Improved surgical instruments without coupled motion used in minimally invasive surgery

Background: Unlike a manual surgical instrument, a surgical instrument used in robot-assisted minimally invasive surgery (MIS) is configured with a wrist to improve flexibility in surgical operation. However, this configuration has a shortcoming that leads to coupled motion between the wrist and end-effector. Methods: Three methods are presented to eliminate the coupled motion between the wrist and end-effector. The three methods are compared via the decoupled motion characteristic, and the third method is applied to design four surgical instruments. Several experiments are done to validate the effectiveness of these surgical instruments. Results: These improved surgical instruments create decoupled motion. The results of experiments on the removal of gall bladder and kidney are excellent, which validates the effectiveness of decoupled surgical instruments. Conclusions: Improved surgical instruments without coupled motion are developed and have a promising clinical application in MIS.