Trajectory tracking control of mobile robot by time‐based spline approach

A mobile robot must move without unacceptable rapid motion. To address this issue, we propose a preview controller using the time‐based spline approach. With this approach, it is also important to plan an adequate trajectory. Here an approach to trajectory planning which has the trajectory determination strategy via a virtual manipulator is proposed. Numerical and experimental results are shown to confirm the proposed algorithm. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(4): 65–71, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10349     

Autonomous mobile robot based on behavior decision skill and control skill of the operator

This paper introduces a human skill base control algorithm using artificial neural networks and fuzzy reasoning for an autonomous mobile robot. Neural networks are used to select a suitable motion control pattern in actual environments. The back propagation algorithm adjusts the weights of the neural networks so that the selected motion control pattern corresponds to the action, which is obtained by the operator's behavior decision skill. To realize the selected motion control pattern, the orientation angle and the speed of the mobile robot are determined by fuzzy reasoning in which fuzzy rules are also automatically tuned so as to simulate the operator's control skill. We have implemented and tested the proposed control algorithm on an autonomous mobile robot and some experimental results demonstrate the effectiveness of the proposed control algorithm for the autonomous mobile robot. © 2000 Scripta Technica, Electr Eng Jpn, 131(2): 30–39, 2000     

New sensorless vector control methods based on a new minimum‐order flux state observer in the “D‐module” for permanent magnet synchronous motors

This paper proposes new sensorless vector control methods that can be applied to both salient‐pole and non‐salient‐pole permanent magnet synchronous motors (PMSM). The proposed method estimates the phase of rotor flux by the “D‐module observer,” which is newly developed for sensorless vector controls of PMSM. The “D‐module observer” has the following attractive features. (1) It is a new state observer requiring no additional approximation to the motor mathematical model. (2) It is a minimum‐order state observer. (3) Observer gain guaranteeing proper estimation in a wide operating range except for singular zero‐speed can be a simple constant, and can be easily designed. (4) It utilizes motor parameters in the simplest manner. (5) Its structure is very simple and is realized at the minimum computing cost. (6) It can be applied to both salient‐pole and non‐salient‐pole PMSM. (7) It can be realized in both rotor and stator reference frames. Detailed designs and analyses for the “D‐module observer” and “D‐module observer”‐based sensorless vector control systems in both rotor and stator reference frames are given. Their validity and usefulness are examined and confirmed through extensive experiments. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(2): 46–62, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20046     

Adaptive control of electrically-driven nonholonomic wheeled mobile robots: Taylor series-based approach with guaranteed asymptotic stability

Taking advantage of an adaptive Taylor series approximator, this research seeks to address a two-loop robust controller for electrically-driven differential drive wheeled mobile robots. A fictitious current signal is designed in the outer loop such that the good tracking performance as well as the asymptotic stability of system will be achieved. Also, the error of currents will be minimized by an actual control input in the inner loop. For both inner/outer loops, uncertain nonlinear functions can be approximated by adaptive Taylor series systems. To validate the proposed control algorithm, numerous simulations have been carried out with two different desired trajectories and multiple initial conditions. Also, the proposed controller is compared with a recent well-designed robust adaptive fuzzy controller. In addition, to simplify the procedure of mathematical modelling of a wheeled mobile robot, the “Simscape Multibody” environment of “MATLAB” is used for 3D simulations.     

Guiding a mobile robot with cellular neural networks

We show how cellular neural networks (CNNs) are capable of providing the necessary signal processing needed for visual navigation of an autonomous mobile robot. In this way, even complex feature detection and object recognition can be obtained in real time by analogue hardware, making fully autonomous real‐time operation feasible. An autonomous robot was first simulated and then implemented by simulating the CNN with a DSP. The robot is capable of navigating in a maze following lines painted on the floor. Images are processed entirely by a CNN‐based algorithm, and navigation is controlled by a fuzzy‐rule‐based algorithm. Copyright © 2002 John Wiley & Sons, Ltd.     

Applying data mining to a field quality watchdog task

This article describes a watchdog program that discovers “meaningful” repair cases from a field service database. “Meaningful” cases are those judged worth probing further to prevent an epidemic of quality problems. Our system has employed the apriori algorithm, a data mining technique that efficiently performs the basket analysis. Our system proves that this data mining technique is not only useful in knowledge discovery but is also capable of performing the database watchdog task. The apriori algorithm automatically generates frequent itemsets from a large set of records. A frequent itemset is an arbitrary combination of values that appear more often than a threshold “minimum support.” The algorithm often generates too many itemsets for quality engineers to review carefully in their daily work. Many itemsets do not provide sufficient information to investigate further. Hence, in order not to generate these valueless itemsets, the apriori algorithm is modified in two ways. One way is “basket analysis on objective and explanatory attributes” and the other is “itemset reduction.” The advantage of our method is demonstrated with some experimental results. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(2): 18–25, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10034     

