Moco User Guide

Table of Contents

• MocoTools
• Solving custom optimal control problems
• Defining a custom goal or cost
• Utilities
• Frequently Asked Questions

This guide shows the various ways of using Moco.

MocoTools

Moco provides easy-to-use tools for solving for muscle activity that can achieve an observed motion. See the following pages:

• MocoTrack: kinematics are tracked in the cost
• MocoInverse: kinematics are prescribed

These tools derive from the MocoTool class.

Solving custom optimal control problems

If the MocoTools do not satisfy your needs, you can create and solve your own custom optimal control problem using the MocoStudy class.

• MocoStudy: custom optimal control problems

Defining a custom goal or cost

Moco allows you to compose your cost from multiple existing cost terms. This gives you flexibility and means that you usually do not need to write your cost yourself, even if it has many terms. Moco's existing costs are ususally well-tested and work well with Moco's solvers, so we encourage you to use them if possible. In the case that you want to create your own custom cost term, you can derive from MocoGoal in C++.

If you do not want to write C++ code, you can prototype your cost in Matlab and we can help convert it to C++. See the Matlab example examplePrototypeCustomGoal.m for more information.

In the future, Moco could allow you to define custom cost terms in Python. If this is of interest to you, please let the Moco developers know (on GitHub).

Utilities

Moco contains utilities for creating models, modifying models, working with data, and postprocessing results.

1. ModelFactory: Create standard models and modify existing models.
2. ModelProcessor: Create a workflow of operations to perform on a model.
3. TableProcessor: Create a workflow of operations to perform on a table.
4. OpenSim::visualize: Visualize (animate) a MocoTrajectory.
5. OpenSim::analyze: Compute the values of Component outputs from a given MocoTrajectory.
6. plot_trajectory.py: Plot a MocoTrajectory with the Python Matplotlib plotting library.
7. report.py: Generate a detailed PDF report about a MocoTrajectory and any reference data (part of the opensim Python package).

Frequently Asked Questions

See Frequently Asked Questions.