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Aaron Johnson

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Standing Self-Manipulation for a Legged Robot

Proceedings of the 2012 IEEE/RSJ Intl. Conference on Intelligent Robots and Systems

October, 2012

Aaron M. Johnson*, G. Clark Haynes†, D. E. Koditschek*
*: Electrical and Systems Engineering, University of Pennsylvania
†: National Robotics Engineering Center, Carnegie Mellon University
Full PDF | IEEE Xplore

Abstract
       On challenging, uneven terrain a legged robotís open loop posture will almost inevitably be inefficient, due to uncoordinated support of gravitational loads with coupled internal torques. By reasoning about certain structural properties governing the infinitesimal kinematics of the closed chains arising from a typical stance, we have developed a computationally trivial self-manipulation behavior that can minimize both internal and external torques absent any terrain information. The key to this behavior is a change of basis in torque space that approximates the partially decoupled nature of the two types of disturbances. The new coordinates reveal how to use actuator current measurements as proprioceptive sensors for the approximate gradients of both the internal and external task potential fields, without recourse to further modeling. The behavior is derived using a manipulation framework informed by the dual relationship between a legged robot and a multifingered hand. We implement the reactive posture controller resulting from simple online descent along these proprioceptively sensed gradients on the X-RHex robot to document the significant savings in standing power.
This work was supported primarily by the DARPA Maximum Mobility and Manipulation Seedling project, with continued support by the ARL/GDRS RCTA project under Cooperative Agreement Number W911NF- 0–2−0016. The second author was funded by an Intelligence Community Postdoctoral Research Fellowship HM1582–08–1−0034.
BibTeX entry
@inproceedings{paper:johnson-iros-2012,
  author       = {Aaron M. Johnson and G. Clark Haynes and D. E. Koditschek},
  title        = {Standing Self-Manipulation for a Legged Robot},
  booktitle    = {Proceedings of the IEEE/RSJ Intl. Conference on Intelligent Robots and Systems},
  month        = {October},
  year         = {2012},
  address      = {Algarve, Portugal},
  doi          = {10.1109/IROS.2012.6386214}, 
  pages        = {272--279}
}

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