Abstract:
Disclosed herein is a surgical operation by wire (SOBW) type surgical operation apparatus including an end effector configured so as to remove or minimize configurations of a mechanical cable. The SOBW type surgical operation apparatus includes: a body part; an extension part having one end connected to the body part; and an end effector formed at the other end of the extension part, and receiving electrical energy transferred through the body part and the extension part and converting the electrical energy into mechanical energy.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2013-0020382, filed on Feb. 26, 2013, and Korean Patent Application No, 10-2013-0134162, filed on Nov. 6, 2013, which are hereby incorporated by reference in its entirety into this application. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to a surgical operation by wire (SOBW) type surgical operation apparatus. More specifically, the present invention relates to an SOBW type surgical operation apparatus including an end effector configured so as to remove or minimize configurations of a mechanical cable. 
         [0004]    2. Description of the Related Art 
         [0005]    A surgical operation apparatus such as a surgical operation robot inserts a small surgical operation tool into a human body in which a surgical operation area is positioned to perform minimally invasive surgery. The surgical operation apparatus includes extension parts connected to a body part thereof, such as a plurality of robot arms, and the like. The extension part may include a passive part and an active part, wherein the passive part is a part that may be manually effected by a preparation step before a surgical operation and the active part is a part effected according to an action of a worker such as a doctor, or the like, at the time of performing the surgical operation. 
         [0006]    The active part is mounted with a surgical operation tool inserted into the abdominal cavity, a joint, or the like, in the human body to perform a surgical operation work such as photographing, resection, or the like. The surgical operation tool is called an end effector in the surgical operation robot and generally may perform motion in five directions such as vertical motion, horizontal motion, forward and reverse motion, rotational motion, and forceps motion. In addition, a mechanical cable extension part such as a robot arm, or the like, may be provided with one or more joint part in order to effectively access the affected part. 
         [0007]    In the surgical operation apparatus according to the related art, the end effector and/or the joint part are driven by a cable extended from the body part to the active part, and the body part or the passive part of the surgical operation apparatus such as the surgical operation robot, or the like, is provided with a driver for driving the cable. Korean Patent Application Publication No. 10-2012-0120837 entitled “Apparatus for Measuring Force of Robot Arm Operating Cable Using Optical Fiber Bragg Grating Sensor and Remote Robot Arm Operating Apparatus Using the Same” has disclosed a configuration using an optical fiber Bragg grating sensor in order to measure force of a cable. However, in the case of driving the end effectors and/or the joint parts of the surgical operation apparatus using the cables, when the number of joint parts is increased or a length of the extension part such as the robot arm, or the like, is increased, the number of cables or lengths of the cables are also increased in proportion to the number of joint parts or the length of the extension part, such that a mechanical connection structure with the surgical operation apparatus provided with the driver for driving the cable may be complicated. This causes a similar problem also in the case in which a degree of freedom of motion of the end effector is increased. In addition, this increases a size of the surgical operation apparatus provided with the driver. 
         [0008]    That is, motion of the cable for driving a distal end joint in the surgical operation apparatus including a plurality of joints may have an influence on motion of other joints, and backlash may be increased as a distance between the driver and the joint part and/or the end effector of the surgical operation apparatus becomes distant. Large tension is applied to the cable in order to decrease the backlash. As a result, a problem that the cable is cut or deformed during a surgical operation may occur. 
       SUMMARY OF THE INVENTION 
       [0009]    An object of the present invention is to prevent a mechanical cable from being extended and cut and prevent a backlash phenomenon by minimizing configurations of the mechanical cable. 
         [0010]    Another object of the present invention is to improve work precision of an end effector. 
         [0011]    In an aspect, the present invention provides a surgical operation by wire (SOBW) type surgical operation apparatus, including: a body part; an extension part having one end connected to the body part; and an end effector formed at the other end of the extension part, and receiving electrical energy transferred through the body part and the extension part and converting the electrical energy into mechanical energy. 
