Header logo is


2012


no image
Model Learning and Real-Time Tracking Using Multi-Resolution Surfel Maps

Stueckler, J., Behnke, S.

Proceedings of the AAAI Conference on Artificial Intelligence (AAAI), 2012 (conference)

ev

link (url) [BibTex]

2012


link (url) [BibTex]


Development of a Minimalistic Pneumatic Quadruped Robot for Fast Locomotion
Development of a Minimalistic Pneumatic Quadruped Robot for Fast Locomotion

Narioka, K., Rosendo, A., Spröwitz, A., Hosoda, K.

In Proceedings of the 2012 IEEE International Conference on Robotics and Biomimetics (ROBIO), 2012, pages: 307-311, IEEE, Guangzhou, 2012 (inproceedings)

Abstract
In this paper, we describe the development of the quadruped robot ”Ken” with the minimalistic and lightweight body design for achieving fast locomotion. We use McKibben pneumatic artificial muscles as actuators, providing high frequency and wide stride motion of limbs, also avoiding problems with overheating. We conducted a preliminary experiment, finding out that the robot can swing its limb over 7.5 Hz without amplitude reduction, nor heat problems. Moreover, the robot realized a several steps of bouncing gait by using simple CPG-based open loop controller, indicating that the robot can generate enough torque to kick the ground and limb contraction to avoid stumbling.

dlg

DOI [BibTex]

DOI [BibTex]


Locomotion through Reconfiguration based on Motor Primitives for Roombots Self-Reconfigurable Modular Robots
Locomotion through Reconfiguration based on Motor Primitives for Roombots Self-Reconfigurable Modular Robots

Bonardi, S., Moeckel, R., Spröwitz, A., Vespignani, M., Ijspeert, A. J.

In Robotics; Proceedings of ROBOTIK 2012; 7th German Conference on, pages: 1-6, 2012 (inproceedings)

Abstract
We present the hardware and reconfiguration experiments for an autonomous self-reconfigurable modular robot called Roombots (RB). RB were designed to form the basis for self-reconfigurable furniture. Each RB module contains three degrees of freedom that have been carefully selected to allow a single module to reach any position on a 2-dimensional grid and to overcome concave corners in a 3-dimensional grid. For the first time we demonstrate locomotion capabilities of single RB modules through reconfiguration with real hardware. The locomotion through reconfiguration is controlled by a planner combining the well-known D* algorithm and composed motor primitives. The novelty of our approach is the use of an online running hierarchical planner closely linked to the real hardware.

dlg

link (url) [BibTex]

link (url) [BibTex]


no image
RoboCup@Home: Demonstrating Everyday Manipulation Skills in RoboCup@Home

Stueckler, J., Holz, D., Behnke, S.

IEEE Robotics and Automation Magazine (RAM), 19(2):34-42, 2012 (article)

ev

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Towards Robust Mobility, Flexible Object Manipulation, and Intuitive Multimodal Interaction for Domestic Service Robots

Stueckler, J., Droeschel, D., Gräve, K., Holz, D., Kläß, J., Schreiber, M., Steffens, R., Behnke, S.

In RoboCup 2011, Robot Soccer World Cup XV, pages: 51-62, Springer, 2012 (inbook)

ev

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Encoding of Periodic and their Transient Motions by a Single Dynamic Movement Primitive

Ernesti, J., Righetti, L., Do, M., Asfour, T., Schaal, S.

In 2012 12th IEEE-RAS International Conference on Humanoid Robots (Humanoids 2012), pages: 57-64, IEEE, Osaka, Japan, November 2012 (inproceedings)

am mg

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Bayesian calibration of the hand-eye kinematics of an anthropomorphic robot

Hubert, U., Stueckler, J., Behnke, S.

In Proc. of the 12th IEEE-RAS Int. Conf. on Humanoid Robots (Humanoids), pages: 618-624, November 2012 (inproceedings)

ev

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Shape-Primitive Based Object Recognition and Grasping

Nieuwenhuisen, M., Stueckler, J., Berner, A., Klein, R., Behnke, S.

