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arXiv 2024年

作者： Izadi, Maedeh Cobbenhagen, A.T.J.R. Sommer, Ruben Andrien, A.R.P. Lefeber, Erjen Heemels, W.P.M.H. Department of Mechanical Engineering Eindhoven University of Technology Netherlands Avular Mobile Robotics Eindhoven Netherlands

In this paper, we present a novel cascade control structure with formal guarantees of uniform almost global asymptotic stability for the state tracking error dynamics of a quadcopter. The proposed approach features a model predictive control strategy for the outer loop, explicitly accounting for the non-zero total thrust constraint. The outer-loop controller generates an acceleration reference, which is then converted into attitude, angular velocity and acceleration references, subsequently tracked by a nonlinear inner-loop controller. The proposed cascade control strategy is validated through numerical case studies, underlying high-fidelity models, demonstrating its ability to track fast trajectories with small error. © 2024, CC BY-NC-ND.

关键词： Predictive control systems

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Integrating Model-Based Footstep Planning with Model-Free Reinforcement Learning for Dynamic Legged Locomotion

arXiv

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arXiv 2024年

作者： Lee, Ho Jae Hong, Seungwoo Kim, Sangbae The Biomimetic Robotics Lab Mechanical Engineering Department Massachusetts Institute of TechnologyCambridge MA United States

In this work, we introduce a control framework that combines model-based footstep planning with Reinforcement Learning (RL), leveraging desired footstep patterns derived from the Linear Inverted Pendulum (LIP) dynamics. Utilizing the LIP model, our method forward predicts robot states and determines the desired foot placement given the velocity commands. We then train an RL policy to track the foot placements without following the full reference motions derived from the LIP model. This partial guidance from the physics model allows the RL policy to integrate the predictive capabilities of the physics-informed dynamics and the adaptability characteristics of the RL controller without overfitting the policy to the template model. Our approach is validated on the MIT Humanoid, demonstrating that our policy can achieve stable yet dynamic locomotion for walking and turning. We further validate the adaptability and generalizability of our policy by extending the locomotion task to unseen, uneven terrain. During the hardware deployment, we have achieved forward walking speeds of up to 1.5 m/s on a treadmill and have successfully performed dynamic locomotion maneuvers such as 90-degree and 180-degree turns. © 2024, CC BY.

关键词： Reinforcement learning

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Guest Editorial: Human-Robot Convergence and Application

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Journal of Institute of Control, robotics and Systems 2023年第2期29卷 87-87页

作者： Choi, Jungsu Kong, Kyoungchul Department of Robotics Engineering Yeungnam University Korea Republic of Department of Mechanical Engineering KAIST Korea Republic of

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Development of a Lightweight Real-Time Application for Dynamic Hand Gesture Recognition

Development of a Lightweight Real-Time Application for Dynam...

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IEEE International Conference on Mechatronics and Automation

作者： Oluwaleke Yusuf Maki Habib Department of Mechanical Engineering Robotics Control and Smart Systems (RCSS) Program The American University in Cairo (AUC) Cairo Egypt

Hand Gesture Recognition (HGR) is a form of perceptual computing with applications in human-machine interaction, virtual/augmented reality, and human behavior analysis. Within the HGR domain, several frameworks have been developed with different combinations of input modalities and network architectures with varying levels of efficacy. Such frameworks maximized performance at the expense of increased hardware and computational requirements. These drawbacks can be tackled by transforming the relatively complex dynamic hand gesture recognition task into a simpler image classification task. This paper presents a skeleton-based HGR framework that implements data-level fusion for encoding spatiotemporal information from dynamic gestures into static representational images. Said static images are subsequently processed by a custom, end-to-end trainable multi-stream CNN architecture for gesture classification. Our framework reduces the hardware and computational requirements of the HGR task while remaining competitive with the state-of-the-art on the CNR, FPHA, LMDHG, SHREC2017, and DHG142S benchmark datasets. We demonstrated the practical utility of our framework by creating a lightweight real-time application that makes use of skeleton data extracted from RGB video streams captured by a standard inbuilt PC webcam. The application operates successfully with minimal CPU and RAM footprint while achieving 93.46% classification accuracy with approximately 2s latency at 15 frames per second.

