Do Robots Need 28 Degrees of Freedom to Rescue the World?
Michael Molitch-Hou posted on December 27, 2016 |

It’s been over five years since disaster struck at the Fukushima Daiichi Nuclear Power Plant, but fear of the event’s long-term effects is still present, as is the memory of the faulty response on the part of government and corporate entities. Future nuclear incidents might be prevented by avoiding dangerous energy sources altogether; however, it is impossible to prevent other nonnuclear disasters from striking vulnerable populations. 

The WAREC-1 robot is designed to navigate a disaster area through unique movements. (Image courtesy of Kenji Hashimoto Lab and Atsuo Takanishi Lab, Waseda University.)
The WAREC-1 robot is designed to navigate a disaster area through unique movements. (Image courtesy of Kenji Hashimoto Lab and Atsuo Takanishi Lab, Waseda University.)

This is particularly true given the increase in extreme weather events related to climate change, and it is particularly true for Japan, one of the most disaster-prone countries in the world. In an effort to respond to such disasters as the Fukushima Daiichi meltdown, with the help of SOLIDWORKS, one team of researchers at Waseda University in Tokyo has developed a one-of-a-kind robot capable of traversing hazardous terrain to perform emergency safety procedures and rescue operations. The WAREC-1 (WAsedaREsCuer-No.1) robot is a machine like no other, and is capable of transforming on the spot depending on the task at hand.

Meet the WAREC-1

To spur the design of rescue robots, Japan’s Cabinet Office for Science and Technology launched the Tough Robotics Challenge through its Impulsing Paradigm Change through Disruptive Technologies Program. For the challenge, Waseda University’s Professor Atsuo Tananishi and Assistant Professor Kenji Hashimoto, in conjunction with Mitsubishi Heavy Industries, developed the WAREC-1 to function autonomously during a disaster. Watching the videos of the WAREC-1 below, you’ll get a quick sense for just how remarkable the robot is, as it shifts from a four-legged crawling mode to a bipedal ladder climbing mode.

 


The robot is able to achieve this uncanny ability through the use of four 7-degree-of-freedom limbs, totaling 28 degrees of freedom for the complete system. Each limb features actuator units of varying sizes for performing pitch, roll or yaw movements. As a result, the robot can move from a crawling position, in order to steadily move across a disaster area, to a climbing position, for effectively pulling up a ladder.

The various actuator units that make up the WAREC-1’s limbs give the robot a total of 28 degrees of freedom. (Image courtesy of Kenji Hashimoto Lab and Atsuo Takanishi Lab, Waseda University.)
The various actuator units that make up the WAREC-1’s limbs give the robot a total of 28 degrees of freedom. (Image courtesy of Kenji Hashimoto Lab and Atsuo Takanishi Lab, Waseda University.)
At 1690 mm tall and 150 kg, the WAREC-1 can crawl on its stomach, unlike the previous model, and it can climb ladders. And it does this without the burden of extra wires through the use of a distributed control system and a hollow-structured actuator unit that allows the wires to fit inside of the robot’s limbs. This prevents the wires from experiencing environmental damage or tangling so that the WAREC-1 can climb or crawl without them causing issues.

Designing the WAREC-1

In an interview with ENGINEERING.com, Hashimoto explained that, since 2001, he and his partner have been designing robots using SOLIDWORKS. After designing the parts with the software, Hashimoto and Tananishi would provide the models to manufacturers, who would then produce the components to specification. 

Of the robot’s design, Hashimoto said, “The main challenge was how to arrange component parts such as a motor, a reduction gear, encoders, etc., in a limited space. Both size reduction and weight reduction were realized while keeping high stiffness of each part by doing finite element analysis repeatedly.”

In particular, Hashimoto said that they relied heavily on simulation tools, and noted, “SOLIDWORKS Simulation, especially finite element analysis is vital to designing a legged robot because its weight must be as light as possible while maintaining a high stiffness. Flow Simulation is also useful when designing a cooling system of a heat source such as actuators, motor drivers, etc.” 

The Waseda team was able to fit all of the various components of the actuator unit into a single module. (Image courtesy of Kenji Hashimoto Lab and Atsuo Takanishi Lab, Waseda University.)
The Waseda team was able to fit all of the various components of the actuator unit into a single module. (Image courtesy of Kenji Hashimoto Lab and Atsuo Takanishi Lab, Waseda University.)

From the image above, it’s possible to see how the team was able to fit all of the necessary components into such a tight space. Rather than use two motors to control a single joint, which would have been much bulkier, Hashimoto and Tananishi were able to create a frameless motor design, in which the rotor and stator are built into the motor, which features a hollowed interior channel. In addition to hiding and protecting the robot’s wires, this makes it possible to reduce its weight. The researchers believe that it’s possible to further miniaturize the motors, as well. 

The Future of the WAREC-1 

At the moment, the WAREC-1 is powered by an outside source, which the team aims to replace with internal batteries. Other features that will be incorporated into the robot include sensors and other systems for increased environmental awareness. The robot may also be outfitted with specialty tools for performing certain emergency procedures. 

Hashimoto said, “We further aim to create a robot that can drill holes into walls and open and shut valves, by equipping it with visual sensors, remote control systems and robot hands that are being developed by other universities and research institutions.” 

Aside from these more exciting capabilities, Hashimoto explained that the team has to improve on minor, but still essential details. “For practical use, there are a lot of things to do such as dust proofing, water proofing, shock resistance and so on from the viewpoint of mechanical hardware,” Hashimoto said. 

Also important is the ability of the WAREC-1 robot to recover from failure and the ability to handle its complex structure in a live environment. According to Hashimoto, the WAREC-1 system that is ultimately implemented may be autonomous, but have a human handler. 

“WAREC-1 has 28 degrees of freedom in total, and it is not realistic to give the robot full autonomy in unstructured and changing environments without human intervention. Supervised autonomy, where an operator remotely controls the robot on a high level of abstraction, will be a possible solution,” Hashimoto said. 

The WAREC-1 may still be about 10 years away from practical implementation. (Image courtesy of Kenji Hashimoto Lab and Atsuo Takanishi Lab, Waseda University.)
The WAREC-1 may still be about 10 years away from practical implementation. (Image courtesy of Kenji Hashimoto Lab and Atsuo Takanishi Lab, Waseda University.)
With the existing design, the Waseda team was able to showcase the WAREC-1 traversing a variety of 20 to 100 mm wood blocks and ascending a vertical ladder; however, the robot is still about 10 years away from practical implementation.

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SOLIDWORKS has sponsored this post. It has provided no editorial input. For more information, go to www.solidworks.com.

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