Towards Precise Positioning and Movement of UAVs for Near-Wall Tasks in GNSS-Denied Environments

Abstract: UAVs often perform tasks that require flying close to walls or structures and in environments where a satellite-based location is not possible. Flying close to solid bodies implies a higher risk of collisions, thus requiring an increase in the precision of the measurement and control of the UAV’s position. The aerodynamic distortions generated by nearby walls or other objects are also relevant, making the control more complex and further placing demands on the positioning system. Performing wall-related tasks implies flying very close to the wall and, in some cases, even touching it. This work presents a Near-Wall Positioning System (NWPS) based on the combination of an Ultra-wideband (UWB) solution and LIDAR-based range finders. This NWPS has been developed and tested to allow precise positioning and orientation of a multirotor UAV relative to a wall when performing tasks near it. Specific position and orientation control hardware based on horizontal thrusters has also been designed, allowing the UAV to move smoothly and safely near walls.Ministerio de Ciencia, Innovación y Universidades; RTI2018-101114-B-I00), Xunta de Galicia; ED431C2017/12)

A New Approach to Laminar Flowmeters

After studying the performance and characteristics of actual laminar flowmeters a new disposition for this type of sensors is proposed in such a way that the measurement errors introduced by the intrinsic nature of the device can be minimized. The preliminary study shows that the developing entry region introduces non-linearity effects in all these devices. These effects bring about not only errors, but also a change in the slope of the linear calibration respect of the Poiseuille relation. After a subsequent analysis on how these non-linearity errors can be reduced, a new disposition of this type of flowmeters is introduced. This device makes used of flow elements having pressure taps at three locations along its length and connected to three isolated chambers. In this way, the static pressure can be measured at three locations and contributed to by the pressure taps at the level of each chamber. Thus the linearization error is reduced with an additional advantage of producing a reduced pressure drop.Xunta de Galicia; 07DPI166EXunta de Galicia; 08TIC035

A Kalman Filter for Nonlinear Attitude Estimation Using Time Variable Matrices and Quaternions

[Abstract] The nonlinear problem of sensing the attitude of a solid body is solved by a novel implementation of the Kalman Filter. This implementation combines the use of quaternions to represent attitudes, time-varying matrices to model the dynamic behavior of the process and a particular state vector. This vector was explicitly created from measurable physical quantities, which can be estimated from the filter input and output. The specifically designed arrangement of these three elements and the way they are combined allow the proposed attitude estimator to be formulated following a classical Kalman Filter approach. The result is a novel estimator that preserves the simplicity of the original Kalman formulation and avoids the explicit calculation of Jacobian matrices in each iteration or the evaluation of augmented state vectors.Ministerio de Ciencia, Innovación y Universidades; RTI2018-101114-B-I00Xunta de Galicia; ED431C 2017/1

Potential and Limitations of an Improved Method to Produce Dynamometric Wheels

[Abstract:] A new methodology for the estimation of tyre-contact forces is presented. The new procedure is an evolution of a previous method based on harmonic elimination techniques developed with the aim of producing low cost dynamometric wheels. While the original method required stress measurement in many rim radial lines and the fulfillment of some rigid conditions of symmetry, the new methodology described in this article significantly reduces the number of required measurement points and greatly relaxes symmetry constraints. This can be done without compromising the estimation error level. The reduction of the number of measuring radial lines increases the ripple of demodulated signals due to non-eliminated higher order harmonics. Therefore, it is necessary to adapt the calibration procedure to this new scenario. A new calibration procedure that takes into account angular position of the wheel is completely described. This new methodology is tested on a standard commercial five-spoke car wheel. Obtained results are qualitatively compared to those derived from the application of former methodology leading to the conclusion that the new method is both simpler and more robust due to the reduction in the number of measuring points, while contact forces’ estimation error remains at an acceptable level.Ministerio de Ciencia e Innovación; TRA2012-38826-C02-01Madrid (Comunidad Autónoma); S2013-MIT271

Proyecto de diseño y desarrollo conceptual de un catamarán, de menos de 5 m con acceso y posibilidad de tripulación universal, basado en el modelo xouva

Banco de experiencias de Aprendizaxe Servizo. Convocatoria 2019/202

Proxectos de deseño e desenvolvemento de elementos medioambientalmente sostibles: deseñando con responsabilidade medioambiental

Banco de experiencias de Aprendizaxe Servizo. Convocatoria 2020/202

Desarrollo de una metodología experimental para el estudio de estrategias de control en vehículos automóviles

[Resumen] En este trabajo se propone el desarrollo de un nuevo estimador del estado cinemático del chasis de un vehículo automóvil, utilizando una formulación con cuaternas y matrices de estado variables en el tiempo, que permite modelar el estado cinemático del vehículo de forma que se puede plantear un Filtro de Kalman lineal, que mantiene su optimalidad, y no tiene singularidades. El estimador está íntimamente relacionado con los sensores que utiliza, y con las ecuaciones que modelan el comportamiento del sistema que se pretende estimar; por tanto, en este trabajo se presenta también el desarrollo de un nuevo sistema de sensorización, actuadores, sistemas de control, estructura mecánica y modelo matemático que forman una plataforma experimental basada en un vehículo, con la que se podrá, en el futuro, verificar el comportamiento del estimador propuesto, contrastarlo con otros estimadores existentes y ensayar nuevas estrategias de control