Medical robot-assisted visualization system and control method for visualization system

Abstract

The present disclosure relates to a medical robot-assisted visualization system (1) for visualizing, in particular during a surgical operation on a patient (P), having a robot (2), the robot has a robot base (4), a movable medical vehicle preferably as a mobile robot base (4), and a movable robot arm (6) connected to the robot base (4); the invention relates to a robot (2) comprising a movable robot arm (6), a visualization unit (8) as an end effector of the robot (2), which visualization unit is mounted or mounted on the movable robot arm (6) and can be spatially positioned, in particular arranged in position and orientation, by means of the movement of the robot arm (6), and a control unit (10), the control unit is adapted to control at least one position and / or orientation of the visualization unit (8). The robot (2) is a seven-axis robot and / or the robot arm (6) has seven axes and is rotatable, in particular about seven axes of rotation, by means of which the robot arm (6) can be moved into different robot arm postures with a constant position and / or orientation of the visualization unit (8). The disclosure also relates to a control method for a medical robot-assisted visualization system (1) according to the parallel claims, a computer-readable storage medium and a computer program.

Description

Technical Field

[0001] This disclosure relates to a medical robot-assisted visualization system for visualization, particularly during surgical procedures on patients. The visualization system comprises a robot having a robot base, a mobile medical vehicle (preferably serving as a mobile robot base), and a movable robotic arm connected to the robot base. Furthermore, the visualization system has visualization units (for optical visualization, digital or optical analog) as end effectors of the robot (to be controlled). These visualization units are (movably) supported or fixed / mounted on the movable robotic arm and can be spatially (e.g., relative to the patient) positioned, particularly in a position and orientation (i.e., orientation), by the movement of the robotic arm (through the configuration of the robotic arm segments). The visualization system also has a control unit adapted to control at least one position and / or orientation of the visualization units. Additionally, this disclosure relates to a control method, a computer-readable storage medium, and a computer program for a medical robot-assisted visualization system according to the preamble of the parallel claims. Background Technology

[0002] To assist surgeons in performing operations, visualization systems are used, such as optical surgical microscopes mounted on cantilever arms, or more advantageously, robot-assisted visualization systems, such as robot-assisted surgical microscopes. These, especially in minimally invasive surgery, improve the surgeon's observation of the areas to be treated on the patient's body. Here, the visualization unit, which serves as an end effector, is moved by a robotic arm. For example, the robotic arm can be movably mounted on a robotic base, which is a movable medical cart, to which the movable robotic arm is hinged. The visualization unit can be positioned or arranged in space by the robotic arm. The robotic arm can be controlled by the user via buttons, joysticks, or by manually moving the end effector to the desired position.

[0003] While various medical robot-assisted visualization systems exist on the market, what these known visualization systems have in common is that they all feature a robotic arm with six (6) hinges; that is, known medical robot-assisted visualization systems have a 6-axis robotic arm. Such 6-axis robots are known from numerous applications and are characterized by their simplicity and robustness. These conventional 6-axis robots are kinematically determined, meaning that the position of the end effector and the pose of the robotic arm are coupled. Therefore, the robotic arm cannot be moved without changing the position of the end effector.

[0004] This has several drawbacks. An unsuitable robotic arm posture, such as the robotic arm itself or its segments or links, can obstruct the surgeon's view of the operating screen. Furthermore, the robotic arm may collide with people or objects in the vicinity when the end effector moves to a different position or orientation. In the worst case, no movement may occur at all, as objects in the operating room can be arranged such that the robotic arm cannot move out of view without a collision. An unfavorable combination of robotic arm posture and end effector position can also force the surgeon or user into an ergonomic posture, which can be particularly burdensome for the user during prolonged surgeries.

[0005] The pre-set or intended positions of the end effector thus result in a very limited number of robotic arm configurations. Typically, even only one robotic arm pose is usable during surgery. The end effector moves continuously during surgery to achieve various viewing orientations. With each movement, the robotic arm is forced to assume a new pose or configuration. In a 6-axis robot, the robotic arm pose is determined for each position of the end effector, or in other words, only one configuration of the robotic arm segment is possible.

[0006] When the visualization unit is a (analog) microscope with an eyepiece system, the surgeon sees the microscope's optics directly. Therefore, the surgeon's field of view is not obstructed by the microscope. However, new-generation surgical microscopes utilize digital optics to provide visualization and better imaging for all professionals in the operating room, and typically use 3D screens as output units to display the microscope's detected images to the surgeon.

[0007] In this known solution, the surgeon can view images captured by the visualization unit on a screen. However, due to limited kinematic configuration possibilities, such visualization systems can cause the robotic arm to obstruct the surgeon's view when the cart is positioned in front of the surgeon. That is, the robotic arm is positioned between the surgeon and the 3D screen. In this situation, the robotic arm may obstruct the surgeon's view, and unfavorable robotic arm postures for specific positions of the end effectors cannot be changed for kinematic reasons, as the robotic arm posture and the end effector position are forcibly coupled to each other. This results in significant ergonomic disadvantages for the surgeon. If the cart is alternatively positioned behind the surgeon and the robotic arm passes over the surgeon's shoulder, the limitations on specific robotic arm postures for specific positions of the end effectors may again lead to collisions between the robotic arm and the surgeon and / or force the surgeon into an ergonomically unfriendly position. While conventional optical microscopes, which extend downwards from the ceiling, generally do not obstruct the surgeon's field of view, the limited number of robotic arm postures can still cause ergonomic problems or cause components of the system to collide with other systems in the operating room. Summary of the Invention

[0008] Therefore, the object of this disclosure is to overcome or at least reduce the disadvantages of the prior art and, in particular, to provide a visualization system, a control method, a computer-readable storage medium, and a computer program that can flexibly adapt the visualization unit in an optimal configuration of a robotic arm. A sub-task may be ensuring that the robotic arm does not obstruct the surgeon's view of the output unit. Another sub-task is to provide a stable configuration of the robotic arm, such that the visualization unit is arranged very stably and performs the smallest possible elastic movement. A further object is to provide the user with a visualization system that can be well moved and controlled according to their requirements, such as during input, and which preferably avoids collisions.

[0009] The objectives of this disclosure are as follows: a visualization system assisted by a medical robot is addressed by the features of claim 1; a medical control method is addressed by the features of claim 14; a computer-readable storage medium is addressed by the features of claim 16; and a computer program is addressed by the features of claim 17.

