waashk/dblp huggingface dataset:
automatic deployment of distributed teams of robots from temporal logic motion specifications. we present a computational framework for automatic synthesis of decentralized communication and control strategies for a robotic team from global specifications, which are given as temporal and logic statements about visiting regions of interest in a partitioned environment. we consider a purely discrete scenario, where the robots move among the vertices of a graph. however, by employing recent results on invarianec and facet reachability for dynamical systems in environments with polyhedral partitions, the framework from this paper can be directly implemented for robots with continuous dyrtamics. while allowing tor a rich specification language and guaranteeing the correctness of the solution, our approach is conservative in the sense that we might not find a solution, even if one exists. the overall amount of required computation is large. however, most of it is performed offline before the deployment. illustrative simulations and experimental results are included.
interrobot transformations in 3-d. in this paper, we provide a study of motion-induced 3-d extrinsic calibration based on robot-to-robot sensor measurements. in particular, we introduce algebraic methods to compute the relative translation and rotation between two robots using known robot motion and robot-to-robot 1) distance and bearing, 2) bearing-only, and 3) distance-only measurements. we further conduct a nonlinear observability analysis and provide sufficient conditions for the 3-d relative position and orientation (pose) to become locally weakly observable. finally, we present a nonlinear weighted least-squares estimator to refine the algebraic pose estimate in the presence of noise. we use simulations to evaluate the performance of our methods in terms of accuracy and robustness.
pursuit-evasion on trees by robot teams. we present graph-clear: a novel pursuit-evasion problem on graphs which models the detection of intruders in complex indoor environments by robot teams. the environment is represented by a graph, and a robot team can execute sweep and block actions on vertices and edges, respectively. a sweep action detects intruders in a vertex and represents the capability of the robot team to detect intruders in the region associated to the vertex. similarly, a block action prevents intruders from crossing an edge and represents the capability to detect intruders as they move between regions. both actions may require multiple robots to be executed. a strategy is a sequence of block and sweep actions to detect all intruders. when instances of graph-clear are being solved, the goal is to determine optimal strategies, i.e., strategies that use the least number of robots. we prove that for the general case of graphs, the problem of computation of optimal strategies is np-hard. next, for the special case of trees, we provide a polynomial-time algorithm. the algorithm ensures that throughout the execution of the strategy, all cleared vertices form a connected subtree, and we show that it produces optimal strategies.
shortest paths for a robot with nonholonomic and field-of-view constraints. this paper presents a complete characterization of shortest paths to a goal position for a robot with unicycle kinematics and an on-board camera with limited field-of-view (fov), which must keep a given feature in sight. previous work on this subject has shown that the search for a shortest path can be limited to simple families of trajectories. in this paper, we provide a complete optimal synthesis for the problem, i.e., a language of optimal control words, and a global partition of the motion plane induced by shortest paths, such that aword in the optimal language is univocally associated with a region and completely describes the shortest path from any starting point in that region to the goal point. an efficient algorithm to determine the region in which the robot is at any time is also provided.
the actuator with mechanically adjustable series compliance. running is a complex dynamic task that places strict requirements on both the physical components and software-control systems of a robot. this paper explores some of those requirements and, in particular, explores how a variable-compliance actuation system can satisfy many of them. we present the mechanical design and software-control system for such an actuator system. we analyze its performance through simulation and bench-top experimental validation of a prototype version. in conclusion, we demonstrate, through simulation, the application of our proof-of-concept aduator to the problem of biped running.
