My seven species of robot -- and how we created them
-
0:01 - 0:04So the first robot
to talk about is called STriDER. -
0:04 - 0:07It stands for Self-excited
Tripedal Dynamic Experimental Robot. -
0:08 - 0:12It's a robot that has three legs,
which is inspired by nature. -
0:12 - 0:16But have you seen anything in nature,
an animal that has three legs? -
0:16 - 0:20Probably not. So why do I call this
a biologically inspired robot? -
0:20 - 0:21How would it work?
-
0:21 - 0:23But before that,
let's look at pop culture. -
0:23 - 0:27So, you know H.G. Wells's
"War of the Worlds," novel and movie. -
0:27 - 0:30And what you see over here
is a very popular video game, -
0:30 - 0:34and in this fiction, they describe
these alien creatures and robots -
0:34 - 0:36that have three legs that terrorize Earth.
-
0:36 - 0:40But my robot, STriDER,
does not move like this. -
0:40 - 0:43This is an actual dynamic
simulation animation. -
0:43 - 0:45I'm going to show you how the robot works.
-
0:45 - 0:47It flips its body 180 degrees
-
0:47 - 0:49and it swings its leg between the two legs
-
0:49 - 0:50and catches the fall.
-
0:50 - 0:52So that's how it walks.
-
0:52 - 0:54But when you look at us
human beings, bipedal walking, -
0:54 - 0:56what you're doing is,
-
0:56 - 1:00you're not really using muscle
to lift your leg and walk like a robot. -
1:00 - 1:03What you're doing is,
you swing your leg and catch the fall, -
1:03 - 1:05stand up again, swing your leg
and catch the fall. -
1:06 - 1:09You're using your built-in dynamics,
the physics of your body, -
1:09 - 1:10just like a pendulum.
-
1:10 - 1:14We call that the concept
of passive dynamic locomotion. -
1:14 - 1:16What you're doing is, when you stand up,
-
1:16 - 1:18potential energy to kinetic energy,
-
1:18 - 1:20potential energy to kinetic energy.
-
1:20 - 1:22It's a constantly falling process.
-
1:22 - 1:25So even though there is nothing
in nature that looks like this, -
1:25 - 1:29really, we're inspired by biology
and applying the principles of walking -
1:29 - 1:30to this robot.
-
1:31 - 1:33Thus, it's a biologically inspired robot.
-
1:33 - 1:35What you see here,
this is what we want to do next. -
1:35 - 1:38We want to fold up the legs
and shoot it up for long-range motion. -
1:38 - 1:41And it deploys legs --
it looks almost like "Star Wars" -- -
1:41 - 1:44so when it lands, it absorbs
the shock and starts walking. -
1:44 - 1:47What you see over here, this yellow thing,
this is not a death ray. -
1:47 - 1:48(Laughter)
-
1:48 - 1:50This is just to show you
-
1:50 - 1:52that if you have cameras
or different types of sensors, -
1:52 - 1:54because it's 1.8 meters tall,
-
1:54 - 1:57you can see over obstacles like bushes
and those kinds of things. -
1:57 - 1:58So we have two prototypes.
-
1:58 - 2:01The first version,
in the back, that's STriDER I. -
2:01 - 2:04The one in front,
the smaller, is STriDER II. -
2:04 - 2:07The problem we had with STriDER I is,
it was just too heavy in the body. -
2:07 - 2:10We had so many motors aligning the joints
-
2:10 - 2:11and those kinds of things.
-
2:11 - 2:14So we decided to synthesize
a mechanical mechanism -
2:14 - 2:17so we could get rid of all the motors,
and with a single motor, -
2:17 - 2:19we can coordinate all the motions.
-
2:19 - 2:22It's a mechanical solution to a problem,
instead of using mechatronics. -
2:22 - 2:26So with this, now the top body
is lighted up; it's walking in our lab. -
2:26 - 2:28This was the very first successful step.
-
2:28 - 2:31It's still not perfected,
its coffee falls down, -
2:31 - 2:33so we still have a lot of work to do.
-
2:33 - 2:36The second robot I want
to talk about is called IMPASS. -
2:36 - 2:41It stands for Intelligent Mobility
Platform with Actuated Spoke System. -
2:41 - 2:43It's a wheel-leg hybrid robot.
