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This work discusses the design and implementation of a robust control strategy based on integral sliding mode (ISM) for tracking a reference trajectory by a nonholonomic wheeled mobile robot (WMR). A state feedback control law using dynamic feedback linearization is adopted to design the controller for the unperturbed dynamics of the WMR. To nullify the effects of perturbations in the WMR and to retain the performance of the nominal controller, the ISM control scheme is introduced, which uses discontinuous control to guarantee the robustness of the closed‐loop system. To relax the frequent use of the communication network due to the continuous exchange of the sensor measurements, the control law is redesigned using event‐based sampled data information. The control signal is updated in an aperiodic manner by designing a novel triggering rule where the triggering occurs only when either of the two sampling errors violates a predefined threshold condition. This design approach gives a balanced solution for a networked WMR regarding network usage and control performance. Finally, a simulation study with comparative analysis and hardware‐in‐loop testing of the proposed controller is performed on a mobile robot system to establish the feasibility of the theoretical results. [ABSTRACT FROM AUTHOR]

This paper addresses the trajectory tracking control of an uncertain robotic manipulator in a networked environment. To avoid the frequent usage of communication and computational resources and to maintain a robust tracking performance of the manipulator, an event-triggered integral sliding mode controller is designed. The controller comprises of a proportional-derivative feedback control loop for the control of the unperturbed /nominal system. The integral sliding mode controller is introduced to guarantee robustness by enforcing the sliding motion from the initial time instant eliminating the reaching phase. Further, to reduce the network usage, a dynamic triggering mechanism is incorporated to reduce the number of control updates. The controller gains are redesigned in an event-based framework to ensure the stability of the system. The closed-loop system with the proposed event-based control law is shown to exhibit Zeno-free behaviour, i.e. the triggering mechanism executes finite sampling instances in finite time. Simulation results are illustrated to prove the theoretical contributions along with the comparative analysis. [ABSTRACT FROM AUTHOR]

Hydrophobic polyurethane (PU) films are widely used for various commercial and industrial applications due to their excellent water repelling and self‐cleaning property. Nevertheless, achieving appreciable hydrophobicity in PU film is quite a challenge. Herein, we report on the development of a novel hydrophobic PU (fluorinated polyurethane [FCO‐PU]) film and comprehensively evaluate its anticorrosive property. The FCO‐PU was prepared by structural modification of castor oil (CO) through attachment of long fluorocarbon chains as pendant groups onto the backbone of CO. A model PU film (CO‐PU) was also prepared from unmodified CO to compare the properties of FCO‐PU film. All intermediate compounds, FCO‐PU and CO‐PU films were characterized by various spectroscopic techniques. Morphological, thermal and mechanical properties of the PU films were analyzed by field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical thermal analysis (DMTA) studies. Successful introduction of long fluorocarbon chains into the FCO‐PU film is reflected by its high hydrophobicity with a water contact angle of 119.1°, compared to the model CO‐PU film with a water contact angle of 84.4°. Anticorrosive properties of the PU films were evaluated by polarization technique and electrochemical impedance spectroscopy under corrosive environment and the obtained results reveal a significant corrosion resistance (corrosion rate: 6.72 × 10−6 mm/year) behavior by the FCO‐PU film. This work represents an effective strategy for the backbone modification of CO to develop novel functional PU materials. [ABSTRACT FROM AUTHOR]