JP2000020128A - Parallel mechanism applied with piezoelectric element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a parallel mechanism which has a wider movement range and can maintain a high rigidity and a high resolution. SOLUTION: A direct moving actuator 3 has arm shafts 1 built in on the inside of outer cylinders 9, Arm shafts 1 are continuously moved by repeating clamp and release or feed and return operations by feed units 51 to 53 consisting of piezoelectric elements, A series of control patterns of these clamp and release or feed and return operations are stored in a memory of a computer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel mechanism using a piezoelectric element, and more particularly to a parallel mechanism using a piezoelectric element which can increase the movable range of the parallel mechanism and maintain high rigidity and high resolution.

[0002]

2. Description of the Related Art In recent years, attention has been paid to parallel mechanisms in terms of high rigidity, high speed, high accuracy, and the like, and the number of cases used for machine tools, assembly robots, and the like is increasing (see Machine Design, Vol. 40, No. 10). No. (July 1996). A specific example of this parallel mechanism is shown in FIGS.

FIG. 14 shows an example of a telescopic parallel mechanism. This parallel mechanism is of a type in which the output node 2 is driven by six linear actuators 3,
Generally referred to as the Stewart platform. The output node 2 is fixed to the upper end of the direct-acting actuator 3 via a ball pair 4A. On the other hand, the lower end of the direct acting actuator 3 is fixed to the stationary joint 5 via the ball pair 4B. The ball pairs 4A and 4B perform a motion with three degrees of freedom around the point.

FIG. 15 shows an example of a ball pair. FIG.
6 shows an example of the slide type parallel mechanism. The slide type parallel mechanism is a linear motion type actuator.
Are arranged on the stationary node 5. A ball pair 7 is provided at a predetermined position of the direct acting actuator 6.
The rod 8 is fixed via the ball pair 7. The output node 2 is fixed to the upper end of the rod 8 via a ball pair 4A.

[0005] The driving method of the direct-acting actuator 3 and the direct-acting actuator 6 of these parallel mechanisms is based on a pneumatic / hydraulic actuator or a motor (A).
C servo) and a ball screw, or a piezoelectric element. In particular, when a piezoelectric element is used as an actuator, the accuracy and resolution are extremely high, so that expectations for a micromachine applied to the medical field and the biotechnology field are increasing.

[0006]

However, since the stroke of a piezoelectric element alone is considerably small (several μm to several tens of μm), the movable range is very narrow even if it is applied to a parallel mechanism as an actuator. On the other hand, when a pneumatic / hydraulic actuator, a motor (AC servo), and a ball screw are used to widen the movable range, the accuracy and resolution are inferior to those of the piezoelectric element.

The present invention has been made in view of such conventional problems, and has as its object to provide a piezoelectric element-applied parallel mechanism capable of widening the movable range of the parallel mechanism and maintaining high rigidity and high resolution. I do.

[0008]

Therefore, the present invention provides a parallel mechanism for driving an output node with any one of 2 to 6 degrees of freedom with respect to a stationary node fixed at a predetermined position in a space. At least one of the degrees of freedom is constituted by a linear actuator, and the linear actuator is:
A feed unit in which a first moving element and a second moving element each including a piezoelectric element for holding and releasing a shaft and feeding and returning in a moving direction are combined in a plane to which the holding direction and the moving direction of the shaft belong. A plurality of feed mechanisms provided in the moving direction of the shaft, and a series of operations of holding the shaft with any of the feed units, extending the shaft in the moving direction, sending the shaft, and then releasing the pinching and contracting in the moving direction. A storage unit for storing in advance the phase and amplitude values of the first moving element and the second moving element for repeatedly changing the phase every time, and a phase and amplitude value stored in the storage unit. Phase or the like calculating means for calculating a phase and amplitude command value to be given to the first moving element and the second moving element, and the first moving element or the like based on the calculation result of the phase or the like calculating means. And configured with a drive instruction value output means for outputting a drive command value and element to the second moving element.

The present invention applies to all cases in which a linear actuator is used for at least one of two to six degrees of freedom. The direct-acting actuator adjusts the position of the output node by driving the shaft. The first moving element and the second moving element are configured to hold and release the shaft,
It includes a piezoelectric element for returning. The feed unit is configured by combining the first moving element and the second moving element. The feed mechanism includes a plurality of feed units in the moving direction of the shaft.

