Tag Archives: position
#439053 Bipedal Robots Are Learning To Move With ...
Most humans are bipeds, but even the best of us are really only bipeds until things get tricky. While our legs may be our primary mobility system, there are lots of situations in which we leverage our arms as well, either passively to keep balance or actively when we put out a hand to steady ourselves on a nearby object. And despite how unstable bipedal robots tend to be, using anything besides legs for mobility has been a challenge in both software and hardware, a significant limitation in highly unstructured environments.
Roboticists from TUM in Germany (with support from the German Research Foundation) have recently given their humanoid robot LOLA some major upgrades to make this kind of multi-contact locomotion possible. While it’s still in the early stages, it’s already some of the most human-like bipedal locomotion we’ve seen.
It’s certainly possible for bipedal robots to walk over challenging terrain without using limbs for support, but I’m sure you can think of lots of times where using your arms to assist with your own bipedal mobility was a requirement. It’s not a requirement because your leg strength or coordination or sense of balance is bad, necessarily. It’s just that sometimes, you might find yourself walking across something that’s highly unstable or in a situation where the consequences of a stumble are exceptionally high. And it may not even matter how much sensing you do beforehand, and how careful you are with your footstep planning: there are limits to how much you can know about your environment beforehand, and that can result in having a really bad time of it. This is why using multi-contact locomotion, whether it’s planned in advance or not, is a useful skill for humans, and should be for robots, too.
As the video notes (and props for being explicit up front about it), this isn’t yet fully autonomous behavior, with foot positions and arm contact points set by hand in advance. But it’s not much of a stretch to see how everything could be done autonomously, since one of the really hard parts (using multiple contact points to dynamically balance a moving robot) is being done onboard and in real time.
Getting LOLA to be able to do this required a major overhaul in hardware as well as software. And Philipp Seiwald, who works with LOLA at TUM, was able to tell us more about it.
IEEE Spectrum: Can you summarize the changes to LOLA’s hardware that are required for multi-contact locomotion?
Philipp Seiwald: The original version of LOLA has been designed for fast biped walking. Although it had two arms, they were not meant to get into contact with the environment but rather to compensate for the dynamic effects of the feet during fast walking. Also, the torso had a relatively simple design that was fine for its original purpose; however, it was not conceived to withstand the high loads coming from the hands during multi-contact maneuvers. Thus, we redesigned the complete upper body of LOLA from scratch. Starting from the pelvis, the strength and stiffness of the torso have been increased. We used the finite element method to optimize critical parts to obtain maximum strength at minimum weight. Moreover, we added additional degrees of freedom to the arms to increase the hands' reachable workspace. The kinematic topology of the arms, i.e., the arrangement of joints and link lengths, has been obtained from an optimization that takes typical multi-contact scenarios into account.
Why is this an important problem for bipedal humanoid robots?
Maintaining balance during locomotion can be considered the primary goal of legged robots. Naturally, this task is more challenging for bipeds when compared to robots with four or even more legs. Although current high-end prototypes show impressive progress, humanoid robots still do not have the robustness and versatility they need for most real-world applications. With our research, we try to contribute to this field and help to push the limits further. Recently, we showed our latest work on walking over uneven terrain without multi-contact support. Although the robustness is already high, there still exist scenarios, such as walking on loose objects, where the robot's stabilization fails when using only foot contacts. The use of additional hand-environment support during this (comparatively) fast walking allows a further significant increase in robustness, i.e., the robot's capability to compensate disturbances, modeling errors, or inaccurate sensor input. Besides stabilization on uneven terrain, multi-contact locomotion also enables more complex motions, e.g., stepping over a tall obstacle or toe-only contacts, as shown in our latest multi-contact video.
How can LOLA decide whether a surface is suitable for multi-contact locomotion?
LOLA’s visual perception system is currently developed by our project partners from the Chair for Computer Aided Medical Procedures & Augmented Reality at the TUM. This system relies on a novel semantic Simultaneous Localization and Mapping (SLAM) pipeline that can robustly extract the scene's semantic components (like floor, walls, and objects therein) by merging multiple observations from different viewpoints and by inferring therefrom the underlying scene graph. This provides a reliable estimate of which scene parts can be used to support the locomotion, based on the assumption that certain structural elements such as walls are fixed, while chairs, for example, are not.
