Research On Controllable System Of Multi-DOFs Microoperation Workbench Based On Vision

1. Introduction At present, in many microoperation areas of engineering, for example, bioengineering ,medical science ,micro manufacturing and superprecision machining,integrate circuit manufacturing,microscope with scanning probe,fibre-optical connecting ,micro mechanical parts and assembly ,micro mechatronics parts machining and encapsulation,optic microoperation,aviation and spaceflight etc. Workers finish these microoperations mostly by hand, which result in low efficiency and successful possibility necessarily. To solve the problems in the above engineering, a new subject that is research on controllable system of muti-DOFs microoperation workbench based on vision will be discussed in the thesis. The aim is that we control a microoperation workbench by using computer, and add the system of vision to realize the intension of pointing the target by mouse on the computer screen, and the executing equipment in the workbench will reach the target through some special image manipulations. Because the system in the thesis involves the areas of mechanics ,electronics,communication,automation,image manipulation and so on, the range of the knowledge is very wide. On the whole, the content to research in the thesis mainly consists of the Microoperation workbench on controlling and driving ,the analyzing and selecting and programming of the serial communication ways and the designing of the vision system and arithmetic. .At last, after we establish the hardware system, we will finish a set of software to realize the function that is prearranged. 2. The whole outline on controllable system of multi-DOFs microoperation workbench The hardware system of the thesis mainly consists of three modules: mechanical part,The controlling and driving machine and computer image manipulation part. The mechanical part uses a kind of six DOFs microoperation workbench driven by step motor to realize the move along the axis of X,Y ,Z (transmit by screw and nut) and the rotation around the axis of X,Y ,Z (transmit by lever and gemel , turbine), so that it can reach a random spacial position when initializing the workbench. The controlling and driving machine uses 8031 singlechips as the controlling core to control step motor and provides RS-232 of asynchronous serial interface standardized by industry in order to communicate with computer. The hardware of computer image manipulation consists of vidicon,image collection card and computer, which make that the system can collect,save,display and output images. Through taking example for cell microoperation in bioengineering, we introduce the work principle of the whole system as follow: divide the work procedure about the move of the microoperation workbench into fast move and automatic move (precise move). Fast move work at a high speed to approach the target. The manipulation way of the automatic move is that click the target on the computer screen by mouse and then the workbench will reach the target automatically, and the principle is that compare the coordinates of the executing equipment end point with the ones of the target and the workbench will stop moving if the coordinate difference is less than a prearranged precision. We will use the technology of vision and depend on the working way of image real time manipulation as well as closed loop in order to guarantee the move precision. 3. The design of the system communication Because the system needs to realize the functions that computer can control the start,the stop and the move direction of the workbench, the controlling and driving machine module was added on it. At first, computer sends orders to the controlling and driving step motor Machine, then the controlling machine will drive the workbench to work according to the orders sent by computer. The serialcommunication is worked between the computer and the controlling machine through RS—232 serial port which is often used in engineering, the transmitting mode is single orientation one. The way to do port program is using the current Active control, namely the MSComm one in the system, there is an important attribute that is Settings in the MSComm, and it was used to initialize parameters and returns four parameters that are online velocity,odd or even checkout,data bit and stop bit in the form of character string. The thesis adopts "9600, N, 8, 1", at the same time it is also a part of communication agreements. Furthermore, for the convenience of making program in the upper computer, we also make an agreement that is using some appointed characters or character strings represent the relevant functions to realize. After having this agreement, in the upper computer, we only need to send the relevant characters or character strings to the lower computer according to the agreement when making program, and the characters or character strings will be translated and edited into the fundamental read-write orders directly by the relevant software of the module to do translating and editing in the lower computer. 4. The Theory Foundation of Computer Image Manipulation There is necessarily image manipulation in the course of being based on vision, because the system needs to collect outside images and get the executing equipment end point, we must do a preceding image manipulation and select space field median filter to decrease noise of images. In the course of binary processing, we select iterative method that can seek field value automatically, and then we do binary processing on images. Aimed at the needlepoint of the system from the thesis, we give the procedure in recognizing. It is that separating the needlepoint from the image background →taking out the character →decision-making. Based on the special geometry attributes of the needle, we make a judging rule in decision-making that is F(n)=(Color(i,j)=0)& (Color(i-1,j)=0)& (Color(i-2,j)=0) & (Color(i-n,j) =0)=1. If the rule is accorded, (i,j) will be the coordinate of the needlepoint.