In Proc. of ROBOTIK, VDE-Verlag, 2012 (inproceedings)

ev

link (url) [BibTex]

link (url) [BibTex]


no image
Learning Force Control Policies for Compliant Robotic Manipulation

Kalakrishnan, M., Righetti, L., Pastor, P., Schaal, S.

In ICML’12 Proceedings of the 29th International Coference on International Conference on Machine Learning, pages: 49-50, Edinburgh, Scotland, 2012 (inproceedings)

am mg

[BibTex]

[BibTex]


no image
Semantic mapping using object-class segmentation of RGB-D images

Stueckler, J., Biresev, N., Behnke, S.

In Proc. of the IEEE/RSJ Int. Conf. on Intelligent Robots and Systems (IROS), pages: 3005-3010, October 2012 (inproceedings)

ev

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Efficient Mobile Robot Navigation using 3D Surfel Grid Maps

Kläß, J., Stueckler, J., Behnke, S.

In Proc. of ROBOTIK, VDE-Verlag, 2012 (inproceedings)

ev

link (url) [BibTex]

link (url) [BibTex]


no image
Quadratic programming for inverse dynamics with optimal distribution of contact forces

Righetti, L., Schaal, S.

In 2012 12th IEEE-RAS International Conference on Humanoid Robots (Humanoids 2012), pages: 538-543, IEEE, Osaka, Japan, November 2012 (inproceedings)

Abstract
In this contribution we propose an inverse dynamics controller for a humanoid robot that exploits torque redundancy to minimize any combination of linear and quadratic costs in the contact forces and the commands. In addition the controller satisfies linear equality and inequality constraints in the contact forces and the commands such as torque limits, unilateral contacts or friction cones limits. The originality of our approach resides in the formulation of the problem as a quadratic program where we only need to solve for the control commands and where the contact forces are optimized implicitly. Furthermore, we do not need a structured representation of the dynamics of the robot (i.e. an explicit computation of the inertia matrix). It is in contrast with existing methods based on quadratic programs. The controller is then robust to uncertainty in the estimation of the dynamics model and the optimization is fast enough to be implemented in high bandwidth torque control loops that are increasingly available on humanoid platforms. We demonstrate properties of our controller with simulations of a human size humanoid robot.

am mg

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Integrating depth and color cues for dense multi-resolution scene mapping using RGB-D cameras

Stueckler, J., Behnke, S.

In Proc. of the IEEE Int. Conf. on Multisensor Fusion and Integration for Intelligent Systems (MFI), pages: 162-167, sep 2012 (inproceedings)

ev

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
SURE: Surface Entropy for Distinctive 3D Features

Fiolka, T., Stueckler, J., Klein, D. A., Schulz, D., Behnke, S.

In Proc. of Spatial Cognition, 2012 (inproceedings)

ev

link (url) [BibTex]

link (url) [BibTex]


no image
Robust Real-Time Registration of RGB-D Images using Multi-Resolution Surfel Representations

Stueckler, J., Behnke, S.

In Proc. of ROBOTIK, VDE-Verlag, 2012 (inproceedings)

ev

link (url) [BibTex]

link (url) [BibTex]


no image
Towards Associative Skill Memories

Pastor, P., Kalakrishnan, M., Righetti, L., Schaal, S.

In 2012 12th IEEE-RAS International Conference on Humanoid Robots (Humanoids 2012), pages: 309-315, IEEE, Osaka, Japan, November 2012 (inproceedings)

Abstract
Movement primitives as basis of movement planning and control have become a popular topic in recent years. The key idea of movement primitives is that a rather small set of stereotypical movements should suffice to create a large set of complex manipulation skills. An interesting side effect of stereotypical movement is that it also creates stereotypical sensory events, e.g., in terms of kinesthetic variables, haptic variables, or, if processed appropriately, visual variables. Thus, a movement primitive executed towards a particular object in the environment will associate a large number of sensory variables that are typical for this manipulation skill. These association can be used to increase robustness towards perturbations, and they also allow failure detection and switching towards other behaviors. We call such movement primitives augmented with sensory associations Associative Skill Memories (ASM). This paper addresses how ASMs can be acquired by imitation learning and how they can create robust manipulation skill by determining subsequent ASMs online to achieve a particular manipulation goal. Evaluation for grasping and manipulation with a Barrett WAM/Hand illustrate our approach.

am mg

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Template-based learning of grasp selection

Herzog, A., Pastor, P., Kalakrishnan, M., Righetti, L., Asfour, T., Schaal, S.

