Learning Generalizable Control Programs Hart, S.; Grupen, R.
IEEE transactions on autonomous mental development,
2011-Sept., 2011-9-00, 20110901, Letnik:
3, Številka:
3
Journal Article
In this paper, we present a framework for guiding autonomous learning in robot systems. The paradigm we introduce allows a robot to acquire new skills according to an intrinsic motivation function ...that finds behavioral affordances. Affordances-in the sense of (Gibson, Toward and Ecological Psychology, Hillsdale, NJ, 1977)-describe the latent possibilities for action in the environment and provide a direct means of organizing functional knowledge in embodied systems. We begin by showing how a robot can assemble closed-loop action primitives from its sensory and motor resources, and then show how these primitives can be sequenced into multi-objective policies. We then show how these policies can be assembled hierarchically to support incremental and cumulative learning. The main contribution of this paper demonstrates how the proposed intrinsic motivator for affordance discovery can cause a robot to both acquire such hierarchical policies using reinforcement learning and then to generalize these policies to new contexts. As the framework is described, its effectiveness and applicability is demonstrated through a longitudinal learning experiment on a bimanual robot.
A prominent emerging theory of sensorimotor development in biological systems proposes that control knowledge is encoded in the dynamics of physical interaction with the world. From this perspective, ...the
musculoskeletal system is coupled through sensor feedback and neurological structure to a non-stationary world. Control is derived by reinforcing and learning to predict constructive patterns of interaction.
We have adopted the traditions of dynamic pattern theory in which behavior is an artifact of coupled dynamical systems with a number of controllable degrees of freedom. For grasping and manipulation, we
propose a closed-loop control process that is parametric in the number and identity of contact resources. We have shown previously that this controller generates a necessary condition for force closure
grasps. In this paper, we will show how control decisions can be made by estimating patterns of membership in a family of prototypical dynamic models. A grasp controller can thus be tuned on-line to optimize
performance over a variety of object geometries. This same process can be used to match the dynamics to several previously acquired haptic categories. We will illustrate how a grasping policy can be acquired
that is incrementally optimal for several objects using our Salisbury hand with tactile sensor feedback.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
A key problem in robot grasping is that of positioning the manipulator contacts so that an object can be grasped. In unstructured environments, contact positions are typically planned based on range ...or visual measurements that are used to reconstruct object geometry. However, because it is difficult to measure the complete object geometry precisely in common grasp scenarios, it is useful to employ additional techniques to adjust or refine the grasp using local information only. In particular, grasp control techniques can be used to improve a grasp by adjusting the contact configuration after making initial contact with an object by using measurements of local object geometry at the contacts. This paper proposes three variations on null-space grasp control: an approach that combines multiple grasp objectives to improve a grasp. Two of these variations are theoretically demonstrated to converge to force-closure configurations for arbitrary convex objects when grasping with two contacts. All variations are found to converge in simulation. Robot-grasping experiments are reported that show the approach to be useful in practice.
Properties of the human embodiment — sensorimotor apparatus and neurological structure — participate directly in the growth and development of cognitive processes against enormous worst case ...complexity. It is our position that relationships between morphology and perception over time lead to increasingly comprehensive models that describe the agent’s relationship to the world. We are applying insight derived from neuroscience, neurology, and developmental psychology to the design of advanced robot architectures. To investigate developmental processes, we have begun to approximate the human sensorimotor configuration and to engage sensory and motor subsystems in developmental sequences. Many such sequences have been documented in studies of infant development, so we intend to bootstrap cognitive structures in robots by emulating some of these growth processes that bear an essential resemblance to the human morphology. In this paper, we will show two related examples in which a humanoid robot determines the models and representations that govern its behavior. The first is a model that captures the dynamics of a haptic exploration of an object with a dextrous robot hand that supports skillful grasping. The second example constructs constellations of visual features to predict relative hand/object postures that lead reliably to haptic utility. The result is a first step in a trajectory toward associative visual-haptic categories that bounds the incremental complexity of each stage of development.
Real-time support for mobile robotics Huan Li; Sweeney, J.; Ramamritham, K. ...
