681 121 84 controller 681 121 84 controlleroptimizer of ball mill performance pistun ye 1 zahray v 2 and fedoryshyn r 1 1 lviv polytechnic national university 12 s bandery st lviv 79013 ukraine email romanfedoryshynyahoo 2 techprylad ltd 116 antonovycha st lviv 79057 ukraine email zagrajukr this work is dedicated to regulatoroptimizer ball.