Vibration Suppression Control Research Articles

Aerodynamic Parameter Prediction via Artificial Hair Sensors with Signal Power in Turbulent Flow

Spatiotemporal surface flow information obtained from distributed arrays of bioinspired hair sensors are capable of predicting the real-time aerodynamic parameters (i.e., lift, moment, angle of attack, and freestream velocity) on a representative wing section. When combined with an appropriate model of the system, these sensors can provide vital information about gust disturbance as well as state estimation of an aeroelastic system, both of which are essential for effective vibration suppression control system design. In a typical aeroelastic system undergoing a periodic change in bending and torsion motion, a number of hair sensors can be in turbulent flow regions at any instant, resulting in random vibration response. This paper specifically investigates the effect in aerodynamic parameter prediction when sensor measurements from both laminar and turbulent flow regions are combined. It also investigates the idea of incorporating the sensor signal power along with sensor information to increase the prediction accuracy in such a scenario. The experimental results show that incorporating sensor response from both laminar and turbulent flow regions improves the prediction for the whole operating region containing both positive and negative angle of attack. Moreover, incorporating the signal power further improves the prediction accuracy and precision.

Development of Bearingless Induction Motors and Key Technologies

In order to effectively suppress rotor periodic synchronous vibration caused by the rotor mass eccentricity and sensor detection error of bearingless induction motor (BIM), a rotor vibration suppression control strategy with improved repetitive control is proposed based on the analysis of the problems existing in traditional repetitive control. On the basis of the vector control model of the BIM system, a simplified suspension control model is derived. The fractional delay filter is used to optimize the repetitive control internal model. Based on the stability conditions of the control system, the design method of repetitive control compensation function in high, middle and low frequency region is given in detail, and the simulation and experimental system of BIM is built. The results show that the vibration suppression control strategy with the improved repetitive control can effectively suppress the vibration of the rotor in steady state and improve the suspension accuracy of the BIM.

An Operator-based Nonlinear Vibration Control System Using a Flexible Arm with Shape Memory Alloy

In the past, arms used in the fields of industry and robotics have been designed not to vibrate by increasing their mass and stiffness. The weight of arms has tended to be reduced to improve speed of operation, and decrease the cost of their production. Since the weight saving makes the arms lose their stiffness and therefore vibrate more easily, the vibration suppression control is needed for realizing the above purpose. Incidentally, the use of various smart materials in actuators has grown. In particular, a shape memory alloy (SMA) is applied widely and has several advantages: light weight, large displacement by temperature change, and large force to mass ratio. However, the SMA actuators possess hysteresis nonlinearity between their own temperature and displacement obtained by the temperature. The hysteretic behavior of the SMA actuators affects their control performance. In previous research, an operator-based control system including a hysteresis compensator has been proposed. The vibration of a flexible arm is dealt with as the controlled object; one end of the arm is clamped and the other end is free. The effectiveness of the hysteresis compensator has been confirmed by simulations and experiments. Nevertheless, the feedback signal of the previous designed system has increased exponentially. It is difficult to use the system in the long-term because of the phenomenon. Additionally, the SMA actuator generates and radiates heat because electric current passing through the SMA actuator provides heat, and strain on the SMA actuator is generated. With long-time use of the SMA actuator, the environmental temperature around the SMA actuator varies through radiation of the heat. There exists a risk that the ambient temperature change dealt with as disturbance affects the temperature and strain of the SMA actuator. In this research, a design method of the operator-based control system is proposed considering the long-term use of the system. In the method, the hysteresis characteristics of the SMA actuator and the temperature change around the actuator are considered. The effectiveness of the proposed method is verified by simulations and experiments.

