Active force sensors are key instruments to get around the tradeoff between the sensitivity and the measurement range of conventional passive force sensors. Thanks to their quasi-infinite stiffness in closed loop, active sensors can be applied for force measurements on samples with a wide range of stiffness without interference with the mechanical parameters of the sensor. MEMS (Micro-Electro Mechanical Systems) active force sensors have been wildly developed in the literature but they are ill adapted for force measurements at the Newton level needed in meso-scale robotics. In this article, a novel structure for a meso-scale active force sensor is proposed for the measurement of forces from the milli-newton to the newton.This novel meso-scale sensor is based on a nil-stiffness guidance and an electromagnetic actuation. This paper deals with its design, identification, calibration and closed loop control. The sensor exhibits nil-stiffness characteristic in open loop and an almost infinite stiffness in closed loop. This allows measuring forces with a large range of gradients. First experiments shows the ability of this new sensor architecture to measure low frequency forces up to 0.8N with a precision of 0.03 N and a closed loop -20 dB cutoff frequency of 73.9Hz.

Micromanipulation is challenging due to the specific physical effects governing the microworld. Interactive approaches using only visual feedback are limited to the 2D image of the microscope, and have forcibly lower bandwidth. Recently, haptic feedback teleoperation systems have been developed to try to overcome those difficulties. This paper explores the case of an optical tweezers platform coupled to an haptic device providing transparent force feedback. The impact of haptic feedback regarding user dexterity on tactile exploration tasks is studied using 3 μm microbeads and a test bench with micro sized shapes. The results reveal a consistent improvement in both users' trajectory tracking and their control of the contact forces. This also validates the experimental setup which performed reliably on 140 different trials of the evaluation.

We present CoVR, a novel robotic interface providing strong kinesthetic feedback (100 N) in a room-scale VR arena. It consists of a physical column mounted on a 2D Cartesian ceiling robot (XY displacements) with the capacity of (1) resisting to body-scaled users' actions such as pushing or leaning; (2) acting on the users by pulling or transporting them as well as (3) carrying multiple potentially heavy objects (up to 80kg) that users can freely manipulate or make interact with each other. We describe its implementation and define a trajectory generation algorithm based on a novel user intention model to support non-deterministic scenarios, where the users are free to interact with any virtual object of interest with no regards to the scenarios' progress. A technical evaluation and a user study demonstrate the feasibility and usability of CoVR, as well as the relevance of whole-body interactions involving strong forces, such as being pulled through or transported.

Micro-assembly is a challenging issue for automation due to particularities of micro-world physics and limitations on sensors. Consequently, most applications are human-operated often with basic joystick-like interfaces. Beside being nonintuitive, these solutions do not provide their users with a meaningful insight into the microworld. This paper proposes a novel intuitive remote handling interface, using a classical hand-held assembly tool as a paradigm. The master device is a portable instrumented tweezers with one active degree of freedom. Its spatial motion, tracked by optical means, controls the slave kinematics while its pinch commands the slave robot's microgripper and provides haptic feedback. Different coupling strategies using position or speed variables are demonstrated.

Optical Tweezers are considered one of the most suitable techniques for biological tasks, however the lack of automation make this technology less accessible. We present here a new 3D force sensing method with high bandwidth (up to 10Khz) which can allow implementing complex robotic approaches. Proposed technique uses high speed image tracking with nano-metric resolution in 3 directions. Its capabilities are demonstrated in a teleoperated 3D manipulation scenario with a haptic user interface, where naive users performed direct in vitro haptic exploration of isolated Red Blood Cells inside a Petri dish.

Visual tracking and estimation of the 3D posture of a micro/nano-object is a key issue in the development of automated manipulation tasks using the visual feedback. The 3D posture of the micro-object is estimated based on a template matching algorithm. Nevertheless, a key challenge for visual tracking in a scanning electron microscope (SEM) is the difficulty to observe the motion along the depth direction. In this paper, we propose a template-based hybrid visual tracking scheme that uses luminance information to estimate the object displacement on x-y plane and uses defocus information to estimate object depth. This approach is experimentally validated on 4-DoF motion of a sample in a SEM.

