Yunping Liu^{1, 2, *}, Xingxing Yan¹, Fei Yan¹, Ze Xu¹, Weiyan Shang³

CMC-Computers, Materials & Continua, Vol.63, No.1, pp. 469-487, 2020, DOI:10.32604/cmc.2020.05746

Abstract Due to the coupled motion between the rotor unmanned aerial vehicle (UAV) and the manipulator, the underactuation characteristics of the system itself, and the influence of external uncertainties, the stability of the rotor UAV’s manipulator control system is difficult to control. Based on the dynamic model of the rotor UAV, the stability of the whole UAV manipulator control system is improved by using the piecewise cost function, the compression factor particle swarm optimization (PSO) algorithm and the sliding mode PID to establish the sliding mode PID control stability method based on the PSO. Compared with the sliding mode PID control… More >

Valera-Montero LL, PJ Muñoz-Rodríguez, H Silos-Espino, S Flores-Benítez

Phyton-International Journal of Experimental Botany, Vol.85, pp. 176-183, 2016, DOI:10.32604/phyton.2016.85.176

Abstract Guava fruit produced in Calvillo, Aguascalientes (Mexico) is considered to be of the best quality in this country. Nevertheless, growers from this place empirically know that there is a noticeable variation among individual trees within the same orchard, and variation among individuals from different orchards. In order to have a clear evidence of this, morphology analysis of guava was performed taking data from seventy nine individuals out of thirty six orchards, while RAPD was performed on a subset of twenty six individuals. Similarity was found for morphology data ranging from 87-100%, while similarity from RAPD data ranged from 30- 100%.… More >

Longqing Zhang¹, Liping Bai^1,*, Xinwei Zhang², Yanghong Zhang², Lei Yang¹, Xiangdu Yan²

CMC-Computers, Materials & Continua, Vol.61, No.2, pp. 817-828, 2019, DOI:10.32604/cmc.2019.06062

Abstract The drawbacks of the traditional multi-hop structure of wireless sensor networks (WSNS) are susceptible to reflection, scattering and diffraction, serious attenuation of signal intensity and phase deviation due to various obstacles in cultivated land environment and mountains. In this paper, the wireless signal intensity is measured and curve fitting is done respectively in both open environment and obstacle-environment with both sending and receiving height of 0 m, 1 m, and 2 m. It is found out that packet loss probability is too high when an obstacle exists. In such a case, unmanned aerial vehicle (UAV) is introduced to activate terrestrial… More >

Chuanlong Li^1,2, Xingming Sun^1,2,*, Junhao Cai^3,*

Journal on Artificial Intelligence, Vol.1, No.1, pp. 1-8, 2019, DOI:10.32604/jai.2019.06064

Abstract Drone also known as unmanned aerial vehicle (UAV) has drawn lots of attention in recent years. Quadcopter as one of the most popular drones has great potential in both industrial and academic fields. Quadcopter drones are capable of taking off vertically and flying towards any direction. Traditional researches of drones mainly focus on their mechanical structures and movement control. The aircraft movement is usually controlled by a remote controller manually or the trajectory is pre-programmed with specific algorithms. Consumer drones typically use mobile device together with remote controllers to realize flight control and video transmission. Implementing different functions on mobile… More >

Yonghong Zhang^1,*, Yunfei Deng¹, Yunping Liu¹, Lihua Wang¹

CMC-Computers, Materials & Continua, Vol.59, No.3, pp. 833-851, 2019, DOI:10.32604/cmc.2019.04078

Abstract In the transition mode of quad tilt wing-unmanned aerial vehicle (QTW-UAV), the system stability of UAV will change with the tilt angle changes, which will cause serious head drop down. Meanwhile, with the complex air flow and other disturbances, the system is prone to side bias, frying, stall and other kinetic stability problems, hence the system stability analysis has become an urgent problem to be solved. To solve the stability problem, we need the quantitative criteria of system stability and effective tool of stability analysis, and can improve the stability of the motion control by optimizing the structural parameters of… More >

