waashk/dblp huggingface dataset:
improved inverse-depth parameterization for monocular simultaneous localization and mapping. inverse-depth parameterization can successfully deal with the feature initialization problem in monocular simultaneous localization and mapping applications. however, it is redundant, and when multiple landmarks are initialized from the same image, it fails to enforce the "common origin" constraint. the authors propose two new variants that addresses both of these issues. the experimental results indicate that the proposed approach achieves a better performance at a lower computational cost.
whole body motion primitive segmentation from monocular video. this paper proposes a novel approach for motion primitive segmentation from continuous full body human motion captured on monocular video. the proposed approach does not require a kinematic model of the person, nor any markers on the body. instead, optical flow computed directly in the image plane is used to estimate the location of segment points. the approach is based on detecting tracking features in the image based on the shi and thomasi algorithm [1]. the optical flow at each feature point is then estimated using the lucas kanade pyramidal optical flow estimation algorithm [2]. the feature points are clustered and tracked on-line to find regions of the image with coherent movement. the appearance and disappearance of these coherent clusters indicates the start and end points of motion primitive segments. the algorithm performance is validated on full body motion video sequences, and compared to a joint-angle, motion capture based approach. the results show that the segmentation performance is comparable to the motion capture based approach, while using much simpler hardware and at a lower computational effort.
mimetic communication with impedance control for physical human-robot interaction. in this paper, mimetic communication is extended to human-robot interaction tasks, in which physical contact transitions must be handled. the mimetic communication consists of imitation learning for learning low level motion primitives and a higher level interaction learning stage in which also the information about the human-robot contacts is included. for the imitation learning, cartesian marker data from a motion capture system is used. a modification of the low level marker trajectory following algorithm is presented, which allows to reshape the trajectory of the motion primitive in accordance with the human hand motion in real-time. moreover, for performing safe contact motion, an appropriate impedance controller is integrated into the setting. all the presented concepts are evaluated in experiments with a humanoid robot.
a versatile wire robot concept as a haptic interface for sport simulation. this paper presents the design of a new user-cooperative rope robot. this robot serves as a large-scale haptic interface in a multi-modal cave environment used for sport simulation. in contrast to current rope robots, the configuration of the presented robot is adaptable to different simulation tasks what makes the robot more versatile. however, this adaptability and the high dynamics in sports lead to challenging requirements and specific design criteria of the hardware components. we present the requirements on the single robot components as well as the design of the entire setup optimized in terms of user-cooperativity and versatility. the setup includes sensors to measure the relevant parameters for user-cooperative control, i.e. position with a high resolution and the rope forces. furthermore, an algorithm is introduced, which calculates the distance between the single ropes and the user in order to avoid collisions between the ropes and the user. single points on the user's body are, therefore, tracked with a motion tracking system; the user's single body parts are then represented by geometrical objects whose distances to the ropes are calculated. the algorithm is programmed in such way that the collision detection runs in real-time. both, the hardware and the algorithm, were evaluated experimentally in two applications, a rowing simulator and a tennis application. the hardware concept combined with the distance calculation allows the use of new kinematic concepts and expands the spectrum of realizable movement tasks that can be implemented into the cave environment.
a wireless acoustic emitter for passive localization in liquids. for the localization of minimally invasive medical devices, such as capsule endoscopes in the human body, ultrasound combines good resolution, minimal adverse health effects, high speed, adequate frame rates, and low cost. in the case of capsule endoscopes, small onboard ultrasonic emitters with minimal power requirements have the potential to provide significantly enhanced localization. we demonstrate for the first time acoustic emission in the khz range using a wireless emitter based on the actuation principle of the wireless resonant magnetic microactuator developed recently in our institute. our experiments show good agreement with the theoretical model, and simulations show the potential for high resolution localization.
a numerical solution to the ray-shooting problem and its applications in robotic grasping. based on the distance algorithm by gilbert et al., this paper presents a numerical algorithm for computing the intersection of the boundary of a compact convex set with a ray emanating from an interior point of the set, which is known as the ray-shooting problem. affinely independent points on the boundary of the convex set are also determined such that the intersection point can be written as their convex combination. because of its high efficiency and other good qualities, this algorithm provides superior solutions to three fundamental problems in robotic grasping, i.e., force-closure test, contact force optimization, and grasp quality evaluation, which can be formulated as the ray-shooting problem.