         [0012]    In another aspect, the present invention provides an SOBW type surgical operation apparatus, including: a body part; an extension part having one end connected to the body part; and an end effector formed at the other end of the extension part, receiving electrical energy transferred through the body part and the extension part, and performing a gripping operation, a pitching operation, and a yawing operation using the electrical energy. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0014]      FIG. 1  is a perspective view illustrating a surgical operation by wire (SOBW) type surgical operation apparatus according to a preferred embodiment of the present invention; 
           [0015]      FIG. 2  is an enlarged perspective view of configurations of an extension part and an end effector according to the preferred embodiment of the present invention; 
           [0016]      FIG. 3  is a perspective view illustrating a configuration in which an upper cover part is removed from the configuration of  FIG. 2 ; 
           [0017]      FIG. 4  is a perspective view illustrating the end effector after some configurations of a lower cover part and a pitching operator are removed from the configuration of  FIG. 3 ; 
           [0018]      FIGS. 5 and 6  are views for describing a gripping operation of a forceps part; 
           [0019]      FIG. 7  is a perspective view illustrating an end effector according to another preferred embodiment of the present invention; 
           [0020]      FIGS. 8 and 9  are views for describing a pitching operation of the forceps part; 
           [0021]      FIG. 10  is an enlarged view of configurations of a forceps part in an end effector used in an SOBW type surgical operation apparatus according to another preferred embodiment of the present invention; and 
           [0022]      FIG. 11  is an enlarged view of configurations of a forceps part in an end effector used in an SOBW type surgical operation apparatus according to still another preferred embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification, an overlapped description and a detailed description for well-known functions and configurations that may obscure the gist of the present invention will he omitted. Preferred embodiments of the present invention are provided in order to more completely explain the present invention to those skilled in the art. Therefore, throughout the accompanying drawings, shapes, sizes, and the like, of components may be exaggerated for clarity. 
         [0024]    Hereinafter, configurations and operations of a surgical operation by wire (SOBW) type surgical operation apparatus according to a preferred embodiment of the present invention will he described. 
         [0025]      FIG. 1  is a perspective view illustrating a surgical operation by wire (SOBW) type surgical operation apparatus according to a preferred embodiment of the present invention.  FIG. 2  is an enlarged perspective view of configurations of an extension part and an end effector according to the preferred embodiment of the present invention. 
         [0026]    Referring to  FIG. 1 , the SOBW type surgical operation apparatus  10  according to the preferred embodiment of the present invention is configured to include a body part  100 , an extension part  200 , and an end effector  300 . 
         [0027]    The body part  100  is supported by a around, a wall, a ceiling, or the like. 
         [0028]    One end of the extension part  200  is connected to the body part  100 . Referring  FIGS. 1 and 2 , the extension part  200  may include an upper cover part  200   a  and a lower cover part  200   b.    
         [0029]    The end effector  300  is formed at the other end of the extension part  200  and accesses a surgical operation target site to perform a surgical operation work. The end effector  300  may be inserted and positioned into inner portions of the upper and lower cover parts  200   a  and  200   b  at the other end of the extension part  200 . 
         [0030]    The end effector  300  receives electrical energy transferred through the body part  100  and the extension part  200  and converts the electrical energy into mechanical energy for the surgical operation work. More specifically, the end effector  300  performs a gripping operation, a pitching operation, and a yawing operation using the electrical energy. Here, the extension part  200  includes an electrical wire (hereinafter, referred to as a “wire”) extended from the body part  100  and transfers the electrical energy to the end effector  300  through the wire (not illustrated). That is, a power source is positioned at the body part  100 , and the electrical energy generated by the power source is transferred to the end effector  300  through the body part  100  and the extension part  200 . 
         [0031]    In the preferred embodiment of the present invention, a rolling operation of the end effector  300  is implemented by the body part  100  of  FIG. 1 , that is, a robot arm. The reason for this is to implement a structure for decreasing a size and a weight of an effector. That is, since the extension part  200  is rotated by the robot arm, the size and the weight of the end effector  300  may be decreased as compared with those of a structure in which a separate driving part is provided so as to be adjacent to an actuating part for rotating the end effector  300  disposed at a distal end of the extension part  200 . 
         [0032]    In addition, the rolling operation may also be implemented by additionally disposing a motor in the extension part. 
         [0033]    Hereinafter, a configuration and a gripping operation of the end effector according to the preferred embodiment of the present invention will he described in more detail. 