-
2:43 - 2:47So think of a rimless wheel
or a spoke wheel, -
2:47 - 2:50but the spokes individually
move in and out of the hub; -
2:50 - 2:52so, it's a wheel-leg hybrid.
-
2:52 - 2:54We're literally reinventing
the wheel here. -
2:55 - 2:57Let me demonstrate how it works.
-
2:57 - 3:01So in this video we're using an approach
called the reactive approach. -
3:01 - 3:04Just simply using
the tactile sensors on the feet, -
3:04 - 3:07it's trying to walk
over a changing terrain, -
3:07 - 3:09a soft terrain where it pushes
down and changes. -
3:09 - 3:12And just by the tactile information,
-
3:12 - 3:14it successfully crosses
over these types of terrains. -
3:14 - 3:18But, when it encounters
a very extreme terrain -- -
3:18 - 3:22in this case, this obstacle
is more than three times the height -
3:22 - 3:23of the robot --
-
3:23 - 3:25then it switches to a deliberate mode,
-
3:25 - 3:28where it uses a laser range finder
and camera systems -
3:28 - 3:30to identify the obstacle and the size.
-
3:30 - 3:33And it carefully plans
the motion of the spokes -
3:33 - 3:37and coordinates it so it can show
this very impressive mobility. -
3:37 - 3:39You probably haven't seen
anything like this out there. -
3:39 - 3:43This is a very high-mobility robot
that we developed called IMPASS. -
3:45 - 3:46Ah, isn't that cool?
-
3:46 - 3:50When you drive your car,
-
3:50 - 3:54when you steer your car, you use
a method called Ackermann steering. -
3:54 - 3:56The front wheels rotate like this.
-
3:56 - 3:58For most small-wheeled robots,
-
3:58 - 4:00they use a method
called differential steering -
4:00 - 4:03where the left and right wheel
turn the opposite direction. -
4:03 - 4:06For IMPASS, we can do many,
many different types of motion. -
4:06 - 4:07For example, in this case,
-
4:07 - 4:10even though the left and right
wheels are connected -
4:10 - 4:13with a single axle rotating
at the same angle of velocity, -
4:13 - 4:16we simply change the length
of the spoke, it affects the diameter, -
4:16 - 4:18then can turn to the left
and to the right. -
4:18 - 4:21These are just some examples
of the neat things we can do with IMPASS. -
4:21 - 4:23This robot is called CLIMBeR:
-
4:23 - 4:27Cable-suspended Limbed Intelligent
Matching Behavior Robot. -
4:27 - 4:30I've been talking
to a lot of NASA JPL scientists -- -
4:30 - 4:32at JPL, they are famous
for the Mars rovers -- -
4:32 - 4:34and the scientists,
geologists always tell me -
4:34 - 4:37that the real interesting science,
the science-rich sites, -
4:37 - 4:39are always at the cliffs.
-
4:39 - 4:41But the current rovers cannot get there.
-
4:41 - 4:43So, inspired by that,
we wanted to build a robot -
4:43 - 4:47that can climb
a structured cliff environment. -
4:47 - 4:48So this is CLIMBeR.
-
4:48 - 4:49It has three legs.
-
4:49 - 4:53It's probably difficult to see, but it has
a winch and a cable at the top. -
4:53 - 4:56It tries to figure out
the best place to put its foot. -
4:56 - 4:57And then once it figures that out,
-
4:57 - 5:00in real time, it calculates
the force distribution: -
5:00 - 5:03how much force it needs
to exert to the surface -
5:03 - 5:05so it doesn't tip and doesn't slip.
-
5:05 - 5:07Once it stabilizes that, it lifts a foot,
-
5:07 - 5:10and then with the winch,
it can climb up these kinds of cliffs. -
5:11 - 5:13Also for search and rescue
applications as well. -
5:13 - 5:16Five years ago,
I actually worked at NASA JPL -
5:16 - 5:18during the summer as a faculty fellow.
-
5:18 - 5:21And they already had
a six-legged robot called LEMUR. -
5:21 - 5:23So this is actually based on that.
-
5:23 - 5:24This robot is called MARS:
-
5:24 - 5:26Multi-Appendage Robotic System.
-
5:26 - 5:27It's a hexapod robot.
-
5:27 - 5:29We developed our adaptive gait planner.
