waashk/dblp huggingface dataset:
global transparency analysis of the lawrence teleoperator architecture. despite the frequent use of the lawrence architecture since its introduction in the early 90's, its global transparency characteristics have not yet been fully analyzed. that is the goal of this paper. we state and prove necessary and sufficient conditions for transparency, with special attention to the information sent across the communication layer. in particular, it is shown that transparency can be preserved even though one, and even two, communication channels are set to zero. the results may serve as a guideline for transparent teleoperator design.
synthesizing a desired trajectory and sensory feedback control laws for an origami-folding robot based on the statistical characteristics of direct teaching by a human. in this paper, a novel method to synthesize a desired trajectory and sensory feedback control laws for robots based on the statistical characteristics of direct teaching data by a human is proposed. this work was motivated by a poor performance of an origami-folding robot developed by the authors. since the robot simply replayed a given trajectory without sensory feedback control, it often failed in folding due to the fluctuation of origami paper behaviors. to model the statistical characteristics of the demonstrated motions by a human, a hidden markov model (hmm) is employed. a nominal desired trajectory is obtained by temporally normalizing and spatially averaging the demonstrated motions in a statistical manner. sensory feedback control laws are then synthesized based on the output probability density function parameters of the hmm. considering the velocity variance and the canonical correlation between velocity and force of the teaching data, important motion segments are extracted and the feedback control is applied only for those segments. the proposed method was applied to the origami-folding robot and experimental results showed that the success rate and the folding quality of "valley-fold" were improved. although the demonstrated task is very specific, the proposed method has generality to be applied to other tasks.
a visual odometry framework robust to motion blur. motion blur is a severe problem in images grabbed by legged robots and, in particular, by small humanoid robots. standard feature extraction and tracking approaches typically fail when applied to sequences of images strongly affected by motion blur. in this paper, we propose a new feature detection and tracking scheme that is robust even to non-uniform motion blur. furthermore, we developed a framework for visual odometry based on features extracted out of and matched in monocular image sequences. to reliably extract and track the features, we estimate the point spread function (psf) of the motion blur individually for image patches obtained via a clustering technique and only consider highly distinctive features during matching. we present experiments performed on standard datasets corrupted with motion blur and on images taken by a camera mounted on walking small humanoid robots to show the effectiveness of our approach. the experiments demonstrate that our technique is able to reliably extract and match features and that it is furthermore able to generate a correct visual odometry, even in presence of strong motion blur effects and without the aid of any inertial measurement sensor.
a model of muscle-tendon function in human walking. in this paper, we study the mechanical behavior of leg muscles and tendons during human walking in order to motivate the design of economical robotic legs. we hypothesize that quasi-passive, series-elastic clutch units spanning the knee joint in a musculoskeletal arrangement can capture the dominant mechanical behaviors of the human knee in level-ground walking. since the mechanical work done by the knee joint throughout a level-ground self-selected-speed walking cycle is negative, and since there is no element capable of dissipating mechanical energy in the musculoskeletal model, biarticular elements would necessarily need to transfer energy from the knee joint to hip and/or ankle joints. this mechanism would reduce the necessary actuator work and improve the mechanical economy of a human-like walking robot. as a preliminary evaluation of these hypotheses, we vary model parameters, or spring constants and clutch engagement times, using an optimization scheme that minimizes ankle and hip actuator positive work while still maintaining human-like knee mechanics. for model evaluation, kinetic and kinematic gait data were employed from one study participant walking across a level-ground surface at a self-selected gait speed. with this under-actuated leg model, we find good agreement between the model's quasi-passive knee torque and experimental knee values, suggesting that a knee actuator is not necessary for level-ground robotic ambulation at self-selected gait speeds.
novel design of a 3-axis optical fiber force sensor for applications in magnetic resonance environments. this paper describes a novel design of a 3-axis force sensor which can be applied in magnetic resonance (mr) workspaces such as that of a magnetic resonance imaging (mri) machine. the sensor operates based on an optical sensing principle to measure forces deforming a 3 degree-of-freedom (dof) flexible structure. by detecting minute deflection of such a structure using an optical sensing scheme, the magnitude and direction of an applied force can be determined. the sensor prototype described in this document demonstrates its capability of performing force measurement in both axial and radial directions with the calibrated working ranges of +/-3 n. because all the sensor's components are entirely fabricated from non-metallic and dielectric materials, the sensor is considered suitable for applications in mr environments.