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Ammonia-fueled solar combined cycle power system: Thermal and combustion efficiency enhancement via solar-driven ammonia decomposition

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International Journal of Hydrogen Energy 2025年 142卷 232-243页

作者： Dmitry Pashchenko Department of Mechanical Engineering (Robotics) and MATEC Guangdong Technion–Israel Institute of Technology 241 Daxue Road Shantou Guangdong 515063 China Faculty of Mechanical Engineering Technion - Israel Institute of Technology Technion City Haifa 3200003 Israel

Ammonia, derived from renewable energy sources, has garnered significant international attention as a carbon-free fuel for power generation. However, direct combustion of ammonia in gas turbines results in low combustion efficiency. Conversely, ammonia can be readily converted into a hydrogen-rich fuel that has higher combustion efficiency. In this paper, we studied the synergistic integration of ammonia-fed gas turbines and concentrated solar power plants, where solar energy is harnessed for the thermochemical decomposition of ammonia into hydrogen-rich gas. The hydrogen-rich gas produced on-site replaces ammonia as the fuel for the gas turbine, enhancing thermal and combustion efficiency. The study investigates the impact of operational parameters on thermal and combustion efficiency. It is established that using the proposed concept the thermal efficiency can be increased up to 3.5 % . Furthermore, a thermodynamic analysis was conducted to assess the thermal efficiency and heat balance. The effect of operational parameters such as the composition of the hydrogen-rich gas, pressure, initial temperature, and fuel-air equivalence ratio, on flame speed is analyzed. The results reveals that under gas turbine operating conditions, the flame speed ranges from 20 to 30 cm/s for 1:3 mole-to-mole ammonia-hydrogen blend.

关键词： Ammonia Gas turbine Hydrogen Renewable energy Thermodynamic analysis

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Characterization of a Rotating Magnetic Dipole Field for Contactless Detumbling of Space Debris

Characterization of a Rotating Magnetic Dipole Field for Con...

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Space robotics (iSpaRo), International Conference on

作者： Travis J. Allen Adam J. Sperry Nicholas R. Posselli Benjamin A. Minor Jake J. Abbott Department of Mechanical Engineering and the Robotics Center University of Utah Salt Lake City UT USA

ISBN: (数字)9798350367232

ISBN: (纸本)9798350367249

There is a need for the remediation of space debris, but many objects must be detumbled before they can be safely serviced. In this paper, we describe an empirical study that is the first to evaluate the detumbling performance of a rotating magnetic dipole (MD) field. We develop a new rotatingpermanent-magnet robotic end-effector capable of generating a strong MD field that can be rotated at high speeds. We construct a low-friction experimental apparatus to simulate a tumbling object. We conduct detumbling experiments using a rotating MD field with a variety of angular velocities, as well as the same field held static in two canonical orientations. We provide an estimate of the expected performance of each method in the microgravity environment of space by correcting our data for the friction in our experimental apparatus. We find that a rotating MD field detumbles an object in finite time, whereas a static field only detumbles an object asympotically to zero angular velocity. We find that the rotating MD field substantially outperforms a static MD field in reaching approximately zero angular velocity, provided the angular velocity of the rotating MD exceeds a modest minimum value. Finally, we observe a diminishing return in performance as we continue to increase the angular velocity of the rotating MD field.

关键词： Magnetostatics Space debris Friction Angular velocity End effectors Robots

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Enhanced Optimal Control of a Magnetically Actuated Capsule Endoscope Using Electromagnetic Coils Considering Small Intestine Dynamics

Enhanced Optimal Control of a Magnetically Actuated Capsule ...

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RSI/ISM International Conference on robotics and Mechatronics (ICROM)

作者： Mahdi Jamali Mohammadreza Zarifi Khameneh Mohammadhossein Sarkhosh Hossein Nejat Pishkenari Department of Mechanical Engineering Micro/Nano Robotics Laboratory Sharif University of Technology Tehran Iran

ISBN: (数字)9798331529734

ISBN: (纸本)9798331529741

Active locomotion of capsule endoscopes has become a prominent progress in minimally invasive diagnostic procedures. Utilizing external magnetic fields for this purpose enables contactless actuation and enhanced maneuverability. This study presents an optimal control technique for magnetically actuated capsule endoscopes (MACE) within the small intestine, using a modified OCTAMAG setup. The objective is to minimize input currents while ensuring accurate path tracking, thereby preventing coil overheating and avoiding actuation inaccuracies. A correction force is also incorporated into the controller to stabilize it against external disturbances. The proposed method is evaluated using a path inspired by the small intestine and compared to conventional PID control. Results show that the optimal controller achieves superior path tracking while maintaining input currents within safe limits. Additionally, the disturbance rejection capabilities of the optimal controller are comparable to those of the PID.

