A system architecture for closed loop control of infusion devices is described. The architecture provides means to control the flow from an infusion device as well as in some embodiments the pressure of the delivery. A variety of infusion systems are described that use the closed loop control architecture. In some embodiments the closed loop control may be adapted to current commonly used infusion means such as a gravity feed intravenous system. Other embodiments describe infusion pump system that use biasing or drive mechanisms of springs, elastomers, rotary and linear motors.