Personal assistant robots provide novel technological solutions in order to monitor people’s activities, helping them in their daily lives. In this sense, unmanned aerial vehicles (UAVs) can also bring forward a present and future model of assistant robots. To develop aerial assistants, it is necessary to address the issue of autonomous navigation based on visual cues. Indeed, navigating autonomously is still a challenge in which computer vision technologies tend to play an outstanding role. Thus, the design of vision systems and algorithms for autonomous UAV navigation and flight control has become a prominent research field in the last few years. In this paper, a systematic mapping study is carried out in order to obtain a general view of this subject. The study provides an extensive analysis of papers that address computer vision as regards the following autonomous UAV vision-based tasks: (1) navigation, (2) control, (3) tracking or guidance, and (4) sense-and-avoid. The works considered in the mapping study—a total of 144 papers from an initial set of 2081—have been classified under the four categories above. Moreover, type of UAV, features of the vision systems employed and validation procedures are also analyzed. The results obtained make it possible to draw conclusions about the research focuses, which UAV platforms are mostly used in each category, which vision systems are most frequently employed, and which types of tests are usually performed to validate the proposed solutions. The results of this systematic mapping study demonstrate the scientific community’s growing interest in the development of vision-based solutions for autonomous UAVs. Moreover, they will make it possible to study the feasibility and characteristics of future UAVs taking the role of personal assistants.

This paper introduces a laboratory helicopter with a variable-speed rotor system based on decentralized active disturbance rejection control. The new control scheme is composed of two independent stages that are utilized to achieve the precise trajectory tracking of the generalized coordinates of the system. A simplified model is proposed at each stage, which highly simplifies the controller design task. High-gain generalized proportional integral observers are considered in order to locally estimate all the disturbances affecting each subsystem online. These estimated disturbances are used in the control law of each stage to eliminate the effects of these disturbances on the system performance. Some of the advantages of the proposed control are: it only requires the knowledge of the input gain to the subsystems (minimum information required from the dynamical models to control them); the robust controller design procedure is simplified; easier and safer implementation with regard to standard controllers; and high robustness to large initial errors, unmodeled unmatched perturbations, noisy measurements, and parametric uncertainties in the model. The effectiveness of the proposed approach has been verified with real experiments conducted on a laboratory platform.

This work is part of an ongoing research project to develop an unmanned flying social robot to monitor dependants at home in order to detect the person’s state and bring the necessary assistance. In this sense, this paper focuses on the description of a virtual reality (VR) simulation platform for the monitoring process of an avatar in a virtual home by a rotatory-wing autonomous unmanned aerial vehicle (UAV). This platform is based on a distributed architecture composed of three modules communicated through the message queue telemetry transport (MQTT) protocol: the UAV Simulator implemented in MATLAB/Simulink, the VR Visualiser developed in Unity, and the new emotion recognition (ER) system developed in Python. Using a face detection algorithm and a convolutional neural network (CNN), the ER System is able to detect the person’s face in the image captured by the UAV’s on-board camera and classify the emotion among seven possible ones (surprise; fear; happiness; sadness; disgust; anger; or neutral expression). The experimental results demonstrate the correct integration of this new computer vision module within the VR platform, as well as the good performance of the designed CNN, with around 85% in the F1-score, a mean of the precision and recall of the model. The developed emotion detection system can be used in the future implementation of the assistance UAV that monitors dependent people in a real environment, since the methodology used is valid for images of real people.

This article presents the design of a novel decentralized nonlinear multivariate control scheme for an underactuated, nonlinear and multivariate laboratory helicopter denominated the twin rotor MIMO system (TRMS). The TRMS is characterized by a coupling effect between rotor dynamics and the body of the model, which is due to the action-reaction principle originated in the acceleration and deceleration of the motor-propeller groups. The proposed controller is composed of two nested loops that are utilized to achieve stabilization and precise trajectory tracking tasks for the controlled position of the generalized coordinates of the TRMS. The nonlinear internal loop is used to control the electrical dynamics of the platform, and the nonlinear external loop allows the platform to be perfectly stabilized and positioned in space. Finally, we illustrate the theoretical control developments with a set of experiments in order to verify the effectiveness of the proposed nonlinear decentralized feedback controller, in which a comparative study with other controllers is performed, illustrating the excellent performance of the proposed robust decentralized control scheme in both stabilization and trajectory tracking tasks.

The Spanish photovoltaic sector could be a serious opportunity for the recovery and economic growth of the country, by serving as a support platform for the National Integrated Energy and Climate Plan (NIECP) 2021–2030, whose objective is to determine the lines of action required for the appropriate and efficient use of clean energy in order to benefit the economy, employment, health, and the environment. Bearing in mind the notable increase in the economic competitiveness of photovoltaic energy in Spain when compared to traditional and other renewable energy sources, it is necessary to carry out a strategic analysis of the macro-environment, using a PESTEL (Political, Economical, Social, Technological, Environmental and Legal) analysis so as to identify the most relevant external aspects that are vital for the performance of photovoltaic industries/markets and to facilitate decision making when developing short-, medium-, and long-term strategies, and the micro-environment, using Porter’s five forces (threat of new entrants, threat from substitution products and/or services, the bargain power of suppliers, the bargaining power of buyers and competitive rivalry) framework, to determine and examine the main factors that define the structure and level of competition that exists within the Spanish industry/market. The results obtained have been combined in a SWOT (Strengths, Weaknesses, Opportunities, and Threats) chart, which facilitates an understanding of the current strengths, weaknesses, opportunities, and threats as regards the photovoltaic sector in Spain.