This work offers an active damping technique for automotive drive systems with backlash and uncertainty on the update timing of control input due to the control cycle limitation. The backlash existing in gears of automotive drive systems induces undesired transient vibration characteristics, which deteriorate the riding comfort, when a driving torque becomes a step signal. Furthermore, in an engine employed for the vibration control, the mechanical process to generate torque makes the control cycle time-varying, resulting in uncertainty on the update timing of control input. Consequently, an active damping technique to compensate for the update timing should be important. To compensate for the maximal phase delay of the control input caused by the time-varying control cycle, the predictive processing utilizing the sampled-data controller and the unscented Kalman filter (UKF) is employed. As the main result of this paper, a fuzzy inference is introduced into the previous approach to cope with the uncertainty on update timing of control input. This paper presents the basic idea of the compensation with two fuzzy inference rules. Finally, to confirm whether the proposed idea can suppress the vehicle body oscillations, a basic simulation verification is conducted.
This paper proposes a method to control the vibration of an automotive drive system by considering the engine torque discrete value constraint due to fuel cut. When engine torque suddenly changes, torsional vibration is generated inside the automotive drive system. This vibration interferes with driving performance and ride comfort. The previous study(1) showed that various model-based methods can be used to suppress this vibration. Currently, most automobiles are equipped with a fuel cut function for the purpose of fuel saving. In today's world, where fuel economy improvement is a priority, fuel cut has become an essential process for engines, and vibration control must take this into account. Since a certain amount of fuel is injected at once from the fuel injector when the engine returns from fuel cut, a discrete value constraint exists in vibration control that takes fuel cut into account. In this study, the optimal dynamic quantizer is introduced to the control system constructed by the model-based method to perform vibration control considering this constraint. As a basic study, simulations are conducted under the condition that the values of the engine torque are discrete values, and the performance of the optimal dynamic quantizer is discussed.
In this paper, we propose a vibration suppression method that takes fuel cutoff into account for an automobile powertrain during rapid acceleration and investigate its effectiveness. An automobile powertrain transmits engine torque to the tires, which causes vibration of the vehicle body during rapid acceleration. The engine is used as an actuator to control this vibration. However, the engine output has a constraint by fuel cut. This degrades the vibration suppression effect of vibration control. In addition, all vehicles will be controlled via controller area networks. The discretization width of control signals and the communications traffic are in the relationship of trade-off. The communications traffic in vehicles will increase in the future. Therefore, we need a control system that can suppress vibration even with coarse discretization widths. In this study, we propose a powertrain vibration control method using an optimal dynamic quantizer as the countermeasure. Optimal dynamic quantizer minimizes the effects on the tracking error (in the control system) due to the quantization. Then, we quantitatively examine the robustness at various quantization widths for the proposed control system. As a result, the optimal dynamic quantizer allows for smoother acceleration while suppressing vibration compared to the case with static quantizers. In conclusion, the performance of the proposed control system is investigated quantitatively.
This study focuses on the vibration tests of concrete materials to evaluate their dynamic characteristics including damping property. The vibration tests are conducted based on the impact excitation using an impulse hammer. The vibration response of an object is measured by a laser Doppler vibrometer. Frequency spectra are analyzed by a spectrum analyzer from the measured time history responses. This vibration test approach is applied to several specimens with different dimensions and water-cement ratios. Damping ratio of each mode for a specimen is calculated by half-width method with the measured frequency responses. The vibration test results confirmed that it is possible to extract differences in natural frequencies and damping ratios due to differences in the dimensions and water-cement ratios of the specimens. The measured natural frequencies were compared to those calculated by finite element analysis, resulting in good agreement between them. It is verified from the experiments that the present vibration test approach for the concrete materials can evaluate their dynamic properties and is effective to develop concrete structures with a desired damping in future.
This study presents a construction method of an active vibration control system which does not require mathematical models of controlled objects. A virtual controlled object (VCO) which is a user-defined single-degree-of-freedom (SDOF) system is introduced between an actuator model and an actual controlled object. The appropriate parameter selection of the VCO yields the model-free vibration control. A state equation for the model-free controller design is derived based on the actuator model and the VCO. A model-free state feedback controller is designed via the traditional linear quadratic regulator (LQR) theory. A reference controlled object (RCO) is defined on behalf of the arbitrary controlled objects to tune the VCO-based model-free LQR. An automatic controller parameter tuning scheme is constructed based on the RCO and the simultaneous perturbation stochastic approximation (SPSA) algorithm. The effectiveness of the proposed method is examined by vibration suppression simulations.
In general, active vibration control is expected to have a high damping effect, but it is designed using the model of the target structure. Therefore, the designed control system may not achieve the desired damping performance due to modeling errors of the target structure or property fluctuations caused by aging. Since the control system is designed for each target structure, it cannot be used for other target structures. In addition, since the modes that can be damped by a single actuator depend on its placement, there may be some modes that cannot be damped by a single actuator if there are restrictions on its location. In this study, we designed a control system without using a model of the target structure, proposed a method to control vibration of arbitrary structures, and applied this method to multiple actuators. First, a model was created by introducing a virtual structure that represents an arbitrary target structure between the actuator and the target structure. A control system based on the homogeneous exponential stabilization control was designed for this model. Using this controller, vibration control simulations were performed on a finite element model of a nominal cantilever beam. Considering the difference in the vibration control effect for the modes depending on the arrangement of the actuators, the arrangement of multiple actuators was determined. Multiple actuators were applied to the determined configurations, and vibration control simulations were performed for the nominal structure and the structure with characteristic variations to demonstrate the effectiveness of the system.
Vibration control of building structures has become more important in recent years as buildings have become taller. Active vibration control is a technique that can be expected to have a high vibration control effect, but it requires a model of the object to be controlled, therefore the vibration control performance depends on the accuracy of the model. This leads to a reduction in vibration control performances and instability of the control system due to modelling errors and characteristic fluctuations over time. To solve these problems, we should improve modelling accuracy and robustness, however this increases the designer's burden. In addition, as the control system is designed for one target structure, it cannot be easily transferred to other structures. For these problems, this study proposes an active vibration control method for multiple-story structures that does not require modelling of the controlled target. First, an H2 controller is designed to indirectly suppress the vibration of the real object by introducing a virtual single-degree-of-freedom controlled object between the actuator and the actual controlled object. Next, vibration control simulations were performed on different multiple-story structure models to demonstrate the effectiveness of the model-free vibration control on arbitrary multiple-story structures.
In this paper, we propose a vibration suppression method that takes fuel cutoff into account for an automobile powertrain during rapid acceleration and investigate its effectiveness. An automobile powertrain transmits engine torque to the tires, which causes vibration of the vehicle body during rapid acceleration. The engine is used as an actuator to control this vibration. However, the engine output has a constraint by fuel cut. This degrades the vibration suppression effect of vibration control.In addition, all vehicles will be controlled via controller area networks. The discretization width of control signals and the communications traffic are in the relationship of trade-off. The communications traffic in vehicles will increase in the future. Therefore, we need a control system that can suppress vibration even with coarse discretization widths. In this study, we propose a powertrain vibration control method using an optimal dynamic quantizer as the countermeasure. Then, we quantitatively examine the control performance at various quantization widths for the proposed control system. The performance of the proposed control system is investigated quantitatively.
