---
title: "Design of a machine tool control system for function reconfiguration and reuse in network environmen"
url: "https://maker.wiznet.io/emimamanna/projects/design-of-a-machine-tool-control-system-for-function-reconfiguration-and-reuse-in-network-environmen/"
markdown_url: "https://maker.wiznet.io/emimamanna/projects/design-of-a-machine-tool-control-system-for-function-reconfiguration-and-reuse-in-network-environmen/md"
type: "UCC: User Created Content"
author: "emimamanna"
author_url: "https://maker.wiznet.io/emimamanna/"
original_author: "Yingxue Yao"
original_url: "https://www.sciencedirect.com/science/article/abs/pii/S0736584518302047"
published: "2022-10-14"
language: "en"
hardware: ["WIZnet W5300"]
likes: 6
views: 1175
comments: 1
source: "WIZnet Makers (https://maker.wiznet.io/)"
---

# Design of a machine tool control system for function reconfiguration and reuse in network environmen

> Design of a machine tool control system for function reconfiguration and reuse in network environment

Original author: Yingxue Yao (source: https://www.sciencedirect.com/science/article/abs/pii/S0736584518302047)

## Components

- **WIZnet W5300** x 1 ([docs](https://docs.wiznet.io/Product/Chip/Ethernet/W5300))

## Article

**Introduction**

CNC system lies at the bottom layer of manufacturing system. As computer/information technologies are developing rapidly, it is important to optimize the architecture and operation mechanism of CNC to achieve higher machining quality and efficiency and lower machining costs.

The development of CNC is closely related to the development of computer/information technologies and software development technology. Similar with the development of computers, early numerical controllers went through stages of electron tubes, transistors and small scale integrated circuits. These numerical controllers are named hardwired numerical controllers (HNC). Numerical control systems significantly improved the manufacturing quality and efficiency, however, the architecture was complex and the functionality was simple. It was difficult to program for the numerical controllers. Since large scale integrated circuits were invented in 1970s, numerical controllers became computerized [1]. Computerized numerical controllers are more programmable and flexible, which made flexible manufacturing systems (FMS) practical. The computers and peripherals of CNC at early stage are dedicatedly designed. It is difficult to reconfigure the controllers to meet specific requirements. Since 1990s, personal computers (PC) were adopted as the platform of CNC systems. Different from former CNC system platforms, PCs have standard hardware architecture, communication interfaces and uniform operating systems. Open architecture controllers (OPC) are organized in modular manner so that functions are interchangeable. By using open interfaces, users can integrate user-specific applications into the system [2]. With OPC as key enabling technology, manufacturing systems become reconfigurable [3]. Functions are configured only when needed. Therefore, manufacturing costs and system ramp-up time are reduced.

Currently there are mainly three kinds of OAC architectures, namely PC embedded in NC, PC plus motion control card and PC with real-time operating systems (RTOS) [4]. In “PC embedded in NC” architecture, PC serves as human-machine interface (HMI), while real-time interpolation and motion control functions are undertaken by stand-alone NC kernel. In “PC plus motion control card” architecture, NC functions are still undertaken by NC kernel which is plugged in PC through standard interface such as PCI. In the above two kinds of CNC architectures, openness is limited since NC kernel is vendor specific. In “PC with RTOS” architecture, all the control functions are executed by PC and no other numerical control platforms are needed. PC communicates with servo drives through field-bus or Industrial Ethernet [5–7]. Because PC is responsible for real-time interpolation and position control algorithms, a real-time operating system is needed to guarantee exact timing for real-time tasks. Since CNC functions are executed by PC software, this type of controller is called “soft-CNC”. Though soft-CNC has enough openness theoretically, it is still difficult to reconfigure CNC controllers and reuse the function modules. Core functions are based on the application program interfaces (API) of real-time operating systems. These functions must be carefully designed in order to not deteriorate real-time performance of the controller [8].

