waashk/dblp huggingface dataset:
actuation and position estimation of a passive mobile end effector from across a thin wall for heavy-duty aircraft manufacturing. a passive mobile robot carrying a heavy manufacturing tool is activated from across a thin wall. the mobile robot placed within a confined space has no tether and no local battery, but is powered from an outside robot through magnetic coupling. a pair of magnetic feet allows the passive inside robot to hang from a ceiling and walk across a wall. a heavy manufacturing tool held in the middle of the passive inside robot is activated with a lorentz force actuator - this is also activated from the outside robot. a set of hall effect sensors on the outside robot detect the magnetic field created by the passive robot in order to estimate the position of the inside robot. first, the task conditions and functional requirements are described, and the design concept of the passive mobile robot is presented. an electro-magnetic model for predicting magnetic field strength and load bearing capacity is used to facilitate design as well as to estimate and control the position of the passive inside robot. a proof-of-concept prototype system is designed and built for application to aircraft manufacturing.
body torque modulation for a microrobotic fly. the harvard microrobotics lab has previously demonstrated the world's first at-scale robotic insect capable of vertical takeoff with external power. both of the robot's wings were driven by a single power actuator and 1-dof mechanical transmission - making independent control of both wings, and therefore asymmetric flapping and the generation of a net body torque, impossible. this paper presents a method to modulate body torques by altering the kinematics of each wing transmission independently, via the introduction of two additional control actuators. theoretical kinematic and dynamic predictions based on a pseudo-rigid body model are compared to the observed wing trajectories. controllable body torques are necessary for the development of control algorithms for eventual stable hovering and free flight.
lsh-ransac: an incremental scheme for scalable localization. this paper addresses the problem of feature-based robot localization in large-size environments. with recent progress in slam techniques, it has become crucial for a robot to estimate the self-position in real-time with respect to a large-size map that can be incrementally build by other mapper robots. self-localization using large-size maps have been studied in litelature, but most of them assume that a complete map is given prior to the self-localization task. in this paper, we present a novel scheme for robot localization as well as map representation that can successfully work with large-size and incremental maps. this work combines our two previous works on incremental methods, ilsh and iransac, for appearance-based and position-based localization.
assigning cameras to subjects in video surveillance systems. we consider the problem of tracking multiple agents moving amongst obstacles, using multiple cameras. given an environment with obstacles, and many people moving through it, we construct a separate narrow field of view video for as many people as possible, by stitching together video segments from multiple cameras over time. we employ a novel approach to assign cameras to people as a function of time, with camera switches when needed. the problem is modeled as a bipartite graph and the solution corresponds to a maximum matching. as people move, the solution is efficiently updated by computing an augmenting path rather than by solving for a new matching. this reduces computation time by an order of magnitude. in addition, solving for the shortest augmenting path minimizes the number of camera switches at each update. when not all people can be covered by the available cameras, we cluster as many people as possible into small groups, then assign cameras to groups using a minimum cost matching algorithm. we test our method using numerous runs from different simulators.
finding good cycle constraints for large scale multi-robot slam. in this paper we describe an algorithm to compute cycle constraints that can be used in many graph-based slam algorithms; we exemplify it in hierarchical slam. our algorithm incrementally computes the minimum cycle basis of constraints from which any other cycle can be derived. cycles in this basis are local and of minimum length, so that the associated cycle constraints have less linearization problems. this also permits to construct regional maps, that is, it makes possible efficient and accurate intermediate mapping levels between local maps and the whole global map. we have extended our algorithm to the multi-robot case. we have tested our methodology using the victoria park data set with satisfactory results.
characterization of the compact hokuyo urg-04lx 2d laser range scanner. this paper presents a detailed characterization of the hokuyo urg-04lx 2d laser range finder. while the sensor specifications only provide a rough estimation of the sensor accuracy, the present work analyzes issues such as time drift effects and dependencies on distance, target properties (color, brightness and material) as well as incidence angle. since the sensor is intended to be used for measurements of a tubelike environment on an inspection robot, the characterization is extended by investigating the influence of the sensor orientation and dependency on lighting conditions. the sensor characteristics are compared to those of the sick lms 200 which is commonly used in robotic applications when size and weight are not critical constraints. the results show that the sensor accuracy is strongly depending on the target properties (color, brightness, material) and that it is consequently difficult to establish a calibration model. the paper also identifies cases for which the sensor returns faulty measurements, mainly when the surface has low reflectivity (dark surfaces, foam) or for high incidence angles on shiny surfaces. on the other hand, the repeatability of the sensor seems to be competitive with the lms 200.
