waashk/dblp huggingface dataset:
localization: approximation and performance bounds to minimize travel distance. localization, which is the determination of one's location in a known terrain, is a fundamental task for autonomous robots. this paper presents several new basic theoretical results about localization.we show that, even under the idealized assumptions of accurate sensing and perfect actuation, it is intrinsically difficult to localize a robot with a travel distance that is close to minimal. our result helps to theoretically justify the common use of fast localization heuristics, such as greedy localization, which always moves the robot to a closest informative location (where the robot makes an observation that decreases the number of its possible locations). we show that the travel distance of greedy localization is much larger thanminimal in some terrains because the closest informative location can distract greedy localization from a slightly farther, but much more informative, location. however, we also show that the travel distance of greedy localization can be larger, but not much larger, than the terrain size n. thus, the travel distance of greedy localization scales well with the terrain size and is much larger than minimal in some terrains, not because it is large with respect to the terrain size, but because the minimal travel distance is exceptionally small in these terrains. as a corollary to our analysis, we show that the travel distance of greedy mapping (which always moves the robot to a closest location, where it makes an observation that increases its knowledge of the terrain) cannot be much larger than the terrain size. in theoretical terms, we prove the np-hardness of minimization of travel distance for localization to within a logarithmic factor of the terrain size. we prove that the travel distance of greedy localization is at least order n/ log2 n larger than minimal in some terrains and that it is at least order n log n/ log log n in the worst case. finally, we prove that the travel distance of both greedy localization and greedy mapping is at most order n log n. previously, it was only known that it is np-hard to localize with minimal travel distance and that the travel distances of greedy localization and greedy mapping are at most order n3/2.
robustness of image-based visual servoing with a calibrated camera in the presence of uncertainties in the three-dimensional structure. this paper concerns the stability analysis of imagebased visual servoing control laws with respect to uncertainties on the 3-d parameters needed to compute the interaction matrix for any calibrated central catadioptric camera. in the recent past, research on image-based visual servoing has been concentrated on potential problems of stability and on robustness with respect to camera-calibration errors. only little attention, if any, has been devoted to the robustness of image-based visual servoing to estimation errors on the 3-d structure. it is generally believed that a rough approximation of the 3-d structure is sufficient to ensure the stability of the control law. in this paper, we prove that this is not always true and that an extreme care must be taken when approximating the depth distribution to ensure stability of the image-based control law. the theoretical results are obtained not only for conventional pinhole cameras but for the entire class of central catadioptric systems as well.
vector fields for robot navigation along time-varying curves in n -dimensions. this paper presents a methodology for computation of artificial vector fields that allows a robot to converge to and circulate around generic curves specified in n-dimensional spaces. these vector fields may be directly applied to solve several robot-navigation problems such as border monitoring, surveillance, target tracking, and multirobot pattern generation, with special application to fixed-wing aerial robots, which must keep a positive forward velocity and cannot converge to a single point. unlike previous solutions found in the literature, the approach is based on fully continuous vector fields and is generalized to time-varying curves defined in n-dimensional spaces. we provide mathematical proofs and present simulation and experimental results that illustrate the applicability of the proposed approach. we also present a methodology for construction of the target curve based on a given set of its samples.
general-weighted least-norm control for redundant manipulators. this paper presents the general-weighted least-norm (gwln) method for the control of redundant manipulators by a new concept of virtual joints, which consist of the performance function of subtasks. the gwln method enables the redundant manipulator to perform multiple subtasks with the assumption that all the subtasks can be represented by the inequalities as the joint limits avoidance subtask. the number of subtasks to be coped with might be even larger than the number of joints if they do not happen simultaneously. the simulations in contrast to the traditional gradient projection method (gpm) and the recent directional gpm have been made to manifest the advantages of the proposed method. an experiment on the seven-degree-of-freedom redundant manipulator illustrates the good performance for tracking a given trajectory of end-effector position, while both guaranteeing the obstacle free and not violating the joint limits.
detecting region transitions for human-augmented mapping. in this paper, we describe a concise method for the feature-based representation of regions in an indoor environment and show how it can also be applied for door-passage-independent detection of transitions between regions to improve communication with a human user.
