Acceleration Feedback Control Research Articles

Design of a linear motor-based shaker rig for testing driver's perceived ride comfort

In autonomous vehicles the driver will become a passenger. By ensuring a high level of ride comfort through active suspensions, the driver's ability to perform various tasks such as reading, drawing and texting can be enhanced. A high-performance shaker rig can conveniently be used to test the ride comfort improvement by means of various active suspensions under laboratory conditions. The paper deals with the design of such a rig, which employs a linear electric servomotor to impose accurately controlled vertical vibrations of driver seat. The reference time profiles of seat acceleration, velocity and displacement are generated off-line by using a half-car vehicle model and LQR control with a road preview option. The selection of linear motor comes from assessment of three characteristic shaker rig drive designs (hydraulic and two electric ones). To ensure high-precision seat motion, the proposed shaker control system includes: acceleration feedforward and feedback control loops, a state controller-like compensator of accelerometer offset to prevent drift of seat position and velocity, and feedforward compensation of linear motor cogging force mode. The designed shaker rig application is demonstrated through a case study related to ride comfort evaluation of various active suspension configurations and a drawing task. The drawing task results are employed to determine the root-mean-square vertical seat acceleration threshold, below which the active suspension drawing task performance remains similar to that obtained under standstill conditions.

Controlling self-excited vibration of a nonlinear beam by nonlinear resonant velocity feedback with time-delay

In this paper, the efficacy of velocity feedback based nonlinear resonant controller is proposed to control the free and forced self-excited vibration of a nonlinear beam. The velocity signal obtained from the sensor is fed through a second-order filter and the nonlinear function of the derivative of the filter variable is used to obtain the control force. The resulting control system being a band-pass one, is believed to be superior to other resonant control schemes like Positive Position Feedback (PPF) control and Acceleration Feedback Control (AFC). To the best of the authors’ knowledge, it is the first attempt to explore the efficacy of resonant nonlinear velocity feedback controller for mitigating self-excited vibration. Analytical results are obtained using multiple time-scale method, are validated with the data obtained from direct numerical simulation carried out in Matlab Simulink model. Analytical results of the uncontrolled system show the periodic, quasi-periodic as well as chaotic behavior. It is observed that the proposed controller can reduce the amplitude of vibration by a significant level near primary resonance. Moreover, the Hopf bifurcations are eliminated by the control action. It is also observed that the proposed controller can reduce the amplitude of the chaotic oscillation significantly. The effect of the actuation delay in the feedback loop is also explored. It is observed that the effect of time delay is detrimental to system performance.

Active Control of Submerged Systems by Moving Mass

In this study, the active vibration control of a rectangular plate submerged in water was investigated. Mass dampers were attached to the plate, and the system was modeled via assumed mode. Water is modeled as an inviscid fluid with moving boundaries at fluid–solid interaction surfaces and applied forces on the plate being calculated by Bernoulli equation. The natural frequencies of the plate in vacuum and in water (for partial and fully submerged cases) found from numerical calculations are compared with experimental results to prove the accuracy of the model. Subsequently, for frequency computations, particular frequencies were chosen and active damping was applied for them. To actively control the plate’s vibration by a moving mass with static stable methods, the displacement data of some points were used as input. First, to increase the damping of target mode at low-frequency, the negative acceleration feedback control algorithm in modal-space was applied. Then, the decentralized method was examined. Both methods were successful in suppressing vibration of the submerged rectangular plate.

Control parameter optimization of a nonlinear vehicle suspension system with time-delayed acceleration feedback

A time-delayed acceleration feedback control is proposed to improve the vibration performance of a nonlinear vehicle suspension system. First, the harmonic balance method is applied to obtain the vertical acceleration amplitude of the system excited by simple harmonic road excitation. Then, taking the amplitude of the sprung mass acceleration and control force into account, the single-objective and multiple-objective optimization problems of time-delayed feedback control parameters, respectively, are discussed. Finally, the mathematical simulation is provided to verify the correctness of the optimization results. It is concluded that the nonlinear suspension with optimal time-delayed feedback control has better vibration control performance compared to passive one. The acceleration amplitude of the sprung mass is significantly reduced by the single-objective optimization of the control parameters. Moreover, when the optimal time delay is introduced, the active control force input is fewer than that without time delay. The phenomenon of energy transfer between the sprung mass and the unsprung mass is observed in some road-excitation frequencies.

