Alexander Scheel

Multiple Extended Target Tracking With Labeled Random Finite Sets

Targets that generate multiple measurements at a given instant in time are commonly known as extended targets. These present a challenge for many tracking algorithms, as they violate one of the key assumptions of the standard measurement model. In this paper, a new algorithm is proposed for tracking multiple extended targets in clutter, which is capable of estimating the number of targets, as well the trajectories of their states, comprising the kinematics, measurement rates, and extents. The proposed technique is based on modeling the multi-target state as a generalized labeled multi-Bernoulli (GLMB) random finite set (RFS), within which the extended targets are modeled using gamma Gaussian inverse Wishart (GGIW) distributions. A cheaper variant of the algorithm is also proposed, based on the labelled multi-Bernoulli (LMB) filter. The proposed GLMB/LMB-based algorithms are compared with an extended target version of the cardinalized probability hypothesis density (CPHD) filter, and simulation results show that the (G)LMB has improved estimation and tracking performance.

Autonomous driving at Ulm University: A modular, robust, and sensor-independent fusion approach

The project “Autonomous Driving” at Ulm University aims at advancing highly-automated driving with close-to-market sensors while ensuring easy exchangeability of the particular components. In this contribution, the experimental vehicle that was realized during the project is presented along with its software modules. To achieve the mentioned goals, a sophisticated fusion approach for robust environment perception is essential. Apart from the necessary motion planning algorithms, this paper thus focuses on the sensor-independent fusion scheme. It allows for an efficient sensor replacement and realizes redundancy by using probabilistic and generic interfaces. Redundancy is ensured by utilizing multiple sensors of different types in crucial modules like grid mapping, localization and tracking. Furthermore, the combination of the module outputs to a consistent environment model is achieved by employing their probabilistic representation. The performance of the vehicle is discussed using the experience from numerous autonomous driving tests on public roads.

A direct scattering model for tracking vehicles with high-resolution radars

In advanced driver assistance systems and autonomous driving, reliable environment perception and object tracking based on radar is fundamental. High-resolution radar sensors often provide multiple measurements per object. Since in this case traditional point tracking algorithms are not applicable any more, novel approaches for extended object tracking emerged in the last few years. However, they are primarily designed for lidar applications or omit the additional Doppler information of radars. Classical radar based tracking methods using the Doppler information are mostly designed for point tracking of parallel traffic. The measurement model presented in this paper is developed to track vehicles of approximately rectangular shape in arbitrary traffic scenarios including parallel and cross traffic. In addition to the kinematic state, it allows to determine and track the geometric state of the object. Using the Doppler information is an important component in the model. Furthermore, it neither requires measurement preprocessing, data clustering, nor explicit data association. For object tracking, a Rao-Blackwellized particle filter (RBPF) adapted to the measurement model is presented.

Multi-sensor multi-object tracking of vehicles using high-resolution radars

Recent advances in automotive radar technology have led to increasing sensor resolution and hence a more detailed image of the environment with multiple measurements per object. This poses several challenges for tracking systems: new algorithms are necessary to fully exploit the additional information and algorithms need to resolve measurement-to-object association ambiguities in cluttered multi-object scenarios. Also, the information has to be fused if multi-sensor setups are used to obtain redundancy and increased fields of view. In this paper, a Labeled Multi-Bernoulli filter for tracking multiple vehicles using multiple high-resolution radars is presented. This finite-set-statistics-based filter tackles all three challenges in a fully probabilistic fashion and is the first Monte Carlo implementation of its kind. The filter performance is evaluated using radar data from an experimental vehicle.

Vehicle tracking using extended object methods: An approach for fusing radar and laser

Combining data from heterogeneous sensors allows to enhance tracking systems by increasing the field of view, incorporating redundancy, and improving the performance by exploiting complementary sensor characteristics. This paper proposes a new vehicle tracking approach for vehicle environment perception that fuses radar and laser data. A Random-Finite-Set-based tracking filter, which permits a clear mathematical formulation of the multi-object problem, is used as fusion center. In combination with extended object measurement models that work on the raw sensor data directly, the filter uses all available information without the need for further preprocessing routines, considers object interdependencies, and works in ambiguous situations. The results are evaluated using experimental data from a test vehicle.

A fast implementation of the Labeled Multi-Bernoulli filter using gibbs sampling

This paper proposes a fast implementation of the Labeled Multi-Bernoulli (LMB) filter based on a joint prediction and update scheme. The joint calculation prevents the treatment of insignificant hypotheses, e.g. considering the disappearance of an object with high existence probability which additionally generated a precise measurement in the received measurement set. Further, a Gibbs sampling approach for generating association hypotheses is presented which drastically reduces the computational complexity compared to Murtys ranked-assignment algorithm. The proposed Gibbs sampling implementation is compared to the standard implementation of the LMB filter using two scenarios: tracking vehicles using a multi-sensor setup on a German highway and extended object tracking in an urban scenario using Velodyne data.

Environment Adaption for Companion-Systems

One of the key characteristics of a Companion-System is the adaptation of its functionality to the user’s preferences and the environment. On the one hand, a dynamic environment model facilitates the adaption of output modalities in human computer interaction (HCI) to the current situation. On the other hand, continuous tracking of users in the proximity of the system allows for resuming a previously interrupted interaction. Thus, an environment perception system based on a robust multi-object tracking algorithm is required to provide these functionalities. In typical Companion-System applications, persons in the proximity are closely spaced, which leads to statistical dependencies in their behavior. The multi-object Bayes filter allows for modeling these statistical dependencies by representing the multi-object state using random finite sets. Based on the social force model and the knowledge base of the companion system, an approach to modeling object interactions is presented. In this work, the interaction model is incorporated into the prediction step of the sequential Monte Carlo (SMC) of the multi-object Bayes filter. Further, an alternative implementation of the multi-object Bayes filter based on labeled random finite sets is outlined.