En este artículo se aborda el control cartesiano para seguimiento de trayectorias en robots manipuladores. Las trayectorias deseadas se proponen en espacio cartesiano. Mediante la cinemática inversa ...se obtienen las trayectorias deseadas en espacio articular; a partir de la cinemática diferencial, se obtiene el jacobiano el cual sirve para obtener las velocidades y aceleraciones articulares deseadas. El modelo dinámico se obtiene mediante las ecuaciones de movimiento de Euler-Lagrange. El objetivo de seguimiento de trayectorias en el espacio cartesiano o articular se logra utilizando solamente mediciones de posición como retroalimentación, por lo que se omite el uso de filtros y observadores de velocidad. Se prueba estabilidad asintótica global en el sentido de Lyapunov para el caso de trayectorias articulares y estabilidad asintótica local para trayectorias en espacio cartesiano. Se ilustran los resultados mediante simulaciones numéricas en un robot de dos grados de libertad y la validación experimental en un robot SCARA.
The COVID-19 pandemic has been the most critical public health issue in modern history due to its highly infectious and deathly potential, and the limited access to massive, low-cost, and reliable ...testing has significantly worsened the crisis. The recovery and the vaccination of millions of people against COVID-19 have made serological tests highly relevant to identify the presence and levels of SARS-CoV-2 antibodies. Due to its advantages, microfluidic-based technologies represent an attractive alternative to the conventional testing methodologies used for these purposes. In this work, we described the development of an automated ELISA on-chip capable of detecting anti-SARS-CoV-2 antibodies in serum samples from COVID-19 patients and vaccinated individuals. The colorimetric reactions were analyzed with a microplate reader. No statistically significant differences were observed when comparing the results of our automated ELISA on-chip against the ones obtained from a traditional ELISA on a microplate. Moreover, we demonstrated that it is possible to carry out the analysis of the colorimetric reaction by performing basic image analysis of photos taken with a smartphone, which constitutes a useful alternative when lacking specialized equipment or a laboratory setting. Our automated ELISA on-chip has the potential to be used in a clinical setting and mitigates some of the burden caused by testing deficiencies.
This paper deals with the design of observer-based nonlinear control of blood glucose concentration (BGC) of Type 1 diabetes mellitus (T1DM) patients in a Linear Matrix Inequality (LMI) framework. ...The controller design relies on the information of the states obtained from a nonlinear observer. The control law is derived using feedback linearisation and regional pole placement technique. Further, a numerical optimisation method is proposed for the computation of the controller gains by capturing the relationship between transformed domain and original domain dynamics by iteratively tuning the circular LMI region parameters (‘q’ and ‘r’) such that the locations of closed-loop poles of the original nonlinear system are attained. The proposed controller can deliver robust closed-loop response of BGC within a specified range of parametric uncertainty and meal disturbances owing to the appropriately tuned bound of LMI region parameters. The performance of the proposed controller is tested for 100 virtual T1DM patients in the presence of parametric uncertainty and uncertain meal disturbance. Both severe hypoglycemia (<50 mg/dl) and post-prandial hyperglycemia are avoided by the proposed scheme for nominal and uncertain parameters.
In order to ensure trajectory tracking on a two degrees-of-freedom self-balancing robot (SBR) a control scheme, based on the combination of adaptive neural networks and input–output linearization, is ...presented in this paper. Both external and internal dynamics are analyzed and proof of uniform ultimate boundedness of the position errors is given. The controller performance is assessed via real-time experiments and compared with respect to other control schemes. Better tracking accuracy and disturbance rejection capability is produced by the introduced controller.
The purpose of this paper is to introduce a new trajectory tracking controller applied to the Furuta pendulum; where the arm tracks a desired time-varying trajectory, while the pendulum remains ...regulated at the upward position. This controller is derived from the input-output feedback linearization technique. The rigorous analysis of the internal dynamics is presented, showing that the tracking error and the regulation error trajectories are uniformly ultimately bounded. Experimental results show the validity of the introduced theory. Additionally, a detailed experimental study is also presented, where a PID controller and an output tracking controller are compared with respect to the new algorithm, which presents the best performance.
