When vestibular sense organs suffer damage functional problems arise such as imbalance and falls as well as difficulty with gaze control, resulting in blurred vision, dizziness and feelings of disorientation. A novel computer-based rehabilitation program has been developed. Using the Gyration TM motion-sense mouse, attached to a headband, to control computer applications and games, the participants were able to interact with targets in computer games through head motion, allowing different gaze exercises to be carried out. Balance exercises can be incorporated simultaneously and progressively into the rehabilitation program. The main findings of this study revealed that using head rotation to interact with computer games coupled with demanding balance conditions resulted in substantial improvements in gaze control, standing balance and walking performance. These observations provide support that a low-cost home computer-gaming rehabilitation program is well suited to train gaze control through active and passive head motion and to concomitantly train standing balance.

When vestibular sense organs suffer damage functional problems arise such as imbalance and falls as well as difficulty with gaze control, resulting in blurred vision, dizziness and feelings of disorientation. A novel computer-based rehabilitation program has been developed. Using the Gyration TM motion-sense mouse, attached to a headband, to control computer applications and games, the participants were able to interact with targets in computer games through head motion, allowing different gaze exercises to be carried out. Balance exercises can be incorporated simultaneously and progressively into the rehabilitation program. The main findings of this study revealed that using head rotation to interact with computer games coupled with demanding balance conditions resulted in substantial improvements in gaze control, standing balance and walking performance. These observations provide support that a low-cost home computer-gaming rehabilitation program is well suited to train gaze control through active and passive head motion and to concomitantly train standing balance.

Undesirable landing area (e. g. , a hole, a fragment of glass, a water puddle, etc) creates the necessity for an alternate foot placement planning and execution. Previous study has proposed that three determinants are used by the central nervous system (CNS) for planning an alternate foot placement: minimum foot displacement, stability and maintenance of forward progression. However, validation of these determinants is lacking. Therefore, the general purpose of the series of studies presented here is to validate and test the generality of the decision algorithm of alternate foot placement selection developed previously. The first study was designed to validate the use of a virtual planar obstacle paradigm and the economy assumption behind minimum foot displacement determinant. Participants performed two blocks of trials. In one block, they were instructed to avoid stepping in a virtual planar obstacle projected in the screen of a LCD monitor embedded in the ground. In another block, they were instructed to avoid stepping in a real hole present in walkway. Behavioral response was unaffected by the presence of a real hole. In addition, it was suggested that minimum foot displacement results in minimum changes in EMG activity which validates the economy determinant. The second study was proposed to validate the stability determinant. Participants performed an avoidance task under two conditions: free and forced. In the free condition participants freely chose where to land in order to avoid stepping in a virtual obstacle. In the forced condition, a green arrow was projected over the obstacle indicating the direction of the alternate foot placement. The data from the free condition was used to determine the preferred alternate foot placement whereas the data from the forced condition was used to assess whole body stability. It was found that long and lateral foot placements are preferred because they result in a more stable behavior. The third study was designed to validate the alternate foot placement model in a more complex terrain. Participants were required to avoid stepping in two virtual planar obstacles placed in sequence. It was found that participants used the strategy of planning the avoidance movement globally and additional determinants were used. One of the additional determinants was implementation feasibility. In the third study, gaze behavior was also monitored and two behaviors emerged from this data. One sub-group of participants fixated on the area stepped during adaptive step, whereas another sub-group anchor their gaze in a spot ahead of the area-to-be avoided and used peripheral vision for controlling foot landing. In summary, this thesis validates the three determinants for the alternate foot placement planning model and extends the previous model to more complex terrains.

This thesis describes the development of a robotic platform for evaluation of gaze stabilization algorithms built for the Sensorimotor Systems Laboratory at the University of British Columbia. The primary focus of the work was to measure the performance of a biomimetic vestibulo-ocular reflex controller for gaze stabilization using cerebellar feedback. A flexible robotic system was designed and built in order to run reproducible test sequences at high speeds featuring three dimensional linear movement and rotation around the vertical axis. On top of the robot head a 1 DOF camera head can be independently controlled by a stabilization algorithm implemented in Simulink. Vestibular input is provided by a 3-axis accelerometer and a 3-axis gyroscope. The video feed from the camera head is fed into a workstation computer running a custom image processing program which evaluates both the absolute and relative movement of the images in the sequence. The absolute angles of tracked regions in the image are continuously returned, as well as the movement of the image sequence across the sensor in full 3 DOF camera rotation. Due to dynamic downsampling and noise suppression algorithms very good performance was reached, enabling retinal slip estimation at 720 degrees per second. Two different controllers were implemented, one adaptive open loop controller similar to Dean et al.’s work[12] and one reference implementation using closed loop control and optimal linear estimation of reference angles. A sequence of tests were run in order to evaluate the performance of the two algorithms. The adaptive controller was shown to offer superior performance, dramatically reducing the movement of the image for all test sequences, while also offering better performance as it was tuned over time.

