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Smith Predictor
The Smith predictor (invented by O. J. M. Smith in 1957) is a type of predictive controller designed to control systems with a significant feedback time delay. The idea can be illustrated as follows. Suppose the plant consists of G(z) followed by a pure time delay z^. z refers to the Z-transform of the transfer function relating the inputs and outputs of the plant G. As a first step, suppose we only consider G(z) (the plant without a delay) and design a controller C(z) with a closed-loop transfer function H(z)=\frac that we consider satisfactory. Next, our objective is to design a controller \bar(z) for the plant G(z) z^ so that the closed loop transfer function \bar(z) equals H(z) z^. Solving \frac = z^ \frac, we obtain \bar = \frac. The controller is implemented as shown in the following figure, where G(z) has been changed to \hat(z) to indicate that it is a model used by the controller. Note that there are two feedback loops. The outer control loop feeds the output back ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otto J
Otto is a masculine German given name and a surname. It originates as an Old High German short form (variants ''Audo'', ''Odo'', ''Udo'') of Germanic names beginning in ''aud-'', an element meaning "wealth, prosperity". The name is recorded from the 7th century ( Odo, son of Uro, courtier of Sigebert III). It was the name of three 10th-century German kings, the first of whom was Otto I the Great, the first Holy Roman Emperor, founder of the Ottonian dynasty. The Gothic form of the prefix was ''auda-'' (as in e.g. '' Audaþius''), the Anglo-Saxon form was ''ead-'' (as in e.g. ''Eadmund''), and the Old Norse form was '' auð-''. The given name Otis arose from an English surname, which was in turn derived from ''Ode'', a variant form of ''Odo, Otto''. Due to Otto von Bismarck, the given name ''Otto'' was strongly associated with the German Empire in the later 19th century. It was comparatively frequently given in the United States (presumably in German American families) during ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Controller (control Theory)
Control theory is a field of mathematics that deals with the control of dynamical systems in engineered processes and machines. The objective is to develop a model or algorithm governing the application of system inputs to drive the system to a desired state, while minimizing any ''delay'', ''overshoot'', or ''steady-state error'' and ensuring a level of control stability; often with the aim to achieve a degree of optimality. To do this, a controller with the requisite corrective behavior is required. This controller monitors the controlled process variable (PV), and compares it with the reference or set point (SP). The difference between actual and desired value of the process variable, called the ''error'' signal, or SP-PV error, is applied as feedback to generate a control action to bring the controlled process variable to the same value as the set point. Other aspects which are also studied are controllability and observability. Control theory is used in control system eng ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Z-transform
In mathematics and signal processing, the Z-transform converts a discrete-time signal, which is a sequence of real or complex numbers, into a complex frequency-domain (z-domain or z-plane) representation. It can be considered as a discrete-time equivalent of the Laplace transform (s-domain). This similarity is explored in the theory of time-scale calculus. Whereas the continuous-time Fourier transform is evaluated on the Laplace s-domain's imaginary line, the discrete-time Fourier transform is evaluated over the unit circle of the z-domain. What is roughly the s-domain's left half-plane, is now the inside of the complex unit circle; what is the z-domain's outside of the unit circle, roughly corresponds to the right half-plane of the s-domain. One of the means of designing digital filters is to take analog designs, subject them to a bilinear transform which maps them from the s-domain to the z-domain, and then produce the digital filter by inspection, manipulation, or numeric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Closed-loop Transfer Function