Contact transition control with acceleration feedback enhancement for a quadrotor

A stable transition from free-motion to contact phase is extremely significant for a UAV interacting with its objects and environment. Oscillations may occur at the contact point if the force controller of the UAV fails to accommodate to the environment parameters, which are usually unknown to the UAV. In this paper, the acceleration feedback control is proposed to enhance the robustness of a classic force controller. This intends to achieve a smooth and stable contact transition of the UAV while interacting with different stiffness environments with non-zero approaching velocity. Extensive flight tests are conducted on a quadrotor UAV to verify the performance of the proposed algorithm with respect to different-stiffness environments. The experimental results are also compared with those without the acceleration feedback enhancement, to demonstrate the improvement of the proposed scheme.

Modeling and Analysis of Suspension Frame of Maglev Train

Based on the acceleration feedback system, the vertical dynamic model of the low-speed maglev train is established. By decoupling the suspension frame module, the author conducted a stress analysis of the single-sided and the entire suspension system, and established a system dynamics model of the suspension frame. The suspension controller is designed using classic PD control and acceleration feedback control methods. Then, the author used Simulink to create a dynamic simulation analysis program to analyze the dynamic performance of the suspension system affected by track misalignment and external disturbance forces, and analyze the impact of the suspension frame’s parameter design on the suspension system performance.

Reduction in the Fluctuating Load on Wind Turbines by Using a Combined Nacelle Acceleration Feedback and Lidar-Based Feedforward Control

An advanced pitch controller is proposed for the load mitigation of wind turbines. This study focuses on the nacelle acceleration feedback control and lidar-based feedforward control, and discusses how these controllers contribute to reduce the load on wind turbines. The nacelle acceleration feedback control increases the damping ratio of the first mode of wind turbines, but it also increases the fluctuation in the rotor speed and thrust force, which results in the optimum gain value. The lidar-based feedforward control reduces the fluctuation in the rotor speed and the thrust force by decreasing the fluctuating wind load on the rotor, which reduces the fluctuating load on the tower. The combination of the nacelle acceleration feedback control and the lidar-based feedforward control successfully reduces both the response of the tower first mode and the fluctuation in the rotor speed at the same time.

Improvement of the band-gap characteristics of active composite laminate metamaterial plates

The characteristics of vibration frequency band-gaps for the composite laminate metamaterial plates are improved by equidistantly placing macro-fiber composite (MFC) piezoelectric patches along one direction of the plates. An acceleration feedback control strategy is proposed to actively regulate the band-gap characteristics of the metamaterial plates. The spectral element method (SEM) and transfer matrix method are used to calculate frequency response curves and attenuation constants of the metamaterial plates, and the calculated results by the SEM are compared with that of the finite element method (FEM) to validate the correctness and accuracy of the present numerical method. The obtained results demonstrate that when lattice constant of the structure is properly designed, superior band-gap properties in the low and medium frequency ranges can be achieved by adjusting the dimensions of the MFC piezoelectric patches. Improved characteristics of the Bragg scattering band-gaps in the medium and high frequency regions can also be obtained using the acceleration feedback control strategy. Moreover, band-gap widths can be significantly enlarged by actively tuning the acceleration feedback gain. In addition, the starting frequencies and band-gap widths of the composite laminate metamaterial plates can be adjusted using different cross-ply angles of the MFC piezoelectric patches and composite laminate metamaterial plates.

