Medical kinematic system having a virtual fulcrum, medical robot, and use of a medical kinematic system and a medical robot

Abstract

The invention relates to a medical kinematic system having a virtual fulcrum (RCM) for a medical robot for guiding a surgical instrument arranged on an instrument holder within a working zone, having a main body, a first linear drive, and a second linear drive for movably arranging an instantaneous fulcrum of the instrument holder within the working zone and simultaneously pivoting the instrument holder about the instantaneous fulcrum. The invention also relates to a medical robot having such a kinematic system and to a method for operating a medical kinematic system or a medical robot.

Description

Medical kinematics with virtual pivot point, medical robot, and the use of medical kinematics and a medical robot.

[0001] The invention relates to a medical kinematics system with a virtual pivot point (RCM) for a medical robot for guiding a surgical instrument arranged on an instrument holder in a working zone, comprising a base body, a first linear drive, and a second linear drive for movably positioning an instantaneous pivot point of the instrument holder in the working zone and simultaneously pivoting the instrument holder about the instantaneous pivot point. The invention further relates to a medical robot with such kinematics and a method for operating a medical kinematics system or a medical robot.

[0002] Known medical kinematics, such as those disclosed in DE 10 2018 118 066 A1, utilize various linear actuators to generate a virtual pivot point. Different linkage mechanisms, for example, guided by multiple curved guides, are used to achieve an effect on an instrument holder through the interplay of these mechanisms' movements and the curves. The aim of these arrangements is to rotate a medical instrument around a virtual pivot point. This process often needs to take place in a confined space, while still requiring a clearly defined virtual pivot point, for example, at an entry point on a body. Further robotic kinematics for generating a virtual pivot point are disclosed in US 2015 / 0351857 A1 and DE 102013004459 A1.

[0003] The purpose of the invention is to improve the state of the art.

[0004] The task is solved by a medical kinematics with virtual pivot point (RCM) for a medical robot for guiding a surgical instrument arranged on an instrument holder in a working zone, with a base body, a first linear drive and a second linear drive for moving an instantaneous pivot point of the instrument holder in the working zone and simultaneously pivoting the instrument holder around the instantaneous pivot point.wherein the first linear drive has a fixed point for receiving a first linear drive part of the first linear drive on the base body and a first guide point for guiding a second linear drive part of the first linear drive relative to the base body in a first guide track, and the second linear drive has a second fixed point for receiving a first linear drive part of the second linear drive and a second guide point for guiding the second linear drive part of the second linear drive relative to the base body and / or relative to the second linear drive part of the first linear drive in a second guide track, wherein one of the guide tracks has a guide curve and at least the linear drive guided in the guide track other than the guide track with the guide curve has a variable transmission ratio,so that, by means of a mechanically acting translation arrangement between the first linear drive and the second linear drive, and by means of an interaction of a geometry of the guide curve with at least one variable translation ratio, the instantaneous pivot point can be moved in a circular path around the virtual pivot point, and the instrument mount can be pivoted around the virtual pivot point.

[0005] Such medical kinematics can be achieved due to the spatially closely arranged and mutually opposed elements. The associated linear drives can be built very compactly, whereby, in particular, the movable arrangement of an instantaneous pivot point ensures that the virtual pivot point is held particularly securely and precisely solely through the geometric relationships of the mechanical components, in this context the design of the guide cam in conjunction with the transmission ratio of the transmission arrangement. In this way, a further guide cam for the respective other linear drive can be eliminated and replaced by the variable transmission ratio.

[0006] In this context, the following terms should be explained:

[0007] A "medical kinematic system" describes an assembly of components connected to one another, either movably or partially immovably, which serves, for example, to guide and spatially position a medical instrument. Positioning here can include both translation along linear axes in space and rotation around corresponding axes. Such a medical kinematic system is implemented, for example, as an articulated rod structure or similar, but can also incorporate ball joints, pivot joints, or the like.

