KAYABA TECHNICAL REVIEW No. 65 OCT. 2022

Foreword

Rethink of Hydraulics for Sustainable Robotics
HYON Sang Ho*

1. Prolog: Meditation During COVID-19 Pandemic
Two years ago, when the world was first hit by COVID19 infections, I tried to think of the value of robots. I
finally concluded that robots are ultimately a tool for mass
production, rather than machinery that can help people. I
have a university class on Robot Motion Control to teachstudents textbook theories for high-speed and accurate
control of hand motion trajectory tracking. This is essentially robotic theory for mass production. Today, however,
the world is saying "No" to mass production or volume
consumption.
When our socioeconomic activities were substantiallycurbed by the COVID-19 pandemic, people fully realized
how their individual activities should be prioritized or
how many so-called "bullshit jobs" they had. While I wasteaching online via my PC screen at home feeling something was wrong, essential workers throughout the world
were being exposed to risks of the infection as they diligently worked to relentlessly support society.
We may now have grown more or less accustomed tothe pandemic situation. Looking around, we can findroads, waterworks, power grids, and other society supporting infrastructure having seriously deteriorated due toa lack of labor. Infrastructure is something that is manmade. If you say people's health can be maintained byhealth care personnel including doctors and nurses, thenman-made things can be maintained by engineers.
As just an engineer, what could I do for society onearth? What could I do, as an educator, for young people?
One could certainly create novel things to attract people's
attention as in the Expos in the past. Inventors could feelexcited about and satisfied with them. Behind that,
however, people are involved in wasteful volume consumption, which is threatening the globe. It is now necessary to undergo a paradigm shift from robotics that canjust satisfy the mega-corporations' needs for high-volume
production for higher profits to another robotics as a new
methodology for mankind to survive.
Even after two years of agonizing over such issues, I
have not yet reached a solid conclusion. Still, there is achallenge I am now trying to address. It is modular robots.
* Professor at Ritsumeikan University

2. Modular Robot Project
Based on the social and natural environments we are in,needs will rapidly increase for civil engineering and construction, transportation, and facility maintenance operations in basically non-accessible environments, such as inagriculture, forestry and fishery, infrastructure maintenance, and disaster recovery. In response to these various
novel needs, not only high-performance robot equipment
but also total robot solutions that can reduce the operators'
burden and costs are needed.
One of the potential concepts for such solutions ismodular robots. Multiple single-function robots working
independently can be combined with each other to becomea robot assembly that can flexibly perform various tasks.
These modular robots offer many operational benefits,
including structure selection and allocation with the rightrobots in the right place, maneuverability and portability,and easy manufacturing and maintenance. Reconfigurable
robots and self-organized robots already exist in the academic area. These can be defined as robot systems toachieve a specific purpose while adapting their own shape
to indefinite circumstances. Many papers in the past haveshowed examples of concepts or simulations where anumber of objects of similar morphology are combined tobecome an assembly forming a specific structure.
However, most of these papers relied on computer graphics (CG) based studies mainly using planning algorithms.
Actual machine-based studies of this kind mainly coveredgroup displacement robots. Attempts to accomplish heavy
duty tasks that are generally assumed to be done by
outdoor robots have seldom been made.
Our challenge is to integrate modular robots withhydraulics. Specifically, we are thinking of maximizing
the robustness and high output specific to hydraulics aswell as the protean power collection and distribution
capability of hydraulic circuits and piping. The former
was introduced in the Technology Introduction article
titled Development of a Hydraulic Module Robot included
in KYB Technical Review No.61 in 2020. The latter
concept was presented at the International Conference on
Robotics and Automation (ICRA) of Institute of Electricaland Electronics Engineers (IEEE) in 2022.
For comparison purposes, let me take conventional―1―Rethink of Hydraulics for Sustainable Robotics

