LIN WU ET AL.: 'Modelling and Experiments of Input-Output Displacement Relations for a Piezoelectric Nanopositioner' PROCEEDINGS OF THE 2004 INTERNATIONAL CONFERENCE ON MEMS, NANO AND SMART SYSTEMS (ICMENS 2004) 25 August 2004, pages 453 - 460
We claim:
1. A method of discontinuous motion for long range displacement of objects using flexural cam with actuator ram incorporating nanopositioner, said method comprising steps of: a. placing the object onto a moving stage (2); b. expanding second actuator (4) to its half the range keeping first actuator (3) at zero expansion to cause first cam (cl) to grip the stage (2) while second cam (c2) and third cam (c3) have no hold of the stage (2); c. activating the actuator (3) to its full range of expansion to bring block (1) in contact with the stage causing cl to loose its hold over the stage (2); d. driving the stage for a predetermined distance (2) using the block (1) to result in displacement of the stage (2) to make tip of the cam (c3) to come in contact with the stage (2); e. contracting the block (1) to bring cam (c2) in contact with the stage (2) and thereafter clenching the stage by cam (c2) to cause the actuator (3) not to expand further; and f. releasing the cam (c2) to bring the actuator (3) to its original state without disturbing the stage which is already moved forward and continuously holding the stage using the cam (c3) to obtain long range displacement.
2. The method as claimed in claim 1, wherein the stage does not go back due to the spring force.
3. A device for long range displacement of objects using flexural cam with actuator ram incorporating nanopositioner, said device comprises a. moving stage (2) to hold the objects; b. actuator (3) for driving the stage (2) forward or backward and another actuator (4) for holding the stage against spring force when actuator (3) has idle motion or not driving the stage (2); and c. cams (cl, c2, c3) to clench the stages for different time periods at various stages.
4. The device as claimed in claim 3, wherein the cams (cl, c2, c3) rotate around the fulcrums to have grip.
5. The device as claimed in claim 3, wherein the flexures above the cams (cl, c2, c3) moves up and holds the moving stage (2).
6. The device as claimed in claim 3, wherein the stage (2) is either monolithic flexible compliance linear spring or monolithic flexural linear spring.
7. A method of discontinuous motion for long range displacement of objects using actuators along with spring pusher incorporating nanopositioner, said method comprising steps of: a. placing the object onto a moving stage (12); b. expanding shear actuator (13) completely by predetermined distance to bring it in contact with the moving stage (12) causing horizontal movement of the moving stage while keeping holder actuator (4) at initial position; c. expanding the holder actuator (14) to lift spring (11) causing the shear actuator (13) to disengage and thereby hold movement of the moving stage
(12); d. holding the spring (15) continuously with the holder actuator (14) till the shear actuator (13) returns to its original state without touching the moving stage (12); and e. causing the spring pusher to come in contact with the shear actuator by contracting the holder actuator (14) due to spring action and thereby obtaining long range displacement of objects.
8. The method as claimed in claim 7, wherein the initial position of the holder actuator (14) and shear actuator (13) are at zero expansion.
9. A device for long range displacement of objects using actuators along with spring pusher incorporating nanopositioner, said device comprises: a. moving stage (12) to hold the object; b. shear actuator (13) to move the moving stage(12); c. holder actuator (14) to lift spring pusher (15) and to hold the moving stage (12); wherein the actuators (13, 14) are mounted at the base (15); and d. holder (11) to maintain the moving stage(12) in single axis direction
10. The device as claimed in claim 9, wherein the shear actuator (13) and the holder actuator (14) are placed next to each other and are having predetermined distance between them.
11. The device as claimed in claim 9, wherein the holder (11) moves the moving stage
(12) in single axis preventing sway and crosstalk motion.
12. The device as claimed in claim 9, wherein the actuators (13, 14) are solid state actuator(s) preferably piezo crystals.
13. The device as claimed in claim 9, wherein the holder (11) is spring.
14. The device as claimed in claim 9, wherein the device is a monolithic or non- monolithic structure.
15. The device as claimed in claim 9, wherein the stage (12) is either monolithic flexible compliance linear spring or monolithic flexural linear spring.
16. A method of discontinuous motion for long range displacement of objects using actuators incorporating nanopositioner, said method comprising steps of: a. placing the object onto a moving stage (22) wherein the actuators (23, 24, 25) are at zero expansion; b. lifting shear actuator (23) vertically by expanding linear actuator (24) placed below the shear actuator (23) to bring it in contact with the moving stage(22); c. moving the stage (22) horizontally in a single axis forward direction by expanding the shear actuator (23); d. holding the stage (22) by expanding the holder actuator (25) to make shear actuator (23) loose contact with the stage (22) and thereby resulting into no further movement of the stage (22); and e. holding the stage (22) firmly till the linear actuator (24) contracts and the shear actuator (23) return to its initial stage and thereby obtaining long range displacement of objects.
