2013 ACC Workshop
Active Disturbance Rejection Control
Opening Remarks
Centrality of Disturbance Rejection
Zhiqiang Gao
June 15, 2013
Center for Advanced Control Technologies
http://cact.csuohio.edu
What makes automatic
control possible?
disturbance
the interruption of a settled and peaceful
condition.
Oxford Dictionary of English (3 ed.)
automatic control
makes a system run in a settled and peaceful
condition.
the problem of automatic control
is
the problem of disturbance
dealing with the problem of disturbance
• attenuate, mitigate, compensate feedback, PID
means: controller (partial, passive)
• reject, counter, cancel
ADRC
means: rejector (total, active)
attenuated, mitigated, compensated
Principle of disturbance attenuation, Watt, 1780s
disturbance
speed error
steam valve
reject
– from reicere, re- '‘back’ ' + jacere '‘to throw’'.
Oxford Dictionary of English (3 ed.)
disturbance rejection
throw it back, not merely accommodate it
throw it back: South-Pointing Chariot
throw it back: Isochronous Govenor
J.V. Poncelet
Mathematician, Physicist
Engineer
“Introduction to Industrial
Mechanics”, 1829
Analyzed steam engine
Isochronous Governor
measure and reject
disturbance
throw it back: dual channel principle
B. N. Petrov, Russian scientist
Academician of USSR, co-founder of Soviet
space program; worked with Sergei Korolev
on R-7 rocket in Sputnik Program (lunar
rover, Apollo–Soyuz, etc)
Practical use of invariance theory
1953, “dual channel principle of control”,
based on invariance theory, one of the
pillars of soviet automatic control
Using his authority, published results of his
work and insisted on rehabilitating
Shipanov’s name and his scientific work
In 1958, organized the first meeting in Kiev
on invariance
In 1966, the theory of invariance was
recognized as a discovery and the proper
patent was issued (13 years after Shipanov
died)
Principle of Disturbance Rejection
South Pointing Chariot, 2700s BC
Isochronous Governor, 1829
Invariance Principle, 1939
Unknown Input Observer, 1970s
Disturbance Observer, 1987
Active Disturbance Rejection, 1989-1998
Two Pillars of Automatic Control
Principle of Disturbance Attenuation
Implementation: Controller
Principle of Disturbance Rejection
Implementation: Rejector
A Copernican Revolution in AC
Geocentric vs. Heliocentric
Model-centric vs. Control-centric
Model
Control
Revolving Planets
Model-Centric
1) optimal control
2) robust control
3) adaptive control
4) nonlinear control
5) intelligent control
6) decoupling control
7) internal model
8) model predictive
9) stochastic control
Control-Centric
1) linear
2) nonlinear
3) time varying
4) time invariant
5) SISO
6) MIMO
7) certain
8) uncertain
Active Disturbance Rejection:
A Copernican Moment in Automatic Control
Reference
Generator
Controller,
of Chained
Integrators
The Enforced Plant:
Chained Integrators
Input
-
Dist. est.
State est.
Rejector
External
Disturbance
Process
Internal
Disturbance
Total
Disturbance
Estimator
Output
Concluding Remarks
What is Automatic Control Anyway?
Not just feedback
Not even just feedback control
Not has to be couched in math symbols
Not has to be model-centric
Not a decoration on ivory tower
In this workshop, we’ll what it is!