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  • 1
    Online Resource
    Online Resource
    Design of a Variable Stiffness Gecko-Inspired Foot and Adhesion Performance Test on Flexible Surface
    MDPI AG ; 2022
    In:  Biomimetics Vol. 7, No. 3 ( 2022-09-05), p. 125-
    Details
    In: Biomimetics, MDPI AG, Vol. 7, No. 3 ( 2022-09-05), p. 125-
    Abstract: Adhesion robots have broad application prospects in the field of spacecraft inspection, repair, and maintenance, but the stable adhesion and climbing on the flexible surface covering the spacecraft has not been achieved. The flexible surface is easily deformed when subjected to external force, which makes it difficult to ensure a sufficient contact area and then detach from it. To achieve stable attachment and easy detachment on the flexible surface under microgravity, an adhesion model is established based on the applied adhesive material, and the relationship between peeling force and the rigidity of the base material, peeling angle, and working surface stiffness is obtained. Combined with the characteristics of variable stiffness structure, the adhesion and detachment force of the foot is asymmetric. Inspired by the adhesion-detachment mechanism of the foot of the gecko, an active adhesion-detachment control compliant mechanism is designed to achieve the stable attachment and safe detachment of the foot on the flexible surface and to adapt to surfaces with different rigidity. The experimental results indicate that a maximum normal adhesion force of 7.66 N can be generated when fully extended, and the safe detachment is achieved without external force on a flexible surface. Finally, an air floating platform is used to build a microgravity environment, and the crawling experiment of a gecko-inspired robot on a flexible surface under microgravity is completed. The experimental results show that the gecko-inspired foot with variable stiffness can satisfy the requirements of stable crawling on flexible surfaces.
    Type of Medium: Online Resource
    ISSN: 2313-7673
    URL: Article
    DOI: 10.3390/biomimetics7030125
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2856245-8
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  • 2
    Online Resource
    Online Resource
    A Monocular-Visual SLAM System with Semantic and Optical-Flow Fusion for Indoor Dynamic Environments
    MDPI AG ; 2022
    In:  Micromachines Vol. 13, No. 11 ( 2022-11-17), p. 2006-
    Details
    In: Micromachines, MDPI AG, Vol. 13, No. 11 ( 2022-11-17), p. 2006-
    Abstract: A static environment is a prerequisite for the stable operation of most visual SLAM systems, which limits the practical use of most existing systems. The robustness and accuracy of visual SLAM systems in dynamic environments still face many complex challenges. Only relying on semantic information or geometric methods cannot filter out dynamic feature points well. Considering the problem of dynamic objects easily interfering with the localization accuracy of SLAM systems, this paper proposes a new monocular SLAM algorithm for use in dynamic environments. This improved algorithm combines semantic information and geometric methods to filter out dynamic feature points. Firstly, an adjusted Mask R-CNN removes prior highly dynamic objects. The remaining feature-point pairs are matched via the optical-flow method and a fundamental matrix is calculated using those matched feature-point pairs. Then, the environment’s actual dynamic feature points are filtered out using the polar geometric constraint. The improved system can effectively filter out the feature points of dynamic targets. Finally, our experimental results on the TUM RGB-D and Bonn RGB-D Dynamic datasets showed that the proposed method could improve the pose estimation accuracy of a SLAM system in a dynamic environment, especially in the case of high indoor dynamics. The performance effect was better than that of the existing ORB-SLAM2. It also had a higher running speed than DynaSLAM, which is a similar dynamic visual SLAM algorithm.
    Type of Medium: Online Resource
    ISSN: 2072-666X
    URL: Article
    DOI: 10.3390/mi13112006
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2620864-7
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  • 3
    Online Resource
    Online Resource
    Bio-Inspired Smart Machines: Structure, Mechanisms and Applications
    MDPI AG ; 2023
    In:  Machines Vol. 11, No. 3 ( 2023-03-20), p. 405-
    Details
    In: Machines, MDPI AG, Vol. 11, No. 3 ( 2023-03-20), p. 405-
    Abstract: With the long-term evolution of nature, each creature has its unique structure and function, which can adjust to unstructured environments with diversity [...]
