Laura Gastaldi

Pneumatic active gait orthosis

Abstract The paper describes design, construction and experimental testing of an active gait orthosis intended to assist locomotion in paraplegic subjects. Design specifications were formulated on the basis of an analysis of the context in which the device will be used. Different joint activation solutions were then proposed and examined. Considerable care was devoted to defining the logic and control system and to implementing the electro-pneumatic circuit, given that the system must be worn by a disabled subject who has no sensory perception in the lower limbs. Experimental tests, which made it possible to determine system performance at each step of development, were carried out with no user, then with a healthy user and finally with a paraplegic user. Experimental results consisting of graphs and photographic images are presented and discussed.

A combined robotic and cognitive training for locomotor rehabilitation: evidences of cerebral functional reorganization in two chronic traumatic brain injured patients

It has been demonstrated that automated locomotor training can improve walking capabilities in spinal cord-injured subjects but its effectiveness on brain damaged patients has not been well established. A possible explanation of the discordant results on the efficacy of robotic training in patients with cerebral lesions could be that these patients, besides stimulation of physiological motor patterns through passive leg movements, also need to train the cognitive aspects of motor control. Indeed, another way to stimulate cerebral motor areas in paretic patients is to use the cognitive function of motor imagery. A promising possibility is thus to combine sensorimotor training with the use of motor imagery. The aim of this paper is to assess changes in brain activations after a combined sensorimotor and cognitive training for gait rehabilitation. The protocol consisted of the integrated use of a robotic gait orthosis prototype with locomotor imagery tasks. Assessment was conducted on two patients with chronic traumatic brain injury and major gait impairments, using functional magnetic resonance imaging. Physiatric functional scales were used to assess clinical outcomes. Results showed greater activation post-training in the sensorimotor and supplementary motor cortices, as well as enhanced functional connectivity within the motor network. Improvements in balance and, to a lesser extent, in gait outcomes were also found.

Wearable sensors for gait analysis

Systems based on inertial sensors are increasingly used in motion analysis due to their low cost, portability and wearability. However, since accuracy is crucial in clinical gait analysis, it is important to assess it in new systems. The aim of this study is to compare the performances of a magnetic and inertial sensors system (MIMUs) to a gold standard, the electromechanical system STEP32. Results shows that spatio-temporal parameters are accurately estimated by the MIMUs system. Joint kinematics does not reach the accuracy of the STEP32 system. In fact, although MIMUs measurements on the knee and hip joints are clinically acceptable, they are not yet reliable for the ankle joint.

Accuracy evaluation of a new stereophotogrammetry-based functional method for joint kinematic analysis in biomechanics

The human joint kinematics is an interesting topic in biomechanics and turns to be useful for the analysis of human movement in several fields. A crucial issue regards the assessment of joint parameters, like axes and centers of rotation, due to the direct influence on human motion patterns. A proper accuracy in the estimation of these parameters is hence required. On the whole, stereophotogrammetry-based predictive methods and, as an alternative, functional ones can be used to this end. This article presents a new functional algorithm for the assessment of knee joint parameters, based on a polycentric hinge model for the knee flexion–extension. The proposed algorithm is discussed, identifying its fields of application and its limits. The techniques for estimating the joint parameters from the metrological point of view are analyzed, so as to lay the groundwork for enhancing and eventually replacing predictive methods, currently used in the laboratories of human movement analysis. This article also presents an assessment of the accuracy associated with the whole process of measurement and joint parameters estimation. To this end, the presented functional method is tested through both computer simulations and a series of experimental laboratory tests in which swing motions were imposed to a polycentric mechanical analogue and a stereophotogrammetric system was used to record them.

