“FLUID POWER” - JFPA...“FLUID POWER” Vol.30, No.2, May.2016, JFPA 2 hydraulic technology was...

“FLUID POWER” Vol.30, No.2, May.2016 Special Issue on the 60th anniversary of JFPA foundation

The Aqua Drive System (Water hydraulics) Section Part 1 General Introduction Part 2 Future Prospects

Contents

Part 1 General Introduction The Birth and Development of the Aqua Drive System (ADS)

Dr. Shimpei Miyakawa, KYB Corporation 1

Part 2 Future Prospects 1. Future Prospects of Water Hydraulics (ADS)

Dr. Shimpei Miyakawa, KYB Corporation 4 2. Aqua Drive System (ADS) in the Meat/Food Processing Machinery Field

Ikuya Sato, Watanabe Foodmach Co., Ltd. 7

3. Aqua Drive System (ADS) in Medical, Welfare, and Nursing Care Fields

Dr. Atsushi Nishikawa, Shinshu University 10

4. Aqua Drive System (ADS) in the Disaster Prevention Field

Kazunori Une, Ironworks Une Co., Ltd. 13

5. Aqua Drive System (ADS) in Precision Machinery and Machine Tool Fields

Dr. Yohichi Nakao, Kanagawa University 17

“FLUID POWER” Vol.30, No.2, May.2016, JFPA

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Part 1 General Introduction The Birth and Development of the Aqua Drive System (ADS)

Dr. Shimpei Miyakawa, KYB Corporation

1. History of ADS technology and water-containing working fluid (1), (2)

Figure 1 shows the historical transition of working fluid for hydraulic systems in chronological

order. It is a well-known fact that water was used as working fluid for the water hydraulic press

invented by Englishman J. Bramah in 1795. From 18th to early 20th century, hydraulics was

meant water hydraulics. Then, the discovery of mineral oil paved the way for the rise of oil

hydraulic technology, which achieved the rapid advancement and has continued to evolve to the

present.

Meanwhile, water hydraulic technology has also been used in special circumstances. In addition

to petroleum-based working fluid, the application of fire-resistant, bio-degradable, and high water

base fluid was started from the perspective of explosion prevention and environmental conservation.

Water hydraulic technology, originally recognized as a high power source, is now expected to satisfy

requirements for global environmental conservation and safety, security, and cleanliness for people.

Fig. 1: Evolution of Fluid Power Technology

The ADS was proposed as a system with potential to meet such needs and with applications

different from those of the old water hydraulic technology, and was put to practical use. “Evolution

to ADS” in the figure shows that by incorporating the achievements of oil hydraulics, the old water


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hydraulic technology was completely changed to a new one, which is a small, high-speed, and

high-precision system with safety, security, and cleanliness based on the use of “pure water” as

working fluid. Organizations in Western countries simultaneously started to adopt this technology

around 1985. Now, 30 years on from then, the situation surrounding the ADS, such as business

success or suspension of R&D, is becoming clearer. The reasons and causes are also emerging.

2. ADS development promoted because of water characteristics and social background (3)

The advancement and development of technology are always pushed by a social background, and

technology development and markets are inseparable. Figure 2 shows a comprehensive overview

of embodiment processes of water hydraulic technology including the factors and requirements for

the promotion of the ADS. The start is the social background, and the end is technical issues

depending on each of the pressure areas. In the development of a new technology, a number of

factor analyses and problem solutions are simultaneously conducted from the start to the end.

From the results, the priority of activities should be determined. The most important thing is to

fully understand water characteristics to face markets. The opponents of a new technology are

conventional ones, as is well known. When the ADS is viewed in terms of needs in markets

without regard for conventional technologies, such as electric, oil hydraulic, and pneumatic, it is

positioned as the fourth drive/control technology. Sticking to the conventional markets makes it

difficult to satisfy social conditions, resulting in withdrawal from the field. Contemplate needs in

markets and the social background. The ADS serves as a bridge to meet customers’ requirements,

owing to its features, and a market will be established on the bridge, as a new technology. Listen

to customers and determine target markets. Comparison with oil hydraulic technology (i.e., a

similar technology) is not considered here. In technology development, “R & D items” emerge

through the determination of target markets. Similar items to those in conventional technologies

are seen in this phase. However, central technical issues of equipment are items described at the

bottom right of the figure. Previous research revealed that the pressure range to be used in

markets is extremely wide. The pressure area is determined according to customer’s conditions for

use, and not always a multiple of 7 (MPa). Development issues vary depending on each of the

areas.

Fig. 2: Overview of Development of ADS from Social and Technical Perspectives


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3. Practical use of the ADS (4), (5)

Based on the above-mentioned perspectives, the Japan Fluid Power Association established the

Water Hydraulic Committee in July 1999, and has been promoting the ADS with the Special

Committee, strenuously facilitating academic-industrial cooperation. The achievements were

introduced in the IFPEX 2014.

The Water Hydraulic Research Committee in the Japan Fluid Power System Society has also

been advancing the ADS, supporting it from the fundamental and academic viewpoints. In the

first committee meeting in May 1997, the research committee studied and organized the pressure

area to be used in the ADS, and classified it into 3 areas: low, medium, and high. Since then, based

on the classification, the research committee has been studying, researching, and developing the

ADS for as long as 18 years.

