Intuitive master device for endoscopic robots with visual-motor correspondence.

BACKGROUND: Master devices exclusively used for endoscopes with position control are being developed as an isomorphic form of endoscopes. These master devices are difficult to intuitively operate because the movement direction of the endoscopic image and control handle do not match. METHODS: To solve this problem, a master device was developed. Its movement direction is compatible with that of the endoscopic image. It analyzes image movements according to flexible endoscopic ureteroscope movements for each degree of freedom. A driving testbed experiment was conducted that modelled the internal structure of a kidney. RESULTS: The time taken in the experiment was shorter when using the proposed master device than the existing isomorphic master device. The proposed device yielded fewer mistakes. CONCLUSIONS: It was confirmed the proposed device is effective in exclusive use for endoscopes because of its feasibility of position control and movement direction's coinciding with that of the endoscopic image.

Analysis of tendon tension and hysteresis by tendon twisting and development of anti-twist tendon mechanism of robotic surgical instruments.

BACKGROUND: Control of the joints of robotic surgical instruments is difficult owing to hysteresis, and tendon twisting due to axial rotation of surgical tools also causes hysteresis. Therefore, a new mechanism is needed to prevent tendon twisting. METHODS: Tendon tension and hysteresis change were analysed by observing the movement of the joint depending on whether the tendons twisted for the same input signal. An anti-twist tendon mechanism to prevent twisting was developed. A 3-mm needle driver applied with the proposed mechanism was manufactured. RESULTS: The anti-twist mechanism makes no tension change because of twisting or friction between the tendon and the system, that is, the operating performance was the same regardless of rotation. CONCLUSION: The proposed mechanism has been verified and can be applied to small surgical instruments 3 mm in size. These findings can be applied in the development of instruments for precise surgeries such as microsurgery.

A highly intuitive and ergonomic redundant joint master device for four-degrees of freedom flexible endoscopic surgery robot.

BACKGROUND: Studies have been conducted on slave-specific master devices with a similar kinematic structure to the slave to enhance intuitiveness. However, for the four-degrees of freedom (DOFs) slave of a flexible endoscopic surgery robot, only four DOFs in the master device causes low ergonomic performance. METHODS: To enhance ergonomic performance, a second yaw joint was added as a redundant joint after considering the range of wrist motion and the workspace shape. Three experiments were performed to compare the intuitiveness and ergonomic performance of the proposed device with four-DOFs slave-specific and six-DOFs general-purpose master devices. RESULTS: Significant differences were observed in terms of intuitiveness performance between the slave-specific and the general-purposed master device. On the other hand, there was no significant difference in ergonomic performance between the master devices with redundant joint. CONCLUSIONS: Compared with a general-purpose master device, the proposed one exhibited noticeably improved intuitiveness performance and comparable ergonomic performance.