standing stabilizability and stepping maneuver in planar bipedalism based on the best com-zmp regulator. the goal of this paper is to answer (i) how the stabilization performance of a biped controller can be evaluated on a certain invariant supporting region, (ii) how the standing stabilizer which performs the best on a given supporting region can be designed, (iii) how the system can be judged if it is stabilizable by the best standing stabilizer without deforming the current supporting region, and (iv) how the supporting region should be deformed if it is judged to be necessary. in order to answer these question, the stable standing region is defined. it gives a criterion to design the best standing stabilizer, to judge if the deformation of the supporting region is necessary to stabilize the system, and to maneuver the stepping motion in accordance with the standing stabilizability condition, which is also defined in the paper. it is found that the best standing stabilizer can be designed by a simple pole-assignment technique. this framework unifies the standing stability and the stepping stability of bipedalism, which have been separately considered in conventional studies. the discussion goes on an approximate planar com-zmp model, in which the total mass is concentrated at the center of mass, and the position of zmp is regarded as the input. though it is the simplest dynamical model of bipeds, it can conceal differences of body constitutions and represent the macroscopic dynamics. therefore, this paper contributes to not only the biped robot controller design but also the biomechanical analyses.
an optimization-based approach to control of robotic manipulators. this paper proposes a method to suboptimally tune the control parameters in a conventional lyapunov-based method which shares the same concept of control design with sliding mode approach as applied to the robot manipulators. optimal tuning of such parameters involves handling of non-linearities in system dynamics and cost functions, which makes the problem challenging. we propose a step-by-step numerical algorithm that select suboptimal parameters while ensuring system stability. the controller is, suboptimal due to the facts that (1) it is in the form of a slotine-type sliding mode control, (2) the numerical recursive algorithm might fall into a local minimum, and (3) the controller coefficients depend on the initial conditions of the system. the method is successfully applied to a two-link robot manipulator and the results are compared in simulation with those of a conventional controller.
mechanical design of a novel hand exoskeleton for accurate force displaying. this paper deals with the mechanical design of a novel haptic hand exoskeleton (he) that allows exerting controlled forces on the fingertip of the index and thumb of the operator. the proposed device includes several design solutions for optimizing the accuracy and mechanical performances. remote centers of motion mechanisms have been adopted for delocalizing the encumbrance of linkages of the structure away from the operator's fingers. an improved stiffness of the transmission and reduced requirements for the actuators have been achieved thanks to a novel patent pending principle for integrating speed reduction ratio with the transmission system.
realization of acrobatic turn via wheelie for a bicycle with a balancer. since unmanned bike robots have high mobility and do not require wide contact space to the ground, it is expected that they will be used as one kind of the robots working in disaster areas and/or in the mountains. we are developing one of the unmanned bike robot systems with a balancer and it can do a wheelie and move to track the path in the ground plane. in this paper, we propose a control strategy to perform an acrobatic turn with wheelie motion, which can be quick and require minimum contact space for a bicycle by using nonlinear control based on the output-zeroing controller. the dynamic models of the bicycle with the balancer are derived from lagrangian's equations and they are combined by lagrange's multiplier according to nonholonomic and holonomic constraints between subsystems. the effectiveness of the proposed method is shown by several numerical simulations using a detail model of a bicycle.
partial order techniques for vehicle collision avoidance: application to an autonomous roundabout test-bed. in this paper, we employ partial order techniques to develop linear complexity algorithms for guaranteed collision avoidance between vehicles at highway and roundabout mergings. these techniques can be employed by virtue of the rich structure offered by such traffic systems, which constrain vehicles to advance unidirectionally along a path. the algorithms are safe by construction while maintaining the liveness of the system. the proposed algorithms are on-line implemented in a decentralized fashion on an experimental testbed composed of two in-scale communicating vehicles continuously running on an autonomous roundabout system.
robot-assisted rapid prototyping for ice structures. ice has long been used by humankind for utilitarian purposes, and more recently for artistic and entertainment purposes. nowadays, the field of ice construction is becoming more commercially relevant, with increased interest in ice modeling at the small scale, and in ice tourism, specifically ice hotels at the large scale. as a result, there is a market for automating ice construction, and building detailed structures that would otherwise require a significant amount of manual work. to address this demand, the authors are currently developing experimental robotic systems for building ice structures: the fab@home, for building small-scale structures, and the adept cobra 600 robot, for building medium-scale structures. further software and hardware development is needed for the cobra, since it was not designed for rapid prototyping, and certainly not for rapid prototyping using ice as the working material. the authors have designed and built fluid delivery systems for each machine to permit the use of water as the building material. a signal-processing subsystem permits control of the water-delivery flow rate and synchronization with the robot motion. additionally, we have developed a slicing algorithm to generate toolpaths for the cobra using stereolithography (stl) files as the input. we also intend to develop a larger robotic system for producing ice sculptures and buildings at the architectural scale.
