Mateusz Michalski

Distance Estimation With a Long-Range Ultrasonic Sensor System

This paper presents the results of tests conducted with an ultrasonic proximity measurement system (composed of Polaroid 600 sensors and a Sonar Ranging Module SN28827), which is used in sensory subsystems in many mobile robots. The tests took into account distances ranging from 0.4 to 11 m. The analysis of the obtained measuring results created the basis for selecting a distance estimator that would guarantee the smallest measuring errors in the whole measuring range of the system. The research described was carried out in a closed room at constant environmental conditions so as to eliminate the influence of external factors on the measurement result. Each measuring series was composed of 100 measurements. For the best estimator chosen in such environment, the value of absolute measuring error never exceeded plusmn 0.03 m. Histograms that present the scatter of measurement results are also included. The minimal number of measurements necessary to achieve a reliable measurement with the selected distance estimator was determined. It is shown that in order to achieve a relative measuring error smaller than 1% with 0.99 probability there is a need to perform at least seven measurements. A proposition of the distance measuring procedure with the chosen estimator is presented. The analysis described in this paper helps to evaluate the reliability of measurements performed with ultrasonic sensors.

SAFARI inspection robot motion strategy

This paper presents the motion strategy of a wall-climbing inspection robot SAFARI. An algorithm of the robots leg movement is described. The movement sequence is chosen autonomously by the robot, respecting geometrical constraints of its construction. Robot behavior in emergency situations when any of the legs cannot be sealed on a movement surface is also described. Direct and inverse kinematics for the SAFARI robot are presented. Then, another approach, named vector formulation of kinematics, is presented. Finally, we describe software supervision of the robots states, supporting an operator in monitoring of the robots functioning.

Universal Multiaxis Control System for Electric Drives

This paper presents a solution for universal multidrive control system, which can be used as a base for the rapid prototyping of various kinematic structures, particularly in robotics, for multiple-axis synchronization tasks, or as a test bed for verification of modern control algorithms for electric drives. The example of the practical application of the proposed system was also given: It was used during prototyping process of a quadruped walking robot, powered by multiple electric motors. The abilities and performance of the system were verified with the attempt to realize the dynamic gait of the robot.

Estimation of parameters for obnoxious load which does not increase amplitude of voltage fluctuations

The influence of obnoxious load manifests in voltage variations. One of available measures of such variations are voltage fluctuations indices: amplitude and rate. Usually the obnoxious influence is accompanied by the increase of fluctuations amplitude. Although there are diagnostic cases when such increase is not present and the obnoxious influence manifests in increased rate of fluctuations. The paper proposes an approach to estimate parameters of obnoxious load for such case. At first the overview of four voltage fluctuations measures is given. Then the results of the measurements of the three different measures recorded in LV power grid are presented. Finally the method of loads parameters estimation is presented.

Design and Control of a Heating-Pipe Duct Inspection Mobile Robot

During operation of the heating net, there may appear leakages and failures in places which are hard to access. Repair of underground heating-pipe ducts requires using heavy equipment as well as temporarily removing neighboring infrastructure elements which are obstacles. This implies high costs of penetrating the failure place, so it is advisable to minimize the risk of erroneous choice of the intervention place. Localization of the failure place is difficult due to its inaccessibility or lack of information or proper tools. So, very expensive is the wrong choice of the exploration place, when failure localization is uncertain. There exist acoustic monitoring devices for rough detection of leakage, from the ground level over the damage, sensitive to the noise of outgoing steam or warm water. Nevertheless, essential is the possibility of estimation of the leakage with one’s eyes. Therefore, construction of a tool which could reach places inaccessible even for a well equipped operator is very important. This situation is due to atmospheric conditions and dimension of places which should be reached.

On selected features of mobile robot control system

In this paper the results of research of mobile robot control system are presented, namely the quality of regulation with and without on-board velocity controllers taken into account. To verify the behaviour of the control system an time-varying controller was chosen which has nontrivial computing requirements. The algorithms parameters used to control real object were set during simulations performed with described controller. The control system consists of kinematic oscillator algorithm implemented in real time operating system (RTAI Linux) and PI on-board controllers. Experimental results were obtained on a new mobile robot platform, Mini-Tacker 3.0.

Selected Problems of

International Electrotechnical Commission flickermeter is an apparatus intended to indicate the correct flicker perception level for all practical voltage fluctuation. The architecture of this apparatus is described by the standard block diagram included in IEC 61000-4-15. On the basis of the standard specification, this paper describes the method of k-factor determination. Following the specification, it has been assumed that the voltage fluctuations correspond to amplitude modulation with rectangular modulating signal. The dependency of the Pst indicator on modulation depth has been presented. The nonlinearity error of this dependency has been calculated for fluctuation rates specified in the standard. Charts have been provided depicting the influence of input voltage carriers initial phase on the Pst indicator value for fluctuation rates specified in the standard as well as for additional values. The presented results of numerical simulations, confirmed by laboratory tests, and also compliant with the proposed analytical model, describe the operation of flickermeter as defined by IEC 61000-4-15.

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The paper presents the assumptions and concepts solve the task titled “Control and Navigation” which is part of the project RobREx and gives a brief description of the construction of a wheeled mobile platform intended for research purposes. This platform has been built in the Chair of Control and Systems Engineering University of Technology. The article describes some aspects of implementing an algorithm of motion control that uses transversal

-Factor Estimation Related to the IEC Flickermeter’s Nonlinearity

In this paper the usage of controller implemented in real time operating system (RTAI Linux) for nonholonomic robot control is presented. The multilayer controller enables user interaction for on-line performance visualization and setting of parameters for reference trajectory and control algorithm. To verify and present capabilities of the controller, a kinematic oscillator algorithm was chosen, which has nontrivial computing requirements. The algorithms parameters used to control real object were set during simulations performed with described controller. The paper presents results of simulations and real robot behavior experiments as well.