1. WQE-1

In this research, two type robots have been developed. 1.Rotary inertia type and 2.Reverse screw type.

1.1. Rotational inatia type

The rotary inertia type has a small DC motor with the flywheel and it is covered with spiral fin. The flywheel is accelerated slowly and it is rapidly decelerated when the flywheel reaches the highest velocity. So, the main body rotates by the inertia force. As a result, the robot is moved forward by spiral shape fin. This model's advantage is big energy can be conserved and big inertia force can be outputed continuously.

1.2. Reverse screw type

The reverse screw type has two units which has each clockwise screw fin and anticlockwise screw fin. And, these units are rotated by the DC motor. The opposite direction of the screw and the opposite direction of rotation generate one direction thrust force. This model's advantage is continuous and smooth locomoting. 　We are developing this method now

2. WQE-2

3. WQE-3

3.2.Control(Reinforcement Learning)

The best method of the robot control is trial-and-error when the robot locomote in the colon. Because, locomoting of the robot influences the colon environment and it is impossible to model . Then, the endoscope robot is controlled with the reinforcement learning. The feature of the reinforcement learning is as follows.

Learn while interacting with environment Learn automatically according to an obtained goal adapt uncertain environment It studied by using an actor critic method in the reinforcement learning. The feature is as follows. Drive continously according toprobability program easily

4.WQE-4

We developed a novel prototype of robotic colonoscopy named WQE-4. This robot is driven by a novel pneumatic
actuator which contributes to reduce risks of complications

4.1.Pneumatic actuator

Basic design of the novel pneumatic actuator was inspired from "part horn." This actuator consists of a
polyethylene bag and a flat spiral spring as shown in the picture. Length of the actuator is controlled by changing air
pressure in the bag as shown in the movie. Structure of the actuator was shown in the picture and its motion was
shown in the movie.

Movie

4.2.Hard ware

WQE-4 consists of 11 pneumatic actuators.3 of them are implemented in the tip of the robot (OG) to change driving
direction of the robot as shown in the movie. These 3 actuators are driven respectively by 3 syringe pomp. Other 8
actuators are implemented latter parts (TG1 and TG2) to generate driving force. These 8 actuator are driven
together by 1 large syringe pomp as shown in the movie.

Movies

4.3.Evaluation experiment

Movie

4.4.Future works

5.WQE-5

　A novel active bending mechanism for self propelled colonoscopy robots was designed. A new prototype of the self propelled colonoscopy robot, with the active bending mechanism and locomotion mechanism consisting of pneumatic actuators, was developed.

5.1.Active bend mechanism

　A picture of the active bending mechanism was shown below. It consists of a 3-DOF parallel link mechanism, which was driven by 3 pneumatic syringe actuators. Each syringe actuator is made by stainless. Its diameter is 4 [mm] and its length is 12[mm]. The end effecter, which was connected with each syringe via a passive joint, was made by 3D printer.

5.2.Hard ware

　A new prototype of the self propelled colonoscopy robot, named WQE-5, was developed as shown in the picture. It has the active bending mechanism and trust force generator which was developed for WQE-4. As shown in another picture, the active bending mechanism and the locomotion mechanism were driven by the piston pumps. WQE-5 obtains the forces for translate and rotate motions by driving these pumps with specific patters.

Movies

5.3.Evaluation experiment

　A colon model was prepared for the evaluation of WQE-5. The diameter of the model was 50[mm], and its length is 200[mm]. It was set on the table to make a curve. The radius of the curve was 140[mm]. The locomotion speeds of WQE-5 were measured under different conditions of the bending angle θ. In each trial, WQE-5 was put at the start point, and the locomotion distance during 30 sec was then measured to calculate the locomotion speed.

　6 trials were performed under each condition of the bending angle θ as shown in the table.

　The locomotion speed was largest when the bending angle θ was 5 [deg]. We consider that the active bending mechanism is effective because the locomotion speed at θ=5 [deg] was larger than that at θ=0 [deg]. However, the locomotion speed at θ=74 [deg] was lower than that at θ=0 [deg]. It suggests that the bending angle should be controlled according to the angle of the curve of the colon.

5.4.Future works

　Current locomotion speed of WQE-5 is not enough to use it in clinical practices. We consider that it can be much improved by optimization of the control.
　More experimental evaluations, such as experiments with animals, are required to show effectiveness and safety of WQE-5.