Undesirable landing area (e. g. , a hole, a fragment of glass, a water puddle, etc) creates the necessity for an alternate foot placement planning and execution. Previous study has proposed that three determinants are used by the central nervous system (CNS) for planning an alternate foot placement: minimum foot displacement, stability and maintenance of forward progression. However, validation of these determinants is lacking. Therefore, the general purpose of the series of studies presented here is to validate and test the generality of the decision algorithm of alternate foot placement selection developed previously. The first study was designed to validate the use of a virtual planar obstacle paradigm and the economy assumption behind minimum foot displacement determinant. Participants performed two blocks of trials. In one block, they were instructed to avoid stepping in a virtual planar obstacle projected in the screen of a LCD monitor embedded in the ground. In another block, they were instructed to avoid stepping in a real hole present in walkway. Behavioral response was unaffected by the presence of a real hole. In addition, it was suggested that minimum foot displacement results in minimum changes in EMG activity which validates the economy determinant. The second study was proposed to validate the stability determinant. Participants performed an avoidance task under two conditions: free and forced. In the free condition participants freely chose where to land in order to avoid stepping in a virtual obstacle. In the forced condition, a green arrow was projected over the obstacle indicating the direction of the alternate foot placement. The data from the free condition was used to determine the preferred alternate foot placement whereas the data from the forced condition was used to assess whole body stability. It was found that long and lateral foot placements are preferred because they result in a more stable behavior. The third study was designed to validate the alternate foot placement model in a more complex terrain. Participants were required to avoid stepping in two virtual planar obstacles placed in sequence. It was found that participants used the strategy of planning the avoidance movement globally and additional determinants were used. One of the additional determinants was implementation feasibility. In the third study, gaze behavior was also monitored and two behaviors emerged from this data. One sub-group of participants fixated on the area stepped during adaptive step, whereas another sub-group anchor their gaze in a spot ahead of the area-to-be avoided and used peripheral vision for controlling foot landing. In summary, this thesis validates the three determinants for the alternate foot placement planning model and extends the previous model to more complex terrains.

Aim: The aim of the thesis was to investigate the impact of gaze-based assistive technology on daily activities in children with severe physical impairments and without speech. The objectives were to develop and pilot a gaze-based assistive technology intervention (GAT intervention) at home and in school for these children and to understand its impact on daily activities as experienced by their parents. Methods: Study I was a pilot study in which the basic components that were developed for the intervention were evaluated for students with physical impairments. The study aimed at improving the use of computers as assistive technology (AT) in school. Based on the findings in Study I, the GAT intervention was developed. The GAT intervention aimed at implementing gaze-based AT in daily activities. It consisted of two parts; having access to gaze-based AT and having access to services from a multi professional communication team during nine to ten months. Studies II-IV concerned gazebased AT for children with severe physical impairments without speech who participated in the GAT intervention. The participants were ten children (ages 1-15) (Studies II, III), and their parents (Study IV). Studies II and III had longitudinal designs and children were followed during 15-20 months with repeated measurements before, after and at follow-up. In Study II children’s repertoire of computer activities, extent of use, and goal attainment with gaze-based AT was evaluated, as well as parents’ satisfaction with the AT and with services. In Study III children’s eye gaze performance when using gaze-based AT was examined. In Study IV, parents were interviewed twice with the aim of  exploring their experiences of children’s gaze-based AT use in daily life. In Study IV a hermeneutical approach was used. Results: The findings of Study I showed that the basic components of intervention improved the use of computers in school. Study II showed an increased repertoire of computer activities with the gazebased AT, maintained use in daily activities for all at follow up, and that all children attained goals for gaze-based AT use in daily activities. Parents were satisfied with the gaze-based AT, and with the services in the GAT intervention. In study III, nine children improved in eye gaze performance over time when using the gaze-based AT in daily activities. Study IV revealed that children’s gaze-based AT usage in daily activities made a difference to parents since the children demonstrated agency, and showed their personality and competencies by using gaze-based AT, and for the parents this opened up infinite possibilities for the child to do and learn things. Overall, children’s gaze-based AT usage provided parents with hope of a future in which their children could develop and have influence in life. Conclusions: This thesis shows that these children with severe physical impairments and without speech acquired sufficient gaze control skills to use gaze-based AT for daily activities in the home and at school. The gaze-based AT had a positive impact on performing activities, for example, play activities and communication- and interaction-related activities. For the parents, children’s gaze-based AT usage made a difference since it shaped a hope of a better future for their children, where they can develop and gain influence in their future life. Furthermore, the children continued to perform daily activities with gaze-based AT over time. This finding suggests that key persons were provided with sufficient knowledge and skills to support children in maintained use of gaze-based AT after withdrawal of the services provided in the GAT intervention.

