Browsing by Author "Wang, Xiaohui"

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    Learning-Based Propulsion Control for Amphibious Quadruped Robots With Dynamic Adaptation to Changing Environment
    (IEEE, 2023-12-01) Yao, Qingfeng; Meng, Linghan; Zhang, Qifeng; Zhao, Jing; Pajarinen, Joni; Wang, Xiaohui; Li, Zhibin; Wang, Cong; Department of Electrical Engineering and Automation; Robot Learning; CAS - Shenyang Institute of Automation; Heriot-Watt University; University College London
    This letter proposes a learning-based adaptive propulsion control (APC) method for a quadruped robot integrated with thrusters in amphibious environments, allowing it to move efficiently in water while maintaining its ground locomotion capabilities. We designed the specific reinforcement learning method to train the neural network to perform the vector propulsion control. Our approach coordinates the legs and propeller, enabling the robot to achieve speed and trajectory tracking tasks in the presence of actuator failures and unknown disturbances. Our simulated validations of the robot in water demonstrate the effectiveness of the trained neural network to predict the disturbances and actuator failures based on historical information, showing that the framework is adaptable to changing environments and is suitable for use in dynamically changing situations. Our proposed approach is suited to the hardware augmentation of quadruped robots to create avenues in the field of amphibious robotics and expand the use of quadruped robots in various applications.
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    Nanocellulose/LiCl systems enable conductive and stretchable electrolyte hydrogels with tolerance to dehydration and extreme cold conditions
    (Elsevier Science, 2021-03-15) Ge, Wenjiao; Cao, Shan; Yang, Yang; Rojas, Orlando J.; Wang, Xiaohui; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; South China University of Technology
    Ionically-conductive and stretchable hydrogels are ideally suited for the synthesis of flexible electronic devices. However, conventional hydrogels undergo dehydration at ambient conditions and freeze at subzero temperatures, limiting their functions. As an alternative to counteract these limitations, we propose double network hydrogels that are easily synthesized by a one-step acrylamide (AM) polymerization in the presence of cellulose nanofibrils (CNF) and LiCl. Following molecular dynamics simulation, thermogravimetric and spectroscopic (Raman and low-field nuclear magnetic resonance) analyses, we show that LiCl increases the interactions between the colloidal phase and water molecules, ensuring water holding capability at atmospheric conditions and endowing the hydrogels with freezing tolerance over a wide range of temperatures, from −80 to 25 °C. The synergy between CNF and LiCl is critical in maintaining the mechanical strength of the system, which simultaneously displays high stretchability (~748%) and ionic conductivity (2.25 S/m) at low temperatures (−40 °C). As a proof of concept, a flexible supercapacitor comprising the proposed electrolyte hydrogel is demonstrated as a reliable, low-temperature electrochemical device. Our results provide the basis for simple and universally applicable systems that fulfill the requirements of flexible electronics under extreme cold conditions.