Transmissions require a good shift feeling and improved fuel efficiency. In state-of-the-art stepped automated transmissions, the number of gear stages increases, and the lock-up area is expanded to ...improve fuel efficiency. However, this makes it difficult to obtain a good shift feeling and it takes a large number of calibration man-hours. Therefore, to reduce the number of calibration man-hours and improve the shift feeling, we propose a slip control law between the engine and the clutch, which is composed of a proportional-integral-derivative (PID) controller and a disturbance observer. Moreover, PID gain is adjusted online by installing an automatic tuning method, which does not require a controlled object model. The effects of the proposed method are verified via an experiment using an actual vehicle. The experimental results show that the proposed method is effective for automatically adjusting PID gain and improving the shift feeling of the stepped automated transmission.
•DEA appropriate for vibration control at high frequencies is developed.•Appropriate layer of DEA generating effective control force is determined.•Actuator location and shape are optimized by modal ...strain energy of the structure.•The validity of the present method is demonstrated by control experiment.
This study evaluates the basic characteristics of smart structures composed of dielectric elastomer actuators (DEAs) to suppress vibrations. A DEA, which is a lightweight, flexible polymer that can induce high deformations, should realize next-generation actuators. Additionally, DEA can achieve vibration control of structures with complex shapes or curved surfaces. Herein the performance and efficacy of DEAs are evaluated as an actuator for vibration control at high frequencies. First, the appropriate DEA structure is considered. Second, the control system for the smart structure using the DEA is modeled and designed as an actuator. Third, a method to determine DEA's optimum arrangement and shape is discussed by focusing on the structure's strain energy. Finally, a control simulation and a control experiment validate the vibration suppression effects and the efficacy of the DEA.
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The purpose of this research is to construct a simple and practical controller design method, considering the actuator’s parameter uncertainty, without using a model of controlled objects. In this ...method, a controller is designed with an actuator model including a single-degree-of-freedom virtual structure inserted between actuator and controlled object, resulting in a model-free controller design. Furthermore, an
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control problem is defined so that the actuator’s parameter uncertainty is compensated by satisfying a robust stability condition. Because the actuator model including the virtual controlled object is a simple low-order system, and the actuator’s parameter uncertainty is considered, a controller with high robustness to the actuator’s parameter uncertainty can be designed based on traditional model-based control theory. The effectiveness of the proposed method is verified by both simulation and experiment.
The purpose of this study is to develop a simple and practical controller design method without modeling controlled objects. In this technique, modeling of the controlled object is not necessary and ...a controller is designed with an actuator model, which includes a single-degree-of-freedom virtual structure inserted between the actuator and the controlled object. The parameters of the virtual structure are determined so that indirect active vibration suppression is effectively achieved by considering the frequency transfer function from the vibration response of the controlled object to that of the virtual structure. Since the actuator model, which includes a virtually controlled object, is a simple low-order system, a controller with high control performance can be designed by traditional model-based optimal control theory. In this research, a mixed
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controller is designed considering both control performance and robust stability. The effectiveness of the proposed method is validated experimentally. The robustness of the controller is demonstrated by applying the same controller to various structures.
This study proposes a gain-scheduled controller with direct tuning for the position control of a pneumatic clutch actuator that is installed in heavy-duty trucks. Pneumatic clutch actuators are ...highly nonlinear systems and cannot be easily controlled. Industries require a simple controller design that is easy to understand and requires few trial-and-error calibrations. Therefore, we adopted a gain-scheduled proportional integral derivative (PID) control law, which is a well-known and easy-to-understand nonlinear control method. In this approach, a gain scheduler is expressed using polynomials composed of coefficient parameters and controlled object states. The unknown coefficient parameters of the polynomials are directly tuned from the controlled object input/output data without having to use a controlled object model. The proposed controller design procedure is simple and does not require system identification or trial-and-error tuning. The effectiveness of the proposed method is verified by an experiment using an actual vehicle. The experimental results confirm the effectiveness of the proposed method for the position control of pneumatic clutch actuators.
•DEA is applied to reduce multiple modes vibration of a membrane structure.•Frequency responses are measured with laser excitation/measurement system.•Controller for vibration control is designed ...based on H∞ control method.•Vibration control experiment is conducted in a vacuum environment.•Effectiveness of the proposed method is validated by experiments.
A vibration suppression technique for lightweight and flexible membrane structures is proposed using smart structure technology with a dielectric elastomer actuator (DEA). DEA, which is a lightweight flexible polynomial material with a large deformation and high response time, can easily be applied to membrane structures for vibration suppression over a wide frequency range. Herein, active vibration control for membrane structures with DEA is examined. A non-contact excitation system with a high-power Nd:YAG pulsed laser precisely measures the vibration responses of membrane structures. A laminated DEA is fabricated and attached to the membrane surface, generating a highly reproducible ideal impulse excitation. Then a digital control system is constructed with the laser excitation system. To demonstrate the effectiveness of the proposed method, vibration control experiments are conducted using a controller designed by H∞ control theory with the identified membrane model in both atmospheric and vacuum environments.
