# Evaluation of Commercial Ropes Applied as Artificial Tendons in Robotic Rehabilitation Orthoses
## 1 Introduction  
Stroke is the world's leading cause of death and disability [1]. with 6.7 million deaths per year, estimated to be the second leading cause of death by the year 2030 [2, 3]. Stroke is a clinical syndrome caused by a reduction in blood perfusion in brain structures and is characterized by disturbances in brain function [4]. About 57% of individuals, after having a stroke, have some of limitations in daily activities and more than 50% of these individuals have functional impairment, thus requiring some external help to perform functional tasks [5]. The prevalent motor deficits presented are paralysis (hemiplegia) or weakness (hemiparesis) of body contralateral half to stroke injury [6]. Clinically, muscle weakness, muscle tone abnormality, movement control deficiency, body composition changes of the extremities with loss of muscle and bone mass [7], posturalalteration, lack of mobility, abnormal synergistic patterns and loss or reduction of motor coordination can also be observed [8]. An innovative and promising rehabilitation alternative capable of enhancing the motor and functional capacity of individuals after stroke is the robotic therapy [9]. It uses robotic orthoses, which is mechatronic equipment ranging from the creation of artificial limbs, to robots that assist in rehabilitation or hospital or residential care [10]. The great advantage of using these devices is the high degree of repeatability and the performance of intensive activities with less professional supervision, using a simple routine of pre-programmed robot rehabilitation activities [8; 11; 12; 13]. Numerous systematic reviews have been performed showing the efficiency in using these devices to rehabilitate individuals [12; 14; 15; 16; 17; 18]. An Improvement in short and long-term proximal end (shoulder and elbow) motor control has been observed in acute and chronic post-stroke patients, using these devices [12; 17]. A combination of traditional methods and robotic therapy in some stages of stroke recovery can produce a significant improvement in elbow and shoulder motor recovery [16; 18]. An improvement in daily life activity, arm function and muscle strength has also been observed [15], as well as minor effects on motor control and mild effects on muscle strength compared with other short-term interventions using robotic therapy [14]. A combination of these devices with brain-computer interfaces has been also used to improve the rehabilitation ability of individuals after stroke, thus proving the effectiveness of these robots during therapy sessions [19]. Several devices have also been developed to rehabilitate or assist upper limb function, such as MIT-Manus [20], ARMin III [21], MIME [22], BI-MANU-TRACK [23], ARM Guide [24] and NeReBot [25]. In Brazil, the Laboratorio de Bioengenharia da Universidade Federal de Minas Gerais (LabBio-UFMG), located in Belo Horizonte/MG, developed a robotic orthosis for upper limb rehabilitation of post stroke individuals [26; 27]. Currently is desire the development of soft robots, made by tissue, or elastic polymers [28]. In this way, mechanical tendons or soft actuators act like a human tendon performing the exoskeleton actuation function, while the hand and fingers perform the strutural function [29]. These devices often use springs, cables, elastics, ropes or elastic wires, making the same fuction of artificial tendons, to transmit movement to the paralyzed muscles, through traction and relaxation of them. In the Exo-Glove [29] (Figure 1b) a Bowden cable, frequently used like a bicycle brake cable, was used to perform the artificial tendon function and control the fingers movement, your choice was due to a teflon coating which protects the steel cable. In the [PERSON] et al. [30; 31] work a Bowden cable was used to transmit de motor force to the artificial tendon, but in the first a Kevlar rope was used in the artificial tendon function and in the second another cable steel was used for this.