JP2000098257A - Stage for microscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stage for a microscope of a flat parallel link type which has a compact structure and of which the moving capability has at three degrees of freedom. SOLUTION: This stage has a rectilinear actuator 12 which moves a movable member 16 relatively to a base 11 by means of respectively at least three drive links 12 and movable links 14 to rectilinearly move the drive links 12b and is mounted at the base surface of the base 11 in parallel therewith or with inclination therewith and a control means which controls the rectilinear actuator 12 by detecting the position and speed of the drive links 12b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microscope stage using a parallel link mechanism.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, there is a well-known parallel link mechanism as a Stuart platform system. In FIG. 6, an upper movable plate 101 and a lower fixed plate 102 are connected by six links 104 which can be extended and contracted by an actuator 103 such as a fluid pressure cylinder. Actuator 1
03 and the fixed plate 102 are connected by a ball joint 105a. Also, the link 104 and the movable plate 101
Are connected by a ball joint 105b.
Each link 104 changes its stroke as the actuator 103 expands and contracts. By controlling the stroke of each link 104 in a coordinated manner, the movable plate 10
1 is “translation 3 degrees of freedom”, “rotation 3
6 degrees of freedom in total.

A "parallel link manipulator" disclosed in JP-A-7-60678 (Nippon Steel Corporation) and JP-A-7-116983 (Toshiba Machine)
Is an improved version of the Stuart platform type parallel link mechanism, in which six telescopic links are arranged between an upper movable plate and a lower fixed plate. As the link expansion / contraction drive means, a rotation / linear conversion mechanism including a rotary motor, a speed reducer, a ball screw, a rack, and a pinion is used.

[0004]

However, in the microscope stage, the size of the stage in the vertical direction is limited due to the approach of the objective lens. In the configuration of the above-described conventional parallel link mechanism, since six actuators and links are arranged in a direction substantially perpendicular to the fixed plate, the entire stage cannot be thinned when applied to a microscope stage. There was a problem. Also,
When the actuator itself moves, the link itself becomes large, and when a rotary motor is used, there is a problem that the entire device becomes large because a reduction gear and a rotation-linear conversion mechanism are used.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention according to claims 1, 2 and 3 is to have a compact structure and at least 3 athletic abilities.
An object of the present invention is to provide a flat parallel link microscope stage having a degree of freedom.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1, 2 or 3 has a structure in which a movable member is attached to a base by at least three drive links and movable links. In the stage for the microscope that moves relatively, the drive link is moved in a straight line to move the drive link in parallel or slightly inclined to the bottom surface of the base, and the position and speed of the drive link are detected. Control means for controlling the linear actuator.

In the microscope stage according to the first, second, or third aspect of the present invention, a linear actuator which linearly moves a drive link and is attached at a slight inclination to the bottom surface of the base;
Control means for detecting the position and speed of the drive link to control the linear actuator, so that the linear actuator mounted parallel or slightly inclined lowers the height of the stage, and the control means Controls linear motion.

In the microscope stage according to the second or third aspect of the present invention, in addition to the above-described operation, an ultrasonic linear motor is used for a linear actuator, and the main body of the ultrasonic linear motor is fixed to the base. By connecting the slider of the motor as a drive link to the base end of the movable link and connecting the distal end of the movable link to the movable member, the slider of the ultrasonic linear motor moves the movable link, and the movable link moves the movable member.

In the microscope stage according to the third aspect of the present invention, in addition to the above operation, the control means includes a trajectory command generation unit, an inverse kinematics operation unit, a position comparator, an inter-axis interpolation operation unit, a speed comparator, A drive frequency control unit, a drive waveform creation unit, a drive signal amplitude control unit, a multiplier, a phase shifter, and an amplifier, which variably control the waveform and frequency or amplitude of the drive signal of the ultrasonic linear motor. And the displacement and speed of the slider of the ultrasonic linear motor are freely controlled.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A microscope stage of a parallel link type described in an embodiment of the present invention has six telescopic drive links and six fixed length movable links. However, although the number of six is a preferable requirement, it is not an essential requirement and may be three. However, the degree of freedom is restricted, and from 6 degrees of freedom to 3 degrees of freedom,
For specific applications. A small ultrasonic linear motor is used for the linear actuator, and a slider of the small ultrasonic linear motor is used as a telescopic drive link. The small ultrasonic linear motor is mounted parallel or at an angle of 0 to 45 degrees, preferably 30 degrees with respect to the bottom surface of the base.

