Force Control and Bilateral Teleoperation (EE 628)

2020 Fall
Faculty of Engineering and Natural Sciences
Electronics Engineering(EE)
Volkan Pato─člu,
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Doctoral, Master
Formal lecture
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This course is designed to equip students with fundamental theories and computational methodologies that are used in (computer aided) analysis and synthesis of force controlled and bilaterally teleoperated systems. By the end of the course a solid understanding of the principles of force/bilateral control in the context of modern classical control and hands on experience with implementation of force/bilateral controllers on force feedback devices are aimed. Covered topics include fundamental limitations of feedback control, explicit force control, implicit force control, impedance control, admittance control, reaction force observers, scaled teleoperation architectures, trade-off between robust stability and transperancy, physics based simulation of virtual environments, haptics rendering, passivity of the human-in-the-loop sampled data system, destabilizing effects of communication/computation delays and approaches to compensate for these time delays, namely, time domain passivity and wave variable approaches. The course is appropriate for students in any engineering discipline with interests in robotics, nonlinear controls, and haptics.


This course is designed to equip students with fundamental theories and computational methodologies that are used in human-machine interfaces and teleoperation systems. Students will learn how to analyze and synthesize controllers for human-machine interfaces as well as how to implement them in real time.

Students will be introduced to explicit and implicit force controllers, force observers, impedance/admittance control, haptic rendering, four/two-channel teleoperator architectures, scaling and time delay in teleoperation. Fundamental limitations of feedback control systems, robust stability and transperancy tradeoff of teleoperation systems will be studied.

Primary application areas of haptic interfaces and teleoperators include rehabilitation and manual task training (including flight and surgery training). Teleoperators are also commonly employed as interfaces of micro/nano manipulators. Addition of force feedback to these interfaces improve sense of immersion in virtual environments and render virtual assistance as well as human capability enhancements possible. "X-by-wire" type concepts are other motivating applications where traditional direct mechanical controllers are replaced by their enhanced electronic implementations.

The emphasis in this course is not on the excessive mathematical abstraction but rather on an integrated understanding of modeling, analysis, synthesis, and real time implementation. A solid understanding of the major concepts in the context of modern haptic interfaces and teleoperation systems is aimed.


The goal of this course is to equip each student with an integrated understanding of fundamental theories and computational methodologies that are used in (computer aided) analysis and synthesis of force controlled and bilaterally teleoperated systems. By the end of the course, each student should be able to do the following:

Linearize nonlinear systems using small signal (Taylor series) and feedback linearization techniques.
Identify phase margin, gain margin, and vector margin of LTI systems from Bode/Nyquist plots.
Derive sensitivity and complementary sensitivity functions of MIMO LTI systems and explain fundamental limitations of feedback control.
Check for internal stability of MIMO LTI systems.
List the major challenges in explicit force control and analytically demonstrate major reasons for chatter.
Synthesize (using root locus analysis) and implement explicit force controllers with guaranteed stability.
Design and implement reaction torque observers.
Derive and implement impedance controllers with and without force feedback.
Synthesize and implement admittance controllers.
Compare several force control architectures, discuss the mechanical properties of the plant favored by each controller, and select the appropriate controller for any given plant.
Construct and formulate physics based simulations of virtual environments.
List the sources of energy leaks in haptics rendering and discuss the compensation approaches.
Implement passive haptics renderings of physics based simulation of virtual environments
Construct the 4-channel bilateral teleoperator architecture with local force feedback and demonstrate the fundamental trade-off between stability and transparency.
Compare approaches to scaled bilateral teleoperation and discuss their advantages/disadvantages.
Identify the differences between BIBO stability, Lyapunov stability, passivity, and unconditional stability.
Design and implement passivity based controllers for stable scaled teleoperator architectures.
Demonstrate destabilizing effects of time delay and discuss approaches to compensate for these effects.



Research papers, book chapters, and supplementary material are assigned throughout the term.

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