France Developing Advanced Humanoid Robot Romeo

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Romeo, shown here in a computer-generated rendering, is a French humanoid robot designed to assist elderly and disabled people. Image: Aldebaran Robotics

France is set to join the select club of countries that have developed advanced adult-size humanoid robots.

Paris-based Aldebaran Robotics, famed for its small humanoid robot Nao, is working with major French research organizations to build a larger and more capable humanoid called Romeo, to be unveiled next March.

Designed to assist elderly and disabled individuals in their daily activities, the 1.4-meter-tall robot will be able to walk through a home, fetching food from the kitchen, taking out the garbage, and acting as a loyal companion who helps entertain its owners and keep tabs on their health.

Expected to cost about 250,000 euros, Romeo will be available first to partners in the project and university researchers. An improved version will later be offered to hospitals and nursing homes, and after that to individuals as well.

Aldebaran claims that Romeo, weighing in at 40 kilograms, will introduce several innovations, including a four-vertebra backbone, articulated feet, a partially soft torso, a composite leg exoskeleton, and a new kind of actuator that lets the robot control its limbs in a safer way.

The company also says it's putting a lot of emphasis on the robot's communication capabilities. “We want people to interact with Romeo using just natural speech and gestures,” Bruno Maisonnier, founder and CEO of Aldebaran, told me at the IEEE Humanoids 2010 conference in Nashville, Tenn., last week.

The Romeo project, which started in early 2009, involves 13 partners and has a budget of 10 million euros, half of which comes from federal and local French governments.

The robot will have 37 degrees of freedom, including 2 DOF for each eye, 1 DOF for each foot, and 3 DOF for the backbone. An advanced type of actuator known as a backdrivable mechanism, which uses motors coupled to screws and cables rather than reduction gears, will power the joints. This mechanism can sense forces on the limbs and move them more safely.

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A computer-generated rendering shows Romeo doing chores at a home. Image: Aldebaran Robotics

To learn more about the project, I spoke to Rodolphe Gelin, head of cooperative projects at Aldebaran and one of the engineers leading the development of Romeo.

Below is my full interview with Gelin, in which he describes the current status of the project, the applications Aldebaran envisions for the robot, and details about its technology.

Erico Guizzo: Colin Angle, one of the founders of iRobot, said in a recent interview that he doesn’t believe that people will have humanoid robots in their homes. I guess he likes his Roombas… Why build a human-shaped robot?

Rodolphe Gelin: My ideas about this are changing regularly. So I’ll give you my opinion today. I think that a humanoid robot is very useful if you want to have a multipurpose robot. If you only want to have a vacuum cleaner, it’s good enough to have a little cylinder robot. But if you want a robot that can open the refrigerator, grab a bottle of water, pour water into a cup, and take the cup to another room, being a little cylinder is not very helpful. If you want to do plenty of things, then you have to have plenty of robots, or one robot able to do lots of things. There’s also human-robot interaction issues. I think that people will find a humanoid much easier to use and much more fun than a Roomba or a kind of box on wheels robot. Many people don’t want just a slave robot; they want a machine that works like a companion, and so it's helpful if your robot has a certain height and a face that people can look at and talk to in a natural way. That’s why a humanoid shape is interesting. Does it need legs? We’ve discussed that a lot. Legs and wheels both have advantages and disadvantages. We decided to use legs because we think it’s more convenient and adaptable for most situations. And also because it's a big technological challenge. But that's my answer today. It may change tomorrow!

EG: What are some of the things you envision Romeo doing? Will it be able to do tasks that other humanoid robots can’t do today?

RG: We have some scenarios. For example, imagine that Mr. Smith lives alone and has a Romeo in his house. Because Mr. Smith is elderly, he might forget where things are, like his glasses or the remote control of the TV. But the robot can constantly keep track of these objects, using its vision, and it doesn’t forget where they are. So Romeo can assist Mr. Smith to find objects and even go get them for him. The robot is also monitoring Mr. Smith himself, checking that he’s feeling okay, and if not, calling family members or medical assistance. We’re also working on more physically challenging tasks. Imagine that Mr. Smith asks Romeo to take the garbage out and the robot has to grab a 5-kilogram bag and walk down the stairs with it. Or imagine that Mr. Smith needs help to stand up and walk. Above all, we’re putting a lot of emphasis on Romeo’s communication functions. We want a robot that is easy to use and that, unlike other robots, doesn't look dangerous.

