Design And Implementation Of The Offline Programming System For Seven-axis Grinding Manipulator

The application of industrial manipulators liberated people from tedious and repetitive work,which greatly improved the production efficiency.In some complex industrial applications,the traditional six-axis tandem manipulator has been replaced by a more flexible seven-axis manipulator.At the same time,the redundant degree of freedom brings certain difficulties to the control and trajectory planning of seven-axis manipulator.Its offline programming symstem can't meet several demands and do not open to the user.In order to use seven-axis manipulator for operation easily,this paper took a typical 7-axis manipulator as research object,designed and implemented a offline programming system for grinding task,the main work is as follows:Firstly,the demand analysis of the offline programming system of manipulator is carried out,and draw a conclusion that the designed system needs to be independent,simple,easy to use,interface friendly and expandable.So the system is divided into 3d modeling,offline teaching,motion control,3d simulation,file management,system output and software interface these seven modules.Considering the requirements and development cost,this paper chose VS2013 with open source graphics library Open GL and open source interface library Qt as development platform.Secondly,the kinematic modeling of a typical seven-axis tandem manipulator is performed in this paper.The establishment of its linkage coordinate system and its forward kinematics solution are completed.As for the difficult inverse kinematics problem,the algebraic solution using the virtual method of joint variable and the numerical solution using BP neural network are adopted respectively.Among them,genetic algorithm is also used to optimize the initial weights and thresholds of the BP neural network to reduce the test error and the number of network iterations.The forward kinematics solution is also used to solve the robot's workspace with the Monte Carlo method.Then,the trajectory planning method based on polynomial interpol ation and cubic spline interpolation in joint coordinate is discussed.The mathematical expressions of the joint angle function constructed by using cubic polynomials,high-degree polynomials and cubic spline functions are derived by taking velocity and acceleration of joint in middle path point as constraints.After the verification and simulation,the cubic spline trajectory planning method result in a smoother trajectory was selected.Finally,implementation process of the core functions in the offline p rogramming system software is represented.Using Open GL to complete the visualization of the workpiece and the manipulator body.The surface topological information of the workpiece has a significant effect on the generation of the grinding path,this part also completed an STL file browser for extracting the information.By using the extracted surface topology information of the workpiece to generate the middle path point of the grinding track,the offline motion demonstration of the manipulator is realize d in a frame-by-frame playback method.At the same time,the interface of the offline programming system software was designed,and other processes such as system communication,teaching reproduction,and file output were briefly described.