Research On Trajectory Planning Of Hydraulic Manipulator Considering Joint Flexibility

At present,the driving joints of the traditional mechanical arm mostly adopt the combination of the motor and the reducer,so that the weight ratio(ie,the ratio of load to self-weight)and the power-to-volume ratio of the conventional mechanical arm are very small,and the load-to-weight ratio is one of the most important indicators to measure the performance of industrial robots.In response to this problem,a six-degrees-of-freedom hydraulic manipulator based on rotary vane actuator(RVA)joint is designed.The greatest advantage of this manipulator is its higher weight ratio.The main research contents include the following three aspects:(1)Taking the designed hydraulic manipulator as the research object,the mathematical model is established.First,the mathematical theoretical basis needed for the modeling of the manipulator is described.Then,the kinematics modeling and kinematics equation of the hydraulic manipulator are performed by the modified D-H method.Finally,the trajectory planning of the hydraulic manipulator is simulated by MATLAB,the characteristic curve of each joint angle is obtained.(2)On the basis of rigid kinematics,considering the joint flexibility,the kinematics model of the flexible joint manipulator is established,and the error distribution of the end effector of the hydraulic manipulator under the joint flexibility is obtained.The working space of the designed hydraulic manipulator is solved by Monte Carlo method,and the working space cloud diagram of the hydraulic manipulator is drawn in MATLAB.(3)Considering the joint flexibility,find the optimal joint rotation angle error when the end effector position error is the smallest,and compensate the rotation angle error.The cubic triangular Bezier spline is used to plan the trajectory in the joint space,which ensures the smooth line and continuity of the joint motion parameter curves.At the same time,the problem of joint angular acceleration mutation is solved by increasing the order of the cubic triangular Bezier spline curve.,and verify its rationality through simulation.In addition,trajectory planning is performed in Cartesian space,and the interpolation equations of linear trajectory planning and the interpolation equations of circular trajectory planning are solved.