Research On Kinematic Reliability Of Industrial Robot

Robot plays a very important role in the field of mechanical intelligence.It is widely used in automobiles,electronic appliances,construction machinery and other industries,as it has advantages of high safety coefficient,strong versatility,high production efficiency and strong durability.In general,the repeatability accuracy of industrial robot is generally higher,and the absolute positioning accuracy of it is generally lower.The lower absolute positioning accuracy cannot meet the needs of modern manufacturing.However,Factors affecting the kinematic accuracy of the robot are usually uncertain.For this reason,the kinematics modeling and analysis of the robot is carried out under uncertainty in this paper,which provides an effective method for improving the kinematic accuracy of the robot.The main research contents are as follows:1.The forward kinematics analysis of the robot is performed according to the D-H modeling method.The mathematical expression of the generalized coordinates of the position and posture of the robot end-effector is thus deduced.According to the differential theory,its error model of position and posture is established,and the error transfer coefficients in the model are derived.Taking the Stanford robot as an example,the position,posture and kinematic error of the robot under a given kinematic law was analyzed.2.Considering the uncertainty of joint parameters,the kinematic accuracy reliability analysis of robot is carried out.For the system of the robot,this paper focuses on the position accuracy of the end effector.Concerning the randomness of parameters of each joint and based on the position and posture error model of the robot,point(static)reliability model of endeffector position accuracy,analysis model of time-dependent(interval)reliability and system kinematic reliability model of the robot are all proposed.The First Order and Second Moment method(FOSM)and the envelope method are used to solve the point reliability and timedependent(interval)reliability,respectively.Finally,the point reliability,interval reliability and system reliability of the robot are obtained by computational examples.3.Considering the joint clearance,the kinematic accuracy reliability analysis of robot is carried out.Assumes that the axis in the joint of the robot is parallel to the axis of the shaft hole and simplifies it to a flat two-dimensional vector,the joint clearance vector is simplified as a flat two-dimensional vector,and the statistical correlation of the joint clearance variables is processed by the Cut-Hybrid Dimension Reduction Method(Cut-HDRM).On this basis,the probability model of position kinematic error of robot with joint clearance and kinematic accuracy time-dependent reliability model of robot is established.The FOSM method and the envelope method are used to solve the kinematic accuracy reliability of the robot with joint clearance respectively.The point reliability and the time-dependent reliability of the robot are obtained.