Tomasz Bartkowiak | Poznan University of Technology (original) (raw)

Papers by Tomasz Bartkowiak

Lecture notes in mechanical engineering, 2019

The paper presents a concept, a mathematical model and a control algorithm of an automated system... more The paper presents a concept, a mathematical model and a control algorithm of an automated system for workpiece leveling. In the proposed solution, a workpiece is placed on a set of electrically-powered variable-length supports. The location of each support is not known before the leveling. A current orientation of workpiece is measured by a precise biaxial inclinometer. The leveling is performed in three stages which involve subsequent extensions of supports and measuring the resulting orientation. This system allows determining the location of each support and the required displacements of each support that are necessary for leveling the workpiece. The system is controlled by an industrial PLC. A single power source and motion controller as well as a distributed demultiplexer, which activates each support, are used to reduce the cost. The supports were manufactured and tested for accuracy and repeatability according to ISO 230-2:2014. The proposed solution can be used for layout and for leveling workpieces on a machine tool table.

International Journal of Simulation Modelling, Jun 15, 2021

The demand for fast, economic and high load capacity intralogistics transport is a growing trend.... more The demand for fast, economic and high load capacity intralogistics transport is a growing trend. One of the recent solution is a logistic train, which consists of a tractor and a certain number of towed trailers. It is essential that the trailer follows the track of the preceding unit as it allows reduction of shopfloor area dedicated for transport. A perfectly suited steering system for this application is the double Ackermann system. In this study, the kinematic model of the tractor with n trailers was developed based on the Jacobian matrix. The tractor model was adapted to drive along a given trajectory using a PD controller. The simulation studies confirmed that the PD controller is sufficient to control the trajectory for developed kinematic model. The obtained results showed that the trailers with the double Ackermann steering system follow a similar path, which is the most convenient for narrow turn ride. The developed kinematic model can be used for the fast path planning and the design of transportation routes in manufacturing areas. The expanded model with an advanced control system can be used to control a real logistic train.

In the paper, authors present a design of a novel input device, in which, thanks to two ergonomic... more In the paper, authors present a design of a novel input device, in which, thanks to two ergonomically placed wheels, the operator can control the multi-axis manipulator with a single hand. The application of rotating elements provides the following benefits: achieving unlimited angular displacement, controlling numerous number of axes thanks to the certain combination of wheels motions, assigning force and position amplification individually, what helps to obtain both high speed and precision. In order to generate feedback force in the joystick, dedicated MR brakes were designed and built. The proposed feedback approach is an example of admittance control [1]. The joystick was built and tested at the Institute of Mechanical Technology of Poznan University of Technology. In the article, a theoretical model of the brake was shown together with analysis and discussion of its parameters. Additionally, it was supplemented with the results of theoretical and simulative studies. The paper also contains the outcome of the initial study focused on the analysis of the functionality, ergonomics and possibility of two-, three- and four axis control. It showed that the control algorithms played an essential role in motion control. They allow a rapid change of the generated resistance force during the change of motion direction. The obtained results validated the assumed design of the joystick with rotary elements and applied MR brakes due to the possibility of precisely control the motion resistance.

The paper presents a study into the kinematics of a novel type of a rotary positioning table base... more The paper presents a study into the kinematics of a novel type of a rotary positioning table based on the constrained parallel mechanism. Fixture and leveling a workpiece on a machine tool table is an essential stage in machining or layout process. In this study, a compact low-height rotary table is presented for automated leveling, which can be mounted directly on the machine tool table without a significant decrease of the workspace. The authors propose a modification of parallel mechanism by introducing four extensible leg design with specific geometrical constraint for workpiece positioning and in order to achieve higher rigidness. The table is driven by four hydraulic linear actuators which are integrated in the linkages. The designed model allows to rotate the table about the sphere center about three independent axis. Procedures using meta-heuristic methods were implemented to optimize the geometrical dimensions of the entire mechanism for the required workspace.Copyright © 2015 by ASME