hydraulic machinery. For example, hydraulic excavators
have arms similar in shape to those of industrial manipulators. They can show great activity for disaster recovery
as powerful and reliable robots, although they are seldom
used as autonomous machinery. The front-end part ishighly modularized to accept a variety of attachments. For
hydraulic excavators, hydraulic equipment manufacturers
provide various actuators as discrete components, including cylinders, valves, and pumps. Still, it is difficult tomodularize these actuators because of the design ofhydraulic excavators wherein their drives are located atthe root of the machinery.
Industrial actuators integrated with drive sources represented by electro-hydraulic actuators (EHAs) haverecently become commercially available. Using this typeof actuator will realize robot modules integrated with ahydraulic source, although the power supply challenge
remains. However, such simple integration would inevitably result in robots with too heavy front ends, leading toan overall deterioration in performance. What impedes
modularization is essentially weight. Could it be possible
to realize a modular robot that can be manually carried
and assembled by people and is able to lift loads at least
equivalent to its own weight, although it could not be somodularized that it could easily be assembled by hand likehobby robots? If attachment and detachment of modular
parts can be automated, the robot can also assemble itself
without human intervention.
This research project considers the potential of hydraulics in several areas:A) The use of small pumps will allow robots to deliver
high output with small motors although the motor
speed is low.
B) For light loads, external pumps can be used to moverobots with agility.
C) Possible to manufacture shock-resistant, weatherproof robots at low cost.
D) Robot power can be monitored and controlled bymeans of pressure.
E) Pressure boosting and merging will allow multiple
shafts to interchange power.
F) Parts attachment and detachment can be achieved
with hydraulics.
Based on these ideas, research challenges were set up
and a research plan developed.
Certainly, robots that are mechanically merged andassembled are substantially inferior in performance tooptimally-designed integrated robots. Is this always true?
A question to be posed is, based on the operational needs
mentioned at the outset, "what are the conditions that give
hydraulic modular robots advantages to conventional
integrated robots?" Note that conventional robots include
pure electric robots. It is important to specifically verify
several hypotheses.

3. Epilog
Under the big slogan of the paradigm shift from tangible
to intangible goods, people's interest in tangible goods hasdiminished. Equipment mechanisms are hidden like ablack box and treated as second-rate things to be consumed in an instant, like something on a smartphone
screen. It is certainly good to get things done easily, but
how many engineers who can understand and interact
with mechanisms of tangible products would survive inJapan if the tendency of people to move away from tangible goods is going to progress in this pace? The samething can be applied to artificial intelligence (AI). Being
indifferent to technology can be considered as a kind ofabandonment of thinking. It is very dangerous to leaveadvanced robot technology to just a few people.
Renovation and similar concepts (including sustainabledesign) will increasingly affect how people face nature orartifacts. Concepts of these kinds always involve inconspicuous and rough-and-ready impressions, rather thanbrave, stereotype cutting-edge images as seen in great
discoveries of novel materials or big inventions regarding
their application. Moreover, they are very hard workrequiring people to be patient and cannot be achieved
without deep understanding of tangible goods and technology. I heard that, under this situation, more and moreyoung people have started to feel something strange aboutmass production and volume consumption. They tend tolove traditional or old things and are trying to put theirown ideas into them to produce additional value. This isdefinitely good news.
To cause renovation to sublimate into science, newinsights and methodologies are needed. Hydraulicmodular robots could be considered as products of renovation of conventional hydraulic machinery. From thenew perspective of modular robots, we can say we aretrying to take lessons from history or hydraulic technology that can be considered well established. While conventional robotics might play the passive role of justresponding to the industrial world's needs (mass production), new robotics should be "technology for all" withwhich people can voluntarily and boldly address difficult
issues in the Anthropocene era. Thinking patiently, wewant to repeatedly make and verify assumptions for as
long as time permits.
Finally, I would like to take this opportunity to thankKYB Corporation for their support for research and education at Ritsumeikan University. While many people areanxious about the sharply worsening issues of global
warming, the COVID-19 pandemic, and food and resource
risks, I hope that all engineers from KYB will continue toproudly support society more and more and work toward
Monozukuri that can save the earth.

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