This thesis is concerned with ABS algorithm project for commercial vehicles. In the first part the reader is introduced to the history and first usage of the anti-blocking system, its principles and main functions. There are also driving algorithms and functionality system control. The second part is dedicated to the dynamic model, programs and ADAMS Car and MATLAB Simulink interfaces. It also contains the description of the algorithm, its parameters and basic functionality assay. Simulation, program interlink, testing and tuning are also described. The concluding part deals with results and their assessment.

The object of this master thesis is testing of vehicle using four post rig. The main goal is to make a research about testing and tuning vehicle characteristics on four post rig in order to implement them for testing of TU Brno Racing’s Formula Student racecar. The main method of testing, input signals and measurement description are presented in this thesis. The different methods of analysis of testing data to find best tuning of damper and spring stiffness for different race disciplines are described. In the last part of this work, quarter car model and multibody model in MSC Adams Car is created. Input parameters of model are based on measurements from real car/ component testing, including damper characteristics and static tire radial stiffness for best fit with the characteristics of real vehicle. The measurements themselves were also described in separate chapter of this thesis. The last but not the least goal was to compare these simulations with measurements, made od real four post rig in order to decide whether car model is suitable for racecar development.

The diploma thesis is focused on the measurement of forces acting between the tire and the road. There is an outline of tire and tire models problematic in the opening part. In the following part, the rear right suspension of the formula student car was mounted with strain gauges and the data logging system was described. There is also a multi-body model of the rear axle created in Adams/Car and SAMS software, that is able to calculate forces acting between the tire and the road, taking the measured forces in the suspension, rocker position, and throttle position into consideration. After a series of calibrations and verification measurements, the measurement on the test track was made, with data analysis focused on forces acting between the tire and the road.

Two and three-wheeled vehicles are being used in increasing numbers in many emerging countries. The dynamics of such vehicles are very different from those of cars and other means of transportation. This thesis deals with a study of the dynamics of a motorcycle and an extensively used three-wheeled vehicle, called an “auto-rickshaw” in India. The commercially available multi-body dynamics (MBD) software, ADAMS, is used to model both the vehicles and simulations are performed to obtain insight into their dynamics. In the first part of the thesis, a study of the two wheeler dynamics is presented. A fairly detailed model of a light motorcycle with all the main sub-systems, such as the frame, front fork, shock absorbers , power train, brakes, front and rear wheel including tire slips and the rider is created in ADAMS-Motorcycle. The simulation results dealing with steering torques and angles for steady turns on a circular path are presented. From the simulation results and analytical models, it is shown that for path radius much greater than motorcycle wheel base, the steering torque and angle can be described by only two functions for each of the two variables. The first function is related to the lateral acceleration and can be determined numerically and the second function, in terms of the inverse of the path radius, is derived as an analytical approximation. Various tire and geometric parameters are varied in the ADAMS simulations and it is clearly shown that steady circular motion of a motorcycle can be reasonably approximated by only two curves–one for steering torque and one for steering angle. In the second part of the thesis, a stability analysis of the three-wheeled “autorickshaw” is presented. The steering instability is one of the major problems of the “auto-rickshaw” and this is studied using a MBD model created in ADAMS-CAR .In an Initial model the frame ,steering column and rear-forks (trailing arms) are assumed to be rigid. A linear eigenvalue analysis, at different speeds, reveals a predominantly steering oscillation, called a “wobble” mode, with a frequency in the range of 5 to 6Hz. The analysis results show that the damping of this mode is small but positive up to the maximum speed(14m/s) of the three-wheeled vehicle. Experiments performed on the three-wheeled vehicle show that the mode is unstable at speeds below 8.33m/s and thus the experimental results do not agree with the model. Next, this wobble instability is studied with an analytical model, similar to the model proposed for wheel shimmy problem in aircrafts. The results of this model show that the wobble is stable at low speeds regardless of the magnitude of torsional stiffness of steering column. This is also not matching with the experimental result. A more refined MBD model with flexibility incorporated in the frame, steering column and the trailing arm is constructed. Simulation results with the refined model show three modes of steering oscillations. Two of these are found to be well damped and the third is found to be lightly damped with negative damping at low speeds, and the results of the model with the flexibility is shown to be matching reasonably well with the experimental results. Detailed simulations with flexibility of each body incorporated, one at a time, show that the flexibility in the steering column is the main contributor of the steering instability and the instability is similar to the wheel shimmy problem in aircrafts. Finally, studies of modal interaction on steering instabilities and parametric studies with payload and trail are presented.

Tato práce se se zabývá návrhem kinematiky zavěšení kol obou náprav. Na základě analýz jízdních dat, multi-body simulací v softwaru Adams Car, simulací v Matlabu a analytických kalkulací v Mathcadu, je navržena řada změn s cílem zlepšit jízdní vlastnosti vozu Formule student, tyto změny jsou následně implementovány do CAD modelu vozu. Jednotlivé změny kinematiky náprav jsou provedeny na základě analýzy konkrétního problému, který se snaží řešit. Jednou z problematik je zástavbová náročnost systému odpružení a zavěšení zadních kol, zde je cílem snížit hmotnost, výšku těžiště a moment setrvačnosti. Další problematikou je geometrie předního kola, kde je cílem zlepšit využití pneumatik a snížit síly v řízení. Dále se práce zabývá simulacemi elastokinematiky zadní nápravy, součástí je také návrh měřícího zařízení. V poslední části je zkoumán vliv provedených změn i elastokinematiky na jízdní dynamiku vozu v ustálených stavech za pomocí MM metody simulované s modelem celého vozu v Adams Car a zpracované v Matlabu.