Minimally assistive robot training for proprioception enhancement

Abstract

In stroke survivors, motor impairment is frequently associated with degraded proprioceptive and/or somatosensory functions. Here we address the question of how to use robots to improve proprioception in these patients. We used an 'assist-as-needed' protocol, in which robot assistance was kept to a minimum and was continuously adjusted during exercise. To specifically train proprioceptive functions, we alternated blocks of trials with and without vision. A total of nine chronic stroke survivors participated in the study, which consisted of a total of ten 1-h exercise sessions. We used a linear mixed-effects statistical model to account for the effects of exercise, vision and the degree of assistance on the overall performance, and to capture both the systematic effects and the individual variations. Although there was not always a complete recovery of autonomous movements, all subjects exhibited an increased amount of voluntary control. Moreover, training with closed eyes appeared to be beneficial for patients with abnormal proprioception. Our results indicate that training by alternating vision and no-vision blocks may improve the ability to use proprioception as well as the ability to integrate it with vision. We suggest that the approach may be useful in the more general case of motor skill acquisition, in which enhancing proprioception may improve the ability to physically interact with the external world.

Potential of robots as next-generation technology for clinical assessment of neurological disorders and upper-limb therapy

“…Some studies have combined functional electrical stimulation [108][109] or transcranial magnetic stimulation [110] with robotic therapy in attempts to improve outcomes. One study has examined trying to improve proprioception following stroke [111].…”

Arm Stiffness During Assisted Movement After Stroke: The Influence of Visual Feedback and Training

“…The task was designed according to the Bobath concept and aimed to facilitate the active execution of outward movements of large amplitude [19]. Subjects had to hit a set of targets arranged on three layers: proximal (A), intermediate (B) and distal (C) with respect to the shoulder joint (see Fig.…”

“…Impedance is influenced by a number of factors, such as task, loading conditions, sensory feedback, adaptation and learning. In stroke survivors, damaged sensorimotor integration is an additional contributor to motor impairment and may influence arm stiffness modulation, as suggested by a recent work [19] in which subjects with a high Modified Ashworth Score (MAS) found it easier to control the arm without visual feedback (VF). The clinical scales used to assess the degree of spasticity following stroke, including the most popular, the MAS [20], require a certain degree of subjective judgment.…”

“…The goal of this paper is to assess to what extent integrating an evaluation of arm stiffness into a robotic rehabilitation protocol for stroke survivors can aid in understanding the main factors that influence functional recovery and how factors such as exercise, sensory feedback, and assistive force influence its modulation. The proposed method was validated using a calibrated rig and was then tested on the data collected from a pilot study [19] whose protocol was ideally suited for the novel measuring method because a single disturbance was part of the robot assistance mechanism. An additional validation of the single-perturbation method was carried out by comparing its estimates with those obtained with the classical multiple-perturbations method.…”

“…The protocol used in the pilot robot-therapy study [19] included trials with different levels of assistive force with and without visual feedback. The assistive force, modulated based on performance, was switched off as soon as a subject reached the current target.…”