Article
Mathematics
Yong Nie, Jiajia Liu, Gang Liu, Litong Lyu, Jie Li, Zheng Chen
Summary: This study develops force tracking impedance control for hydraulic series elastic actuators (SEAs), which can theoretically guarantee the force tracking performance. By introducing backstepping control to deal with high-order nonlinear dynamics and estimating environment parameters online using an adaptive method, the force tracking performance is improved.
Article
Automation & Control Systems
Hamed Toubar, Mohammad I. Awad, Mohamed N. Boushaki, Zhenwei Niu, Kinda Khalaf, Irfan Hussain
Summary: This paper presents a new Clutched Elastic Actuator (CEA) called SEADAS, which allows for discrete adjustment of stiffness. The paper discusses the working principle, design and development, as well as control methods for accurate and adaptive joint position control.
Article
Automation & Control Systems
Andrea Calanca, Enrico Sartori, Bogdan Maris
Summary: This paper analyzes the challenges of lightweight series elastic systems in force control applications and proposes a control methodology to enhance the performance robustness of existing disturbance observers. The approach is experimentally validated and successfully compared to basic control solutions and state of the art DOB approaches.
ROBOTICS AND AUTONOMOUS SYSTEMS
(2023)
Article
Automation & Control Systems
Emre Sariyildiz, Rahim Mutlu, Jon Roberts, Chin-Hsing Kuo, Barkan Ugurlu
Summary: This article presents the design and control of a new variable stiffness series elastic actuator (VSSEA). By employing a modular mechanical design approach, the stiffness modulation characteristics and power density of the actuator are effectively optimized. The proposed VSSEA features a wide range of stiffness modulation, low-energy-cost modulation, compact design, high torque density, and high-speed modulation. These features can enhance the safety and performance of advanced robotic systems and enable various control tasks without the need for complex motion control systems.
IEEE-ASME TRANSACTIONS ON MECHATRONICS
(2023)
Article
Automation & Control Systems
Jihoo Kwak, Wiha Choi, Chan Lee, Sehoon Oh
Summary: This article presents a body weight support (BWS) system that can support and assist trunk motions using series elastic actuators. The system utilizes a wire-driven mechanism with a compact planetary-geared elastic actuator to provide weight compensation and impedance compensation for trunk motion assistance. The functionality and ability of the system are validated through experiments.
IEEE-ASME TRANSACTIONS ON MECHATRONICS
(2022)
Article
Automation & Control Systems
Jiyuan Song, Aibin Zhu, Yao Tu, Xiaodong Zhang, Guangzhong Cao
Summary: This research introduces a novel crank-slider series elastic actuator (CS-SEA) for lower-limb exoskeleton joint module. Compared to traditional designs, it has better torque effect and transparency. The precise force control performance is verified through experiments, and it is successfully applied in a knee exoskeleton prototype.
IEEE-ASME TRANSACTIONS ON MECHATRONICS
(2023)
Article
Automation & Control Systems
Chao Wang, Bo Sheng, Zhenhong Li, Manoj Sivan, Zhi-Qiang Zhang, Gu-Qiang Li, Sheng Quan Xie
Summary: This article proposes a lightweight variable stiffness actuator (LVSA) driven by a novel mechanism with four sliders on a shared crank (FS2C). The FS2C mechanism allows the LVSA to simultaneously regulate the preload of four springs using only one motor and achieve a wider-range continuous stiffness adaption with reduced weight. The proposed actuator provides a solution for actuation systems that require lightweight and variable stiffness, such as wearable robotics and assistive exoskeletons.
IEEE-ASME TRANSACTIONS ON MECHATRONICS
(2023)
Article
Engineering, Mechanical
Shuaishuai Han, Haoping Wang, Yang Tian, Haoyong Yu
Summary: In this paper, a model-free force controller (MFFC) is proposed for the Series Elastic Actuator (SEA) to achieve accurate and robust force control in a physical human-robot interaction condition. The SEA force dynamics is reformulated using the ultra-local model concept, and an enhanced extended stated observer (EESO) is designed to estimate the disturbance, force velocity, and control input gain. A disturbance rejective intelligent PD (iPD) control scheme is established, and the closed-loop stability is verified using Lyapunov method. The control accuracy and robustness of the MFFC are validated in a physical human-robot interaction environment.
MECHANICAL SYSTEMS AND SIGNAL PROCESSING
(2023)
Article
Energy & Fuels
Pauli Mustalahti, Jouni Mattila
Summary: Series elastic actuators (SEAs) are commonly used in torque-controlled electric lightweight arm applications. They provide high force fidelity, shock tolerance, and force sensing. Designing controllers for hydraulic SEAs (HSEAs) is challenging, but a full state feedback controller and a position-based impedance controller have been proposed to handle the highly nonlinear dynamics behavior and control the HSEA system effectively.
Article
Engineering, Mechanical
Yingbing Su, Huaiwu Zou, Hongrun Lu, Bingshan Hu, Hongliu Yu
Summary: The bionic design of muscles is a current research hotspot. Researchers have designed bionic elastic actuators based on the Hill muscle model. In this study, a nonlinear series elastic cable actuating mechanism is designed to simulate the active contraction performance of a muscle by optimizing the parameters based on the Hill muscle model.