17. A device for long range displacement of objects using actuators incorporating nanopositioner, said device comprises a. moving stage (22) to hold the object; b. shear actuator(3) to move the moving stage(22), c. linear actuator (24) to lift the shear actuator (23) to come in contact with the moving stage (22); d. holder actuator (25) to hold the moving stage firmly when the linear actuator contracts and the shear actuator return to its initial stage; and e. holder (21) to maintain the moving stage (22) in single axis direction.
18. The device as claimed in claim 17, wherein the shear actuator (23) is stacked above the linear actuator (24).
19. The device as claimed in claim 17, wherein the holder (21) moves the moving stage (22) in single axis preventing sway and crosstalk motion.
20. The device as claimed in claim 17, wherein the actuators (23, 24, 25) are solid state actuator(s) preferably piezo crystals.
21. The device as claimed in claim 17, wherein the holder (21) is spring.
22. The device as claimed in claim 17, wherein the device is a monolithic or non monolithic structure.
23. The device as claimed in claim 17, wherein the stage (22) is either monolithic flexible compliance linear spring or monolithic flexural linear spring.
24. A continuous motion method for long range displacement of objects using actuators incorporating nanopositioner, said method comprising steps of: a. placing the object onto a moving stage (32) wherein the actuators (33, 34, 35, 36) are at zero expansion; b. lifting shear actuator (33) vertically by expanding linear actuator (34) placed below the shear actuator (33) to bring it in contact with the moving stage (32) and in the mean time expanding another shear actuator (36) without lifting it by another linear actuator (35) placed above the actuator (35); c. moving the stage (32) horizontally in a single axis forward direction by expanding the shear actuator (33) and at the same time keeping the linear actuator (35) at zero expansion; d. lifting the expanded shear actuator (36) by expanding the linear actuator (35) to bring it in contact with the stage (32) and thereafter releasing the shear actuator (33) by contracting the linear actuator (34) without touching the moving stage (32); e. moving the stage (32) by shear actuator (36) by keeping the shear actuator (33) and linear actuator (34) in non contact state with the stage (32); and f. releasing the shear actuator (36) to its original state by contracting the linear actuator (35) to obtain long range displacement of objects.
25. A device for long range displacement of objects using actuators incorporating nanopositioner, said device comprises a. a. moving stage (32) to hold the object; b. shear actuator(33) to move the moving stage(32) and linear actuator (34) to lift the shear actuator (33) to come in contact with the moving stage (32); c. shear actuator(36) to move the moving stage (32) and another linear actuator (5) to lift the shear actuator (36) to come in contact with the moving stage (32); and d. holder (31) to maintain the moving stage (32) in single axis direction.
26. The device as claimed in claim 25, wherein the shear actuators (33 & 36) are stacked above the linear actuators (34 & 35) respectively.
27. The device as claimed in claim 25, wherein the holder (or spring) (31) moves the moving stage (32) in one axis preventing sway and crosstalk motion.
28. The device as claimed in claim 25, wherein the actuators (33, 34, 35, 36) are solid state actuator(s) preferably piezo crystals.
29. The device as claimed in claim 25, wherein the holder (31) is spring.
30. The device as claimed in claim 25, wherein the device is a monolithic or non monolithic structure.
31. The device as claimed in claim 25, wherein the stage (32) is either monolithic flexible compliance linear spring or monolithic flexural linear spring.
32. A system for nanopositioning of objects comprising the device of claims 3, 9, 17, 25 and a circuit to drive the actuators. |
NANOPOSITIONING DEVICES FOR LONG RANGE DISPLACEMENT OBJECTS AND METHODS THEREOF
FILED OF THE INVENTION The present invention is related to the flexural cam (6) with actuator ram, incorporated Nanopositioner for long range displacement with short range actuator. Since actuators have limitation in displacement up to their maximum possible range, Flexural Cam (6) for Actuator Ram (FlexCAR) (5) is useful in achieving long range displacement.
BACKGROUND OF THE INVENTION AND PRIOR ART
Positioning objects such as lenses, fibers, tools, sensors etc., with respect to the nanometer resolution is a challenging one. With the advent of the technology in various fields such as photonics, optics, semiconductor, microscopy etc., the requirement for precise positioning with nanometer resolution is inevitable.
Many positioning applications require larger displacement with a nanometer resolution.
The one of the ways to achieve this is to use actuators of larger displacement. Apart from this, an Inchworm is one of the technology with which one can move for larger displacement with number of actuators. These solutions become expensive one since the actuator increases the cost of the equipment. An inchworm requires al least four to five actuators and complex control systems with intelligent algorithm. Just by using two actuators one for displacement and the other for grip control, we can achieve larger displacement with a normal control systems and less complicated software algorithm. Here the displacement is limited by the flexural stage designs i.e. the flexure design limit set the displacement range; not the. actuator expansion range.
The paper titled "Development of a "Walking Drive" Ultraprecision Positioner" by Eiji Shamoto and Toshimichi Morikawi, Precision Engineering, 20, pp 85-927, 1997, discusses about the inchworm technology and the authors have used up to 12 actuators.
