Gravity compensation of an upper extremity exoskeleton.

This paper presents a new gravity compensation method for an upper extremity exoskeleton mounted on a wheel chair. This new device is dedicated to regular and efficient rehabilitation training for post-stroke and injured people without the continuous presence of a therapist. The exoskeleton is a wearable robotic device attached to the human arm. The user provides information signals to the controller by means of the force sensors around the wrist and the arm, and the robot controller generates the appropriate control signals for different training strategies and paradigms. This upper extremity exoskeleton covers four basic degrees of freedom of the shoulder and the elbow joints with three additional adaptability degrees of freedom in order to match the arm anatomy of different users. For comfortable and efficient rehabilitation, a new heuristic method have been studied and applied on our prototype in order to calculate the gravity compensation model without the need to identify the mass parameters. It is based on the geometric model of the robot and accurate torque measurements of the prototype's actuators in a set of specifically chosen joint positions. The weight effect has been successfully compensated so that the user can move his arm freely while wearing the exoskeleton without feeling its mass.

A biomechanical model of the female reproductive system and the fetus for the realization of a childbirth virtual simulator.

Our main work consists in modeling of the female pelvis and uterus, as well as the human fetus. The goal of this work is to recover the different forces generated during the delivery. These forces will be input to the haptic obstetric training tool BirthSim which has already been developed by the Ampère Laboratory at the INSA of Lyon. This modeling process will permit us to develop a new training device to take into account different anatomies and different types of delivery. In this paper, we will firstly show the different existing haptic and virtual simulators in the obstetric world with their advantages and drawbacks. After, we will present our approach based on a biomechanical modeling of concerned organs. To obtain interactive time performance, we proceed by the simplification of the organs anatomy. Then, we present some results showing that FEM analysis can be used to model forces during childbirth. In the future, we plan to use this work to more accurately control a childbirth simulator.

Assessment of forceps blade orientations during their placement using an instrumented childbirth simulator.

This paper aims to highlight the benefits of simulator training in obstetric manipulations such as forceps blade placement. The BirthSIM simulator is used to mimic operative vaginal deliveries. To characterise forceps blade placement, we studied the curvature of forceps path. The orientation of the forceps blades are studied in the quaternion unit space to ensure time-independent analysis. The results showed progress for all novices in forceps blade placement. Simulator training helps them to develop their self-confidence and acquire experience before working in the delivery room.

Assessment of forceps use in obstetrics during a simulated childbirth.

BACKGROUND: In obstetrics, manipulations are mainly learned during real deliveries. To minimize the risks linked to such training, we propose a childbirth simulator as a teaching tool in hospitals. More specifically, we focus on training with forceps during obstetric manipulation. METHODS: The training method can be divided into two steps: the teaching of forceps placement, and the extraction manipulation. In this paper we focus on the extraction manipulation on the simulator and the analysis of the results, taking into account several parameters and using an evaluation function to obtain a global score. RESULTS: Experimental results reveal novice difficulty while proceeding to the fetus extraction. These results highlight the fact that novices need a personalized training which can be carried out on the BirthSIM simulator. CONCLUSION: Results lead to the conclusion that a simulator training offers benefit to novices by providing them with risk-free training to acquire initial experience before proceeding to conventional training in the delivery room.

A method to evaluate skill transfer and acquisition of obstetric gestures based on the curvatures analysis of the position and the orientation.

This paper focuses on the gesture analysis in order to compare two human gestures. The orientations and the positions of the gestures are both taken into account and the similarity rate between two gestures is calculated. In our case, the application is in obstetrics and the aim is to evaluate forceps blade placement. The method is based on the curvature analysis of the paths during the gesture. The 3-D position paths are expressed according to their cumulated chord length and the orientation paths in the quaternion unit space. These parameterizations lead to analyze data in space independently to time as requested by physicians. After filtering data in order to minimize sensor noises, the gestures are then compared by calculating the correlation between the position and the orientation curvatures of a novice gesture and an expert one. The results clearly show that novice skills in handling forceps increase in becoming smoother and closer to the reference placement. A childbirth simulator allows novices to acquire experience without any risks, however the training have to be completed with the extraction gesture evaluation and a compulsory training period in the delivery ward.

A medical simulator for subcutaneous contraceptive implant insertion.

New contraceptive methods like the subcutaneous implant offers a new kind of comfort for women with an efficiency similar to the contraceptive pill. Unfortunately the few numbers of unintended pregnancies that have been reported are generally due to a bad insertion of the implant. In order to give more security to patients, we have designed, in close collaboration with physicians, a new kind of medical simulator. This paper focuses on a device dedicated to a specific subcutaneous implant but it is worth noting that this simulator is relatively generic since it will be used for other subcutaneous techniques or other implant instruments. This simulator can be used for two purposes: one for training novice physicians in the correct manipulation and the other for physician certification which will help determine if they are capable of inserting the implant in vivo. This paper describes the approach which has led to the design of this simulator. It describes its functionalities, its several components but also methods used to analyze the manipulation of the implant insertion inside the patient. Finally first experimental results are reported and discussed. The system used in this paper makes possible to carry out training in a constraint-free context and provides the first mean of visualizing a maneuver that, until now, has been performed blindly.

