Hideo Tsukune

Study of deformation and insertion tasks of a flexible wire

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 insertion task of a flexible wire into a hole by using visual tracking observed by stereo vision

Measuring the force on a flexible wire is difficult by using force/torque sensors when the flexural rigidity of the wire is small because the wire buckles and the force on the wire is smaller than the force that can be measured by a force/torque sensor. This paper presents a method of calculating the force on a wire from its shape observed by stereo vision. We propose a method of inserting the wire into a hole in a wall by using the estimated force. Three experiments have been successfully carried out.

Delivery by hand between human and robot based on fingertip force-torque information

Presents a delivery by hand between a multifingered hand and a human based on force-torque sensing. Of all cooperated tasks between humans and robots, the most important and basic factor is delivery of objects by hand. To insure positive delivery, the robot should open its hand only after making sure that the object has been received by the human. The human releases the object only after confirming that the robot can actually grasp the object stably. The features of the hand-delivery system introduced in the paper include that (1) the robot recognizes successful transfer of the object to a human when the human changes the grasping condition, (2) the human guides the position and orientation of the grasped object to a stable grasp, and (3) the robot, in response to the above guide, regrasps the object to realize a stable grasping condition. The paper introduces evaluation for stable grasp, and presents a new technique for sensor based regrasp manipulation and delivery by hand between a human and robot based on force-torque sensing which reflects the result of stability evaluation. Finally, experimental results are shown to demonstrate the effectiveness of the proposed scheme.

Study of insertion task of a flexible beam into a hole

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.

A telerobotics system for maintenance tasks integrating planning functions based on manipulation skills

The paper describes an integrated teleoperation system for maintenance tasks with planning functions based on manipulation skills. We embed planning functions into a telerobotics system to make the system more flexible and robust. A motion teaching system based on contact state transition, a geometric modeling system using teaching trees, and a task execution system based on manipulation skills are integrated. The design concept of the system and essential technologies are described. An experimental task is explained to demonstrate the efficiency of the telerobotics system.

Fine motion strategy in three-dimensional space using skill-based backprojection

The motion of manipulation in a task can be decomposed into several motion primitives called “skills.” Skill-based motion planning gives the possibility of performing tasks as skillfully as human beings do. On the other hand, the backprojection method performed in configuration space has often been used in fine-motion planning. This paper describes fine-motion planning in three-dimensional space using skill-based backprojection. Now that skill-based planning in three-dimensional space has been developed, it becomes possible to plan manipulation motions like the behavior of the human hand.

Surface-based geometric modeling of general objects using teaching trees

Geometric modeling of the environment is important in robot motion planning. Generally, shapes can be stored in a database, so the elements that need to be decided are positions and orientations. In this paper surface-based geometric modeling using a teaching tree is proposed. In this modeling method, combinations of surfaces are considered in order to decide the positions and orientations of the object. The combinations are represented by a depth-first tree, which makes it easy for the operator to select one combination out of several. This method is effective not only in the case when perfect data can be obtained but also when conditions for measurement of three-dimensional data are unfavorable which often is the case in the environment of a working robot.

Monitoring and co-ordinating behaviours for purposive robot navigation

This paper presents a new scheme of purposive navigation for mobile agents. The new scheme is robust, qualitative and provides a mechanism for combining mapping, planning and mission execution for a mobile agent into a single data structure called the purposive map (PM). The agent can navigate using incomplete and approximate information stored the PM. We present a novel approach to perform obstacle avoidance for a behaviour based robot. Our approach is based on using a physically grounded search while monitoring and co-ordinating behaviours. The physically grounded search exploits stagnation points (local minima) to guide the search for the shortest path to a target. This scheme enables our robot to escape from dead-end situations and allows it to deduce that a target location is unreachable. Simulation results are presented.<<ETX>>

Fine motion strategy for skill-based manipulation

Generally, a manipulator task can be divided into several motion primitives called “skills.” Skill-based motion planning is an effective way to execute a complicated task. When planning an assembly process, a technique of fine motion planning such as the backprojection method in configuration space is often used. This paper describes fine motion planning using a skill library, which consists of a pattern of trajectories of skill motions in configuration space. This method gives the initial position and orientation from which the object can reach the goal in skill-based manipulation.

Surface-based geometric modeling using task-oriented teaching trees

In robot motion planning, geometric modeling plays an important role. Generally the shapes of objects such as factory products can be stored in a computer software database, so the elements that need to be decided are positions and orientations. In this paper surface-based geometric modeling using a task-oriented teaching tree is proposed. In this modeling, combinations of surfaces for deciding positions and orientations of objects are represented in a depth-first tree based on a kind of task. Therefore, the operator can choose easily one combination out of several compared with the obtained data. Moreover a geometric model of the object suited to the manipulation task can be obtained.