extended nicosia-tomei observer-based tracking control of robot manipulators. this paper presents an observer-based control of robot manipulators for velocity estimation and trajectory tracking. the proposed scheme does not require the velocity feedback because velocity measurements may not be available due to cost and weight. we introduce parameters involving the tracking and estimation errors and their derivatives into the observer-controller. exploiting the structural properties, we propose the new combined form of observer-controller to ensure the closed loop stability of the tracking and estimation. moreover, we show that the proposed controller-observer scheme achieves semi-globally exponential stability results for tracking errors and estimation errors. the proposed observer-controller facilitates the stability analysis and explicitly extends nicosia-tomei observer-based tracking control. to validate the proposed scheme, we conduct numerical simulation of a two-link robot. the simulation results clearly indicate that the proposed scheme improves the error convergence for both trajectory tracking and velocity estimation.
real-time ultrasonic distance measurements for autonomous mobile robots using cross correlation by single-bit signal processing. distance measurement using an ultrasonic wave is suitable for environment recognition in autonomous mobile robots. ultrasonic distance measurement with the pulse-echo method is based on determining the time-of-flight (tof) of the reflected echoes. the pulse-echo method with pulse compression, the cross-correlation method, can improve the distance resolution and the signal-to-noise ratio (snr) of the reflected echo. however, cross correlation of the cross-correlation method requires the high-cost digital signal processing. a sensor signal processing method of cross correlation using a delta-sigma modulated single-bit digital signal has been proposed. cross correlation by single-bit signal processing reduces the calculation cost of cross correlation. furthermore, cross correlation by single-bit signal processing improves the time resolution of digital signal processing. in this paper, the distance resolution of cross correlation by single-bit signal processing is evaluated by computer simulations and experiments of ultrasonic distance measurement. distance measurement from the high-time-resolution cross-correlation function obtained by single-bit signal processing realized high distance resolution from experimental results, despite the low calculation costs.
adding millimeter-sized, rapidly prototyped robotic structures to microfluidic lab-on-a-chip devices. this paper describes a rapid prototyping method to add robotic functionality to microfluidic devices using existing equipment, materials, and methods already employed in photolithography. details on the fabrication as well as basic design and analyses methods are given. these techniques are then employed to fabricate an example structure that is subsequently integrated with a microfluidic channel. the eventual purpose of this example structure would be to serve as an interface between a microfluidic device and its environment, using a brush-like structure to sweep cells into the channel, which could then be delivered to another microfluidic system for analyses of the cells. the resulting brush-like structure fits within a 6mm × 4mm × 2mm volume and can be further miniaturized. the alteration of compressed air and vacuum modulated by pneumatic solenoid valves is used to push and pull a plunger/rod system that actuates the device. the delivery of the pressurized air and vacuum is accomplished through flexible 500µm-diameter tubing to the plunger/rod system but future work would involve completely containing the actuation on a chip-size device
3 axial force sensor for a semi-autonomous snake robot. now that mobile robots are getting tested more and more in challenging areas, difficulties in control, particularly when the robot cannot be seen, have appeared. in this research a mobile snake robot with actuated wheels is given the ability to sense its surroundings through its wheels by 3dof force sensors, so that semi-autonomous control can be realized. this will simplify necessary operator commands and improve situation awareness through information feedback. even with the many limitations of practical robot design, such as unwanted flexibilities, and measuring while actuating the wheels, the sensor's errors are confirmed to vary between just 1% and 3%. moreover, sensitivity is equal over the wheels, only a 3s calibration at startup is needed, and the sensor is shown to be resistant to aging and temperature change. the sensor is implemented directly into a new snake robot, one sensor in each segment. its central control will adjust the snake body according to the surroundings while automatically avoiding obstacles and crossing gaps.
analytic error variance predictions for planar vehicles. path planning algorithms that incorporate risk and uncertainty need to be able to predict the evolution of path-following error statistics for each candidate plan. we present an analytic method to predict the evolving error statistics of a holonomic vehicle following a reference trajectory in a planar environment. this method is faster than integrating the plant through time or performing a monte carlo simulation. it can be applied to systems with external gaussian disturbances, and it can be extended to handle plant uncertainty through numerical quadrature techniques.
