Abstract:
In a retention device, a medical robot and a method to set the tool center point of a medical robot, the retention device has a fixing device to fix the head of a person held by the retention device. The fixing device provides an indication of the position of the openings of the auditory canals of the ears of the person relative to the retention device based on the relation between the fixing device and the head of the person and the relation between the fixing device and the retention device.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention concerns a retention device, a medical robot and a method to set the tool center point of a medical robot. 
         [0003]    2. Description of the Prior Art 
         [0004]    Robots are generally work machines that can be equipped with tools for automatic handling and/or processing of subjects and are programmable in multiple movement axes, for example with regard to orientation, position and workflow. Robots typically possess programmable controllers (control devices) that control the movement workflow of the robot during the operation. 
         [0005]    Moreover, robots are increasingly used in medical technology, for example as carriers of patient positioning systems. For example, DE 10 2005 041 606 A1 discloses a patient positioning device to position a patient in an exposure position for a radiation therapy system. The patient positioning device comprises a patient retention module and a positioning arm moving the patient retention module; a therapy control center controls the movement of said positioning arm. 
         [0006]    In the field of otorhinolaryngological (ENT) medicine, different illnesses affecting the sense of equilibrium exist. One example of such an illness is benign paroxysmal positional vertigo (BPPV), in which affected persons suffer from rotatory vertigo as soon as they change the position of their heads. This rotatory vertigo is triggered by a separation of otolith particles of the utricular spot, which then causes an irritation of the nerve cells in the semicircular canals of the affected ear, which in turn causes the vertigo. 
         [0007]    The complaint can be treated with therapy through a specific positioning of the affected persons, as is described by John M. Epley, for example. The particles separate as a result of a targeted and geometric sequence of repositionings of the affected person and are swept into a region of the vestibule of the vestibular labyrinth where they no longer cause complaints. 
         [0008]    Depending on the affected semicircular canals, the affected person is repositioned in part by means of complex sequences. In particular, the repositionings associated with the vertical and rear semicircular canals can be implemented only barely or not at all. Moreover, a relatively precise positioning of the affected person and the time workflow of the repositioning are likewise relatively critical. In order to achieve a relatively good therapeutic success, the movement of the affected person should ensue relative to the center of the affected vestibular organ (equilibrium organ). 
       SUMMARY OF THE INVENTION 
       [0009]    It is an object to provide a device that allows for an improved result in the treatment of the aforementioned positional vertigo. 
         [0010]    The object of the invention is achieved in accordance with the invention by a retention device having a patient support that supports a person, and having a fixing device that fixes the head of a person held by the retention device relative to the patient support, the fixing device being configured to provide an indication of the position of the openings of the auditory canals of the ears of the person relative to the retention device, due to the known setting (relation) of the fixing device with the head of the person. 
         [0011]    The invention also encompasses a medical robot having a retention device as described above, a control device, and a robot arm that has multiple axes and an attachment device controlled by the control device, the retention device being attached to the attachment device so as to also be controlled by the control device. 
         [0012]    The invention also encompasses a method to set the tool center point of a robot that has a robot arm with an attachment device at which a retention device with a fixing device as described above is attached. In the method, the head of a person held with the retention device is fixed by means of the fixing device, determine the position of one of the two eardrums of the person is determined by means of measurement devices of the fixing device, relative to the retention device, the position of the hearing organ associated with the eardrum relative to the retention device is determined, and the tool center point of the robot is placed in the position of the hearing organ. 
         [0013]    The retention device according to the invention, which is (for example) fashioned as a patient bed, carries the fixing device with which the head of the person can be fixed relative to the retention device. The retention device is fashioned such that a conclusion as to the positions of the openings of the auditory canals relative to the retention device is enabled based on its setting associated with the person. For example, this can be achieved by the fixing device having suitable automatic measurement devices that encompass the ears of the person as soon as his head is fixed with the fixing device. Such automatic measurement devices can be, for example, position measurement devices. It is also possible for an operator to read the position of the openings of the ears mechanically at the fixing device based on the mechanical setting of the fixing device, for example. 