In 2012 IEEE International Conference on Robotics and Automation, pages: 2379-2384, IEEE, Saint Paul, USA, 2012 (inproceedings)

Abstract
The ability to grasp unknown objects is an important skill for personal robots, which has been addressed by many present and past research projects, but still remains an open problem. A crucial aspect of grasping is choosing an appropriate grasp configuration, i.e. the 6d pose of the hand relative to the object and its finger configuration. Finding feasible grasp configurations for novel objects, however, is challenging because of the huge variety in shape and size of these objects. Moreover, possible configurations also depend on the specific kinematics of the robotic arm and hand in use. In this paper, we introduce a new grasp selection algorithm able to find object grasp poses based on previously demonstrated grasps. Assuming that objects with similar shapes can be grasped in a similar way, we associate to each demonstrated grasp a grasp template. The template is a local shape descriptor for a possible grasp pose and is constructed using 3d information from depth sensors. For each new object to grasp, the algorithm then finds the best grasp candidate in the library of templates. The grasp selection is also able to improve over time using the information of previous grasp attempts to adapt the ranking of the templates. We tested the algorithm on two different platforms, the Willow Garage PR2 and the Barrett WAM arm which have very different hands. Our results show that the algorithm is able to find good grasp configurations for a large set of objects from a relatively small set of demonstrations, and does indeed improve its performance over time.

am mg

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Adjustable autonomy for mobile teleoperation of personal service robots

Muszynski, S., Stueckler, J., Behnke, S.

In Proc. of the IEEE Int. Symp. on Robot and Human Interactive Communication, pages: 933-940, sep 2012 (inproceedings)

ev

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Adaptive Multi-cue 3D Tracking of Arbitrary Objects

Garcia, G. M., Klein, D. A., Stueckler, J., Frintrop, S., Cremers, A. B.

In DAGM/OAGM Symposium, 7476, pages: 357-366, Lecture Notes in Computer Science, Springer, 2012 (inproceedings)

ev

[BibTex]

[BibTex]


no image
Probabilistic depth image registration incorporating nonvisual information

Wüthrich, M., Pastor, P., Righetti, L., Billard, A., Schaal, S.

In 2012 IEEE International Conference on Robotics and Automation, pages: 3637-3644, IEEE, Saint Paul, USA, 2012 (inproceedings)

Abstract
In this paper, we derive a probabilistic registration algorithm for object modeling and tracking. In many robotics applications, such as manipulation tasks, nonvisual information about the movement of the object is available, which we will combine with the visual information. Furthermore we do not only consider observations of the object, but we also take space into account which has been observed to not be part of the object. Furthermore we are computing a posterior distribution over the relative alignment and not a point estimate as typically done in for example Iterative Closest Point (ICP). To our knowledge no existing algorithm meets these three conditions and we thus derive a novel registration algorithm in a Bayesian framework. Experimental results suggest that the proposed methods perform favorably in comparison to PCL [1] implementations of feature mapping and ICP, especially if nonvisual information is available.

am mg

link (url) DOI [BibTex]

link (url) DOI [BibTex]

2010


Graph signature for self-reconfiguration planning of modules with symmetry
Graph signature for self-reconfiguration planning of modules with symmetry

Asadpour, M., Ashtiani, M. H. Z., Spröwitz, A., Ijspeert, A. J.

