Showing 4 results for Darvish
E. Khanmirza, H. Darvish, F. Gholami, E. Alimohammadi,
Volume 6, Issue 4 (12-2016)
Abstract
Accurate and correct performance of controller in cruise control systems is important. Hence, in such systems, controller should optimize itself against noise and probable changes in system dynamic. As a matter of fact, in this article three approaches have been conducted to-ward this purpose: MIT, direct estimation and indirect estimation. These approaches are used as controllers to track reference signal. First the performance of each of these three controllers is checked. comparison of performances indicated better behavior for indirect estimation than others. Also, it has less sensitivity against external noise. Finally, by using indirect estimation method as an adaptive control approach, two parallel separate controllers are designed for two inputs, gas and braking, and their performances are compared with recent studies. It shows improvement in performance of adaptive cruise control system to track reference signal.
A. Otadi, M. Masih-Tehrani , S.m. Boluhari , A. Darvish-Damavandi ,
Volume 7, Issue 3 (9-2017)
Abstract
In this paper, a three-axle bus rollover threshold and the effective parameters are studied. The rollover threshold is a speed that automotive is passing without occurring rollover. The objective is a determination of the heavy vehicle rollover critical speed while turning. For this purpose, a three-axle bus is studied. The dynamic equations related to rollover is extracted, and then rollover criterion, which is LTR (Load Transfer Ratio) in this paper, is obtained. The governing equations are simulated in MATLAB software and then the effect of the parameters such as steering rate, road curvature radius, road bank slope and automotive effective parameters on the rollover critical speed is studied. Prior to the investigation of these parameters, due to validation of the simulation model in MATLAB, a three-axle bus with specific parameters values is placed under various maneuvers with different conditions in TruckSim software then results are recorded. In order to validate, these results are compared with the results which are achieved from MATLAB. After validation, the relation between effective parameters in rollover stability and vehicle speed for desire maneuvers is obtained and it is illustrated in form of function. The results of this research work can be used in road threshold speed without huge computation costs and expensive tests.
Ehsan Alimohammadi, Esmaeel Khanmirza, Mr Hamed Darvish Gohari,
Volume 8, Issue 4 (12-2018)
Abstract
In cruise control systems, the performance of the controller is important. Hence, in order to have accurate results, the nonlinear behavior of a vehicle model should also be considered. In this article, a vehicle with a nonlinear model is controlled by using a nonlinear method. The nonlinear term of the model is the generated torque of engine, which is a polynomial equation. In addition, feedback linearization is used as a nonlinear method in order to design two parallel controllers to control the movement of the vehicle. These two parallel controllers are used to control braking and gas pedals which are in charge of the angular velocity of the wheels. To check the performances of controllers, first, each controller is used separately. Finally, two parallel controllers are used to track the reference signal. Comparison between results shows that the designed controller is able to reduce the convergence time of about 10 seconds. This improvement is near 35% in comparison with near studies. In addition, it can reduce the error between the velocity of the vehicle and the values of the reference signal that results in more safety for passengers.
Mr Arash Darvish Damavandi, Dr Behrooz Mashhdi, Dr Masoud Masih-Tehrani,
Volume 13, Issue 3 (9-2023)
Abstract
This paper investigates the performance of the hydraulically interconnected suspension system with the full vehicle model of ride and handling. A sensitivity analysis has been performed by changing the coefficients of the cylinder and accumulator valves and the initial conditions of the accumulators in the default hydraulic circuits to determine the effect on the frequency and damping of the system response such as roll, pitch, and bounce. This study highlights the importance of the influence of all system parameters to investigate vehicle vibration characteristics. The results provide valuable insights for designers and engineers working on improving automotive suspension system performance. Damping and frequency of modes change up to 179% with the change of cylinder valves and 141% with the change of accumulator valves and 74% for the initial pressure of accumulators change in mentioned range.
