| 1. |
- Bechlioulis, Charalampos P., et al.
(författare)
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Robust Image-Based Visual Servoing With Prescribed Performance Under Field of View Constraints
- 2019
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Ingår i: IEEE Transactions on robotics. - : Institute of Electrical and Electronics Engineers (IEEE). - 1552-3098 .- 1941-0468. ; 35:4, s. 1063-1070
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we propose a visual servoing scheme that imposes predefined performance specifications on the image feature coordinate errors and satisfies the visibility constraints that inherently arise owing to the camera's limited field of view, despite the inevitable calibration and depth measurement errors. Its efficiency is demonstrated via comparative experimental and simulation studies.
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| 2. |
- Heshmati-Alamdari, Shahab, et al.
(författare)
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A robust interaction control approach for underwater vehicle manipulator systems
- 2018
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Ingår i: Annual Reviews in Control. - : Elsevier. - 1367-5788 .- 1872-9088. ; 46, s. 315-325
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Forskningsöversikt (refereegranskat)abstract
- In underwater robotic interaction tasks (e.g., sampling of sea organisms, underwater welding, panel handling, etc) various issues regarding the uncertainties and complexity of the robot dynamic model, the external disturbances (e.g., sea currents), the steady state performance as well as the overshooting/undershooting of the interaction force error, should be addressed during the control design. Motivated by the aforementioned considerations, this paper presents a force/position tracking control protocol for an Underwater Vehicle Manipulator System (UVMS) in compliant contact with a planar surface, without incorporating any knowledge of the UVMS dynamic model, the exogenous disturbances or the contact stiffness model. Moreover, the proposed control framework guarantees: (i) certain predefined minimum speed of response, maximum steady state error as well as overshoot/undershoot concerning the force/position tracking errors, (ii) contact maintenance and (iii) bounded closed loop signals. Additionally, the achieved transient and steady state performance is solely determined by certain designer-specified performance functions/parameters and is fully decoupled from the control gain selection and the initial conditions. Finally, both simulation and experimental studies clarify the proposed method and verify its efficiency.
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| 3. |
- Heshmati Alamdari, Shahabodin, et al.
(författare)
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A Robust Predictive Control Approach for Underwater Robotic Vehicles
- 2020
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Ingår i: IEEE Transactions on Control Systems Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 1063-6536 .- 1558-0865. ; 28:6, s. 2352-2363
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Tidskriftsartikel (refereegranskat)abstract
- This article presents a robust nonlinear model predictive control (NMPC) scheme for autonomous navigation of underwater robotic vehicles operating in a constrained workspace including the static obstacles. In particular, the purpose of the controller is to guide the vehicle toward specific way points with guaranteed input and state constraints. Various constraints, such as obstacles, workspace boundaries, predefined upper bounds for the velocity of the robotic vehicle, and thruster saturations, are considered during the control design. Moreover, the proposed control scheme is designed at dynamic level, and it incorporates the full dynamics of the vehicle in which the ocean currents are also involved. Hence, taking the thrusts as the control inputs of the robotic system and formulating them accordingly, the vehicle exploits the ocean current dynamics when these are in favor of the way-point tracking mission, resulting in reduced energy consumption by the thrusters. The robustness of the closed-loop system against parameter uncertainties has been analytically guaranteed with convergence properties. The performance of the proposed control strategy is experimentally verified using a 4 degrees of freedom (DoF) underwater robotic vehicle inside a constrained test tank with sparse static obstacles.
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| 4. |
- Heshmati Alamdari, Shahabodin, et al.
(författare)
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A Self-triggered Position Based Visual Servoing Model Predictive Control Scheme for Underwater Robotic Vehicles
- 2020
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Ingår i: Machines. - : MDPI. - 2075-1702. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- An efficient position based visual sevroing control approach for Autonomous Underwater Vehicles (AUVs) by employing Non-linear Model Predictive Control (N-MPC) is designed and presented in this work. In the proposed scheme, a mechanism is incorporated within the vision-based controller that determines when the Visual Tracking Algorithm (VTA) should be activated and new control inputs should be calculated. More specifically, the control loop does not close periodically, i.e., between two consecutive activations (triggering instants), the control inputs calculated by the N-MPC at the previous triggering time instant are applied to the underwater robot in an open-loop mode. This results in a significantly smaller number of requested measurements from the vision tracking algorithm, as well as less frequent computations of the non-linear predictive control law. This results in a reduction in processing time as well as energy consumption and, therefore, increases the accuracy and autonomy of the Autonomous Underwater Vehicle. The latter is of paramount importance for persistent underwater inspection tasks. Moreover, the Field of View constraints (FoV), control input saturation, the kinematic limitations due to the underactuated degree of freedom in sway direction, and the effect of the model uncertainties as well as external disturbances have been considered during the control design. In addition, the stability and convergence of the closed-loop system has been guaranteed analytically. Finally, the efficiency and performance of the proposed vision-based control framework is demonstrated through a comparative real-time experimental study while using a small underwater vehicle.
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| 5. |
- Heshmati Alamdari, Shahabodin, et al.
(författare)
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Cooperative Impedance Control for Multiple Underwater Vehicle Manipulator Systems Under Lean Communication
- 2021
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Ingår i: IEEE Journal of Oceanic Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 0364-9059 .- 1558-1691. ; 46:2, s. 447-465
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Tidskriftsartikel (refereegranskat)abstract
- This article addresses the problem of cooperative object transportation for multiple underwater vehicle manipulator systems (UVMSs) in a constrained workspace with static obstacles, where the coordination relies solely on implicit communication arising from the physical interaction of the robots with the commonly grasped object. In this article, we propose a novel distributed leader-follower architecture, where the leading UVMS, which has knowledge of the object's desired trajectory, tries to achieve the desired tracking behavior via an impedance control law, navigating in this way, the overall formation toward the goal configuration while avoiding collisions with the obstacles. On the other hand, the following UVMSs estimate locally the object's desired trajectory via a novel prescribed performance estimation law and implement a similar impedance control law that achieves tracking of the desired trajectory despite the uncertainty and external disturbance in the object and the UVMS dynamics, respectively. The feedback relies on each UVMS's force/torque measurements and no explicit data is exchanged online among the robots, thus reducing the required communication bandwidth and increasing robustness. Moreover, the control scheme adopts load sharing among the UVMSs according to their specific payload capabilities. Finally, various simulation studies clarify the proposed method and verify its efficiency.
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| 6. |
- Logothetis, Michalis, et al.
(författare)
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Efficient Cooperation of Heterogeneous Robotic Agents
- 2021
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Ingår i: IEEE robotics & automation magazine. - : Institute of Electrical and Electronics Engineers (IEEE). - 1070-9932 .- 1558-223X. ; 28:2, s. 74-87
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Tsiamis, Anastasios, et al.
(författare)
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Decentralized Leader-Follower Control under High Level Goals without Explicit Communication
- 2015
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Ingår i: 2015 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS). - : IEEE. - 9781479999941 ; , s. 5790-5795
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Konferensbidrag (refereegranskat)abstract
- In this paper, we study the decentralized control problem of a two-agent system under local goal specifications given as temporal logic formulas. The agents collaboratively carry an object in a leader-follower scheme and lack means to exchange messages on-line, i. e., to communicate explicitly. Specifically, we propose a decentralized control protocol and a leader re-election strategy that secure the accomplishment of both agents' local goal specifications. The challenge herein lies in exploiting exclusively implicit inter- robot communication that is a natural outcome of the physical interaction of the robots with the object. An illustrative experiment is included clarifying and verifying the approach.
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