Research On Geometrical Parameters Calibration And Assisted Force Of Direct Teaching Robot

Contemporary industry is booming,as well as the industry of industrial robots.With the maturity and perfect technology of industrial robots,the demand for industrial robots is becoming more and more demanding.To meet the actual demand of industrial production,the robot is required to run a complex trajectory.Direct teaching technology can greatly improve the efficiency of programming of teaching trajectory.At the same time,there is no need for the operator to master the robot technology and experience.Therefore,it is very important for the study of direct teaching technology.The general industrial robots are so heavy that operators are unable to teach flexibly and accurately.Then the key to the direct teaching technique is the force assistance of the joints of the robot.So that the instructor's instruction operation is flexible.Firstly,the design scheme of direct teaching assistance is established in this thesis.In order to study the robot direct teaching force system,the kinematics and dynamics of the robot are analyzed.The kinematics and dynamics model of the robot are established.In order to make the dynamics model of the robot and positioning accuracy more precise,the kinematics parameters of the robot are calibrated.The simulation of the dynamics model is carried out and the ADAMS software is used to verify it.For the kinematics modeling of the robot,the DH coordinate system is used to establish the connecting rod transformation matrix of the general robot so that the change of the coordinate system between the connecting rods is easily described.Through the connecting rod transformation matrix,the robot's kinematics is solved.Then the inverse kinematics of the robot is solved with geometric and algebraic methods.The number of inverse kinematics of the robot is optimized to simplify the calculation which would make programming easier.For geometrical parameter calibration,the concept and principle of calibration are studied firstly,and then the simulation of geometric parameters calibration has been carried out for the nominal parameter model of the robot studied.The results show that the accuracy of DH parameters can be effectively improved by calibrating the geometrical parameters of the robot.The accuracy of kinematics model and dynamics model of the robot can also be improved.For the modeling of robot dynamics,the Newton Euler method is used to establish the dynamic equation.The parameters of the dynamic equation are identified from CAD model.Then the dynamic equations are calculated according to the dynamic parameters of the robot,and the relationship between the motion state of the robot and the joint torque is studied.Finally,the motion simulation of the dynamic model is carried out,and the torque curves of each joint are plotted.At last For the robot dynamics simulation system,a platform for dynamic simulation is set up.Using the software ADAMS,combined with the six joint robot model used in this thesis.The torque curve of the robot joints is drawn under the condition of the given robot motion state.Compared with the calculated kinetic models,it is found that the curve of torque coincide and the errors between them are small,and the established dynamic model is correct.It can provide theoretical basis for direct teaching assistance under torque control mode.