control effort
Deep reinforcement learning-based spacecraft attitude control with pointing keep-out constraint
Yang, Juntang, Ben-Larbi, Mohamed Khalil
This paper implements deep reinforcement learning (DRL) for spacecraft reorientation control with a single pointing keep-out zone. The Soft Actor-Critic (SAC) algorithm is adopted to handle continuous state and action space. A new state representation is designed to explicitly include a compact representation of the attitude constraint zone. The reward function is formulated to achieve the control objective while enforcing the attitude constraint. A curriculum learning approach is used for the agent training. Simulation results demonstrate the effectiveness of the proposed DRL-based method for spacecraft pointing-constrained attitude control.
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Balancing Centralized Learning and Distributed Self-Organization: A Hybrid Model for Embodied Morphogenesis
We investigate how to couple a learnable brain-like'' controller to a cell-like'' Gray--Scott substrate to steer pattern formation with minimal effort. A compact convolutional policy is embedded in a differentiable PyTorch reaction--diffusion simulator, producing spatially smooth, bounded modulations of the feed and kill parameters ($ΔF$, $ΔK$) under a warm--hold--decay gain schedule. Training optimizes Turing-band spectral targets (FFT-based) while penalizing control effort ($\ell_1/\ell_2$) and instability. We compare three regimes: pure reaction--diffusion, NN-dominant, and a hybrid coupling. The hybrid achieves reliable, fast formation of target textures: 100% strict convergence in $\sim 165$ steps, matching cell-only spectral selectivity (0.436 vs.\ 0.434) while using $\sim 15\times$ less $\ell_1$ effort and $>200\times$ less $\ell_2$ power than NN-dominant control. An amplitude sweep reveals a non-monotonic Goldilocks'' zone ($A \approx 0.03$--$0.045$) that yields 100\% quasi convergence in 94--96 steps, whereas weaker or stronger gains fail to converge or degrade selectivity. These results quantify morphological computation: the controller seeds then cedes,'' providing brief, sparse nudges that place the system in the correct basin of attraction, after which local physics maintains the pattern. The study offers a practical recipe for building steerable, robust, and energy-efficient embodied systems that exploit an optimal division of labor between centralized learning and distributed self-organization.
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- North America > United States > Georgia > Fulton County > Atlanta (0.04)
- Asia > Middle East > Jordan (0.04)
Smooth Spatiotemporal Tube Synthesis for Prescribed-Time Reach-Avoid-Stay Control
Upadhyay, Siddhartha, Das, Ratnangshu, Jagtap, Pushpak
In this work, we address the issue of controller synthesis for a control-affine nonlinear system to meet prescribed time reach-avoid-stay specifications. Our goal is to improve upon previous methods based on spatiotemporal tubes (STTs) by eliminating the need for circumvent functions, which often lead to abrupt tube modifications and high control effort. We propose an adaptive framework that constructs smooth STTs around static unsafe sets, enabling continuous avoidance while guiding the system toward the target within the prescribed time. A closed-form, approximation-free control law is derived to ensure the system trajectory remains within the tube and satisfies the RAS task. The effectiveness of the proposed approach is demonstrated through a case study, showing a significant reduction in control effort compared to prior methods.
Adaptive Task Space Non-Singular Terminal Super-Twisting Sliding Mode Control of a 7-DOF Robotic Manipulator
Wan, L., Smith, S., Pan, Y. -J., Witrant, E.
--This paper presents a new task-space Non-singular Terminal Super-Twisting Sliding Mode (NT -STSM) controller with adaptive gains for robust trajectory tracking of a 7-DOF robotic manipulator. The proposed approach addresses the challenges of chattering, unknown disturbances, and rotational motion tracking, making it suited for high-DOF manipulators in dexterous manipulation tasks. A rigorous boundedness proof is provided, offering gain selection guidelines for practical implementation. Simulations and hardware experiments with external disturbances demonstrate the proposed controller's robust, accurate tracking with reduced control effort under unknown disturbances compared to other NT -STSM and conventional controllers. The results demonstrated that the proposed NT -STSM controller mitigates chattering and instability in complex motions, making it a viable solution for dexterous robotic manipulations and various industrial applications. HE development of robust control algorithms is necessary for industrial robotic manipulators in applications such as remote surgery, cooperative multi-robot manipulation, and handling varying payloads. These applications require precise trajectory tracking, robustness to disturbances, and energy-efficient control strategies. High degree-of-freedom (DOF) manipulators offer an extensive range of motion, however, their complex nonlinear dynamics, with model uncertainties and external disturbances, pose significant control challenges.
