Juan J. Castillo

A fuzzy logic control for antilock braking system integrated in the IMMa tire test bench

The use of fuzzy control strategies has recently gained enormous acknowledgement for the control of nonlinear and time-variant systems. This article describes the development of a fuzzy control method for a tire antilock system in vehicles while braking, integrated in a tire test bench, thereby allowing us to imitate the functioning and to understand the behavior of these systems in a reliable way. One of the inconveniences found in the development of these systems has been the difficulty of adjustment to the real conditions of a functioning vehicle. The main advantage obtained when using the tire test bench is the possibility of being able to reproduce the conditions established as fundamental to the operation of the antilock brake system (ABS) in a reliable and repetitive way, and to adjust these systems until optimal performance is obtained. The fuzzy control system has been developed and tested in the tire test bench to be able to refine its fundamental parameters, obtaining adequate results in all the studied conditions. The ease of the bench for the development and verification of new control systems for ABS has been demonstrated.

A Novel Electrohydraulic Brake System With Tire–Road Friction Estimation and Continuous Brake Pressure Control

The braking system is the main active safety equipment of vehicles. This paper presents a new brake system architecture based on the use of proportional servovalves. The use of servovalves allows for faster and more precise control of the pressure, preventing the wheels from locking and reducing braking distances. A new control block has been developed to determine the optimum pressure in the braking circuit. The new controller is based on the use of fuzzy logic techniques. A Kalman-filter-based estimation algorithm allows for obtaining the adhesion between the wheel and road surface and vehicle speed. These parameters are used in a fuzzy block to detect the road type. Using the road type, an artificial neural network gives an estimation of the slip that produces higher adhesion, and a final block, which is also based on fuzzy logic, determines the optimal pressure in the braking circuit. The performance of the new brake architecture and controller is evaluated by simulating driving on different road surfaces and with real tests on dry and wet asphalt.

An optical tire contact pressure test bench

An optical tire contact pressure test bench developed by the IMMa group is described. The measurement system is based on the frustration of total internal reflection (FTIR) of light. The test bench allows performing normal pressure distribution and patch contact shape measurements on passenger car tires. The system is based on the use of a laterally illuminated glass on which the tire leans. Between them a plastic interphase is located that will cause the FTIR of light. A video camera catches the formed shining image through the glass. The brightness level in each pixel of the image can be related to the existing normal pressure. The study of the contact patch provided by the bench makes it possible to characterize tire behaviour under different loading states, inflation pressure, tire defects and toe and camber angles. The bench incorporates a computerized load and control system of the tire operation parameters, an image acquisition module and a data acquisition system that allow monitoring and acting on the experimental variables of interest in the tests such as load on the tire and environmental conditions. A supporting mechanical system incorporated to the bench allows providing the tire with variable toe and camber angles. From the images obtained with this system, the maximum normal pressure points, total force, size and shape of the patch can be determined, which are related to the tire-use conditions. As an application example, results that show the patch size and shape under different load and tire inflation pressures are presented. A further application, which is the use of the system for the detection and study of defective tires is also presented.

Design and Modelling of Omnibola©, A Spherical Mobile Robot

A spherical mobile robot called Omnibola© is introduced and analyzed in this article. Some advantages of this kind of robot compared with typical wheeled robots are described. Its geometry and its features are presented, emphasizing on those which make it different from other ball-shaped robots. A mathematical model has been developed to have a tool to study our robot dynamics. We conducted some experiments to confirm that model results are similar to experimental results observed in the real robot. Either in experiments or in simulations, the robots behavior is quite oscillatory. Because of this, a simple control law is proposed to stabilize that oscillatory motion.

Synthesis of Mechanisms with Evolutionary Techniques

The paper deals with optimal synthesis solution methods to planar mechanisms. Several searching procedures are defined in this work, which apply algorithms based on evolutionary techniques. These algorithms are used to solve different synthesis problems of planar mechanisms. Concretely, a path, a multiobjective optimization and a structural synthesis of mechanism are used to test the method, showing that solutions are accurate and valid for all cases. This work is a summary of the research that our group has carried out over several years and we continue investigating due to the great interest shown by the mechanism synthesis community who use these kinds of techniques.

Evolutionary Optimization of a Motorcycle Traction Control System Based on Fuzzy Logic

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 study 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.

Analysis and evaluation of a tyre model through test data obtained using the IMMa tyre test bench

Nowadays, obtaining results on the forces and torques in a tyre, in controllable and repetitive working conditions in a laboratory, is fundamental for research groups in vehicle dynamics simulations. There is a need, more than a convenience, to own a facility to test tyres of a wide range of dimensions and with versatile and non-restricted operating conditions of functioning. In this paper a group of experimental data obtained from tests on a tyre in the IMMa tyre test bench is presented. With the goals of determining the accuracy of these experimental test data and also the operating performance of the test bench in the steady state, the analytical model of pneumatic tyres for vehicle dynamics simulations reported by Gim and Nikravesh is employed.

A Procedure for Determining Tire-Road Friction Characteristics Using a Modification of the Magic Formula Based on Experimental Results

Knowledge of tire-road friction characteristics is essential for the proper performance of most relevant vehicle active safety systems. Therefore, its determination is necessary to improve the effectiveness of these systems and to avoid or reduce the consequences of traffic accidents. For this reason, there is a great deal of literature concerning methods and devices for measuring and modeling tire-road friction. Most of these methods have focused on determining the road friction resistance, taking only road composition and making measurements in wet conditions into account. However, friction forces are also dependent on the tire type, since the contact is established between the tire and the road in real driving conditions. Thus, the type and characteristics of the tire have to be considered in the study of the interaction between the vehicle and the road. The aim of this work is to unify the study of the friction coefficient, taking into consideration the two existing bodies involved in the contact, i.e., the tire and road and the main factors that influence the forces in the contact. To this end, a modification of the Pacejka Magic Formula is proposed to include the effects of the main parameters that influence the contact, such as road composition and its state, tire type, vehicle speed, and slip between the tire and the road. To do so, real tests have been conducted on several roads and with different operating conditions. As a result, a more accurate tire-road friction model has been obtained.

Design of a Driving Module for a Hybrid Locomotion Robot

One of the challenges in today’s mobile robotics is the design of high mobility and maneuverability robots. In this work we present the design and construction of a new concept of a locomotion system for mobile robots. It consists of a hybrid leg-wheel module that can be attached to the main body of a robot in a similar way to a conventional wheel. The mechanical configuration of the driving module is described, emphasizing the characteristics which make it different from other hybrid locomotion systems. A dynamic model that simulates the movement of the module was developed to analyze its behavior and to test different control algorithms that were subsequently implemented on the real module. Finally, we have carried out a series of simple experiments that demonstrate the correct operation of the module on flat ground without obstacles.

Optimal Design of Motorcycle Rear Suspension Systems Using Genetic Algorithms

Acceleration, braking and turning capabilities are widely influenced by the parameters of the suspension systems. In this paper a geometric configuration of a rear suspension that fits a chosen target curve is obtained. The procedure followed in this study begins by choosing the topology of the rear suspension system. After that, the rear suspension characteristics are selected (highest and lowest force, progressiveness, squat ratio…). Subsequently, user-defined functions are used to obtain the position of each suspension element along the path and, later, to get the forces at each point of the system. Finally, a genetic algorithm is used to obtain an appropriate geometry of the rear suspension elements which fits the given requirements. An example is included to demonstrate the behavior and potential of the method. This strategy takes into account both the progressiveness and desired squat-ratio of the system, which have never been included in a rear suspension design before.