The control of the feed unit shaft is performed as follows. That is, one of the feed units clamps the shaft and extends it in the moving direction to feed the shaft. Thereafter, a series of operations of releasing the pinching and contracting in the moving direction is repeatedly performed while changing the phase for each feed unit. The storage means stores in advance the patterns of the phase and amplitude values of the first moving element and the second moving element that are the basis of such control.

Next, the phase etc. calculating means calculates the phase and amplitude command values to be given to the first moving element and the second moving element from the phase and amplitude values stored in the storage means. The drive command value output means outputs a drive command value to the first moving element and the second moving element based on the calculation result of the phase etc. calculating means.

The control of the direct-acting actuator is as follows.
Instead of controlling the position on the shaft side by the feed unit, the feed unit may be fixed to the shaft side, and the outer cylinder side of the actuator may be controlled with respect to the shaft. This makes it possible to drive the direct-acting actuator over a long stroke to adjust the position of the output node. Further, since the piezoelectric element is used, the parallel mechanism can maintain high resolution as it is.

Further, the present invention is characterized in that both ends of the direct-acting type actuator are connected to the stationary node and the output node via a pair of balls which make a motion of three degrees of freedom around a predetermined point. I do.

Both ends of the actuator are fixed to the stationary node and the output node via a ball pair so that the stationary node and the output node are connected and linked. As described above, since no moment acts on the connection chain, the rigidity is high. Further, by increasing the number of feed units, higher rigidity can be secured.

Further, according to the present invention, there is provided a rod in which a first ball pair that moves with a degree of freedom about a predetermined point is fixed at a predetermined position of the shaft, and one end of which is fixed to the first ball pair. Is connected to the output node via a second ball pair,
The moving direction of the shaft may be in the plane of the stationary node or parallel to the plane to which the stationary node belongs.

A first ball pair is fixed at a predetermined position of the shaft. Then, one end of the rod is fixed to the first pair of balls. The other end of the rod is connected to the output node via a second ball pair. The shaft is disposed such that its movement direction is in the plane of the stationary node or parallel to the plane to which the stationary node belongs. As described above, since no moment acts on the connection chain even for such a parallel mechanism, the rigidity is high. Also, by increasing the number of feed units,
Higher rigidity can be secured. The control lines and the like can be easily considered for aesthetics, such as embedding in a static node.

Further, the present invention is a parallel mechanism for driving an output node with any of two to six degrees of freedom with respect to a stationary node fixed at a predetermined position in space, wherein at least one of the degrees of freedom is selected. One is constituted by a direct-acting actuator, and the direct-acting actuator extends or contracts a piezoelectric element in a direction perpendicular to the shaft, an outer cylinder arranged in parallel to the shaft, and the shaft. At least one supporting / releasing means for supporting or releasing the outer cylinder, and feeding or returning the shaft and / or the supporting / releasing means by extending or contracting a piezoelectric element in a longitudinal direction of the shaft. Feed / return means for performing an operation, a feed / return operation by the feed / return means,
Control means is provided for controlling the longitudinal position of the shaft with respect to the outer cylinder by repeatedly performing a series of operations of supporting or releasing the support by the releasing means.

The direct-acting type actuator constituting the parallel mechanism has a shaft inside the outer cylinder.
However, a shaft may be provided outside the outer cylinder. The support / release means prepares a piezoelectric element in a direction perpendicular to the shaft, and expands or contracts the piezoelectric element. The expansion or contraction at this time supports or releases the outer cylinder. The feed / return means prepares a piezoelectric element in the longitudinal direction of the shaft, and performs a feed or return operation of the shaft by expanding or contracting the piezoelectric element.

When a plurality of supporting / releasing means are provided, a part of the supporting / releasing means together with the shaft performs a feeding or returning operation. The control means controls the longitudinal position of the shaft with respect to the outer cylinder by repeatedly performing a series of operations by the feed and return, and the support and release of support. As a result, it becomes possible to drive the direct-acting actuator over a long stroke to adjust the position of the output node. Further, since the piezoelectric element is used, the parallel mechanism has high rigidity and can maintain high resolution as it is.

