物件導向軟體之架構(Object-Oriented Software Construction)探討

Propulsion system development requires new, more affordable manufacturing techniques and technologies in a constrained budget environment, while future in-space applications will require in-space manufacturing and assembly of parts and systems. Marshall is advancing cuttingedge commercial capabilities in additive and digital manufacturing and applying them to aerospace challenges. The Center is developing the standards by which new manufacturing processes and parts will be tested and qualified. Rapidly evolving digital tools, such as additive manufacturing, are the leading edge of a revolution in the design and manufacture of space systems that enables rapid prototyping and reduces production times. Marshall has unique expertise in leveraging new digital tools, 3D printing, and other advanced manufacturing technologies and applying them to propulsion systems design and other aerospace materials to meet NASA mission and industry needs. Marshall is helping establish the standards and qualifications “from art to part” for the use of these advanced techniques and the parts produced using them in aerospace or elsewhere in the U.S. industrial base.

Additive manufacturing

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Hydraulic Control Systems

This paper presents the recent advancements in the control of multiple-degree-of-freedom hydraulic robotic manipulators. A literature review is performed on their control, covering both free-space and constrained motions of serial and parallel manipulators. Stability-guaranteed control system design is the primary requirement for all control systems. Thus, this paper pays special attention to such systems. An objective evaluation of the effectiveness of different methods and the state of the art in a given field is one of the cornerstones of scientific research and progress. For this purpose, the maximum position tracking error $|e|_{\rm max}$ and a performance indicator $\rho$  (the ratio of $|e|_{\rm max}$ with respect to the maximum velocity) are used to evaluate and benchmark different free-space control methods in the literature. These indicators showed that stability-guaranteed nonlinear model based control designs have resulted in the most advanced control performance. In addition to stable closed-loop control, lack of energy efficiency is another significant challenge in hydraulic robotic systems. This paper pays special attention to these challenges in hydraulic robotic systems and discusses their reciprocal contradiction. Potential solutions to improve the system energy efficiency without control performance deterioration are discussed. Finally, for hydraulic robotic systems, open problems are defined and future trends are projected.

A Survey on Control of Hydraulic Robotic Manipulators With Projection to Future Trends

Hardware-in-the-loop (HIL) simulations are more and more used to assess performances of electric drives. Software simulations lead to develop control of the studied system. In this case generally a lot of simplifications are assumed to reduce the computation time. Before a real-time implementation of the control, HIL simulations could be a very useful intermediary step. Thus a hardware device is introduced in the loop in order to take its real constraints into account. In this paper, three different kinds of HIL simulation are suggested: signal level, power level, and mechanical level. A example is given for the traction system of an electric scooter.

Different types of Hardware-In-the-Loop simulation for electric drives

Displacement control of a mobile crane using a digital hydraulic power management system

This article presents digital fluid power as a new branch of fluid power which offers high potential for innovative solutions. The variety of digital concepts is quite large and digital concepts ha...

https://journals.sagepub.com/doi/pdf/10.1177/0959651811435628

Is the future of fluid power digital

Hardware-in-the-loop environment for servo system controller design, tuning and testing

Design and Implementation of Energy Saving Digital Hydraulic Control System

In this paper, cavitation in water hydraulic poppet valves is investigated by an experimental method with a half cut test model The situation of cavitation appearance, the effects of cavitation on the characteristics of flow rate, noise level, pressure distributions and the boundary of inception of the cavitation are investigated Comparison between a poppet valve with sharp edged seat and another, which has a length on the seat, is made The effects of change in the shape of the seat are discussed as well as the effect of cavitation appearance As a result, it is revealed that the sharp edged seat valve is less influenced by the cavitation on its characteristics

Matti Linjama

Papers

Displacement control of a mobile crane using a digital hydraulic power management system

Is the future of fluid power digital

Hardware-in-the-loop environment for servo system controller design, tuning and testing

Design and Implementation of Energy Saving Digital Hydraulic Control System

Effect of Cavitation in Water Hydraulic Poppet Valves