The exhibition “Water: the new power for machines!” in the IFPEX 2014 was a product of those

activities. Specific applications in the low pressure area include waterproof plates to prevent rain

water from flowing into underground parking lots and subway areas in heavy rain and bathing care

devices for persons of advanced age or with disabilities. For these devices, the water hydraulic

cylinder is driven at the pressure level of tap water network. Applications in the medium pressure

area of 7 MPa include functional components for food processing machines, such as water hydraulic

motors for rotation and water hydraulic cylinders for reciprocation. Those machines provide

cleaning water after food-processing operation to assure the safety and security of food.

Applications in the high pressure area of 14 MPa include formation of containers and parts that

must be clean, pressure generators most suitable for quality assurance of durability, and food

forming presses required to meet sanitation requirements.

As described above, the research and development of the ADS and the introduction to markets

were started around 1985. Based on the above-mentioned achievements, the ADS will be

introduced to markets for “light and compact” products, which will lead to the expansion of the fluid

power market scale.

4. References (1) S. Miyakawa: ADS technology development and market characteristics, Water hydraulic technology lecture

material in IFPEX 2008, 2008.4.23.

(2) S. Miyakawa: Aqua-Drive-System, O+P, 11-12, NOV/DEZ, 2010, Germany.

(3) S. Miyakawa: ADS technology development and commercialization, Journal of the Japan Fluid Power System

Society, VOL.44, NO.4, Jul. 2013.

(4) Y. Ohbayashi: Report of participation in special exhibition in IFPEX 2014, Journal of the Japan Fluid Power

Association, VOL.29, NO.1, Jan. 2015.

(5) S. Miyakawa, et al.: Water hydraulic technology feature article, Journal of the Japan Fluid Power System Society,

VOL.44, NO4, Jul. 2013.


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Part 2 Future Prospects 1. Future Prospects of Water Hydraulics (ADS)

Dr. Shimpei Miyakawa, KYB Corporation

1.1 Approaches to new technologies and new markets

In most cases, conventional concepts serve as a barrier to the emergence of a new technology. As

described in the General Introduction, the Aqua Drive System (ADS) was born from water

hydraulic technology that is the origin of all hydraulic technologies, as a system with characteristics

of oil hydraulic technology. When water hydraulic technology is sought again from another

perspective, conventional techniques, ideas, and common practices should be unlearned. This is

known as a paradigm shift.

In evaluation of a new technology/product, a two-dimensional representation “Portfolio:

Technology and Market” is often used. However, a paradigm shift axis must be added to the

two-dimensional representation to introduce a new technology into a new market.

A new market will never be found until the new technology/market areas are taken to a level of

paradigm shift, as shown in Fig. 1. Although the ADS is a hydraulic technology, “heavy and large”

product markets are not its main target, unlike oil hydraulic systems. For the ADS, the entry into

“light and compact” product markets that require safety, security, and cleanliness is being

attempted. In those markets, there exists non-conventional potential added value. Without a

paradigm shift, a new technology cannot be brought to a new market. First, for the introduction of

the ADS to the markets, above-mentioned characteristics should be understood. As conventional

techniques, ideas and experiences do not necessarily apply, it is vital to create new techniques.

Fig. 1: New Market/New Technology and Paradigm

1.2 ADS and social systems (1)

The features of the ADS have a strong link with social backgrounds and social systems based on

needs. Specifically, the food, medical care/drug, cosmetic, and packaging industries have needs

similar to “Safety and Security of Food” in recent years, and HACCP standards will be

implemented in food-related industries in the near future.

Fig. 2 shows the relation between ADS markets and social backgrounds/systems.

In this figure, the ADS is represented by a keyword, “environmental conservation.” When the

ADS is associated with markets involving environmental conservation, some prospective markets

will emerge. At the same time, the possibility of introduction of the ADS to a market can be

determined based on restrictions imposed by related social backgrounds and systems. It is such

restrictions and needs in markets that are the source to find a guideline for the standardization of

ADS equipment, and target markets will be identified if it is achieved.

New T New M

New T Present M

Present T New M

Present T Present M

Technology (T)

Market (M) New Present

Present

New

Para

dig

m S

hift


5

Fig. 2: ADS Markets and Social Systems

1.3 Specific examples of ADS markets

In recent years, there is an urgent need to take measures for “Safety and Security of Food.” As

one of the measures, upgrading of safety, security, and hygiene in meat processing facilities is

receiving attention in association with the Trans-Pacific Partnership (TPP) (2). This measure is a

hygiene control method “Hazard Analysis and Critical Control Point (HACCP),” which is used to

identify and analyze hazards in food production management.

In this measure, naturally the advanced hygiene control of processing facilities is important; and

machines, equipment, and work areas must be cleaned safely and effectively every day. Processing

facilities are under severe work environments, such as aging workforce, dangerous operation, and

high humidity. In washing, sterilization, disinfection, and drying processes, a large quantities of

water and steam are used. In many cases, steam of relatively low temperatures (100 to 250ºC) is

wasted. Therefore, the following proposal has been presented: A water hydraulic pump is driven

by a turbine utilizing the waste steam and all meat processing machines in a factory are driven by

the ADS. Planning safe, secure, and energy-saving (power recovery-enabled) facilities becomes

possible.