-
5:29 - 5:32We actually have a very interesting
payload on there. -
5:32 - 5:33The students like to have fun.
-
5:33 - 5:36And here you can see that it's walking
over unstructured terrain. -
5:36 - 5:37(Motor sound)
-
5:37 - 5:40It's trying to walk
on the coastal terrain, a sandy area, -
5:40 - 5:45but depending on the moisture content
or the grain size of the sand, -
5:45 - 5:49the foot's soil sinkage model changes,
so it tries to adapt its gait -
5:49 - 5:51to successfully cross
over these kind of things. -
5:51 - 5:53It also does some fun stuff.
-
5:53 - 5:56As you can imagine,
we get so many visitors visiting our lab. -
5:56 - 5:59So when the visitors come,
MARS walks up to the computer, -
5:59 - 6:01starts typing, "Hello, my name is MARS.
-
6:01 - 6:02Welcome to RoMeLa,
-
6:02 - 6:05the Robotics Mechanisms
Laboratory at Virginia Tech." -
6:05 - 6:07(Laughter)
-
6:07 - 6:09This robot is an amoeba robot.
-
6:09 - 6:12Now, we don't have enough time
to go into technical details, -
6:12 - 6:14I'll just show you
some of the experiments. -
6:14 - 6:16These are some of the early
feasibility experiments. -
6:16 - 6:19We store potential energy
to the elastic skin to make it move, -
6:19 - 6:23or use active tension cords
to make it move forward and backward. -
6:23 - 6:24It's called ChIMERA.
-
6:24 - 6:27We also have been working
with some scientists and engineers -
6:27 - 6:29from UPenn
-
6:29 - 6:32to come up with a chemically actuated
version of this amoeba robot. -
6:32 - 6:34We do something to something,
-
6:34 - 6:37and just like magic, it moves.
-
6:38 - 6:39"The Blob."
-
6:40 - 6:42This robot is a very recent project.
-
6:42 - 6:43It's called RAPHaEL:
-
6:43 - 6:46Robotic Air-Powered Hand
with Elastic Ligaments. -
6:46 - 6:49There are a lot of really neat,
very good robotic hands -
6:49 - 6:50out there on the market.
-
6:50 - 6:52The problem is,
they're just too expensive -- -
6:52 - 6:53tens of thousands of dollars.
-
6:53 - 6:56So for prosthesis applications
it's probably not too practical, -
6:57 - 6:58because it's not affordable.
-
6:58 - 7:01We wanted to tackle this problem
in a very different direction. -
7:01 - 7:04Instead of using electrical motors,
electromechanical actuators, -
7:04 - 7:06we're using compressed air.
-
7:06 - 7:10We developed these novel actuators
for the joints, so it's compliant. -
7:10 - 7:11You can actually change the force,
-
7:11 - 7:13simply just changing the air pressure.
-
7:13 - 7:15And it can actually crush
an empty soda can. -
7:15 - 7:19It can pick up very delicate
objects like a raw egg, -
7:19 - 7:20or in this case, a lightbulb.
-
7:21 - 7:24The best part: it took only 200 dollars
to make the first prototype. -
7:26 - 7:29This robot is actually
a family of snake robots -
7:29 - 7:30that we call HyDRAS,
-
7:30 - 7:33Hyper Degrees-of-freedom Robotic
Articulated Serpentine. -
7:33 - 7:35This is a robot that can climb structures.
-
7:35 - 7:37This is a HyDRAS's arm.
-
7:37 - 7:39It's a 12-degrees-of-freedom robotic arm.
-
7:39 - 7:41But the cool part is the user interface.
-
7:42 - 7:44The cable over there,
that's an optical fiber. -
7:44 - 7:47This student, it's probably
her first time using it, -
7:47 - 7:49but she can articulate it
in many different ways. -
7:49 - 7:53So, for example, in Iraq, the war zone,
there are roadside bombs. -
7:53 - 7:57Currently, you send these remotely
controlled vehicles that are armed. -
7:57 - 8:00It takes really a lot of time
and it's expensive to train the operator -
8:00 - 8:02to operate this complex arm.
-
8:02 - 8:04In this case, it's very intuitive;
-
8:04 - 8:06this student, probably
his first time using it, -
8:06 - 8:08is doing very complex manipulation tasks,
-
8:08 - 8:12picking up objects and doing
manipulation, just like that. -
8:12 - 8:13Very intuitive.
