Franz-Erich Wolter

Andreas Tarnowsky, Jan Jamaszyk, Daniel Brandes et al.

Tactile displays have a wide potential field of applications, ranging from enhancing Virtual-Reality scenarios up to aiding telesurgery as well as in fundamental psychological and neurophysiological research. In this paper, we describe an open source hardware and software architecture that is designed to drive a variety of different tactile displays. For demonstration purposes, a tactile computer mouse featuring a simple tactile display, based on lateral piezoelectric (PZT) actuators, is presented. Even though we will focus on driving mechanical actuators in this paper, the system can be extended to different working principles. The suggested architecture is supplied with a custom, easy to use, software stack allowing a simple definition of tactile scenarios as well as user studies while being especially tailored to non-computer scientists. By releasing the OpenTactile system under MIT license we hope to ease the burden of controlling tactile displays as well as designing and reproducing the related experiments.

Qirui Zheng, Dan Wu, Franz-Erich Wolter et al.

The widespread adoption of renewable energy poses a challenge in maintaining a feasible operating point in highly variable scenarios. This paper demonstrates that, within a feasible region of a power system that meets practical stability requirements, the power flow equations define a smooth bijection between nodal voltage phasors (angle and magnitude) and nodal active/reactive power injections. Based on this theoretical foundation, this paper proposes a data-based power flow evaluation method that can imply the associated power flow manifold from a limited number of data points around a single operating point. Using techniques from differential geometry and analytic functions, we represent geodesic curves in the associated power flow manifold as analytic functions at the initial point. Then, a special algebraic structure of the power flow problem is revealed and applied to reduce the computation of all higher-order partial derivatives to that of the first-order ones. Integrating these techniques yields the proposed data-based evaluation method, suggesting that a small number of local measurements around a single operating point is sufficient to imply the entire associated power flow manifold. Numerical cases with arbitrary directional variations are tested, certifying the efficacy of the proposed method.