• 한국CDE학회논문집
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• 제14권5호
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• pp.291-296
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• 2009

This paper presents a post-processing algorithm for 5-axis machines with three rotary axes (3R-2L type). 5-axis machining needs the postprocessor for converting cutter location (CL) data to machine control (NC) data. The existing methods for post-processing use inverse kinematics equations from for-ward kinematics. However in case of 5-axis machines with three rotary axes, the inverse kinematics equations are not induced directly since the forward kinematics equations are non-linear. In order to get the joint values from the forward kinematics equations, previous algorithms use numerical method for the post-processing, which needs searching algorithms with computation time and may result in fail. This paper proposes a geometric method for the post-processing of 3 rotary type 5-axis machines. Our algorithm has three advantages: first, it does not need establishing forward kinematics equations. Second, it is reliable method that eliminates any numerical methods for the inverse kinematics, resulting in the exact solution. Finally, the proposed algorithm can also be applied to 2R-3L type of 5-axis machines.

• Restorative Dentistry and Endodontics
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• 제47권2호
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• pp.22.1-22.18
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• 2022

Objectives: This systematic review (register-osf.io/wg7ba) compared the efficacy and safety of rotary and reciprocating kinematics in the removal of filling material from curved root canals. Materials and Methods: Only in vitro studies evaluating both kinematics during retreatment were included. A systematic search (PubMed/MEDLINE, Scopus, and other databases, until January 2021), data extraction, and risk of bias analysis (Joanna Briggs Institute checklist) were performed. Efficacy in filling removal was the primary outcome. Results: The search resulted in 2,795 studies, of which 15 were included. Efficacy was measured in terms of the remaining filling material and the time required for this. Nine studies evaluated filling material removal, of which 7 found no significant differences between rotary and reciprocating kinematics. Regarding the time for filling removal, 5 studies showed no difference between both kinematics, 2 studies showed faster results with rotary systems, and other 2 showed the opposite. No significant differences were found in apical transportation, centering ability, instrument failure, dentin removed and extruded debris. A low risk of bias was observed. Conclusions: This review suggests that the choice of rotary or reciprocating kinematics does not influence the efficacy of filling removal from curved root canals. Further studies are needed to compare the kinematics safety in curved root canals.

• 한국정밀공학회지
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• 제32권1호
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• pp.89-96
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• 2015

In this paper, it is studied that kinematic analysis of a 5-axis ultrasonic inspection equipment. The equipment is comprised of three straight axes and two rotary axes. With features of ultrasonic, the transmitter and receiver of the equipment are vertical to a test surface, operating at regular intervals. To perform this well, the motions of every link should be found on the based of kinematic analysis of the equipment. We chose starting point for testing and defined relations among all links through transformation of coordinates. For double curvature-shaped test object, we generated test paths. To follow these, we found motions of all links using inverse kinematics. By using Matlab/Simulink, simulator was developed, so that we could find out desired trajectories of main axes for a scan.

• International Journal of Aeronautical and Space Sciences
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• 제13권1호
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• pp.90-98
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• 2012

In this paper, the Integrated Guidance and Control (IGC) law is proposed for the Rotary Unmanned Aerial Vehicle (RUAV). The objective of the IGC law is to consider the nonlinear dynamic characteristics of the RUAV and to design a guidance law which takes into consideration the nonlinear relationship between kinematics and dynamics. In order to control the RUAV system, sliding mode control scheme is adopted. As the RUAV is an under-actuated system, a slack variable approach is used to generate the available control inputs. Through the Lyapunov stability theorem, the stability of the proposed IGC law is proved. In order to verify the performance of the IGC law, numerical simulations are performed for waypoint tracking missions.

• 한국기계가공학회지
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• 제10권2호
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• pp.9-15
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• 2011

In order to develop a practical postprocessor for 5-axis machining, the general equations of numerically controlled (NC) data for 5-axis configurations with not only non-orthogonal rotary axes but also orthogonal rotary axes were exactly expressed by the inverse kinematics, and a Windows-based postprocessor written in Visual Basic was developed according to the proposed algorithm. The developed postprocessor is a general system that suitable for all kinds of 5-axis machine tool with orthogonal and non-orthogonal rotary axes. Through implementation of the developed postprocessor and verification by a cutting simulation and machining experiment, the effectiveness of the proposed algorithm is confirmed. Compatibility is improved by allowing exchange of data formats such as rotational tool center position (RTCP) controlled NC data, vector post NC data, and program object file (POF) cutter location (CL)data, and convenience is increased by adding the function of work-piece origin offset. Consequently, the technology of practical post-processor for 5-axis machining is developed.