In Proceedings of the 2009 IEEE/RSJ International Conference on Intelligent Robots and Systems, pages: 5295-5300, IEEE, St. Louis, MO, 2010 (inproceedings)

Abstract
In our previous works we had developed a framework for self-reconfiguration planning based on graph signature and graph edit-distance. The graph signature is a fast isomorphism test between different configurations and the graph edit-distance is a similarity metric. But the algorithm is not suitable for modules with symmetry. In this paper we improve the algorithm in order to deal with symmetric modules. Also, we present a new heuristic function to guide the search strategy by penalizing the solutions with more number of actions. The simulation results show the new algorithm not only deals with symmetric modules successfully but also finds better solutions in a shorter time.

dlg

DOI [BibTex]

2010


DOI [BibTex]


Roombots - Towards decentralized reconfiguration with self-reconfiguring modular robotic metamodules
Roombots - Towards decentralized reconfiguration with self-reconfiguring modular robotic metamodules

Spröwitz, A., Laprade, P., Bonardi, S., Mayer, M., Moeckel, R., Mudry, P., Ijspeert, A. J.

In Proceedings of the 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), pages: 1126-1132, IEEE, Taipeh, 2010 (inproceedings)

Abstract
This paper presents our work towards a decentralized reconfiguration strategy for self-reconfiguring modular robots, assembling furniture-like structures from Roombots (RB) metamodules. We explore how reconfiguration by loco- motion from a configuration A to a configuration B can be controlled in a distributed fashion. This is done using Roombots metamodules—two Roombots modules connected serially—that use broadcast signals, lookup tables of their movement space, assumptions about their neighborhood, and connections to a structured surface to collectively build desired structures without the need of a centralized planner.

dlg

DOI [BibTex]

DOI [BibTex]


Roombots: Reconfigurable Robots for Adaptive Furniture
Roombots: Reconfigurable Robots for Adaptive Furniture

Spröwitz, A., Pouya, S., Bonardi, S., van den Kieboom, J., Möckel, R., Billard, A., Dillenbourg, P., Ijspeert, A.

Computational Intelligence Magazine, IEEE, 5(3):20-32, 2010 (article)

Abstract
Imagine a world in which our furniture moves around like legged robots, interacts with us, and changes shape and function during the day according to our needs. This is the long term vision we have in the Roombots project. To work towards this dream, we are developing modular robotic modules that have rotational degrees of freedom for locomotion as well as active connection mechanisms for runtime reconfiguration. A piece of furniture, e.g. a stool, will thus be composed of several modules that activate their rotational joints together to implement locomotor gaits, and will be able to change shape, e.g. transforming into a chair, by sequences of attachments and detachments of modules. In this article, we firstly present the project and the hardware we are currently developing. We explore how reconfiguration from a configuration A to a configuration B can be controlled in a distributed fashion. This is done using metamodules-two Roombots modules connected serially-that use broadcast signals and connections to a structured ground to collectively build desired structures without the need of a centralized planner. We then present how locomotion controllers can be implemented in a distributed system of coupled oscillators-one per degree of freedom-similarly to the concept of central pattern generators (CPGs) found in the spinal cord of vertebrate animals. The CPGs are based on coupled phase oscillators to ensure synchronized behavior and have different output filters to allow switching between oscillations and rotations. A stochastic optimization algorithm is used to explore optimal CPG configurations for different simulated Roombots structures.

dlg

DOI [BibTex]

DOI [BibTex]


Distributed Online Learning of Central Pattern Generators in Modular Robots
Distributed Online Learning of Central Pattern Generators in Modular Robots

Christensen, D. J., Spröwitz, A., Ijspeert, A. J.

In From Animals to Animats 11, 6226, pages: 402-412, Lecture Notes in Computer Science, Springer, Berlin, 2010, author: Doncieux, Stéphan (incollection)

Abstract
In this paper we study distributed online learning of locomotion gaits for modular robots. The learning is based on a stochastic ap- proximation method, SPSA, which optimizes the parameters of coupled oscillators used to generate periodic actuation patterns. The strategy is implemented in a distributed fashion, based on a globally shared reward signal, but otherwise utilizing local communication only. In a physics-based simulation of modular Roombots robots we experiment with online learn- ing of gaits and study the effects of: module failures, different robot morphologies, and rough terrains. The experiments demonstrate fast online learning, typically 5-30 min. for convergence to high performing gaits (≈ 30 cm/sec), despite high numbers of open parameters (45-54). We conclude that the proposed approach is efficient, effective and a promising candidate for online learning on many other robotic platforms.

dlg

DOI [BibTex]

DOI [BibTex]


Automatic Gait Generation in Modular Robots: to Oscillate or to Rotate? that is the question
Automatic Gait Generation in Modular Robots: to Oscillate or to Rotate? that is the question

Pouya, S., van den Kieboom, J., Spröwitz, A., Ijspeert, A. J.

