A low cost coarse/fine piezoelectrically actuated microgripper with force measurement adapted to EUPASS control structure.

Over the last few years the demand for miniature objects and devices has continuously increased. So the need for MEMS (Micro Electro Mechanical Systems) and MOEMS (Micro Opto Electro Mechanical Systems) in various fields has become more and more important. New micromanipulation technologies must be developed that take into account the specificities of MEMS and MOEMS. For performing manipulation tasks, gripping is one of the fundamental functions. In this paper, the design and the control of a microgripper dedicated to very high precision tasks are presented. The LAB (Laboratoire d'Automatique de Besançon) has developped a microgripper based on the piezoelectric properties (1). This gripper is equipped with a precise sensor for force measurement. Force measurement is very important in order to avoid damaging or destroying the fragile object. Various approaches we used to model and calibrate the microgripper. The control of the gripper is done using the EUPASS Control Structure (6)

Towards clinical application of continuum active micro-endoscope robot based on EAP actuation.

International audienceContinuum robots have shown astounding abilities in the medical field as numerous robotized devices have emerged. For instance, colonoscopes, arthroscopes, catheters, endoscopes, and other medical tools have been developed. Their ability to navigate through complex anatomy and narrow spaces represent the attractive features of continuum robots. We foresee to improve their usefulness for Minimally Invasive Surgery (MIS) and Natural Orifice Transluminal Endoscopic Surgery (NOTES). These robots may be downscaled depending on the target application, e.g., from endoscopy to neurosurgery. Shorter hospital stay, less pain and scarring, and quicker recovery might then be provided to the patient. Recently, active cannulas have been used for endonasal skull base surgery for pituitary gland cancer as depicted in Figure 1a, transurethral laser prostate surgery, laser surgery, beating heart surgery, and neurosurgery. Thus, we are interested in developing a micro-endoscope whether for diagnosis or laser surger

Hybrid Force/Position control applied to automated guiding tasks at the Microscale.

International audienceForce feedback control constitutes a promising solution for achieving fully automated micro-assembly. In this paper, we report the study of force feedback control used during guiding task. An experimental setup with two sensorized fingers is proposed. It enables to grasp a micropart of 2 mm x 50 μm x 50 μm in size and to estimate the lateral contact force. A simulator is developed to take into account the gripping forces evolution during a lateral perturbation. External hybrid force/position control is chosen for performing automated guiding tasks. Experimental results demonstrate the ability of the implemented controller and suitable design of microsystems

A hybrid Electrostatic-piezoelectric integrative actuated microsystem for robot-assisted laser phonomicrosurgery.

International audienceSeveral forms of microactuators have been investigated for microrobots, for example, electrothermal actuators [1,2], electrostatic actuators [3], piezoelectric actuators [4], electromagnetic actuators [5], acoustic actuators, pneumatics actuators, and shape memory alloys. Key enable technology for these miniaturized actuators is microfabrication processes for microelectromechanical systems because the processes can create submicron features with high precision, mass productive, and low cost. Examples of fabricated systems have been developed and some medical applications have been reported [1-5]. This talk provides literature reviews to compare advantages and disadvantages of micro actuators for biomedical applications. Then, we propose a new device that is devoted to medical applications (laser phonomicrosurgery) within the European μRALP-project [6]. Based on precise micromachined electrostatic and piezoelectric actuators, the platform is assembled using micro assembly approach. With sizes less than 5mm x 5mm x 5mm, the proposed design has three degree-of-freedom: two rotational motions around the in-plane axis and one out-of-plane translational motion. Static and dynamic analysis of the device is simulated by Finite Element Analysis and compared to theoretical calculations. Fig. 1 depicts the CAD-scheme of the designed device. This system preserves outstanding characteristics of both actuators for fast response and low power consumption. Moreover, challenge of electrostatic actuator for a high driving voltage and challenges of piezoelectric actuator for hysteresis effects and charge leakage problems are reduced with collaborated controls and operations of two sets of actuators

Automated Micro-assembly tasks based on hybrid Force/position Control.

