Maurice Bétemps

The design of a new type of micro robot for the intestinal inspection

In the last few years, we have observed a fast development of modern science and technology. In the field of medical engineering, the same evolution is observed, and the minimally invasive surgery (MIS) has became one of the most important research area. Medical endoscope is one typical medical instrument that complies with the requirement of MIS. This paper deals with the design of a new type of micro-robot for intestinal inspection. Because of the injuries caused by the colonoscope during the operation, and the long time spent at the hospital by the patient, we focus on a new type of intelligent colonoscope. The main purpose of this medical tool is to be in accordance with MIS by minimizing the contact between the colonoscope and the interior boundary of the colon, and to make the progression of the colonoscope easier for the surgeon. Our current prototype, which is twice the size of the final tool, is electro pneumatically driven. It is constituted by three metal bellows disposed 120/spl deg/ apart, and its position in the intestine is driven by three sensors positioned on the superior plate. Some experimental results are presented.

Micro robots dedicated to small diameter canalization exploration

In this paper, three peculiar in-pipe microrobots are presented. They are the result of investigations of 3 laboratories involved in the microrobotics workgroup of the French National Centre of the Scientific Research (CNRS). They have been conceived to answer the locomotion problem inside industrial tubes of small diameter. Each of them is specific to a particular set of conditions.

A new mechanical birth simulator: BirthSIM

This paper deals with a new mechanical birth simulator (BirthSIM). Currently available birth simulators provide manikins that include new-born head and maternal pelvis but they do not produce the movements of the new-born in the mothers pelvis. Furthermore available maternal pelvis do not include interface pressure and are not enough realistic to simulate maternal pelvic muscles. In summary, these simulators do not help students to practice the gestures they should safely use to help the new-born in normal and at-risk situations of delivery. The originality of our mechanical birth simulator, is to provide a system to mimic the last step of the instrumental delivery, to insure a safe training of junior obstetricians and to test new techniques in obstetrics practice. The new mechanical birth simulator is composed of three parts: a physical new-born head and a maternal pelvis manikin, an interface pressure system, and a pneumatic actuator that develops an active resistance. Driven by a computer, the simulator can simulate the contractions, the interface pressure applied in the new-born head and mimic birth complications.

The development of a bendable colonoscopic tip

Medical technology is changing rapidly with devices such as stereo-endoscopes, virtual reality, tele-presence surgery, and robotics for use in colonoscopy. The minimally invasive surgery (MIS) is becoming one of the most important research area in the field of medical engineering. The colonoscope is one typical medical instrument that complies with the requirement of MIS. This paper describes the design of a new type of intelligent tip for the colonoscope. Because of the injuries caused by this surgical tool during the operation, we focus on a new type of bendable tip. The main purpose of this medical tool is to be in accordance with MIS by minimizing the contact between the colonoscope and the interior boundary of the colon, and to make the progression of the colonoscope easier for the surgeon. Our current prototype is twice the size of the final tool. It is electro-pneumatically driven and constituted by three metal bellows disposed 120/spl deg/ apart. Its position in the intestine is driven by three sensors positioned on the superior plate. Some experimental results are presented.

Identification of the flexible actuator of a colonoscope

In recent years, much has been studied on the colonoscope because it is a very important tool for diagnosing colon cancer which is the second leading cause of cancer in the developed countries. During the course of colonoscopy, the colonoscope need to be inserted to the tortuous colon of patients. This is a procedure often painful for the patient and complex for the surgeon. In order to solve this problem, a new flexible actuator of a colonoscope capable of avoiding the injury to the patients has been developed for autonomous colonoscope in our lab. In this paper we mainly deal with the modeling and parameter identification of our flexible actuator in order to design a controller that can automatically detect the contact between the surgical instruments and the intestine. First a mathematical model of the actuator was deduced and linearised from previous research, then a direct identification approach was studied for the continuous-time system, using continuous-time ARX (CARX) model and the Levenberg Marquardt (L-M) algorithm. Finally, the experiment setup and the identification of the parameters of the actuator are described and the results are compared with the data obtained from classical frequency response method. Experimentation has proved the continuous-time method to be very effective for our system identification.

