Hideo Kitagawa

Multiprocessor scheduling algorithm with communication time

This paper proposes an algorithm for multiprocessor scheduling which is needed to realize efficient parallel processing. In the traditional multiprocessor scheduling algorithms the time required for data communication was neglected to decrease the complexity of combinatorial computation. In this paper, using a scheduling algorithm which incorporates elements of communication time into a suboptimal algorithm, divided tasks are assigned onto a multiprocessor system. The characteristics of this algorithm are two-fold: first, since the time required for data communication between processors as a parameter is taken into consideration, scheduling conforming to practical systems is possible; second, since it is based on a suboptimal algorithm, it shortens the time required for scheduling. Furthermore, as examples of applications of this algorithm, it is described how it is applied to inverse kinematics and inverse dynamics problems.

Dimensional Measurement at a Point on the Diffusing Surface by Using Speckle Pattern Interferometry

A collimated light beam from a He-Ne Laser, is transformed into two beams by using a concave lens and a beam-splitter cube, in a Twyman-Green-type interferometer. When a diffusing surface is placed at the focal point of one of the two beams, a diverging spherical wave front containing large-sized speckle patterns is scattered. If a smooth surface reference mirror is placed in the vicinity of the focal point of the other beam, the reflected beams have essentially the same shaped wave front. The two beams can be combined to form concentric interference fringes, which are fairly regular. By observing the concentric fringes flowing out or sinking in, it is shown that the normal component of the displacement of the diffused surface can be measured with an accuracy of a fraction of a half wavelength.

Cyclic Fine Change Sensing Method by Using Synchronized Image Input.

An object shape is changed by cyclic physical excitements, for example, sunlight in nature or vibration in factory. The change of shape is very fine and also cyclic. A new method is given for detecting edge movements of a cyclic moved object by cyclic physical excitements. The movement is very fine in a pixel on the image sensing device in a CID (Charge Injection Device) camera, but can be sensed by synchronized image input as cyclic edge movements of object. Every cycle has two images. One is with the excitement and another is with no excitement. The difference between the two images is calculated and these differences are summed 8 times. The summation has 64X128 matrix and shows the edge movement of a moved object. A conventional method with asynchronized image input gives 0.1 pixel resolution. The new method with synchronized image input gives 0.036 pixel resolution.

Composite Sensor Using Scattered Light from the Fringe of Laser Beams

This paper describes composite sensor for industrial robot, which detects both distance and slip. The fringe of interference by two laser beam is made by the sensor on the surface of an object which robot will hold. When the sensor is moved pararell to the surface of an object, the intensity of reflected light from the position of fringe changes periodically. And distance is calculated from the period of signal, which is proportional to distance. When slip occurs after robot holds an object, signal changes peiodically again because an object moves to the sensor relatively, and slip velocity can be calculated. Shape, position and orientation of an object can also be detected by measuring distance to several points.