Editing Feed forward (control) (section)

== Model ==
The mathematical model of the plant (machine, process or organism) used by the feedforward control system may be created and input by a [[Control engineering|control engineer]] or it may be learned by the control system.<ref>{{cite web|title=Learned Feed Forward - Innovations in Motion Control|url=http://www.tagonline.org/articles.php?id=42|publisher=Technology Association of Georgia|access-date=24 February 2013|archive-date=16 March 2012|archive-url=https://web.archive.org/web/20120316002359/http://www.tagonline.org/articles.php?id=42|url-status=dead}}</ref> Control systems capable of learning and/or adapting their mathematical model have become more practical as [[microprocessor]] speeds have increased. The discipline of modern feedforward control was itself made possible by the invention of microprocessors.<ref name=onote1/><ref name=onote25>Alberts, T.E., Sangveraphunsiri, V. and Book, Wayne J., Optimal Control of a Flexible Manipulator Arm: Volume I, Dynamic Modeling, MHRC Technical Report, MHRC-TR-85-06, Georgia Inst, of Technology, 1985.</ref>

Feedforward control requires integration of the mathematical model into the control algorithm such that it is used to determine the control actions based on what is known about the state of the system being controlled. In the case of control for a lightweight, flexible [[robotic arm]], this could be as simple as compensating between when the robot arm is carrying a [[Payload (air and space craft)|payload]] and when it is not. The target joint angles are adjusted to place the payload in the desired position based on knowing the deflections in the arm from the mathematical model's interpretation of the disturbance caused by the payload. Systems that plan actions and then pass the plan to a different system for execution do not satisfy the above definition of feedforward control. Unless the system includes a means to detect a disturbance or receive an input and process that input through the mathematical model to determine the required modification to the control action, it is not true feedforward control.<ref name=onote38/><ref name=onote13>Book, W.J., Modeling, Design and Control of Flexible Manipulator Arms, PhD. Thesis, MIT, Dept. of Mech. Eng., April 1974.</ref><ref name=onote14>Maizza-Neto, 0., Modal Analysis and Control of Flexible Manipulator Arms, PhD. Thesis-, MIT, Dept. of Mech. Eng., September 1974.</ref>

===Open system<!--'Open system (control theory)' redirects here-->===
In [[systems theory]], an '''open system''' is a feed forward system that does not have any [[feedback loop]] to control its output. In contrast, a [[closed system (control theory)|closed system]] uses on a feedback loop to control the operation of the system.  In an open system, the output of the system is not fed back into the input to the system for control or operation.{{citation needed|date=May 2021}}