Materials, Jan 14, 2019

The objectives of this paper are to demonstrate the viability, and to validate, in part, a multis... more The objectives of this paper are to demonstrate the viability, and to validate, in part, a multiscale method for calculating curvature tensors on measured surface topographies with two different methods of specifying the scale. The curvature tensors are calculated as functions of scale, i.e., size, and position from a regular, orthogonal array of measured heights. Multiscale characterization of curvature is important because, like slope and area, it changes with the scale of observation, or calculation, on irregular surfaces. Curvatures can be indicative of the topographically dependent behavior of a surface and, in turn, curvatures are influenced by the processing and use of the surface. Curvatures of surface topographies have not been well-characterized yet. Curvature has been used for calculations in contact mechanics and for the evaluation of cutting edges. Manufactured surfaces are studied for further validation of the calculation method because they provide certain expectations for curvatures, which depend on scale and the degree of curvature. To study a range of curvatures on manufactured surfaces, square edges are machined and honed, then rounded progressively by mass finishing; additionally, a set of surfaces was made by turning with different feeds. Topographic measurements are made with a scanning laser confocal microscope. The calculations use vectors, normal to the measured surface, which are calculated first, then the eigenvalue problem is solved for the curvature tensor. Plots of principal curvatures as a function of position and scale are presented. Statistical analyses show expected interactions between curvature and these manufacturing processes.

Materials, Jul 7, 2020

Anisotropy can influence surface function and can be an indication of processing. These influence... more Anisotropy can influence surface function and can be an indication of processing. These influences and indications include friction, wetting, and microwear. This article studies two methods for multiscale quantification and visualization of anisotropy. One uses multiscale curvature tensor analysis and shows anisotropy in horizontal coordinates i.e., topocentric. The other uses multiple bandpass filters (also known as sliding bandpass filters) applied prior to calculating anisotropy parameters, texture aspect ratios (Str) and texture directions (Std), showing anisotropy in horizontal directions only. Topographies were studied on two milled steel surfaces, one convex with an evident large scale, cylindrical form anisotropy, the other nominally flat with smaller scale anisotropies; a µEDMed surface, an example of an isotropic surface; and an additively manufactured surface with pillar-like features. Curvature tensors contain the two principal curvatures, i.e., maximum and minimum curvatures, which are orthogonal, and their directions, at each location. Principal directions are plotted for each calculated location on each surface, at each scale considered. Histograms in horizontal coordinates show altitude and azimuth angles of principal curvatures, elucidating dominant texture directions at each scale. Str and Std do not show vertical components, i.e., altitudes, of anisotropy. Changes of anisotropy with scale categorically failed to be detected by traditional characterization methods used conventionally. These multiscale methods show clearly in several representations that anisotropy changes with scale on actual surface measurements with markedly different anisotropies.

Modelowanie Inżynierskie, 2013

Latin American Journal of Solids and Structures, 2021

Logistic train is one of the recent solutions applied in the intralogistics. It bases on the conc... more Logistic train is one of the recent solutions applied in the intralogistics. It bases on the concept of the "milkrun" delivery method. The main problem in the implementation of intralogistics trains is the possibility to determine whether the train is able to pass the given path without a colliding with surrounding objects. Dynamic model presented in this paper was performed for the three most common steering systems for the trolleys: double Ackermann steering system and two drawbar systems: conventional and virtual clutch. The dynamic model was developed following Lagrange's theorem including the possibility of lateral slip. The system of differential equations was numerically solved. In order to calculate the lateral friction forces we used three different tire models: simplified, sigmoidal and Pacejka Magic formula. The results obtained for different tire models and steering systems are presented in the form of animations presenting train run in various conditions. The analyses have shown that the use of simplified tire models is justified under certain conditions.

Anisotropy of surface texture can in many practical cases significantly affect the interaction be... more Anisotropy of surface texture can in many practical cases significantly affect the interaction between the surface and phenomena that influence or are influenced by the topography. Tribological contacts in sheet forming, wetting behavior or dental wear are good examples. This article introduces and exemplifies a method for quantification and visualization of anisotropy using the newly developed 3D multi-scale curvature tensor analysis. Examples of a milled steel surface, which exhibited an evident anisotropy, and a ruby contact probe surface, which was the example of isotropic surface, were measured by the confocal microscope. They were presented in the paper to support the proposed approach. In the method, the curvature tensor T is calculated using three proximate unit vectors normal to the surface. The multi-scale effect is achieved by changing the size of the sampling interval for the estimation of the normals. Normals are estimated from regular meshes by applying a covariance matrix method. Estimation of curvature tensor allows determination of two directions around which surface bends the most and the least (principal directions) and the bending radii (principal curvatures). The direction of the normal plane, where the curvature took its maximum, could be plotted for each analyzed region and scale. In addition, 2D and 3D distribution graphs could be provided to visualize anisotropic or isotropic characteristics. This helps to determine the dominant texture direction or directions for each scale. In contrast to commonly used surface isotropy/anisotropy determination techniques such as Fourier transform or autocorrelation, the presented method provides the analysis in 3D and for every region at each scale. Thus, different aspects of the studied surfaces could clearly be seen at different scales.Copyright © 2017 by ASME