[0008] Such medical kinematics features, in particular, a "virtual pivot point," also known as the "RCM," or "remote center of motion." This means, specifically, that such a virtual pivot point is not, or only in certain cases is it, located directly in the region of a mechanical pivot point, such as a joint. Instead, the medical kinematics operates in such a way that a spatial fixed point, namely the virtual pivot point, remains stationary even though the medical kinematics performs arbitrary movements. Such a virtual pivot point is used, in particular, to create a so-called The goal is to create a "trocar point," namely an entry point, for example, into a human body during minimally invasive surgery. This allows, for instance, a trocar—the sheath of a medical instrument—to be guided in such a way that lateral forces on the entry point are avoided or prevented. Nevertheless, movement of a medical instrument within the trocar, or of another medical or surgical instrument, is still possible, for example, through rotational degrees of freedom. Furthermore, inserting or withdrawing an instrument within the trocar through the virtual pivot point is possible without exerting lateral forces on, for example, the patient's skin.

[0009] A "medical robot" is typically a multi-axis robot used for telesurgical procedures, i.e., partially or fully machine-assisted surgical procedures. Such a medical robot can be configured as an articulated robot, a linear-axis robot, or any other type of robot. It should also be noted that the mechanical boundaries between the medical robot as a movable fixed point for medical kinematics and the medical kinematics themselves can be fluid; in particular, both components of a medical system can merge into one another or be part of each other. Conceptually, the medical robot serves primarily as a movable platform for the global movement of a medical instrument, while the medical kinematics often serve for fine adjustment, for example, for precise positioning, also with the aforementioned virtual pivot point.

[0010] In this context, "guiding" occurs in such a way that the surgical or medical instrument can be positioned in a defined manner, for example, by moving it along axes or rotating it around axes. Such guiding can This can be done entirely or partially manually, but can also be electronically and / or technically supported, for example by means of a remote control, a joystick or other control elements.

[0011] An "instrument receptacle" describes the part of the medical kinematics system in which a surgical instrument is mounted, for example, an interchangeable surgical instrument with a corresponding interface. Accordingly, an instrument receptacle is, for example, a mechanical component that is the last component encountered in the medical kinematics system in the direction of the body being treated, before the surgical instrument can be connected distally.

[0012] A "surgical instrument" can be, for example, a laparoscope, an endoscope, or any surgical instrument that is guided in relation to, for example, a patient using medical kinematics. In particular, such a surgical instrument may also include or provide means for preparing and / or following up on a procedure, such as adhesives, stapling devices, sutures, or cutting tools.

[0013] In this context, a "work zone" describes the area in which, for example, an operator works with medical kinematics and surgical instruments. Thus, the work zone is, for instance, an area of ​​a work table or treatment table, a patient lying on it, and a suitably functional environment for preparing and, for example, pre-positioning the medical kinematics and / or surgical instruments. Such a work zone is not strictly defined, but rather emerges from the context, such as the operation to be performed.

[0014] The medical kinematics system has a "basic body" to which other components of the medical kinematics system are arranged. Such a basic body is also provided with a coupling point in the direction of a medical robot, or it can also be, looking from the medical robot towards the direction of the medical kinematics system, the last component of such a medical robot at a distal end of the medical robot, whereby the boundaries here can be fluid.

[0015] A linear actuator, as used in medical kinematics, is a technical device capable of initiating movement along a linear axis. Examples of such linear actuators include linear motors, linear guides, linearly guided spindle drives, and similar devices. The term "linearity" in this context implies that technically reasonable deviations are acceptable, allowing for slight arcs, wave-like shapes, or similar configurations. In this context, mathematically precise linearity of the drive movement is not necessary and may even be explicitly omitted depending on spatial requirements.Each linear drive has a first "linear drive part" and a second "linear drive part", wherein the first linear drive part is, for example, fixed in position and the second linear drive part is, for example, designed to be movable relative to the first linear drive part.

[0016] By means of one of the linear drives, a so-called "instantaneous pivot point" is movably arranged in the working zone, whereby such an instantaneous pivot point is designed analogously to the virtual pivot point, whereby the "instantaneous pivot point" exists within the medical kinematics and is therefore in relation to other components, for example to components of the first Unlike a virtual pivot point, the linear drive's instantaneous pivot point is fixed in relation to the working zone, but rather is movable within it. This instantaneous pivot point can be, for example, a joint, a bearing, or a similar arrangement around which other components can then be pivoted.

