Twin Activate Fundamentals: Activation Pulses with Integrators
Altair EmployeeCreating signals that drive a component’s behavior is a fundamental requirement in systems modeling. Very often, a system’s model requires us to set up timers and delays that are triggered by events and reset by other events.
Although Twin Activate allows for many alternatives to create signal profiles for activation of a given block, using integrator blocks is the most flexible and generalizable way to do it.
Stripping this concept to the basics, integrating a constant 1 for 1 second results in a value of 1:
Taking this further, if, for example, it’s required to reach the value of 2.5 in 3.5 seconds, it can be generalized to the formula value/time, which can be implemented using a product block:
Furthermore, integrating 0 produces 0, so a timer or a delay can be held at 0 with this trick:
With these simple implementations there’s already a lot of different profiles to create, but this can be taken further using the re-initialization capability of the integrator block.
An integrator with re-initialization has two normal inputs and an activation input port (the red one on top). Every time an activation is received, the output of the integrator is updated to whatever value is being received through its second input:
These fundamentals can be expanded with very basic logic blocks to create signals of any kind, like in these examples:
Constant periodic pulses:
In this case, a logical block detects whether the output of the integrator is greater or equal to one, and an activation es triggered when that condition is reached. Note: As the activation input of the integrator depends on the integrator’s output, a loop breaker block is required to avoid an algebraic loop.
Increasingly spaced pulses:
In this case, every time the integral block is re-initialized, it starts from a more negative value and thus takes more time to reach an output of 1, constantly increasing pulse spacing.
Last but not least, I want to highlight how multiple integrators can be used together to delay timers depending on your needs:
These are absolute fundamentals and can be expanded much more. Also, keep in mind that there’s a full set of activation blocks that might be better suited for applications with desired activations occurring at discrete time instants. This guide highlights the flexibility and robustness of building signals with an integrator. You can download the models and play around with them.
Reach out in the community forum if you have questions about these or other systems modeling concepts!