| At present, the domestic and international shipbuilding industries are restricted by the large surface and the poor uniformity of hull block. The spraying of hull block is still used in the traditional manual work whose spraying efficiency is low and quality stability of spraying is poor. This resulted in a high rate of return to the surface of the hull, which severely restricted the productivity. At the same time, the operation environment is bad, and the workers are injured. Based on the national science and technology support project "Development of the complete equipment for the automatic spraying of super large block", this paper has developed a kind of lightweight spraying manipulator system which is mounted on the platform of the hydraulic boom to complete the automatic spraying of the surface of hull. This is used to solve the problems of the low efficiency of coating, the unstable coating quality and so on. In this paper, the structure design of spraying robot arm, kinematics and dynamics analysis, spraying algorithm of coating optimization and control system and other key technologies are also carried out.Firstly, according to the performance index of spraying and the the characteristics of the load platform of hydraulic boom, a lightweight spraying manipulator arm which can be mounted on the hydraulic arm has been developed. Based on the structure optimization, the parameters of robot arm are designed to achieve the maximum efficiency of working space. Each joint of the robot arm is arranged in the way of coaxial arrangement of the coder, the motor and the reducer, wrist uses the design of skew wrist with three-degrees freedom. The wrist motor focuses on elbow joint. The whole robot arm has the characteristics of compact structure and flexible movement. In order to ensure that the robot arm is e asy to install on the hydraulic arm, the two interface modules are designed. And according to the working environment of the robot arm, the corresponding treatments of explosion proof are carried out.Then, the kinematics and dynamics of the manipulator are analyzed. Solving the forward kinematics of the robot arm which is based on the DH parameter method; solving the inverse kinematics of the robot arm based on the ergodic iteration method. According to the transformation relation of coordinate system, using the Jacobian matrix to establish the relationship between the end of the robot arm and the velocity and acceleration of each joint, and then to calculate the motion space of the robot arm. With the aid of ADAMS software, the dynamic simulation of the robot arm is carried out, and the required torque of each joint in the limit state is analyzed.Secondly, based on the optimization algorithm of coating uniformity, the optimal spraying velocity and the distance between the robot arm and the trajectory are analyzed. Take the coating thickness as the output of the equation, the mathematical model of accumulation rate and that of accumulated thickness of plane and curved surface coating were established. On the basis of this, take the variance of the actual coating thickness and the ideal coating thickness as the objective optimization function to optimize the spraying velocity and the spraying distance. So that the uniformity of the coating thickness is guaranteed.Finally, based on the fast response and the short development time, we can configure driver and controller, and build robot control hardware system. Based on VC++6.0 and Open Inventor, the control interface of the upper monitor has been developed, and the trajectory control of the robot arm in the con troller has been realized. The laser tracker had been used to do the kinematics parameter calibration of manipulator and its main performance test, and then the results has showed that the spraying manipulator which had been processed and assembled meets t he design requirements. A simulation of the hull block has been built, and the spraying experiment has been carried out with the hydraulic boom. |
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