Eyes-Free Tongue Gesture and Tongue Joystick Control of a Five DOF Upper-Limb Exoskeleton for Severely Disabled Individuals

Abstract

Spinal cord injury can leave the affected individual severely disabled with a low level of independence and quality of life. Assistive upper-limb exoskeletons are one of the solutions that can enable an individual with tetraplegia (paralysis in both arms and legs) to perform simple activities of daily living by mobilizing the arm. Providing an efficient user interface that can provide full continuous control of such a device—safely and intuitively—with multiple degrees of freedom (DOFs) still remains a challenge. In this study, a control interface for an assistive upper-limb exoskeleton with five DOFs based on an intraoral tongue-computer interface (ITCI) for individuals with tetraplegia was proposed. Furthermore, we evaluated eyes-free use of the ITCI for the first time and compared two tongue-operated control methods, one based on tongue gestures and the other based on dynamic virtual buttons and a joystick-like control. Ten able-bodied participants tongue controlled the exoskeleton for a drinking task with and without visual feedback on a screen in three experimental sessions. As a baseline, the participants performed the drinking task with a standard gamepad. The results showed that it was possible to control the exoskeleton with the tongue even without visual feedback and to perform the drinking task at 65.1% of the speed of the gamepad. In a clinical case study, an individual with tetraplegia further succeeded to fully control the exoskeleton and perform the drinking task only 5.6% slower than the able-bodied group. This study demonstrated the first single-modal control interface that can enable individuals with complete tetraplegia to fully and continuously control a five-DOF upper limb exoskeleton and perform a drinking task after only 2 h of training. The interface was used both with and without visual feedback.

Adapting to progressive paralysis: A tongue-brain hybrid robot interface for individuals with amyotrophic lateral sclerosis

“…Similarly, an individual with tetraplegia managed to pick up objects within just 70s [10]. Tongue has also been used to control upper-limb exoskeletons [57] or wheelchairs [58], [59].…”

Computer Vision-Based Adaptive Semi-Autonomous Control of an Upper Limb Exoskeleton for Individuals with Tetraplegia

“…An upper limb exoskeleton is used, as several studies have successfully demonstrated how it can help restore some of the lost functionality for individuals with movement impairments in the arms [6,7]. Furthermore, the tongue-based interface has previously been shown to be an efficient and suitable interface for individuals with tetraplegia to control an exoskeleton [8,9]. Finally, a semi-autonomous control scheme assists the user in controlling the exoskeleton based on input from a computer vision module, which detects and analyzes nearby objects.…”

“…It offers high throughput, both in terms of the number of possible commands and also in terms of how fast they can be issued [16]. Furthermore, several studies have demonstrated that a tongue-based interface can be used by individuals with tetraplegia to control various assistive devices, such as an upper limb exoskeleton [8] or a robotic arm [17]. These considerations have led to the choice of a tongue-based interface.…”

Tongue control of a five-DOF upper-limb exoskeleton rehabilitates drinking and eating for individuals with severe disabilities

“…The intraoral tongue-computer interface (ITCI) introduced in Andreasen Struijk (2006) and enabled full control of a seven-DOF assistive robotic manipulator and a five-DOF ULE by means of tongue movements (Mohammadi et al, 2021b). Usually, an SCI does not affect the tongue motor functionality and its fine movement, which makes the tongue a suitable modality for a control interface (Chu et al, 2018;.…”

“…In a previous study (Mohammadi et al, 2021b), ten able-bodied individuals controlled the EXOTIC ULE with five DOFs using an adapted version of the commercially available ITCI, iTongue (TKS, Denmark). The interface provided continuous and full control of all five DOFs of the EXOTIC Exo in a single control mode both with and without visual feedback of the interface.…”