In Proceedings of the 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), pages: 514-520, IEEE, Taipei, 2010 (inproceedings)

Abstract
Modular robots offer the possibility to design robots with a high diversity of shapes and functionalities. This nice feature also brings an important challenge: namely how to design efficient locomotion gaits for arbitrary robot structures with many degrees of freedom. In this paper, we present a framework that allows one to explore and identify highly different gaits for a given arbitrary- shaped modular robot. We use simulated robots made of several Roombots modules that have three rotational joints each. These modules have the interesting feature that they can produce both oscillatory movements (i.e. periodic movements around a rest position) and rotational movements (i.e. with continuously increasing angle), leading to very rich locomotion patterns. Here we ask ourselves which types of movements —purely oscillatory, purely rotational, or a combination of both— lead to the fastest gaits. To address this question we designed a control architecture based on a distributed system of coupled phase oscillators that can produce synchronized rotations and oscillations in many degrees of freedom. We also designed a specific optimization algorithm that can automatically design hybrid controllers, i.e. controllers that use oscillations in some joints and rotations in others, for fast gaits. The proposed framework is verified by multiple simulations for several robot morphologies. The results show that (i) the question whether it is better to oscillate or to rotate depends on the morphology of the robot, and that in general it is best to do both, (ii) the optimization framework can successfully generate hybrid controllers that outperform purely oscillatory and purely rotational ones, and (iii) the resulting gaits are fast, innovative, and would have been hard to design by hand.

dlg

DOI [BibTex]

DOI [BibTex]


Roombots: Design and Implementation of a Modular Robot for Reconfiguration and Locomotion
Roombots: Design and Implementation of a Modular Robot for Reconfiguration and Locomotion

Spröwitz, A.

EPFL, Lausanne, Lausanne, 2010 (phdthesis)

dlg

DOI [BibTex]


no image
Combining depth and color cues for scale- and viewpoint-invariant object segmentation and recognition using Random Forests

Stueckler, J., Behnke, S.

In Proc. of the IEEE/RSJ Int. Conf. on Intelligent Robots and Systems (IROS), pages: 4566-4571, October 2010 (inproceedings)

ev

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Intuitive Multimodal Interaction for Domestic Service Robots

Nieuwenhuisen, M., Stueckler, J., Behnke, S.

In Proc. of the ISR/ROBOTIK, VDE Verlag, 2010 (inproceedings)

ev

link (url) [BibTex]

link (url) [BibTex]


no image
Improving People Awareness of Service Robots by Semantic Scene Knowledge

Stueckler, J., Behnke, S.

In RobuCup, 6556, pages: 157-168, Lecture Notes in Computer Science, Springer, 2010 (inproceedings)

ev

link (url) [BibTex]

link (url) [BibTex]


no image
Towards Semantic Scene Analysis with Time-of-flight Cameras

Holz, D., Schnabel, R., Droeschel, D., Stueckler, J., Behnke, S.

In RobuCup, 6556, pages: 121-132, Lecture Notes in Computer Science, Springer, 2010 (inproceedings)

ev

link (url) [BibTex]

link (url) [BibTex]


no image
Utilizing the Structure of Field Lines for Efficient Soccer Robot Localization

Schulz, H., Liu, W., Stueckler, J., Behnke, S.

In RobuCup, 6556, pages: 397-408, Lecture Notes in Computer Science, Springer, 2010 (inproceedings)

ev

link (url) [BibTex]

link (url) [BibTex]


no image
Improving indoor navigation of autonomous robots by an explicit representation of doors

Nieuwenhuisen, M., Stueckler, J., Behnke, S.

