MJCF import: auto-enable actuator *limited flags when *range is specified in MJCF by adenzler-nvidia · Pull Request #1504 · newton-physics/newton

adenzler-nvidia · 2026-01-30T16:19:06Z

Implements MuJoCo's auto-inference behavior: if ctrllimited/forcelimited/actlimited is not explicitly set in MJCF but the corresponding range attribute has valid values (range[0] < range[1]), automatically enable the limit flag.

This matches native MuJoCo behavior where specifying a range implicitly enables the corresponding limit unless explicitly disabled.

Changes:

Add resolution logic in MJCF parser after parsing custom attributes
Add comments to solver_mujoco.py custom attribute definitions

Tests:

test_ctrllimited_auto_enabled_when_ctrlrange_specified
test_ctrllimited_not_auto_enabled_without_ctrlrange
test_ctrllimited_explicit_false_not_overridden
test_forcelimited_auto_enabled_when_forcerange_specified
test_actlimited_auto_enabled_when_actrange_specified

Before your PR is "Ready for review"

Necessary tests have been added and new examples are tested (see newton/tests/test_examples.py)
Documentation is up-to-date
Code passes formatting and linting checks with pre-commit run -a

Summary by CodeRabbit

Bug Fixes
- Actuator limitation flags are now auto-enabled when corresponding range constraints are present in MuJoCo MJCF, improving model parsing.
Documentation
- Clarified MJCF attribute defaults with inline comments to explain parser behavior.
Tests
- Added and updated tests covering actuator auto-enablement and adjusted expectations/renamed a test to reflect override behavior.

coderabbitai · 2026-01-30T16:19:25Z

📝 Walkthrough

Walkthrough

Adds automatic resolution of MuJoCo actuator limited flags (ctrllimited, forcelimited, actlimited) based on corresponding range attributes when the limited flags are not explicitly specified; adds inline MJCF comments and new tests validating this behavior.

Changes

Cohort / File(s)	Summary
Documentation & Comments `newton/_src/solvers/mujoco/solver_mujoco.py`	Inserted inline comments next to three `default=0` MJCF actuator attribute declarations noting the MJCF parser auto-enables these when corresponding ranges are provided.
Core Implementation `newton/_src/utils/import_mjcf.py`	In `parse_actuators`, added logic to auto-set `ctrllimited`, `forcelimited`, and `actlimited` to 1 when their respective range attributes (`ctrlrange`, `forcerange`, `actrange`) are present with valid bounds and the limited flags are not explicitly specified.
Tests `newton/tests/test_import_mjcf.py`	Added `TestMjcfActuatorAutoLimited` with tests for auto-enabling/disabling of actuator limited flags and explicit overrides; updated `TestMjcfActuatorClassDefaults` assertions to expect integer biasprm values and renamed one test to reflect override behavior.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

fix: add class default inheritance for actuator parsing in MJCF #1503: Modifies parse_actuators in import_mjcf.py and adjusts actuator-related parsing/tests — overlaps with actuator flag resolution changes.
Add passive stiffness and damping support for joints in MuJoCo solver #1082: Also alters parse_actuators and actuator handling logic; related to range/limited attribute processing.
Add parsing actuators from MJCF #1432: Touches MJCF actuator parsing and MuJoCo solver actuator attributes, overlapping similar code paths.

Suggested reviewers

jvonmuralt
eric-heiden

🚥 Pre-merge checks | ✅ 3

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Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly and accurately summarizes the main change: auto-enabling actuator limited flags based on range specifications in MJCF imports.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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… MJCF Implements MuJoCo's auto-inference behavior: if ctrllimited/forcelimited/actlimited is not explicitly set in MJCF but the corresponding range attribute has valid values (range[0] < range[1]), automatically enable the limit flag. This matches native MuJoCo behavior where specifying a range implicitly enables the corresponding limit unless explicitly disabled. Changes: - Add resolution logic in MJCF parser after parsing custom attributes - Add comments to solver_mujoco.py custom attribute definitions Tests: - test_ctrllimited_auto_enabled_when_ctrlrange_specified - test_ctrllimited_not_auto_enabled_without_ctrlrange - test_ctrllimited_explicit_false_not_overridden - test_forcelimited_auto_enabled_when_forcerange_specified - test_actlimited_auto_enabled_when_actrange_specified

codecov · 2026-01-30T16:35:57Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

📢 Thoughts on this report? Let us know!

eric-heiden · 2026-02-03T16:52:48Z

Depending if #1510 gets merged before, these limited flags I think should be boolean custom attributes. I've changed that in #1510.

