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Volume 49, Issue 5
Displaying 1-11 of 11 articles from this issue
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Paper
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Satoko YAMAKAWA2013 Volume 49 Issue 5 Pages 499-504
Published: 2013
Released on J-STAGE: May 29, 2013
JOURNAL FREE ACCESSThe control method based on the Time-state control form makes it easy to apply the linear control theory into the controller design of chained systems. However, this control method requires the switches of the control inputs. Therefore, we have to discuss the stabilization conditions for the switched system. The sufficient conditions for stabilization have been previously formulated as the condition for the existence of a common Lyapunov function. In this paper, a common Lyapunov function for the switched system is shown explicitly. On the basis of the function, it is clarified that the stabilization conditions for the switched system are equal to those for a basic continuous-time linear system.View full abstractDownload PDF (391K) -
Susumu SHIOZAWA, Tsutomu TANZAWA, Noriaki KIYOHIRO2013 Volume 49 Issue 5 Pages 505-511
Published: 2013
Released on J-STAGE: May 29, 2013
JOURNAL FREE ACCESSAn ultrasonic range finger that an autonomous robot is equipped with is required to find landmarks at a long distance for navigation, and to detect objects at a short distance for obstacle avoidance. Especially, it is very important to detect an obstacle at a very short distance that has the high danger of a collision. But it is difficult to detect the obstacle at a very short distance using conventional long-range ultrasonic range finders. Because the conventional finders receive a directly transmitted wave and a reflected wave by the obstacle at same time. This paper shows the theoretical and experimental results about wide-range ultrasonic range finders that are able to measure both short range and long range.View full abstractDownload PDF (1630K) -
Akimasa SUZUKI, Taketoshi IYOTA2013 Volume 49 Issue 5 Pages 512-520
Published: 2013
Released on J-STAGE: May 29, 2013
JOURNAL FREE ACCESSThe fields of application for indoor positioning have expanded in tandem with advancements in our information-driven society. Compared to other positioning methods such as using radio waves, pseudolites or infrared rays, the systems based on ultrasonic waves have the advantages of low cost and comparatively high accuracy. However, these systems have weak noise resistance. Furthermore, the system takes a longer time to acquire data because they use a time-division multiplexed method with on-off keying (OOK), which becomes more cumbersome as the number of objects to be measured increases. To overcome these drawbacks, we have investigated a a real-time positioning system with spread spectrum (SS) ultrasonic modulation using general-purpose transducers, which is band-limited and utilized in the conventional systems with the OOK. In this paper, the measurement time, measurable range and measurement errors are compared with two modulation types (i.e., conventional OOK and proposed SS modulation) in a situation and an environment using a positioning system. In real-time measurements, improvement of angular dependence and ability for accuracy using SS modulation in conjunction with general-purpose transducers has been not discussed thus far. In the case of measurement for over 3 targets, the system with OOK takes more longer time to obtain a position than with SS, because of CDMA. The result with SS modulation presents the measurement accuracy and measurable range were improved. Therefore, in terms of accuracy, the SS modulation is more effective for indoor positioning than OOK.View full abstractDownload PDF (825K) -
Sadaaki KUNIMATSU, Mitsuaki ISHITOBI, Takao FUJII2013 Volume 49 Issue 5 Pages 521-528
Published: 2013
Released on J-STAGE: May 29, 2013
JOURNAL FREE ACCESSIn this paper, we propose a PID control design method for decentralized control systems from the inverse linear quadratic problem viewpoint by using the structure of controllers obtained by the ILQ(Inverse Linear Quadratic) design method. First, we show an optimal decentralized PID design method for systems with relative degree no more than 2 and block diagonal decoupling matrix. Then, we derive a necessary and sufficient condition for the stability of the closed loop system using our proposed design method of decentralized PID control in the case where the decoupling matrix is not block diagonal. Moreover, we show that a desired transient response with decoupled input/output characteristics can be achieved by our decentralized PID controller. Finally, we illustrate the effectiveness of our proposed method by simulation.View full abstractDownload PDF (673K) -
Tomoki TAKEGAMI, Shun-ichi AZUMA, Toshiharu SUGIE2013 Volume 49 Issue 5 Pages 529-536
Published: 2013
Released on J-STAGE: May 29, 2013
JOURNAL FREE ACCESSThis paper addresses dispersed power networks composed of dispersed power sources and demand points. For the networks, we consider a problem of balancing power supply and demand in a decentralized manner. To solve this, we propose a new control method called multicast control. We first formulate the problem from the viewpoint of the multicast control. Second, we propose a set of multicast controllers and local controllers. Then it is proven that our method asymptotically balances the supply and demand with probability 1. Finally, the effectiveness of the proposed method is demonstrated by numerical simulation.View full abstractDownload PDF (700K) -
Hidekazu KAJIWARA2013 Volume 49 Issue 5 Pages 537-546
Published: 2013
Released on J-STAGE: May 29, 2013