Further, according to the present invention, in the feed or return operation by the feed / return means, at least one ultrasonic motor is attached to the outer cylinder in parallel with the shaft, and the shaft is moved relative to the outer cylinder. It is characterized in that it is performed by controlling the position in the longitudinal direction.

As the feed / return means, an ultrasonic motor is used instead of using a piezoelectric element. At least one ultrasonic motor is attached inside the outer cylinder, but a shaft may be provided outside the outer cylinder. In this case, an ultrasonic motor is attached outside the outer cylinder. As a result, it becomes possible to drive the direct-acting actuator over a long stroke to adjust the position of the output node. Also,
The parallel mechanism has high rigidity without a moment acting on the connecting chain, and can maintain high resolution as it is.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. The overall configuration diagram of the first embodiment of the present invention is the same as FIG. The direct-acting actuator 3 has the arm shaft 1 incorporated inside the outer cylinder 9. FIG. 1 shows a detailed functional diagram of the direct acting actuator 3.

In FIG. 1, one end of each of a pair of feed elements 13a is fixed to a space position (outer cylinder 9) opposed to the arm shaft 1 in a direction perpendicular to the direction of movement of the arm shaft 1. The other end of the feed element 13a is opened so as to be able to expand and contract in the moving direction of the arm shaft 1.
In addition, the pair of clamp elements 14a is
a one end of which is fixed to the other end of the
The other end of 4a is openable and contractible in a direction perpendicular to the moving direction of the arm shaft 1 so that the arm shaft 1 can be clamped or released.

The feed unit 51 comprises a pair of feed elements 13a and a pair of clamp elements 14a. The feed mechanism 10 includes feed units 51 to 53 having the same configuration in the moving direction of the arm shaft 1. The feed element 13a and the clamp element 14a are configured by a piezoelectric element (PZT) so that an applied voltage can be converted into displacement.

The feed unit may be configured as shown in FIG. 2 or FIG. In FIG. 2, the feed element 1
One end of 3 is fixed to a predetermined space position (outer cylinder 9), and the other end is fixed to one end surface of a clamp block 12 for holding the arm shaft 1. Clamp block 1
One end of the clamp element 14 is fixed to the other end face of the armature 2 in a direction perpendicular to the moving direction of the arm shaft 1. The other end of the clamp element 14 is fixed at a predetermined space position (outer cylinder 9).

In FIG. 3, one end of the moving element 43 is fixed to a predetermined space position (outer cylinder 9), and the holding direction and the moving direction of the arm shaft 1 are within a plane to which the holding direction belongs. Are provided. And
One end surface of a clamp block 42 for holding the arm shaft 1 is fixed to the other end of the moving element 43.

One end of a moving element 44 is fixed to another end face of the clamp block 42. The moving element 44 has a predetermined angle with respect to the clamping direction of the arm shaft 1 and a plane to which the moving direction belongs. It is arranged. Moving element 4
The other end of 4 is fixed to a predetermined space position (outer cylinder 9). Here, the feed element 13 and the moving element 43 (or the moving element 44) are the first moving element, and the clamp element 14 and the moving element 44 (or the moving element 43) are the second moving element.
Of moving elements.

FIG. 4 shows an overall system configuration diagram for controlling the feed mechanism 10. As shown in FIG. The computer 21 includes a memory 22 (corresponding to a storage means, not shown), and includes feed elements 13a to 13c and clamp elements 14a to 14
A command value for the phase and amplitude of c is calculated.
The D / A converter 23 and the driving amplifier 24 are configured to convert the command value into a voltage. When the position feedback control is performed, a position sensor 25 is provided, the signal is converted by an A / D converter 26, and then input to the computer 21.

Next, the feed mechanism 10 will be described with reference to FIGS.
Will be described. FIG. 5 and FIG. 7 show control patterns for one cycle for moving the arm shaft 1. FIG. 5 shows a control pattern when the feed unit shown in FIGS. 1 and 2 is used, and FIG. 7 shows a control pattern when the feed unit shown in FIG. 3 is used.

First, in FIG. 5, between timings 1 and 2, the clamp elements 14a and 14c are in a sandwiching state. The clamping element 14b is released from being held. While maintaining this state, a voltage is gradually applied to the feed elements 13a and 13c. As a result, arm shaft 1
Can be moved.

