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International Conference on Unmanned Vehicle Systems-Oman (UVS)

作者： Ali Kafili Gavgani Amin Talaeizadeh Siamak Heidarzadeh Aria Alasty Hossein Nejat Pishkenari Department of Mechanical Engineering Advanced Research Lab for Control and Agricultural Robotics (Sharif AgRoLab) Sharif University of Technology Tehran Iran

The conventional quadrotor, characterized by four control inputs to control six degrees of freedom, is inherently under-actuated, resulting in limited independent control over pitch and roll angles. In this study, we present a configuration that incorporates four additional control inputs for manipulating the angles of the propeller axes. This addresses the previously mentioned limitations and offers additional advantages. Also, it can exhibit enhanced stability during altitude reduction by mitigating the vortex ring state. We derive the dynamic model for this system using Newthon-Euler's method. To address unmodeled dynamics, uncertainties, disturbances, and the inherent complexity of these systems, we utilize a nonlinear robust sliding mode controller. An affining process is performed to account for the non-affine nature of the dynamic equations. We introduce an optimization criteria aimed at maximizing battery life, leveraging the over-actuation of the system. This controller is applied to a dynamic system, infused with various uncertainties, such as inaccurate actuators, high-delayed servo motors, uncertain physical parameters, and wind disturbances. These factors collectively challenge the robustness of the control strategy. Additionally, the controller is implemented on a MATLAB Simscape Multibody model. Given that the controller is model-based, the consistency of the obtained results validates the accuracy of the derived dynamic equations. This research aligns with the project SAC-1, one of the objectives of our lab, Sharif AgRoLab.

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Stable CoM Trajectory Generation for Biped Robots based on Heuristic Capture Point Tracking Approach

Stable CoM Trajectory Generation for Biped Robots based on H...

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IEEE Punecon

作者： Kumod K. Sharma Sunil Nimje S. E. Talole Center for Systems and Technologies for Advanced Robotics Research & Development Estt (Engrs) Pune India Department of Mechanical Engineering Defence Institute of Advanced Technology Pune India

ISBN: (数字)9798331527822

ISBN: (纸本)9798331527839

Biped locomotion is a complex phenomenon. As the bipedal robotic system possesses multiple degrees of freedom (DoF), the resulting dynamics is highly nonlinear and coupled. However for practical purposes, reduced and simplified dynamical models such as Linear Inverted Pendulum Model (LIPM) have been widely used for gait generation. In this work, an LIPM based Capture Point (CP) method has been worked out to achieve stable and robust walk for biped robot. An existing algorithm has been modified to avoid infeasibility of solution while generating the desired trajectories of Zero Moment Point (ZMP), CP and Center of Mass (CoM) for stable bipedal locomotion and the efficacy of the approach is validated through simulations. It is shown that the modification also offers an approach to adjust footprint up to a certain extent according to design requirements or terrain conditions.

关键词： Legged locomotion Simulation Heuristic algorithms Trajectory Nonlinear dynamical systems Robots

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Self-Tuning PID Controller for an Arm-Angle Adjustable Quadrotor Using an Actor-Critic-Based Neural Network

Self-Tuning PID Controller for an Arm-Angle Adjustable Quadr...

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Iranian Conference on Intelligent Systems (ICIS)

作者： Arshia Rezaei Amin Talaeizadeh Aria Alasty Department of Mechanical Engineering Advanced Research Lab for Control and Agricultural Robotics (Sharif AgRoLab) Sharif University of Technology Tehran Iran

ISBN: (数字)9798331507565

ISBN: (纸本)9798331507572

The increasing prevalence of multirotors necessitates the development of new configurations for specific applications. Innovative morphing of multirotors has enhanced their stability, maneuverability, agility, and overall performance. The utilization of Artificial Intelligence (AI) in robotics has enabled robots to exhibit autonomous behaviors in areas such as control, path planning, state estimation, system identification, and image processing. This paper introduces a novel approach to improving the control system of an adjustable arm-angle quadrotor through the integration of a self-tuning Proportional-Integral-Derivative (PID) controller, utilizing an Actor-Critic-based Neural Network (NN). Arm-angle adjustable quadrotors, with their complex and variable dynamics, present challenges in achieving optimal control performance across different arm angles. Traditional PID controllers often struggle to adapt efficiently to these dynamics. To address this issue, the Actor-Critic framework from reinforcement learning is employed to develop a self-tuning mechanism for the PID controller. The Actor network learns the optimal control actions, while the Critic network evaluates the performance of the control system, enabling continuous improvement. Extensive Software-in-the-Loop (SIL) and Hardware-in-the-Loop (HIL) tests demonstrate the effectiveness and feasibility of the proposed approach in achieving robust and adaptive control for tilt-arm quadrotors under diverse operating conditions. The results highlight the superiority of the Actor-Critic-based self-tuning PID controller over conventional methods, showcasing its potential for real-world devlopment in autonomous aerial systems.

