Recent developments in virtual reality and robotic technologies have allowed investigating the behavioural and brain mechanisms that grounds self-consciousness in the multi-sensory (e.g. vision and touch) and sensorimotor processing of bodily signals. Yet, previous technological solutions to apply tactile stimuli for body illusion induction limit participants movements, do not allow for stimulations in dynamic environments (e.g., the subject walking), and can hardly be integrated into real-life settings and complex, interactive, virtual reality environments. Here, we present the development and first validation of a new semi-wearable haptic system, based on vibration technology, to induce a range of bodily illusions that are of relevance for research in psychiatry. This is a first step towards the development of wearable haptic systems able to administer touch and induce specific bodily illusions under dynamic conditions and in real-life settings.

Sensory function is essential for functional post-stroke recovery and control of basic hand movements like grasping. Despite this fact, therapy focuses strongly on motor aspects of rehabilitation, requiring active participation and thus excluding stroke patients with severe paresis. The aim of our novel therapeutic approach combining virtual reality, based on clinically proven mirror therapy, and tendon vibration of hand and wrist muscles is to induce neuroplastic changes leading to improved hand function. This paper presents the further development and evaluation of a robotic device, which can apply vibrations at precise locations on the finger flexor tendons to create illusions of extension movements and visualize the movements with a virtual hand. A preliminary study including 16 healthy subjects investigated the influence of the virtual reality on the perception of proprioceptive illusory movements. The experimental results provided evidence that the addition of the virtual reality enhanced the perception of the illusory movement generated by tendon vibration, by inducing movements with significantly higher extension (+4.5%, p <; 0.05). Furthermore, the virtual reality allowed a better controlled temporal elicitation of the illusion. These findings indicate the potential of this novel strategy for a more effective therapy, especially for severely impaired patients.

In the field of surgical robotics, it is difficult to find objective assessment techniques for evaluating telepresence. In this study we try to merge the concepts from cognitive neuroscience more specifically from the field of tool incorporation (embodiment) into surgical robotics in order to assess quantitatively the affect of delayed feedback on the telepresence. Hence, this study investigates the relationship between tool-incorporation (in this case the haptic device of the surgical console) and the decrease of performance due to time delays. A cognitive neuroscience method called the crossmodal congruency effect (CCE) is used to measure the level of tool incorporation and thus indirectly the level of telepresence while performing a simulated surgical-like task. The result of this study shows that user telepresence level and performance measures decrease with increasing delayed visual and haptic feedback.

In this paper we present a combination of neuroscience experiments with the use of a parallel armrest robot to study the effects of temporal delays and spatial biases on the movement perception. A dedicated armrest to guide and manipulate the arm has been developed for these experiments. It is a three-degree-of-freedom Delta structure. In combination with a virtual reality application, the movement perception has been evaluated. The results of this study demonstrate that experimental conditions such as spatial deviations and temporal delays impair the correct self-attribution of the movements done with the motorized Delta armrest. This result shows that the motorized Delta armrest can be successfully used to study the effect of movement perception, opening up the way to new studies about the movement perception using robotic system and virtual reality.

This paper describes the system development of an admittance-controlled 2-dof haptic device using electrostatic motors. The unique point of the device is that all components including the motors and sensors are fabricated using non ferromagnetic materials to realize operation in a strong magnetic field. The device consists of an operation handle, two electrostatic motor units and two optical force sensors, and is an improved version of our previous development. The new device has stiffer platforms, improved force sensors, and newly fabricated driving electronics. The employed electrostatic motor is one of the strongest electrostatic actuators and can generate thrust force of several newtons. To operate a motor unit, two three-phase signals are required and they have to be amplified to over 1 kV. In our previous development, the signals were amplified by six large commercial amplifiers, which was not practical enough considering the portability of the system. This work developed an original driving electronics for the motor using Field Programmable Gate Array (FPGA) and step-up transformers to reduce the system size. The device was implemented on one of the major haptic toolkits, CHAI 3D. To be able to run sample impedance-type programs without any modifications, we implemented our device to behave like impedance-type on CHAI 3D.

