31/35 9.5 Current and Power Measurement Grain hopper Hopper:送料斗 885 Mil:面粉厂，磨粉机 Auger::螺旋钻Auger feed Mill motor motor Remote adiustment load meter Power sensing 00 PAT-1401 feed rate Adjust- controller able Flour speed drive Analog signal to adjust feed rate Fig.9.8 Power Measurement/Control in Extra meter to help with Grinding Application set up Tips:To maintain the machine at optimum power level via monitoring the motor power and adjusting material feed rate. 32/35 9.6 Using "Observers"to Measure Inaccessible Variables in a Physical System ●hy observer? -Some physical quantities are inaccessible or not cost/effective to measure directly. -A commercial sensor for the variable may not be available or perhaps the environment is too severe to allow a sensor to survive for long. The basic idea of the observer probably comes from the technical area usually called modern control theory. The observer is a mathematical model of the physical system in which the inaccessible variable(or variables)is found. -The observer must have a model(set of equations)describing the system. -At least one of the physical system's state variables can be directly measured. Examples in the text book.9.5 Current and Power Measurement Tips: To maintain the machine at optimum power level via monitoring the motor power and adjusting material feed rate. Fig. 9.8 Power Measurement/Control in Grinding Application Auger: 螺旋钻 Hopper: 送料斗 Mill: 面粉厂，磨粉机 31/35 z Why observer? - Some physical quantities are inaccessible or not cost/effective to measure directly. - A commercial sensor for the variable may not be available or perhaps the environment is too severe to allow a sensor to survive for long. z The basic idea of the observer probably comes from the technical area usually called modern control theory. z The observer is a mathematical model of the physical system in which the inaccessible variable (or variables) is found. - The observer must have a model (set of equations) describing the system. - At least one of the physical system's state variables can be directly measured. z Examples in the text book. 9.6 Using “Observers” to Measure Inaccessible Variables in a Physical System 32/35