[0010] This disclosure relates to a medical robot-assisted visualization system for visualization, particularly during surgical procedures. The medical robot-assisted visualization system comprises a robot having a robot base, a medical mobile vehicle preferably serving as a mobile robot base, and a movable robotic arm connected to the robot base. The visualization system also includes a visualization unit and a control unit, the visualization unit acting as a (controllable and movable) end effector of the robot, the visualization unit being supported or mounted on the movable robotic arm and spatially positioned (e.g., via three coordinates x, y, z) particularly with respect to position and orientation (i.e., orientation) by the movement of the robotic arm, the control unit being adapted to at least control the position and / or orientation of the visualization unit. According to this disclosure, the robot is a seven-axis robot (7-axis robot) and / or the robotic arm has (at least) seven hinges or (different hinge) axes, through which the robotic arm can be moved / configured into different robotic arm postures while the position and / or orientation of the visualization unit remains unchanged / constant. In particular, the robot arm has seven rotation axes, exactly seven rotation axes, around which each robot arm segment can rotate.

[0011] In other words, the robotic arm has seven hinges, each with one degree of freedom, giving the robotic arm a total of seven degrees of freedom. The robotic arm is therefore a 7-axis robot with a medical visualization unit serving as an end effector. The control unit moves the robotic arm into multiple different robotic arm poses while the position and / or orientation of the visualization unit remains unchanged, which is possible due to the seven hinges or axes. Therefore, the core of this disclosure can be summarized as follows: the position and / or orientation of the visualization unit is decoupled as much as possible from the robotic arm pose via at least seven axes of the robot. Thus, a seven-axis robot with a visualization unit serving as an end effector is proposed in particular as a visualization system.

[0012] This allows the robotic arm to move or change its posture without forcibly moving the end effector or visualization unit, or changing the position and / or orientation of the visualization unit. Therefore, the robotic arm can perform so-called zero-space movements. This allows the arm segments or sections of the robotic arm to move from unfavorable postures to more favorable ones without requiring movement of the visualization unit. For example, it can prevent robotic arm segments from being positioned within the user's line of sight. Furthermore, it can prevent collisions between the robotic arm and the user. The user is no longer forced into an ergonomically unfriendly position or posture by the positioning of the visualization unit and / or the robotic arm.

[0013] Therefore, the visualization system according to this disclosure combines the advantages of a visualization unit (where the user directly observes the object and thus has an unobstructed view) with the advantages of a screen-based solution in which the user is not forced into an uncomfortable posture.

[0014] Specifically, the visualization system can be implemented, in particular, as a robotic microscope with a mobile vehicle having a robotic arm with seven or more hinges and a visualization unit, such as a microscope, connected, and in particular, fixed as an end effector. An output unit, such as a screen, for displaying images detected by the visualization unit can be fixed to the same vehicle or to a separate bracket. The control unit can be adapted, in particular, to determine the surgeon's / user's positioning and the screen's positioning relative to the end effector using a microscope-specific algorithm or model. This model or algorithm can be used by the control unit to optimize the robotic arm configuration for a (pre-)determined or predefined end effector position. For example, obstruction of the surgeon's field of vision can be avoided by rotating the "elbow" of the robotic arm, i.e., the angled hinge, downward (i.e., toward the ground) from the surgeon's line of sight. The intermediate hinge of the robotic arm, which can be particularly referred to as the "elbow," allows two adjacent tubular robotic arm segments to bend relative to each other and thus protrude away from the basic extension of the robotic arm in a particular robotic arm posture.

[0015] The objective of this disclosure is further addressed by a control method for a robot-assisted visualization system, particularly according to this disclosure. This control method comprises the following steps: A visualization unit moves or moves to a preset target position and / or target orientation via a robot arm. Optical sensors, particularly cameras, detect the spatial position of the user's head, particularly the position of the user's eyes. Furthermore, a control unit determines the position of an output unit, particularly a screen. The control unit calculates a line of sight / visual axis or straight line between the determined position of the output unit and the detected head position of the user. Preferably, a tolerance range can be drawn around the calculated line of sight, particularly in the form of a tunnel or tube with a predefined diameter. Here, the calculated line of sight corresponds to the user's observation on the output unit. Additionally, the control unit detects the robot arm posture. That is, the control unit detects the orientation and / or orientation of the individual arm segments / robot arm sections of the robot arm. The control unit identifies or determines possible obstructions to the calculated line of sight, for example, through the robot arm segments. Here, the control unit can particularly detect the robot arm entering the tolerance range. If an obstruction to the line of sight is identified by the control unit, the control unit moves the robot arm, wherein the target position and / or target orientation of the visualization unit remains constant.

[0016] Sensors or sensing devices may, in particular, incorporate optical sensor systems (e.g., cameras) and / or radar and / or ultrasonic and / or lidar R to detect spatial position and / or orientation. Sensors or sensing devices may be implemented, for example, as optical cameras (e.g., with CMOS sensors) or within optical cameras. However, sensors or sensing devices can also be implemented as radar, lidar, and / or ultrasonic sensors, which are particularly suitable for detecting spatial structures and distances. In principle, different sensors can be considered that can be used to detect the position of a user's head in space.

[0017] Therefore, if the control unit determines that the user does not have free observation of the output unit because the robot arm is in the line of sight, the control unit moves the robot arm into another robot arm pose, so that only the robot arm moves, while the visualization unit, as an end effector, remains in its position and / or orientation.

[0018] The robotic arm can be moved by the user via input signals through a joystick, buttons, and / or "manual" (force-sensitive) controls, where the user pushes or pulls the robotic arm to the desired position. Especially when a microscope serving as an end effector is moved via the robotic arm (with joystick and / or force or button controls), the robotic arm can also optimize its position to minimize obstruction of the surgeon's observation.

[0019] The proposed control method allows the control unit to detect whether the user's view is obstructed by the robotic arm. If the control unit determines an obstruction exists, it can keep the robotic arm moving for an extended period until the obstruction is removed. The result is unobstructed observation of the output unit by the user, without requiring the user to be in an uncomfortable or ergonomic posture.

[0020] Preferably, the control unit can detect the robot arm posture during the movement of the visualization unit and thus determine whether the robot arm is obstructing the calculated user's line of sight during the movement of the visualization unit, and accordingly configure the robot arm segments in such a targeted manner during movement that the robot arm does not impair observation at the target position and / or target orientation of the visualization unit.