International audienceFull automated micro-assembly is an ongoing challenge for researchers. The use of force control constitutes a suitable approach to achieve automated micro-assembly. It takes into account microscale specificities like pull off forces, measurement resolution... The integration of force sensors in micro-assembly station is discussed. An experimental setup is proposed to achieve automated guiding tasks of 2mm x 50 μm x 50 μm microparts. It is based on two-sensing-finger microgripper of 2 mN force range. Interaction forces are modeled and used to establish suitable strategy for guiding according to stability conditions and response time. Control scheme which combines force and position control is proposed and its integration to dSPACE board for real time control is achieved. Automated guiding task is performed with dynamic rejection of perturbation within 35 ms and a ramp tracking with a contact force of 20 μN between the rail side and the micropart is obtained

Active force control for Robotic Micro-Assembly : Application to guiding tasks.

International audienceThis paper presents an analytical model and experimental results from a study of guiding tasks in microassembly. This work is focused on the use of two fingers for gripping microparts. The stability of the grasp when the contact appears is investigated and strategies during the guiding task are discussed. The contact side detection and the contact force estimation are studied. The incremental control in static mode is then investigated for controlling the guiding task. Experimental setups are proposed and some experimental results are presented

Presentation, Force Estimation and Control of an instrumented platform dedicated to automated micromanipulation tasks.

International audienceThis paper presents a platform used to measure micromanipulation forces. The main interest of the proposed platform is that it uses classical force sensors with limited range and adapts these sensors to that of micromanipulation forces. The proposed platform, and an additional micropositioning device, are afterwards used to develop a micromanipulation system. To automate this system, we design two control levels. First, an internal loop with a PID controller is employed to improve the micropositioning device's performances. Then, an external loop based on an incremental control law is implemented to control the force. The automated system is finally used for the micromanipulation task on rigid and non-rigid microobjects

Automated Guiding Task of a Flexible Micropart Using a Two-Sensing-Finger Microgripper.

International audienceThis paper studies automated tasks based on hybrid force/position control of a flexible object at the microscale. A guiding task of a flexible micropart is the case of the study and is achieved by a two-sensing-finger microgripper. An experimental model of the behavior of the microgripper is given and the interaction forces are studied. Based on grasp stability, a guiding strategy taking into account the pull off forces is proposed. A specific control strategy using an external hybrid force/position control and taking into account microscale specificities is proposed. The experimental results of automated guiding task are presented

Guiding strategies for the assembly of micro-components subjected to planar pull-off-force.

International audienceDuring micro-assembly processes, planar contacts often appear (between two manipulated components, one manipulated component and its gripping tool or substrate). Adhesion forces being predominant at the microscale, such contacts have important consequences on assembly strategies. One of these adhesion forces is the pull-off force which is the necessary force to break a contact. This article focuses on the measurement of pull-off force of micrometric planar contacts (50x50 m2) and shows that it can be in the range of several hundreds of microNewtons. Consequences of this pull-off force on assembly strategy, especially guiding tasks, are then introduced. A strategy based on a force study is applied on teleoperated assembly sequences and validates the proposed guiding strategy. The study also enables to establish design rules that are specific for the microscale and that can e applied to the field of MOEMS assembly

Characterizations and Micro-assembly of Electrostatic Actuators for 3-DOF Micromanipulators in Laser Phonomicrosurgery.

International audienceThis paper presents a design of electrostatic actuators for 3-DOF micromanipulators in robot-assisted laser phonomicrosurgery. By integrating three sets of electrostatic actuators in a vertical configuration, scanning micro-mirror canbe used as a manipulator for laser source. Key enable technology for these miniaturized actuators is microfabrication processes for microelectromechanical systems (MEMS) because the processes can create submicron features with high precision, mass productive, and low cost. Based on precise micromachined electrostatic actuators, the platform is assembled using micro assembly approach. With sizes less than 5 mm x 5 mm x 5 mm, the proposed design has three degree-of-freedom: two rotational motions around the in-plane axis and one out-of-plane translational motion. Static and dynamic analysis of the device is simulated by Finite Element Analysis (FEA) and compared to theoretical calculations. This system preserves outstanding characteristics of electrostatic actuators for fast response and low power consumption. By micro-assembly of the scanning micromirror, the endoscopic systems can be created with a high range of motion and high scanning speed. The target applications of this system include laryngeal microsurgery, optical coherence tomography (OCT), and minimally invasive surgeries (MIS)