Research On Multi-objective Trajectory Optimization And Control Of Electro-hydraulic Robot

With the vigorous development of economy,robots have become one of the key fields to promote the development of industrial structure.Heavy-duty robots with electro-hydraulic robots as the core have irreplaceable advantages in construction,mining,handling and other fields.Therefore,the future development of electro-hydraulic robots has huge space,and the research on electro-hydraulic robot should be more investment.In this paper,the self-developed 6-DOF electro-hydraulic robot is taken as an object of study,focusing on basic work such as multi-objective optimization of joint trajectory and control algorithm of hydraulic drive system.Firstly,the mechanical structure of the electro-hydraulic robot is elaborated in detail.Based on the research of forward kinematics,and in view of the local controllability of B-spline curve,the quintic B-spline curve is used to plan the trajectory of the electro-hydraulic robot in its joint space.Under the condition of kinematics constraints,three objective functions,time-energy-jerk,are proposed.The joint trajectory is optimized by using the non-dominant neighborhood immune genetic multi-objective algorithm,and uniformly distributed Pareto-front is obtained.The optimized joint velocity and acceleration curves of the electro-hydraulic robot are relatively smooth.Secondly,according to the principle of hydraulic system of electro-hydraulic robot,the mathematical model of the system is obtained.The simulation model of single joint hydraulic system is established in Simulink software.With the optimized joint trajectory as the ideal input,the fuzzy-PID controller of the system is designed by using the Fuzzy Toolbox in MATLAB.The simulation results show that the fuzzy-PID algorithm has better effect on the hydraulic system of the electro-hydraulic robot.According to the conditions of the experiment,the simulation flow output curve under the control system is obtained.Finally,an electro-hydraulic robot experimental platform is built to detect the flow changes in the hydraulic system of the electro-hydraulic robot under different loads.The flow data collected by the experiment are fitted,and compared and analyzed with the simulated flow data.The experimental results show that the trend of the experimental data curve is basically the same as that of the simulated data curve.Further analysis shows that the velocity curve of electro-hydraulic robot joint is continuous and the jerk is small.