The main goal of virtual reality based surgery simulators with haptic feedback is to provide an alternative to traditional training methods on animals, cadavers or real patients. Haptic feedback is a key feature for every surgery simulator for the training of hand-eye coordination. To address the need for higher fidelity and complexity in an endoscopic simulator, we have designed a new haptic interface, instrumented a clinical endoscope and integrated it with a software simulation for colonoscopy. The proposed haptic interface provides high translational force and rotational torque with combined electrical motors and passive brakes. This paper presents the evaluation of the haptic interface. Experimental analyzes are performed for characterization and performance evaluation. A model-based feed-forward control is implemented and the results show that the control successfully compensates for the device dynamics and nonlinearities such as Coulomb and viscous friction.

This paper introduces a novel approach to the manipulation of body-parts ownership, using the tactile rubber hand illusion (RHI) paradigm. In the conventional studies on the RHI, participant's invisible hand and the visible rubber hand are manually tapped or stroked by an experimenter. Differently, in our approach, a bilateral master-slave system is applied to provide tactile stimulations in a novel interactive manner—active self-touch. Here, we present a 3-DOF master-slave system based on human self-touch characteristics and a validation experiment using an arranged version of the conventional RHI paradigm. In this new version, participants can contact with the rubber hand by manipulating the master device with their right hand and actively touch their own left hand through the slave device. The results demonstrate that the master-slave system can be successfully used to manipulate body-parts ownership, opening up the way to new studies concerning self-touch and body representation.

Simultaneous localization and mapping (SLAM) is a prominent feature for autonomous robots operating in undefined environments. Applications areas such as consumer robotics appliances would clearly benefit from low-cost and compact SLAM implementations. The SLAM research community has developed several robust algorithms in the course of the last two decades. However, until now most SLAM demonstrators have relied on expensive sensors or large processing power, limiting their realms of application. Several works have explored optimizations into various directions; however none has presented a global optimization from the mechatronic to the algorithmic level. In this article, we present a solution to the SLAM problem based on the co-design of a slim rotating distance scanner, a lightweight SLAM software, and an optimization methodology. The scanner consists of a set of infrared distance sensors mounted on a contactless rotating platform. The SLAM algorithm is an adaptation of FastSLAM 2.0 that runs in real time on a miniature robot. The optimization methodology finds the parameters of the SLAM algorithm using an evolution strategy. This work demonstrates that an inexpensive sensor coupled with a low-speed processor are good enough to perform SLAM in simple environments in real time.

Collective and swarm robotics explores scenarios involving many robots running at the same time. A good platform for collective-robotic experiments should provide certain features among others: it should have a large battery life, it should be able to perceive its peers, and it should be capable of interacting with them. This paper presents the marXbot, a miniature mobile robot that addresses these needs. The marXbot uses differential-drive treels to provide rough-terrain mobility. The marXbot allows continuous experiments thanks to a sophisticated energy management and a hotswap battery exchange mechanism. The marXbot can self-assemble with peers using a compliant attachment mechanism. The marXbot provides high-quality vision, using two cameras directly interfaced with an ARM processor. Compared to the related work, the marXbot has better energy management, vision, and interaction capabilities. By allowing complex tasks in large environments for long durations, the marXbot opens new perspectives for the collective-robotic research.

To design, to study, and to control mixed animals-robots societies is a challenging field of scientific exploration that can bring new frameworks to study individual and collective behaviors in animal and mixed robot-animal societies. In the Chicken Robot project we aim at developing a mobile robot, able to collaborate with a group of chicks and to control certain group behaviors. The first research step is to build formal models of relevant animal behaviors by performing ethological experiments. Hence, one of the principal tasks is to design a setup equipped with appropriate monitoring tools. In this paper, we present a toolset for running chick-robot experiments and analyzing results. It includes an autonomous PoulBot robot and an experimental setup, able to autonomously record experimental video and audio data, to detect displacements of chicks and robots, to detect their calling activity and to provide robots with these data. We also present a visual data analysis system to extract behavioral features of individual chicks using the variational Bayesian Gaussian mixture model classification with a particle filters based prediction of future positions of chicks. We show how these tools are currently used to carry out chick-robot experiments, to collect behavioral data and to extract animal behavioral features that allow us to build behavioral models bound to be implemented in the robot.

