We propose a new guide method for developing an easy-to-design process for product development. This process ensures a smaller number of wasteful iterations and less multiple conflicts. The design process is modeled as a sequence of design decisions. A design decision is defined as the process of determination of product attributes. A design task is represented as a calculation flow that depends on the product constraints between the product attributes. We also propose an automatic planning algorithm for the execution of the design task, in order to minimize the design loops and design conflicts. Further, we validate the effectiveness of the proposed guide method by developing a prototype design system and a design example of piping for a power steering system. We find that the proposed method can successfully minimize design loops and design conflicts. This paper addresses (1) a design loop model, (2) a design conflict model, and (3) how to minimize design loops and design conflicts.
This paper deals with an experimental evaluation of bending fatigue strength for austempered ductile iron (ADI) spur gears. The module is 2.5 and the number of teeth is 26 in the test gears. The material of the test gears corresponds to Japan Industrial Standard (JIS) FCAD1100-15. Some gears are processed by one of two types of fine particle bombarding (FPB). The surface roughness is slightly increased by FPB. The obtained strengths are 623 MPa for the as-austempered gears, and 1011 and 1085 MPa for the gears after FPB. The strength is expressed by the fillet stress level, which is calculated by FEM. The strength of a gear with the same dimensions made of carburized SCr420H alloy steel is 1205 MPa, and the strength of the ADI gear is approximately half that of the carburized steel gear. The FPB process has a significant effect on the ADI gear, improving its strength by 62-74%.
A swept volume strategy to detect the collision distances between obstacles is presented in this paper for robot motion planning based on optimization technique. The strategy utilizes the recursive quadratic programming optimization method to perform the motion planning problem. This paper is based on segmental swept volume for convenient distance-to-contact calculation. Hermite interpolation is presented to approach the envelope bounding the swept volume. The new method is capable of handling a modestly non-convex swept volume and it has yielded accurate answers in distance calculations. Also, examples would be presented to illustrate and demonstrate this approach in the paper.
The face hobbing process has been widely applied in automotive industry. But so far few analytical tools have been developed. This makes it difficult for us to optimize gear design. To settle this situation, this study aims at developing a computerized tool to predict the running performances such as loaded tooth contact pattern, static transmission error and so on. First, based upon kinematical analysis of a cutting machine, a mathematical description of tooth surface generation is given. Second, based upon the theory of gearing and differential geometry, conjugate tooth surfaces are studied. Then contact lines are generated. Third, load distribution along contact lines is formulated. Last, the numerical model is validated by measuring loaded transmission error and loaded tooth contact pattern.
This work extends the concepts and methodologies of Shen et al(1) and Al-Smadi et al(2) to synthesis of spatial RRSS motion generators with applied coupler loads. A general four-bar mechanism constraint that includes a coupler static load and a driver static torques is formulated using the principal of virtual work. This constraint is combined with the conventional RRSS motion generation model by Suh and Radcliffe(13) to form a nonlinear optimization problem from which RRSS mechanism solutions are calculated that approximate prescribed coupler poses and satisfy prescribed driver static torques for given coupler loads.
A ski boot is important to make progress in ski turning technique as an interface between a skier and a ski. Especially in alpine ski races, suitability of design of the boots for racers becomes more important to achieve accurate and quick lean of the leg in ski turns. This study is aimed at building a new design concept of a ski boot that can improve the results of alpine ski races. In this paper, new design of an upper shell of a ski boot that was adjusted to the features of the frame of alpine ski racers was experimentally examined. As a result, it was demonstrated that a front and a rear part of the upper shell of a ski boot should be separately adjusted to the length of a shank of each player for well-balanced quick lean of the leg in the ski turn. Finally, the effect of new design of an upper shell was examined in giant slalom and slalom tests by Japanese alpine ski racers of the first rank. Consequently, the results showed that lean angle during turns was increased and finish time was shortened when the skiers wore the newly designed boots.
We focused on developing a management system that provides a design process in which the important attributes of the product can be easily incorporated. We developed a knowledge template to express the product information using five types of knowledge, namely, knowledge about product structure, product entity, product function, product constraint, and product design process. To determine a suitable design process, we first compared the knowledge template of existing products with the product being designed. We calculated the consistency between the two models. From the results of the consistency calculation, we selected and extracted the available knowledge. We created a new design process by using the knowledge extracted from the design template. Finally, we evaluated the process from three perspectives: the ease with which the customer requirements could be reflected, the level of difficulty of the design conflict problem, and the level of difficulty of the design loop problem. Based on the results of this evaluation, designers can select a process to design a new product. We developed a prototype system and used it to design an ocean thermal energy conversion (OTEC) system. The design knowledge for an actual OTEC design was adequately represented by the proposed knowledge template. The most important attribute has a higher value in the design process obtained using the proposed management system process than in the existing system. The proposed management system yields a design process that can easily reflect customer requirements.
This paper proposes a new algorithm of generating pulse sequence for numerical controllers. Different from the existing algorithms using which the generated pulse frequency is fixed at one displacement increment, the proposed algorithm can generate pulse sequence with real-time changing frequency following the reference displacement command, so that fast-changing velocity requirements in machining can be satisfied. Moreover, by adopting the proposed algorithm, the generated velocity and acceleration can be also controlled within the range of the motor system to achieve better performance. Structure and parameters of the numerical controller which adopts the proposed algorithm are thoroughly discussed in this paper, and methods of adjusting the controller parameters to adapt to the servo system's torque-frequency characteristic are also introduced. At last, effectiveness of the proposed algorithm and effectiveness of the proposed methods for velocity and acceleration control are demonstrated by simulations.
In order to improve the power control flexibility of axial piston double pump and reduce energy consumption, a cross power control mechanism of double pump is developed. Comparing with the traditional summation power control and individual power control methods, the cross power control can distribute the power into two different individual pumps according to the sum of operating pressure of the two pumps. A virtual prototype of displacement adjusting mechanism of the double pump was established to analyze the control flexibility and energy saving ability of the cross power control. With this prototype model, the power distributions were calculated and analyzed at different operating pressures. Besides, the sensing control system of negative load was also simulated by the model as an additional function. And both the experiment results and simulation results were used to prove the performance of summation power control. It is concluded form the simulation and experimental analysis that the cross-power control has advantages in control flexibility, power distribution and energy-saving ability.