Explore the vast range of titles available.

To address the DC-link voltage control issue in flywheel energy storage systems (FESSs), a DC-link voltage control strategy using a capacitor-energy-based super-twisting sliding mode controller (CE-STSMC), integrated with a disturbance observer, is proposed in this article. First, an exponential term is incorporated into the STSMC algorithm to enhance its convergence rate. Then, the improved STSMC is employed as the voltage-loop controller to mitigate the insufficient anti-disturbance capability of conventional control methods. To improve the system robustness, a nonlinear disturbance observer (NDOB) is developed to estimate the load power. The estimated disturbance is further feedforward-compensated into the improved STSMC controller. Finally, experiments are carried out on a 2.2 kW FESS prototype under DC-link voltage step and sudden load-change conditions, which demonstrates the effectiveness and superiority of the proposed control strategy.

Regardless of the type of application, robot manipulators are frequently subjected to various disturbances, including unmodeled dynamics, uncharacterized friction, unexpected collisions, compliant interaction forces, and varying payloads. Disturbance observers play a crucial role in mitigating and counteracting these perturbations. They serve as force/torque (F/T) estimators in situations where F/T sensors are unavailable for force control applications or in the design of cost-effective robotic systems for interaction tasks. In this paper, we introduce a nonlinear and velocity-independent perturbation observer that represents an enhanced version of the classic Mohammadi’s approach. Here, velocity is estimated through the filtering of robot joint positions. The efficacy of the proposed method is substantiated through a Lyapunov convergence analysis of perturbation/force and velocity estimation errors. Furthermore, the method’s performance is validated through a series of simulation and experimental tests.

In human–robot cooperative industrial manipulators, safety issues are crucial. To control force safely, contact force information is necessary. Since force/torque sensors are expensive and hard to integrate into the robot design, estimation methods are used to estimate external forces. In this paper, the goal is to estimate external forces acting on the end-effector of the robot. The forces at the task space affect the joint space torques. Therefore, by employing an observer to estimate the torques, the task space forces can be obtained. To accomplish this, loadcells are employed to compute the net torques at the joints. The considered observers are extended Kalman filter (EKF) and nonlinear disturbance observer (NDOB). Utilizing the computed torque obtained based on the loadcells measurements and the observer, the estimates of external torques applied on the robot end-effector can be achieved. Moreover, to improve the degree of safety, an algorithm is proposed to distinguish between intentional contact force from an operator and accidental collisions. The proposed algorithms are demonstrated on a robot, namely WallMoBot, which is designed to help the operator to install heavy glass panels. Simulation results and preliminary experimental results are presented to demonstrate the effectiveness of the proposed methods in estimating the joint space torques generated by the external forces applied to the WallMoBot end-effector and to distinguish between the user-input force and accidental collisions.

In this paper, a novel cooperative controller combining Linear Quadratic optimal control based on feedback linearization (LQ-FL) and state error port-Hamiltonian (EPH) with integral term is proposed for permanent magnet synchronous motor. Firstly, the LQ-FL is presented to ensure rapid dynamic performance, and the EPH method makes up for the shortcomings of the system in steady-state performance. The integral term is utilized to eliminate the position tracking steady-state error. Secondly, the Gaussian function is utilized to coordinate the two controllers and make them play their respective superiorities. Then, a nonlinear disturbance observer is used to resolve the total disturbance caused by parameter changes, modeling errors and external disturbance. Finally, the effectiveness and robustness of the proposed controller are verified by simulation and experiments.

Two-wheeled inverted pendulum (TWIP) vehicles are prone to lose their mobility and postural stability owing to their inherently unstable and underactuated dynamic characteristics, specifically when they encounter abruptly changed slopes or ground friction. Overcoming such environmental disturbances is essential to realize an agile TWIP-based mobile platform. In this paper, we suggest a disturbance compensation method that is compatible with unmanned TWIP systems in terms of the nonlinear-model-based disturbance observer, where the underactuated dynamic model is transformed to a fully actuated form by regarding the gravitational moment of the inverted pendulum as a supplementary pseudo-actuator to counteract the pitch-directional disturbances. Consequently, it enables us to intuitively determine the disturbance compensation input of the two wheels and the pitch reference input accommodating to uncertain terrains in real time. Through simulation and experimental results, the effectiveness of the proposed method is validated.

An adaptive current compensation control for a single-sided linear induction motor (SLIM) with nonlinear disturbance observer was developed. First, to maintain t-axis secondary component flux constant with consideration of the specially dynamic eddy-effect (DEE) of the SLIM, a instantaneously tracing compensation of m-axis current component was analyzed. Second, adaptive current compensation based on Taylor-discretization algorithm was proposed. Third, an effective kind of nonlinear disturbance observer (NDOB) was employed to estimate and compensate the undesired load vibrations, then the robustness of the control system could be guaranteed. Experimental verification of the feasibility of the proposed method for an SLIM control system was performed, and it showed that the proposed adaptive compensation scheme with NDOB could significantly promote speed dynamical response and minimize speed ripple under the conditions of external load coupled vibrations and unavoidable feedback control variables measured errors, i.e., current and speed.