flat dry elastomer adhesives as attachment materials for climbing robots. in this paper, flat elastomers are proposed as an attachment material for climbing robots on less than a few micrometer-scale rough surfaces due to their energy-efficient, quiet, and residue-free characteristics. the proper elastomer is chosen by the use of the current adhesion, friction, and peeling elastomer-contact-mechanics models. then, adhesion and friction properties of the chosen dry flat-elastomer thick films (vytaflex-10) are characterized on acrylic and smooth and rough glass surfaces for variations in preloads, speeds, contact times, and elastomer thicknesses. a climbing robot with four-bar-based legged-body kinematics is designed and fabricated as simple and lightweight as possible to demonstrate the feasibility of the elastomers as attachment materials on relatively smooth surfaces. the robot utilizes a passive alignment system to make the footpads parallel to the surface on light contact, a peeling mechanism to minimize the detachment vibration, and a passive tail to minimize the pitch-back moment. experimental results showed that the robot can climb stably on vertical, smooth surfaces in any direction and can walk inverted for a limited amount of time.
sliding-mode velocity control of mobile-wheeled inverted-pendulum systems. there has been increasing interest in a type of underactuated mechanical systems, mobile-wheeled inverted-pendulum (mwip) models, which are widely used in the field of autonomous robotics and intelligent vehicles. robust-velocity-tracking problem of the mwip systems is investigated in this study. in the velocity-control problem, model uncertainties accompany uncertain equilibriums, which make the controller design become more difficult. two sliding-mode-control (smc) methods are proposed for the systems, both of which are capable of handling both parameter uncertainties and external disturbances. the asymptotical stabilities of the corresponding closed-loop systems are achieved through the selection of sliding-surface parameters, which are based on some rules. there is still a steady tracking error when the first smc controller is used. by assuming a novel sliding surface, the second smc controller is designed to solve this problem. the effectiveness of the proposed methods is finally confirmed by the numerical simulations.
design and control of concentric-tube robots. a novel approach toward construction of robots is based on a concentric combination of precurved elastic tubes. by rotation and extension of the tubes with respect to each other, their curvatures interact elastically to position and orient the robot's tip, as well as to control the robot's shape along its length. in this approach, the flexible tubes comprise both the links and the joints of the robot. since the actuators attach to the tubes at their proximal ends, the robot itself forms a slender curve that is well suited for minimally invasive medical procedures. this paper demonstrates the potential of this technology. design principles are presented and a general kinematic model incorporating tube bending and torsion is derived. experimental demonstration of real-time position control using this model is also described.
cooperative load transport: a formation-control perspective. we consider a group of agents collaboratively transporting a flexible payload. the contact forces between the agents and the payload are modeled as gradients of nonlinear potentials that describe the deformations of the payload. the load-transport problem is then treated in a similar fashion to the formation-control problem. decentralized control laws are developed such that without explicit communication, the agents and the payload converge to the same constant velocity; meanwhile, the contact forces are regulated. experimental results illustrate the effectiveness of our designs.
deterministic robot-network localization is hard. this paper provides a complexity study of the deterministic localization problem in robot networks using local and relative observations only. this is an important issue in collective and cooperative robotics where global positioning systems (gps) are not available, and the basic premise is the localization ability of the group. we prove that given a set of relative observations made by the robots, the unique unambiguous pose estimation of the robot network in a deterministic way is an np-hard problem. thismeans that no polynomial-time algorithm can deterministically solve the unique pose estimation problem based on relative observations unless p = np. the consequence is that no guarantee can be provided, in a polynomial time, that the possibly estimated poses of the robots will correspond to the effective (actual) ones. the proof is based on complexity theory where we build appropriate polynomial-time reductions interrelating the multirobot localization problem to a well-known np-complete problem (the partition problem). this np-hardness result opens questions and perspectives for research into approximations to overcome its intractability.
online trajectory generation: basic concepts for instantaneous reactions to unforeseen events. this paper introduces a new method for motion-trajectory generation of mechanical systems with multiple degrees of freedom (dofs). the key feature of this new concept is that motion trajectories are generated online, i.e., within every control cycle, typically every millisecond. this enables systems to react instantaneously to unforeseen and unpredictable (sensor) events at any time instant and in any state of motion. as a consequence, (multi)sensor integration in robotics, in particular the development of control systems enabling sensor-guided and sensor-guardedmotions, becomes greatly simplified. we introduce a class of online trajectory-generation algorithms and present themathematical basics of this new approach. the algorithms presented here consist of three steps: calculation of the minimum synchronization time for all dofs, synchronization of all dofs, and calculation of output values. the theory is followed by real-world experimental results indicating new possibilities in robot-motion control.