Active tunability of band gaps for a novel elastic metamaterial plate

A novel active elastic metamaterial plate is proposed, with tunable vibration band-gap characteristics is by using the periodically placed piezoelectric actuator and sensor pairs along one direction of the plate. Active control strategies are employed to actively adjust the band-gap properties of the metamaterial plate. Displacement and acceleration feedback control methods are applied to design the controllers so that the positive active stiffness and inertia for the elastic metamaterial plate can be provided. The dynamic responses of the finite plate with periodic piezoelectric actuator/sensor pairs are calculated using the spectral element method (SEM), and the calculation accuracy of the SEM is validated by the finite element method. The present results reveal that zero-frequency band gaps can be generated for the elastic metamaterial plate, and the band-gap characteristics in the medium and high frequency ranges can be significantly enhanced by using the acceleration feedback control. Moreover, very wide band gaps for the elastic metamaterial plate can be obtained by using the active acceleration control, and the starting frequencies of the first band gap under the acceleration control can be reduced by increasing the acceleration control gain. The widths of the zero-frequency and Bragg-type band gaps for the elastic metamaterial plate can be amplified by increasing the displacement feedback control gain. The control voltages to be applied on the actuators for the elastic metamaterial plate are also calculated and discussed.

Nonlinear Vibration Mitigation of a Beam Excited by Moving Load with Time-Delayed Velocity and Acceleration Feedback

The time-delayed velocity and acceleration feedback control are provided to mitigate the resonances response of a nonlinear dynamic beam. By use of the method of multiple scales, the primary resonance and the 1/3 subharmonic resonance response of the controlled beam are analyzed. The excitation amplitude response peak and critical expression are obtained, and numerical simulations are also given. The effect of the feedback gains and time delayed on the steady-state response of the two types of resonances are investigated. The result show that time-delayed acceleration feedback control can effectively mitigate amplitude, and the main resonance response is affected periodically. Selecting reasonable control gain and time delay quantity can avoid the main resonance region and unstable multi-solutions, and can improve the efficiency of the vibration control.

Displacement and acceleration feedback controller design for automated driving tram

Automated driving in train is discussing about partially implementation. Those implementations in limited area and situation marked well progress such as general railway lines and AGT. Tram vehicle on mixture traffic seems to be next target of them. Usual automated driving train is controlled considering with velocity and displacement as a position. However, tram vehicle run in the more complex situation than usual automated driving trains. Thus, there are much possibility braking to avoid collision with other traffic participants. In this time, the comfortability of passengers is decreasing if the huge braking acceleration occurring since acceleration is strongly relationship with it. Thus, Automated driving tram should be considered to control with acceleration to let acceleration smaller to improve passenger comfort. So, both displacement and acceleration feedback control are required. However, direct acceleration feedback should consider drift or noise on sensing results. This paper introduces direct acceleration feedback control with direct displacement control for positioning. These controllers are designed by Unified approach and Composite Filter. These controllers are considering with noise reduction for accelerometer. The example controller designed for small experimental rig on the rail are introduced with numerical simulation results. These results show the controllers can set desired poles related with settling time without considering of noise reduction frequency.

Research on Active Obstacle Avoidance Control Strategy for Intelligent Vehicle Based on Active Safety Collaborative Control

Aiming at the issue of active obstacle avoidance control for intelligent vehicles under emergency, an active safety collaborative control system integrated with adaptive cruise control (ACC), rear steering control (RSC), and rollover braking control (RBC) is developed. The proposed novel control architecture consists of a supervisor, an upper controller, and a lower controller. The supervisor decides which control mode to be used based on multi-sensors information of the driving vehicle. Active rear wheel steering based on lateral acceleration feedback and active braking control strategies based on fuzzy PID are added into the control model to enhance driving stability. To make the vehicle motion control model suitable for highway path tracking with obstacle avoidance under emergency, a priority is given to the RBC controller even though the vehicle speed is lower than the expected speed when the rollover index exceeds the safety threshold. A nonlinear vehicle simulation model is established to validate the proposed control scheme based on Carsim. Finally, a Carsim-Simulink co-simulation model is constructed, and simulation results show that the proposed integrated control strategy based on active safety collaborative control has good performance in both path tracking and driving stability, and has better stability of rollover under emergency.