[0021] Advantageous improvements disclosed herein are the subject of the dependent claims and are explained in particular below.

[0022] According to optional features of this disclosure, the respective adjacent or sequentially adjacent rotation axes of the robot arm are arranged perpendicularly or orthogonally to each other. Here, adjacent rotation axes can be rotation axes arranged sequentially in a force flow or torque flow that begins or ends at the robot base. Through their respective perpendicular or orthogonal rotation axes, the robot arm can have seven degrees of freedom. This allows the position and / or orientation of the visualization unit to be decoupled from the robot arm posture. Therefore, the robot arm can move or its posture can change without causing movement of the end effector of the robot arm.

[0023] The robot may have multiple axes of rotation and multiple robot arm segments or arm sections. In this document, each arm section should be separated from the others by a hinge (having one degree of freedom) or an axis of rotation. The robot arm may have a first axis of rotation relative to the robot base. The first axis of rotation can be arranged such that rotation of the first robot arm segment or arm section, and thus the entire robot arm, relative to the robot base (when no other hinge is altered) is possible. Preferably, the first axis of rotation is arranged vertically or along the direction of gravity. The terms vertical, horizontal, upper, and lower are visible relative to the operating room. Here, "upper" is approximately the ceiling and "lower" is approximately the bottom connecting the "vertical line." Similarly, the bottom of the operating room extends "horizontally." The second axis of rotation of the robot arm can be arranged such that pivoting, tilting, or pitching of the second robot arm segment relative to the first robot arm segment is possible. The second axis of rotation can be, in particular, perpendicular to the first axis of rotation. A third axis of rotation can be arranged such that rotation of the third robot arm segment relative to the coaxially arranged second robot arm segment is possible. Coaxiality here means that the longitudinal axes of the two robot arm segments are arranged coaxially in the connecting area. Here, the longitudinal axis of the second robot arm segment can be coaxial with or transition into the longitudinal axis of the third robot arm segment. That is, the third axis of rotation can be parallel to or coaxial with the longitudinal axes of the second and third robot arm segments. Thus, rotation of the third robot arm segment about the common longitudinal axis of the second and third robot arm segments is feasible. The degree of freedom of the third robot arm segment may not exist, especially in conventional robots. Preferably, the robot arm can have a fourth axis of rotation, which is arranged such that pivoting of the third robot arm segment relative to the fourth robot arm segment is feasible. In particular, this fourth axis of rotation is perpendicular to the third axis of rotation. A configuration of a robot arm with at least three, especially four, mutually orthogonal axes of rotation enables the hinge with the fourth axis of rotation to move independently of the position and / or orientation of the end effector of the robot arm. Therefore, it is possible to move or shift the hinge with the fourth axis of rotation without moving the end effector. In particular, the decoupling (position and / or orientation) of the end effector and the robot arm posture can be achieved through the degree of freedom of the third rotation axis (through which the third robot segment can rotate relative to the second robot segment).

[0024] The vertical axis of rotation can be arranged parallel to the direction of gravity, while the horizontal axis of rotation can be oriented perpendicular to the direction of gravity.

[0025] According to further optional features of this disclosure, the visualization system has, in particular, an optical sensor, especially a camera. The control unit can be adapted to detect the spatial position of the user's head, especially the position of the user's eyes, via detection, particularly by the optical sensor. Furthermore, the control unit can be adapted to determine the position of the output unit, especially the screen. Additionally, the control unit can be adapted to calculate a line of sight or visual axis, particularly a straight line, between the detected position of the user and the determined position of the output unit. Here, a tolerance range around the calculated line of sight can be included, for example, a type of tube or cylinder with a predefined tolerance diameter around the calculated straight line. The tolerance range around the calculated line of sight can be predefined or variably adapted, for example, by user input. Here, in particular, in addition to the cylindrical tolerance "tunnel," other cross-sectional geometries, such as triangles or quadrilaterals (for blocks), can also be selected and used by the user.

[0026] The spatial position of the user's head can therefore be determined, in particular, by sensors or sensing devices preferably optical. However, the spatial position of the head can also be determined alternatively or additionally (as two redundant detection methods) by a stored data set or heuristic. Here, the data set can be, in particular, a historical data set of past / previous surgeries, storing data on previous surgeries (e.g., specific surgeries for knee prostheses), especially the spatial position of the surgeon's head relative to the output device. The heuristic can use the calculated / estimated head position based on the stored previous surgical data to determine whether the user's line of sight is obstructed, and then maintain that line of sight by (pre-)moving the robotic arm from the surgeon's field of view. The data set can also have a model of the entire operating room, in which the positions of the user and / or objects are stored or considered. This model can be provided to the control unit as a spatial basis for boundary conditions, and the control unit can be adapted to move the robotic arm based on this model (e.g., to avoid collisions).

[0027] The control unit can also be adapted to detect the robot arm posture or configuration and determine whether segments of the robot arm, particularly robot arm segments, are within the line of sight or tolerance. The control unit then determines whether there is any obstruction through the robot arm segments to the direct line of sight between the head, particularly the user's eyes, and the position of the output unit. Using, in particular, optical sensors, the visualization system can detect the position of the user or surgeon, particularly the position of the user's eyes. Based on the detected user's head position, the position of the output unit, and the arm posture, the control unit can calculate whether the user's view is obstructed. Thus, the control unit can detect or determine whether the user's line of sight to the output unit is free or obstructed. This can form the basis for subsequent motion control of the control unit.

[0028] Preferably, the control unit can be adapted to move the robot arm out of the line of sight when an obstruction to the line of sight is determined or identified, thereby removing the obstruction from the robot arm segment, wherein the position and / or orientation of the visual unit serving as the end effector is maintained, particularly by moving the segment of the robot arm with the hinge having a fourth axis of rotation out of the line of sight. The end effector can be moved by the robot arm until the control unit determines that the obstruction to the line of sight has been released, i.e., until the line of sight between the output unit and the user is free.

[0029] The control unit is preferably adapted to control the robot arm so that each robot arm segment, especially the robot arm elbow (in space), does not exceed a predefined height. Here, the predefined height can be coordinates (e.g., Z_max coordinates) stored in the coordinate system of the control unit.