Liu Duo-Neng^1,2, Hou Zhong-Xi¹, Guo Zheng¹, Yang Xi-Xiang¹, Gao Xian-Zhong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.6, pp. 531-565, 2016, DOI:10.3970/cmes.2016.111.531

Abstract Dynamic soaring is a flight maneuver to exploit gradient wind field to extend endurance and traveling distance. Optimal trajectories for permissible wind conditions are generated for loitering dynamic soaring as well as for traveling patterns with a small unmanned aerial vehicle. The efficient direct collection approach based on the Runge-Kutta integrator is used to solve the optimization problem. The fast convergence of the optimization process leads to the potential for real-time applications. Based on the results of trajectory optimizations, the general permissible wind conditions which involve the allowable power law exponents and feasible reference wind strengths supporting dynamic soaring are… More >

B. J. Zhu^1,2, Z. X. Hou¹, X. Z. Wang³, Q. Y. Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.106, No.5, pp. 357-377, 2015, DOI:10.3970/cmes.2015.106.357

Abstract The paper presents a comprehensive study on the performance of long endurance and long distance trajectory optimization of engineless UAV in dynamic soaring. A dynamic model of engineless UAV in gradient wind field is developed. Long endurance and long distance trajectory optimization problems are modelled by non-linear optimal control equations. Two different boundary conditions are considered and results are compared: (i) open long endurance pattern, (ii) closed long endurance pattern, (iii) open long distance pattern. In patterns of (i) and (ii), the UAV return to original position with the maximum flying time in pattern (ii) , and in patterns of… More >

B. J. Zhu^1,2, Z. X. Hou¹, Y. F. Lu¹, S. Q. Shan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.105, No.6, pp. 467-490, 2015, DOI:10.3970/cmes.2015.105.467

Abstract This paper mainly analyzes the dynamic soaring of UAV utilizing gradient wind. Dynamic soaring is an efficient path in which UAV absorbs energy from environment to enhance its flight endurance. A set of three-dimensional point dynamic equations for a soaring aircraft in three degrees of freedom is used in calculations. To simplify the calculation, the gradient wind’s direction is taken into decomposition. The notion of trajectory subsection analysis is applied to account for the energy transformation mechanism during the dynamic soaring, and the zone of direction is converted into cutting-in angle, which is regarded as initial limiting condition in the… More >

Na Lin¹, Jiacheng Tang¹, Xianwei Li^2,3, Liang Zhao^1,*

CMC-Computers, Materials & Continua, Vol.61, No.1, pp. 323-344, 2019, DOI:10.32604/cmc.2019.05674

Abstract Path planning algorithm is the key point to UAV path planning scenario. Many traditional path planning methods still suffer from low convergence rate and insufficient robustness. In this paper, three main methods are contributed to solving these problems. First, the improved artificial potential field (APF) method is adopted to accelerate the convergence process of the bat’s position update. Second, the optimal success rate strategy is proposed to improve the adaptive inertia weight of bat algorithm. Third chaos strategy is proposed to avoid falling into a local optimum. Compared with standard APF and chaos strategy in UAV path planning scenarios, the… More >

Zhaoyue Zhang^{1, *}, Jing Zhang², Peng Wang¹, Lei Chen³

CMC-Computers, Materials & Continua, Vol.57, No.1, pp. 151-166, 2018, DOI:10.32604/cmc.2018.02890

Abstract In order to explore the safe operation of UAVs in non-segregated airspace, a collision risk model for cylindrical UAVs based on conflict areas was constructed and the risk of conflict between manned and unmanned aerial vehicles was researched. According to the results of risk analysis, a strategy for solving the conflict of aircraft is proposed, and the risk assessment experiment of unmanned aerial vehicle (UAV) in non-isolated airspace conflict is carried out. The results show that under the experimental conditions, large unmanned aerial vehicles equipped with ADS-B, TCAS and other airborne sensing systems will indeed interfere with other aircraft in… More >