Stephan Pölzer

Estimating Interval Process Models for Type 1 Diabetes for Robust Control Design

Abstract A linear transfer function model comprising 4 parameters is used to describe the post-prandial breakfast excursions of a group of 10 type 1 diabetes patients who are treated with multiple daily insulin injections. The model is able to simulate the glucose concentration in blood and uses the information of carbohydrate content of the breakfast and the administered insulin injections as inputs. Additionally, a measurement of the actual blood glucose concentration at the time when the breakfast occurs is required. No additional information, in particular the use of a continuous glucose monitoring system is necessary. Based on a 3 day observational period, parameter intervals are calculated such that the measured glucose responses are inside the bounds given by the output of the model. The model together with the parameter intervals can be used for robust control design.

Direct continuous time system identification of MISO transfer function models applied to type 1 diabetes

This paper shows an application of continuous time system identification methods to Type 1 diabetes. First, a general MISO transfer function structure with individual nominator and denominator polynomials for each input is assumed and a parameter estimation procedure via an iterative prediction error method presented. Then, the proposed identification method is evaluated on a simple simulation example and finally applied on real-life data from Type 1 diabetes patients with the purpose of modeling blood glucose dynamics. To this aim, the method was extended to consider the time-varying nature of the system.

Accessibility of Brainstorming Sessions for Blind People

Today, research focuses on the accessibility of explicit information for blind users. This gives only partly access to the information flow in brain-storming sessions, since non-verbal communication is not supported. Advances in ICT however allow capturing implicit information like hand gestures as important part of non-verbal communication. Thus, we describe a system that al-lows integrating blind people into a brainstorming session using a mind map.

Presenting Non-verbal Communication to Blind Users in Brainstorming Sessions

In co-located meetings, which are part of our professional and educational lives, information exchange relies not only on information exchange using artifacts like bubbles in mind-maps or equations presented on electronic whiteboards in classrooms, but also to a large extent on non-verbal communication. In the past much effort was done to make the artifact level accessible but also non-verbal communication heavily relies on the visual channel to which blind people do not have access. Thereby co-located meetings are seen as first domain to research accessibility of non-verbal communication, which are well defined and should lead to more general research on access to non-verbal communication. We present a first prototypical system which allows experimenting with access to non-verbal communication elements by blind people using both the input from a ”human” transcriber or automatic tracking and recognition of non-verbal communication cues.

Virtual Braille-Keyboard in Co-located Meetings

Our daily live is no longer imaginable without touch devices. Besides standard touch devices as mobile phones and tablets also touch-tables have the chance to find their way into our daily lives. Co-located meetings can be seen as a good application area for touch-tables. They can present the artifact information layer to the whole group. On touch surfaces virtual keyboards are used by sighted people for text input and text manipulations. For blind people, such keyboards are only accessible with a decreased working speed. In co-located meetings, manipulation of artifacts (for instance bubbles of mind-maps) is very dynamic. Therefore, a decreased working speed to generate and manipulate textual inputs makes an equal participation of blind people in co-located meetings impossible. The ongoing work is concerned with the development of a virtual Braille-keyboard to allow a better integration of blind users into co-located meetings.

Assisting people with Nystagmus through image stabilization: Using an ARX model to overcome processing delays

Pathological Nystagmus is characterized by an unintended and involuntary eye-movement, which tends to impact on visual acuity. Today only view therapies (for instance medication or surgeries) to treat nystagmus are at hand and the existing therapies only show partial improvement. Only general Assistive Technology (AT) solutions like glasses, screen magnifiers, speech output, display adaptation and concepts holders are at hand to support daily living. More specific ATs to reduce the impact of nystagmus are missing. This paper presents conceptual research and feasibility studies with the attempt to reduce the impact of nystagmus by stabilizing the image on the retina (digital Retinal Image Stabilization) by moving the digital image synchronal with the unintended eye movement using gaze contingent display technology. Further an identification and validation process using recorded eye-movements is presented since the synchronization approach relies on predicting eye-movements to reduce the impact of delays due to processing time.

Making Tabletop Interaction Accessible for Blind Users

Tabletop systems and their interaction capabilities are typically a domain for sighted people only. While the content on the tabletop can already be made accessible to blind people, the interaction above the tabletop is still inaccessible. This paper describes our approach towards making the above tabletop interaction accessible to blind people by using LEAP sensors and speech recognition.

Gaze Based Magnification to Assist Visually Impaired Persons

Screen magnifiers are one of the core tools to assist people with visual impairments in accessing digital content. We introduce an approach to minimize interaction requirements by magnifying at the fixation point/area which is identified using eye tracking. Screen magnifiers mostly use the cursor to define the magnification area and ask for configuring when and how to magnify. This paper presents a modular design of a gaze based magnification tool reducing interaction tasks and thereby also supporting a good overview of the content and thereby showing potential to improve usability. Modularization supports an easy integration of filtering and personalization techniques to support adjustment of gaze based magnification to unusual eye-movements as e.g. nystagmus.