Haptic interfaces compatible with functional magnetic resonance imaging (fMRI) are finding increasing interest as a tool to explore the neural correlates of human motor control and related dysfunctions. To achieve safety and MR compatibility, such devices have mainly relied on unconventional actuation methods suffering from limited bandwidth and non-linearities. This has resulted in complex control and restricted their use in applications involving fine and dynamic interaction with the hand and fingers. To address these limitations, we propose a concept for a shielded high-performance actuation system to be located inside the MR room, evaluate the effectiveness of the shielding and perform detailed MR compatibility tests. A conventional electromagnetic actuator is located within a steel shield to prevent mutual disturbance with magnetic fields of the scanner, which, together with power and control hardware, is placed within a Faraday cage with only a fiber-optical USB link to the control room. Detailed compatibility tests show that disturbing dynamic electromagnetic fields generated by the actuation system are well below the detectable threshold of the scanner, and actuator performance is not degraded by the MR environment. In combination with a light and stiff cable or rod transmission, the presented actuator technology, providing high transparency and force bandwidth, paves the way for fMRI-based neuroscience studies, e.g., to investigate the fine motor control of hand and fingers.

During traditional open procedures, surgeons directly palpate tissues before dissecting them. In this way, they can avoid the accidental damage of hidden arteries that can lead to fatal hemorrhage. New Minimally Invasive Surgical (MIS) techniques progressively decreased the instrument access into the patient's body to reduce scars and side effects. The major drawback of these procedures is that they do not permit surgeons to perform direct tactile exploration of internal tissues. Surgeons have to rely on preoperative images and anatomical knowledge to avoid artery locations. However, the exact artery position changes depending on the patient and his posture. Hence, it is of primary importance to assist surgeons with technology that can guide them during the surgical procedure. This paper presents the design and evaluation of a tactile display that reproduces pulse-like feedback on the surgeon's fingertip. The display bandwidth and performance of the ad-hoc control unit were assessed with encouraging results. In addition, the outcome of two psychophysical studies carried out in this work validate the usability of the display in terms of user perception.

This paper describes the development of a 2-DOF electrostatic haptic joystick designed for neuroscience studies in an MRI/fMRI. The joystick is fabricated using non-magnetic materials and actuated by two high-power electrostatic motor units which produce various force fields in the horizontal plane. The electrostatic motor is a synchronous drive and thus the positioning of the joystick is achieved in an open-loop control. As for force sensing, a 2-DOF force sensor is developed using non-magnetic materials and optical fibers so as to measure interaction force with a user; hence, the haptic rendering is based on the admittance control scheme that respects the rule of force-in and position-out. The operation of both the actuators and force sensor respects non-magnetic principles. Thus, the haptic joystick into which these components are integrated is expected to have high MR compatibility, although the evaluation of the MR compatibility is beyond the scope of this paper. In this paper, the device performance is evaluated in the normal environment, which verifies the operation of the unique electrostatic haptic device.

This paper describes the effect of Muller-Lyer illusion on a reaching movement just after the visual and haptic/kinesthetic cues are simultaneously presented. First, a standard experiment on this visual illusion is conducted by means of the most typical way so as to make sure that participants can experience this illusion; the result shows that all the subjects are deceived by the illusion figure as in many previous results. As the next step, the subjects are asked to physically trace one of three lines-normal line and lines with feathers of an arrow-with the same length displayed on an LCD. After a few traces, the line suddenly vanishes, and then the subjects retrace the invisible line based on only their memory and somatic sensations. During this task, we measure the trajectory of fingertip from a start to the goal using a motion capture system. The result indicates that the Muller-Lyer illusion dominantly affects the reaching task although the haptic/kinesthetic cue was also given just before the task. Thus, this result implies that the visual illusion affects the motion planning, which partly supports a planning-motion model.

This study attempts to make a compact humanoid robot acquire a giant-swing motion without any robotic models by using reinforcement learning; only the interaction with environment is available. Generally, it is widely said that this type of learning method is not appropriated to obtain dynamic motions because Markov property is not necessarily guaranteed during the dynamic task. However, in this study, we try to avoid this problem by embedding the dynamic information in the robotic state space; the applicability of the proposed method is considered using both the real robot and dynamic simulator. This paper, in particular, discusses how the robot with 5-DOF, in which the Q-Learning algorithm is implemented, acquires a giant-swing motion. Further, we describe the reward effects on the Q-Learning. Finally, this paper demonstrates that the application of the Q-Learning enable the robot to perform a very attractive giant-swing motion.

