Examination of the positioning accuracy of the machine tool with hybrid kinematics

The intensive development of machine production in recent years has enabled the emergence of machine tools with parallel and hybrid kinematic structure and their integration into industrial production. Therefore, extensive research has been conducted in recent years to examine the exploitation possibilities of such machines and the justification of their application in certain areas of mechanical engineering. An important part of that research is the examination of accuracy and the possibility of calibrating machine tools with non‐trivial kinematics. The paper presents a part of the research carried out to determine the influence of the characteristics of individual machine components on the overall positioning accuracy of the machine tool prototype based on the O‐X glide hybrid mechanism.For publisher: Full Prof. Aleksandar Milašinović, PhD Editor of chief: Full Prof. Petar Gvero, PhD Executive editor:Biljana Prochaska, PhD, Milivoj Stipanović, Bs

Testing the positioning accuracy of machine tools with hybrid kinematics according to ISO 230-2 standard

Mašine alatke sa parelelno-serijskom (hibridnom) kinematskom strukturom predstavljaju nekonvencionalan tip mašina alatki čije karakteristike zavise od kinematske konfiguracije. Zbog toga je neophodno da se za svaki tip mehanizma izvrši posebna analiza tačnosti. Ako tačnost neke mašine opisujemo kao karakteristiku koja je posledica niza osobina mehaničke i upravljačke strukture, onda je jedan od najboljih pokazatelja karakteristika mašine stanje tačnosti pozicioniranja. Kod konvencionalnih mašina alatki koje se baziraju isključivo na serijskoj (rednoj) kinematskoj strukturi postoje standardi i preporuke (ISO 230-2, VDI DGQ 3441), koje se bave problemom tačnosti pozicioniranja. U ovom radu se opisuje merenje tačnosti pozicinoranja mašine alatke sa hibridnom kinematskom strukturom „O-X glide“ prema standardu ISO 230-2 i analiziraju se dobijeni rezultati.Machine tool with parallel-serial (hybrid) kinematics structure represents unconventional type machine tools whose characteristics depend on the kinematic configuration. Therefore, it is necessary to perform a separate accuracy analysis for each type of mechanism. If we describe the accuracy of a machine as a characteristic that is a consequence of a number of properties of the mechanical and control structure, then one of the best indicators of the characteristics of a machine is the state of positioning accuracy. Conventional machine tools based exclusively on serial (in-line) kinematic structure have standards and recommendations (ISO 230-2, VDI DGQ 3441) that deal with positioning accuracy. This paper describes the measurement of the positioning accuracy of a machine tool with a hybrid kinematic structure "O-X glide" according to the ISO 230-2 standard and analyzes the obtained results of this mechatronic system

Analysis of Positioning Accuracy of Prototype Machine Tools with Hybrid Kinematics

Machine tools with a hybrid kinematic structure represent an unconventional type of machine tools whose characteristics depend on the kinematic configuration. Therefore, it is necessary to perform a separate accuracy analysis for each machine configuration. The analysis of the characteristic values obtained by examining the accuracy of positioning is the starting point for further improvement and calibration of this type of machine. In the case of conventional machine tools with a serial kinematic structure, appropriate standards and recommendations are used to evaluate the state of the machine through testing the positioning accuracy. The paper describes the preliminary measurement of the condition of the machine tool with the hybrid kinematic structure "O-X glide" according to the ISO 230-2 standard, carried out in order to adjust the mechanical subassemblies of the machine, which precedes the process of calibrating the machine's control system

Analysis of Positioning Accuracy of Prototype Machine Tools with Hybrid Kinematics

Machine tools with a hybrid kinematic structure represent an unconventional type of machine tools whose characteristics depend on the kinematic configuration. Therefore, it is necessary to perform a separate accuracy analysis for each machine configuration. The analysis of the characteristic values obtained by examining the accuracy of positioning is the starting point for further improvement and calibration of this type of machine. In the case of conventional machine tools with a serial kinematic structure, appropriate standards and recommendations are used to evaluate the state of the machine through testing the positioning accuracy. The paper describes the preliminary measurement of the condition of the machine tool with the hybrid kinematic structure "O-X glide" according to the ISO 230-2 standard, carried out in order to adjust the mechanical subassemblies of the machine, which precedes the process of calibrating the machine's control system

Inverse kinematics of a 5-axis hybrid robot with non-singular tool path generation

This paper deals with non-singular tool path generation of a 5-axis hybrid robot named TriMule, which is designed for large part machining in situ. It is observed that at a singularity pose sudden changes occur in rotation of the C-axis and lengths of three telescopic legs. It is found that when the tool axis rotates about the axis normal to the plane expanded by the tool axis and the singular axis, the singular axis itself is forced to rotate simultaneously about the same axis in the opposite direction. This exploration enables the minimum rotation angle of the tool axis to be determined accurately for avoiding singularity and reducing machined surface errors caused by tool axis modification, leading to the development of an algorithm for non-singular tool path generation by modifying a partial set of the control points of B-splines. Both simulation and experiment on a prototype machine are carried out to verify the effectiveness of this approach

Novel Design and Analysis of Parallel Robotic Mechanisms

A parallel manipulator has several limbs that connect and actuate an end effector from the base. The design of parallel manipulators usually follows the process of prescribed task, design evaluation, and optimization. This dissertation focuses on interference-free designs of dynamically balanced manipulators and deployable manipulators of various degrees of freedom (DOFs). 1) Dynamic balancing is an approach to reduce shaking loads in motion by including balancing components. The shaking loads could cause noise and vibration. The balancing components may cause link interference and take more actuation energy. The 2-DOF (2-RR)R or 3-DOF (2-RR)R planar manipulator, and 3-DOF 3-RRS spatial manipulator are designed interference-free and with structural adaptive features. The structural adaptions and motion planning are discussed for energy minimization. A balanced 3-DOF (2-RR)R and a balanced 3-DOF 3-RRS could be combined for balanced 6-DOF motion. 2) Deployable feature in design allows a structure to be folded. The research in deployable parallel structures of non-configurable platform is rare. This feature is demanded, for example the outdoor solar tracking stand has non-configurable platform and may need to lie-flat on floor at stormy weathers to protect the structure. The 3-DOF 3-PRS and 3-DOF 3-RPS are re-designed to have deployable feature. The 6-DOF 3-[(2-RR)UU] and 5-DOF PRPU/2-[(2-RR)UU] are designed for deployable feature in higher DOFs. Several novel methods are developed for rapid workspace evaluation, link interference detection and stiffness evaluation. The above robotic manipulators could be grouped as a robotic system that operates in a green way and works harmoniously with nature