Mitigating vortex-induced vibration by acceleration feedback control

Vortex-induced vibration is a common phenomenon observed in many engineering applications and it is detrimental to the performances and health of the system. It is, therefore, imperative for engineers to make suitable design modifications or arrange for some type of control device to mitigate such oscillations. In this paper, the performance of the acceleration feedback control is compared with that of the simple passive vibration absorber. The effect of time-delay in the feedback loop is also investigated. The acceleration of the primary system is measured and passed through a second-order compensator. The active absorber is designed by setting the filter frequency same as the natural frequency of vibration and the optimum filter damping is numerically obtained. Nonlinear analysis is performed using the Describing Function method and the results are validated using direct numerical simulation performed in MATLAB Simulink. In the present paper, vortex shedding frequencies are selected from two different regions, one with vortex shedding frequency less than the natural frequency of the system and other having vortex shedding frequency higher than the natural frequency of the system. It is observed that the acceleration feedback control can effectively reduce the amplitude of vibration to a great extent. It is also observed that the amplitude of the system changes marginally (up to a certain value of time-delay) in the pre-locking and locking region. However, the effect of time-delay in post-locking zone is detrimental. Beyond a certain value of the time-delay, the amplitude becomes large and even the system may become unstable.

External Vibration Damping of a Robot Manipulator's TCP Using Acceleration Feedback

AbstractThere are multiple possible applications, which demand high accuracy from industrial robot arms. The usual approach to improve the path accuracy of these robot manipulators is to make the mechanical design as stiff as possible and to employ high fidelity joint controllers, which compensate path inaccuracies with well‐identified models of the manipulator system. These methods are, however, only available to the robot manufactures themselves during their development phase. Companies designing tools for specific high accuracy tasks generally cannot change the design of a given robot manipulator and are bound to its precision. An alternative concept to further increase the path accuracy of a robot manipulator, without making changes to its design itself, might be to employ traditional Active Vibration Damping techniques by adding a supplementary proof‐mass actuator to the robots tool center point with collocated acceleration sensor feedback. This paper explores the feasibility of this idea within a multi body simulation of a simple robot manipulator, which consist of rigid links, flexible joints and is actuated by cascaded joint controllers. The performance of an acceleration feedback controller employed on the robots TCP is evaluated by a test trajectory.

Acceleration feedback control for enhancing dynamic stiffness of fast tool servo system considering the sensor imperfections

Lorentz type fast tool servo devices have found wide applications in freeform machining but they face problems of insufficient stiffness with large depth of cut. Acceleration feedback control is an alternative way to enhance the dynamic stiffness without the need for a large inertia, which is strictly limited in fast tool servo devices. However, the current knowledge gap in the understanding of the influences of limited sensor bandwidth and sensor noises on positioning performance has impeded the application of acceleration feedback control approach in fast tool servo devices. This paper established an analytical model to reveal, for the first time, how much positioning errors are caused by the added sensor noises and how the acceleration feedback technique changes the closed loop stiffness. The measured positioning error spectrum agrees with the modelled one with different acceleration gains. The stiffness model is verified through frequency response tests. It is found that the dynamic stiffness is significantly improved by 5.6 folds within the acceleration sensor bandwidth, while the stiffness deteriorates at frequencies beyond the bandwidth due to the low-pass characteristics in the acceleration loop. The stiffness analysis results are further verified in the intermittent facing cut experiments. The measured surface form errors can be mapped to the low frequency and high frequency vibrations caused by the cutting forces. The analysis model provides a theoretical basis for adopting acceleration feedback technique, paving the way for its practical implementations in ultra-precision applications.

Controlling self-excited vibration using acceleration feedback with time-delay

This paper investigates the control of vibration of a self-excited system, namely Rayleigh Oscillator, by using Acceleration Feedback Control method. In this control scheme, acceleration of the vibrating system is fed back to a second-order compensator and the control force is produced by amplifying the signal obtained from the compensator. Linear and non-linear stability analyses are performed. Linear stability analysis is used to obtain the stability regions and the optimal system parameters. Non-linear analysis is performed using Describing Function method. Acceleration feedback control is found to be effective in controlling the self-excited vibration. The presence of time-delay is also studied in this paper. It is observed that the presence of uncertain time-delay in the feedback loop can be detrimental. The optimal system (optimized for no delay case) can result in instability of the static equilibrium leading to finite amplitude oscillation. However, one can improve the situation by increasing the loop-gain. In order to circumvent this problem, it is proposed that a pre-determined time-delay may be introduced in the feedback circuit and the control parameters are re-optimized considering this time-delay. As a result, the system equilibrium can be stabilized even in the presence of time-delay. The results of theoretical analysis are validated with the simulation results performed in MATLAB Simulink.

