| Multi-DOF electro-hydraulic servo manipulator is widely used in nuclear power,petrochemical,metallurgy,casting and other industries because of its high driving power density,heavy-load(over 1 ton),high-temperature.high-pressure and corrosion-resistant characteristics.However,it’s motion control is involved in the kinematics and dynamic characteristics,the nonlinear characteristics of the electro-hydraulic servo system,the positioning feedback control characteristics,the smooth of the motion curve,and energy consumption characteristics,so the motion is not easy to detect and compensate.How to effectively improve the precision,the stability and high-speed of motion control will become one of the problems to be solved urgently.Taking 3DOF hydraulic manipulator for research objects,this study manly carried out and completed those work as follow.(1)Aiming at the trajectory planning issue,this paper made a closed-chain vector model of hydraulic manipulator firstly,which show the spatial relationship between the TCP and the output displacement of hydraulic actuator.And then,the motion trajectory of manipulator in joint space was constructed based on 5-order B-spline curve.The trajectory function of main joint was also deduced based on the continuity property of the interpolation function.Otherwise,the improved PSO and time optimal planning method was used to optimize the trajectory.At last,the effectiveness of the proposed trajectory planning method is verified by simulation calculation.(2)Aiming at the control problem of push&pull and pitch system,this research established the mathematical model of single and dual asymmetrical valve controlled cylinder based on classical electro-hydraulic servo theory.And then,the motion control method of push&pull system was put forward by using fuzzy-PID controller.And the control method of pitch system was also proposed by using NDI theory.At last,it is verified that the proposed control method has better tracking and synchronous performance by comparing with the results of simulation calculation of classical PID.(3)Aiming at the control problem of rotating system,this study presented a mathematical model of dual-motor rotating and gear meshing based on the theory of elastic dynamics and nonlinear valve controlled hydraulic motor.And then,the motion control method was proposed by using IL control theory.At last,it is also verified that the proposed control method has better tracking and synchronous performance by comparing with the results of simulation calculation of classical PID.(4)Finally,the practical application of manipulator motion control was discussed.First of all,the experimental system of 3DOF hydraulic servo manipulator is set up.Then,aiming at the application of actuator motion control,the experiment of motion control was carried out and compared with the simulation results in push&pull,pitch and rotating system.The results verified the effectiveness of the proposed algorithm.At last,aiming at the application of trajectory planning,the experiment of TCP trajectory was carried out and compared with the simulation results.The effectiveness of the proposed method is also verified.The experimental results of practical application showed that the absolute error was less than 2.5mm between the actual tool center point(TCP)trajectory and the desired trajectory.In this paper,the trajectory of the manipulator is relatively smooth,which is beneficial to the manipulator control,and the algorithm has practical value. |
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