When to make a step? Tackling the timing problem in multi-contact locomotion by TOPP-MPC

Stéphane Caron, Quang-Cuong Pham.

Abstract

We present a model predictive controller (MPC) for multi-contact locomotion where predictive optimizations are realized by time-optimal path parameterization (TOPP). A key feature of this solution is that, contrary to existing planners where step timings are provided as inputs, here the timing between contact switches is computed as output of a fast nonlinear optimization. This is particularly appealing to multi-contact locomotion, where proper timings depend on terrain topology and suitable heuristics are unknown. We show how to formulate legged locomotion as a TOPP problem and demonstrate the behavior of the resulting TOPP-MPC controller in simulations with a model of the HRP-4 humanoid robot.

HRP-4 walking a series of hills using the TOPP-MPC controller

Cite

@unpublished{caron2017hal,
  title = {When to make a step? Tackling the timing problem in multi-contact locomotion by TOPP-MPC},
  author = {Caron, St{\'e}phane and Pham, Quang-Cuong},
  year = {2017},
  month = {September},
  hal_id = {hal-01363757},
  hal_version = {v1},
  url = {https://hal.archives-ouvertes.fr/hal-01363757}
}
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