Abstract:
A robotic surgical system includes a master manipulator, slave robotic units having a surgical instrument for performing a Minimal Invasive Surgery (MIS), and a control system for electrically associating the master manipulator with the slave robotic units. The slave robotic unit includes the driving mechanisms which are more compact than those of the conventional MIS system. In use, the existing surgical instruments used in the conventional MIS procedure can be applied to the slave robotic unit. Moreover, by using the pivotal mechanism of the driving mechanisms, a pivot point of the surgical instrument is allowed to be shifted with respect to an incision of a patient. So, the patient&#39;s tissues surrounding the surgical instrument are not excessively affected by the surgical instrument during the procedure.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a robotic surgical system; and, more particularly, to a robotic surgical system having a plurality of compact slave robotic arms capable of performing laparoscopic surgery in minimal invasive manner. 
     BACKGROUND OF THE INVENTION 
     Generally, there have been attempts to perform a minimally invasive surgical (MIS) procedure. Such MIS techniques are aimed at reducing the amount of extraneous tissue that is damaged during diagnostic or surgical procedures, thereby reducing patient recovery time, discomfort, and deleterious side effects. The most common form of such procedures is laparoscopy, which is used for minimally invasive inspection and surgery inside the abdominal cavity. To perform such MIS procedures, a surgeon needs special instruments. The surgeon passes these instruments through a small incision of an abdominal wall to a surgical site and manipulates them from outside the abdominal wall by sliding them in and out through the abdominal wall, rotating and pivoting them against the abdominal wall. However, it has been found that a high level of dexterity is required to accurately control such instruments. And, the surgeon has no flexibility of tool replacement. Additionally, he or she experiences difficulty in approaching the surgical site through the incision. The length and construction of many instruments reduces the surgeon&#39;s ability to feel forces exerted by the surgical site on the instruments. Further, human hands typically have at least a minimal amount of tremor. The tremor further increases the difficulty of performing minimally invasive surgical procedures. So, only a relatively small number of surgeries have been performed due to limitations in required instruments, techniques and the surgical training. 
     Therefore, minimally invasive surgical robotic systems have been currently developed to increase a surgeon&#39;s dexterity when working within an internal surgical site as well as to allow a surgeon to operate on a patient from a remote location while monitoring a procedure by means of, e.g., a viewer which displays a three dimensional image of the surgical site via a camera. By means of the robotic systems, the surgeon can manipulate surgical instrument movements without directly holding and moving the instruments by hand. In such robotic systems, the surgical instruments can be precisely operated and be remotely controlled in a minimally invasive manner. 
     A robotic surgery is getting increasing attention with the wider application of the laparoscopic surgery. Actually, surgeons can do more efficient surgery with the enhanced dexterity and intelligent assistance provided by the robotic system. 
     Conventional robotic surgical systems are disclosed in e.g., U.S. Pat. No. 6,102,850 entitled “Medical Robotic System”, and U.S. Pat. No. 6,364,888 entitled “Alignment of Master and Slave in a Minimally Invasive Surgical Apparatus”. However, up to the present, the currently commercially available robotic surgical systems have drawbacks for abdominal surgery such as a huge system with bulky robotic arms, expensive cost, and so forth. Such a robotic system requires a large installation space and can not fully ensure an accurate surgical procedure. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide a robotic surgical system provided with a pivotal mechanism for adjusting a pivot point of a surgical instrument. 
     In accordance with the present invention, there is provided a robotic surgical system including: 
     a master manipulator installed at a control station to be manipulated by an operator; slave robotic units for performing a surgical procedure on a patient; a control system for electrically associating the master manipulator with the slave robotic units to allow each slave robotic unit to be remotely controlled by the associated master manipulator; and a display for viewing the surgical procedure conducted by the slave robotic units. 
     Each slave robotic unit includes: 
     a surgical instrument being inserted to a surgical site of the patient; a yaw driving mechanism for moving the surgical instrument in a yaw direction; a pitch driving mechanism for moving the surgical instrument in a pitch direction; a linear driving mechanism for linearly moving the surgical instrument; a rotational driving mechanism for rotating the surgical instrument about its longitudinal axis; an end tip driving mechanism for incising, sewing or cutting the surgical site; and a pivotal mechanism for allowing the surgical instrument to be freely pivoted. 
     Preferably, the pivotal mechanism includes: a lower part engaged with the pitch driving mechanism; a middle part pivotally connected to the lower part; and an upper part pivotally connected to the middle part, the upper part being fixed to the linear driving mechanism. 