The 9th IEEE Real-Time and Embedded Technology and Applications Symposium, 2003. Proceedings,
2003
Conference Proceeding
Coordinated behavior of mobile robots is an important emerging application area. Different coordinated behaviors can be achieved by assigning sets of control tasks, or strategies, to robots in a ...team. These control tasks must be scheduled either locally on the robot or distributed across the team. An application may have many control strategies to dynamically choose from, although some may not be feasible, given limited resource and time availability. Thus, dynamic feasibility checking becomes important as the coordination between robots and the tasks that need to be performed evolves with time. This paper presents an online algorithm for finding a feasible strategy given a functionally equivalent set of strategies for achieving an application's goals. We present two heuristics for feasibility checking. Both consider communication cost and utilization bound to make allocation (of tasks to execution sites) and scheduling decisions. Extensive experimental results show the effectiveness of the approaches, especially in resource-tight environments. We also demonstrate the application of our approach to real-world scenarios involving teams of robots and show how feasibility analysis also allows the prediction of the scalability of the solution to large robot teams.
KASCADE and its extension array of KASCADE-Grande were devoted to measure individual air showers of cosmic rays in the primary energy range of 100 TeV to 1 EeV. The experiment has substantially ...contributed to investigate the energy spectrum and mass composition of cosmic rays in the transition region from galactic to extragalactic origin of cosmic rays as well as to quantify the characteristics of hadronic interaction models in the air shower development through validity tests using the multi-detector information from KASCADE-Grande. Although the data accumulation was completed in 2013, data analysis is still continuing. Recently, we investigated the reliability of the new hadronic interactions models of the SIBYLL version 2.3d only with the energy spectra from the KASCADE-Grande data. The evolution of the muon content of high energy air showers in the atmosphere is studied as well, using EPOS-LHC, SIBYLL 2.3, QGSJET-II-04 and SIBYLL 2.3c. In this talk, recent results from KASCADE-Grande and the update of the KASCADE Cosmic Ray Data Centre (KCDC) will be discussed.
In recent years, the potential of robot-mediated upper extremity therapy has been widely acknowledged in stroke rehabilitation. The primary focus of rehabilitation robotics has been on building ...exoskeleton robots as well as devising control strategies that leverage robotic forces to adaptively assist and resist the movements of patients' impaired arms during repetitive reach-touch exercises. In our single subject case study, a robot presents exercise target positions that are successively more difficult to the patient. This serves to adaptively challenge the patient, while inducing voluntary reach-touch movements. Through data collected during 12 weeks of therapy with a single subject, we demonstrate that a general purpose robot can induce desired therapeutic exercise movements from a patient. In addition, we have observed that the challenge level can be adapted as the patient improves his motor function, which leads to observable improvements in the motor function of the patient.
Coordinated teams of reactive mobile platforms Sweeney, J; Brunette, T J; Yang, Y ...
Proceedings - IEEE International Conference on Robotics and Automation,
01/2002, Letnik:
1
Journal Article
This paper presents techniques for exploiting redundancy in teams of mobile robots. In particular, we address tasks involving the kinematic coordination of several communicating robots. Teams are ...modeled as highly redundant spatial mechanisms for which multi-objective, concurrent controllers are constructed using a generalization of null-space control. The goal is to develop a methodology in which the robustness and error suppression in a control theoretic substrate can be used to preserve critical properties in teams of reactive robots. The resulting "safe" control options can then be explored while guaranteeing global compliance with system specifications. The proposed architecture depends on a set of concurrent, low-dimensional control processes that interact in a well-defined manner. Cascaded null space projections and coordination templates are used to manage control interactions across platforms that actively maintain constraints for pairs of robots. Pairwise policies can then be combined to represent coordinated, multi-robot tasks. To illustrate the approach, we demonstrate a distributed control that maintains critical connectivity in line-of-sight communication networks.
Any given task can be solved in a number of ways, whether through path-planning, modeling, or control techniques. In this paper, we present a methodology for natural task decomposition through the ...use of intrinsically meaningful potential fields. Specifically, we demonstrate that using classical conditioning measures in a concurrent control framework provides a domain-general means for solving tasks. Among the conditioning measures we use are manipulability T. Yoshikawam, 1985, localizability J. Uppala et al., 2002, and range of motion. To illustrate the value of our approach we demonstrate its applicability to an industrially relevant inspection task.
A critical problem in sensory interpretation is the derivation of the right mapping between sensor signals and properties of the world. In this regard, the method proposed uses active sensing to ...acquire environmental features for reliable navigation in indoor environments. The features utilized are lines, corners, and edges extracted from common indoor room features such as walls, room corners and room edges, respectively. These features are abundant in indoor environments and allow for closed-form location estimates from time-of-flight sonar information. Subsequently, a multiple hypothesis testing procedure is utilized to accurately localize and identify those features. Experiments using a new active sonar system, implemented using a 3 DOF binaural sonar head, shows that the system is able to correctly localize and identify indoor environmental features, and that active sensing strategies based on sensor reconfiguration makes the process of feature extraction more accurate.
PDF