OBJECTS OF THE INVENTION
The primary objective of the present invention is to develop an actuator engine for nanopositioners for longer range displacement.
Yet another object of the present invention is to provide a method of discontinuous motion for long range displacement of objects using flexural cam (6) with actuator ram incorporating nanopositioner and device thereof.
Still another object of the present invention is to provide a method of discontinuous motion for long range displacement of objects using two actuators (13 and 14) along with spring pusher (15) (15) incorporating nanopositioner and device thereof. Still another object of the present invention is to provide a method of discontinuous motion for long range displacement of objects using three actuators (23, 24 and 25) incorporating nanopositioner and device thereof. Still another object of the present invention is to provide a continuous motion method for long range displacement of objects using four actuators (33, 34, 35, and 36) incorporating nanopositioner and device thereof.
Still another object of the present invention is to provide a system to achieve aforementioned objectives.
STATEMENT OF INVENTION
Accordingly, the present invention provides for a method of discontinuous motion for long range displacement of objects using flexural cam with actuator ram incorporating nanopositioner, said method comprising steps of placing the object onto a moving stage (2); expanding second actuator (4) to its half the range keeping first actuator (3) at zero expansion to cause first cam (cl) to grip the stage (2) while second cam (c2) and third cam (c3) have no hold of the stage (2); activating the actuator (3) to its full range of expansion to bring block (1) in contact with the stage causing cl to loose its hold over the stage (2); driving the stage for a predetermined distance (2) using the block (1) to result in displacement of the stage (2) to make tip of the cam (c3) to come in contact with the stage (2); contracting the block (1) to bring cam (c2) in contact with the stage (2) and thereafter clenching the stage by cam (c2) to cause the actuator (3) not to expand further; and releasing the cam (c2) to bring the actuator (3) to its original state without disturbing the stage which is already moved forward and continuously holding the stage using the cam (c3) to obtain long range displacement, and a device for long range displacement of objects using flexural cam with actuator ram incorporating nanopositioner, said device comprises moving stage (2) to hold the objects; actuator (3) for driving the stage (2) forward or backward and another actuator (4) for holding the
stage against spring force when actuator (3) has idle motion or not driving the stage (2); and cams (cl, c2, c3) to clench the stages for different time periods at various stages, and a method of discontinuous motion for long range displacement of objects using actuators along with spring pusher (15) incorporating nanopositioner, said method comprising steps of placing the object onto a moving stage (12); expanding shear actuator (13) completely by predetermined distance to bring it in contact with the moving stage (12) causing horizontal movement of the moving stage (2) while keeping holder actuator (14) at initial position; expanding the holder actuator (14) to lift spring (1 1) causing the shear actuator (13) to disengage and thereby hold movement of the moving stage (12); holding the spring (15) continuously with the holder actuator (14) till the shear actuator (13) returns to its original state without touching the moving stage (12); and causing the spring pusher (15) to come in contact with the shear actuator (13) by contracting the holder actuator (14) due to spring action and thereby obtaining long range displacement of objects and A device for long range displacement of objects using actuators along with spring pusher (15) incorporating nanopositioner, said device comprises moving stage (2), (12) to hold the object; shear actuator (13) (13) to move the moving stage (12); holder actuator (14) to lift spring pusher (15) and to hold the moving stage (12); wherein the actuators (13, 14) are mounted at the base (16); and holder/spring (11) to maintain the moving stage (12) in single axis direction, and a method of discontinuous motion for long range displacement of objects using actuators incorporating nanopositioner, said method comprising steps of placing the object onto a moving stage (22) wherein the actuators (23, 24, 25) are at zero expansion; lifting shear actuator (23) vertically by expanding linear actuator (24) placed below the shear actuator (23) to bring it in contact with the moving stage (22); moving the stage (22) horizontally in a single axis forward direction by expanding the shear actuator (23); holding the stage (22) by expanding the holder actuator (25) to make shear actuator (23) loose contact with the stage (22) and thereby resulting into no further movement of the stage (22); and holding the stage (22) firmly till the linear actuator (24) contracts and the shear actuator (23) return to its initial stage and thereby obtaining long range displacement of objects, and a device for long range displacement of objects using actuators a incorporating nanopositioner, said device comprises moving stage (22) to hold the object; shear actuator (23) to move the moving stage
(22), linear actuator (24) to lift the shear actuator (23) to come in contact with the moving stage (22); holder actuator (25) to hold the moving stage (22) firmly when the linear actuator (24) contracts and the shear actuator (23) return to its initial stage; and holder (21) to maintain the moving stage (22) in single axis direction, and also a continuous motion method for long range displacement of objects using actuators incorporating nanopositioner, said method comprising steps of placing the object onto a moving stage (32) wherein the actuators (33, 34, 35, 36) are at zero expansion; lifting shear actuator (33) vertically by expanding linear actuator (34) placed below the shear actuator (33) to bring it in contact with the moving stage (32) and in the mean time expanding another shear actuator (36) without lifting it by another linear actuator (35) placed above the actuator (35); moving the stage (32) horizontally in a single axis forward direction by expanding the shear actuator (33) and at the same time keeping the linear actuator (35) at zero expansion; lifting the expanded shear actuator (36) by expanding the linear actuator (35) to bring it in contact with the stage (32) and thereafter releasing the shear actuator (33) by contracting the linear actuator (34) without touching the moving stage (32); moving the stage (32) by shear actuator (36) by keeping the shear actuator (33) and linear actuator (34) in non contact state with the stage (32); and releasing the shear actuator (36) to its original state by contracting the linear actuator (35) to obtain long range displacement of objects and a device for long range displacement of objects using actuators incorporating nanopositioner, said device comprises a. moving stage (32) to hold the object; shear actuator (33) to move the moving stage (32) and linear actuator (34) to lift the shear actuator (33) to come in contact with the moving stage (32); shear actuator (36) to move the moving stage (32) and another linear actuator (35) to lift the shear actuator (36) to come in contact with the moving stage (32); and holder (31) to maintain the moving stage (32) in single axis direction.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Figure 1 shows nanopositioner assembly showing the various parts of the assembly showing their positioners.
