Study On Semi-active Control For Cab's Hydraulic Isolation System Of The Vibratory Roller

The vibratory roller is a type of the soil compactor which is mainly used in the field of the construction project on roads,railways,airports,and so on.In recent years,the vibration roller market has increasingly required not only for compact performance but also on ride comfort,especially the vehicle's ride comfort.In actual operation conditions,the vibratory roller always travels on various kinds of deformable terrains and compacts on different types of elastic-plastic soil grounds.Therefore,the vehicle's body vibration is greatly influenced not only by the exciting drum and engine but also by the excitations of the interaction between wheels/drum and deformable terrains in low-frequency region.The low excitation frequency arising from wheels/drum-soil interactions is mostly transmitted to the driver via cab's isolation system and seat's suspension.These are the main causes for the uncomfortable and fatiguing driver.Consequently,the cab's isolation system of the vibratory roller is one of the most important factors to improve the driver's ride comfort.This study selects a single drum vibratory roller with its cab's hydraulic systems to improve the ride comfort as the research objects.Firstly,a nonlinear vehicle dynamic model with cab's isolation systems is established,and experimental investigations are used to validate the models and verify their accuracy.The isolating performance of the cab's hydraulic mounts is then simulated and compared with both the traditional rubber mounts and the pneumatic mounts.The power spectral density(PSD)acceleration and the weighted rootmean-square(RMS)acceleration responses of the vertical driver's seat,cab's pitch and roll vibrations in both the frequency and time domains are chosen as objective functions to evaluate the ride comfort and health of the driver.Next,in order to enhance further the ride comfort performance of the vibratory roller,a semi-active hydraulic mount used the magnetorheological fluid is studied and developed for cab's hydraulic mounts.Finally,the performance ride comfort of the vibratory roller with semi-active cab's hydraulic mounts is analyzed and evaluated under all actual operating conditions of the vehicle in the time region.Main contents and innovation points of this study are as follows:1.Based on the analysis of nonlinear geometric characteristics of wheels/drum-deformable soil interaction,and objective functions of the PSD acceleration and the weighted RMS acceleration responses of the vertical driver's seat,cab's pitch and roll vibrations.A threedimensional nonlinear dynamic model of a single drum vibratory roller is established which including based on Adam and Kopf's elastic-plastic soil model and Bekker hypothesis of the deformable soil ground.A quarter of the wheel/drum-terrain contact model is respectively established to analyze the vertical excitation force acting on the front and rear vehicle frame.Matlab/Simulink software is then used to build and simulate the nonlinear dynamic models as well as to calculate the objective functions.By comparing the results between the numerical simulation and the vehicle ride test with cab's rubber mounts under the different operating conditions which have verified the validity of models.The vibrating isolation performance of the cab's hydraulic mounts is then analyzed and compared with both the traditional rubber mounts and the pneumatic mounts according to ISO 2631: 1997(E)standard.The results show that:(1)when the vibratory roller travels on a deformable terrain with the poor terrain roughness surface,the maximum PSD values and the weighted RMS acceleration responses of the vertical driver's seat,cab's pitch and roll vibrations with the hydraulic mounts are the lowest.(2)when the vibratory roller moves and compacts at a low/high excitation frequency 28/35 Hz of the drum on an elastic-plastic soil with the high-density soil,the maximum PSD values and the weighted RMS acceleration responses of the vertical driver's seat,cab's pitch and roll vibrations with the hydraulic mounts also are smallest.Therefore,the hydraulic mounts have good low-frequency vibration characteristics which benefit the improvement of the ride comfort of the vibratory roller.2.Based on the nonlinear dynamic model of the vehicle with the cab's hydraulic mounts and their objective functions.Semi-active hydraulic mount used the magneto-rheological(MR)fluid is researched for cab's isolation system,and Fuzzy-PID controller in which the fuzzy control rules optimized by the genetic algorithm program is then developed to control MR damping force of semi-active hydraulic mount.The vibrating isolation performance of semiactive hydraulic mount with optimal fuzzy rules is then simulated and compared with both semi-active hydraulic mount without optimal fuzzy rules and passive hydraulic mounts.The simulation results show that the vehicle ride comfort is greatly enhanced by the semi-active hydraulic mount with optimal fuzzy rules when the vehicle travels on a poor off-road terrain surface terrain of Grenville loam and compacts on a high-density soil of elastic-plastic soil ground in both the frequency and time region.3.In order to fully evaluate the performance of semi-active hydraulic mount with optimal fuzzy rules in all various operation conditions,the vehicle forward speed region and the different deformable terrains in the condition of the vehicle traveling to the workshop,and the various elastic-plastic soil grounds in the condition of the vehicle working in the workshop are respectively carried out to simulate and analysis performance ride comfort via the weighted RMS acceleration responses of the vertical driver's seat,cab's pitch and roll vibrations.The results also show that the weighted RMS values of the vertical driver's seat,cab's pitch and roll vibrations are clearly reduced by the semi-active hydraulic mount with optimal fuzzy rules under all operating conditions of the vibratory roller.Thus,the vibratory roller ride comfort is significantly improved with cab's isolation system equipped by the semi-active hydraulic mount with optimal fuzzy rules under all operating conditions of the vehicle.