Whether we want to drive a car, play a ball game, or even enjoy watching a flying bird, we need to track moving objects. This is possible via smooth pursuit eye movements (SPEMs), which maintain the image of the moving object on the fovea (i.e., a very small portion of the retina with high visual resolution). At first glance, performing an accurate SPEM by the brain may seem trivial. However, imperfect visual coding, processing and transmission delays, wide variety of object sizes, and background textures make the task challenging. Furthermore, the existence of distractors in the environment makes it even more complicated and it is no wonder why understanding SPEM has been a classic question of human motor control. To understand physiological systems of which SPEM is an example, creation of models has played an influential role. Models make quantitative predictions that can be tested in experiments. Therefore, modelling SPEM is not only valuable to learn neurobiological mechanisms of smooth pursuit or more generally gaze control but also beneficial to give insight into other sensory-motor functions. In this thesis, I present a neurocomputational SPEM model based on Neural Engineering Framework (NEF) to drive an eye-like robot. The model interacts with the real world in real time. It uses naturalistic images as input and by the use of spiking model neurons controls the robot. This work can be the first step towards more thorough validation of abstract SPEM control models. Besides, it is a small step toward neural models that drive robots to accomplish more intricate sensory-motor tasks such as reaching and grasping.

This master thesis is done at CrossControl, a company in the automation industry. A literature review was done covering state of the art technology of eye-tracking and gaze control and how it can be used in the automation industry. One purpose with the study was to indentify features important for an eye-tracker in automation applications. Findings suggests that there are no standard methods for measuring the performance of trackers and further that performance in regard to gaze control is limited by physiology of the eye rather than limitations of the devices. The differences between trackers are found in robustness when it comes to differences in people or conditions in the environment. A prototype was made for demonstration. The prototype was built on equipment used in the industry combined with an eye-tracker from Tobii. A library, where coordinates from the eye-tracker were used to indicate what object in the interface was gazed upon, was implemented and used to demonstrate concepts such as buttons outside the screen activated by gaze.

Eye tracking technology has made it possible to accurately and consistently track a users gaze position on a screen. The human eyes center of focus, where it can see the most detailed information, is quite small at a given moment. The peripheral vision of humans have a much lower level of details than the center of gaze. Knowing this, it is possible to display a view that increases the level of resolution at the position of the users gaze point on the screen, while the rest of the screen keeps a lower resolution. An implementation of such a system can generate a representation of data with both detail and overview. The results indicate that even with simple gaze data processing it is possible to use gaze control to help explore details of a high resolution image. Gaze data processing often involve a compromise between stability, responsiveness and latency. A low latency, highly responsive gaze data filter would increase the risk for lens oscillation, and demand a higher concentration level from the viewer then a slower filter would. Applying a gaze data filter that allowed for smooth and stable lens movement for small saccades and responsive movements for large saccades proved successfully. With the uses of gaze control the user might be able to use a gaze aware application more efficient since gaze precedes actions. Gaze control would also reduce the need for hand motions which could provide a improved work environment for people interacting with computer.

Aim: The aim of the thesis was to investigate the impact of gaze-based assistive technology on daily activities in children with severe physical impairments and without speech. The objectives were to develop and pilot a gaze-based assistive technology intervention (GAT intervention) at home and in school for these children and to understand its impact on daily activities as experienced by their parents. Methods: Study I was a pilot study in which the basic components that were developed for the intervention were evaluated for students with physical impairments. The study aimed at improving the use of computers as assistive technology (AT) in school. Based on the findings in Study I, the GAT intervention was developed. The GAT intervention aimed at implementing gaze-based AT in daily activities. It consisted of two parts; having access to gaze-based AT and having access to services from a multi professional communication team during nine to ten months. Studies II-IV concerned gazebased AT for children with severe physical impairments without speech who participated in the GAT intervention. The participants were ten children (ages 1-15) (Studies II, III), and their parents (Study IV). Studies II and III had longitudinal designs and children were followed during 15-20 months with repeated measurements before, after and at follow-up. In Study II children’s repertoire of computer activities, extent of use, and goal attainment with gaze-based AT was evaluated, as well as parents’ satisfaction with the AT and with services. In Study III children’s eye gaze performance when using gaze-based AT was examined. In Study IV, parents were interviewed twice with the aim of  exploring their experiences of children’s gaze-based AT use in daily life. In Study IV a hermeneutical approach was used. Results: The findings of Study I showed that the basic components of intervention improved the use of computers in school. Study II showed an increased repertoire of computer activities with the gazebased AT, maintained use in daily activities for all at follow up, and that all children attained goals for gaze-based AT use in daily activities. Parents were satisfied with the gaze-based AT, and with the services in the GAT intervention. In study III, nine children improved in eye gaze performance over time when using the gaze-based AT in daily activities. Study IV revealed that children’s gaze-based AT usage in daily activities made a difference to parents since the children demonstrated agency, and showed their personality and competencies by using gaze-based AT, and for the parents this opened up infinite possibilities for the child to do and learn things. Overall, children’s gaze-based AT usage provided parents with hope of a future in which their children could develop and have influence in life. Conclusions: This thesis shows that these children with severe physical impairments and without speech acquired sufficient gaze control skills to use gaze-based AT for daily activities in the home and at school. The gaze-based AT had a positive impact on performing activities, for example, play activities and communication- and interaction-related activities. For the parents, children’s gaze-based AT usage made a difference since it shaped a hope of a better future for their children, where they can develop and gain influence in their future life. Furthermore, the children continued to perform daily activities with gaze-based AT over time. This finding suggests that key persons were provided with sufficient knowledge and skills to support children in maintained use of gaze-based AT after withdrawal of the services provided in the GAT intervention.