# Remote Servo Tuning System for Multi-Axis CNC Machine Tools Using a Virtual Machine Tool Approach
## 4 Intelligent Servo Tuning Cloud System: Machine Dr.
### Machine Dr. System Development  
We developed a platform to implement remote connection with machine tools, where the user could connect the machine tools and obtain the status of machines via the internet, called Machine Dr.; the functions illustration is shown in Figure 10. It is based on system identification, intelligent tuning servo systems, database processing, and cloud computing. Figure 10 illustrates the communication between machine tools and users. After receiving system identification data, Machine Dr. calculates the associated information of the machine and establishes corresponding data in the cloud, and then Machine Dr. also provides identification results and suggested P-PI controller parameters with the corresponding bandwidth. The Vendor can also get these information and supply services when  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Two-Step** & **1** & **2** & **3** & **4** & **5** & **6** \\ \hline _Time (s)_ & 199.9 & 210.8 & 323.5 & 344.4 & 513.3 & 501.9 \\ _Bandwidth (rad/s)_ & 81.23 & 82.95 & 82.95 & 84.55 & 84.55 & 84.55 \\ _Particle (PSO)_ & 25 & 30 & 30 & 35 & 35 & 40 \\ _Iteration (PSO)_ & 200 & 200 & 500 & 500 & 600 & 600 \\ \hline
**One-Step** & **1** & **2** & **3** & **4** & **5** & **6** \\ \hline _Time (s)_ & 371.7 & 440.5 & 687.2 & 712.9 & 833.4 & 904.2 \\ _Bandwidth (rad/s)_ & 42.58 & 27.33 & 41.14 & 43.64 & 42.74 & 79.18 \\ _Particle (PSO)_ & 25 & 30 & 30 & 35 & 35 & 40 \\ _Iteration (PSO)_ & 200 & 200 & 500 & 500 & 600 & 600 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Comparison results of tuning results between one-step and two-steps.  
Figure 9: Intelligent tuning servo system flowchart.  
needed. Thus, the vendor and users can reduce the maintenance duration and increase the efficiency of the machine tools.  
In addition, when the machine tools have already been in use for some time, and the stiffness of the structure may have changed, Machine Dr. recommends suitable parameters to enhance the bandwidth. Figure 11a shows the results of using the Machine Dr. The current system parameters obtained by system identification are shown in the right column and the suggested controller parameters are listed as below. Furthermore, Machine Dr. also provides the function of remote monitoring, since communication has already been established between the user and the CNC machine tools though the platform. When a user operates the software to survey the machine, the information of the machine is stored in the cloud, which is shown in Figure 11b. As the result, both the user and vendor can monitor the machine operation status, servo parameters, tuning history, etc. by their personal computer (PC) remotely.  
In summary, Machine Dr. combines cloud computing with knowledge of CNC machine tools to develop additional features for CNC machine tools. Machine Dr. provides customers and vendors a more easy method of controlling and obtaining information on machine tools. The vendor can also receive these data from the platform. As the result, the vendor can keep track the condition of CNC machine tools which are sold, and then services can be easily offered. In addition to this, if problems occur with the machine tools, the vendor may obtain the causes of the problems from the data stored in the cloud. Consequently, downtime and customers' service time can be reduced.  
Figure 10: Illustration of the cloud platform—Machine Dr. system; (**a**) functions illustration; (**b**) communication between the user and the cloud servo system.