Closed-loop Linear Motion Module

Closed-loop Linear Motion Module is a high-precision linear drive system that integrates position feedback devices, representing the highest standard in the field of precision motion control. Unlike traditional open-loop systems, it forms a complete control loop through real-time monitoring, comparison, and correction, ensuring unparalleled positioning accuracy, repeatability, and reliability under any working condition. Closed-loop Linear Motion Module is the ultimate solution to meet the demanding requirements of high-end manufacturing.

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Closed-loop Linear Motion Module usually use motors as power sources, commonly including stepper motors and servo motors. The operation of the motor generates rotational motion, which is converted into linear motion through transmission mechanisms such as screws and synchronous belts, driving the slider on the module to make linear displacement along the guide rail. Unlike open-loop systems, closed-loop linear motion modules are equipped with position sensors such as grating rulers, encoders, etc. The sensor monitors the actual position of the slider in real time and feeds back the position information to the controller. The controller compares the target position with the actual position. If there is a deviation, Closed-loop Linear Motion Module will adjust the input signal of the motor to correct the movement of the slider and ensure its accurate positioning.

On the basis of traditional linear modules (including motors, screws/belts, rails, etc.), Closed-loop Linear Motion Module has added a real-time feedback system at its core, usually consisting of a high-resolution encoder (grating ruler or rotary encoder) and corresponding motion controller. The workflow forms a closed loop: the controller sends instructions to drive the motor → the module starts moving → the encoder reads the actual position signal in real time and feeds it back to the controller → the controller compares the actual position with the target position → calculates the error and immediately issues a correction instruction → drives the motor to eliminate the error. This cycle of "perception decision execution re perception" continues continuously, thus automatically compensating for any deviation caused by factors such as thermal elongation, backlash, load changes, vibration, etc.

Basic Specification of closed-loop linear motion module:

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Closed-loop Linear Motion Module is a device that can achieve high-precision linear motion control and is widely used in many fields such as industrial automation, scientific research, and medical care. Its core technology lies in a closed-loop control system that can accurately achieve the expected motion goals. The closed-loop linear motion module is an inevitable choice for pursuing ultimate precision, reliability, and intelligence. It has been widely used in semiconductor lithography machines, precision measuring equipment, cell injection robots, high-precision CNC machine tools, and any cutting-edge manufacturing and research fields that do not allow errors. Closed-loop Linear Motion Module is a key landmark component for modern industry to move from "automation" to "intelligence" and "precision".

Semiconductor manufacturing: used for equipment such as lithography machines and etching machines to achieve high-precision alignment and positioning of wafers, as well as precision machining and testing in the chip manufacturing process. ​

Biomedical: In equipment such as microscopes, cell manipulators, and gene sequencers, precise control of sample or instrument component positions is used for cell observation, manipulation, and gene analysis. ​

Aerospace: In satellite component testing, space simulation experiments, etc., precise control of the position and attitude of experimental equipment, simulating the motion state in the space environment.

As we all know, the traditional linear motion is mostly converted into linear motion through a certain transmission conversion mechanism, and various transmission links are passed in the middle. Therefore, the positioning accuracy of the system must consider the accuracy of the rotation motion, the accuracy of the transmission mechanism, and the installation error. , System wear and other factors that affect system accuracy. At present, the high-end domestic and international solutions use direct-drive linear motors, and the middle and low-end ones use grinding-grade precision screw rods, low elastic deformation belts, high-precision racks, etc. to minimize the accuracy brought by the system transmission links. loss.

High-end direct drive linear motors have high speed, high acceleration, high positioning accuracy, no backlash and other traditional transmission type linear motion can not achieve high performance, but because the core technology of the linear motor system is basically mastered and controlled by foreign developed countries. Although several domestic companies have also started to make linear motors, most of them only make motor bodies, and displacement sensors and servo controllers still need to rely on imports. Therefore, the overall price of the linear motor system is still high, making it truly a high-end product that dare to ask but dare not use it. Coupled with the current national rare earth strategic control, the linear motor body has gradually lost its price advantage. The price of the entire system is gradually rising. It is precisely because of the high price that many core components need to be imported, so that the consumption of the entire market has a considerable gap with traditional servo products, and the overall situation is weak.

