This paper studies the flexibility of production management. Especially, the effects of production ordering intervals upon the flexibility are analyzed for multi-stage production inventory systems in make-to-stock environment. After the introduction, the literature on the flexibility of production management is reviewed. A mathematical model of a production system and its management system is developed. In the model, a multi-stage production inventory system with autocorrelated product demand fluctuation is formulated. Also, the production ordering interval is considered in the production management system. As performance criteria of flexibility, the amplifications of production quantity and inventory level are analyzed, and the relationship between the prduction ordering interval and the flexibility of production management system is clarified.
Tissue culture involves the regeneration of plants from very small plants, tissues, or cells grown aseptically in a suitable environmemt. A robot system has been developed to automate the cultivation of shoot tips. An image processing technique is used to decide where to cut a shoot. The procedure for the selection of the cutting points includes taking an image of a shoot, binalizing the image, deciding a search area where a joint exists, and deciding the cutting points. A robotic hand which cuts a shoot at two cutting points simultaneously and grasps the shoot without destroying it is developed. An applicative experiment using carnations is made to demonstrate the effectiveness of the robot system.
This paper presents that the combination of a robot with sliding tables equipped with a pulse stepper motor can make an automatic test system of instrument production compact. At the same time this paper presents the software technology consisting of a software reuse and an automatic programming. They improve the productivity of the test software development.
This paper deals with an optimal oil supply problem in which different kinds of oil must be supplied without mixing from the multiple input stations to the multiple output stations of a given pipeline network. The objective function is to minimize the overall transportation time. The genetic algorithm (GA) is applied to solving this problem. The individual description, the decoding rule and the operations of reproduction, crossover and mutation are proposed for this problem. Particularly, our attention is paid to the generation of lethal gene which corresponds to an infeasible solution of the problem. Numerical results show the effect of lethal gene in the algorithm.
The case-based approach applied to the design problem may be promising alternative to the knowledge-based one, since it is free from the knowledge acquisition from human designers. However the generated design candidates are frequently restricted within the range of the past cases from the conventional case-based reasoning. In this article, we discuss an application of the genetic algorithm to establish the structural case-base and to generate design candidates. Each structure is represented as an individual and its fitness is evaluated in terms of the frequency in the past cases. The case-base population is formed through the genetic operations. The genetic operation is also applied to the case-base for the candidate generation. The similarity between the design specification and that in the case-base is used as the fitness at this stage. The candidates generated by the proposed operations reflect the past cases but are partially free from them. This gives diversity of the design candidates to be considered by human designer.
The objective of the research work is to develop a product model which is applicable to represent shapes, structures and attributes of mechanical assemblies based on the STEP. In particular, emphasis is given to establishment of a data structure to represent hierarchical relations and connecting relations among the assemblies, sub-assemblies and parts. A data structure of the product model was proposed to describe the mechanical assemblies. The data structure developed here consists of the entities defined in the STEP and the entities newly proposed to represent the hierarchical relations and the connecting relations among the mechanical assemblies. A prototype of the product modeling system has been developed to input the product model data and to transfer the product model data to the model data for dynamic kinematic analysis.
This paper mainly describes an orientation control scheme of a vision-based autonomous vehicle by means of fluorescent lamps on the ceiling. The long shape of a fluorescent lamp makes this control possible. First, we propose the method that discriminates a fluorescent lamp from the other light sources and gives the distance and the angle between the vehicle and the fluorescent lamp. Then, the errors of the detected distance and angle are estimated and it is found that they are small enough to control the vehicle. Lastly, experimental results of the vehicle navigation are shown. The vehicle can move along the fluorescent lamp array or in a certain direction from the fluorescent lamp array. These two types of vehicle motion give the autonomous vehicle more flexibility to decide the vehicle's path in factories.
When an endpoint of a manipulator is moving in touch with a rigid smooth surface, it is controlled so as to realize both a desired trajectory on the surface and a desired contact force arising at the contact point. In this paper, a model-based adaptive control method for such a geometrically constrained robot manipulator is proposed. The position and force control of the manipulator is realized by orthogonalizing the position and velocity error vectors to the contact force vectors in the joint space through introduction of a projection matrix that projects error vectors in the joint space to the tangent plane of the constraint surface. The convergence of joint angular errors and contact force errors is proved under an appropriate initial Condition and the smoothness of the surface. The effectiveness of the proposed method is demonstrated by some computer simulation results using a 3-DOF manipulator dynamics model.
This paper deals with scheduling problems of minimizing the maximum completion time (i. e., the makespan) for automated manufacturing systems in which n jobs are processed on two machine centers Ma and Mb in this order, and there is an intermediate washing station (WS) between Ma and Mb, which is also used for storing the jobs completed on Ma (work-in-process, WIP). The job transportation between Ma and WS is done by a robot RTA and the job transportation between WS and Mb by another robot RTB. This paper gives an algorithm that can efficiently solve the problem exactly even when the job loading/unloading times are non-negligible and the job washing times are job-dependent. Furthermore, this paper gives more efficient algorithms for the special cases in which the washing station is set in input AS/RS (Automated Storage/ Retrieval System) or output AS/RS so only one transportation robot is necessary.
During cylindrical traverse grinding processes, two types of regenerative chatter -workpiece and grinding wheel- may degrade the accuracy of the surface finish. To maintain productivity and quality, a closed-loop vibration control system should be provided for the grinding system. An algorithm for automated classification by types is essential in developing such a system. In cylindrical traverse grinding, the chatter vibration signals display unstable dynamic characteristics, which makes the task of chatter classification especially difficult. This paper introduces an approach which combines entropy techniques with morphological preprocessing to classify traverse grinding regenerative chatter by types based on the vibration spectrum. Experimental data analysis is used to demonstrate that the proposed method can effectively distinguish workpiece regenerative chatter from wheel regenerative chatter. Since both entropy function and morphological processing are computationally easy, this method is not only transparent to the understanding but also conveniently adaptable to practical system expansion and real time applications.