Program

You can download the entire program here
Sunday, June 29th 2014
 
17h00
19h30
Registration (in Nantes downtown).
 
Monday, June 30th 2014
 
8h00
8h30
Registration
 
 
8h30
9h00
Opening ceremony.
9h00
10h00
Plenary session I : Some prospects of the modern sliding-mode control Abstract. The standard sliding-mode control (SMC) approach is usually described as a specific method of controlling heavily uncertain systems. Its well-known idea is to choose a proper constraint to be established in finite time and to be kept afterwards by high-frequency switching. The solution notably includes the search of a suitable constraint and
overcoming the chattering effect. Today, after a long evolution history, the SMC technique is capable to solve the most difficult problems of the contemporary control theory.
The modern SMC method often produces the straight-forward solution of the original control problem. Indeed, the finite-time establishment of a constraint with arbitrary relative degree is now optional. Also the SM-based observation has been shown to provide for the exact robust output derivatives in finite time. Thus, one can practically ideally solve most black-box control problems, provided the input and the output are scalars. The control can be chosen as smooth as needed, excluding any high-energy system vibrations. The results are currently extended to the multi-input multi-output case. The developed methods are proved to be effective also in control of hybrid or switched systems, systems with variable delays, systems with distributed parameters, stabilization of continuous systems, etc.

What happens when the parameters of the system uncertainty are themselves uncertain? These uncertainty-iteration problems require tuning of previously constant parameters, i.e. the SM adaptation. The Lyapunov function development is carried out for complicated systems featuring high-relative degrees and finite-time stability. The convergence rate regulation is now feasible, which includes the fixed-time convergence option as the extremal case. SMC optimization, including SMC system accuracy optimization and comparison with high-gain methods, has been recently performed.

While discrete SMs have been already studied for a long time, practical discretization methods for high-order SMC systems draw the attention only now. The author also believes that the practical-relative-degree approach opens a lot of new application possibilities.
The practical SMC theory implementation issues produce new challenging theoretical SMC problems. The approximability problems and stochastic analysis of high-order SMC systems still wait for their time.

Chairs : Prof A.Levant.
10h15
12h35
 
12h35
14h15
Lunch
 
14h15
15h00
15h00
15h25
Break
15h25
17h45
17h45
18h00
Break
18h00
19h00
Slide linkSlide link
Panel Discussion IHow to generalize super-twisting for arbitrary relative degree ?
Speakers. Kamal, Moreno, Fridman, Levant.
Generalization of the Super-Twisting Algorithm(STA) is discussed. Proposed algorithm called (r+1)-th order STA provides for relative degree r systems with respect to output
- finite-time convergence to the (r+1)-th order sliding mode set;
- absolutely continuous control signal;
- using the information about the output, it is differentiated till the order (r-1).
The convergence conditions for the 3-STA algorithm are proposed. The formula for algorithms of arbitrary order is suggested. The possibilities to prove their convergence will be discussed.


How to implement output Super-Twisting Controllers (STC) based on HOSM observers correctly?
Speakers. Fridman, Kamal, Levant.
Recently, a lot of papers devoted to output based Super-Twisting controllers (STC) using HOSM differentiators have been published. Implementation of the STC requires that the first time derivative of the sliding surface must be Lipschitz in time. STC based on the absolutely continuous estimation of the surface cannot be implemented. That is why the order of differentiators is important there. Different methodologies for output based implementations of STC will be discussed.


Discrete realization of fixed time convergence.
Speakers. Levant, Efimov, Polyakov, Moreno.
Recently, a new type of convergence for SM controllers and differentiators has been considered. For example, it has been shown that fixed time convergence is not feasible via Euler discretization. The possibilities of the discrete realization of fixed time convergence will be discussed.
Chairs : L. Fridman
Tuesday, July 1st 2014
9h00
10h00
10h15
12h35
 
