ApplicationResearchofFuzzyControlMethodsUsedinWeldingRobot英语毕业论文.docx

application research of fuzzy control methods used in welding robotabstract-in this research, it developed a main control program and a fuzzy distinguishing sub program based on the open operation system for users of the cloos welding robot. with the help of the fuzzy distinguishing sub program, the robot could automatically search the correctly welding seam start point and avoided wrong stopping because of none finding welding seam start point. after running the robot; moreover, the fuzzy distinguishing sub program could also distinguish components positive side or opposite side which would to be welded according to the input signal, and then automatically call the corresponding welding sub program of the component saved in the robot hard disk which had been taught program with the standard component to finish the welding tasks, which could greatly increase the production efficiency and intelligence of the robot. after finished the welding tasks, the control system could return the main control program automatically and prompt a message for another operation or new welding tasks.keywords-welding robot; fuzzy control; intelligent control; fuzzy distinguishingi. introductionwith the development of industry robot technology, welding robot and robot automatic welding technology are used in mechanical fields for metal components sewing and manufacture more and more. in order to satisfied different requirements of welding tasks, functions of welding robot control system are improved perfect more and more i, 2, such as intelligent control system 3, welding seam tracking technology 4, advanced adaptive capability 5. besides the above new functions, robot control system is designed more open for users to add different outside equipments, develop and expand functions of robot.but in fact, the assembly size errors of components are usually big enough to make robots difficult to find the correctly welding seams, which usually make the robot start at wrong point and weld wrong seams, therefore, how to improve the seam searching function of the robot and make it possibly find the correctly start points and seams to start weld becomes very important to acquire eligible components and increase production efficiency.in this research, it developed a fuzzy distinguish sub program by using the fuzzy control language and arithmetic based on the open control system of the cloos welding robot (show as figure i). when runs the fuzzy sub program and makes the torch of the robot contact with the component, a fuzzy signal will be input to the robot and read by the sub program, then the robot can automatically distinguish the positive side or opposite side of the component according to the fuzzy arithmetic, and then automatically call the corresponding welding program and finish the welding tasks of the component. with this fuzzy distinguishing sub program, it can greatly improve the intelligent of the welding robot.figure i welding robot station for connector of concrete pump truckii. develop of fuzzy control systema. hardware circuits designin order to develop the fuzzy control main program, firstly, it must design a hardware circuit which can read the different input signal and then help the robot to distinguish different sides of the component. where it used the initial welding point searching function of the robot opened for users, and the hardware circuit was designed as figure 2.figure 2 bloch diagram of initial welding position searching circuitin figure2, the robot will automatically use the torch to touch the component to be welded slightly, if the torch and the component contact with each other, the torch, component, and the robot will form a closed circuit, and the initial position searching hardware will read the input signal and the fuzzy distinguishing sub program will tell robot this is the positive side of the component and how to call the positive welding program. if not contact with each other, there will no signal input, and the fuzzy program will tell the robot this is the opposite side of the component and must call the corresponding opposite welding program to execute the welding tasks.in the hardware circuits designing, it uses the nozzle of the welding torch as an electrode and correctly connects with the hardware by a wire. in fact, the nozzle usually connects with the welding wire by the welding splash, which can easily damage other hardware circuits without any protection because of the big welding electric current. in order to avoid the above damage situation occur, a photoelectric isolation circuit is be designed as in figure 2. and the fuzzy distinguishing program can automatically open the isolation circuit and make the nozzle connect with the searching hardware circuits each other to prepare for reading distinguishing signal when the robot execute the fuzzy program to find the correct start point of the welding seam; otherwise, it will close the isolation circuit and turn off the nozzle connecting with the searching hardware circuits to avoid it being damaged by welding current while the robot executes welding tasks.b. software designthe distinguishing arithmetic of the fuzzy distinguishing sub program can be explained as figure 3.in figure 3, when the robot executes the welding program and runs to the order line of call distinguish sub program, there is some distance between the torch and the component, which likes there exists a virtual switch and the switch is initially opened. the working principle and the fuzzy arithmetic can be described as: when setup the standard welding program in teach program mode with the teach screen panel, it first call the initial position searching program, set the searching length and then send gp (go point) or gc (go continuous) orders to the robot control system and control the robot taking the torch moving to the component with a safety velocity, as soon as the torch contacts with the component, the virtual switch is closed and the robot automatically stops, then a fuzzy signal input to the robot and the fuzzy arithmetical will automatically judge which side of the component will be welded, and then, welding sub program will be called and executed. the fuzzy control