With more hardware/software resources as enabler, more functions are integrated in CNC controllers. Traditionally CNC controllers read Gcode as input. G-code mainly contains information of tool path trajectory, feed command and input/output (IO) functions, which are not sufficient for multiple functions and cannot serve as bi-directional information flow between CNC controllers and high-level systems such as CAD/CAM [9]. Therefore, STEP-NC has been proposed as object-oriented machining task description program [10,11]. Using object-oriented approach, STEP-NC programs contain information of machining features, machine tools, machining strategy, tool paths, etc. [12]. With the above high level information, CNC controllers have more decision making ability and intelligence, such as modifying machining strategy or machining tool paths. Meanwhile, modifications can be fed back to CAD/CAM systems [13]. STEP-NC increases the interoperability of CNC controllers and fills the gap between CNC and CAD/CAM. Functions originally belong to CAD/CAM systems are integrated in CNC systems, such as manufacturing feature recognition and tool path generation. STEP-compliant CNC system is more than just a machine tool controller, but rather an integrated manufacturing data processing platform.

With the development of information and communication technologies, manufacturing systems are stepping into a new stage which is widely known as Industry 4.0. Initiated by Germany, Industry 4.0 describes the fourth industrial revolution enabled by cyber-physical systems (CPS), internet of things (IOT) and services [14]. In the realm of Industry 4.0, resources involved in value-adding process such as humans, objects and systems are networked to create smart factories [15,16]. In smart factories, manufacturing systems can communicate with each other and response rapidly to different requirements. By using CPS and IOT technologies, manufacturing systems achieve intelligence such as self-awareness, self-prediction and self-reconfiguration [17].

As the key element of manufacturing systems, machine tools also need to make changes to keep pace with upcoming Industry 4.0. Xu [18] named machine tools in context of Industry 4.0 Machine Tool 4.0. By connecting machine tools into manufacturing networks as a cyberphysical production system, machine tools can be smarter, more adaptive and more autonomous. With smart machine tools such as Machine Tool 4.0, smart factories become distributed and collaborative. The business logic of machine tools can be moved into cloud-based applications and provide smart products and services [19].

In order to achieve smart machine tools, the controllers of machine tools should be well-connected and interoperable with the aid of network-based or cloud-based system [20–22]. In network-based or cloudbased paradigms, CNC controllers are not merely stand-alone assembly of hardware and software. The reconfigurability and scalability of CNC should be considered in a distributed environment instead of local shop floor. Functions of CNC systems should be available to multiple machine tools in plug-and-play manner. It is worth mentioning that research on remote operation and monitoring of machine tools arose earlier than the research on Industry 4.0. Ong et al. [23] and Hanwu and Yueming [24] developed network-based virtual CNC systems respectively. Users can virtually operate machine tools via web browser. Wang et al. [25], Torrisi and Oliveira [26] and Adamson et al. [27] developed remote CNC machine tool control platforms. Meanwhile, real-time monitoring of machining is realized. Liu et al. [28] designed a cyber-physical manufacturing cloud architecture. Local machines receive machine operation requests from the cloud and feedback status information. In the above researches, a local CNC controller is still needed to parse machining programs and generate motion instructions for servo drives. Verl et al. [29] proposed a framework of cloud-based machine control methodology. The control functions are moved up to the cloud, while the framework needs a cloud-based real-time operating system to handle real-time tasks. Schlechtendahl et al. [30] evaluated TCP/IP and UDP protocols performance in the framework that control functions are moved up to the cloud without local CNC systems. The results showed that current TCP/IP and UDP protocols cannot meet real-time performance and quality of service that real-time cloud-based CNC system execution required.

Current manufacturing paradigms such as Industry 4.0 are aiming at more reconfigurability, scalability and function reusability via network environment to shorten manufacturing time, reduce costs and increase system adaptability. However, while the upper layers of manufacturing system are becoming cloud-based and service-oriented, CNC systems are still bound to local machines. The main reason why current CNC systems cannot operate in remote platforms is the closely-coupled architecture of CNC systems. Key functions such as machining program parsing and tool path interpolation are executed in compact real-time platforms. In such platforms CNC function algorithms have to be carefully designed to meet real-time requirement. These functions can only serve corresponding local machine. While more functions are integrated in current CNC architecture, function reusability becomes low.

