Bernard Bayle

Manipulability of Wheeled Mobile Manipulators: Application to Motion Generation:

We propose a systematic modeling of the nonholonomic mobile manipulators built from a robotic arm mounted on a wheeled mobile platform. We use the models derived to generalize the standard definition of manipulability to the case of mobile manipulators. The effects of mounting a robotic arm on a nonholonomic platform are shown through the analysis of the manipulability thus defined. Several applications are evoked, particularly applications to control. The optimization of criteria inherited from manipulability considerations are given to generate the controls of our system when its end effector motion is imposed.

In Vivo Model Estimation and Haptic Characterization of Needle Insertions

During percutaneous interventions, the haptic perception of transitions and ruptures in the tissues is fundamental. In the medical robotics context, these events should be conveyed to a remote telemanipulating practitioner or should be taken into account in a robotic control scheme. However, this problem is extremely complex given the nature and the variety of tissues involved in percutaneous procedures. In this article, in vivo percutaneous experiments associated with an online model estimation of the interaction between tissues and a surgical needle are presented for the first time. The estimation scheme is then used to provide a robust method to automatically detect the transitions that occur during needle insertion. Finally, the principle of a modified teleoperation scheme that would allow better haptic discrimination of ruptures is proposed and illustrated.

Modeling and Evaluation of Low-Cost Force Sensors

Low-cost piezoresistive sensors can be of great interest in robotic applications due not only to their advantageous cost but to their dimension as well, which enables an advanced mechanical integration. In this paper, a comparison of two commercial piezoresistive sensors based on different technologies is performed in the case of a medical robotics application. The existence of significant nonlinearities in their dynamic behavior is demonstrated, and a nonlinear modeling is proposed. A compensation scheme is developed for the sensor with the largest nonlinearities before discussing the selection of a sensor for dynamic applications. It is shown that force control is achievable with these kinds of sensors, in spite of their drawbacks. Experiments with both types of sensors are presented, including force control with a medical robot.

A Force Feedback Teleoperated Needle Insertion Device for Percutaneous Procedures

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.

A Parallel Robotic System with Force Sensors for Percutaneous Procedures Under CT-Guidance

This paper presents a new robotic framework for assisted CT-guided percutaneous procedures with force feedback and automatic patient-to-image registration of needle. The purpose is to help practitioners in performing accurate needle insertion while preserving them from harmful intra-operative X-rays imaging devices. Starting from medical requirements for needle insertions in the liver under CT-scan, a description of a dedicated parallel robot is made. Its geometrical and physical properties are explained. The design is mainly based on the accuracy and safety constraints. A real prototype is presented that is currently tested.

Design considerations for a novel MRI compatible manipulator for prostate cryoablation

PurposeProstate carcinoma is a commonly diagnosed cancer in men. Nonsurgical treatment of early stage prostate cancer is an important alternative. The use of MRI for tumor cryoablation is of particular interest: it offers lower morbidity compared with other localized techniques. However, the current manual procedure is very time-consuming and has limited accuracy. A novel robotic assistant is therefore designed for prostate cancer cryotherapy treatment under MRI guidance to improve efficiency and accuracy.MethodsGesture definition was achieved based on actions of interventional radiologists at University Hospital of Strasbourg. A transperineal approach with a semiautonomous prostatic cryoprobe localization procedure was developed where the needle axis is automatically positioned before manual insertion. The workflow was developed simultaneously with the robotic assistant used for needle positioning.ResultsThe design and the associated workflow of an original wire-driven manipulator were developed. The device is compact and has a low weight: its overall dimensions in the scanner are 100xa0× 100 × 40 mm with a weight of 120xa0g. Very good MRI compatibility was demonstrated.ConclusionsA novel cryoablation procedure based on the use of a robotic assistant is proposed. The device design was presented with demonstration of MRI compatibility. Further developments include automatic registration and in vivo experimental testing.

A Parallel 5 DOF Positioner for Semi-Spherical Workspaces

In this paper, a new five-degree-of-freedom parallel manipulator is described and modeled. This structure has been specially designed for medical applications that require in the same time mobility, compactness and accuracy around a functional point. The purpose of this robotic device is to help practitioners to perform accurate needle insertions while preserving them from harmful intra-operative X-ray imaging devices. The system is built from revolute joints, among which only five joints are actuated to convey the required five degrees of freedom to its moving platform. A numerical simulation of the workspace and a physical prototype are presented.Copyright

Bilateral controllers for teleoperated percutaneous interventions : evaluation and improvements

This paper presents two teleoperation control schemes developed in the context of percutaneous procedures in interventional radiology. The teleoperation task is characterized by a nonlinear interaction with the environment. The whole force feedback teleoperation structure is modeled to derive a practical, stable and transparent force feedback. The proposed control approach is based on the adaptation of standard force feedback teleoperation controllers. Position-position and force-position structures are improved by local compensation loops that include an a priori knowledge of the interactions between the slave robot and the environment made of soft tissues. This contribution allows to improve position tracking capabilities in spite of the nonlinearity of the interaction

Kinematic modelling of wheeled mobile manipulators

We propose a systematic modelling of the nonholonomic mobile manipulators built from a robotic arm mounted on a wheeled mobile platform. It extends the fundamental notions of nonholonomy, mobility and maneuverability to the case of these hybrid holonomic/nonholonomic systems. It offers unambiguous definitions and models to the designer of kinematic control laws.

Design and Evaluation of a Robotic System for Transcranial Magnetic Stimulation

Transcranial magnetic stimulation is a noninvasive brain stimulation technique. It is based on current induction in the brain with a stimulation coil emitting a strong varying magnetic field. Its development is currently limited by the lack of accuracy and repeatability of manual coil positioning. A dedicated robotic system is proposed in this paper. Contrary to previous approaches in the field, a custom design is introduced to maximize the safety of the subject. Furthermore, the control of the force applied by the coil on the subjects head is implemented. The architecture is original and its experimental evaluation demonstrates its interest: the compensation of the head motion is combined with the force control to ensure accuracy and safety during the stimulation.