[0017] In this context, "swiveling" the instrument mount describes a rotational movement of the instrument mount around its instantaneous pivot point. A translational movement of the instrument mount can also result from a movement of the instantaneous pivot point. The relationship between the instrument mount and the instantaneous pivot point is established such that the instantaneous pivot point serves as the rotation point of the instrument mount. Such swiveling occurs primarily in a plane.

[0018] The linear drive has a "fixed point," which exists relative to the base body or to the respective other linear drive and enables a rotationally fixed or, in particular, a rotatable mounting of a first linear drive component. For example, this first "linear drive component" is a stationary part of the linear drive, which is pivotably or pivotably mounted at the fixed point, and a further linear drive component represents the movable part of the linear drive. If such a linear drive is designed as a spindle drive, the spindle of the linear drive would, for example, be axially fixed, but pivotable or rotatable about the fixed point via a spindle axis, and a corresponding component with a spindle nut would represent the movable linear drive component of the linear drive.

[0019] This involves a "guide point", which corresponds to the further linear drive part, in the example shown the movable The linear actuator component, with its associated spindle nut, is guided along a "guide track." This guide track serves to spatially guide the guide point when the linear actuator component is extended or retracted. If a fixed point is rotatable, allowing the linear actuator to rotate around this fixed point during operation, moving from a retracted to an extended position or in reverse, the linear actuator can perform a guided, for example, oscillating, wave-like movement. The guide track then has a "guide curve" with a non-linear geometry, which, for example, describes a curved or arc-shaped path. In this context, it should be noted that, in particular, the guide track and / or the guide curve are mechanically coupled to the guide point in such a way that positive guidance takes place.

[0020] A "circular path," which results from the line of motion of the instantaneous pivot point around the virtual pivot point, is not to be understood in this context solely as a mathematically exact circular path, i.e., as a circular path in the mathematical sense, but serves as an illustrative example and may exhibit tolerable deviations. In this context, the circular path is defined such that the virtual pivot point is maintained as a fixed point in space within the necessary tolerances. Likewise, another mathematical function can be represented as a circular path, or alternatively, another mathematical function, for example, an elliptical path, a parabolic path, or any other, in particular, closed path or trajectory, each with technically induced deviations from the mathematical ideal.

[0021] A so-called "transmission arrangement" is effective between the first linear drive and the second linear drive. which has a variable "transmission ratio" and couples the first and second linear drives in such a way that mechanical interaction occurs, i.e., simultaneous operation of the second linear drive when, for example, the first linear drive is driven externally. The "variable transmission ratio" describes a property of a single linear drive such that, along, for example, a certain travel distance of the respective linear drive, the linear drive is driven with a variable transmission ratio, i.e., with a uniform drive, the linear motion is carried out according to a non-constant or non-linear function.A transmission arrangement can be implemented, for example, with a positive drive in the form of a toothed belt, gears, or a differently acting gearbox between the linear drives, whereby these or other parts of the transmission arrangement can also implement the variable transmission ratio. For example, a toothed belt can drive a threaded spindle with a fixed transmission ratio, while the threaded spindle itself has a variable pitch to achieve the variable transmission ratio. Alternatively, electronic coupling can be implemented, for example, via appropriate synchronization of stepper motors with a variable transmission ratio stored in a controller, provided this is advantageous in relation to the available installation space or the arrangement of the components.

[0022] In this context, it should be mentioned that the variable transmission ratio is chosen due to the spatial and geometric conditions in such a way that, from the interaction of the geometry of the guide curve with the variable transmission ratio, the instrument mount around the virtual pivot point can be adjusted to each point of a corresponding swivel movement. is pivotable, meaning the virtual pivot point is fixed in space within the desired tolerances.

[0023] In one embodiment, the first guide track associated with the second linear drive section of the first linear drive can have the guide curve, wherein, in particular, the second guide track associated with the second linear drive section of the second linear drive is essentially straight. In another embodiment, the second guide track associated with the second linear drive section of the second linear drive has the guide curve, wherein, in particular, the first guide track associated with the second linear drive section of the first linear drive is essentially straight, and, in particular, the instrument holder is movably mounted on the second linear drive section relative to the second linear drive section of the first linear drive in essentially one direction through the virtual pivot point.

[0024] Thus, in different design forms and depending, for example, on the available installation space, either the first linear drive or the second linear drive can be equipped with the guide cam, with the other linear drive being guided in a straight line.

