Optimal Design for Anti-Skid Control of Electric Vehicles by Fuzzy Approach

In this paper, a new fuzzy approach is applied to optimal design of the anti-skid control for electric vehicles. The anti-skid control is used to maintain the wheel speed when there are uncertainties. The control is able to provide an appropriate torque for wheels when the vehicle is about to skid. The friction coefficient and the moments of inertia of wheels and motor are considered as uncertain parameters. These nonlinear, bounded and time-varying uncertainties are described by fuzzy set theory. The control is deterministic and is not based on IF-THEN fuzzy rules. Then, the optimal design for this fuzzy system and control cost is proposed by fuzzy information. In this way, the uniform boundedness and uniform ultimate boundedness are guaranteed and the average fuzzy performance is minimized. Numerical simulations show that the control can prevent vehicle skidding with the minimum control cost under uncertainties.

Adaptive control and disturbance compensation for gear transmission servo systems with large-range inertia variation

In gear transmission servo systems, backlash effect and inertia variation often generate low precision, oscillations or even affect the stability. Focusing on this issue, an adaptive terminal integral sliding mode control (ATISMC) strategy and a discrete linear extended state observer (DLESO) are proposed in this article. First, different from using traditional dynamic model, a characteristic model is established with online parameter identification to describe inertia variation. Then, a DLESO is proposed to observe and compensate the modeling error caused by parameter identification and backlash effect. An ATISMC is newly designed based on the characteristic model to suppress the uncertainties and stabilize the whole closed-loop system. Both the uniform ultimate boundedness of observation error and the practical finite-time stability of the system is proved. Finally, simulation and experimental results demonstrate that the proposed strategy can adapt to large-range inertia variation and suppress the backlash effect.

Stability, boundedness and existence of unique periodic solutions to a class of fourth order functional differential equations

In this paper a novel class of fourth order functional differential equations is discussed. By reducing the fourth order functional differential equation to system of first order, a suitable complete Lyapunov functional is constructed and employed to obtain sufficient conditions that guarantee existence of a unique periodic solution, asymptotic and uniform asymptotic stability of the zero solutions, uniform boundedness and uniform ultimate boundedness of solutions. The obtained results are new and include many prominent results in literature. Finally, two examples are given to show the feasibility and reliability of the theoretical results.

Nonlinear Ride Height Control of Active Air Suspension System with Output Constraints and Time-Varying Disturbances

This paper addresses the problem of nonlinear height tracking control of an automobile active air suspension with the output state constraints and time-varying disturbances. The proposed control strategy guarantees that the ride height stays within a predefined range, and converges closely to an arbitrarily small neighborhood of the desired height, ensuring uniform ultimate boundedness. The designed nonlinear observer is able to compensate for the time-varying disturbances caused by external random road excitation and perturbations, achieving robust performance. Simulation results obtained from the co-simulation (AMESim-Matlab/Simulink) are given and analyzed, demonstrating the efficiency of the proposed control methodology.

Robust control design for home pension service mobile robots with passive and servo constraints

This paper presents a novel robust control design for a class of home pension service mobile robots (HPSMRs) with non-holonomic passive constraints, based on the Udwadia-Kalaba theory and Udwadia control. The approach has two portions: dynamics modeling and robust control design. The Udwadia-Kalaba theory is employed to deal with the non-holonomic passive constraints. The frame of the Udwadia control is employed to design the robust control to tracking the servo constraints. The designed approach is easy to implement because the analytical solution of the control force can explicitly be obtained even if the non-holonomic passive constraints exists. The uniform boundedness and uniform ultimate boundedness are demonstrated by the theoretical analysis. The effectiveness of the proposed approach is verified through the numerical simulation by a HPSMR.

A Novel Trajectory Tracking Control Strategy for Underactuated Quadrotor UAV with Uncertainties and Disturbances

In this research, a novel position trajectory tracking control architecture has been constructed for an underactuated quadrotor unmanned aerial vehicle (UAV) with uncertainties and disturbances. Primarily, we divide the whole dynamic system into an underactuated position subsystem and a fully-actuated attitude subsystem. For the position subsystem, we have transformed it into a fully-actuated system by constructing a virtual PD controller, and this controller can render the position tracking error asymptotically stable. Besides, based on the position controller designed for quadrotor UAV, the desired attitudes, i.e. roll, pitch and yaw angles, will be derived. Next, as for the attitude subsystem which is sensitive to uncertainties and external disturbances, a novel robust attitude constraint-following controller is proposed for this aircraft, this attitude controller can not only guarantee the uniform boundedness and uniform ultimate boundedness of constraint deviation, but also does not requiring more information of uncertainties and disturbances except their bounds. Eventually, the simulations have demonstrated a sound tracking performance of our proposed control strategy for quadrotor UAV even in the presence of uncertainties and disturbances.

Adaptive Event Triggering Normed Observer Control of Nonlinear Time Delayed Systems

In this paper, event-triggering state-norm estimators are studied for nonlinear delayed systems also normed-observability concept is extended for these systems. Moreover, we established a Lyapunov–Krasovskii functional to obtain normed observability of the delayed nonlinear systems. Furthermore, an adaptive observer is developed such that convergence of the error system is guaranteed. The proposed event-triggering algorithm yields an event-based observer that ensures uniform ultimate boundedness of the tracking error.

A Novel Robust Control of Uncertain Furuta Pendulum Based on a General Lyapunov Function

A novel robust approach for the obedience control of Furuta pendulum with uncertainty is proposed. The uncertainty considered in this paper is (possibly fast) time-varying and bounded, which may exist in any stage of the pendulum subsystem. By the Lagrangian formulation of the nonlinear pendulum system, a robust control, based on a general Lyapunov function, is designed to render the Furuta pendulum a position obedience. As a consequence of the Lyapunov approach, the control design is not restricted to linearize the pendulum system. The system performance under the proposed control is guaranteed as uniform boundedness and uniform ultimate boundedness. The salient features of this new control are demonstrated both analytically and numerically. The experiment is conducted in the Furuta pendulum system to prove the validity and effectiveness of the control design.

Output Feedback Hybrid Force/Motion Control for Robotic Manipulators Interacting with Unknown Rigid Surfaces

SummaryThe problem of hybrid force and motion control over unknown rigid surfaces when only joint position measurements are available is considered. To overcome this problem, an extended state high-gain observer is designed to simultaneously estimate the contact force and joint velocities. These estimated signals are in turn employed to design a local estimator of the unknown surface gradient. This gradient is utilized to decompose the task space into two orthogonal subspaces: one for force tracking and the other one for motion control. A simple position Proportional Integral Derivative (PID) and force Proportional Integral (PI) controllers are proposed to track the desired signals. Finally, a mathematical analysis of the closed-loop dynamics is carried out, guaranteeing uniform ultimate boundedness of the position and force tracking errors and of the surface gradient estimation error. A numerical simulation is employed to validate the approach in an ideal scenario, while experiments are carried out to test the proposed strategy when uncertainties and unmodeled dynamics are present.