[0030] The control unit can be adapted to control the robotic arm based on a predefined plane extending at a maximum height parallel to the ground, particularly in the horizontal direction, such that no robotic arm segments cross this plane. Here, the plane can be arranged to reduce the likelihood of obstructed line-of-sight connections above the plane. Specifically, the predefined plane can be expanded by two stored vectors and define a type of spatial ceiling for the robotic arm.

[0031] The obstruction of vision is addressed by moving the section of the robotic arm with the hinge on the fourth axis of rotation out of the line of sight. This is achieved, in particular, by rotating the hinge with respect to the third axis of rotation. Due to this degree of freedom, the robotic arm possesses greater "flexibility" than conventional robots. That is, the robotic arm can adopt different postures without moving the end effector to its position and / or orientation. In particular, the hinge on the second axis of rotation can rotate from 90° to 120°. Therefore, the entire robotic arm will move downward in the direction of gravity. However, if the hinge on the third axis of rotation rotates simultaneously by approximately 180°, the end effector can remain in its position. Thus, the robotic arm can perform its zero-space movement.

[0032] According to another embodiment of this disclosure, the output unit is movable relative to the robot base, and in particular, the output unit is movable on a second medical vehicle. Here, the control unit can be adapted to detect the position of the movable output unit by means of a tracking system, particularly by arranging a rigid body with optical markers on the output unit, which is detected by an external camera of the tracking system. Optical sensors can detect the optical markers, and the control unit thereby determines the (variable) position of the output unit.

[0033] In particular, the tracking system can be mounted on a second medical vehicle, for example, rigidly secured, and adapted to (directionally) detect a robot, specifically configured as an (external) camera, with the robot falling within the camera's field of view. Thus, the tracking system can detect and spatially locate the robot and thereby determine the position of the output unit relative to the robot. Alternatively, a tracking system in the form of a camera system, each having at least one camera, can be preferably arranged on both the movable output unit and the robot, the cameras detecting each other and thereby detecting their relative orientation. Here, the tracking system can particularly include sensors, implemented as cameras, radar, lidar, and / or ultrasonic sensors.

[0034] Alternatively or additionally, the output unit can be movably mounted on the first medical vehicle and can be moved by an electric motor. The control unit can determine the position of the output unit relative to the vehicle by controlling the electric motor or the control current on the electric motor.

[0035] The output unit can be, in particular, a screen or (touch) display. The position of the output unit can be calculated by the control unit. For example, the output unit can be set by a stepper motor. By controlling the stepper motor, the control unit can detect the position of the screen.

[0036] The output unit is preferably, alternatively or additionally, mounted in a fixed location, such as on a wall in an operating room. A robotic arm with a visualization unit can move relative to the output unit via this vehicle. The control unit can determine the position of the output unit relative to the vehicle using optical sensors.

[0037] Preferably, the control unit detects objects and / or people in the surrounding environment of the visualization system using optical sensors. Furthermore, the control unit can be adapted to identify collisions between the robotic arm and detected objects and / or people as the robotic arm moves, and to prevent collisions by (slowing down or) stopping the movement of the robotic arm. Using optical sensors, the control unit can create a digital (virtual) model of the entire environment of the visualization system, particularly the entire operating room. All objects and / or people can be included in this model. If a collision with a detected object and / or person is likely, the control unit can stop the movement of the robotic arm and / or output an alarm signal.

[0038] The control unit can also predict the expected / foreseeable movements of the detected personnel and / or robot arm based on historical data and adapt the robot arm's motion characteristics or robot arm posture accordingly.

[0039] According to another optional feature of this disclosure, the control unit is adapted to set / configure the robot arm such that the robot arm segments / arm links are substantially located in a vertical plane and thus oriented parallel to the direction of gravity, in order to increase the rigidity of the visualization unit. The vertical plane can be understood as a plane extending or oriented parallel to the direction of gravity. This can improve the rigidity of the robot arm, especially when the load in the direction of gravity increases sharply.

[0040] Preferably, the control unit is adapted to configure the robot arm in such a way that the robot arm segments are arranged as far away from the user as possible, allowing the user good accessibility to the visualization unit, and particularly, no robot arm segments are arranged between the user's position and the visualization unit. This improves the accessibility of the visualization unit. In particular, the hinge with the fourth axis of rotation can be variably oriented. Here, in particular, an orientation of the fourth hinge towards the user is disadvantageous, while an orientation of the fourth hinge away from the user can be advantageous. The control unit can also improve the accessibility of the visualization unit by controlling the configuration of the individual robot arm segments.

[0041] In particular, the robot arm posture that can be understood as allowing the user to easily reach the visualization unit is the following robot arm posture for the user, in which no part or segment of the robot arm is positioned between the user and the visualization unit.

[0042] According to another optional feature of this disclosure, the control unit is adapted to configure the robot arm or robot arm segment in a manner that avoids singularities in the end position of the robot arm.

[0043] In this paper, what should be understood as the singularity of the robot arm is its posture, especially when the robot arm is fully extended, in which the rotation axes of the two hinges are redundant relative to each other, thus eliminating the robot arm's degrees of freedom. With the additional degrees of freedom of the seven-axis robot, the control unit can set the robot arm posture such that no two hinges overlap.

[0044] Preferably, the control unit is adapted to weight parameters related to collision avoidance, singularity avoidance, improved accessibility, and increased rigidity, and to adapt the robot arm configuration accordingly to achieve optimal robot arm posture. Collision avoidance, in particular, can have the highest weight. The control unit can also, to some extent, balance which parameters are considered more important when there is a target conflict. As mentioned above, the various (optimization) parameters of the robot arm posture can be collision avoidance, singularity avoidance, improved accessibility of the visualization unit, and increased robot arm rigidity. Here, the weights of each parameter can be predefined. Furthermore, the control unit can learn the weights of each parameter through an AI system (artificial intelligence system), especially pure reinforcement learning. Moreover, the control unit can preferably be adapted so that, for example, when there is a target conflict between increasing rigidity and avoiding collisions, the robot posture used to avoid collisions is always preferred. This can be caused, for example, by anticipated consequences that are more negative when the robot arm collides with a person than when the end effector moves (minimum) along the direction of gravity. In particular, parameters to be optimized could be: improving the rigidity of the robot arm and / or avoiding singularities and / or improving the user's accessibility to the visualization unit and / or providing the possibility of moving the robot's "elbow" (especially the hinge of the fourth rotation axis) into different postures through appropriate robot arm posture (when pressed against the microscope or cannula).

