Automatic Control

Faculty of Engineering, LTH

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FRTN05 - Nonlinear Control and Servo Systems

Olinjär reglering och servosystem, 7.5 hp


In real life, most control systems are nonlinear in one way or the other (nonlinear dynamics, actuation saturations, sensor nonlinearities, etc). While a controller designed for linear systems may continue to work well in many nonlinear systems, this is not always the case. In some situations, nonlinear effects must be taken into account in order to get acceptable performance. In the course Nonlinear Control and Servo Systems (FRTN05) we study common nonlinearities and how to handle those, treat different analysis methods and learn how to do control synthesis for nonlinear systems, both in theory and practice.


2019-04-26 The re-take exam from 2019-04-24 has been graded. The results will be entered into LADOK in the beginning of next week. The solutions can be found here. The exam can be reviewed in the seminar room (M:2112B) on May 2,

2019-02-04. The occasion to review the exam was somewhat forgotten, and started later than announced, so if you got there at 12.30 and left, you can just come to office in the end of the second floor corridor to review your exam (2170E).

2019-01-30 The exam has been graded, and the results will shortly be entered into LADOK. If you would like to review your exam, there will be an opportunity to do so on Monday, Febuary 4, 12.30 in the seminar room (M:2112B).

2019-01-16 The exam with solutions is available here. The grading is expected to be done towards the end of next week.

2019-01-07: Extra session for questions Friday January 11 at 13.15-15.00 in the seminar room 2112B of Automatic Control.

2018-12-03: Sign-up for lab 3 is open.

2018-11-26: Sign-up for lab 2 is open.

2018-11-19: Sign-up for lab 1 is open.


Anders Rantzer, (course responsible) M-building (fifth floor, room 5143) 046 - 222 87 83

Teaching assistants 

Mattias Fält, M-building (second floor), 046-222 08 47
Olof Troeng, M-building (second floor), 046-222 97 43




Recommended textbook is

  • Glad, T., and Ljung,L., "Reglerteori: Flervariabla och olinjära metoder" (2003, Studentlitteratur, Lund, ISBN 9-14-403003-7) or the English translation "Control Theory: Multivariable and Nonlinear Methods", 2000, Taylor & Francis Ltd, ISBN 0-74-840878-9. Chapter 11-16,18. This book covers MPC and Optimal control which are not covered in the other text book. The first part of this book (Ch. 1-10) covers linear control theory and is useful for the course Multivariable Control - (FRTN10 Flervariabel reglering)

An alternative reference is

  • Khalil, H. K., Nonlinear Systems (3rd ed., 2002, Prentice Hall, ISBN 0-13-122740-8). This is a good textbook on nonlinear control systems, at a bit more advanced level than the course.

Handouts: Lecture notes and extra material will be handed out and posted on this website.

Lectures and Exercises

Lectures on Mondays are held at 13.15-15.00, other days at 08.15-10.00. Lectures are held in M:E (except for November 14 when it is in the Automatic Control seminar room M:2112B on the second floor in the M-building.)

The exercises are held Tuesdays and Wednesdays 15:15-17:00 in lab A and lab B of the Automatic Control Department, first floor of the M-building. See Exercise schedule and problem set.

The lecture slides will be handed out during the lectures. Below you find last edition's versions to be replaced when the lecture is given (indicated by red or green bullet).

 Monday 12/11: L4: Lyapunov methods. (2018)
 Wednesday 14/11: L5: Stability theory. Small gain theorem. Circle criteria. Passivity. (2018)
 Friday 16/11: L6: Describing function analysis. (2018)

 Monday 19/11: L7: Saturation and antiwindup. Friction. (2018)
 Wednesday 21/11: L8: Compensation for backlash and quantization. (2018)

Reading material on: antiwindup and friction

 Monday 26/11: L9: Lyapunov-based design and sliding modes. (2018)
 Wednesday 28/11: L10: Optimal control: The Maximum Principle, examples. (2018)

Lab1: Deadzone-compensation for an air throttle in a car. (2018)

 Monday 3/12:L11: Optimal control (cont'd). (2018)
D. Liberzon, Calculus of variations and optimal control theory: A Coincise Introduction, Princeton University Press, 2012.

 Wednesday 5/12: L12: Dynamic programming. (2018)

Lab2 : Pendulum swing-up

 Monday 10/12: L13: Internal model control. Model predictive control. Nonlinear observers. Gain scheduling. (2018)
 Wednesday 12/12: L14: Course summary. (2018)

Lab 3: Optimal control of pendulum an a cart.


Exercises and Solutions

Exercise schedule and problem set


 Lab1: Deadzone-compensation for an air throttle in a car (nonlinear compensation and describing function analysis) Sign-up
 Lab2: Pendulum swing-up (Sign-up starts November 26) Sign-up
 Lab3: Pendulum on a cart (Sign-up starts December 3)



Matlab and Simulink are extensively used in the course, and can be obtained from here using your StiL/Lucat-account.

Graphical user interfaces called pplane and dfield for phase-plane analysis have been developed at Rice University,, and are available for academic use.

For MATLAB 2017a and onwards, use the following versions: pplane9.m and dfield9.m.
For MATLAB 2014b-2016b, use the following versions: pplane8.m and dfield8.m.

Old Exams

March 7, 2012 
April 5, 2013
Mar 12, 2014
Jan 13, 2016

Jan 10, 2017

Jan 3, 2018



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