-
8:15 - 8:17Now, this robot
is currently our star robot. -
8:17 - 8:20We actually have a fan club
for the robot, DARwIn: -
8:20 - 8:23Dynamic Anthropomorphic
Robot with Intelligence. -
8:23 - 8:27As you know, we're very interested
in human walking, -
8:27 - 8:29so we decided to build
a small humanoid robot. -
8:29 - 8:31This was in 2004; at that time,
-
8:31 - 8:33this was something really,
really revolutionary. -
8:34 - 8:35This was more of a feasibility study:
-
8:35 - 8:38What kind of motors should we use?
Is it even possible? -
8:38 - 8:40What kinds of controls should we do?
-
8:40 - 8:43This does not have any sensors,
so it's an open-loop control. -
8:43 - 8:46For those who probably know,
if you don't have any sensors -
8:46 - 8:49and there's any disturbances,
you know what happens. -
8:49 - 8:51(Laughter)
-
8:51 - 8:56Based on that success, the following year
we did the proper mechanical design, -
8:56 - 8:57starting from kinematics.
-
8:57 - 9:00And thus, DARwIn I was born in 2005.
-
9:00 - 9:03It stands up, it walks -- very impressive.
-
9:03 - 9:06However, still, as you can see,
it has a cord, an umbilical cord. -
9:06 - 9:08So we're still using
an external power source -
9:08 - 9:10and external computation.
-
9:11 - 9:14So in 2006, now it's really
time to have fun. -
9:14 - 9:16Let's give it intelligence.
-
9:16 - 9:18We give it all the computing
power it needs: -
9:18 - 9:20a 1.5 gigahertz Pentium M chip,
two FireWire cameras, -
9:20 - 9:23rate gyros, accelerometers,
four forced sensors on the foot, -
9:23 - 9:24lithium polymer batteries --
-
9:25 - 9:28and now DARwIn II
is completely autonomous. -
9:28 - 9:31It is not remote controlled.
There's no tethers. -
9:31 - 9:35It looks around, searches for the ball ...
looks around, searches for the ball, -
9:35 - 9:40and it tries to play a game of soccer
autonomously -- artificial intelligence. -
9:40 - 9:41Let's see how it does.
-
9:41 - 9:43This was our very first trial, and ...
-
9:43 - 9:47(Video) Spectators: Goal!
-
9:48 - 9:51Dennis Hong: There is actually
a competition called RoboCup. -
9:51 - 9:54I don't know how many of you
have heard about RoboCup. -
9:54 - 9:58It's an international autonomous
robot soccer competition. -
9:58 - 10:01And the actual goal of RoboCup is,
-
10:01 - 10:03by the year 2050,
-
10:03 - 10:07we want to have full-size,
autonomous humanoid robots -
10:07 - 10:10play soccer against the human
World Cup champions -
10:10 - 10:11and win.
-
10:11 - 10:12(Laughter)
-
10:12 - 10:14It's a true, actual goal.
-
10:14 - 10:17It's a very ambitious goal,
but we truly believe we can do it. -
10:17 - 10:19This is last year in China.
-
10:19 - 10:22We were the very first team
in the United States that qualified -
10:22 - 10:24in the humanoid RoboCup competition.
-
10:24 - 10:26This is this year in Austria.
-
10:26 - 10:29You're going to see the action
is three against three, -
10:29 - 10:30completely autonomous.
-
10:30 - 10:31(Video) (Crowd groans)
-
10:31 - 10:33DH: There you go. Yes!
-
10:33 - 10:37The robots track and they team-play
amongst themselves. -
10:38 - 10:39It's very impressive.
-
10:39 - 10:41It's really a research event,
-
10:41 - 10:45packaged in a more exciting
competition event. -
10:45 - 10:48What you see here is the beautiful
Louis Vuitton Cup trophy. -
10:48 - 10:50This is for the best humanoid.
-
10:50 - 10:54We'd like to bring this, for the first
time, to the United States next year, -
10:54 - 10:55so wish us luck.
-
10:55 - 10:56(Applause)
-
10:56 - 10:57Thank you.
-
10:57 - 10:59(Applause)
-
10:59 - 11:01DARwIn also has a lot of other talents.