Figure 2 shows actual fabrication of nanopositioner used for discontinuous motion with two actuators.
Figures 2A to 2E shows conceptual representation and working principle of discontinuous motion with two actuators.
Figure 3 shows actual fabrication of nanopositioner used for discontinuous motion with three actuators. Figures 3A to 3F shows conceptual representation and working principle of discontinuous motion with three actuators.
Figure 4 shows actual fabrication of nanopositioner used for continuous motion with four actuators.
Figure 5 shows block diagram of the figure 4. Figures 5A to 5E shows conceptual representation and working principle of continuous motion with four actuators.
DETAILED DESCRIPTION OF THE INVENTION
The primary embodiment of the present invention is a method of discontinuous motion for long range displacement of objects using flexural cam with actuator ram incorporating nanopositioner, said method comprising steps of placing the object onto a moving stage (2); expanding second actuator (4) to its half the range keeping first actuator (3) at zero expansion to cause first cam (cl) to grip the stage (2) while second cam (c2) and third cam (c3) have no hold of the stage (2); activating the actuator (3) to its full range of expansion to bring block (1) in contact with the stage causing cl to loose its hold over the stage (2); driving the stage for a predetermined distance (2) using the block (1) to result in displacement of the stage (2) to make tip of the cam (c3) to come in contact with the stage (2); contracting the block (1) to bring cam (c2) in contact with the stage (2) and thereafter clenching the stage by cam (c2) to cause the actuator (3) not to expand further; and releasing the cam (c2) to bring the actuator (3) to its original state without disturbing the stage which is already moved forward and continuously holding the stage using the cam (c3) to obtain long range displacement.
In yet another embodiment of the present invention, the stage does not go back due to the spring force.
In still another embodiment of the present invention is a device for long range displacement of objects using flexural cam with actuator ram incorporating nanopositioner, said device comprises moving stage (2) to hold the objects; actuator (3)
for driving the stage (2) forward or backward and another actuator (4) for holding the stage against spring force when actuator (3) has idle motion or not driving the stage (2); and cams (cl, c2, c3) to clench the stages for different time periods at various stages.
In still another embodiment of the present invention, the cams (cl, c2, c3) rotate around the fulcrum s to have grip.
In still another embodiment of the present invention, the flexure above the cams (cl, c2, c3) move up and holds the moving stage (2).
In still another embodiment of the present invention, the stage (2) is either monolithic flexible compliance linear spring or monolithic flexural linear spring.
In still another embodiment of the present invention is a method of discontinuous motion for long range displacement of objects using actuators along with spring pusher
(15) incorporating nanopositioner, said method comprising steps of: placing the object onto a moving stage (12); expanding shear actuator (13) completely by predetermined distance to bring it in contact with the moving stage (12) causing horizontal movement of the moving stage (2) while keeping holder actuator (13)(4) at initial position; expanding the holder actuator (14) to lift spring (11) causing the shear actuator (13) to disengage and thereby hold movement of the moving stage (12); holding the spring
(15) continuously with the holder actuator (14) till the shear actuator (13) returns to its original state without touching the moving stage (12); and causing the spring pusher
(15) to come in contact with the shear actuator (13) by contracting the holder actuator (14) due to spring action and thereby obtaining long range displacement of objects.
In still another embodiment of the present invention, the initial position of the holder actuator (14) and shear actuator (13) are at zero expansion.
In still another embodiment of the present invention is a device for long range displacement of objects using actuators along with spring pusher (15) incorporating nanopositioner, said device comprises moving stage (12) to hold the object; shear actuator (13) to move the moving stage (2)(12); holder actuator (14) to lift spring pusher (15) and to hold the moving stage (12); wherein the actuators (13, 14) are
mounted at the base (16); and holder (11) to maintain the moving stage (12) in single axis direction
In still another embodiment of the present invention, the shear actuator (13) and the holder actuator (14) are placed next to each other and are having predetermined distance between them.
