Closed-Loop Method for Controlling Insulin Infusion

Abstract

A closed loop infusion system controls the rate that fluid is infused into the body of a user. The closed loop infusion system includes a sensor system, a controller, and a delivery system. The sensor system includes a sensor for monitoring a condition of the user. The sensor produces a sensor signal, which is representative of the condition of the user. The sensor signal is used to generate a controller input. The controller uses the controller input to generate commands to operate the delivery system. The delivery system infuses a liquid into the user at a rate dictated by the commands from the controller. Preferably, the sensor system monitors the glucose concentration in the body of the user, and the liquid infused by the delivery system into the body of the user includes insulin.

1 .- 32 . (canceled) 
     
     
         33 . A method for calculating the amount of insulin to be infused into a body of a user, the method comprising:
 obtaining a blood glucose concentration of the user;   generating a controller input based on the blood glucose concentration; and   generating infusion calculations by a proportional plus, integral plus, derivative (PID) controller from the controller input using at least one preset controller gain;   wherein the at least one preset controller gain is selected such that the infusion commands generated by the PID controller infuses insulin into the body of the user in response to the glucose concentration at a rate similar to a rate that beta cells would release insulin in an individual with a healthy normally functioning pancreas; and   wherein the an automatic blood withdrawal system is used to obtain the blood glucose concentration of the user.   
     
     
         34 . The method according to  claim 33 , further comprising:
 infusing insulin based on the infusion calculations from the PID controller;   wherein the insulin is infused through an IV catheter connected to the body of the user.   
     
     
         35 . The method according to  claim 33 , wherein the at least one preset controller gain includes at least one tuning parameter that further modifies the commands generated by the PID controller to create an insulin concentration profile that more closely resembles the insulin concentration profile that would be generated by the release of insulin by beta cells in an individual with a healthy normally functioning pancreas. 
     
     
         36 . The method according to  claim 35 , wherein the at least one tuning parameter is an integrator leak. 
     
     
         37 . The method according to  claim 35 , wherein the at least one tuning parameter is a lead/lag compensator. 
     
     
         38 . The method according to  claim 35 , wherein the at least one tuning parameter is an integrator clip. 
     
     
         39 . The method according to  claim 35 , wherein the at least one tuning parameter is a feedback of predicted plasma insulin. 
     
     
         40 . The method according to  claim 33 , wherein the at least one preset controller gain is selected by a method that includes the step of measuring an insulin response of at least one individual with a healthy normally functioning pancreas and calculating the at least one controller gain that causes the infusion commands to generally match the insulin response of the at least one individual. 
     
     
         41 . The method according to  claim 33 , wherein the PID controller is a bilinear PID controller.