Photo: DARPAThis robot won the DARPA Robotics Challenge 2015.
On Saturday, Team KAIST from South Korea emerged as the winner
of the DARPA Robotics Challenge (DRC) in Pomona, Calif., after its
robot, an adaptable humanoid called DRC-HUBO, beat out 22 other robots
from five different countries, winning the US $2 million grand prize.
The robot’s “transformer” ability to switch back and forth from a
walking biped to a wheeled machine proved key to its victory. Many robots lost their balance and collapsed to the ground
while trying to perform tasks such as opening a door or operating a
drill. Not DRC-HUBO. Its unique design allowed it to perform tasks
faster and, perhaps more important, stay on its feet—and wheels.
“Bipedal walking [for robots] is not very stable yet,” Jun Ho Oh, a professor of mechanical engineering at the Korea Advanced Institute of Science and Technology who led the KAIST Team, told IEEE Spectrum.
“One single thing goes wrong, the result is catastrophic.” He said a
robot with a humanoid form has advantages when operating in a human
environment, but he wanted to find a design that could minimize the risk
of falls. “I thought about different things, and the simplest was
wheels on the knees.”
Photo: DARPADRC-HUBO performs the valve task. Note its upper body turned 180 degrees.
“Flexibility is the most important thing,” DARPA program manager and DRC organizer Gill Pratt
said at a media briefing, commenting on the different robot designs. A
robot that could change its configuration from using legs to using
wheels, he explained, might be heavier and more complex, but would “give
you that flexibility.”
Professor Oh is an internationally recognized expert in humanoid
robots. He and his students at KAIST in Daejeon, South Korea, have been
improving their HUBO platform over several generations. Below is a video
from a few years ago, when Professor Oh gave us a tour of his lab and a demonstration of HUBO 2.
For the DRC Finals, Professor Oh decided to make significant
modifications to specifically address the tasks the robots would face.
At a workshop after the competition, he said DRC-HUBO is
“nothing very special, just a humanoid robot.” But in fact, his team at
KAIST custom designed and built almost every part of the robot. He estimated the cost of each humanoid at between $500,000 and $1 million. Here are some of the key features that helped the robot win the competition:
Wheels on knees: DRC-HUBO has motorized wheels on
both knees as well as casters on its feet [right]. The wheels let the
robot move around in a fast and stable manner. When rolling on the
ground, it uses optical sensors on the shins for optical flow odometry.
Powerful motors: Like SCHAFT, the robot that won a preliminary DARPA robot challenge and was acquired by Google,
DRC-HUBO draws a lot of power from its motors (there are 33 in the
robot, which has 31 degrees of freedom). With customized motor drivers
and an air cooling system (fans and fins), the robot is able to drive 3x
to 4x more current than what is listed in the motor specs, with peaks
of 30 amperes in some cases.
Compliance: The team wanted to make their robot
compliant, but didn’t want to use force-torque sensors and a
conventional feedback controller (which they feared would introduce
instabilities). So instead the implemented compliance on their custom
motor driver, using a special amplifier.
Rotating torso: DRC-HUBO can turn its upper body
up to 180 degrees. That means that the robot can have its knees pointing
one way and its eyes looking at the opposite direction (you
try that!). This capability works both in standing mode and kneeling
mode, and the robot relied on it during several tasks, including driving
the vehicle, cutting the wall [right], pushing away rubble, and climbing stairs.
Long arms: The KAIST Team realized that the arms
of HUBO 2 were too short for some tasks, so they designed longer
7-degrees-of-freedom arms for DRC-HUBO, and they also tucked all cables
inside, to prevent them from getting caught on things. Each arm can hold
up to 15 kilograms, and has an “adaptive gripper” capable of grasping
hard or soft objects.
Simplified sensing: Instead of a sensor-packed head with stereo cameras and a lidar that is continuously scanning the environment (used in the ATLAS robots,
for example), DRC-HUBO uses a simplified vision system; operators rely
on a regular camera most of the time, and a lidar, attached to a servo,
scans the environment only when needed. In fact, the robot appears to have no head, “only eyes,” one KAIST student told us.
Robust power: When motors draw lots of current,
the main power system may fail to provide enough power to critical
components. To avoid that, the team used a supercapacitor system that
keeps computers, communications, and some sensors like gyros running
even if the main power system goes down.