In still another embodiment of the present invention, the holder (11) moves the moving stage (12) in single axis preventing sway and crosstalk motion.
In still another embodiment of the present invention, the actuators (13, 14) are solid state actuator(s) preferably piezo crystals.
In still another embodiment of the present invention, the holder (11) is spring.
In still another embodiment of the present invention, the device is a monolithic or non- monolithic structure.
In still another embodiment of the present invention, the stage (12) is either monolithic flexible compliance linear spring or monolithic flexural linear spring.
In still another embodiment of the present invention is a method of discontinuous motion for long range displacement of objects using actuators incorporating nanopositioner, said method comprising steps of placing the object onto a moving stage (22) wherein the actuators (23, 24, 25) are at zero expansion; lifting shear actuator (23) vertically by expanding linear actuator (24) placed below the shear actuator (23) to bring it in contact with the moving stage (22); moving the stage (22) horizontally in a single axis forward direction by expanding the shear actuator (23); holding the stage (22) by expanding the holder actuator (25) to make shear actuator (23) loose contact with the stage (22) and thereby resulting into no further movement of the stage (22); and holding the stage (22) firmly till the linear actuator (24) contracts and the shear actuator (23) return to its initial stage and thereby obtaining long range displacement of objects.
In still another embodiment of the present invention is a device for long range displacement of objects using actuators incorporating nanopositioner, said device comprises moving stage 22) to hold the object; shear actuator (23) to move the moving stage (22), linear actuator (24) to lift the shear actuator (23) to come in contact with the moving stage (22); holder actuator (25) to hold the moving stage (22) firmly when the linear actuator (24) contracts and the shear actuator (23) return to its initial stage; and holder (21) to maintain the moving stage (22) in single axis direction.
In still another embodiment of the present invention, the shear actuator (23) is stacked above the linear actuator (24).
In still another embodiment of the present invention, the holder (21) moves the moving stage (22) in single axis preventing sway and crosstalk motion.
In still another embodiment of the present invention, the actuators (23, 24, 25) are solid state actuator(s) preferably piezo crystals.
In still another embodiment of the present invention, the holder (21) is spring.
In still another embodiment of the present invention, the device is a monolithic or non monolithic structure.
In still another embodiment of the present invention, the stage (22) is either monolithic flexible compliance linear spring or monolithic flexural linear spring.
In still another embodiment of the present invention a continuous motion method for long range displacement of objects using actuators incorporating nanopositioner, said method comprising steps of placing the object onto a moving stage (32) wherein the actuators (33, 34, 35, 36) are at zero expansion; lifting shear actuator (33) vertically by expanding linear actuator (34) placed below the shear actuator (33) to bring it in contact with the moving stage (32) and in the mean time expanding another shear actuator (36) without lifting it by another linear actuator (35) placed above the actuator (35); moving the stage (32) horizontally in a single axis forward direction by expanding the shear actuator (13) (33) and at the same time keeping the linear actuator (35) at zero expansion; lifting the expanded shear actuator (36) by expanding the linear actuator
(35) to bring it in contact with the stage (32) and thereafter releasing the shear actuator
(33) by contracting the linear actuator (34) without touching the moving stage (32); moving the stage (32) by shear actuator (36) by keeping the shear actuator (33) and linear actuator (34) in non contact state with the stage (32); and releasing the shear actuator (36) to its original state by contracting the linear actuator (35) to obtain long range displacement of objects.
In still another embodiment of the present invention is a device for long range displacement of objects using actuators incorporating nanopositioner, said device comprises a. moving stage (32) to hold the object; shear actuator (33) to move the moving stage (32) and linear actuator (34) to lift the shear actuator (33) to come in contact with the moving stage (32); shear actuator (36) to move the moving stage (32) and another linear actuator (35) to lift the shear actuator (36) to come in contact with the moving stage (32); and holder (31) to maintain the moving stage (32) in single axis direction.
In still another embodiment of the present invention, the shear actuators (33 & 36) are stacked above the linear actuators (34 & 35) respectively.
In still another embodiment of the present invention, the holder (or spring) (31) moves the moving stage 1 (32) in one axis preventing sway and crosstalk motion.
In still another embodiment of the present invention, the actuators (33, 34, 35, 36) are solid state actuator(s) preferably piezo crystals.
In still another embodiment of the present invention, the holder (31) is spring.
In still another embodiment of the present invention, the device is a monolithic or non monolithic structure.
In still another embodiment of the present invention, the stage (32) is either monolithic flexible compliance linear spring or monolithic flexural linear spring.
In still another embodiment of the present invention is a system for nanopositioning of objects comprising the device of claims 3, 9, 17, 25 and a circuit to drive the actuators.
The primary objective of the present invention is to develop an actuator engine for nanopositioners for longer range. The novelty of this invention is to obtain longer range displacement with two, three and four small range actuators. Unlike the differential stiffness, here the spring and actuator stiffness can be designed to applications and the stiffness of the stage and actuator, are not needed to be unequal.