The object of this pater is to present a new CNC architecture that fits current network operation environment. The authors name the proposed architecture invisible numerical control (INC). With fundamental technologies advancements such as rapidly increasing Ethernet throughput and mass storage capacity, INC system is organized in loosely coupled manner by using object-oriented programming (OOP) and service-oriented architecture (SOA) technique. In INC architecture, machine control instructions are generated in non-real-time environment. Therefore, INC can operate remotely rather than configuring CNC system locally. This feature is very important to achieve high reconfigurability, scalability and function reusability.

The rest of this paper is organized as follows: Section 2 describes the concept of INC. Section 3 designs INC system architecture. In Section 4 a prototype system is built and in Section 5 experiments illustrates the property of INC. The authors’ conclusions are stated in Section 6.

**Concept of INC**

Invisible numerical control (INC) is a network-based and distributed machine tool numerically control paradigm. By adopting loosely-coupled architectures and defining communication interface among function modules, INC achieves high degree of reconfigurability, scalability and function reusability. INC system interacts with machine tools in plug-and-play manner. The term “invisible” implies that machine tool motion command generation related functions are all implemented in network environment and are invisible to local users.

| ![](https://maker.wiznet.io/upload/ckeditor5/58106168%5F1665773011%2Epng) Fig. 1. INC architecture. |
| --- |

The overall architecture of INC is shown in Fig. 1. It has three subsystems, namely project center, motor controller and mobile terminal. Project center is a remote manufacturing management and machining instruction generation unit. It is the aggregation of CNC related function modules. These function modules are loosely coupled and communicate with each other through standardized communication protocols. The reconfigurability and scalability of INC are achieved by applying different function modules. Project center communicate with motor controller through Ethernet. The message sent to motor controller mainly contains motion instructions of machine tool motors for each sampling period and switch on/off commands of machine tools. This paper names the message sent to motor controller machine control instructions (MCI). By taking MCI files as standard communication protocol, project center can generate command for machine tools as a service in plug-and-play manner.

Motor controller controls the motion and synchronization of the motors of machine tool. In order to avoid real-time communication between project center and motor controller, motor controller contains mass storage to save MCI received from project center. Besides motor control functions, motor controller also undertakes some machine level functions such as machine tool parameter management, machining monitoring and communication with project center and mobile terminal.

Mobile terminal serves as the local HMI of INC system. It can be smartphone, laptop or PC. It communicates with project center and motor controller via wireless networks. When communicating with project center, mobile terminal receives manufacturing tasks description (in the formats of G-code, STEP-NC program or CAD file) and send machining option requirements such as MCI transmission or machining/machine tool parameters modification. When communicating with motor controllers, mobile terminal acts as operation panel of CNC machine tools.

**Operation mechanism of INC**

The operation mechanism of current CNC systems is shown in Fig. 2 [31]. After fed into CNC system, NC program is processed by interpreter. In real-time domain, feedrate profiles are generated for the tool paths, then interpolator generates motion commands for each axis. In order to avoid dataflow jam or stop, buffers are applied in each function modules. The depth of the buffer represents the “look-ahead” ability of the system [32]. By processing NC program in real-time domain, function modules are closely-coupled. Theoretically, only motor movement control has to be real-time. However, motor controller reads reference command in each servo sampling interval (less than a few milliseconds). If not generated in real time, reference commands have to be generated and saved in advance to meet the tight timing requirement. During the development of computers, in quite a long period memory devices are expensive and small in capacity. Therefore, closely-coupled operation mechanism is optimal when computer resources are limited. As a consequence, real-time property is important for function modules such as interpolator and feedrate planning algorithms.