Active vibration control of plate by active mass damper and negative acceleration feedback control algorithms

In this study, an active mass damper that could track desired displacement was considered as a controller to suppress vibrations of a plate. Multi-input multi-output modal-space negative acceleration feedback control algorithm and decentralized multi-input multi-output negative acceleration feedback control algorithm were proposed and their stability conditions were checked theoretically. Stability conditions for both controllers are static, and they can effectively increase the damping of target mode without causing instability in low-frequency region. It was proved theoretically that both the multi-input multi-output modal-space negative acceleration feedback control and the decentralized multi-input multi-output negative acceleration feedback control can suppress vibrations of a continuous system such as a plate.

Design of Tuneable Vibration Absorber by Using Inertial Actuator with Proof-Mass Acceleration Feedback

This study is concerned with design of a tuneable vibration absorber by using an inertial actuator (IA) with its proof-mass acceleration used as feedback signal. Acceleration feedback control loop can produce virtual mass effect, and the natural frequency of the IA can be shifted. The main advantage of the proposed IA-based tuneable vibration absorber is that the control loop is very simple and does not require any low-pass filter or integrator. Finally, the experimental results are presented to verify the tuning capability and control performance of the proposed vibration absorber.

Design of a hybrid proportional electromagnetic dynamic vibration absorber for control of idling engine vibration

A hybrid proportional electromagnetic dynamic vibration absorber consisting of an electromagnetic actuator and an elastic element is proposed for control of engine vibration during idling. The design of the proportional electromagnetic actuator is realized considering the geometric parameters of the core to achieve nearly constant magnetic force over a broad range of its dynamic displacement but proportional to square of the current. The dynamic characteristics of the electromagnetic dynamic vibration absorber are analyzed analytically and experimentally. The effects of various geometric parameters of the actuator such as the slopes and width/height, and the air gaps on the resulting magnetic force characteristics are evaluated using a finite element model and verified experimentally. A methodology is proposed to achieve magnetic force proportional to current and consistent with the disturbance frequency. The hybrid proportional electromagnetic dynamic vibration absorber is subsequently applied to a single-degree-of-freedom primary system with an acceleration feedback control algorithm for attenuation of primary system vibration in a frequency band around the typical idling vibration frequencies. The effectiveness of the hybrid proportional electromagnetic dynamic vibration absorber is evaluated through simulations and laboratory experiments under harmonic excitations in the 20–30 Hz frequency range. Both the simulation and measurements show that the hybrid proportional electromagnetic dynamic vibration absorber can yield effective attenuation of periodic idling vibration in the frequency range considered.

Design of a Micromachined Z-axis Tunneling Magnetoresistive Accelerometer with Electrostatic Force Feedback.

This paper presents the design, simulation, fabrication and experiments of a micromachined z-axis tunneling magnetoresistive accelerometer with electrostatic force feedback. The tunneling magnetoresistive accelerometer consists of two upper differential tunneling magnetoresistive sensors, a middle plane main structure with permanent magnetic films and lower electrostatic feedback electrodes. A pair of lever-driven differential proof masses in the middle plane main structure is used for sensitiveness to acceleration and closed-loop feedback control. The tunneling magnetoresistive effect with high sensitivity is adopted to measure magnetic field variation caused by input acceleration. The structural mode and mass ratio between inner and outer proof masses are optimized by the Ansys simulation. Simultaneously, the magnetic field characteristic simulation is implemented to analyze the effect of the location of tunneling magnetoresistive sensors, magnetic field intensity, and the dimension of permanent magnetic film on magnetic field sensitivity, which is beneficial for the achievement of maximum sensitivity. The micromachined z-axis tunneling magnetoresistive accelerometer fabricated by the standard deep dry silicon on glass (DDSOG) process has a device dimension of 6400 μm (length) × 6400 μm (width) × 120 μm (height). The experimental results demonstrate the prototype has a maximal sensitivity of 8.85 mV/g along the z-axis sensitive direction under the gap of 1 mm. Simultaneously, Allan variance analysis illustrate that a noise floor of 86.2 μg/Hz0.5 is implemented in the z-axis tunneling magnetoresistive accelerometer.