Nav: Home

Development of a hydraulic drive high-power artificial muscle

January 25, 2017

The artificial muscle that was developed using rubber tube is extremely powerful but lightweight and has strong resistance to impact and vibration, allowing for the most compact and energy efficient tough robots ever created. It is expected that this will lead to the smallest, lightest, and most powerful consumer robots ever created in the near future.

Highlights of the research

    * "Light yet Powerful" Ultra lightweight, highly powerful. Strength-to-weight ratio that is 5 to 10 times greater than conventional electric motors and hydraulic cylinders.

    * "Durable" High durability against impact and vibration achieved through highly durable, and oil-resistant rubber.

    * "Gently yet Strong" Possible to handle wide range of working environments requiring strong force and delicate control of power.

Research background and related details

Through the ImPACT Tough Robotics Challenge, our aim is to bring about "Tough Robots" that are used for rescuing people and ensuring safety in extreme environments after disasters such as the Great East Japan Earthquake Disaster and Han-Shin Awaji Earthquake Disaster in Japan. When existing robots are used in disaster situations, a number of problems arise. For example, they "cannot operate at disaster sites", the "situation is unknown", "total breakdown in the event of failure", and they "do not meet the work conditions". These problems must be overcome to achieve the goal of this program.

In this program, in order to create "Tough Robots" with excellent mobility and power that can be utilized for disaster recovery, the researchers are carrying out research and development of "tough hydraulic actuators", which are one of the key components. An actuator is a generic term for a device that generates "motion and power" and includes motors and cylinders. Most robots that currently exist are driven by electric motors that are based on technology commonly used for consumer products, but there are problems related to their structure. First, the "strength-to-weight ratio" (calculated by dividing the generated force by the weight of the actuator) is low (heavy and weak). Second, such robots have low resistance to outside impact and vibration (break easily), and third, it is difficult to achieve large power output while also having gentle movement according to the situation.

To address these problems, the Tokyo Institute of Technology and Bridgestone have focused on the development of human muscles, which are capable of outputting a large amount of power while also being capable of flexible movement according to the work being done. Since 2014, the researchers have been collaborating to promote research and development of "highly powerful artificial muscles" by striving for output greater than that possible by human muscles while also trying to reproduce their flexibility. These artificial muscles consist of rubber tubes and high-tensile fibers, and are actuated by hydraulic pressure. The use of rubber tubes and high-tensile fibers make it possible to achieve smooth movement, and the use of hydraulic pressure makes it possible to achieve a high "strength-to-weight ratio", high shock and vibration resistance, and gentle movement appropriate for the work being done.

This research opens up new possibilities for creating robots that have greater "toughness" than current robots; are highly resistant to external shock and vibration; able to perform high intensity jobs; and handle delicate jobs requiring precise power control as the situation necessitates.

Overview of research achievements

The high-power artificial muscle that was successfully developed is a kind of McKibben type artificial muscle. It consists of a rubber tube surrounded by a woven sleeve (many fibers woven into a cylindrical shape). Conventional McKibben type artificial muscles operate at an air pressure of 0.3 to 0.6 MPa (nearly equal 3 to 6 kgf/cm2), but the artificial muscle developed by the researchers can be used in hydraulic pressure drives, and is operable at a pressure of 5 MPa ( nearly equal 50 kgf/cm2), which is much higher than conventional McKibben type artificial muscles. Therefore, it is possible to generate a significantly higher amount of power with the muscle developed in this research.

The research team: (1) developed a new rubber material that has excellent oil resistance and deformation characteristics; (2) adjusted the method for weaving the high-tension chemical fibers; and (3) worked to develop a technique for tightening tube ends that can resist high pressures. As a result, the researchers were able to achieve an innovative, lightweight, and highly powerful artificial muscle with excellent pressure resistance and oil resistance, and that is capable of converting high hydraulic pressure into efficient power generation. It is an innovative actuator with a "strength-to-weight ratio" that is 5 to 10 times greater than conventional electric motors and hydraulic cylinders.

The artificial muscle developed in this research consists of a rubber tube surrounded by a woven sleeve, so it is highly resistant to strong external shocks and vibrations. It is expected to lead to tough robots that can handle work where shocks are applied, which is difficult for existing robots driven by electric motors to handle (for example, making holes in walls using an impact drill, chipping concrete walls, etc.).

Future development

The researchers will continue to proceed with the development and implementation of tough robots that use this artificial muscle in order to contribute to the realization and spread of advanced robot services for a safe and secure society. In addition, they are aiming to achieve higher performance and to help spread its use and development as a consumer-use robot actuator.

Remarks by Satoshi Tadokoro, Manager of ImPACT Program

The purpose of the ImPACT Tough Robotics Challenge is to create various "tough" technologies that are essential for robots used for disaster prevention and emergency response and recovery, rescue, and humanitarian support, and to establish industrial innovations through the creation of new projects along with social innovation for disaster prevention. We are promoting such project research development.

Robots that operate in disaster areas need to be lightweight, powerful, capable of controlling large forces precisely, have sufficient shock resistance, and other "mechanical toughness", which is different from robots used indoors and in factories. Methods using electric motors and reduction gears have limitations, so hydraulic actuators are essential. This research has developed a new McKibben type artificial muscle that can be driven by a hydraulic pressure of 5 MPa, and that can generate significantly more power than conventional methods while also being light. In addition, it is possible to minimize sliding friction, which becomes an issue when trying to achieve high precision control, and it has strong resistance to shock. It is expected that this component will allow for great progress to be made towards the practical application of robots in extreme environments such as disasters.

The Cabinet Office: Impulsing Paradigm Change through Disruptive Technologies Program (ImPACT)

Program Manager: Satoshi Tadokoro

Research development program: Tough Robotics Challenge

Research development theme: Development of a high-output artificial muscle

Person in charge of Research development: Koichi Suzumori

Research period: Fiscal 2014 to Fiscal 2018

Tokyo Institute of Technology

Related Robots Articles:

Darn you, R2! When can we blame robots?
A recent study finds that people are likely to blame robots for workplace accidents, but only if they believe the robots are autonomous.
Robots need a new philosophy to get a grip
Robots need to know the reason why they are doing a job if they are to effectively and safely work alongside people in the near future.
How can robots land like birds?
Birds can perch on a wide variety of surfaces, thick or thin, rough or slick.
Soft robots for all
Each year, soft robots gain new abilities. They can jump, squirm, and grip.
Robots activated by water may be the next frontier
Columbia University scientists have developed material that can drive mechanical systems, with movements controlled by a pattern set into the design.
The robots that dementia caregivers want: robots for joy, robots for sorrow
A team of scientists spent six months co-designing robots with informal caregivers for people with dementia, such as family members.
Faster robots demoralize co-workers
A Cornell University-led team has found that when robots are beating humans in contests for cash prizes, people consider themselves less competent and expend slightly less effort -- and they tend to dislike the robots.
Increasing skepticism against robots
In Europe, people are more reserved regarding robots than they were five years ago.
Humans help robots learn tasks
With a smartphone and a browser, people worldwide will be able to interact with a robot to speed the process of teaching robots how to do basic tasks.
Robots as tools and partners in rehabilitation
Why trust should play a crucial part in the development of intelligent machines for medical therapies.
More Robots News and Robots Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.