Research
dm_control: Software and Tasks for Continuous Control
Overview
A public colab notebook with a tutorial for dm_control software is available here.
Infrastructure
- An autogenerated MuJoCo Python wrapper provides full access to the underlying engine.
- PyMJCF is a Document Object Model, wherein a hierarchy of Python Entity objects corresponds to MuJoCo model elements.
- Composer is the high-level “game engine” which streamlines the composing of Entities into scenes and the defining observations, rewards, terminations and general game logic.
- The Locomotion framework introduces several abstract Composer entities such as the Arena and Walker, facilitating locomotion-like tasks.
Environments
- The Control Suite, including a new quadruped and dog environment.
- Several locomotion tasks, including soccer.
- Single arm robotic manipulation tasks using snap-together bricks.
Highlights
Named Indexing
Exploiting MuJoCo’s support of names for all model elements, we allow strings to index and slice into arrays. So instead of writing:
"fingertip_height = physics.data.geom_xpos[7, 2]"
...using obscure, fragile numerical indexing, you can write:
"fingertip_height = physics.named.data.geom_xpos['fingertip', 'z']"
leading to a much more robust, readable codebase.
PyMJCF
The PyMJCF library creates a Python object hierarchy with 1:1 correspondence to a MuJoCo model. It introduces the attach() method which allows models to be attached to one another. For example, in our tutorial we create procedural multi-legged creatures by attaching legs to bodies and creatures to the scene.
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Composer
Composer is the “game engine“ framework, which defines a particular order of runtime function calls, and abstracts the affordances of reward, termination and observation. These abstractions allowed us to create useful submodules:
composer.Observable: An abstract observation wrapper which can add noise, delays, buffering and filtering to any sensor.
composer.Variation: A set of tools for randomising simulation quantities, allowing for agent robustification and sim-to-real via model variation.
Diagram showing the life-cycle of Composer callbacks. Rounded rectangles represent callbacks that Tasks and Entities may implement. Blue rectangles represent built-in Composer operations.
Locomotion
The Locomotion framework introduced the abstractions:
Walker: A controllable entity with common locomotion-related methods, like projection of vectors into an egocentric frame.
Arena: A self-scaling randomised scene, in which the walker can be placed and given a task to perform.
For example, using just 4 function calls, we can instantiate a humanoid walker, a WallsCorridor arena and combine them in a RunThroughCorridor task.
Watch
New Control Suite domains
Quadruped
- A generic quadruped domain with a passively stable body.
- Several pure locomotion tasks (e.g. walk, run).
- An escape task requiring rough terrain navigation.
- A fetch task requiring ball dribbling.
Watch
Dog
- An elaborate model based on a skeleton commissioned from leo3Dmodels.
- A challenging ball-fetching task that requires precision grasping with the mouth.
Watch
Showcase
A fast-paced montage of dm_control based tasks from DeepMind:
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