This invention will be useful in various field of astronomy, data storage, medical, metrology, micro machining, microscopy, photonics, precision machining, semiconductors etc.
Instead of using an expensive long range actuator, flexural concepts can be applied with just two, three and four actuators in order to move the stage for larger distance.
a) Discontinuous Motion with Two Actuators and Three Cams
One of the two actuators (3 & 4) is used to move the stage during forward (or reverse) direction while the other is used to hold the stage at a particular position till the driving actuator (3) goes to the reverse (or forward) end. A software algorithm is used in the electronics drive to control this system during forward and reverse direction. The present invention shall now be fully described with reference to the accompanying drawings in which, Figure 1 is a nanopositioner assembly showing the various parts of the assembly showing their positioners.
This FlexCAR (5) uses two actuators namely Al (3) and A2 (4). Al (3) is used for driving the stage (2) forward or backward and A2 (4) is used for holding the stage (2) against the spring force when Al (3) has idle motion or not driving the stage (2). A2 (4) is expanded for half of its full expansion range. The cams Cl, C2, C3 are to clench the stage (2) for different time period at the various stages. The following table describes the forward displacement. When these cams rotate about the fulcrums to have grip, the flexures above the cams move up and holds the moving stage (2).
FORWARD MOTION ALGORITHM
T - Touch, NT - No Touch, TP - Tip Touch.
At first in mode A, the Al (3) actuator has no expansion and A2 (4) actuator is expanded to its half the range and hence Cl is gripping the stage while C2 and C3 have no hold of it. In mode B, the Al (3) is activated, and when it reaches 1 micron expansion, CAM - Cl is designed to hold the stage while CAM - C2 and CAM - C3 still do not hold the stage. Now CAM - Cl holds the stage with it's the tip of the edge, from where a slight move forward will lose contact from the stage. In mode C, the A2 (4) actuator is activated to its full range of expansion, which results in prime mover or block coming to contact with the stage. At this juncture, CAM - Cl also loses its hold on the stage. The prime mover drives the stage along with it for 3 micron (if the total range of Piezo is 5 micron). Now CAM - C3 tip come into contact with the moving stage (2). When the prime mover or block (1) travels by 3 micron, mode D Begins. In mode D, CAM - C2 come into contact with the stage (2) with its tip while the prime mover (1) contracts (or deactivated) with 0 voltages. At this point CAM - C2 clenches the stage (2) well once the contraction of the actuator is completed. Now the Actuator Al (3) cannot expand ahead as it reaches its full range. Now it is time for actuator Al (3) to go back to the original state without disturbing the stage (2) which is already moved forward. The mode E initiates this process by releasing CAM - C2 at the end of this process. As CAM - C3 is constantly holds the stage till a new cycle begins; the stage will not go back due to the spring force. In the end of the mode F & G, CAM -
Cl comes into complete contact with the stage (2). Now the same cycle repeats till the required target is arrived.
The same algorithm is followed with little change in case of reverse motion. The software controlled electronics switches to the reverse mode in this case before continuing the operation.
REVERSE MOTION ALGORITHM
T - Touch, NT - No Touch, TP — Tip Touch. YES' denotes reverse motion.
At first in mode P, the Al (3) actuator is set to full expansion while A2 (4) actuator has half expansion and hence C3 is gripping the stage while Cl and C2 have no hold of it. In mode Q, the Al (3) is contracted, and when it lessens by 1 micron, CAM - C3 is designed to hold the stage while CAM - Cl and CAM - C2 still do not hold the stage. Now CAM - C2 holds the stage with it's the tip of the edge, from where a slight move backward will lose contact from the stage. In mode R, the A2 (4) actuator is activated which results in prime mover or block (1) coming to contact with the stage (2) releasing CAM - C3 from the hold. At this juncture, CAM - C3 also loses it hold on the stage (2). The prime mover (1) drives the stage (2) along with it for 3 micron in reverse direction (if the total range of Piezo is 5 micron). When the prime mover (1) travels by 3 micron, mode S begins. In mode S, CAM - Cl come into contact with the stage (2) with its tip while the prime mover (1) contracts (or deactivated). At this point CAM - C2 clenches the stage (2) well once the contraction of the actuator is completed. Now
the Actuator Al (3) cannot contract below as it reaches its full range. Now it is time for actuator Al (3) to go forward to the start the similar process in mode P without disturbing the stage (2) which is already moved back. The mode T initiates this process by releasing CAM - Cl at the end of this process. As CAM - C2 is constantly holds the stage (2) till a new cycle begins; the stage (2) will not go back due to the spring force. In the end of the mode U & V, CAM - C2 comes into complete contact with the stage (2). Now the same cycle repeats till the required target is arrived.
Advantages: Just by using couple of actuators we can achieve the same displacement. The use of flexural cam is the one which was not used by other authors or inventors.
Disadvantage: The displacement is not continuous and this discontinuity can be ignored by using high stiff fast actuator.
Advantages of the Invention
• The expensive actuator, inchworm, and its complex algorithm can be avoided.