[0025] In order to achieve a smooth transition of movements and to make the medical kinematics as simple as possible, the geometry of the guide curve is arc-shaped, parabolic and / or elliptical, wherein a respective center of curvature of the geometry and / or a respective center of curvature of the respective section of the geometry, i.e. the arc-shaped section, the parabolic section and / or the elliptical section, is arranged from the geometry in the direction of the virtual pivot point.

[0026] In this context, it has become apparent that such an arrangement can be implemented in a particularly compact way, which means that, for example, the naturally very limited space in the workroom, which is located near a patient during an operation, can be used very efficiently.

[0027] The terms "arc-shaped," "parabolic," and / or "elliptical" describe a design corresponding to the respective mathematical term, while explicitly including any technically necessary tolerances. In this context, the guide curve can also be composed of different arc-shaped, parabolic, and / or elliptical components, resulting in a continuous and distinct guide curve for smooth and jerk-free guidance of the surgical instrument.

[0028] A “center of curvature” describes the currently existing center of the circular path of a correspondingly curved section of the guide curve at each point of the curve.

[0029] In one embodiment, the guide curve has at least one cam guide, with the guide point having a pin guided in the at least one cam guide. Alternatively, instead of a pin engaging in a cam guide, a guide clamp engaging via a cam rail can also be used, for example, if this is advantageous for reasons of simpler manufacturing.

[0030] The advantage of such a cam track with a corresponding pin or an analogous design is the forced guidance of the components along the guide curve, so that in a compact mechanical arrangement a deviation of the movement of the medical kinematics from a movement around the virtual pivot point is almost impossible.

[0031] In this context, a "scenery guide" describes a gear element which usually has a slot, a web or a groove and guides a pin in or on the slide, which is also called a slide block, or an alternative guide means, and thus imprints a movement path predetermined along the longitudinal extent of the slide.

[0032] For example, such a cam guide is designed as a slot formed along the longitudinal direction of a flat component, whereby a corresponding "pin" can be, for example, a round pin, which is then ideally guided without play within the cam guide.

[0033] In order to make the medical kinematics particularly compact, the second linear drive is arranged essentially parallel to the first linear drive and / or a first linear drive part of the second linear drive is assigned to the second linear drive part of the first linear drive, wherein in particular the second linear drive part of the second linear drive is driven via the transmission arrangement with the variable transmission ratio.

[0034] "Essentially parallel" describes a fundamentally parallel action, whereby technically induced deviations of, for example, ± 10° or ± 15° are also covered. Angle specifications in this context refer to a full 360-degree angle.

[0035] In one embodiment, a lever is assigned to the second linear drive part of one of the linear drives, wherein the lever is rotatably mechanically connected to the instrument mount when the instrument mount is pivoted about the instantaneous pivot point by means of the respective linear drive.

[0036] Such a lever can be designed, for example, with a first lever pivot point and a second lever pivot point acting in the sense of a connecting rod, in such a way that the corresponding arrangement is part of the transmission ratio and thus enables a particularly compact design of the medical kinematics.

[0037] In this context, a “lever” can be, for example, a bridge with a first pivot point and a second pivot point, which functions analogously to a push rod or a connecting rod with a receptacle movable on both sides.

[0038] In order to enable corresponding assemblies, for example for the production of different medical kinematics with different effective parameters, the variable transmission ratio is realized by means of a drive ratio of the first linear drive and / or the second linear drive that can be changed over a movement length of the second linear drive.

[0039] For example, the second linear drive can be designed with a drive ratio that varies over its travel length, so that a corresponding combination of linear drives with standard components allows for different arrangements of a virtual pivot point relative to the basic body of the medical kinematics. This greatly simplifies the production of different medical kinematics, for example, for different motion requirements.

[0040] In one embodiment, one of the linear drive components of the respective linear drive has a spindle with pitch flanks arranged radially along the length of travel and a pitch of the pitch flanks that varies over the length of travel, wherein the other linear drive component of the respective linear drive has a spindle mounted on the spindle. is associated with a guided spindle nut with engagement elements that engage in the pitch flanks.

