The International Journal of Robotics Research recent issues

Annual Editorial

Hollerbach, J. — Mon, 26 Oct 2009 09:41:35 PDT

Editorial: Special Issue on the 13th International Symposium on Robotics Research, 2007

Kaneko, M., Nakamura, Y. — Mon, 26 Oct 2009 09:41:35 PDT

Navigating, Recognizing and Describing Urban Spaces With Vision and Lasers

Mon, 26 Oct 2009 09:41:35 PDT

In this paper we describe a body of work aimed at extending the reach of mobile navigation and mapping. We describe how running topological and metric mapping and pose estimation processes concurrently, using vision and laser ranging, has produced a full six-degree-of-freedom outdoor navigation system. It is capable of producing intricate three-dimensional maps over many kilometers and in real time. We consider issues concerning the intrinsic quality of the built maps and describe our progress towards adding semantic labels to maps via scene de-construction and labeling. We show how our choices of representation, inference methods and use of both topological and metric techniques naturally allow us to fuse maps built from multiple sessions with no need for manual frame alignment or data association.

How Should Microrobots Swim?

Mon, 26 Oct 2009 09:41:35 PDT

Microrobots have the potential to dramatically change many aspects of medicine by navigating through bodily fluids to perform targeted diagnosis and therapy. Researchers have proposed numerous micro-robotic swimming methods, with the vast majority utilizing magnetic fields to wirelessly power and control the microrobot. In this paper, we compare three promising methods of microrobot swimming (using magnetic fields to rotate helical propellers that mimic bacterial flagella, using magnetic fields to oscillate a magnetic head with a rigidly attached elastic tail, and pulling directly with magnetic field gradients) considering practical hardware limitations in the generation of magnetic fields. We find that helical propellers and elastic tails have very comparable performance, and they generally become more desirable than gradient pulling as size decreases and as distance from the magnetic-field-generation source increases. We provide a discussion of why helical propellers are likely the best overall choice for in vivo applications.

The Belief Roadmap: Efficient Planning in Belief Space by Factoring the Covariance

Prentice, S., Roy, N. — Mon, 26 Oct 2009 09:41:35 PDT

When a mobile agent does not know its position perfectly, incorporating the predicted uncertainty of future position estimates into the planning process can lead to substantially better motion performance. However, planning in the space of probabilistic position estimates, or belief space, can incur a substantial computational cost. In this paper, we show that planning in belief space can be performed efficiently for linear Gaussian systems by using a factored form of the covariance matrix. This factored form allows several prediction and measurement steps to be combined into a single linear transfer function, leading to very efficient posterior belief prediction during planning. We give a belief-space variant of the probabilistic roadmap algorithm called the belief roadmap (BRM) and show that the BRM can compute plans substantially faster than conventional belief space planning. We conclude with performance results for an agent using ultra-wide bandwidth radio beacons to localize and show that we can efficiently generate plans that avoid failures due to loss of accurate position estimation.

A Fast Stereo-based System for Detecting and Tracking Pedestrians from a Moving Vehicle

Bajracharya, M., Moghaddam, B., Howard, A., Brennan, S., Matthies, L. H. — Mon, 26 Oct 2009 09:41:35 PDT

In this paper we describe a fully integrated system for detecting, localizing, and tracking pedestrians from a moving vehicle. The system can reliably detect upright pedestrians to a range of 40 m in lightly cluttered urban environments. The system uses range data from stereo vision to segment the scene into regions of interest, from which shape features are extracted and used to classify pedestrians. The regions are tracked using shape and appearance features. Tracking is used to temporally filter classifications to improve performance and to estimate the velocity of pedestrians for use in path planning. The end-to-end system runs at 5 Hz on 1,024 x 768 imagery using a standard 2.4 GHz Intel Core 2 Quad processor, and has been integrated and tested on multiple ground vehicles and environments. We show performance on a diverse set of datasets with groundtruth in outdoor environments with varying degrees of pedestrian density and clutter. In highly cluttered urban environments, the detection rates are on a par with state-of-the-art but significantly slower systems.

Growing Hidden Markov Models: An Incremental Tool for Learning and Predicting Human and Vehicle Motion

Vasquez, D., Fraichard, T., Laugier, C. — Mon, 26 Oct 2009 09:41:35 PDT

Modeling and predicting human and vehicle motion is an active research domain. Owing to the difficulty in modeling the various factors that determine motion (e.g. internal state, perception) this is often tackled by applying machine learning techniques to build a statistical model, using as input a collection of trajectories gathered through a sensor (e.g. camera, laser scanner), and then using that model to predict further motion. Unfortunately, most current techniques use offline learning algorithms, meaning that they are not able to learn new motion patterns once the learning stage has finished. In this paper, we present an approach where motion patterns can be learned incrementally, and in parallel with prediction. Our work is based on a novel extension to hidden Markov models, called growing hidden Markov models, which gives us the ability to learn incrementally both the parameters and the structure of the model. The proposed approach has been evaluated using synthetic and real trajectory data. In our experiments our approach consistently learned motion models that were more compact and accurate than those produced by two other state-of-the-art techniques.

