Material related to reading the book Feedback Systems - Second Edition, written by Karl Johan Åström and Richard M. Murray.
Alphabetical list of terms introduced in chapter 1:
closed loop A system divided into parts that are interconnected in a cycle. A system with feedback will include a closed loop.
command signal Input to a system from an actor to intentionally change the state of the system. For example an operator that changes setting of a machine through a control panel.
control This term is in the book defined as the use of algorithms and feedback in engineered systems.
control law Algorithm in a control system that provides functionality to compute control action based on input from sensors.
dynamical system System whose behaviour changes over time. An example is a bathtub with water flowing into the tub through the facet and leaving through the drain.
feedback Coupling between dynamical systems in a circular chain of cause and effect. An example is body temperature regulation, when your body temperature rises through exercise, you will start to sweat to release heat.
feedback loop Central concept in control involving a loop construction with sensing, computation, and actuation to give a system a desired behaviour.
feedforward Measuring disturbance and using this as input of a control system to proactively take a corrective action preventing the disturbance from affecting the system. A feedforward controller will not measure the actual output of the system it is hence an open loop system.
information Data in the form of signals flowing in a control system, can be digital or analog.
negative feedback Type of feedback causing a response that will reverse or cause the opposite effect of the original stimulus. An example is body temperature regulation, when your body temperature rises through exercise, you will start to sweat to release heat.
open loop A system where parts are not connected in a cycle as opposed to a closed loop system.
positive feedback Type of feedback causing a response that will amplify the changes rather than reverse them, in other words the opposite of negative feedback. Encouragement is a form of positive feedback.
proportional integral (PI) Type of regulation based on compensating proportionally for the error between the measured and desired output and the integral of that error.