range-only slam with a mobile robot and a wireless sensor networks. this paper presents the localization of a mobile robot while simultaneously mapping the position of the nodes of a wireless sensor network using only range measurements. the robot can estimate the distance to nearby nodes of the wireless sensor network by measuring the received signal strength indicator (rssi) of the received radio messages. the rssi measure is very noisy, especially in an indoor environment due to interference and reflections of the radio signals. we adopted an extended kalman filter slam algorithm to integrate rssi measurements from the different nodes over time, while the robot moves in the environment. a simple pre-processing filter helps in reducing the rssi variations due to interference and reflections. successful experiments are reported in which an average localization error less than 1 m is obtained when the slam algorithm has no a priori knowledge on the wireless node positions, while a localization error less than 0.5 m can be achieved when the position of the node is initialized close to the their actual position. these results are obtained using a generic path loss model for the trasmission channel. moreover, no internode communication is necessary in the wsn. this can save energy and enables to apply the proposed system also to fully disconnected networks.
piezoelectrically driven silicon microgrippers integrated with sidewall piezoresistive sensor. this paper presents the design, fabrication, and application of an piezoelectrically driven microgripper integrated sidewall piezoresistive force sensor for measuring the gripping force. surface and bulk micromachining technology is employed to fabricate end-effectors and sensor of the microgripper from a single crystal silicon wafer. vertical sidewall surface piezoresistor etching technique is used to form the side direction sensors. the end-effectors of the gripper are four-bar structures. two fixed cantilever beams integrated with piezoresistive sensor are designed to sense the gripping force, and a piezoelectrically driven microactuator is designed to provide the force to operate the other two movable bars. the piezoelectrically driver adhered with the silicon end-effectors generates a linear horizontal motion 9µm, which is amplified to 30µm at the bar tip of the microgripper. then the range of the operation is 25µm-140µm. testing results verify that the vertical sidewall surface piezoresistor etching technique is effective. the sensitivity of the piezoresistive sensors is better than 72v/n, and the resolution is better than 3µn.
radiation pattern correlation for mobile robot localization in low power wireless networks. we present a new method for localization using received signal strength indicator (rssi) in ordinary wireless communication networks such as specified by ieee 802.15.4. the method exploits the anisotropy of the antenna gain to determine the bearing of the robot relative to reference radio nodes. this method is not only more precise than the mapping of the rssi to distance only, it also allows to estimate the orientation of the robot and to monitor the integrity of the measurement. the integrity measure is also incorporated into the rssi to distance mapping and a thorough error analysis is presented. the paper describes the localization concept and presents experimental results for mobile robot localization in an outdoor environment. the achieved accuracy is significantly increased compared to previously developed rssi based localization methods.
overcoming adhesion forces: active release of micro objects in micromanipulation. due to force scaling laws, rapid, accurate release of micro objects has been a long-standing challenge for microrobotic manipulation. this paper presents an active release technique that for the first time, achieves 100% repeatability and a release accuracy of 0.70±0.46µm, experimentally quantified through the manipulation of 10µm glass spheres under an optical microscope. using a new mems (microelectromechanical systems) microgripper, this technique employs a controllable plunging mechanism for the micro object to gain sufficient momentum to overcome adhesion forces. experimental results also confirmed that this technique is not substrate dependent. theoretical analyses were conducted to understand the release principle. based on this preliminary study, the technique may also prove to be an effective solution to active release of submicron objects in robotic pick-place.
human daily activity recognition in robot-assisted living using multi-sensor fusion. in this paper, we propose a human daily activity recognition method by fusing the data from two wearable inertial sensors attached on one foot and the waist of the subject, respectively. we developed a multi-sensor fusion scheme for activity recognition. first, data from these two sensors are fused for coarse-grained classification in order to determine the type of the activity: zero displacement activity, transitional activity, and strong displacement activity. second, a fine-grained classification module based on heuristic discrimination or hidden markov models (hmms) is applied to further distinguish the activities. we conducted experiments using a prototype wearable sensor system and the obtained results prove the effectiveness and accuracy of our algorithm.
robust backstepping control of active vibration isolation using a stewart platform. this paper focuses on deriving a robust backstepping control approach to solve the active vibration isolation problem using a stewart platform. the dynamics of the stewart platform driven by the linear voice coil motors is developed with the newton-euler method. by fully considering the characteristics of vibration isolation, the properties of the dynamics of the stewart platform are applied to transform the coupled dynamics into six independent single-input single-output (siso) channels. furthermore, in the procedure of controller design, the influence factors of vibration isolation are taken into account, such as the parameter perturbation and the unmodeled dynamics, etc. meanwhile, high-gain design method is employed to deal with the problem introduced by input unmodeled dynamics of the system. it is demonstrated that a sufficiently small l2 gain from disturbance to output can be obtained in lyapunov synthesis. the simulation results show that the controller can effectively attenuate low frequency vibrations in six degrees of freedom (dofs) and a satisfactory vibration isolation performance can be achieved.