Requirements for Safe Robots: Measurements, Analysis and New Insights

Haddadin, S., Albu-Schaffer, A., Hirzinger, G. — Mon, 26 Oct 2009 09:41:35 PDT

Physical human—robot interaction and cooperation has become a topic of increasing importance and of major focus in robotics research. An essential requirement of a robot designed for high mobility and direct interaction with human users or uncertain environments is that it must in no case pose a threat to the human. Until recently, quite a few attempts were made to investigate real-world threats via collision tests and use the outcome to considerably improve safety during physical human—robot interaction. In this paper, we give an overview of our systematic evaluation of safety in human—robot interaction, covering various aspects of the most significant injury mechanisms. In order to quantify the potential injury risk emanating from such a manipulator, impact tests with the DLR-Lightweight Robot III were carried out using standard automobile crash test facilities at the German Automobile Club (ADAC). Based on these tests, several industrial robots of different weight have been evaluated and the influence of the robot mass and velocity have been investigated. The evaluated non-constrained impacts would only partially capture the nature of human—robot safety. A possibly constrained environment and its effect on the resulting human injuries are discussed and evaluated from different perspectives. As well as such impact tests and simulations, we have analyzed the problem of the quasi-static constrained impact, which could pose a serious threat to the human even for low-inertia robots under certain circumstances. Finally, possible injuries relevant in robotics are summarized and systematically classified.

Robot-assisted Long Bone Fracture Reduction

Mon, 28 Sep 2009 09:15:39 PDT

The preferred treatment of femoral (thigh bone) shaft fractures nowadays is the minimally invasive technique of intramedullary nailing. However, in addition to its advantages, this technique also has a number of disadvantages, such as the frequent occurrence of malaligned fracture reductions and high X-ray exposure, especially to the operating team. The aim of our research is to overcome these shortcomings by utilizing modern techniques such as three-dimensional (3D) imaging, navigation, and robotics. In this paper we present the current state of our interdisciplinary research project. We first introduce a telemanipulated fracture reduction procedure, which is based on 3D imaging data. This set-up is improved one step further towards an automated fracture reduction procedure. Finally, two drilling tasks, namely the opening of the medullar cavity and the distal locking of the intramedullary nail, are presented, which are supported by automated X-ray-based image analysis and robot-assisted drill guidance. We show that high reduction accuracies can be achieved with our robotic system. Furthermore, the robot-assisted drill guidance achieves superior results with respect to increased precision and decreased X-ray exposure compared with the conventional procedure. We conclude that this surgical procedure benefits conspicuously from the support of robotic assistance systems and that further research and development in this field is worthwhile.

Hyperelastic Model of Anisotropic Fiber Reinforcements within Intestinal Walls for Applications in Medical Robotics

Ciarletta, P., Dario, P., Tendick, F., Micera, S. — Mon, 28 Sep 2009 09:15:39 PDT

The development of an anatomically realistic model of intestinal tissue is essential for the progress of several clinical applications of medical robotics. A hyperelastic theory of the layered structure of the intestine is proposed in this paper to reproduce its purely elastic passive response from the structural organization of its main constituents. The hyperelastic strain energy function is decoupled into an isotropic term, describing the ground biological matrix, and an anisotropic term, describing the single contributions of the directional fiber-reinforcements. The response of the muscular coat layer has been modeled as a stiffening effect due to two longitudinal and circular muscular reinforcements. The contribution of the submucosa has been described from a uniform distribution of fibrillar collagen in a cross-ply arrangement. An experimental procedure has been proposed in order to characterize the passive response of porcine intestinal samples from planar uniaxial traction and shear tests. The experimental data have been non-linearly fitted in the least square sense with the results of the theoretical predictions. The mechanical parameters have been fitted with high accuracy (R_min=0.9329, RMSE_max =0.01167), demonstrating the ability of the model to reproduce the mechanical coupling due to the presence of multiple directional reinforcements. The fundamental mechanical role of collagen morphology in the passive biomechanical behavior of intestinal wall is demonstrated. These results may drive a better understanding of the key factors in growth and remodeling of healthy and diseased tissue, together with numerous applications in robotic endoscopy, minimally invasive surgery, and biomedical research.