Evaluation of obstetric gestures: an approach based on the curvature of quaternions.

This paper presents a method to evaluate a gesture carried out by a resident obstetrician by comparing it to a gesture carried out by an expert obstetrician. The studied gesture is the forceps blade placement. Resident paths were recorded on a childbirth simulator while placing forceps blades instrumented with six degrees of freedom sensors. The path is characterized by the positions and the orientations. In this paper we particularly focus on the orientations. Forceps orientations are expressed in the quaternion unit space and the curvature of quaternion path is compared by correlation to a reference defined by an expert. Residents have been trained on a simulator and their gestures are evaluated by comparing their orientation path curvatures to reference path curvatures. Quantitative results confirm the qualitative analysis, residents become more similar to the reference while training on simulator.

Design of a medical simulator for subcutaneous contraceptive implant insertion.

New contraceptive methods like the subcutaneous implant offers a new kind of comfort for women with an efficiency similar to the contraceptive pill. Unfortunately, the few numbers of unintended pregnancies that have been reported, are generally due to a bad insertion of the implant. In order to give more security to patients, we have designed, in close collaboration with physicians, a new kind of medical simulator. This simulator can be used for two purposes: one for training novice physicians in the correct gesture and the other for doctor certification which will help to determine if they are capable of inserting the implant in vivo. This paper describes the approach which has led to the design of this simulator. It describes its functionalities, its several components but also methods used to analyze the gesture of the implant insertion inside the patient. Finally, first experimental results are reported and discussed.

Evaluation of obstetric gestures: an approach based on the curvature of 3-D positions.

This paper presents a method to evaluate a gesture carried out by a resident obstetrician doctors by comparing it to a gesture carried out by an expert obstetrician doctors. The studied gesture is the forceps blade placement. Residents were recorded on a childbirth simulator while placing forceps blades. Their paths were compared in order to evaluate how similar they are to a reference path defined by an expert. The comparison method is developed with respect to expert requests: time independence and in considering the whole set of data and not only particular points. In order to respect these requests, the developed method lies on the correlation coefficient between the path curvatures. Residents have been trained on a simulator and their gestures were evaluated by comparing their path curvatures to reference path curvatures. Quantitative results confirm the qualitative analysis, residents become more similar to the reference while training on simulator.

[Obstetrical forceps: yesterday, today and tomorrow. Toward a new classification of obstetrical forceps]. / Les forceps hier, aujourd'hui et demain. Une nouvelle classification des forceps.

OBJECTIVE: Obstetrical forceps are used worldwide since more than 400 years. In 2003 forceps deliveries accounted for 6.3% of all deliveries of the AURORE Grand-Lyon perinatal network. Although more than 400 different forceps have been described, obstetrics handbooks neither describe experimental forceps nor provide any chapter dedicated to instrumental delivery training. Our aim was to provide junior obstetricians with information that will allow them to select the best instrument and to let them know about experimental as well as pedagogic forceps. PATIENTS AND METHODS: International literature review using the terms "forceps" and "delivery" and a four year experimental work involving a close collaboration between obstetricians and biomechanics of the INSA engineering school. RESULTS: Two instruments are presented as well as a new forceps classification. DISCUSSION AND CONCLUSION: This classification distinguishes between three types of forceps: operational forceps designed to delivers neonates, experimental forceps designed to study biomechanics and training forceps designed for resident training. For the first time the classic blind forceps procedure is transformed in a full screen real time procedure.

[Instrumental extraction in 2002 in the "AURORE" hospital network: incidence and serious neonatal complications]. / Extraction instrumentale en 2002 au sein du réseau AURORE : incidence et complications néo-natales graves.

OBJECTIVES: The purpose of this study was to evaluate the incidence of forceps and vacuum application and the incidence of its related neonatal complications. This study was performed in a network of 37 maternity hospitals. PATIENTS AND METHOD: A postal questionnaire was sent to 156 obstetricians between February and March 2003. RESULTS: Response rate was 78%. In 2002 the operative vaginal delivery rate was 11.2% of all live births. Forceps are the primary instruments (6.3%) whereas vacuum delivery rate was 4.9%. One obstetrician never uses forceps while 38 (31%) never use vacuum. Only 29 (24%) report using both instruments frequently. During 2002 no neonatal death related to an operative vaginal delivery was reported while 145 neonatal complications were (3.2%). Major complications were one depressed skull fracture (1/4589) and 14 extensive caput succedaneum (14/4589). Minor complications were cutaneous lesions (124/4589) and facial palsy (6/4589). Vacuum delivery was associated with a significantly higher extensive caput succedaneum rate (P = 0.018) while the only depressed skull fracture observed was related to forceps use. Forceps delivery was associated with a significantly higher cutaneous lesions rate (P < 0.001). DISCUSSION AND CONCLUSIONS: This study showed that, in 2002, operative vaginal deliveries still represent a significant amount of vaginal deliveries, a majority of obstetricians do not use both instrument and neonatal associated complications are frequent (3.2%) but rarely severe. Therefore, we believe that every method that allows a safe teaching of operative delivery should be promoted.