Documentation

jointVariables

List all kinematic variables associated with joints

Syntax

``jointVariables(ks)``

Description

````jointVariables(ks)` lists the kinematic variables native to the `KinematicsSolver` object `ks` and available to capture the displacements of joints.MATLAB outputs a table with the joint variables in rows. Each row gives the ID of a variable, the type of joint it belongs to, the path from the root of the model to the corresponding joint block in the Simulink model, and the unit for its numerical value. The table starts out fully populated with all the joint variables identified in the model at the time the `KinematicsSolver` object is constructed.A model can have many joint variables. These are sorted by joint, joint primitive, and primitive component. The variables are correspondingly named according to the scheme `jointName`.`primitiveType`.`primitiveComponent`. A gimbal joint, which has three revolute primitives (`Rx`, `Ry`, and `Rz`), each with a rotational component (`q`), allows for three joint variables. With `j1` for joint name, the variable identifiers become `j1.Rx.q`, `j1.Ry.q`, and `j1.Rz.q`.Joint primitives can also be prismatic (`Px`, `Py`, and `Pz`), spherical (`S`), constant-velocity (`CV`), or lead-screw (`LSz`). Primitive components can be translations (`p`), rotations (`q`), and axis components (`ax`). Spherical primitives are the only to allow rotation about a general 3-D axis, and so only they have axis components. These are denoted `ax_x`, `ax_y`, and `ax_z`. Other joint primitives have one component each—save for the constant-velocity primitive, which has an azimuth rotation component (`q_a`) and a bend rotation component (`q_b`).Joint variables can play different roles in the analysis. They can serve as targets, guesses, or outputs. As targets, they help to specify the multibody configuration for which to solve the output variables. As guesses, they help to bias the solver toward a desired solution—for example, to ensure that the elbow of a humanoid robot bends and extends only in the natural range of 0–145 degrees. As outputs, they add to the unknowns to be determined by the solver.The figure shows the variables of a general `KinematicsSolver` object. Target (T), guess (G), and output (O) variables can be joint variables (J) or frame variables (F). Joint variables are native to the object and can be assigned from its start as targets, guesses, and outputs. Frame variables must first be created with `addFrameVariables`.```

Input Arguments

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Name of the `KinematicsSolver` object for which to run the analysis. The object is a kinematic representation of the model from which it derives. It contains the variables upon which the analysis depends.

Example: 'fourBarKS'

Data Types: `char` | `string`