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- Europe > France > Auvergne-Rhône-Alpes > Isère > Grenoble (0.05)
- North America > Canada > Nova Scotia > Halifax Regional Municipality > Halifax (0.04)
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Robust and Agile Quadrotor Flight via Adaptive Unwinding-Free Quaternion Sliding Mode Control
Yazdanshenas, Amin, Faieghi, Reza
--This paper presents a new adaptive sliding mode control (SMC) framework for quadrotors that achieves robust and agile flight under tight computational constraints. The proposed controller addresses key limitations of prior SMC formulations, including (i) the slow convergence and almost-global stability of SO(3)-based methods, (ii) the oversimplification of rotational dynamics in Euler-based controllers, (iii) the unwinding phenomenon in quaternion-based formulations, and (iv) the gain overgrowth problem in adaptive SMC schemes. Our controller is computationally efficient and runs reliably on a resource-constrained nano quadrotor, achieving 250 Hz and 500 Hz refresh rates for position and attitude control, respectively. In an extensive set of hardware experiments with over 130 flight trials, the proposed controller consistently outperforms three benchmark methods, demonstrating superior trajectory tracking accuracy and robustness with relatively low control effort. The controller enables aggressive maneuvers such as dynamic throw launches, flip maneuvers, and accelerations exceeding 3g, which is remarkable for a 32-gram nano quadrotor . The experimental codes and videos related to this paper are accessible at the following links: Code: https://github.com/A A. Motivation Quadrotors require robust control to maintain stability and precise maneuverability under disturbances and uncertainties. One widely studied method in this context is sliding mode control (SMC). One key challenge involves attitude control. As discussed in Section II, coordinate-free methods exhibit slow convergence and provide only almost global stability. The authors are with the Autonomous V ehicles Laboratory, Department of Aerospace Engineering, Toronto Metropolitan University, Toronto, Canada{amin.yazdanshenas,reza.faieghi Quaternion-based methods also face the unwinding issue, which can cause unnecessarily prolonged rotations. A second challenge is the need to know the upper bounds of uncertainties. Adaptive switching gains eliminate the need for prior knowledge of these bounds.
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- Asia > Middle East > Republic of Türkiye > Karaman Province > Karaman (0.04)
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- Research Report > Experimental Study (0.46)
- Transportation > Air (1.00)
- Aerospace & Defense > Aircraft (1.00)
Shape-Adaptive Planning and Control for a Deformable Quadrotor
Wu, Yuze, Han, Zhichao, Wu, Xuankang, Zhou, Yuan, Wang, Junjie, Fang, Zheng, Gao, Fei
Drones have become essential in various applications, but conventional quadrotors face limitations in confined spaces and complex tasks. Deformable drones, which can adapt their shape in real-time, offer a promising solution to overcome these challenges, while also enhancing maneuverability and enabling novel tasks like object grasping. This paper presents a novel approach to autonomous motion planning and control for deformable quadrotors. We introduce a shape-adaptive trajectory planner that incorporates deformation dynamics into path generation, using a scalable kinodynamic A* search to handle deformation parameters in complex environments. The backend spatio-temporal optimization is capable of generating optimally smooth trajectories that incorporate shape deformation. Additionally, we propose an enhanced control strategy that compensates for external forces and torque disturbances, achieving a 37.3\% reduction in trajectory tracking error compared to our previous work. Our approach is validated through simulations and real-world experiments, demonstrating its effectiveness in narrow-gap traversal and multi-modal deformable tasks.
- Asia > Middle East > Republic of Türkiye > Karaman Province > Karaman (0.04)
- Asia > India (0.04)
- Asia > China > Zhejiang Province > Hangzhou (0.04)
- Asia > China > Liaoning Province > Shenyang (0.04)
A Genetic Fuzzy-Enabled Framework on Robotic Manipulation for In-Space Servicing
Steffen, Nathan, Louw, Wilhelm, Ernest, Nicholas, Arnett, Timothy, Cohen, Kelly
Automation of robotic systems for servicing in cislunar space is becoming extremely important as the number of satellites in orbit increases. Safety is critical in performing satellite maintenance, so the control techniques utilized must be trusted in addition to being highly efficient. In this work, Genetic Fuzzy Trees are combined with the widely used LQR control scheme via Thales' TrUE AI Toolkit to create a trusted and efficient controller for a two-degree-of-freedom planar robotic manipulator that would theoretically be used to perform satellite maintenance. It was found that Genetic Fuzzy-LQR is 18.5% more performant than optimal LQR on average, and that it is incredibly robust to uncertainty.