EG: There are lots of humanoid robots out there, both small and large, and their technology has been advancing fast. How did Aldebaran go about designing Romeo? Is it essentially an enlarged version of Nao?

aldebaran romeo legRG: No. The things we’re learning with Nao are helping us with Romeo and vice versa, so there’s a lot of synergy between the two projects. In fact, from the software point of view, most code will be compatible between the two and both will use our Coregraph program to create movements and behaviors. But in terms of hardware, they are very different robots. You can’t simply transform a small robot into a bigger one because variables like power, mechanical strength, and other things don’t scale in the same way. One thing that is very different compared to other humanoids is how Romeo controls its leg actuators. Japanese robots like the HRP use position control: You control the position and speed of each joint but you can’t control the force or torque. Other robots [like Justin, developed at DLR in Germany] are capable of controlling force, but they rely on very fast and accurate—and expensive—force sensors in each joint. In our approach, based on technology developed at CEA [France’s Alternative Energies and Atomic Energy Commission], we don’t need a force sensor; we only have what is called a backdrivable mechanism. It means a mechanism that can convert electrical current into motion but also motion into current. To do that you need a mechanism with very low friction, so energy losses are very small. Then by reading the current in the actuator you’re able to compute the torque applied by the robot on the environment. For Romeo we designed a system of screws and cables with very low friction and inertia [image, right].

EG: Why did you decide to use this approach and how unique is it? Are there other robots using this?

RG: Researchers we spoke to complained that if you can’t control the force and  torque in each joint, you don’t truly control what you want to do with the robot. That becomes critical when the robot is big, because of the damage it can cause. So from both a control and safety point of view, controlling torque rather than just position is very important. The WAM arm from Barrett Technology uses a backdrivable mechanism. But most humanoid robots use motor and gears to power their joints, and these mechanisms are not backdrivable—due to energy losses in the gears and you can’t relate the electrical current in the motors to force. That’s why they need force sensors if you want to move in a compliant way; it’s called active compliance. Romeo is different. It has no gears. We transmit the motion from the motors to the joints using screws and cables. This system is backdrivable. We can measure the torque applied by the arm of the robot only by reading the electrical currents in the motors. It’s passively and intrinsically compliant. We think that this approach is better because it offers more control and is safer and cheaper.


Romeo's upper torso and head. Image: Aldebaran Robotics 

EG: In terms of walking strategies, are you using the traditional ZMP [zero moment point] approach that most other humanoid robots use?

RG: You have to take ZMP into account, or your robot will fall. But what we’re doing differently is that we want to have a top-down approach to the walking algorithm. In the classical approach, say you’re in the living room and you want to go to the kitchen; first you plan where you have to put your feet for each step going from the living room to the kitchen and then the robot will try to put its feet in the footprints it planned. And if the robot encounters an obstacle, it has to stop and compute new footprints to avoid the obstacle. In our approach—and this is something that other top labs are also pursuing—the robot walks by relying on a real-time pattern generator. Basically the robot uses its vision system to decide where it wants to go and then it just walks in that direction, adjusting its walking in real time. It’s a more reactive and realistic way of implementing walking. In fact, vision will be Romeo’s main sensing capability. It has two cameras to do simultaneous localization and mapping, or SLAM. Basically the robot can recognize where it is and navigate from room to room.

EG: Will the robot be capable of performing dexterous manipulation as well?

RG: Romeo’s hand has four fingers and one degree of freedom. The hand can perform a basic grasping motion and grasp objects like a cup on a table or place a dish inside the oven. Of course we’d like to have more dexterous hands. But that would have made the budget too expensive. So we’re leaving manipulation for a future phase of the project, when we may implement things like tactile sensors and force control on the hands.

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With three fingers and one thumb, Romeo's hand will be able to grasp objects like cups and plates. Image: Aldebaran Robotics

EG: Open source robotics is gaining momentum. Do you plan to release any part of Romeo’s software as open source?

RG: From a commercial point of view, we’re exploring different business models and at this point we can’t say Romeo is open source. But like with the Nao, we’ll release a SDK [software development kit] that will provide libraries and functions to those interested in programming Romeo. So Romeo is an open platform in the sense that there are APIs to to control the robot.

EG: When will Romeo be available and how much will it cost?

RG: We have completed the design of all the mechanics of the robot—the legs, arms, torso, neck, and head. The head is already built and we’re expecting the parts to assemble the legs and the arms. We should have a full body prototype sometime early next year. The robot will cost about 250,000 euros. This is not a final price tag; it’s just an order of magnitude. A lot of things can change. We’d really like to tell the world that if you want to buy a humanoid robot, you don’t have to buy a Japanese one, there are other good choices available. We want to be one of these choices. It’s a challenge, because Japan has very strong products. But we want to be considered a competitor in this area. Romeo will initially be a research tool for university labs and our partners in the project. With time, we plan to improve the robot and transform into a more reliable and affordable product that we can offer to hospitals and nursing homes. After that we’d sell it to individuals for personal use. We hope that one day anyone can have a Romeo as a companion at home.

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A prototype of Romeo's head. Image: Aldebaran Robotics

This interview has been edited and condensed.

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