Dynamical feedback control of robotic manipulators with joint flexibility

A dynamic feedback controller will be proposed to treat the trajectory tracking control problem of robotic manipulators with flexible joints that use only position measurements on the link and motor sides. Previously published results for the tracking control problem without velocity measurements address only the rigid robot design. Moreover, these results are based on a full-order observer whose dimension is equal to the dimension of the robotic systems. In contrast, our solution can be applied to treat the robotic systems with flexible joints. It does not require any restriction on the joint stiffness. The proposed controller is based on a reduced-order observer which is constructed only to estimate the velocity signal and whose dimension is half of the dimension of flexible-joint robotic systems. We shall show that the resulting closed-loop error system is locally exponentially stable with an arbitrarily large region of attraction. The convergence rate can be arbitrarily pre-assigned and the attraction...

The aim of this paper is to develop a new approach for a solution of the model following control (MFC) problem with a dynamic compensator by using linear matrix inequalities (LMIs). TheH1 model following control problem is derived following LMI formulation. First, the H1 optimal control problem is revisited by referring to Lemmas assuring all admissible controllers minimizing the H1 norm of the transfer function between the exogenous inputs and the outputs. Then, the solvability condition and a design procedure for a two degrees of freedom (2 DOF) dynamic feedback control law is introduced. The existence of a 2 DOF dynamic output feedback controller for the model following control is proven and the stability of the closed-loop system is satisfied by assuring the Hurwitz condition. The benchmark thermal process (PT-326) as the first order process with timedelay is regulated by the presented 2 DOF dynamic output feedback controller. The simulation results illustrate that the presented controller regulates a system with dead-time as a large set of generic industrial systems and the H1 norm of the closed-loop system is assured less than the H1 norm of the desired model system.

New results on dynamic output state feedback stabilization of some class of time-varying nonlinear Caputo derivative systems

This paper is devoted to the finite‐time local piecewise control for parabolic partial differential equations (PDEs) by using dynamic output feedback control strategy, where the controller is designed as an ordinary differential equation (ODE). This makes the closed‐loop system PDE‐ODE coupled, which is employed to accurately describe the dynamics of the PDE system. According to the constructed PDE‐ODE coupled model, a local piecewise dynamic feedback control law is first proposed. Sufficient conditions on finite‐time stabilisation of the parabolic PDE‐ODE coupled system by the suggested feedback controller are then developed in the sense of both complete spatial measurement and incomplete spatial measurement of the observed output of the PDE system, respectively. Finally, the issues regarding the finite‐time stabilisation of the closed‐loop system is converted into the feasibility of matrix inequalities, and some simulation studies are provided to verify the effectiveness of the proposed results.

A 24-GHz power amplifier (PA) for 5G communication is implemented with a 65-nm bulk CMOS process, which adopts analog linearization techniques of dynamic feedback control (DFC) and an adaptive bias control (ADB). The DFC decreases feedbacks and the ADB increases a gate bias of common sources (CSs) with an increase of the input signal power so that the DFC improves gain flatness and peak efficiency, and the ADB increases high power gain, saturation power, and peak efficiency. These analog linearization techniques lower the IMD3 by improving the AM-AM and AM-phase modulation (PM) of the PA. The proposed PA shows a saturation power of 18.7 dBm, a 1-stage PA gain of 15.3 dB, and a peak PAE of 37.2% with the 24.29-GHz continuous wave signal measurement. It also shows a linear power of 12.9 dBm and a linear PAE of 14.8% with a two-tone signal measurement that has a center frequency of 24.49 GHz and a bandwidth of 80 MHz.

A new approach is proposed for the design of a pulse width modulated (PWM) feedback control scheme regulating a full bridge buck converter (FBBC) in an output signal stabilization task. The approach is based on the specification of a dynamical feedback control law which accomplishes asymptotic stabilization to a preselected constant operating point, for the average PWM converter model. The approach emphasizes the use of the Fliess generalized observability canonical form (GOCF) of the average converter model and partial inversion techniques. >

Dynamic feedback control of day-to-day traffic disequilibrium process

This work carefully revisits the topic of dynamic feedback H ∞ control problem for discrete singular systems (DSSs) with time–varying delays. A new state decomposed Lyapunov-Krasovskii functional is presented by a discrete state decomposition method. For the unforced nominal DSSs, delay–dependent sufficient conditions with an H ∞ performance index are derived. Based on these conditions, a closed–loop system being regular and causal is developed via a dynamic feedback controller. As a new discrete state decomposition–reorganization method is proposed, the required admissibility conditions are attained. Through the accurate calculation of each decomposition component of the dynamic feedback controller, the desired dynamic feedback controller settings are determined. The numerical findings demonstrate the superiority of our method over earlier approachers, and the results are less conservative.