In Proc. of the IEEE Int. Conf. on Robotics and Automation (ICRA), pages: 4895-4901, May 2010 (inproceedings)

ev

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Constrained Accelerations for Controlled Geometric Reduction: Sagittal-Plane Decoupling for Bipedal Locomotion

Gregg, R., Righetti, L., Buchli, J., Schaal, S.

In 2010 10th IEEE-RAS International Conference on Humanoid Robots, pages: 1-7, IEEE, Nashville, USA, 2010 (inproceedings)

Abstract
Energy-shaping control methods have produced strong theoretical results for asymptotically stable 3D bipedal dynamic walking in the literature. In particular, geometric controlled reduction exploits robot symmetries to control momentum conservation laws that decouple the sagittal-plane dynamics, which are easier to stabilize. However, the associated control laws require high-dimensional matrix inverses multiplied with complicated energy-shaping terms, often making these control theories difficult to apply to highly-redundant humanoid robots. This paper presents a first step towards the application of energy-shaping methods on real robots by casting controlled reduction into a framework of constrained accelerations for inverse dynamics control. By representing momentum conservation laws as constraints in acceleration space, we construct a general expression for desired joint accelerations that render the constraint surface invariant. By appropriately choosing an orthogonal projection, we show that the unconstrained (reduced) dynamics are decoupled from the constrained dynamics. Any acceleration-based controller can then be used to stabilize this planar subsystem, including passivity-based methods. The resulting control law is surprisingly simple and represents a practical way to employ control theoretic stability results in robotic platforms. Simulated walking of a 3D compass-gait biped show correspondence between the new and original controllers, and simulated motions of a 16-DOF humanoid demonstrate the applicability of this method.

am mg

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Improving imitated grasping motions through interactive expected deviation learning

Gräve, K., Stueckler, J., Behnke, S.

In Proc. of the 10th IEEE-RAS Int. Conf. on Humanoid Robots (Humanoids), pages: 397-404, December 2010 (inproceedings)

ev

link (url) DOI [BibTex]

link (url) DOI [BibTex]


no image
Learning Motion Skills from Expert Demonstrations and Own Experience using Gaussian Process Regression

Gräve, K., Stueckler, J., Behnke, S.

In Proc. of the ISR/ROBOTIK, pages: 1-8, VDE Verlag, 2010 (inproceedings)

ev

link (url) [BibTex]

link (url) [BibTex]


no image
Using Time-of-Flight cameras with active gaze control for 3D collision avoidance

Droeschel, D., Holz, D., Stueckler, J., Behnke, S.

In Proc. of the IEEE Int. Conf. on Robotics and Automation (ICRA), pages: 4035-4040, May 2010 (inproceedings)

ev

link (url) [BibTex]

link (url) [BibTex]


no image
Inverse dynamics with optimal distribution of ground reaction forces for legged robot

Righetti, L., Buchli, J., Mistry, M., Schaal, S.

In Proceedings of the 13th International Conference on Climbing and Walking Robots (CLAWAR), pages: 580-587, Nagoya, Japan, sep 2010 (inproceedings)

Abstract
Contact interaction with the environment is crucial in the design of locomotion controllers for legged robots, to prevent slipping for example. Therefore, it is of great importance to be able to control the effects of the robots movements on the contact reaction forces. In this contribution, we extend a recent inverse dynamics algorithm for floating base robots to optimize the distribution of contact forces while achieving precise trajectory tracking. The resulting controller is algorithmically simple as compared to other approaches. Numerical simulations show that this result significantly increases the range of possible movements of a humanoid robot as compared to the previous inverse dynamics algorithm. We also present a simplification of the result where no inversion of the inertia matrix is needed which is particularly relevant for practical use on a real robot. Such an algorithm becomes interesting for agile locomotion of robots on difficult terrains where the contacts with the environment are critical, such as walking over rough or slippery terrain.

am mg

DOI [BibTex]

DOI [BibTex]