关键词： Coils Intestines Accuracy Uncertainty Endoscopes System performance Optimal control Electromagnetics Robots Standards

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Estimating Propulsion Kinetics in Absence of a Direct Measurement of the Anterior Component of Ground Reaction Force

Estimating Propulsion Kinetics in Absence of a Direct Measur...

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IEEE/RAS-EMBS International Conference on Biomedical robotics and Biomechatronics (BioRob)

作者： Hannah N. Cohen Miguel Vasquez Fabrizio Sergi Department of Biomedical and Mechanical Engineering Human Robotics Laboratory University of Delaware Newark DE USA

ISBN: (数字)9798350386523

ISBN: (纸本)9798350386530

Anterior ground reaction force (AGRF) is a common measurement of propulsion mechanics. It is typically measured using multi-axis force-plates which are not always found in robotic research labs. Here we present a comparison of models using kinematic and kinetic metrics of propulsion to estimate AGRF. Nine models using measurements of maximum vertical ground reaction force (maxVGRF), vertical ground reaction force at peak AGRF (aVGRF), maximum trailing limb angle (maxTLA), trailing limb angle at peak AGRF (aTLA) and stride length (SL) were used to predict different metrics of propulsion kinetics, including maximum AGRF (maxAGRF), propulsive impulse (PI), maximum AGRF normalized by body-weight (maxAGRFnorm), and normalized PI (PInorm) from participants walking at speeds [0.6 1.4] m/s. R2 and AICc scores were recorded for each model, and the individual participant R 2 values for the best single and two-factor models for each outcome were examined. Of the single-factor models, kinematic measurements were the best predictors of the outcome measurements. More specifically, maxAGRF/norm were best predicted by SL (R 2 = 0.91, 0.82, respectively), and PI/norm were best predicted by maxTLA (R 2 = 0.84, 0.43, respectively). For the two-factor models, maxAGRFnorm and PInorm were both best predicted by SL and aVGRFnorm, and maxVGRF yielded the best predictions for maxAGRF and PI. Models predicting maxAGRF /norm better fit individual participants than those predicting PI/norm. These results indicate that maxAGRF can be estimated with reasonable accuracy (R 2 = 0.92, RMSE of residuals: 1.5% bodyweight, equivalent to a 0.09 m/s increase in velocity) in the absence of a direct measurement of AGRF using both kinematic and kinetic measurements of propulsion.

关键词： Force measurement Atmospheric measurements Force Kinematics Predictive models Biomedical measurement Propulsion Particle measurements Kinetic theory Velocity measurement

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Model and Control Synthesis for an Active Vehicle Suspension Strut Involving a Single-Rod Electrohydraulic Actuator

Model and Control Synthesis for an Active Vehicle Suspension...

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International Carpathian Control Conference (ICCC)

作者： Marek Sibielak Jarosław Konieczny Adam Smoter Department of Process Control Faculty of Mechanical Engineering and Robotics AGH University of Krakow Krakow Poland

ISBN: (数字)9798350350708

ISBN: (纸本)9798350350715

The paper presents the synthesis of a nonlinear model of a wheeled vehicle suspension strut using an asymmetric (single-rod) electrohydraulic actuator. Due to differences in the active areas of the piston and the nonlinear nature of flows through the throttling orifices of the servo valve, the nonlinear model is characterised by increased complexity relative to systems using symmetric actuators (double rod). The paper covers the results of simulation studies to linearise the model and synthesise a linear quadratic controller based on the linearised model. The derived linear-quadratic controller was utilised to control a nonlinear model of the suspension strut. The control performance of the nonlinear active suspension strut model was compared with laboratory tests of the passive suspension system.

关键词： Suspensions (mechanical systems) Roads Orifices Wheels Process control Valves Mathematical models

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Integrating Model-Based Footstep Planning with Model-Free Reinforcement Learning for Dynamic Legged Locomotion

Integrating Model-Based Footstep Planning with Model-Free Re...

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IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)

作者： Ho Jae Lee Seungwoo Hong Sangbae Kim Mechanical Engineering Department Biomimetic Robotics Lab Massachusetts Institute of Technology Cambridge Massachusetts USA

ISBN: (数字)9798350377705

ISBN: (纸本)9798350377712

关键词： Legged locomotion Adaptation models Tracking Lips Dynamics Reinforcement learning Predictive models Turning Planning Foot

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