The operation mechanism of INC is illustrated in Fig. 3. In order to minimize the constraint of real-time requirement, machine control instructions are generated in off-line manner. This method is similar to the compiled operation of computer programs [4]. Compiler is the key function module in project center. It contains a series of sub modules which correspond to each step of machine control instruction generation. Compiler takes NC program such as G-code or STEP-NC files as source code files. Machine tool parameters are referenced to generate object files. The object files sent to motor controllers and saved in mass storage. Therefore, motor controller can read machine control instructions and execute directly without traditional real-time tool path interpolation.

The merits of INC system are multifold. Firstly, the architecture of CNC machine tools is simplified. In the shop floor only motor controllers are configured, while PC and conventional CNC software are removed. Secondly, since INC architecture is loosely coupled and CNC program compiling process is not constrained in compact real-time kernel, it is easier to add or replace function modules such as different kinds of feedrate planning methods [33,34] and interpolators [27,35]. Thirdly, machining process data, such as CAD/CAM models, machine tool configurations, machining parameters, machine tool motor feed commands and monitoring information, are all integrated in project center. With this information, especially detailed machine tool movement information, it is more efficient and accurate to evaluate machining cycle time and accuracy [36].

| ![](https://maker.wiznet.io/upload/ckeditor5/58106168%5F1665773000%2Epng) Fig. 2. Operation mechanism of current CNC systems. |
| --- |

Applying INC technology will change the operation paradigm of manufacturing systems. Currently functions of CNC are encapsulated by CNC vendors and machine tool manufacturers. When CNC functional requirements change, the whole CNC system has to be changed or updated. INC project center provides a platform on which distributed function modules are integrated. Users can choose function modules from a shared pool of resources [37] according to constraints such as machining precision/efficiency, material property of products, kinematics/dynamics/error models of machine tool, etc. Manufacturing systems are becoming distributed and collaborative [3,16]. Since there are abundant researches available in literature and industry covering different area of CNC functions, the authors believe that INC architecture is a potential methodology to make full use of resources.

**Architecture design of INC system**

Project center is the MCI generation unit of INC system. The core functions of project center are shown in Fig. 4. In order to generate MCI for specific machine tool, Configurations of the machine tool should be referenced by every procedure during the generation of MCI. The core functions of project center are to transmit MCI to motor controllers and receive machining monitoring feedback. During machining, users can send instant commands such as start/stop to control machining process. Typically, MCI files are generated by compiling NC programs. NC program compiler first parses the program and extracts tool path information. Then compiler generates feedrate profiles based on tool paths. Feedrate profiles are interpolated to generate MCI files. Based on the above basic function modules, project center can integrate highlevel functions. For instance, When CAM functions are required, tool paths are generated based on manufacturing features. Then tool paths can be translated to standard NC program files.

The reconfigurability, scalability and function reusability of INC are enabled by the service-oriented architecture (SOA) of project center software [38]. It indicates that function modules of project center operate autonomously and interoperate through well-defined interfaces. These interfaces are mainly different files that are involved during manufacturing process. For CAD/CAM functions, vendor-specific CAD/ CAM files still can be used. In CNC level, G-code and STEP-NC files can be used to describe specific machining tasks. Since a compiler is implemented in project center, the key intermediate file of compiler is tool path file and the outcome is MCI files. Therefore, the format of these files needs to be defined.

Although G-code and STEP-NC files contain tool path information, the feedrate profiles of the tool paths are generated dynamically by CNC controllers in current machining process. After feedrate profiles are interpolated, these profiles are deleted. In INC architecture, feedrate profile generation is a function module that can be used as a service. It generates tool path file that contains feedrate profile information. As shown in Fig. 5, the data structure of tool path is a list consisting tool path elements. Tool path element contains two aspects of information – geometry and feedrate. By using object-oriented programming technology, different kinds of curves can be derived from base class “Curve”. Meanwhile, feedrate profile can be generated by different methods such as trapezoidal method (acceleration limited) and Sshaped method (jerk limited).