         [0034]      FIG. 3  is a perspective view illustrating a configuration in which an upper cover part is removed from the configuration of  FIG. 2 .  FIG. 4  is a perspective view illustrating the end effector after some configurations of a lower cover part and a pitching operator are removed from the configuration of  FIG. 3 .  FIGS. 5 and 6  are views for describing a gripping operation of a forceps part. 
         [0035]    Referring to  FIGS. 3 and 4 , the end effector  300  according to the preferred embodiment of the present invention may be configured to include an effector  301 , a gripping operator, and a pitching operator. 
         [0036]    The effector  301  may he formed of forceps including first and second legs  301 , a and  301   b.  The effector  301  may be supported to a support member  319  to be described below through a support pin  302 . In addition, the first and second legs  301   a  and  301   b  may perform a gripping operation based on the support pin  302 . The gripping operation of the first and second legs  301   a  and  302   b  will be described below in a description of  FIGS. 5 and 6 . 
         [0037]    In addition, the effector  301  may be forceps, scissors, a needle driver, a clip applier, a probe grasper, or a retractor. The forceps, or the like, access the surgical operation target site to perform gripping, pitching, rolling, or yawing motion. 
         [0038]    A spur gear is a cylindrical gear in which sterns of gear teeth are oriented parallel to an axis of the gear and is connected to another gear in such a way that two external gears engage with each other. The spur gear is used to transmit power when two axes are parallel to each other so that force generated from the motor may be precisely transmitted to the end effector that is a surgical operation tool. A rack gear refers to a rack on which gear teeth are linearly arranged in a shape wherein the number of teeth of a cylindrical gear that is a spur gear is infinitely increased such that the diameter of the cylinder becomes infinite. The rack gear may be used to convert rotational motion into linear motion or, on the contrary, it may be used to convert linear motion into rotational motion. 
         [0039]    A helical gear is a gear which has teeth, the sterns of which are formed to have twisted curved surfaces, unlike the spur gear, to prevent the entire lengths of the stems of the gear teeth from engaging with each other at the same time. Compared to the spur gears, the helical gears more smoothly engage with each other so that vibration or noise may be reduced when the gears rotate. Further, since the length of a contact line of the helical gear is longer than that of the spur gear, the helical gear may be used to transmit more power. 
         [0040]    Bevel gears engage with each other in such a way that two axes of the gears intersect at 90°. A worm gear is configured such that an axis thereof intersects, at a right angle, an axis of a gear that engages with the worm gear. In a manner similar to the bevel gears, the worm gear is used to transmit power in a perpendicular direction. Since the worm gear may make a comparatively high gear ratio, the size of a structure using the worm gear may be reduced to about half of the size of a structure using bevel gears or helical gears in the same conditions. Furthermore, the worm gear has an advantage of reduced noise or vibration compared to the other kinds of gears. 
         [0041]    The gripping operator receives the electrical energy transferred from the body part and the extension part to induce a gripping operation of the effector  301 . Hereinafter, a gripping operation of the gripping operator will be described under the assumption that the effector  301  is the forceps. However, the effector  301  may be various surgical operation apparatuses such as forceps, scissors, a needle driver, a clip applier, a probe grasper, a retractor, or the like. Therefore, in the present specification, the gripping operation is used as a term encompassing a surgical operation work of the surgical operation apparatuses. 
         [0042]    The gripping operator may be configured to include a gripping motor part  311 , a screw member  312 , a female screw member  313 , a screw guide  314 , a gripping extension part  315 , a sub extension part  316 , a linear motion transfer member  317 , a first connection member  318   a,  a second connection member  318   b , and a support member  319 . 
         [0043]    The gripping motor part  311  converts the electrical energy transferred through the body part  100  and the extension part  200  into rotational motion. 
         [0044]    The screw member  312  is formed at one side of the gripping motor part  311  and is rotated according to rotation of the gripping motor part  311 . In addition, the screw member  312  has a screw thread formed on a surface thereof. 
         [0045]    The female screw member  313  is coupled to an outer portion of the screw member  312  so as to enclose the screw member  312 . In addition, the female screw member  313  may have a screw thread formed on an inner surface thereof contacting the screw member  312  and corresponding to the screw thread of the screw member  312 . Therefore, the female screw member  313  linearly moves along the screw guide  314  according to the rotation of the screw member  312 . 