A new model-based dynamic resistive wall mode (RWM) identification and feedback control algorithm has been developed. While the overall RWM structure can be detected by a model-based matched filter in a similar manner to a conventional sensor-based scheme, it is significantly influenced by edge-localized-modes (ELMs). A recent study suggested that such ELM noise might cause the RWM control system to respond in an undesirable way. Thus, an advanced algorithm to discriminate ELMs from RWM has been incorporated into this model-based control scheme, dynamic Kalman filter. Specifically, the DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] resistive vessel wall was modeled in two ways: picture frame model or eigenmode treatment. Based on the picture frame model, the first real-time, closed-loop test results of the Kalman filter algorithms during DIII-D experimental operation are presented. The Kalman filtering scheme was experimentally confirmed to be effective in discriminating ELMs from RWM. As a result, the actuator coils (I-coils) were rarely excited during ELMs, while retaining the sensitivity to RWM. However, finding an optimized set of operating parameters for the control algorithm requires further analysis and design. Meanwhile, a more advanced Kalman filter based on a more accurate eigenmode model has been developed. According to this eigenmode approach, significant improvement in terms of control performance has been predicted, while maintaining good ELM discrimination.

In this artilce we propose an output feedback control scheme for the robust stabilization, through sliding mode creation, of nonlinear discrete-time systems described in Fliess' Generalized Observability Canonical Form. The results arc applied to the regulation of a discretized model of a nonlinear DC motor.

Presents a nonlinear dynamic model for a four rotors helicopter in a form suited for control design. We show that the input-output decoupling problem is not solvable for this model by means of a static state feedback control law. Then, a dynamic feedback controller is developed which renders the closed-loop system linear, controllable and noninteractive after a change of coordinates in the state-space. Finally, the stability and the robustness of the proposed control law in the presence of wind, turbulences and parametric uncertainties is analyzed through a simulated case study.

Mechanical systems are often only equipped with position measurement encoders and obtain the velocity signal by differentiation.However, differentiation largely amplifies noise.In this paper we look at dynamic feedback control of Euler-Lagrange mechanical systems.Dynamic feedback is often used to avoid velocity measurements in the control feedback.In the Euler-Lagrange literature it is shown that the dynamic extension realizes an approximate differentiator, justifying its application.We show in this paper that the dynamic extension used in the Euler-Lagrange literature actually realizes a leadcompensator, proving that a lead-compensator can also globally asymptotically stabilize a nonlinear mechanical systems.Furthermore, based on the lead-compensator structure it is then possible to offer a frequency approach to tune the controller gains.

The dynamic linear state feedback control problem is addressed for a class of nonlinear systems subject to time-delay. First, using the dynamic change of coordinates, the problem of global state feedback stabilization is solved for a class of time-delay systems under a type of nonhomogeneous growth conditions. With the aid of an appropriate Lyapunov-Krasovskii functional and the adaptive strategy used in coordinates, the closed-loop system can be globally asymptotically stabilized by the dynamic linear state feedback controller. The growth condition in perturbations are more general than that in the existing results. The correctness of the theoretical results are illustrated with an academic simulation example.

Cooperative output regulation problem for linear time-delay multi-agent systems under switching network

Acceleration feedback (AF) is applied to restrain the trajectory disturbances in the motion control of parallel manipulators to increase the trajectory tracking accuracy. A dynamic model is formulated in the task space, and the optimal exciting trajectory is calculated for dynamic identification. The acceleration signals can be estimated without acceleration sensors on the basis of the closed-loop constraint equations. Furthermore, the dynamic acceleration feedback (DAF) controller is developed by introducing the AF into the robust dynamics compensation and trajectory tracking, and the stability of the closed-loop system is proven. The DAF controller is implemented on a planar parallel manipulator platform, and the corresponding experimental results are compared with an existing, robust controller.