Designing multi-input multi-output modal-space negative acceleration feedback control for vibration suppression of structures using active mass dampers

The objective of this study was to design multi-input and multi-output feedback control for vibration suppression of structures using multiple active mass dampers driven by linear servo motors. The linear servo motor was used to enhance control effectiveness and decrease noise. The multi-input and multi-output modal-space negative acceleration feedback control was developed to fully utilize multiple accelerometers and multiple active mass dampers. Control spillover problem due to mistuning of the negative acceleration feedback control was also investigated in detail. To determine the efficacy of the proposed multi-input and multi-output modal-space negative acceleration feedback control, a two-story building-like structure was built and tested. A dynamic model was derived by using energy approach and beam modeling. The proposed multi-input multi-output modal-space negative acceleration feedback controller was validated both theoretically and experimentally for the test structure. Both numerical and experimental results showed that the proposed controller could effectively suppress vibrations.

Passenger body vibration control in active quarter car model using ANFIS based super twisting sliding mode controller

This paper presents passenger body vibration control using an Adaptive Neuro Fuzzy Inference System (ANFIS) based super twisting sliding mode controller (ASTSMC) in active quarter car system. The proposed quarter car model is having three degrees of freedom composed of passenger body, sprung mass and unsprung mass. The random road profile is generated using ISO 8608 standard. The ride comfort of passenger body is calculated as per ISO 2631-1 standard. The simulation response is studied in time and frequency domain for passenger body acceleration and displacement in quarter car model. The response generated by ASTSMC controller for passenger body vibration suppression is compared with super twisting sliding mode controller and passive suspension system. The graphical and mathematical results proved the superiority of proposed ASTSMC controller in providing best ride comfort and safety to travelling passenger.

Vibration suppression control of free-floating space robots with flexible appendages for autonomous target capturing

Some flexible appendages, such as solar panels, communication antenna and other large structures are mounted on the base of the space robot. The structure flexibilities will cause vibration during the operation of manipulators. Due to complicated dynamic coupling among manipulators, the rigid base and flexible appendages, it is very challenging to control the end-effector to track inertial trajectories, especially when the target states are constantly changing. This paper proposes a vibration suppression method for autonomous target capturing during the preimpact phase without controlling the base. Firstly, we derive the rigid-flexible coupling dynamics of a space robot system with flexible appendages. Then, the relationship among joint rates, elastic motion and the end-effector velocities is established by using the linear momentum and angular momentum conservation equations. Secondly, a closed-loop control system is designed based on the dynamic coupling model. And the control system is composed of target motion prediction, autonomous trajectory planning, energy-based joint controllers and so on. Thirdly, the energy-based joint control is detailed, which is proved to be stable by Lyapunov direct method. Finally, simulations of a planar space robot with two flexible appendages and a 3D space robot with single flexible appendage are provided to verify the effectiveness of the presented approach. The effectiveness of energy-based joint control for vibration suppression is verified by a single-degree-of-freedom space robot experimental system. The simulation and experimental results show that the space manipulator can successfully capture the moving target while suppressing the structure vibration.

Filter Design of Adjusting Common Phase for Vibration Suppression Control of Multi-Degree-of Freedom System

In flexible structures such as a stacker crane, vibration is generated by the high acceleration of the traveling axis in the load transportation slider. Vibration suppression is necessary for productivity improvement. We utilized the acceleration feedback control for vibration suppression. The flexible structure has several natural vibration modes of varying phase, and vibration suppression is difficult by the simple feedback control. The second mode is excited by the simple feedback control for the vibration suppression of the first mode when the phase between the first mode and the second mode are different, e.g., a flexible structure. This paper proposes a filter design by adjusting the common phase for the feedback control. The filter using the operational amplifier reverses the phase of the second mode and such that it is the same as the first mode. The effect of vibration suppression is verified by the experiment.

Design and Vibration Suppression Control of a Modular Elastic Joint.