12h35
14h15
Lunch
 
14h15
15h35
15h35
15h50
Break
15h50
16h50
16h50
17h00
Break
17h00
18h00
Slide linkSlide linkSlide link
Panel discussion IIPractical relative degree: frequency domain approach
Speakers. Fridman, Shtessel, Levant, Boiko.
The exact output tracking in controllable minimum-phase perturbed SISO systems, which mathematical model has well-defined known relative degree r, can be achieved via HOSM controller with an HOSM observer/differentiator of r-1 order . However, relative degree of the principal mathematical model that is used for the HOSM controller/observer design inevitably is reduced with respect to relative degree of the real system. It has been shown that the unmodeled dynamics has a fractal nature that increases system?s relative degree up to infinity. This yields chattering. Since it is impossible to design the HOSM control for system with relative degree r -> 8, a new notion of Practical Relative Degree (PRD) has been introduced using the time-domain techniques. A novel approach to defining the PRD using the frequency domain technique will be discussed. This approach is based on the following new concepts:
- the Level of Tolerance that includes the definitions of the acceptable amplitude and the acceptable frequency of the oscillation in the real sliding mode ;
- the Performance Margins, specifically Performance Gain Margins (PGM) and Performance Phase Margins (PPM) that characterize the additional gain and the additional phase shift that the system can tolerate until the Level of Tolerance is violated.

Two approaches to defining the PRD will be discussed
- if the model of the system is unknown, the PRD of the system is the smallest order of SM controller that generates the oscillations in the system satisfying the Level of Tolerance;
- the Performance Phase Margin (PPM) and the Performance Gain Margin (PGM) could be found for each tested sliding mode controller. The smallest order of controller that satisfies the Level of Tolerance with the desired/given PGM and PPM could be also considered as PRD.
When the adaptation of SM controllers is needed ?
Speakers: Y. Shtessel, L. Fridman, L. Hsu, G. Bartolini
Recently two important approaches to SM adaptation were published. SM adaptation when the upper bound of perturbations and their derivatives are known. In this case, 2 approaches can be used
- classical adaptation of SM gain to equivalent control;
- reconstruction of the perturbations basing on HOSM differentiators, and use of the perturbations estimation for direct compensation or as SM control gain.

Although, there are papers published on adapting the SMC for perturbed systems with unknown bounds of perturbations (these algorithms usually yield the gain overestimation), we suggest discussing several recent results on adaptive SMC/HOSM for such systems. The proposed concept consists in dynamically increasing the SMC/HOSM gains until the sliding mode is established. Then, the gains can be dynamically reduced so that the sliding mode is still retained. The proposed questions for the discussion are
- Adapt the control gains or reconstruct the perturbation and compensate ?
- Does the adaptation make sense in systems with known bounds of the perturbations ?
- Adaptation in systems with unknown bounds of the perturbations :

o gain overestimation ?
o how to guarantee the ability to retain the sliding mode with minimal gains ?
o the best concepts for the adaptation algorithms ?
o Lyapunov approach versus the ?minoring- majoring? and other techniques ?


Chairs : Fridman, Shtessel, Levant, Boiko, L. Hsu, G. Bartolini
 
20h00
23h59
Banquet (in a boat on Erdre river - http://bateaux-nantais.fr ) .
Wednesday, July 2nd 2014
9h00
10h00
Plenary session III : Theory and Practice of Sliding Mode Control for Industrial Electro-Hydraulic SystemsAbstract. In modern production machinery, fluid power is the muscle for the most demanding processes and applications, such as industrial presses, rolling mills, molding machines, flight simulators, industrial robots etc. In the last two decades, technical and economic forces have dynamically changed the requirements of hydraulic drive technology. Demands for efficiency, dynamics and quality of production processes, have forced the hydraulic drive industry to search for new and more advanced nonlinear control methods. Standard linear algorithms cannot assure optimal behavior in the presence of dominant system nonlinearities and strong system variations in hydraulic systems. Therefore, since the early 1990?s, many innovative linear and nonlinear control algorithms designed for hydraulic drives have been proposed. Of the many different algorithms available for industrial motion systems, one of the most promising is Sliding Mode Control (SMC). SMC is well known for its robustness against modeling uncertainties and external disturbances, as well as possessing a simple structure and a manageable design process. This makes it ideal in many industrial applications.

The presentation discusses integral sliding mode control methods, and higher order SMC disturbance compensators suitable for electro-hydraulic drives. The controllers presented, and the tuning rules developed, fulfill the demands of industry for suitability and handling during system commissioning. The controller performance was empirically verified and the results show that dynamic behavior, accuracy and robustness of electro-hydraulic drives can be significantly improved using nonlinear Sliding Mode Control.

Chairs : Dr.Ing. J. Komsta
10h15
12h35
 
12h35
14h15
Lunch
 
14h15
15h35
15h35
15h50
Break
15h50
17h30
 
17h30
18h00
Closure ceremony