[0041] A "spindle," for example, is a rod-shaped arrangement with a thread-like design, featuring "pitch flanks" incorporated into the spindle, analogous to threads. Corresponding "engagement elements," such as sliding pieces designed to correspond to the cross-sectional geometry of the pitch flanks, engage with these "pitch flanks."

[0042] In order to use such a spindle with a corresponding spindle nut with as little backlash as possible, as is particularly important in medical kinematics, the spindle nut has elastic compensating means acting between the engagement elements to compensate for differences in distance occurring along the length of movement, due to the variable pitch and / or tolerances between and / or on the respective pitch flanks.

[0043] Such an "elastic compensating element" can be, for example, a spring or spring element, whereby different engagement elements are tensioned against each other by means of the elastic compensating element in a respective direction of action of the spindle and can thus compensate for differences in distance and / or tolerances. Mechanical springs as well as hydraulic spring devices or co-acting means can be used here.

[0044] In one embodiment, a third linear drive with a movement axis passing through the virtual pivot point is assigned to the instrument holder for linear movement of the surgical instrument through the virtual pivot point.

[0045] Such a third linear drive can, for example, achieve a penetration depth of the surgical instrument into the body being treated in such a way that the virtual pivot point remains unchanged, which is why the third linear drive has a movement axis that essentially runs through the virtual pivot point. It should also be noted in this context that corresponding technical deviations are expressly included.

[0046] Likewise, a rotary mount with a rotary axis for connecting the medical kinematics to a medical robot can be assigned to the base body, wherein the rotary axis is arranged skew to a motion axis of the first linear drive.

[0047] By means of such a rotary mount with a corresponding axis of rotation, the essentially two-dimensional mode of action of the medical kinematics, as previously designed, can be extended to a third dimension, whereby the arrangement of the axis of rotation is such that it passes through the virtual pivot point. This allows the movement of the medical kinematics to occur in all six degrees of freedom, namely three translational and three rotational degrees of freedom.

[0048] In another aspect, the task is solved by a medical robot with medical kinematics according to one of the previously described implementation forms. Such a medical robot utilizes all the advantages of medical kinematics and can also position and guide the medical kinematics globally within or even outside the workspace, thus providing an overall easy-to-use, compact medical system.

[0049] In another aspect, the task is solved by a method for operating a medical kinematics according to one of the previously described implementation forms and / or a medical robot with a virtual pivot point, with the following steps: - Arranging the medical kinematics in the working zone, so that the medical kinematics are arranged in the working zone, - Guiding the medical kinematics and / or the medical robot around the virtual pivot point (RCM) by means of an interaction of the geometry of the guide curve with the variable transmission ratio, so that the instrument holder is pivoted around the virtual pivot point, so that the medical kinematics is operated with a virtual pivot point.

[0050] The invention will now be explained using exemplary embodiments. These will show... Figure 1 shows a schematic representation of the kinematics for a medical robot in a side view. Figure 2 is a schematic overview of a medical robot with a kinematics of Figure 1. Figures 3a to 3c show the kinematics of Figure 1 in different positions, as well as Figure 4 shows a schematic detail of a Spindle drive of the kinematics of Figure 1 .

[0051] A kinematic mechanism 101 for medical purposes is a so-called "RCM" mechanism, which can be used to guide a medical instrument. The kinematic mechanism 101 has a base body 103. The base body 103 serves to hold the other components of the kinematic mechanism 101 and thus also acts as a mechanical base. Reference system for the movement of further components. The base body 103 can be connected to a medical robot by means of a rotary joint 141, whereby a rotation about a rotation axis 183 of the rotary joint 141 in relation to the medical robot is enabled.

[0052] A guide 105 is arranged on the base body 103, wherein a static part 109 of the guide is rotatably connected to the base body 103 by means of a fixed point 143, but is fixed in position. A movable part 111 of the guide 105, which is arranged to be longitudinally displaceable relative to the static part 109, can slide back and forth on the static part 109 with respect to the fixed point 143. A guide point 145, which is designed as a pin, is arranged on the movable part 111. This guide point 145 slides in a cam 147, the cam 147 being arranged on the base body 103. The backdrop 147 is arc-shaped, whereby a longitudinal displacement of the movable part 111 relative to the static part 109 of the guide 105 initiates a corresponding oscillating movement of the guide 105.

