RAZVOJ REKONFIGURABILNOG OBRADNOG SISTEMA NA BAZI ROBOTA

Rezime: Istraživanje i razvoj u oblasti višeosne obrade i rekonfigurabilnih multifunkcionalnih obradnih sistema su danas u svetu veoma aktuelni. U radu se pokazuje deo rezultata u razvoju multifunkcionalnog rekonfigurabilnog obradnog sistema na bazi robota za delove od mekih materijala sa složenim površinama, veih dimenzija i niže klase tanosti

Detection of road structure composition and geometry changes by processing measured parameters, for the purpose of road network categorization

U ovoj disertaciji razvijen je algoritam za predikciju rizika proklizavanja vozila, čime je omogućeno mapiranje rizičnih zona duž putne infrastrukture. Predloženim algoritmom se realizuju automatska detekcija i prepoznavanje finih promena sastava i geometrije putne površi. Ovo se zasniva na obradi teksture slike dobijene skeniranjem puta, iz specijalnog vozila koje se kreće kolovoznom trakom duž deonice putne mreže. Merni podaci prikupljeni su upotrebom multisenzorske platforme montirane na vozilo. Ovakav pristup analizi putne infrastrukture ima za cilj adekvatnu i blagovremenu reakciju na promene stanja površi puta, koje nisu vidljive golim okom od strane direktnih učesnika u saobraćaju. Ovo je od posebnog značaja i za potrebe službi koje se bave održavanjem puteva i sanacijom oštećenja. Na osnovu eksperimentalnih rezultata i obradom izmerenih parametara, razvijen je i predstavljen algoritam čiji je glavni cilj predviđanje rizika i lokalizacija regiona potencijalnih saobraćajnih nezgoda koje mogu nastati kao posledica proklizavanja vozila sa putne površi. U pogledu strukturnog kvaliteta, putna površ se najčešće opisuje svojom teksturom. Njena geomerijska svojstva direktno utiču na druge činioce bezbednosti u saobraćaju, kao što su interakcija pneumatika sa površinskim slojem puteva, odvođenje tj. drenaža vode i otpornost na proklizavanje. U osnovi razvoja pomenutog algoritma urađene su analize jednodimenzionalnih i dvodimenzionalnih signala dobijenih uređajima za beskontaktno skeniranje. Akvizicija jednodimenzionalnih signala vršena je na osnovu interakcije koherentne svetlosti sa površinskim materijalima puta, upotrebom laserskog profilometra. Dvodimenzionalni signal je dobijen upotrebom video-kamere kojom je snimana putna površ. Oba dijagnostička pristupa realizovana su uređajima sa istog specijalnog vozila. U ovoj disertaciji je najpre potvrđena multifraktalna priroda profila putne površi, čime je dokazana mogućnost primene multifraktalnog pristupa u analizi teksture puta, koja se pokazala kao veoma pouzdan alat za detekciju i lokalizaciju granulometrijskih promena na putnoj površi. Rezultati multifraktalne analize su iskorišćeni kao potvrda stohastičke prirode jednodimenzionalnog signala, i pretpostavka da dvodimenzionalni signal pripada sličnoj familiji slučajnih/pseudoslučajnih vremenskih serija. Novi algoritam predikcije rizika, predložen u disertaciji, bazira se na obradi i analizi dvodimenzionalnog signala. Obrada i analiza slike vršena je testiranjem četiri metode za ekstrakciju obeležja teksture: Gaborovom transformacijom, transformacijom talasićima, matricom kopojavljivanja nivoa sivog i obeležjima histograma ivica. Od svih navedenih metoda, primena Gaborove transformacije je pokazala najbolje rezultate. Ekstrakcija vektora obeležja teksture praćena statističkim algoritmima za merenje sličnosti vektora obeležja i selekcija referentnog vektora, dovela je do klasifikacije teksture slike. Sâm algoritam je nadograđen inkorporiranjem istovremenih merenja temperature površine, kako bi se kreirala i validirala finalna klasifikacija finih tekstura površine. Put je klasifikovan u klase rizika visokog, srednjeg i niskog nivoa, u skladu sa opasnostima od proklizavanja, što je omogućilo formiranje mape rizičnih zona. Algoritam predviđanja rizika je potvrđenna osnovu podataka o saobraćajnim nezgodama, koje su se desile u periodu od tri sukcesivne godine na istoj deonici puta, pribavljenih iz baze Agencije za bezbednost drumskog saobraćaja Srbije. Razvijeni algoritam omogućava predikciju lokacija rizičnih zona sa mapiranjem, koje upozoravaju na potencijalne saobraćajne nezgode usled proklizavanja vozila. Može se koristiti kao podrška za navigaciju, autonomnu vožnju, a moguće je unaprediti celu proceduru sa ciljem adekvatne reakcije u realnom vremenu, putem globalne mreže (IoV - Internet of Vehicles), koja