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X-rays, discovered in 1895, contributed to the amazing development of modern medicine by enabling the observation of the inside of the body, and have been used as a means of "definitive diagnosis" for over 100 years since then. In recent years, with the establishment of X-ray photography technology that does not use film, the functions required of X-ray diagnostic systems have become more diverse, such as 3D diagnosis and treatment under X-ray fluoroscopy.
However, medical devices have many challenges that must be overcome beyond performance alone, which causes problems for developers.
Company U, which plans, manufactures, and sells medical equipment, was conducting research and development of a new X-ray diagnostic system to meet increasingly sophisticated medical needs.
This next-generation X-ray diagnostic system enables surgical procedures under X-ray fluoroscopy and whole-body imaging from the head to the lower extremities. To position the patient as the treating technician wishes and obtain stable, clear images, the arms and examination table must be able to move smoothly and with high precision.
However, achieving these goals was not an easy task, and it was troubling U Company's development department. The company had been using the same model of general-purpose servo system for each product, but when they implemented it in a prototype of a new model and tested it, they found that they were unable to sufficiently suppress the vibration at the tip of the arm when creating 3D measurement data. Mr. J from the company's Technology Development Department explains:
"Because the servo system was a type that had been in use for the past 10 years, it did not yet have the function to suppress vibration at the tip of the arm. In fact, due to the Pharmaceutical Affairs Law, any change to the installed parts requires an application and approval process. Since the application process takes a long time, considering the development time and cost, it was preferable to reuse parts that had already been approved. However, in order to meet the user's need to improve treatment efficiency, we had no choice but to take the plunge and choose a new servo system."
In addition, the problem of miniaturizing the device was bothering Mr. J.
In the limited space inside a treatment room, it is necessary to use multiple medical devices to perform advanced medical procedures, so it was essential to reduce the space required for each piece of medical equipment.
In addition, in the conventional X-ray diagnostic system, the entire device was equipped with six-axis servo motors, and products from two manufacturers were mixed for each specification. Until now, there was no problem with this, but in the next model, we were planning to connect the controller and servo system via serial communication, so if the communication specifications differ depending on the manufacturer, the system would become complicated.
"Using serial communication and reducing wiring not only reduces costs, but also has major benefits in terms of reducing problems and maintenance," says J.
After receiving a detailed explanation, Mr. J arranged for a prototype servo system for evaluation and carried out the evaluation. He verified the performance of the "new vibration suppression control", which is essential for smooth movement of the arm and high-precision images.
"This was my first time using the vibration control function, and it exceeded my expectations. With our previous system, the tip of the arm would inevitably vibrate significantly when moving, but we were able to reduce the amplitude to less than one-tenth of what it was now. No matter what movement we made, the vibration at the tip of the arm was imperceptible to the naked eye. If we can suppress vibration, then of course image precision will improve. I'm convinced that this will make a major contribution to improving treatment efficiency." (Mr. J)
Furthermore, during amplifier testing, we confirmed that the amplifier supports the open serial communications standard "EtherCAT," and therefore can operate without problems with controllers made by other companies.
"Developing the controller will likely take some time, but as it is an ultra-high-speed field bus system with a transfer rate of 100 Mbps, we can expect accurate synchronization to be ensured with transfer and processing speeds that are orders of magnitude faster than anything we have had up until now. In addition, multiple devices, including servo systems made by other companies, can be connected via the same EtherCAT communications. By replacing our 10-year-old servo amplifier, the volume has been reduced by 62%, and the overall length of the motor has also been shortened, so we are hopeful that we will be able to achieve significant space savings for the entire equipment." (Mr. J)
The adoption of the new servo system has many possibilities, including miniaturization, reduced wiring work, reduced development costs, and fewer malfunctions and errors. These have been a big step forward in resolving the company's development challenges.
After thorough verification, Company U decided to adopt SANYO DENKI CO., LTD. 's new AC Servo Systems judging it to be effective in developing a new X-ray diagnostic system.
After that, in parallel with the development of the controller, the company installed a prototype controller and performed operational verification. At that time, SANYO DENKI CO., LTD. dispatched service staff to follow up on optimal gain adjustments and continued to support U company thereafter.
"Because they were always there to personally visit us, we were able to adjust the gain to achieve the optimal characteristics, and we were able to get prompt answers to all the little things we didn't know afterwards, which allowed us to move forward smoothly with design and development. I feel that it was this kind of service ability, in addition to the high performance of the servo system itself, that enabled us to succeed in developing the next model." (Mr. J)
Although still in the prototype stage, the next-generation X-ray diagnostic system is performing as expected. SANYO DENKI CO., LTD. 's servo system has reduced the size of the new X-ray diagnostic machine by 15% and improved image accuracy by approximately 20%.
Mr. J. said:
"Thanks to SANYO DENKI CO., LTD. 's proposal, we were able to find a way forward in developing a new X-ray diagnostic system. As advances in medical technology and diversifying needs make it imperative to develop equipment equipped with more advanced technology, I believe that this servo system, with its excellent functions and performance, will continue to be a great help in the future."
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