| Different trajectory planning methods are needed in different applications,and the traditional trajectory planning methods for industrial robots may not be suitable for the rail type photography robot.Therefore,this paper aims at developing a set of trajectory planning algorithm which is suitable for the rail type photography robot,and does the following research work:(1)The user requirements are analyzed,and the research emphasis of this paper is established: Constructing G2 continuous Cartesian space trajectories The structure analysis of the rail type photography robot with completely independent property rights is analyzed,and the physical significance of the Zoom and Focus related to the camera shooting technique is analyzed,which is virtualized into two motion pairs to construct a virtual 6-DOF PPRRPR robot.The robot's DH parameters are obtained by using the improved DH method to analyze the robot.Then,the formulas of its forward kinematics and inverse kinematics are deduced,and the inverse solution of the robot is found to be a unique analytical solution.(2)A Cartesian spatial position trajectory planning algorithm is established.Considering the point-to-point motion mode of the robot,after deriving the construction equations of three-dimensional space uniform line and arc path,the golden ratio interpolation method and the polyline approximation interpolation are constructed respectively with time t as the variable of the interpolation algorithm.The clothoid,which is commonly used in highway design,is introduced as the transition curve of trajectory planning for the first time.To this end,the coordinate transformation method is used to transform the three-dimensional space problem into two-dimensional space for solution.The point coordinate formula is derived from the basic formula and geometric characteristics of the clothoid curve,and its general clothoid equation is derived from its basic characteristics and pure mathematical integration methods.The connection forms are divided into three categories: straight lines to straight lines,straight lines to circular arcs,and circular arcs to circular arcs.After analyzing the similarities and differences between the previous research work and the problems to be solved in this paper,the connection algorithm suitable for the characteristics of this paper is constructed from the perspective of geometry and pure mathematics.Finally,a set of Cartesian space trajectory planning algorithms with G2 continuous curvatures is constructed.(3)The Cartesian space attitude trajectory planning method is proposed.The various attitude description methods are compared.Finally,the axial angle method is selected as the attitude input method of the human-computer interaction terminal,and the unit quaternion is selected as the method of attitude trajectory planning.Inspired by studying the relationship between quaternion and rotation and the camera attitude change method on the pan / tilt,the evaluation method of quaternion interpolation algorithm based on the locus of unit sphere is constructed,which makes the interpolation result more concrete and takes the motion of joint space into account.This method is used to evaluate three common unit quaternion interpolation algorithms.Finally,the spherical quadrilateral interpolation algorithm(squad)is selected as the algorithm to construct Cartesian space attitude trajectory.Finally,in order to verify the feasibility of the Cartesian space trajectory planning algorithm in robot control,a set of feasibility experiments are designed for position and attitude respectively.Firstly,the key nodes of interpolation are obtained by simulation in MATLAB and then imported into the robot control system,which controls the robot to run according to the predetermined trajectory.The feasibility of the algorithm is verified by simulation and experiment. |
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