Upper-Limb Robotic Exoskeletons for Neurorehabilitation: A Review on Control Strategies

Abstract

Since the late 1990s, there has been a burst of research on robotic devices for poststroke rehabilitation. Robot-mediated therapy produced improvements on recovery of motor capacity; however, so far, the use of robots has not shown qualitative benefit over classical therapist-led training sessions, performed on the same quantity of movements. Multidegree-of-freedom robots, like the modern upper-limb exoskeletons, enable a distributed interaction on the whole assisted limb and can exploit a large amount of sensory feedback data, potentially providing new capabilities within standard rehabilitation sessions. Surprisingly, most publications in the field of exoskeletons focused only on mechatronic design of the devices, while little details were given to the control aspects. On the contrary, we believe a paramount aspect for robots potentiality lies on the control side. Therefore, the aim of this review is to provide a taxonomy of currently available control strategies for exoskeletons for neurorehabilitation, in order to formulate appropriate questions toward the development of innovative and improved control strategies.

Interaction force and motion estimators facilitating impedance control of the upper limb rehabilitation robot

“…As a result, many robots for both upper [4], [5] and lower limb rehabilitation [6], [7] have been proposed in the last decade.…”

Impedance Control of a Pneumatic Muscles-Driven Ankle Rehabilitation Robot

“…The robot is also equipped with displacement sensors and force sensors to measure the position and force information of three pneumatic muscle actuators during operation. The impedance controller is comprised of an inlayer position control unit and an outlayer impedance control unit [11]. In this paper, the ankle rehabilitation robot only installs the force sensors in each pneumatic muscle, the interaction force between the robot and the external environment can be reflected by the force in joint space.…”

“…However, when the pneumatic muscle interacts with the outside world and drives the robot to move, the interaction force e f must be considered, which can be measured by the force sensor of each driven joint. In the process of impedance control, the pneumatic muscle and the external environment are regarded as one system [16]. The main function of the position based on impedance model is to convert the force error to the position correction f x .…”

Brain-machine Interface in Robot-assisted Neurorehabilitation for Patients with Stroke and Upper Extremity Weakness – the Therapeutic Turning Point

“…In case that the natural movement was achieved, exoskeleton type should give more potential adjustment points to the human body. Introduction for the body motion and the types of robots are explained in other reviews [28,29].…”