| High speed tracked special vehicles have high off-road mobility and powerful attack firepower.Their driving conditions are complex,with frequent gear changes.The reliability and remaining life of structural components will change with changes in mission profile and road load.The scheduling and operation decision-making of special vehicles require timely acquisition of the load time history of structural components such as the transmission system gear shaft system and support components.However,due to its limited space,sensors such as torque testing cannot be installed,and road load information is missing.Based on the limited temperature,pressure,speed,and engine operating status information of the transmission system on the actual vehicle bus,combined with the integrated transmission system dynamics model,obtaining the operating load time history of the transmission system structural components has become an urgent demand for the development of vehicle health management and intelligent operation and maintenance technology.In response to the above issues,this article conducted relevant research on time-varying dynamic modeling and load calculation analysis of special vehicle transmission systems.To meet the real-time monitoring and health management requirements of the load characteristics of the comprehensive transmission system of special vehicles under practical complex working conditions,the matrix analysis method and numerical solution method of planetary transmission mechanism are used for modeling.Using sensor data such as throttle opening,engine speed,turbine speed,and shift clutch oil pressure as model inputs.A dynamic model has been established to quickly and continuously solve the transmission output speed and torque under time-varying working conditions.A fast and continuous solution method for dynamic models under time-varying operating conditions has been proposed.The method for solving road load under the condition of missing road load information was studied.We conducted bench test validation analysis under typical operating conditions.The results show that under typical operating conditions,the relative error between the output speed torque obtained from the model solution and the test results on the test bench is less than 8%,which can achieve rapid and continuous dynamic simulation calculation of the integrated transmission output characteristics and various performance indicators.In order to study and analyze the influence of load changes on shift quality and maneuverability,the Control variates principle is used to change the performance degradation degree to reflect the load changes.The friction coefficients corresponding to different friction and wear stages of the wet shift clutch friction pair were used to characterize different wear levels.The influence of load changes on shift performance was studied,and it was found that as the wear level of the friction pair increased,the peak torque of the main shaft was less affected,and the acceleration time showed a non-linear change pattern;Three typical types of complete machine transmission efficiency,0.8,0.78,and 0.75,were selected to characterize different degrees of degradation.The impact of load changes on maneuverability was studied,and it was found that the higher the degradation degree of transmission efficiency,the greater the impact of rolling resistance coefficient on acceleration ability.When the transmission efficiency of the entire machine deteriorates to0.75 and the rolling resistance coefficient is about 0.124,the acceleration performance significantly weakens when the time from full throttle acceleration of 60km/h to maximum vehicle speed exceeds 20 seconds.To achieve real-time data transmission under time-varying working conditions,a special vehicle integrated transmission system load characteristic analysis and calculation platform was constructed based on MATLAB App Designer.By utilizing remote data communication methods,using TCP/IP,HTTP communication protocols,and My SQL cloud database to achieve real-time data transmission,the technical problem of data being continuously transmitted from real vehicle or test bench sensors to physical models for solution calculation has been preliminarily solved.The platform includes specific and timevarying working condition calculation modules,providing support for real-time monitoring,dynamic control,and intelligent operation and maintenance of the service status of the special vehicle integrated transmission system. |
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