         [0014]    When the position of the opening of the ear whose hearing organ triggers the vertigo is known relative to the retention device, the position of the relevant hearing organ can then be determined based on this information in order, for example, to control the robot according to the invention so as to execute a movement relative to the position of the relevant hearing organ, this movement being designed for administering therapy to the person. 
         [0015]    Based on the position (determined by means of the fixing device) of one of the openings of the auditory canals of the person, the robot according to the invention can then be set up to set the tool center point (whose movement in space can be controlled by means of the control device) in relation to this opening, in particular in the position of the relevant equilibrium organ. 
         [0016]    The fixing device can have a measurement device that abuts the openings of the auditory canals in the setting associated with the head of the person and determines the distance to the eardrums of the person. Auditory canals of different persons are of different lengths. Requirements for an improved determination of the position of the eardrum associated with the hearing organ to be treated are satisfied due to this embodiment of the fixing device, so the position of the relevant hearing organ can likewise be determined more precisely relative to the retention device, and thus also relative to the robot. The measurement device is preferably based on a non-contact measurement method, for example laser or ultrasound, but contact-based measurement devices can also be used. 
         [0017]    Based on the position (determined by means of the fixing device and the measurement device) of one of the eardrums of the person, the robot according to the invention can then be set up to set the tool center point (whose movement in space can be controlled by means of the control device) in relation to this eardrum, in particular in the position of the relevant equilibrium organ. 
         [0018]    If the retention device according to the invention is a patient bed, the fixing device can have first displacement devices that allow a displacement of the measurement device in the direction of the longitudinal axis of the patient bed. The setting of the first displacement devices thus allows a conclusion to be made as to the position of the openings of the ears relative to the longitudinal axis of the patient bed. 
         [0019]    In an embodiment of the retention device according to the invention, wherein measurement devices are used that emit signals that are a measure of the displacement of the measurement devices relative to the longitudinal axis are integrated into the first displacement devices, it is possible in a relatively simple and automated manner to determine the position of the openings of the ears relative to the longitudinal axis of the patient bed. 
         [0020]    The fixing device can also have second displacement devices that allow a displacement of the measurement device in the direction of the transverse axis of the patient bed. The setting of the second displacement devices thus allows a conclusion to be made as to the position of the openings of the ears relative to the transverse axis of the patient bed. 
         [0021]    In an embodiment of the retention device according to the invention, wherein measurement devices are sued that emit signals that are a measure of the displacement of the measurement devices relative to the transverse axis are integrated into the second displacement devices, it is possible in a relatively simple and automated manner to determine the position of the openings of the ears relative to the transversal axis of the patient bed. 
         [0022]    The fixing device can have third displacement devices that allow a displacement of the measurement device at a right angle to a surface of the patient bed on which the patient lies. The setting of the third displacement devices thus allows a conclusion to be made as to the position of the openings of the ears relative to the surface of the patient bed. 
         [0023]    In an embodiment of the retention device according to the invention, wherein measurement devices are used that emit signals that are a measure of the displacement of the measurement devices relative to the surface of the patient bed are integrated into the third displacement devices, it is possible in a relatively simple and automated manner to determine the position of the openings of the ears relative to the transversal axis of the patient bed. 
         [0024]    The fixing device can also be designed to have articulated arms, that embody (for example) measurement scales and/or angle transmitters to determine set angles, and that fix the head of the person. The measurement scales, or possibly measurement transmitters that are connected with the control device, provide the indication of the position of the openings of the auditory canals of the ears of the person. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  shows a robot with a patient bed having a fixing device in accordance with the invention. 
           [0026]      FIG. 2  is a side view of the patient bed of  FIG. 1 . 
           [0027]      FIG. 3  is a plan view of the patient bed of  FIGS. 1 and 2 . 