The displacement of the feed element 13b gradually decreases during this time. At timing 3 (phase π), the clamp element 14b is brought into the clamping state, and the clamp elements 14a and 14
Release the holding of c. Between timing 4 and timing 5, the clamp element 14b is in the clamped state, and the clamp elements 14a and 14c are in the state of releasing the clamp. While maintaining this state, a voltage is gradually applied to the feed element 13b.

As a result, the arm shaft 1 can be further moved. The feed elements 13a and 13c gradually reduce their displacement during this time. Then, between timing 5 and timing 6 (phase 2π), the clamp element 14a is
And 14c are brought into the sandwiched state, thereby returning to the phase 0 state. By repeating such one-cycle operation, the feed mechanism 10 can drive the arm shaft 1 over a long stroke.

The return operation of the arm shaft 1 puts the clamp elements 14a and 14c in a clamping state, and releases the clamping of the clamp element 14b. While maintaining this state, a positive voltage is applied to the feed element 13b to increase (extend) its displacement. This state is maintained, and the clamp element 14b is brought into the sandwiched state. And the clamping elements 14a and 14c
Release the pinch.

When the voltage of the feed element 13b in the sandwiched state is reduced in the range of the plus voltage, the displacement of the feed element 13b decreases, and the arm shaft 1 moves backward. Next, the same return command can be given to the clamp elements 14a and 14c in the clamp release state, so that the return operation can be continuously performed.

Next, FIG. 6 shows a case where a feed mechanism is constituted by using the feed unit shown in FIG. FIG. 7 shows a control pattern of the feed mechanism. The timing is shown in FIG. Moving element 43a, moving element 43b, moving element 4
3c is one each for feeding the arm shaft 1 in the moving direction.
The sine voltage is applied by changing the phase by 20 degrees.

The moving elements 43a, 43b,
The phases of the moving element 43c and the moving element 44a, the moving element 44b, and the moving element 44c are different from each other by 90 degrees in order to continuously repeat the pinching or the pinching release. In order to facilitate understanding, FIG. 6 shows a conceptual diagram of the feed at each timing of each feed unit as an ellipse around the arm shaft 1.

For example, in the case of the feed unit 81, the timing indicates a state where the clamp block 42a is farthest from the arm shaft 1, and the timing indicates a state where the clamp block 42a clamps the arm shaft 1 most strongly. . When the feed conceptual diagram for each feed unit is similarly shown as an ellipse, it can be confirmed that the arm shaft 1 is moved in the moving direction at each timing. In addition, as shown in FIG. 8, the voltage actually applied to each moving element is superimposed with a clamping voltage to secure a predetermined rigidity.

FIG. 9 is a flowchart for explaining the operation of the first embodiment of the present invention. First, in step 1 (S
Shown as 1. In the following, the phase and voltage waveform (amplitude value) for one cycle described in FIG. 5 or FIG. 7 are stored and held in the memory 22 as a periodic function. In step 2, variables such as a movement target position and a movement speed of the arm shaft 1 are input. In step 3, the phase increment is calculated based on the input variables. In step 4, the voltage is read from the periodic function stored in the memory 22 to calculate the voltage command value.

For example, when a variable is input so as to decrease the moving speed of the arm shaft 1, the increment of the phase is reduced, and when a variable is input so as to increase the moving speed, the increment of the phase is increased. I do. However, arm shaft 1
If you input a variable that slows down the moving speed, decrease the amplitude command value.If you input a variable that speeds up the moving speed, perform processing to increase the amplitude command value. Is also good. Steps 3 and 4 correspond to a phase and the like calculating means.

Thereafter, in step 5, it is determined whether or not the position is within the error range of the movement target position. If the processing in step 6 is not within the error range of the movement target position, the D / A converter 2 is sent from the computer 21 based on the voltage command value obtained in step 4.
3, and sends a voltage to each sending element and each clamping element via the drive amplifier 24, and corresponds to a drive command value output means. The process of step 7 is to hold all the clamp elements in a clamping state (or apply a voltage equal to or greater than the clamping voltage equally to all the moving elements) if the error is within the error range of the movement target position, and clamp the arm shaft 1 (hereinafter, the clamping operation and the Call)
Things.

As a result, a long stroke movement can be performed. Further, if the clamping operation is performed after the movement target position is reached, it is possible to increase the rigidity at the time of load control by the output node 2 or the like that follows.

