Research On Vibration Semi-Active Control Of Vehicle Seat Based On Cube Stewart Mechanism

Vehicles such as commercial vehicles and non-road vehicles often work in harsh working conditions.The vibrational excitation of the ground input is large in this situation.Due to the limit of the structure,the natural frequency of the suspension of such vehicles is high,which seriously affects the ride comfort of the vehicle.Therefore,during the commercial vehicles and non-road vehicles driving,the driver should withstand low-frequency and high-intensity vibration for a long time,which will cause fatigue driving,cause safety accidents,and even damage the driver’s lumbar spine,spine,chest and internal organs.So,it is necessary to design damping seat suspension for non-road vehicles to improve the ride comfort of drivers.Because commercial vehicles and non-road vehicles will be excited by vibration in multiple directions,it is very necessary to study multi-dimensional damping seat suspension which can attenuate multi-directional vibration.Aiming at this problem,the multi-dimensional damping of vehicle seat semi-active control is studied in this paper.Combining the magnetorheological fluid damper,which can realize semi-active control,with the cube Stewart mechanism,which can realize multi-dimensional vibration reduction,a new multi-degree-of-freedom seat damping suspension has been proposed.The suspension system is mainly based on the cubic Stewart mechanism and MRF damper.The virtual prototype model and test prototype model of the seat damping platform have been established.The multi-dimensional damping semi-active control is studied.The main research contents include the following aspects:(1)The kinematic analysis of the cubic Stewart mechanism is carried out.According to the inverse kinematics equation,the relative motion velocity of each leg of the Stewart mechanism can be obtained by the velocity and angular velocity of the center position of the upper and lower platform.Using this method,the measurement of parameters is simplified.When the semi-active control is implemented,we can only use two sensors to control six legs separately.(2)The damping characteristic test of the magnetorheological damper was carried out.According to the test data,the modeling of the magnetorheological damper was completed based on the Bouc-Wen model.The experimental and simulation results show that the Bouc-Wen model can accurately reflect the mechanical characteristics of MRF damper.Then the inverse model of MRF damper developed by Grey Wolf algorithm optimizes BP neural network has been established to solve the control current from the expected output damping force.Compared with the unoptimized BP neural network,the optimized neural network reduces the error of the inverse model and improves the prediction accuracy of the control current.(3)A fuzzy skyhook control method based on the grey wolf optimizer(GWO)has been proposed.Aiming to overcoming the shortcoming that it is difficult to accurately select fuzzy control parameters,the GWO algorithm is used to optimize the selection of fuzzy control parameters based on the acceleration of the seat upper platform.Then the single degree of freedom seat suspension simulation model and test prototype are established.The simulation and experimental research of semi-active control are carried out.The research results show that the semi-active control method can effectively reduce the vibration of seat suspension in low frequency region.(4)The virtual prototype model of multi-dimensional seat damping platform is established,and the multi degree of freedom semi-active control simulation analysis is carried out.The simulation results show that using this method can improve the vibration damping performance of the seat suspension in the vertical,horizontal,and roll directions simultaneously.The angular acceleration and acceleration in the three directions are significantly lower than that of passive vibration reduction.The comfort weighting result shows that after adopting semi-active control,the overall weighted acceleration of the upper platform on the seat drops by 19.7%.Meanwhile,the test prototype of multi-dimensional seat damping platform is manufactured,and the vertical,horizontal and roll directions of the seat test prototype are studied.The test results show that the multi-dimensional damping seat suspension proposed in this paper can reduce the vibration excitation in three directions.In summary,this paper establishes a vehicle multi-dimensional damping seat platform with cubic Stewart mechanism as the carrier and MRF damper as the control mechanism,and establishes the fuzzy skyhook semi-active control method optimized by gray wolf algorithm optimization.The research results show that good damping effects can be achieved for vibration excitation in multiple directions.The semi-active control multi-dimensional damping seat platform established in this paper can effectively improve the vibration acceleration response in the vertical direction,horizontal direction and roll direction in the low frequency area,and improve the overall driving comfort of the vehicle.