Direct photometric visual servoing uses only the pure image information as a visual feature, instead of using classic geometric features such as points or lines. It was demonstrated efficiently in 6 degrees of freedom (DoF) positioning. However, in micro-scale, using only image intensity as a visual feature performs unsatisfactorily in cases where the photometric variation is low, such as motions along vision sensor's focal axis under a high magnification. In order to improve the performance and accuracy in those cases, an approach using hybrid visual features is proposed in this paper. Image gradient is employed as a visual feature on z axis while image intensity is used on the other 5 DoFs to control the motion. A 6-DoF micro-positioning task is accomplished by this hybrid visual servoing scheme. The experimental results obtained on a parallel positioning micro-stage under a digital microscope show the robustness and efficiency of the proposed method.

Microscale teleoperation with haptic feedback requires scaling gains in the order of 104−107. These high gains impose a trade-off between stability and transparency. Due to the conservative approach used in most designs, transparency is reduced since damping is added to the system to guarantee stability. Starting from the fact that series, negative feedback and parallel connection of passive systems is a passive system, a new approach is addressed in this work. We propose here a complete teleoperation chain designed from the ground up for full transparency and stability, including a novel self-sensing probe and a high fidelity force-feedback haptic interface. By guaranteeing the passivity of each device and assuming that the human operator and the environment are passive systems, a homothetic direct coupling can be used without jeopardizing the stability and provides best transparency. The system is experimentally demonstrated in the complex case of a probe interacting with a water droplet under human control, while accurately transcribing the interaction back to operator.

This paper reports the remote handling of microscale objects, between two sites approximately 630 km distant. To manipulate objects less than 10 ¿m, specific equipments such as AFM (Atomic Force Microscope) cantilevers integrated into a SEM (Scanning Electron Microscope) are generally required. Enabling remote access to such a system would benefit any micro/nanoresearcher. However, vision feedback and sensor data of a micromanipulation system are generally limited, hence the implementation of a teleoperation scenario is not straightforward. Specific tools are proposed here for an intuitive manipulation in a wide range of applications. To ensure ease of manipulation, both a 3D virtual representation of the scene and haptic feedback are provided. Force sensor feedback is limited since only two measures are available. In order to extend this information, vision algorithms are developed to estimate the respective positions of the tool and objects, which are then used to calculate the haptic feedback. The stability of the overall scheme is very sensitive to time delays. This requirement is taken into account in vision algorithms and the communication module which transfers the data between the two remote sites. In addition, the proposed robotic control architecture is modular so that the platform can be used for a wide range of applications. First results are obtained on a teleoperation between Paris, France, and Oldenburg, Germany.

In this paper, a fully teleoperated 3D micro assembly task with haptic feedback is presented. Microspheres (diameter: 4-6μm) are manipulated by pick-and-place. The setup is composed of a dual-tip gripper controlled through a haptic interface. To grasp the spheres, the tips must be correctly positioned with respect to the objects. The approach proposed to align the gripper is based on a user-driven exploration of the to-be-manipulated object. During this step, the haptic feedback is based on amplitude measurements from cantilevers in dynamic mode. Hence, the operator perceives the contact while freely exploring the manipulation area. A virtual guide is generated to pull the user to the optimum contact point, allowing correct positioning of dual tips. For the pick-and-place operation, the haptic feedback provides the user with information about the microscale interactions occurring during the operation. As experimental validation, a two-layer pyramid composed of four nylon microspheres is built in ambient conditions.

This paper deals with the problem of bilateral haptic control in nanorobotics. At this scale, a human operator cannot interact directly with objects. He needs special tools manipulated through robotic systems. Therefore, force feedback devices are the only solution to provide him a sense of touch. However, the quality of the rendering strongly influences his ability to perform a given task. Stability is the main requirement that the system must fulfil to be usable. As the choice of the controller and its tuning are critical issues, a general method to tune the parameters of two haptic controllers is presented. A theoretical study is carried out and the methodology is validated with an experiment composed of several phases with high dynamic phenomena. Intrinsic limitations of the two controllers are also pointed out.

