Combining pontryagin's principle and dynamic programming for linear and nonlinear systems
File(s)DP_PMP_TAC.pdf (2.94 MB)
Accepted version
Author(s)
Sassano, Mario
Astolfi, Alessandro
Type
Journal Article
Abstract
To study optimal control and disturbance attenuation problems, two prominent-and somewhat alternative-strategies have emerged in the last century: dynamic programming (DP) and Pontryagin's minimum principle (PMP). The former characterizes the solution by shaping the dynamics in a closed loop (a priori unknown) via the selection of a feedback input, at the price, however, of the solution to (typically daunting) partial differential equations. The latter, instead, provides (extended) dynamics that must be satisfied by the optimal process, for which boundary conditions (a priori unknown) should be determined. The results discussed in this article combine the two approaches by matching the corresponding trajectories, i.e., combining the underlying sources of information: knowledge of the complete initial condition from DP and of the optimal dynamics from PMP. The proposed approach provides insights for linear as well as nonlinear systems. In the case of linear systems, the derived conditions lead to matrix algebraic equations, similar to the classic algebraic Riccati equations (AREs), although with coefficients defined as polynomial functions of the input gain matrix, with the property that the coefficient of the quadratic term of such equation is sign definite, even if the corresponding coefficient of the original ARE is sign indefinite, as it is typically the case in the H ∞ control problem. This feature is particularly appealing from the computational point of view, since it permits the use of standard minimization techniques for convex functions, such as the gradient algorithm. In the presence of nonlinear dynamics, the strategy leads to algebraic equations that allow us to (locally) construct the optimal feedback by considering the behavior of the closed-loop dynamics at a single point in the state space.
Date Issued
2020-12-01
Date Acceptance
2020-08-29
Citation
IEEE Transactions on Automatic Control, 2020, 65 (12), pp.5312-5327
ISSN
0018-9286
Publisher
Institute of Electrical and Electronics Engineers
Start Page
5312
End Page
5327
Journal / Book Title
IEEE Transactions on Automatic Control
Volume
65
Issue
12
Copyright Statement
© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000595526300020&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Technology
Automation & Control Systems
Engineering, Electrical & Electronic
Engineering
Optimal control
Partial differential equations
Regulators
Symmetric matrices
Dynamic programming
Attenuation
Mathematical model
Disturbance attenuation
nonlinear control systems
optimal control
Riccati equations
H-INFINITY-CONTROL
MAXIMUM PRINCIPLE
FEEDBACK
EQUATION
Publication Status
Published
Date Publish Online
2020-09-03