Although the number of feed units is three in this embodiment, the rigidity can be increased by increasing the number of feed units. In addition, even if the clamping operation is not necessarily performed on all of the feed units, the rigidity can be increased by performing the operation on at least two or more feed units.

By inputting the movement target position of the arm shaft 1 as a variable, the arm shaft 1 may be automatically moved to the movement target position as described above. The arm shaft 1 may be moved only while the push button is being pressed.
Even in this case, it is possible to change the moving speed of the arm shaft 1 by calculating the phase and the like in step 3 by inputting the moving speed as a variable.

That is, it is possible to change the moving speed by changing at least one of the phase and the amplitude applied to the feed element and the clamp element. If the moving speed is not input as a variable, the movement of the arm shaft 1 is controlled based on the periodic function stored in the memory 22 in step 1 in advance. Since the above control is performed in an open loop without performing feedback control, the position sensor 25 may not be provided.

FIG. 10 shows a case in which two feed units are provided as another configuration diagram (feed mechanism 30) of the feed mechanism. The arm shaft 1 is moved based on a periodic function stored in the memory 22 in advance. The point that the rigidity can be increased by performing the movement control and performing the clamping operation after reaching the movement target position is the same as described above. The control when four or more feed units are provided is basically the same. Even if the number of feed units is increased, the control section can be processed with the same configuration. Further, at this time, as the number of feed units is increased, the number of feed units for processing the same process is increased, so that the rigidity during movement of the arm shaft 1 can be increased.

As described above, by arranging a plurality of feed units using piezoelectric elements in the actuator, the actuator can have a long stroke and the movable range of the parallel mechanism can be widened (for example,
Several μm to several hundred mm). Further, high rigidity and high resolution (for example, several μm) can be maintained by applying the piezoelectric element.

Next, a second embodiment of the present invention will be described. The overall configuration diagram of the second embodiment of the present invention is the same as FIG. The same elements as those in FIG. 14 are denoted by the same reference numerals, and description thereof will be omitted. Linear actuator 6
The arm shaft 1 is incorporated inside the outer cylinder 9. However, a ball pair 7 is fixed to the arm shaft 1. The linear actuator 6 is arranged on the stationary node 5 in parallel with the stationary node 5.

Except that the ball pair 7 is fixed to the arm shaft 1 and the rod 8 is disposed between the output node 2 and the stationary node 5,
The second embodiment of the present invention is the same as the first embodiment. Therefore, the internal configuration and control method of the linear motion actuator 6 are the same as those of the first embodiment of the present invention. Note that the wiring to the linear motion actuator 6 and the like can be embedded in the stationary node 5, so that the configuration can be made without exposing the control wiring and the like. As described above, effects similar to those of the first embodiment of the present invention can be obtained.

Next, a third embodiment of the present invention will be described. FIG. 11 shows an overall configuration diagram of the third embodiment of the present invention. The same elements as those in FIGS. 14 and 16 are denoted by the same reference numerals and description thereof will be omitted. In FIG. 11, a support / release unit 55 is fixed to the lower end of the arm shaft 1 in a direction perpendicular to the arm shaft 1. The support / release unit 55 contains a piezoelectric element 57, and the outer periphery of the support / release unit 55 supports or releases the outer cylinder 61 from the inside.

The feed / return portion 59 is fixed to the lower end of the support / release portion 55. Then, the feed / return unit 59
Has a piezoelectric element 63 therein. Further, a support / release unit 65 is fixed to the lower end of the feed / return unit 59 in a direction perpendicular to the arm shaft 1. A piezoelectric element 67 is provided in the support / release unit 65, and the outer periphery of the support / release unit 65 supports or releases the outer cylinder 61 from the inside. The support / release unit 55 and the support / release unit 65 correspond to a support / release unit.

Next, the operation of the third embodiment of the present invention will be described. Now, it is assumed that the piezoelectric element 57 and the piezoelectric element 63 are in a contracted state. It is assumed that the piezoelectric element 67 is in an extended state. Since the piezoelectric element 67 is in the extended state, the outer periphery of the support / release unit 65 supports the outer cylinder 61 from the inside.

