Research On Vibration Suppression Of Truck With Hydraulic Manipulator’s Luffing System

With the development of science,technology and economy,large hydraulic mechanical manipulator plays an irreplaceable role in transportation and loading,forestry transportation,municipal construction,rescue and disaster prevention,construction and Marine test.Market demand and market holding are constantly increasing.At present,the mechanical manipulator industry is developing towards to unmanned and information-based.Many countries are promoting the automatic transformation of excavators,hydraulic mechanical manipulator and other large construction machinery.With the proposal of China smart manufacturing 2025 and the arrival of industry 4.0,China is also actively stepping into the research and development team.But there are many obstacles in the way of achieving this goal.For example,as the hydraulic manipulator,the vibration of the end of the manipulator is the key factor that affects whether the manipulator can successfully complete the automatic grasping task.Meanwhile serious safety accidents will occur if the mechanical manipulator vibrates heavily.Therefore,it is necessary to solve the vibration problem of hydraulic manipulator.This paper is aimed at the vibration problem of the hydraulic manipulator in the process of grasping,carrying and unloading the cargo,starting from two aspects of the problem,one inside and one outside,to solve this problem.The inside aspect refers to the main driving mode from the hydraulic manipulator-hydraulic system.Suppress and eliminate the vibration problem of hydraulic manipulator caused by the phenomenon of creeping and jumping when the hydraulic cylinder is extended or withdrawn due to pressure instability from the power source.The hydraulic system solves the low frequency vibration of the piston rod of the hydraulic cylinder when the hydraulic cylinder of the mechanical manipulator moves,especially when the piston rod of the hydraulic cylinder drops with load.However,considering that during the process of moving the cargo(with load)to the designated position of unloading when the manipulator grabs the cargo(with load),which will cause the global vibration of the cargo and the mechanical manipulator and affect the stability of the whole system.Therefore,a good velocity and trajectory planning method is necessary to improve the stability of the manipulator.Therefore,the velocity smoothing technique using in NC machine tool,acceleration control method,is introduced into the trajectory planning of manipulator.A two-stage adaptive acceleration and deceleration control method is proposed.With the help of motion velocity and trajectory planning to solve the vibration problem of hydraulic manipulator further,which is the outside solution..The main research contents of this paper include:(1)This paper summarizes the problems existing in large hydraulic manipulator and the solutions to the problems related to the vibration of hydraulic manipulator,through searching and reading a large number of domestic and foreign literature.The problems in some existing methods are also pointed out.(2)Firstly,the components of the hydraulic manipulator are introduced.The important position of the luffing system in the whole hydraulic manipulator hydraulic system is explained.The stability analysis of the hydraulic system with balancing valve is carried out.The inner cavity,channel and hole of the balance valve body are modeled mathematically,which is the key step to this paper.The key factors that affect the stability of the system are found by analyzing the dynamic characteristics of the problem condition hydraulic system.And this provides a strong theoretical basis for the subsequent optimization of hydraulic system.(3)The parametric modeling of the balancing valve and the lube loop of the balancing valve is carried out according to the problem condition by using the software of AMEsim.The simulation of the problem condition is repeated and the hydraulic damping network is introduced according to the optimization theory.With the help of the optimization method of NLPQL,the parameters of hydraulic damping network and balancing valve are optimized,which leads the luffing system of the hydraulic manipulator to achieve the optimal parameter configuration.(4)Kinematic modeling is carried out with the hydraulic manipulator as the object by using the method of D-H parameter.And the positive and negative solutions of its kinematics are found out.A two-stage adaptive acceleration and deceleration control method is proposed to smooth the motion velocity and to plan the trajectory of the hydraulic manipulator.And then the method is taken to MATLAB toolbox for simulation verification.(5)According to the research subject of the hydraulic manipulator,the corresponding sensors are selected,the experimental platform is built,and the experimental research on vibration suppression of the hydraulic manipulator is carried out.The feasibility of the optimization and improvement theory above is verified through the collected data,the experimental results and the comparison result of the experiment and the simulation.