human-intent detection and physically interactive control of a robot without force sensors. in this paper, a physically interactive control scheme is developed for a manipulator robot arm. the human touches the robot and applies force in order to make it behave as he/she likes. the communication between the robot and the human is maintained by a physical contact with no sensors. the intent of the human is estimated by observing the change in control effort. the robot receives the estimated human intent and updates its position reference accordingly. the developed method uses the principle of conservation of zero momentum for position-controlled systems. a switching scheme is developed that goes between themodes of pure impedance control with a fixed-position reference and interactive control under human intent. the switching mechanism uses neither a physical switch nor a sensor; it observes the human intent and puts the robot into interactive mode, if there is any. when the human intent disappears, the robot goes into the pure-impedance-control mode, thus stabilizing in the left position.
a fundamental study of wing actuation for a 6-in-wingspan flapping microaerial vehicle. this paper investigates the hovering efficiency of the wing-actuation parameters of a flapping microaerial vehicle with a two-degree-of-freedom (2-dof) driving mechanism, using finite-element analysis based on the arbitrary lagrangian-eulerian method (ale-fea). a 75-mm-long wing and multilinkage mechanism that consisted of thin plates and films was employed. it generated a flapping motion that consisted of horizontal stroke of the wing and twist around its leading edge, which were activated by the rotations of two motors. the application of the ale-fea was successfully extended to the structural behavior of the driving mechanism. the behaviors of the linkage mechanism, the wing, and its surrounding airflow were reproduced numerically. various parameters were obtained, some of which were difficult to measure in real experiments, such as the pressure distribution on the wing. for cases of 25 combinations of wings' twist angles and flapping periods, lift forces and energy requirements for the motors were determined. based on these results, the most efficient flapping combination that generated 1 gf lift force was calculated. in contrast with the combination that created the strongest lift force, the combination of a larger twist angle and a faster flapping cycle was found to provide the most efficient flight.
control of a speech robot via an optimum neural-network-based internal model with constraints. an optimum internal model with constraints is proposed and discussed for the control of a speech robot, which is based on the human-like behavior. the main idea of the study is that the robot movements are carried out in such a way that the length of the path traveled in the internal space, under external acoustical and mechanical constraints, is minimized. this optimum strategy defines the designed internal model, which is responsible for the robot task planning. first, an exact analytical way to deal with the problem is proposed. next, by using some empirical findings, an approximate solution for the designed internal model is developed. finally, the implementation of this solution, which is applied to the control of a speech robot, yields interesting results in the field of task-planning strategies, task anticipation (namely, speech coarticulation), and the influence of force on the accuracy of executed tasks.
steering by gazing: an efficient biomimetic control strategy for visually guided micro aerial vehicles. oscar ii is a twin-engine aerial demonstrator equipped with a monocular visual system, which manages to keep its gaze and its heading steadily fixed on a target (i.e., a dark edge or a bar) in spite of the severe random perturbations applied to its body via a ducted fan. the tethered robot stabilizes its gaze on the basis of two oculomotor reflexes (ors) inspired by studies on animals: 1) a visual-fixation reflex (vfr) and 2) a vestibulo-ocular reflex (vor). one of the key features of this robot is that the eye is decoupledmechanically from the body about the vertical (i.e., yaw) axis. to meet the conflicting requirements of high accuracy and fast ocular responses, a miniature (2.4 g) voice-coil motor (vcm) was used, which enables the eye tomake a change of orientation with an unusually short rise time (19 ms). the robot, which was equipped with a high-bandwidth (7 hz) "vor," which is based on an inertial microrate gyro, is capable of accurate visual fixation as long as there is light. the robot is also able to pursue a moving target in the presence of erratic gusts of wind. here, we present the two interdependent control schemes driving the eye in the robot and the robot in space with no knowledge of the robot's angular position. this "steering-by-gazing" control strategy, which is implemented on this lightweight (100 g) miniature aerial robot, demonstrates the effectiveness of this biomimetic visual/inertial heading control strategy.
influence of vibration modes and human operator on the stability of haptic rendering. developing stable controllers, which are able to display virtual objects with high stiffness, is a persistent challenge in the field of haptics. this paper addresses the effect of internal vibration modes and the human operator on the maximum achievable virtual stiffness. an 11-parameter mechanical model is used to adequately characterize the overall system dynamics. experiments that are carried out on lhifam and phantom haptic interfaces demonstrate the importance of vibration modes to determine the critical stiffness when the user grasps the device.
