Research On Multi-constraint Synchronous Motion Trajectory Planning For Dual-robot Cooperative Mirror Machining Of Complex Surface Components

Mirror machining is an effective means to realize high-quality machining of large thinwalled components such as aircraft skin and aviation transparency.When conventional CNC machine tools are used to machine the internal and external profiles of large thin-walled parts,it often needs to be reversed twice,which leads to the increase of machining error and the decrease of machining efficiency.Therefore,in this paper,a cooperative mirror machining scheme of dual robots for cutting the internal and external profiles of complex curved surface components simultaneously is proposed.Because the stiffness of industrial robots is posedependent and anisotropic,mirror machining requires maximum stiffness matching and adaptive synchronous motion.Therefore,this paper proposes a synchronous motion trajectory planning algorithm based on stiffness matching pose determination of dual robots in cooperative mirror machining,which meets the stiffness matching requirements of two robots in mirror machining and significantly improves the efficiency of mirror machining.The main research contents of this paper are as follows:(1)The stiffness matching optimization model of dual-robot cooperative mirror machining is established.Firstly,the normal synchronous mapping relationship of the corresponding points on the double spline tool path is derived,which is used as the geometric constraint condition to ensure the synchronous motion of the double tools.Then,an evaluation index of robot stiffness along the normal direction of the surface is given,and the constraint conditions for matching the stiffness of dual robots in mirror machining are established.Through dichotomy,the set of stiffness matching points at each corresponding point pair is obtained,and the rigid matching posture of dual robots with continuous joint paths is obtained by a one-way search method.The optimized posture of dual robots not only meets the requirements of stiffness matching,but also improves the overall stiffness of the robot on the machining path.(2)A linear synchronous trajectory planning algorithm for dual-robot cooperative mirror machining is proposed.On the premise of the stiffness matching results of dual-robot cooperative mirror machining,the geometric constraints between dual tool paths are transformed into motion constraints between dual tools,and a time optimal synchronous motion trajectory planning model with jerk and synchronous motion constraints is established.In order to further accelerate the process of solving the nonlinear model,the linear relationship between the constraint and the square of the tool speed is constructed,and the accurate expression of the synchronous motion trajectory curve is obtained by using the linear programming algorithm.On the premise of maintaining the cutting performance of the tool,the algorithm significantly improves the efficiency of dual robot cooperative mirror machining.(3)The simulation and machining experiments are carried out.In this paper,the synchronous motion planning algorithm of dual-robot cooperative mirror machining based on stiffness matching pose determination is simulated in MATLAB software,and cutting experiments are carried out on the platform of dual-robot cooperative mirror machining.The simulation and experimental results show that the overall stiffness of the robot is effectively improved and the mirror machining time is greatly reduced on the premise of satisfying the stiffness matching,which verifies the feasibility of the algorithm proposed in this paper in engineering application.