Research And Design Of The Adaptive Electro-hydraulic Hitch System For Hilly Mountain Tractor

Electro-hydraulic hitch system has been widely used recent years.The inferior slope adaptability of Electro-hydraulic Hitch System is gradually realized for hilly mountain tractor.Adaptive electro-hydraulic hitch system is designed to solve the problem above by improving the electro-hydraulic hitch system.Function of roll angle adjustment is added to make the hitch have slope adaptability compared to the conventional electro-hydraulic hitch system.Overall scheme of adaptive electro-hydraulic hitch system,which have two degrees of freedom,is designed to meet the requirement of tillage in the hilly mountain.And key parameters of hitch rods and key hydraulic system components are also designed.In order to formulate the effective control strategy,mechanical hydraulic system model is established in the AMESim platform to conduct kinematics and dynamics simulation analysis.Dynamic characteristics of mechanical hydraulic system in the up-down condition and slope adaptive condition is achieved.The control strategy is proposed,which the roll angle is adapted by actual slope angle and tillage depth is adjusted according to force and position sensor signal.The ideal roll angle prediction method is proposed.The method reflects the time-delay effects when tractors are working.Further,mathematical expression is derived in theory.Then ideal roll angle is tracked by fuzzy control algorithm.Slope angle and actual pavement spectrum is used as model input signal and control algorithm is simulated in the Matlab/Simulink to verify the effects of control strategy.The results show that the control strategy could control horizontal fluctuation below 10 mm,which proves that the requirement of tractor slope tillage could be met.Finally,design and manufacturing of adaptive electrohydraulic hitch controller,which includes software and hardware,are completed.To verify the actual control effects further,test bench of adaptive electro-hydraulic hitch system is designed and set up and then experiment under the slope step condition is conducted to verify its slope adaptability.The results show that slope adaptive electro-hydraulic hitch could track the slope signal effectively and actual horizontal fluctuation can be controlled below 10 mm.