Haptic Effects of Surgical Teleoperator Flexibility

Tavakoli, M., Howe, R. D. — Mon, 28 Sep 2009 09:15:39 PDT

Minimally invasive surgery systems typically involve thin and cable-driven surgical instruments. This introduces link and joint flexibility in the slave robot of a master—slave teleoperation system, reducing the effective stiffness of the slave and the transparency of teleoperation. In this paper, we analyze transparency under slave link and joint flexibility (tool flexibility). We also evaluate the added benefits of using extra sensors at the tip of the flexible robot. It is shown that tip velocity (or position) feedback improves free-space position tracking performance in the presence of robot flexibility. Also, when the interaction forces with an environment are measured by a force sensor and fed back to the user’s hand, tip velocity feedback improves hard-contact force tracking performance. During a hard contact task, tip velocity feedback can also eliminate the transmission of robot flexibility to the user’s hand.

Stitching Planning in Laparoscopic Surgery: Towards Robot-assisted Suturing

Nageotte, F., Zanne, P., Doignon, C., de Mathelin, M. — Mon, 28 Sep 2009 09:15:39 PDT

The work presented in this paper addresses the problem of the stitching task in laparoscopic surgery using a circular needle and a conventional four-degree-of-freedom needle holder. This task is particularly difficult for surgeons because of the kinematic constraints generated by the fulcrum in the abdominal wall of the patient. In order to assist the surgeons during suturing, we propose to compute possible paths for the needle through the tissues, which limit tissues deformation as much as possible while driving the needle towards the desired target. We propose a kinematic analysis and geometric modeling of the stitching task from which useful information can be obtained to assist the surgeon. The description of the task with appropriate state variables allows us to propose a simple practical method for computing optimal paths. Simulations show that the obtained paths are satisfactory even under difficult configurations and short computation times make the technique useful for intra-operative planning. The use of the stitching planning is shown for manual as well as for robot-assisted interventions in in vitro experiments.

Identification of Human Limb Viscoelasticity using Robotics Methods to Support the Diagnosis of Neuromuscular Diseases

Venture, G., Yamane, K., Nakamura, Y., Yamamoto, T. — Mon, 28 Sep 2009 09:15:39 PDT

In this paper we present an original method to estimate in vivo the joint dynamics of the human limbs. The method is based on a non-invasive and painless technology making use of an optical motion capture system and an associated skeletal model to record the human motion and compute its kinematics and its dynamics. The formalism that is used for the identification is commonly used in robotics. The passive limb joints properties are modeled by enhanced spring-damper systems. The inverse dynamics is sampled along a movement to give an over-determined system. The obtained system is solved by the linear least-squares method. To perform the estimation, we place emphasis on giving indicators and requirements to interpret the obtained results, and on using painless, passive constraint-free movements that are usually performed during the clinical diagnosis of neuromuscular diseases. Finally the method is experimentally applied to two healthy subjects and five patients of neuromuscular diseases in order to estimate the upper-limb viscoelastic properties. The obtained results are discussed.

Real-time Motion Stabilization with B-mode Ultrasound Using Image Speckle Information and Visual Servoing

Krupa, A., Fichtinger, G., Hager, G. D. — Mon, 28 Sep 2009 09:15:39 PDT

We develop visual servo control to stabilize the image of moving soft tissue in B-mode ultrasound (US) imaging. We define the target region in a B-mode US image, and automatically control a robot to manipulate a an US probe by minimizing the difference between the target and the most recently acquired US image. We exploit tissue speckle information to compute the relative pose between the probe and the target region. In-plane motion is handled by image region tracking and out-of-plane motion recovered by speckle tracking using speckle decorrelation. A visual servo control scheme is then applied to manipulate the US probe to stabilize the target region in the live US image. In a first experiment involving only translational motion, an US phan-In a first experiment involving only translational motion, an US phantom was moved by one robot while stabilizing the target with a second robot holding the US probe. In a second experiment, large six-degree-of-freedom (DOF) motions were manually applied to an US phantom while a six-DOF medical robot was controlled automatically to compensate for the probe displacement. The obtained results support the hypothesis that automated motion stabilization shows promise for a variety of US-guided medical procedures such as prostate cancer brachytherapy.

