Delta robot

Looped linkages

Three driven arms swing a level platform in circles on parallelogram forearms.

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Loop

The steel preset (the default), recordedon an NVIDIA RTX PRO 6000 Blackwell.

Run it

cd examples
# the default preset (steel), then the others
uv run shelf play loop_delta_robot
# change solver settings live
uv run shelf tune loop_delta_robot

Source: examples/shelf/05_looped_linkages/loop_delta_robot/ · ported from common/loop_mechanisms.py, mechanism delta

Presets

Preset	Solver	Status	Checked
steeldefault	steel	works	2026-11-10, newton f6fc82a8b, NVIDIA RTX PRO 6000 Blackwell Server Edition

Solvers with no row are untested on this example. The full settings are inpresets.toml.

Code

example.py

examples/shelf/05_looped_linkages/loop_delta_robot/example.py

# SPDX-FileCopyrightText: Copyright (c) 2026 Skild AI and the Steel contributors
# SPDX-License-Identifier: Apache-2.0

###########################################################################
# Example Delta robot
#
# Three driven upper arms carry a 0.3 kg platform through parallelogram forearms (ball joints at the
# elbows, universal joints at the platform). Five ball closures, nearly redundant rows; 3 DOF.
#
# The mechanism comes from common/loop_mechanisms.py and runs through common/loop_linkage.py. check compares
# the tracked bodies with reference.json, an exact-constraint reference integration.
#
# Command: python -m shelf run loop_delta_robot
#
###########################################################################

from typing import ClassVar

import newton.examples

from common.loop_linkage import LoopLinkageExample


class Example(LoopLinkageExample):
    file = __file__
    mechanism = "delta"
    period = 10.0  # [s] the trajectory repeats with this period once its one-second ramp is over
    camera: ClassVar = {"eye": (-0.248, -0.681, 0.814), "target": (0.0, 0.0, 0.62)}


if __name__ == "__main__":
    parser = Example.create_parser()
    viewer, args = newton.examples.init(parser)
    newton.examples.run(Example(viewer, args), args)

example.py on GitHub

presets.toml

examples/shelf/05_looped_linkages/loop_delta_robot/presets.toml

example = "loop_delta_robot"
source = "common/loop_mechanisms.py, mechanism delta"
default = "steel"

[check]
# Arguments `python -m shelf check` passes in test mode: a 4 s run, the frames in reference.json.
args = ["--num-frames", "200"]

[gallery]
short = "Three driven arms swing a level platform in circles on parallelogram forearms."
title = "Delta robot"
frame = 75

[xpbd]
status = "untested"

[vbd]
status = "untested"

[mujoco]
status = "untested"

[featherstone]
status = "untested"

[semi_implicit]
status = "untested"

[feather_pgs]
status = "untested"

[steel]
status = "works"
# loop-closing joints need the "immediate" response (this Newton's Steel enforces BALL and REVOLUTE closures only there).
# 2 substeps x 28 iterations: the fastest setting (RTX PRO 6000 sweep, 2026-11-07, mean 0.71 ms per frame) within
# 0.5 mm of the exact reference on the platform (0.38 mm) and a 0.25 mm loop gap (0.17 mm) with some margin; 1 x 64
# (0.54 ms) sits on the edge (0.50 mm) and 1 x 48 misses (0.68 mm). The parallelogram rows are nearly redundant, so
# the gap closes slowly with iterations. Tuned with solve_mode "split", which newton f6fc82a8b removed (it runs
# "serial"); re-checked there at 0.72 ms.
sim = { fps = 50, substeps = 2 }
solver = { solve_mode = "serial", iterations = 28, articulated_contact_response = "immediate" }
checked = "2026-11-10, newton f6fc82a8b, NVIDIA RTX PRO 6000 Blackwell Server Edition"

[kamino]
status = "untested"

[implicit_mpm]
status = "untested"

[style3d]
status = "untested"

presets.toml on GitHub

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