Also, the team plans to develop a specific dataset with annotations further describing the attributes of the object (such as roughness of the surface or its softness) and that will be used to master multi-contact locomotion in even more complex scenes. As of today, the vision and navigation system is not finished yet; thus, in our latest video, we used pre-defined footholds and contact points for the hands. However, within our collaboration, we are working towards a fully integrated and autonomous system.
Is LOLA capable of both proactive and reactive multi-contact locomotion?
The software framework of LOLA has a hierarchical structure. On the highest level, the vision system generates an environment model and estimates the 6D-pose of the robot in the scene. The walking pattern generator then uses this information to plan a dynamically feasible future motion that will lead LOLA to a target position defined by the user. On a lower level, the stabilization module modifies this plan to compensate for model errors or any kind of disturbance and keep overall balance. So our approach currently focuses on proactive multi-contact locomotion. However, we also plan to work on a more reactive behavior such that additional hand support can also be triggered by an unexpected disturbance instead of being planned in advance.
What are some examples of unique capabilities that you are working towards with LOLA?
One of the main goals for the research with LOLA remains fast, autonomous, and robust locomotion on complex, uneven terrain. We aim to reach a walking speed similar to humans. Currently, LOLA can do multi-contact locomotion and cross uneven terrain at a speed of 1.8 km/h, which is comparably fast for a biped robot but still slow for a human. On flat ground, LOLA's high-end hardware allows it to walk at a relatively high maximum speed of 3.38 km/h.
Fully autonomous multi-contact locomotion for a life-sized humanoid robot is a tough task. As algorithms get more complex, computation time increases, which often results in offline motion planning methods. For LOLA, we restrict ourselves to gaited multi-contact locomotion, which means that we try to preserve the core characteristics of bipedal gait and use the arms only for assistance. This allows us to use simplified models of the robot which lead to very efficient algorithms running in real-time and fully onboard.
A long-term scientific goal with LOLA is to understand essential components and control policies of human walking. LOLA's leg kinematics is relatively similar to the human body. Together with scientists from kinesiology, we try to identify similarities and differences between observed human walking and LOLA’s “engineered” walking gait. We hope this research leads, on the one hand, to new ideas for the control of bipeds, and on the other hand, shows via experiments on bipeds if biomechanical models for the human gait are correctly understood. For a comparison of control policies on uneven terrain, LOLA must be able to walk at comparable speeds, which also motivates our research on fast and robust walking.
While it makes sense why the researchers are using LOLA’s arms primarily to assist with a conventional biped gait, looking ahead a bit it’s interesting to think about how robots that we typically consider to be bipeds could potentially leverage their limbs for mobility in decidedly non-human ways.
We’re used to legged robots being one particular morphology, I guess because associating them with either humans or dogs or whatever is just a comfortable way to do it, but there’s no particular reason why a robot with four limbs has to choose between being a quadruped and being a biped with arms, or some hybrid between the two, depending on what its task is. The research being done with LOLA could be a step in that direction, and maybe a hand on the wall in that direction, too. Continue reading
Posted in Human Robots
#438762 When Robots Enter the World, Who Is ...
Over the last half decade or so, the commercialization of autonomous robots that can operate outside of structured environments has dramatically increased. But this relatively new transition of robotic technologies from research projects to commercial products comes with its share of challenges, many of which relate to the rapidly increasing visibility that these robots have in society.
Whether it's because of their appearance of agency, or because of their history in popular culture, robots frequently inspire people’s imagination. Sometimes this is a good thing, like when it leads to innovative new use cases. And sometimes this is a bad thing, like when it leads to use cases that could be classified as irresponsible or unethical. Can the people selling robots do anything about the latter? And even if they can, should they?
Roboticists understand that robots, fundamentally, are tools. We build them, we program them, and even the autonomous ones are just following the instructions that we’ve coded into them. However, that same appearance of agency that makes robots so compelling means that it may not be clear to people without much experience with or exposure to real robots that a robot itself isn’t inherently good or bad—rather, as a tool, a robot is a reflection of its designers and users.