Interventional radiologists manipulate guidewires and catheters and steer stents through the patient’s vascular system under X-ray imaging for treatment of vascular diseases. The complexity of these procedures makes trainingmandatory in order to master hand-eye coordination, instrument manipulation and procedure protocols for each radiologist. In this paper we present a simulator for interventional radiology, which deploys a model of guidewire/catheter based on the Cosserat theory applied to one-dimensional structures. This model starts from the energetic formulation of the filament considering the Hook laws of continuum mechanics. The Lagrange formulations are used to describe the model deformation. This model takes (self-) collisions into account and it is revealed to be very efficient for interactive applications. The simulation environment allows to carry out the most common procedures: guidewire and catheter navigation, contrast dye injection to visualize the vessels, balloon angioplasty and stent placement. Moreover, heartbeat as well as breathing are also simulated visually.

The purpose of evaluation procedures is to achieve both qualitative and quantitative statements on haptic rendering realism and performance. Since a haptic interface provides an interaction between a user and a virtual environment, fidelity of a haptic interface directly affects the performance. To our knowledge, a standard, generic and reusable validation method which comprehensively addresses all the attributes of haptic feedback has not been realized yet. Despite the large number of human factor studies, only few of them have been proposed as well for haptic interface performance measurements. For this reason, we review validation procedures for haptic rendering and propose an evaluation method based on testbeds to obtain a systematic haptic interface assessment. We integrated the approaches of human factor studies into the testbeds to obtain a simple and yet complete measure of human-machine interaction performance. The testbeds were tested on a haptic interface, the IHP of Xitact SA, and performance results are presented. In the testbeds, performance metrics for generic haptic interaction tasks are expressed in terms of information transfer (bits) and sensory thresholds which are indeed device specific benchmark metrics. Thus, the suitability of a haptic interface for a defined task can be verified, device comparisons become possible and the obtained information can be used to identify possible improvements.

Various approaches have been proposed to tackle the rough-terrain robot motion planning task to date. Depending on the application at hand, a different algorithm is selected to generate a motion plan. Nevertheless, they all have the fundamental characteristics of the rough terrain in common. Based on this notion, a unifying formalism is presented which can be used to represent application-dependent properties of the terrain to the motion planner. The approach is based on the characteristic difficulty associated with each configuration of the robot on the rough terrain. This concept is formalised resulting in the definition of "obstacleness" as generic degree of presence of an obstacle. A novel rough-terrain motion planning algorithm is presented which makes use of the obstacleness measure. The approach is based on a bi-directional rapidly exploring random tree (RRT) algorithm. The exploration of configuration space by the RRTs is biased towards regions of low navigational difficulty to compute trajectories in easily traversable terrain. Preliminary test results obtained with a fictional planetary rover in a rigid body dynamics simulation are also presented

This paper describes a two-degrees-of-freedom haptic interface to investigate the brain mechanisms of human motor control, which is capable of safely and gently interacting with human arm motion during functional magnetic resonance imaging (fMRI). A hydrostatic transmission separates the interface into a master and an MR compatible slave system, allowing the placement of all interfering components outside the electromagnetic shield of the MR room. The transmission mirrors force and motion of the master actuators on the slave system placed close to the MR scanner. The parallel architecture takes advantage of the linear MR compatible actuators and allows human subjects to perform reaching movements comfortably in the small workspace limited by the dimensions of the MR scanner and the biomechanics of the arm. The kinematic structure of the slave interface was optimized with respect to the available space and types of movements to be investigated. Materials were chosen based on their MR compatibility, their stiffness and weight. The interaction force with the subject is measured over two optical force sensors, located close to the output of the interface. Two shielded optoelectronic encoders measure the extension of the slave hydraulic pistons. Detailed tests demonstrated the fMRI compatibility even during movement of the interface

