MOESP Approach for Designing a Compensation Input to Linear Unknown SISO Systems

Masuhiro Nitta 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

This paper deals with a compensation method for linear unknown single-input-single-output systems. A mechanical system is often suffered by frictions, so that aging degradation is unavoidable. If the original controller does not bring out a control performance, controller redesign is demanded. However it sometimes degrades the control performance due to variance of the system dynamics. The present paper considers supplying the system with a compensation input satisfying the control performance. Since the transfer function of the system is unknown, we apply a test signal merely one-time and observe its response to get hold of the system characteristics. From this once trial, several pairs of the input-output signals are generated by applying the MOESP approach. Lack of control performance, which appears on the output channels, is compensated by a linear mixture of the generated output signals. By using the mixing coefficient, the compensation input signal is back calculated. Effectiveness of the proposed design method is demonstrated through numerical simulations.

Development of An Intelligent Traffic Light for Reducing Traffic Accidents

Katsuya Matsuzaki,Masuhiro Nitta,Kiyotaka Kato 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

Increase of a traffic accident is recognized as a social problem, hence reduction of he accidents now becomes an urgent task. This paper places a special emphasis on saving pedestrians at blind intersections because the death rate of the pedestrian at the blind intersection is high. To prevent the accident, the paper proposes a notion of the intelligent traffic light. In case that a car and a human are in danger of collision at the intersection, the intelligent traffic light makes the corresponding car stop autonomously by transmitting a warning signal. In order to demonstrate the effectiveness of the proposed traffic system, we substituted a mobile robot for a car. As for the intersection, we installed a radio transmitter with a car approaching sensor and a human detection sensor. As for the mobile robot, we installed a radio receiver and a car control unit. Experimental results indicated that the mobile robot stopped autonomously before the collision and pedestrians would not be injured. But the mobile robot stopped suddenly because the present system did not pay mind to the safety of drivers. This paper thus considers the deceleration curve so that cars stop smoothly. As the result of experiments, the proposed system is applicable enough to the real environment.

Error Analysis on Distribution-based Frequency Estimator

Asami Ishizaka,Masuhiro Nitta,Kiyotaka Kato 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10

Frequency estimation is a useful technology for analyzing oscillatory phenomena. In these days, there is a demand for rapid and highly accurate frequency estimator. Though various frequency estimation methods have been proposed, most of them can not respond to the demand. An algebraic approach is succeeded in achieving the demand but it requires a lot of multiple integrations due to eliminating differential operations. The present paper proposes a frequency estimator of a sinusoidal signal based on the notion of distribution theory. Then the estimator is realized by single integrations. The proposed method relaxes the complexity of multiple integrations into single integrations but the integration is theoretically evaluated over the infinite interval (-∞,∞). The paper firstly reduces the infinite interval to a finite observation interval [0,T] and secondly approximates the integration by a numerical integration. The authors introduce Gaussian function as a test function and perform an error analysis to ensure the accuracy of the frequency estimator. As a result of the error analysis, the suitable conditions of the Gaussian function are clarified. Under the derived conditions, the authors confirmed that the proposed frequency estimator brings out enough the estimation performance.

Pseudo-Real-Time Control of a USB I/O Device under Windows 7

Yuto Watanabe,Akiyoshi Yamada,Masuhiro Nitta,Kiyotaka Kato 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10

Windows-based PCs (Personal Computers) provide a powerful development environment for controller synthesis because it is easy to evaluate the control effect via installed multifunction I/O devices. These I/O devices are expensive due to handling a real-time processing while non-real-time I/O devices are constructed by inexpensive general-purpose ICs (Integrated Circuits.) The aim of this paper is to assemble an inexpensive I/O device with USB interface and to realize a software-based real-time processing. Since Windows does not allow application programs to access such devices, device drivers are required certainly. Device driver should be coded by fulfilling the device drivers’ specification but it is so costly for beginners. The present paper relaxes the development cost by employing the KMDF (Kernel-Mode Driver Framework.) Then the authors develop an application program to command the I/O device periodically. In order to measure the elapsed time precisely, the paper utilizes the RDTSC (Read Time Stamp Counter) instruction. The authors tackle the stabilization problem of the rotational inverted pendulum to evaluate the usefulness of the developed system.