software framework for human neuromuscular behavior. in this paper we present our low-level software framework that allows human neuromuscular properties and behaviors to be programmed modularly onto biologically inspired prosthetic devices. specifically this software framework is used at the lowest level of the anatomically correct testbed (act) hand. it abstracts away from the robotic details and allows users including biologists to program individual muscle physiology, multiple muscle synergistic activities, neural commands, etc. independently. our system has been designed to be fault-tolerant with the idea of safe and continued operation of prostheses if a new prototype behavior were to perform incorrectly or outright fail. example coding of hills model is shown.
making networked robots connectivity-aware. maintaining the network connectivity in mobile multi-robot systems (mrss) is a key issue in many robotic applications. in our view, the solution to this problem consists of two main steps: (i) making robots aware of the network connectivity; and (ii), making use of this knowledge to plan robots tasks without compromising connectivity. in this paper, we view the ad-hoc network connectivity as an abstraction that is independent from application issues. we propose a new distributed algorithm executing on individual robots to build the connectivity-awareness. the correctness and theoretical analysis of the proposed algorithm are given. we also show how our solution allows checking network bi-connectivity more efficiently than existing work and can be used, for example, during distributed control motion.
anatomically correct testbed hand control: muscle and joint control strategies. human hands are capable of many dexterous grasping and manipulation tasks. to understand human levels of dexterity and to achieve it with robotic hands, we constructed an anatomically correct testbed (act) hand which allows for the investigation of the biomechanical features and neural control strategies of the human hand. this paper focuses on developing control strategies for the index finger motion of the act hand. a direct muscle position control and a force-optimized joint control are implemented as building blocks and tools for comparisons with future biological control approaches. we show how gaussian process regression techniques can be used to determine the relationships between the muscle and joint motions in both controllers. our experiments demonstrate that the direct muscle position controller allows for accurate and fast position tracking, while the force-optimized joint controller allows for exploitation of actuation redundancy in the finger critical for this redundant system. furthermore, a comparison between gaussian processes and least squares regression method shows that gaussian processes provide better parameter estimation and tracking performance. this first control investigation on the act hand opens doors to implement biological strategies observed in humans and achieve the ultimate human-level dexterity.
natural frequency based optimal design of a two-link flexible manipulator. modern industries, e.g., semiconductor packaging, imposes increasing stringent requirement on equipment with very high acceleration and high precision. traditionally, arm linkage and drive mechanism are first designed followed by control design. the integrated design method is proposed as a preferable technique of the traditional one. in this paper, a general framework of the integrated design method for a point-to-point control is presented. the dynamic model for a flexible planar two-link manipulator is derived by the finite element method. the pd control strategy is applied in the closed-loop system. the structural parameters and control parameters are optimized simultaneously by solving the integrated design problem. the differential evolution (de) technique, a global optimization technique, is used to solve the optimal design problem. a simulation shows the integrated design method gives improved system performance.
probabilistic search optimization and mission assignment for heterogeneous autonomous agents. this paper presents an algorithmic framework for conducting search and identification missions using multiple heterogeneous agents. dynamic objects of type "neutral" or "target" move through a discretized environment. probabilistic representation of the current level of situational awareness - knowledge or belief of object locations and identities - is updated with imperfect observations. optimization of search is formulated as a mixed-integer program to maximize the expected number of targets found and solved efficiently in a receding horizon approach. the search effort is conducted in tandem with object identification and target interception tasks, and a method for assignment of these missions among agents is developed. the proposed framework is demonstrated in simulation studies, and an implementation of its decision support capabilities in a recent field experiment is reported.
harnessing bacterial power in microscale actuation. this paper presents a systematic analysis of the motion of microscale structures actuated by flagellated bacteria. we perform the study both experimentally and theoretically. we use a blotting procedure to attach flagellated bacteria to a buoyancy-neutral plate called a microbarge. the motion of the plate depends on the distribution of the cells on the plate and the stimuli from the environment. we construct a stochastic mathematical model for the system, based on the assumption that the behavior of each bacterium is random and independent of that of its neighbors. the main finding of the paper is that the motion of the barge plus bacteria system is a function of a very small set of parameters. this reduced-dimensional model can be easily estimated using experimental data. we show that the simulation results obtained from the model show an excellent match with the experimentally-observed motion of the barge.