Functional brain exploration methodologies such as functional magnetic resonance imaging (fMRI) are critical tools to study perceptual and cognitive processes. In order to develop complex and well-controlled fMRI paradigms, researchers are interested in using active interfaces with electrically powered actuators and sensors. Due to the particularity of the MR environment, safety and compatibility criteria have to be strictly followed to avoid risks to the subject under test, the operators or the environment, as well as to prevent artifacts in the images. This paper describes the design of an fMRI compatible mechatronic interface based on MR compatibility tests of materials and actuators. In particular, a statistical test is introduced to evaluate the presence of artifacts in the image sequences that could negatively affect the fMRI studies. The device with two degrees of freedom, allowing one translation with position-feedback along a horizontal axis and one rotation about a vertical axis linked to the translation, was realized to investigate the brain mechanisms of dynamic tactile perception tasks. It can be used to move and orient various objects below the finger for controlled tactile stimulation. The MR compatibility of the complete interface is shown using the statistical test as well as a functional study with a human subject

Using haptic interfaces in combination with functional magnetic resonance imaging (fMRI) could lead to important insights into the brain mechanisms of human motor control and related dysfunctions. However, in addition to the usual requirements for haptic interfaces (e.g. smooth force control, back-drivability, low friction and inertia) these devices must also be MR safe and MR compatible. Previous MR-compatible actuation methods for force-feedback present drawbacks with respect to conventional haptic interfaces. Here, we present a novel MR-compatible actuator designed especially for impedance control and to meet the requirements for haptic interfaces. It consists of an ultrasonic motor controlled in speed combined with an electrorheological fluid brake which modulates the output torque over a differential gear. The entire system is integrated into a compact housing with an encoder at the output

The strong impairment of motor functions in stroke survivors affects daily activities such as eating, manipulating objects or writing. Our goal is to induce long lasting improvements in such tasks by having patients perform systematic exercises using haptic interfaces. This paper describes a novel two-degrees-of-freedom interface which we have developed to help stroke patients gradually recover the ability to open and close the hand and manipulate knobs. Different solutions are studied and a design consisting of two parallelogram structures interacting with the fingers is proposed. The mechanical design offers the possibility to adapt the interface to various hand sizes and finger orientations, and to right or left-handed subjects. Design kinematics as well as actuation and system control are described. Several knobs are proposed to interact with patients, especially a cone mechanism to train a complete opening movement from a strongly contracted and closed hand to a large opened position. The interaction force with the subject is measured over four force sensors located close to the output of the interface. A preliminary study has been performed to evaluate the performances of the haptic interface

A fundamental property of rough-terrain motion planning is that each configuration of the robot on the terrain can be assigned a characteristic navigational difficulty based on the terrain topography and physical properties of the underground. This measure is computed in an application-dependent manner based on the properties of the robot and terrain model employed. In this work we propose a motion planner based on rapidly exploring random trees (RRTs) which takes into consideration the characteristics of the underground. In the suggested solution, the randomised expansion of the RRTs is biased towards regions of low navigational difficulty. The motion planner generates trajectories which follow areas of easy navigation and only deviates to harder regions where inevitable. In particular, the maximal difficulty on the path is approximately minimised. For single-query motion planning tasks, bidirectional RRTs have proven to be effective in rapidly computing a path between the initial and goal configurations. To deal with complex distributions of the terrain characteristics, this concept has been extended. Rooted at randomly chosen configurations, a number of additional RRTs is grown. While the algorithm discussed is intended for rough-terrain motion planning and demonstrated in this context, it can easily be adapted to other domains where a characteristic measure for the desirability of attaining individual configurations can be defined

Low trauma, reduced costs, fast recovery are few factors why minimally invasive surgery (MIS) is taking over classical surgical methods. Interventional Radiology (IR) is a MIS technique where thin tubular instruments are steered through the patient’s vascular system under the X-ray imaging. These procedures demand highly trained and experienced specialists. A computer-based haptic interface is proposed as a quality training environment. The system is composed of a virtual reality (VR) environment and force feedback units for the surgical instruments. This paper describes the 4 degrees of freedom (DOFs) haptic interface that has been developed for this purpose.

This paper reports a new MRI (Magnetic Resonance Imaging) compatible actuator that can operate near an MRI without degrading its imaging quality. A high-power electrostatic motor is introduced and its MR-compatibility is examined, both experimentally and theoretically. The proposed motor was fabricated with only paramagnetic materials, and its MR-compatibility was evaluated by measuring the output performance of the motor and the signal-to-noise ratios of the MRI images. The experimental results showed that motor’s thrust force while positioned within the MRI is almost the same as that in normal operation. The signal-to-noise investigation indicated that the motor did not affect the MRI images when it was operated over 60 cm away from the MRI’s RF coil. The theoretical calculations showed that the magnetic field generated by the motor is relatively small and the effect of the MRI’s magnetic fields on the motor is negligible, suggesting that the motor is MR-compatible.