postaje sastavni deo tzv. pametnih gradova (smart cities). Ovakav pristup analizi putne površi će svakako, u svojoj daljoj primeni, rezultirati u smeru precizne i objektivne klasifikacije i kategorizacije kompletne putne infrastrukture, a sve u pravcu povećanja bezbednosti učesnika u saobraćaju, sa naročitim akcentom na rešenje problema predviđanja rizika na putu za donošenje odluka pri autonomnoj vožnji.This dissertation describes the development of an algorithm for predicting the risk of vehicle skidding by mapping high-risk zones along road surfaces. The algorithm enables the automatic detection and recognition of fine changes in the composition and geometry of road surfaces. It is based on image texture processing of the metrics obtained from scanning the road surface using a vehicle-mounted multi-sensory platform. The objective of this algorithm is to provide the means to a real time response to invisible to the bare eye changes in road surface conditions for the benefit of road maintenance and damage repair services, as well as general motorists and autonomously driven vehicles. The algorithm will be capable of being used to identify and assess the accident risk posed by inadequate and compromised road surfaces that potentiate the possibility of vehicles skidding and sliding. In terms of structural quality, road surface is most often described according to its texture. Its geometric properties have a direct impact on other road safety factors, such as interaction with vehicle tires, water drainage and skid resistance. The development of the algorithm was based on analysis of onedimensional and two-dimensional signals obtained by contactless scanning devices. The acquisition of one-dimensional signals was performed with a laser profiler, and the two-dimensional signal was obtained with a combination of a video camera and a surface temperature sensor. All diagnostic devices were mounted on the same special vehicle. For this research, the multifractal nature of the road surface profile was firstly confirmed, thus proving the feasibility of applying a multifractal approach to analyze road texture. This has proven to be a very reliable tool for detecting and locating real changes in the geometry of road surfaces. The results of multifractal analysis were used to confirm the stochastic nature of the one-dimensional signal, and the assumption that the two-dimensional signal belongs to a similar family of random / pseudorandom time series. The new risk prediction algorithm proposed in this dissertation is based on processing and analyzing a two-dimensional signal. Image processing and analysis were tested by comparing four texture extraction methods: Gabor transform, wavelet transform, gray level co-occurrence matrix and edge histogram descriptor. Of all the above methods, the Gabor transform produced the best results. Texture feature vector extraction, followed by statistical algorithms to measure feature vector similarity and reference vector selection, led to the classification of the image texture. The algorithm itself has been upgraded by incorporating simultaneous surface temperature measurements to create and validate the final classification of fine surface textures. The road was classified into high, medium and low level risk areas according to skid hazard, which enabled the formation of a map of risk zones. The algorithm for risk prediction was validated on the basis of traffic accidents which occurred over three successive years on the same section of road, information for which was obtained from the database of the Road Traffic Safety Agency of Serbia.The algorithm that has been developed enables risk assessment mapping of dangerous locations. In this way, potential traffic accident sites due to vehicle skidding can be flagged. It could be used as a support for navigation or for autonomous driving. The entire procedure could be improved and updated by integrating real time responses through the global network (Internet of Vehicles - IoV), to become an integral part of so-called smart cities. The approach to road surface analysis described in this research paper could potentially be applied to the precise and objective classification and categorization of the entire road surface infrastructure. Road safety could be increased, with particular emphasis on solving the risk prediction problems for decision making for autonomous driving