[0045] Weighting factors are particularly useful during continuous operation. The control unit can calculate alternative possible arm positions for preset positions and / or orientations of the end effector and control the robot arm to the optimized position with respect to parameters.

[0046] Preferably, the control unit's algorithm can also be used to train the controller to maintain a specific hinge position combination or to optimize a specific hinge position combination within a preset or trained area of ​​one or more hinges.

[0047] In particular, visualization systems can implement additional constraints / limitations or optimization parameters beyond those that obstruct the line of sight through adapted control units. These parameters, in particular, include or combinations of the following: reserving space (spatial volume) for assistive surgeons; maximizing robot accessibility; maximizing robot arm maneuverability; considering user preferences for hinge positions (especially the robot arm elbow); avoiding singularities; and optimizing end effector stiffness through robot arm stiffness or other motion parameters. If multiple optimization parameters / criteria are used, these parameters / criteria can be combined with each other, particularly through weighting or weighting factors, via the control unit. Weighting factors can be applied, particularly on an instantaneous basis. Algorithms of the control unit can be used, in particular, to calculate alternative arm positions for a specific end effector position and move the robot arm to a position within the optimized boundary conditions. Using this algorithm, the robot arm can also be trained to maintain specific hinge position combinations or optimize within a preset or trained area of ​​one or more hinges. For example, during surgery, the surgeon manually moves the robot elbow to a specific position, and the robot arm maintains that elbow position when the end effector moves again. Alternatively, the zero space (fixed end effector position) can be optimized only, or the hinge configuration can be optimized as the end effector moves (sending the target position and / or target orientation to the end effector while sending preferred angles to one or more hinges). In the case of multiple hinges, the hinges can be weighted relative to each other, particularly via a correlation factor (similar to a weighting).

[0048] Preferably, the user can manually move the hinge with the fourth axis of rotation into a favorable position, and the control unit can store the robot arm posture with the hinge in the favorable position and automatically manipulate the robot arm posture.

[0049] The control unit can not only maintain the preset position and / or orientation of the end effector in any robot arm posture, but also follow the preset angles of the individual hinges of the robot arm.

[0050] Preferably, the visualization system has an input unit, particularly a button or touch display, by which the user can manually request movement of the robot arm without changing the position and / or orientation of the visualization unit. Here, the hinge with a fourth axis of rotation can rotate 90° about the horizontal or longitudinal axis of the robot arm. Here, the longitudinal axis of the robot arm is its general longitudinal extension. In particular, the control unit can be adapted to rotate the elbow of the robot arm (particularly with respect to the fourth hinge or fourth axis) 45° about the substantially horizontal axis via the input unit, such as a button, upon user input (an interactive feasible scheme), or to rotate the elbow continuously until no further input is received.

[0051] The input unit can be arranged on the robot base and can also be a (touch) display or joystick, through which the user controls the robot arm. Here, the joystick can preferably be arranged not only on a movable vehicle but also on an end effector.

[0052] Preferably, the control unit can be adapted to set the robot arm posture even when the end effector is moved manually by the user, so as to avoid, for example, collisions with people and / or objects.

[0053] The user can grasp the end effector and move or pull it to the desired position. Here, the robotic arm offers minimal resistance, allowing the user to move or pull the end effector effortlessly to the desired location. During manual movement of the end effector, the control unit can configure the robotic arm to set or optimize parameters such as increased rigidity, singularity avoidance, collision avoidance, and improved accessibility.

[0054] According to further optional features of this disclosure, the visualization unit is a digital microscope, particularly a stereomicroscope / stereoscopic microscope, an (analog) optical microscope, especially a stereomicroscope, and / or an endoscope. Photographs (images) taken by the visualization unit can be displayed to the user, particularly through an output unit. Areas within the patient's body openings can also be displayed via an endoscope.

[0055] Furthermore, the end effector may have an instrument guide, particularly a cannula, mounted on a visualization unit. In this case, the control unit can optimize or set the position and / or orientation of the visualization unit so that the instrument guide is properly oriented. In particular, rigidity optimization can be prioritized in this case so that the end effector does not exhibit undesirable movement under external forces, such as pressure applied from above.

[0056] The robotic arm can also have end effectors on the visualization unit. For example, a second end effector could be an endoscope, camera, or surgical tool for patient contact. If there is a conflict of objectives between the configurations of the individual end effectors, the individual end effectors can be weighted. The weights can be varied or preset during continuous operation of the robot.

[0057] The control unit can be particularly housed within the robot's base. The vehicle, serving as a movable robot base, can have a CPU, storage units such as hard drives or RAM, and an energy source, especially a power supply.

[0058] The objective of this disclosure relates to computer-readable storage media and to computer programs in such a way that these include instructions, which, when executed by a computer, cause the computer to implement the control method according to this disclosure. Attached Figure Description

[0059] The present disclosure will now be explained in more detail with reference to the accompanying drawings, based on preferred embodiments. It is shown that:

[0060] Figure 1 A schematic diagram of a visualization system based on existing technology is shown;

[0061] Figure 2 A schematic diagram of a visualization system according to an embodiment of the present disclosure is shown;

[0062] Figure 3 Show Figure 1 A schematic diagram of the visualization system in the image, showing the obstructed line of sight.

[0063] Figure 4 Show Figure 1 A schematic diagram of the visualization system, showing a free line of sight; and

[0064] Figure 5 A flowchart illustrating a control method according to a preferred embodiment of the present disclosure is shown.

[0065] The accompanying drawings are schematic in nature and are intended only for understanding this disclosure. The same elements are given the same reference numerals. Features of various embodiments may be substituted for each other. Detailed Implementation

[0066] Figure 1 A visualization system 100 according to the prior art is shown. The visualization system 100 has a robot 102 with a movable robotic arm 106 on which a visualization unit 108 is mounted as an end effector. In this case, the visualization unit 108 is a simulated microscope, which the user looks directly into. Through this configuration of the robotic arm, the position and / or orientation of the visualization unit 108 are forcibly coupled to the posture of the robotic arm. Figure 1 In this case, the robot arm's posture is unfavorable because the user is obstructed by the robot arm 106. As described below, the visualization system according to this disclosure solves this problem.