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- North America > United States > Massachusetts > Suffolk County > Boston (0.04)
- Africa > Middle East > Egypt (0.04)
RL-based Control of UAS Subject to Significant Disturbance
Chakraborty, Kousheek, Hof, Thijs, Alharbat, Ayham, Mersha, Abeje
RL-based Control of UAS Subject to Significant DisturbanceAccepted at the 2025 International Conference on Unmanned Aircraft SystemsKousheek Chakraborty, 1, Thijs Hof, 1, A yham Alharbat 1, 2, Abeje Mersha 1 Abstract --This paper proposes a Reinforcement Learning (RL)-based control framework for position and attitude control of an Unmanned Aerial System (UAS) subjected to significant disturbance that can be associated with an uncertain trigger signal. The proposed method learns the relationship between the trigger signal and disturbance force, enabling the system to anticipate and counteract the impending disturbances before they occur . We train and evaluate three policies: a baseline policy trained without exposure to the disturbance, a reactive policy trained with the disturbance but without the trigger signal, and a predictive policy that incorporates the trigger signal as an observation and is exposed to the disturbance during training. Our simulation results show that the predictive policy outperforms the other policies by minimizing position deviations through a proactive correction maneuver . This work highlights the potential of integrating predictive cues into RL frameworks to improve UAS performance. I NTRODUCTION Unmanned Aerial Systems (UAS) are increasingly deployed in high-risk environments to perform critical tasks such as infrastructure inspection, search and rescue, and aerial firefighting [1].
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- Law Enforcement & Public Safety > Fire & Emergency Services (0.34)
Reinforcement Learning-Based Neuroadaptive Control of Robotic Manipulators under Deferred Constraints
Nohooji, Hamed Rahimi, Zaraki, Abolfazl, Voos, Holger
This paper presents a reinforcement learning-based neuroadaptive control framework for robotic manipulators operating under deferred constraints. The proposed approach improves traditional barrier Lyapunov functions by introducing a smooth constraint enforcement mechanism that offers two key advantages: (i) it minimizes control effort in unconstrained regions and progressively increases it near constraints, improving energy efficiency, and (ii) it enables gradual constraint activation through a prescribed-time shifting function, allowing safe operation even when initial conditions violate constraints. To address system uncertainties and improve adaptability, an actor-critic reinforcement learning framework is employed. The critic network estimates the value function, while the actor network learns an optimal control policy in real time, enabling adaptive constraint handling without requiring explicit system modeling. Lyapunov-based stability analysis guarantees the boundedness of all closed-loop signals. The effectiveness of the proposed method is validated through numerical simulations.
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Resilient Timed Elastic Band Planner for Collision-Free Navigation in Unknown Environments
Kulathunga, Geesara, Yilmaz, Abdurrahman, Huang, Zhuoling, Hroob, Ibrahim, Arunachalam, Hariharan, Guevara, Leonardo, Klimchik, Alexandr, Cielniak, Grzegorz, Hanheide, Marc
In autonomous navigation, trajectory replanning, refinement, and control command generation are essential for effective motion planning. This paper presents a resilient approach to trajectory replanning addressing scenarios where the initial planner's solution becomes infeasible. The proposed method incorporates a hybrid A* algorithm to generate feasible trajectories when the primary planner fails and applies a soft constraints-based smoothing technique to refine these trajectories, ensuring continuity, obstacle avoidance, and kinematic feasibility. Obstacle constraints are modelled using a dynamic Voronoi map to improve navigation through narrow passages. This approach enhances the consistency of trajectory planning, speeds up convergence, and meets real-time computational requirements. In environments with around 30\% or higher obstacle density, the ratio of free space before and after placing new obstacles, the Resilient Timed Elastic Band (RTEB) planner achieves approximately 20\% reduction in traverse distance, traverse time, and control effort compared to the Timed Elastic Band (TEB) planner and Nonlinear Model Predictive Control (NMPC) planner. These improvements demonstrate the RTEB planner's potential for application in field robotics, particularly in agricultural and industrial environments, where navigating unstructured terrain is crucial for ensuring efficiency and operational resilience.
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