Extended State Observer-Based Sliding Mode Control of an Omnidirectional Mobile Robot With Friction Compensation

This paper proposes the control design for the wheeled mobile robot in the presence of external disturbances, parametric uncertainties together with input saturation. Integrating the extended state observer technique, a practical method named sliding mode control is designed to force the state variables to attain the stable equilibrium with the help of extended state observer by compensating uncertainty and disturbance (called lumped uncertainty). To handle the shortcoming of undesired chattering and the difficulty of choosing the control gain, sliding mode control with adaptive mechanism is applied, which has the ability to automatically adjust the control gain and can even work well without a requirement of knowing the upper bound on lumped uncertainty. Subsequently, an auxiliary system is further developed to cope with input saturation problem. In addition, the stability analysis of the closed-loop system is rigorously proved via Lyapunov theorem, manifesting that the proposed controller can guarantee the ultimate boundedness of all signals in the overall system and make tracking errors converge to an arbitrarily small neighborhood around zero by selecting appropriate control parameters. Finally, simulation results are intuitively carried out to demonstrate the feasibility of the introduced adaptive composite controller.

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An extended state observer-based full-order sliding mode control for robotic joint actuated by antagonistic pneumatic artificial muscles

International Journal of Advanced Robotic Systems ◽

10.1177/1729881420986036 ◽

2021 ◽

Vol 18 (1) ◽

pp. 172988142098603

Author(s):

Daoxiong Gong ◽

Mengyao Pei ◽

Rui He ◽

Jianjun Yu

Keyword(s):

Sliding Mode Control ◽

Sliding Mode ◽

State Observer ◽

Extended State Observer ◽

Artificial Muscles ◽

Extended State ◽

Robot System ◽

Mode Control ◽

Physical Experiments ◽

Pneumatic Artificial Muscles

Pneumatic artificial muscles (PAMs) are expected to play an important role in endowing the advanced robot with the compliant manipulation, which is very important for a robot to coexist and cooperate with humans. However, the strong nonlinear characteristics of PAMs hinder its wide application in robots, and therefore, advanced control algorithms are urgently needed for making the best use of the advantages and bypassing the disadvantages of PAMs. In this article, we propose a full-order sliding mode control extended state observer (fSMC-ESO) algorithm that combines the ESO and the fSMC for a robotic joint actuated by a pair of antagonistic PAMs. The fSMC is employed to eliminate the chattering and to guarantee the finite-time convergence, and the ESO is adopted to observe both the total disturbance and the states of the robot system, so that we can inhibit the disturbance and compensate the nonlinearity efficiently. Both simulations and physical experiments are conducted to validate the proposed method. We suggest that the proposed method can be applied to the robotic systems actuated by PAMs and remarkably improve the performance of the robot system.

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