In the manufacture and production of processed meat food products, the final amount of ground meat components in the final food product is labeled, such as the percent fat and/or amount of protein, for example. The amount of ground meat added to the process is used to calculate the amounts of other additional ingredients that are based on the amount of meat added. Therefore, there is a need to measure the amount of ground meat transported into the process hopper from the meat hopper and added to other ingredients. One way to measure the amount of ground meat is to monitor the flow rate of the system. However, flow rates of non-liquid streams, such as ground meat, can be difficult to measure in a continuous process.
One method of measure utilizes a proportional-integral-derivative controller, or PID loop control, often used as a feedback loop control in process manufacturing systems. The PID controller obtains a measured value from the process and compares it with a setpoint or target value. The difference between the two values, if any, is an error value, which is then used to calculate a correction to the process input variable so that the correction will remove the error from the process output measurement and bring it closer to the target setpoint.
In a ground meat processing system, loss in weight data is measured to provide PID loop control to establish the flow rate of ground meat. Loss in weight data is obtained by measuring the weight of the ground meat stream fed to the system (i.e., fed to the pump) and subtracting the final weight of the stream at the same location after a set time period has elapsed. When considered in conjunction with the elapsed time, this yields an actual flow rate which can be used to obtain a difference in flow rate between the actual flow rate value and the target value, which is an error value. The pump speed is then adjusted based on the loss in weight data provided to the PID loop control.
One problem with the PID loop control being based on loss in weight data, however, is that as the hopper is being filled with the meat, the loss in weight data cannot be properly calculated, as can be seen in FIG. 2. This is because meat is being added to the hopper at the same time that meat is leaving the hopper and being transported through the pump, therefore, an accurate measurement of weight loss cannot be properly measured at the same time. As a result, during times of filling the hopper flow rate measurements must be temporarily halted due to the rapid increase in weight within the hopper. Therefore, the halt in collecting loss in weight data interferes with the operation of the PID loop control and during these periods of filling there is no PID loop control.
Without accurate and continual PID loop control, or any other type of flow rate control of the system, inaccurate flows of the meat stream may cause the amount or weight of meat added to the final meat product to be inaccurately calculated.