In this paper, a novel mechatronic design philosophy is introduced to develop a compact modular rotary elastic joint for a humanoid manipulator. The designed elastic joint is mainly composed of a brushless direct current (DC) motor, harmonic reducer, customized torsional spring, and fail-safe brake. The customized spring considerably reduces the volume of the elastic joint and facilitates the construction of a humanoid manipulator which employs this joint. The large central hole along the joint axis brings convenience for cabling and the fail-safe brake can guarantee safety when the power is off. In order to reduce the computational burden on the central controller and simplify system maintenance, an expandable electrical system, which has a double-layer control structure, is introduced. Furthermore, a robust position controller for the elastic joint is proposed and interpreted in detail. Vibration of the elastic joint is suppressed by means of resonance ratio control (RRC). In this method, the ratio between the resonant and anti-resonant frequency can be arbitrarily designated according to the feedback of the nominal spring torsion. Instead of using an expensive torque sensor, the spring torque can be obtained by calculating the product of spring stiffness and deformation, due to the high linearity of the customized spring. In addition, to improve the system robustness, a motor-side disturbance observer (DOb) and an arm-side DOb are employed to estimate and compensate for external disturbances and system uncertainties, such as model variation, friction, and unknown external load. Validity of the DOb-based RRC is demonstrated in the simulation results. Experimental results show the performance of the modular elastic joint and the viability of the proposed controller further.

A novel fractional-order model and controller for vibration suppression in flexible smart beam

Vibration suppression represents an important research topic due to the occurrence of this phenomenon in multiple domains of life. In airplane wings, vibration can cause discomfort and can even lead to system failure. One of the most frequently used means of studying vibrations in airplane wings is through the use of dedicated flexible beams, equipped with sensing and actuating mechanisms powered by suitable control algorithms. In order to optimally reject these vibrations by means of closed-loop control strategies, the availability of a model is required. So far, the modeling of these smart flexible beams has been limited to deliver integer order transfer functions models. This paper, however, describes the mathematical framework used to derive a fractional-order impedance lumped model for capturing frequency response of a flexible beam system exposed to a multisine excitation. The theoretical foundation stems from fractional calculus applied in combination with transmission line theory and wave equations. The simplified model reduces to a minimal number of parameters when converging to a limit value. It is shown that the fractional-order model outperforms an integer order model of the smart beam. Based on this novel fractional-order model, a fractional-order $$\hbox {PD}^\mu $$ controller is then tuned. The controller design is based on shaping the frequency response of the closed-loop system such that the resonant peak is reduced in comparison to the uncompensated smart beam system and disturbances are rejected. Experimental results, considering a custom-built smart beam system, are provided, considering both passive and active control situations, showing that a significant improvement in the closed-loop behavior is obtained using the proposed controller. Comparisons with a fractional-order $$\hbox {PD}^\mu $$ controller, tuned according to classical open-loop frequency domain design specifications, are provided. The experimental results show that the proposed tuning technique leads to similar results as the classical approach. Thus, the proposed method is a viable alternative, being based on closed-loop specifications, which is more intuitive for practitioners.

Sampled-data mixed and passive control for attitude stabilization and vibration suppression of flexible spacecrafts with input delay

This paper deals with the problem of mixed and passive control for flexible spacecrafts subject to nonuniform sampling and time-varying delay in the input channel. An impulsive observer-based controller is introduced and the resulting closed-loop system is a hybrid system consisting of a continuous time-delay subsystem and an impulsive differential subsystem. As a first result, we derive a generalized bounded real lemma (GBRL), that is, a generalized performance criterion, for the impulsive differential subsystem by constructing a time-varying Lyapunov functional. Then, on the basis of this GBRL and utilizing the Lyapunov–Krasovskii approach, a sufficient condition is derived to asymptotically stabilize the closed-loop system and simultaneously guarantee a prescribed mixed and passivity performance index. A design method is proposed for the desired controller, which can be readily constructed by solving a convex optimization problem with linear matrix inequalities (LMIs) constraints. Finally, numerical experiments are provided to support the theoretical results, and comparisons with former approaches are also discussed.

