Precision farming is the newest agricultural approach in countries with highly mechanized field operations, and the role of unmanned ground vehicles (UGVs) in smart farming is becoming increasingly prominent. This work aimed to evaluate the stability of the DEDALO UGV developed by the University of BOLOGNA for precision orchard and vineyard management. The driving part of the machine is somewhat peculiar; it moves autonomously in the field combined with a tank to store water and pesticide mixture for crop protection, with an additional structure to carry agricultural implements. The study aimed to evaluate the stability of the agricultural unladen UGV, and mulcher and sprayer mounted configurations. In the case of the sprayer, the stability behavior was evaluated with an empty and full tank. The machine, in terms of stability, was studied both laterally and longitudinally. A theoretical model was developed based on the upstream side forces measured during experimental tipping tests. The results of the experimental data were compared with the theoretical predicted results to validate the model. In the lateral test, the average value of the limit stability angle was 48 degrees, while in the longitudinal test, it was 49 degrees. The results of the model were statistically correlative (R2 > 95) and denoted that the most stable condition occurred in the case of the UGV fitted with the mulcher in the longitudinal tipping position (56 degrees), while the most unstable condition was the case of the unladen UGV in the longitudinal tipping position (40 degrees). Although the stability problem is not directly connected with the operator, as these machines do not require a driver, the lack of stability can lead to the UGV overturning with consequent risks for the surrounding environment and damage to the UGV body.

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Evaluation of the Stability Behavior of an Agricultural Unmanned Ground Vehicle

Next generation wireless networks are expected to be greatly supported by unmanned aerial vehicles, which can act as aerial base stations and constitute a promising solution for the exorbitant rise in user demands. This is possible because of unmanned aerial vehicle characteristics such as mobility, flexibility, increased line-of-sight probability, and their ability to access unreachable locations. Extensive research is now widely performed on the deployment, performance analysis, resource management, trajectory optimization, and channel modeling in such networks. This survey article focuses on the different applications and the related algorithms for realizing aerial base stations by thoroughly reviewing each related research area. In a nutshell, this article provides key applications, challenges, and the technology used for the design and analysis of unmanned aerial vehicles as base stations.

https://doi.org/10.1177/15501329221123933

Unmanned aerial vehicles: Applications, techniques, and challenges as aerial base stations

In this article, the problem of precisely tracking a nominal trajectory by an under-actuated multirotor platform is formulated as a game against bounded external disturbances, measurement noise, and initial condition uncertainty. The nominal trajectory is composed of desired position and yaw angle, which is known to be a differentially flat output for the multirotor state dynamics. Using this property, a linearized error dynamics is obtained in the vicinity of the nominal trajectory. Using the linearized error dynamics, a linear-quadratic differential game approach is used to propose an integrated estimation and control method for trajectory tracking. A salient feature of this approach is that the drag coefficients are estimated online from the information of the tracking error. Moreover, there are only six parameters to be tuned for both estimation and control loops. The intuitive rationale behind the tuning of these parameters is also discussed. Simulations as well as experimental validations are presented to demonstrate the performance and applicability of the controllers. 

Game Theoretic Approach for Robust Trajectory Tracking by a Multirotor

A simple architecture for an autonomous mobile robot is presented. Additionally, an allocation of competencies for its components is established. The architecture is flexible and can be used as a guideline for engineers working in the design of autonomous mobile robots. Following the architecture a control level has been fully developed for a real robot, and the experimental results showed that design decisions were taken quickly.

Autonomous Mobile Robot: Guidelines for a Simple Architecture

This paper presents an experimental assessment of event-triggered sliding mode control (ET-SMC) on a Quadcopter for trajectory tracking. Sufficient triggering conditions using Lyapunov analysis and a lower bound of inter-event time to avoid Zeno behaviour are derived to ensure robust stability. Real-time flights are performed for tracking constant and time-varying trajectories. Results reveal that while using the proposed controller, there is a significant reduction in the number of updates implying a substantial saving in the computations.

Wei Sun

Papers

A survey of guidance, navigation, and control systems for autonomous multi-rotor small unmanned aerial systems