A state variable is one of the set of variables that are used to describe the mathematical "state" of a dynamical system. Intuitively, the state of a system describes enough about the system to determine its future behaviour. Models that consist of coupled first-order differential equations are said to be in state-variable form.
In mechanical systems, the position coordinates and velocities of mechanical parts are typical state variables; knowing these, it is possible to determine the future state of the objects in the system.
In control engineering and other areas of science and engineering, state variables are used to represent the states of a general system. The state variables can be used to describe the state space of the system. The equations relating the current state and output of a system to its current input and past states are called the state equations. The state equations for a linear time invariant system can be expressed using coefficient matrices:
RN*N, RN*L, RM*N, RM*L,
where N, L and M are the dimensions of the vectors describing the state, input and output, respectively.
The state variable representing the current state of a discrete-time system (i.e. digital system) is , where n is the discrete point at which the system is being evaluated. The discrete-time state equations are
, which describes the next state of the system (x[n+1]) with respect to current state and inputs u[n] of the system.
, which describes the output y[n] with respect to current states and inputs u[n] to the system.
The International Technology Roadmap for Semiconductors, for example, has identified spin as a viable alternate state variable that should be developed for use in advanced electronic systems to complement the functionality provided by charge.
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When a state is successfully changed, it will also update the state variable in the animator. The animator has an integer parameter State: 1=Setup, 2=lockedToPaddle,3=Moving. Each state has it's own animation, at the start of each animation there is an ...
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