[0053] A linear drive 108 serves to drive the guide 105, wherein a spindle 110 is axially fixed relative to the fixed point 143 and a movable part 112 is mechanically axially fixed to the movable part 111 of the guide 105. Thus, the movable part 111 of the guide 105 can be moved axially by means of the linear drive 108, thereby initiating the oscillating movement described above. The guide 105 serves only to absorb mechanical forces and is thus a component of the linear drive 108 in terms of its functional purpose, namely the drive in the linear direction.

[0054] A linear drive is also assigned to guide 105. 107, wherein a spindle 113 of the linear drive 107 is rotatable via a bearing point 117, but axially fixed relative to the A fixed point 143 is arranged. A movable part 116, which is driven by means of the spindle 113, is axially displaceable, parallel to the guide 105 and linear drive 108, analogous to the processes described above. For this purpose, the movable part 116 is longitudinally displaceable in a support tube 115, in particular to prevent tilting relative to the spindle 113 and to guide the movable part 116.

[0055] The linear drive 107 has a variable transmission ratio, which will be explained in detail in later sections.

[0056] A mechanical coupling in the form of a toothed belt drive (not shown) exists between the linear drive 108 and the linear drive 107, such that a rotary movement of the linear drive 108 is synchronized with a rotary movement of the linear drive 107. Overall, this mechanical coupling, together with the variable transmission ratio of the linear drive 107 over its travel length, results in a variable transmission ratio between the linear drive 108 and the linear drive 107.

[0057] The guide 105 serves to move an instantaneous pivot point 185 in space. An instrument holder 121 is pivotably arranged around the instantaneous pivot point 185. The instrument holder 121 has a guide rail 123 on which a linear drive 125 is arranged. By means of the linear drive 125, a shaft 127, as part of a surgical instrument, is longitudinally displaceable along the guide rail 123. The shaft 127 also has a supply line 131, which is representative of instruments, lighting devices, and the like guided in the trocar 127. The shaft 127 further has an instrument tip 129.

[0058] The linear drive 107, in particular the movable part 116 of the linear drive 107, is provided with a lever 119. The movable part 116 is guided in the support tube 115 and connected to the instrument holder 121 by means of the lever 119 such that the instrument holder 121 is driven by the linear drive 107 via the lever 119. The linear movement of the linear drive 107 acts on the instrument holder 121 via the lever 119 and the additional transmission resulting from the arrangement of the lever. Thus, the linear drive 107 and the lever 119 together form a pivoting drive for the instrument holder 121. The instrument holder 121 can therefore be pivoted about the instantaneous pivot point 185 by means of the linear drive 107 and the coupling effect of the lever 119.

[0059] The geometric relationships are explained in detail below:

[0060] For surgical procedures, for example, it is advantageous for a surgical instrument to rotate around a virtual pivot point, i.e., to perform no lateral movement at, for example, an entry point into a body. In this context, the shaft 127 has a so-called trocar point, namely the virtual pivot point 181, at which the shaft 127 is inserted, for example, into a trocar. The cam 147, which acts on the pin 145, is designed in conjunction with the transmission of the linear drive 108 to the linear drive 107 and the variable transmission ratio over the travel length of the linear drive 107, in conjunction with the lever 119, such that the instantaneous pivot point 185, when the linear drive 108 is actuated, describes a circular path around the virtual pivot point 181, namely the circular path 187.Likewise, the angle of the axis of rotation 183 to the corresponding axes of movement of the linear drives is set skew, such that the axis of rotation 183 passes through the virtual pivot point 181. Thus, movement of the instrument using the kinematics 101 and rotation of the kinematics 101 about the axis of rotation are possible. 183, for example on a medical robot, in such a way that the virtual pivot point 181 remains fixed in space, i.e. also fixed in relation to an entry point on a patient.

[0061] As an example, a medical robot 201 with a foot 203 and an arm 205 is described, wherein the kinematics 101 is connected to a distal end of the arm 205. The virtual pivot point 181 is fixed to a boundary of an exemplary body 250, which lies on a table 252, for example, an operating table.