Rigid body dynamics in optimization of the machine tool vibroisolation

Modern design of the machine tool treats the suspending parts as a crucial element of the effective vibration isolation. Therefore the suspending items are specifically developed and subjected to extensive tests before being applied on real objects. These elements ensure accurate levelling and appropriate vibration damping. Usually selection of inadequate support element causes intensive disturbing effects in machining. The paper presents dynamics analysis of the machine tool suspended on flexible mountings. The overall analysis is conceived on a rigid body dynamics. This method enables selection of an optimal supporting configuration. Further on such an effective suspension design prevents a need for expensive monitoring of the dynamic characteristics of the mechanical system, i.e. machine tool and supports. The paper explores dynamics of a real, flexibly supported machine tool. Results are obtained with the assistance of the "SUPPORT" software. Finally the theoretical and computational statements are approved throughout extensive site measurements on the machine tool body with appropriate instrumentation

Configuring of 3-axis vertical CNC machine for rapid prototyping with two translatory and one rotary axes

This paper describes the configuration of a 3-axis vertical CNC machine tool for rapid prototyping with one rotary and two translational axes. The machine works in a polar-cylindrical coordinate system. The structure of the machine is C'OXZ. The virtual machine model is configured in the PTC Creo software environment. After configuring the virtual machine, the simulation of the CLF-based was performed in the mentioned software environments, and then the verification according to the G-code program in the Vericut software environment was performed. Programming and control of the configured prototype machine are realized in the LinuxCNC software environment, which is based on the PC platform. Also, in this paper, digital twin of machine realized in a python software environment is shown. The presented results show the proper functioning of the whole system

Kinematic modeling of hybrid parallel serial five-axis machine tool

Paralelne strukture mašina alatki i robota u odnosu na serijske strukture imaju niz prednosti. Za gradnju paralelnih mašina alatki i robota danas se koristi veći broj mehanizama sa paralelnom kinematikom različitih topologija sa 3 do 6 stepeni slobode. Međutim, s obzirom na izvesna ograničenja paralelnih mehanizama intenzivirana su istraživanja na iznalaženju mehanizama hibridnih arhitektura kao kombinacija paralelnih i serijskih struktura. U radu su predstavljeni rezultati kinematičkog modeliranja hibridne paralelno-serijske petoosne mašine alatke na bazi Tricept mehanizma. Kako ovakva mašina uključuje paralelnu strukturu sa tri stepena slobode i serijsku strukturu sa dva stepena slobode, to rešenja problema inverzne i direktne kinematike takođe uključuju paralelni i serijski deo. Inverzni kinematički problem je rešen analitički dok rešenje direktnog kinematičkog problema sadrži analitički i numerički deo. Na osnovu rešenja inverznog kinematičkog problema analiziran je radni prostor u cilju izbora projektnih parametara prototipa.Compared with serial structured machine tools and robots, parallel kinematic machine tools and robots have many advantages. Many different topologies of parallel mechanisms with 3-6 DOF have been used. Considering that some limitations are indeed due to the use of parallel mechanisms, it is appealing to investigate architectures based on hybrid arrangements where serial and parallel concepts are combined. This paper is aimed at presenting a study on the kinematic modeling of the Tricept based five-axis vertical machine tool. Since the machine comprises 3-DOF parallel structure and 2-DOF serial wrist direct and inverse kinematics also comprise serial and parallel part. Inverse kinematics is solved analytically while direct kinematics consists of an analytical and numerical part. Based on machine inverse kinematics, the workspace has been analyzed in order to select machine prototype design parameters