Indoor motion analysis of a subject wearing prosthesis for adaptive snowboarding

The growing popularity of adaptive snowboarding has motivated the designs of new prostheses for lower limb amputees. In the paper the biomechanics of an amputee subject wearing an energy-storing trans-femoral prosthesis for snowboarding is investigated. Experimental motion analysis lab tests were conducted by two expert surfers, an amputee and an able body subject, in order to compare the different behaviours. Results for the two subjects and for different working conditions are reported and analysed. A strong dependence of the prosthesis behaviour on working conditions, especially on working frequency, can be pointed out

Analysis of Exoskeleton Introduction in Industrial Reality: Main Issues and EAWS Risk Assessment

Exoskeletons are part of the technological and organizational innovation sought by the fourth industrial revolution to support and re-launch the manufacturing area. In the present study, we described the experimental protocol designed to test the usability and acceptance of an upper limbs passive exoskeleton. In total, 42 workers from FCA plants volunteered to participate in the research study. The testing campaign included static and dynamic tests aimed at evaluating the potential benefit of the exoskeleton (lessen muscle strain, higher comfort rating and dexterity) vs. possible restrictions to movements and work-device interactions in tasks resembling work activities. Open questions remain on how to assess the biomechanical workload risk, especially in the design phase, for which holistic methods like EAWS are needed.

Evaluation of the factors affecting the optimal fiducial configurations calculated through a genetic-algorithm-based methodology in image-guided neurosurgery

Image‐guided neurosurgery usually involves a point‐pair registration between two spaces, associating the patient in the operating room with pre‐operative image scans. The distribution and number of fiducial markers during registration are critical for the expected error at the target point.

Biomechanics of simulated versus natural cross-country sit skiing

The purpose of this study was to investigate the biomechanics of cross-country sit-skiing in simulated and natural skiing. Thirteen international level athletes participated in a ski ergometer test (simulated conditions) and a test on snow in a ski-tunnel (natural conditions) using their personal sit-ski. Tests in both conditions were performed at individual maximal speed. When comparing the two conditions the main results were: (1) maximal speed in simulated conditions was lower (p<0.05) but correlated well with the natural condition (r=0.79, p<0.001); (2) no differences in pole force variables were found; peak force (r=0.77, p<0.01) and average force (r=0.78, p<0.01) correlated well; (3) recovery time and time to peak did not differ and time to impact correlated with each other (r=0.88, p<0.01); (4) no differences were found in peak electromyography (EMG) and average EMG for Triceps, Pectoralis, and Erector Spinae; Rectus Abdominis did not differ in peak. EMG peak and average EMG of all muscles were correlated between the two conditions (r=0.65-0.94; p<0.05-0.01). Although some differences were observed, this study demonstrated that technical skill proficiency in natural and simulated cross-country skiing is comparable from a force production and muscle activation perspective.

Hydraulic actuation system with active control for the lateral suspensions of high speed trains

High speed trains normally use actively controlled pneumatic systems to recentre the car body with respect to the bogie when the train negotiates a curve. Pneumatic systems are used because of their softness, which adds a little contribution to the elastic force generated by the mechanical springs of the lateral suspension system, thereby allowing the necessary dynamic isolation between car body and bogie. However, pneumatic systems have the drawbacks of large dimensions and slow response, often accompanied by a few damped oscillations. An innovative solution was developed that makes use of hydraulic actuators, providing them with artifi cial compliance generated by an appropriate control, hence making the hydraulic actuators suitable for this application. A car body centring system is thus obtained that presents fast response, small volume and a softness comparable to that of a pneumatic system. The optimal control law for this system was defi ned, the system dynamic characteristics were analysed and a technological demonstrator was built to assess the system merits. The paper outlines the theoretical grounds for the system control, its performance and the most signifi cant results obtained during a test campaign conducted on the technological demonstrator.

Determination of the human arm stiffness efficiency with a two antagonist muscles model

In the last years, due the working age increase, more and more attention was given to the use of exoskeleton for industrial applications, such to reduce fatigue and the operator effort. Since in industrial practice, stiffening the joint is a requested action for those operations in which precision is needed, an exoskeleton whose stiffness could be controlled by the operator would reduce the operator discomfort. In this paper we attempt to study the stiffness of the elbow on which two muscles act as agonist-antagonist and we proposed an estimation of the efficiency.