This can put robotics companies into a difficult position. When they sell a robot to someone, that person can, hypothetically, use the robot in any way they want. Of course, this is the case with every tool, but it’s the autonomous aspect that makes robots unique. I would argue that autonomy brings with it an implied association between a robot and its maker, or in this case, the company that develops and sells it. I’m not saying that this association is necessarily a reasonable one, but I think that it exists, even if that robot has been sold to someone else who has assumed full control over everything it does.
“All of our buyers, without exception, must agree that Spot will not be used to harm or intimidate people or animals, as a weapon or configured to hold a weapon”
—Robert Playter, Boston Dynamics
Robotics companies are certainly aware of this, because many of them are very careful about who they sell their robots to, and very explicit about what they want their robots to be doing. But once a robot is out in the wild, as it were, how far should that responsibility extend? And realistically, how far can it extend? Should robotics companies be held accountable for what their robots do in the world, or should we accept that once a robot is sold to someone else, responsibility is transferred as well? And what can be done if a robot is being used in an irresponsible or unethical way that could have a negative impact on the robotics community?
For perspective on this, we contacted folks from three different robotics companies, each of which has experience selling distinctive mobile robots to commercial end users. We asked them the same five questions about the responsibility that robotics companies have regarding the robots that they sell, and here’s what they had to say:
Do you have any restrictions on what people can do with your robots? If so, what are they, and if not, why not?
Péter Fankhauser, CEO, ANYbotics:
We closely work together with our customers to make sure that our solution provides the right approach for their problem. Thereby, the target use case is clear from the beginning and we do not work with customers interested in using our robot ANYmal outside the intended target applications. Specifically, we strictly exclude any military or weaponized uses and since the foundation of ANYbotics it is close to our heart to make human work easier, safer, and more enjoyable.
Robert Playter, CEO, Boston Dynamics:
Yes, we have restrictions on what people can do with our robots, which are outlined in our Terms and Conditions of Sale. All of our buyers, without exception, must agree that Spot will not be used to harm or intimidate people or animals, as a weapon or configured to hold a weapon. Spot, just like any product, must be used in compliance with the law.
Ryan Gariepy, CTO, Clearpath Robotics:
We do have strict restrictions and KYC processes which are based primarily on Canadian export control regulations. They depend on the type of equipment sold as well as where it is going. More generally, we also will not sell or support a robot if we know that it will create an uncontrolled safety hazard or if we have reason to believe that the buyer is unqualified to use the product. And, as always, we do not support using our products for the development of fully autonomous weapons systems.
More broadly, if you sell someone a robot, why should they be restricted in what they can do with it?
Péter Fankhauser, ANYbotics: We see the robot less as a simple object but more as an artificial workforce. This implies to us that the usage is closely coupled with the transfer of the robot and both the customer and the provider agree what the robot is expected to do. This approach is supported by what we hear from our customers with an increasing interest to pay for the robots as a service or per use.
Robert Playter, Boston Dynamics: We’re offering a product for sale. We’re going to do the best we can to stop bad actors from using our technology for harm, but we don’t have the control to regulate every use. That said, we believe that our business will be best served if our technology is used for peaceful purposes—to work alongside people as trusted assistants and remove them from harm’s way. We do not want to see our technology used to cause harm or promote violence. Our restrictions are similar to those of other manufacturers or technology companies that take steps to reduce or eliminate the violent or unlawful use of their products.
Ryan Gariepy, Clearpath Robotics: Assuming the organization doing the restricting is a private organization and the robot and its software is sold vs. leased or “managed,” there aren't strong legal reasons to restrict use. That being said, the manufacturer likewise has no obligation to continue supporting that specific robot or customer going forward. However, given that we are only at the very edge of how robots will reshape a great deal of society, it is in the best interest for the manufacturer and user to be honest with each other about their respective goals. Right now, you're not only investing in the initial purchase and relationship, you're investing in the promise of how you can help each other succeed in the future.
“If a robot is being used in a way that is irresponsible due to safety: intervene! If it’s unethical: speak up!”