Article
Engineering, Mechanical
Mehmet C. Yildirim, Polat Sendur, Ahmet Talha Kansizoglu, Umut Uras, Onur Bilgin, Sinan Emre, Guney Guven Yapici, Mehmet Arik, Barkan Ugurlu
Summary: This paper presents the integrated design, development, and testing procedures for a state-of-the-art torsion-based series elastic actuator. Through a four-fold design approach, optimal torsional spring topology was unveiled, manufactured and experimentally tested, thermal response was scrutinized, and fatigue life of the spring was computed. Favorable torque tracking was achieved with a bandwidth of 19 Hz and peak-to-peak torque input of 20 Nm in preliminary torque control experiments.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE
(2021)
Article
Engineering, Mechanical
Iksu Choi, Chanyong Park, Gi-Hun Yang, Hyouk Ryeol Choi, Hugo Rodrigue, Hyungpil Moon
Summary: This study introduces a novel series elastic actuator using a mixture of air and water, which can be adjusted by changing the air-to-water ratio for different performance characteristics. The actuator was successfully applied to grasp both flexible and hard objects, demonstrating its effectiveness in force control.
JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY
(2023)
Article
Automation & Control Systems
Zongxia Jiao, Zhihui Li, Yaoxing Shang, Shuai Wu, Zengning Song, Qingxin Pan
Summary: This article proposes a novel active load sensitive electro-hydrostatic actuator (ALS) that can achieve both low heat generation and high dynamic response. By adding a special pressure following valve (PFV) to adjust the load sensitive pressure, motor heating is effectively reduced.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2022)
Article
Automation & Control Systems
Yueyue Liu, Zhijun Li, Hang Su, Chun-Yi Su
Summary: This article presents a dynamic model and whole-body trajectory control framework for an autonomous mobile manipulator suitable for flexible-joint robots, and validates the feasibility of the proposed control method through experiments.
IEEE-ASME TRANSACTIONS ON MECHATRONICS
(2021)
Article
Robotics
Chase W. Mathews, David J. Braun
Summary: This article introduces a parallel variable stiffness actuator (PVSA) consisting of a direct-drive motor connected in parallel to a variable stiffness spring. PVSA amplifies the torque and power of the motor over a range of oscillation frequencies while retaining torque control characteristics. The compact design is suitable for mobile robots and wearable devices.
IEEE TRANSACTIONS ON ROBOTICS
(2023)
Article
Robotics
Miguel Arduengo, Luis Sentis
Summary: This paper discusses the impact of automation technology development, pointing out that the increasing autonomy and human-robot interaction of intelligent robots may bring about the issue of robots directly participating in economic activities.
INTERNATIONAL JOURNAL OF SOCIAL ROBOTICS
(2021)
Article
Computer Science, Artificial Intelligence
Jaemin Lee, Efstathios Bakolas, Luis Sentis
Summary: This work proposes a trajectory generation method for robotic systems with contact kinematics and force constraints based on optimal control and reachability analysis tools, avoiding linearizing the nonlinear and coupled constraints. The method addresses the problem using sampling-based dynamic programming and rigorous reachability analysis tools, effectively handling intricate contact constraints and system dynamics in a computationally efficient way. The proposed trajectory optimization algorithm is validated using extensive numerical simulations with two legged robots.
Article
Robotics
Jaemin Lee, Junhyeok Ahn, Donghyun Kim, Seung Hyeon Bang, Luis Sentis
Summary: This paper proposes an online gain adaptation approach to enhance the robustness of the whole-body control framework for legged robots under unknown external force disturbances. The approach estimates unknown disturbances without force/torque sensors and computes adaptive gains based on stability analysis. The proposed method reduces task tracking errors under the effect of external forces and is easy-to-use without further modifications.
FRONTIERS IN ROBOTICS AND AI
(2022)
Article
Computer Science, Artificial Intelligence
Minkyu Kim, Luis Sentis
Summary: Active sensor planning is crucial for visual servoing or object tracking tasks to ensure targets are in sight. This study proposes a Dynamic Bayesian Network that utilizes contextual information to search for targets effectively, and defines the robot's utility function using information theoretic formalism.
APPLIED INTELLIGENCE
(2022)
Article
Robotics
Ye Zhao, Yinan Li, Luis Sentis, Ufuk Topcu, Jun Liu
Summary: This study proposes a formal architecture composed of task planning and control for dynamic locomotion behaviors in constrained and dynamically changing environments. By utilizing formal synthesis methods and game theory, the study achieves high-level reasoning and complex maneuvering behaviors with correctness guarantees. The proposed framework includes a locomotion planner, a locomotion controller, and a motion planner, which together enable intelligent locomotion behaviors in diverse environments.
