| With the rapid development of China's nuclear power,wind power and offshore oil and natural gas exploration,the in-service regular inspection and analysis of the performance of key components of underwater large equipment has gradually become a research hotspot.Due to the harsh Marine and nuclear power environment,non-destructive testing is difficult and dangerous,and is recognized as a technical problem.In this paper,in order to improve the efficiency of NDT for key underwater components and reduce the operational risk,an underwater NDT manipulator is developed,and theoretical analysis,simulation and experimental research are carried out on kinematics,dynamics and control strategies that have a great impact on the operational performance of the manipulator.In this paper,a lightweight and modular robot joint structure based on frameless torque motor and harmonic reducer is proposed based on the research of underwater NDT manipulator.The overall structure of the manipulator is composed of highly integrated modular joints and light connecting rods.The connection is simple and reliable,which can be quickly assembled and disassembled for fault maintenance and quick layout.The kinematics forward and inverse solutions of typical manipulator are solved and verified by MATLAB program.Aiming at the modeling and analysis of the dynamics of the working mechanical arm in onshore and underwater environments,ADAMS simulation verified that the dynamics model was correct,and MATLAB program was written to verify that the motor reducer selection met the design requirements.In order to meet the requirements of underwater comprehensive nondestructive testing(NDT),a semi-autonomous remote control strategy based on master-slave control obstacle avoidance and off-line trajectory planning detection is studied.The forward kinematics of the remote control main arm is analyzed,and the motion space of the main and slave manipulator is simulated by monte carlo method.The position and attitude planning of the working mechanical arm are carried out through the s-shaped curve velocity planning,so that the track speed and acceleration are smooth and continuous,and the motion is stable to reduce the impact on the motor.In order to complete the tasks of high precision,high reliability and high efficiency of underwater NDT,a distributed real-time control system based on EtherCAT bus was proposed in this paper.Which has characteristics of strong coupling nonlinear operation manipulator trajectory tracking control are studied,advantages and disadvantages of the decentralized and centralized control schemes are analyzed,and considering the underwater work environment,design the fuzzy PID control strategy based on equivalent gravity compensation,and through constructing MATLAB/Simulink model simulation,proved this method can improve the dynamic responses of the joints,improve the trajectory tracking precision.In order to make the operator more intuitive control of mechanical arm,efficient detection task,in this paper,based on the LabView platform,the idea of modular programming PC simulation interactive control program was designed and developed to realize the offline operation arm motion simulation and on-line state monitoring,single joint control,offline trajectory programming,master-slave telecontrol,etc.The experimental platform was built and the off-line trajectory planning writing experiment was carried out to verify that the trajectory planning algorithm moved smoothly and the gravity feedforward control strategy could improve the trajectory tracking accuracy.The master-slave control following experiment is carried out,and it is proved that the master-slave remote control strategy can make the slave arm follow the master arm in accordance with the mapping requirements. |
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