基于目标向量的非全向测距机器人路径规划

设计了以DSP TMS320F28335为核心的非全向测距室内移动机器人,通过DSP控制超声波传感器阵列来获取障碍物信息。并且基于此机器人系统,提出一种基于目标向量的路径规划算法,该算法不仅融合了TangentBug算法机器人行为简单、全局收敛的特点,又解决了TangentBug算法仅能应用于全向测距质点机器人的问题。实验结果表明,在该算法下,机器人能够在多种类、多障碍的位置环境下有效避开障碍物,到达定目标点。     

Development of an Autonomous Mobile Robot with Several Sensors using Neuro‐Fuzzy Control Based on Server/Client Model

The purpose of this paper is to detail the development of an autonomous mobile robot and a control support system. The robot has five infrared sensors and three ultrasonic sensors to enable it to follow a ‘ guide person’ with an infrared ray transmitter. The robot will follow the infrared rays emitted by a transmitter with the guide person, and move to the destination. The control system has been developed by the network technology based on server/client model. The advanced control strategy for the autonomous mobile robot is carried out with a high‐speed host server computer connected through the TCP/IP network. Therefore, it is enough for the CPU of the robot to be of low speed. In this paper, the autonomous mobile robot system and the control system using the server/client model are described. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Characteristics of behavior of robots with emotion model

A cooperative multirobot system has much dominance over a single‐robot system. It is able to adapt to various circumstances and has flexibility for variation of tasks. However, it still has problems of controlling each robot, although methods for control of a multirobot system have been studied. Recently, emotion and sensitivity of the robots have been widely studied. In this study, a human emotion model based on psychological interaction was adapted to a multirobot system to achieve methods for organization of multiple robots. The characteristics of behavior of multirobot systems achieved through computer simulation were analyzed. As a result, very complex and interesting behavior emerged even though it is of rather simple configuration. And it has flexibility in various circumstances. Additional experiments with actual robots will be conducted based on the emotion model. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(4): 32–38, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20167     

Generation of adaptive gait patterns for quadruped robot with CPG network including motor dynamic model

This paper describes the generation of adaptive gait patterns using new Central Pattern Generators (CPGs) including motor dynamic models for a quadruped robot under various environments. The CPGs act as the flexible oscillators of the joints and adjust joint angles to required values. The CPGs are interconnected with each other and sets of their coupling parameters are adjusted by a genetic algorithm so that the quadruped robot can realize stable and adequate gait patterns. Generation of gait patterns results in the formation of the CPG networks suitable for the formation of not only a straight walking pattern but also of rotating gait patterns. Experimental results demonstrate that the proposed CPG networks are effective for the automatic adjustment of the adaptive gait patterns for the tested quadruped robot under various environments. Furthermore, the target tracking control based on image processing is achieved by combining the general gait patterns. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(1): 35–43, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20225     

Simultaneous design of the sensory morphology and controller of mobile robots

This paper proposes a method for automatic design of the sensory morphology of a mobile robot. The proposed method employs two types of adaptations, ontogenetic and phylogenetic, to optimize the sensory morphology of the robot. In ontogenetic adaptation, reinforcement learning searches for the optimal policy, which is highly dependent on the sensory morphology. In phylogenetic adaptation, a genetic algorithm is used to select morphologies with which the robot can learn tasks faster. Our proposed method was applied to the design of the sensory morphology of a line‐following robot. We performed simulation experiments to compare the design solution with a hand‐coded robot. The results of the experiments revealed that our robot outperformed the hand‐coded robot in terms of the following accuracy and learning speed, although our robot had fewer sensors than the hand‐coded one. We also built a physical robot using the design solution. The experimental results revealed that this physical robot used its morphology effectively and outperformed the hand‐coded robot. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 172(1): 48–57, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20965     

Position and altitude tracking control for toe support phase of biped walking robot

No paper has been published on the active use of the foot toe of biped walking robots. In other words, the sole of the supporting leg is usually assumed to completely contact the ground. To maintain this condition, the robot walking has a restriction such as the maximum walking speed limitation. If the point contact of the toe to the ground through walking is available, a variety of walking can be realized. In this paper, a new control method for biped robots, in which the contact of the sole to the ground becomes a point contact, is proposed. The COM (Center of Mass) and swing leg can track the desired path and each heel joint angle can be controlled by the proposed controller while a biped walking robot is following a forward falling. Therefore, the motion of the body does not need to be limited to quiet motion. The proposed method is verified by simulation and experimental results with “Ken,” a six‐joint DOF biped robot. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(1): 72–79, 2006; Published online in Wiley InterScience ( http://www.interscience.wiley.com ). DOI 10.1002/eej.20094     

A control method based on modal transformation for biped robots to climb unknown steps

This paper proposes a control method based on a modal transformation for biped robots to climb unknown steps. The method is able to control the foot position of the biped robot and the ground reaction force acting in the vertical direction when the biped robot climbs unknown steps in a double support phase. The effectiveness of the proposed method is confirmed by the results of simulations and experiments. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 181(3): 59‐69, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21265     

Neural network approximation to nonlinear dynamics by velocity error backpropagation

