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The robust non-singular fast terminal sliding mode (NFTSM) controller is adopted in this work to solve the problem of tracking trajectory of a mobile manipulator (MM) suffering from uncertainties. The NFTSM method has the capability to ensure convergence rate and to provide good tracking accuracy and robustness against external perturbations and parameter uncertainties (total disturbances). However, the NFTSM controller needs high discontinuous gain to reject the effect of strong disturbances, which results in vibrations in the steady-state and chattering in the control law. To solve these issues, an extended state observer–based NFTSM technique is proposed for n-degree of freedom (DoF) coupling MM. The proposed method is designed to approximate and compensate in real-time the uncertainties. It also ensures robustness against total disturbances, good convergence rate, and good tracking accuracy. The stability of the proposed control is also verified based on the Lyapunov theory. Experimental works are conducted on a 5-degree-of-freedom (5-DoF) MM where the results obtained demonstrate the effectiveness of the developed technique and prove the stability of the closed-loop system.

This paper develops an inner stator current controller based on an enhanced reaching-law-based discrete-time terminal sliding mode. The problem of tracking stator currents with high accuracy while ensuring the robustness of a six-phase induction motor in the presence of uncertain electrical parameters and unmeasurable states is tackled. The unknown dynamics are approximated by using a time delay estimation method. Then, an enhanced power-reaching law is used to make each stage of the convergence faster. A stability analysis and the system controller’s finite-time convergence are demonstrated in detail. Practical work was conducted on an asymmetrical six-phase induction machine to illustrate the developed discrete approach’s robustness and effectiveness.

Presentación realizada en el marco Proyecto PINV18-765: Vehículos aéreos no tripulados en aplicaciones para la agricultura de precisión para el monitoreo de cultivos agrícolas. Cuyo objetivo general fue: el Estudio, investigación, análisis y validación experimental de, por un lado, avanzadas estrategias de control de vuelo de vehículos no tripulados (UAV) y, por otro, de algoritmos de procesamiento de imágenes obtenidas por el UAV, orientada al análisis de cultivos agrícolas enfocado al desarrollo del sector agropecuario.

Presentación realizada en el marco Proyecto PINV18-765: Vehículos aéreos no tripulados en aplicaciones para la agricultura de precisión para el monitoreo de cultivos agrícolas. Cuyo objetivo general fue: el Estudio, investigación, análisis y validación experimental de, por un lado, avanzadas estrategias de control de vuelo de vehículos no tripulados (UAV) y, por otro, de algoritmos de procesamiento de imágenes obtenidas por el UAV, orientada al análisis de cultivos agrícolas enfocado al desarrollo del sector agropecuario.

This paper features a novel sliding mode controller for robotic arms using nonlinear model-based switching functions. The new controller is experimentally validated on a 7-DOF exoskeleton arm used for upper-limb rehabilitation applications. The proposed approach features a novel concept using model-based switching functions in the sliding mode controller, which leads to considerable simplifications on the torque control inputs. Compared to conventional linear switching functions, model-based switching functions show substantial control performance improvements on the torque inputs, such as transient constraints reduction and enhanced robustness, while maintaining a very good tracking performance. Moreover, model-based switching functions design ensures a complete decoupling of chattering effect between joint axes. Furthermore, this approach can be combined with existing chattering reduction techniques to ensure proper control of chattering levels on the torque inputs. These advantages make the practical implementation of the model-based switching functions approach particularly desirable for wearable robotics, where smooth movements and high accuracy are important requirements for patients' comfort and security.