In assembly system, one of the primary factors of the bandwidth limitation is the flexibility of the base on which a tool or manipulator is mounted. We have shown that there exists a set of configurations in which high robustness and controllability are obtained even with high-gain error feedback of the end effector. Based on the positive realness of the transfer matrix, we have defined ‘Robust arm configuration’ which is a special configuration where the system is passive. We have also proposed a measure which indicates the distance from robust arm configuration. In this paper, we propose a mode shape compensator which improves the robustness of the arm configuration where the robustness is not high enough. The compensator consists of a constant gain matrix and acceleration feed back of each joint. The structure is simple and easy to use. We also show the method of designing the mode shaping matrix. The validity is confirmed by a numerical example. A high bandwidth positioning is realized with obtained compensator.
It is expected that robots play an important role coxisting with human beings in the field of medical application, welfare one and so on.In such a case, the robot should not effect psychological threat to the human.This paper describe the method for the previous announcement in moving of the robotic arm to reduce human _??_ s threat gainst the robot.The notice device is performed by lighting several LED markers attached at the endpoint of the robotic arm.The effectiveness of the proposed method is evaluated as follows.First, the timing against the previous announcement in moving of the robtic arm was investigated by psychological evaluation. As a result, it is found that the timing has an optimal value and it is from 1.0 to 1.5 seconds.Second, the relation between psychological evaluation value and the changing point of velocity was investigated.As a result, it is verified that the psychological threat of the human can be controlled by giving the previous notice of the change of motion of the robotic arm.
New digital-mockup technology to cut back the development cost and time for a new product is required, which can perform check of the validity of parts shape and also examine an assembly procedure on a screen. In this paper, a collision-detection algorithm and an object-operation algorithm are proposed, which are required to operate a non-convex shape object in a haptic virtual environment. In the collision detection algorithm, point cloud is used to represent the shape of an operated object by a 6-DOF haptic device, triangular polyhedron is used to represent the other objects. The collision detection algorithm finds pairs of point and triangle with nearest distance between them. In the object operation algorithm, the motion of the operated object is decided from two forces, one is operating force by the haptic device and the other is impulsive force generated at the time of contact. The validity of these algorithms were confirmed by the experiments using the non-convex shape objects designed by 3-D CAD system.
In the paper, special attention is paid to human errors in a human/robot coexistence system for their collaborative tasks in which the robot partially assisted the power of a human operator. The possibility of applying maintainability concept for maintainance of tasks is explored for human error detection and recovery. After setting a problem of inferring a goal intended to reach by the operator, we propose to provide the robot with a capability of inferring an operator-intended path pattern from a halfway sequence of detected trajectory data using HMM whose algorithm is modified for our target. We verify, through experiments of the robot operation for rapid parts conveyance tasks, that efficient human error detection and recovery can be achieved with the aid of the proposed operator-intended path pattern inference scheme and demonstrate its usefulness. Interviews from the subjects in the experiments reveal that all human error types of slips, lapses, and mistakes are included in which our proposal is effective against human lapses and mistakes.
The possibility to utilize 3D information for engineering purposes is incleasing by the recent development of various 3D sensors. But because optical 3D sensors such as laser range finder use light, which moves straight, the measurement area is limited to the front face of the object and the back side is not measurable. To adapt such unmeasurable area, we need a system that memorizes shapes of objects that have often encountered and superimposes them to scene. To realize such kind of system, an appropriate 3D shape representation, which is 1) able to compare partial and entire shape information and to detect corresponding areas 2) working as quick as possible for real-time tasks, is needed. We propose a novel representation framework to describe and compare 3D objects: Internal Radiatedlight Projection (IRP) - projection of local shape informations of an object on a sphere by imaginary rays from the proposing reference point “kernel”-. In order to describe local shape information, Harmonic Contour Analysis (HCA), and to arrange them properly the shape matrix are used respectively in IRP framework. The characteristics of IRP are: (1) simple representation for complicated 3D shape information; (2) use of local shape characteristics and their adjacency informations; and moreover, by using shape matrix, (3) simple matching procedure considering the effect of gravity and stable poses for objects. By IRP representation, we can categorize objects in known classes and estimate their positions and attitudes. In this paper, the basic concept of IRP, a reliable way to obtain reference point “kernel”, representation of local 3D shape by HCA, and shape matrix based comparison and categorization of objects are explained. Experiments of object recognition for both virtual and real objects are shown to demonstrate its efficiency and feasibility.
A hybrid drive parallel arm with 3 cylinders and 4 wires has been developed for manipulating heavy materials. This paper discusses the estimation of various data of handling object and external force at handling object using only 4 tension sensor output. The developed hybrid arm is a kind of actuation-redundant mechanism and its internal force can be freely controlled. The proposed algorithm will compensate the internal force and estimate various data by exploiting 4 tension sensor output obtained at several arm positions. The paper introduces the hybrid parallel arm and the tension sensor. Then, a control method of the arm using tension information is described. Finally, an estimation method of gravity center and mass of an unknown handling object, and external force estimation are explained. The basic experiments using the prototype arm are presented with effective reasonable results.
This paper discusses coupling of two 2R open kinematic chains with their second joints unactuated in the horizontal plane. When they are not coupled, they can operate as independent underactutaed manipulators and when they are coupled, they can operate as a single 5R parallel manipulator which has the same number of actuators as its degrees of freedom. In the horizontal plane, they cannot make use of gravity for motion generation. In parallel mechanisms, uncertainty and stationary-uncertainty singularities exist in general. If the two open kinematic chains form such a singular configuration when they touch with each other, they can exert force with each other and therefore can be coupled easily. In addition, at a stationary-uncertainty singular configuration, they can escape from it after they are coupled simply by controlling their joint velocities. We propose a coupling mechanism without actuation, which can be a smooth free joint when coupling is achieved. The two open kinematic chains can reach an uncertainty singular configuration if they touch with each other at certain initial configurations. This paper analyzes this motion and show such initial configurations. We experimentally verify the proposed coupling.
Minimally Invasive Direct Coronary Artery Bypass (MIDCAB) requires surgeons the precision of hand skill and the mental concentration, since it needs to work on beating hearts. We propose a surgical robot system that compensates motions of organs during operations. The motion canceling robot system consists of three technologies; visual stabilization, motion stabilization and master-slave control. The visual stabilization provides the surgeon with the image of stabilized target point on the video monitor. The surgeon operates the master robot referring to the stabilized image. The motion stabilization, on the other hand, controls the slave robot being synchronized with the heart beat, which has the function of the master-slave control. In this paper, we verify the effectiveness of the prototype system by in-vivo experiment.