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Symmetry
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Unmanned Vehicles, Automation, and Robotics
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Unmanned Vehicles, Automation, and Robotics

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Engineering and Materials".

Deadline for manuscript submissions: closed (31 August 2023) | Viewed by 10603

Special Issue Editors

Dr. Xuan-Mung Nguyen

E-Mail Website
Guest Editor
Department of Aerospace Engineering, Sejong University, Seoul 05006, Korea
Interests: unmanned aerial vehicles; control systems; automation; robotics
Special Issues, Collections and Topics in MDPI journals
Dr. Zhiqiang Ma

E-Mail Website
Guest Editor
School of Astronautics, Northwestern Polytechnical University, Xi'an 710072, China
Interests: robust control; physical human-robot interaction; teleoperation robot
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Control systems are playing essential roles in almost every aspect of our daily environment. The search for appropriate control designs or dynamics analysis methods for such a system often leads to solving symmetric or asymmetric problems. In dynamical systems, symmetry concepts have been used, e.g., to explain the onset of instability in feedback systems, to design observers and controllers, and to analyze synchronization properties and associated symmetry detection mechanisms. Typically, the symmetries of a physical system are preserved in the mathematical tools used to model it.

For this Special Issue, we invite specialists that are active in the field of control systems, including control theory, to submit their theoretical or experimental research.

Dr. Xuan-Mung Nguyen
Prof. Dr. Zhiqiang Ma
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • unmanned vehicles
  • autonomous vehicles
  • vehicle dynamics
  • path planning and collision avoidance
  • fault detection and fault tolerance
  • navigation with communications
  • sensors and actuators
  • controller design
  • artificial intelligence (AI) algorithms
  • robotics
  • automation

Published Papers (7 papers)

