• Journal of the Korean Society for Precision Engineering
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• v.33 no.9
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• pp.745-751
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• 2016

This paper presents the acceleration and deceleration control of free-form surfaces. A rapid variation of acceleration (or Deceleration) drives the system into a machine shock, resulting in the inaccuracy of the path control of the NURBS curve. The pattern of acceleration control can be established using the curvature of the NURBS curve. The curvature can be easily calculated from the first and second derivative of the NURBS curve used in Taylor's expansion for NURBS interpolation. However, the derivatives are not used in the recursive method for NURBS interpolation. Hence, we attempted the difference-derivatives for calculating the NURBS curvature. Both, Taylor's expansion and the recursive method, are used jointly for controlling the acceleration in the same interpolation algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1904-1909
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• 1991

Software linear and exponential acceleration/deceleration algorithms for control of machine axes of motion in industrial robots and CNC machine tools are proposed. Typical hardware systems used to accelerate and decelerate axes of motion are mathematically analyzed. Discrete-time state equations are derived from the mathematical analyses for the development of software acceleration/deceleration algorithms. Synchronous control method of multiple axes of motion in industrial robots and CNC machine tools is shown to be easily obtained on the basis of the proposed acceleration/deceleration algorithms. The path error analyses are carried out for the case where the software linear and exponential acceleration/deceleration algorithms are applied to a circular interpolator. A motion control system based on a floating point digital signal processor (DSP) TMS 320C30 is developed in order to implement the proposed algorithms. Experimental results demonstrate that the developed algorithms and the motion control system are available for control of multiple axes and nonlinear motion composed of a combination of lines and circles which industrial robots and CNC machine tools require.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.11
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• pp.221-227
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• 2002

Tapping is a machining process that makes a female screw on parts to be assembly together. Recently, as the number of small and compact products increases the radius of tap as small as 1 mm is not unusual and more accurate tapping is needed. In complying with those needs, some high-speed tapping machines with synchronizing function have been developed. This paper describes the development of an ultra high-speed tapping machine up to 10,000rpm. The key factors in the tapping speed are the acceleration/deceleration and the synchronizing errors between spindle motor and fred motor. To minimize the acceleration/deceleration time, a low inertia spindle with a synchronous built-in servo motor was developed. To minimize the synchronizing errors, the tapping cycle algorithm was optimized on an open architecture CNC. The developed tapping machine has the acceleration/deceleration time of 0.13sec/10,000rpm for rigid tapping and the synchronizing error below 4.4%. The cycle time for tapping a female screw of M3 and depth 2 times diameter was 0.55sec.

• The Journal of Korea Robotics Society
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• v.12 no.3
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• pp.279-286
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• 2017

In this paper, we proposed a method to determine the acceleration/deceleration time of the motion for reducing the residual vibration caused by the resonance of the robot in the high-speed motion. The relationship between the acceleration/deceleration time and the residual vibration was discussed for the trapezoidal velocity profile by analyzing the time when the jerk happens. The natural frequency of the robot can be estimated in advance through the dynamics simulation. The simulation and experiment for both cases where the moving distance of the robot is long enough and the distance is short, are implemented in the 1-DOF linear robot. Simulation and experimental results show that when the acceleration/deceleration time is a multiple of the vibration period, the settling time and the amplitude of the residual vibration become less than when the time is not a multiple.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.5
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• pp.15-28
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• 1998

Recently may investigations have been studied on the high-speed machining by using machine tools. A CNC machine tool makes some tool path errors caused by software acceleration/deceleration. The faster a cutting feedrate is, the bigger the tool path errors are. Some known methods reduce these kinds of errors, but they make the total cutting time increased. This paper presents a feed-forward algorithm that can be generated by distorting the original tool path, and reduces the tool path errors and the total cutting time. The algorithm to generate a new tool path is represented as following; 1)calculating each distance of software acceleration/deceleration between two adjacent blocks, 2) estimating the distorted distance which is the adjacent-ratio-constant(k1, k2) multiply the distance of software acceleration/deceleration, 3) generating a 3-degree Bezier curve approximating the distorted tool path, 4) symmetrically transforming the Bezier curve about the intersection point between two blocks, and 5) connecting the transformed Bezier curve with the original tool path. The algorithm is applied to FANUC 0M. The study is to promote the high-precision machining and to reduce the total cutting time.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.1
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• pp.89-94
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• 2013

Electro Otical Tracking System(EOTS) is required for a rapid movement as well as the stabilization of Line-Of-Sight(LOS). In order to achieve these two goals, this paper presents a position and velocity driving profile generation method from the constant acceleration and deceleration profile according to the current state, enabling a fast and smooth trajectory even if the target position changes during the movement of LOS. Simulation and experimental results reveal that the settling time could be reduced significantly by adopting the present position control scheme.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.3
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• pp.304-312
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• 1999

In order to make industrial robots and CNC machine tools perform tasks efficiently, each axis has to be accelearated and decelerated appropriately. The existing techniques for the acceleration and deceleration of industrial robots and CNC machine tools are not efficient to generate velocity profiles. Thus, these previous techniques cannot generate velocity generating velocity profiles that cannot be generated by them. Based on the proposed approach, an acceleration and deceleration circuit for industrial robots and CNC machine tools is designed with a FPGA by using the VHDL.

• Journal of information and communication convergence engineering
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• v.8 no.1
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• pp.95-98
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• 2010

The Electro Magnetic (EM) Acceleration and Deceleration (ACC/DCC) system of the Ferromagnetic Ball(FB) is the linear motor's final structural development which can be used for devices that conserve energy, gaming or rail gun. By accelerating the FB within the coil structure, it is difficult to utilize the FB's magnetizing feature via the ACC/DCC system. There is much monopole space inside the monopole coil. By using this particular feature of the FB, starting coil and Monopole Coil Structure (MCS) can be structurally separated and another simple electric related control system can be experimented for further development. For the purpose of development a review is needed of the control system of both basic stepper motor and BLDC motor.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.9
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• pp.52-60
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• 1997

This paper proposes the effective method of the software based motion control by using lenear, exponential and bell type discrete filters for acceleration and deceleration of servo motors. Recursive filters are designed in discrete time domain which can reduce computation time and vibration of motors due to load disturbance. Also it deals with the method which decides the time constants of filters when a machine tool is driven at rapid, cutting and jog feedrate. Validity of the proposed method is verified by corner cutting experiments.

• Tribology and Lubricants
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• v.36 no.1
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• pp.39-46
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• 2020

Air stages are usually applied to precision engineering in sectors such as the semiconductor industry owing to their excellent performance and extremely low friction. Since the productivity of a semiconductor depends on the acceleration and deceleration performance of the air stage, many attempts have been made to improve the speed of the stage. Even during sudden start or stop sequences, the stage should maintain an air film to avoid direct contact between pad and the rail. The purpose of this study is to quantitatively predict the dynamic behavior of the air stage when acceleration and deceleration occur. The air stage is composed of two parts; the stage and the guide-way. The stage transports objects to the guideway, which is supported by an externally pressurized gas bearing. In this study, we use COMSOL Multiphysics to calculate the pressure of the air film between the stage and the guide-way and solve the two-degree-of-freedom equations of motion of the stage. Based on the specified velocity conditions such as the acceleration time and the maximum velocity of stage, we calculate the eccentricity and tilting angle of the stage. The result shows that the stiffness and damping of the gas bearing have non-linear characteristics. Hence, we should consider the operating conditions in the design process of an air stage system because the dynamic behavior of the stage becomes unstable depending on the maximum velocity and the acceleration time.