This paper examines a family of designs for magnetic cubes and counts how many configurations are possible for each design as a function of the number of modules. Magnetic modular cubes are cubes with magnets arranged on their faces. The magnets are positioned so that each face has either magnetic south or north pole outward. Moreover, we require that the net magnetic moment of the cube passes through the center of opposing faces. These magnetic arrangements enable coupling when cube faces with opposite polarity are brought in close proximity and enable moving the cubes by controlling the orientation of a global magnetic field. This paper investigates the 2D and 3D shapes that can be constructed by magnetic modular cubes, and describes all possible magnet arrangements that obey these rules. We select ten magnetic arrangements and assign a "color" to each of them for ease of visualization and reference. We provide a method to enumerate the number of unique polyominoes and polycubes that can be constructed from a given set of colored cubes. We use this method to enumerate all arrangements for up to 20 modules in 2D and 16 modules in 3D. We provide a motion planner for 2D assembly and through simulations compare which arrangements require fewer movements to generate and which arrangements are more common. Hardware demonstrations explore the self-assembly and disassembly of these modules in 2D and 3D.
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Closed-Loop Control of Magnetic Modular Cubes for 2D Self-Assembly
Reconfigurable modular robots can dynamically
assemble/disassemble to accomplish the desired task better.
Magnetic modular cubes are scalable modular subunits with
embedded permanent magnets in a 3D-printed cubic body and
can be wirelessly controlled by an external, uniform, timevarying
magnetic field. This paper considers the problem of
self-assembling these modules into desired 2D polyomino shapes
using such magnetic fields. Although the applied magnetic field
is the same for each magnetic modular cube, we use collisions
with workspace boundaries to rearrange the cubes. We present a
closed-loop control method for self-assembling the magnetic modular
cubes into polyomino shapes, using computer vision-based
feedback with re-planning. Experimental results demonstrate
that the proposed closed-loop control improves the success rate of
forming 2D user-specified polyominoes compared to an open-loop
baseline. We also demonstrate the validity of the approach over
changes in length scales, testing with both 10mm edge length
cubes and 2.8mm edge length cubes.
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- NSF-PAR ID:
- 10440445
- Editor(s):
- Ani Hsieh
- Date Published:
- Journal Name:
- IEEE Robotics and Automation Letters
- ISSN:
- 2377-3774
- Page Range / eLocation ID:
- 1 to 8
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1109/LRA.2023.3296008
