## 2 7 DOFs VI Robotic System
### Master Devices of AI Robotic System  
In this study, two types of master devices were tested in the in vivo experiments. The first master device has 2 DOFs, as shown in Figure 3. The motion of this device was inspired by the movement of the operator's hand during the VI procedure. In the conventional VI procedure, the catheter and guidewire are manually operated. Thus, the ergonomically designed 2 DOFs master device was implemented to involve the same motions as those in the conventional VI procedure.  
Upon the activating button being pressed, the command from the master device is transferred to the VI slave robot. Further, a mode switch button is used to change the  
Figure 3: Motions and buttons of the ergonomically designed 2 DOFs master device.  
Figure 2: Schematic of the slave robot: (**a**) **5** DOFs robot arm for positioning the slave robot; (**b**) **7** DOFs VI slave robot mounted on the bed.  
catheter control mode to the guidewire control mode and vice versa. This master device adopts the position-position control method, where the displacement of the VI slave robot is proportional to that of the master device.  
The advantage of the ergonomically designed 2 DOFs master device is that it mimics the movement of the operator's hand. Therefore, any operator can easily and intuitively use it. Conversely, the disadvantage of this device is that the operator has to perform repetitive motions to send the catheter and the guidewire to the target vessel. Using a motion scale, the operator can easily manipulate the catheter or the guidewire. However, the operator may feel physical burden/fatigue when operating this master device for a long duration.  
The second master device also has 2 DOFs, as shown in Figure 4a and a joystick-type structure comprising two hemisphere-type linkages. These linkages were coupled to the joystick handle at the center of the device so that insertion and rotation of either the catheter or the guidewire could be achieved using the two rotational degrees of the joystick. Two buttons were placed on the right side of the device. Similar to the ergonomically designed master device, the slave robot could move only when the button was pressed. Further, a mode switch button was used to change the catheter control mode to guidewire control mode and vice versa. The joystick-type master device adopts the position-velocity control strategy, where the velocity of the VI slave robot is proportional to the position command of the master device. In the 2 DOFs joystick-type device, the motion speed of the VI slave robot increased as it moved farther away from the center of the joystick structure.  
The merit of the 2 DOFs joystick-type master device with position-velocity control is that the operator does not have to perform repetitive motions, which can save time and physical effort of the operator. The operation of the master device is similar to that of gaming joystick-type device. The disadvantage of the 2 DOFs joystick device, however, is that the operator requires more time to get used to the 2 DOFs joystick master device because the control modes of the conventional VI procedure and 2 DOFs joystick-type device are different.