• Larger displacement with just two actuator
• Entire systems forms a monolithic structure and hence manufacturing ' process is relatively simple.
b) Discontinuous Motion with Two Actuators and spring pusher
If the light weight is to be placed for pick and place or discontinuous motion, then this design is suitable. This design uses two actuators only. The holder actuator (14) and shear actuator (13) are used for displacement and holding purpose. The actuators are mounted at base (16) of the nanopositioner which can move up and down. Spring pusher (15) is shown in green color and dotted circle.
Stage Design:
The stage is monolithic flexible compliance linear spring, stiffness can be calculated as λs = (12EI) / L 3 Where
I = Second Moment of Inertia
E = Young's Modulus L = Column Length
The figure 2 shows the actual fabrication of the Nanopositioner. The material is stainless steel with the following specifications:
The maximum displacement of the flexible compliance stage can be calculated as y = F
* L 3 / 12EI
With the above specifications, the nanopositioner can produce displacement up to 1000 mircon (1 mm) and the stiffness is 9.5157E-07 kN/micron. The dynamic analysis shows that the natural frequency of the stage is 0.21991612 Hz.
Actuator Design
The actuator stiffness should be more than that of the stiffness of the stage.
The stiffness of the actuator is 0.003070446 kN / micron which is more than the value of stage.
Working Principle The conceptual representations is given in figures 2A to 2E.
Step 1: Moving stage (12) is at initial state. Shear and linear actuator (13 and 14) are at zero expansion. (Figure 2A)
Step 2: Shear actuator (13) moves the moving stage (12) as shear actuator (13) expands fully by "x" distance. Linear actuator (14) is at zero expansion. (Figure 2B)
Step 3: Shear actuator (13) stops expanding and hence the moving stage (2). Linear actuator (14) expands and lifts the spring pusher (15) so that shear actuator (13) gets disengaged. (Figure 2C)
Step 4: Shear actuator (13) returns to its original state without touching the moving stage (12). Linear actuator keeps holding the spring so that shear actuator (13) gets disengaged. (Figure 2D)
Step 5: Shear actuator (13) is at zero expansion. Linear actuator (14) contracts and thus due to spring action, the spring pusher (15) comes into contact with shear actuator (13).
(Figure 2E) Then follows step 1.
c) Discontinuous Motion with Three Actuators
If the heavy weight is to be dealt with pick and place or discontinuous motion, then this design works well. The linear (24) and shear actuators (23) are stacked one above the other. Third actuator (25) is attached for holding the moving stage (22) firmly when linear actuator (24) contracts and shear actuator (13) returns to its initial stage. In this case the holding actuator (25) holds the stage (22) firmly with respect to the payload which could be parallel or perpendicular to the force line.
Stage Design: If the stage is monolithic flexural linear spring, stiffness can be calculated as λs = (8BEtVt) / 9 πlA 1/2 Where
B = width
E = Young's Modulus t = Thickness
L = Column Length r = Radius of Flexure
If the stage is monolithic flexible compliance linear spring, stiffness can be calculated as λs = (12EI) / L 3 Where
I = Second Moment of Inertia E = Young's Modulus L = Column Length
The figure 3 shows the actual fabrication of the Nanopositioner. The material is stainless steel with the following specifications:
Figure 3 shows the steel made monolithic nanopositioner, linear actuator (24) and the shear actuator (23).
The maximum displacement of the flexible compliance stage can be calculated as y = F * L 3 / 12EI
With the above specifications, the nanopositioner can produce displacement up to 1000 mircon (1 mm) and the stiffness is 9.5157E-07 kN/micron. The dynamic analysis shows that the natural frequency of the stage is 0.21991612 Hz.
Actuator Design
The actuator stiffness should be more than that of the stiffness of the stage.
The stiffness of the actuator is 0.003070446 kN / micron which is more than the value of stage.
Working Principle
The conceptual representation is given in figures 3A to 3F.
Step 1 (Figure 3A):
The moving stage (22) is held by Shear actuator (23) and linear actuator (24) set. The
Holder actuator (25) has no contact with the moving stage (2) at this (initial) stage. Step 2 (Figure 3B):
Linear actuator (24) at full expansion, Shear actuator (23) at zero expansion and Holder actuator (23) at zero expansion. The moving stage (22) is not moved by the shear actuator (23).
Step 3 (Figure 3C): Linear actuator (24) at full expansion, Shear actuator (23) at full expansion and Holde' actuator (25) at zero expansion. The moving stage (22) is moved by the shear actuator
(23) by "x".
Step 4 (Figure 3D):
Linear actuator (24) at full expansion, Shear actuator (23) at full expansion and Holder actuator (25) at full expansion. The moving stage (22) is NOT moved by the shear actuator (23).
Step 5 (Figure 3E):
Linear actuator (24) at zero expansion, Shear actuator (23) at zero expansion and
Holder actuator (25) at full expansion. The moving stage (22) is NOT moved by the shear actuator (23).