Fig. 3 illustrates the relation of a large amount of water used in meat processing facilities, the

water treatment technology, and the ADS applied in such places. Prospective industries for the

ADS technology are shown in the right of the figure.

Fire insurance

Environment-related systems

Basic Act on Establishing

a Sound Material-Cycle Society Act on Promoting Green Purchasing, etc.

Leisure &

sports

Radiation fields Underwater Undersea

Maritime/river

construction

machinery &

movable structures

(floodgate, etc.)

Safety

of people

General industrial

machinery

Large-scale water

hydraulic network

system (factory production

equipment)

Food

processing

Environmental

conservation (Aqua Drive System)

Special

environment

Nature

conservation

Energy

saving

Cleanliness

Hot work

machinery (steelmaking,

metal rolling)

Medical care

Medical drug

Paper

manufacturing

Semiconductor

Ind

ustria

l accid

en

t insu

ran

ce

F

ire S

erv

ice A

ct

Sanitation

Explosion

prevention

& safety

Resource

saving

Working

environment

Elimination of dirty,

dangerous

and difficult work

Food

Bottling

machines


6

Fig. 3: ADS and Water Management in Food Production Facilities

Fig. 4 shows an overview of ADS markets including water use with the “Pressure” and “Flow rate”

axes (3). Centrifugal pumps are generally used in the low pressure/high flow rate area; and

displacement pumps, in the high pressure/low flow rate area.

In recent years, “seawater desalination technology” is drawing attention because of water

shortage. That technology is positioned across the above-mentioned areas, and expected to be a

field of ADS markets, in addition to drive and control.

Fig. 4: Water Use and ADS Technology

References

(1) S. Miyakawa: Development trends and applications of water hydraulic technology (Aqua Drive

System), The Fluid Power Systems & Components, 2002 edition, The Heavy & Chemical

Industries News Agency.

(2) S. Miyakawa: Research and development of water hydraulic driven, advanced hygiene, and

energy-saving meat processing machines and total system, Livestock Technology, Dec. 2015.

(3) S. Miyakawa: ADS technology development and commercialization, Journal of the Japan Fluid

Power System Society, VOL.44, NO.4, Jul. 2013.

・食料品製造業

・酒/飲料類製造業

・化学薬品製造業

・プラスチック類製造業

・セメント製造業

・医薬化粧品製造業

・染色整理業

・紙類製造業

・自動車部品製造業

・半導体部品製造業

他の産業への波及効果

水処理技術ADS技術

食肉処理施設

水の水平・垂直利用

高度衛生管理技術（総合異常・故障予知）

駆動と制御自動化

上水・下水処理クリーン・衛生機器

水質管理

水利用の世界

Prospective industries for the ADS ・Food manufacturing

・Beverage production

・Chemical manufacturing

・Plastic manufacturing

・Cement manufacturing

・Drug & cosmetic manufacturing

・Dyeing and finishing

・Paper manufacturing

・Automobile parts manufacturing

・Semiconductor parts manufacturing

Water supply/ sewage treatment

Clean & sanitary

equipment

Meat processing facilities

Advanced hygiene control technology

(comprehensive abnormality & failure prediction)

World of Water use

ADS technology Water treatment technology

Automation of drive & control

Water quality management

Horizontal/vertical water use

Utilization of natural energies

Wind power Solar energy

Water jet cutting

Pressure

washing

Agricultural water

Flow rate

Pre

ssure


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2. Aqua Drive System (ADS) in the Meat/Food Processing Machinery Field

Ikuya Sato, Watanabe Foodmach Co., Ltd.

2.1 Introduction

Amid calls for “Safety and Security of Food,” meat/food processing machinery is required to

comply with safety- and security-related standards and to improve sanitary quality.

To expand meat/food processing machinery markets, it is essential to enter into markets in

countries with positive population growth other than Japan where the decline in the

population is reducing the market size. Before market entry, the compliance with

international standards for Western products is required (1).

Responding to such social backgrounds, an innovative poultry processing machine with a

new water hydraulic drive system “ADS” was introduced in 2010 (2). Subsequently, this

stream is spreading to the field of meat processing machines in meat processing facilities.

In this section, the 10-year history of ADS applications (to 2015) is described for slicing and

pressing machines among the meat processing machinery.

2.2 Development of an ADS-installed meat processing machine

The comparison of drive sources used in conventional meat processing machines revealed

the following characteristics. Electric drive systems are regulated by IP standards as

measures for water and drip prevention, but electrical problems, such as ground leakage, are

inevitable. Oil hydraulic drive systems require measures for oil spill upon leakage or

maintenance. Pneumatic drive systems have issues related to energy saving because the

energy (drive) efficiency is extremely low when a compressor is included.

From these results, the ADS was considered to be suitable for meat processing machines as

a measure to satisfy various needs from the meat processing industry, and the

commercialization of an ADS-installed machine was conducted.

2.2.1 Selecting a machine to install the ADS

Based on the advantages of ADS application and needs from the meat processing industry,

manufacturing of portion products (with the same shape and weight) from frozen meat was

selected as the examination object for ADS application.