Robotic Motion Compensation for Beating Heart Intracardiac Surgery

Yuen, S. G., Kettler, D. T., Novotny, P. M., Plowes, R. D., Howe, R. D. — Mon, 28 Sep 2009 09:15:40 PDT

3D ultrasound imaging has enabled minimally invasive, beating heart intracardiac procedures. However, rapid heart motion poses a serious challenge to the surgeon that is compounded by significant time delays and noise in 3D ultrasound. This paper investigates the concept of using a one-degree-of-freedom motion compensation system to synchronize with tissue motions that may be approximated by 1D motion models. We characterize the motion of the mitral valve annulus and show that it is well approximated by a 1D model. The subsequent development of a motion compensation instrument (MCI) is described, as well as an extended Kalman filter (EKF) that compensates for system delays. The benefits and robustness of motion compensation are tested in user trials under a series of non-ideal tracking conditions. Results indicate that the MCI provides an approximately 50% increase in dexterity and 50% decrease in force when compared with a solid tool, but is sensitive to time delays. We demonstrate that the use of the EKF for delay compensation restores performance, even in situations of high heart rate variability. The resulting system is tested in an in vitro 3D ultrasound-guided servoing task, yielding accurate tracking (1.15 mm root mean square) in the presence of noisy, time-delayed 3D ultrasound measurements.

Insertable Surgical Imaging Device with Pan, Tilt, Zoom, and Lighting

Hu, T., Allen, P. K., Hogle, N. J., Fowler, D. L. — Mon, 28 Sep 2009 09:15:40 PDT

In this paper we describe work we have done in developing an insertable surgical imaging device with multiple degrees of freedom for minimally invasive surgery. The device is fully insertable into the abdomen using standard 12 mm trocars. It consists of a modular camera and lens system which has pan and tilt capability provided by two small DC servo motors. It also has its own integrated lighting system that is part of the camera assembly. Once the camera is inserted into the abdomen, the insertion port is available for additional tooling, motivating the idea of single-port surgery. A third zoom axis has been designed for the camera as well, allowing close-up and far-away imaging of surgical sites with a single camera unit. In animal tests with the device we have performed surgical procedures including cholecystectomy, appendectomy, running (measuring) the bowel, suturing, and nephrectomy. Preliminary tests suggest that the new device may have advantages over a standard laparoscope including the following.

• Low-cost and simple design.

• Easier and more intuitive to use than a standard laparoscope.

• Joystick operation requires no specialized operator training.

• Pan/tilt functions provide a large imaging volume not restricted by the fulcrum point of standard laparoscope.

• Time to perform procedures was better than or equivalent to a standard laparoscope.

We believe these insertable platforms will be an integral part of future surgical systems. The platforms can be used with tooling as well as imaging devices, allowing many surgical procedures to be performed using such a system.

Dual-channel Haptic Synthesis of Viscoelastic Tissue Properties using Programmable Eddy Current Brakes

Gosline, A. H. C., Hayward, V. — Mon, 28 Sep 2009 09:15:40 PDT

We describe a novel method for haptic synthesis of viscoelastic responses which employs a dual-channel haptic interface. It has motors that generate torque independently of velocity and brakes that generate viscous torque independently of position. In this way, twice as many states are directly accessible, which reduces reliance on observation and feedback. Torque-generating actuators, e.g. DC motors, are well known. For the viscous actuators, we use eddy current brakes as programmable, linear, non-contact, physical dampers. By decomposing a mechanical impedance to be realized into viscous and elastic components, we can dedicate each actuator to that component it is ideally suited to synthesize, dampers for the viscous component, and motors for the elastic component. The decomposition is in general not unique so it is possible to select the option that takes the best advantage of the hardware. Experimental results show that this technique can render a variety of viscoelastic models without the artifacts that can occur when synthesizing viscous components on conventional haptic interfaces. The synthesized mechanical impedances have guaranteed passivity, and can have arbitrarily high or low viscous and elastic components.

Erratum

Mon, 28 Sep 2009 09:15:40 PDT

Editorial: Special Issue on Medical Robotics

Desai, J. P., Ayache, N. — Fri, 21 Aug 2009 01:41:50 PDT

Robot-assisted Active Catheter Insertion: Algorithms and Experiments

Jayender, J., Patel, R.V., Nikumb, S. — Fri, 21 Aug 2009 01:41:50 PDT

Angioplasty is a frequently performed clinical procedure in which a catheter is inserted into a blood vessel under image guidance to open narrowed or blocked arteries and to allow normal blood flow to resume. This paper is concerned with the development of algorithms for a robot-assisted method for a more accurate, safer and more reliable approach for catheter insertion that can reduce the potential for injury to patients and radiation exposure or discomfort to clinicians. A force control algorithm is presented for a robot to control the force of insertion of a catheter and prevent the catheter from buckling or "bunching up" during insertion. In addition, the paper also describes a master—slave control strategy to precisely control the bending angle of the tip of an active catheter instrumented with Shape Memory Alloy (SMA) actuators. A novel model for SMAs and a robust H loop-shaping controller have been implemented to guarantee robust performance of the active catheter. The algorithms for catheter insertion developed in this paper may help to prevent damage to the epithelial cells of an artery and enable easier guidance of the catheter into appropriate branches. In addition, a robotics-based approach could make it possible for a clinician to remotely perform the insertion of the active catheter from a safe and comfortable environment, thereby reducing exposure to harmful X-ray radiation. Experimental results are presented to illustrate the performance of the algorithms.