Next, in this state, the voltage applied to the piezoelectric element 63 is gradually increased to expand the piezoelectric element 63. Due to the extension at this time, the support / release unit 55 and the arm shaft 1 move upward. After the extension of the piezoelectric element 63 is completed,
The piezoelectric element 57 is extended. Due to the extension of the piezoelectric element 57, the outer periphery of the support / release unit 55 supports the outer cylinder 61 from the inside.

After the support of the outer cylinder 61 by the support / release unit 55 is completed, the piezoelectric element 67 is contracted. Due to the contraction of the piezoelectric element 67, the outer periphery of the support / release unit 65 is released from the outer cylinder 61. After that, the piezoelectric element 63 is contracted. next,
The voltage applied to the piezoelectric element 67 is gradually increased and expanded. At this time, the outer periphery of the support / release unit 65 supports the outer cylinder 61 again from the inside. Thereafter, by contracting the piezoelectric element 57, the outer periphery of the support / release unit 55 is released from the outer cylinder 61. Thus, one cycle is completed.

For the expansion and contraction of each piezoelectric element, another operation may be performed after the completion of each operation, but a predetermined range may be set as an overlap operation in order to shorten the control time. For example, the contraction operation of the piezoelectric element 67 and the contraction operation of the piezoelectric element 63 can be partially overlapped and performed simultaneously.
Further, if the supporting / releasing portions 55 and 65 are molded of, for example, a resin having high elasticity and a high friction coefficient, the movement control of the arm shaft 1 with respect to the outer cylinder 61 can be ensured.

Next, a fourth embodiment of the present invention will be described. FIG. 12 shows an overall configuration diagram of the fourth embodiment of the present invention. The same elements as those in FIG. 11 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 12, a feed / return portion 59 is fixed to the lower end of the arm shaft 1. The feed / return unit 59 includes a piezoelectric element 63 therein. Further, at the lower end of the feed / return unit 59,
Support / release unit 65 in a direction perpendicular to arm shaft 1
Is fixed.

Next, the operation of the fourth embodiment of the present invention will be described. If a not-shown contact portion with the outer cylinder 61 is provided above the arm shaft 1 and the frictional force therebetween is set high, the arm shaft 1 is still even when the piezoelectric element 67 is in a contracted state. In this state, the piezoelectric element 63 is contracted.
Thereafter, the piezoelectric element 67 is extended to support the outer periphery of the support / release unit 65 with respect to the outer cylinder 61 from the inside. Then, the arm element 1 is moved upward by extending the piezoelectric element 63. By repeating this series of operations, the arm shaft 1 can be continuously moved upward.

Next, a fifth embodiment of the present invention will be described. FIG. 13 shows an overall configuration diagram of the fifth embodiment of the present invention. The same elements as those in FIGS. 11 and 12 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 13, a feed / return unit 69 is fixed to the lower end of the support / release unit 55. Ultrasonic motors 71A and 71B are attached to the feed / return unit 69 on the left and right so as to face the outer cylinder 61. A support / release unit 65 is fixed to the lower end of the feed / return unit 69.

Next, the operation of the fifth embodiment of the present invention will be described. The feed / return operation of the feed / return unit 69 is performed by ultrasonic motors 71A and 71B instead of the piezoelectric element. Also in this case, the actuator can have a long stroke, and the movable range of the parallel mechanism can be widened. In addition, high rigidity and high resolution can be maintained.

[0059]

As described above, according to the present invention, the position of the output node can be adjusted by driving the direct-acting actuator over a long stroke. The parallel mechanism can maintain high resolution as it is.

[0060]

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a feed mechanism.

FIG. 2 is another configuration diagram of a feed unit.

FIG. 3 is another configuration diagram of a feed unit.

FIG. 4 is an overall system configuration diagram

FIG. 5 is a control pattern for one cycle for moving a moving object.

FIG. 6 is a conceptual diagram of the movement of a feed mechanism using the feed unit shown in FIG. 3;

FIG. 7 is a control pattern of a feed mechanism using the feed unit shown in FIG. 3;

FIG. 8 shows a voltage pattern applied to each moving element.

FIG. 9 is a flowchart according to the first embodiment of the present invention.

FIG. 10 is another configuration diagram of a feed mechanism.

FIG. 11 is an overall configuration diagram of a third embodiment of the present invention.

FIG. 12 is an overall configuration diagram of a fourth embodiment of the present invention.

FIG. 13 is an overall configuration diagram of a fifth embodiment of the present invention.

