Continuous processing system with accumulator model for product flow control

A method of measuring product inventory in a loosely coupled mechanical system of the type having an upstream processing machine and a downstream processing machine operable at variably different speeds and connected to an entrance and exit portion of a product accumulator which transfers unit products from the upstream machine to the downstream machine and which has a variable length floating accumulation area beginning at the accumulator entrance where product speed is dependent only on the conveyor characteristics, and a variable length continuous accumulation area, extending from the floating accumulation area to the accumulator exit where products are packed in continuous touching contact and where product speed is dependent on the downstream machine operating speed, comprising the steps of:

• (a) providing a floating accumulation data array having a predetermined number of serially arranged data storage elements corresponding to physical portions of the accumulator;
• (b) providing a continuous-fill-accumulation data storage element for storing a value corresponding to the number of unit products currently in the continuous accumulation area of the accumulator;
• (c) detecting each unit product as it enters the accumulator and incrementing a data element of the floating accumulation data array which corresponds to the entrance of the accumulator in response to each detected entering product;
• (d) periodically serially shifting data through the elements of the data array in a direction corresponding to the direction of physical product movement through the accumulator;
• (e) periodically transferring data from a number of serially adjacent elements of the data array, which are selected based on the current value stored in the continuous-fill-accumulation data storage element, to the continuous-fill-accumulation data storage element to provide a new continuous-fill-accumulation value;
• (f) detecting each unit product as it exits the accumulator and decrementing the continuous-fill-accumulation element in response thereto.

A continuous processing system for performing production operations on a plurality of unit products comprising:

• (a) a downstream processing machine means for performing an operation on unit products passing therethrough, said downstream machine having a product inlet and a product outlet;
• (b) accumulator means having a product inlet and having a product outlet connected to said downstream machine product inlet for receiving and transferring said plurality of unit products to said downstream machine means and for accumulating unit products in tightly packed continuously touching relationship in a variable length area starting at a position adjacent said downstream machine product inlet;
• the number of unit products in said tightly packed continuously touching relationship adjacent said downstream machine product inlet defining a continuous-fill-accumulation;
• (c) count-in sensor means for sensing each unit product entering said accumulator means product inlet and for generating a count-in sensor signal in response thereto;
• (d) count-out sensor means for sensing each unit product exiting from said accumulator means product outlet to said downstream machine product inlet and for generating a count-out sensor signal in response thereto;
• (e) accumulator modeling means for receiving said count-in and said count-out sensor signals and for continuously predicting said continuous-fill-accumulation;
• (f) machine speed control means for continuously variably controlling the speed of said downstream machine based on said predicted continuous-fill-accumulation for maintaining said downstream machine speed sufficiently low relative the rate of unit products entering said accumulator means to continuously provide a sufficiently large continuous-fill-accumulation to enable an uninterrupted flow of unit products to said downstream machine, and for maintaining said downstream machine speed sufficiently high relative the rate of unit products entering said accumulator means to continuously prevent excessive accumulation of unit products in said accumulation means.