4족 보행 로봇의 머리모듈 현가장치의 진동저감제어

The high degree of freedom in leg systems enables quadruped robots to provide superior mobility and gait robustness. Therefore, quadruped robots are regarded as a new means of transportation over rough terrain. One of the most promising applications of quadruped robots may be precise surveillance in military and disaster environments. For this purpose, the vibration of the robot body, which is unavoidable due to the repeated ground contact, should be suppressed. This paper proposes a vibration suppression control algorithm for the head suspension system of a quadruped robot. Using inertial measurement units (IMUs), the vertical velocity of the end point of the head suspension system is estimated with high reliability. The head suspension system is controlled to regulate the absolute vertical velocity of the end point of the head suspension system, i.e., a camera. The proposed absolute velocity estimation method is verified using an external camera and encoder. Finally, the vibration suppression control algorithm is verified with a quadruped robot called the Cheetaroid-I Carrier.

Numerical simulation and experimental validation of the vibration suppression control by using input shaping technique with extended Kalman filter

Numerical simulation and experimental validation of the vibration suppression control by using input shaping technique with extended Kalman filter

Adaptive Control and Predictive Control for Torsional Vibration Suppression in Helicopter/Engine System

In order to damp torsional vibrations in a helicopter, which would cause resonance in rotating components like engine, transmission, and rotor, an adaptive notch filter is proposed. Instead of fixed notch filter, the adaptive one, with FFT analyzer and sorting algorithm, can damp the low-order torsional vibration signal with natural frequency varying in a wide range. Then, in order to enhance the power following capability of the engine, a nonlinear model predictive controller based on the supported vector machine is designed to compensate for the dynamic control performance. Through the adaptive notch filter, the torsional vibration of the free turbine speed whose frequency is away from the set-point value can effectively be suppressed by 50% compared with the fixed notch filter. Furthermore, instead of conventional PID controller, the nonlinear model predictive controller based on the adaptive notch filter can reduce the sag of the free turbine to less than 0.4%. Therefore, the control strategy achieves fast high-quality response of the turbo-shaft engine.

Backstepping boundary control: an application to the suppression of flexible beam vibration

This paper presents a backstepping boundary control for vibration suppression of flexible beam. The applications are such as industrial robotic arms, space structures, etc. Most slender beams can be modelled using a shear beam. The shear beam is more complex than the conventional Euler-Bernoulli beam in that a shear deformation is additionally taken into account. At present, the application of this method in industry is rather limited, because the application of controllers to the beam is difficult. In this research, we use the shear beam with moving base as a model. The beam is cantilever type. This design method allows us to deal directly with the beam’s partial differential equations (PDEs) without resorting to approximations. An observer is used to estimate the deflections along the beam. Gain kernel of the system is calculated and then used in the control law design. The control setup is anti-collocation, i.e. a sensor is placed at the beam tip and an actuator is placed at the beam moving base. Finite difference equations are used to solve the PDEs and the partial integro-differential equations (PIDEs). Control parameters are varied to see their influences that affect the control performance. The results of the control are presented via computer simulation to verify that the control scheme is effective.

Vibration Suppression of Hamiltonian Systems with Velocity and Force Disturbances using IDA-PBC

This paper proposes a vibration-suppression control method for 2DOF Hamiltonian systems using only the relative displacements and velocities. The controller can suppress the vibration of the main body in the world coordinate, where a velocity disturbance and a force disturbance affect to the system simultaneously. The main idea of the feedback law is to convert a nonlinear 2DOF system into a desired system with virtual skyhook dampers by using the IDA-PBC technique. A parameter selection procedure is derived by combining the constraints of nonlinear IDA-PBC and the evaluation of the control performance of the linearly approximated system. The effectiveness of the proposed method is confirmed by simulations for an example.

Robust Iterative Learning Control for Vibration Suppression of Industrial Robot Manipulators

Vibration suppression is of fundamental importance to the performance of industrial robot manipulators. Cost constraints, however, limit the design options of servo and sensing systems. The resulting low drive-train stiffness and lack of direct load-side measurement make it difficult to reduce the vibration of the robot's end-effector and hinder the application of robot manipulators to many demanding industrial applications. This paper proposes a few ideas of iterative learning control (ILC) for vibration suppression of industrial robot manipulators. Compared to the state-of-the-art techniques such as the dual-stage ILC method and the two-part Gaussian process regression (GPR) method, the proposed method adopts a two degrees-of-freedom (2DOF) structure and gives a very lean formulation as well as improved effects. Moreover, in regards to the system variations brought by the nonlinear dynamics of robot manipulators, two robust formulations are developed and analyzed. The proposed methods are explained using simulation studies and validated using an actual industrial robot manipulator.