analysis and experimental verification for dynamic modeling of a skid-steered wheeled vehicle. skid-steered vehicles are often used as outdoor mobile robots due to their robust mechanical structure and high maneuverability. sliding, along with rolling, is inherent to general curvilinearmotion, whichmakes both kinematic and dynamic modeling difficult. for the purpose of motion planning, this paper develops and experimentally verifies dynamic models of a skid-steered wheeled vehicle for general planar (2-d) motion and for linear 3-d motion. these models are characterized by the coefficient of rolling resistance, the coefficient of friction, and the shear deformation modulus, which have terrain-dependent values. the dynamic models also include motor saturation and motor power limitations, which enable correct prediction of vehicle velocities when traversing on hills. it is shown that the closed-loop system that results from inclusion of the dynamics of the [proportional-integral-derivative (pid)] speed controllers for each set of wheels does a much better job than the open-loop model of predicting the vehicle linear and angular velocities. for a vehicle turning with small linear and angular accelerations, the model provides accurate predictions of velocities and reasonable predictions of torques. hence, the closed-loop model is recommended for motion planning.
iterative-learning hybrid force/velocity control for contour tracking. in this paper, we propose a new method, which is based on an iterative-learning-control (ilc) algorithm, for the contour tracking of an object of unknown shape performed by an industrial robot manipulator. in particular, we consider (both implicit and explicit) hybrid force/velocity control whose performance is improved by repeating the task. here, a time-based reference signal is not present, and therefore, a new approach has been developed, which is different from the typical applications of ilc. experimental results show the effectiveness of the technique.
adaptive task-space tracking control of robots without task-space- and joint-space-velocity measurements. the task-space tracking control of robots without the exact knowledge of kinematics and dynamics has been studied before with the assumption that the joint velocities are available for controller designs. however, the velocity measurements can be contaminated by noises, thereby resulting in poor system performance, or even leading to instability problems. therefore, in this paper, we propose a new tracking controller for robots in the task space without the use of both task-space and joint-space-velocity measurements, under the condition that both the robot kinematics and dynamics are unknown. to overcome these incapacities without the velocity measurements, we introduce the well-known sliding-observer-design techniques to estimate the joint velocities for the purpose of our controller design. our main concern, i.e., the stability analysis of our controller design incorporated with the siding observer, is presented with the help of lyapunov-analysis methodology and the sliding-patch concept. simulation results are presented to show the performance of our controller-observer designs.
evolutionary trajectory planner for multiple uavs in realistic scenarios. this paper presents a path planner for multiple unmanned aerial vehicles (uavs) based on evolutionary algorithms (eas) for realistic scenarios. the paths returned by the algorithm fulfill and optimize multiple criteria that 1) are calculated based on the properties of real uavs, terrains, radars, and missiles and 2) are structured in different levels of priority according to the selected mission. the paths of all the uavs are obtained with the multiple coordinated agents coevolution ea (mcacea), which is a general framework that uses an ea per agent (i.e., uav) that share their optimal solutions to coordinate the evolutions of the eas populations using cooperation objectives. this planner works omine and online by means of recalculating parts of the original path to avoid unexpected risks while the uav is flying. its search space and computation time have been reduced using some special operators in the eas. the successful results of the paths obtained in multiple scenarios, which are statistically analyzed in the paper, and tested against a simulator that incorporates complex models of the uavs, radars, and missiles, make us believe that this planner could be used for real-flight missions.
bioinspired visuomotor convergence. in this paper, wide-field integration methods, which are inspired by the spatial decompositions of wide-field patterns of optic flow in the insect visuomotor system, are explored as an efficient means to extract visual cues for guidance and navigation. a control-theoretic framework is developed and used to quantitatively link weighting functions to behaviorally-relevant interpretations such as relative orientation, position, and speed in a corridor environment. it is shown through analysis and demonstration on a ground vehicle that the proposed sensorimotor architecture gives rise to navigational heuristics, namely, centering and speed regulation, which are observed in natural systems.
decentralized localization of sparsely-communicating robot networks: a centralized-equivalent approach. finite-range sensing and communication are factors in the connectivity of a dynamic mobile-robot network. state estimation becomes a difficult problem when communication connections allowing information exchange between all robots are not guaranteed. this paper presents a decentralized state-estimation algorithm guaranteed to work in dynamic robot networks without connectivity requirements. we prove that a robot only needs to consider its own knowledge of network topology in order to produce an estimate equivalent to the centralized state estimate whenever possible while ensuring that the same can be performed by all other robots in the network. we prove certain properties of our technique and then it is validated through simulations. we present a comprehensive set of results, indicating the performance benefit in different network connectivity settings, as well as the scalability of our approach.
