Second-Order Sliding Mode Control with Adaptive Control Authority for the Tracking Control of Robotic Manipulators (original) (raw)
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20th European Control Conference, 2021
Robotic manipulators must operate in complex scenarios, which make the overall operational space quite large, and the system dynamics within that space subject to significant variations and uncertainties. Sliding mode control (SMC) strategies have been successfully applied in this context, yet, if a worst-case approach is taken in the face of large operational variations, the resulting performance may happen to be suboptimal. Moreover, attention must be paid, in an industrial setting, to vibrations that may be induced on the robot joints by the presence of chattering induced by the SMC algorithm. This work tests, in a challenging application context, a recently-proposed r-order SMC strategy that encompasses both continuous and discrete adaptation strategies to adjust its parameters, giving rise to an overall switched approach. In particular, two realistic case studies of robot motion control are discussed, proving its effectiveness in enhancing both performance and robustness in complex operational scenarios.
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2013
This paper presents the development of a nonlinear control strategy for a robot manipulator model, using a robust higher order sliding mode control structure. In the present work, a traditional sliding mode control is presented, the robustness of the controller in the context of stabilization and trajectory tracking, is analytically proved using Lyapunov approach. In order to reduce the chattering in sliding mode controller (SMC) we used the higher order sliding mode control algorithm (Super twisting and Twisting). The simulation results presented in this paper indicate that the suggested approach has considerable advantages compared to the classical sliding mode control. Keywords-robot manipulator; higher order sliding mode control; Twisting; Super twisting
International Journal of Modelling, Identification and Control, 2017
The sliding mode control concept has been extensively investigated during the last decade, where it has been proved that such a control strategy is not so simple to be efficiently applied in dynamical and mechanical systems, because of the too strong sensitivity of such systems to the chattering phenomenon. In this paper, a reformulated second order sliding mode controller has been implemented into a robotic system for a trajectory tracking task, both in the case of ideal operation as well as for real systems submitted to parameter uncertainties. A comparative study performed through the obtained simulation results has been presented. Then, an adaptive extension of the second order sliding mode control has been treated seeking to resolve the challenging problems of real systems reflected by the presence of physical and environmental disturbances and especially parametric uncertainties. The proposed adaptive second order SMC has the advantage that it allows not only to remedy disturbing phenomena but also to retain all properties and system performances. Simulation results performed on a robotic manipulator system have illustrated improved performances with the proposed adaptive second order sliding mode control design.
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In this article, an approach for tracking control of robot manipulators is presented. The proposed controller incorporates the approximately known inverse dynamic model output as a model-base portion of the controller; an estimated uncertainty term to compensate for the un-modeled dynamics, external disturbances, and time-varying parameters; and a decentralized PID controller as a feedback portion to enhance closed-loop stability and account for the estimation error of uncertainties. The robustness and capabilities of the proposed approach are investigated in simulation for an example robot.
sliding mode control of robot manipulator
Design a nonlinear controller for second order nonlinear uncertain dynamical systems is one of the most important challenging works. This course focuses on the design, implementation and analysis of a chattering free sliding mode controller for highly nonlinear dynamic PUMA robot manipulator and compare to computed torque controller, in presence of uncertainties. These simulation models are developed as a part of a software laboratory to support and enhance graduate/undergraduate robotics courses, nonlinear control courses and MATLAB/SIMULINK courses at research and development company (SSP Co.) research center, Shiraz, Iran.
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This paper presents a control strategy for robot manipulators, based on the coupling of the inverse dynamics method with the so-called second order sliding mode control approach. The motivation for using sliding mode control in robotics mainly relies on its appreciable features, such as design simplicity and robustness. Yet, the chattering effect, typical of the conventional sliding mode control, can be destructive. In this paper, this problem is suitably circumvented by adopting a second order sliding mode control approach characterized by a continuous control law. To design the inverse dynamics part of the proposed controller, a suitable dynamical model of the system has been formulated, and its parameters have been accurately identified. The proposed inverse dynamics-based second order sliding mode controller has been experimentally tested on a COMAU SMART3-S2 industrial manipulator, demonstrating the tracking properties and the good performances of the controlled system.