• 한국산업융합학회 논문집
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• 제23권5호
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• pp.875-880
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• 2020

In this paper, a novel 3-DOF hybrid robot with enlarged workspace is presented for high speed applications. The 3-DOF hybrid robot is made up of one linear actuator and 2-DOF planar parallel robot in series. The actuation consists of one ball-screw to make one linear motion and two rotary ball-screws to transmit rotational motion to 2-DOF parallel robot. The workspace can be enlarged according to ball-screw stroke and the moving inertia can be reduced due to locating all the heavy actuators at the fixed base. The inverse kinematics and workspace analyses are presented. The robot prototype and PC-based control system are developed.

• 한국CDE학회논문집
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• 제6권2호
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• pp.69-77
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• 2001

This paper describes a method of calculating the feedrate for the constant cutting speed at a CL-point in 5-axis machining. Unlike 3-axis machining, 5-axis machining has the flexibility of the tool motions due to two rotation axes. But the feedrate at joint space differs from the feedrate at a tool tip(the CL-point) of the 3D Euclidean space for the tool motions. The proposed algorithm adjusts the feedrate based on 5-axis NC data, the kinematics of a machine, and the tool length. The following calculations is processed for each NC block to generate the new feedrate; 1) calculating the moving distance at the CL-point, 2) calculating the moving time by the given feedrate, 3) calculating the feedrate of each axis, 4) getting the new feedrate. The proposed algorithm was applied to a 5-axis machine which had a tilting spindle and a rotary table. Totally, the result of the algorithm reduced the machining time and smoothed the cutting-load by the constant cutting speed at the CL-point.

• 한국CDE학회논문집
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• 제14권1호
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• pp.18-24
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• 2009

This paper proposes an analytical method of evaluating the maximum error by modeling the exact tool path for the tool traverse singular region in five-axis machining. It is known that the NC data from the inverse kinematics transformation of 5-axis machining can generate singular positions where incoherent movements of the rotary axes can appear. These lead to unexpected errors and abrupt operations, resulting in scoring on the machined surface. To resolve this problem, previous methods have calculated several tool positions during a singular operation, using inverse kinematics equations to predict tool trajectory and approximate the maximum error. This type of numerical approach, configuring the tool trajectory, requires much computation time to obtain a sufficient number of tool positions in a region. We have derived an analytical equation for the tool trajectory in a singular area by modeling the tool operation into a linear and a nonlinear part that is a general form of the tool trajectory in the singular area and that is suitable for all types of five-axis machine tools. In addition, we have evaluated the maximum tool-path error exactly, using our analytical model. Our algorithm can be used to modify NC data, making the operation smoother and bringing any errors to within tolerance.

• 로봇학회논문지
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• 제12권2호
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• pp.184-193
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• 2017

This work shows how to create an algorithm and implementation for motion and image matching between a vehicle simulator and Unity 3D based virtual object. The motion information of the virtual vehicle is transmitted to the real simulator via a RS232 communication protocol, and the motion is controlled based on the inverse kinematics solution of the platform adopting rotary-type six actuators driving system. Wash-out filters to implement the effective motion of the motion platform are adopted, and thereby reduce the dizziness and increase the realistic sense of motion. Furthermore, the simulator system is successfully designed aiming to reducing size and cost with adaptation of rotary-type six actuators, real driving environment via VR (Virtual Reality), and control schemes which employ a synchronization between 6 motors and 3rd order motion profiles. By providing relatively big sense of motion particularly in impact and straight motions mainly causing simulator sickness, dizziness is remarkably reduced, thereby enhancing the sense of realistic motion.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2290-2295
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• 2005

In this paper, it is developed simulator system of 3 D.O.F parallel robot for educate of expertness. This simulator system is composed of three parts ? 3 D.O.F parallel robot, controller (hardware) and software. First, basic structure of the robot is 3 active rotary actuator that small geared step motor with fixed base. An input-link is connected to this actuator, and this input-link can connect two ball joints. Thus, two couplers can be connected to the input-link as a pair. An end-plate, which is jointed by a ball joint, can be connected to the opposite side of the coupler. A sub-link is produced and installed to the internal spring, and then this sub-link is connected to the upper and bottom side of the coupler in order to prevent a certain bending or deformation of the two couplers. The robot has the maximum diameter of 230 mm, 10 kg of weight (include the table), and maximum height of 300 mm. Hardware for control of the robot is composed of computer, micro controller, pulse generator, and motor driver. The PC used in the controller sends commands to the controller, and transform signals input by the user to the coordinate value of the robot by substituting it into equations of kinematics and inverse kinematics. A controller transfer the coordinate value calculated in the PC to a pulse generator by transforming it into signals. A pulse generator analyzes commands, which include the information received from the micro controller. A motor driver transfer the pulse received from the pulse generator to a step motor, and protects against the over-load of the motor Finally, software is a learning purposed control program, which presents the principle of a robot operation and actual implementation. The benefit of this program is that easy for a novice to use. Developed robot simulator system can be practically applied to understand the principle of parallel mechanism, motors, sensor, and various other parts.