JOURNAL FREE ACCESSIn this paper, we deal with hopping height control problem for a hopping robot by periodic input control. In our previous research, we proposed periodic input control which can control the energy of a system by modulating the amplitude or phase of periodic input, and controlled periodic motion of various systems (such as pendulum or quasi passive walking robot). But periodic motions of these systems which we dealt were sinusoidal, and their motion cycles were almost constant. In this research, we apply periodic input control to a hopping robot whose motion is nonsinusoidal and motion cycle changes significantly depending on hopping height. First, we analyze the timing in which energy of a robot is efficiently excited by periodic input. Next, we design energy control law for hopping height control based on periodic input control. Finally, we show efficiency of our method in experiments.View full abstractDownload PDF (1027K) -
Hirotaka KATSUURA, Yasumasa FUJISAKI2013 Volume 49 Issue 5 Pages 547-552
Published: 2013
Released on J-STAGE: May 29, 2013
JOURNAL FREE ACCESSThis paper deals with distributed control for a class of multi-agent systems composed of a lot of interconnected agents each of which has the first order dynamics. It is assumed that the interconnection can be described as an undirected graph. Then, a necessary and sufficient condition for stability of the closed-loop system is presented in terms of the distributed feedback gains. A sufficient condition for optimality of the system is further presented, where it is shown that the distributed feedback can minimize a quadratic performance index if a gain is selected sufficiently large. The results are also extended to the case that each of the agents has a higher order dynamics.View full abstractDownload PDF (410K) -
Noriko TAKEMURA, Yutaka NAKAMURA, Hiroshi ISHIGURO2013 Volume 49 Issue 5 Pages 553-559
Published: 2013
Released on J-STAGE: May 29, 2013
JOURNAL FREE ACCESSThis paper deals with a multi-agent path planning problem for tracking humans in order to obtain detail information such like human behavior and characteristics. To achieve this, paths of agents is planned based on similarity between the predicted intensity of humans positions and the agents' field of view in the future. The positions of humans are predicted by a k-Nearest Neighbor-based method which allows to predict complicated human movements in a real environment. The number of steps of the planned path is determined according to the consistency between the current prediction and the previous prediction of the future human positions to avoid the path planning using less reliable predictions. We conducted computer simulations and results showed that agents can follow human trajectories observed in a real environment, i.e., concourse of a station by our path planning method.View full abstractDownload PDF (1703K) -
Susumu SHIOZAWA, Tsutomu TANZAWA, Noriaki KIYOHIRO2013 Volume 49 Issue 5 Pages 560-567
Published: 2013
Released on J-STAGE: May 29, 2013
JOURNAL FREE ACCESSThe main purpose of this research is to study and develop a robust sonar system for mobile robots. In order to realize the robust system, the sonar which calculates the cross-correlation is used. This sonar transmits wave coded by the pattern that consist of some narrow pulses, then calculates the cross-correlation between the transmitted signal and the received one. But if the sonar can measure multi-obstacles, it may cause erroneous measurement by the wave reflected from each one. The measurement result will keep to include this error, unless the positional relationship of the obstacles changes. It is difficult to navigate a robot safely. In this paper, the necessary conditions for a transmitting signal of the sonar which always obtain an exact result are proposed. Especially we define the proper form of the transmitting signal for the situation, when the cycle of one is varied.View full abstractDownload PDF (985K) -
Keisuke SHIMA, Yuki HIRAMATSU, Taro SHIBANOKI, Toshio TSUJI2013 Volume 49 Issue 5 Pages 568-575
Published: 2013
Released on J-STAGE: May 29, 2013
JOURNAL FREE ACCESSThis paper proposes a novel dual-arm motion discrimination method combining of the posterior probabilities estimated independently for left and right arm motions. In the proposed method, first, only the posterior probability of each single-arm motion is estimated through learning from measured biological signals using recurrent probabilistic neural networks. The posterior probabilities output from the recurrent probabilistic neural networks are then combined based on motion dependency between arms, making it possible to calculate a joint posterior probability of dual-arm motions. With this method, all the dual-arm motions consisting of each single-arm motion can be discriminated through leaning of single-arm motions only. In the experiments, the proposed method was applied to discrimination of 15 dual-arm motions which consist of three right-arm motions, three left-left arm motions and nine combined dual-arm motions. The results showed that the proposed method could achieve high discrimination performance though leaning of three motions for each arm only (average discrimination rates: 97.49±2.37%). In addition, the possibility of applying the proposed method for a human interface was confirmed through operation experiments for the glovebox system.View full abstractDownload PDF (1342K) -
Randomness-based Approach to the Identification of Fractal Pattern Spanning a Connected Roadway AreaKohji KAMEJIMA2013 Volume 49 Issue 5 Pages 576-585
Published: 2013
Released on J-STAGE: May 29, 2013
JOURNAL FREE ACCESSA stochastic scheme is presented for the identification of a roadway pattern in complex natural scenes. By matching linear scale shift rule with randomly distributed noise images, a version of invariant measure is estimated as the observation of not-yet-identified fractal attractor spanning the roadway area within a generic ground-object structure. The expansion of the invariant measure is restricted by associated breakdown pixels with respect to the linear scale shift rule to design the self-similarity process generating the attractors. The consistency of designed process is verified via invariant feature detection and visualization on the scene images. Proposed method is verified through experimental studies using various types of roadway scene images.View full abstractDownload PDF (3049K)
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