[0062] The effect of the kinematics 101 is shown in detail again (see also Figures 3a to 3c):

[0063] Regardless of the respective positions of the linear actuators 108 and 107 relative to the base body 103 of the kinematics 101, a movement of the instantaneous pivot point 185 on the circular path 187 around the virtual pivot point 181 can be observed in different positions 301, 303, and 305 (see Figures 3a, 3b, 3c). The linear actuator 107 follows the pivoting movement of the instrument mount 121 in such a way that no technically detrimental deviations from this movement occur. Rotation of the kinematics 101 about the axis of rotation 183 also has no negative effect.

[0064] A spindle drive 401, as used in the linear drive 107, is explained in detail here:

[0065] The spindle drive 401 has the spindle 113 with spiral, thread-like flanks 114, the corresponding flanks being part of a U-shaped profile.

[0066] Corresponding to the profile of these flanks 114, a pin 405 is guided radially to the spindle 113 within a spindle nut 403 and engages with a head area 406 in a flank. 114. This establishes a fixed reference in the longitudinal direction along a longitudinal axis 481 by the pin 405. The pin 405 serves as a pin fixed relative to the spindle nut 403. Further pins 407, which are rotationally fixed but longitudinally displaceable in elongated holes in the spindle nut 403 and are also arranged radially to the spindle 113 and positioned engaging the flanks 114, are held free of play relative to the pin 405 by means of springs 409, so that the pins 405 and 407 are clamped within the flanks 114 by means of the springs 409, thus enabling the spindle nut 403 to be guided on the spindle 113 without play.

[0067] The variable pitch of the flanks 114 along a longitudinal axis 481 of the spindle 113 (see Fig. 4) is part of the variable transmission ratio of the linear drive 107 relative to the linear drive 108. The pins 405, together with the pins 407 and the springs 409, serve not only to compensate for play but also to compensate for the changing distances between the flanks 114 resulting from the variable pitch.

[0068] In the above example of the kinematics 101, the spindle nut 403 is mechanically connected to the moving part 116 of the second linear drive 107 and ensures the controlled movement of the moving part 116 in relation to the spindle 113, whereby the moving part 116 is guided in the support tube 115 to decouple the force absorption, so that the spindle 113 together with the spindle nut 403 only has to absorb axial forces. Reference character list 101 Kinematics 103 Basic body 105 Leadership 107 Linear drive 108 Linear actuator 109 static part 110 spindle 111 moving part 112 moving part 113 Spindle 114 Flank 115 Support tube 116 moving part 117 bearing point 119 levers 121 instrument holders 123 Running rail 125 Linear drive 127 shaft 129 Instrument tip 131 Supply line 141 Swivel joint 143 Fixed point 145 lead point 147 Scenery 181 virtual pivot 183 Axis of rotation 185 Instantaneous pivot point 187 Circular railway 201 Medical robot 203 feet arm Body Table position position position Spindle drive Spindle nut Cones Cones Feather Longitudinal axis

Claims

Patent claims:

