Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Reexamination Certificate
2002-03-08
2003-11-04
Ro, Bentsu (Department: 2837)
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
C318S568100, C318S568230, C318S568140, C318S568160, C901S001000
Reexamination Certificate
active
06642686
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a swivel arm with passive actuators, in particular to be used in the field of computer-aided surgery for stereotactic applications.
DESCRIPTION OF RELATED ART
A pivoting arm is known from U.S. Pat. No. 5,820,623 which serves to support and position medical instruments. In this respect, a drive device is provided comprising a servomotor, to move a pivoting element of the arm.
A device and a method are known from U.S. Pat. No. 5,952,796 for guiding the movements of an operator, e.g. to assist a person in moving a load by using a control motor.
U.S. Pat. No. 5,704,253 discloses a device for guiding a movement along a given trajectory.
SUMMARY OF THE INVENTION
It is an object of the present invention to propose a swivel arm, a system comprising a swivel arm and a method for guiding a swivel arm, which can be used to assist in examining or treating a body.
This object is solved by the devices and methods defined in the independent claims. Advantageous embodiments follow from the sub-claims.
One end of the swivel arm in accordance with the invention can be fixed to a suitable support such as for example a table or a medical device and comprises at least one pivot and preferably a number of pivots, such that the fixed swivel arm can be moved with at least one degree of freedom, preferably with two, three, four, five or more degrees of freedom. In this respect, a pivot can enable a rotational movement or a tilting movement, such that for example a ball bearing can be used to enable a rotational movement or a hinge to enable a tilting movement. A telescopic element, for example, is also to be understood as a pivot in the sense of the invention, by means of which a movement in the axial direction of the telescopic element is possible. In general, the swivel arm is to be designed by attaching at least one pivot in such a way that a movement can be performed with at least one degree of freedom. On the at least one pivot, a sensor is provided with which the position or movement of the at least one pivot can be determined. A controllable passive actuator, for example a controllable brake, is furthermore provided on the at least one pivot in accordance with the invention, to release the movement of the swivel arm at the specific pivot, to impede and/or brake said movement, or even to render it entirely impossible, with a variable resistance force, i.e. to arrest the pivot in a particular position. In accordance with the invention, the controllable passive actuator is guided by a control device which can determine the current position of the swivel arm as a whole, in particular the position of an instrument or the tip of an instrument connected to the swivel arm, based on the sensor data of the at least one pivot sensor. In accordance with the invention, data on a target object to be examined or treated with the instrument, for example a body or part of a body, are detected, for example by CT or MRI, before or while the arm is used, and used by the control device to output control signals, determined in combination with the position of the instrument determined from the sensor signals, to the passive actuators to thus impede and/or decelerate or facilitate and/or simplify a particular movement of the swivel arm at the respective pivots.
The swivel arm in accordance with the present invention thus enables an operator to relatively simply and exactly move an instrument guided by the swivel arm with the aid of the control device to a desired position or along a given path, or also to move it within a desired range e.g. to perform a method planned before using the instrument connected to the swivel arm.
Since only passive actuators, for example controllable brake elements, are used in the individual pivots in accordance with the invention, no active element such as for example a motor is required, such that the swivel arm can be manufactured cost-effectively, comprises a simple mechanism, can be guided simply and is relatively light. Consequently, no driving element is required for the swivel arm, since the force required to move the swivel arm is applied by an operator and said movement is directed to the desired position by the swivel arm in accordance with the invention in co-operation with the control device, by employing the passive actuators in a targeted and dosed way.
Thus, an operator can for example be given a haptic feedback or a tactile feedback as to whether for example the direction of movement in which the swivel arm is moved by the operator is correct or not. To this end, a braking force applied to the pivot by the actuator can for example be increased when the operator moves the swivel arm in a direction which does not correspond-to a desired or planned direction, and the braking force can be reduced when the movement of the swivel arm by the operator is in the desired direction. The passive actuator provided on one or on each pivot in accordance with the invention can even block the respective pivot completely, if moving the swivel arm further would cause the instrument connected to the swivel arm to penetrate a sensitive area, thus for example avoiding undesired injuries or incisions.
The feedback can advantageously be designed in such a way that the force opposing a movement of the swivel arm initiated by the operator is dosed in such a way that the operator can “sense” particular areas in which for example an instrument connected to the arm is situated. Thus, based on imaging performed beforehand on a body to be treated, particular values of a resistance force can for example be assigned to particular areas or structures, such as for example veins, tendons, bones, soft tissue etc., by a processing step carried out before treatment, for example suitably segmenting the body, said resistance force being opposed for example by a movement of an instrument connected to the arm, if for example the tip of the instrument approaches or enters such an area. In this respect, different resistance values can be assigned to different structures and/or their near vicinity, such that the passive actuators of the arm oppose movements towards or through the corresponding areas, using exactly dosed braking or supporting forces. Using such a tactile feedback, an operator can “sense” in which area an instrument connected to the arm is situated, by assigning different values of movement resistance to different areas or structures.
The swivel arm and in particular each actuator is preferably designed in such a way that the force of e.g. 2 kN which may be applied by a person can be supported, i.e. an operator cannot move a pivot fixed by the actuator, not even via leverage acting on partial elements of the swivel arm.
The instrument connected to the swivel arm is preferably a medical and/or surgical instrument and is attached to a partial element of the swivel arm either directly or via an adaptor or suitable support which can be moved when the arm is attached to a supporting device. Thus, for example, a nail, a screw, an endoscope, a microscope, a biopsy needle, a cutting device such as for example a scalpel, a catheter or a catheter guide, a drill, a drilling template, a cutting block or a cutting template or the like can be used as an instrument, which can be connected to the swivel arm and moved to a desired position, along a given trajectory or in a particular area by the control device.
The invention further relates to a system comprising a swivel arm such as described above and an input device for inputting e.g. control data for the control device such as for example the type and/or dimensions of the instrument used, the type of desired method to be performed and/or data on the target object, for example the body and/or part of the body to be treated or examined, said data being obtained for example by computer topography (CT), nuclear spin resonance imaging (MRI), ultrasonic examination, positron emission topography (PET) or other suitable methods. Thus, prior to neurosurgery, the operator can, on the basis of for example three-dimensional dat
BrianLAB AG
Duda Rina I.
Renner , Otto, Boisselle & Sklar, LLP
Ro Bentsu
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