         [0046]    The gripping extension part  315  has one end coupled to one side of the female screw member  313 . Therefore, the gripping extension part  315  linearly moves together with the female screw member  313  according to the linear motion of the female screw member  313 . All of the female screw member  313 , the screw guide  314 , and the gripping extension part  315  may be called a gripping extension part. 
         [0047]    The sub extension part  316  is extended from the other end of the gripping extension part  315 . In addition, the sub extension part  316  is pivot-coupled to the other end of the gripping extension part  315  through a pivot coupling part  315   a  and is extended from the other end of the gripping extension part  315  toward the effector  301 . 
         [0048]    The linear motion transfer member  317  is formed at an end of the sub extension part  316 . In addition, the linear motion transfer member  317  may convert mechanical kinetic energy transferred through the female screw member  313 , the screw guide  314 , the gripping extension part  315 , and the sub extension part  316  into linear motion for the effector  301 . Here, the linear motion transfer member  317  may have the first connection member  318   a  and the second connection member  318   b  formed at one side and the other side thereof, respectively, wherein the first and second connection members  318   a  and  318   b  may transfer force to one ends of the first and second legs  301   a  and  301   b  in different directions, respectively. 
         [0049]    The support member  319  may he formed to support the effector  301  through a support pin  302 . In addition, the support member  319  may have a groove part  319   a  formed in a portion of an inner side thereof to accommodate motion of the sub extension part  316  inward. 
         [0050]    Referring to  FIGS. 5 and 6  in more detail with respect to the gripping operation of the effector  301 , the female screw member  313  and the gripping extension part  315  linearly move by the rotation of the gripping motor part  311  and the screw member  312 . In addition, the sub extension part  316  allows the liner motion transfer member  317  to linearly move according to the linear motion of the gripping extension pan  315 . Therefore, the first and second connection members  318   a  and  318   b  transfer force to one ends of the first and second legs  301   a  and  301   b  in different directions, respectively. As a result, the effector  301  performs the gripping operation. 
         [0051]    The pitching operator receives the electrical energy transferred from the body part and the extension part to induce a pitching operation of the effector  301 . A configuration and an operation of the pitching operator will be described in detail, together with a third gear  324  and a third gear support bar  325  that are not described, with reference to  FIGS. 7 to 9 . 
         [0052]    Hereinafter, configurations and operations of an end effector used in an SOBW type surgical operation apparatus according to another preferred embodiment of the present invention will be described. 
         [0053]      FIG. 7  is a perspective view illustrating an end effector according to another preferred embodiment of the present invention.  FIGS. 8 and 9  arc views for describing a pitching operation of the forceps part. 
         [0054]    The end effector  400  according to another preferred embodiment of the present invention is different from the end effector  300  illustrated in  FIGS. 3 and 4  in view of a configuration of a gripping operator, but is the same as the end effector  300  illustrated in  FIGS. 3 and 4  in view of a configuration of the pitching operator. Hereinafter, configurations similar to those of the end effectors  300  illustrated in  FIGS. 3 and 4  will be denoted by the same terms and a detailed description thereof will be omitted. 
         [0055]    In the end effector  400  according to another preferred embodiment of the present invention, the gripping operator may be configured to include a gripping motor part  411 , a screw member  412 , a counter screw member  413 , a gripping extension part  414 , and a sub extension part  415 . Here, the counter screw member  413  may be formed to contact only a surface of one side of the screw member  412 . The counter screw member  413  converts rotational motion of the gripping motor part  411  and the screw member  412  into linear motion. 
         [0056]    Additionally, the gripping motor part  411  of the gripping operator may be formed of a linear motor. Since the linear motor directly generates linear driving force unlike a general rotation type motor, the linear motor may be used more effectively than the rotating motor, in a system requiring linear driving force. The reason is that in the case of generating linear driving force by a rotation type motor in a linear driving system, mechanical conversion devices such as a screw, a chain, a gear, and the like, are required, which causes energy loss and generation of noise due to friction. 
