Michael Blaich

Real-Time Door Detection Based on AdaBoost Learning Algorithm

Doors are important landmarks for robot self-localization and navigation in indoor environments. Existing algorithms of door detection are often limited for restricted environments. They do not consider the diversity and variety of doors. In this paper we present a camera- and laser-based approach, which allows finding more than 72% doors with a false- positive rate of 0.008 in static testdata. By using different door perspectives form a moving robot, we detect more than 90% of the doors with a very low false detection rate.

Collision Avoidance for Vessels using a Low-Cost Radar Sensor

Abstract Collision avoidance for vessels highly depends on a robust obstacle detection. This is commonly achieved by use of high precision radar sensing. For smaller vessels however, the use of low-cost sensors is typical. The idea of this work is to improve the robustness of collision avoidance by integrating a sensor model together with the collision avoidance algorithm in order to consider the accuracy of the measurements. Furthermore, a target tracking algorithm based on an interacting Multi-Model Filter (IMM) is used for robust obstacle detection.

Modelling and identification of a twin hull-based autonomous surface craft

In this paper, the process and results of a parameter identification task for a maritime unmanned surface vehicle are presented. The system has been modeled using state of the art methodology, and the parameters have been estimated via a weighted least square optimization approach. The required measurement data have been taken from various maneuvre trials. For solving the optimization problem, a Particle Swarm programming approach has been used, which has reliably found the global minimum of the cost function. The results show excellent agreement between measured and simulated data.

Fast grid based collision avoidance for vessels using A∗ search algorithm

In this work a real-time grid based collision avoidance algorithm for vessels in maritime environments is presented. Most grid based collision avoidance approaches use Lees algorithm to find an optimal collision-free path. The drawback of this algorithm is the long runtime for large grids. To reduce this runtime, in this work the A* search is used instead of Lees algorithm. The algorithm additionally regards the physical constrains of the vessel and pays attention to the COLREGs. The runtime and the resulting path of Lees algorithm and the A* search are compared in computational experiments. Furthermore, the performance of the collision avoidance on a real vessel on the Lake Constance is presented.

Extended Grid Based Collision Avoidance Considering COLREGs for Vessels

Abstract In this work a grid based collision avoidance algorithm which considers the physical constrains of a vessel is presented. For this purpose a new geometry neighbourhood is introduced and explained in detail. The collision avoidance algorithm pays attention to the COLREGs and provides a collision-free path. To find this path, Lees algorithm is used.

Trajectory Planning with Negotiation for Maritime Collision Avoidance

The problem of vessel collisions or near-collision situations on sea, often caused by human error due to incomplete or overwhelming information, is becoming more and more important with rising maritime traffic. Approaches to supply navigators and Vessel Traffic Services with expert knowledge and suggest trajectories for all vessels to avoid collisions, are often aimed at situations where a single planner guides all vessels with perfect information. In contrast, the authors suggest a two-part procedure which plans trajectories using a specialised A* and negotiates trajectories until a solution is found, which is acceptable for all vessels. The solution obeys collision avoidance rules, includes a dynamic model of all vessels and negotiates trajectories to optimise globally without a global planner and extensive information disclosure. The procedure combines all components necessary to solve a multi-vessel encounter and is tested currently in simulation and on several test beds. The first results show a fast converging optimisation process which after a few negotiation rounds already produce feasible, collision free trajectories.

Obstacle and Game Element Detection with the 3D-Sensor Kinect

Detecting objects is of fundamental importance for the Eurobot Challenge 2011. This paper presents a Kinect-based approach to detect the game elements on the game field. Using the Kinect sensor provides the advantage that elements lying behind other elements can still be detected, which is nearly impossible for a laser-based approach. The Kinect provides depth information which is projected to the 3D space, building a point cloud of the game elements. The point cloud is then analyzed for the clusters of the game elements which are passed to a classifier each. The classifier decides if the passed-in cluster is a pawn, king or the enemy robot.

Designing an Omni-Directional Infrared Sensor and Beacon System for the Eurobot Competition

In this paper the design of an omni-directional sensor which measures the angles between active infrared beacons is proposed. The aim is to develop a simple and inexpensive sensor and beacon system. Therefore an array of ten CMOS cameras with an infrared filter is used. We present the design steps and the evaluation of the sensor in detail. The systematic errors of the system are analyzed during the evaluation of the sensor’s accuracy. They are compensated by a linear regression, which leads to an accuracy of less than one degree. The achieved accuracy qualifies the system for applications like landmark-based localization.

Design of a Twin Hull Based USV with Enhanced Maneuverability

Abstract This paper provides an overview of the development of a catamaran-like autonomous surface vessel. The vessel is intended to serve as an experimental platform to study algorithms for control, sensor data fusion as well as path planning and collision avoidance. The mechanical design, the electronics and software architecture is described together with the sensor and actuator setup. The propulsion system comprises of two azimuth thrusters with limited azimuth angles. This concept provides additional degrees of freedom resulting in an overactuated control system. A mathematical model of the vessel has been adapted and implemented for model based control strategies, simulation and hardware in the loop testing. In this paper some results of the parameter identification process are presented. For the overactuated system a control allocation algorithm has been developed.

Mapping of Inland Waters Using Radar

This paper presents a mapping approach for inland waters using a noisy radar sensor installed on a boat. The vessel’s position is acquired from GPS, thus this is a pure mapping problem. For the actual mapping the probabilistic open-source mapping framework octomap as presented by [8] is used. Exactly one polygon is extracted from a binary radar image, the so-called Water Enclosing Polygon. This discards inland echos and multi-path measurements. Additionally, an approach to detect bridges and dolphins is presented. The runtime of the mapping algorithm is less then 2.5 s. Thus, each new radar scan is integrated into the octomap.