Abstract
In the field of measurement, we often encounter the need to measure a pipe length indirectly. We have thus developed an on-line pipe length measurement with one acoustic sensor from the viewpoints of cost and its ease to be used in various applications. The system made use of the stationary wave generated spontaneously or by hitting the pipes. The system realized a fast and highly accurate measurement by modeling the stationary wave as the state variable of a linear dynamic system and applying Kalman filters and maximum likelihood method.
The paper extends the system to that which can measure the temperature in the pipe together with the pipe length in order to cope with the situation where the temperature changes so rapidly as not to allow any conventional thermometer to track the change. The new system makes use of two acoustic sensors to achieve the objective.