Since meat has each an irregular shape, the product weight varies when it is sliced in a

normal manner. However, consumers require that each slice of meat should have the same

weight. Therefore, meat suppliers use various equipment to manufacture their products.

Generally in this manufacturing process, raw materials with an irregular shape are formed

into a regular shape, and then sliced to a certain thickness by a slicing machine. Materials

are formed by a meat press, which has an oil hydraulic power source.

To form irregular-shaped meat into a regular shape, the upper and the side oil hydraulic

cylinders press the material with a force of 30 t and 3 t, respectively (Fig. 1).

This machine received attention first, and application of the ADS was planned.

Fig. 1: Press Section Structure


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2.2.2 Issues on oil hydraulic presses

・Tampering upon leakage: Spilt oil is likely to attach to raw material.

・Low sanitary level: Many restrictions exist for cleaning because of the use of iron.

・Environment: Corrosion occurs in high-humidity and low-temperature places. 2.2.3 Advantages of ADS application

・Since the working fluid is “tap water,” the hygiene and safety levels are advanced.

・The sanitary level is improved by the use of SUS as material of cylinder, etc. 2.2.4 Creating an ADS-installed prototype

A prototype machine was built, and the basic operations and functions were checked (Fig.

2) (3).

・The condition of pressed raw material was equal to that by an oil hydraulic press.

・The safety level was improved by adoption of two-hand push control in operation.

・The sanitary level was improved because the whole cleaning became possible.

In 2014, this prototype was displayed in two exhibitions to demonstrate the functions and

advantages of ADS application to users of meat processing machinery.

Feedbacks and issues pointed out in the exhibitions are as follows:

・Advantages of ADS application are valid.

・The hygiene and safety levels and workability need to be improved.

・The price should be considered, with the balance between the market prices of conventional

machines and ADS-installed ones taken into account. 2.3 Commercializing an ADS-installed press

Based on the summarized exhibition feedbacks, the commercialization of the prototype

design was concluded difficult. A product design concepts were set as follows:

・Change the design to improve the sanitary and safety levels and to increase the machine

value.

・Optimize the machine structure to reduce costs.

In June 2015, a new machine including those concepts was built and displayed in an

exhibition as a product version (Fig. 3). After the exhibition, the machine has not been

ordered yet; however, it will be continuously proposed because application of the ADS

provides great advantages for the meat processing industry, which is struggling with

tampering problems.

Fig. 2: Full View of the Prototype Fig. 3: Commercialized meat press

2.4 Future prospects of food industries

Thus, it is now possible to offer proposals to use “safe, secure, and clean” machines for

manufacturing portion products from frozen meat. Currently, the development of a

combined pressing and slicing machine, the second proposal, is in progress.

This machine is being reviewed based on the concepts, “safety, security, and cleanliness”


9

and “labor saving” put in as an added value. However, the commercialization is not easy;

and the efforts to achieve the goal are being accumulated.

For the ADS, the future challenge is to reduce the costs. The ADS requires a high initial

cost. In terms of the running cost, however, the initial investment for a water hydraulic

system can be recovered in 3 years (compared to pneumatic) or 2 years (compared to oil

hydraulic), according to a calculation.

The target stage of water hydraulic systems is originally different from that of oil

hydraulic/pneumatic systems. It is important to facilitate users’ understanding of the

difference. As this fact has not been known well in the food processing industry,

disseminating that information is a key to promote the ADS in the future.

“Safety and Security of Food” is becoming a norm, and the ADS is an effective measure to

realize the norm. Penetrating the ADS into food industries, however, is considerably

difficult, and it cannot be achieved by one company. It will be required to build partnerships

with more ADS equipment/system suppliers, in addition to KYB Corporation that provided

cooperation and support for the product development this time.

References

(1) Commercialization of ADS-installed food processing machine, IFPEX 2014 forum, water

hydraulics session audit material.

(2) S. Mammoto: Hygiene-secured food processing machinery, Fluid Power, Vol.24, No.2,

p39-42, Apr. 2010.

(3) Accomplishment presentation of research and development 2014 material, Meat

Production Technology Research Association, Japan Meat Technology Institute.


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3. Aqua Drive System (ADS) in Medical, Welfare, and Nursing Care Fields

Dr. Atsushi Nishikawa, Shinshu University

3.1 Specifications required for medical and nursing-care robots

In the last 10 years, an epoch-making event occurred in the field of medical/nursing-robots,

and more specifically surgery assisting robots. In November 2009, “da Vinci®”, which is an

endoscopic surgery assisting robot developed by Intuitive Surgical, Inc. in the U.S., was

approved as a medical device by Japanese government, and the marketing approval was

granted. In April 2012, surgeries to remove prostate cancer with this robot were included in

the coverage of the national health insurance. Since then, the da Vinci has been introduced

mainly into domestic large hospitals at a rapid pace. As of the end of September 2015, more

than 200 units have been installed in medical facilities all over the country, and the system is

dominating the medical robot market in Japan (1). Actually, the da Vinci is built based on a

considerably old technology, which was developed around 1990s by the application of

industrial robot and military mechatronics technologies to the medical field, though its robot

functions are upgraded as needed. The actuators are driven by electromagnetic motors

commonly used in industrial robots, instead of fluid power.

