SCRIPT Passive Orthosis: Design and technical evaluation of the wrist and hand orthosis for rehabilitation training at home

Abstract

In this paper, a new hand and wrist exoskeleton design, the SCRIPT Passive Orthosis (SPO), for the rehabilitation after stroke is presented. The SPO is a wrist, hand, and finger orthosis that assists individuals after stroke that suffer from impairments caused by spasticity and abnormal synergies. These impairments are characterized in the wrist and hand by excessive involuntary flexion torques that make the hand unable to be used for many activities in daily life. The SPO can passively offset these undesired torques, but it cannot actively generate or control movements. The user needs to use voluntary muscle activation to perform movements and thus needs to have some residual muscle control to successfully use the SPO. The SPO offsets the excessive internal flexion by applying external extension torques to the joints of the wrist and fingers. The SPO physically interacts with the users using the forearm shell, the hand plate and the digit caps from the Saebo Flex, but is otherwise a completely novel design. It applies the external extension torques via passive leaf springs and elastic tension cords. The amount of this support can be adjusted to provide more or less offset force to wrist, finger, or thumb extension, manually. The SPO is equipped with sensors that can give a rough estimate of the joint rotations and applied torques, sufficient to make the orthosis interact with our interactive gaming environment. Integrated inertial and gyroscopic sensors provide limited information on the user's forearm posture. The first home-based patient experiences have already let to several issues being resolved, but have also made it clear that many improvement are still to be made.

Design, development and deployment of a hand/wrist exoskeleton for home-based rehabilitation after stroke - SCRIPT project

“…The integrated bending sensors in the leaf springs at the fingers are good enough to differentiate between different grasps, 36 and can detect small changes of motion, but are only able to resolve between large absolute angle deviations of roughly 20 degrees. 37 These limitation are caused not by the mechanism itself, but by the type of bending sensor used: the flexible resistance-based sensors suffer from natural decay in step response that makes it hard to get accurate absolute values from the sensors. In the wrist, the flexion-extension axis rotation is measured using a potentiometer at the forearm link of the parallelogram.…”

SCRIPT passive orthosis: design of interactive hand and wrist exoskeleton for rehabilitation at home after stroke

“…Based on these ranges, the desired ROM for the orthoses (Ates et al 2014a;Ates et al 2013) are given in Table 1.…”

“…Therefore, the orthosis also has to meet the following usage requirements: Table 1 Desired range of motion for hand and wrist therapy (van Andel et al 2008;Ates et al 2014a;Ates et al 2013;Clarkson 2000;Ryu et al 1991 …”

“…The SCRIPT project 1 aimed to develop an improved rehabilitation system for motivational and affordable post-stroke therapy at home Ates et al 2013;Prange et al 2012). In the project, we have explored multiple actuation principles and interaction mechanisms in several prototypes (see Fig.…”

Robotic and Mechanotherapeutic Technology to Restore the Functions of the Upper Limbs: Prospects for Development (Review)

“…Mostly, these exoskeleton devices are made in the form of a glove which can be either flexible or rigid. So, the SCRIPT exoskeleton of the forearm and hand [86] is a passive orthesis which can assist movement with springs and elastic rods. The orthesis is equipped with goniometry sensors and potentiometers that can be used, not only for providing biological feedback, but also for evaluating the movements and dynamics of rehabilitation.…”