The theory and the applications of artificial neural networks, especially in a control field, are described. Recurrent networks and feedforward networks are discussed. Application to pattern recognition, information processing, design, planning, diagnosis, and control are examined. Hybrid systems using the neural networks, fuzzy sets, and artificial intelligence (AI) technologies are surveyed. >

Theory and applications of neural networks for industrial control systems

The wide interest of research and industry in the human–robot interaction HRI related topics is proportional to the increased productivity and flexibility of the production lines, as it combines human and robot capabilities. This paper presents a review of recent research and progress on HRI, related to task planning/coordination and programming with emphasis on the manufacturing/production environment. Human–robot task allocation and scheduling, metrics for HRI, as well as the social aspects are reviewed. The role of digital human modelling systems for human–robot task planning related issues is also discussed. The process of learning by demonstration as well as the instructive systems is reviewed, focussing mainly on programming through visual guidance and imitation, voice commands and haptic interaction. The aspect of physical HRI as well as the safety related issues are also discussed. Additionally, a survey on multimodal communication frameworks is presented. Challenges encountered and directions for future research are discussed.

Human–robot interaction review and challenges on task planning and programming

This paper presents a new adaptive controller for image-based dynamic control of a robot manipulator using a fixed camera whose intrinsic and extrinsic parameters are not known. To map the visual signals onto the joints of the robot manipulator, this paper proposes a depth-independent interaction matrix, which differs from the traditional interaction matrix in that it does not depend on the depths of the feature points. Using the depth-independent interaction matrix makes the unknown camera parameters appear linearly in the closed-loop dynamics so that a new algorithm is developed to estimate their values on-line. This adaptive algorithm combines the Slotine-Li method with on-line minimization of the errors between the real and estimated projections of the feature points on the image plane. Based on the nonlinear robot dynamics, we prove asymptotic convergence of the image errors to zero by the Lyapunov theory. Experiments have been conducted to verify the performance of the proposed controller. The results demonstrated good convergence of the image errors

Uncalibrated visual servoing of robots using a depth-independent interaction matrix

An adaptive motion/force controller is developed for unilateral or bilateral teleoperation systems. The method can be applied in both position and rate control modes, with arbitrary motion or force scaling. No acceleration measurements are required. Nonlinear rigid-body dynamics of the master and the slave robots are considered. A model of the flexible or rigid environment is incorporated into the dynamics of the slave, while a model of the human operator is incorporated into the dynamics of the master. The master and the slave are subject to independent adaptive motion/force controllers that assume parameter uncertainty bounds. Each parameter is independently updated within its known lower and upper bounds. The states of the master (slave) are sent to the slave (master) as motion/force tracking commands instead of control actions (efforts and/or flows). Under the modeling assumptions for the human operator and the environment, the proposed teleoperation control scheme is L/sub 2/ and L/sub /spl infin// stable in both free motion and flexible or rigid contact motion and is robust against time delays. The controlled master-slave system behaves essentially as a linearly damped free-floating mass. If the parameter estimates converge, the environment impedance and the impedance transmitted to the master differ only by a control-parameter dependent mass/damper term. Asymptotic motion (velocity/position) tracking and force tracking with zero steady-state error are achieved. Experimental results are presented in support of the analysis.

Stability guaranteed teleoperation: an adaptive motion/force control approach

Robots have become significantly more powerful and intelligent over the last decade, and are moving in to more service oriented roles. As a result robots will more often be used by people with minimal technical skills and so there is a need for easier to use and more flexible programming systems. This paper reviews the current state of the art in robot programming systems. A distinction is made between manual and automatic programming systems. Manual systems require the user/programmer to create the robot program directly, by hand, while automatic systems generate a robot program as a result of interaction between the robot and the human; there are a variety of methods including learning, programming by demonstration and instructive systems.

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A Survey of Robot Programming Systems

Insertion of a flexible wire into a hole is a difficult task because the wire has a tendency to buckle under external forces. Moreover, the plastic deformation occurs on a flexible wire when the force acting on the wire is big. In this paper, we propose a method of inserting a flexible wire whereby a force acts on the wire and the shape of the wire is observed by stereo vision. A strategy to transform the deformed wire to the straight one and to insert the wire into a hole is presented. Finally, some experimental results are shown.

