Modeling and analysis of servo dynamics errors on measuring paths of five-axis machine tools

Lin, Ming-Tzong; Wu, Shih-Cheng

doi:10.1016/j.ijmachtools.2012.11.002

Cited by 33 publications

(9 citation statements)

References 23 publications

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“…This entails identifying a best suitable feedforward gain for each motion axis, which could become a cumbersome procedure. Lin and Wu [14,15] developed a contour error model on five-axis measuring paths during synchronous motions. An S-shape acceleration/ deceleration was used for the trajectory planning and several tests were conducted to investigate how contour charts of the tool center point are affected by the dynamic gains of five-axis servo loops.…”

Section: Related Workmentioning

confidence: 99%

Development of an analyzing and tuning technology for improving circularity of cone-frustum motions of five-axis CNC machine tools

Hidalgo

Yeh

2018

Int J Adv Manuf Technol

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The machining of a cone frustum as specified on the ISO 10791-7 standard is a widely accepted test to evaluate the performance of five-axis machining centers. By measuring the cross-sectional circularity of the cone, the contouring accuracy of a five-axis CNC machine tool can be assessed. A reduction of circularity is directly related to the improvement of the contouring accuracy in circular motions. The contouring accuracy can also be assessed by measuring the circularity of the circular motion path described by the tool center point of a five-axis CNC machine tool. A better circular tool center path entails an enhancement on the circularity of the traversal sections of the cone frustum. The majority of CNC actuators are AC servomotors that are precisely controlled via two closed loops: one for position and one for velocity. The circular contouring accuracy of a five-axis CNC machine tool can be improved by adjusting the loop gains and time constant of the velocity loop integration. Although higher gains enable the servomotors to attain the desired positions faster, the resulting contouring accuracy may not be satisfactory. Furthermore, excessively high gains could cause vibrations. The objective of this research is to establish a frequency domain approach for tuning the control parameters for each motion axis such that their frequency responses are matched within a range of frequencies, reducing the circularity value of the cross sections of a cone frustum. Results demonstrate the effect of tuning the control loop parameters based on the frequency response of each axis. Case studies were conducted to determine the variation in the circularity value when the control parameters of each axis were tuned to obtain similar frequency responses to the linear and rotary axes within a frequency range. Rates of improvement greater than 80% were achieved after using the proposed method to tune the control parameters of each motion axis.

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Section: Related Workmentioning

confidence: 99%

Development of an analyzing and tuning technology for improving circularity of cone-frustum motions of five-axis CNC machine tools

Hidalgo

Yeh

2018

Int J Adv Manuf Technol

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“…If dL is small enough, the geometric errors of the machine tool at the same pose in both setups are nearly the same. In this condition, the difference between ~ pu1 in the 1 st p2 in the 2 nd setup can be calculated as follows: (9) where, p0 is the initial position of TCP, A0 and C0 are the initial rotation angels of the cutter in w-CS respectively; X0, Y0, Z0are the initial positions of X, Y and Z axes in the 1 st setup, X1, Y1, Z1 are the positions of X, Y and Z axes at pose 1 in the 1 st setup. From Eq.…”

Section: Errors Inspection By R-testmentioning

confidence: 99%

“…Tracking errors are calculated based on the model provided by Ref. [9]. The other errors are randomly generated from the given range.…”

Section: Case Studymentioning

confidence: 99%

Energy-Efficient Cutting Parameters Determination for NC Machining with Specified Machining Accuracy

Liu

Wang

2017

Procedia CIRP

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An energy-efficient cutting parameters determination method for NC machining parts with specified machining accuracy is proposed in this paper. The identification mechanism of machine tool errors by R-test is employed to establish machining error estimation model. By replacing the coordinate of each tool path point with the origin, the R-test tool paths are generated. R-tests at two different setups are designed to capture the volumetric errors of the machine tool. After dynamic R-test simulations at different feedrates in two setups, the volumetric errors of the machine tool at different feedrates are predicted. With the volumetric errors, the maximum machining errors of the part at different feedrates are calculated based on the machining error estimation model. The allowed feedrate range is obtained by comparing the calculated machining errors with the specified machining accuracy. With the allowed feedrate range and the other cutting parameters as the factors, the response surface of total energy consumption of machine tool is constructed according to the requirements of machining operations. The energy-efficient cutting parameters combination is found by searching the constructed response surface. A typical aircraft structural part is used to validate the proposed method.

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“…Sencer et al [14] proposed a multi-input multi-output (MIMO) sliding mode controller to simultaneously minimize the tool tip contour error and the tool orientation contour error. With the assistance of servo dynamics errors modeling method [15], Lin et al [16] proposed a servo dynamics matching approach to improve the TCP contouring accuracy of fiveaxis machines. In our most recent work [17], a generalized on-line five-axis contouring error control approach was proposed, where the estimated axis components were added to the position commands of each closed-loop of servo drivers to realize the on-line contouring error control.…”

Section: Introductionmentioning

confidence: 99%

“…A common control structure of the aforementioned contouring error control algorithms [13][14][15][16][17] is feedback control based on online estimation. Evidently, control action always lags behind the error because control signals are calculated according to previous errors.…”

Section: Introductionmentioning

confidence: 99%

Contouring error control of the tool center point function for five-axis machine tools based on model predictive control

Yang

Zhang

Ding

2016

Int J Adv Manuf Technol

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In five-axis machining processes, tool center point (TCP) control is often used to adjust the orientation of the ball end milling while maintaining constant tool center point coordinates in the workpiece frame. Therefore, TCP contouring error decreases the quality of the machined surface, but very few efforts have been made so far to minimize the contouring error of five-axis TCP by feedback control. To this end, a model predictive control (MPC) method is developed here for rolling optimization. More precisely, the contouring error model of five-axis TCP function is developed, where a Jacobian matrix is used to approximate the relationship between the contouring error and five drivers' tracking errors. The MPC algorithm is afterwards derived, where constraints of control signals are considered as well to avoid violation of the power limitation of the drivers. Finally, the proposed MPC method is examined by extensive experiments using testing tool path of ISO 10791-6: 2014 to verify its effectiveness and superiority.

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Modeling and analysis of servo dynamics errors on measuring paths of five-axis machine tools

Cited by 33 publications

References 23 publications

Development of an analyzing and tuning technology for improving circularity of cone-frustum motions of five-axis CNC machine tools

Development of an analyzing and tuning technology for improving circularity of cone-frustum motions of five-axis CNC machine tools

Energy-Efficient Cutting Parameters Determination for NC Machining with Specified Machining Accuracy

Contouring error control of the tool center point function for five-axis machine tools based on model predictive control

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