tissue identification using inverse finite element analysis of rolling indentation. the authors have recently proposed the method of rolling indentation over soft tissue to rapidly identify soft tissue properties for localization and detection of tissue abnormalities, with the aim of compensating for the loss of haptics information experienced during robotic-assisted minimally invasive surgery (rmis). this paper investigates the concept of rolling indentation using finite element modeling. to obtain ground truth data, rolling indentation experiments are conducted on a silicone phantom which contains three simulated tumours. the tissue phantom is modeled as hyperelastic material using abaqus™. the identification of tumours includes two parts: firstly, when the spatial location of tumour is known, identify the tumour's mechanical properties (initial shear modulus); secondly if the mechanical properties of tumour are known, identify the tumour's spatial location. the results show that the proposed method can identify information of tumours accurately and robustly. the identified tumour mechanical properties and tumour locations are in good agreement with experimental measurements.
surveying noctural cuttlefish camouflage behaviour using an auv. this paper describes a recent study in which an autonomous underwater vehicle (auv) with a high resolution stereo-imaging system was used to document nocturnal camouflage behaviour in cuttlefish at a well known spawning site in whyalla, south australia. the auv's ability to fly at low altitude during day and night while closely following a desired survey pattern provided improved data collection compared to divers and previous work with a small rov. over the course of the week long expedition, the auv sirius was deployed on 38 dives at three sites in the survey area and collected tens of thousands of stereo images. of these, nearly a thousand were seen to contain cuttlefish during post cruise analysis, with a large proportion showing evidence of camouflage. the distribution of images containing cuttlefish suggest that the animal concentrations were substantially higher closer in to shore in shallow waters, where the flat rocky substrate occurs; females lay their eggs on the underside of these rocks. results demonstrate the strengths of using an auv for surveying near-shore benthic habitats of ecological interest, with a particular emphasis on the ability to operate during both day and night time operations.
stochastic strategies for a swarm robotic assembly system. we present a decentralized, scalable approach to assembling a group of heterogeneous parts into different products using a swarm of robots. while the assembly plans are predetermined, the exact sequence of assembly of parts and the allocation of subassembly tasks to robots are determined by the interactions between robots in a decentralized fashion in real time. our approach is based on developing a continuous abstraction of the system derived from models of chemical reactions and formulating the strategy as a problem of selecting rates of assembly and disassembly. these rates are mapped onto probabilities that determine stochastic control policies for individual robots, which then produce the desired aggregate behavior. this top-down approach to determining robot controllers also allows us to optimize the rates at the abstract level to achieve fast convergence to the specified target numbers of products. because the method incorporates programs for assembly and disassembly, changes in demand can lead to reconfiguration in a seamless fashion. we illustrate the methodology using a physics-based simulator with examples involving 15 robots and two types of final products.
active mechanical compensation to obtain gravity-free robots: modeling, control, design and preliminary experimental results. in this paper, a new hybrid active mechanical technique is proposed, which nullifies the torque coming from gravitational acceleration by means of controlled displacements of the center of mass of each link. modeling, design and control issues are presented as well as some preliminary experimental results illustrate this principle.
development and preliminary data of novel integrated optical micro-force sensing tools for retinal microsurgery. this paper reports the development of novel micro-force sensing tools for retinal microsurgery. retinal microsurgery requires extremely delicate manipulation of retinal tissue, and tool-to-tissue interaction forces are frequently below human perceptual thresholds. further, the interaction between the tool shaft and sclera makes accurate sensing of forces exerted on the retina very difficult with previously developed force sensing schemes, in which the sensor is located outside the eye. in the work reported here, we incorporate 160 µm fiber bragg grating (fbg) strain sensors into the tool shaft to sense forces distal to the sclera. the sensor is applicable both with robotically manipulated and freehand tools. preliminary results with a 1 degree-of-freedom (dof) sensor have demonstrated 0.25 mn resolution, and work is underway to develop 2 and 3 dof tools. the design and analysis of the force sensing tool is presented with preliminary testing data and some initial experiments using the tool with both freehand and robotic manipulation.