In this paper, a model reference adaptive control (MRAC) principle for a one-degree-of-freedom rigid-link electrically driven robot is presented. The proposed control methodology addresses the ...problem of trajectory tracking with parameter uncertainties in the dynamic model of the system and proposes adaptation laws for the electrical and mechanical parameters. Closed-loop stability is rigorously discussed, proving that the tracking error trajectories converge to the origin exponentially. With the aim of performing experimental comparisons, two control schemes are also revisited theoretically and experimentally: one is an algorithm previously reported in the literature and the other is an adaptive controller derived under the assumption that the electrical dynamics of the actuator are negligible. All the discussed controllers have been implemented in an experimental setup consisting in a rigid-link robot actuated with brushed DC motor. The comparison indicates that better results are obtained with the new MRAC scheme.
This paper discusses for the first time the effects of modeling, identifying and compensating nonlinear friction for the control of the inertia wheel pendulum and proposes a new algorithm for the ...stabilization of the pendulum at the upward unstable position. First, it is shown that the dynamic model with the proposed asymmetric Coulomb friction component characterizes better the real experimental platform of the system. Then, a feedback linearization based controller with friction compensation was designed, where theoretical results show the stability of the output trajectories. Finally, the new algorithm was experimentally compared with its version without friction compensation, showing that the new scheme yields better performance with less power consumption.
In this paper, a new composite scheme is proposed, where the total control action is composed of the sum of a feedback-linearization-based controller and an energy-based compensation. This new ...proposition is applied to the rotary inverted pendulum or Furuta pendulum. The Furuta pendulum is a well-known underactuated mechanical system with two degrees of freedom. The control objective in this case is the tracking of a desired periodic trajectory in the actuated joint, while the unactuated link is regulated at the upward position. The closed-loop system is analyzed showing uniformly ultimately boundedness of the error trajectories. The design procedure is shown in a constructive form, such that it may be applied to other underactuated mechanical systems, with the proper definitions of the output function and the energy function. Numerical simulations and real-time experiments show the practical viability of the controller. Finally, the proposed algorithm is compared with a tracking controller previously reported in the literature. The new algorithm shows better performance in both arm trajectory tracking and pendulum regulation.
•New control algorithm composed of feedback-linearization and an energy-based compensation.•The new scheme is applied for trajectory tracking of the Furuta pendulum.•Uniformly ultimately boundedness of the closed-loop system trajectories is guaranteed.•Real-time experiments and numerical simulations confirm the theoretical results.•The proposed algorithm shows better performance.
In this paper, the tracking control of periodic oscillations in an underactuated mechanical system is discussed. The proposed scheme is derived from the feedback linearization control technique and ...adaptive neural networks are used to estimate the unknown dynamics and to compensate uncertainties. The proposed neural network-based controller is applied to the Furuta pendulum, which is a nonlinear and nonminimum phase underactuated mechanical system with two degrees of freedom. The new neural network-based controller is experimentally compared with respect to its model-based version. Results indicated that the proposed neural algorithm performs better than the model-based controller, showing that the real-time adaptation of the neural network weights successfully estimates the unknown dynamics and compensates uncertainties in the experimental platform.
The purpose of this paper is to introduce a novel adaptive neural network-based control scheme for the Furuta pendulum, which is a two degree-of-freedom underactuated system. Adaptation laws for the ...input and output weights are also provided. The proposed controller is able to guarantee tracking of a reference signal for the arm while the pendulum remains in the upright position. The key aspect of the derivation of the controller is the definition of an output function that depends on the position and velocity errors. The internal and external dynamics are rigorously analyzed, thereby proving the uniform ultimate boundedness of the error trajectories. By using real-time experiments, the new scheme is compared with other control methodologies, therein demonstrating the improved performance of the proposed adaptive algorithm.
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