The Study On Kinematics And Dynamics And Error Analysis Of Automatic Merging System Of Ship Block

During the shipbuilding stage,the assembly of ship block is an important procedure which has great influence on shipbuilding accuracy.At present,the assembly of ship block is mainly accomplished by adjusting the position of ship block with the crane or marine railway car.Both of the above methods have the disadvantages of low accuracy and low efficiency.Based on the above background,in this paper,we will study the automatic merging system based on the split-type assembly equipment.The split-type assembly equipment studied in this paper can realize the movement in three directions: transverse,longitudinal and vertical.Three or more three-dimensional adjustable piers cooperate with each other can adjust the position and posture of ship block.The main contents of this paper are as follows.(1)Building automatic merging system of ship block,the system consists of several adjustable piers,measuring unit,data processing unit and motion control unit.In the system,the three-dimensional adjustable piers are responsible for supporting and moving ship block,the measuring unit is responsible for measuring the coordinates of block datum points,the data processing unit is responsible for calculating the position and posture of ship block,the motion control unit is responsible for controlling the motion of the three-dimensional adjustable piers.(2)This paper introduces the description method of space position and posture of rigid body and the transformation principle of coordinate system,studies the methods of position and posture calculation of ship block,motion planning of ship block and the solution of adjustable piers’ inverse kinematics solution and proposes two automatic merging methods based on two-step adjustment method.(3)The model of ship block and the adjustable pier are constructed by CATIA.Kinematics simulation of automatic merging system of ship block based ADAMS verifies the feasibility of the methods of the position and posture calculation and motion planning.The dynamic model of the system is established based on Newton Euler method.Dynamics simulation of the system under non-redundant driving and redundant driving conditions is carried out respectively.Comparing the simulation results in two cases,we can get that redundant driver is more superior in improving system performance.In the research of system control method,the PID control based on joint space and the hybrid control of force and position are proposed.(4)The model test of three-dimensional adjustable pier is carried out and its motion error is analyzed.The precise control of model speed can be realized by using the PVT function of motion control card.The comparison between model test and simulation results shows that the system is feasible in motion control function.An error compensation method based on open-loop system and an error compensation method combining open-loop compensation with closed-loop feedback are proposed for model test and engineering practice respectively.