Frequently Asked Questions

How do I get started creating a model?

See Getting Started for instructions on how to create your first model

Where can I find introductory examples?

See the demo/ directory for introductory examples.

How would you recommend to handle different rates and possibly lack of exact synchronization for the models which FormaK produces?

If you pass in the sensors and control information, the ManagedFilter will take care of the rest, including synchronizing your sensor readings. This reduces code complexity for you and opens the opportunity to adopt additional benefits as well.

In the current version of the library, there is manual work required to perform synchronization. The outline of the algorithm I’d recommend is:

1. Maintain a clock reference for publishing time

2. Queue inputs as they arrive (e.g. as ROS messages from subscribers), sorted by time

3. At the desired output rate, take the front of the message queue that are at or before the desired reference time

4. Pass that list/vector as input to the FormaK ManagedFilter .tick method (managed.tick(reference_time, list_of_messages)) and the ManagedFilter will process the messages according to their time stamp using the process model to shift in time and align with the stamped time

5. The output from the tick function will be the estimate of the filter for all of the messages up to the reference time

Example usage of the ManagedFilter class

If ManagedFilter isn’t serving your use case, please reach out to formak.open.source@gmail.com or submit an issue via Github. I’d love to learn more about your use case and see if it’s something that can be supported by the library.