AN EXPERIMENTAL INVESTIGATION ON MEASURING THE PH VALUE OF THE SOLUTIONBASED ON THE MACHINE VISION

The pH value of the solution is an important physical and chemical parameter which affects the physical and chemical properties of the solution , the velocity of chemical reaction, the composition and properties of the resultant and the growth of the microbe metabolism greatly .It plays a decisive position in detecting and controlling at industrial procedure of production.The industrial pH meter based on the electrode is usually used to measure the pH Value of the solution in industry, although it has high precision in theory, its mechanization about chemical sensor is very complicated , the loss of electrolyte in electrode causes accumulated error, the electrode sensitive with H+ ion is polluted and damaged easily, the wash and purify of the electrode ruins the characteristics of the electrode and it does not used in high temperature and high pressure. These working condition defects puzzle factories and other enterprises. Studying its causes, it is not appropriate for the adverse circumstances. Starring from artificial colorimetric ocular estimate and according to the developing characteristics of the computer technique of the present period,this article put forward a new method which measures the pH value of the solution by testing the digital color information of the pH test paper drawing from the digital image file shot by digital camera . Compared with the method of using human vision, it improves the objectivity of the result by avoiding the subjectivity of human ; Compared with the method of using electrode, it can be content with the precision but avoiding the influences of the adverse circumstance.The article firstly summarizes the measuring method of the pH value of the solution, approaches the theory about the theory of colouriry ,the mechanization of the acid and alkali color-developing agent and the method of the colour measurement, then gives a simple system design scheme, and designs the hardware system based on the present computer technique, programmes the software, finally tests and verifys the technical scheme by experiment, proves its feasibility.