What is YoVariables

YoVariables provides a framework for organizing, storing, and manipulating variables used in algorithms. The variables are organized in a tree structure using registries.

This library was designed with the idea that a user should be able to:

• retrieve any control variable by name,
• list the variables declared by an algorithm,
• observe their value changing over time and have access to the variable history,
• should be able to tune a variable on the fly. YoVariables is the foundation block to implement these features in the Simulation Construction Set project.

Who would use YoVariables

Any developer using the Simulation Construction Set project for visualizing an algorithm.

Any developer who wants to organize control variables.

What is the goal of YoVariables?

The objective is to provide a data structure that is easy to implement and intuitive to use and usable in a real-time environment.

Content

YoRegistry and YoVariable

A YoVariable is an abstract class that represents a primitive that has a name and can be registered in a YoRegistry. Five implementations can be found:

• YoBoolean to implement a variable holding a boolean value.
• YoDouble to implement a variable holding a double value.
• YoInteger to implement a variable holding an integer value.
• YoLong to implement a variable holding a long value.
• YoEnum to implement a variable holding an enum value.

YoRegistry represents a registry that contains variables and child registries.

YoParameter

A YoParameter can be seen as a read-only YoVariable that guarantees that the algorithm declaring it will only read the parameter value. As a consequence, when dealing with a YoParameter on the user side, for instance in SCS, it is ensured that the parameter is only modified by the user.

A YoParameter can be attributed an initial value at construction or can also be loaded from an XML parameter file. See XmlParameterReader and XmlParameterWriter from more details.

YoBuffer

YoBuffer provides an implementation of a buffer which can be used to store value history of collection of YoVariables.

Filters

The Filters project provides a way of generating yo variables with diffeerent types of filters on the resulting output signal. This includes:

• AlphaFilteredYoVariable, which applies an alpha filter to a YoDouble, which is equivalent to a low-pass filter.
• RateLimitedYoVariable, which limits the output of a YoDouble to change less than a cerrtain rate.
• BacklashCompensatedVelocityYoVariable, which attempts to remove the backlash from the velocity that is estimated from a finite-differenced position signal.
• GlitchFilteredYoBoolean, which forces a system to change value for a certain number of times before the return changes value.

Using YoVariables from .jar releases with Maven/Gradle

The releases .jars for YoVariables are hosted on Bintray. You can browse the IHMC release packages at https://bintray.com/ihmcrobotics/maven-release. Instructions for adding the Maven repository and identifying the artifacts can also be found on Bintray for each package.

At a minimum, you will need to have the following repository declared in your build script to use the YoVariables .jars:

repositories {
   mavenCentral()
}

dependencies {
   compile group: "us.ihmc", name: "ihmc-yovariables", version: "x.x",
   compile group: "us.ihmc", name: "ihmc-yovariables-filters", version: "x.x"
}