ACTUATOR FOR AN ENDOSCOPIC PROBE, ENDOSCOPIC PROBE AND METHOD FOR CONTROLLING AN ACTUATOR OF AN ENDOSCOPIC PROBE

Abstract

The invention relates to an actuator for an endoscopic probe, an endoscopic probe and a method for controlling an actuator of an endoscopic probe. The actuator is provided with an elongate shape memory wire (2) consisting of a shape memory alloy, with an electrical conductor (5) which is electrically conductively connected to the shape memory wire (2) and supplies the shape memory wire (2) with current, with a wire insulation (3) which surrounds at least some sections of the shape memory wire (2) and consists of an electrically insulating material and with a flexible sheath (4) which is pressure-resistant in the longitudinal direction of the shape memory wire (2). The shape memory wire (2) converts the electrical energy of the current flowing through said shape memory wire into thermal energy. Under the influence of this heat, the shape memory wire (2) changes its length from a first length to a second length. The sheath (4) forms a guide for the shape memory wire (2) and a counterbearing for supporting the tensile forces to be transmitted which are effective as a result of the change in shape of the shape memory wire (2).

Claims

1. An actuator for an endoscopic probe with a an elongate shape memory wire (2) comprising a shape memory alloy, with an electrical conductor (5) which is electrically conductively connected to the shape memory wire (2) and supplies the shape memory wire (2) with current, wherein the shape memory wire (2) is designed to convert the electrical energy of the current flowing through it into thermal energy and to change its length from a first length to a second length under the influence of this heat, with wire insulation (3) which surrounds at least some sections of the shape memory wire (2) and comprises an electrically insulating material, with a flexible sheath (4) which is pressure-resistant in the longitudinal direction of the shape memory wire (2), which forms a guide for the shape memory wire (2) and a counterbearing for supporting the tensile forces to be transmitted which are effective as a result of the change in shape of the shape memory wire (2), and which surrounds the wire insulation (3).

2. The actuator according to claim 1, wherein the change in length of the shape memory wire (2) under the influence of the heat that is generated by the current flowing through it is a contraction.

3. The actuator according to claim 1, wherein the wire insulation (3) forms a flexible guide tube between the shape memory wire (2) and the sheath (4).

4. The actuator according to claim 1, wherein the wire insulation (3) is made of polyamide.

5. The actuator according to claim 1, wherein the sheath (4) is formed by a strip or wire that is wound into a cylindrical spiral.

6. The actuator according to claim 5, wherein the spiral is wound out of metal.

7. The actuator according to claim 1, wherein the sheath (4) is equipped with a sheath insulation surrounding the sheath (4) which thermally insulates the sheath (4) from its surroundings.

8. The actuator according to claim 1, wherein one end of the shape memory wire (2) is mechanically fixed at a counterholder (7, 7a), and wherein the sheath (4) is also secured with its end at the counterholder (7, 7b).

9. The actuator according to claim 8, wherein the shape memory wire (2) is connected to the counter holder (7, 7a) with the electrical conductor (5).

10. The actuator according to claim 8, wherein a mechanical pull cable (23) is connected at the end of the shape memory wire (2) facing away from the counterholder (7, 7a).

11. The actuator according to claim 10, wherein the shape memory wire (2) is connected to the pull cable (23) via a sleeve (24).

12. The actuator according to claim 10, wherein at least some sections of the pull cable (23) are also surrounded by the wire insulation (3) and the sheath (4).

13. The actuator according to claim 1, wherein the shape memory wire (2) is connected at one end to the electrical conductor (5) and at the other end to a reference potential.

14. An endoscopic probe with an elongate shaft (11, 21) which has the form of a hollow body, with a proximal end of the shaft (11, 21), with a distal end of the shaft (11, 21), with a shaft head (12, 22) on the distal end of the shaft (11, 21), wherein the shaft head (12, 22) can be moved in relation to the shaft (11, 21), with the actuator (1, 1a, 1b, 1c, 1d, 1e, 1f) according to claim 1 which aligns the shaft head (12, 22) relative to the shaft (11, 21).

15. The endoscopic probe according to claim 14, wherein the actuator (1, 1a, 1b, 1c, 1d, 1e, 1f) is arranged in the shaft (11, 21).

16. The endoscopic probe according to claim 15, wherein the actuator (1, 1a, 1b, 1c, 1d, 1e, 1f) is aligned with its longitudinal axis essentially parallel to the longitudinal axis of the shaft (11, 21).

