Robotic Cane Controlled to Adapt Automatically to Its User Gait Characteristics.

Research on robotic assistance devices tries to minimize the risk of falls due to misuse of non-actuated canes. This paper contributes to this research effort by presenting a novel control strategy of a robotic cane that adapts automatically to its user gait characteristics. We verified the proposed control law on a robotic cane sharing the main shape features of a non-actuated cane. It consists of a motorized telescopic shaft mounted on the top of two actuated wheels driven by the same motor. Cane control relies on two Inertial Measurement Units (IMU). One is attached to the cane and the other to the thigh of its user impaired leg. During the swing phase of this leg, the motor of the wheels is controlled to enable the tracking of the impaired leg thigh angle by the cane orientation. The wheels are immobilized during the stance phase to provide motionless mechanical support to the user. The shaft length is continuously adjusted to keep a constant height of the cane handle. The primary goal of this work is to show the feasibility of the cane motion synchronization with its user gait. The control strategy looks promising after several experiments. After further investigations and experiments with end-users, the proposed control law could pave the road toward its use in robotic canes used either as permanent assistance or during rehabilitation.

Precisely positioning the tip of an instrument inserted through an orifice with a free wrist robot: application to prostate biopsies.

PURPOSE: Robots with a spherical unactuated wrist can be used for minimally invasive surgery. With such a robot, positioning the wrist center controls the instrument tip position when assuming that the insertion site behaves like a lever with a fixed and known fulcrum. In practice, this assumption is not always respected. In this paper we first study the practical consequences of this problem in terms of tip precision positioning. We then propose a robotic control scheme that improves the precision compared to the fixed point assumption approach. METHODS: In the first part of the paper, data recorded during robot-assisted transrectal needle positioning for prostate biopsies (nine patients) are exploited to quantify the positioning error induced by the use of a fixed point hypothesis in the positioning process. In the second part of the paper advanced control techniques allow for the online identification of a locally linear system that describes a model characterized by anisotropy and center displacement. A laboratory apparatus is used to demonstrate the resulting improvement on tip positioning precision. RESULTS: Errors obtained by processing the clinical data reach 7.5 mm at the tip in average. Errors obtained with the laboratory apparatus drop from 2.4 mm in average to 0.8 mm when using real-time model update.

Prostate biopsies assisted by comanipulated probe-holder: first in man.

PURPOSE: A comanipulator for assisting endorectal prostate biopsies is evaluated through a first-in-man clinical trial. This lightweight system, based on conventional robotic components, possesses six degrees of freedom. It uses three electric motors and three brakes. It features a free mode, where its low friction and inertia allow for natural manipulation of the probe and a locked mode, exhibiting both a very low stiffness and a high steady-state precision. METHODS: Clinical trials focusing on the free mode and the locked mode of the robot are presented. The objective was to evaluate the practical usability and performance of the robot during clinical procedures. A research protocol for a prospective randomized clinical trial has been designed. Its specific goal was to compare the accuracy of biopsies performed with and without the assistance of the comanipulator. RESULTS: The accuracy is compared between biopsies performed with and without the assistance of the comanipulator, across the 10 first patients included in the trial. Results show a statistically significant increase in the precision.

Evaluation of the effect of a laparoscopic robotized needle holder on ergonomics and skills.

BACKGROUND: Laparoscopy generates technical and ergonomics difficulties due to limited degrees of freedom (DOF) of forceps. To reduce this limitation, a new 5-mm robotized needle holder with two intracorporeal DOF, Jaimy(®), has been developed. The aim of this study was to evaluate its effects on ergonomics and skills. METHODS: Fourteen surgeons including eight senior and six residents were crossover randomized and stratified based on experience. Three suturing tasks were performed with both Jaimy(®) and a classic needle holder (NH): task 1: Peg-Board; task 2: hexagonal suture; task 3: frontal suture. Postural ergonomics of the dominant arm were evaluated with an ergonomics score (RULA score) thanks to motion capture, and muscular ergonomics with electromyography of six muscular groups (flexor and extensor carpis, biceps, triceps, deltoid, trapeze). Performance outcomes are a quantitative and qualitative score, and skills outcomes are the measurement of the number of movements and the path length travelled by the instrument. RESULTS: The RULA score showed a statistically improved posture with Jaimy(®) (p < 0.001). The cumulative muscular workload (CMW) of four muscles was not different. However, the CMW was in favor of the NH for the flexor carpi ulnaris (p < 0.001) and the triceps (p = 0.027). The number of movements was not different (p = 0.39) although the path length was shorter with Jaimy(®) (p = 0.012). The score for task 1 was in favor of the NH (p = 0.006) with a higher quantity score. Task 2 score was not different (p = 0.086): The quality part of the score was in favor of Jaimy(®) (p = 0.009) and the quantity part was higher with the NH (p = 0.04). The score for task 3 was higher with Jaimy(®) (p = 0.001). CONCLUSION: This study suggests that the use of a robotized needle holder improves both posture and the quality of laparoscopic sutures.

Manual segmentation of individual muscles of the quadriceps femoris using MRI: a reappraisal.

PURPOSE: To propose a manual segmentation method for individual quadriceps femoris (QF) muscles and to test its reliability for muscle volume estimation. MATERIALS AND METHODS: Images were acquired every 5 mm along the thigh using a 3T MRI scanner on 10 young (mean age: 25 years) and 10 older (mean age: 75 years) adults using a three-point 3D Dixon sequence. In each slice, anatomical cross-sectional areas of the individual quadriceps muscles of the dominant leg were outlined by two operators working independently. Differences between operators were assessed by means of Bland-Altman plots and intraclass correlation coefficients (ICC). This study was approved by the local Ethics Committee. RESULTS: Precise delimitation of individual muscles along the femur often remains challenging, particularly near their insertion areas where some muscles may be partially or totally fused. There was, however, an excellent interoperator segmentation reliability despite a systematic significant difference between operators (ICC > 0.99), mainly due to delineation divergences. Considering all subjects and muscles, differences between operators were all lower than 4.4%. CONCLUSION: This work has demonstrated the excellent reliability of manual segmentation to assess cross-sectional areas and therefore the volume of individual QF muscles using MRI. It may serve as a basis for a future segmentation consensus of the QF muscles.