bounded attitude control of a flapping wing micro aerial vehicle using direct sensors measurements. this paper presents two bounded attitude control laws of a high frequency flapping micro aerial vehicle (fmav) based on sensors measurements feedback. first, a simplified model of a fmav is proposed using only the steady aerodynamic efforts. since solely the averaged forces and torques affect the body's movement, the control laws are computed using the averaged model and applied to the time varying model at the beginning of each wingbeat period. a first control law is developed using a rate gyro (measuring the body's angular velocity), and some reference sensors used to compute the attitude error. a second control law is proposed omitting the rate gyro in order to reduce fmav's size and weight. the control laws are highly simple and bounded in order to prevent the saturation of the actuators and to increase their efficiency. the control strategies are compared and tested with respect to external disturbances.
the columbia grasp database. collecting grasp data for learning and benchmarking purposes is very expensive. it would be helpful to have a standard database of graspable objects, along with a set of stable grasps for each object, but no such database exists. in this work we show how to automate the construction of a database consisting of several hands, thousands of objects, and hundreds of thousands of grasps. using this database, we demonstrate a novel grasp planning algorithm that exploits geometric similarity between a 3d model and the objects in the database to synthesize form closure grasps. our contributions are this algorithm, and the database itself, which we are releasing to the community as a tool for both grasp planning and benchmarking.
node localization during power adjustment in wireless sensor networks. node localization is a challenging problem in wireless sensor networks, especially in the scenarios of tuning multiple transmit-powers. in this article, we utilized particle filter to infer static node position from the correlations between radio frequency (rf) received signal strength indication (rssi) and distance under multiple power settings. the rssi based stochastic measurement model was analyzed and followed by the particle filter design. the simulation results verified the performance of proposed algorithm for localization. the proposed method is contributive in terms of making advantages of multiple transmit power for localization.
wiping motion for deformable object handling. this paper presents wiping motion as a task during which the movement and deformation of a deformable object occur simultaneously. during the wiping motion of a deformable object, there is contact, but no relative movement, between the manipulator and the object, while there is both contact and relative movement between the object and the floor during the displacement of the object. we first describe wiping motion and distinguish wiping slide from wiping deformation by displacement of the internal points of an object. in addition, we show that a wiping motion is an extended system of pushing and sliding of rigid objects. as an example of wiping motion, we utilize grasping of a fabric, and we demonstrate the grasping motion of a fabric using a single-armed gripper.
laser-based detection and tracking moving objects using data-driven markov chain monte carlo. we present a method of simultaneous detection and tracking moving objects from a moving vehicle equipped with a single layer laser scanner. a model-based approach is introduced to interpret the laser measurement sequence by hypotheses of moving object trajectories over a sliding window of time. knowledge of various aspects including object model, measurement model, motion model are integrated in one theoretically sound bayesian framework. the data-driven markov chain monte carlo (ddmcmc) technique is used to sample the solution space effectively to find the optimal solution. experiments and results on real-life data of urban traffic show promising results.
novel parameter estimation schemes in microsystems. this paper presents two novel estimation methods that are designed to enhance our ability of observing, positioning, and physically transforming the objects and/or biological structures in micromanipulation tasks. in order to effectively monitor and position the microobjects, an online calibration method with submicron precision via a recursive least square solution is presented. to provide the adequate information to manipulate the biological structures without damaging the cell or tissue during an injection, a nonlinear spring-mass-damper model is introduced and mechanical properties of a zebrafish embryo are obtained. these two methods are validated on a microassembly workstation and the results are evaluated quantitatively.
design of a robotic system for mri-guided deep brain stimulation electrode placement. deep brain stimulation (dbs) is a technique for influencing brain function though the use of implanted electrodes. direct magnetic resonance (mr) image guidance during dbs insertion would provide many benefits; most significantly, interventional mri can be used for planning, monitoring of tissue deformation, real-time visualization of insertion, and confirmation of placement. the accuracy of standard stereotactic insertion is limited by registration errors and brain movement during surgery. with real-time acquisition of high-resolution mr images during insertion, probe placement can be confirmed intra-operatively. direct mr guidance has not yet taken hold because it is often confounded by a number of issues including: mr-compatibility of existing stereotactic surgery equipment and patient access in the scanner bore. the high resolution images required for neurosurgical planning and guidance require high-field mr (1.5-3t); thus, any system must be capable of working within the constraints of a closed, long-bore diagnostic magnet. currently, no technological solution exists to assist mri guided neurosurgical interventions in an accurate, simple, and economical manner. we present the design of a robotic assistant system that overcomes these difficulties and promises safe and reliable electrode placement in the brain inside closed high-field mri scanners. the robot performs the insertion under real-time 3t mr image guidance. this paper described analysis of the workspace requirements, mr compatibility evaluation, and mechanism design.
