Robust implementation of a variable structure control scheme

1990 ◽  
Author(s):  
B.M. Diong ◽  
J.V. Medanic
Keyword(s):  
Variable Structure Control ◽  
Variable Structure ◽  
Structure Control ◽  
Robust Implementation ◽  
Control Scheme

Robust Variable Structure Control for Free-Floating Space Robot System With Dual-Arms in Joints Space

2009 ◽  
Author(s):  
Xiaoteng Tang ◽  
Li Chen
Keyword(s):  
Variable Structure Control ◽  
Variable Structure ◽  
Joint Space ◽  
Space Robot ◽  
Dynamic Equations ◽  
Robot System ◽  
Structure Control ◽  
Floating Base ◽  
Inertial Parameters ◽  
Control Scheme

In this paper, the kinematics and dynamics of free-floating space robot system with dual-arms are analyzed. It is shown that the dynamic equations of the system are nonlinearly according to inertial parameters. In order to overcome these problems, the system is modeled as under-actuated robot system, and the idea of augmentation approach is adopted. It is demonstrated that the dynamic equations of the system can be linearly depending on a group of inertial parameters. Based on this result, a robust variable structure control scheme for free-floating space robot system with dual-arms with uncertain inertial parameters to track the desired trajectories in joint space is proposed, and a planar space robot system with dual-arms is simulated to verify the proposed control scheme. The advantage of the control scheme proposed is that it requires neither measuring the position, velocity and acceleration of the floating base with respect to the orbit nor controlling the position and attitude angle of the floating base. In addition to this advantage, it is computationally simple, because of choosing the controller robust for the uncertain inertial parameters rather than explicitly estimating them online.

scholarly journals A Variable Structure Control Scheme Proposal for the Tokamak à Configuration Variable

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Aitor Marco ◽  
Aitor J. Garrido ◽  
Stefano Coda ◽  
Izaskun Garrido ◽  
TCV Team
Keyword(s):  
Fusion Reaction ◽  
Plasma Heating ◽  
Variable Structure Control ◽  
Variable Structure ◽  
Current Control ◽  
Vacuum Vessel ◽  
Plasma Current ◽  
Tokamak Reactor ◽  
Structure Control ◽  
Control Scheme

Fusion power is the most significant prospects in the long-term future of energy in the sense that it composes a potentially clean, cheap, and unlimited power source that would substitute the widespread traditional nonrenewable energies, reducing the geographical dependence on their sources as well as avoiding collateral environmental impacts. Although the nuclear fusion research started in the earlier part of 20th century and the fusion reactors have been developed since the 1950s, the fusion reaction processes achieved have not yet obtained net power, since the generated plasma requires more energy to achieve and remain in necessary particular pressure and temperature conditions than the produced profitable energy. For this purpose, the plasma has to be confined inside a vacuum vessel, as it is the case of the Tokamak reactor, which consists of a device that generates magnetic fields within a toroidal chamber, being one of the most promising solutions nowadays. However, the Tokamak reactors still have several issues such as the presence of plasma instabilities that provokes a decay of the fusion reaction and, consequently, a reduction in the pulse duration. In this sense, since long pulse reactions are the key to produce net power, the use of robust and fast controllers arises as a useful tool to deal with the unpredictability and the small time constant of the plasma behavior. In this context, this article focuses on the application of robust control laws to improve the controllability of the plasma current, a crucial parameter during the plasma heating and confinement processes. In particular, a variable structure control scheme based on sliding surfaces, namely, a sliding mode controller (SMC) is presented and applied to the plasma current control problem. In order to test the validity and goodness of the proposed controller, its behavior is compared to that of the traditional PID schemes applied in these systems, using the RZIp model for the Tokamak à Configuration Variable (TCV) reactor. The obtained results are very promising, leading to consider this controller as a strong candidate to enhance the performance of the PID-based controllers usually employed in this kind of systems.

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