Identification, modelling and compensation of errors due to machining

У раду се полази од развиjеног обрадног система на бази робота за вишеосну обраду делова од мекших материjала ниже и средње класе тачности. Развоj оваквог система jе обухватио две групе проблема. Први, развоj система управљања и програмирања робота у G-коду и други, побољшање тачности обраде кроз компензациjу грешака обраде услед статичке попустљивости робота, што представља и основни циљ истраживања у овоj дисертациjи. У циљу моделирања и идентификациjе ових грешака извршено jе моделирање статичке попустљивости експерименталног робота. Развиjени приступ моделирања статичке попустљивости робота даjе увид у утицаj попустљивости сваког поjединачног зглоба на попустљивост робота у Декартовом простору, што га чини вишеструко применљивим. Оваj приступ jе омогућио и развоj експерименталног метода идентификациjе попустљивости робота и експериментално аналитичког приступа идентификациjе резултуjућих попустљивости зглобова коjе представљаjу главне изворе попустљивости робота. За овако развиjен модел попустљивости робота, с обзиром на могућност да се робот програмира у G-коду, у овоj дисертациjи jе развиjен метод off-line компензациjе статичких грешака изазваних силама резања. Идеjа развиjеног метода jе модификациjа програмиране путање кориговањем G-кода према израчунатим статичким помераjима врха алата. Ови помераjи се израчунаваjу применом развиjеног модела попустљивости робота и механистичког модела сила резања познатог у литератури. Развиjени метод off-line компензациjе грешака ствара реалне претпоставке за практичну примену робота у обради. Метод jе директно применљив од стране програмера и оператера коjи имаjу искуства у CNC технологиjи и програмирању у G-коду. Експерименталним обрадама са и без компензациjе грешака показана jе ефикасност развиjеног off-line метода компензациjе. Добиjени резултати су показали да се применом развиjеног метода компензациjе грешака може остварити задата тачност обраде у очекиваним границама за роботе, jер на грешке обраде утичу и динамика робота, крутост моторног вретена, итд.The work starts from the developed robotic machining system for multiaxis machining of lower- and medium-accuracy class lightweight materials. The development of such system comprised two groups of problems. First, the development of robot control and programming in G-code and, second, improvement of machining accuracy through machining errors compensation due to robot static compliance, which represents the main goal of investigations in this doctoral dissertation. For the purpose of modelling and identifying these errors, static compliance modelling of the experimental robot has been done. The developed approach to modelling robot static compliance provides an insight into the impact of each individual joint compliance on robot static compliance within a Cartesian space, making it multi-purpose applicable. The approach has also enabled the development of experimental method for identifying robot compliance and experimental analytical approach for identifying the resulting compliances of joints, representing the major sources of robot compliance. For such developed model of robot static compliances as well as the possibility of programming the machining robot in G-code, a method of off-line compensation of cutting force-induced static errors has been developed. The idea underlying the developed method is modification of programmed machining path by correcting G-code according to calculated tool tip static displacements. These displacements are calculated by applying the developed robot compliance model and cutting forces mechanistic model well-known in the literature. The developed method for off-line error compensation creates realistic assumptions for practical robot application in machining. The method is straightforward applicable by programmers and operators experienced in CNC technology and programming in G-code. Experimental machining with and without error compensation evidenced the efficiency of the developed off-line method for error compensation. The obtained results indicate that the application of the developed method for error compensation can achieve specified machining accuracy within the expected limits for robots since machining errors also influence robot dynamics, motor spindle stiffness, etc

Virtual horizontal machining center LOLA HBG 80 for program verification and monitoring

Ovaj rad opisuje konfigurisanje virtuelnog horizontalnog obradnog centra LOLA HBG80 u okviru sistema za programiranje i verifikaciju, kao i u okviru sistema otvorene arhitekture upravljanja. Horizontalni obradni centar LOLA HBG 80 podržan je ekvivalentnom virtuelnom mašinom u CAD/CAM okruženju (PTC Creo i Catia), STEP-NC mašinskom okruženju, kao i u upravljačkom sistemu. Virtuelna simulacija je od suštinske važnosti za obradu, a razvijene virtuelne mašine koriste se za verifikaciju programa i monitoring procesa obrade. Virtuelna mašina u sistemu za programiranje omogućava verifikaciju programa pre slanja na stvarnu mašinu i može da uključuje verifikaciju putanje alata (CLF-Cutter Location File) i verifikaciju G-koda. U radu se takođe govori o mogućnosti primene novog metoda programiranja poznatog kao STEP-NC i pripremi odgovarajućeg okruženja koje uključuje virtuelnu mašinu. Virtuelna mašina u sistemu upravljanja predstavlja poslednji nivo za konačnu verifikaciju programa, kao i sistem za nadzor procesa.This paper describes configuring the virtual horizontal machining center LOLA HBG80 within the programming and verification system and the open architecture control system. The horizontal machining center LOLA HBG 80 is represented by an equivalent virtual machine in a CAD/CAM environment (PTC Creo and Catia), STEP-NC Machine environment, and the control system. Virtual simulation is essential for machining, and the developed virtual machines are used for program verification and monitoring of the machining process. The virtual machine in the programming system allows the verification of the program before sending it to the real machine and includes verification of the tool path (CLF-Cutter Location File) and G-code. The paper also discusses the possibility of applying a new programming method known as STEP-NC and preparing an adequate environment that includes a virtual machine. The virtual machine in the control system represents the last level for the final program verification and the process monitoring system

