Existing position controllers for VTOL UAVs require measurements of the system attitude (orientation) for feedback. However, in practice the orientation cannot be measured directly; it is rather obtained through the use of an attitude observer relying on a set of inertial vector measurements. In this paper a new control strategy is proposed for VTOL-UAVs which avoids the direct measurement of t...

The QUEST measurement noise model for unit vector observations has been widely used in spacecraft attitude estimation for more than twenty years. It was derived under the approximation that the noise lies in the tangent plane of the respective unit vector and is axially symmetrically distributed about the vector. For large field-of-view sensors, however, this approximation may be poor, especial...

The star sensor has been widely used as an important and accurate attitude measurement sensor in classical satellite attitude determination systems. This paper analyses the influence of star sensor’s sampling frequency on attitude determination accuracy within an Extended Kalman filter (EKF). Simulations are used to validate the theoretical analysis and determine the parameters of the influence...

This paper describes a method for correcting the dynamically induced bias errors in wind tunnel model att i tude measurements using measured modal properties of the model system. At NASA Langley Research Center, the predominant instrumentation used to measure model attitude is a servo-accelerometer device that senses the model attitude with respect to the local vertical. Under smooth wind tunne...

User Experience (UX), as a recently established research area, is still haunted by the challenges of defining the scope of UX in general and operationalising experiential qualities in particular. To explore the basic question whether UX constructs are measurable, we conducted semi-structured interviews with ten UX researchers from academia and one UX practitioner from industry where a set of qu...

An important feature of questionnaire validation is reliability. To be able to measure a given concept by questionnaire validly, the reliability needs to be high. The objectives of this study were to examine reliability of attitude and knowledge and behavioral consistency of sunburn in a developed questionnaire for monitoring and evaluating population sun-related behavior. Sun related behavior,...

This article reviews the purchase behaviour of consumers for plants and the attitude towards horticultural novelties. The palm, Trachycarpus wagnerianus especially, is the main focus of this study. Based on a survey of 408 customers in Bavaria during autumn 2009, the results gave an impression of how consumers inform themselves about novelties in horticulture as well as, their attitude to T. wa...

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