Xinyu Shu

Active vibration control for harmonic disturbances with time-varying frequencies through LPV gain scheduling

A design method for a discrete-time H∞-optimal gain-scheduling controller that rejects harmonic disturbances with time-varying, known frequencies is presented. This is motivated by active vibration control and the controller is experimentally validated on an active vibration control test bench. The harmonic disturbances are modeled as outputs of a linear parameter varying system (LPV) where the frequencies are the varying parameters. The design method and the controller synthesis are discussed and experimental results for constant and time-varying frequencies are shown. The design method leads to a controller that stabilizes the closed-loop system even for arbitrarily fast changes in the disturbance frequencies. In the real-time experiment, the controller suppresses a disturbance consisting of six independent harmonics with frequencies that vary over ranges of 20 Hz.

LPV Gain-Scheduled Observer-Based State Feedback for Active Control of Harmonic Disturbances with Time-Varying Frequencies

The design of controllers for the rejection of multisine disturbances with time-varying frequencies is considered. The frequencies are assumed to be known. Such a control problem frequently arises in active noise and vibration control (ANC/AVC) applications where the disturbances are caused by imbalances due to rotating or oscillating masses or periodically fluctuating excitations, for example the torque of a combustion engine, and the rotational speed is measured. Application examples are automobiles and aircrafts.

LPV Gain-Scheduled Output Feedback for Active Control of Harmonic Disturbances with Time-Varying Frequencies

In this chapter, the same control problem as in the previous chapter is considered, which is the rejection of harmonic disturbances with time-varying frequencies for linear time-invariant (LTI) plants. In the previous chapter, gain-scheduled observer-based state-feedback controllers for this control problem were presented. In the present chapter, two methods for the design of general gain-scheduled output-feedback controllers are presented. As in the previous chapter, the control design is based on a description of the system in linear parameter-varying (LPV) form. One of the design methods presented is based on the polytopic linear parameter-varying (pLPV) system description (which has also been used in the previous chapter) and the other method is based on the description of an LPV system in linear fractional transformation (LPV-LFT) form. The basic idea is to use the well-established norm-optimal control framework based on the generalized plant setup shown in Fig. 1 with the generalized plantG and controllerK.

Design of structured discrete-time LPV gain-scheduling controllers through state augmentation and partial state feedback

A method to design discrete-time linear parameter-varying (LPV) gain-scheduling controllers with prescribed order through state augmentation and partial state feedback is presented. Prescribed polytopic linear parameter-varying (pLPV) dynamics are added to the plant for the control design using state augmentation. Static state-feedback gains are calculated via convex linear matrix inequalities (LMIs) and interpolated with pLPV techniques. The resulting controller consists of the prescribed pLPV dynamics and the time-varying gains. The order of the controller is fixed and reduced compared to existing approaches. As an example, a sixth-order controller for suppression of a harmonic disturbance with three time-varying frequencies is designed and implemented in real time in an active vibration control (AVC) test bench.

An LPV discrete-time controller for the rejection of harmonic time-varying disturbances in a lightweight flexible structure

In this work, control system design and implementation for active vibration control (AVC) of flexible structures with piezoelectric actuators is studied. The goal is to reduce the effect of harmonic disturbances with known time-varying frequencies acting on a system. As a test bed, a thin flexible aluminum cantilevered beam with two symmetrically bonded piezoelectric actuators is used. The harmonic excitation is generated by two DC motors each of them with an unbalanced mass. A discrete-time model is obtained through black-box system identification methods. The control algorithm design is based on a plant description with a disturbance model as a linear parameter varying (LPV) system in linear fractional transformation (LFT) form. This results in a gain-scheduled controller where the harmonic disturbance frequencies are the scheduling variables. The experimental real-time results show the effectiveness of the controller and its capability to suppress time-varying harmonic disturbances, whose frequencies are measured directly from the DC motors. The design method leads to a controller that stabilizes the closed-loop system even for arbitrarily fast changes in the disturbance frequencies. In the real-time experiment, the controller suppresses a disturbance consisting of two independent harmonics with frequencies that vary over a range of 15 Hz.