Robot-assisted Tactile Sensing for Minimally Invasive Tumor Localization

Fri, 21 Aug 2009 01:41:50 PDT

The 10 mm incisions used in minimally invasive cancer surgery prevent the direct palpation of internal organs, making intraoperative tumor localization difficult. A tactile sensing instrument (TSI), which uses a commercially available sensor to measure distributed pressure profiles along the contacting surface, has been developed to facilitate remote tissue palpation. The objective of this research is to assess the feasibility of using the TSI under robotic control to reliably locate underlying tumors while reducing collateral tissue trauma. The performance of humans and a robot using the TSI to locate tumor phantoms embedded into ex vivo bovine livers is compared. An augmented hybrid impedance control scheme has been implemented on a Mitsubishi PA10-7C to perform the force/position control used in the trials. The results show that using the TSI under robotic control realizes an average 35% decrease in the maximum forces applied and a 50% increase in tumor detection accuracy when compared to manual manipulation of the same instrument. This demonstrates that the detection of tumors using tactile sensing is highly dependent on how consistently the forces on the tactile sensing area are applied, and that robotic assistance can be of great benefit when trying to localize tumors in minimally invasive surgery.

Design and Integration of a Telerobotic System for Minimally Invasive Surgery of the Throat

Fri, 21 Aug 2009 01:41:50 PDT

In this paper we present the clinical motivation, design specifications, kinematics, statics, and actuation compensation for a newly constructed telerobotic system for Minimally Invasive Surgery (MIS) of the throat. A hybrid dual-arm telesurgical slave, with 20 joint-space Degrees-of-Freedom (DoFs), is used in this telerobotic system to provide the necessary dexterity in deep surgical fields such as the throat. The telerobotic slave uses novel continuum robots that use multiple super-elastic backbones for actuation and structural integrity. We present the kinematics of the telesurgical slave and methods for actuation compensation to cancel the effects of backlash, friction, and flexibility of the actuation lines. A method for actuation compensation is presented in order to overcome uncertainties of modeling, friction, and backlash. This method uses a tiered hierarchy of two novel approaches of actuation compensation for remotely actuated snake-like robots. The tiered approach for actuation compensation uses compensation in both joint space and configuration space of the continuum robots. These hybrid actuation compensation schemes use intrinsic model information and external data through a recursive linear estimation algorithm and involve compensation using configuration space and joint space variables. Experimental results validate the ability of our integrated telemanipulation system through experiments of suturing and knot tying in confined spaces.

A Force Feedback Teleoperated Needle Insertion Device for Percutaneous Procedures

Piccin, O., Barbe, L., Bayle, B., de Mathelin, M., Gangi, A. — Fri, 21 Aug 2009 01:41:50 PDT

A novel robotized tool for percutaneous interventions under CT-scanner guidance is presented in this paper. This teleoperated compact robotic device can be used as an end-effector for an image-guided positioning robot. It is fully compatible with computed tomography constraints. In particular, it is able to manipulate needles that are longer than the overall height of its body. This novel device mimics the manual gesture performed by the physician by grasping and re-grasping the needle. This operating principle enables direct force measurement on the inserted surgical needle and allows efficient teleoperation with force feedback. In the paper, the specifications of this needle driver are presented and the proposed design is explained. Experiments conducted on swine under operating conditions were performed in order to validate both the concept and the design of the proposed insertion device in the context of teleoperated needle insertions with force feedback.

MRI-based Medical Nanorobotic Platform for the Control of Magnetic Nanoparticles and Flagellated Bacteria for Target Interventions in Human Capillaries

Fri, 21 Aug 2009 01:41:50 PDT

Medical nanorobotics exploits nanometer-scale components and phenomena with robotics to provide new medical diagnostic and interventional tools. Here, the architecture and main specifications of a novel medical interventional platform based on nanorobotics and nanomedicine, and suited to target regions inaccessible to catheterization, are described. The robotic platform uses magnetic resonance imaging (MRI) for feeding back information to a controller responsible for the real-time control and navigation along pre-planned paths in the blood vessels of untethered magnetic carriers, nanorobots, and/or magnetotactic bacteria (MTB) loaded with sensory or therapeutic agents acting like a wireless robotic arm, manipulator, or other extensions necessary to perform specific remote tasks. Unlike known magnetic targeting methods, the present platform allows us to reach locations deep in the human body while enhancing targeting efficacy using real-time navigational or trajectory control. We describe several versions of the platform upgraded through additional software and hardware modules allowing enhanced targeting efficacy and operations in very difficult locations such as tumoral lesions only accessible through complex microvasculature networks.