     Preferably, the pivot movements of the middle part and the upper part are orthogonal to each other. 
     In accordance with the robotic surgical system of the present invention, the driving mechanisms are more compact than those of the conventional system. Furthermore, the existing surgical instruments used in the conventional MIS procedure can be applied to the robotic surgical system of the present invention. Moreover, the pivotal mechanism allows the pivot point of the surgical instrument to be shifted with respect to the incision, the patient&#39;s tissues surrounding the surgical instrument are not excessively affected by the surgical instrument during the procedure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects and features of the present invention will become apparent from the following description, given in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a robotic surgical system in accordance with a preferred embodiment of the present invention; 
         FIG. 2A  is a perspective view of one of slave robotic arms of the robotic surgical system shown in  FIG. 1 ; 
         FIGS. 2B and 2C  are a front view and a side view of the slave robotic arm shown in  FIG. 2A , respectively; 
         FIG. 3  is a front view of a carriage of the slave robotic arm in accordance with the present invention; 
         FIGS. 4A and 4B  are a front view and a side view of a linear guide of the slave robotic arm in accordance with the present invention, respectively; 
         FIG. 5A  is a side view of a pivotal mechanism in accordance with the present invention; 
         FIG. 5B  is an exploded perspective view of the pivotal mechanism shown in  FIG. 5A ; 
         FIG. 5C  is a perspective view of the pivotal mechanism which is mounted on the linear guide; 
         FIG. 6  is a side view of a surgical instrument of the slave robotic arm in accordance with the present invention; 
         FIG. 7  is a diagram for explaining the shift of an original pivot point P 1  to a new pivot point P 2  with the help of the pivotal mechanism in accordance with the present invention; and 
         FIGS. 8A and 8B  are a side view and a perspective view of a master manipulator in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, a robotic surgical system in accordance with a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
     Referring to  FIG. 1 , the robotic surgical system includes a plurality of slave robotic units  200  for performing a surgery on a patient P lying on an operation table T; and master manipulators  800 , which are installed in a control station  100 , for allowing an operator O to remotely control the slave robotic units  200 . The control station  100  includes a control system (not shown) for converting movements of the master manipulator  800  into electrical signals; and a display D for allowing the operator O to see surgical procedures conducted by the slave robotic units  200 . At least one of the slave robotic units  200  has an endoscope (not shown) for allowing the operator O to view a surgical site through the display D while doing an operation. 
     Referring to  FIGS. 2A to 2C , the slave robotic unit  200  includes a wrist  204 , a semicircular rack gear guide  205 , a carriage  300 , a linear guide  400 , a pivotal mechanism  500  and a surgical instrument  600 . The surgical instrument  600  is mounted on the slave robotic unit  200  and can reach the surgical site (not shown) through an incision (not shown). The slave robotic unit  200  further includes forearms  201 ,  203  and a holder  202 . As shown in  FIG. 1 , the slave robotic unit  200  is fixedly mounted on the operation table T by using a holder  202 . 
     The wrist  204  is pivotally coupled to a shaft (not shown) in the forearm  203  and is rotated clockwise or counterclockwise in a yaw direction as indicated by the arrows S 1  by a motor (not shown) in the forearm  201 . The shaft is outwardly protruded and engaged to one end of the wrist  204 . Further, the semicircular rack gear guide  205  is fixedly coupled to the other end of the wrist  204 . 
     The carriage  300  is movably mounted on the semicircular rack gear guide  205 . Referring to  FIG. 3 , the carriage  300  includes a motor  301 , a pair of guide rollers  302 , connectors  303  and a pinion gear  304  being rotated by the motor  301 . The semicircular rack gear guide  205  (indicated by the dashed lines in  FIG. 3 ) is provided between the guide rollers  302  and the pinion gear  304 . Accordingly, the carriage  300  can be moved along the semicircular rack gear guide  205  in a pitch direction as indicated by the arrows S 2 . So, the carriage  300  can be moved in two degrees of freedom along the arrows S 1  and S 2 . Additionally, the carriage  300  is coupled via the connectors  303  to the pivotal mechanism  500  to be described later. 
