| Current needle holders, graspers, and other tools transmit a surgeon's hand motions by passive mechanics. As the instruments slide, twist, and pivot through the point at which they enter the body wall, they are four-degree-of-freedom manipulators. Consequently, the surgeon can reach points within a three-dimensional volume but cannot fully control orientation. For simple tasks this is not a major hindrance, but it makes complex skills such as suturing and knot tying extremely difficult. Also, the instrument handles are anchored with respect to the patient and it is difficult for the surgeon to align the video display to the camera and instrument axes, resulting in misleading perspective cues. To address these difficulties,laparoscopic manipulators that are more versatile and dextrous are being designed with multi-degree-of-freedom end effectors with an appropriate surgeon-machine interface. |
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