In general, demanded specifications substantially differ between industrial and

medical/nursing-care robots. For industrial robots, the emphasis is on high power, high speed,

and high accuracy under human-free environments. On the other hand, the top priority for

medical/nursing-care robots is “affinity with humans,” including safety, cleanliness, and

usability, under environments where humans (doctors, patients, helpers) and robots work

together. The author and his team set up the following three basic concepts for medical

robots (and more specifically endoscopic surgery assisting robots) (2).

(1) Robots must have a system to release the force mechanistically when they are just about to

harm a doctor or patient for any cause. (Safety)

(2) The parts operating in a sterilized area must be disposable (one-time use). As robots are

provided for medical facilities after sterilization, the cleanliness is assured and no

maintenance is required there. (Cleanliness)

(3) Robots must be lightweight and compact. It is important that robots do not interfere with

doctors’ work and can be set up easily. (Usability)

These basic concepts are incompatible with the design concepts of da Vinci, which was

originally developed based on industrial and military robot technologies. As the da Vinci

robot is, so to speak, a collection of electrical systems that cannot be sterilized, medical staff

must cover the whole of this large equipment with a sterilized drape and set it carefully in

such a manner that it is positioned over the patient, every time. In the operating room, the

doctor (operating surgeon) works at a distance from the patient and robot, because he/she

watches a console to control the robot remotely. As a result, the patient condition is not easy

to understand for the surgeon. Moreover, other significant issues are also found for the

installation location, use in an emergency, and costs. To resolve these issues, a breakthrough

is required. The author and his team insist that the ADS is a key to realize the

above-mentioned basic concepts (requirement specifications) for medical robots; and they

started research and development to build a world's first “water-hydraulic driven” and

disposable surgery-assisting robot in 2006, just 10 years ago. That year marked the 50th

anniversary of the founding of the Japan Fluid Power Association.

3.2 ADS and “safety, cleanliness, and usability”

For the sterilizable water hydraulic linear actuator (2) independently developed by the

author and his team, the driving amount is controlled by the amount of water supplied

through a tube from a cylinder installed in an unsterilized area. This method is based on the

structures of syringe infusion pumps to administer medicines to a patient with high accuracy,


11

which have been demonstrating consistent performance in medical practice. The actuator is

safe, clean, lightweight, and low-cost, and there is no risk of electrical leakage in a sterilized

area. Moreover, highly-accurate control can be executed easily. If multiple actuators are

connected in parallel to form a robot (i.e., parallel mechanism), the structure can be simplified

and downsized, the setup will be easier, and the equipment can be made disposable. For

electric, oil hydraulic, and pneumatic systems, it is difficult to satisfy all these requirements

in a balanced manner; and the water hydraulic system is most suitable for actuators of

medical robots.

3.3 Dream in the future: ADS with an automatic endoscope operation function

Fig. 1: ADS with an automatic endoscope operation function

(New Year ’s card for 2016)

Figure 1 shows the New Year’s card for 2016 handwritten by the author. Actually, the

illustration is a modified version of an image that was drawn by the author when he set up the

R & D project for “water-hydraulic driven” endoscopic surgery assisting robots in 2006. The

most major characteristic of endoscope surgery is that the surgeon observes a diseased area

through an image displayed on the monitor via the endoscope. Therefore, how the endoscope

provides a field of view appropriate for surgical manipulations is an important factor to

perform surgery safely and successfully. Generally, the endoscope is operated by a camera

assistant (another surgeon who supports the operating surgeon) directly with his/her hands;

and if the assistant does not have enough experience and cannot provide an appropriate field

of view for the operating surgeon, the progress of surgery may be affected. In addition, if a

surgery simply takes a longer time, the assistant will not be able to provide a stable field of

view due to fatigue and hand shaking. In recent years, doctor shortage has been a problem,

and more surgeons with enough experience in the advanced endoscope surgery have also been

required.

To resolve such issues drastically, the author and his team started research 10 years ago in

order to realize “an ADS with an automatic endoscope operation function” that does not

require any help of a human camera assistant, like one shown in Fig. 1. As mentioned above,

such a system configuration with “high affinity with humans” is enabled only by the ADS.

Until now, many prototype machines have been designed and built, and have passed animal

testing successfully, but have not yet reached clinical application and practical realization. In

2016, the very year marking the 60th anniversary of the founding of the Japan Fluid Power

Association, this project entered the second stage under new industry-university,

interuniversity, and medical-engineering collaboration. The New Year’s card (Fig. 1) is an

expression of determination to realize the “dream” of putting into practical use and

popularizing small, lightweight, low-cost, and domestic endoscope surgery assisting robots

that are adapted to medical situations in Japan with concepts totally different from those of


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the made-in-US da Vinci and can be introduced even to small-and-medium-sized hospitals.

Please look forward to the next greeting card 10 years later.

