This context exhaustively investigates the ride comfort performance index on the proposed active suspension vehicle system. Ride comfort in terms of occupants (includes driver and passenger) head acceleration, sprung mass vertical and pitching accelerations is considered. For this examination, a 14-degree-of-freedom human vehicle road integrated system model was extensively developed. Then, an active suspension system composed of a hydraulic actuator and proportional-integral-derivative controller is incorporated into the developed vehicle model to enhance the ride comfort. Besides, the designed controller needs to satisfy other vehicle performance indices like vehicle stability and ride safety. Accordingly, the controller parameters were optimally tunned with the help of genetic algorithm technique, on the basis of integral time absolute error criterion. The objective function was created on the basis of minimizing the integral time absolute error of sprung mass displacement, suspension working space and tire deflection responses. The entire response of human vehicle road integrated model, with the proposed active suspension system and passive suspension system on various random road surfaces (A, B, C, D and E with respect to ISO 8608) with five constant speeds (20, 40, 60, 80 and 100 kmph), was compared via surficial presentation. Furthermore, the comfort measures such as root mean square and vibration dose value from ISO 2631-1 were adopted to evaluate the severity between the occupants via head acceleration response. The simulation results showed that the suggested active suspension system significantly improved the ride comfort with guaranteed vehicle stability and ride safety.

In order to improve the ride comfort of the driver, a higher-order Sliding Mode Controller was proposed in this study for a semiactive magnetorheological (MR) suspension system. The work is mainly focused on improving the ride comfort of the driver with simultaneous improvement in road holding capability of the vehicle and to study the effects of using Super Twisting Sliding Mode Controller (STSMC) in a quarter car with driver seat model. The modified Bouc-Wen model was simulated using MATLAB/Simulink software and the STSMC was adopted to control the voltage variation in MR damper using Continuous State Control (CSC) algorithm. The controller and the suspension system parameters were analysed in time domain with random road inputs. Fast Fourier Transform (FFT) analysis was also carried out to show the effectiveness of the controller towards improving the driver seat comfort. The STSMC-controlled MR damper was used as a primary suspension and the effectiveness of its controllability was compared with passive suspension system. The uncontrolled MR suspension system was also analysed in order to verify the fail-proof advantage of the MR damper. From the results, it was found that the ride comfort was extremely improved when STSMC controller was used than when the uncontrolled MR and passive suspension systems were employed. The uncertainty of the STSMC was verified for different passenger masses and it achieved a robust control over load variation. The selected STSMC was validated with the first-order Sliding Mode Controller and the results were discussed in terms of time-domain analysis.

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A tractor is a machine which is predominantly used for various agricultural operations such as plowing, tilling, planting, harvesting, etc. Apart from the regular agricultural applications, currently, tractor is being also used for various other applications such as haulage, dozing, loading, digging, and so on. Because of the versatility in usage patterns and applications, it is extremely difficult to estimate the loads coming on different structural parts of a tractor. Therefore, fatigue behaviors of different structural parts are also highly unpredictable. Limited test methodologies or information are available about the testing methodologies to validate the structural parts of a tractor. Conventional uniaxial load tests may not be sufficient to replicate actual Real World Usage Pattern (RWUP) as different structural failures are reported from field testing or end customers despite clearing in different lab testing. On the other hand, multiaxial loading may produce more realistic and accurate test results. In this paper, an attempt has been made to develop a practically deployable and simple to use laboratory test methodology considering multiaxial loading to validate Rear Axle Carrier (RAC) assembly of a tractor. At the end of the study, simple to put methodology has been demonstrated in which all the stated objectives were full filled. Real time acquired load data have been used to analyze and develop the duty cycle with a considerable test time reduction in place. This methodology can be used for validating similar kind of structures.