关键词： Uncertainty Optimal control Reinforcement learning Artificial neural networks Autonomous aerial vehicles Real-time systems Adaptive control Robots Tuning Quadrotors

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Experimental Study on the Improvement of Yaw Stability by Coordination Control between the Caudal Fin and Anal Fin

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Journal of Bionic engineering 2022年第5期19卷 1261-1271页

作者： Jiang Ding Changzhen Zheng Chaocheng Song Qiyang Zuo Yaohui Xu Bingbing Dong Jiaxu Cui Kai He Fengran Xie College of Mechanical Engineering Guangxi UniversityNanning 530004China Guangxi Key Lab of Manufacturing System and Advanced Manufacturing Technology Nanning 530004China Shenzhen Institute of Advanced Technology Chinese Academy of SciencesShenzhen 518055China Shenzhen Key Laboratory of Precision Engineering Shenzhen 518055China University of Chinese Academy of Sciences Beijing 100049China College of Mechanical Automation Wuhan University of Science and TechnologyWuhan 430000China SIAT Branch Shenzhen Institute of Artificial Intelligence and Robotics for SocietyShenzhen 518055China

Due to the unique locomotion,the head-shaking problem of biomimetic robotic fish inevitably occurs during rectilinear locomotion,which strongly hinders its practical *** this paper,we experimentally study this problem by proposing the method of coordination control between the caudal fin and anal ***,an untethered biomimetic robotic fish,equipped with an anal fin,a caudal fin and two pectoral fins,is developed as the experimental ***,a Central Pattern Generator(CPG)-based controller is used to coordinate the motions of the anal fin and caudal ***,extensive experiments are conducted to explore different combinations of the flapping frequencies,the flapping amplitudes,and the phase differences between the anal fin and caudal ***,through proper control of the anal fin,the amplitude of the yaw motion can be as small as 4.32°,which sees a 65%improvement compared to the scenario without anal fin,and a 57%improvement compared to that with a stationary anal *** paper provides a novel way to alleviate the head-shaking problem for biomimetic robotic fish,and first test this method on an untethered,freely swimming robotic platform,which can shed light on the development of underwater robotics.

关键词： Biomimetic robotic fish Anal fin Head-shaking Yaw stability

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Kinematics Analysis and Singularity Avoidance of a Parallel Mechanism with Kinematic Redundancy

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Chinese Journal of mechanical engineering 2022年第5期35卷 244-261页

作者： Chaoyu Shen Haibo Qu Sheng Guo Xiao Li Robotics Research Center School of MechanicalElectronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China China Waterborne Transport Research Institute Beijing 100088China Key Laboratory of Vehicle Advanced Manufacturing Measuring and Control TechnologyMinistry of EducationBeijing Jiaotong UniversityBeijing 100044China

The kinematic redundancy is considered as a way to improve the performance of the parallel *** this paper,the kinematics performance of a three degree-of-freedom parallel mechanism with kinematic redundancy(3-DOF PM-KR)and the influence of redundant parts on the PM-KR are ***,the kinematics model of the PM-KR is *** inverse solutions,the Jacobian matrix,and the workspace of the PM-KR are ***,the influence of redundancy on the PM-KR is *** there exists kinematic redundancy,the PM-KR possesses fault-tolerant *** locking one actuating joint or two actuating joints simultaneously,the fault-tolerant workspace is *** the position of the redundant part is changed,the workspace and singularity will be *** results show that kinematic redundancy can be used to avoid ***,the simulations are performed to prove the theoretical analysis.

关键词： Parallel mechanism Kinematic redundancy Singularity Simulation analysis

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A Fault Detection Method Based on Bearing Dynamics with Multi-frequency Sinusoidal Signal 41

A Fault Detection Method Based on Bearing Dynamics with Mult...

