Control of Linear Motors for Machine Tool Feed Drives: Design and Implementation of H∞ Optimal Feedback Control

1996 ◽  
Vol 118 (4) ◽  
pp. 649-656 ◽  
Author(s):  
D. M. Alter ◽  
Tsu-Chin Tsao
Keyword(s):  
Machine Tool ◽  
Closed Loop ◽  
Force Feedback ◽  
Dynamic Stiffness ◽  
Tracking Performance ◽  
Optimal Feedback Control ◽  
Optimal Position ◽  
Linear Motors ◽  
Feed Drives ◽  
Position Feedback

Direct drive linear motors have good potential for use as next generation machine tool feed drives since they can increase machining rates and improve servo accuracy by eliminating gear related mechanical problems. To exploit the high speed and high response direct drives for machining, the servo control must achieve as high as possible tracking performance while at the same time establishing as much as possible the dynamic stiffness in order to maintain machining stability and reduce the effect of machining disturbance forces on the tool position. This paper investigates the use of optimal H∞ control to design for large stiffness and closed-loop tracking performance. Position feedback alone is first considered, with cutting force feedback later added to augment closed loop stiffness. Optimal position feedback is experimentally seen to achieve up to a 46 percent stiffness improvement over that achievable with proportional-derivative control. The addition of force feedback to the servo-loop resulted in a further 70 to 100 percent stiffness improvement over the position feedback alone values.

Control of Linear Motors for Machine Tool Feed Drives: Experimental Investigation of Optimal Feedforward Tracking Control

1998 ◽  
Vol 120 (1) ◽  
pp. 137-142 ◽  
Author(s):  
David M. Alter ◽  
Tsu-Chin Tsao
Keyword(s):  
Closed Loop ◽  
Reference Model ◽  
Feedforward Control ◽  
Tracking Performance ◽  
Motor Drive ◽  
Tracking Errors ◽  
Linear Motors ◽  
Closed Loop Systems ◽  
Feed Drives ◽  
Integral Action

This paper investigates the use of optimal l1 and H∞ model reference optimal feedforward control to enhance the tracking performance of a linear motor drive. Experimental work is presented which studies the effects of signal preview, tracking constraint, and reference model choice on tracking performance. Suboptimal l1 control where the closed-loop system has a zero on the unit circle due to integral action in the feedback controller is given special attention, and is seen to give near optimal performance for the system under study here. For the specific trajectory employed here, the best performing feedforward controllers were experimentally seen to reduce by more than half the maximum and rms tracking errors of the H∞ optimal feedback closed-loop systems.

Modeling and Synchronous Control of Dual Mechanically Coupled Linear Servo System

2014 ◽  
Vol 137 (4) ◽  
Author(s):  
Wu-Sung Yao
Keyword(s):  
Machine Tool ◽  
High Speed ◽  
Dynamic Stiffness ◽  
System Modeling ◽  
Coupled System ◽  
Mechanical Coupling ◽  
Synchronous Control ◽  
Linear Motors ◽  
Operation Speed ◽  
Control Scheme

This paper presents a system modeling technique for a high-speed gantry-type machine tool driven by linear motors. One feed axis of the investigated machine tool is driven by the joint thrust from two parallel linear motors. These two parallel motors are coupled mechanically to form the Y-axis while another standalone motor fixed to a support forms the X-axis. The components in the X-axis, which is treated as the mechanical coupling, are carried by the slides of the Y-axis motors. This configuration is applied to improve the dynamic stiffness of the system and operation speed/acceleration. However, the precise synchronous control of the two parallel and coupled motors would be the major challenge. To overcome this challenge, a multivariable system identification method is developed in this paper. This method is used to construct an accurate system mathematical model for the target coupled system. A synchronous control scheme is then applied to the model obtained using the proposed technique. The performance of the system is experimentally verified with a high-speed S-curve motion profile. The results substantiate the constructed system model and demonstrate the effectiveness of the control scheme.

