Abstract
In this paper, a time-varying chattering-free disturbance observer-based position tracking control law of serial robotic manipulators is presented to track a reference signal in a finite time. The key idea is to employ a positive-increasing function associated with the control/observer objectives to improve the control performance. First, the model of an uncertain robotic manipulator is presented as the case study of the proposed strategy. Then, the time-varying form of the robotic manipulator model is obtained to provide finite-time boundedness using the first-order sliding mode method. Moreover, without any knowledge about the upper bounds of the uncertainties, a reduced-order observer is presented to estimate the uncertainties in a finite time. Subsequently, a disturbance observer-based finite-time position tracking control law is designed. The time-varying gains are provided to converge the position tracking error to a neighborhood of zero in a finite time. Finally, comparative simulations are presented to show the effectiveness of the proposed scheme compared to other existing strategies.
Highlights
The problem of position tracking in uncertain robotic manipulators is a well-known topic over the last years, especially in the presence of external disturbances [1,2,3,4,5,6,7]
Motivated by the above considerations, this paper presents a new method for finite-time tracking control of robotic manipulators
Comparative simulations are reported between the proposed observer and the third-order sliding mode observer (TOSMO) in [24], which has had superior performance to estimate the uncertainties for robotic manipulators
Summary
The problem of position tracking in uncertain robotic manipulators is a well-known topic over the last years, especially in the presence of external disturbances [1,2,3,4,5,6,7]. An alternative approach is to measure the outputs of the system and to design an observation algorithm to construct a reliable estimation of the unknown terms. In this regard, disturbance observer-based control schemes have been proposed, in which to decrease the initial value of the control input, the observer is combined with the state feedback law. Some results related to this concept have been presented in [10,11,12,13,14], where the sliding mode observer (SMO)-based control is one of the main methods with widespread applications. Despite the successful deployment of the SMO-based control method, its standard version is affected by some restrictions, leading to the
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