Bronius Baksys

Alignment of parts in automatic assembly using vibrations

Purpose – The paper aims to investigate theoretically and experimentally vibrational alignment of parts in an assembly position under kinematical excitement of the movably based part.Design/methodology/approach – Presents developed mathematical model for vibrational alignment when the kinematical excitement of movable part is applied along the insertion axis. Dependencies of alignment duration on stiffness of basing elements and excitation frequency were defined numerically solving the mobile‐based part alignment equations. Alignment experiments of rectangular cross‐section and cylindrical parts under kinematical excitement were carried out.Findings – The mathematical model and the experiments have demonstrated that alignment of the parts being assembled happens due to directed displacement of the movable part resulted by certain parameters of the system and excitement. In the course of the displacement, mating surfaces are aligned and the final mutual orientation of the parts before insertion is realized...

Dynamic analysis of vibratory insertion process

Purpose – The paper aims to investigate theoretically and experimentally the process of compliantly supported peg insertion into a bush for high‐speed assembly, when vibrations are provided to the bush in the axial direction, and to analyse the influence of the parameters of the dynamic system and excitation on the assembly process.Design/methodology/approach – The mathematical model of parts vibratory insertion process is formed and the simulation is performed using a numerical computing software environment. The model includes inertia, compliance, dry friction, insertion speed and vibratory excitation. The three‐dimensional simulation of peg‐in‐hole insertion is accomplished using motion analysis software to test the influence of vibratory excitation on assembly failures, such as jamming and wedging. The experimental setup for the robotic vibratory assembly and the investigation methodology were presented. The experimental analysis of the vibratory insertion process of cylindrical parts with clearance i...

Sensorless Vibratory Manipulation of the Automatically Assembled Parts

Presented paper considers the experimental analysis of vibratory manipulation and interdependent alignment of the parts prior to automated assembly. Different values of vibration parameters and parameters of the dynamic system provide possibility to influence the duration of part alignment process. Mating part manipulation on the plane, excited along two perpendicular directions, was also analyzed and different search trajectories were considered.

Modeling of vibrational non-impact motion of mobile-based body

Abstract The paper deals with vibrational non-impact displacement of a mobile-based body on an inclined plane. Two cases are considered: when the body is subjected to kinematical excitement, and when the plane is excited in two perpendicular directions. This phenomenon is used in vibratory assembly devices, where vibration excitement compensates interdependent orientation errors of the components subjected to assembly. Transient and periodic regimes of the body motion from static to dynamic equilibrium are investigated. Dependencies of maximum displacement and average creeping displacement speed upon the elastic resistance force, body pressure to the plane force, the ratio of mutually perpendicular vibration amplitudes, and the phase of these vibrations are presented. The possibilities and conditions of automatic components assembling by applying vibration displacement are characterized.

Peg-bush alignment under elastic vibrations

Purpose – The paper aims to theoretically and experimentally investigate vibratory peg-bush alignment using elastic vibrations of the peg, when the peg is axially excited by a pressed piezoelectric vibrator on the upper end. Design/methodology/approach – Experimental research of part alignment using elastic vibrations was performed and dependencies of alignment duration on excitation signal parameters and initial pressing force were defined for rectangular and circular cross-section parts. Mathematical model of two-mass dynamic systems with elastic contact model representing alignment process was created. Dependencies of system parameters on the alignment duration were obtained by numerically solving systems differential equations. Findings – Theoretical and experimental investigation approved the usage of elastic vibrations for alignment of chamferless circular and rectangular cross-section parts. This novel method of part alignment compensates axial misalignment between mating parts by directional displ...

The vibratory alignment of the parts in robotic assembly

Purpose This paper aims to consider the experimental and theoretical investigation of the vibratory alignment of the peg-hole, when the peg is fixed in the remote centre compliance (RCC) device, and the vibrations are provided either to the hole or to the peg. Design/methodology/approach The experimental analysis of the circular and rectangular peg-hole vibratory alignment using the attached to the robot arm RCC device, under vibratory excitation of the hole, has been performed. The parameters of the vibratory excitation and the part-to-part pressing force influence on the alignment process have been analysed. The mathematical approach of the vibratory alignment using the passive compliance device with the vibrations provided to the peg has been proposed, and the simulation has been carried out. Findings The research has approved the applicability of the RCC device for both of the vibratory alignments of the non-chamfered peg-hole parts either circular or rectangular ones. The compensation of the axial misalignments has been resulted by the directional displacement of the peg supported compliantly. To perform the successful alignment of the parts, it has been necessary to adjust the frequency and the amplitude of the vibrations, the pressing force, the lateral, as well as the angular stiffness of the device. Research limitations/implications The experiments on the vibratory alignment of the rectangular peg-hole parts have been carried out considering only the translational misalignment moved into one direction. The non-impact regime of the vibratory alignment has been analysed. Practical implications The obtained results can be applied in designing the reliable and efficient devices of the vibratory assembly for the alignment of the non-chamfered peg-hole parts, as well as for chamfered ones, if the axial misalignment exceeds the width of the chamfer. The vibratory technique and passive compliance provide possibility to accomplish the assembly operations using the non-expensive low accuracy robots. Originality/value The new method and the mathematical approach of the vibratory assembly using the RCC device can ensure the reliable alignment of the non-chamfered parts, chamfered circular and the rectangular ones, in case the axial misalignment exceeds the assembly clearance, and prevent jamming and wedging.

Experimental Investigation of Vibratory Peg-in-Hole Insertion for Robotic Assembly

The paper aims to experimentally investigate the process of a compliantly supported peg insertion into a bush with clearance by a robot, when vibrations are provided to the bush in the axial direction. The experimental setup of robotic vibratory assembly and the investigation methodology are presented. The experiments were performed by inserting the peg which is attached to a remote center compliance device by a robot into the bush mounted on an electrodynamic shaker. Durations of insertion process stages were measured under various combinations of excitation parameters of the bush. The experiments show that parameters of vibratory excitation have an influence on the duration of insertion process. By selecting suitable excitation parameters it is possible to shorten the insertion process duration and avoid jamming of the parts to be assembled.

Robotic Assembly Using Vibrations

On the basis of the dynamic model of vibratory alignment the main features of the vibrational assembly process are investigated. The regularities of non−impact alignment, when an immovable part is excited in two perpendicular directions, are defined. It is revealed that during the vibrational alignment the movable part can move from static till dynamic equilibrium position. The distance between these two positions defines allowable error of mutual positioning of the parts subject to the assembly, when the unhindered parts insertion is still possible. On the basis of the dynamic model of vibratory displacement the regularities of a body displacement under controlled dry friction force at a particular time interval is examined. If elastic vibrations are excited, dry friction coefficient decreases and smaller friction force acts against the body displacement. Stoppage of these vibrations causes a steep increase of friction coefficient. When the body moves from static to dynamic equilibrium position on the inclined plane the vibratory displacement is governed by the transient regimes of motion. Assembly robots equipped with passive compliance vibratory end-effectors allow one to compensate considerably bigger deviations in part’s interposition without using sensors and feedback systems. Therefore usage of vibratory devices with passive compliance allows one to significantly reduce the expenses of robotic assembly.