| The hydraulic manipulator is the most important operating mechanism of heavy-duty mobile/industrial robots,such as rescue and heavy load handling.The existing hydraulic heavy-duty manipulators are mainly the working arms of construction machinery and forest machinery,which have fewer degrees of freedom(DOF)and huge hand grasping structure,resulting in small accessible space and poor flexibility,unable to meet the needs of complex tasks on the rescue site.Besides,the traditional hydraulic manipulators are mainly to realize task function,the friction of its structure is large and the electro-hydraulic proportional drive system with centralized control has poor accuracy and high energy consumption,which can't meet the requirements of precise and efficient operation in emergency rescue,large industrial manufacturing,and other occasions.To solve these problems,this paper first designs a heavy-duty manipulator with high-reaching space,high flexibility,and high precision,and builds a prototype test platform for the heavy-duty hydraulic manipulator with 7+1 degrees of freedom and a 500 kg maximum load.Tests the function of each joint,and studies the high-precision 7-DOF redundant manipulator inverse kinematics solution method.Then,aiming at the problem that the existing energy-saving methods of the hydraulic manipulator are limited to "stop-loss",this paper reduces the load energy consumption by making full use of the self-motion characteristics of the redundant freedom manipulator,proposes to realize the energy optimization of the redundant freedom hydraulic manipulator from the angle of optimizing the movement,and uses the dynamic programming(DP)algorithm to optimize the problem.Finally,the energy-saving effect of the algorithm is verified by simulation.The main research contents of this paper include:1.Based on the requirements of high reachable space,high flexibility and high precision for rescue and other scenarios,the overall configuration of the manipulator,heavy-duty 2-DOF hand structure,compact hydraulic slip ring structure and hydraulic system are designed,the three-dimensional model of the manipulator and the three-dimensional model of the Hydraulic power station are designed,the test platform based on the physical prototype of the manipulator is built,and the function of each joint of the manipulator is tested.2.The forward kinematics model of the manipulator is established based on the Denavit-Hartenberg(D-H)method,the working space is determined by Monte Carlo method,the inverse kinematics of the manipulator is solved based on the gradient projection method with joint limits,and the inverse kinematics optimization algorithm based on the closed-loop is completed by using the real-time feedback tracking error,the algorithm is verified by simulation.3.It is proposed to optimize the energy of the redundant freedom hydraulic manipulator from optimizing the movement of the manipulator.To verify the feasibility of this method,the kinematics and dynamics of the 3-DOF redundant manipulator are analyzed.Aiming at two kinds of energy-saving hydraulic control systems: variable pump constant pressure(CP)and variable pump load sensing(LS)systems,the relationship between the multi joints "hydraulic-mechanism" is established.The global energy-saving optimization motion planning problem of the redundant hydraulic manipulator is described mathematically,and the problem is optimized by using the dynamic programming algorithm.4.In the CP system and the LS system,the motion planning method of the redundant hydraulic manipulator with the best global energy is calculated by example.To verify the energy-saving effect of the algorithm,the AMESim machine-liquid coupling accurate simulation model is established and compared with the gradient projection method and the minimize cylinder speed method. |
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