Research On Polishing Of Free-form Surface With Torus Tool

1.IntroductionIn the research of robot control technology, it has a core conflict. Namely when robot contact special operation environment, between require produce the complaisance of random force and require robot toward position precision and structure firm. It is called complaisance that robot can compliant the contact environment, and the research of this problem is called the research of compliant control. The technology of robot compliant control, is the forward of cross subject between theory of modern control and the technology of automated manufacturing, it is always one of the difficulty of the area of automation, and the text establish the foundation in order to further research the theory of compliant control. The text take the control of polishing force as the object, integrate a series of advance technology of the application of robot technology, compliant control technology, modern control theory, modern mathematics, NC technology. Study the computational method of position and gesture when roborts polishing for free-form surface,and study the movement planning method for polishing tool and the control of polishing force. Builds a foundation of the computational method of position and gesture and the control of polishing force when roborts polishing for free-form surface,Resolve the problem of implantation of standard NC of robot's compliant control in free-form surface.2.Robot Flexibility Polishing ToolThe text develop a flexibility polishing tool using by robot, it can self-determination fit the the outline of big scale free-form by itself, it can separate the normal pressure, tangent displacement, tangent angle in the process of polishing, correct tangent angle yaw the by itself, and the top of polishing tool has the specialty of no velocity dead-center. The sketch figure of flexibility polishing tool and the practicality image are shown as figure 1,figure 2.As figure 1 shown the flexibility polishing tool mainly composed by 1.upper fixation connection board, 2. flexibility adaptable body, 3.Electrical Motor, 4. lower fixation connection board, 5.ring polishing tool and other correlation connection parts.The process of polishing sketch is shown as follow. control the position and gesture of robot, make tool axis vector of polishing tool and normal of the surface of workpiece to be machined superposition, and make the polishing tool contact the surface of workpiece to be machined with definite pressure, the polishing tool adjust the ring top to adapt the outline of the surface of workpiece to be machined by its flexibility adaptable body, in the process of machining, via PC control robot adjust the position and gesture of the bottom of robot, to ensure the pressure between polishing tool and workpiece invariableness, and the electrical motor drive the ring top circumrotate at the meantime to make the machining of the workpiece surface.3.Research on the Computational Method of the Position and Gesture of the Polishing Tool(1)Modeling of toolsFirstly, establish equation of the torus polishing tool,the equation shown as formula(1), and simulation model shown as figure 4. (2) The transition matrix from tool coordinate to workpiece coordinate the transition matrix of the tool move to workpiece coordinate shown as formula(2)(3)The computational method and simulation of the tours tool's position and gestureUsing the simulation of sphere workpiece and ellipse workpiece validate the the computational method.Under knowing the condition of processing point, establish the mutual relation of the point of tool and this point.using matlab optimization method work out the optimization position and gesture of this point,then simulate the position and gesture of that time.The level of simulative error is e-6mm,so we can ignore it.The final simulative result shown as figure 5 and figure 6. The final simulative result indicate that the tool can move to artifactitious point according to the computational position and gesture .(4)Experimental research on the position and gesture computational method of tours tool Using three-coordinate metrical apparatus measure the point date of workpiece's generatrix. Do polynomial fitting of curve by the date of workpiece's generatrix ,then gained workpiece's generatrix equation,by software of proE establish workpiece model,then import model into MasterCAM software .Putting the date of workpiece model into equations gained five parameters. The polishing tool lastly gets to the process position through the calculated arthrosis variable. Figure 7 shows the experiment result,which indicates that the calculated arthrosis variable can make polishing tool get to the given position and gesture.4.The Movement Planning Method and the Complaisant Force Control of Robort Polishing for Free-form Surface(1) Studies the Movement Planning Method for Polishing Toolthis dissertation studies the movement planning method for polishing tool, introduces the principle and characteristics of both transverse movement planning method and longitudinal movement planning method systematically, demonstrates that, transverse movement planning makes polishing tool move in a 3-D space of two line movements and a writhe movement, longitudinal movement planning makes polishing tool move in a 2-D space of one line movements and a writhe movement, so longitudinal movement planning needs less number of degree of freedom and is much easier to avoid movement intervention and mechanic singularity, and then, reaches the conclusion that the performance of longitudinal movement planning method is better than that of transverse movement planning method in polishing free-form surfaces by robot.(2)Studies the Complaisant Force Control for Tool Polishing for Free-form SurfaceBy analyzing the structure and rigidity of polishing robot system, the elastic distortion of this robot polishing system is thought to concentrate on the elastic polishing tool, and the passive distortion structure is constructed for force control in the robot polishing system. With the appropriate rigidity matrix of the robot polishing system, this dissertation studies the relationship between polishing force and position warp, constitutes the polishing robot force control system with the passive distortion structure by improving the position accuracy under the restrict condition on the force sign feedback, completes a new robot force control method on the basis of the passive distortion structure, in which the force between polishing tool and work-piece is considered as the information resource for the position warp of polishing robot under the restrict condition, and then a track compensator and a self-collected compensator are designed for the polishing robot force control under the self-collected and trackable qualification of the controlled system. this robot polishing system can essentially eliminates the influences that are caused by the curvature radius of free-form surfaces and obtain the consistency of both the degree of roughness and the depth of material removal by force controlling on the passive distortion structure.5.conclusionThis paper aims at robot torus polishing tool processing system,based on using torus flexibility polishing equipment,analyses one computational method of position and gesture,puts forward robot active-passive structure force compliant control policy,and does simulation and experiment for polishing force,emphasizely researches the problems on compliant control of robot polishing process.