Glosario de Control

bang-bang control

A very simple, no-tuning-required closed-loop control technique. It simply «turns on» the control effort when the process variable is too small, and «turns off» the control effort when the process variable is too big. It works well in some cases, but not all. See «Bang-bang» control on Wikipedia for more info.

Cartesian coordinate system

A set of points in space where each point is described by a set of numbers, indicating its coordinates within that space. These coordinates are an expression of the orthogonal distance of each point from a set of fixed, orthogonal axes (IE, a «rectangular» system). 2-dimension and 3-dimension spaces are most common in FRC (and likely what was learned in algebra 1), but any number of dimensions is theoretically possible. See Cartesian coordinate system on Wikipedia for more info.

churning losses

Complex friction-like forces arising from the fact that when gears and bearings rotate, they must displace liquid lubricant. This reduces the efficiency of rotating mechanisms.

control signal

The driving signal sent to a plant by a controller, usually quantified as a voltage.

Esfuerzo de control

Control signal

ley de control

Una fórmula matemática que genera entradas <input>`para conducir un :term:`sistema a un: estado deseado, dado el actual estado. Un ejemplo común es la ley de control \(\mathbf{u} = \mathbf{K(r - x)}\)

controller

Usado en una posición o compensación negativa en una planta para llegar al deseado estado del sistema haciendo cero la diferencia entre la señal de referencia y la salida.

convolution

A mathematical operation that calculates a weighted moving average of one function, with the weights assigned by a second function. A common way to «filter» sensor input is to apply a convolution to it, using a carefully-chosen filtering function. See convolution on Wikipedia for more info.

counter-electromotive force

A voltage generated in a spinning motor. The voltage is a result of the fact that has a coil of wire rotating near a magnet. See Counter-electromotive_force on Wikipedia for more info.

current

The flow of electrons through a conductor. Current is described with a unit of «Amps» (or simply «A»), and is measured at a single point in a circuit. One amp is equal to \(6241509074000000000\) electrons moving past the measurement point in one second.

dinámica

Rama de la física que se ocupa del movimiento de los cuerpos bajo la acción de fuerzas. En el control moderno, los sistemas evolucionan según su dinámica.

derivative

A mathematical operation which evaluates the «rate-of-change» of a function at a given point. See derivative on Wikipedia for more info.

error

Es la referencia menos la salida o el estado.

exponential search

An iterative process of finding a specific value within a wide search range by applying a multiplicative factor to the search value. See exponential search on Wikipedia for more info.

exponential smoothing

A very common way to implement a simple low-pass filter, using an exponential window function in a convolution with an input signal. The convolution operation simplifies down to a very simple set of math operations on the current input and previous output. See exponential smoothing on Wikipedia for more info.

ganancia

A scalar value that relates the magnitude of an input signal to the magnitude of an output signal. For example, gain in output = gain * input. A gain greater than one would amplify an input signal, while a gain less than one would dampen an input signal. A negative gain would negate the input signal.

Gaussian distribution

A special mathematical function that describes distributions of averages. The graph of a Gaussian function is a «bell curve» shape. This function is described by its mean (the location of the «peak» of the bell curve) and variance (a measure of how «spread out» the bell curve is). See Gaussian distribution on Wikipedia for more info.

gradiente

La derivada, pero aplicada a una función con múltiples entradas. Como resultado, la salida es tanto la magnitud de la tasa de cambio como la dirección del vector a lo largo del cual ocurre.

estado oculto

Un estado que no se puede medir directamente, pero cuya dinámica puede relacionarse con otros estados.

entrada

Una entrada a la planta (circuito) que puede modificar el estado de la planta.

Ej. Un volante tendrá 1 entrada: el voltaje del motor que lo impulsa.

Ej. Un drivetrain puede tener 2 entradas: los voltajes de los motores izquierdo y derecho.

Las entradas a menudo son representadas mediante la variable \(\mathbf{u}\), un vector de columna con una entrada por input a system.

regresión de minimos cuadrados

A curve-fitting technique which picks a curve to minimize the square of the error between the fitted curve and the actual measured data. See ordinary least-squares regression on Wikipedia for more info.

RCL

Linear-Quadratic Regulator - A feedback control scheme which seeks to operate a system in a «most optimal» or «lowest cost» manner, in the sense of minimizing the square of some «cost function» that represents a combination of system error and control effort. This requires an accurate mathematical model of the system being controlled, and function describing the «cost» of any given system state. See LQR on Wikipedia for more info.

medición

Las mediciones son salidas que se miden a partir de una planta, o sistema físico, utilizando sensores.

modelo

A set of mathematical equations that reflects some aspect of a physical system's behavior.

observador

En la teoría de control, un sistema que proporciona una estimación del estado interno de un sistema real dado a partir de las mediciones del entrada`y :term:`salida del sistema real. WPILib incluye una clase de filtro de Kalman para observar sistemas lineales y las clases ExtendedKalmanFilter y UnscentedKalmanFilter para sistemas no lineales.

ortogonal

Tener la propiedad de ser independientes o carecer de influencia mutua. Por ejemplo, dos lineas son ortogonales si al mover cualquier cantidad de unidades a lo largo de una línea provoca un desplazamiento cero a lo largo de la otra linea. En un sistema de coordenadas cartesianas a menudo se dice que las lineas ortogonales tienen ángulos de 90 grados entre sí.

output

Measurements from sensors. There can be more measurements than states. These outputs are used in the «correct» step of Kalman Filters.