A random exploration approach for automatic chamberless insertion

The stochastic approach strategy to realize the robotized in sertion of low-clearance, chamferless parts is studied in both the analytical and experimental contexts. The analytical ap proach is discussed in terms of stochastic differential equations that involve Gaussian white and colored noises processes to model a planar random search. Special attention is devoted to characterize the time required for the insertion, a random variable whose first moment calculation (i.e., the mean) is dealt with. In the mathematical modelization context adopted, it is remarkable that the calculated mean mating time grows slowly (i.e., logarithmically), with the precision required to perform an insertion. The. theoretical results are validated on a robo tized assembly system, also presented in this article. In this experimental system, the random movements are generated by pseudorandom binary sequences that, for the time scales con sidered, are large band processes. The experimental data are observed to sustain the logarithmic behavior obtained analyt ically. Hence, in addition to its simplicity and flexibility, the random strategy approach appears to be very efficient when high mating precision is required.

Geometric model of the DCR-LAI compliant device

In this paper the authors present a mathematical model of geometric and kinematic behaviour of an original passive compliant device provided with two rotation centres, called DCR–LAI system. This device is designed for a robotic assembly of parts with very small tolerances including a chamfer at the hole. The given modelisation may be used as a decision aid for the choice of a compliant device with regard to characteristics of parts being assembled.

Control of a planar fine positioner actuated by metal bellows

Abstract In this paper we discuss the modeling and control of a pneumatic two-degree-of-freedom fine positioner for, but not restricted to, robotic applications requiring small, fast and precise movements. The micro-manipulator actuation is based on a new technique: motion is generated by the deformation of metal bellows controlled by air pressure. This technique yields a direct-drive pneumatic actuator capable of producing high force with negligible static friction and no backlash over a relatively large operating range. The trade-off however is that a well-adapted control strategy is necessary to achieve fast and accurate motion. The development of a linearized model of reasonable complexity and the selection of a position state feedback control law based on this model are the main topics of our contribution, which also comprises a description of the fine positioner. In order to meet the requirements of micro-manipulation applications, the tuning of the control scheme parameters are analyzed. The development of the actuator control strategy is completed by its implementation that involves, for the sake of simplicity and low-cost, only position sensing. All this results in a proper control scheme for metal bellows actuation in the context of robotics applications; its performance is evaluated both by simulation and from the experiences conducted on the actual prototype. The fine positioner has an isotropic dynamic behavior with a settling time inferior to 28 ms, it is capable of developing up to 250 N of peak force and features a positioning accuracy of 2 μm over an operating range of 2 mm. Finally, the application of the fine positioner to robotic assembly systems is also presented and analyzed.

Modeling and control of a colonoscopic tip under disturbance of the insertion of colonoscope

During the conventional procedure of the colonoscopy, there are two important movements, the introduction of colonoscope in the colon and the maneuver of the distal end. In this paper, the authors focus on a new type of automatic bendable tip while keeping the advance of the colonoscope in the colon by endoscopist. The main purpose of this tip is to make the colonoscope overcome acute intestinal bends and make easier the progression of the colonoscope for the surgeon. Firstly, we model our current prototype tip, named EDORA (distal extremity with automatic orientation). Next, the parameters of the system are estimated by using the Levenberg-Margquardts algorithm. Finally, by using the maximum of the sensitivity function a gain margin specification is made. A set point for a position controller is designed, thus the tip can stay in the middle of the colon with disturbance rejection due to the manipulation of the colonoscope. In the same time, this controller has been designed to make the tip have some degrees of compliance to reduce the contact force due to the undesirable contact with the colon. Simulation and experimental results for the controller would be presented by emulating the real environments.

Design and control of a pneumatic microrobot for in-pipe inspection of nuclear pipes

Micro Electro Mechanical Systems (MEMS) are integrated in many current products and are not only the concern of military defence or medicine. Nowadays, many different types of microactuators exist which use different types of energy and perform a variety of movements. Several applications require small systems to inspect confined and hostile places. Vapour generators in nuclear plants comprise of 3000 to 5000 vertical pipes of 17 mm diameter. These pipes endure high mechanical constraints and have to be inspected to detect possible cracks. Our study is based on the design, modelling and implementation of a microrobot able to move upwards within and carry sensors into these pipes. It moves as an inchworm and is composed of 2 blocking modules that brace the robot on the pipe sides, and one stretching module that creates a step. This actuator is pneumatic and composed of metal bellows. By this original design, the microrobot has a good power-to-volume ratio and it can carry a load of 600 g. Its good positioning accuracy has been proved over a 90 mm course where the error of positioning is less than 60 μm.