A novel control scheme for typical unstable processes with time delay

Author(s):  
Tao Liu ◽  
Xing He ◽  
Danying Gu ◽  
Wei Wang
Actuators ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 54
Author(s):  
Minh-Thien Tran ◽  
Dong-Hun Lee ◽  
Soumayya Chakir ◽  
Young-Bok Kim

This article proposes a novel adaptive super-twisting sliding mode control scheme with a time-delay estimation technique (ASTSMC-TDE) to control the yaw angle of a single ducted-fan unmanned aerial vehicle system. Such systems are highly nonlinear; hence, the proposed control scheme is a combination of several control schemes; super-twisting sliding mode, TDE technique to estimate the nonlinear factors of the system, and an adaptive sliding mode. The tracking error of the ASTSMC-TDE is guaranteed to be uniformly ultimately bounded using Lyapunov stability theory. Moreover, to enhance the versatility and the practical feasibility of the proposed control scheme, a comparison study between the proposed controller and a proportional-integral-derivative controller (PID) is conducted. The comparison is achieved through two different scenarios: a normal mode and an abnormal mode. Simulation and experimental tests are carried out to provide an in-depth investigation of the performance of the proposed ASTSMC-TDE control system.


Author(s):  
J-F Zhang ◽  
C-J Yang ◽  
Y Chen

A novel control architecture based on a multi-event for tele-operation with an exoskeleton arm over the internet in case of transmission delay and communication failure is proposed. In this proposed control scheme a non-time event reference s is chosen to coordinate two sites and promises synchronization of the system. In addition, more than one event generator is employed to compose the multi-event-based control structure, in which the state of the slave site and uncertainties on the master site, such as singularity of the master arm and so on, are both evaluated. Through the bilateral tele-operation experiments in case of time delay with a rigid obstacle and master arm singularity structure, this control scheme is well demonstrated. The tele-operation system has solid performance with good stability and synchronization.


Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 597
Author(s):  
Brahim Brahmi ◽  
Ibrahim El Bojairami ◽  
Tanvir Ahmed ◽  
Asif Al Zubayer Swapnil ◽  
Mohammad AssadUzZaman ◽  
...  

The research presents a novel controller designed for robotic systems subject to nonlinear uncertain dynamics and external disturbances. The control scheme is based on the modified super-twisting method, input/output feedback linearization, and time delay approach. In addition, to minimize the chattering phenomenon and ensure fast convergence to the selected sliding surface, a new reaching law has been integrated with the control law. The control scheme aims to provide high performance and enhanced accuracy via limiting the effects brought by the presence of uncertain dynamics. Stability analysis of the closed-loop system was conducted using a powerful Lyapunov function, showing finite time convergence of the system’s errors. Lastly, experiments shaping rehabilitation tasks, as performed by healthy subjects, demonstrated the controller’s efficiency given its uncertain nonlinear dynamics and the external disturbances involved.


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