passive-set-position-modulation framework for interactive robotic systems. in this paper, we propose a novel framework, passive set-position modulation (pspm), which enables us to connect a (continuous-time) robot's position to a sequence of slowly updating/sparse (discrete-time) set-position signal via the simple (yet frequently used in practice) spring coupling with damping injection, while enforcing passivity of the closed-loop robotic system. the pspm modulates the original set-position signal in such a way that themodulated signal is as close to the original signal as possible (i.e., maximum information recovery for better performance), yet only to the extent permissible by the available energy in the system (i.e., passivity constraints). we present its algorithm and theoretically show its passivity and performance. we also show how this pspm can be applied for two applications, with some experimental results: internet teleoperation with varying delay and packet loss; and haptics with slow and variable-rate data update.
a model of proximity control for information-presenting robots. in this paper, we report a model that allows a robot to appropriately control its position as it presents information to a user. this capability is indispensable, since in the future, many robots will function in daily situations such as shopkeepers presenting products to customers or museum guides presenting information to visitors. psychology research suggests that people adjust their positions to establish a joint view toward a target object. similarly, when a robot presents an object, it should stand at an appropriate position that considers the positions of both the listener and the object to optimize the listener's field of view and establish a joint view. we observed human-human interaction situations, where people presented objects, and developed a model for an information-presenting robot to appropriately adjust its position. our model consists of four constraints to establish o-space: 1) proximity to listener; 2) proximity to object; 3) listener's field of view; and 4) presenter's field of view.we also experimentally evaluate the effectiveness of our model.
optimization of a parallel shoulder mechanism to achieve a high-force, low-mass, robotic-arm exoskeleton. this paper describes a robotic-arm exoskeleton that uses a parallel mechanism inspired by the human forearm to allow naturalistic shoulder movements. the mechanism can produce large forces through a substantial portion of the range of motion (rom) of the human arm while remaining lightweight. this paper describes the optimization of the exoskeleton's torque capabilities by the modification of the key geometric design parameters.
proxy-based sliding mode control: a safer extension of pid position control. high-gain proportional-integral-derivative (pid) position control involves some risk of unsafe behaviors in cases of abnormal events, such as unexpected environment contacts and temporary power failures. this paper proposes a new position-control method that is as accurate as conventional pid control during normal operation, but is capable of slow, overdamped resuming motion without overshoots from large positional errors that result in actuator-force saturation. the proposed method, which we call proxy-based sliding mode control (psmc), is an alternative approximation of a simplest type of sliding mode control (smc), and also is an extension of the pid control. the validity of the proposed method is demonstrated through stability analysis and experimental results.
path planning for improved visibility using a probabilistic road map. this paper focuses on the challenges of vision-based motion planning for industrial manipulators. our approach is aimed at planning paths that are within the sensing and actuation limits of industrial hardware and software. building on recent advances in path planning, our planner augments probabilistic road maps with vision-based constraints. the resulting planner finds collision-free paths that simultaneously avoid occlusions of an image target and keep the target within the field of view of the camera. the planner can be applied to eye-in-hand visual-targettracking tasks for manipulators that use point-to-point commands with interpolated joint motion.
autonomous robot navigation in outdoor cluttered pedestrian walkways. this paper describes an implementation of a mobile robot system for autonomous navigation in outdoor concurred walkways. the task was to navigate through nonmodified pedestrian paths with people and bicycles passing by. the robot has multiple redundant sensors, which include wheel encoders, an inertial measurement unit, a differential global positioning system, and four laser scanner sensors. all the computation was done on a single laptop computer. a previously constructed map containing waypoints and landmarks for position correction is given to the robot. the robot system's perception, road extraction, and motion planning are detailed. the system was used and tested in a 1-km autonomous robot navigation challenge held in the city of tsukuba, japan, named &ldquo;tsukuba challenge 2007.&rdquo; the proposed approach proved to be robust for outdoor navigation in cluttered and crowded walkways, first on campus paths and then running the challenge course multiple times between trials and the challenge final. the paper reports experimental results and overall performance of the system. finally the lessons learned are discussed. the main contribution of this work is the report of a system integration approach for autonomous outdoor navigation and its evaluation. &copy; 2009 wiley periodicals, inc.