Custom software: The team uses the Xenomai
real-time operating system for Linux and a customized motion control
framework called PODO developed at KAIST. They also use the Gazebo simulation environment.
The team designed their software with a focus on the low bandwidth and
unstable nature of communications between operators and robot.
Now let’s take a closer look at DRC-HUBO going through all eight
tasks in the run that gave Team KAIST its victory (if you want to watch
the full run back-to-back, we uploaded it here; the full run at 20x is here):
1. Drive Task: Teams were allowed to make certain
modifications to the Polaris vehicle so their robots could drive it and
get out of it more easily. Team KAIST placed a metal contraption with
two levers on the floor of the vehicle; when DRC-HUBO pressed one of the
levers, a cable system made the second lever press the accelerator. The
robot holds on to the vehicle with its left hand and steers with its
right one. It completes this task very, very fast (in a little over a
minute) and, unlike other teams, it doesn’t stop while going around the
barriers.
2. Egress Task: This was one of the most difficult
tasks in the competition. When planning for it, Professor Oh said he got
in and out of the vehicle himself several times, to see what kind of
motions and parts of his body he needed to use. He concluded that a
“dynamic approach” was needed. His team programmed DRC-HUBO to put its
arms up and hold on to the frame of the vehicle. Then the robot applies
100 newtons of pulling force to each arm. As the arms pull the robot’s
body up, it pretty much falls out of the vehicle, albeit in a controlled
manner (hence the “dynamic approach”). Pay attention starting at 1:00.
It’s a beautiful egress maneuver! Professor Oh said the team burned
several motors perfecting this motion, but solved the problem using
their high power custom motor drivers. In the actual run, the robot is
able to get out in less than 4 minutes, and once it’s off the vehicle,
it gets on its knees and zips away.
3. Door Task: Unlike several other robots that had
to stand (and balance on two legs) to perform this task, DRC-HUBO could
stay on its knees to manipulate the door knob. It elegantly uses its
other arm to hold the door open while it releases the knob. In less than
2 minutes, it’s going through the doorway on its knee-wheels.
4. Valve Task: Note at the beginning of the video
how the lidar moves up and down to give the operators a scan of the
scene ahead. Then, as DRC-HUBO approaches the valve, it performs a
180-degree upper body rotation. Pay attention at 0:20 or you’ll miss it
(the camera angle doesn’t show the lower part of the robot,
unfortunately). In this configuration, while still kneeling, the robot
can raise its body just enough so that it can better manipulate the
valve (why stand if you don’t have to?). The robot performs some more
lidar scans, adjusts its position, and in about 3 minutes it’s done with
the task. Note that only one full turn was required but DRC-HUBO
performs two complete turns! At 2:01 you can see the robot “undoing” the torso rotation.
5. Wall Task: This was a tricky task for most teams
because it required a precise grasp of a drill, and the robots had to
press a trigger or on/off button to use the tool. DRC-HUBO relied on a
force-torque sensor on each hand to help with grasping. You can see the
robot moving itself and even repositioning the drill on the shelf (even
knocking down another drill out of the way) to find a good way to grab
it. Once the robot has the tool, operators indicate where to cut and the
robot does the rest autonomously. It keeps 20 newtons of force against
the wall, and you can see how it uses its whole body to move the drill
in a perfect circle. Completing this task takes about 11 minutes.
6. Surprise Task: The surprise task consisted of
pulling out a plug and putting it back into another socket. Note how
DRC-HUBO scans the floor and notices that the drill it had knocked down
earlier is on its path. The robot turns around and pushes the tool away
with its knees. It then tries to turn around but looks like it hits the
wall. The operators apparently notice the problem and drive forward a
bit and then are able to turn. Finally they approach the wall with the
plug, which is positioned higher than the valve and door knob. It’s time
to get up on its feet, and you can watch that happening starting at
3:05. DRC-HUBO takes some steps forward and after a while it initiates
the grasping process. It grabs the plug by its cable; we believe that
was intentional, to allow the operators to better see the plug and
prevent the robot’s hand from obstructing their view, which would make
the task nearly impossible. Inserting the plug proves tricky, and at
7:47 you can see how the robot tries to push it in and misses the
socket. After some corrective motions, success! The task takes 13
minutes and 30 seconds, the slowest in the run.