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Research

21 pages, 7112 KiB  
Article
Data-Driven Kalman Consensus Filtering for Connected Vehicle Speed Estimation in a Multi-Sensor Network
by Honghai Ji, Jie Mei, Li Wang, Shida Liu and Ye Ren
Symmetry 2023, 15(9), 1699; https://doi.org/10.3390/sym15091699 - 05 Sep 2023
Cited by 1 | Viewed by 781
Abstract
The autonomous traffic system has imposed higher requirements on the speed estimation of connected vehicles, where the speed of connected vehicles, as one of the control conditions for refined traffic management, plays a crucial role in the evaluation and optimization of network performance. [...] Read more.
The autonomous traffic system has imposed higher requirements on the speed estimation of connected vehicles, where the speed of connected vehicles, as one of the control conditions for refined traffic management, plays a crucial role in the evaluation and optimization of network performance. In this paper, we propose a multi-source speed measurement sensor network consensus filtering (MSCF) algorithm based on information weight for the problem of optimal speed consistency estimation for connected vehicles. Specifically, we first utilize dynamic linearization techniques and data-driven parameter identification algorithms to handle the derived state equations of connected vehicles. We then establish observation models for four different types of sensors and construct distributed direct and indirect measurement models by dynamically adjusting the information weights of sensor nodes. Following this, we combine the Kalman consistency filtering algorithm to derive the speed state estimation update rate and design a new state estimator to achieve the optimal consistent convergence estimation for connected vehicles’ speed. The MSCF algorithm can solve the problem of consistency filtering for noisy sensor data under observation- and communication-constrained conditions, enabling each sensor node to obtain a consistent convergence estimation value for the speed of the connected vehicle. The convergence of the algorithm is proved using the Lyapunov function. Through numerical simulation, the results are verified, indicating that compared to existing methods, this method can achieve a higher precision speed estimation effect. Full article
(This article belongs to the Special Issue Unmanned Vehicles, Automation, and Robotics)
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17 pages, 20339 KiB  
Article
An Extended Vector Polar Histogram Method Using Omni-Directional LiDAR Information
by Byunguk Lee, Wonho Kim and Seunghwan Lee
Symmetry 2023, 15(8), 1545; https://doi.org/10.3390/sym15081545 - 05 Aug 2023
Cited by 1 | Viewed by 738
Abstract
This study presents an extended vector polar histogram (EVPH) method for efficient robot navigation using omni-directional LiDAR data. Although the conventional vector polar histogram (VPH) method is a powerful technique suitable for LiDAR sensors, it is limited in its sensing range by the [...] Read more.
This study presents an extended vector polar histogram (EVPH) method for efficient robot navigation using omni-directional LiDAR data. Although the conventional vector polar histogram (VPH) method is a powerful technique suitable for LiDAR sensors, it is limited in its sensing range by the single LiDAR sensor to a semicircle. To address this limitation, the EVPH method incorporates multiple LiDAR sensor’s data for omni-directional sensing. First off, in the EVPH method, the LiDAR sensor coordinate systems are directly transformed into the robot coordinate system to obtain an omni-directional polar histogram. Several techniques are also employed in this process, such as minimum value selection and linear interpolation, to generate a uniform omni-directional polar histogram. The resulting histogram is modified to represent the robot as a single point. Subsequently, consecutive points in the histogram are grouped to construct a symbol function for excluding concave blocks and a threshold function for safety. These functions are combined to determine the maximum cost value that generates the robot’s next heading angle. Robot backward motion is made feasible based on the determined heading angle, enabling the calculation of the velocity vector for time-efficient and collision-free navigation. To assess the efficacy of the proposed EVPH method, experiments were carried out in two environments where humans and obstacles coexist. The results showed that, compared to the conventional method, the robot traveled safely and efficiently in terms of the accumulated amount of rotations, total traveling distance, and time using the EVPH method. In the future, our plan includes enhancing the robustness of the proposed method in congested environments by integrating parameter adaptation and dynamic object estimation methods. Full article
(This article belongs to the Special Issue Unmanned Vehicles, Automation, and Robotics)
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15 pages, 14326 KiB  
Article
A Novel 3D Complex Welding Seam Tracking Method in Symmetrical Robotic MAG Welding Process Using a Laser Vision Sensing
by Gong Zhang, Jing Huang, Yueyu Wu, Gen Yang, Si Di, Hai Yuan, Xuepeng Cao and Kyoosik Shin
Symmetry 2023, 15(5), 1093; https://doi.org/10.3390/sym15051093 - 16 May 2023
Cited by 2 | Viewed by 1998
Abstract
The welding seam tracking operation ensures that the welding torch of the welding robot can go with the welding seam during the whole symmetrical robotic welding procession. To achieve three-dimensional complex welding seams tracking, a four-step welding seam tracking system is suggested based [...] Read more.
The welding seam tracking operation ensures that the welding torch of the welding robot can go with the welding seam during the whole symmetrical robotic welding procession. To achieve three-dimensional complex welding seams tracking, a four-step welding seam tracking system is suggested based on segmented scanning, combined filtering, feature-point extraction, and welding path planning. From using the laser sensor installed at the end of welding robot, the welding seam data was continuously collected in multiple segments by segmented scanning. For the purpose of improving seam tracking accuracy, a combined filtering technique was used to correct the data to reduce the effects of burrs, data distortion, and noise on the surface of the weldment. Then, the feature points were collected so that the coordinate system will be calibrated to identify the welding points. Finally, a spatial welding path was obtained by welding path planning. Experimental investigations of the two-dimensional (2D) symmetrical S-shaped and three-dimensional (3D) curved welding seams were conducted. The obtained results demonstrate the proposed method can form a complete welding path. The average errors of the two weldments are about 0.296 mm and 0.292 mm, respectively. This shows that the proposed tracking method is effective and can provide a reference for the research of high-precision seam tracking and automatic welding. Full article
(This article belongs to the Special Issue Unmanned Vehicles, Automation, and Robotics)
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25 pages, 14223 KiB  
Article
Path Planning Algorithm for a Wheel-Legged Robot Based on the Theta* and Timed Elastic Band Algorithms
by Junkai Sun, Zezhou Sun, Pengfei Wei, Bin Liu, Yaobing Wang, Tianyi Zhang and Chuliang Yan
Symmetry 2023, 15(5), 1091; https://doi.org/10.3390/sym15051091 - 16 May 2023
Cited by 3 | Viewed by 1378
Abstract
Aimed at the difficulty of path planning resulting from the variable configuration of the wheel-legged robot for future deep space explorations, this paper proposes a path planning algorithm based on the Theta* algorithm and Timed Elastic Band (TEB) algorithm. Firstly, the structure of [...] Read more.