MCI files contain periodic position commands of machine tool axis and switch commands of machine tool I/O. Formats of position command and switch command are shown in Fig. 6. In position command, spindle command may be the desired output of variable-frequency drive while feed axes commands are desired feed command discretized by the basic length unit (BLU) of axes. Compared with position command, the amount of switch command is negligible. Therefore, the size of MCI files is determined by the amount of position commands. When machining, the MCI reading speed of motor controller is

1000(4*n*+ 2)*R*= *T *

* *(1) where R (byte/s) is the MCI reading speed. n is the axes number of the machine tool and T (ms) is the sampling period of position control loop. For a five-axis machine tool, when the sampling period of position

![](https://maker.wiznet.io/upload/ckeditor5/58106168%5F1665773006%2Epng)

Fig. 3. Operation mechanism of INC.

![](https://maker.wiznet.io/upload/ckeditor5/58106168%5F1665773011%5F1%2Epng)

Fig. 4. Functions of project center.

control loop is 0.5 ms, the MCI reading speed of motor controller equals 52 Kbyte/s. The throughput of current Ethernet and memory devices can satisfy the requirement for reading MCI files. Besides, quality of service (QoS) mechanism integrated in TCP can guarantee that no telegram losses occur during MCI transmission [24].

Project center should be reconfigurable and scalable to meet various requirements. Its user interface (UI), core functions and involved data can be changed according to the tasks. Therefore, the widely-used three-tier architecture [39] can be used to organize the software of project center. As shown in Fig. 7, project center software is divided into three layers: presentation layer (UIs), business logic layer (service provided) and data access layer (data operation interface). A group of standardized application programming interfaces (API) can be defined to connect the layers of project center software. Users and developers can access or implement functions through these APIs.

**Architecture of motor controller**

Motor controller receives instructions from project center and mobile terminal. Compared with current CNC controllers, motor controller does not include NC program processing and feedrate interpolation functions, but executes MCI directly. Therefore, real-time tasks are simplified in INC system. ARM and FPGA which are generally used in embedded CNC kernels [40] can be used to implement motor controller. The architecture of motor controller is shown in Fig. 8. Motor controller contains large scale memory device which acts as buffer to store MCI files. Therefore, there is no need to receive MCI in real-time from project center. Through IO control interface and motor control interface, motor controller sends IO command to PLC and position command to motors respectively and gathers their status information.

When needed, motor controller feedbacks these information to project center or mobile terminal.

In order to control machining contour, motor controller needs to synchronize the motion of each axis of the machine tool. There are two kinds of machine tool feed drives topology: centralized and fieldbusbased. Motor controller can be used in both topologies. In centralized topology, all the motors are controlled and synchronized by single motor controller. While in fieldbus-based topology, multiple motor controllers are used and they are connected by fieldbuses such as EtherCAT or SERCOS using vendor-specific ASICs. Among these motor controllers, the master interacts with project center/mobile terminal and synchronizes the slaves, while the slaves only control the corresponding motors by receiving commands from the master.

Motor controller can be developed using currently widely used embedded devices such as ARM and FPGA. As for MCI storage, SDRAM or DDR can be used. The capacity requirement of MCI storage can be calculated according to Eq. (1). For a five-axis machine tool, when the sampling period of position control loop is 0.5 ms, motor controller needs 183 Mbyte of MCI for machining autonomously for an hour. Commonly the capacity of SDRAM ranges from 32 Mbyte up to 1 Gbyte, which can support motor controller to operate independently for 10 min to 5 h.

1. Mobile terminal architecture

| ![](https://maker.wiznet.io/upload/ckeditor5/58106168%5F1665773011%5F0%2Epng) Fig. 5. Tool path data structure. |
| --- |

Mobile terminal acts as portable user interface and operation panel of INC machine tools. It interacts with project center and motor controller via wireless network. When communicating with motor controller, mobile terminal configures the parameters of motor controller at ramp-up stage, sets operation modes and monitors the state of machining. When interacts with project center, mobile terminal sends the parameters of machine tools to project center and sets up machining parameters. Meanwhile, project center feeds back NC programs and MCI transmission status. Since current portable devices also have considerable resources, mobile terminal can act as a simplified project center. On mobile terminal, users can edit and compile NC programs and transmit MCIs to motor controller. The layered architecture in Fig. 7 can also be referenced to implement mobile terminal software. Based on the resources of platforms and requirements, the functions of mobile terminal can be scalable from elementary display of machining status to a full-featured portable project center.

