Compensation of gravity-related displacements of medical carrier structures

1 . A computer-implemented method of determining a compensation for gravity-related displacements of a medical carrier structure having at least one adjustable joint including a joint brake to selectively immobilize the joint which respectively connects two sections of the medical carrier structure, the method comprising:

acquiring target position data which describes a target position for a predefined section of the medical carrier structure, the target position being a position at which the predefined section is intended to be held by a positional configuration of the medical carrier structure;

acquiring rest position data which describes a rest position into which the predefined section of the medical carrier structure is displaced by gravity, wherein the acquiring the rest position data comprises:

positioning the predefined section of the medical carrier structure at the target position;

applying the brake to immobilize the at least one joint; and

allowing the predefined section of the medical carrier structure to deviate from the target position into the rest position due to gravity and without any actuator effects or support from an operator;

determining deviation data based on the target position data and the rest position data, wherein the deviation data describes a spatial deviation between the target position and the rest position; and

determining prepositioning data based on the deviation data, wherein the prepositioning data describes an offset position at which the predefined section of the medical carrier structure needs to be positioned, the offset position being representative of an amount and direction of deviation of the predefined section, in order for the predefined section of the medical carrier structure to be displaced by gravity into the target position at which the predefined section is intended to be held in place by the positional configuration of the medical carrier structure.

2 . The method according to claim 1 , wherein the acquiring target position data comprises acquiring target position data after the at least one joint is immobilized, with the predefined section of the medical carrier structure being held at the target position.

3 . The method according to claim 1 , wherein the acquiring rest position data comprises acquiring rest position data after the predefined section has come to rest at the rest position.

4 . The method according to claim 1 , wherein determining prepositioning data is further based on:

the rest position data, wherein the offset position is determined based on a spatial offset from the rest position, wherein the spatial offset is calculated from the spatial deviation between the target position and the rest position; or

the target position data, wherein the offset position is determined based on a spatial offset from the target position, wherein the spatial offset is calculated from the spatial deviation between the target position and the rest position.

5 . The method according to claim 1 , further comprising:

transmitting the prepositioning data to a graphical-user-interface-(GUI)-module adapted to output instructions to a user to manually position the predefined section at the offset position; and/or

transmitting the prepositioning data to an actuator-control-module adapted to output control signals to at least one actuator to automatically position the predefined section at the offset position.

6 . The method according to claim 1 , wherein the acquiring target position data comprises acquiring target position data from a medical planning module and/or from at least one tracking system adapted to determine a spatial position of the predefined section.

7 . The method according to claim 1 , wherein the acquiring rest position data comprises acquiring rest position data from at least one tracking system adapted to determine a spatial position of the predefined section.

8 . The method according to claim 6 , wherein the target position data is acquired from the at least one tracking system, wherein the at least one tracking system is selected from the group consisting of:

an optical tracking system;

an EM-tracking system;

an ultrasound tracking system;

a position sensor tracking system;

a capacitive tracking system; and

a permanent magnetic tracking system.

9 . The method according to claim 1 , wherein:

the medical carrier structure comprises a plurality of joints, and wherein each one of the joints respectively connects two sections of the medical carrier structure;

at least one joint is a pivot joint providing a rotational degree of freedom;

at least one joint comprises a position sensor adapted to determine a relative position of the sections connected via the joint;

the predefined section is an end section of the medical carrier structure; and/or

the medical carrier structure comprises a spatially invariant base section which connects to the predefined section via the at least one joint.

10 . The method according to claim 1 , further comprising:

storing the target position and an assigned offset position in a database.

11 . The method according to claim 10 , further comprising:

acquiring target position data describing the target position for the predefined section of the medical carrier structure; and

acquiring, from the database storing at least one offset position, prepositioning data describing the offset position at which the predefined section of the medical carrier structure needs to be positioned in order for the predefined section of the medical carrier structure to be displaced by gravity into the target position with the at least one joint being immobilized and the predefined section of the medical carrier structure being free of any actuator effects or support from an operator.

12 . The method according to claim 11 , further comprising:

calculating an offset position assigned to a new target position based on at least two offset positions assigned to target positions stored in the database and proximate to an unknown target position.

13 . The method according to claim 11 , wherein offset positions determined for a plurality of medical carrier structures are stored in the database.