17. The endoscopic probe according to claim 14, wherein at least two actuators (1, 1a, 1b, 1c, 1d, 1e, 1f) are arranged in the shaft (11, 21) so that the shape memory wires (2) of the actuators (1, 1a, 1b, 1c, 1d, 1e, 1f) are offset from one another in the axial direction of the shaft and are free of any overlapping in the axial direction.

18. The endoscopic probe according to claim 14, wherein it is equipped with a power supply (14, 27), and wherein it is equipped with a control device (15, 28) which supplies at least one actuator (1, 1a, 1b, 1c, 1d, 1e, 1f) for moving the shaft head (12, 22) with current in such a manner that the actuator (1, 1a, 1b, 1c, 1d, 1e, 1f) deflects the shaft head (12, 22) out of a specified starting position and moves it into a specified end position, and moves the shaft head (12, 22) out of the specified end position back into its starting position.

19. The endoscopic probe according to claim 18, wherein the control device (15, 28) is designed to determine the resistance of the shape memory wire (2) of the actuator (1, 1a, 1b, 1c, 1d, 1e, 1f) or of the actuators (1, 1a, 1b, 1c, 1d, 1e, 1f) and to determine from the resistance the actual state of the deflection of the shape memory wire (2) to compare this with a specified target state of the deflection of the shape memory wire (2).

20. The endoscopic probe according to claim 14, wherein it is equipped with at least one temperature sensor (17, 18).

21. The endoscopic probe according to claim 20, wherein it is equipped with at least one first temperature sensor (17) that determines the temperature at the shape memory wire (2) of the actuator or of the actuators (1, 1a, 1b, 1c, 1d, 1e, 1f).

22. The endoscopic probe according to claim 20, wherein it is equipped with one second temperature sensor (18) that determines the ambient temperature of the shaft (11, 21) or the shaft head (12, 22).

23. The endoscopic probe according to claim 14, wherein in the shaft (11, 21) exactly one actuator (1) is arranged that moves the shaft head (12, 22) out of its starting position into its end position and that the endoscopic probe (10, 20) is additionally equipped with a spring that moves the shaft head (12, 22) from its end position back into the starting position.

24. The endoscopic probe according to claim 18, wherein it is equipped with an even number of actuators (1, 1a, 1b, 1c, 1d, 1e, 1f), of which two actuators (1, 1a, 1b, 1c, 1d, 1e, 1f) in each case form an actuator pair with a first actuator and a second actuator, wherein the two actuators (1, 1a, 1b, 1c, 1d, 1e, 1f) of an actuator pair both expand their shape memory wires (2) to a specified second length.

25. The endoscopic probe according to claim 14, wherein the shaft (11) has an oblong cross-section.

26. The endoscopic probe according to claims 14 wherein the shaft head (12) can be turned relative to the shaft (11) around a shaft head rotation axis that is aligned essentially perpendicular to the longitudinal axis of the shaft (11).

27. The endoscopic probe according to claim 26, characterised in that wherein the shaft head (12) has the form of a rotary plate.

28. The endoscopic probe according to claim 14, wherein the shape memory wire (2) of the actuator (1, 1a, 1b, 1c, 1d, 1e, 1f) is directly attached to the shaft head (12).

29. The endoscopic probe according to claim 14, wherein the shaft head (22) has several ring or tube-shaped shaft head segments (25) that can be moved relative to one another, which can be aligned by the actuator or by the actuators (1c, 1d, 1e, 1f).

30. The endoscopic probe according to claim 29, wherein the shaft head segments (25) are made of plastic.

31. The endoscopic probe according to claim 29, wherein the shaft head segments (25) have openings through which the shape memory wires (2) or pull cables (23) connected to the shape memory wires (2) of the actuators (1c, 1d, 1e, 1f) are guided.

32. A method for controlling an actuator of the endoscopic probe according to claim 14, comprising the following process steps, detection of the resistance of the shape memory wire (2) of the actuator(1, 1a, 1b, 1c, 1d, 1e, 1f), detection of the temperature at the actuator (1, 1a, 1b, 1c, 1d, 1e, 1f) or in its vicinity, monitoring of the resistance as a factor of the temperature, control of the current for the shape memory wire (2) of the actuator (1, 1a, 1b, 1c, 1d, 1e, 1f) using the temperature and/or the resistance.