Study of deformation and insertion tasks of a flexible wire

Methods to detect the contact state of an end-effector and the environment by force sensing, which is a useful technique for very small motions, are described. One method estimates the position of the contact point, while another method detects the transition of the contact state. These methods are implemented on an edge-mating task. The contact position is estimated with two sets of observed relative force and moment, and the forces to be applied for the estimation are determined based on the singular value decomposition technique. Transition detection is achieved by monitoring the relation between observed force and moment. Experiments demonstrate the effectiveness of this technique, which is robust against force noise caused by friction and the characteristics of the manipulator control. >

Methods to detect contact state by force sensing in an edge mating task

Discusses the task of inserting a flexible beam into a hole when the friction force is large enough to buckle the beam. The authors analyze the buckle shape of the beam and external forces and moments loaded on the beam during the insertion task, under the condition that the potential energy of the beam is minimized. Then, the authors find that the buckling shape has two buckling modes and the modes are changed by varying the orientation angle of the end of the beam. The authors propose a method of performing the insertion task, based on an analysis of the relation between the external forces and friction coefficient. Finally, the authors present experimental results which confirm their analysis.

Study of insertion task of a flexible beam into a hole

This paper presents a general approach of model-based adaptive hybrid control for holonomically constrained manipulators. Both time-invariant and time-variant constraints are dealt with. This controller works on the basis of an orthogonalization principle of trajectory and force errors in the joint space and intrinsic characters of the manipulator dynamics. Its asymptotic stability is guaranteed by a passivity-based Lyapunov function. A distributed cooperation controller based on the same concept for multiple manipulators is also presented. Further, we show a parallel implementation of this controller using transputers on a six DOF direct drive manipulator, and some experimental results.

Adaptive control for holonomically constrained robots: time-invariant and time-variant cases

We discuss grasp stability under gravity where each finger makes soft-finger contact with an object. By clustering polygon models of a finger and an object, the contact area between a finger and an object is obtained as the common area between an object cluster and a finger cluster. Then, by assuming the Winkler elastic foundation, the pressure distribution within the contact area is obtained. By using this pressure distribution, we show that we can judge grasp stability under soft-finger contact. We further consider defining a quality measure of a soft-finger grasp by assuming that although the gravitational force is applied to an object, the direction of gravity is unknown. To demonstrate the effectiveness of the proposed approach, we show several numerical examples. I. INTRODUCTION Grasp stability is widely used as an index for evaluating the grasping posture of multifingered hands. If grasp stability is satisfied, we can guarantee that the grasped object can resist an external disturbance from any direction. In this study, we focus on grasp stability for general multifingered hands, wherein a finger makes soft-finger contact (SFC) with an object. We consider solving formulating grasp stability under SFC by explicitly using the pressure distribution acting in the contact area between finger and object. In addition to this problem, we obtain the quality measure by taking the effect of gravity into consideration. Many industrial manipulators are equipped with two- fingered parallel grippers at the tip. For such manipulators, it is well known that, if a finger contacts an object under the point contact with friction (PCwF), three fingers are needed to ensure grasp stability. However, many two-fingered grippers have a flexible sheet attached to the finger surface. When a finger contacts an object, the flexible sheet deforms, thereby generating torsional friction at the contact area. Because of this torsional friction, grasp stability can be satisfied even if a hand has only two fingers. This contact style is called SFC. Here, because the amount of torsional friction depends on the area of contact, grasp stability also depends on the area of contact. Although the area of contact depends on the object shape and the flexibility of the sheet, there has been no research on grasp stability under SFC in which the effect of object shape and flexibility of the sheet has been considered. On the other hand, we determine grasp stability under SFC by explicitly considering this effect. We

Kosei Kitagaki

Papers

Study of deformation and insertion tasks of a flexible wire

Methods to detect contact state by force sensing in an edge mating task

Study of insertion task of a flexible beam into a hole

Adaptive control for holonomically constrained robots: time-invariant and time-variant cases

Stability of Soft-Finger Grasp under Gravity