This paper presents a new type of recurrent neural network (RNN) and its learning algorithm for nonlinear dynamics, called “Velocity‐Error Backpropagation (VEBP).” In VEBP, learning is performed in two steps: (a) The velocity vector field of reference trajectories is approximated by a feedforward neural network (NN) with biconnection layers by backpropagating the velocity errors directly. (b) The RNN is constructed by adding integrators and output feedback loops to the trained feedforward NN. VEBP has some advantages over “backpropagation through time (BPTT),” the conventional learning method for RNNs. The effectiveness of the presented RNN and its learning algorithm is demonstrated by simulation results for some examples of nonlinear dynamics. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(2): 26–35, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10011     

基于自适应模糊滑模控制的机器人轨迹跟踪算法

针对控制参数的不确定性以及存在未知外部扰动情况下移动机器人的轨迹跟踪问题,提出一种基于光滑非线性饱和函数的自适应模糊滑模轨迹跟踪控制算法。通过建立不确定非线性移动机器人运动控制模型,利用自适应模糊逻辑系统构建自适应模糊滑模控制器。为了增强轨迹跟踪控制算法对随机不确定外部扰动适应能力的同时削弱滑模控制算法中的输入抖振现象,利用有界输入有界输出(BIBO)稳定的方法,通过带有自适应调节算法的模糊系统对滑模控制律中非线性函数项进行自适应逼近,并设计了模糊系统中可调参数的自适应控制律,保证了控制系统的稳定与收敛。实验结果表明,所设计的控制器对系统参数不确定性和外界扰动均具有较强的轨迹跟踪性能和鲁棒性。与传统的滑模控制算法相比,该算法不仅能有效减小输入抖振而且轨迹跟踪控制精度提高了18.89%。     

Novel straight and circular road driving control of electric power assisted wheelchair based on fuzzy algorithm

This paper describes a novel straight and circular road driving control scheme for electric power‐assisted wheelchairs. “Electric power‐assisted wheelchair” which assists the driving force by electric motors is expected to be widely used as a mobility support system for elderly people and disabled people, however, the performance of straight and circular road driving must be further improved because the two wheels drive independently. This paper proposes a novel driving control scheme based on fuzzy algorithm to realize stable and reliable driving on straight and circular roads. The suitable assisted torque of the right and left wheels is determined by fuzzy algorithm based on the posture angular velocity of the wheelchair and the human input torque proportion of the right and left wheels. Some experiments on the practical roads show the effectiveness of the proposed control system. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(1): 36–44, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20846     

基于Backstepping时变反馈和PID控制的移动机器人实时轨迹跟踪控制

根据机器人的运动学模型，采用分层控制的思想将移动机器人的轨迹跟踪控制分为两部分：轨迹跟踪控制器和机器人速度PID控制器。基于Backstepping时变状态反馈方法和Lyapunov理论，引入具有双曲正切特性的虚拟反馈量，提出一种移动机器人全局轨迹跟踪算法：采用PID速度控制器以满足机器人驱动电机实时调速要求。考虑到机器人的动力学约束，引入受限策略以保证其运动平滑。在基于DSP的两轮驱动移动机器人上对算法进行了实时轨迹跟踪试验，取得了满意的控制效果。     

Deployment control of wireless multihop‐relay mobile robots based on voronoi partition

This paper describes a new method for the deployment of wireless relay nodes. When using rescue robots in a building or underground city, radio signals are attenuated significantly, and therefore, multihop extension involving wireless communication relays is required. The goal of this research is to deploy wireless relay nodes to maintain connectivity between the base station and the leader robot that explores around the front line. To move the relay robot autonomously, a distributed algorithm is required. The proposed method is suitable when it is applied for wireless relay purposes. In this method, a virtual force drives a node to the centroid of Voronoi neighbors so that the connectivity of wireless communication is maintained. The proposed method is evaluated by conducting numerical simulations and experiments. In the simulation, one or two leader robots are assumed. In the experiment, a mobile robot equipped with omni‐wheels is used. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(4): 42–51, 2013; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22413     

Hebbian learning rule restraining catastrophic forgetting in pulse neural network

In this paper, a Hebbian learning rule restraining “catastrophic forgetting” is proposed on a pulsed neural network (PNN) with leaky integrate‐and‐fire neurons. The strong point of this learning rule is that a learning of new pattern does not destroy past ones, and that an efficient use of synapses is enabled. First, in order to consider the function of the learning rule, a fundamental experiment is carried out. Next, to compare the performance between the proposed learning rule and conventional ones on the application, simulation experiments are examined using autonomous behavior robots which are forced to learn concurrently two different environments. The results of the experiments show that the proposed learning rule clearly restrains “catastrophic forgetting” and enables working of more efficient than conventional PNN learning. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(3): 50–60, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10343     

Reliability evaluation considering customized power quality supply in FRIENDS

The authors have proposed a Flexible, Reliable and Intelligent ENergy Delivery System (called “FRIENDS”), which is a new concept for a future power distribution system. One of the most important feature of FRIENDS is to be able to manage the reliability of power supply. In this paper, FRIENDS and a conventional distribution system are compared quantitatively as to supply reliability and cost through time sequential Monte Carlo simulation. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(4): 25–35, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20053