Stability of Turning Processes with Actively Controlled Linear Motor Feed Drives

1994 ◽  
Vol 116 (3) ◽  
pp. 298-307 ◽  
Author(s):  
D. M. Alter ◽  
Tsu-Chin Tsao
Keyword(s):  
Dynamic Stiffness ◽  
Sufficient Conditions ◽  
Machining Process ◽  
System Stability ◽  
Dynamic Feedback ◽  
Machining Performance ◽  
Linear Motors ◽  
Feed Drives ◽  
The Stability ◽  
Necessary And Sufficient

Using linear motors as machine tool feed drives has the potential of enhancing machining performance by eliminating gear related mechanical problems and increasing speed and accuracy, but introduces a stability concern due to a strong dynamic feedback interaction between the machining process and the drives. This paper investigates the stability aspect of this dynamic interaction and the use of active damping to achieve machining stability in turning. Various necessary and sufficient conditions for stability at all cutting speeds are derived, and have been used to study the effect of damping and gear reduction in system stability. The interaction of the cutting process with the tool servo loop is seen to have significant instability consequences in systems with small drive gear reductions. Both theoretical stability and experimental cutting results are presented for PD and PID regulation. Results show that actively controlled linear motors can provide sufficient dynamic stiffness for stable turning operation.

Improvement of horizontal borer control system

2020 ◽  
Vol 2020 (7) ◽  
pp. 41-48
Author(s):  
Dmitriy Petreshin ◽  
Viktor Khandozhko ◽  
Andrey Dubov ◽  
German Dobrovolsky
Keyword(s):  
Control System ◽  
Machine Tool ◽  
Feed Drive ◽  
Feed Drives ◽  
System Improvement

The control system improvement of a machine-tool is considered. The necessity in control system updating is substantiated. There is shown a procedure for horizontal borer updating. A problem on adjustment of modern digital electrical feed drives is presented. A sample of electrical feed drive and NC device adjustment is presented.

Linear electric motors in feed drives of multi-purpose machine tools

2020 ◽  
pp. 47-52
Author(s):  
A.A. Mahov ◽  
O.G. Dragina ◽  
P.S. Belov ◽  
S.L. Mahov
Keyword(s):  
Electric Motor ◽  
Machine Tools ◽  
Electric Motors ◽  
Linear Motors ◽  
Machining Center ◽  
Feed Drives ◽  
Selection Of

The possibility of using linear feed drives along the X and the Y axes in the portal-milling machining center is shown. The calculations of force indicators of drives, feed drives of traverse and carriage for two modes, as well as the selection of Siemens linear motors are given. Keywords milling machining center, drive, feed, linear electric motor. [email protected]

scholarly journals Double Closed-Loop Compound Control Strategy for Magnetic Liquid Double Suspension Bearing

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1195
Author(s):  
Jianhua Zhao ◽  
Yongqiang Wang ◽  
Xuchao Ma ◽  
Sheng Li ◽  
Dianrong Gao ◽  
...  
Keyword(s):  
Control Strategy ◽  
Electromagnetic Force ◽  
Closed Loop ◽  
Static Characteristic ◽  
Magnetic Liquid ◽  
Initial Current ◽  
Electromagnetic System ◽  
Initial Flow ◽  
Hydrostatic Force ◽  
Position Feedback

As a new type of suspension bearing, the magnetic liquid double suspension bearing (MLDSB) is mainly supported by electromagnetic suspension and supplemented by hydrostatic support. At present, the MLDSB adopts the regulation strategy of “electromagnetic-position feedback closed-loop, hydrostatic constant-flow supply” (referred to as CFC mode). In the equilibrium position, the external load is carried by the electromagnetic system, and the hydrostatic system produces no supporting force. Thus, the carrying capacity and supporting stiffness of the MLDSB can be reduced. To solve this problem, the double closed-loop control strategy of “electromagnetic system-force feedback inner loop and hydrostatic-position feedback outer loop” (referred to as DCL mode) was proposed to improve the bearing performance and operation stability of the MLDSB. First, the mathematical models of CFC mode and DCL mode of the single DOF supporting system were established. Second, the real-time variation laws of rotor displacement, flow/hydrostatic force, and regulating current/electromagnetic force in the two control modes were plotted, compared, and analyzed. Finally, the influence law of initial current, flow, and controller parameters on the dynamic and static characteristic index were analyzed in detail. The results show that compared with that in CFC mode, the displacement in DCL mode is smaller, and the adjustment time is shorter. The hydrostatic force is equal to the electromagnetic force in DCL mode when the rotor returns to the balance position. Moreover, the system in DCL mode has better robustness, and the initial flow has a more obvious influence on the dynamic and static characteristic indexes. This study provides a theoretical basis for stable suspension control and the safe and reliable operation of the MLDSB.