FIG. 14 shows an example of a telescopic parallel mechanism.

FIG. 15: An example of a ball pair

FIG. 16 shows an example of a slide type parallel mechanism.

[Explanation of symbols]

Reference Signs List 1 arm shaft 2 output joint 3, 6 direct acting actuator 4A, 4B, 7 ball pair even 5 stationary joint 8 rod 9, 61 outer cylinder 12, 42, 42a, 42b, 42c clamp block 13a, 13b, 13c, 33a, 33b Feeding elements 14a, 14b, 14c, 34a, 34b Clamping elements 10, 30 Feeding mechanism 22 Memory 24 Driving amplifier 25 Position sensor 43, 44, 43a, 43b, 43c, 44a, 44
b, 44c Moving element 55, 65 Support / release section 57, 63, 67 Piezoelectric element 59, 69 Feed / return section 71A, 71B Ultrasonic motor

Continued on the front page (72) Inventor Ikuo Muto 4-3-1, Yashiki, Narashino-shi, Chiba Seiko Seiki Co., Ltd. (72) Inventor Yoshinobu Ohdate 4-3-1, Yashiki, Narashino-shi, Chiba Seiko Seiki Incorporated F term (reference) 3F059 BA05 FC00 3F060 BA10 EA10 GA01 GA11 GA13 HA39 5H303 AA01 AA10 BB01 BB08 BB11 BB17 CC01 DD01 DD14 KK01 5H680 BB01 BC08 BC09

Claims (5)

[Claims] 1. A parallel mechanism for driving an output node with one of two to six degrees of freedom with respect to a stationary node fixed at a predetermined position in space, wherein at least one of the degrees of freedom is a direct mechanism. The linear actuator comprises a first moving element and a second moving element each including a piezoelectric element for holding and releasing a shaft or for sending and returning in a moving direction. A feed mechanism having a plurality of feed units combined in a plane to which the holding direction and the movement direction belong in the movement direction of the shaft, and a shaft which is held in one of the feed units and stretches in the movement direction to feed the shaft. The phase of the first moving element and the second moving element for repeatedly performing a series of operations of releasing the pinching and contracting in the moving direction while changing the phase for each of the feed units and A storage unit for storing amplitude values in advance, a phase for calculating a phase and amplitude command value given to the first moving element and the second moving element from the phase and amplitude values stored in the storage unit, Calculating means, and the first moving element and the second moving element based on a calculation result of the phase etc. calculating means.
And a drive command value output means for outputting a drive command value to the moving element. 2. The linear motion type actuator according to claim 1, wherein both ends of the linear motion type actuator are connected to the stationary node and the output node via a pair of spheres which move about three degrees of freedom around a predetermined point. The parallel mechanism to which the piezoelectric element described is applied. 3. A first ball pair that moves about three predetermined degrees of freedom around a predetermined point is fixed to a predetermined position of the shaft, and the other end of the rod having one end fixed to the first ball pair is 2. The output node is connected to the output node via a second pair of balls, and a moving direction of the shaft belongs to a plane of the stationary node or is parallel to a plane to which the stationary node belongs. The parallel mechanism according to claim 2, wherein the piezoelectric element is applied. 4. A parallel mechanism for driving an output node with any of two to six degrees of freedom with respect to a stationary node fixed at a predetermined position in space, wherein at least one of the degrees of freedom is a direct mechanism. The linear actuator comprises a shaft, an outer cylinder arranged in parallel with the shaft, and a piezoelectric element which is extended or contracted in a direction perpendicular to the shaft. At least one supporting / releasing means for supporting or releasing the cylinder, and a feed for performing a feeding or returning operation of the shaft and / or the supporting / releasing means by extending or contracting a piezoelectric element in a longitudinal direction of the shaft.・ Return means and a series of operations of feed or return operation by the feed / return means and support or release by the support / release means are repeatedly performed on the outer cylinder. A parallel mechanism using a piezoelectric element, comprising a control means for controlling a position of the shaft in a longitudinal direction. 5. A feed or return operation by said feed / return means, wherein at least one ultrasonic motor is attached to said outer cylinder in parallel with said shaft, and a longitudinal position of said shaft with respect to said outer cylinder. 5. The parallel mechanism according to claim 4, wherein the control is performed by controlling the following.