Mass measurement of non-Newtonian substances in a conveyor pipe based on pulse response acquisition

This paper presents a non-invasive principle for the measurement of the mass of Newtonian and non-Newtonian substances in a closed pipe. At a desired point and in a desired direction, a pulse shaped excitation force is applied to the conveyor system. With an accelerometer the movements of the pipe are measured in three axes to acquire the natural frequency of the pulse response. The measurement principle exploits the relation between the mass and the natural frequency of a system showing approximately constant spring behavior. The parameters measured are the natural frequency and the amplitude of the FFT spectrum. Our experiments show the influence of pipe loading on the natural frequency with a good reproducibility for both parameters.