3.4 Future prospects: new development in ADS

The small, lightweight, and compactible ADS is applicable to not only standard endoscope

surgery *1, but also single incision endoscopic surgery *2 and high-precision endoscope surgery

that is performed while biological information is being obtained with an open Magnetic

Resonance Imaging (MRI) and utilized in real time. (*1: Several incisions are made in the

abdominal or breast region of the patient. *2: All of the instruments and endoscope are

inserted into only one incision. If the incision is made in the navel, surgical scars will be

invisible. This method was started to spread around 2009.) Above all, high-precision

endoscope surgery can be a right candidate for the application of the ADS with “MR

compatibility,” which is ADS’s characteristic that it can be composed only of non-magnetic

components, including the drive system, for use in a sterilized area. Furthermore, a project

for water filled laparo-endoscopic surgery (WaFLES) has been started recently under the

initiative of a study group in Chiba University (3). This is a new method of endoscope surgery

where a body cavity is filled with an isotonic solution, such as normal saline, and medical

treatment is provided in water. It is more friendly to human bodies (cells and organs)

compared to the conventional endoscopic surgery where carbon dioxide is insufflated into a

body cavity to secure the space for operation. In recent years, the method has been drawing

attention as a new type of surgery in which characteristics special to underwater operation,

such as water pressure, water temperature, and buoyancy, are utilized. Another attention

point of this method is that ultrasonic images can be utilized effectively because sound travels

better in water than in the air. As the compatibility with the ADS is also extremely excellent,

the method is expected to further develop in the future.

3.5 Summary

This chapter has presented circumstances surrounding the ADS in the last 10 years and the

future vision in the next 10 years, based on the author’s personal view. Due to space

limitation and the author’s area of expertise, the discussions focused on surgery assisting

robots, and only general theories were described for the welfare and nursing care fields.

References

(1) Japan Robotic Surgery Society website: http://j-robo.or.jp/ [Date of access: 2016.1.20]

(2) Takeharu Kobayashi: Development of an endoscope surgery assisting robot, Journal of the

Japan Society of Mechanical Engineers, Vol. 112, No. 1083 (2009).

(3) WaFLES Project website: http://www.cfme.chiba-u.jp/~wafles/ [Date of access: 2016.1.20]


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4. Aqua Drive System (ADS) in the Disaster Prevention Field

Kazunori Une, Ironworks Une Co., Ltd.

4.1 Introduction

In the equipment for disaster prevention, an oil hydraulic or electrical drive source has been installed

generally; however, the development of products with a water hydraulic drive source is also in progress to

address issues of environment and fire caused by flash ignition.

One example is the development of a high-pressure water-driven cutter, which is an power cutter that

plays an active role in rescue operations in disaster sites. The water hydraulic system allows the cutter to

be operated in the scene of a fire, under oxygen deficient atmosphere, and underwater. Another example

is the ongoing research of a water hydraulic jack-up robot. This equipment is based on a small jack-up

robot for life-saving operations, and an ultrahigh-pressure water hydraulic cylinder is installed.

Meanwhile, against the high incidence of flood damage in various parts of Japan, the ADS is applied to

watertight walls, one of the flood damage prevention equipment, for labor saving and drastic improvement

of operability.

This chapter introduces a watertight wall among those products for disaster prevention.

4.2 Watertight wall driven by tap water hydraulic cylinders

In recent years, downpour, which is a driving rain falls in a small area over a short time (so-called

“guerrilla rainstorm”), has occurred frequently under the influence of climate change and heat island

phenomenon. This guerrilla rainstorm and heavy rain caused by a typhoon or a strong front have

wreaked enormous flood damage across Japan, especially in urban regions. Major characteristics of flood

damage caused by guerrilla rainstorms are as follows:

(1) The time and place of occurrence cannot be predicted.

(2) As an enormous amount of rain falls in a short time, flood occurs quickly.

Therefore, the following items are required for the waterproof equipment against the above-mentioned

flood damage.

(1) Anyone can operate it intuitively.

(2) It can be set up easily even by one person, in a short time.

As a disaster prevention product that satisfies those requirements, a rising-type watertight wall based on

ADS technology was developed and began to spread around 2012.

Photo 1 shows the appearance of a watertight wall installed at a shop entrance. A rising-type

watertight wall is a device that normally lies on the floor to allow the passage of humans/vehicles on it and

raises to keep out water in case of flood.

Photo 1: Appearance of a Watertight wall

From a faucet, pressure of the water supply network is provided to multiple double-acting low-pressure

water hydraulic cylinders to raise or lay the watertight wall, as shown in Photo 1. The most remarkable

feature is that even in case of a blackout in disasters, the device can be operated unlike electrical

equipment with an electrical drive source because it utilizes pressure of the water supply network. In fact,

anyone can raise the gate in an unquestioning and intuitive way simply by turning the lever handle on the

control panel as if opening a faucet. If the water source is not available due to water stoppage or other

causes, its manual rising system (i.e., a bicycle pump) can be used.


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As the water hydraulic cylinders takes only about 1 minute to raise the wall, it can sufficiently cope with

a rapid advance of torrential rain.

Figure 1 shows the constitution diagram of the watertight wall in raised and laid positions. The water

hydraulic cylinders are stored in the wall, but must operate without fail at the time of disaster. The

sliding resistance of cylinders is minimized so that they can be operated by a low pressure of approx. 0.2

MPa.

Fig. 1: Diagram of the Watertight wall

Table 1 shows the specifications of the water hydraulic cylinder.