[0067] Figure 2A preferred embodiment of a medical robot-assisted visualization system 1 is shown. The visualization system 1 has a robot 2 with a robot base 4. The robot base 4 is currently a mobile medical vehicle used in an operating room. A robot arm 6 is movably connected to the robot base 4. The visualization system 1 has a visualization unit 8 as an end effector for the robot 2, which is mounted on the movable robot arm 6. The visualization unit 8 can be spatially positioned by the movement of the robot arm 6. The visualization system 1 also has a specially configured control unit 10 adapted to control the position and / or orientation of the visualization unit 8. The robot arm 6 has seven (different and spaced) axes A1 to A7, through which the robot arm 6 can be moved to different robot arm postures / configurations, particularly while the position and / or orientation of the visualization unit 8 remains unchanged. In this embodiment, the robot 2 is a seven-axis robot with a surgical microscope (as the visualization unit 8) as an end effector. With this specific configuration, the robot 2 can flexibly set the arrangement of the robot arm 6 without forcing the end effector to move.

[0068] The visualization system 1 also has a (surgical) screen 12 as an output unit, which is mounted on the robot base 4. The visualization system 1 has a camera 14 as an optical sensor, which detects the user's spatial position and, if necessary, the position of another screen (not shown).

[0069] In the current configuration, the robot arm 6 has seven axes of rotation A1 to A7 and six robot arm segments S1 to S6. Each robot arm segment 18 or S1 to S6 is separated from each other by a hinge or one of the axes of rotation A1 to A7. The first axis of rotation A1 is arranged such that rotation of the first robot arm segment S1, and thus of the robot arm 6, relative to the robot base 4 is feasible. The first axis of rotation A1 is located vertically on the robot base 4. The second axis of rotation A2 is perpendicular to the first axis of rotation A1 and arranged horizontally (this second axis of rotation can rotate about the first axis of rotation A1, while maintaining a horizontal orientation). The second axis of rotation A2 is arranged such that pivoting / tilting of the second robot arm segment S2 relative to the first robot arm segment is feasible. The second axis of rotation A2 is also arranged perpendicular to the longitudinal axis of the second robot arm segment S2. The third axis of rotation A3 is arranged such that rotation of the third robot arm segment S3 relative to the coaxially arranged second robot arm segment S2 is feasible. In other words, the longitudinal axes of the second robot arm segment S2 and the third robot arm segment S3 coincide (coaxial) with each other and extend along the third rotation axis A3.

[0070] The fourth rotation axis A4 is arranged such that pivoting of the third robot arm segment S3 relative to the fourth robot arm segment S4 is feasible. The fourth rotation axis A4 is perpendicular to both the third rotation axis A3 and the fifth rotation axis A5. Therefore, the fourth rotation axis A4 is oriented parallel to the second rotation axis A2. The fifth rotation axis A5 extends along the longitudinal axis of the fourth robot arm segment S4. Therefore, the fifth rotation axis A5 enables the rotational movement of the fifth robot arm segment S5 about the longitudinal axis of the fourth robot arm segment S4. With the robot arm 6 fully extended, the fifth rotation axis A5 can be located on the third rotation axis A3. The sixth rotation axis A6 is arranged perpendicular to the fifth rotation axis A5 and, in particular, parallel to the fourth rotation axis A4. Therefore, the sixth rotation axis A6 enables the pivoting of the sixth robot arm segment S6 relative to the fifth robot arm segment S5. A visualization unit 8 is rotatably mounted on the sixth robot arm segment S6 as an end effector. The visualization unit 8 can rotate about the seventh rotation axis A7 relative to the sixth robot arm segment S6. The seventh rotation axis A7 is perpendicular to the sixth rotation axis A6. All rotation axes A1 to A7 are perpendicular to or orthogonal to their respective adjacent rotation axes. For example, the third rotation axis A3 is therefore perpendicular to the adjacent second rotation axis A2 and the adjacent fourth rotation axis A4.

[0071] The user can input the desired position and / or orientation of the visualization unit 8 through the input unit 20. The input unit 20 may be a (touch) display, a button on the robot base 4, and / or a joystick on the visualization unit 8.

[0072] Figure 3 The diagram illustrates the robot arm pose or the configuration of robot arm segment 18 for robot arm 6. In the illustrated pose, the hinge of the robot arm with a fourth axis of rotation A4 is arranged such that it obstructs the user's line of sight 16 to screen 12 via robot arm segment 18 or via the hinge with the fourth axis of rotation A4. The disadvantage of this is that the user cannot see the entire screen 12 or change their posture to see the entire screen 12. This may force the user into an ergonomic posture and reduce the advantages of the visualization system with screen 12.

[0073] The control unit 10 detects the position of the user's head via the camera 14, and even the position of the user's eyes. Furthermore, the control unit 10 determines the position of the screen 12. The control unit 10 calculates the line of sight 16 as a straight line between the detected eye position and the determined screen position. Additionally, since the control unit 10 can detect the robot arm's posture, it can determine whether a portion or segment of the robot arm is in the line of sight 16 and obstructs the view. Therefore, the control unit 10 determines whether the user has free access to the screen 12.

[0074] The individual robot arm segments 18 move relative to each other, for example, via (electric) servo motors (not shown). The control unit 10 can calculate the robot arm posture via control signals from the servo motors or determine the current configuration of the robot arm segments via the kinematics within the robot.

[0075] For example, screen 12 can move relative to robot base 4. Here, screen 12 can be moved up and down relative to robot base 4, for example, by means of an electric motor (not shown) in the manner of pressing a button. Control unit 10 can calculate the position of screen 12 based on control signals to the electric motor.

[0076] If screen 12 or another screen is arranged on the second movable vehicle and can move relative to robot 2, camera 14 can detect the position of external screen 12.

[0077] Figure 4 The diagram illustrates the robot arm posture of 6, where hinge movement along a fourth rotation axis A4 allows the user's line of sight 16 on screen 12 to be free. The core concept here is that when the control unit determines that the line of sight 16 is obstructed, robot arm 6 moves to another robot arm posture, such as... Figure 3 As shown. By implementing it as a 7-axis robot, the robot arm 6 can move without changing the position and / or orientation of the end effector. Therefore, the end effector 8 is... Figure 4 The position and / or orientation in Figure 3 Same. Only the robot arm posture was changed.

[0078] In particular, the control unit 10 can be adapted to calculate the hinge configuration of the robotic arm 6 based on the spatial geometry of the operating room, where the focus or main weights are located in the surgeon's free line of sight. Here, the environment model provides input for the optimization algorithm. The environment model can take into account or integrate the patient's anatomy and / or the foreseeable movements of the personnel and / or, when considering the surgical situation, the foreseeable movements of the robot and / or the entire geometry of the operating room, in order to avoid collisions.

