Session: MR-05/MSNDC-08-02 Motion Planning, Dynamics, and Control of Robots

Paper Number: 70733

Start Time: August 19, 11:10 AM

70733 - Optimal Control of a 5-Link Biped Using Quadratic Polynomial Model of Two-Point Boundary Value Problem 

To walk over-constrained environments, bipedal robots must meet concise control objectives of speed and foot placement. The decisions made at the current step need to factor in their effects over a time horizon. Such step-to-step control is formulated as a two-point boundary value problem (2BVP). As the dimensionality of the biped increases, it becomes increasingly difficult to solve this 2-two-point boundary value problem (2BVP) in real-time. The common method to use a simple linearized model for real-time planning followed by mapping on the high dimensional model cannot capture the nonlinearities and leads to potentially poor performance for fast walking speeds. In this paper, we present a framework for real-time control based on using partial feedback linearization for model reduction, followed by a data-driven approach to find a quadratic polynomial model for the 2-BVP. This simple step-to-step model along with constraints is then used to formulate and solve a quadratically constraint quadratic program to generate real-time control commands. We demonstrate the efficacy of the approach in simulation on a 5-link biped following a reference velocity profile and on a terrain with ditches. Future work will explore hardware implementation of the approach. A short video is here posted on this link: https://youtu.be/-UL-wkv4XF8

Presenting Author: Ernesto Hernandez-Hinojosa University of Illinois at Chicago

Authors:

Ernesto Hernandez-Hinojosa University of Illinois at Chicago
Aykut Satici Boise State University
Pranav Bhounsule University of Illinois at Chicago