    Type of Medium: Online Resource
    ISSN: 2075-1702
    URL: Article
    DOI: 10.3390/machines11030405
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2704328-9
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  • 4
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    Online Resource
    Equivalent Dynamic Analysis of a Cable-Driven Snake Arm Maintainer
    MDPI AG ; 2022
    In:  Applied Sciences Vol. 12, No. 15 ( 2022-07-26), p. 7494-
    Details
    In: Applied Sciences, MDPI AG, Vol. 12, No. 15 ( 2022-07-26), p. 7494-
    Abstract: In this paper, we investigate a design method for a cable-driven snake arm maintainer (SAM) and its dynamics modelling. A SAM can provide redundant degrees of freedom and high structural stiffness, as well as high load capacity and a simplified structure ideal for various narrow and extreme working environments, such as nuclear power plants. However, their serial-parallel configuration and cable drive system make the dynamics of a SAM strongly coupled, which is not conducive to accurate control. In this paper, we propose an equivalent dynamics modelling method for the strongly coupled dynamic characteristics of each joint cable. The cable traction dynamics are forcibly decoupled using force analysis and joint torque equivalent transformation. Then, the forcibly equivalent dynamic model is obtained based on traditional series robot dynamic modelling methods (Lagrangian method, etc.). To verify the correctness of the equivalent dynamics, a simple model-based controller is established. In addition, a SAM prototype is produced to collect joint angles and cable forces at different trajectories. Finally, the results of the equivalent dynamics control simulation and the prototype tests demonstrate the validity of the SAM structural design and the equivalent dynamics model.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app12157494
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2704225-X
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  • 5
    Online Resource
    Online Resource
    Mechanism Design of a Transformable Crawling Robot and Feasibility Analysis for the Unstructured Environment
    MDPI AG ; 2022
    In:  Actuators Vol. 11, No. 2 ( 2022-02-17), p. 60-
    Details
    In: Actuators, MDPI AG, Vol. 11, No. 2 ( 2022-02-17), p. 60-
    Abstract: The better application of crawl robots depends on their ability to adapt to unstructured environments with significant variations in their structural shape and size. This paper presents the design and analysis of a novel robot with different locomotion configurations to move through varying environments. The leg of the robot, inspired by insects, was designed as a multi-link structure, including the Hoekens linkage and multiple parallel four-link mechanisms. The end trajectory was a symmetrical closed curve composed of an approximate straight line and a shell curve with a downward opening. The special trajectory allowed the robot to share drives and components to achieve structural deformation and locomotion. The structural characteristics of the crawl robot on the inner and outer arcs were obtained based on the working space. The constraint relationship between the structure size, the radius of the arc, and the coefficient of static friction with which the robot could crawl on the arc were established. The feasible support posture and support position of the robot under different arc radii were obtained. The simulation tested the locomotion of the robot on the plane, arc, and restricted space. The robot can be used for detection, search, and rescue missions in unstructured environments.
    Type of Medium: Online Resource
    ISSN: 2076-0825
    URL: Article
    DOI: 10.3390/act11020060
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2682469-3
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  • 6
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    Online Resource
    A Novel Wheel-Legged Hexapod Robot
    MDPI AG ; 2022
    In:  Biomimetics Vol. 7, No. 4 ( 2022-09-29), p. 146-
    Details
    In: Biomimetics, MDPI AG, Vol. 7, No. 4 ( 2022-09-29), p. 146-
    Abstract: Traditional mobile robots are mainly divided into wheeled robots and legged robots. They have good performance at fast-moving speeds and crossing obstacles, and weak terrain adaptability and moving speeds, respectively. Combining the advantages of these two types mentioned, a multi-functional wheel-legged hexapod robot with strong climbing capacity was designed in this paper. Each wheel-leg of the robot is driven directly by a single motor and can move smoothly and quickly in a diagonal tripod gait. Based on the obstacle-crossing way of the wheel-leg and combined with the characteristics of insects moving stably in nature, the middle part of the robot body is wider than head and tail. Tripod gait was selected to control the robot locomotion. A series of simulations and experiments were conducted to validate its excellent adaptability to various environmental conditions. The robot can traverse rugged, broken, and obstacle-ridden ground and cross rugged surfaces full of obstacles without any terrain sensing or actively controlled adaptation. It can negotiate obstacles of approximately its own height, which is much higher than its centre of gravity range.
    Type of Medium: Online Resource
    ISSN: 2313-7673
    URL: Article
    DOI: 10.3390/biomimetics7040146
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2856245-8
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  • 7
    Online Resource
    Online Resource
    Performance Analysis of Hybrid Kinematic Mechanism for Fusion Reactor Maintenance
    MDPI AG ; 2023
    In:  Applied Sciences Vol. 13, No. 3 ( 2023-01-29), p. 1740-
    Details
    In: Applied Sciences, MDPI AG, Vol. 13, No. 3 ( 2023-01-29), p. 1740-