An overview of rapid prototyping technologies using subtractive, additive and formative processes

Ovaj rad opisuje metodologiju za primenu brze izrade prototipova primenom subtraktivnih, aditivnih i formativnih tehnologija na osnovu STL fajlova. Tehnologije brze izrade prototipova uključuju digitalni lanac informacija CAD/CAM /CNC, do nivoa koji omogućava uspešnu realizaciju fizičkih modela koristeći novu tehnologiju, dodavanjem, oduzimanjem i oblikovanjem materijala. U radu su razmatrane uobičajene tehnologije brze izrade prototipova, za koje je predložena generalizovana metodologija za njihovu primenu. Pokazane su i mogućnosti za verifikaciju programa pre same izrade modela. Metodologija je verifikovana na konkretnim primerima izrade izabranih delova koristeći tehnologije oduzimanja, dodavanja materijala sloj po sloj, i izrade kalupa (dodavanjem materijala) za livenje modela od silikona.This paper describes methodology for application of a rapid prototyping using subtractive, additive and formative technology based on STL files. Rapid prototyping technology includes using of a digital information chain CAD/CAM/CNC to a level which allows the successful realization of the physical models based on new technologies by adding, subtracting and molding material. The paper discusses about the usual technologies for rapid prototyping, for which a generalized methodology for their application has been proposed. The possibilities for program verification prior to the realization of the model were also shown. The methodology is verified on real examples of making selected parts. Used technologies are subtracting and adding material layers, layer by layer, and mold making (by adding material) for molding the silicone model

Configuring of 3-axis vertical CNC machine for rapid prototyping with two translatory and one rotary axes

This paper describes the configuration of a 3-axis vertical CNC machine tool for rapid prototyping with one rotary and two translational axes. The machine works in a polar-cylindrical coordinate system. The structure of the machine is C'OXZ. The virtual machine model is configured in the PTC Creo software environment. After configuring the virtual machine, the simulation of the CLF-based was performed in the mentioned software environments, and then the verification according to the G-code program in the Vericut software environment was performed. Programming and control of the configured prototype machine are realized in the LinuxCNC software environment, which is based on the PC platform. Also, in this paper, digital twin of machine realized in a python software environment is shown. The presented results show the proper functioning of the whole system

An overview of rapid prototyping technologies using subtractive, additive and formative processes

Ovaj rad opisuje metodologiju za primenu brze izrade prototipova primenom subtraktivnih, aditivnih i formativnih tehnologija na osnovu STL fajlova. Tehnologije brze izrade prototipova uključuju digitalni lanac informacija CAD/CAM /CNC, do nivoa koji omogućava uspešnu realizaciju fizičkih modela koristeći novu tehnologiju, dodavanjem, oduzimanjem i oblikovanjem materijala. U radu su razmatrane uobičajene tehnologije brze izrade prototipova, za koje je predložena generalizovana metodologija za njihovu primenu. Pokazane su i mogućnosti za verifikaciju programa pre same izrade modela. Metodologija je verifikovana na konkretnim primerima izrade izabranih delova koristeći tehnologije oduzimanja, dodavanja materijala sloj po sloj, i izrade kalupa (dodavanjem materijala) za livenje modela od silikona.This paper describes methodology for application of a rapid prototyping using subtractive, additive and formative technology based on STL files. Rapid prototyping technology includes using of a digital information chain CAD/CAM/CNC to a level which allows the successful realization of the physical models based on new technologies by adding, subtracting and molding material. The paper discusses about the usual technologies for rapid prototyping, for which a generalized methodology for their application has been proposed. The possibilities for program verification prior to the realization of the model were also shown. The methodology is verified on real examples of making selected parts. Used technologies are subtracting and adding material layers, layer by layer, and mold making (by adding material) for molding the silicone model