turning dynamics and passive damping in flapping flight. we investigated whether flapping flight has an inherent stability by analyzing the inertial and aerodynamic effects of flapping wings on body dynamics. based on wing and body kinematics of free flying fruit flies during rapid maneuvers, we found a passive counter torque due to body rotation. it is indentified both in simulation through quasi-steady state aerodynamic model and through experiments on a dynamically scaled robotic wing. an analytical form is derived correspondingly. in the turning yaw axis, the estimated damping coefficient of flapping wings is significantly higher than body frictional damping; this indicates a passive deceleration during turning. by simulating insect to rotate about each principal axis of inertial and body frames, we calculated the corresponding damping coefficients, and further analyzed the attitude stability. the result reveals that, passive damping of flapping flight, while does not necessarily lead to a stable full body dynamics, provides a considerable passive restoring torque that could be critical for flight stabilization and control in the design of micro aerial vehicles. preliminary analysis on the scaling parameters of passive damping was also performed.
identification of accelerometer orientation errors and compensation for acceleration estimation errors. inertial measurement units (imu) consist of accelerometers. estimation accuracy of acceleration in a particular direction depends on how accurately accelerometers are placed at desired or ideal orientations. the estimation inaccuracy which results from inaccurate orientation of an accelerometer can be eliminated if the orientation error or the angle between the actual and the ideal orientations is known. this paper presents a method of identification of the accelerometer orientation errors without requiring any rotational motion of the imu in which accelerometers are placed. it also presents a method of compensation for the inaccuracy of acceleration estimation due to the accelerometer orientation errors using angular motion information.
'teleportation'-based motion planner for design error analysis. probabilistic path planning techniques have proven to be vital for finding and validating solutions for difficult industrial assembly tasks. nevertheless, the failure of a path planner to find a solution to a task does not suggest how to correct the error. we suggest a methodology to identify possible bottlenecks and present an algorithm to analyze the extent to which the design must be modified in order for the task to complete successfully. we validate our algorithm on two industrial problems involving design errors, and explain how to interpret the results in order to improve the design.
realtime segmentation of range data using continuous nearest neighbors. in mobile robotics, the segmentation of range data is an important prerequisite to object recognition and environment understanding. this paper presents an algorithm for realtime segmentation of a continuous stream of incoming range data. the method is an extension of the previously developed rbnn algorithm and proceeds in two phases: firstly, the normal vector of each incoming point is estimated from its neighborhood, which is continuously monitored. secondly, new points are clustered according to their euclidean and angular distance to previously clustered points. an outline of the algorithm complexity as well as the parameters that influence the segmentation performance is provided. three benchmark scenarios in which the algorithm is deployed on a mobile robot with a laser range finder confirm that the method can robustly segment incoming data at high rates.
analysis and improvement of image-based insertion point estimation for robot-assisted minimally invasive surgery. estimating insertion points of surgical instruments for minimally invasive surgery is a necessary step to be able to control surgical instruments using endoscopic images. in this paper, we propose an analysis of possible methods which use image information only. mathematical properties are detailed together with statistical properties obtained by simulations. then a specific method is chosen to estimate the insertion point for bi-modal surgery (laparoscopy and flexible endoscopy). in vitro experiments show the accuracy of the approach and how it is possible to track the motion of the insertion point in the case of physiological motions.
learning to stabilize the head of a quadrupedal robot with an artificial vestibular system. during quadrupedal robot locomotion, there is pitch, yaw, and roll of the head and body due to the stepping. the head motion adversely affects visual sensors embedded in the robot's head. mammals stabilize the head using a vestibulocollic reflex that detects linear and rotational acceleration. in this paper we describe the use of a machine learning algorithm that utilizes signals from an artificial vestibular system that has been embedded in the robot's head. our approach can rapidly learn to compensate for the head movements that appear when no stabilization mechanism is present. the stabilization using a sony aibo robot occurs in only a few gait cycles.
design principles of large quadrotors for practical applications. virtually all quadrotors used in research weigh less than 2 kg, and carry payload measured in hundreds of grams. to be useful platforms for expanded operations, these vehicles must be capable of carrying greater weight. several obstacles in aerodynamics, design and control must be overcome to enable the construction of larger craft with payloads in excess of 1 kg. we report the key design considerations essential for the construction of heavy quadrotor mavs and demonstrate a 4 kg quadrotor with 1 kg payload.