Aimed at the difficulty of path planning resulting from the variable configuration of the wheel-legged robot for future deep space explorations, this paper proposes a path planning algorithm based on the Theta* algorithm and Timed Elastic Band (TEB) algorithm. Firstly, the structure of the wheel-legged robot is briefly introduced, and the workspace of a single leg is analyzed. Secondly, a method to judge complete obstacles and incomplete obstacles according to the height of the obstacles is proposed alongside a method to search for virtual obstacles, to generate a grid map of the wheel and a grid map of the body, respectively. By dividing obstacles into complete obstacles and incomplete obstacles, the path planning of the wheel-legged robot is split into the planning of the body path and the planning of the wheel path. The body can be still simplified as a point by searching for the virtual obstacle, which avoids the difficulty of a planning path of a variable shape. Then, we proposed hierarchical planning and multiple optimization algorithms for the body path and wheel path based on the Theta* algorithm and TEB algorithm. The path can be optimized and smoothed effectively to obtain a shorter length and higher safety. On that basis, the proposed algorithm is simulated by Matlab. The results of simulations show that the algorithm proposed in this paper can effectively plan the path of the wheel-legged robot by using variable configurations for different types of obstacles. The path-planning algorithm of the wheel-legged robot proposed in this paper has a broad prospect for deep space exploration. Full article
(This article belongs to the Special Issue Unmanned Vehicles, Automation, and Robotics)
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17 pages, 11348 KiB  
Article
Optimization Design and Parameter Analysis of a Wheel with Array Magnets
by Xuan Zhang, Minglu Zhang, Shilong Jiao, Xiaojun Zhang and Manhong Li
Symmetry 2023, 15(5), 962; https://doi.org/10.3390/sym15050962 - 23 Apr 2023
Viewed by 1196
Abstract
At present, a large number of magnetic wall-climbing robots are applied to various magnetically conductive metal facades for detection and anti-corrosion work. Limited by the wall-climbing mechanism and adsorption device, most wall-climbing robots can only climb on smooth walls, and it is difficult [...] Read more.
At present, a large number of magnetic wall-climbing robots are applied to various magnetically conductive metal facades for detection and anti-corrosion work. Limited by the wall-climbing mechanism and adsorption device, most wall-climbing robots can only climb on smooth walls, and it is difficult to adapt to complex walls. Therefore, by studying the multi-media magnetic circuit conduction mechanism, a permanent magnetic adsorption wheel with a magnet array arrangement was designed in this study and applied to a hinge-type wall-climbing robot. By analyzing the influence of structural parameters on the adsorption performance and optimization design, a magnetic wheel structure with a symmetric structure that can meet a variety of adsorption requirements was obtained. To analyze the mechanical characteristics of the wall-climbing robot under complex facade conditions, we researched the adsorption performance of the designed magnetic wheel in different wall structures. Finally, the adhesion force of the magnetic wheel was verified through experimental measurements, and it was found that the hinged wall-climbing robot could adapt to different structural features and complete wall-transition and obstacle-crossing movements. Full article
(This article belongs to the Special Issue Unmanned Vehicles, Automation, and Robotics)
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24 pages, 3911 KiB  
Article
A Novel Multi-Agent Model-Free Adaptive Control Algorithm for a Class of Multivehicle Systems with Constraints
by Lipu Wu, Zhen Li, Shida Liu, Zhijun Li and Dehui Sun
Symmetry 2023, 15(1), 168; https://doi.org/10.3390/sym15010168 - 06 Jan 2023
Cited by 2 | Viewed by 1030
Abstract
To solve the problem of longitudinal cooperative formation driving control of multiple vehicles, a model-free adaptive control algorithm with constraints (cMFAC) is proposed in this paper. In the cMFAC algorithm, a dynamic linearization technique with a time-varying parameter pseudo-gradient (PG) is used to [...] Read more.
To solve the problem of longitudinal cooperative formation driving control of multiple vehicles, a model-free adaptive control algorithm with constraints (cMFAC) is proposed in this paper. In the cMFAC algorithm, a dynamic linearization technique with a time-varying parameter pseudo-gradient (PG) is used to linearize the multivehicle collaborative system. Then, a cMFAC controller is designed. The algorithm sets the input and output constraints at the same time to prevent the vehicle speed and other parameters from exceeding the specified range. The main advantage of the cMFAC algorithm is that the entire control process only needs the input and output data of each vehicle and can effectively handle the input and output constraints. In addition, the stability of the cMFAC method is verified through strict mathematical analysis, and its effectiveness is verified with semi-physical experiments based on a MATLAB/Simulink module and CarSim platform connection environment. It is worth noting that the proposed cMFAC controller is symmetric because the input cost function and PG cost function have symmetric and similar structures, and the forms of the two cost functions are the same. Full article
(This article belongs to the Special Issue Unmanned Vehicles, Automation, and Robotics)
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21 pages, 1355 KiB  
Article
A New Study on Optimization of Four-Bar Mechanisms Based on a Hybrid-Combined Differential Evolution and Jaya Algorithm
by Sy Nguyen-Van, Qui X. Lieu, Nguyen Xuan-Mung and Thi Thanh Nga Nguyen
Symmetry 2022, 14(2), 381; https://doi.org/10.3390/sym14020381 - 14 Feb 2022
Cited by 8 | Viewed by 2351
Abstract
In mechanism design with symmetrical or asymmetrical motions, obtaining high precision of the input path given by working requirements of mechanisms can be a challenge for dimensional optimization. This study proposed a novel hybrid-combined differential evolution (DE) and Jaya algorithm for the dimensional [...] Read more.
In mechanism design with symmetrical or asymmetrical motions, obtaining high precision of the input path given by working requirements of mechanisms can be a challenge for dimensional optimization. This study proposed a novel hybrid-combined differential evolution (DE) and Jaya algorithm for the dimensional synthesis of four-bar mechanisms with symmetrical motions, called HCDJ. The suggested algorithm uses modified initialization, a hybrid-combined mutation between the classical DE and Jaya algorithm, and the elitist selection. The modified initialization allows generating initial individuals, which are satisfied with Grashof’s condition and consequential constraints. In the hybrid-combined mutation, three differential groups of mutations are combined. DE/best/1 and DE/best/2, DE/current to best/1 and Jaya operator, and DE/rand/1, and DE/rand/2 belong to the first, second, and third groups, respectively. In the second group, DE/current to best/1 is hybrid with the Jaya operator. Additionally, the elitist selection is also applied in HCDJ to find the best solutions for the next generation. To validate the feasibility of HCDJ, the numerical examples of the symmetrical motion of four-bar mechanisms are investigated. From the results, the proposed algorithm can provide accurate optimal solutions that are better than the original DE and Jaya methods, and its solutions are even better than those of many other algorithms that are available in the literature. Full article
(This article belongs to the Special Issue Unmanned Vehicles, Automation, and Robotics)
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