Topics

Guidance, Navigation, and Control (GNC)

Guidance, navigation and control (abbreviated GNC, GN&C, or G&C and within the context of NASA operations, often pronounced 'Gintsee' or (IPA) ʤɪnsiː) is a branch of engineering dealing with the design of systems to control the movement of vehicles, especially, automobiles, ships, aircraft, and spacecraft. In many cases these functions can be performed by trained humans. However, because of the speed of, for example, a rocket's dynamics, human reaction time is too slow to control this movement... See More

Digital Signal Processor (DSP)

A digital signal processor (DSP) is a specialized microprocessor chip, with its architecture optimized for the operational needs of digital signal processing. DSPs are fabricated on MOS integrated circuit chips. They are widely used in audio signal processing, telecommunications, digital image processing, radar, sonar and speech recognition systems, and in common consumer electronic devices such as mobile phones, disk drives and high-definition television (HDTV) products. The goal of a DSP is... See More

State Estimation

In mathematics, stability theory addresses the stability of solutions of differential equations and of trajectories of dynamical systems under small perturbations of initial conditions. The heat equation, for example, is a stable partial differential equation because small perturbations of initial data lead to small variations in temperature at a later time as a result of the maximum principle. In partial differential equations one may measure the distances between functions using Lp norms or... See More

Tuning

Tuning a control loop is the adjustment of its control parameters (e.g. in the case of a PID controller, it proportional band/gain, integral gain/reset, derivative gain/rate) to the optimum values for the desired control response. See More

State Space Representation

In control engineering, a state-space representation is a mathematical model of a physical system as a set of input, output and state variables related by first-order differential equations or difference equations. State variables are variables whose values evolve over time in a way that depends on the values they have at any given time and on the externally imposed values of input variables. Output variables’ values depend on the values of the state variables. from State-Space Representation -... See More

Errors and Residuals

In statistics and optimization, errors and residuals are two closely related and easily confused measures of the deviation of an observed value of an element of a statistical sample from its "theoretical value". The error (or disturbance) of an observed value is the deviation of the observed value from the (unobservable) true value of a quantity of interest (for example, a population mean), and the residual of an observed value is the difference between the observed value and the estimated value... See More

Multi-Agent Control

A multi-agent system (MAS or "self-organized system") is a computerized system composed of multiple interacting intelligent agents[citation needed]. Multi-agent systems can solve problems that are difficult or impossible for an individual agent or a monolithic system to solve. Intelligence may include methodic, functional, procedural approaches, algorithmic search or reinforcement learning. from Multi-Agent System - Wikipedia See More

Modeling (Dynamics)

A mathematical model is a description of a system using mathematical concepts and language. The process of developing a mathematical model is termed mathematical modeling. Mathematical models are used in the natural sciences (such as physics, biology, earth science, chemistry) and engineering disciplines (such as computer science, electrical engineering), as well as in non-physical systems such as the social sciences (such as economics, psychology, sociology, political science). Mathematical... See More

Mechanical Vibrations

Mechanical vibrations is the study of free and forced response analysis of SDOF and multi degrees of freedom mechanical systems. The reader is expected to have prior knowledge of dynamics, the strength of materials, differential equations, and Laplace transform. See More

System Identification

The field of system identification uses statistical methods to build mathematical models of dynamical systems from measured data. System identification also includes the optimal design of experiments for efficiently generating informative data for fitting such models as well as model reduction. A common approach is to start from measurements of the behavior of the system and the external influences (inputs to the system) and try to determine a mathematical relation between them without going... See More

Time Delay

For a device such as an amplifier or telecommunications system, group delay and phase delay are device performance properties that help to characterize time delay, which is the amount of time for the various frequency components of a signal to pass through the device from input to output. If this timing does not sufficiently meet certain requirements, the device will contribute to signal distortion. from Group Delay and Phase Delay - Wikipedia See More

Radar

Radar (radio detection and ranging) is a detection system that uses radio waves to determine the distance (ranging), angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver... See More

Open-Loop Controller

In an open-loop controller, also called a non-feedback controller, the control action from the controller is independent of the "process output", which is the process variable that is being controlled. It does not use feedback to determine if its output has achieved the desired goal of the input command or process "set point". There are many open-loop controls, such as on/off switching of valves, machinery, lights, motors or heaters, where the control result is known to be approximately... See More

