Collaborative music interaction on tabletops: an HCI approach

With the advent of tabletop interaction, collaborative activities are better supported than they are on single-user PCs because there exists a physical shareable space, and interaction with digital data is more embodied and social. In sound and music computing, collaborative music making has traditionally been done using interconnected networks, but using separated computers. Musical tabletops introduce opportunities of playing in collaboration through sharing physically the same musical interface. However, few tabletop musical interfaces exploit this collaborative potential (e.g. the Reactable). We are interested in looking into how collaboration can be fully supported by means of musical tabletops for music performance in contrast with more traditional settings. We are also looking at whether collective musical engagement can be enhanced by providing more suitable interfaces to collaboration. In HCI and software development, we find an iterative process approach of design and evaluation—where evaluation allows us to identify key issues that can be addressed in the next design iteration of the system. Using a similar iterative approach, we plan to design and evaluate some tabletop musical interfaces. The aim is to understand what design choices can enhance and enrich collaboration and collective musical engagement on these systems. In this paper, we explain the evaluation methodologies we have undertaken in three preliminary pilot studies, and the lessons we have learned. Initial findings indicate that evaluating tabletop musical interfaces is a complex endeavour which requires an approach as close as possible to a real context, with an interdisciplinary approach provided by interaction analysis techniques

Position estimation delays in signal injection-based sensorless PMSM drives

The causes of position estimation delays and their effects on the sensorless control of permanent magnet synchronous motor drives are investigated. The position of a permanent magnet synchronous machine is estimated via the injection of high frequency voltage signals. The delays under investigation are due to the digital implementation of the control algorithm and to the digital filters adopted for decoupling the inspection signals from the fundamental components of the stator current measures. If not correctly modeled and compensated, such delays can reduce the performance of the control scheme. Experimental results are provided, proving the accuracy of the modeling approach and the effectiveness of the related compensation strateg

Position determination systems

A system for an orbital antenna, operated at a synchronous altitude, to scan an area of a celestial body is disclosed. The antenna means comprises modules which are operated by a steering signal in a repetitive function for providing a scanning beam over the area. The scanning covers the entire area in a pattern and the azimuth of the scanning beam is transmitted to a control station on the celestial body simultaneous with signals from an activated ground beacon on the celestial body. The azimuth of the control station relative to the antenna is known and the location of the ground beacon is readily determined from the azimuth determinations

Aircraft control position indicator

An aircraft control position indicator was provided that displayed the degree of deflection of the primary flight control surfaces and the manner in which the aircraft responded. The display included a vertical elevator dot/bar graph meter display for indication whether the aircraft will pitch up or down, a horizontal aileron dot/bar graph meter display for indicating whether the aircraft will roll to the left or to the right, and a horizontal dot/bar graph meter display for indicating whether the aircraft will turn left or right. The vertical and horizontal display or displays intersect to form an up/down, left/right type display. Internal electronic display driver means received signals from transducers measuring the control surface deflections and determined the position of the meter indicators on each dot/bar graph meter display. The device allows readability at a glance, easy visual perception in sunlight or shade, near-zero lag in displaying flight control position, and is not affected by gravitational or centrifugal forces

X-ray position detector

An X-ray position detector for real time operation is described. A set of proportional counters is arranged into an array which can detect and indicate the position of an X-ray interaction within the array, in the X Y plane