14 IEEE CONTROL SYSTEMS MAGAZINE » DECEMBER 2006

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No special issue on process controlwould be complete without men-tioning Ziegler-Nichols tuning

rules, and no series of “25 Years Ago”columns in IEEE Control Systems Maga-zine (CSM) would be complete with-out recognizing Nathaniel B. Nichols,CSM’s first associate editor for controlsystems history. Nichols is coinventorof the Ziegler-Nichols tuning rules forPID controllers, father of the Nicholschart, and coauthor with Hubert Jamesand Ralph Phillips of volume 25 of theMIT Radiation Laboratory Series vol-ume Theory of Servomechanisms [1].

In 1980, Nichols was awarded thesecond AACC Control HeritageAward, now known as the Richard E.Bellman Control Heritage Award,“for distinguished lifetime career con-tributions to the technology or appli-cation of automatic control.” (HendrikBode was the first recipient in 1979.)In recognition of his award, the June1981 issue of IEEE CSM contained thefollowing short biography:

Nathaniel B. Nichols receivedhis B.S. degree from CentralMichigan University in 1936, hisM.S. degree from the Universityof Michigan in 1937, an Hon-orary Doctor of Science degreefrom Central Michigan Universi-ty in 1964 and an Honorary Doc-tor of Science degree from CaseWestern Reserve University in1968. He has worked with TheAerospace Corporation, DowChemical Company, MIT, TaylorInstrument Companies, Univer-sity of Minnesota, and RaytheonManufacturing Company. Hisprofessional experience includesautomatic control, automaticradar tracking and fire controlcomputers, power driven servo-mechanisms, industrial processcontrollers, recording and con-

trolling instruments, spacecraftattitude controls, space experi-ment controls and instruments.This short biography is understat-

ed to the extreme. Nichols was a giantin the field of control. The Nichols

chart is arguably the most usefulclosed-loop system design tool in thehistory of control, and Theory ofServomechanisms is probably the mostwidely read control-systems designdocument ever written [2].

The original Nichols chart, reprinted from the 1947 textbook by James, Nichols, and Phillips[1]. The curves show contours of constant closed-loop magnitude and constant closed-loopphase. To use the chart, the open-loop frequency response is plotted on the rectilinear gainand phase coordinates, while the closed-loop frequency response is read from the contoursof closed-loop magnitude and phase.

Nathaniel B. Nichols

DECEMBER 2006 « IEEE CONTROL SYSTEMS MAGAZINE 15

Nathaniel Nichols’s career wasfar more groundbreaking than theabove l ist suggests . In the late1930s, he worked at Taylor Instru-ments Company in Rochester as aprocess control engineer. There hemet chemical engineer John Ziegler,and together they developed andpublished simple techniques foradjusting automatic controllers forprocess control systems, whichbecame known as the Ziegler-Nichols tuning rules.

In the early 1940s, the companysent Nichols to use the MIT differen-tial analyzer, where he met CharlesStark Draper and Gordon Brown.Draper and Brown were so impressedwith Nichols that they insisted heremain at MIT to work at the Radia-

tion Laboratory during World War II.Nichols subsequently worked on twoof the Rad Lab's tracking radars,specifically, the ground-based SCR-584 and the ship-based Mark-56.

After the war, Nichols returned toTaylor Instruments for four yearsand then held a short-lived facultyposition at the University of Min-nesota. Ivan Getting, with whom hehad worked at the Radiation Labora-tory, convinced him to leave Min-nesota to become manager ofresearch at Raytheon Manufacturing.Nichols returned to Taylor Instru-ments in 1957 as chief engineer. In1963, he left Taylor to once again joinGetting, who was now at the Aero-space Corporation, where Nicholsstayed with the Control Systems

Division until his retirement. He wasassociate editor for control systemshistory of CSM from 1981 to 1986.Since 1996, IFAC has awarded theNathaniel Nichols Medal in recogni-tion of outstanding contributions todesign methods, software tools andinstrumentation, or to significantprojects resulting in major applica-tions and the advancement of controleducation. Nichols died on 17 April1997 after a prolonged illness.

REFERENCES[1] H.M. James, N.B. Nichols, and R.S. Phillips.Theory of Servomechanisms. New York: McGraw-Hill, 1947.[2] S. Kahne, “Remembering Nathaniel B. Nichols1914–1997,” IEEE Control Syst. Mag., vol. 18, no. 3,pp. 74–75, June 1998.

Kent H. Lundberg