Modlab The Modular Robotics Laboratory at the University of Pennsylvania

Self re-Assembly after Explosion
Self re-Assembly after Explosion
A car bumper is designed to crumple upon impact and protect the driver. A ski boot will detach from the ski to prevent injury to the ankle. Likewise a CKbot assembly falls apart when it is kicked, however CKbot can put itself back together again.

One of the grand challenges of modular self-reconfigurable robots is the ability for a system to repair itself after being exploded into many pieces. The effort to solve this grand challenge pushes the technical ability for integrated systems to plan and execute self-assembling hardware and software under unstructured conditions. Solving the challenge will show an unprecedented level of robustness in a robotic system. Robustness is one of the three promises of self-reconfiguring modular robotic systems, the others being versatility and low cost.

This project investigates the issues involved and an implementation towards this goal.

Robotic Self-assembly After Explosion (SAE)

The SAE problem involves a system putting itself back together after being exploded. The main word to define is explosion. Explosion in this context is defined as the rapid randomized disassembly of a system from a high-energy event.

Grand challenges are often best described by what a demonstration of a solution would look like. For the SAE problem, the solution would show this sequence:

1) Doing a task.
2) Being exploded into many pieces.
3) Self-repair (self-assembly).
4) Resuming the original, pre-explode task.

One of the main aspects of the solution is what we call structured disassembly. Some may argue that rather than spend efforts to efforts should be spent to make sure the system won’t break into pieces in the first place. One response to this argument is that there may be unexpected conditions in which forces are larger than planned for, such as an earthquake or terrorist activity. Even beyond this, there are situations where breaking apart may be desired. Just as car bumpers are made to crumple to absorb the energy of an impact, the disassembly of specific bonds holding a structure together may also absorb the energy of an impact. Ski boot detachment devices are an example of a system where structured disassembly helps to protect more fragile components, such as injury to feet and legs. Here, an important metric in analyzing the level of recoverable explosion is the amount of energy absorbed by the breaking of bonds.

Related Projects

CKbot: SAE is performed using CKbot modules

Related Papers:

  • M. Yim, B. Shirmohammadi, J. Sastra, M. Park, M. Dugan, and C. J. Taylor, “Towards robotic self-reassembly after explosion,” in Video proc. of the ieee/rsj intl. conf. on intelligent robots and systems (iros), San Diego CA, 2007.
    [BibTeX] [Download PDF]
    author = {M. Yim and B. Shirmohammadi and J. Sastra and M. Park and M. Dugan and C.J. Taylor},
    title = {Towards Robotic Self-reassembly After Explosion},
    booktitle = {Video Proc. of the IEEE/RSJ Intl. Conf. on Intelligent Robots and Systems (IROS)},
    address = {San Diego CA},
    year = {2007},
    url = {}

  • B. Shirmohammadi, C. J. Taylor, M. Yim, J. Sastra, and M. Park, “Using smart cameras to localize self-assembling modular robots,” in Proc. of acm/ieee interantional conference on distributed smart cameras (icdsc07), 2007. doi:10.1109/ICDSC.2007.4357508
    [BibTeX] [Download PDF]
    author = {B. Shirmohammadi and C.J. Taylor and M. Yim and J. Sastra and M. Park},
    title = {Using Smart Cameras to Localize Self-Assembling Modular Robots},
    booktitle = {Proc. of ACM/IEEE Interantional Conference on Distributed Smart Cameras (ICDSC07)},
    year = {2007},
    url = {},
    doi = {10.1109/ICDSC.2007.4357508},