       FIGS. 4A and 4B  show the linear guide  400  including motors  401 ,  402 , rollers  403 , a fastener  406 , and gears  404 ,  405 . The upper motor  401  allows the surgical instrument  600  (shown by the dashed lines in  FIGS. 4A and 4B ) to rotate as indicated by the arrows S 3 , and the lower motor  402  allows the surgical instrument  600  to move up and down linearly as indicated by the arrows S 5 . The rotational movement S 3  is controlled by the gears  404  and  405  which are driven by the upper motor  401 , and the linear movement S 5  is controlled by the rollers  403  which are driven by the lower motor  402 . The surgical instrument  600  is positioned between the rollers  403  to be moved linearly by rotations of the rollers  403 . Additionally, the pivotal mechanism  500  is fixedly mounted on the linear guide  400  by using the fastener  406 . 
     As described above, the slave robotic unit  200  is provided with the yaw driving mechanism, the pitch driving mechanism, the linear driving mechanism and the rotational driving mechanism. The slave robotic unit  200  is further provided with the end tip driving mechanism and the pivotal mechanism  500  as will be described later. 
     The yaw driving mechanism serves to move the surgical instrument  600  in the yaw direction S 1 . The yaw driving mechanism includes the forearms  201  and  203 ; the motor (not shown) installed in the forearm  201 ; the shaft (not shown) rotated by the motor; and the wrist  204  coupled to the shaft. The wrist  204  is moved in the yaw direction S 1  by the shaft. 
     The pitch driving mechanism serves to move the surgical instrument  600  in the pitch direction S 2 . The pitch driving mechanism includes the semicircular rack gear guide  205  coupled to the wrist  204 ; the carriage  300  movably mounted on the semicircular rack gear guide  205 ; the motor  301 , the pinion gear  304  and the guide rollers  302 . The carriage  300  is moved along the semicircular rack gear guide  205  in the pitch direction S 2 . Further, the carriage  300  is also rotated in the yaw direction S 1  about an axis of the wrist  204  together with the semicircular rack gear guide  205  rotated by the yaw driving mechanism. 
     The linear driving mechanism serves to move the surgical instrument  600  linearly through the incision as indicated by the arrows S 5 . The linear driving mechanism includes the linear guide  400 , the lower motor  402  and the rollers  403  provided in the linear guide  400 . The rollers  403  are driven by the lower motor  402 . The surgical instrument  600  is inserted between the rollers  403  so as to be linearly moved by the rollers  403 . 
     The rotational driving mechanism includes the upper motor  401  and the gears  404 ,  405  of the linear guide  400 . The gear  404  is driven by the rotation of the gear  405 , to thereby rotate the surgical instrument  600  as indicated by the arrows S 3 . 
     Referring to  FIGS. 5A to 5B , the pivotal mechanism  500  includes a lower part  501 , a middle part  502 , an upper part  503 . The parts  501  to  503  are pivotally coupled to each other by using bolts  502   a  and  503   a . The lower part  501  is engaged with the carriage  300  by coupling connectors  501   a  to the connectors  303  of the carriage  300 . The lower part  501  and the middle part  502  can be pivoted relative to each other as indicated by the arrows J 2 , and the upper part  503  and the middle part  502  can be pivoted relative to each other as indicated by the arrows J 1 . The movements J 1  and J 2  are orthogonal to each other. The pivotal mechanism  500  is not actively motor driven. Furthermore, the movements J 1  and J 2  are orthogonal to the movements S 1  and S 2 , respectively. 
     Additionally, the linear guide  400  is fixed to the upper part  503  by using the fastener  406 . In that case, a shaft (not shown) of the motor  401  is inserted through a hole  503   d  of a protruding portion  503   c  to be engaged with the gear  405 . With such arrangements, the linear guide  400  can be pivoted relative to the carriage  300  as indicated by the arrows J 1  and J 2 . 
     Referring to  FIG. 6 , the surgical instrument  600  includes a motor  601 , an electric wire  602 , a rod  603 , fingers  604  and a pivot connection  605  for the end tip driving mechanism. A pair of fingers  604  is pivotally coupled to the pivot connection  605 , for incising, sewing and cutting a tissue of the patient P. A wire (not shown) is connected between the fingers  604  and the motor  601  through the rod  603 . The motor  601  is provided to an upper end of the surgical instrument  600  and serves to pull and release the wire. The electric wire  602  is connected to a force feedback sensor (not shown) in the surgical instrument  600 . The force feedback sensor detects a feedback force applied to the fingers  604  and transmits a signal of the feedback force via the electric wire  602  to the control system. It will be appreciated that the fingers  604  can be angularly displaced about the pivot connection  605  toward and away from each other as indicated by the arrows S 4 . 