TWO-PARAMETER PLPV MODELING OF NONSTATIONARY HARMONICALLY RELATED MULTISINE DISTURBANCES FOR REDUCED-ORDER GAIN-SCHEDULING CONTROL

A two-parameter polytopic linear parameter-varying (pLPV) modeling approach for nonstationary harmonically related multisine disturbances is presented, and a pLPV controller based on this model is introduced. An exact model for disturbances with known nonstationary frequencies is used. The number of the scheduling parameters is reduced to two using the disturbance model presented. The controller only consists of the disturbance model. Therefore, the controller order is the minimal order required for asymptotic disturbance rejection. Experimental results validate the effectiveness of the controller using an active vibration control (AVC) test bed.

A discrete-time MIMO LPV controller for the rejection of nonstationary harmonically related multisine disturbances

This paper is an extension of the previous work realized by the authors. Here a discrete-time multiple input multiple output (MIMO) linear parameter-varying (LPV) controller is designed, a polynomial approximation for disturbances with harmonically related frequencies to reduce the number of gain-scheduling parameters is used and the controller is validated experimentally for the rejection of the engine-induced vibrations in a vehicle. Excellent results are achieved in a Golf VI Variant for the rejection of disturbances with nine time-varying frequency components with a controller interpolated from three vertices using only two gain-scheduling parameters. The stability of the controller is guaranteed for changes in the gain-scheduling parameters since LPV control design techniques are used.

LPV gain-scheduling control with time-varying sampling time for rejecting nonstationary harmonically related multisine disturbances

A method to design linear parameter-varying (LPV) controllers with time-varying sampling time to reject nonstationary harmonically related multisine disturbances is presented in this work. Unlike common approaches, the design considers the disturbance as a time-invariant model while the plant is an LPV system with sampling time as the scheduling parameter in linear fractional transformation (LFT) form. Only one scheduling parameter is used for this approach, independently of the number of frequencies. Good disturbance rejection is achieved by simulation.

Discrete-time Switching MIMO LPV Gain-scheduling Control for the Reduction of Engine-induced Vibrations in Vehicles

Abstract The work of this paper is an extension of the previous work realized by the authors. The main objective of this work is the reduction of the engine-induced vibrations in vehicles using a switching strategy to augment the controller range of actuation. Two inertia mass actuators and two accelerometers are attached to the engine mounts. Multiple input multiple output (MIMO) linear parameter-varying (LPV) controllers are designed for the reduction of the engine-induced vibrations and validated experimentally with test drives in a Golf VI Variant. The stability of the controllers is guaranteed since LPV gain-scheduling techniques are used. The MIMO LPV controllers achieved excellent results for the reduction of nine frequency components of the engine-induced vibration using only two gain-scheduling parameters for a range of 750 rpm.

A wireless crane to vessel locating system for sea swell compensation

Sea swell causes significant risk in transferring people and material to offshore constructions and oftentimes hamper the accessibility completely. The weather window where a construction is accessible can be enlarged notably if a crane is equipped with a sea swell compensation system. For a crane to vessel swell compensation system it is required to measure the 3D position of the crane load handling device relative to the deck of ship precisely, reliably and in real-time. In this paper a novel wireless crane to vessel locating system is introduced. Several secondary radar units that are mounted on the ship deck are measuring the distance to a responder unit attached to the crane boom. The 3D localization is based on a fusion of secondary radar distance measurements and the data from an inertial sensor platform. The fusion is done by a quaternion based extended Kalman filter which implements both multilateration and strapdown inertial navigation techniques. Real measurement data acquired with the inertial platform on a ship and radar data measured with the realized local positioning radar onshore are fed in a PC based simulation of the complete system. The real data simulations prove that the developed real time locating system provides the required position information precisely and reliably. By this it is shown that the novel wireless locating system is well suited for sea swell compensation equipment.