Tyre behavior plays an important role in vehicle dynamics research. Knowledge of tyre properties is necessary to properly design vehicle components and advance control system. For that purpose mathematical models of the tyre are being used in vehicle simulation models. The Magic Formula Tyre Model is a semi-empirical tyre model which describes tyre behavior quite accurately. The Magic Formula Tyre Model needs a set of parameters to describe the tyre properties; the determination of these parameters is dealt with in this paper. A new method based on genetic techniques is used to determine these parameters. The main advantages of the method are its simplicity of implementation and its fast convergence to optimal solution, with no need of deep knowledge of the searching space. So to start the search, it is not necessary to know a set of starting values of the Magic Formula parameters. The comparison between analytical optimization methods and the method proposed is discussed in this paper.
This paper deals with optimal temporal‐planning of wheeled mobile robots (WMRs) when navigating on predefined spatial paths. A method is proposed to generate a time‐optimal velocity profile for any spatial path in static environments or when mobile obstacles are present. The method generates a feasible trajectory to be tracked by fully exploiting velocity, acceleration and deceleration boundaries of the WMR, and by ensuring the continuity of the velocity and acceleration functions. As an additional benefit for the tracking process the jerk is also bounded. The algorithm is not time consuming, since it mostly uses closed mathematical expressions, nonetheless iteration strategies are presented to solve specific situations. However, such situations are not expected to occur when the spatial paths are planned as smooth curves. The success of the algorithm was tested by experimental and simulation results on the WMR “RAM.” © 2003 Wiley Periodicals, Inc.
Braking and traction control systems are fundamental vehicle safety equipments. The first ones prevent the wheels from locking, maintaining, when possible, the handling of the vehicle under emergency braking. While the second ones control wheel slip when excessive torque is applied on driving wheels. The aim of this work is to develop and implement a new control model of a traction control system to be installed on a motorcycle, regulating the slip in traction and improving dynamic behavior of two-wheeled vehicles. This paper presents a novel traction control algorithm which makes use of a fuzzy logic control block. Two strategies to create the control block have been carried out. In the first one, the parameters that define the fuzzy logic controller have been tuned according to experience. In the second one, the parameters have been obtained by means of an Evolutionary Algorithm (EA) in order to design an augmented traction controller. It has been proved that the use of EA can improve the fuzzy logic based control algorithm, obtaining better results than those produced with the control tuned only by experience.
2005) Experience with the IMMa tyre test bench for the determination of tyre model parameters using genetic techniques, Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility, 43:sup1, 253-266,The study of tyre behaviour is an interesting area in vehicle dynamics research. There are a great number of researchers working in this area. So knowledge of the tyre properties is necessary to design vehicle components and advance control systems properly. For that purpose, mathematical models of the tyre are used in vehicle simulation models. Semiempirical models can be used for this. These kinds of tyre model use a certain number of parameters that define them. Semiempirical models need to fit measurement data to the tyre properties that they define. The determination of these sets of parameters and the measurement data obtained are dealt with in this paper. A new method based on genetic techniques is used to determine these parameters. The main advantages of the method are its simplicity of implementation and its fast convergence to an optimal solution, with no need for an extensive knowledge of the searching space. So, to start the search, it is not necessary to know a set of starting values of the parameters that define the tyre model. A set of measurements that define several tyre properties are obtained on the IMMa tyre test bench. These measurement data are used to compare with results from the method proposed, and a new mutation procedure has been developed.
This work is intended to show the feasibility of the utilisation of a shear-thickening fluid as working fluid in a steering damper for motorcycles. To that end, a prototype of a steering damper has been designed and then tested under different working conditions. Unlike conventional models, this new steering damper bases its performance on the combination of very simple rod geometries and a shear-thickening fluid of different concentrations. The experiments carried out with a test machine demonstrate that, despite its simplicity and reduced cost of manufacturing, the prototype shows similar behaviour to a conventional high-performance racing steering damper. The Bouc-Wen model has been used to reproduce the behaviour of the shear-thickening fluid-based damper prototype. The parameters of the model have been obtained following an optimization process to fit the model’s response to the experimental data when exciting the absorber at different speeds. Results show that the damper’s behaviour can be properly modelled with a single combination of parameters.
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