Development of an Adaptive Cruise Control System Using a Monocular Camera

Yuto Baba,Yuto Watanabe,Masuhiro Nitta,Kiyotaka Kato 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10

ACC (Adaptive Cruise Control) system has been attracted much attention because it has a potential to reduce traffic accidents and drivers’ stress. The system maintains a safe inter-vehicular distance and assists driving by keeping traffic lane automatically. Though the conventional ACC system can observe the preceding vehicles using a millimeter wave radar, it fails in following in case of a curved road because of the narrow detection angle. The present paper develops an ACC system to maintain the safe distance by using a monocular camera even though the tracking course is curved. The inter-vehicular distance and the steering angle is calculated by image processing of the acquired video image. By using the processed data, the proposed ACC system properly controls the vehicle velocity and the steering angle. The effectiveness of the proposed system has been evaluated through experiments using mobile robots instead of real cars. The experimental results reveal that the proposed system surely maintains the inter-vehicular distance to the preceding mobile robot.

Survey of a Controller Design Method Based on Experimental Data and a Proposal of Data Conversion Method

Nobuhiko Koyama,Keisuke Kubota,Ichiro Kitamuki,Masuhiro Nitta,Kiyotaka Kato 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

Several methods have been proposed for designing a controller using experimental data directly without identifying a controlled plant. Among them, optimal controller design methods from one-time experimental data, such as Virtual Reference Feedback Tuning (VRFT), Fictitious Reference Iterative Tuning (FRIT), and Noniterative Correlation-based Tuning (NCbT), are especially expected to reduce the time and cost of designing a controller. VRFT and FRIT make a reference signal from experimental data. In contrast, NCbT is a method that removes noise influence by determining parameters for the controller so as not to have the interrelation of the correlation function between a reference signal and noise. However, VRFT and FRIT cannot deal with data that include noises. Although NCbT can be used to design an optimal controller from experimental data with noise, it is limited to cases where there is no interrelation between a reference signal and noise. In this paper, we show a summary of the conventional method and argue about a problem where there is noise. We also propose a data conversion method using linearity after applying spline fitting instead of using experimental data directly. In addition, we discuss the advantages of the conventional method and the proposed method.

Systematization of Flight Instruction and Control for Autonomous Helicopter

Yuto Matsuzawa,Yuta Tozaki,Yuji Kameda,Masuhiro Nitta,Kiyotaka Kato 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

A radio-controlled (RC) helicopter can be used in the fields of aerial crop dusting, aerial photography, and many more. However, controlling a RC helicopter needs advanced techniques. Therefore, a flight instruction system that provides guidance on how to fly a RC helicopter is required. Examples that give flight instructions to an autonomous helicopter have been reported, but those had been designed and developed individually. To extend the application of an autonomous helicopter to an indoor environment, such as a factory, the systematization and standardization of flight instructions are required. From this, each flight instruction generative system that has been prepared for individual use can generate common flight instructions. Likewise, an autonomous helicopter can operate based on the common flight instructions designed for various purposes. In this paper, we have defined flight instruction codes based on the Numerical Control (NC) code system that has been used for a machine tool. In addition, we have systematized instruction codes. To verify such a system, an autonomous flight control system has been developed for indoor use and a flight experiment has been performed. As a result, we were able to confirm that the helicopter flew by executing the flight instructions that have been read.

Comparison of VRFT, NCbT and VRFT with Spline Fitting

Keisuke Kubota,Nobuhiko Koyama,Ichiro Kitamuki,Masuhiro Nitta,Kiyotaka Kato 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

In order to design an optimal controller for a feedback system with an unknown plant, it is a common way to identify the plant by performing plural experiments. On the contrary, certain methods used to design a controller using the data from one-time experiments have been proposed. Such methods include Virtual Reference Feedback Tuning (VRFT) and Noniterative Correlation-based Tuning (NCbT). These methods are expected to reduce the design cost. However, VRFT cannot be used to design an optimal controller from a data with noise and NCbT is limited in that there is no correlation of a reference signal with noise. An actual plant often has higher harmonics of an input signal as noise. Such noises are correlated with a reference signal. Therefore, a controller design must be able to deal with various kinds of noises. This paper proposes a method of applying spline fitting to VRFT. To verify the effectiveness of this technique, we compared the response of the proposed method with that of VRFT and NCbT on a simulator. Then, we designed each controller using VRFT, NCbT, and VRFT+SF, respectively, by providing white Gaussian noise and periodic noise. As a result, this paper shows that the proposed method surpasses the original VRFT and NCbT based on overall experimental results.