This paper presents a robot aimed to assist the shoulder movements of stroke patients during their rehabilitation process. This robot has the general form of an exoskeleton, but is characterized by an action principle on the patient no longer requiring a tedious and accurate alignment of the robot and patient’s joints. It is constituted of a poly-articulated structure whose actuation is deported and transmission is ensured by Bowden cables. It manages two of the three rotational degrees of freedom (DOFs) of the shoulder. Quite light and compact, its proximal end can be rigidly fixed to the patient’s back on a rucksack structure. As for its distal end, it is connected to the arm through passive joints and a splint guaranteeing the robot action principle, i.e. exert a force perpendicular to the patient’s arm, whatever its configuration. This paper also presents a first prototype of this robot and some experimental results such as the arm angular excursions reached with the robot in the three joint planes.

Категория: Ищем научные статьи | Нет комментариев »

The Robotic Gait Rehabilitation (RGR) Trainer targets secondary gait deviations in stroke survivors undergoing rehabilitation. Using an impedance control strategy and a linear electromagnetic actuator, the device generates a force field to control pelvic obliquity through a Human-Machine Interface (i.e. a lower body exoskeleton). Herein we describe the design of the RGR Trainer Human-Machine Interface (HMI) and we demonstrate the system’s ability to alter the pattern of movement of the pelvis during gait in a healthy subject. Results are shown for experiments during which we induced hip-hiking — in healthy subjects. Our findings indicate that the RGR Trainer has the ability of affecting pelvic obliquity during gait. Furthermore, we provide preliminary evidence of short-term retention of the modified pelvic obliquity pattern induced by the RGR Trainer.

Категория: Ищем научные статьи | Нет комментариев »

A new set of lower limb orthoses was developed for the WalkTrainer project. This mobile reeducation device for paralyzed people allows overground gait training combining closed loop electrical muscle stimulation and lower limb guiding while walking. An active body weight support system offers precise body weight unloading during locomotion. A 6 DOF parallel robot moves the pelvis in any desired position and orientation. The lower extremity orthosis is composed of two key parts. First, a purely passive lightweight exoskeleton acts as the interface between the human leg and the machine. A 1 DOF knee orthotic joint is also designed to prevent hyperextension. Second, the active part — composed of a mechanical leg equipped with motors and sensors — is located behind each human leg, with its base fixed to the WalkTrainer base frame. The two kinematic chains are connected with appropriate linkages at the thigh and the ankle joint. Actuation of the hip, knee and ankle joints is thus provided for their flexion/extension axis. The active mechanism operates only within the sagittal plane and guides the ankle-foot subsystem. Thigh and shank add/abduction movements are possible and even essential since the pelvis moves in a 3D space. This achievement prevents the scissors effect while allowing natural walking motion at the other joints. This paper describes the design and development of the lower extremity orthosis. Starting from a biomechanical approach, the needed actuation and the mechanical structure are discussed as well as the interface between the patient and the robot.

Категория: Ищем научные статьи | Нет комментариев »

This paper analyzes cause of control errors for 5 DOF exoskeleton upper-limb rehabilitation robot. Based on the method of typical repetitive control, let multiple improved repetitive control loops with filtering parallel embed into closed-loop of control system in order to eliminate motion error of rehabilitation robot with multi-channel periodic input signal. The simulation results show that the effect of system tracking is very well and it has higher stability, tracking control purpose is attained.

Категория: Ищем научные статьи | Нет комментариев »

A Bowden cable performance analysis, based on a design of experiments (DoE) is presented for orthosis applications. The need for analysing these cables is based on the construction of IKO (IKerlan’s Orthosis) with five actuated degrees of freedom (DoF) to help the human arm. The aim is for an individual to be capable of lifting weight without any great effort using this exoskeleton, which should be portable and readily dressed (and, therefore, lightweight). In order to transmit the power from the actuators to the joints, Bowden cables are used due to their flexibility and light weight. Transmission performance has been analysed in terms of load loss and cable deformation in order to estimate actuator requirements and positioning accuracy. A test bench has been built to measure the cable deformation and load loss occurring between the two ends of the cable in different situations. This has been applied to cables with two different diameters and at different loads. The variables for which the effect has been analysed are weight, the angle formed by the cable at the point where it leaves the sheath, the cable flexion angle, cable length, cable flexion curvature radius and cable type.

Категория: Ищем научные статьи | Нет комментариев »