         [0057]    In addition, the pitching operator may be configured to include a pitching motor part  321  and a gear part including a first gear  322 , a second gear  323 , and a third gear  324 . 
         [0058]    The pitching motor part  321  converts the electrical energy transferred through the body part and the extension part into rotational motion. 
         [0059]    Referring to  FIGS. 8 and 9  in more detail with respect to the pitching operation of the effector  301 , the first gear  322  of the gear part accommodates rotational motion of the pitching motor part  321 , such that it rotates, in addition, the second gear  323  formed perpendicularly to the first gear  322  and supported to a second gear support bar  323   a  and the third gear  324  formed perpendicularly to the first gear  322  and supported to a third gear support bar  325  engage with each other to transfer rotational motion to the support member  319 . Further, the effector  301  performs pitching motion according to rotation of the support member  319 . 
         [0060]    Further, the gear part may be formed of at least one selected from a group consisting of a spur gear, a helical gear, a worm gear, a rack gear, and a bevel gear. 
         [0061]    Hereinafter, configurations and operations of a forceps part of an end effector used in an SOBW type surgical operation apparatus according to preferred embodiments of the present invention will be described. 
         [0062]      FIG. 10  is an enlarged view of configurations of a forceps part in an end effector used in an SOBW type surgical operation apparatus according to another preferred embodiment of the present invention. 
         [0063]    Referring to  FIG. 10 , a gripping operator of the SOBW type surgical operation apparatus according to another preferred embodiment of the present invention is configured to include a power source transfer part  501 , a piezoelectric material  502 , a linear motion transfer member  503 , a first connection member  504   a,  a second connection member  504   b,  and a support member  505 . 
         [0064]    The power source transfer part  501  transfers the electrical energy transferred through the body part and the extension part to the piezoelectric material  502 . 
         [0065]    The piezoelectric material  502  receives the electrical energy to perform a mechanical contraction or relaxation operation. The piezoelectric material  502  is made of at least one of ceramics with perovskite structures, ceramics with tungsten-bronze structures, and a polyvinylidene fluoride (PVDF) polymer. 
         [0066]    The piezoelectric material refers to a material which induces dielectric polarization when it is mechanically deformed or, inversely, causes mechanical deformation when an electric field is applied thereto. Piezoelectric materials are classified into a natural material and an artificial material. Quartz, berlinite (AlPO4), topaz, tourmaline, etc., are examples of the natural material. The artificial material is formed by synthesizing material which is more inexpensive than natural material. The artificial material has superior piezoelectric characteristics. Artificial piezoelectric ceramics with perovskite or tungsten-bronze structures, an artificial piezoelectric crystal and polyvinylidene fluoride (PVDF) which is a polymer are representative examples of the artificial material. 
         [0067]    The PVDF exhibits piezoelectricity several times greater than quartz. Unlike ceramics where the crystal structure of the material creates the piezoelectric effect, in polymers the long-chain molecules attract and repel each other when an electric field is applied. In the preferred embodiment of the present invention, such PVDF layers are placed on top of one another and used to control the gripping operation of the forceps of the end effector. 
         [0068]    In the preferred embodiment of the present invention, in lieu of the piezoelectric material, a pneumatic linear actuator, a pneumatic tube, a pneumatic cylinder, an electromagnet, etc., may he used. 
         [0069]    The linear motion transfer member  503  is formed at one end of the piezoelectric material  502 . In addition, the linear motion transfer member  503  induces the gripping operation of the effector  301  while linear moving according to the mechanical contraction or relaxation operation of the piezoelectric material  502 . That is, the linear motion transfer member  503  includes the first connection member  504   a  connected to the first leg of the effector  301  and the second connection member  504   b  connected to the second leg of the effector  301 , and the first and second connection members  504   a  and  504   b  transfer force to the first and second legs of the effectors  301  in different directions according to the linear motion of the linear motion transfer member  503 . 
         [0070]    The support member  505  may he configured to support the support pin  302  of the effector  301 . 
         [0071]      FIG. 11  is an enlarged view of configurations of a forceps part in an end effector used in an SOBW type surgical operation apparatus according to still another preferred embodiment of the present invention. 