—Péter Fankhauser, ANYbotics
What can you realistically do to make sure that people who buy your robots use them in the ways that you intend?
Péter Fankhauser, ANYbotics: We maintain a close collaboration with our customers to ensure their success with our solution. So for us, we have refrained from technical solutions to block unintended use.
Robert Playter, Boston Dynamics: We vet our customers to make sure that their desired applications are things that Spot can support, and are in alignment with our Terms and Conditions of Sale. We’ve turned away customers whose applications aren’t a good match with our technology. If customers misuse our technology, we’re clear in our Terms of Sale that their violations may void our warranty and prevent their robots from being updated, serviced, repaired, or replaced. We may also repossess robots that are not purchased, but leased. Finally, we will refuse future sales to customers that violate our Terms of Sale.
Ryan Gariepy, Clearpath Robotics: We typically work with our clients ahead of the purchase to make sure their expectations match reality, in particular on aspects like safety, supervisory requirements, and usability. It's far worse to sell a robot that'll sit on a shelf or worse, cause harm, then to not sell a robot at all, so we prefer to reduce the risk of this situation in advance of receiving an order or shipping a robot.
How do you evaluate the merit of edge cases, for example if someone wants to use your robot in research or art that may push the boundaries of what you personally think is responsible or ethical?
Péter Fankhauser, ANYbotics: It’s about the dialog, understanding, and figuring out alternatives that work for all involved parties and the earlier you can have this dialog the better.
Robert Playter, Boston Dynamics: There’s a clear line between exploring robots in research and art, and using the robot for violent or illegal purposes.
Ryan Gariepy, Clearpath Robotics: We have sold thousands of robots to hundreds of clients, and I do not recall the last situation that was not covered by a combination of export control and a general evaluation of the client's goals and expectations. I'm sure this will change as robots continue to drop in price and increase in flexibility and usability.
“You're not only investing in the initial purchase and relationship, you're investing in the promise of how you can help each other succeed in the future.”
—Ryan Gariepy, Clearpath Robotics
What should roboticists do if we see a robot being used in a way that we feel is unethical or irresponsible?
Péter Fankhauser, ANYbotics: If it’s irresponsible due to safety: intervene! If it’s unethical: speak up!
Robert Playter, Boston Dynamics: We want robots to be beneficial for humanity, which includes the notion of not causing harm. As an industry, we think robots will achieve long-term commercial viability only if people see robots as helpful, beneficial tools without worrying if they’re going to cause harm.
Ryan Gariepy, Clearpath Robotics: On a one off basis, they should speak to a combination of the user, the supplier or suppliers, the media, and, if safety is an immediate concern, regulatory or government agencies. If the situation in question risks becoming commonplace and is not being taken seriously, they should speak up more generally in appropriate forums—conferences, industry groups, standards bodies, and the like.
As more and more robots representing different capabilities become commercially available, these issues are likely to come up more frequently. The three companies we talked to certainly don’t represent every viewpoint, and we did reach out to other companies who declined to comment. But I would think (I would hope?) that everyone in the robotics community can agree that robots should be used in a way that makes people’s lives better. What “better” means in the context of art and research and even robots in the military may not always be easy to define, and inevitably there’ll be disagreement as to what is ethical and responsible, and what isn’t.
We’ll keep on talking about it, though, and do our best to help the robotics community to continue growing and evolving in a positive way. Let us know what you think in the comments. Continue reading
Posted in Human Robots
#438553 New Drone Software Handles Motor ...
Good as some drones are becoming at obstacle avoidance, accidents do still happen. And as far as robots go, drones are very much on the fragile side of things. Any sort of significant contact between a drone and almost anything else usually results in a catastrophic, out-of-control spin followed by a death plunge to the ground. Bad times. Bad, expensive times.
A few years ago, we saw some interesting research into software that can keep the most common drone form factor, the quadrotor, aloft and controllable even after the failure of one motor. The big caveat to that software was that it relied on GPS for state estimation, meaning that without a GPS signal, the drone is unable to get the information it needs to keep itself under control. In a paper recently accepted to RA-L, researchers at the University of Zurich report that they have developed a vision-based system that brings state estimation completely on-board. The upshot: potentially any drone with some software and a camera can keep itself safe even under the most challenging conditions.