7. Rubble Task: While kneeling, DRC-HUBO can drive
with its knees pointing forward, or it can turn its upper body 180
degrees and drive with its feet pointing forward and acting as a
bulldozer’s blade. And that’s what it does for this task. You can see
the torso rotation starting at 0:28. It’s so cool. The robot then puts
its arms up, probably for stability and preventing them from getting
caught in the debris. It then starts plowing through the rubble. It
stops momentarily when it appears that a piece of wood might get stuck
on the cinder blocks, so it turns left a bit to get that out of the way.
It then moves the plastic tube to the right. At 4:14 it rotates its
torso once again and positions itself in front of the stairs. The task
took less than 5 minutes.
8. Stairs Task: Professor Oh said that, for many
tasks, especially climbing stairs, it’s important that the robot is able
to see its own feet. Big robots like ATLAS have a hard time doing that,
having to bend their bodies and making balancing more difficult.
DRC-HUBO solves this problem in a very clever way. It climbs the stairs backwards!
By doing that, its knees don’t block the robot’s cameras from seeing
its feet and the ground, and another advantage is that its shins won’t
ever hit the steps when it bends its legs. But how does it see its own
feet if it’s climbing the stairs backwards? By rotating its upper body,
of course! You can see the process starting at 0:26. The robot is
kneeling in front of the stairs when it suddenly turns its back to it.
It then stands up and at 0:55 you can see it turning the torso 180
degrees. Now it can scan the stairs and start the climb. But note that,
before doing that, it takes two steps sideways, to the left
(1:45)! After a couple of minutes—which felt like an eternity for those
watching—the robot finally starts going up, climbing the final three
steps in a continuous maneuver. Neat! After less than 7 minutes,
DRC-HUBO is atop the platform. The video has no audio, but at this point
the team and audience had exploded in cheers.
KAIST built four DRC-HUBOs and had been practicing without safety cables for over a month prior to the event. They
did their runs outdoors, on a parking lot with rough ground and under a
variety of conditions, including heavy sunlight and strong winds. “If we don’t remove safety, operators are too fearful,” Professor Oh said at the post-competition workshop.
He added that, during practice, they completed all tasks with the
robot both in walking and kneeling modes (their average time was about
30 minutes). The team was particularly good at clearing debris with
DRC-HUBO’s arms, something they didn’t get a chance to demonstrate at
the DRC Finals, and they could also comfortably perform the tasks on
much more difficult terrain than the one at the competition.
“Pity that we could not present that kind of beautiful walking
at the challenge. . . . It was too easy!” Professor Oh said, walking off
stage to applause.
Photo: Evan Ackerman/IEEE SpectrumProfessor Jun Ho Oh and his team celebrate their win at the DRC Finals on Saturday.Source: http://spectrum.ieee.org
The ReWalk™ robotic exoskeleton will make a guest appearance in Yaskawa’s booth. A ReWalker will demonstrate how the device provides powered hip and knee motion, enabling individuals with spinal cord injuries to stand upright and walk.
According to ReWalk Robotics, the device’s manufacturer, the ReWalk Personal is the only powered exoskeleton with U.S. Food and Drug Administration clearance. A rehabilitation version is also FDA approved.
In September 2013, Yaskawa announced its investment in Argo Medical Technologies, now ReWalk Robotics. DeRosett says there are parallels between exoskeletons and where production robots could be going in the near future.
“I think technology is moving in that direction, providing exoskeletons that can assist people in manufacturing or production environments to lift and move payloads that are not ergonomically practical today,” he says. “That could also translate into warehousing, supply chain and distribution environments.”
In fact, a recent report is projecting more than 70 percent growth for exoskeletons in the medical, military and industrial markets through 2019.
“Our core is all about motion and control,” says DeRosett, referring to Yaskawa’s expertise in servo motors and controllers. “That’s really much of the technology that’s needed in these types of devices.”
“There’s been a lot of discussion around collaborative robots, and humans and robots working together,” adds DeRosett. “You can’t get anymore collaborative than an exoskeleton.”
Robotic exoskeletons, especially those expected to populate factory floors and warehouses, blur the distinctions between industrial, collaborative and service robots, a rapidly emerging phenomenon we explored in RIA’s latest forecast article, Robotics 2015 and Beyond: Collaboration, Connectivity, Convergence.
