Identification of task model using piecewise affine systems with variable switching points and its application

This paper considers a human‐operated task model based on identification techniques using switched systems expressed by mixed logical dynamical systems. In the system, each subsystem is expressed by a piecewise affine system. For a model to be identified, it is not easy to determine a number of subsystems in advance. In this paper, we propose a simultaneous identification technique which takes into account both a number of subsystems and parameters, so that a piecewise affine model of a human operation can be obtained. In addition, the obtained model is applied to automation. The effectiveness of the proposed method is illustrated by simulations and experiments. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(1): 46–54, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21079     

Refinement of inverter model considering dead‐time for performance improvement in predictive instantaneous current control

Model predictive instantaneous‐current control (MPIC), which was proposed in our earlier works, enables us to achieve better instantaneous current control using mathematical models of an inverter and permanent magnet synchronous motors (PMSMs). However, dead‐time to avoid short breakdown in the inverter is not usually considered in a general inverter model. Such an unmodeled part in the inverter model prevents accurate prediction of current evolution in motor systems based on the model predictive control. Therefore, in this paper, we analyze current response resulting from the dead‐time in the MPIC, and propose a refined inverter model considering the dead‐time so that control performance is improved. The effectiveness of the proposed method is verified through simulation and experiments. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Switching of H∞ controller under constraints and decision of controller state at instance of the controller switching

In real control systems, certain constraints are placed on the input, state, and output values. If such constraints are violated, the system may become unstable, in a worst‐case scenario. One of the promising approaches to solving this problem is to switch the controller according to the state of the closed‐loop system. No useful design strategy for each controller, however, has yet been developed. In addition, the determination of the controller state at the instant of controller switching has not been investigated. First, this paper presents a new design methodology which merges the switching control and H_∞ controller design into one design algorithm. Second, this paper presents a way of determining the controller state at the instant of controller switching. Finally, the proposed method is applied to force control of a one‐DOF manipulator in order to demonstrate the usefulness of the proposed method. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 142(2): 68–75, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10082     

Identification of Human Operations Using Data Clustering and its Applications to Automation

Some human operations are realized by the combination of continuous behaviors and logical judgment. Such a system is called a hybrid dynamical system (HDS). In this study, we consider a driving task as an HDS. Then, we identify the task using the clustering method, which is one of the methods used to identify an HDS. In addition, we apply the identified model to an automatic driving system. Both the simulation and application results illustrate the effectiveness of the proposed approach. © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Quantized feedback stabilization of linear discrete‐time systems with constraints

This paper addresses the quantization of control systems. The state of the system is quantized by means of a quantizer. In addition, constraints on the input and/or state are considered explicitly. For a linear system with no constraints, some quantized feedback control methods have been proposed. In this paper, a control methodology for a constrained system is proposed. Specifically, the idea of a positively invariant set is introduced so that the performance is improved while the constraints are satisfied. The effectiveness of the proposed method is verified through both simulation and experiment. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(3): 53–61, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21122     

Association of the antibodies against human papillomavirus 16 E4 and E7 proteins with cervical cancer positive for human papillomavirus DNA

Occurrence of the antibodies against human papillomavirus (HPV) 16 proteins E4 and E7 is specifically but independently associated with cervical cancer. To correlate HPV DNA and antibody data, we examined the biopsy specimens and sera, by polymerase chain reaction (PCR) and by ELISA, respectively, from 51 patients with cervical cancer (including 3 recurrent cases) and 22 with cervical intra-epithelial neoplasia. Consensus primers for the L1 region were used for PCR and bacterially expressed, purified fusion protein HPV-16 E4 and non-fusion protein HPV-16 E7 were used for ELISA. HPV-16 DNA and other HPV types were detected in 17 and 25, respectively, out of 51 cases of cervical cancer. Ten out of the 17 HPV-16-DNA-positives were positive either for anti-E4 or for anti-E7: positivities for anti-E4, for anti-E7, and for both were 6/17, 5/17 and 1/17 respectively. Three anti-E7-positives consisted of those for HPV-33, -52 and -58 DNA, suggesting that limited cross-reaction occurred between the HPV types. Among the HPV-16-DNA-positive cases of cancer, lymph-node or distant metastasis was recorded more frequently in the seropositives than in the seronegatives. Our results show that the HPV-16 anti-E4 or anti-E7 occurs in some, but not in all, of the HPV-16-DNA-positive cases, and support the hypothesis that the presence of the HPV-16 antibodies can be used as a marker for possible metastasis.     

Off-line model predictive control of DCDC converter and its experimental verification

This paper presents an optimal control method for DCDC converters. The system is modeled as a mixed logical dynamical system so that the switching property can be considered explicitly. Specifically, the input of the system is confined to a discrete value whereas the output to be controlled is a continuous value. The optimal control law for the system is obtained by means of off-line model predictive control. The effectiveness of the proposed method is illustrated through numerical simulations and experiments. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Transformation algorithm from Ladder Diagram to SFC using temporal logic

The Ladder Diagram (LD) has been widely used in industry as a language for sequential control. However, the LD cannot represent sequential flows of control logic explicitly. This leads to difficulties for other engineers in understanding the control logic. To overcome this problem, the Sequential Function Chart (SFC) has been proposed. Because the SFC can represent sequential flow explicitly, it is expected to be used more widely. Since the LD has been widely used in the past, however, it is necessary to develop an algorithm for transformation from the LD to the SFC. In this paper, a technique to transform an LD to the corresponding SFC by using temporal logic is proposed. In the closed loop system which consists of the LD and the controlled plant, sequence information including parallel path divergences is extracted to develop the transformation algorithm. An example is presented to verify the feasibility of the proposed algorithm. © 1999 Scripta Technica, Electr Eng Jpn, 129(1): 74–81, 1999     

Identification of the parameters of the high‐frequency equivalent circuit of PM synchronous motor based on genetic algorithm

This paper presents an identification technique of parameters of a high‐frequency equivalent circuit of permanent magnet synchronous motors (PMSM) driven by a PWM inverter. The high‐frequency oscillatory currents such as leakage current to the motor frame (common‐mode current) and high‐frequency oscillatory line current (normal‐mode current) are generated by switching instants of inverter transistors. The parameters of the high‐frequency equivalent circuit of PMSM which can simulate the oscillating current are identified by means of genetic algorithm. It is shown that the high‐frequency equivalent circuit with identified parameters can generate the oscillating current by some simulation results. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(4): 57–66, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20717     

Improved PMSM model considering flux characteristics for model predictive‐based current control

Model predictive‐based current control, which was proposed in our previous study, offers better current response performance by employing mathematical models of an inverter and a permanent magnet synchronous motor (PMSM). The performance of this kind of approach depends on the predictive model. From a more practical point of view, current behavior in the steady state should be improved. In our previous model predictive‐based current control, the inverter model was refined by taking the dead‐time into consideration. The use of the refined inverter model reduces the current offset in the control. However, the PMSM model was not investigated. This paper proposes a more appropriate PMSM model for model predictive‐based current control in order to improve the current prediction in the steady state. For the purpose, we incorporate more detailed magnetic flux characteristics instead of average characteristics into the improved PMSM model. Specifically, in the improved PMSM model, the inductance of the PMSM is divided into transient and steady‐state parts on the basis of magnetic saturation. The effectiveness of the improved model in the model predictive‐based current control is demonstrated through simulations and experiments. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.