Description

Drawing

[0049] Model embodiments of an actuator according to the invention and two endoscopic probes according to the invention are represented in the drawing. Illustrations:

[0050] FIG. 1 Detail from an actuator in a side view,

[0051] FIG. 2 Counterholder and electrical conductor of the actuator according to FIG. 1,

[0052] FIG. 3 First model embodiment of an endoscopic probe,

[0053] FIG. 4 Part of the shaft with shaft head of the probe according to FIG. 3,

[0054] FIG. 5 Second model embodiment of an endoscopic probe,

[0055] FIG. 6 Part of the shaft with shaft head of the probe according to FIG. 5,

[0056] FIG. 7 Probe according to FIG. 5 with a surrounding tube.

DESCRIPTION OF THE MODEL EMBODIMENTS

[0057] FIGS. 1 and 2 represent a model embodiment of an actuator 1 in a side view. Actuator 1 has a shape memory wire 2, a wire insulation 3, a sheath 4, a first electrical conductor 5 which can be connected to a voltage source (not shown) and supplies the shape memory wire 2 with current, and a second electrical conductor 6 which connects the shape memory wire 2 to the zero potential. The shape memory wire 2 is surrounded by the wire insulation 3, which in turn is surrounded by the sheath 4. The sheath 4 comprises a spring steel strip which is wound into a cylindrical spiral. The sheath 4 is only partially shown in FIG. 1. However, it actually extends from a counterholder 7 shown in FIG. 2 to the opposite end of the actuator, which is not shown in FIGS. 1 and 2. The shape memory wire 2 and sheath 4 are fixed at the counterholder 7. The shape memory wire 2 is guided through several openings of the counterholder 7 for this. The section of the counterholder 7 that has openings is displayed transparently in FIG. 2. The counterholder 7 is partially made of a conductive material. In the counterholder 7, the first electrical conductor 5 is arranged in such a way that the electrical current can flow from the first electrical conductor 5 to the shape memory wire 2. The current from the shape memory wire 2 can flow off via the second electrical conductor 6. The section of the counterholder 7 that is connected to the sheath 4 is electrically insulated against the conductive section of the counterholder 7. The counterholder 7 has a first counterholder component 7a for supporting the shape memory wire 2 and a second counterholder component for supporting the sheath 4. Both counterholder components 7a, 7b are shown in the FIGS. 3 and 5.

[0058] The end of the shape memory wire 2 facing away from the counterholder 7 which is not shown in FIGS. 1 and 2 either protrudes from the sheath 4 or the shape memory wire 2 is connected to a pull cable (not shown) inside the wire insulation 3 and the sheath 4 and this pull cable protrudes from the sheath 4. The part protruding from the sheath is connected with a movable shaft head of the endoscopic probe. Model embodiments are shown in the FIGS. 3 to 7.

[0059] If an electrical current flows through the shape memory wire 2 which is fed through the first electrical conductor 5 and conducted away by the second electrical conductor, the shape memory wire 2 heats up. As a result of this heating, the shape memory alloy of the shape memory wire undergoes a shape change based on a temperature-dependent lattice transformation to one of the two crystal structures of the shape memory alloy. This leads to the length of the shape memory wire being shortened. Because the one end of the shape memory wire 2 is fixed at the counterholder 7 and the sheath 4 is also secured at the counterholder 7 and retains its axial length, the end of the shape memory wire 2 facing away from the counterholder moves relative to the sheath 4. This movement is transferred to a shaft head. A tensile force then acts on the shaft head.

[0060] FIGS. 3 and 4 represent a first model embodiment of an endoscopic probe 10. The probe 10 comprises an elongate shaft 11 and a shaft head 12 that can be moved relative to the shaft 11. The shaft 11 is connected via a cable 13 with a housing which contains a power supply 14 and a control device 15. The shaft 11 has a rectangular cross-section so that it takes the form of a blade or lance. The surface of the shaft 11 facing the viewer in FIGS. 3 and 4 is larger than the surface of the shaft 11 aligned perpendicular to this. The shaft head 12 takes the form of a rotary plate. The rotation axis of this rotary plate runs perpendicular to the drawing plane in FIGS. 3 and 4 and thus perpendicular to the longitudinal axis of the shaft 11. Two actuators 1a, 1b are arranged in the shaft 11 which line up with the actuator according to FIGS. 1 and 2. The corresponding reference numbers are thus used for the individual components of the actuators in FIGS. 3 and 4 as were used in FIGS. 1 and 2. The shape memory wire 2 of the two actuators 1a, 1b protrudes from the sheath 4 with its side facing away from the counterholder 7. The counterholder 7 has a first counterholder component 7a in which the shape memory wire 2 is fixed with one end. In the first counterholder component 7a, the first electrical conductor 5 is also housed such that the first electrical conductor is electrically conductively connected to the shape memory wire. Furthermore, the counterholder 7 also has a second counterholder component 7b in which one end of the sheath 4 is fixed. Both counterholder components 7a and 7b are designed such that the sheath 4 is electrically insulated against the first electrical conductor 5 and the shape memory wire 2.

