Advanced trajectory tracking for UAVs using combined feedforward/feedback control design

Trajectory tracking is a major challenge for UAVs. The more complex the trajectory is, the more accurate tracking is required with minimum divergence from the trajectory. Apart from active trajectory tracking mechanisms, current solutions to accurate trajectory tracking in narrow areas require low speed motions. This paper presents a systematic design methodology using centralised feedforward/feedback control architecture for advanced trajectory tracking without compromising the speed of the vehicle. Using the norm as a measure for the design criteria, the proposed method proves fast tracking with no overshooting and less actuators energy compared with single degree-of-freedom feedback control method. The results are verified using simulations for two systems: a tri-rotor VTOL UAV (fully actuated system), and a quadrotor trainer (over-actuated system)

Creating inclusive spaces for partnership: Responses from local leaders engaged in a community-university partnership centre

Communities around the world are faced with challenges as they seek to address inequality in spite of larger systems designed to create dependence. In response to this, local residents have begun to develop their own solutions to address the needs of their communities. Creating spaces for capacity building and empowerment engages community members as leaders to identify and address concerns as they emerge. The Hartland Partnership Center is an example of a community-university partnership designed to meet the needs of individuals and families living on the westside of Salt Lake City. The Hartland Resident Committee (HRC) was formed to lead this endeavour by identifying what the needs of community members were and developing programs within a community learning centre located in a gateway neighbourhood for new arriving populations of immigrant and refugee background. With this pilot study, we sought not only to understand why individuals became engaged in leadership, but also why HRC members remained engaged. More specifically, we wanted to identify what it was about the HRC that helped individuals feel comfortable to share their ideas for change and growth. We identified five key methods to engage the HRC members to be leaders in their community: (1) provide opportunities for leadership development; (2) create an inclusive environment; (3) identify the common goal of the group while respecting diversity; (4) care about the lives of RC members; and (5) implement the decisions of the group. The findings of this study provide additional insights into why community members become engaged in community-university partnerships and the foundation for further research on engagement of community members as leaders. Keywords: community engagement, empowerment, capacity building, resident committee, community social wor

PID vs LQR controller for tilt rotor airplane

The main thematic of this paper is controlling the main manoeuvers of a tilt rotor UAV airplane in several modes such as vertical takeoff and landing, longitudinal translation and the most important phase which deal with the transition from the helicopter mode to the airplane mode and visversa based on a new actuators combination technique for specially the yaw motion with not referring to rotor speed control strategy which is used in controlling the attitude of a huge number of vehicles nowadays. This new actuator combination is inspired from that the transient response of a trirotor using tilting motion dynamics provides a faster response than using rotor speed dynamics. In the literature, a lot of control technics are used for stabilizing and guarantee the necessary manoeuvers for executing such task, a multiple Attitude and Altitude PID controllers were chosen for a simple linear model of our tilt rotor airplane in order to fulfill the desired trajectory, for reasons of complexity of our model the multiple PID controller doesnt take into consideration all the coupling that exists between the degrees of freedom in our model, so an LQR controller is adopted for more feasible solution of complex manoeuvering, the both controllers need linearization of the model for an easy implementation

Design and Control of UAV Systems: A Tri-Rotor UAV Case Study

The field of UAV systems is an active research area with potential for development and enhancement in various perspectives. This thesis investigates different issues related to the design, operation and control of UAV systems with a focus on the application side of each proposed solution where the implementation side and applicability of the proposed solutions are always considered with high priority. The thesis discusses unmodeled actuator dynamics and their effect on UAV systems when using feedback linearisation to linearize nonlinear models of UAVs. The analysis shows potential risk when implementing feedback linearisation and neglecting actuator dynamics even for first order actuator system. A solution algorithm of two stage feedback linearisation is proposed to handle actuator dynamics and linearize the main dynamics of the system. In the field of design and operation of UAVs, this thesis proposes a systematic design procedure for electric propulsion systems that are widely used in UAVs. The design procedure guides the designer step by step to achieve minimum propulsion system weight or maximum flight time or a trade off between the two factors from the supplied solution sets. On the navigation side, the thesis proposes a new indoor navigation system that is easy to implement and less costly compared with other indoor navigation systems. The proposed system can be classified under computer-vision based navigation systems, however, it needs less information and less computational capacity. The thesis also contributes to the structure design of UAV systems by producing a novel tri-rotor UAV platform. The proposed UAV is novel in structure and design and has a centralized control system that stabilizes and tracks both rotational and transitional motion of the vehicle simultaneously

Présentation

Éléments de problématisation Codification des savoirs scolaires ou académiques, rhétorique de la connaissance, idiomaticité des énoncés savants : quelque formulation que l’on retienne il s’agit invariablement de l’expression d’une problématique associant l’objet soumis à examen – que l’on appellera par commodité le référent – à sa formalisation dans un langage naturel, ou artificiel d’ailleurs. Tel est l’objet assigné à ce numéro de Pratiques : décrire les itinéraires épistémologiques qui con..

