Signals

This part provides the mechanism to transfer information from one entity to another. There are three main types of signals, all deriving from the common class dynamicgraph::SignalBase :

• dynamicgraph::Signal : a "normal" signal, passing data around by value
• dynamicgraph::SignalPtr : a signal used for efficient passing of large data, by reference (or rather, C pointers)*
• dynamicgraph::SignalTimeDependent : a signal that enforces a time dependency between other signals, making sure its inputs are up to date on access, using a incrementing time tick as reference.

* Note: this may cause a problem if this package is used in a multithreaded program.

Signals can be grouped together using dynamicgraph::SignalArray.

Signals implement a caching mechanism by storing the last computation time tick.

For more information, please see the individual signal pages.

Samples

• The following code ensures the jacobian output signal uses up-to-date values for its computations, when accessed.

// This signal returns the Jacobian of the current value
//  according to the robot state
dg::SignalTimeDependent<ml::Matrix,int> jacobianSOUT;

(...)

jacobianSOUT.addDependency( positionSIN );
jacobianSOUT.addDependency( articularJacobianSIN );