**Prototype development**

In order to investigate the reconfiguration process of INC and testify the usability of current hardware and software for INC architecture, we developed an INC system prototype. The framework of the prototype is shown in Fig. 9.

Project center need to provide a platform to plug in different function modules. Instead of developing stand-alone software, we choose Solidworks as the project center platform. By this means it is easier to acquire user interface with multiple functions. Solidworks provides APIs based on component object model (COM) technology. To use the API of Solidworks, function modules are encapsulated as dynamic link libraries (DLL) and registered in Solidworks. A series of core functions of project center are developed. At last, MCI files are generated. The UI of project center is shown in Fig. 10.

The prototype of motor controller is developed using FPGA. It is a centralized dual-axis controller. For each servo motor, position/velocity/current control loops are integrated in FPGA. The network interface of motor controller is W5300 from Wiznet™. It integrates 10/100M Ethernet controller, media access control (MAC), physical layer (PHY) and TCP/IP stack. The maximum throughput of W5300 can reach 80 Mbps. After MCI is received, a function module named network controller decides whether to save the MCI in the memory or to send it to main control module and execute instantly. It depends on the ID.

![](https://maker.wiznet.io/upload/ckeditor5/58106168%5F1665773009%5F0%2Ejpeg)

Fig. 7. 3-tier architecture of project center software.

the MCI. The MCI storage is composed by two pieces of 256 Mbit SDRAM. Each SDRAM has independent address/data/control bus so that MCIs can be read and written in the same time. Therefore, it is possible for motor controller to read MCIs from memory and to download MCIs from project center simultaneously. By this means, motor controller does not have to wait until all MCI file are downloaded. After the size of MCI in the storage reaches a certain threshold value, motor controller can start machining, which can shorten the lead time.

The mobile terminal of the prototype is a simplified Graphical user interface (GUI) developed using Qt framework, as shown in Fig. 11. To simplify development procedure, mobile terminal and project center run in the same PC. Mobile terminal connects with motor controller through TCP by setting the IP address and port number of target motor controller. Besides sending MCI files to motor controller, mobile terminal also receives and saves feedback from motor controller. The feedback is mainly periodical position information of machine tool axes. Mobile terminal can also send instant command to control the operation of motor controller.

Experimental study

To validate the reconfigurability, scalability and function reusabilityof proposed INC system, we conducted different experiments using developed prototype. The experiment platform is shown in Fig. 12. The developed INC prototype is configured with a lathe. Besides turning, virtual milling and spline curve machining are carried out using the feed drives of the lathe. A laser tracker is used to observe the tool paths of virtual milling. The result of experiments is shown in Fig. 13.

First, turning experiment is carried out. The turning part model and result is shown in Fig. 13(a). The NC program of the part is written manually in G-code. Therefore, a G-code parser module is loaded in Solidworks platform together with feedrate planning module and interpolation module. The interpolation period, as same as position control loop period, is set as 1 ms, while the feedrate is set as 60 mm/ min. The G-code program is compiled and the size of MCI file generated is 76.5 Mbyte. Because the capacity of MCI storage is 64 Mbyte, MCI file need to be transmitted in batches. When motor controller reads MCI from one SDRAM, MCI file is saved in the other one. During the experiment, the through put of W5300 reached up to 50 Mbps. It took 35 minutes to read all MCIs in a SDRAM, while it took about 10 s to refill it. Therefore, MCIs are executed without halt.

Using the same platform, we carried out virtual milling of 2D pocket experiment. As shown in Fig. 13(b), the experiment uses a 2D pocket with two islands. In order to generate MCI files of pocket milling, project center is reconfigured. After modelling in Solidworks, a feature

![](https://maker.wiznet.io/upload/ckeditor5/58106168%5F1665773007%2Epng)

Fig. 8. Architecture of motor controller.

