| Due to the nonlinear characteristics of stiffness and damping,hydro-pneumatic suspension is widely used in large engineering vehicles,special vehicles and off-road vehicles.With corresponding components such as pipelines and valve blocks,semi-active control of vehicle and adjustment of vehicle body attitude can be realized by control algorithm because of the hydraulic damping characteristics of the hydro-pneumatic suspension.Based on the skyhook control theory and fuzzy control theory,a vehicle attitude compensation control algorithm was designed in this paper.The control algorithm was used to carry out semi-active control for vehicle body attitude of a three-axis mine dump truck equipped with hydro-pneumatic suspension.Firstly,a nonlinear mathematical model of semi-active hydro-pneumatic suspension was established in Simulink.The basic characteristics of the suspension were simulated and analyzed.The damping force model and the elastic force model were separated from the suspension model.The damping nonlinear characteristics and stiffness nonlinear characteristics of the semi-active hydro-suspension were simulated,and the correctness of the semi-active hydro-suspension model was verified.Secondly,the three-axis nine-degree-of-freedom vibration model of the full vehicle and Cclass,D-class random road surface time-domain model were established.Based on the skyhook control algorithm and the fuzzy control algorithm,the skyhook control force and the vehicle body attitude control force were calculated,respectively.The ideal control force of the vehicle body attitude compensation was obtained by the designed semi-active control strategy.The semi-active control was carried out by controlling the flow area of adjustable damping valve.Finally,the control effects of the vehicle body attitude compensation control strategy based on the semi-active hydro-pneumatic suspension was simulated and verified.The performance of semi-active hydro-pneumatic suspension and passive hydro-pneumatic suspension was compared and analyzed.The influence of the addition of body attitude control on the semi-active control was discussed.Based on dSPACE,the hardware-in-the-loop simulation test was carried out to verify the logic correctness and effectiveness of the vehicle attitude compensation control strategy.According to the research conclusions: compared with the passive hydro-pneumatic suspension,the root mean square(RMS)value of the vertical acceleration,the pitch acceleration,the roll acceleration,the body pitch angle and the body roll angle of the vehicle equipped with a semi-active hydro-pneumatic suspension were decreased by 20.38%,19.99%,24.14%,15.18%,14.60%,respectively.The suspension working space and the dynamic tire load were deteriorated,but the deterioration was within the acceptable range.The results indicated that the vehicle body attitude control strategy can effectively suppress the vertical vibration,the pitch vibration and the roll vibration of the vehicle body,and improved the ride comfort and body attitude of the vehicle.The dynamic performance of the vehicle was not affected by the addition of body attitude control,but the attitude of the vehicle body was significantly improved,indicating the rationality and effectiveness of introducing the attitude control into the semi-active control.The results of hardware-in-the-loop simulation(HILS)were consistent with the numerical simulation results,which verified the logical correctness and practical feasibility of the vehicle attitude compensation control strategy and the good performance of the hardware-in-the-loop simulation system(HILSS). |
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