Abstract
This article considers finite-time trajectory tracking control problem for robotic manipulators with parameter uncertainties and external disturbances. A finite-time controller that achieves high precision and strong robustness is proposed without the requirement of the exact dynamic model. First, a novel finite-time model-assisted extended state observer is designed to compensate the system uncertainties with complex and uncertain dynamics. Then, a composite finite-time controller is developed for trajectory tracking control with the help of finite-time model-assisted extended state observer. Compared to the classic extended state observer, it is proved that the estimation error of finite-time model-assisted extended state observer can be stabilized in finite time. Meanwhile, the finite-time convergence of the closed-loop system with the proposed controller can also be proved through Lyapunov’s stability theory. A variable structure term is employed to compensate the estimation errors of finite-time model-assisted extended state observer. The validity of the control scheme is demonstrated by simulations and experiments.
Highlights
With the rapid development and widespread exploitation of robotic manipulators, the requirements for high control performance are increasing, including high precision, fast motion control and high anti-disturbance capability, and so on
ITAE: integral of the time multiplied by the absolute value of the error; Integral of the square value (ISV): integral of the square value; continuous TSM controller (CTSMC): continuous terminal sliding mode controller; ADRC: active disturbance rejection control; FTC: finite-time controller; finite-time model-assisted ESO (FTMESO): finite-time model-assisted extended state observer; CTC: computed torque control
Considering many servo drivers without this featureless, we introduce tracking differentiator (TD) as an alternative to make the proposed controller be applied to more applications
Summary
With the rapid development and widespread exploitation of robotic manipulators, the requirements for high control performance are increasing, including high precision, fast motion control and high anti-disturbance capability, and so on. Precise and rapid trajectory tracking control problem is addressed for robotic manipulators, which contain high nonlinearities, uncertainties, and disturbances. The desired design scheme should have a simple structure, finite-time convergence, strong robustness, small initial control input, and less computational burden. With the help of FTMESO, the proposed controller can guarantee the finite-time stability of the closed loop system, and achieve prescribed tracking performance and high anti-disturbance capability. For further observer and control design, the system (10) can be restructured as follows
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