rule can be described as the following: move the robot with the torch if the torch contact with the componentthen input= 1 and robot stop wait for some seconds, the robot will call the positive side welding program to execute if the torch not contact with the component, after waiting for some seconds, then input=o and robot will call the opposite side welding program to execute if out of the search range and the torch still not contact with the component, then input=o and pause robot and prompt wrong messagefigure 3 fuzzy control principle of side distinguishingaccording to the fuzzy control rule and program manual of cloos welding robot 6, some segments of the fuzzy program can be developed as the following:public varz46d1f .if z46d1f 1 then z46d2f:=0setvar (1,z46d2f) proc search$ (100)set (1)gp (stp)l002: if in (1) then jump l002when in (1) during gc (stp+2) then jump l001reset (1) pauselool:reset (1)but in fact, there exists great assembly size errors of each component, which result the torch usually cannot contact with the component (shown as figure 4) and usually make the robot make a mistake determination and call a wrong program to execute if it is according to the above search sub program. thus, it must improve the searching arithmetic. from figure 4, because of the component assembly size error, the actual contact position is out of the searching range in the searching direction, thus when the robot call the searching sub program, the torch will not contact with the component and the searching circuit not be closed, after waiting for some seconds (such as 10 seconds), the fuzzy distinguishing program will call a wrong welding program and control the robot execute a wrong task. in order to avoid this mistake, it must tell the robot call the searching sub program and execute searching task again. therefore, the sub program search should be modified as the following: proc distinguishset (1)labelol:num=num+lgp (stp)l002: if in (1) then jump l002when in (1) during gc (stp+2) then jump looireset (1)waits (6)change (stp+l)if num 2 jump label02jump labeloilabel02: waits (10)looj:reset (1). figure 4 sketch of searching position and component errorfrom the above sub program and searching method according to figure 4, it can automatically tell the robot when in executing the distinguishing program, and if the torch cannot contact with the component in the searing range and have no signal inputted, the robot will replace the torch initial position pi with p2, and move the torch in the first searching direction in another searing range again, until contact with the component at position p3, or wait for some seconds (if not contact with the component) and execute the other orders. after the above improvement, if there is no signal input at the first searching time, the robot will automatically execute the searching action again based on the first searching, which can effectively avoid the wrong calling welding program result from the wrong distinguish because of the component assembly size errors.iii. develop the fuzzy control programthe control system of the cloos robot is entirely opened for users, and the program style is more same as the c/c+ language, thus it can easily setup program frame for fuzzy control with the keyboard. according to the hardware and software design, sketch of the fuzzy control main program can be described as figure 5. figure 5 sketch diagram of fuzzy control systemfrom figure 5, it can easily develop the main control program (the menu program), some segments of menu program is shown as the following:if z46d2f1 then z46d2f:=0setvar (1,z46d2f)main.if prog=4 then jump lgxl46lgxl46:wread (,please slc component ng.= lgxh)if lgxh=ll then jump l46gwidiif lgxh=12 then jump l46gwid2.l46gwid2:.lg462: if not in (16) then jump lg462.above this, the welding sub program must also be modified as the following:if z46d2f1 then z46d2f:=osetvar (j,z46d2f).proc distinguishendp.main.call distinguishif z46d2f=o then jump oppositeif z46d2f= 1 then jump positiveopposite:jump labelmenupositive:endwhen the robot executes a welding task, sometimes it cannot find the start point of a welding seam correctly because of the component assembly size errors, which will make the robot weld a wrong seam or make the robot stop and prompt a mistake message automatically, where it can also improve the search sub program according to the distinguish sub program to avoid the seam searching errors.iv. experiments and resultsafter developed the fuzzy distinguishing sub program and the main control program, it used different types of component to test the fuzzy program and accomplish welding experiments such as in figure 6. figure 6 components for experimentsfrom experimental photo such as figure 6, it can easily understand when fixing the component on the robot station, if the positive side is upward, and the opposite side is downward, point p3 is on the right of the symmetrical blue dashed line (connecting the two assembly axes between point pi and point p2); when the positive side seams welding are all finished, it need to re-fix the component up side down, which means make the positive side downward and opposite side upward, in this situation, position of point pi and point p2 is still in the same position, but position of point p3 will be changed to the left of the blue dashed line, such as point p4. in the two fixing situations, because the torch position is fixed in the same position, which makes the displacement between the torch and the component different, when in teaching the welding program and developing the fuzzy distinguishing sub program, it can easily keep the robot avoid making mistakes and calling the wrong welding sub program.in the welding side distinguishing experiments, it first fixed the component positive side upward, then ran the robot, after the robot distinguished the side to be welded, it could correctly call the welding sub program to execute. on the contrary, when fixed the component opposite side upward, the robot could also distinguish the correct side to be welded and correctly call the welding sub program to execute.after developed the fuzzy distinguishing sub program, it can greatly improve the intelligent degree of the robot and help the operators easily operating