1. Shortening colonic fold (SCF)

　 We observed the colonoscopy of doctors for obtaining the knowledge to decide how to assist the insertion of colonoscope. The shape of the colon model when a colonoscope was inserted by a doctor is shown below.
　 We found the model's deflection was linearized after insertion of the colonoscope. (We named this technique to linearize and shorten colon SCF: shortening colonic fold.) Additionally, it was found that SCF was difficult.

　 So, we has devised that robot do SCF. The idea is that the robot hauls intestinal wall by operating as shown in the figure below, and then achives SCF.

2. Prototypes

2.1. WQEM-1（Waseda Q:Kyudai Endoscope assist Manipulator No.1）

　 We developed a first prototype WQEM-1 that operated hauling motion. Distal part of WQEM-1 can be attached to existing endoscopes, and driven by motors outside body through wires.
　 WQEM-1 could haul the colon model.

Movies

1. WQEM-1 idling
2. WQEM-1 hauling the colon model

2.2. WQEM-2（Waseda Q:Kyudai Endoscope assist Manipulator No.2）

　 We developed second prototype WQEM-2 that had new mechanism to bend passively at flexure colon and aim of improving its hauling speed with the same hauling mechanism remained.
　 The manipulator part's stiffness is changed by tension of wires inside.(Stiffness transition mechanism) The tension is dependent on the length of wires inserted in the manipulator. The manipulator becomes stiff state that can haul when it has high stiffness, and becomes flexible state that can bend passively when it has low stiffness.

Movies

1. WQEM-2 idling
2. WQEM-2 hauling the colon model
3. mechanism outside body

2.3. Experiments

　 First, we measured hauling speed of WQEM. We drived WQEM in the colon model placed as straight, and measured the length of the model hauled during 30[s]. The hauling speed calculated from the rusults is shown in below.
　 The hauling speed is need to be more than 4[mm/s], taking into account the observation of colonoscopy by experts. WQEM-2's hauling speed was about 9.8[mm/s], so it met the requirement.

　 Second, we asked doctors to insert the endoscope with/without WQEM-2 as simulations. The measured time required to pass the sigmoid descending junction (SDJ) from the anus is shown below.
　 The required time was reduced 60[%] on average by using WQEM-2. Therefore the effectiveness of hauling by WQEM was suggested.

3. Future Works

　　Some doctors who worked with us said damage to the colon was concerned. Thus development of devices with high safety is the major issue. And it is also an issue that WQEM couldn't operate in entire colon. We think it is needed to develop that the stiffness transition mechanism wchich have lower stiffness in the flexible state for passing the flexure colon.