We propose a signal processing method that uses deep learning to estimate the absolute tag position directly from the raw channel impulse response (CIR) data. We use the CIR together with ground truth positional data to train a convolutional neural network (CNN) that not only estimates non-linearities in the signal propagation space but also analyzes the signal for multipath effects. Our evaluation shows that our position estimation works in multipath environments and also outperforms classical signal processing in line-of-sight situations.

This paper proposes evaluation criteria that consider algorithmic properties of ML-based positioning schemes and introduces a dataset from an indoor warehouse scenario to evaluate for them. Our dataset consists of images labeled with millimeter precise positions that allows for a better development and performance evaluation of learning algorithms. This allows an evaluation of machine learning algorithms for monocular optical positioning in a realistic indoor position application for the first time. We also show the feasibility of ML-based positioning schemes for an industrial deployment.

Pose tracking does not yet reliably work in large-scale interactive multi-user VR. Our novel head orientation estimation combines a single inertial sensor located at the user’s head with inaccurate positional tracking. We exploit that users tend to walk in their viewing direction and classify head and body motion to estimate heading drift. This enables low-cost long-time stable head orientation. We evaluate our method and show that we sustain immersion.

This paper studies the effects of head orientation drift around the yaw axis on the user’s absolute head and body orientations when walking naturally in the VR. We study how much drift accumulates over time, how a user experiences and tolerates it, and how a user applies strategies to compensate for larger drifts.

We propose a novel positioning system which uses the entities of visible light communication (VLC) system as anchors and tags. Our technique scales with the number of tags and the VLC network provides both positioning and communication capabilities. The anchor points transmit the OFDM-based VLC signals synchronously, and we estimate the time differences of arrival between anchor points and tags using positioning reference signals embedded into the air-interface of the VLC system. Simulation results show that positioning accuracy of 10 cm or better is possible for over 95% of users if the sampling clock offset is better that 10 ppm, clock jitter is below 1 ps, and a bit resolution of at least 16 bits is available.

We train recurrent neural networks on ToFs both in simulation and reality that successfully processes noisy measurements that are not zero-mean Gaussian distributed. We show that our methods outperforms conventional methods based on Kalman filters that are currently considered to be state of the art.

We propose a methodology for building control. A central part of our methodology is the control improvement (or optimisation) module, facilitating two simulation-based control improvement methodologies: one based in multi-criteria decision analysis methods and the other based on state-space identification of dynamical systems using Gaussian process models and reinforcement learning. We evaluate the proposed methodology in a set of simulation-based experiments using the thermal simulation model of a real building located in Portugal.

In this paper, a subspace-based approach to frequency-domain multipath resolution is presented. Resolution of multipath components allows for a RSS-based DOA estimation considering the power of the line of sight (LOS) component only. The impact of the multipath channel is considerably reduced with our approach. In contrast to common broadband DOA estimation techniques, the presented approach does not need phase-coherent receive channels or a synchronized sensor network. Hence, the proposed super-resolution technique is applicable to low-power sensor networks and brings accurate positioning to small-sized and energy-efficient sensor nodes.

Our novel yaw orientation estimation combines a single inertial sensor located at the human’s head with inaccurate positional tracking. We exploit that humans tend to walk in their viewing direction and that they also tolerate some orientation drift. We classify head and body motion and estimate heading drift to enable low-cost long-time stable head orientation in NP tracking on 100 m×100 m. Our evaluation shows that we estimate heading reasonably well.

Redirected Walking (RDW) manipulates a scene that is displayed to VR users so that they unknowingly compensate for scene motion and can thus explore a large virtual world on a limited space. So far, mostly visual manipulation techniques have been studied.
This paper shows that users can also be manipulated by means of acoustical signals. In an experiment with a dynamically moving audio source we see deviations of up to 30% from a 20 m long straight-line walk for male participants and of up to 25% for females. Static audio has about two thirds of this impact.

This work in progress report demonstrates a novel approach for behavioral augmentations in Virtual Reality (VR). Using a large scale tracking system, groups of five users explored a virtual museum. We investigated how augmenting social interactions impacts this experience, by designing behavioral transformations for behavioral phenomena in social interactions. Preliminary data indicate a reduction of perceived isolation, and a more thought-provoking experience with active behavioral augmentations.

Many satellite systems require knowledge about inter-satellite distances. Inter-satellite links provide direct connectivity between satellites and may be used for ranging, while they remove the need of dedicated hardware. This paper addresses inter-satellite ranging at the Low Earth Orbit (LEO) using S-Band signals. We take the requirements from recent missions and future applications into account and analyze the factors that limit ranging. We show how these factors affect the quality of distance estimation in terms of the Cramér-Rao Lower Bound for ranging. Two-way-ranging (TWR) provides the best accuracy and sustains the low-cost objective of small satellites. We further propose an enhanced TWR message exchange that enables on-the-fly delay calibration and sub-sample corrections. We implemented the transceiver modules on a Software-Defined Radio (SDR) platform and evaluated them with real-world data. The results show that the proposed ranging algorithm achieves an accuracy of few centimeters.

We present a concept for energy-efficient low-complexity localization based on Phase Difference of Arrival (PDoA). Besides a novel method for reference transmitter selection we propose a waveform, well-suited for PDoA measurements, and evaluate its ranging performance. We compare multiple signal classification (MUSIC), linear fitting, and mean phase difference and compare their estimation variance to the Cramer Rao Lower Bound (CRLB). Our system concept allows for the mitigation of near-far effects for reference and tag signals at the receiver nodes, and an efficient implementation of a wideband frequency hopping scheme.

We conducted an online survey among 227 athletes about the acceptance of virtual reality headsets for training in different kind of sport disciplines.