scholarly journals Control of an Anthropomorphic Manipulator using LuGre Friction Model - Design and Experimental Validation

2021 ◽  
Vol 67 (9) ◽  
pp. 401-410
Author(s):  
Khurram Ali ◽  
Adeel Mehmood ◽  
Israr Muhammad ◽  
Sohail Razzaq ◽  
Jamshed Iqbal
Keyword(s):  
Sliding Mode ◽  
Friction Model ◽  
Linear Control ◽  
Superior Performance ◽  
Linear Control Systems ◽  
Friction Compensation ◽  
Control Law ◽  
Peak Time ◽  
Sliding Surface ◽  
Non Linear

Automation technology has been extensively recognized as an emerging field in various industrial applications. Recent breakthrough in flexible automation is primarily due to deployment of robotic arms or manipulators. Autonomy in these manipulators is essentially linked with the advancements in non-linear control systems. The objective of this research is to propose a robust control algorithm for a five degree of freedom (DOF) robotic arm to achieve superior performance and reliability in the presence of friction. A friction compensation-based non-linear control has been proposed and realized for the robotic manipulator. The dynamic model of the robot has been derived by considering the dynamic friction model. The proposed three-state model is validated for all the joints of the manipulator. The integral sliding mode control (ISMC) methodology has been designed; the trajectories of system every time begin from the sliding surface and it eliminates the reaching phase with assistance of integral term in the sliding surface manifold. The designed control law has been first simulated in Matlab/Simulink environment to characterize the control performance in terms of tracking of various trajectories. The results confirm the effectiveness of the proposed control law with model-based friction compensation. The transient parameters like settling and peak time have improvement as well have better results with friction than without considering the friction. The proposed control law is then realized on an in-house developed autonomous articulated robotic rducational platform (AUTAREP) and NI myRIO hardware interfaced with LabVIEW. Experimental results also witnessed the trajectory tracking by the robotic platform.

Disturbance Adaptive Discrete-Time Sliding Control With Application to Engine Speed Control

1998 ◽  
Vol 123 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Mooncheol Won ◽  
J. K. Hedrick
Keyword(s):  
Nonlinear Systems ◽  
Discrete Time ◽  
Control Method ◽  
Sliding Mode ◽  
Input Saturation ◽  
Adaptive Sliding Mode Control ◽  
Control Law ◽  
Sliding Surface ◽  
Sliding Control ◽  
Error Dynamics

This paper presents a discrete-time adaptive sliding control method for SISO nonlinear systems with a bounded disturbance or unmodeled dynamics. Control and adaptation laws considering input saturation are obtained from approximately discretized nonlinear systems. The developed disturbance adaptation or estimation law is in a discrete-time form, and differs from that of conventional adaptive sliding mode control. The closed-loop poles of the feedback linearized sliding surface and the adaptation error dynamics can easily be placed. It can be shown that the adaptation error dynamics can be decoupled from sliding surface dynamics using the proposed scheme. The proposed control law is applied to speed tracking control of an automatic engine subject to unknown external loads. Simulation and experimental results verify the advantages of the proposed control law.

A numerical method for the approximation of reachable sets of linear control systems

2017 ◽  
Vol 36 (2) ◽  
pp. 423-441 ◽  
Author(s):  
Lizhen Shao ◽  
Fangyuan Zhao ◽  
Guangda Hu
Keyword(s):  
Numerical Method ◽  
Control Systems ◽  
Optimization Problems ◽  
Approximation Error ◽  
Outer Approximation ◽  
Reachable Sets ◽  
Linear Control ◽  
Superior Performance ◽  
Linear Control Systems ◽  
Inner Approximation

Abstract In this article, a numerical method for the approximation of reachable sets of linear control systems is discussed. First a continuous system is transformed into a discrete one with Runge–Kutta methods. Then based on Benson’s outer approximation algorithm for solving multiobjective optimization problems, we propose a variant of Benson’s algorithm to sandwich the reachable set of the discrete system with an inner approximation and an outer approximation. By specifying an approximation error, the quality of the approximations measured in Hausdorff distance can be directly controlled. Furthermore, we use an illustrative example to demonstrate the working of the algorithm. Finally, computational experiments illustrate the superior performance of our proposed algorithm compared to a recent algorithm in the literature.

scholarly journals Design of Terminal Sliding Mode Controllers for Disturbed Non-Linear Systems Described by Matrix Differential Equations of the Second and First Orders

2019 ◽  
Vol 9 (11) ◽  
pp. 2325 ◽  
Author(s):  
Paweł Skruch ◽  
Marek Długosz
Keyword(s):  
Differential Equations ◽  
Sliding Mode ◽  
Sliding Surface ◽  
Terminal Sliding Mode ◽  
Sliding Mode Controllers ◽  
System Trajectory ◽  
Non Linear ◽  
Matrix Differential Equations ◽  
Non Linear Systems ◽  
Matrix Differential

This paper describes a design scheme for terminal sliding mode controllers of certain types of non-linear dynamical systems. Two classes of such systems are considered: the dynamic behavior of the first class of systems is described by non-linear second-order matrix differential equations, and the other class is described by non-linear first-order matrix differential equations. These two classes of non-linear systems are not completely disjointed, and are, therefore, investigated together; however, they are certainly not equivalent. In both cases, the systems experience unknown disturbances which are considered bounded. Sliding surfaces are defined by equations combining the state of the system and the expected trajectory. The control laws are drawn to force the system trajectory from an initial condition to the defined sliding surface in finite time. After reaching the sliding surface, the system trajectory remains on it. The effectiveness of the approaches proposed is verified by a few computer simulation examples.

Robust Optimal Sliding Mode Control for Attitude Synchronization of Autonomous Docking to a Tumbling Target

2012 ◽  
Vol 157-158 ◽  
pp. 757-761
Author(s):  
Wei Lu ◽  
Yun Hai Geng ◽  
Xiao Wei Shan
Keyword(s):  
Sliding Mode Control ◽  
Measurement Errors ◽  
Sliding Mode ◽  
Algorithm Design ◽  
Salient Feature ◽  
Control Law ◽  
Sliding Surface ◽  
Mode Control ◽  
Tumbling Target ◽  
Attitude Synchronization

This paper investigates the control problem of attitude synchronization for an on-orbit servicing spacecraft autonomously docking to a freely tumbling target in space. An optimal sliding surface is designed based on optimal control theory, followed by a robust optimal sliding mode control law designed for attitude synchronization in accordance. Meanwhile, the unknown but bounded external disturbances, parameter variations, model uncertainties, and measurement errors are all considered during the control algorithm design. The salient feature of this control law is that the relative attitude variables will converge to the origin in the sense of optimality with respect to a quadratic cost function once the sliding surface is reached. The simulation results validate the effectiveness and robustness of the designed robust optimal sliding mode control law.

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