In general, permanent magnet synchronous motor (PMSM) drives require four sensors (one position, one DC-link voltage and at least two current sensors) to obtain a good dynamic control performance. If an unpredictable fault occurs in any of these sensors, the performance of the drive deteriorates or even become unstable. Most of the existing works are limited to fault diagnosis (FD) of one or two sensors due to complexity. Therefore, to provide a continuous drive operation regardless of any of the sensor faults, an advanced fault-tolerant control (FTC) scheme that comprises of higher-order sliding mode (HOSM) based observers and controllers is proposed. Two HOSM observers and one Luenberger observer (LO) are designed to generate the respective residuals and provide the detection of all sensor faults. Moreover, HOSM controllers are developed to ensure finite-time convergence of the error trajectories after the fault reconfiguration. The proposed FTC scheme reduces the existing chattering phenomenon with good performance in terms of convergence speed and steady-state error. Evaluation results on a three-phase PMSM are presented to validate the effectiveness of the proposed FTC approach.

Rotor eccentricity and local demagnetization in permanent magnet synchronous motors (PMSMs) increases unbalanced magnetic pull and motor vibration resulting in accelerated aging of motor components. If the asymmetry in the rotor remains undetected, it can increase in severity, and increase the risk of stator-rotor contact, which causes forced outage of the motor and driven process. Detection of PMSM rotor asymmetry currently relies on off-line testing and on-line vibration/current spectrum analysis. However, they are inconvenient or cannot provide reliable detection as they are influenced by other mechanical non-idealities in the motor or load. In this paper, the feasibility of using the signals from analog Hall-effect field sensors for detecting eccentricity and local demagnetization is investigated. It is shown that Hall sensors present in machines for motion control can be used for measuring the variation in the flux inside the motor due to rotor magnetic asymmetry with minimal or no hardware modifications. 3-dimensional (3D) finite element analysis (FEA) and experimental results performed on an interior PMSM (IPMSM) show that the proposed method can provide sensitive and reliable detection of dynamic/mixed eccentricity and local PM demagnetization.

Stabilization of type-2 fuzzy system in the presence of cyber-attacks is investigated in this paper. For a practical application, a class of nonlinear system can be represented by an interval type-2 (IT2) fuzzy system through a set of membership functions. Unlike existing schemes, 1) affine membership functions are considered in the controller design, moreover 2) a robust adaptive event-triggered control (ETC) is proposed to avoid the unwanted triggering events, which makes the proposed scheme more reliable and relaxes the conservativeness of stability analysis. In the numerical simulation, the mass-spring damper (MSD) system and the tracking control system are considered to illustrate the robustness and effectiveness of the proposed approach.

Online monitoring of external torque/force is receiving much attention with the increasing demand in industries, where robot manipulators are required to cooperate with humans, assemble product parts or perform certain tasks that involve the interaction with fragile objects. Estimation of external torque when the robot manipulator interacts with the external environment is investigated in this article. A higher order sliding-mode-based observer is designed to estimate the external torque online against nonlinear friction. Moreover, a Luenberger observer is designed to stabilize the general momenta error dynamics by using sum of squares programming. Lyapunov analysis is considered to demonstrate the stability of an overall system and the convergence of angular position tracking errors. Simulation as well as experimental results using 7-DOF Sawyer robot under various practical scenarios demonstrate the effectiveness of the proposed scheme.

Electric vehicle adoption has accelerated globally, necessitating the development of an efficient charging technology. Static and partially dynamic charging are currently in use, but such types of charging reduce vehicles’ ability to stand charge, contributing to range anxiety. Dynamic charging of electric vehicles will be a promising technology in the near future, allowing an electric vehicle to charge by itself while in motion. However, assessing the security risks before enabling dynamic charging is mandatory, with authentication being a necessary step. Hence, a protocol suite EV-Auth is proposed for communicating entities in a dynamic charging system capable of mutual authentication and session key computation. To achieve practical capabilities, EV-Auth is built using lightweight cryptographic primitives. Additionally, it includes a unique feature known as seamless electric vehicle handover. The security of the proposed protocol suite is assessed both informally and formally using random oracle model and scyther tool. The performance analysis demonstrates that the proposed protocol suite satisfies the communication and computation time requirements.

A difficult problem of high-resistance (HR) connection for permanent magnet synchronous motor (PMSM) drives is investigated in this paper. The presence of HR affects stator currents in such way to deviate from their reference currents in the vector-control structure of the drive, which degrades the performance, reliability, and efficiency of the system. Unlike existing schemes which are limited to detection of HR connection, in this paper, a current-control scheme based on higher-order sliding mode is designed to not only detect, but also provide fault tolerant control (FTC) simultaneously. The HR connection control is obtained by canceling extra dynamics which are generated due to HR connection) in the considered PMSM current-model, which provides accurate tracking of actual current dynamics (d; q) to the reference currents. Moreover, it also estimates HR from the robust sliding mode control terms to monitor the symmetry in the faulted phase. Simulation and experimental results on a 3-phase laboratory test PMSM confirm the validity of the proposed scheme for various cases of stator phase resistances.