The RAVEN: Design and Validation of a Telesurgery System

Fri, 21 Aug 2009 01:41:50 PDT

The collaborative effort between fundamental science, engineering and medicine provides physicians with improved tools and techniques for delivering effective health care. Minimally invasive surgery (MIS) techniques have revolutionized the way a number of surgical procedures are performed. Recent advances in surgical robotics are once again revolutionizing MIS interventions and open surgery. In an earlier research endeavor, 30 surgeons performed 7 different MIS tasks using the Blue Dragon system to collect measurements of position, force, and torque on a porcine model. This data served as the foundation for a kinematic optimization of a spherical surgical robotic manipulator. Following the optimization, a seven-degree-of-freedom cable-actuated surgical manipulator was designed and integrated, providing all degrees of freedom present in manual MIS as well as wrist joints located at the surgical end-effector. The RAVEN surgical robot system has the ability to teleoperate utilizing a single bi-directional UDP socket via a remote master device. Preliminary telesurgery experiments were conducted using the RAVEN. The experiments illustrated the system’s ability to operate in extreme conditions using a variety of network settings.

A Compact Modular Teleoperated Robotic System for Laparoscopic Surgery

Berkelman, P., Ji Ma, — Fri, 21 Aug 2009 01:41:50 PDT

Compared with traditional open surgery, minimally invasive surgical procedures reduce patient trauma and recovery time, but the dexterity of the surgeon in laparoscopic surgery is reduced owing to the small incisions, long instruments and limited indirect visibility of the operative site inside the patient. Robotic surgical systems, teleoperated by surgeons from a master control console with joystick-type manipulation interfaces, have been commercially developed yet their adoption into standard practice may be limited owing to their size, complexity, cost and time-consuming setup, maintenance and sterilization procedures. The goal of our research is to improve the effectiveness of robot-assisted surgery by developing much smaller, simpler, modular, teleoperated robotic manipulator systems for minimally invasive surgery.

A High-performance Redundantly Actuated Parallel Mechanism for Ankle Rehabilitation

Saglia, J.A., Tsagarakis, N.G., Dai, J.S., Caldwell, D.G. — Fri, 21 Aug 2009 01:41:50 PDT

In this paper we present a redundantly actuated parallel mechanism for ankle rehabilitation. The proposed device has the advantage of mechanical and kinematic simplicity when compared with the state-of-the-art multi-degree-of-freedom parallel mechanism prototypes while at the same time it is fully capable of carrying out the exercises required by the ankle rehabilitation protocols. Optimization of the device workspace, dexterity, torque output and size was carried out during the design phase of the device. The development of the system involved the realization of a new customized linear actuator able to meet the speed and force requirements of the device functionality. We also discuss the impedance-based control scheme used for the redundantly actuated device, which allows the execution of both assistive and resistive strengthening rehabilitation regimes. Results from the control of a single linear actuator and further experimental tests including the position tracking of the fully actuated platform are presented. It is believed that the performance and the simplicity of the proposed mechanism will allow the widespread use of the system as a new aid tool for ankle rehabilitation.

Development and Experimental Evaluation of Oral Rehabilitation Robot that Provides Maxillofacial Massage to Patients with Oral Disorders

Ishii, H., Koga, H., Obokawa, Y., Solis, J., Takanishi, A., Katsumata, A. — Fri, 21 Aug 2009 01:41:50 PDT

We have developed an oral-rehabilitation robot WAO-1 (Waseda Asahi Oral-rehabilitation robot No. 1) for use in cases of oral disorders such as temperomandibular joint (TMJ) disorder and dry mouth. WAO-1 is the first robot designed to provide massage to the facial tissues of a patient with oral disorders. This robot provides massage to the masseter and temporal muscles and to the parotid gland and duct with simple operation. It consists of two six-degree-of-freedom arms with plungers, a body with headrest, a control box, a PC, and an automatic massage trajectory generation system with virtual compliance control. Two evaluation experiments were performed to verify the effectiveness of the oral massages of WAO-1 compared with the massages given by doctors. In the experiments, the massage to the parotid gland and duct by WAO-1 increased the amount of saliva in the subjects, and the massage to the masseter muscle by WAO-1 increased facial skin temperature and width of the masseter muscle in the subjects. We consider that these results indicate that massage by WAO-1 can be effective for patients with oral disorders.

