Andrej Babinec

VFH*TDT (VFH* with Time Dependent Tree)

A new modifications of VFH+ and VFH* (Vector Field Histogram) methods are presented in the paper. The features of the histogramic algorithms are generally improved and also using a potential of advanced sensors such as laser scanners is enabled. The main focus of the work is an introduction of modifications that provides collision-free navigation in environments with moving obstacles. For this purpose, a new approach in creating a look-ahead tree is proposed. All new modifications are analyzed and experimentally verified. The results obtained using conventional and modified methods have been compared. Experiments have demonstrated the validity and the technical feasibility of the proposed methods.

Optimal Navigation for Mobile Robot in Known Environment

Optimal navigation is a subset of robot navigation in an environment. It is also known as a path planning. The aim of the optimal navigation is to choose optimal path between the initial state and the desired state of the robot. There are many methods how to choose the optimal path. In this article A* algorithm was chosen, because it is widely applied. The main idea was to propose an algorithm, which is able to select the optimal path in a typical indoor environment. Despite that our real robot uses metric maps and A* algorithm is primarily designated for the topological maps, it was verified in the experiments that this algorithm can be used for off-line path planning.

High Precision GNSS Guidance for Field Mobile Robots

In this paper, we discuss GNSS (Global Navigation Satellite System) guidance for field mobile robots. Several GNSS systems and receivers, as well as multiple measurement methods and principles of GNSS systems are examined. We focus mainly on sources of errors and investigate diverse approaches for precise measuring and effective use of GNSS systems for real-time robot localization. The main body of the article compares two GNSS receivers and their measurement methods. We design, implement and evaluate several mathematical methods for precise robot localization.

RGB-D map for robot navigation

In this paper we present an algorithm for 3D map generation with an RGB-D sensor. The purpose of the generated map is to improve the navigation and localization abilities of a mobile robot. Single RGB-D frames were captured and a complex 3D representation was created using simple geometric transformations.

Real-time path planning for the robot in known environment

This article deals with path planning algorithms based on known representation of the environment. In terms of such planning choice of suitable environment representation is important. The introduction of this article is dedicated to this issue. The main body is concerned about the path planning algorithms. Several algorithms are described, verified and compared. Key contribution of this article is a comparison of these algorithms and their analysis of the suitability for various applications in mobile robotics.

Improved GNSS Localization with the Use of DOP Parameter

This paper presents the approach to improve localization based on GNSS. The principles of the GPS localization and impact of the DOP parameter on localization error are mathematically analyzed. The algorithm based on the use of DOP parameter and Kalman filter for the improvement of the localization accuracy suitable for small scale outdoor mobile robots and other outdoor applications is proposed. The applicability of the proposed methodology was verified by performed experiments with two common cheap miniature GPS modules and accurate high-end GNSS receiver used as a reference frame for the measurements. The obtained results affirmed the improvement of the localization accuracy.

Simple Image Processing Algorithms for Robot Navigation in Unknown Environment

This article deals with simple image processing algorithms which are used for navigation of the robot in unknown environment. In the beginning of the article image processing procedures used in these algorithms are defined. The transformation of coordinate system of camera to robot’s coordinate system is introduced. The main body of the article consists of the definition of L-K optical flow method used in proposed visual odometry system. Article also contains the parameter settings of the used methods. Emphasis in these algorithms has been placed on simplicity and speed, so that they can be carried out in real-time. Algorithms have been verified on several scenarios.

Detection of Welds in Automated Welding

This article deals with automated welding conceived as a robotic welding cell. Laser scanners used in automated welding are described in the main part of the article. Then, the control scheme of the robotic welding is defined. Several simple algorithms are proposed for the data processing. Emphasis in these algorithms has been placed on simplicity, so that they can run online. Algorithms have been verified on several scenarios.

Control of overhead crane based on Lyapunov approach to fuzzy controller synthesis

The subject of the paper is synthesis of a robust controller of the load swing during motion of overhead cranes. The approach implements fuzzy partition to the state variables. Stability is secured by employing the Lyapunov theory. The proposed methodology is the most appropriate for the presented problem since exact knowledge about the plant parameters is not needed. Numerical tests show the feasibility of the control scheme.

Vector Field Histogram* with look-ahead tree extension dependent on time variable environment:

The article deals with a novel approach to reactive navigation. A proposed reactive navigation is based on the Vector Field Histogram (VFH) method, which is easily modifiable. The biggest advantage of the proposed method is that it allows the robot to avoid static as well as moving obstacles in an unknown environment in a more effective way and without the need of switching any algorithm or the robot’s behaviour. Moreover, the proposed extension allows the avoidance of several moving obstacles in real time. The article contains three proposed improvements of the original VFH* method: representation of moving objects, look-ahead tree improvements and approach to criterion function. The method is verified by several experiments in various scenarios, which include few static and moving obstacles.