## 1 Introduction  
### Background  
Robotic technology has been introduced as a type of minimally invasive surgical approach to reducing the physical and economic burden on patients. The novel operation method using robotic technology is expected to reduce the physical burden on surgeons, and to achieve more accurate operations that are difficult to perform under conventional conditions. One of the surgical fields in which this robotic technology is expected to be introduced is the pediatric surgical field. In pediatric surgery, patients ranging from newborn babies to children who are approximately 15 years old are treated. In particular, treatment during the newborn period is important because it can suppress the onset of acquired symptoms. However, the insertion of a hand by the surgeon into the body of a newborn baby is difficult due to the small size of the patient's body and the space available for treatment. In addition, this operation makes it difficult because the target organs of newborn babies are very soft, fragile, and underdeveloped when compared with those of adult patients. Hence, a procedure in pediatric surgery is required to carry out delicate movements within a restricted space. To solve this problem, robotic technology for pediatric surgery is required, given that the robot can miniature the size of its own mechanism in addition to performing an accurate movement using a control system. Commonly used surgical instruments are designed to treat adult patients; thus, there is a critical problem in that the instruments are as large as the tools used for treatment in pediatric surgery. Therefore, the da Vinci\({}^{\text{\textregistered}}\)Surgical System (Intuitive Surgical Inc.) was developed as a clinical application robot. In the case report about the da Vinci\({}^{\text{\textregistered}}\)Surgical System used in pediatric endoscopic surgery, [PERSON] [1] and [PERSON] [2] reported that complex procedures can be carried out by surgeons using a surgical assisted robot, and that the application of robotic technology to pediatric surgery is effective. In addition, compared with conventional laparoscopic surgery, the effectiveness of the robot was reported regarding the three-dimensional (3D) high-quality vision, advanced instrument movement, and improved ergonomic position of the surgery in the field of pediatric surgery [3; 4]. Moreover, the advantages to the surgeon's intuitive and delicate procedure were presented with respect to the multi-degree-of-freedom mechanism of the surgical tool, the scaling function, and the operative field obtained using a 3D image. By taking advantage of the surgical assisted robot, the burden on the surgeon can be reduced, even in a pediatric environment with a small surgical workspace. In addition, the patient can undergo treatment in the same manner, irrespective of their physical constitution. However, given that the da Vinci\({}^{\text{\textregistered}}\)Surgical System was also developed for adult patients, it is difficult to directly apply this robot to pediatric surgery. The size of the surgical instrument is excessively large when this device is applied to newborns and infants. Moreover, it was highlighted that the following issues have a significant influence on the treatment outcome: the limitation of the surgical tool's operation [3; 4; 5], the obstruction of endoscopic vision [2], and the position of trocars [6]. As one of the commercial examples, the Endo Wrist\({}^{\text{\textregistered}}\), which has a forceps diameter of 5 mm, was developed for the da Vinci\({}^{\text{\textregistered}}\)Surgical System to solve these drawbacks as a surgical tool for pediatric surgery. However, [PERSON] reported that the size of the surgical workspace slightly exceeded that of the workspace using surgical tools for adult surgery due to structural problems [7]. [PERSON] et al. performed the verification of the safety and accuracy of the Neuromate\({}^{\text{\textregistered}}\)stereotactic robot for deep brain stimulation in childhood [8].