Researches Regarding the Use of Fuzzy Controllers within CNC Feed Drives

2015 ◽  
Vol 772 ◽  
pp. 229-234
Author(s):  
Radu Eugen Breaz ◽  
Octavian Bologa
Keyword(s):  
Machine Tool ◽  
Fuzzy Controller ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Fuzzy Controllers ◽  
Feed Drive ◽  
Feed Drives ◽  
Simulation Based ◽  
Position Controller ◽  
Dc Servomotor

This paper presents some simulation based upon a dynamic model of a feed-drive within the structure of a CNC machine tool. A DC servomotor was considered as actuation device for the feed drive. For a given set of parameters for the position controller, two fuzzy types of fuzzy controllers were tested by means of simulation. The first fuzzy controller was a proportional one, with one input and one output, while the second one was a two variables one, with two inputs and one outputp.

The Determination of the Three-Point Support Design of Machine Tool Based on iSIGHT

2014 ◽  
Vol 607 ◽  
pp. 342-345
Author(s):  
Sheng Hui Zhao ◽  
Xiao Chuang Zhu ◽  
Da Wei Zhang
Keyword(s):  
Machine Tool ◽  
High Precision ◽  
Multidisciplinary Optimization ◽  
Joint Surface ◽  
Objective Functions ◽  
Multi Objective Optimization ◽  
Support Design ◽  
Optimal Position ◽  
Point Support

In order to meet the requirements of high-precision machine tool, it has been an important factor to select an appropriate way to support the bed. By building a multidisciplinary optimization (MDO) process based on iSIGHT, this article select the deformation difference of the guides and the deformation difference of the joint surface between column and bed of the machine tool as the objective functions, and then conduct a multi-objective optimization (MOO) of the positional parameters of the three-point support. Eventually the optimization result is given and the optimal position of the three-point support is determined.

Dynamic Analysis of Helical Milling Unit Based on Virtual Machine Tool

2011 ◽  
Vol 188 ◽  
pp. 463-468 ◽  
Author(s):  
Xu Da Qin ◽  
Qi Wang ◽  
H.Y. Wang ◽  
Song Hua
Keyword(s):  
Machine Tool ◽  
Virtual Machine ◽  
Dynamic Stiffness ◽  
Three Dimensional ◽  
Geometrical Model ◽  
Helical Milling ◽  
Response Analysis ◽  
Computer Simulation Model ◽  
Element Analysis ◽  
Virtual Machine Tool

The virtual prototype is a computer simulation model of the physical product that can be analyzed like a real machine. This paper studies the helical milling unit based on the virtual machine tool. The helical milling unit is first designed according to the kinematics of the helical milling. The main parts of the equipment include rotating mechanism, orbital agency and radial offset organization. Based on the feasibility analysis of the structure, the three-dimensional geometrical model is built in the Solidworks software. The key parts in the model are separated from the device and introduced into the finite element analysis (FEA) software, according to the cutting loads tested from experiment, static and dynamic modal analysis and harmonic response analysis are carried out for the key parts of this device. The results show that the static and dynamic stiffness can meet design requirement.

Backlash Compensation on CNC Machine Tool Based on Semi-Closed Loop Control

2011 ◽  
Vol 346 ◽  
pp. 644-649 ◽  
Author(s):  
Bin Feng ◽  
Xue Song Mei ◽  
Liang Guo ◽  
Dong Sheng Zhang ◽  
You Long Cheng
Keyword(s):  
Machine Tool ◽  
Closed Loop ◽  
Closed Loop Control ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Positional Accuracy ◽  
Loop Control ◽  
Open Cnc ◽  
Contouring Error ◽  
Open Cnc System

The positional accuracy and machining precision are mainly affected by backlash for semi-closed loop control CNC machine tool. And compensation for backlash is essential to improving the accuracy of machine tool. A method is developed to reduce contouring error in this paper. A simulated model of backlash and Open CNC system are used to verify compensation algorithm. Computational simulations and experimental results have shown that the contouring error due to backlash can be greatly reduced by using backlash compensation.

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