![](https://maker.wiznet.io/upload/ckeditor5/58106168%5F1665773011%2Ejpeg)

Fig. 9. Framework of INC system prototype.

![](https://maker.wiznet.io/upload/ckeditor5/58106168%5F1665773008%2Ejpeg)

Fig. 10. UI of project center based on Solidworks.

recognition module extracts the boundaries of the pocket and the islands. Then a 2D pocket tool path generation module generates the tool paths. The feedrate planning module and interpolation module are reused. The desired feedrate is 1.5 m/min, while the interpolation period is 1 ms. The size of generated MCI file is 3.08MB, therefore the MCI file can be transmitted once. The machining trajectory is tracked by the laser tracker.

The third experiment is to enable spline curve machining function. To achieve this, original feedrate planning modules and linear/circular interpolation module are replaced by a new jerk-limited feedrate planning module and spline interpolation module. The test curve, as shown in Fig. 13(c) is a simple three order B-spline curve. Project center reads the control points and knot vector, then generates uniform MCI files. The motion of tool is also tracked by the laser tracker.

During these experiments, the configurations of motor controller and machine tool remain the same. The loosely coupled architecture of project center makes it easy to replace or add function modules. Therefore, the INC system has high reconfigurability and scalability. Moreover, motor controller reads MCI in every position control cycle, which usually lies between 0.1 and 2 ms. The transmission rate of MCI can reach up to 50 Mbps, which is much faster than MCI reading speed. Therefore, project center can send MCIs to multiple motor controllers in time-sharing manner. These machine tools can reuse the functions or service of project center.

**Conclusions**

As manufacturing industry is becoming distributed and

![](https://maker.wiznet.io/upload/ckeditor5/58106168%5F1665773006%2Ejpeg)

Fig. 11. User interface of mobile terminal.

Fig. 12. Platform of experimental study.

collaborative, CNC systems are integrated and isolated. To meet different requirements, more and more functions are integrated in CNC systems, which makes CNC architecture more complex while the function reusability is lower. The reason why current CNC systems cannot fully benefit from the reconfigurable and scalable nature of network environment is that the functions of current CNC are closelycoupled in real-time environment.

This paper defines the concept of a new kind of machine tool control technology named invisible numerical control (INC). The main difference between INC and current CNC is that the architecture of INC system is loosely coupled and motion command generation related functions are configured in project center in network environment, leaving only motion control related functions in the shop floor encapsulated as motor controller. This is enabled by the development of supporting infrastructure such as Ethernet and memory devices and compiled execution of NC programs. By applying INC architectures, not only local control system architecture is simplified, machine tool control system also achieves high degree of reconfigurability, scalability and function reusability.

An INC system prototype has been built using Solidworks platform and off-the-shelf hardware. In the architecture of this prototype, function modules are encapsulated as COM add-ins and registered to Solidworks when needed. Experiments illustrate that by reconfiguring function modules in project center, local machine tools can acquire new machining ability without changing local device architectures. By saving MCI files in motor controller, local machine tools can operate independently for a considerable long time (10 min to 5 h). Therefore,

![](https://maker.wiznet.io/upload/ckeditor5/58106168%5F1665773009%2Ejpeg)

Fig. 13. Results of machining experiments. (a) Turning; (b) virtual machining; (c) virtual spline machining.

multiple machine tools can reuse the functions of project center by time sharing method.

In order to make full use of the abundant knowledge on manufacturing technology and connect INC system with manufacturing system, a uniform project center platform need to be designed. Standardized interfaces of function modules and resource description methods are vital to implement INC systems. Moreover, researches on the security and quality of service of MCI transmission are needed. These aspects are the further research directions of INC technology.

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Source: https://maker.wiznet.io/emimamanna/projects/design-of-a-machine-tool-control-system-for-function-reconfiguration-and-reuse-in-network-environmen/