A Robotic Neural Interface for Autonomous Positioning of Extracellular Recording Electrodes

Fri, 21 Aug 2009 01:41:50 PDT

In this paper we describe a set of algorithms and a novel miniature device that together can autonomously position electrodes in neural tissue to obtain high-quality extracellular recordings. This robotic system moves each electrode to detect the signals of individual neurons, optimize the signal quality of a target neuron, and then maintain this signal over time. Such neuronal signals provide the key inputs for emerging neuroprosthetic medical devices and serve as the foundation of basic neuroscientific and medical research. Experimental results from extensive use of the robotic electrodes in macaque parietal cortex are presented to validate the method and to quantify its effectiveness.

Editorial: Selected Papers from Robotics: Science and Systems 2008

Trinkle, J., Hirai, S. — Thu, 30 Jul 2009 03:56:01 PDT

Planning Long Dynamically Feasible Maneuvers for Autonomous Vehicles

Likhachev, M., Ferguson, D. — Thu, 30 Jul 2009 03:56:01 PDT

In this paper, we present an algorithm for generating complex dynamically feasible maneuvers for autonomous vehicles traveling at high speeds over large distances. Our approach is based on performing anytime incremental search on a multi-resolution, dynamically feasible lattice state space. The resulting planner provides real-time performance and guarantees on and control of the suboptimality of its solution. We provide theoretical properties and experimental results from an implementation on an autonomous passenger vehicle that competed in, and won, the Urban Challenge competition.

Distributed Localization of Modular Robot Ensembles

Funiak, S., Pillai, P., Ashley-Rollman, M. P., Campbell, J. D., Goldstein, S. C. — Thu, 30 Jul 2009 03:56:01 PDT

Internal localization, the problem of estimating relative pose for each module of a modular robot, is a prerequisite for many shape control, locomotion, and actuation algorithms. In this paper, we propose a robust hierarchical approach that uses normalized cut to identify dense sub-regions with small mutual localization error, then progressively merges those sub-regions to localize the entire ensemble. Our method works well in both two and three dimensions, and requires neither exact measurements nor rigid inter-module connectors. Most of the computations in our method can be distributed effectively. The result is a robust algorithm that scales to large ensembles. We evaluate our algorithm in two- and three-dimensional simulations of scenarios with up to 10,000 modules.

Planning and Control of Ensembles of Robots with Non-holonomic Constraints

Michael, N., Kumar, V. — Thu, 30 Jul 2009 03:56:01 PDT

In this paper we focus on the construction of distributed formation control laws that permit the control of individual mobile robots in a formation to a desired distribution with minimal knowledge of the global state. As in previous work, we consider an abstraction of the team that is derived from a shape descriptor of the ensemble and the position and orientation of the ensemble. We consider the control of the abstract state with decentralized control laws which are independent of the number of agents. However, we incorporate an important departure from previous work by explicitly modeling the shape of the robot, the geometric, non-interpenetration constraints and non-holonomic, kinematic constraints. Further, we propose a motion planning technique to plan motions for ensembles of robots. We demonstrate the effectiveness of the algorithms on a team of differential drive robots in simulation and on real hardware.

Using Multi-view Recognition and Meta-data Annotation to Guide a Robot's Attention

Thomas, A., Ferrari, V., Leibe, B., Tuytelaars, T., Van Gool, L. — Thu, 30 Jul 2009 03:56:01 PDT

In the transition from industrial to service robotics, robots will have to deal with increasingly unpredictable and variable environments. We present a system that is able to recognize objects of a certain class in an image and to identify their parts for potential interactions. The method can recognize objects from arbitrary viewpoints and generalizes to instances that have never been observed during training, even if they are partially occluded and appear against cluttered backgrounds. Our approach builds on the implicit shape model of Leibe et al. We extend it to couple recognition to the provision of meta-data useful for a task and to the case of multiple viewpoints by integrating it with the dense multi-view correspondence finder of Ferrari et al. Meta-data can be part labels but also depth estimates, information on material types, or any other pixelwise annotation. We present experimental results on wheelchairs, cars, and motorbikes.

Probabilistic Models of Object Geometry with Application to Grasping

Glover, J., Rus, D., Roy, N. — Thu, 30 Jul 2009 03:56:01 PDT

Robot manipulators typically rely on complete knowledge of object geometry in order to plan motions and compute grasps. However, when an object is not fully in view it can be difficult to form an accurate estimate of the object's shape and pose, particularly when the object deforms. In this paper we describe a generative model of object geometry based on Mardia and Dryden's "Probabilistic Procrustean Shape", which captures both non-rigid deformations and object variability in a class. We extend their shape model to the setting where point correspondences are unknown using Scott and Nowak's COPAP framework. We use this model to recognize objects in a cluttered image and to infer their complete two-dimensional boundaries with a novel algorithm called OSIRIS. We show examples of learned models from image data and demonstrate how the models can be used by a manipulation planner to grasp objects in cluttered visual scenes.