A few years ago, we wrote about first author Sihao Sun’s work on high speed controlled flight of a quadrotor with a non-functional motor. But that innovation relied on an external motion capture system. Since then, Sun has moved from Tu Delft to Davide Scaramuzza’s lab at UZH, and it looks like he’s been able to combine his work on controlled spinning flight with the Robotics and Perception Group’s expertise in vision. Now, a downward-facing camera is all it takes for a spinning drone to remain stable and controllable:
Remember, this software isn’t just about guarding against motor failure. Drone motors themselves don’t just up and fail all that often, either with respect to their software or hardware. But they do represent the most likely point of failure for any drone, usually because when you run into something, what ultimately causes your drone to crash is damage to a motor or a propeller that causes loss of control.
The reason that earlier solutions relied on GPS was because the spinning drone needs a method of state estimation—that is, in order to be closed-loop controllable, the drone needs to have a reasonable understanding of what its position is and how that position is changing over time. GPS is an easy way to take care of this, but GPS is also an external system that doesn’t work everywhere. Having a state estimation system that’s completely internal to the drone itself is much more fail safe, and Sun got his onboard system to work through visual feature tracking with a downward-facing camera, even as the drone is spinning at over 20 rad/s.
While the system works well enough with a regular downward-facing camera—something that many consumer drones are equipped with for stabilization purposes—replacing it with an event camera (you remember event cameras, right?) makes the performance even better, especially in low light.
For more details on this, including what you’re supposed to do with a rapidly spinning partially disabled quadrotor (as well as what it’ll take to make this a standard feature on consumer hardware), we spoke with Sihao Sun via email.
IEEE Spectrum: what usually happens when a drone spinning this fast lands? Is there any way to do it safely?
Sihao Sun: Our experience shows that we can safely land the drone while it is spinning. When the range sensor measurements are lower than a threshold (around 10 cm, indicating that the drone is close to the ground), we switch off the rotors. During the landing procedure, despite the fast spinning motion, the thrust direction oscillates around the gravity vector, thus the drone touches the ground with its legs without damaging other components.
Can your system handle more than one motor failure?
Yes, the system can also handle the failure of two opposing rotors. However, if two adjacent rotors or more than two rotors fail, our method cannot save the quadrotor. Some research has shown that it is possible to control a quadrotor with only one remaining rotor. But the drone requires a very special inertial property, which is hard to satisfy in real applications.
How different is your system's performance from a similar system that relies on GPS, in a favorable environment?
In a favorable environment, our system outperforms those relying on GPS signals because it obtains better position estimates. Since a damaged quadrotor spins fast, the accelerometer readings are largely affected by centrifugal forces. When the GPS signal is lost or degraded, a drone relying on GPS needs to integrate these biased accelerometer measurements for position estimation, leading to large position estimation errors. Feeding these erroneous estimates to the flight controller can easily crash the drone.
When you say that your solution requires “only onboard sensors and computation,” are those requirements specialized, or would they be generally compatible with the current generation of recreational and commercial quadrotors?
We use an NVIDIA Jetson TX2 to run our solution, which includes two parts: the control algorithm and the vision-based state estimation algorithm. The control algorithm is lightweight; thus, we believe that it is compatible with the current generation of quadrotors. On the other hand, the vision-based state estimation requires relatively more computational resources, which may not be affordable for cheap recreational platforms. But this is not an issue for commercial quadrotors because many of them have more powerful processors than a TX2.
What else can event cameras be used for, in recreational or commercial applications?
Many drone applications can benefit from event cameras, especially those in high-speed or low-light conditions, such as autonomous drone racing, cave exploration, drone delivery during night time, etc. Event cameras also consume very little power, which is a significant advantage for energy-critical missions, such as planetary aerial vehicles for Mars explorations. Regarding space applications, we are currently collaborating with JPL to explore the use of event cameras to address the key limitations of standard cameras for the next Mars helicopter.
[ UZH RPG ] Continue reading
Posted in Human Robots