         [0072]    Referring to  FIG. 11 , the SOBW type surgical operation apparatus according to still another preferred embodiment of the present invention is configured to include a power source transfer part (not illustrated) and a piezoelectric material  602 . In addition, an effector  401  includes a first leg part and a second leg part. Further, the first and second leg parts may perform a grapping operation based on a support pin  402 . 
         [0073]    Here, the first leg part is configured to include a first forceps part  401   a  and a first sub leg part  401   c  extended from the first forceps part  401   a.  The second leg part is configured to include a second forceps part  401   b  and a second sub leg part  401   d  extended from the second forceps part  401   b.    
         [0074]    In addition, the piezoelectric material  602  is coupled to one end of the first sub leg part  401   c  and one end of the second sub leg part  401   d.  Further, the piezoelectric material  602  may perform a mechanical contraction or relaxation operation through received electrical energy to implement the grapping operation of the effector  401 . 
         [0075]    To perform the gripping, pitching, rolling, or yawing motion of the end effector, the present invention introduces a new concept, named surgical operation by wire (SOBW), to the surgical operation apparatus  100  such as a surgical operation robot. For this, the driving part is disposed in the distal end of the extension part  200  to which the surgical operation end effector is connected, such that a mechanical cable may be removed or the number of mechanical cables may be minimized. In other words, in the conventional technique, driving parts such as electrical motors, the number of which corresponds to the number of degrees of freedom of motion of the end effector are disposed in the body part of the surgical operation apparatus, and cables, the number of which corresponds to the number of degrees of freedom of motion of the end effector, connect the driving parts to the end effector. However, the present invention does not require any cable. If as shown in the description of the conventional technique, the distance between the driving part and the end effector is comparatively long, there is a problem of backlash. As the number of degrees of freedom of motion of the end effector is increased, the structure of the apparatus becomes complicated to prevent the cables from being entangled. Given this, in the present invention, the driving part which has been disposed in the body part in the conventional technique is disposed in the distal end of the extension part, thus reducing the distance between the driving part and the end effector. In lieu of cables, a gear is used to transfer driving force from the driving part to the end effector, thereby fundamentally avoiding a problem related to the tension of the cables. This is an application of technology of reducing the size of a power source such as an electrical motor. As a result, the operation of the end effector may be more precisely and accurately controlled. The electrical motor, or the like, is connected to the body part through an electrical wire, whereby a surgical operation is controlled by the electrical wire through which electrical signals are transmitted and received rather than by the cables that have tension. In this sense, a concept that is called surgical operation by wire (SOBW) is introduced. 
         [0076]    In the preferred embodiment of the present invention, the adjustment of the joints of the active part of the extension part  200  that extends from the body part of the surgical operation apparatus  100  and controlling gripping, pitching, rolling or yawing motion of the end effector may be performed in such a way that a doctor manipulates a controller attached or connected to the body part of the surgical operation apparatus  100  rather than using cables. That is, when the doctor manipulates the controller, variation in the controller is converted into an electrical signal, and it is transmitted to the driving unit that is disposed adjacent to the end effector. The driving unit that receives the signal generates driving force and transmits it to the end effector through a gear or the like. In this way, an SOBW type surgical operation apparatus technology can be implemented. 
         [0077]    According to the preferred embodiment of the present invention, it is possible to prevent a mechanical cable from being extended and cut and prevent a backlash phenomenon by minimizing configurations of the mechanical cable. 
         [0078]    In addition, the present invention has a configuration in which the mechanical cable is replaced by the gear, thereby making it possible to improve work precision of the end effector. Further, the prevent invention may reduce diameters of the connection part and the end effector. Therefore, the present invention minimizes an incision entering the abdominal cavity to decrease bleeding of a patient and ultimately minimize a side effect due to a surgical operation, thereby making it possible to maximize an advantage of minimally invasive surgery. 
         [0079]    Furthermore, the present invention allows driving force to directly act on the effector rather than using cable tension and frictional force, thereby making it possible to improve work precision. 
         [0080]    In the SOBW type surgical operation apparatus according to the preferred embodiment of the present invention as described above, the configuration and the method of the above-mentioned preferred embodiments are not restrictively applied. That is, all or some of the respective preferred embodiments may be selectively combined with each other so that they may be variously modified.