           [0028]      FIG. 4  is a flowchart illustrating the setting of the tool center point of the robot in accordance with the invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]      FIG. 1  shows a medical robot R with a robot arm M. The robot arm M essentially represents the movable part of the robot R and has multiple axes  1 - 6 , multiple levers  7 - 10  and a flange F at which (in the case of the present exemplary embodiment) a patient bed L (shown in detail in  FIGS. 2 and 3 ) is attached as an example of a patient retention device.  FIG. 2  shows a side view and  FIG. 3  shows a plan view of the patient bed L. 
         [0030]    Each of the axes  1 - 6  is moved with an actuator (for example an electrical actuator)  11 - 16  that are connected (not shown) with a control computer  17  of the robot R so that the control computer  17  or a computer program running on the control computer  17  can control the electrical actuators  11 - 16  such that the position of the flange F of the robot R, and thus the patient bed L or, respectively, its tool center point TCP, can essentially be freely aligned in space. Each electrical actuator  11 - 16  of the robot R is formed, for example, by a motor and possibly power electronics activating the motor. 
         [0031]    The patient bed L also has a fixing device  20 , and a person P whose head K is fixed with the fixing device  20  so that the head K is essentially immobile relative to the patient bed L lies on the patient bed L. 
         [0032]    In the present exemplary embodiment, the control computer  17  is set up to adjust the tool center point TCP to the person P. The setting of the tool center point TCP adapted to the person P is summarized with a flowchart shown in  FIG. 4 . 
         [0033]    In the present exemplary embodiment, the fixing device  20  has displacement devices in the form of longitudinal rails  21   a ,  21   b  aligned in the direction of the longitudinal axis A (x-direction) of the patient bed L. The longitudinal rails  21   a ,  21   b  are respectively attached to the sides of the patient bed L. 
         [0034]    In the present exemplary embodiment, the fixing device  20  has displacement devices  22   a ,  22   b  that are supported such that they can be displaced in the longitudinal rails  21   a ,  21   b  so that the displacement devices  22   a ,  22   b  can be slid in the direction of the longitudinal axis A of the patient bed L. 
         [0035]    In the case of the present exemplary embodiment, the displacement devices  23   a ,  23   b  are executed in a telescoping manner relative to the transversal axis Q (y-direction) aligned at a right angle to the longitudinal axis A, so as to interact with the displacement devices  22   a ,  22   b . Measurement devices  24   a ,  24   b  respectively connected (not shown) with the control computer  17  are attached to the ends of said displacement devices  23   a ,  23   b  facing away from the sides of the patient bed L. The displacement devices  23   a ,  23   b  executed in a telescoping manner are coupled with the displacement devices  22   a ,  22   b  so that they can be displaced at a right angle to the longitudinal axis A and at a right angle to the transversal axis Q of the patient bed L. It is thus possible to align the measurement devices  24   a ,  24   b  at a desired distance from the surface  19  of the patient bed L (z-direction). The measurement devices  24   a ,  24   b  can be displaced in the direction of the transversal axis Q by means of the displacement devices  23   a ,  23   b  executed in a telescoping manner. 
         [0036]    The fixing device  20  is provided to fix the head K of the person P relative to the patient bed L in that the measurement device  24   a  approaches the ear  18   a  and the measurement device  24   b  approaches the ear  18   b  of the person P. 
         [0037]    If the head K of the person P is fixed, the position of the displacement devices  22   a ,  22   b  relative to the longitudinal axis A can be read, for example by means of a measurement scale (not shown) arranged at the longitudinal rails  21   a ,  21   b . The longitudinal rails  21   a ,  21   b  can also or alternatively possess measurement sensors (not shown for the sake of clarity) connected with the control computer  17 , as is provided in the present exemplary embodiment, the signals of which measurement sensors transmit to the control computer  17  information about the position of the displacement devices  22   a ,  22   b  relative to the longitudinal axis A of the patient bed L, and thus of the measurement devices  24   a ,  24   b  relative to the longitudinal axis A of the patient bed L. 