Table 1: Water Hydraulic Cylinder Specifications

Structure Double acting

single rod

Working fluid Tap water

Rated pressure 1.0 MPa

Test pressure 1.5 MPa Minimum

working pressure 0.1 MPa

Tube bore 63 mm

Rod diameter 20 mm

Stroke 170 mm

Figure 2 shows the circuit diagram. Raised and laid positions are switched by the manual operation of

the 4-way switching valve. To prevent reflux into the water piping from the device for safety and hygiene,

a check valve is provided on the way from the piping to the switching valve. In addition, the appearance of

the control panel for the switching valve is simplified so that the operator can operate it without question,

as shown in Photo. 2.

Laid position Raised position

Water pressure direction

Tap water hydraulic cylinder

Pit

dep

th

Pit

dep

th

Wa

ll h

eig

ht


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Fig. 2: Circuit Diagram of the Watertight wall

Photo 2: Switching Valve for the Watertight wall

Generally, sandbags and fabricated wall-like waterproof equipment, such as flash boards*, have been

used to keep out water at the entrances of buildings because of their inexpensive introduction costs (*: a

gate that functions by the insertion and removal of a board). However, the installation requires a large

amount of labor for wide or more than one opening, and sometimes cannot be finished in time when rain

arrives quickly. The application of ADS technology utilizing pressure of the water supply network, which

can support above-mentioned installations mechanically, makes possible the development of a watertight

wall that allows the operator to easily raise the heavy metal panel laid on the floor with simple operation.

4.3 Conclusion

Disasters are never without unanticipated situations; and one example is the Fukushima nuclear

accident caused by the Great East Japan Earthquake in March 2011. The equipment for disaster

prevention to be used under such situations must operate without fail. Therefore, it is required to

thoroughly examine the selection of robust drive sources, backup functions in emergency, and simple

operations that can be performed without question even in a state of panic. According to “Damage caused

Control panel

Water supply

Water discharge

Check valve

Valve

Switching valve

Lay

Raise

Water discharge

Tap water pressure

Waterproof plate

Raise Lay

Stop


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by large-scale disasters and actions to water supply systems*,” the number of water stoppage was 2.3

million (including 0.24 million of stoppage due to blackouts) whereas 8.5 million of blackouts occurred in

the Great East Japan Earthquake (*: Water Resources Development Subcommittee material, National

Land Development Council, November 2013).

Pressure of the water supply network is not only a low-cost and readily-obtainable energy in daily life,

but also a valid drive source in disasters because the stoppage of supply less occurs.

The ADS technology surely has unlimited potential to provide innovative and advanced products also in

the disaster prevention field. To realize that, it is necessary to find ideas without being bound by

conventional knowledge and to replace in-use drive sources with the ADS in a pressure zone appropriate

for the intended use.


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5. Aqua Drive System (ADS) in Precision Machinery and Machine Tool Fields

Dr. Yohichi Nakao, Kanagawa University

5.1 Application of ADS technology in the machine tool field

The representative application example of ADS technology in the machine tool field is a

water-jet machine. It is a machine to process various materials with jet of water that

includes abrasive grains and is pressurized to several hundred MPa; and the machine is used

for cutting, etc., because it can also process hard-to-cut materials to which standard cutting

processing cannot be applied. This chapter focuses on the application of ADS technology in

the ultra-precision machine tool field that is expected to evolve in the future, instead of the

conventional fields of application in the machine tool field.

Based on the fundamental principle of machine tools, they are positioned as mother

machines that form the basis of manufacturing. The machining accuracy of machine tools for

forced processing, including cutting, is governed by the coping principle; and the accuracy of

processed products are subject to restrictions from the motion accuracy of machine tools used.

Especially in the field of ultra-precision machine tool application, the required machining

accuracy is several tens of nm or more, and therefore, the motion accuracy required for

ultra-precision machine tools reaches approximately several tens of nm, based on the

above-mentioned coping principle.

The ADS technology is expected to have the potential to obtain an extremely high motion

accuracy, and the research is now in progress.

5.2 ADS technology used in ultra-precision machine tools

Among products familiar to us, copiers and laser printers have various built-in lenses and

reflecting mirrors. In the process of machining molds for eyewear lenses, ultra-precision

machine tools are used. Mirror surface can be formed with a high accuracy by the cutting

process using an ultra-precision machine tool and monocrystal diamond turning tool. As

these parts are required to have the form accuracy of several tens of nm, the required motion

accuracy of spindles and linear motion tables that constitutes ultra-precision machine tools is

also extremely high. To achieve this, motion elements including spindles and linear motion

tables need high-precision bearings to provide a high motion accuracy. If currently-used

oil/pneumatic hydrostatic bearings are replaced with water hydrostatic ones, the following

performance improvement will be achieved.

5.2.1 Characteristics of water hydrostatic bearings

Oil hydrostatic bearings are used for spindles and linear motion tables of grinding machines,

and pneumatic hydrostatic bearings are used for spindles of most ultra-precision machine

tools.