coderabbitai

Actionable comments posted: 2

🤖 Fix all issues with AI agents

In `@newton/_src/utils/import_mjcf.py`:
- Around line 1871-1884: The limit auto-enable logic is incorrectly reading
actuator_elem.attrib directly and checking for limited_attr there, which ignores
defaults; update the loop that resolves ("ctrllimited","ctrlrange",...),
("forcelimited","forcerange",...), ("actlimited","actrange",...) to use
merged_attrib for both the presence check and for reading the range string
(i.e., check if limited_attr not in merged_attrib and get range_str =
merged_attrib.get(range_attr, "")), then keep the existing parsing and setting
parsed_attrs[limited_key] = 1 when range_vals[0] < range_vals[1]; this ensures
default-derived range and limited flags are respected for actuator_elem.

In `@newton/tests/test_import_mjcf.py`:
- Around line 4361-4478: The tests in TestMjcfActuatorAutoLimited access
model.mujoco.actuator_* arrays but never call
SolverMuJoCo.register_custom_attributes, so add a registration step before the
tests run (e.g., in a class-level setUpClass or a shared helper invoked at the
top of each test) to ensure MuJoCo actuator custom attributes are registered;
call SolverMuJoCo.register_custom_attributes(...) once before using
ModelBuilder().add_mjcf()/finalize() in tests like
test_ctrllimited_auto_enabled_when_ctrlrange_specified,
test_ctrllimited_not_auto_enabled_without_ctrlrange,
test_ctrllimited_explicit_false_not_overridden,
test_forcelimited_auto_enabled_when_forcerange_specified, and
test_actlimited_auto_enabled_when_actrange_specified.

…fied in MJCF (newton-physics#1504)

adenzler-nvidia force-pushed the fix/mjcf-actuator-auto-limited branch from e48ebd1 to 3fa2891 Compare January 30, 2026 16:25

adenzler-nvidia requested a review from jvonmuralt January 30, 2026 16:39

adenzler-nvidia mentioned this pull request Jan 30, 2026

We do not support parsing autolimits from mjcf #1374

Closed

eric-heiden previously approved these changes Feb 3, 2026

View reviewed changes

adenzler-nvidia dismissed eric-heiden’s stale review via 3dd6c95 February 5, 2026 11:53

coderabbitai Bot reviewed Feb 5, 2026

View reviewed changes

Comment thread newton/_src/utils/import_mjcf.py

Comment thread newton/tests/test_import_mjcf.py

Merge main into fix/mjcf-actuator-auto-limited

2583712

adenzler-nvidia force-pushed the fix/mjcf-actuator-auto-limited branch from 3dd6c95 to 2583712 Compare February 5, 2026 12:24

adenzler-nvidia enabled auto-merge February 5, 2026 12:57

adenzler-nvidia disabled auto-merge February 5, 2026 12:57

jvonmuralt approved these changes Feb 5, 2026

View reviewed changes

adenzler-nvidia added this pull request to the merge queue Feb 5, 2026

Merged via the queue into newton-physics:main with commit 7a82df9 Feb 5, 2026
22 checks passed

dylanturpin pushed a commit to dylanturpin/newton-collab that referenced this pull request Feb 13, 2026

MJCF import: auto-enable actuator *limited flags when *range is speci…

b6f7052

…fied in MJCF (newton-physics#1504)

vreutskyy mentioned this pull request Feb 16, 2026

Support parsing autolimits from MJCF #1651

Merged

4 tasks

This was referenced Feb 18, 2026

Fix implicit biastype for position/velocity actuator shortcuts #1678

Merged

Support dampratio for position/velocity actuator shortcuts #1722

Merged

Resolve inheritrange for position actuators in MJCF parser #1727

Merged

This was referenced Feb 25, 2026

Fix default kp/kv for position and velocity actuators #1786

Merged

Fix for MJCF actuator custom attributes #1783

Merged

mmacklin pushed a commit to mmacklin/newton that referenced this pull request Apr 7, 2026

MJCF import: auto-enable actuator *limited flags when *range is speci…

bc3f747

…fied in MJCF (newton-physics#1504)

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MJCF import: auto-enable actuator limited flags when range is specified in MJCF#1504

MJCF import: auto-enable actuator limited flags when range is specified in MJCF#1504
adenzler-nvidia merged 2 commits into
newton-physics:mainfrom
adenzler-nvidia:fix/mjcf-actuator-auto-limited

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