         [0038]    The displacement devices  22   a ,  22   b  can likewise be a measurement scale based on which the position of the telescoping displacement devices  23   a ,  23   b  relative to the surface  19  of the patient bed L can be read. As is provided in the present embodiment, the displacement devices  22   a ,  22   b  can also or alternatively have measurement sensors (not shown for clarity) connected with the control computer  17  whose signals transmit to the control computer  17  information about the position of the telescoping displacement devices  23   a ,  23   b  relative to the surface  19  of the patient bed L, and thus of the measurement devices  24   a ,  24   b  relative to the surface  19  of the patient bed L. 
         [0039]    The telescoping displacement devices  23   a ,  23   b  can likewise be a measurement scale based on which the position of the measurement devices relative to the transverse axis Q of the patient bed L can be read. As is provided in the present exemplary embodiment, the displacement devices  23   a ,  23   b  can also or alternatively possess measurement sensors (not shown for the sake of clarity) connected with the control computer  17  whose signals transmit to the control computer  17  information about the position of the measurement devices  24   a ,  24   b  relative to the transversal axis Q of the patient bed L. This enables the control computer  17  to determine the position of the measurement devices  24   a ,  24   b  relative to the patient bed L (Step S 1  of the flowchart shown in  FIG. 4 ). 
         [0040]    Furthermore, the patient bed P is attached at the flange F of the robot R in a position known to the control computer  17  and is aligned in an orientation known to the control computer  17  so that the control computer  17  can determine the position of the measurement devices  24   a ,  24   b  relative to the flange F from the signals originating from the measurement sensors (Step S 2  of the flowchart). 
         [0041]    In the present exemplary embodiment, the measurement devices  24   a ,  24   b  lie at the ears  18   a ,  18   b , and in particular at the openings of the ear canals (external auditory canals). In the case of the present exemplary embodiment, the measurement devices  24   a ,  24   b  are executed such that they in particular determine the length of the external auditory canals—thus the distance from the openings of the external auditory canals to the respective eardrums—without contact (Step S 3  of the flowchart). Contact-free measurement methods are based on lasers or ultrasound, for example. Based on the signals originating from the measurement devices  24   a ,  24   b , it is afterward possible for the control computer  17  to determine the positions of the eardrums of the ears  18   a ,  18   b  relative to the flange F of the robot R (Step S 4  of the flowchart). 
         [0042]    In the present exemplary embodiment, the control computer  17  is set up (configured) to place the tool center point TCP of the robot R at the position of one of the equilibrium organs (vestibular organs) of the ears  18   a ,  18   b  (Step S 5  of the flowchart). Based on the position of the relevant eardrum, it is enabled for the control computer  17  to accordingly conclude the position of the relevant equilibrium organ relative to the patient bed L, and thus relative to the flange F, in order to set the tool center point TCP of the robot R at the position of the relevant equilibrium organ. 
         [0043]    In the present exemplary embodiment, the control computer  17  is configured to activate the actuator  11 - 16  such that the tool center point TCP (and thus the person P lying on the patient bed L) conducts a predetermined movement. 
         [0044]    Instead of the displacement devices in the form of longitudinal rails  21   a ,  21   b  and the displacement devices  23   a ,  23   b , the fixing device  20  can be executed with a different design. An alternative embodiment of the fixing device  20  can also be such that this possesses articulated arms that, for example, comprise measurement scales and/or angle transmitters for the determination of set angles, and that this fixes the head K of the person P. The measurement scales or, respectively, in particular the measurement sensors connected with the control computer  17  allow a conclusion to be made as to the position of the openings of the auditory canals of the ears ( 18   a ,  18   b ) so that the robot R can suitably activate the axes  1 - 6  as necessary. 
         [0045]    Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventor to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of his contribution to the art.