[0061] The distal end of the shape memory wire 2 facing away from the counterholder 7 is guided around a section of the outside of the shaft head 12 in the form of a rotary plate and secured at the shaft head 12 by means of a screw 16. Heating of the shape memory wire of the actuator 1a thus leads to a clockwise rotation of the shaft head. Heating of the shape memory wire of the actuator 1b leads to an anticlockwise rotation of the shaft head. Both rotation directions are shown by arrows in FIG. 3. Using a first temperature sensor 17 and a second temperature sensor 18, the temperature is recorded at the shaft head 12 and at the shaft 11 and output to the control device 15. Both temperature sensors are connected to the control device 15 for this purpose. The control device takes into account the recorded temperature when specifying the current with which the actuators are supplied.

[0062] A camera 19 is arranged on the shaft head 12.

[0063] FIGS. 5, 6 and 7 represent a second model embodiment of an endoscopic probe 20. FIG. 5 shows the probe 20 in various views. The probe 20 has an elongate shaft 21 and a shaft head 22. The shaft is equipped with a total of four actuators 1c, 1d, 1e, 1f which line up with the actuator according to FIGS. 1 and 2. The actuators are arranged in the shaft 21 in the axial direction in such a manner that the shape memory wires do not overlap in the axial direction. They are offset relative to each other. This is shown in the upper part of FIG. 5. The axial length of the actuators 1c, 1d, 1e, 1f differs. The actuator 1c has the shortest length in the axial direction and the actuator 1f has the longest. At the distal ends, the shape memory wires 2 are connected with pull cables 23 via a sleeve 24. This is shown in a detail of actuator 1c. The shaft head has several ring-shaped shaft head segments 25. Two actuators 1c, 1d and 1e, 1f each form an actuator pair. In an actuator pair, the movements of the respective actuator are compensated by the movement of the respective other actuator so that the shaft head 22 returns to its starting position.

[0064] The ring-shaped shaft head segments 25 are equipped with several openings through which the pull cables 23 are guided. A movement of the actuators 1c, 1d, 1e, 1f leads to the shaft head segments 25 being aligned relative to one another.

[0065] FIG. 7 shows the endoscopic probe according to FIGS. 5 and 6 with a tube 26 which surrounds the entire probe 20 and with a combined power supply 27 and control device 28. The probe has a considerable axial length here. A camera 29 or 30 can be connected on the shaft head 22.

[0066] All features can be material to the invention both individually and in any combination.

REFERENCE NUMBERS

[0067] 1 Actuator [0068] 1a Actuator [0069] 1b Actuator [0070] 1c Actuator [0071] 1d Actuator [0072] 1e Actuator [0073] 1f Actuator [0074] 2 Shape memory wire [0075] 3 Wire insulation [0076] 4 Sheath [0077] 5 First electrical conductor [0078] 6 Second electrical conductor [0079] 7 Counterholder [0080] 7a First counterholder component [0081] 7b Second counterholder component [0082] 8 [0083] 9 [0084] 10 Endoscopic probe [0085] 11 Shaft [0086] 12 Shaft head [0087] 13 Cable [0088] 14 Power supply [0089] 15 Control device [0090] 16 Screw [0091] 17 First temperature sensor [0092] 18 Second temperature sensor [0093] 19 Camera [0094] 20 Endoscopic probe [0095] 21 Shaft [0096] 22 Shaft head [0097] 23 Pull cable [0098] 24 Sleeve [0099] 25 Shaft head segment [0100] 26 Tube [0101] 27 Power supply [0102] 28 Control device [0103] 29 Camera [0104] 30 Camera