Medical robotic systems such as teleoperative systems used in performing minimally invasive surgical procedures offer many benefits over traditional open surgery techniques, including less pain, shorter hospital stays, quicker return to normal activities, minimal scarring, reduced recovery time, and less injury to tissue. Consequently, demand for such medical robotic systems is strong and growing.
One example of such a medical robotic system is the da Vinci® Surgical System from Intuitive Surgical, Inc., of Sunnyvale, Calif., which is a minimally invasive robotic surgical system. The da Vinci® Surgical System has a number of robotic arms that move attached medical devices, such as an image capturing device and Intuitive Surgical's proprietary EndoWrist® articulated surgical instruments, in response to movement of input devices by a surgeon viewing images captured by the image capturing device of a surgical site. Each of the medical devices is inserted through its own minimally invasive incision into the patient and positioned to perform a medical procedure at the surgical site. The incisions are placed about the patient's body so that the surgical instruments may be used to cooperatively perform the medical procedure and the image capturing device may view it without their robotic arms colliding during the procedure.
A minimally invasive surgery may employ a number of different surgical instruments. When a different tool is desired during the surgical procedure, the surgical instrument may be withdrawn from the surgical site so that it can be removed from its associated arm and replaced with an instrument bearing the desired end effector. The desired surgical instrument is then inserted into the surgical site. A surgical instrument may also be withdrawn from a surgical site for reasons other than to replace the end effector. For example, the loading of a clip in a clip applier used in affixing tissue may occur outside the patient's body. In this case, each time a new clip is desired, the clip applier may be removed from the surgical site to load the clip and then reintroduced into the patient's body to apply the clip. As another example, removal of tissue or an object within a patient may involve grasping the tissue or object with an end effector while withdrawing the surgical instrument from the patient's body so that the tissue or object held by its end effector may be removed.
To perform a tool exchange for a medical robotic system, however, takes time. Moreover, it may be difficult to bring the new tool into the field of view manually after a tool exchange operation. It is also possible for the operator to misjudge the depth of insertion and place the tool too deep into the surgical site, which may cause unintended contact between the tool and the patient's anatomy. To avoid such contact, the operator is likely to move the new tool very slowly into the surgical site. These factors contribute to make a tool exchange operation a time-consuming process.
U.S. Pat. No. 6,645,196, which is incorporated herein by reference, describes a guided tool exchange procedure employable in a medical robotic system, such as the afore-described da Vinci® Surgical System, to guide a new tool quickly and precisely, after a tool exchange operation, into close proximity to the operating position of the original tool prior to its removal from a surgical site.
To perform certain medical procedures, it may be advantageous to use a single entry aperture, such as a minimally invasive incision or a natural body orifice, to enter a patient to perform a medical procedure. For example, an entry guide may first be inserted, positioned, and held in place in the entry aperture. Instruments such as an articulated camera and a plurality of articulated surgical tools, which are used to perform the medical procedure, may then be inserted into a proximal end of the entry guide so as to extend out of its distal end. Thus, the entry guide provides a single entry aperture for multiple instruments while keeping the instruments bundled together as it guides them toward the work site.
Due to the limited number of articulated instruments that may be disposed in the entry guide at one time, it may be necessary to exchange one articulated instrument in the entry guide for another instrument that performs a different function during the performance of a medical procedure. Alternatively, in lieu of exchanging the articulated instrument, only its end effector may be changed. As used herein, the phrase “tool exchange” is to be understood to cover both cases. To perform the tool exchange, the articulated instrument is retracted back into the entry guide and taken out through the entry guide's proximal end while other articulated instruments extending out of the distal end of the entry guide are either held in place or controlled by associated input devices. A new instrument (or old instrument with a new end effector) is then inserted into the entry guide and extended out of the entry guide's distal end. To retract the articulated instrument back into the entry guide, it may be necessary to first change the pose of the instrument (i.e., reconfigure its joints and links) so that it can be fully retracted into the entry guide. Since the instrument being retracted into the entry guide may be outside the field of view of an articulated camera instrument also extending out of and fixed in position relative to the distal end of the entry guide, possible collisions with other objects is a safety concern during blind retractions of an old tool into the entry guide from a surgical site and blind insertions of a new tool out of the entry guide towards the surgical site.