INTERNATIONAL JOURNAL OF ROBOTICS RESEARCH
(2022)
Editorial Material
Robotics
Navinda Kottege, Luis Sentis, Dimitrios Kanoulas
FRONTIERS IN ROBOTICS AND AI
(2022)
Article
Robotics
Oussama Khatib, Mikael Jorda, Jaeheung Park, Luis Sentis, Shu-Yun Chung
Summary: This research presents a comprehensive approach to controlling a high-dimensional robotic system with complex tasks and various constraints. The approach utilizes individual objectives and constraints, simple independent controllers, potential fields, and dynamic projections to achieve whole-body control and balance stability. The framework also addresses underactuation and introduces a coordinate completion mechanism for task-space dynamic control.
INTERNATIONAL JOURNAL OF ROBOTICS RESEARCH
(2022)
Article
Chemistry, Multidisciplinary
Minkyu Kim, Ryan Gupta, Luis Sentis
Summary: This paper proposes a failure-resilient path-planning algorithm for heterogeneous robot teams to improve search efficiency in indoor and outdoor environments. The algorithm uses two steps, heterogeneous clustering and multiple traveling salesman problems, to generate high-quality candidate paths. Experimental results show that the algorithm reduces total mission time in scenarios without prior target information.
APPLIED SCIENCES-BASEL
(2022)
Article
Biodiversity Conservation
Eun-A Hwang, Ha-Kyung Kim, In-Hwan Cho, Chen Yi, Baik-Ho Kim
Summary: In this study, epilithic diatoms were collected from central South Korea and classified using both morphological and molecular analysis. The results showed clear differences among the species in terms of morphology and molecular markers. Ultrastructure analysis further revealed the unique characteristics of these diatoms.
Article
Robotics
Jee-eun Lee, Tirthankar Bandyopadhyay, Luis Sentis
Summary: This study proposes a robust planning and control framework for climbing robots to avoid slippage in unknown environments. The framework includes CoM trajectory optimization, environment parameter estimation, and weight adaptation for controlling ground reaction force distribution. Additionally, an online weight adaptation approach is presented to stabilize slippery motions.
FRONTIERS IN ROBOTICS AND AI
(2022)
Article
Environmental Sciences
Ziwei Zhang, Florian Marcel Nuta, Levente Dimen, Irfan Ullah, Xuanye Si, Junchen Yao, Yihan Zhou, Chen Yi
Summary: This paper examines the relationship between FDI, renewable energy consumption, CO2 emissions, and population health quality in China from 1980 to 2020. In the short run, FDI and CO2 emissions had no impact on health quality in China; however, in the long run, they improved life expectancy. Renewable energy had both short and long-term implications for health quality in China. The results suggest that FDI creates more jobs and improves income, leading to more accessible healthcare services in the long run. The government should provide incentives for FDI inflows that use renewable energy, and implement a carbon tax on industries with significant CO2 emissions to mitigate their effects.
FRONTIERS IN ENVIRONMENTAL SCIENCE
(2023)
Article
Telecommunications
Chen Yi, Bo Pang, Lifang He, Baoze Ma, Yong Li, Francis C. M. Lau
Summary: This letter proposes two low-complexity algorithms for blind identification of polar codes, aiming to identify code length and information bits. By taking the union of estimated code parameters and derived code parameters from the allowable shortest code without candidate code sets, our proposed scheme shows robustness to errors and significantly improves identification performance compared to existing purely code parameter estimation approaches.
IEEE COMMUNICATIONS LETTERS
(2023)
Proceedings Paper
Computer Science, Cybernetics
Junhyeok Ahn, Seung Hyeon Bang, Carlos Gonzalez, Yuanchen Yuan, Luis Sentis
Summary: This paper presents a probabilistic verification framework for legged systems, which evaluates the safety of planned trajectories by learning an assessment function from trajectories collected from a closed-loop system. The approach does not require an analytic expression of the closed-loop dynamics, enabling safety verification of systems with complex models and controllers. The framework accurately predicts the systems' safety both at the planning phase and execution phase.
2022 IEEE-RAS 21ST INTERNATIONAL CONFERENCE ON HUMANOID ROBOTS (HUMANOIDS)
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Justin Hart, Elliot Hauser, Samuel Baker, Joydeep Biswas, Junfeng Jiao, Luis Sentis
Summary: The Longitudinal Social Impacts of HRI over Long-Term Deployments Workshop aims to bring together researchers to thoroughly understand the impact of long-term robot deployments on human-robot interaction and social structures.
PROCEEDINGS OF THE 2022 17TH ACM/IEEE INTERNATIONAL CONFERENCE ON HUMAN-ROBOT INTERACTION (HRI '22)
(2022)
Article
Automation & Control Systems
Jaemin Lee, Efstathios Bakolas, Luis Sentis
Summary: This letter presents a new control paradigm, hierarchical optimal covariance control, for nonlinear systems such as robots. It formulates the control problem involving multiple operational tasks in a lexicographic order and uses linear stochastic systems and sequential semi-definite programming to solve it. The results demonstrate that this approach achieves higher accuracy for multiple hierarchical tasks compared to deterministic control models.
IEEE CONTROL SYSTEMS LETTERS
(2022)
