|Particle Discharge Rate Analysis and Control Laws of the Exit Gate for Pyramidal Hoppers
Jaehyun Kim and Jonghoek Kim*
International Journal of Control, Automation, and Systems, vol. 19, no. 7, pp.2529-2535, 2021
Abstract : In this paper, we investigated a pyramidal hopper with extended discharge at the exit to make a bag of particles to a designated weight. Any feedback control strategy cannot be applied because the exit gate does not have any encoders to check its size, the gate size cannot be adjusted precisely during the closing motion, and the speed of the closing gate is relatively slow compared to the discharge rate of the particles. By only processing the weighing scale measurement in real time, we need to find the best point of time to start the exit gate closure of the pyramidal hopper to fill precise amount of particles into the bag. We developed and compared two control methods to determine appropriate point to initiate gate closure. First, we developed a control method by applying an empirical model describing the correlation between the gate size and the particle discharge rate, which is established by thorough experiments. Second, we developed a control method using curve fitting to predict the discharge rate of particles during gate closing motion without experiment. Both control methods were demonstrated using real time experiments, and the first one with an empirical model showed better result for final weight. This method can be directly applied to weight control of bag filling hopper without modifying the hardware system.
Discharge rate analysis, exit gate control, hopper control, pyramidal hopper.