[0079] Here, the optimization can in particular have two or more of the following mandatory conditions or restrictions as parameters, either uniquely or in any combination:

[0080] - Minimize obstruction of the user's view with the robotic arm 6.

[0081] - Rotate the elbow of robot arm 6 to a specific position.

[0082] - Manually defined constraints during use, especially the spatial arrangement of hinges within the area, must be adhered to for subsequent movement of the end effector.

[0083] - Avoid collisions with objects or anatomical sections of the body that may come into contact with patients or other personnel.

[0084] The aforementioned limitations are used, in particular, by the control unit 10 to optimize robot motion and / or robot arm posture, in order to optimize one or a combination of the following parameters:

[0085] - Improve rigidity

[0086] - Improved operability of the robotic arm 6

[0087] - Improved accessibility of the robotic arm 6

[0088] -Avoid the singularity of robotic arm 6

[0089] - Optimization of the motion of robot arm 6 (e.g., optimization to enable the robot arm to accelerate rapidly from a position). This can be achieved by combining multiple parameters using weighting factors for boundary conditions. The weighting factors and / or optimization criteria can also be changed during continuous operation. The position of robot arm 6 can be optimized either after reaching a new end effector position or immediately during movement to a new position.

[0090] The visualization system 1 is particularly equipped with a navigation system that tracks the position of the visualization unit 8.

[0091] The visualization system 1 may be equipped with a second (or third) effector (not shown here), such as an instrument guide or a cannula, mounted on the visualization unit. In this case, optimization criteria are applied, necessitating consideration of instrument-guided surgery, with particular emphasis on rigidity optimization. If a second end effector is used, the requirements of the two end effectors can be balanced to find the optimal hinge position, or one end effector can be prioritized over the other (a change in priority can occur during ongoing operation).

[0092] Figure 5A flowchart or process diagram illustrating a control method according to the present disclosure for a preferred embodiment of a visualization system 1 for medical robot assistance is shown. In step 1, the robot arm 6 moves or moves the visualization unit 8 to a preset target position and / or target orientation. The preset target position and / or target orientation can be input or preset by the user through the input unit 20. In step 2, the control unit 10 detects the spatial position of the user's head, particularly the position of the user's eyes, using a camera 14 as an optical sensor. Furthermore, the control unit 10 determines the position of the screen 12, which serves as an output unit. In step 3, the control unit calculates a line of sight 16 or visual axis between the determined position of the screen 12 and the detected head position of the user. Preferably, a tolerance range can be drawn around the calculated line of sight 16. Using the tolerance range, a cylinder with a preset diameter can be formed along the line of sight 16, which is constructed as a straight line. The diameter of the (tolerance) cylinder can be, for example, 20 cm or particularly preferably 50 cm. In step 4, the control unit 10 detects the robot arm posture. That is, the control unit 10 detects the orientation and / or orientation of each arm segment / robot arm section 18 of the robot arm 6. In step 5, the control unit 10 identifies potential obstructions to the calculated line of sight 16, for example, via a single robot arm segment 18. Specifically, the control unit 10 detects intrusions of the robot arm 6 into tolerance ranges. If an obstruction to the line of sight 16 is identified by the control unit 10, the control unit 10 moves the robot arm 6 in step 6, wherein the target position and / or target orientation of the visualization unit 8 remains constant.

[0093] The control unit 10 also includes an environment model in which the position of the user or surgeon relative to the visualization system 1 and the position of the screen 12 are detected. Furthermore, the environment model includes the robot arm's posture. The environment model can detect the entire operating room and is captured by the camera 14. Based on the environment model, the control unit 10 controls the robot arm 6.

[0094] An environment model may in particular have one or more of the following elements:

[0095] -The patient's anatomical structure;

[0096] - The predictable movement of one or more users;

[0097] - Predictable movements of the robotic arm 6;

[0098] - The geometry of the entire operating room;

[0099] Using an environmental model, the control unit 10 prevents, for example, collisions between the robotic arm 6 and detected users, patients, and / or objects in the operating room. Furthermore, the control unit 10 optimizes the robotic arm posture by improving the rigidity of the robotic arm 6, the accessibility of the visualization unit 8, and avoiding singularities in the robotic arm 6.

[0100] List of reference numerals

[0101] 1. Visualization System

[0102] 2 robots

[0103] 4. Robot Base

[0104] 6 robotic arms

[0105] 8 Visualization Units

[0106] 10 Control Unit

[0107] 12 screens

[0108] 14. Optical sensor (camera)

[0109] 16 line of sight

[0110] 18 robot arm segments

[0111] 20 Input Units

[0112] 100 Visualization System

[0113] 102 robots

[0114] 106 robotic arms

[0115] 108 Visualization Units

[0116] A1 First axis of rotation

[0117] A2 Second axis of rotation

[0118] A3 Third axis of rotation

[0119] A4 Fourth axis of rotation

[0120] A5 Fifth axis of rotation

[0121] A6 Sixth axis of rotation

[0122] A7 Seventh Rotation Axis

[0123] S1 First Robot Arm Segment

[0124] S2 Second Robot Arm Segment

[0125] S3 Third Robotic Arm Segment

[0126] S4 Fourth Robot Arm Segment

[0127] S5 Fifth Robot Arm Segment

[0128] S6, the sixth robot arm segment.

Claims

1. A medical robot-assisted visualization system (1) for visualization, particularly during surgical procedures at a patient (P), comprising: The robot (2) has a robot base (4), preferably a movable medical vehicle as a mobile robot base (4) and a movable robot arm (6) connected to the robot base (4); The visualization unit (8), serving as an end effector of the robot (2), is supported or mounted on the movable robot arm (6) and can be spatially positioned by the movement of the robot arm (6), particularly in terms of location and orientation. Control unit (10), the control unit being adapted to control at least one position and / or orientation of the visualization unit (8), Its features are, The robot (2) is a seven-axis robot and / or the robot arm (6) has at least seven axes, particularly about seven rotational axes, through which the robot arm (6) can move into different robot arm postures while the position and / or orientation of the visualization unit (8) remains constant.

2. The medical robot-assisted visualization system (1) according to claim 1, characterized in that, The axes are rotation axes (A1, A2, A3, A4, A5, A6, A7), and each of the adjacent rotation axes (A1, A2, A3, A4, A5, A6, A7) of the robot arm (6) is arranged perpendicular to each other.