When a hydrostatic bearing used in an ultra-precision machine tool is selected, compatibility

between high thermal stability and high bearing stiffness must be considered. For spindles,

pneumatic hydrostatic bearings are selected to suppress heat generation attributed to fluid

viscosity because spindle’s relative motion speed is generally high. At the same time, further

reduction of bearing displacement caused by machining load is needed as the required

machining accuracy increases. As a result, it is essential to improve bearing stiffness. To

suppress bearing displacement caused by 1 N of cutting force to 10 nm or lower, the support

stiffness of the bearing must be 100 N/μm or higher. Small pneumatic hydrostatic bearings,

which are advantageous to high-speed operation, are difficult to increase the stiffness due to

air compressibility.

Since water hydrostatic bearings utilize water that is a relatively-low-viscosity and

incompressible fluid, they are a valid option to achieve both of higher speed and higher

stiffness for spindles and linear motion tables, as shown in Fig. 1. As water has high specific


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heat and thermal conductivity, a high cooling effect can also be expected while it is used as

lubricating fluid for bearings.

Fig. 1 Effective Application Range of

Water Hydrostatic Bearings

5.2.2 Research on spindles and linear motion tables with water hydrostatic bearings

Application of water hydrostatic bearings to ultra-precision machine tools is being

researched by Professor Slocum at the Massachusetts Institute of Technology (MIT), other

than the author (1). The author’s laboratory also developed spindles and linear motion tables

that have built-in water hydrostatic bearings, and demonstrated the effectiveness.

If a flow rate control function is added to water hydrostatic bearings, displacement control of

the bearings becomes possible. This control system can be realized relatively easily by the

use of a commercial flow control valve and a conventional water hydrostatic bearing. In a

research by the author et al., the control resolution was measured to be 0.2 μm or lower (2), as

shown in Fig. 2, and 0.1 μm or lower in the following research. Especially if a certain value of

target displacement is set for this control system, the bearing displacement can be kept

constant regardless of external load fluctuations, and the bearing stiffness can be infinitized.

Fig. 2: Displacement Control Performance of Water Hydrostatic Bearings

For linear motion tables for ultra-precision machine tools, control of table attitudes, such as

pitching, yawing and rolling, will also be required, in addition to a simple displacement control.

Oil hydrostatic

bearing

Water

hydrostatic

bearing

Pneumatic

hydrostatic bearing


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By the enhancement of the displacement control function of water hydrostatic bearings,

attitude control will become possible. Fig. 3 (3) shows one of such examples.

Fig. 3: Attitude Control Performance of Water Driven Stage

For the water driven stage developed by the author et al. (4), a highly-accurate pitching

control can be executed by flow control and attitude signal feedback to the water hydrostatic

bearing. A higher machining accuracy of ultra-precision machine tools is expected to be

achieved by the application of water hydrostatic bearings and ADS technology to the machine

tools in future research and development.

5.3 Future expectations on ADS technology

To realize a sustainable society, efforts are being made in the industrial engineering field as

well. For example, a concept of “Green Manufacturing” is spreading, which includes the idea

of the realization of a recycling-based society and energy saving technologies for machine tools.

This concept is similar to the idea of the shift from “Linear Economy *1” to “Circular Economy *2” (*1: The mainstream of the conventional production activities. In “linear economy” the flow

from production to consumption is unidirectional. *2: An economy system where resources are

recycled effectively and optimally.).

Oil hydraulic systems are used in clamps and other devices of many machine tools, including

machining centers. If such oil hydraulic systems used in machine tools are replaced with

water hydraulic systems, green-manufacturing-compliant and eco-friendly machine tools seem

to be realized; however, machine tool manufacturers have not made much progress in the

application of ADS technology.

In early NC machine tools, oil hydraulic motors were used instead of servo ones. The

author’s laboratory is seeking for new usages of water hydraulic systems to achieve a higher

motion accuracy, which is not a mere replacement of oil hydraulic systems in machine tools

with water hydraulic ones.

The conventional machine tools do not allow tap water to be used in them without any

measures; and therefore, it is hoped that proper materials will be selected and new materials

will be developed to meet various conditions. The water hydrostatic linear motion table

developed by the research group at the MIT was made with ceramic. To evolve the ADS

technology, not only system development but also new material development and basic

research on water lubrication are required.

As for water that is essential to the ADS, it is required to establish a water quality

management technology or a robust ADS technology that is unaffected by water quality,

because tap water varies greatly among countries and regions. In addition, it must be

reminded that water is also a precious resource, as with mineral oil. On a world scale,

ensuring drinking water is becoming difficult every year. Some technologies will be required


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to be developed and established in the future to control the total water amount to be used in

the ADS and to manage ADS operations. In development and popularization of the ADS, ADS

engineers will play an important role in various technology fields, including unexplored ones.

References

(1) A. Slocum, Water Hydrostatic Bearings For Precision Machine Tools and Industrial

Machinery, Proc. of ASPE 2007 Annual Meeting, (2007).

(2) Y. Nakao et al., “Displacement control of water hydrostatic thrust bearing by hybrid use of

constant resistance restrictors and flow control valve”, Proc. 15th Intl. Conf. of the

European Society for Precision Engineering & Nanotechnology, Vol. 1, pp. 343-346, (2015).

(3) S. Shibata et al., “Trial study on attitude control of water driven stage”, Proc. of the 8th

LEM21, (2015).

(4) Y. Nakao et al., “Development and speed control of a water driven stage”, Transactions of

the JSME, Vol.80, No.815, (2014-7).

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