Proposes a magnetic measurement principle to develop a balance sensor. Basically, the sensor is composed of a spherical vessel sealing a certain amount of liquid, a mushroom-shaped float and a permanent magnet. The circular plated magnet is fixed on the root of the float stem. As the liquid moves in the vessel, the float changes the position of the magnet. And the Hall effect devices located around the vessel sense the change of balance with the aid of a signal processor. The density of the Hall effect devices and the algorithm for determining the direction of the resultant acceleration are considered. Also, the results of experiments for magnet's position and the angle of balance are shown. The proposed method is effective in detecting all directions of the resultant acceleration of motion and gravity with uniform resolution, since the sensor has no rotation axes.

Firm and stable 3-D grips have been achieved for articulated multifinger hands, easing object handling tasks under uncertainties. In this paper, the authors propose a new concept of two-fingered parallel gripper, which they name SCROLLIC (acronym for synchronously closing with rolling constraints). It provides multiple contacts and enables objects of a general shape to be held. Its design and functioning are exposed in detail, as well as the model of the workspace where firm grasps are achievable. For this workspace, a force-closure grasp is always possible when a form-closure is not realizable. A quality function to evaluate the grasp is modeled and a basic application for the gripper is shown. Although acting basically as a planar parallel-jaw gripper, the new gripper offers great stability and firmness in grasping.

The authors describe the construction of an articulated multi-vehicle robot for inspection and testing of pipeline interiors. The robot is capable of traveling inside pipes of radius 520-800 mm diameter over a distance 150 m. Output pressure versus extension characteristics of the two-stage air cylinder, reduction of the wave reflection in a wheel-type ultrasonic probe, an umbilical cable assembly housing optical fibers, air tubes and electric cables are key elements of the robot. The articulated robot was tested in the laboratory to evaluate and the scanning performance. The results of the non-destructive test of a weld bead to the longitudinal direction show that the robot can pick up surrounding color images and transmit them to the ground station's monitor with high precision.

This paper describes a sensor for the measurement of overall direction-of-action in 3-D space. The sensor uses a spherical heavy weight suspended by springs, without lateral distortion of the springs. When a platform on which the sensor is attached accelerates by an external force, the weight moves toward the direction from which a resultant direction of motional and gravitational accelerations are obtained. Displacement of the sphere is in proportion to the magnitude of the acceleration. Four small magnets are installed on the surface of the sphere so that the displacement can be measured using Hall Effect devices. In order to evaluate total stiffness and natural frequency of the suspended weight, behavior of the weight is analyzed. Experimental results show that measurement error is within 5.8 in all directions of gravity.

The design and experimental results for a suspension-shell tactile sensor are described. The sensor uses a suspension-shell mechanism to make the entire surroundings of a finger-body sensitive. The sensor detects the magnitude and the point of application of an external force operating on the shell by measuring the relative displacement of the suspension shell with regard to the finger-body. However, the force distribution is not provided since the sensor has no arrays, and the sensor records the actual force distributed over the surface area of the sensor shell as an integrated force at a single point of action. Sensing at the fingertip is excluded since the prototype sensor is designed for detecting lateral force rather than coaxial force for the first step. The sensor's basic characteristics and how it works in practice are shown.>

A proximity sensor is presented in which light is cast from a source point on an object through a slit cut in a rotating disk. The light passing through the slit is reflected onto the object's surface. Some of the reflected light is captured by a photodiode with the time period being recorded. The distance is determined from the function of the slit's shape and the time period when the photodiode captures the reflected light. The light-emitting mechanism makes it possible to measure the distance of an object repetitively. The distance measurement is neither affected by environmental illumination nor by attributes of the object such as diffusibility or reflectivity as far as there is light to reach the photodiode. Two profiles of the slit are discussed. One allows for easy fabrication and the other simplifies signal processing. The validity of the measurement concerning the two profiles is shown by experimental results.>

A three-wheeled vehicle for in-pipe monitoring tasks is described. The vehicle is basically composed of two hinged arms building what is hereafter referenced as a scissor structure. The arms are joined at one end. Another joint connects the middle points of the lower parts, called links. A wheel located at the pivot of the scissor structure is driven by an electric dc motor. Two other wheels located at the ends of the links (sphere bearings) are not actuated and can roll freely in any direction. Since the force of the arm mechanism pushing against the pipe wall is generated mechanically by an extension spring combined with levers, the vehicle rests in the pipe by pressing its wheels in the direction of maximum pipe cross section. The vehicle moves automatically by action of the driving wheel in the direction in which the pipe extends. The relation between the stretch force and the configuration of the vehicle is analyzed to optimize the lengths of the levers and the direction in which the levers should be attached for force generation. The geometric and kinematic conditions of the vehicle are investigated to make it move stably. Results of a simulation of locomotion proved the capability of self-adjustment of the vehicle to different pipe shapes and sizes. The resulting vehicle mechanism, called MOGRER, was built to carry a CCD video camera attached to its body for in-pipe monitoring tasks. Experimental results show that MOGRER can monitor while moving in an inclined pipe with a heavy angle, overcoming the effects of gravity and changes in pipe size and shape.

The computer control of a multijointed finger system is discussed. First, an overall view of the system is given, and the optimum operational direction of the fingers for manual tasks from their motional structure is determined. Primitive programs prepared for this system also are described. Second, the cooperative motion of two fingers is analyzed and control procedures are constructed for the fingers for locating objects at a desired position and in a desired orientation precisely under the condition such that each fingertip is considered globe-shaped. The cooperative motion of two fingers generating simultaneous finger operations is studied only in a situation in which the relative positions of the fingers and the grasped object are kept the same as those in the initial state. Third, the programming of several manual tasks is discussed, and experimental results are presented which verify the success made toward the programmable automation of manual tasks by multijointed fingers.

An object-handling system for manual industry is described. This system is designed to have a compact structure and to accomplish multiple prehension and flexible motion for manual tasks. The system has three fingers which have structures similar to those of a human. Namely, these fingers are composed of three, four, and four joints, respectively, and can perform not only such simple motions as bending and extending but also such lateral flexing motions as adduction and abduction. The kinematics of the system is discussed in a rectangular coordinate system. The general solution for the finger joint is obtained by solving a fourth-degree equation. The control mode of each finger joint is suitably changed between position and torque control, and each joint is controlled by a hardware servo system. Cooperative motions among the fingers are easily realized by means of the hardware servo system. In an experiment of swing motion, cooperative motion based on a force control is accomplished between the right and left fingers without dropping the object. Bar turning and sphere turning are accomplished smoothly by a computer control in which control signals for finger joints are generated by interpolating a sequence of set points that has been stored in the computer in the teaching process.