Orbital Research Adaptive Nonlinear Control - Manual

R
ecent research into the development of systematic design for global adaptive
control of nonlinear systems with parametric uncertainty at Case Western
Reserve University has resulted in the development of a nonsmooth framework for
global adaptive control of a significant class of nonlinearly parameterized systems.
Orbital Research, Inc., in conjunction with Case Western Reserve University is
currently developing a family of Nonlinear Adaptive Control algorithms for
underactuated mechanical systems based upon this ground breaking research.
Nonlinear control techniques for global
regulation of underactuated systems
Orbital Research, Inc.
4415 Euclid Ave., Suite 500
leveland, OH 44103-3733 C
Contact: Frederick J. Lisy, Ph.D.
Telephone (216) 649-0399
E-mail [email protected]
www.orbitalresearch.com
Copyright 2003
Rev C: RMK-12-05-03
Underactuated Systems Control
Nonlinear Adaptive Control
The pursuit of more capable and versatile systems is driving the need
for more and more capable control system design techniques. In
particular, control systems are becoming increasing important for
bridging gaps left by design tradeoffs. One example of particular
interest is the control of a vehicle mounted gun or mortar on a Light
Armored Vehicle (LAV). In this application, the transportability of the
LAV is of paramount importance and hence, any gun/mount system
must be made as light as possible. For the lightweight application
envisioned with the LAV, a lighter, and therefore, more flexible
structure is necessary to satisfy weight constraints. Unfortunately,
the lighter, more flexible structure does not supply a suitable ground
for more traditional controllers such as those used to control the
main guns of heavier fighting vehicles that possess heavier and more
rigid gun mount structures. In order to adequately control gun
attitude on the LAV, a control scheme capable of accommodating the
system compliance over a large range of operating conditions is
needed.
Orbital Research, Inc. (ORI), in conjunction with Case Western
Reserve University (CWRU), is developing a suite
that have a tremendous number of
applications. In particular, they are ideally suited for underactuated
systems, i.e. for systems that possess more degrees of freedom than
control inputs. This type of system occurs frequently in mechanical
systems that possess structural flexibility or in the design of fault
tolerant controllers to accommodate the loss of actuation. For
example, crane booms can have significant flexibility and typically
have no actuation designed to control the boom dynamics. Another
example is the control of a fighter aircraft, in combat scenarios it may
be necessary to control a damaged aircraft that has, for example, lost
an engine and has damage to one of its wings. The undamaged
control surfaces can be used to compensate for the engine loss,
asymmetric flow resulting from wing damage, as well as the loss of
control surfaces via higher order coupling effects in the fighter
aerodynamics. In both of these cases, it may be impossible to
stabilize the systems via any smooth static or dynamic feedback.
ORI’s approach to nonlinear adaptive control design is markedly
different from the majority of systematic design methods for global
adaptive control of nonlinear systems with parametric uncertainty.
Typical approaches concentrated on adaptive control of feedback
linearizable systems with linear parameterization using
.
In contrast, the control methodology discussed here focuses on the
development of but continuous adaptive control
schemes for nonlinearly parameterized systems. The approach
combines a recently developed extension to the technique of
a
nonlinear
adaptive controllers
smooth
feedback
nonsmooth
adding
The majority of the commercially available controllers are
smooth or at least C and many inherently nonlinear systems cannot
be stabilized by any smooth static or dynamic state feedback. The
control design methodology discussed here assumes only continuous
(C ) feedback.
1
0
New nonlinear adaptive control
techniques can accomodate nonlinear
structural flexibility in applications such
as light weight gun-mounts for LAV’s.
The adaption mechanism provides a means of producing fault tolerant
controllers for unmanned air vehicles including high altitude airships.