     With reference to  FIG. 7 , there will be described an operation of the pivotal mechanism  500  of the present invention. When the surgical instrument  600  inserted through an abdominal wall W of the patient P is pivoted about an original pivot point P 1 , normally, a port of entry on the abdominal wall W, the pivot point of the surgical instrument  600  is shifted from the original pivot point P 1  to a new pivot point P 2 . In the present invention, by the help of the above-mentioned movements J 1  and J 2  of the pivotal mechanism  500 , the surgical instrument  600  is pivoted to be in alignment with the pivot point P 2 . It will be appreciated that the shifted pivot point P 2  remains stationary throughout the surgical procedure. Accordingly, tissues of the abdominal wall W surrounding the surgical instrument  600  are not excessively affected by the surgical instrument  600 . Preferably, the distance between P 1  and P 2  is about 50 mm or less. 
     Referring now to  FIGS. 8A and 8B , the master manipulator  800  includes a shaft  812 ; a toothed belt  802  provided to the shaft  812 ; a lever  810  for allowing the shaft  812  to slide as indicated by the arrows M 5 ; pivotal connections  805 ,  806 ; a spring-biased wire wheel  801  for aiding the movement of the shaft  812  with an additional force; a wire  807  being wound up into the spring-biased wire wheel  801  as the shaft  812  moves upward, and vice versa; a handle  804  rotatably engaged with the pivotal connection  806 , and being gripped by a hand of the operator O; finger seats  803  pivotally coupled to the handle  804 ; and a motor assembly  809  for aiding and sensing the movement of the master manipulator  800 . 
     The lever  810  can be pivoted as indicated by the arrows M 1  by connecting a first portion  811  of the lever  810  to an arm (not shown) installed in the control station  100  (see,  FIG. 1 ). A second portion  813  of the lever  810  can be pivoted about a connection  808  with respect to the first portion  811  as indicated by the arrows M 2 .  FIG. 1  indicates that the master manipulator  800  is installed in the control station  100 . The master manipulator  800  can be displaced angularly as indicated by arrows M 1  and M 2 . 
     The finger seats  803  can be angularly displaced about the handle  804  toward and away from each other as indicated by the arrows M 4 . And, the handle  804  can be rotated about the pivotal connection  806  as indicated by the arrows M 3 . The pivotal connection  806  can also be pivoted about the pivotal connection  805 . 
     Now, the electrical connections with the master/slave movements in the control system will be described. 
     Each slave robotic unit  200  is operated and moved in response to movement demands from its associated master manipulator  800 . Preferably, sensors (not shown, e.g., encoders, potentiometers or the like) are provided to the master manipulator  800  and the slave robotic unit  200 . The control system receives input signals from the master manipulator  800 , computes a corresponding movement of the surgical instrument  600  and determines positions and orientations of each slave robotic unit  200  based on the received input signals. Accordingly, the movement M 1  of the master manipulator  800  is translated to the corresponding movement S 1  of the slave robotic unit  200 . Similarly, the movements M 2  through M 5  are, respectively, translated to the movements of S 2  through S 5 . 
     Meanwhile, the operator O can feel feedback forces by the master manipulator  800  electrically connected with the associated slave robotic unit  200  during the operation thereof, so that the operator O can more exactly control the surgical instrument  600 . 
     The following is a description of an operation of the surgical robotic system as described above. 
     A small incision is made on the patient P lying on the operation table T. Next, the semicircular rack gear guide  205  is positioned near the incision, and then, the surgical instrument  600  is allowed to pass through the incision to the surgical site. The operator O grips the handle  804  of the respective master manipulators  800  with his or her fingers fitted into the finger seats  803  to perform a surgery while monitoring the display D. 
     The movement M 4  of the finger seats  803  is translated to the movement S 4  of the fingers  604  through the control system. The motor  601  of the surgical instrument  600  is driven by an operation signal of the finger seats  803  via the control system. The wire repetitively pulls and releases the fingers  604  as the motor  601  rotates clockwise and counterclockwise. Accordingly, an incision, a sewing and a cutting operation can be performed by the fingers  607 . 
     Meanwhile, a difficulty in controlling the surgical instrument  600 , due to a mechanical load while manipulating the master manipulators  800 , is minimized by using motors driven in the same directions as manipulating directions of the operator O. 
     In accordance with the present invention, the surgical robotic system can reduce recovery time of a patient by performing a surgery in a minimal invasive manner. Further, by shifting a pivot point of a surgical instrument on the fat layer or the abdominal wall of the patient P during the surgery, it is possible to reduce repelling forces of the abdominal wall against the surgical instrument. 
     While the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.