-
11:01 - 11:05Last year, it actually conducted
the Roanoke Symphony Orchestra -
11:05 - 11:07for the holiday concert.
-
11:07 - 11:10This is the next generation
robot, DARwIn IV, -
11:10 - 11:13much smarter, faster, stronger.
-
11:13 - 11:15And it's trying to show off its ability:
-
11:15 - 11:17"I'm macho, I'm strong."
-
11:17 - 11:19(Laughter)
-
11:19 - 11:23"I can also do some Jackie Chan-motion,
martial art movements." -
11:23 - 11:25(Laughter)
-
11:26 - 11:28And it walks away. So this is DARwIn IV.
-
11:28 - 11:31Again, you'll be able
to see it in the lobby. -
11:31 - 11:34We truly believe this will be
the very first running humanoid robot -
11:34 - 11:35in the United States.
-
11:35 - 11:36So stay tuned.
-
11:36 - 11:39All right. So I showed you
some of our exciting robots at work. -
11:39 - 11:41So, what is the secret of our success?
-
11:41 - 11:43Where do we come up with these ideas?
-
11:43 - 11:45How do we develop these kinds of ideas?
-
11:45 - 11:47We have a fully autonomous vehicle
-
11:47 - 11:49that can drive into urban environments.
-
11:49 - 11:52We won a half a million dollars
in the DARPA Urban Challenge. -
11:52 - 11:55We also have the world's very first
vehicle that can be driven by the blind. -
11:55 - 11:58We call it the Blind Driver
Challenge, very exciting. -
11:58 - 12:01And many, many other robotics
projects I want to talk about. -
12:01 - 12:04These are just the awards
that we won in 2007 fall -
12:04 - 12:06from robotics competitions
and those kinds of things. -
12:06 - 12:08So really, we have five secrets.
-
12:08 - 12:11First is: Where do we get inspiration?
-
12:11 - 12:13Where do we get this spark of imagination?
-
12:13 - 12:15This is a true story, my personal story.
-
12:15 - 12:18At night, when I go to bed,
at three, four in the morning, -
12:18 - 12:21I lie down, close my eyes,
and I see these lines and circles -
12:21 - 12:22and different shapes floating around.
-
12:22 - 12:25And they assemble, and they form
these kinds of mechanisms. -
12:25 - 12:27And I think, "Ah, this is cool."
-
12:27 - 12:30So right next to my bed
I keep a notebook, a journal, -
12:30 - 12:32with a special pen
that has an LED light on it, -
12:32 - 12:35because I don't want to turn on the light
and wake up my wife. -
12:35 - 12:39So I see this, scribble everything down,
draw things, and go to bed. -
12:39 - 12:41Every day in the morning,
the first thing I do, -
12:41 - 12:44before my first cup of coffee,
before I brush my teeth, -
12:44 - 12:45I open my notebook.
-
12:45 - 12:47Many times it's empty;
sometimes I have something there. -
12:47 - 12:50If something's there, sometimes it's junk.
-
12:50 - 12:52But most of the time,
I can't read my handwriting. -
12:52 - 12:54Four in the morning --
what do you expect, right? -
12:54 - 12:56So I need to decipher what I wrote.
-
12:56 - 12:59But sometimes I see
this ingenious idea in there, -
12:59 - 13:01and I have this eureka moment.
-
13:01 - 13:03I directly run to my home office,
sit at my computer, -
13:03 - 13:05I type in the ideas, I sketch things out
-
13:05 - 13:07and I keep a database of ideas.
-
13:08 - 13:10So when we have these calls for proposals,
-
13:10 - 13:14I try to find a match
between my potential ideas -
13:14 - 13:15and the problem.
-
13:15 - 13:18If there's a match,
we write a research proposal, -
13:18 - 13:19get the research funding in,
-
13:19 - 13:21and that's how we start
our research programs. -
13:21 - 13:24But just a spark of imagination
is not good enough. -
13:24 - 13:25How do we develop these kinds of ideas?
-
13:26 - 13:28At our lab RoMeLa, the Robotics
and Mechanisms Laboratory, -
13:28 - 13:31we have these fantastic
brainstorming sessions. -
13:31 - 13:35So we gather around, we discuss problems
and solutions and talk about it. -
13:35 - 13:38But before we start,
we set this golden rule. -
13:38 - 13:40The rule is:
-
13:40 - 13:43nobody criticizes anybody's ideas.
