From: curt Date: Mon, 3 Feb 2003 21:29:58 +0000 (+0000) Subject: Initial stab at documenting the electrical system. X-Git-Url: https://git.mxchange.org/?a=commitdiff_plain;h=f15ca79b8f5f973fb9ddf1220a0b9fbc60f83f20;p=flightgear.git Initial stab at documenting the electrical system. --- diff --git a/docs-mini/README.electrical b/docs-mini/README.electrical new file mode 100644 index 000000000..5c3c409c5 --- /dev/null +++ b/docs-mini/README.electrical @@ -0,0 +1,149 @@ +Specifying and Configuring and Aircraft Electrical System +========================================================= + +Written by Curtis L. Olson +Started February 3, 2003 + + +Introduction +============ + +The FlightGear electrical system model is an approximation. We don't +model down to the level of individual electrons, but we do try to +model a rich enough subset of components so that a realistic (from the +pilot's perspective) electrical system may be implemented. We try to +model enough of the general flow so that typical electrical system +failures can be implimented and so that the pilot can practice +realistic troubleshooting techniques and learn the basic structure and +relationships of the real aircraft electrical system. + +An electrical system can be built from 4 major components: suppliers, +buses, outputs, and connectors. Suppliers are things like batteries +and generators. Buses collect input from multiple suppliers and feed +multiple outputs. Outputs are not strictly necessary, but are +included so we can name generic output types and provide a consistent +naming scheme to other FlightGear subsystems. Finally connectors +connect a supplier to a bus, or a bus to an output, and optionally can +specify a switch property (either a physical switch or a circuit +breaker.) + +At run time, the structure specified in the electrical system config +file is parsed and a directional graph (in the computer science sense) +is built. Each frame, the current is propagated through the system, +starting at the suppliers, flowing through the buses, and finally to +the outputs. The system follows the path of connectors laid out in +the config file and honors the state of any connector switch. + + +Suppliers +========= + +A supplier entry could look like the following: + + + Battery 1 + /systems/electrical/suppliers/battery[0] + battery + 24 + 60 + + + can be anything you choose to call this entry. + is the name of a property that will be updated with the state + of this supplier. + can be "battery", "alternator", or "external". + specifies the volts of the source + specifies the amps of the source + +Currently and are not really modeled in detail. This +is more of a place holder for the future. + + +Buses +===== + +A bus entry could look like the following: + + + Essential/Cross Feed Bus + /systems/electrical/outputs/bus-essential + /systems/electrical/outputs/annunciators + /systems/electrical/outputs/master-switch + + + is whatever you choose to call this bus + +You can have an arbitrary number of entries. Each entry is the +name of a property that will be updated with the value of the current +at that bus. This allows you to wire devices directly to the bus but +does not allow you to insert a switch or circuit breaker in between. +See "Outputs" and "Connectors" if you want to do that. + + +Outputs +======= + +An output entry could look like the following: + + + Starter 1 Power + /systems/electrical/outputs/starter[0] + + +An output isn't entirely unlike a bus, but it's nice conceptually to +have a separate entity type. This enables us to specify a common set +of output property names so that other subsystems can automatically +work with any electrical system that follows the same conventions. An +output lives on the other side of a switch, so this is how you can +wire in cockpit switches to model things like fuel pump power, +avionics master switch, or any other switch on the panel. + + is whatever you choose to call this bus + +You can have an arbitrary number of entries. Each entry is the +name of a property that will be updated with the value of the current +at that bus. This allows you to wire devices directly to the bus but +does not allow you to insert a switch or circuit breaker in between. +See "Outputs" and "Connectors" if you want to do that. + +Other FlightGear subsystems can monitor the property name associated +with the various outputs to decide how to render an instrument, +whether to run the fuel pump, whether to spin a gyro, or any other +subsystem that cares about electrical power. + + +Connectors +========== + +An connector entry could look like the following: + + + Alternator 1 + Virtual Bus 1 + /controls/switches/master-alt + + +A connector specifies and input, and output, and any number of +switches that are wired in series. In other words, all switches need +to be true/on in order for current to get from the input to the output +of the connector. + + specifies the of the input. Typically you would +specify a "supplier" or a "bus". + + specifies the of the output. Typically you would +specify a bus or an output. + +You can have an arbitrary number of entries. The switches +are wired in series so all of them need to be on (i.e. true) in order +for current to pass to the output. + + +Summary +======= + +The electrical system has a lot of power and flexibility to model a +variety of electrical systems. However, it is not yet perfect or +finished. One major weakness is that it doesn't yet model degraded +battery or generator power, and it doesn't model the "charge" of the +batteries in case of a generator failure.