Sliding Mode Control

In control systems, sliding mode control (SMC) is a nonlinear control method that alters the dynamics of a nonlinear system by applying a discontinuous control signal (or more rigorously, a set-valued control signal) that forces the system to "slide" along a cross-section of the system's normal behavior. The state-feedback control law is not a continuous function of time. Instead, it can switch from one continuous structure to another based on the current position in the state space. Hence... See More

PES Pareto

PES Pareto is a method to categorize the strata of broadband noise in the frequency domain for a feedback (or feedforward) system. The idea is to isolate noise measurements and then back filter their Power Spectral Densities (PSDs) through the appropriate magnitude squared filter to be able to model the noise as an independent noise input. All of the various isolated independent noise inputs can then have their PSDs forward filtered through the appropriate magnitude squared filter to show their... See More

Demodulation

Both in nature and engineered systems, many signals are modulated onto carriers. This provides some immunity to baseline noise and DC level shifts. We see many of these modulated signals in various position and velocity sensors (as well as others). Unfortunately, most control engineers are not taught enough about how to efficiently demodulate these signals so as to minimize the noise, nonlinearities, and time delay in the extracted information. This topic covers some of the ways in which control... See More

Feedback Principles

Feedback principles are the broad and fundamental concepts that underlay all systems (both human made and in nature) which rely on feedback for their proper operation. While the specific application, models, parameters, and conditions of any one system/environment can dramatically alter the behavior of the feedback dependent system, the principles themselves are immutable. Furthermore, while learning the mathematics needed to do most control design and control systems engineering is complicated... See More

Control Education

Control education deals with how controls engineers, control researchers, and educations teach topics in the field of automatic control. There is often some confusion because these different groups will often visualize different audiences for the topic. For our broad definition here we can consider the following audiences: Future controls researchers: This crowd has taken their first automatic control class in college or graduate school and has loved it so much that they wish to pursue it in... See More

Biomimicry or biomimetics

Biomimetics or biomimicry is the emulation of the models, systems, and elements of nature for the purpose of solving complex human problems. [2] The terms "biomimetics" and "biomimicry" are derived from Ancient Greek: βίος ( bios), life, and μίμησις ( mīmēsis), imitation, from μιμεῖσθαι ( mīmeisthai), to imitate, from μῖμος ( mimos), actor. A closely related field is bionics. [3] Living organisms have evolved well-adapted structures and materials over geological time through natural selection... See More

Pade Approximant

In mathematics, a Padé approximant is the "best" approximation of a function by a rational function of given order. Under this technique, the approximant's power series agrees with the power series of the function it is approximating. The technique was developed around 1890 by Henri Padé, but goes back to Georg Frobenius, who introduced the idea and investigated the features of rational approximations of power series. The Padé approximant often gives better approximation of the function than... See More

Anomaly Detection

In data analysis, anomaly detection (also referred to as outlier detection and sometimes as novelty detection) is generally understood to be the identification of rare items, events or observations which deviate significantly from the majority of the data and do not conform to a well defined notion of normal behaviour. Such examples may arouse suspicions of being generated by a different mechanism, or appear inconsistent with the remainder of that set of data. Anomaly detection finds application... See More

Phased Array

In antenna theory, a phased array usually means an electronically scanned array, a computer-controlled array of antennas which creates a beam of radio waves that can be electronically steered to point in different directions without moving the antennas. In a simple array antenna, the radio frequency current from the transmitter is fed to multiple individual antenna elements with the proper phase relationship so that the radio waves from the separate elements combine (superpose) to form beams, to... See More

Posicast Control

Posicast controllers are used to dampen the oscillations of a stable system(to improve transient response and reduce overshoot). By stable system, this refers to systems with manageable overshoot which satisfy BIBO stability. They were initially used as feed forward dampeners, especially by Otto J Smith in the 1950s who actually invented this class of controllers. Modern posicast controllers are available in both feedforward and feedback schemes and are widely used in power electronics. The... See More

Process Control Concepts and Practice

The chemical process industries (CPI) convert natural resources into useful products. The CPI sectors include pulp & paper, glass, petroleum refining, mineral refining, chemicals, polymers, food, paint, pharmaceuticals, water purification, fragrances, etc. Process control differs from many other application domains (such as mechatronics, aerospace, electronic, manufacturing, and distribution), because chemical processes are typically nonlinear, interactive, noisy, have delays, have constraints... See More