Robust Sliding Mode Control for Robot Manipulators
IEEE Transactions on Industrial Electronics, 2000
In the face of large-scale parametric uncertainties, the single-model (SM)-based sliding mode control (SMC) approach demands high gains for the observer, controller, and adaptation to achieve satisfactory tracking performance. The main practical problem of having high-gain-based design is that it amplifies the input and output disturbance as well as excites hidden unmodeled dynamics, causing poor tracking performance. In this paper, a multiple model/control-based SMC technique is proposed to reduce the level of parametric uncertainty to reduce observercontroller gains. To this end, we split uniformly the compact set of unknown parameters into a finite number of smaller compact subsets. Then, we design a candidate SMC corresponding to each of these smaller subsets. The derivative of the Lyapunov function candidate is used as a resetting criterion to identify a candidate model that approximates closely the plant at each instant of time.
IEEE Transactions on Control Systems Technology, 2015
The formulation of an Integral Suboptimal Second Order Sliding Mode control algorithm, oriented to solve motion control problems for robot manipulators, is presented in this paper. The proposed algorithm is designed so that the socalled reaching phase, normally present in the evolution of a system controlled via the sliding mode approach, is reduced to a minimum. This fact makes the algorithm more suitable to be applied to a real industrial robot, since it enhances its robustness, by extending it also to time intervals during which the classical sliding mode is not enforced. Moreover, since the algorithm generates second order sliding modes, while the model of the controlled electromechanical system has a relative degree equal to one, the control action actually fed into the plant is continuous, which provides a positive chattering alleviation effect. The assessment of the proposal has been carried out by experimentally testing it on a COMAU SMART3-S2 anthropomorphic industrial robot manipulator. The satisfactory experimental results, also compared with those obtained with a standard PD controller and with the original Suboptimal algorithm, confirm that the new algorithm can be actually used in an industrial context.
Design New Control Methodology of Industrial Robot Manipulator: Sliding Mode Baseline Methodology
International Journal of Hybrid Information Technology, 5(4):41-54, 2012
Design a nonlinear controller for second order nonlinear uncertain dynamical systems is one of the most important challenging works. This paper focuses on the design of a chattering free mathematical baseline sliding mode controller (BSMC) for highly nonlinear dynamic robot manipulator, in presence of uncertainties and external disturbance. In order to provide high performance nonlinear methodology, sliding mode controller and baseline methodology are selected. Conversely, pure sliding mode controller is used in many applications; it has an important drawback namely; chattering phenomenon which it can causes some problems such as saturation and heat the mechanical parts of robot manipulators or drivers so baseline sliding mode controller is used to eliminate this important challenge. In order to reduce the chattering this research is used the switching function in presence of baseline method instead of switching function method in pure sliding mode controller. The results demonstrate that baseline sliding mode controller with switching function is a model-based controllers which works well in certain and partly uncertain system and have a better performance compare to pure sliding mode controller. Chattering free baseline sliding mode controller is stable controller which eliminates the chattering phenomenon without to use the boundary layer saturation function.
A survey of applications of second-order sliding mode control to mechanical systems
International Journal of Control, 2003
The effective application of sliding mode control to mechanical systems is not straightforward because of the sensitivity of these systems to chattering. Higher-order sliding modes can counteract this phenomenon by confining the switching control to the higher derivatives of the mechanical control variable, so that the latter results are continuous. Generally, this approach requires the availability of a number of time derivatives of the sliding variable, and, in the presence of noise, this requirement could be a practical limitation. A class of second-order sliding mode controllers, guaranteeing finite-time convergence for systems with relative degree two between the sliding variable and the switching control, could be helpful both in reducing the number of differentiator stages in the controller and in dealing with unmodelled actuator dynamics. In this paper different second-order sliding mode controllers, previously presented in the literature, are shown to belong to the above cited class, and some challenging control problems involving mechanical systems are addressed and solved. Simulations and experimental results are provided throughout the paper.