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In this paper, we present a data-driven tuning method for model-free control based on an ultra-local model (MFC-ULM), which is also called intelligent proportional-integral-derivative control. In ...industries, the control design must be easy, and it is important that the control law can be applied to nonlinear systems. The MFC-ULM has most of these features. However, in practice, trial-and-error tuning of MFC-ULM design parameters is necessary. To address this problem, we adopt a data-driven tuning approach. In the proposed method, the MFC-ULM design parameters can be tuned from single-experiment data without requiring system identification, and optimal parameters for the MFC-ULM are obtained using the least-squares method. Additionally, we adopt <inline-formula> <tex-math notation="LaTeX">L_{2} </tex-math></inline-formula>-norm regularization to avoid overlearning. The effectiveness of this method was examined using simulations of two nonlinear systems. The results revealed that the MFC-ULM design parameters can be obtained directly without knowing the characteristics of the controlled object.
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•DEA excitation technique is applied to a vibration experiment for pear fruit.•Pear fruit firmness during storage is evaluated using a firmness index.•Variations of firmness indices ...are approximated based on the least square method.•Mode shapes of pear fruit are extracted via experimental modal analysis.•Evaluating firmness indices demonstrates the effectiveness of the proposed method.
This study proposes a vibration technique based on the dielectric elastomer actuator (DEA) excitation to determine the resonance frequency of La France pear fruit. Postharvest pear fruit ripen during storage to improve their quality. A non-destructive measurement technique is necessary to predict maturity without damaging the fruit. The maturity of pear fruit is correlated with firmness, which can be assessed by a firmness index derived from the resonance frequency and the mass. Because DEAs exhibit characteristics that are conducive to vibration applications such as flexibility, lightweight, responsiveness, and deformability, they can be applied and effectively transfer excitation forces to fruit or vegetables with curved surfaces. In this study, the proposed technique is used to evaluate the variations in firmness indices of pear fruit during storage. Additionally, the firmness is measured using a penetrometer to verify the correlation with the firmness index. Using a vibration test system, the distinct frequency responses of pear fruit are obtained and the resonance peaks of the first elastic mode are observed around 700 Hz. The firmness indices of the target fruit are (21.6±2.5)×106 Hz2 g2/3 on day 0 and tend to decrease during storage. The tendency of each fruit is approximated based on a nonlinear least square method. Moreover, the firmness indices are well correlated with the results of the penetrometer test, demonstrating the effectiveness of the proposed technique to evaluate pear fruit quality.
This paper proposes a noniterative direct data-driven gain-scheduled control. Gain-scheduled proportional-integral-derivative (PID) control is one of the most popular approaches for nonlinear ...systems. However, compared to fixed PID, gain-scheduled PID has considerably more scheduler parameters and requires time to tune them, which is the problem in conventional methods that include hand-tuning and model-based control design. To solve these problems, a noniterative data-driven tuning method for a gain-scheduled controller with polynomials via tuning approach using a fictitious reference signal is proposed. The proposed method enables tuning of the parameters from one-shot data obtained from a test without the system model to be controlled. To verify this method, the numerical simulation for two types of nonlinear systems is conducted. Therefore, the proposed method enables the parameters of the gain-scheduled controller to realize high tracking performance.
The direct tuning of controller parameters, which is based on data-driven control, has been attracting considerable attention because of the ease of its control system design. In practical use, it is ...important to consider the stability of the closed-loop system and model matching with few design parameters. In this study, we propose a direct tuning method based on a fictitious reference signal that considers the bounded-input bounded-output (BIBO) and model matching without repeating experiments. The proposed method includes two steps. In the first step, the BIBO stability is satisfied. The pole information is lost in the cost function of the conventional method using a fictitious reference signal. Then, we derive a new cost function that can prevent the loss of the pole information. This provides controller parameters that can stabilize the closed-loop system. The model matching between the reference model and the closed-loop system is considered in the second step. When model matching is achieved, the characteristics of the reference model almost match those of the closed-loop system, including the gain and phase margins. The parameters of the reference model are automatically tuned to realize model matching. Using the two-step method, we can obtain parameters considering BIBO stability and the model matching. In addition, there are no design parameters apart from the dealing noise. Two simulations and an experiment were performed on a system with dead time to verify the effectiveness of the proposed two-step method. The results showed that the proposed method provides BIBO stability and model-matched control parameters from the measured data through a one-time experiment without trial and error.
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