J. Krejsa

Ackermann mobile robot chassis with independent rear wheel drives

This paper describes four-wheeled robotic chassis of the autonomous mobile robot Bender II utilizing Ackermann steering and independent rear drive units. The robot is designed for the use in outdoor environment. Independent rear drive gives better traction in uneven terrain with the cost of doubling the motion hardware (motors, gears and controllers). Hardware and software implementation details as well as practical experiences of this approach deployment are presented.

The enhancement of PCSM method by motion history analysis

This paper deals with the identification of wheel robot position and orientation when dealing with the global localization problem. We used a method called PCSM (Pre-Computed Scan Matching) for solving this problem for autonomous robot in known environment. This method was developed for small robots. The identification of the position and orientation of the robot is based on the fusion of pre-computed match data and the analysis of the history of robot motion. The paper provides information about this fast yet simple method.

Hybrid Navigation Method for Dynamic Indoor Environment Based on Mixed Potential Fields

Navigation task for highly populated indoor environment belongs to the most difficult issues in mobile robotics. Presented paper deals with a hybrid approach which combines three methods: potential fields, Voronoi diagrams and rule based path planner. Such combination takes the best of all mentioned methods to create reliable navigation system with maximum emphasis on safety. The method was verified using real mobile robot in common environment with dynamic obstacles.

High Level Software Architecture for Autonomous Mobile Robot

The paper deals with the high level software architecture for autonomous mobile robot Bender II, medium size wheeled nonholonomic mobile robot with Ackerman chassis for both indoor/outdoor environment. High level software uses hybrid approach combining common layered architecture with reactive control. Local navigation including static/dynamic obstacle detection/avoidance is based on laser range finder data. Global navigation in indoor environment is based on fusion of odometry based position estimation with precomputed scan matching localization technique. Architecture description is accompanied by tests results obtained in real environment.

Sensor failure detection in autonomous mobile robot application

Presented paper deals with sensor failure detection and identification (FDI) in navigation task of autonomous mobile robot. Mobile robots use ultrasonic range finders to solve a collision avoidance task, which is crucial for successful navigation. When the sensory readings are invalid the robot should be able to detect such a failure and interrupt its actual movement. To solve this task, the method based on first-order Markov chain parameters estimation was developed and tested in both the simulation and the real world environment. Practical experiments were performed on autonomous mobile robot Advee.

Active Elbow Orthosis

This paper presents a novel approach to the design of a motorized rehabilitation device – active elbow orthosis (AEO) – inspired by the principles of robotic exoskeletons. The device is currently designed for the elbow joint, but can be easily modified for other joints as well. AEO determines the motion activity of the patient using a strain gauge and utilizes this measurement to control the actuator that drives the forearm part of the orthosis. Patient activity level is related to a free arm measurement obtained via a calibration procedure prior to the exercise. A high-level control module offers several types of exercises mimicking the physiotherapist. The device was successfully verified by tests on a number of patients, resulting in extended range of elbow-joint motion.

Design of the control basis for walking gait generation based on DEDS

This contribution deals with using the hybrid control architecture for walking gait generation of the four legged robot. The main aim is to design and implement the control basis layer. Software simulation is used for validation of proposed solution.

The influence of Ga initial boundaries on the identification of nonlinear damping characteristics of shock absorber

The paper is focused on the simulation identification of nonlinear damping characteristics of the shock absorber using genetic algorithm (GA). 2 DOF quarter car model is used with nonlinear characteristics of damping force defined as piecewise functions. The characteristics are found using time courses of position, velocity and acceleration of both masses under kinematic excitation. The influence of initial boundaries determining the limits within the parameter values are searched is shown in the paper.

Probabilistic Reasoning in Diagnostic Expert System for Smart Homes

We present an expert system shell suitable for smart homes application where a diagnostics or prediction functionality can be used. Presented expert system is based on probabilistic theory and decision networks, which brings natural support for uncertainty handling. Dealing with uncertainty is one of features the expert system has and since it is designed as an empty expert system it can be transformed to other domain e.g. onboard diagnostic application for mobile robots.

Determination of Optimal Local Path for Mobile Robot

The paper presents the method of finding locally optimal path with respect to the safety of the mobile robot with non-holonomic constraints. The path is represented by the polyline and circular segments. Initial path is found in the geometrical centers of the corridors to pass through and is optimized using evolutionary algorithm. The complexity of path description can be sequentially increased, allowing to further improve the quality of the path while optimization can be interrupted any time. Minimal distance to the obstacles is taken as optimality criterion.