Vibrations in Physical Systems, 2012

Winter Simulation Conference, Dec 11, 2016

The paper demonstrates the use of a Discrete Event Simulation tool to reduce the negative impact ... more The paper demonstrates the use of a Discrete Event Simulation tool to reduce the negative impact of machine failures on the performance of a filling line. The buffer allocation problem has received a lot of attention, but still there are examples of unreliable production systems for which a buffer can be allocated in order to increase their productivity. The subject of the study is a filling and packaging production line which consisted of seven machines connected by conveyors. Machine failures are registered by maintenance Data Acquisition system. Those data are used to derive statistical distributions for Time To Repair and Time Between Failures. The model is built using FlexSim simulation software and different allocation scenarios are considered. Introduction of buffers results in an increase in mean line throughput by 15%. The initial results indicate that the proposed approach may lead to the reduction of negative effects of machine failures.

Archives of Mechanical Technology and Materials, 2019

This paper demonstrates kinematic analysis of multiple trailers on a tractor system for productio... more This paper demonstrates kinematic analysis of multiple trailers on a tractor system for production logistics. The analysis concerned three different steering systems of the trailers: virtual clutch and drawbar system, conventional clutch and drawbar system, double Ackermann steering system. Designed kinematic models contain various variants of paths: turning at a constant value of the steering angle, changing the steering angle as a result of an approaching collision. Each of these variants also included driving in a straight line after a 90° turn. The validation of the developed kinematic model was done by using a real logistic train, which path was registered via aerial drone. For each of the developed kinematic models, a visualization of drive through the 90° turn was created.

Mechanik, Sep 1, 2016

W opracowaniu przedstawiono koncepcję, model matematyczny oraz algorytm sterowania automatycznego... more W opracowaniu przedstawiono koncepcję, model matematyczny oraz algorytm sterowania automatycznego systemu poziomowania odlewu do trasowania. Do budowy systemu zastosowano precyzyjny, dwuosiowy przetwornik inklinometryczny, napędzane przyrządy obróbcze o różnej długości i sile oraz sterownik przemysłowy PLC kontrolujący cały proces poziomowania. SŁOWA KLUCZOWE: poziomowanie odlewów, trasowanie, napędzane podpory The paper presents the concept, mathematical model and algorithm of automated cast leveling control system for marking-out. The system uses a precise, two-axis inclinometer, electrically driven machining devices of different heights and load capabilities as well as an industrial PLC to controls the entire leveling process.

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, Jun 7, 2015

In this paper, the numerical and experimental results for the dynamics of pendulum with variable ... more In this paper, the numerical and experimental results for the dynamics of pendulum with variable mass were described. Mathematical model was developed taking into account the loss of mass, reactive force, air resistance, and friction. A corresponding test rig was designed and built in order to validate the numerical results. The purpose of the paper is to show that in case of the variable mass systems the second Newton’s law cannot be directly applied in the traditional form. The simple experiment was designed to support the thesis that the modification of Newton’s second law is necessary.

Surface topography, Jan 23, 2023

This study explores a quantitative analysis of multiscale geometric characterization of laser mel... more This study explores a quantitative analysis of multiscale geometric characterization of laser melted parts made of Ti-6Al-4V to establish functional relations between geometric characterisations and formation, or process, parameters. A focus is here is on multiscale curvature as a characterization of local shape which, unlike conventional texture characterizations, does not require a datum. Surfaces were measured using microCT scanner which, unlike conventional optical and stylus methods, can measure surfaces of re-entrant features. Laser power and scanning speed were considered as crucial AM process parameters in this study. It was found that curvature performed well in discriminating surfaces by both crucial process parameters and their combination for all analysed scales ranging from 0.005 to 1.000 mm. Strong functional correlations were established using linear regression (R2 = 0.83) for the largest considered scale, while no correlations were observed for fine scales associated with the powder particle sizes. It was noticed that large scale curvature increases with laser power and decreases with the scanning speed. That showed that multiscale curvature can be an easy-to-implement and valuable analysis for complex, freeform, AM metal surfaces.