Friction-Induced Velocity Fields for Point Parts Sliding on a Rigid Oscillated Plate

Vose, T. H., Umbanhowar, P., Lynch, K. M. — Thu, 30 Jul 2009 03:56:01 PDT

We show that small-amplitude periodic motion of a rigid plate causes point parts in frictional contact with the plate to move as if they are in a position-dependent velocity field. Further, we prove that every periodic plate motion maps to a unique velocity field. By allowing a plate to oscillate with six degrees of freedom, we can create a large family of programmable velocity fields. We examine in detail the class of plate motions described by sinusoidal linear and angular accelerations with a single frequency. We hypothesize that this simple class can generate all velocity fields that have constant and linear terms with respect to position, as well as some quadratic fields with respect to position. This set includes fields with isolated sinks and squeeze lines that can be used to perform tasks such as sensorless part orientation. Several of these fields have been verified on our programmable parts-feeding oscillatory device (PPOD). The PPOD is a parallel manipulator similar to a Stewart platform, but with flexures as joints. An iterative learning control algorithm is described that moves the platform with the six-degree-of-freedom periodic motion that creates the desired velocity field.

Metastable Walking Machines

Byl, K., Tedrake, R. — Thu, 30 Jul 2009 03:56:01 PDT

Legged robots that operate in the real world are inherently subject to stochasticity in their dynamics and uncertainty about the terrain. Owing to limited energy budgets and limited control authority, these "disturbances" cannot always be canceled out with high-gain feedback. Minimally actuated walking machines subject to stochastic disturbances no longer satisfy strict conditions for limit-cycle stability; however, they can still demonstrate impressively long-living periods of continuous walking. Here, we employ tools from stochastic processes to examine the "stochastic stability" of idealized rimless-wheel and compass-gait walking on randomly generated uneven terrain. Furthermore, we employ tools from numerical stochastic optimal control to design a controller for an actuated compass gait model which maximizes a measure of stochastic stability—the mean first-passage time—and compare its performance with a deterministic counterpart. Our results demonstrate that walking is well characterized as a metastable process, and that the stochastic dynamics of walking should be accounted for during control design in order to improve the stability of our machines.

Nanonewton Force Sensing and Control in Microrobotic Cell Manipulation

Xinyu Liu, , Kim, K., Yong Zhang, , Yu Sun, — Thu, 30 Jul 2009 03:56:01 PDT

Cellular force sensing and control techniques are capable of enhancing the dexterity and reliability of microrobotic cell manipulation systems. In this paper we present two experimental techniques for nanonewton force sensing and control in microrobotic cell manipulation. A vision-based cellular force sensing approach, including a microfabricated elastic cell holding device and a sub-pixel visual tracking algorithm, was developed for resolving forces down to 3.7 nN during microrobotic mouse embryo injection. The technique also experimentally demonstrated that the measured mechanical difference could be useful for in situ differentiation of healthy mouse embryos from those with compromised developmental competence without requiring a separate mechanical characterization process. Centered upon force-controlled microrobotic cell manipulation, this paper also presents nanonewton force-controlled micrograsping of interstitial cells using a microelectromechanical systems (MEMS)-based microgripper with integrated two-axis force feedback. On-chip force sensors are used for detecting contact between the microgripper and cells to be manipulated (resolution: 38.5 nN at 15Hz) and sensing gripping forces (resolution: 19.9 nN at 15Hz) during force-controlled grasping. The experimental results demonstrate that the microgripper and the control system are capable of rapid contact detection and reliable force-controlled micrograsping to accommodate variations in size and stiffness of cells with a high degree of reproducibility.

Modeling and Experimental Characterization of an Untethered Magnetic Micro-Robot

Pawashe, C., Floyd, S., Sitti, M. — Thu, 30 Jul 2009 03:56:01 PDT

Here we present the control, performance and modeling of an untethered electromagnetically actuated magnetic micro-robot. The microrobot, which is composed of neodymium—iron—boron with dimensions 250 µm 1 130 µm 1 10 µm , is actuated by a system of six macro-scale electromagnets. Periodically varying magnetic fields are used to impose magnetic torques, which induce stick—slip motion in the micro-robot. These magnetic forces and torques are incorporated into a comprehensive dynamic model, which captures the behavior of the micro-robot. By pivoting the micro-robot about an edge, non-planar obstacles with characteristic sizes comparable to the robot length can be surmounted. Actuation is demonstrated on several substrates with different surface properties, in a fluid environment, and in a vacuum. Observed micro-robot translation speeds can exceed 10 mm s^-1.