robot positioning using camera-space manipulation with a linear camera model. this paper presents a new version of the camera-space-manipulation method (csm). the set of nonlinear view parameters of the classic csm is replaced with a linear model. simulations and experiments show a similar precision error for the two methods. however the new approach is simpler to implement and is faster.
invariant trajectory tracking with a full-size autonomous road vehicle. safe hundling of dynamic inner-city scenarios with autonomous road vehicles involves the problem of stabilization of precalculated state trajectories. in order to account for the practical requirements of the holistic autonomous system, we propose two complementary nonlinear lyapunov-based traddng-controllaws to solve the problem for speeds between ±6 m/s. their designs are based on an extended kinematic one-track model, and they provide a smooth, singularity-free stopping transient. with regard to autonomous test applications, the proposed tracking law without orientation control performs much better with respect to control effort and steering-input saturation than the one with orientation control but needs to be prudently combined with the latter for backward driving. the controller performance is illustrated with a full-size test vehicle.
an integrated system for user-adaptive robotic grasping. this paper presents an integrated system that combines learning, a natural-language interface, and robotic grasping to enable the transfer of grasping skills from nontechnical users to robots. the system consists of two parts: a natural-language interface for grasping commands and a learning system. this paper focuses on the learning system and testing of the entire system in a small usability study. the learning system presented consists of two phases. in the first phase, the system learns to predict the next command, which the user is planning to issue based on command sequences recorded during previous grasping sessions. in the second phase, the system predicts the user's current state and moves the robot's gripper to the intended target endpoint to attempt to grasp the object. using eight nontechnical users and a 5-degree-of-freedom (dof) robot arm, a usability study was conducted to observe the impact of the learning system on user performance and satisfaction during a grasping operation. experimental results show that the system was effective in learning users' grasping intentions, which allowed it to reduce the average time to grasp an object. in addition, participants' feedback from the usability study was generally positive toward having an adaptive robotics system that learns from their commands.
sampling-based path planning on configuration-space costmaps. this paper addresses path planning to consider a cost function defined over the configuration space. the proposed planner computes low-cost paths that follow valleys and saddle points of the configuration-space costmap. it combines the exploratory strength of the rapidly exploring random tree (rrt) algorithm with transition tests used in stochastic optimization methods to accept or to reject new potential states. the planner is analyzed and shown to compute low-cost solutions with respect to a path-quality criterion based on the notion of mechanical work. a large set of experimental results is provided to demonstrate the effectiveness of the method. current limitations and possible extensions are also discussed.
multi-uav convoy protection: an optimal approach to path planning and coordination. in this paper, we study the problem of controlling a group of unmanned aerial vehicles (uavs) to provide convoy protection to a group of ground vehicles. the uavs are modeled as dubins vehicles flying at a constant altitude with bounded turning radius.we first present time-optimal paths to provide convoy protection to stationary ground vehicles. then, we propose a control strategy to provide convoy protection to ground vehicles moving in straight lines. the minimum number of uavs required to provide perpetual convoy protection, in both cases, are derived.
null-space grasp control: theory and experiments. akey 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.