-
13:43 - 13:45Nobody criticizes any opinion.
-
13:45 - 13:49This is important, because many times,
students fear or feel uncomfortable -
13:49 - 13:52about how others might think
about their opinions and thoughts. -
13:52 - 13:56So once you do this, it is amazing
how the students open up. -
13:56 - 13:59They have these wacky, cool,
crazy, brilliant ideas, -
13:59 - 14:03and the whole room is just electrified
with creative energy. -
14:03 - 14:05And this is how we develop our ideas.
-
14:06 - 14:07Well, we're running out of time.
-
14:07 - 14:09One more thing I want to talk about is,
-
14:09 - 14:12you know, just a spark of idea
and development is not good enough. -
14:12 - 14:17There was a great TED moment --
I think it was Sir Ken Robinson, was it? -
14:17 - 14:22He gave a talk about how education
and school kill creativity. -
14:22 - 14:24Well, actually,
there's two sides to the story. -
14:24 - 14:30So there is only so much one can do
with just ingenious ideas -
14:30 - 14:33and creativity
and good engineering intuition. -
14:33 - 14:34If you want to go beyond a tinkering,
-
14:35 - 14:37if you want to go
beyond a hobby of robotics -
14:37 - 14:40and really tackle
the grand challenges of robotics -
14:40 - 14:41through rigorous research,
-
14:41 - 14:43we need more than that.
-
14:43 - 14:45This is where school comes in.
-
14:45 - 14:47Batman, fighting against the bad guys,
-
14:47 - 14:50he has his utility belt,
he has his grappling hook, -
14:50 - 14:51he has all different kinds of gadgets.
-
14:51 - 14:54For us roboticists,
engineers and scientists, -
14:54 - 14:58these tools are the courses
and classes you take in class. -
14:58 - 15:00Math, differential equations.
-
15:00 - 15:03I have linear algebra, science, physics --
-
15:03 - 15:06even, nowadays, chemistry
and biology, as you've seen. -
15:06 - 15:08These are all the tools we need.
-
15:08 - 15:09So the more tools you have, for Batman,
-
15:10 - 15:11more effective at fighting the bad guys,
-
15:12 - 15:14for us, more tools to attack
these kinds of big problems. -
15:16 - 15:17So education is very important.
-
15:19 - 15:21Also -- it's not only about that.
-
15:21 - 15:23You also have to work really, really hard.
-
15:23 - 15:25So I always tell my students,
-
15:25 - 15:27"Work smart, then work hard."
-
15:27 - 15:30This picture in the back --
this is three in the morning. -
15:30 - 15:32I guarantee if you come
to our lab at 3, 4am, -
15:32 - 15:33we have students working there,
-
15:34 - 15:37not because I tell them to,
but because we are having too much fun. -
15:37 - 15:38Which leads to the last topic:
-
15:38 - 15:40do not forget to have fun.
-
15:40 - 15:44That's really the secret of our success,
we're having too much fun. -
15:44 - 15:47I truly believe that highest productivity
comes when you're having fun, -
15:47 - 15:48and that's what we're doing.
-
15:48 - 15:50And there you go.
-
15:50 - 15:51Thank you so much.
-
15:51 - 15:55(Applause)
- Title:
- My seven species of robot -- and how we created them
- Speaker:
- Dennis Hong
- Description:
-
At TEDxNASA, Dennis Hong introduces seven award-winning, all-terrain robots -- like the humanoid, soccer-playing DARwIn and the cliff-gripping CLIMBeR -- all built by his team at RoMeLa, Virginia Tech. Watch to the end to hear the five creative secrets to his lab's incredible technical success.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TEDTalks
- Duration:
- 15:57
Krystian Aparta commented on English subtitles for My seven species of robot -- and how we created them | ||
Krystian Aparta edited English subtitles for My seven species of robot -- and how we created them | ||
Krystian Aparta edited English subtitles for My seven species of robot -- and how we created them | ||
Brian Greene edited English subtitles for My seven species of robot -- and how we created them | ||
TED Translators admin edited English subtitles for My seven species of robot -- and how we created them | ||
TED edited English subtitles for My seven species of robot -- and how we created them | ||
TED added a translation |
Krystian Aparta
The English transcript was updated on 6/21/2017.