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第41届中国控制会议

作者： Xiaohong Li Zhicheng Li Zaiyue Yang Shenzhen Key Laboratory of Biomimetic Robotics and Intelligent Systems Department of Mechanical and Energy Engineeringand the Guangdong Provincial Key Laboratory of Human-Augmentation and Rehabilitation Robotics in UniversitiesSouthern University of Science and Technology Academy for Advanced Interdisciplinary Studies Southern University of Science and Technology

ISBN: (数字)9789887581536

ISBN: (纸本)9781665482561

Bearing is a common and important component in the industry,and it is crucial to detect and diagnose its working *** to the characteristic the motion process of the bearing that is a periodic nonlinear system with sinusoidal input,a bearing fault detection method based on the nonlinear system with multi-frequency sinusoidal input is *** the dynamics modeling of the motion for the bearing,it is found that its input and output have the characteristics of almost periodic *** the periodogram-based asymptotic local fault detection method,the fault detection problem is transformed into a hypothesis test problem,and a threshold is obtained by the given confidence and the degree of freedom of a specific frequency *** method can effectively and quickly monitor the early minor faults in strong noise *** realization and performance of this bearing detection method are illustrated by the simulated vibration signal of the bearing.

关键词： Bearing dynamics model fault detection sinusoidal signal statistical methods

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Evolution of Iron-Based Metallic Glass Composite Coating with Enhanced Corrosion Resistance and Biocompatibility

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Arabian Journal for Science and engineering 2024年第8期49卷 10547-10559页

作者： Ibrahim, Mahmoud Z. Sarhan, A.A.D. Kuo, T.Y. Yusof, Farazila Hamdi, M. Chang, C.P. Lee, T.M. Chien, C.S. Department of Mechanical Engineering Faculty of Engineering Ain Shams University Cairo 11517 Egypt Advanced Manufacturing & Material Processing (AMMP) Research Centre Department of Mechanical Engineering Faculty of Engineering University of Malaya Kuala Lumpur 50603 Malaysia Department of Mechanical Engineering Faculty of Engineering University of Malaya Kuala Lumpur 50603 Malaysia Department of Mechanical Engineering King Fahd University of Petroleum and Minerals Dhahran 31261 Saudi Arabia Interdisciplinary Research Centre for Intelligent Manufacturing & Robotics King Fahd University of Petroleum and Minerals Dhahran 31261 Saudi Arabia Department of Mechanical Engineering Southern Taiwan University of Science and Technology Tainan 701 Taiwan Department of Medical Research Chimei Medical Centre Tainan 710 Taiwan Institute of Oral Medicine National Cheng Kung University Tainan 701 Taiwan Department of Orthopaedics Chimei Foundation Hospital Tainan 710 Taiwan

Metallic glasses are a new class of metallic alloys that attract increasing attention in bone implants due to their ultrahigh wear resistance and hardness, high toughness and superior strength. However, their cytotoxicity and biocorrosion resistance are still under investigation. In this research, the cytotoxicity and biocorrosion resistance of iron-based metallic glass composite coating are explored. To approach real-life conditions, the biocorrosion resistance of the proposed coating in phosphate buffer saline (PBS) is evaluated via immersion test for 30 days followed by an electrochemical corrosion test. Then, human bone cells (MG-63) are cultured on corroded samples and the cell viability is determined using MTT assay, in addition to cell attachment examination. The results revealed the formation of a metallic glass composite layer with 78.76% amorphous content. Additionally, the metallic glass composite demonstrated excellent and stable corrosion resistance in PBS over 30 days compared to the substrate. The MTT assay has shown that the cytotoxicity of iron-based metallic glass composite is within the permitted levels according to ISO 10993–5, Part 5 vol 2009. The cells were well attached to the surface besides, showing a healthy growth after 7 days of culture. These results confirm the in vitro biocompatibility of iron-based metallic glass composite coating for biomedical implant applications. © 2023, King Fahd University of Petroleum & Minerals.

关键词： Biocorrosion Coating Cytotoxicity Iron-based metallic glass composite Joint replacement applications

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Learning Complicated Manipulation Skills Via Deterministic Policy with Limited Demonstrations

Learning Complicated Manipulation Skills Via Deterministic P...

