, which is especially important in loading / unloading zones. Subject of research: the article presents an approach to predicting the indicators of curvilinear movement of multi-axle wheeled road trains, based on the application of the method of mathemati-cal modeling of the dynamics of body systems. Methodology and methods: the essence of the method is to create a mathematical model of the movement of a road train, represented by a system of rigid bodies, which are interconnected by kin-ematic and power connections. The simulation model developed within the framework of the study makes it possible to take into account with high accuracy the peculiarities of the interaction of the wheel propeller with the supporting surface, the redistribution of normal reactions between the sup-port modules, as well as the force factors arising in the coupling device and ensuring the interaction between the tractive vehicle and the trailer link. The mathematical description of the interaction of the propeller with the ground is based on the concept of “friction ellipse”. Using the presented mod-el, an assessment of the turnability of a wheeled road train equipped with a trailed link with swivel and non-swivel wheels was carried out. The required width along the tracks of the outer (running in) and inner (lagging) wheels was used as an assessment criterion. To assess the feasibility of using a trailed link with fully steered wheels and, accordingly, complicating the design of the machine, an additional assessment of the required power of the steering drive was carried out. Results and scientific novelty: a mathematical model of the dynamics of a road train was de-veloped. It makes possible to predict with high accuracy the indicators of curvilinear movement of wheeled vehicles, as well as to estimate the required power of the steering drive. Practical significance: a mathematical model of road train movement was developed, which al-lows a wide range of tests to be carried out to assess not only the indicators of curved-linear move-ment, but also the mobility of wheeled vehicles of any configuration as a whole.

A high-fidelity approach for vehicle mobility simulation: Nonlinear finite element tires operating on granular material

Assessing the mobility of off-road vehicles is a complex task that most often falls back on semi-empirical approaches to quantifying the vehicle–terrain interaction. Herein, we concentrate on physics-based methodologies for wheeled vehicle mobility that factor in both tire flexibility and terrain deformation within a fully three-dimensional multibody system approach. We represent the tire based on the absolute nodal coordinate formulation (ANCF), a nonlinear finite element approach that captures multi-layered, orthotropic shell elements constrained to the wheel rim. The soil is modeled as a collection of discrete elements that interact through contact, friction, and cohesive forces. The resulting vehicle/tire/terrain interaction problem has several millions of degrees of freedom and is solved in an explicit co-simulation framework, built upon and now available in the open-source multi-physics package Chrono. The co-simulation infrastructure is developed using a Message Passing Interface (MPI) layer for inter-system communication and synchronization, with additional parallelism leveraged through a shared-memory paradigm. The formulation and software framework presented in this investigation are proposed for the analysis of the dynamics of off-road wheeled vehicle mobility. Its application is demonstrated by numerical sensitivity studies on available drawbar pull, terrain resistance, and sinkage with respect to parameters such as tire inflation pressure and soil cohesion. The influence of a rigid tire assumption on mobility is also discussed.

Quadruped robot trotting over irregular terrain assisted by stereo-vision

Legged robots have the potential to navigate in challenging terrain, and thus to exceed the mobility of wheeled vehicles. However, their control is more difficult as legged robots need to deal with foothold computation, leg trajectories and posture control in order to achieve successful navigation. In this paper, we present a new framework for the hydraulic quadruped robot HyQ, which performs goal-oriented navigation on unknown rough terrain using inertial measurement data and stereo-vision. This work uses our previously presented reactive controller framework with balancing control and extends it with visual feedback to enable closed-loop gait adjustment. On one hand, the camera images are used to keep the robot walking towards a visual target by correcting its heading angle if the robot deviates from it. On the other hand, the stereo camera is used to estimate the size of the obstacles on the ground plane and thus the terrain roughness. The locomotion controller then adjusts the step height and the velocity according to the size of the obstacles. This results in a robust and autonomous goal-oriented navigation over difficult terrain while subject to disturbances from the ground irregularities or external forces. Indoor and outdoor experiments with our quadruped robot show the effectiveness of this framework.

Tire designs for mobility—USSR

The Soviet Union has developed many types of tires to increase the mobility of wheeled vehicles. Five design types are described with characteristics, models, sizes, and construction details noted. This information is primarily the result of searching Soviet publications. The five design types will be discussed in their order of dev elopment. The focus of this report is on tires for use on military transport vehicles.

The effect of tire chains on wheeled vehicle mobility: P.W. Haley and F.J. Janosi. Land locomotion Lab. 21 pp. (Oct. 1966).

The effect of tire chains on wheeled vehicle mobility: P.W. Haley and F.J. Janosi. Land locomotion Lab. 21 pp. (Oct. 1966).