This paper presents the EXOTIC- a novel assistive upper limb exoskeleton for individuals with complete functional tetraplegia that provides an unprecedented level of versatility and control. The current literature on exoskeletons mainly focuses on the basic technical aspects of exoskeleton design and control while the context in which these exoskeletons should function is less or not prioritized even though it poses important technical requirements. We considered all sources of design requirements, from the basic technical functions to the real-world practical application. The EXOTIC features: (1) a compact, safe, wheelchair-mountable, easy to don and doff exoskeleton capable of facilitating multiple highly desired activities of daily living for individuals with tetraplegia; (2) a semi-automated computer vision guidance system that can be enabled by the user when relevant; (3) a tongue control interface allowing for full, volitional, and continuous control over all possible motions of the exoskeleton. The EXOTIC was tested on ten able-bodied individuals and three users with tetraplegia caused by spinal cord injury. During the tests the EXOTIC succeeded in fully assisting tasks such as drinking and picking up snacks, even for users with complete functional tetraplegia and the need for a ventilator. The users confirmed the usability of the EXOTIC.

This study assessed the ability of the tongue tip to accurately select intraoral targets embedded in an upper palatal tongue-computer interface, using 18 able-bodied volunteers. Four performance measures, based on modifications to Fitts's Law, were determined for three different tongue-computer interface layouts. The layouts differed with respect to number and location of the targets in the palatal interface. Assessment of intraoral target selection speed and accuracy revealed that performance was indeed dependent on the location and distance between the targets. Performances were faster and more accurate for targets located farther away from the base of the tongue in comparison to posterior and medial targets. A regression model was built, which predicted intraoral target selection time based on target location and movement amplitude better than the predicted by using a standard Fitts's Law model. A 30% improvement in the speed and accuracy over three daily practice sessions of 30 min emphasizes the remarkable motor learning abilities of the tongue musculature and provides further evidence that the tongue is useful for operating computer-interface technologies.

Assistive robotic arms have shown the potential to improve the quality of life of people with severe disabilities. However, a high performance and intuitive control interface for robots with 6-7 DOFs is still missing for these individuals. An inductive tongue computer interface (ITCI) was recently tested for control of robots and the study illustrated potential in this field. The paper describes the investigation of the possibility of developing a high performance tongue-based joystick-like controller for robots through two studies. The first compared different methods for mapping the 18 sensor signals to a 2D coordinate, as a touchpad. The second evaluated the performance of a novel approach for emulating an analog joystick by the ITCI based on the ISO9241-411 standard. Two subjects performed a multi-directional tapping test using a standard analog joystick, the ITCI system held in hand and operated by the other hand, and finally by tongue when mounted inside the mouth. Throughput was measured as the evaluation parameter. The results show that the contact on the touchpads can be localized by almost 1 mm accuracy. The effective throughput of ITCI system for the multi-directional tapping test was 2.03 bps while keeping it in the hand and 1.31 bps when using it inside the mouth.

High level spinal cord injury drastically reduces the quality of life of the injured person. Various systems attempted to interface the still intact or residual abilities following injury in various monomodal or multimodal designs to compensate for the highly affected mobility. An intra-oral inductive tongue computer interface (ITCI) has been designed to provide real-time discrete and proportional control for computers and assistive devices and to meet specific requirements for individuals with tetraplegia. Operation of the ITCI for wheelchair control was demonstrated with two participants with tetraplegia in a short-term training study. Additionally, two non-disabled individuals participated in the study. For each participant, the ability to drive a Permobil C500 with the ITCI was compared to that when driving the wheelchair with joystick (mouth-stick in one case) along two different lanes of 39 m, by reporting the speed along the lanes and the number of obstacles hit. The lanes consisted of 90°, 360°, and complex maneuver segments linked by linear segments. The ITCI featured a mouthpiece encapsulating two pads of inductive sensors, driving electronics, and battery. The mouthpiece was attached to the palate of the participant’s oral cavity with dental retainers. A piercing-like activation unit was attached to the tongue. Data were transmitted wirelessly to a central unit that controlled the wheelchair through wired interface. Among all participants, mean speeds along lane A or B reached maximal values between 0.42 and 0.74 m/s when driving with the ITCI, representing 41 to 71% of that obtained when driving with the joystick.

Background: A system providing disabled persons with control of various assistive devices with the tongue has been developed at Aalborg University in Denmark. The system requires an activation unit attached to the tongue with a small piercing. The aim of this study was to establish and evaluate a safe and tolerable procedure for medical tongue piercing and to evaluate the expected and perceived procedural discomfort. Methods: Four tetraplegic subjects volunteered for the study. A surgical protocol for a safe insertion of a tongue barbell piercing was presented using sterilized instruments and piercing parts. Moreover, post-procedural observations of participant complications such as bleeding, edema, and infection were recorded. Finally, procedural discomforts were monitored by VAS scores of pain, changes in taste and speech as well as problems related to hitting the teeth. Results: The piercings were all successfully inserted in less than 5 min and the pain level was moderate compared with oral injections. No bleeding, infection, embedding of the piercing, or tooth/gingival injuries were encountered; a moderate edema was found in one case without affecting the speech. In two cases the piercing rod later had to be replaced by a shorter rod, because participants complained that the rod hit their teeth. The replacements prevented further problems. Moreover, loosening of balls was encountered, which could be prevented with the addition of dental glue. No cases of swallowing or aspiration of the piercing parts were recorded. Conclusions: The procedure proved simple, fast, and safe for insertion of tongue piercings for tetraplegic subjects in a clinical setting. The procedure represented several precautions in order to avoid risks in these susceptible participants with possible co-morbidity. No serious complications were encountered, and the procedure was found tolerable to the participants. The procedure may be used in future studies with tongue piercings being a prerequisite for similar systems, and this may include insertion in an out-patient setting.

It is crucial to increase the independence of severely disabled individuals. Assistive robotics can aid in the desired activities of daily living, including tasks requiring remote performance e.g. grasping remote objects, turning switches on/off, and opening/closing doors. The robot control is compromised by the lack of efficient interfaces for individuals with disabilities and the lack of depth perception. This paper addresses these challenges by presenting the development and evaluation of efficient tongue-based robot interfaces and low-level robot control schemes targeting tele-robotic control through a 2D display. Ten able-bodied participants were successful in completing ten rounds of controlling a JACO robot to perform a pouring water task, using five different control methods, under 2D or 3D visual feedback. The tool-frame based tongue interface layout, L2_TF (with emulated joystick, mode switch button and a “GO” button) improved the 2D visual guided control of the JACO robot compared with the other tongue control methods. The mean trajectory length of completing the task using L2_TF was 3% longer compared with the standard joystick when controlling through 2D. The trajectory length for reaching and grabbing a bottle was shortest for L2_TF compared with all other control methods, including the joystick. The iTongue control layouts performed well in gripping time, showing no significant difference between 2D and 3D. The transition from 2D to 3D resulted in a mean decrease of 27.7% for task completion time across all interfaces. L2_TF and the joystick had the strongest and most similar robustness to the transition between 3D and 2D.