development of the ihmc mobility assist exoskeleton. the ihmc mobility assist exoskeleton is a robitic suit that a user can wear for strength augmentation or gait generation. this first generation exoskeleton prototype focuses on providing walking assistance to persons with lower extermity paralysis. the main goal is to successfully enable a person that cannot walk without assistance to walk in a straight line a distance of 15 feet. when in disable assist mode this prototype will rely on the user to provide balance control, and thus an external means for balancing will be required, such as crutches or a walker. power and control is off board and supplied to the exoskeleton by means of a tether. rotary series elastic actuators (rseas), which have high force fidelity and low impedance were designed to power the joints. this paper described the design, test results, future work and potential applications of the exoskeleton.
task oriented kinematic analysis for a legged robot with half-circular leg morphology. in this paper, we study the kinematics of a legged robot with half-circular leg morphology. in particular, our focus is on the rhex hexapod platform. a new kinematic model for rhex is developed considering the leg shape and its consequences, which was over simplified in the previous models seen in literature. the formulation is an accurate kinematic representation of the robot in the sagittal plane that is based on a four-link mechanism analogy. when only pure rolling motion of the legs are considered, it is found that when front and rear pairs of legs are in contact with the ground, the robot becomes a one degree-offreedom mechanism and position of the middle pair of legs are redundant. the problem is solved in two steps; the first one being the determination of the initial configuration of the leg angular positions which defines the initial value of the variable distance of the front and rear leg and ground contact ponts. after the initial configuration of the system is set, pitch angle of the robot body can be manipulated by controlling one of the leg angular positions and the results are presented on an example case; positioning a body fixed unactuated sensor by controlling robot body pitch angle through the actuation of one of the legs. the results are a good display of the multifunctional aspect of the legs in addition to their use for locomotion.
multi-vehicle path planning in dynamically changing environments. in this paper, we propose a path planning method for nonholonomic multi-vehicle system in presence of moving obstacles. the objective is to find multiple fixed length paths for multiple vehicles with the following properties: (i) bounded curvature (ii) obstacle avoidant (iii) collision free. our approach is based on polygonal approximation of a continuous curve. using this idea, we formulate an arbitrarily fine relaxation of the path planning problem as a nonconvex feasibility optimization problem. then, we propound a nonsmooth dynamical systems approach to find feasible solutions of this optimization problem. it is shown that the trajectories of the nonsmooth dynamical system always converge to some equilibria that correspond to the set of feasible solutions of the relaxed problem. the proposed framework can handle more complex mission scenarios for multi-vehicle systems such as rendezvous and area coverage.
task modeling approach to enhance man-machine collaboration in cell production. the objective of this work is to enhance man-machine collaboration in cell production by task modeling approach. task modeling provides a method to define and study the collaboration between man and machine. six requirements have been derived as basis of development. in this work, the task modeling has extended classical hta method to represent collaborative operation in a hierarchical structure with the classification of operation task levels and extended operation details as task properties. a modeling tool is developed to provide a development and data management platform. the man-machine collaboration is well defined in a structural format by the ability of task analysis method to address human task in a more flexible way. the collaboration modeling and operation resources information have significantly facilitated operation planning in both assembly and control levels. from the case study, the improvement in safety aspect has proven the ability of this approach in assisting safety design and development of production system. the integration with operation control system has shown the execution potential in real-time operation. the unique development of operation data management has expanded this work into operation information support. through the multimodal information support system, the human operator is well guided by the operation information corresponded to the task components. the operation information also can work as evaluation functions to measure the human working performance and system performance as a whole.
a coordinate-free approach to instantaneous kinematics of two rigid objects with rolling contact and its implications for trajectory planning. this paper adopts a coordinate-free approach to investigate the kinematics of rigid bodies with rolling contact. a new equation of angular velocity of the moving body is derived in terms of the magnitude of rolling velocity and two sets of geometric invariants belonging to the respective contact curves. this new formulation can be differentiated up to any order. furthermore, qualitative information about trajectory planning can be deduced from this equation if the characteristics of rolling objects and the motion are taken into consideration.