Tuning and Testing Dual Sensor Technology in Digital Implementation for Single-Axis Nanopositioning Stages

This study produces a practical tuning algorithm to tune the force feedback control for nanopositioning systems. The tuning procedure uses standard measures such as bandwidth and oscillation to tune the parameters of the force feedback loop and the outer loop. The study also discusses the impact of each control parameter on the overall performance of the system. The results include experimental data from the stage NPS-X-15A from Queensgate

On the Performance of Energy Criterion Method in Wi-Fi Transient Signal Detection

In the development of radiofrequency fingerprinting (RFF), one of the major challenges is to extract subtle and robust features from transmitted signals of wireless devices to be used in accurate identification of possible threats to the wireless network. To overcome this challenge, the use of the transient region of the transmitted signals could be one of the best options. For an efficient transient-based RFF, it is also necessary to accurately and precisely estimate the transient region of the signal. Here, the most important difficulty can be attributed to the detection of the transient starting point. Thus, several methods have been developed to detect transient start in the literature. Among them, the energy criterion method based on the instantaneous amplitude characteristics (EC-a) was shown to be superior in a recent study. The study reported the performance of the EC-a method for a set of Wi-Fi signals captured from a particular Wi-Fi device brand. However, since the transient pattern varies according to the type of wireless device, the device diversity needs to be increased to achieve more reliable results. Therefore, this study is aimed at assessing the efficiency of the EC-a method across a large set of Wi-Fi signals captured from various Wi-Fi devices for the first time. To this end, Wi-Fi signals are first captured from smartphones of five brands, for a wide range of signal-to-noise ratio (SNR) values defined as low (−3 to 5 dB), medium (5 to 15 dB), and high (15 to 30 dB). Then, the performance of the EC-a method and well-known methods was comparatively assessed, and the efficiency of the EC-a method was verified in terms of detection accuracy.publishedVersio

Crecimiento y reproducción de la dorada, Sparus aurata en la laguna de Mellah (nordeste de Argelia)

Gilthead seabream Sparus aurata (L.), a protandrous hermaphrodite, was caught in Mellah lagoon (Algeria) from July 1997 to June 1998. Its age, growth and reproduction were studied. Fish ranged in size from 157 to 610 mm total length and weighed from 60 to 4000 g wet weight. There were fish aged 1+ to 7+ years old in the samples. Direct scale readings were made by counting the number of rings. These were compared with the data obtained by backcalculating the lengths at different ages. These two methods were in agreement and showed that the growth rate of gilthead seabream in Mellah lagoon is very high compared to other study areas. The growth parameters of the Von Bertalanffy equation were: L∞ = 55.33 cm, K = 0.513, t0 = - 0.282, with F’ = 7.359. The fitted length-weight relationship was W = 1.292. 10-2 L3.06. The reproductive season extended from October to January, with a peak in December. Sex inversion occurred at a total length of 44 cm. Sexual maturity was reached at 32.6 cm total length.Se capturaron ejemplares de dorada, Sparus aurata (L.), una especie hermafrodita proterándrica, en la laguna de Mellah (Argelia) entre Julio de 1997 y Junio de 1998. Se estudiaron la edad, el crecimiento y la reproducción. La talla de los ejemplares estudiados osciló entre 157 y 610 mm de longitud total, pesando entre 60 y 4000 g (peso fresco). Ejemplares de edades comprendidas entre 1+ y 7+ años estuvieron presentes en las muestras. La lectura directa de algunas escamas mediante el conteo del número de anillos fue comparada con los datos obtenidos por retrocálculo de las tallas a distintas edades. Los resultados de los dos métodos fueron similares y mostraron que la tasa de crecimiento de la dorada en la laguna de Mellah es muy alta en comparación con otras áreas de estudio. Los parámetros de crecimiento de la ecuación de Von Bertalanffy fueron los siguientes: L• = 55.33 cm, K = 0.513, t0 = - 0.282, con F’ = 7.359. El ajuste de la relación talla – peso fue el siguiente: W = 1.292. 10-2 L3.06. La estación reproductiva estuvo comprendida entre Octubre y Enero, con un pico en Diciembre. La inversión de sexo tuvo lugar a una longitud total de 44 cm. La madurez sexual se alcanzó a una longitud total de 32.6 cm.