In order to fundamentally solve the problem of large-scale promotion of linear motor systems, we must start from three aspects: one is to design linear motors that save rare earth materials, which requires linear motor manufacturers to have advanced design tools and innovative design ideas, blindly The copying and copying of foreign companies can only make a difference in labor cost at most; the second is the localization of high-performance displacement sensors. Only by mastering the core technology can we break the monopoly of international manufacturers and design cost-effective products that meet my country's national conditions; The third is the localization of the servo controller. In fact, there are many inverter manufacturers in China. It is relatively easy to switch from frequency conversion to servo. It is just that the software algorithm is the key to measuring the performance of the entire servo controller. In terms of hardware, everyone is basically It's almost the same. Therefore, the basic research and in-depth absorption of the algorithm is the first problem to be solved for the domestic servo controller.

Most of the mid-end and low-end use transmission methods to realize the conversion of rotation to the current movement. The traditional way of thinking is to add an encoder to the back end of the rotating servo motor, and then use various methods to minimize the loss of precision in the transmission link. Therefore, various precision screws, precision belts, precision racks and other high-precision transmission mechanisms have been introduced to meet the needs of the equipment. The purpose is to allow the entire system to achieve predictable system accuracy. However, in fact, this semi-closed-loop transmission system is constantly increasing due to the wear of the contact transmission during use, the loosening of system assembly, stress and deformation and other error sources, the declared accuracy of the system cannot meet the expected requirements at all. Downgrade use. The reason is that the system is only a semi-closed loop, and the actual situation of the final load movement can only be approximated by the accuracy of the transmission mechanism. In addition, high-precision screw rods, racks, belts, etc., are difficult to process and expensive. For example, the micron-level screws of THK and IKO have thousands of moves, and strategic control is required. To completely get rid of this dilemma, the only way to comprehensively consider the system from a new perspective, such as how to achieve a full closed loop of the system, so that the error level of the system can not only be predicted, but can be accurately measured. The other is how to upgrade the traditional system with a lower cost, without making major changes to the original system, and by adding limited components to achieve the high precision of the traditional transmission system.

We all know that the digital display transformation of the machine tool is to realize the closed-loop display of displacement only by adding the grating digital display, which greatly improves the performance of the traditional manual machine tool. The machining accuracy is no longer just prediction, but also accurate measurement. The company's linear drive full closed loop solution is similar to this, there are low-end full closed loop digital display solutions, and mid-to-high end full closed loop numerical control solutions. This benefits from our mastery of the core technology of linear coding and in-depth research on system compensation control algorithms.

This fully closed-loop high-precision solution is not only suitable for performance upgrades of traditional servo systems, but also suitable for performance upgrades of traditional open-loop stepper slide systems. It fills the middle ground between the traditional servo motor system and the open-loop stepper motor system. It is a low-cost, cost-effective and unique servo control solution. The stepping system of this solution inherits all the advantages of the traditional stepping system (for example: static locking force, good low-speed performance, high torque (relative to the servo motor of the same base model), and no delay in response to the position loop Time, cheap, maintenance-free), and has some advantages of the servo system (for example: good safety, no loss of step and overshoot, communication with the host computer, faster acceleration or deceleration, and high positioning accuracy). In addition to high-speed performance and overload performance, the stepper motor of this solution is not comparable to the traditional servo motor, and its performance in other aspects is completely comparable to the servo motor, and even some performance is better than the servo motor (for example: static locking force, with ordinary grating ruler It can get higher and more reliable positioning accuracy, low-speed stability and low-speed high torque without the need of a gear reducer...). Because this solution is very cost-effective, it will provide industrial automation design and users with a more choice, especially the economical CNC machine tool industry.

This solution is simple in principle and easy to debug. Anyone can set it up well through the manual. It does not require professional debugging technology. The control and use are no different from the traditional open-loop stepper motor system. The existing Any stepper motor system can be upgraded in accordance with this solution. After being widely used by customers, it can fully adapt to three-axis or multi-axis CNC machine tools.

This solution can work with gratings with a resolution of up to 0.001mm. It is completely designed for multi-axis linkage, the response to position error is microsecond, the static accuracy is plus or minus one pulse of the grating, and the dynamic accuracy is 2-3 pulses plus or minus of the grating. In the actual test on the wire cutting machine with middle wire, the square can reach the precision of 0.003mm, and the circle can reach the precision of 0.005mm. For the machine using this solution, whether it is using a C7 grade screw or a C3 grade screw, the final machining accuracy is not much different, but the price difference between the C7 and C3 grade screw is huge , Which is very economical.