transfer of knowledge for a climbing virtual human: a reinforcement learning approach. in the reinforcement learning literature, transfer is the capability to reuse on a new problem what has been learnt from previous experiences on similar problems. adapting transfer properties for robotics is a useful challenge because it can reduce the time spent in the first exploration phase on a new problem. in this paper we present a transfer framework adapted to the case of a climbing virtual human (vh). we show that our vh learns faster to climb a wall after having learnt on a different previous wall.
coordinated motion control of multiple passive object handling robots based on environment information. in this paper, we introduce a passive mobile robot called prp (passive robot porter), which has passive dynamics with respect to an applied force and its appropriate motion is controlled based on the servo brakes. in this paper, we especially focus on a motion control algorithm of multiple passive mobile robots for handling a large object in cooperation with a human. by controlling each passive mobile robot in the decentralized way, we realize collision avoidance function and path following function of the object to improve the maneuverability for the human operator. the proposed algorithms applied to two prps actually, and experimental results illustrate the validity of the proposed algorithms.
probabilistic multi-component extended strong tracking filter for mobile robot global localization. this paper proposes a multi-component extended strong tracking filter (mester) for global localization. it is the first time strong tracking filter (stf) is introduced into robotics domain and is fundamentally extended to be suitable for fusing observations with arbitrary time-varying dimensionality, based on equivalent space transformation and extended orthogonality principle. the resulted extended strong tracking filter (estf) is then combined with a probabilistic multi-component evolving mechanism and finally forms the mester localization method. real robot experiments and comparisons with existing methods show that mester has high convergence speed, computational efficiency and definite robustness to sensor noises, kidnapped robot problem, system nonlinearities, and symmetric environments.
surface model reconstruction of 3d objects from multiple views. a points surface reconstruction algorithm of 3d object models from multiple silhouettes is proposed in this paper. some images of the target object are taken from a circular trajectory by a robot with a camera mounted in an eye-in-hand configuration. the silhouettes of the observed object are evaluated for each view using a blob analysis process, and from those a set of points that sample a reconstruction sphere surrounding the target object are estimated. the sphere sample points are attracted by the object center of mass using a variable step according to the distance from the silhouettes contours. for each point, the iterative process of constriction is stopped when all the back-projections of the point are within the corresponding silhouettes. moreover, a new method based on a rough estimation of object dimension is proposed to reduce the disturbances due to projection and shadow cones. simulations and experiments are presented to evaluate the performance of the proposed algorithm.
adaptive autonomous control using online value iteration with gaussian processes. in this paper, we present a novel approach to controlling a robotic system online from scratch based on the reinforcement learning principle. in contrast to other approaches, our method learns the system dynamics and the value function separately, which permits to identify the individual characteristics and is, therefore, easily adaptable to changing conditions. the major problem in the context of learning control policies lies in high-dimensional state and action spaces, that needs to be explored in order to identify the optimal policy. in this paper, we propose an approach that learns the system dynamics and the value function in an alternating fashion based on gaussian process models. additionally, to reduce computation time and to make the system applicable to online learning, we present an efficient sparsification method. in experiments carried out with a real miniature blimp we demonstrate that our approach can learn height control online. further results obtained with an inverted pendulum show that our method requires less data to achieve the same performance as an off-line learning approach.
development of inspection robot for under floor of house. we are developing robots for inspection of the under floor of houses. the developed robot system is reported in this paper. the mobile robot platform is based on a crawer type robot developed for rescue purposes. as sensors, a pan-tilt-zoom camera, top-view camera and sokuiki sensor are used. we constructed a test field and verified the performance of the robot.
detecting repeated motion patterns via dynamic programming using motion density. in this paper, we propose a method that detects repeated motion patterns in a long motion sequence efficiently. repeated motion patterns are the structured information that can be obtained without knowledge of the context of motions. they can be used as a seed to find causal relationships between motions or to obtain contextual information of human activity, which is useful for intelligent systems that support human activity in everyday environment. the major contribution of the proposed method is two-fold: (1) motion density is proposed as a repeatability measure and (2) the problem of finding consecutive time frames with large motion density is formulated as a combinatorial optimization problem which is solved via dynamic programming (dp) in polynomial time o(n log n) where n is the total amount of data. the proposed method was evaluated by detecting repeated interactions between objects in everyday manipulation tasks and outperformed the previous method in terms of both detectability and computational time.