We analyze the dynamics of an MR-compatible hydrostatic transmission designed to transfer power over distances of up to 10 m. In this system, a master actuates a passive slave connected by two hydrostatic lines in a cyclic arrangement. We derive a nonlinear model of this system and use it to analyze the system's behavior and the design parameters. The transmission acts as a low-pass filter with cut-off frequency decreasing for longer hoses. Even for a length of 10 m the cut-off frequency is about 20 Hz, resulting in a bandwidth that suffices for haptic interfaces interacting with human motion as well as for medical robots. A pragmatic control delivered free movements, position and velocity dependent force fields and trajectory control suitable to investigate how the brain controls movements in interaction with the environment. For short hose lengths (/spl les/1 m) the dynamics can be well approximated by a linear model, and the system is dynamic and stiff. The hydraulic transmission can produce force and motion in any orientation, enabling a more flexible design than other types of transmissions such as by cables.

A cluster of small cooperative robots capable of executing measurement and manipulation tasks is being developed within the scope of a European project. The robots are autonomous and have an overall dimension in the order of 1 cm/sup 3/. In this paper we present the concept of the robots, along with possible locomotion modules based on piezoelectric stick-slip actuators. Tools can be added to the robot for different measurements and manipulations. The integration of an AFM probe on the robot has been realized as a high resolution sensor for localization purposes and for measurements. First experimental results are shown.

Force/torque sensors compatible with magnetic resonance imaging (MRI) are required to develop haptic interfaces for neuroscientific investigations and robotic tools for interventional MRI. In this paper, we analyze the mechanical structure of classical and MRI compatible sensors from literature and demonstrate the critical role of the mechanical design on the sensing performance. A simple and efficient torque sensor based on light intensity measurement over optical fibers is introduced, which allows to place the electronic components outside the scanner room. By using a self-guiding flexible structure and optimal mirror placement, the sensitivity to transverse torque is reduced to 0.03% of the desired output torque.

In minimal-invasive surgery surgeons are generally confronted with complex scenario and sometimes they have to overcome unexpected pathologies or life-threatening injuries. Therefore there is a demand for realistic training without risk to the patient. Since a decade ago there have been research activities on virtual reality surgery simulators with haptic feedback with the goal to provide an alternative to traditional training methods on animals or cadavers. Haptic feedback is a key feature for every surgery simulator for the training of hand-eye coordination. In this paper a 4-dof haptic device is presented for hysteroscopy, the examination and treatment of the uterine cavity through the vagina. Specifications are presented, and kinematics as well as force transmission are analyzed. The realized prototype, result of a systematic design process, is based on a 2-dof spherical manipulator with low inertia and a 2-dof serial extension, which allows the use of slightly adapted original instruments. With difference to common surgery simulators tool insertion and complete removal can be performed. The performance of the prototype is shortly discussed.

Magnetically compatible robots are required to develop haptic interfaces for neuroscience studies and MRI guided robots for minimally invasive interventions. This paper introduces an MR compatible master slave concept using a hydraulic transmission, and presents an operational robot able to work within an MRI/fMRI scanner and acquire images continuously during motion. It describes a magnetically inert actuator using a direct drive to power the hydraulic circuitry and a modular set of position and force/torque sensors that we have developed. These were integrated into a haptic interface prototype with on rotary degree of freedom, which can be used in conjuction with an fMRI. The MR compatibility was confirmed experimentally, and the performances show a manipulation accuracy of a few micrometers over a range of several centimeters, and forces up to several thousand Newton.

Illustrates with various practical examples an activity at the intersection of MEMS, system control, robotics and ultraprecision design. The resulting new application domains include microrobotics, microfactories and nanotechnologies.

This paper presents several approaches for piezoactuators in motion control over a large dynamic range (cm to nm). The devices include monolithic two-degree-of-freedom actuators with mechanical amplification, stick-slip actuators and 6-DOF designs of micro-positioners. Closed loop feedback is of course necessary for good performance. All the proposed solutions have been realized and experimental results are discussed, application examples in scanning probe microscopy and biology are shortly presented.