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Single-port multichannel multi-degree-of-freedom robot 391

sterilized wraps or bags for isolation. As a result, we focus on a robotic endoscopy system
with variable stiffness and multichannel dexterity in this chapter.

17.2 Robotic endoscopy system

17.2.1 Clinical requirements

It is a challenge to perform a surgical operation, especially for a robotic system, as the
environment of the natural orifices of the human body and the operational tasks are
incredibly complex [12]. Both experiments of the clinical surgeons and the characteristics
of the robot-assisted minimally invasive surgery (MIS) are taken into consideration to
summarize the clinical requirements for the robotic system as follows:
1. Size. To access the natural orifice and operate freely, the size of the robotics for
NOTES mainly ranges from [5to [14 mm [13].
2. Dexterity. The degrees of freedom (DOFs) that represent the dexterity of the robot
should not be less than 4 for performing an essential flexible manipulation [14].
3. Load capacity. Manipulating target organs and tissues requires proper load capacity
during the operation while avoiding potential risk from overload. The payload of
surgical robotics ranges from 0.5 to 3 N [13].
4. Channel. To avoid instrument exchange and to maximize operational effectiveness,
a multiinstrumental channel design is necessary. Generally, a minimum of three
endoscopic channels is needed [15].

Currently, it is still a challenge to design surgical robots in NOTES. For example, it is
difficult to propose a sophisticated structure with multiple DOFs and enough strength under
a compact volume. The balance between adequate compliance for safe operation and high
load/accuracy for delicate procedures is not straightforward to achieve. Viable solutions
include designing an optimized mechanism and using materials with excellent properties.

Figure 17.1
Surgical robotic system with variable stiffness for NOTES. (A) 3D model. (B) Prototype.