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1. Analytical and Experimental Decentralized Adaptive Control of a High-Degrees-of-Freedom Robot Manipulator

   https://doi.org/https://doi.org/10.1115/1.4049795  

   Bertino, Alexander ; Naseradinmousavi, Peiman ; Kelkar, Atul ( July 2021 , Journal of dynamic systems measurement and control)

   null (Ed.)

   In this paper, we study the analytical and experimental control of a seven degrees-of-freedom (7DOF) robot manipulator. A model-free decentralized adaptive control strategy is presented for the tracking control of the manipulator. The problem formulation and experimental results demonstrate the computational efficiency and simplicity of the proposed method. The results presented here are one of the first known experiments on a redundant 7DOF robot. The efficacy of the adaptive decentralized controller is demonstrated experimentally by using the Baxter robot to track a desired trajectory. Simulation and experimental results clearly demonstrate the versatility, tracking performance, and computational efficiency of this method. 

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2. Analytical and experimental nonzero-sum differential game-based control of a 7-DOF robotic manipulator

   https://doi.org/https://doi.org/10.1177/1077546320982447  

   Bagheri, Mostafa ; Naseradinmousavi, Peiman ( January 2021 , Journal of vibration and control)

   null (Ed.)

   We formulate a Nash-based feedback control law for an Euler–Lagrange system to yield a solution to noncooperative differential game. The robot manipulators are broadly used in industrial units on the account of their reliable, fast, and precise motions, while consuming a significant lumped amount of energy. Therefore, an optimal control strategy needs to be implemented in addressing efficiency issues, while delivering accuracy obligation. As a case study, we here focus on a 7-DOF robot manipulator through formulating a two-player feedback nonzero-sum differential game. First, coupled Euler–Lagrangian dynamic equations of the manipulator are briefly presented. Then, we formulate the feedback Nash equilibrium solution to achieve perfect trajectory tracking. Finally, the performance of the Nash-based feedback controller is analytically and experimentally examined. Simulation and experimental results reveal that the control law yields almost perfect tracking and achieves closed-loop stability. 

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3. Experimental and Analytical Nonzero-Sum Differential Game-Based Control of a 7-DOF Robotic Manipulator

   https://doi.org/10.1115/DSCC2020-3114  

   Bagheri, Mostafa ; Bertino, Alexander ; Naseradinmousavi, Peiman ( January 2021 , Proceedings of the ASME Dynamic Systems and Control Conference)

   null (Ed.)

   We formulate a Nash-based feedback control law for an Euler-Lagrange system to yield a solution to non-cooperative differential game. The robot manipulators are broadly utilized in industrial units on the account of their reliable, fast, and precise motions, while consuming a significant lumped amount of energy. Therefore, an optimal control strategy needs to be implemented in addressing efficiency issues, while delivering accuracy obligation. As a case study, we here focus on a 7-DOF robot manipulator through formulating a two-player feedback nonzero-sum differential game. First, coupled Euler-Lagrangian dynamic equations of the manipulator are briefly presented. Then, we formulate the feedback Nash equilibrium solution in order to achieve perfect trajectory tracking. Finally, the performance of the Nash-based feedback controller is analytically and experimentally examined. Simulation and experimental results reveal that the control law yields almost perfect tracking and achieves closed-loop stability. 

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4. Time Delay Control of a High-DOF Robot Manipulator Through Feedback Linearization Based Predictor

   https://doi.org/https://doi.org/10.1115/DSCC2019-8915  

   Bagheri, Mostafa ; Naseradinmousavi, Peiman ; Krstic, Miroslav ( November 2019 , ASME 2019 Dynamic Systems and Control Conference)

   We formulate a predictor-based controller for a high-DOF manipulator to compensate a time-invariant input delay during a pick-and-place task. Robot manipulators are widely used in tele-manipulation systems on the account of their reliable, fast, and precise motions while they are subject to large delays. Using common control algorithms on such delay systems can cause not only poor control performance, but also catastrophic instability in engineering applications. Therefore, delays need to be compensated in designing robust control laws. As a case study, we focus on a 7-DOF Baxter manipulator subject to three different input delays. First, delay-free dynamic equations of the Baxter manipulator are derived using the Lagrangian method. Then, we formulate a predictor-based controller, in the presence of input delay, in order to track desired trajectories. Finally, the effects of input delays in the absence of a robust predictor are investigated, and then the performance of the predictor-based controller is experimentally evaluated to reveal robustness of the algorithm formulated. Simulation and experimental results demonstrate that the predictor-based controller effectively compensates input delays and achieves closed-loop stability. 

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5. Adaptive Control of a Two-Link Robot Using Batch Least-Square Identifier

   https://doi.org/10.1109/JAS.2020.1003459  

   Bagheri, Mostafa ; Karafyllis, Iasson ; Naseradinmousavi, Peiman ; Krstic, Miroslav. ( January 2021 , IEEECAA journal of automatica sinica)

   Liu, Tengfei ; Ou, Yan. (Ed.)

   We design a regulation-triggered adaptive controller for robot manipulators to efficiently estimate unknown parameters and to achieve asymptotic stability in the presence of coupled uncertainties. Robot manipulators are widely used in telemanipulation systems where they are subject to model and environmental uncertainties. Using conventional control algorithms on such systems can cause not only poor control performance, but also expensive computational costs and catastrophic instabilities. Therefore, system uncertainties need to be estimated through designing a computationally efficient adaptive control law. We focus on robot manipulators as an example of a highly nonlinear system. As a case study, a 2-DOF manipulator subject to four parametric uncertainties is investigated. First, the dynamic equations of the manipulator are derived, and the corresponding regressor matrix is constructed for the unknown parameters. For a general nonlinear system, a theorem is presented to guarantee the asymptotic stability of the system and the convergence of parameters’ estimations. Finally, simulation results are discussed for a two-link manipulator, and the performance of the proposed scheme is thoroughly evaluated. 

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