Step 6 (Figure 3F):
Linear actuator (24) at full expansion, Shear actuator (13) at zero expansion and Holder actuator (25) at zero expansion after linear actuator (24) comes to contact with the moving stage (22). The moving stage 2(2) is NOT moved by the shear actuator (23). Then step 1 is repeated.
d) Continuous Motion with Four Actuators
If the continuous displacement is required and speed can be compromised, then using four short range actuators, long range displacement can be achieved. It is slightly modified version of inchworm.
Stage Design:
If the stage is monolithic flexural linear spring, stiffness can be calculated as λs = (8BEtVt) / 9 πL 2 r 1/2
Where
B = width
E = Young's Modulus t = Thickness L = Column Length r = Radius of Flexure
If the stage is monolithic flexible compliance linear spring, stiffness can be calculated as λs = (12EI) / L 3
Where
I = Second Moment of Inertia E = Young's Modulus L = Column Length The figure 4 shows the actual fabrication of the Nanopositioner. The material is stainless steel with the following specifications:
Figure 4 shows the steel made monolithic nanopositioner, linear actuator (34) and indicates the shear actuator (33).
The maximum displacement of the flexible compliance stage can be calculated as y = F * L 3 / 12EI
With the above specifications, the nanopositioner can produce displacement up to 1000 mircon (1 mm) and the stiffness is 9.5157E-07 kN/micron. The dynamic analysis shows that the natural frequency of the stage is 0.21991612 Hz.
Actuator Design
The actuator stiffness should be more than that of the stiffness of the stage.
The stiffness of the actuator is 0.003070446 kN / micron which is more than the value of stage.
In the previous method, the reversal motion of the actuator results in discontinuity during the displacement. Also if the stiffness difference between the stage and actuators are not much, reversal displacement is high in the moving stage (2). In order to prevent this additional "actuator set" is fixed as shown in figure 5. Adding two more actuators will add cost as well.
The shear actuators (33 and 36) and linear actuators (34 and 35) are put together so that they work as a single system at both sides like A & B.
Step by Step Description
Step 1 (Figure 5A):
SIDE A: Linear actuator (34) fully expanded, Shear actuator (33) at zero expansion and Nanopositioner at zero displacement SIDE B: Linear actuator (35) with zero expanded, Shear actuator (36) at full expansion and Nanopositioner at zero displacement The blue strips are flexible springs which deforms on application of force.
Step 2 (Figure 5B): SIDE A: Linear actuator (34) fully expanded, Shear actuator (33) at full expansion to
"x" distance and Nanopositioner is moved for "x" distance DUE TO SIDE A
ACTUATORS.
SIDE B: Linear actuator (35) with zero expanded, Shear actuator (36) at full expansion and Nanopositioner at zero displacement due SIDE B ACTUATORS As shear actuator (33) shears, it takes the moving stage (32) along with it to "x" displacement (i.e. full range expansion of the solid state actuators). Doted lines show the previous state.
During this period, SHEAR ACTUATOR (36) is fully expanded and yet LINEAR
ACTUATOR (35) is not expanded.
Step 3 (Figure 5C):
SIDE A: Linear actuator (34) at full expansion, Shear actuator (33) at full expansion and Nanopositioner at "x" displacement DUE TO SHEAR ACTUATOR (33) A. SIDE B: Linear actuator (35) with fully expanded, Shear actuator (36) at full expansion and Nanopositioner at zero displacement DUE TO SHEAR ACTUATOR (36) B .
Linear actuator (34) gets contracted and shear actuator (33) is released to its original state. By this time LINEAR & SHEAR ACTUATOR (35 and 36) at SIDE B contact the moving stage (32) and move by "x" distance further.
Step 4 (Figure 5D):
SIDE A: Linear actuator (34) at zero expansion, Shear actuator (33) at zero expansion and Nanopositioner at zero displacement DUE TO SHEAR ACTUATOR (33) A. SIDE B: Linear actuator (35) with fully expanded, Shear actuator (36) at full expansion and Nanopositioner at "xl" displacement DUE TO SHEAR ACTUATOR (36) B.
Linear actuator (34) gets contracted and shear actuator (33) is released to its original state. By this time LINEAR & SHEAR ACTUATOR (35 and 36) at SIDE B contact the moving stage (32) and move by "x" distance further.
Step 5 (Figure 5E):
SIDE A: Linear actuator (34) at full expansion, Shear actuator (33) at zero expansion and Nanopositioner at zero displacement DUE TO SHEAR ACTUATOR (33) A.
SIDE B: Linear actuator (35) with fully expanded, Shear actuator (36) at full expansion and Nanopositioner at "xl" displacement DUE TO SHEAR ACTUATOR (36) B.
Linear actuator (34) expands and shear actuator (33) is still at zero expansion. The moving stage (32) also is stationary.
If step 1 through step 5 is considered as one cycle, the total displacement that can be produced with the actuator that expands for "x" distance, is
X = x
For "k" of cycles,
X = kx
Where k = 1, 2, 3...
Thus with the actuator whose full expansion is small, a large displacement can be achieved.
Applications of the invention
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