1. Medical Kinematics (101) with virtual pivot point (RCM) (181) for a medical robot (201) for guiding a surgical instrument (127) arranged on an instrument holder (121) in a working zone, comprising a base body (103), a first linear drive (108) and a second linear drive (107) for movably arranging an instantaneous pivot point (185) of the instrument holder (121) in the working zone and simultaneously pivoting the instrument holder (121) about the instantaneous pivot point (185), wherein the first linear drive (108) has a first fixed point (143) for receiving a first linear drive part (109, 110) of the first linear drive (108) on the base body (103) and a first guide point (145) for guiding a second linear drive part (111,112) of the first linear drive (108) relative to the base body (103) in a first guide track (147) and the second linear drive (107) has a second fixed point (117) for receiving a first linear drive part (115) of the second linear drive (107) and a second guide point for guiding the second linear drive part (116) of the second linear drive (107) relative to the base body (103) and / or relative to the second linear drive part (110, 111) of the first linear drive (108) in a second guide track (115, 116), wherein one of the guide tracks (115, 116, 147) has a guide curve (147) and at least the linear drive (107, 108) guided in the guide track (115, 116) other than the guide track (147) with the guide curve (147) has a variable has a translation ratio (114) such that by means of a connection between the first linear drive (105,108) and the second linear drive (107) mechanically acting translation arrangement and by means of an interaction of a, Geometry of the guide curve (147) with at least one With a variable transmission ratio (114), the instantaneous pivot point (185) is movable in a circular path (187) around the virtual pivot point (181), and the instrument holder (121) is pivotable around the virtual pivot point (181). Medical kinematics according to claim 1, characterized in that the first guide track (147) associated with the second linear drive part (110, 111) of the first linear drive (108) has the guide curve (147), wherein, in particular, the second guide track (115, 116) associated with the second linear drive part (116) of the second linear drive (107) is essentially straight.Medical kinematics according to claim 1, characterized in that the second guide track (115) associated with the second linear drive part (116) of the second linear drive (107) has the guide curve, wherein, in particular, the first guide track associated with the second linear drive part (110, 111) of the first linear drive (108) is essentially straight. Medical kinematics according to claim 3, characterized in that the instrument holder (121) is movably mounted on the second linear drive part (110, 111) of the first linear drive (108) relative to the second linear drive part (110, 111) of the first linear drive (108) in essentially one direction through the virtual pivot point (181).Medical kinematics according to one of the preceding claims, characterized in that the geometry of the guide curve (147) is arc-shaped, parabolic and / or elliptical, wherein a center of curvature of the geometry and / or a respective section of the geometry is arranged from the geometry in the direction of the virtual pivot point (181). Medical kinematics according to one of the preceding claims, characterized in that the guide cam (147) has at least one cam guide (147), wherein the guide point (145) has a pin (145) guided in the at least one cam guide (147). Medical kinematics according to one of the preceding claims, characterized in that the second linear drive (107) is arranged to act substantially parallel to the first linear drive (108) and / or a first linear drive part (113) of the second linear drive (107) is associated with the second linear drive part (111, 112) of the first linear drive (108), wherein in particular the second linear drive part (115) of the second linear drive (107) is driven via the transmission arrangement by means of the first linear drive (108).Medical kinematics according to claim 7, characterized in that a lever (119) is associated with the second linear drive part (115) of one of the linear drives (107, 108), wherein the lever (119) is rotatably mechanically connected to the instrument holder (121) for indirectly pivoting the instrument holder (121) about the instantaneous pivot point (185) by means of the respective linear drive (107, 108). Medical kinematics according to any one of the preceding claims, characterized in that the at least one variable transmission ratio is realized by means of a drive ratio (114) of the first linear drive and / or the second linear drive (107) that can be varied over a travel length. Medical kinematics according to claim 9, characterized in that one of the linear drive parts (113, 115) of the first linear drive and / or the second linear drive (107) has a spindle (113) spirally wound along its length. The linear drive (107) has slope flanks (114) arranged along the length of the movement and a slope of the slope flanks (114) that is variable over the length of the movement, wherein the other linear drive part (113, 115) of the respective linear drive (107) is associated with a spindle nut (403) guided on the spindle with engagement elements (405, 407) engaging the slope flanks. Medical kinematics according to claim 10, characterized in that the spindle nut (403) has elastic compensating means (409) acting between the engagement elements (405, 407) for compensating for differences in distance and / or tolerances occurring along the length of the movement between and / or on the respective slope flanks (114).Medical kinematics according to one of the preceding claims, characterized in that a third linear drive (123, 125) with a movement axis extending through the virtual pivot point (181) for linearly moving the surgical instrument (127) through the virtual pivot point (181) is associated with the instrument holder (121). Medical kinematics according to one of the preceding claims, characterized in that a rotary mount (141) with a rotation axis (183) for rotatably connecting the medical kinematics (101) to a medical robot (201) is associated with the base body (103), wherein the rotation axis (183) is arranged skew to the movement axis of the first linear drive (108). Medical robot (201) with medical kinematics (101) according to one of claims 1 to 13. Method for operating a medical kinematics (101) according to any one of claims 1 to 13 or a medical robot (201) according to claim 14 with a virtual pivot point (181) comprising the following steps: - Arranging the medical kinematics (101) in the work zone such that the medical kinematics (101) is arranged in the work zone, - Guiding the medical kinematics and / or the medical robot around the virtual pivot point (RCM) (181) by means of an interaction of the geometry of the guide curve (147) with the at least one variable translation ratio (114) , such that the instrument holder (121) is pivoted about the virtual pivot point (181) so that the medical kinematics (101) is operated with a virtual pivot point (181).

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