    Abstract: The hybrid kinematic mechanism (HKM) as an alternative remote handling subsystem of the Demonstration Fusion Power Plant (DEMO) breeding blanket (BB) is undergoing extensive theoretical analysis and feasibility verification. In this paper, the forward and inverse kinematic models of the HKM are derived by combining the Newtonian iterative method and the analytical method. Cartesian space trajectory planning is designed based on the trajectories of the HKM lifting of inboard and outboard BBs. The continuous smooth inverse kinematic solutions in the HKM joint space are obtained based on the polynomial interpolation method. For the characteristics of the HKM piston thread driving, the end-effector position error caused by the degradation of the spherical joint into a universal joint is analyzed and calculated. During the lifting of the left inboard BB, there is a maximum absolute error ∆P = 3.1 mm, and as the error continues to expand to the bottom of the BB it causes a risk of collision. Combining the overall effects of driving control, rigid–flexible coupling, etc., on position accuracy, an open-loop variable parameter error compensation plan based on the Levenberg–Marquardt (LM) nonlinear damping least-squares algorithm is proposed and validated in this paper. The simulation results show that the maximum absolute error after compensation is less than 1 mm as the mesh density increases, and the absolute position accuracy can be further improved by local mesh encryption. This study verifies the feasibility of the HKM as a BB remote handling subsystem and provides an option for high-precision control of the HKM.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app13031740
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
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  • 8
    Online Resource
    Online Resource
    Development of a Lizard-Inspired Robot for Mars Surface Exploration
    MDPI AG ; 2023
    In:  Biomimetics Vol. 8, No. 1 ( 2023-01-18), p. 44-
    Details
    In: Biomimetics, MDPI AG, Vol. 8, No. 1 ( 2023-01-18), p. 44-
    Abstract: Exploring Mars is beneficial to increasing our knowledge, understanding the possibility of ancient microbial life there, and discovering new resources beyond the Earth to prepare for future human missions to Mars. To assist ambitious uncrewed missions to Mars, specific types of planetary rovers have been developed for performing tasks on Mars’ surface. Due to the fact that the surface is composed of granular soils and rocks of various sizes, contemporary rovers can have difficulties in moving on soft soils and climbing over rocks. To overcome such difficulties, this research develops a quadruped creeping robot inspired by the locomotion characteristics of the desert lizard. This biomimetic robot features a flexible spine, which allows swinging movements during locomotion. The leg structure utilizes a four-linkage mechanism, which ensures a steady lifting motion. The foot consists of an active ankle and a round pad with four flexible toes that are effective in grasping soils and rocks. To determine robot motions, kinematic models relating to foot, leg, and spine are established. Moreover, the coordinated motions between the trunk spine and leg are numerically verified. In addition, the mobility on granular soils and rocky surface are experimentally demonstrated, which can imply that this biomimetic robot is suitable for Mars surface terrains.
    Type of Medium: Online Resource
    ISSN: 2313-7673
    URL: Article
    DOI: 10.3390/biomimetics8010044
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
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  • 9
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    Online Resource
    Design and Test of an Active Pneumatic Soft Wrist for Soft Grippers
    MDPI AG ; 2022
    In:  Actuators Vol. 11, No. 11 ( 2022-10-27), p. 311-
    Details
    In: Actuators, MDPI AG, Vol. 11, No. 11 ( 2022-10-27), p. 311-
    Abstract: An active wrist can deliver both bending and twisting motions that are essential for soft grippers to perform dexterous manipulations capable of producing a wide range movements. Currently, the versions of gripper wrists are relatively heavy due to the bending and twisting motions performed by the motors. Pneumatic soft actuators can generate multiple motions with lightweight drives. This research evaluates a pneumatic soft wrist based on four parallel soft helical actuators. The kinematics models for predicting bending and twisting motions of this soft wrist are developed. Finite element method simulations are conducted to verify the functions of bending and twisting of this wrist. In addition, the active motions of the soft pneumatic wrist are experimentally demonstrated. Based on sensitivity studies of geometric parameters, a set of parameter values are identified for obtaining maximum bending and twisting angles for a bionic human wrist. Through simulation and experimental tests of the soft wrist for a soft gripper, the desired bending and twisting motions as those of a real human hand wrist are established.
    Type of Medium: Online Resource
    ISSN: 2076-0825
    URL: Article
    DOI: 10.3390/act11110311
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2682469-3
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  • 10
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    Online Resource
    Design and Development of an Air–Land Amphibious Inspection Drone for Fusion Reactor
    MDPI AG ; 2024
    In:  Drones Vol. 8, No. 5 ( 2024-05-11), p. 190-
    Details
    In: Drones, MDPI AG, Vol. 8, No. 5 ( 2024-05-11), p. 190-
    Abstract: This paper proposes a design method for a miniature air–land amphibious inspection drone (AAID) to be used in the latest compact fusion reactor discharge gap observation mission. Utilizing the amphibious function, the AAID realizes the function of crawling transportation in the narrow maintenance channel and flying observation inside the fusion reactor. To realize miniaturization, the mobile platform adopts the bionic cockroach wheel-legged system to improve the obstacle-crossing ability. The flight platform adopts an integrated rotor structure with frame and control to reduce the overall weight of the AAID. Based on the AAID dynamic model and the optimal control method, the control strategies under flight mode, hover mode and fly–crawl transition are designed, respectively. Finally, the prototype of the AAID is established, and the crawling, hovering, and fly–crawling transition control experiments are carried out, respectively. The test results show that the maximum crawling inclination of the AAID is more than 20°. The roll angle, pitch angle, and yaw angle deviation of the AAID during hovering are all less than 2°. The landing success rate of the AAID during the fly–crawl transition phase also exceeded 77%, proving the effectiveness of the structural design and dynamic control strategy.
    Type of Medium: Online Resource
    ISSN: 2504-446X
    URL: Article
    DOI: 10.3390/drones8050190
    Language: English
    Publisher: MDPI AG
    Publication Date: 2024
    detail.hit.zdb_id: 2934569-8
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