A closed-loop transfer function in control theory is a mathematical expression (algorithm) describing the net result of the effects of a closed (feedback) loop on the input signal to the plant under control. Overview The closed-loop transfer function is measured at the output. The output signal can be calculated from the closed-loop transfer function and the input signal. Signals may be waveforms, images, or other types of data streams. An example of a closed-loop transfer function is shown below: The summing node and the ''G''(''s'') and ''H''(''s'') blocks can all be combined into one block, which would have the following transfer function: : \dfrac = \dfrac G(s) is called feedforward transfer function, H(s) is called feedback transfer function, and their product G(s)H(s) is called the Open loop transfer function. Derivation We define an intermediate signal Z (also known as error signal) shown as follows: Using this figure we write: : Y(s) = G(s)Z(s) : Z(s) =X(s) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smith Predictor 1
Smith may refer to: People * Metalsmith, or simply smith, a craftsman fashioning tools or works of art out of various metals * Smith (given name) * Smith (surname), a family name originating in England, Scotland and Ireland ** List of people with surname Smith * Smith (artist) (born 1985), French visual artist Arts and entertainment * Smith (band), an American rock band 1969–1971 * ''Smith'' (EP), by Tokyo Police Club, 2007 * ''Smith'' (play), a 1909 play by W. Somerset Maugham * ''Smith'' (1917 film), a British silent film based on the play * ''Smith'' (1939 film), a short film * ''Smith!'', a 1969 Disney Western film * ''Smith'' (TV series), a 2006 American drama * ''Smith'', a 1932 novel by Warwick Deeping * ''Smith'', a 1967 novel by Leon Garfield and a 1970 TV adaptation Places North America * Smith, Indiana, U.S. * Smith, Kentucky, U.S. * Smith, Nevada, U.S. * Smith, South Carolina, U.S. * Smith Village, Oklahoma, U.S. * Smith Park (Middletown, Connecticut), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smith Predictor 2
Smith may refer to: People * Metalsmith, or simply smith, a craftsman fashioning tools or works of art out of various metals * Smith (given name) * Smith (surname), a family name originating in England, Scotland and Ireland ** List of people with surname Smith * Smith (artist) (born 1985), French visual artist Arts and entertainment * Smith (band), an American rock band 1969–1971 * ''Smith'' (EP), by Tokyo Police Club, 2007 * ''Smith'' (play), a 1909 play by W. Somerset Maugham * ''Smith'' (1917 film), a British silent film based on the play * ''Smith'' (1939 film), a short film * ''Smith!'', a 1969 Disney Western film * ''Smith'' (TV series), a 2006 American drama * ''Smith'', a 1932 novel by Warwick Deeping * ''Smith'', a 1967 novel by Leon Garfield and a 1970 TV adaptation Places North America * Smith, Indiana, U.S. * Smith, Kentucky, U.S. * Smith, Nevada, U.S. * Smith, South Carolina, U.S. * Smith Village, Oklahoma, U.S. * Smith Park (Middletown, Connecticut), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Feed-forward Control
A feed forward (sometimes written feedforward) is an element or pathway within a control system that passes a controlling signal from a source in its external environment to a load elsewhere in its external environment. This is often a command signal from an external operator. A control system which has only feed-forward behavior responds to its control signal in a pre-defined way without responding to the way the load reacts; it is in contrast with a system that also has feedback, which adjusts the input to take account of how it affects the load, and how the load itself may vary unpredictably; the load is considered to belong to the external environment of the system. In a feed-forward system, the control variable adjustment is not error-based. Instead it is based on knowledge about the process in the form of a mathematical model of the process and knowledge about, or measurements of, the process disturbances. Some prerequisites are needed for control scheme to be reliabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minimum Phase
In control theory and signal processing, a linear, time-invariant system is said to be minimum-phase if the system and its inverse are causal and stable. The most general causal LTI transfer function can be uniquely factored into a series of an all-pass and a minimum phase system. The system function is then the product of the two parts, and in the time domain the response of the system is the convolution of the two part responses. The difference between a minimum phase and a general transfer function is that a minimum phase system has all of the poles and zeroes of its transfer function in the left half of the s-plane representation (in discrete time, respectively, inside the unit circle of the z-plane). Since inverting a system function leads to poles turning to zeroes and vice versa, and poles on the right side (s-plane imaginary line) or outside ( z-plane unit circle) of the complex plane lead to unstable systems, only the class of minimum phase systems is closed under in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