information-based compact pose slam. pose slamis the variant of simultaneous localization and map building (slam) is the variant of slam, in which only the robot trajectory is estimated and where landmarks are only used to produce relative constraints between robot poses. to reduce the computational cost of the information filter form of poseslam and, at the same time, to delay inconsistency as much as possible, we introduce an approach that takes into account only highly informative loop-closure links and nonredundant poses. this approach includes constant time procedures to compute the distance between poses, the expected information gain for each potential link, and the exact marginal covariances while moving in open loop, as well as a procedure to recover the state after a loop closure that, in practical situations, scales linearly in terms of both time and memory. using these procedures, the robot operates most of the time in open loop, and the cost of the loop closure is amortized over long trajectories. this way, the computational bottleneck shifts to data association, which is the search over the set of previously visited poses to determine good candidates for sensor registration. to speed up data association, we introduce a method to search for neighboring poses whose complexity ranges from logarithmic in the usual case to linear in degenerate situations. the method is based on organizing the pose information in a balanced tree whose internal levels are defined using interval arithmetic. the proposed pose-slam approach is validated through simulations, real mapping sessions, and experiments using standard slam data sets.
tactile sensing - from humans to humanoids. starting from human "sense of touch," this paper reviews the state of tactile sensing in robotics. the physiology, coding, and transferring tactile data and perceptual importance of the "sense of touch" in humans are discussed. following this, a number of design hints derived for robotic tactile sensing are presented. various technologies and transduction methods used to improve the touch sense capability of robots are presented. tactile sensing, focused to fingertips and hands until past decade or so, has now been extended to whole body, even thoughmany issues remain open. trend and methods to develop tactile sensing arrays for various body sites are presented. finally, various system issues that keep tactile sensing away from widespread utility are discussed.
coordinated kinematic control of compliantly coupled multirobot systems in an array format. this paper presents coordinated kinematic control of compliantly coupled multirobot systems for payload transportation. in the robot, unicycle-type axles are connected to a moving platform in an array format using compliant frames. a coordinate system is attached to an ideal center point on the platform to establish robot kinematics. in order to drive the system along a reference trajectory, we coordinate axle velocity commands, while considering frame compliance, nonholonomic constraints, and rigid body kinematics, respectively. these commands are further coordinated to consider configuration stability and physical limitations. simulation and experimental results evaluate the coordination algorithms for various trajectories.
decoupled image-based visual servoing for cameras obeying the unified projection model. this paper proposes a generic decoupled image-based control scheme for cameras obeying the unified projection model. the scheme is based on the spherical projection model. invariants to rotational motion are computed from this projection and used to control the translational degrees of freedom (dofs). importantly, we form invariants that decrease the sensitivity of the interaction matrix to object-depth variation. finally, the proposed results are validated with experiments using a classical perspective camera as well as a fisheye camera mounted on a 6-dof robotic platform.
2-d ultrasound probe complete guidance by visual servoing using image moments. this paper presents a visual-servoing method that is based on 2-d ultrasound (us) images. the main goal is to guide a robot actuating a 2-d us probe in order to reach a desired cross-section image of an object of interest. the method we propose allows the control of both in-plane and out-of-plane probe motions. its feedback visual features are combinations of moments extracted from the observed image. the exact analytical form of the interaction matrix that relates the image-moments time variation to the probe velocity is developed, and six independent visual features are proposed to control the six degrees of freedom of the robot. in order to endow the system with the capability of automatically interacting with objects of unknown shape, a model-free visual servoing is developed. for that, we propose an efficient online estimation method to identify the parameters involved in the interaction matrix. results obtained in both simulations and experiments validate the methods presented in this paper and show their robustness to different errors and perturbations, especially those inherent to the noisy us images.
dual-differential rheological actuator for high-performance physical robotic interaction. today's robotic systems are mostly rigid and position-controlled machines designed to operate in structured environments. to extend their application domains to partially unknown, dynamic, or anthropic environments, improved physical-interaction capabilities are required. in this new context, to blend the requirements for safety, robustness, and versatility is often a challenge, in part, because commonly available actuator technologies are inadequate. this paper presents our solution with the introduction of the dual-differential rheological actuator (ddra) concept, which is based on the synergistic combination of an electromagnetic (em) motor and two differentially coupled magnetorheological (mr) brakes. this paper describes the approach and the prototype design. it then discusses performances in force, motion, and interaction control.