Vibration suppression-based attitude control for flexible spacecraft

In this paper, a novel approach for high-accuracy attitude control in a flexible spacecraft is developed by compensating and damping the vibration of the flexible appendage. A vibration suppression-based attitude controller (VSAC) that addresses the coupling disturbance in attitude dynamics that is generated by the vibration of the flexible appendage is developed for flexible spacecraft. The proposed VSAC integrates the existing attitude control theories with vibration suppression control strategies by combining a time delay feedback controller with a PD controller. The stability of the flexible spacecraft control system under the proposed VSAC is investigated in time domain, and the damping effect of the proposed VSAC on the vibration of the flexible appendage is analyzed in frequency domain. The proposed VSAC utilizes the traditional attitude controller and vibration suppression controller, which can not only effectively improve the performance of attitude control system but also efficiently damp the vibration of the flexible appendage. Finally, numerical simulations are performed, and analysis and conclusions are presented.

Modeling and control for rotating pretwisted thin-walled beams with piezo-composite

In this paper, a rotating thin-walled beam theory incorporating fiber-reinforced and piezo-composite is developed and used to study the active control for vibration suppression. The structural model accounts for transverse shear strain, primary and secondary warpings, pretwist and presetting angles. In addition, the centrifugal stiffening effect, tennis-racket effect, flapping-lagging-transverse shear and extension-twist couplings are accounted as well. Based on a negative velocity feedback control algorithm, the effective damping performance is optimized by studying anisotropic characteristics of piezo-actuators and elastic tailoring of the host structure. Moreover, relations between damping control authority and design factors, such as rotor speed, presetting and pretwist angles are investigated in detailed.

Active vibration control of large space flexible slewing truss using cable actuator with input saturation

SummaryThis paper proposes a composite approach to implementing attitude tracking and active vibration control of a large space flexible truss system. The system dynamic model is based on Hamilton's principle and discretized using the finite difference method. A nonlinear attitude controller for position tracking is developed based on the input‐output linearization of the discretized system, which can effectively improve system performance compared with a traditional proportional‐differential feedback controller. A taut cable actuator scheme is presented to suppress tip vibration because the mechanical model is a large large‐span spatial structure; furthermore, because the cable has the feature of unilateral input saturation constraint, which can provide only a pulling force, a nonlinear quadratic regulator controller is developed by introducing a piecewise nonquadratic cost function to suppress the vibration of the flexible structure. To investigate the factors that influence the damping effects of the cable, the parametrically excited instability of a cable under 2 supports is analyzed. Simulation results illustrate that the proposed attitude controller can implement the task of position tracking, and the vibration suppression control law is shown to be optimal for functional performance with input saturation.

Simple Physically Parameterized Observer for Vibration Suppression Control of SCARA Robot with Elastic Joints

This paper presents a practical solution for vibration suppression control of a SCARA robot with elastic joints, utilizing motor-side measurements only. We previously proposed a torsion-angular velocity feedback (TVFB) scheme for vibration suppression control. The scheme utilizes an uncomplicated nonlinear observer based on a physically parameterized dynamic model of the elastic-joint robot arm with harmonic-drive (HD) gears. The TVFB can be easily plugged into existing joint servos such as PI velocity controllers. In this paper, the TVFB scheme is applied to the SCARA robot that has a complex structure composed of rotary-vector (RV) gears, timing belts, and an elastic prismatic joint. Experiments are conducted to validate that the TVFB scheme also has the capability to suppress vibration of the tip of the elastic prismatic joint with a payload, utilizing a simple two-link two-inertia model in the nonlinear observer.