3. The medical robot-assisted visualization system (1) according to claim 1 or 2, characterized in that, The first axis of rotation (A1) is arranged such that rotation of the first robot arm segment (S1) and therefore the robot arm (6) relative to the robot base (4) is possible. The second axis of rotation (A2) is arranged such that pivoting of the second robot arm segment (S2) relative to the first robot arm segment (S1) is possible, and in particular, the second axis of rotation (A2) is perpendicular to the first axis of rotation (A1). The third axis of rotation (A3) is arranged such that the twisting of the third robot arm segment (S3) relative to the coaxially arranged second robot arm segment (S2) is feasible, and Preferably, the fourth axis of rotation (A4) is arranged such that pivoting of the fourth robot arm segment (S4) relative to the third robot arm segment (S3) is possible, and in particular, the fourth axis of rotation (A4) is perpendicular to the third axis of rotation (A3).

4. The medical robot-assisted visualization system (1) according to any one of claims 1 to 3, characterized in that... The sensor (14), especially the optical sensor, particularly the camera, and the control unit (10) therefrom are adapted to: The spatial position of the user's head, especially the position of the user's eyes, is detected by optical sensor (14). Determine the position of the output unit (12), especially the screen. Specifically, the line of sight (16) between the detected position of the user and the determined position of the output unit (12) is calculated within the tolerance range surrounding the line of sight (16), and The robot arm posture is detected and it is determined whether a segment of the robot arm (6) is within the line of sight (16), in particular the tolerance range, and whether the robot arm segment (18) of the robot arm (6) obstructs the direct line of sight between the user's head, in particular the eyes, and the position of the output unit (12).

5. The medical robot-assisted visualization system (1) according to claim 4, characterized in that, The control unit (10) is adapted to move the robot arm (6) out of the line of sight (16) when it detects an obstruction to the line of sight connection, thereby removing the obstruction of the robot arm segment (18), wherein the position and / or orientation of the visualization unit (8) as an end effector is maintained, and in particular the hinge of the robot arm (6) having a fourth axis of rotation (A4) is moved out of the line of sight (16).

6. The medical robot-assisted visualization system (1) according to claim 4 or 5, characterized in that, The output unit (12) is movable relative to the robot base (4), particularly on the second medical vehicle, wherein the control unit (10) is adapted to detect the position of the movable output unit (12) by means of a tracking system, particularly a rigid body with optical markers arranged at the output unit (12), the rigid body being detected by an external camera of the tracking system.

7. The medical robot-assisted visualization system (1) according to any one of claims 4 to 6, characterized in that, Objects and / or people around the visualization system (1) are detected, particularly by an optical sensor (14), and The control unit (10) is adapted to identify and prevent collisions between the robot arm (6) and detected objects and / or people by stopping the movement of the robot arm (6) as it moves.

8. The medical robot-assisted visualization system (1) according to any one of claims 1 to 7, characterized in that, The control unit (10) is adapted to set the robot arm (6) such that the robot arm segments (18) are substantially in a vertical plane and therefore oriented parallel to the direction of gravity in order to improve the rigidity of the robot arm (6).

9. The medical robot-assisted visualization system according to any one of claims 1 to 8, characterized in that, The control unit (10) is adapted to configure the robot arm (6) such that each robot arm segment (18) is arranged furthest from the user, so that the user can easily reach the visualization unit (8) and in particular, no robot arm segments (18) are arranged between the user's position and the visualization unit (8).

10. The medical robot-assisted visualization system (1) according to any one of claims 1 to 9, characterized in that, The control unit (10) is adapted to configure the robot arm (6) to avoid singularities, particularly at the end position of the robot arm (6).

11. The medical robot-assisted visualization system (1) according to any one of claims 1 to 10, characterized in that, The control unit (10) is adapted to weight the various parameters of collision avoidance, avoidance of singularities, improvement of accessibility and / or improvement of rigidity, and to adapt the configuration of the robot arm (6) according to the weighting to achieve the optimal posture of the robot arm, wherein, in particular, collision avoidance has the largest weight.

12. The medical robot-assisted visualization system (1) according to any one of claims 3 to 11, characterized in that... The input unit (20), in particular a button or touch display, allows the user to manually request the movement of the robot arm (6) by manipulating the input unit, wherein the position and / or orientation of the visualization unit (8) remains constant, wherein, in particular during manipulation, the hinge having the fourth axis of rotation (A4) rotates 90° about a virtual horizontal axis or about the longitudinal axis of the robot arm (6).

13. The medical robot-assisted visualization system (1) according to any one of claims 1 to 12, characterized in that, The visualization unit (8) is a digital surgical microscope, an optical microscope, and / or a medical endoscope.

14. A control method for a medical robot-assisted visualization system (1), particularly for a robot-assisted visualization system (1) according to any one of the preceding claims, characterized in that... The following steps: - The robot arm (6) of the visualization system (1) moves the visualization unit (8) as the end effector of the robot (2) to a preset target position and / or target orientation via the control unit (10). The robot has a robot base (4) and the robot arm (6) of the visualization system (1) connected to the robot base (4). The robot (2) is a seven-axis robot and / or the robot arm (6) has at least seven axes and is particularly rotatable about seven rotational axes. Through these axes, the robot arm (6) can move to different robot arm postures while the position and / or orientation of the visualization unit (8) remains constant. - The spatial position of the user's head, especially the position of the user's eyes, is detected by the optical sensor (14), and the position of the output unit (12) is determined by the control unit (10); - Calculate the line of sight (16) between the detected position of the user and the determined position of the output unit (12); - The robot arm posture of the robot arm (6) is detected by the control unit (10); -The control unit (10) identifies possible obstructions to the line of sight (16), particularly through the robotic arm segments (18) of the robotic arm (6); - If an obstacle is detected, the robot arm (6) is moved by the control unit (10), wherein the target position and / or target orientation of the visualization unit (8) remain constant.

15. The control method according to claim 14, characterized in that, The step of detecting the robot arm posture of the robot arm (6) by the control unit (10) during the movement of the visualization unit (8) by the robot arm (6).

16. A computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform the steps of the control method according to any one of claims 14 or 15.

17. A computer program comprising instructions that, when executed by a computer, cause the computer to perform the steps of the control method according to any one of claims 14 or 15.

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