14 . A non-transitory computer readable storage medium storing a program comprising program instructions, that when executed on at least one processor of a computer or loaded onto the at least one processor of the computer, causes the computer to perform a method of determining a compensation for gravity-related displacements of a medical carrier structure having at least one adjustable joint including a joint brake to selectively immobilize the joint which respectively connects two sections of the medical carrier structure by:

acquiring target position data which describes a target position for a predefined section of the medical carrier structure, the target position being a position at which the predefined section is intended to be held by a positional configuration of the medical carrier structure;

acquiring rest position data which describes a rest position into which the predefined section of the medical carrier structure is displaced by gravity, wherein the acquiring the rest position data comprises:

positioning the predefined section of the medical carrier structure at the target position;

applying the brake to immobilize the at least one joint; and

allowing the predefined section of the medical carrier structure to deviate from the target position into the rest position due to gravity and without any actuator effects or support from an operator;

determining deviation data based on the target position data and the rest position data, wherein the deviation data describes a spatial deviation between the target position and the rest position; and

determining prepositioning data based on the deviation data, wherein the prepositioning data describes an offset position at which the predefined section of the medical carrier structure needs to be positioned, the offset position being representative of an amount and direction of deviation of the predefined section, in order for the predefined section of the medical carrier structure to be displaced by gravity into the target position at which the predefined section is intended to be held in place by the positional configuration of the medical carrier structure.

15 . A medical system, comprising:

at least one computer;

at least one electronic data storage device storing at least target position data; and

a medical carrier structure having at least one adjustable joint including a joint brake to selectively immobilize the joint respectively connecting two sections of the medical carrier structure,

wherein the at least one computer is operable to:

acquire, from the at least one electronic data storage device, the target position data, wherein the target position data describes a target position for a predefined section of the medical carrier structure having the at least one joint which respectively connects two sections of the medical carrier structure, the target position being a position at which the predefined section is intended to be held by a positional configuration of the medical carrier structure;

acquire rest position data which describes a rest position into which the predefined section of the medical carrier structure is displaced by gravity, wherein the acquiring the rest position data comprises:

positioning the predefined section of the medical carrier structure at the target position;

applying the brake to immobilize the at least one joint; and

allowing the predefined section of the medical carrier structure to deviate from the target position into the rest position due to gravity and without any actuator effects or support from an operator;

determine deviation data based on the target position data and the rest position data, wherein the deviation data describes a spatial deviation between the target position and the rest position;

determine prepositioning data based on the deviation data, wherein the prepositioning data describes an offset position at which the predefined section of the medical carrier structure needs to be positioned, the offset position being representative of an amount and direction of deviation of the predefined section, in order for the predefined section of the medical carrier structure to be displaced by gravity into the target position at which the predefined section is intended to be held in place by the positional configuration of the medical carrier structure; and

issue a control signal to the medical carrier structure for controlling operation of the medical carrier structure based on the target position data.

16 . The method according to claim 10 , wherein a plurality of target positions and the assigned offset positions are stored in the database.

17 . The method according to claim 12 , wherein the calculating the offset position comprises calculating the offset position assigned to the new target position via interpolation or extrapolation.

18 . The method according to claim 1 , wherein:

the allowing the predefined section of the medical carrier structure to deviate from the target position into the rest position comprises:

allowing the predefined section of the medical carrier structure to deviate from the target position into the rest position after the applying the brake to immobilize the at least one joint; and

the applying the brake to immobilize the at least one joint comprises:

applying the brake to immobilize the at least one joint after positioning the predefined section of the medical carrier structure at the target position.

19 . The non-transitory computer readable storage medium storing the program comprising program instructions according to claim 14 , wherein when the program instructions are executed on the at least one processor of the computer or loaded onto the at least one processor of the computer, cause the computer to:

allow the predefined section of the medical carrier structure to deviate from the target position into the rest position by:

allowing the predefined section of the medical carrier structure to deviate from the target position into the rest position after the applying the brake to immobilize the at least one joint; and

apply the brake to immobilize the at least one joint by:

applying the brake to immobilize the at least one joint after positioning the predefined section of the medical carrier structure at the target position.

20 . The medical system according to claim 15 , wherein the at least one computer is operable to:

allow the predefined section of the medical carrier structure to deviate from the target position into the rest position by:

allowing the predefined section of the medical carrier structure to deviate from the target position into the rest position after the applying the brake to immobilize the at least one joint; and

apply the brake to immobilize the at least one joint by:

applying the brake to immobilize the at least one joint after positioning the predefined section of the medical carrier structure at the target position.