1 Introduction The super-precision machine tool servo feed system is the most critical part of ultra-precision machine tools. It directly determines the machine tool's machining precision surface quality and productivity. In the ultra-precision machine tool servo system, the ball screw is used as the servo drive mechanism. The nonlinear effect of the gap between the lead screw and the nut pair may cause the limit loop of the servo system to be generated, or even unstable, which greatly affects the performance of the servo system. Therefore, in order to design a high-precision servo system, this paper has studied A method of rationally designing the controller to eliminate the nonlinear effects of the gap.
2The composition of the system and the conventional control method exist. The super-precision machine tool servo feed system realizes the position servo feed by the AC servo motor + ball screw, realizes the position detection by the dual-frequency laser interferometer, and adopts the air static pressure guide rail and the air floatation work. The platform reduces the influence of friction during the transmission process, and realizes the closed-loop speed regulation of the motor by adopting the AC servo drive unit matched with the motor, and the speed loop adopts a type regulator. Among them, the generation moment constant in the speed loop is 1 position in the servo servo, and the dynamic model of the same service system has a high frequency response, which is used as a proportional link, which is an input signal and outputs the position of the station. In the modeling, the high-frequency oscillation mode that may exist in the workbench is treated as the unmodeled dynamic characteristic to obtain the system-measured model, and the system is identified by the frequency method. The system linear part open-loop transfer function is obtained as the system cage system. ,name. Regardless of the gap, the design of such a system can be attributed to how the system is designed into a wide bandwidth and high stiffness system to ensure a fast response speed and strong anti-interference ability. The form of the controller, due to the pure integral link in 08, the system's static servo stiffness is infinite, so that the system can effectively suppress the influence of step interference torque on the shaft. The better damping characteristics of the system can be obtained by adjusting the parameters to obtain a compromise between the response speed noise error and the unmodeled dynamic characteristic controller. In order to apply this controller to the closed-loop system, the description function method is used to analyze the wooden system 4! The system linear link, 4, the curve of the curve 1 and the negative reversal of the gap link are drawn. The two curves intersect!
The point is controlled by the nonlinear control theory. The 3rd generation actually exists in the right 2 controller of the plant system. The gap nonlinear link will cause the system to produce steady state error.
The system has better dynamic response characteristics. Only through the change of the product, the structure of the system, and the reasonable design of the controller, the curve of the curve is 2 curve 2 of the curve 2. The person has no intersection, and the small system has no self-sustaining oscillation.
3 Improved design of dual-loop controller Because the proportional+integral control method does not consider the influence of the gap, the system will generate self-sustaining vibration and be known by the nonlinear control theory. If the system is type, self-sustaining oscillation can be avoided. However, the bandwidth of the type system is limited, and it is difficult to design a high-stiffness system to suppress the interference. To solve this kind of spear, the text is designed to be a wide-bandwidth fast-breaking loop to suppress the interference; and the position loop is designed to be narrow. Bandwidth type system When the bandwidth of the speed loop is designed to be more than 5 times the bandwidth of the position loop, the influence between the two loops becomes weak, so that the system can be approximated as the type system. The bandwidth of the position loop in this paper is taken as 50,18 The speed loop bandwidth is taken as 2503.1. The speed loop is designed to design the speed loop into a high gain path. The dynamic structure of the speed loop is not changed after the original correction. The 3 speed input signal includes not only the original speed error, but also the integral of the speed error. The closed loop transmission coefficient of the speed loop can be seen. Out, the calibration plant's speed loop bends to the type system effect open loop transfer function, 8 can be written, then the corresponding frequency characteristics of the ç¥8 are in the inner, the bandwidth of the road design, in order to make the system obtain greater damping Ratio and smaller equivalent noise bandwidth. In general, 21 707, = 177, they are achieved by adjusting 1. and to achieve 1.
And the speed loops corrected for 3625 and 125 respectively, for the stepped disturbance signal. The steady-state speed output of the motor is 0. When 1. is the speed disturbance, the motor steady-state output is violated. Due to the gain in the speed loop, 1 is very large, so it has high interference suppression capability. 3.2 Position loop design Because the bandwidth of the speed loop is wide, the speed loop can be used in the reciprocal of its feedback link within the bandwidth of the position loop. Instead, it is approximated as a proportional coefficient, so the position loop can be approximated as a type system. Since the frequency characteristics of the type system and the negative reversal characteristics of the gap link are not verified, it is tried to offset it, and the final accumulated deviation is not allowed to be installed. The adjustment is made to ensure that the long distance still reaches the non-accumulation deviation. The red light-emitting diode and the photocell are composed of the reader. The interval between them is 5+, which is a natural number and is considered to be 2, so every other one is placed with a light-emitting diode and The tube assumes that the reader is moving to the left. The photocell; 1 is aligned with the aperture 3.
At this time, 1 produces a photo 0, and when the reader shifts 1 to the left, 02 is aligned with the hole 5. 02 generates a photoelectric signal, whereby when a reader consisting of only a photocell slides on the light ruler, each moving photocell will generate a photoelectric signal, and the request for each pulse of the test is issued. This kind of sensor does not reduce the number of light apertures and reduces the machining requirements. The frequency of the signal transmitted by the 4-wire is reduced, which is applied to the extension puller. It is necessary to improve the running speed between the test cars, and it is also necessary to improve the number of photoelectric tubes in the reader and increase the spacing between the optical holes to meet the requirements of different occasions. Principle, the light hole uses a blank short-line pole tube on the light ruler. The principle of 4.
The method of positioning the light ruler 4 has a great meaning for the long-distance positioning occasions requiring low cost, and the second page is born. The dynamic structure of the stability problem position loop is solved small, and the position loop can be adjusted by adjusting. Bandwidth, 4 experimental results To verify the effectiveness of the method, it will be applied to the ten-one ultra-viscous machine tool servo system, the machine version detection resolution 5 cabinet 6 for joining, 1 controller and dual loop controller system The zero-input response curve can be used. The proportional+integration method does not consider the effect of the gap, and the self-sustained oscillation is generated in the system. The dual-loop clamping method can eliminate the self-sustained oscillation and raise the steady-state performance of the system. Due to the untrained dynamic characteristics neglected in the system, the maximum steady-state error of the two-way time proportional+integral control method in the system positioning process does not exceed the soil. 5 Conclusion To solve the problem of the ultra-precision machine tool servo system The system is unstable due to the intersection of the ring frequency characteristic and the negative reversal curve of the gap link. This paper proposes a two-loop control method that can prevent self-sustained oscillation in the system. When the bandwidth of the mouth speed loop and the position loop are appropriate, the two loops are designed separately.
The position loop can prevent self-sustained oscillations; the high-gain speed loop can effectively suppress the interference. Finally, the experiment verifies its effectiveness. 2 Wang Guangxiong. Control system design. Aerospace Publishing House, 1992.
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