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The Cerebellar Model Articulation Controller (CMAC) is a type of neural network particularly suited to real-time control applications due to fast adaptation and the ability to handle many inputs. However, the CMAC is well-known to exhibit weight (adaptive-parameter) drift when used in adaptive control, and overlearning when applied in static learning situations. A weight smoothing algorithm originally...
This study is aimed to find low order, stable and proper controllers for the linearized models of two well known underactuated robots i.e. Acrobot and Pendubot around their upright equilibrium points in order to maximize the robustness of the feedback loop to uncertainties. The proposed method makes use of the robust stabilization of finite dimensional plants by Nevanlinna-Pick interpolation problem...
To enhance the control precision of permanent magnet synchronous motor (PMSM) under parameter variations and load torque disturbances, a minimal reduced-order load torque observer (MRLTO) based discrete-time sliding mode control (DSMC) scheme is presented. First, a DSMC controller is presented on the basis of the second-order discrete-time PMSM dynamics model to enhance the speed tracking response...
Conventional ring amplifier suffers from stability problem, the problem is exacerbated when process, voltage and temperature (PVT) variations are taken into considerations. Prior works are mainly focused on stability problem, the influence of PVT on transient response were barely discussed. In this paper the influence of process variations on stability and transient response is analyzed, a process-...
A model-based control design method is developed for nonlinear reactive sputter processes that can be modelled by a nonlinear ordinary differential equation with linear input and stable and unstable equilibrium states. The controller shall robustly stabilize the unstable working points. Lyapunov's direct method is used to formulate stability conditions that respect possible uncertainties in the process...
In order to improve the speed-regulation performance of the permanent-magnet synchronous motor (PMSM) system under uncertainties and disturbances, an equivalent disturbance observer (EDO) based discrete-time integral sliding mode control (DISMC) scheme is proposed. To avoid the high-frequency noise caused by the differential terms of conventional sliding mode control (SMC), a discrete-time integral...
This paper presents a procedural level generation algorithm for physics-based puzzle games similar to Angry Birds. The proposed algorithm is capable of creating varied, stable and solvable levels consisting of multiple self-contained structures placed throughout a 2D area. The work presented in this paper builds and improves upon a previous level generation algorithm, enhancing it in several ways...
A fault tolerant control approach is proposed in this paper for quadrotor Unmanned Aerial Vehicle (UAV) subject to time varying disturbances and actuator faults. The approach is based on a Super-Twisting (STW) control algorithm and a Higher Order Sliding Mode Observer (HOSMO). The HOSMO generates the exact estimates of the unmeasured states and time varying disturbances without any filtration that...
This paper proposes a systematic approach to derive analytical and explicit certificates for transient stability analysis of inverter-based microgrids. We first derive a line-based model of microgrids with general mesh structure. Then by employing Lyapunov stability theory with a quadratic Lyapunov function, the region of attraction of any post-fault stable equilibrium point (EP) is estimated by a...
In this paper, we propose a robust multi-speaker voice activity detection approach for wireless acoustic sensor networks (WASN). Each node of the WASN receives a mixture of sound sources. We propose a non-negative feature extraction using stability selection that exploits the sparsity of the speech energy signals. The strongest right singular vectors serve as source-specific features for the subsequent...
An active disturbance rejection controller (ADRC) is designed and originally implemented on a real torsional plant. The torsional plant resembles the dynamics of a rotational system. Due to mass imbalance, centrifugal imbalance, and the non-coincidence between the principal and geometric axes of a rotating disc, the system parameters of this torsional plant are varying constantly. In addition, an...
This paper investigates the stabilization problem for a class of nonlinear time-delay Hamiltonian systems with actuator saturation and input delay, and proposes delay-independent and delay-dependent results on the systems by applying Lyapunov-Krasovskii (L-K) functional method. Different from existing methods, we construct a suitable L-K functional to overcome the input delay problems, obtain some...
Constant-Power Load (CPL) introduces destabilizing effect to dc-dc converters, which may lead to voltage oscillation or collapse. To mitigate the destabilizing problem brought by CPL, a nonlinear boundary controller is proposed in this paper, which has a nonlinear switching line. The converters' dynamics on the state space plane is analyzed through phase portrait. The proposed controller is verified...
In this paper, robust consensus for fractional nonlinear multi-agent systems with external disturbances is investigated over a directed fixed interaction graph. Mittag-Leffler stability and the general algebraic connectivity are introduced to establish various sufficient conditions for reaching consensus. For fractional multi-agent systems with nonlinear dynamics, when the condition on the general...
Compared with the traditional front-wheel-steering (FWS) vehicles, four-wheel-independent-steering (4WIS) vehicles have better handling stability and path-tracking performance. In this paper, a novel 4WIS electric vehicle (EV) is proposed and it is viewed as a controlled object for path tracking. The nonlinear dynamical model of the 4WIS EV is built based on the nonlinear Dugoff tire model. For controller...
This paper studies the attitude control problem for the longitudinal motion of a hypersonic aircraft model containing 28 inertial and aerodynamic uncertain parameters given by NASA Langley Research Center. To handle the nonlinear dynamics and uncertain parameters, ADRC for the unobservable and unmatched disturbance is designed. Besides, the properties of the closed-loop system is discussed in two...
Small gain theorem is used to interpret stability and robustness of linear active disturbance rejection control(LADRC). For the case linear unmodeled dynamic and additive external disturbance, LADRC system is decomposed into two interconnected subsystems. The first subsystem includes all parametric uncertainty of the plant, while the second has a gain which can be adjusted by choosing the parameters...
This paper investigates the problem of robust output feedback stabilization of uncertain Hamiltonian systems with saturating actuator and input delay. The uncertainties are assumed to be time invariant and belong to convex bounded polytopic domain. By employing Lyapunov-Krasovskii functional method and Wirtinger's inequality, some sufficient conditions are derived for stabilization of nonlinear Hamiltonian...
The lateral guidance objective is to derive the cross track error towards zero with graceful and stable maneuvers and then to keep it as minimum as possible. A nonlinear sliding surface based lateral guidance scheme is proposed here for Unmanned Aerial Vehicles (UAVs) application with limited actuation. Following the inner (control) and outer (guidance) loop structure, the proposed guidance scheme...
A methodology of designing adaptive sliding mode controllers for a class of nonlinear systems with matched and mismatched perturbations is proposed in this paper. Firstly, A specific designed sliding surface function is presented, and the controller with adaptive mechanisms embedded is also designed in accordance with the designated sliding surface function. Secondly, the coefficients of designated...
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