Ej. Un volante puede tener 1 salida de un codificador que mide su velocidad.

Ej. Un tren motriz puede usar solvePNP y V-SLAM para encontrar su posición x/y/posición de frente en el campo. Está bien que haya 6 medidas (solvePNP x/y/frente y V-SLAM x/y/frente) y 3 estados (robot x/y/frente).

Outputs of a system are often represented using the variable \(\mathbf{y}\), a column vector with one entry per output (or thing we can measure). For example, if our system had states for velocity and acceleration but our sensor could only measure velocity, our output vector would only include the system's velocity.

retrato de fase

A graph of a function’s value and its derivative as they change in time, given some initial starting conditions. They are useful for analyzing system behavior (stable/unstable operating points, limit cycles, etc.) given a certain set of parameters or starting conditions. See phase portrait on Wikipedia for more info.

PID

Proportional-Integral-Derivative - A feedback controller which calculates a control signal from a weighted sum of the error, the rate of change of the error, and an accumulated sum of previous errors. See PID controller on Wikipedia for more info.

planta

El sistema o el conjunto de actuadores siendo controlados.

variable de proceso

Término usado para describir la salida de una :term:`planta `en contexto del control PID.

r-al cuadrado

A statistical measurement of how well a model predicts a set of data, representing the fraction of the observed variation in the independent variable that is accurately predicted by the model. The value typically runs from 0.0 (a terrible fit, equivalent to just guessing the average value of your independent variable) to 1.0 (a perfect fit). See Coefficient_of_determination on Wikipedia for more info.

referencia

El estado deseado. Este valor es usado como punto de referencia para que el controlador calcule el error.

tiempo de subida

Es el tiempo que le lleva al sistema alcanzar la referencia después de haber aplicado la entrada unitaria.

RECM

Root Mean Squared Error - Statistical measurement of how well a curve is fit to a set of data. It is calculated as the square root of the average (mean) of the squares of all the errors between the actual sample and the curve fit. It has units of the original input data. See Root Mean Squared Error on Wikipedia for more info.

punto de referencia

Término usada para describir la referencia de un controlador PID.

tiempo de estabilización

Es el tiempo que le lleva al sistema estabilizarse en la referencia después de haber aplicado la entrada unitaria.

signum function

A non-continuous function that expresses the «sign» of its input. It is equal to -1 for all negative input numbers, 0 for an input of 0, and 1 for all positive input numbers. See signum function on Wikipedia for more info.

estado

A characteristic of a system (e.g., velocity) that can be used to determine the system's future behavior. In state-space notation, the state of a system is written as a column vector describing its position in state-space.

Ex. A drivetrain system might have the states \(\begin{bmatrix}x \\ y \\ \theta \end{bmatrix}\) to describe its position on the field.

Ej. Un sistema de elevador puede tener los estados \(\begin{bmatrix} \text{position} \\ \text{velocity} \end{bmatrix}\) para describir su altura y velocidad actual.

A system's state is often represented by the variable \(\mathbf{x}\), a column vector with one entry per state.

statistically robust

The property of a data processing algorithm which makes it resilient to a noisy or outlier-prone data set. Designing statistically robust algorithms on robots is important because real-world sensor data can often be unpredictable, but unexpected robot behavior is never desirable. See Robust Statistics on Wikipedia for more info.

error de estado estable

Es el term:error <error> después que el sistema alcanza el equilibrio.

entrada unitaria

Una entrada del sistema que es \(0\) para \(t < 0\) y una constante mayor que \(0\) para \(t \geq 0\). Una entrada unitaria que es \(1\) para \(t \geq 0\) se le llama unit step input.

respuesta Unitaria

Es la respuesta del sistema a una entrada unitaria.

sistema

A term encompassing a plant and its interaction with a controller and observer, which are treated as a single entity. Mathematically speaking, a system maps inputs to outputs through a linear combination of states.

identificación del sistema

The process of capturing a system's dynamics in a mathematical model using measured data. The SysId toolsuite uses system identification to find kS, kV and kA terms.

Respuesta del sistema

Es el comportamiento de un sistema durante un tiempo después de aplicar una entrada.

voltage

The measurement of how much an electric field is «pushing» electrons through a circuit. It is sometimes called «Electromotive Force», or «EMF». It is measured in units of «Volts». It always is defined between two points in a circuit. If one electron travels between two points that have one volt of EMF between them, it will have been accelerated to the point of having \(\frac{1}{6241509074000000000}\) joules of energy.

viscous drag

The force generated from an object moving relatively slowly through non-turbulent fluid. In this region, the force is roughly proportional to the velocity of the object. It describes the most common type of «air resistance» an FRC robot would encounter, as well as losses in a gearbox from displacing grease. See Drag (physics) on Wikipedia for more info.

punto x

\(\dot{\mathbf{x}}\), o punto x: la derivada del vector state vector \(\mathbf{x}\). Si el system tuviera solo una velocidad state, entonces \(\dot{\mathbf{x}}\) representaría la system's aceleración.

x-hat

\(\hat{\mathbf{x}}\), o x-hat: el estado estimado de un sistema, como es estimado por un observador.