A new approach for the robust fixed-order H_∞ controller design by convex optimization is proposed. In this paper, the robust performance condition is represented by a set of convex constraints with respect to the pa...
详细信息
ISBN:
(纸本)9784907764388
A new approach for the robust fixed-order H_∞ controller design by convex optimization is proposed. In this paper, the robust performance condition is represented by a set of convex constraints with respect to the parameters of a linearly parameterized controller on the Nyquist diagram for prespecified frequency points. This method can directly handle frequency-domain uncertainty without any modeling. Frequency-domain uncertainty can be minimized by selecting the appropriate nominal plant model for the corresponding frequency points in the proposed method. The proposed method is compared with the standard H_∞ control problem by experiments.
This paper deals with the regulation of the three-level neutral-point-clamped (NPC) converter operating as synchronous rectifier connected to the ac mains. The regulation of the rectifier, whose primary application is...
详细信息
ISBN:
(纸本)9781479940318
This paper deals with the regulation of the three-level neutral-point-clamped (NPC) converter operating as synchronous rectifier connected to the ac mains. The regulation of the rectifier, whose primary application is to derive dc power from the utility grid, is based on a dynamic model of the system. This model includes the dynamics of the instantaneous powers as well as those of the total dc-link voltage and of the voltage difference of the dc-link capacitors, which are the state variables of the system and should be controlled. In this way, a direct power control (DPC) strategy and a proportional-integral (PI) cascade controller are considered for the regulation, respectively, of the instantaneous powers and of the total dc-link voltage. Regarding the balancing of the capacitor voltages, a novel and simple controller is proposed. This model-based controller can be considered as a non-conventional form of a PI controller. Simulations are performed in PSCAD environment to evaluate the performance of the closed-loop rectifier system under the proposed controllers.
This paper considers the model-based control of a pneumatic system, where a tank is connected to a valve via a long tube. Due to the significant distance between the control input and the pressure in the tank to be co...
详细信息
ISBN:
(纸本)9781538670804;9788993215168
This paper considers the model-based control of a pneumatic system, where a tank is connected to a valve via a long tube. Due to the significant distance between the control input and the pressure in the tank to be controlled, a distributed-parameter model is used for the tube, involving quasilinear hyperbolic partial differential equations. In contrast, the tank is modelled by ordinary differential equations. Experimental data verifies the validity of the corresponding quasilinear system model. based on a less accurate, linear PDE-ODE system model, derived there upon, both, a back-stepping controller and a backstepping observer are designed. The resulting output feedback controller is augmented by a flatness-based feedforward controller. Experimental results for tube lengths of approximately five and twenty meters show that this controller allows to track fast pressure changes in the tank almost perfectly.
Hovering capabilities of unmanned helicopters can be seriously affected by wind effects. One possible solution for improving hovering performance under such circumstances is the use of a tethered setup that takes adva...
详细信息
ISBN:
(纸本)9781479908158
Hovering capabilities of unmanned helicopters can be seriously affected by wind effects. One possible solution for improving hovering performance under such circumstances is the use of a tethered setup that takes advantage of the tension exerted on the cable that links the helicopter to the ground. This paper presents a more elaborated strategy for helicopter control in this augmented setup that extends previous work on the subject by the authors. Particularly, a combination of classical PID control laws together with model inversion blocks constitutes the base of the new controller. Additionally, feed-forward action for counteracting rotational couplings is also accounted for. The resulting nonlinear control structure considers the complex and nonlinear nature of the tethered system in a better way. Several demonstrating simulations under artificially generated wind influences are presented to endorse the validity of the new proposed controller.
Solenoid current regulation is well-known and standard in any proportional electro-hydraulic *** goal is to provide a wide-band transfer function from the reference to the measured current,thus making the solenoid a f...
详细信息
Solenoid current regulation is well-known and standard in any proportional electro-hydraulic *** goal is to provide a wide-band transfer function from the reference to the measured current,thus making the solenoid a fast and ideal force actuator within the limits of the power *** latter is a Pulse Width Modulation(PWM) amplifier fixing the voltage bound and the Nyquist frequency of the *** analogue regulators include three main terms:a feedforward channel,a proportional feedback channel and the electromotive force *** latter may be accomplished by an integrative *** the problem is faced through a model-based design(Embedded modelcontrol),on the basis of a wide-band embedded model of the solenoids which includes the effect of eddy *** this end the model must be *** embedded model includes a disturbance dynamics capable of estimating and correcting the electromotive contribution together with parametric uncertainty,variability and state *** embedded model fed by the measured current and the supplied voltage becomes a state predictor of the controllable and disturbance *** control law combines reference generator,state feedback and disturbance rejection to dispatch the PWM with the appropriate duty ***,identification and control design are outlined together with regulator performance.
Precise models of robot inverse dynamics allow the design of significantly more accurate, energy-efficient and compliant robot control. However, in some cases the accuracy of rigid-body models does not suffice for sou...
详细信息
Precise models of robot inverse dynamics allow the design of significantly more accurate, energy-efficient and compliant robot control. However, in some cases the accuracy of rigid-body models does not suffice for sound control performance due to unmodeled nonlinearities arising from hydraulic cable dynamics, complex friction or actuator dynamics. In such cases, estimating the inverse dynamics model from measured data poses an interesting alternative. Nonparametric regression methods, such as Gaussian process regression (GPR) or locally weighted projection regression (LWPR), are not as restrictive as parametric models and, thus, offer a more flexible framework for approximating unknown nonlinearities. In this paper, we propose a local approximation to the standard GPR, called local GPR (LGP), for real-time model online learning by combining the strengths of both regression methods, i.e., the high accuracy of GPR and the fast speed of LWPR. The approach is shown to have competitive learning performance for high-dimensional data while being sufficiently fast for real-time learning. The effectiveness of LGP is exhibited by a comparison with the state-of-the-art regression techniques, such as GPR, LWPR and.-support vector regression. The applicability of the proposed LGP method is demonstrated by real-time online learning of the inverse dynamics model for robot model-based control on a Barrett WAM robot arm. (C) Koninklijke Brill NV, Leiden and The Robotics Society of Japan, 2009
Our data rule out a broad class of behavioral models in which behavioral change is guided by differential reinforcement. To demonstrate this, we showed that the number of reinforcers missed before the subject shifted ...
详细信息
暂无评论