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International Conference on advanced robotics (ICAR)

作者： Haofeng Liu Jiayi Tan Yiwen Chen Marcelo H Ang Department of Mechanical Engineering National University of Singapore Advanced Robotics Centre College of Design and Engineering National University of Singapore

Deep reinforcement learning, when combined with demonstrations, can effectively formulate policies for manipulators. However, the practical collection of ample high-quality demonstrations is time-consuming, and demonstrations generated by humans may not perfectly correspond with the operational demands of robots. These challenges are intensified by issues such as non-Markovian processes and excessive reliance on demonstrations. Our study indicates that in manipulation tasks, reinforcement learning (RL) agents are sensitive to the quality of demonstrations and struggle to adapt to those derived from humans. As a result, leveraging low-quality or scarce demonstrations to assist reinforcement learning in developing superior policies presents a significant challenge. In some cases, dependence on limited demonstrations may paradoxically impair performance. To address these challenges, we propose a novel algorithm, TD3fG (TD3 learning from a generator). This algorithm facilitates a seamless transition from learning from experts to learning from experience, enabling agents to assimilate prior knowledge while mitigating the negative impacts of the demonstrations. Our algorithm demonstrates notable improvement in the Adroit manipulator and MuJoCo tasks, even with limited demonstrations of mixed failure trajectory.

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An Optimal Control Platform for Simulation of Gait Patterns and Assistive Strategies, Based on “MATLAB-Moco” Co-Simulation

An Optimal Control Platform for Simulation of Gait Patterns ...

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Iranian Conference of Biomedical engineering (ICBME)

作者： Mohadeseh Shafie Tali Iman Kardan Alireza Akbarzadeh Dept. of Mechanical Engineering Center of Advanced Rehabilitation and Robotics Research(FUM CARE) Ferdowsi University of Mashhad(FUM) Mashhad Iran

ISBN: (数字)9798331529710

ISBN: (纸本)9798331529727

This paper addresses the field of hip assist technology by focusing on a novel closed-loop control system that uses OpenSim Moco capabilities to optimize the motion and control of musculoskeletal models. The user is equipped with an exoskeleton specifically designed for the hip joint. In the strategy for assisting the user’s hip joint, the use of a closed-loop assist control algorithm for the exoskeleton robot is crucial for walking assistance. The user reacts based on the feedback, and the amount of assist and assist performance can be observed and checked at any step, which can improve factors such as accuracy, stability, and adaptability, which are critical for human-robot exoskeleton interaction. In this paper, the OpenSim Moco toolbox and direct collocation methods are used for the simulation of a walking gait. The OpenSim Moco toolbox supports musculoskeletal models and allows the problem to be solved as an optimal control problem using the direct collocation method. However, currently this toolbox does not support implementation of closed-loop control algorithms, as it is designed to solve the entire motion at once. Given these points, this paper enhances the advantages of the OpenSim Moco toolbox by providing the possibility of step-by-step “MATLABMoco” co-simulation. The proposed structure enables the “MATLAB-Moco” package to be used for closed-loop applications, like the simulation of assistive algorithms. In this structure, at every step of the motion, the controller can receive any desired feedback from the human model and can apply the defined actions to the body. This creates an integrated and responsive interface for any closed-loop simulations that involve the human body and its reactions. In this paper, the proposed method is used for the simulation of a simple assistive strategy in which the control algorithm receives the torque produced by the user and adjusts the assistive torque accordingly. As expected, with increased levels of assistance, the

关键词： Legged locomotion Musculoskeletal system Torque Accuracy Exoskeletons Optimal control Stability analysis MATLAB Hip Robots

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Kinematic and Kinetic Analysis of 3-RRS Parallel Manipulator

Kinematic and Kinetic Analysis of 3-RRS Parallel Manipulator

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

作者： Sara Ashrafi S. Ali A. Moosavian Department of Mechanical Engineering Advanced Robotics and Automated Systems (ARAS) Lab. Center of Excellence in Robotics and Control K. N. Toosi University of Technology Tehran Iran

ISBN: (数字)9798331529734

ISBN: (纸本)9798331529741

This paper presents the Kinematic and Kinetic properties of the 3-RRS parallel manipulator that has been designed and prototyped at the ARAS Lab, together with an extensive experimental setup. Inverse and forward kinematics of the mechanism are studied, which leads to the attainment of eight possible solutions in each case, of which just one is physically acceptable and maintains its consistency in both analyses. In addition, the Jacobian matrix of the manipulator is derived for various operational scenarios. In this most recent update, a linear actuator under the moving platform is added to cancel the effect of the mass of the plate and the ball for enhancing the responsiveness of the system. Dynamic and kinetic equations are updated based on reduced gravitational effects.

关键词： Jacobian matrices Actuators Mechatronics System dynamics Dynamics Kinematics Kinetic theory Manipulator dynamics

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