Nonsmooth Optimal Value and Policy Functions in Mechanical Systems Subject to Unilateral Constraints

State-of-the-art approaches to optimal control use smooth approximations of value and policy functions and gradient-based algorithms for improving approximator parameters. Unfortunately, we show that value and policy functions that arise in optimal control of mechanical systems subject to unilateral...

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Bibliographic Details
Published in:IEEE control systems letters Vol. 4; no. 2; pp. 506 - 511
Main Authors: Banjanin, Bora S., Burden, Samuel A.
Format: Journal Article
Language:English
Published: IEEE 01.04.2020
Subjects:
Cost function
Force
Heuristic algorithms
hybrid systems
Mechanical systems
Optimal control
robotics
Robots
Trajectory
ISSN:2475-1456, 2475-1456
Online Access:Get full text
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Summary:State-of-the-art approaches to optimal control use smooth approximations of value and policy functions and gradient-based algorithms for improving approximator parameters. Unfortunately, we show that value and policy functions that arise in optimal control of mechanical systems subject to unilateral constraints - i.e., the contact-rich dynamics of robot locomotion and manipulation - are generally nonsmooth due to the underlying dynamics exhibiting discontinuous or piecewise-differentiable trajectory outcomes. Simple mechanical systems are used to illustrate this result and the implications for optimal control of contact-rich robot dynamics.
ISSN:2475-1456
2475-1456
DOI:10.1109/LCSYS.2019.2960442