Applications of the conventional atomic force microscope (AFM) succeeded in manipulating nanoparticles, nanowires or nanotubes by widely used pushing or pulling operations on a single plane. However, pick-and-place nanomanipulation is still a challenge in the air. In this paper, a modified AFM, called three-dimensional (3D) manipulation force microscope (3DMFM) was developed, aiming to achieve the pick-and-place in the air. This system mainly consists of two microcantilevers and each is quipped with a nanopositioning device and an optical lever, constructing a nanotweezer with capabilities of picking and releasing nanoobjects with force sensing. Before the 3D manipulation, one of the cantilevers is employed to position nanoobjects and locate the tip of another cantilever by image scanning, then these two cantilevers fit together as a nanotweezer to grasp, transport and place the nanoobjects with real-time force sensing. In pick-and-place experiments, silicon nanowires (SiNMs) with different diameters were manipulated and 3D nanowire crosses were achieved. 3D nanomanipulation and nanoassembly in the air could become feasible through the newly developed 3DMFM.

Both the extent and accuracy of force application in atomic force microscope (AFM) nanomanipulation are significantly limited by the nonlinearity of the commonly used optical lever with a nonlinear position-sensitive detector (PSD). In order to compensate the nonlinearity of the optical lever, a nonlinear calibration method is presented. This method applies the nonlinear curve fit to a full-range position-voltage response of the photodiode, obtaining a continuous function of its voltage-related sensitivity. Thus, Interaction forces can be defined as integrals of this sensitivity function between any two responses of photodiode voltage outputs, instead of rough transformation with a single conversion factor. The lateral position-voltage response of the photodiode, a universally acknowledged puzzle, was directly characterized by an accurately calibrated force sensor composed of a tippless piezoresistive force sensor, regardless of any knowledge of the cantilevers and laser measuring system. Experiments using a rectangular cantilever (normal force constant 0.24 N/m) demonstrated that the proposed nonlinear calibration method restrained the sensitivity error of normal position-voltage responses to 3.6% and extended the force application range.

This paper presents a remote handling force feedback coupling for micromanipulation systems. In the literature, the most generally used coupling mode is 'force position'. This kind of control scheme is not portable and instability is an often occurring problem. The coupling scheme proposed in this paper is based on the passivity considerations on the teleoperated systems. It is independent of the used haptic interface and the manipulator and unconditionally stable regarding scaling ratios. It is experimented using the LRP's (Laboratoire de Robotique de Paris) micromanipulator, which is based on AFM architecture and uses the adhesion forces for pickup and release tasks. A comparison between the force position coupling and proposed coupling is presented. Experimental results show the good performances in terms of stability.

This paper presents our work in developing an autonomous micromanipulation system. The originality of our system is that it takes advantage of adhesion to grip micro-objects by using a single fingered gripper. This is in fact a tipless cantilever previously designed for atomic force microscopy applications. We describe vision techniques employed to process images provided by an optical microscope, allowing to position accurately the end-effector for a gripping task. A theoretical study of the direct force measurement device and an experimental validation show how we can improve the measurement of impact and contact forces. Then we explain the strategy used to bring the gripper into contact with the object, based on force control and kinematic redundancy. Finally, a simplified model of the release task is proposed in order to determine conditions that allow to roll the object, and then to place it with precision.

A micro-manipulation method based on adhesion forces and dynamic effects has been proposed in our previous papers. A prototype manipulator, called [mu]MAD, has been constructed and successfully experimented. This paper describes the advanced capabilities of [mu]MAD, especially two new interesting applications: sorting of micro-objects and mechanical characterizations.

Describes a dynamical strategy for releasing micro objects picked-up by means of adhesion forces. While sticking effects are used in order to capture an object by adequately choosing a high surface energy constitutive material for the end-effector, these same effects handicap considerably the release. We propose to take advantage of the inertial effects of both the end-effector and the manipulated object to overbalance adhesion forces and to achieve the release. Simulations show that for this purpose, accelerations as high as 10/sup 5/ m/s/sup 2/ are needed. Successful manipulation of a 40 /spl mu/m radius glass sphere is experimented.

In this paper, we propose an original design for a manipulation system of rigid micro-objects by adhesion (50 /spl mu/m/spl sim/200 /spl mu/m) in open air. The design is based on a precise analysis of the mechanical conditions for manipulation by adhesion. Simulations using a dynamic model of a canonical manipulation (capture and release of micro-objects) have shown that it exists an "end-effector initial acceleration" windows for which manipulations are possible. The end-effector we have developed integrates a highly sensitive contact sensor and two piezo-accelerators (/spl sim/10/sup 6/ m.s/sup -2/). Successful manipulations by adhesion of silicon chips with a gold coated piezoresistive silicon cantilever have been carried out and are presented as conclusion of this paper.