The system definition can be present any number of times in an aircraft definition. This section is used to define an arbitrary system, such as navigation, guidance, or control avionics, electrical systems, etc. The system, autopilot, and flight_control sections of a configuration file are all built the same way, using channel elements that contain strings of component definitions. The name for a channel is simply a brief, descriptive, name. The name is not used for anything other than display. The execute attribute value refers to a property that evaluates to a boolean indicating whether the channel should execute or not. If this attribute is not supplied, the channel always executes. The aerosurface scale component maps an input value (which must fall within the span specified in the domain element) to an output value that falls within the span specified in the range element. For example, if the actual input value is 30% of the distance from the minimum to the maximum domain value, the output would be the value corresponding to 30% of the span of the range, from the minimum range value. The Gain element may contain a fixed numeric value, or it may be a property name. Specifies the proportional constant value or property. The integrator control action gain. Specifies a rectangular integrator. Specifies a trapezoidal integrator. Specifies an Adams-Bashforth second order integrator. [default] Specifies an Adams-Bashforth third order integrator. The derivative control action gain. The trigger element provides a way to specify a property that controls how the integrator works, and is designed for wind-up protection. If the value of the property supplied to the trigger element is 0, there is no effect. If the value of the trigger property is non-zero, (positive or negative) then the integrator does not integrate and holds the last value. If the trigger property value is negative, the integrator value is reset to 0.0. pvdot is the process variable time derivative. If not specified, the derivative control action will be determined from the change in the input from the last time step (divided by the time step size). If pvdot is specified, the specified value will be used instead. The difference may be minimal in practice - UNLESS there is an unnatural step change in the input value. For instance, if the control input (process variable) is alpha, an alphadot value is calculated as mentioned from the previous value. If pvdot is explicitly specified as alphadot (alphadot is calculated and is available as a native property in JSBSim) the results can be smoother - particularly if there is a step change in the error signal (the input) due to a step change in the target state. To be clear, pvdot is meant to be the time derivative of the input parameter. If the input to the PID controller is pitch rate then pvdot should be pitch acceleration. If altitude is the input then pvdot should be altitude rate. Specifies a standard PID controller where the output is defined as: Output = Kp * (Input + Integrator_value + Kd*Dval), where Dval is the time derivative of the input signel. The Gain element may contain a fixed numeric value, or it may be a property name. The Gain element may contain a fixed numeric value, or it may be a property name. An actuator component models a general purpose mechanical effector. The actuator can exhibit a lag, can be rate- and position-limited, can feature a bias, can have a deadband, and it can feature hysteresis. The rate limit can be specified as a numeric value or as a property. Further, an "incr" or "decr" sense attribute to specify which direction the rate limit should apply to. The sense attribute determines which direction the rate limit applies to. If no sense is given, the rate limit applies to both directions equally. If "incr" is specified then the rate limit applies only to the rate of increase. If "decr" is specified, then the rate limit applies only to a decreasing rate. The decreasing rate limit - if given - is assumed to be negative - no negative sign is required. Specify this type when the rate limit applies to an increasing rate. Specify this type when the rate limit applies to a decreasing rate. The width value specifies the width of the deadband - i.e. the total span about zero where the input will be mapped to zero output. The noise can be entered as a percentage of the signal, or as an absolute value. This element specifies a minimum and/or a maximum limit that the associated component will be allowed to have. The result will be clipped to the specified limits. The domain defines the minimum and maximum input value allowed. The range defines the minimum and maximum output value mapped.. Uses the integer value of the first immediate child element as an index to select one of the subsequent immediate child elements to return the value of. Multiplies together the values of all immediate child elements. Subtracts from the value of the first immediate child element the values of all subsequent immediate child elements. Sums the values of all immediate child elements. Divides the value of the first immediate child element by the value of the second immediate child element. Returns the absolute value of the immediate child element. Returns the square root of the value of the immediate child element. Converts the argument presumed to be expressed in degrees to radians by multiplying the value of the immediate child element by pi/180. Converts the argument presumed to be expressed in radians to degrees by multiplying the value of the immediate child element by 180/pi. Raises the value of the first immediate child element to the power of the value of the second immediate child element. Calculates the sine of the value of the immediate child element (the argument is expected to be in radians). Calculates the cosine of the value of the immediate child element (the argument is expected to be in radians). Calculates the tangent of the value of the immediate child element (the argument is expected to be in radians). Calculates the arcsine (inverse sine) of the value of the immediate child element. The value provided should be in the range from -1 to +1. The value returned will be expressed in radians, and will be in the range from -pi/2 to +pi/2. Calculates the arccosine (inverse cosine) of the value of the immediate child element. The value provided should be in the range from -1 to +1. The value returned will be expressed in radians, and will be in the range from 0 to pi. Calculates the inverse tangent of the value of the immediate child element. The value returned will be expressed in radians, and will be in the range from -pi/2 to +pi/2. Calculates the inverse tangent of the value of the immediate child elements, Y/X (in that order). It even works for X values near zero. The value returned will be expressed in radians, and in the range -pi to +pi. Returns the smallest value from all the immediate child elements. Returns the largest value from all the immediate child elements. Returns the average value of all the immediate child elements. Returns the fractional part of the value of the immediate child element . Returns the integer part of the value of the immediate child element. Returns the remainder from the integer division of the value of the first immediate child element by the second immediate child element, X/Y (X modulo Y). The value returned is the value X-I*Y, for the largest integer I such that if Y is nonzero, the result has the same sign as X and magnitude less than the magnitude of Y. For instance, the expression "5 mod 2" would evaluate to 1 because 5 divided by 2 leaves a quotient of 2 and a remainder of 1, while "9 mod 3" would evaluate to 0 because the division of 9 by 3 has a quotient of 3 and leaves a remainder of 0. Returns a 1 if the value of the first immediate child element is less than the value of the second immediate child element, returns 0 otherwise. Returns a 1 if the value of the first immediate child element is less than or equal to the value of the second immediate child element, returns 0 otherwise. Returns a 1 if the value of the first immediate child element is greater than the value of the second immediate child element, returns 0 otherwise. Returns a 1 if the value of the first immediate child element is greater than or equal to the value of the second immediate child element, returns 0 otherwise. Returns a 1 if the value of the first immediate child element is equal to the value of the second immediate child element, returns 0 otherwise. Returns a 1 if the value of the first immediate child element is not equal to the value of the second immediate child element, returns 0 otherwise. Returns a 1 if the values of the immediate child elements are all 1, returns 0 otherwise. Values provided are expected to be either 1 or 0 within machine precision. Returns a 1 if any of the values of the immediate child elements are 1, returns 0 otherwise. Values provided are expected to be either 1 or 0 within machine precision. Returns the inverse of the value of the supplied immediate child element (e.g., returns 1 if supplied a 0). If the value of the first immediate child element is 1, then the value of the second immediate child element is returned, otherwise the value of the third child element is returned. Returns the result from a 1-dimensional interpolation of the supplied values, with the value of the first immediate child element representing the lookup value into the table, and the following pairs of values representing the independent and dependent values. The first provided child element is expected to be a property. The interpolation does not extrapolate, but holds the highest value if the provided lookup value goes outside of the provided range. A simple text description of the item.