A Semi-Empirical Tire-Model Including the Effects of Camber

This report presents the addition of camber to a previously published semi-empirical tire model by the same authors. The model combines empirical models for pure braking, cornering and cambering to a model for simultaneous braking, cornering and cambering. It is based on brush-model tire mechanics and aims to offer an easy-to-use accurate model for vehicle handling-simulations. The proposed model is a method to extract and rescale the adhesion and sliding forces from empirical pure-slip tire models to account for the combined-slip condition. The combined-slip self-aligning torque is described likewise. Cambering affects the natural path of the tire carcass on the road surface and deforms the threads to produce an additional force in the lateral direction. Thereby, the proportions of the sliding and adhesive forces changes. The model is computationally sound and efficient and does not rely on any additional parameters that depend on combined-slip data for calibration. It can be used in combination with virtually any empirical pure-slip model. The report also contains a validation of the combined slip behavior towards measurement data from a Jeep Cherokee equipped with Goodyear-wrangler tires

A 9-DOF Tractor-Semitrailer Dynamic Handling Model for Advanced Chassis Control Studies

A nonlinear dynamic handling model for a tractor-semitrailer combination vehicle is presented in this report. The equations of motion are derived from the fundamental equations of dynamics in Euler's formulation without approximations. The model is modular in the sense that it is easy to change axle configuration, tyre model, suspension model, or to add new features. The primary aim of the model is simulations of handling scenarios with active yaw control, using unilateral braking and possibly tractor rear wheel steering. Other applications of the model may include real-time hardware-in-the-loop simulations of tractor-semitrailer handling scenarios. The model is formulated as a state-space model that may be implemented in standard simulation environments. A Simulink (TM) implementation is presented. Simulation results are compared with experiments to validate the model

JModelica---an Open Source Platform for Optimization of Modelica Models

Optimization is becoming a standard methodology in many engineering disciplines to improve products and processes. The need for optimization is driven by factors such as increased costs for raw materials and stricter environmental regulations as well as a general need to meet increased competition. As model-based design processes are being used increasingly in industry, the prerequisites for optimization are often fulfilled. However, current tools and languages used to model dynamic systems are not always well suited for integration with state of the art numerical optimization algorithms. As a result, optimization is not used as frequently as it could, or less efficient, but easier to use, algorithms are employed. This paper reports a new Modelica-based open source project entitled JModelica, targeted towards dynamic optimization. The objective of the project is to bridge the gap between the need for high-level description languages and the details of numerical optimization algorithms. JModelica is also intended as an extensible platform where algorithm developers, particularly in the academic community, may integrate new and innovative methods. In doing so, researchers gain access to a wealth of industrially relevant optimization problems based on existing Modelica models, while at the same time facilitating industrial use of state of the art algorithms. The JModelica project rests upon three pillars, namely a language extension of Modelica for optimization entitled Optimica, software tools, and applications. In this paper, these three topics will be highlighted

Truck Model for Yaw Dynamics Control

This report describes the derivation of a nonlinear model of a tractor-semitrailer combination vehicle. The purpose of the model is validation of yaw-control algorithms. The model include 4 DOF in lateral, longitudinal, and yaw motion. It is formulated as a state-spece model with 5 state variables. Additional states are added with the rotational dynamics of the wheels. The model includes a static description of load-transfer, and a fairly detailed tyre model. A linearized version of the model is also presented. The nonlinear model is implemented in Simulink (TM). Validation is performed by comparison with a multibody model. Examples of simulation outputs are given

Friction and Friction Compensation in the Furuta Pendulum

Inverted pendulums are very well suited to investigate friction phenomena and friction compensation because the effects of friction are so clearly noticeable. This paper analyses the effect of friction on the Furuta pendulum. It is shown that friction in the arm drive may cause limit cycles. The limit cycles are well predicted by common friction models. It is also shown that the amplitudes of the limit cycles can be reduced by friction compens ation. Compensators based on the Coulomb friction model and the LuGre model are discussed. Experiments performed show that reduction of the effects of friction can indeed be accomplished