By mounting the small ultrasonic linear motor at an angle of 0 to 45 degrees with respect to the bottom of the base, the mechanism can be flattened and the height of the entire stage can be reduced. In addition, the use of a small ultrasonic linear motor eliminates the need for a rotation-linear conversion mechanism such as a reduction gear at all.
The microscope stage can have a compact structure. Hereinafter, specific embodiments will be described.

(Embodiment 1) FIGS. 1 to 4 show Embodiment 1, FIG. 1 is a perspective view of a main body of a microscope stage, and FIG. 2 is a configuration of a position and speed detecting device of an ultrasonic linear motor. FIG. 3 is a block diagram of a control system of the microscope stage, FIG. 4 is a perspective view showing a space vector of the microscope stage, and FIG. 5 is a speed-drive frequency characteristic diagram of the ultrasonic linear motor.

In FIG. 1, a main body 1 of a microscope stage is shown.
On the upper surface of the base 11, there are a total of six ultrasonic linear motors 12 as a set of two on a circumference around the central axis of the base 11.
Are arranged at equal intervals of 120 degrees. The ultrasonic linear motor 12 includes a motor body 12a and a slider 12b, and the slider 12b as a drive link is driven straight forward and backward with respect to the motor body 12a. Motor body 12
a is attached to the bottom surface of the base 11 at an inclination angle α. The inclination angle α is set to 0 degree to 45 degrees. The tilt angle α may be variable by providing a tilt angle adjusting mechanism, mounting the motor body 12a thereon. The distal end of the slider 12b of the ultrasonic linear motor 12 is connected to the base end of a movable link 14 having a fixed length via a lower joint 13 formed of a ball joint.
Similarly, it is connected to a movable member 16 via an upper joint 15 composed of a ball joint.

As shown in FIG. 2, the ultrasonic linear motor 1
The optical scale 17 is fixed to the second motor body 12a. Opposite to the optical scale 17, a sensor head 18 a of an optical displacement sensor 18 (see FIG. 2) is connected to the ultrasonic linear motor 12 via a sensor head adjusting mechanism 19.
Is attached to the slider 12b. The sensor head adjusting mechanism 19 keeps a constant angle with respect to the optical scale 17 and adjusts the distance and position between the optical scale 17 and the sensor head 18a so that the light emitted from the sensor head 18a is focused on the optical scale 17. It can be adjusted freely. The optical displacement sensor 18 detects a change in stroke (position and speed) of the slider 12b of the ultrasonic linear motor 12, and inputs the signal to a control system 2 (see FIG. 3) as control means for the microscope stage. I do.

As shown in FIG. 3, the control system 2 for the microscope stage includes a trajectory command generator 21 and an inverse kinematics calculator 22.
A position comparator 23, an inter-axis interpolation calculator 24, a speed comparator 25, a drive frequency calculator 26, a drive waveform generator 27, a drive signal amplitude controller 28, a multiplier 29,
It comprises a phase shifter 30, an amplifier a31, an amplifier b32, and a position detector 18b and a speed detector 18c of the optical displacement sensor 18 attached to the ultrasonic linear motor 12 of the main body 1. Although FIG. 3 shows the configuration of a control system for controlling one ultrasonic linear motor, the control system of the other five ultrasonic linear motors has the same configuration.

In order to control the ultrasonic linear motor 12 when operating the parallel link type microscope stage,
Inverse kinematics calculations are required. In the case of the microscope stage having the above configuration, the control amount of the ultrasonic linear motor 12 is as shown in FIG.
Is obtained geometrically using the space vector diagram shown in FIG. The calculation method is shown below. The following relationship is established from the space vector diagram. _{k i w i = p + Rph} i -pb i (1) k i w i = L i a i + cz i (2) the formula from the relationship of (1) (2),

[0017]

(Equation 1)

## EQU1 ## where: R is a rotation conversion matrix to a posture command

[0019]

(Equation 2)

P: the center position of the movable member including the position command ph _i : a spatial position vector representing the connection point of the movable member and each movable link in the movable member coordinates (i is the order of the movable links 1 to 6) pb _i : When the slider of the ultrasonic linear motor is located at the bottom, a spatial position vector expressing the connection point between the slider and each movable link in base coordinates c: Length of each movable link _ki : Upper joint and lower Distance between joints a _i : unit direction vector of slider of each ultrasonic linear motor w _i : unit direction vector between upper joint and lower joint z _i : unit direction vector of each movable link l _max : ultrasonic wave maximum travel distance of the linear motor slider alpha: ultrasonic linear motor of the tilt angle L _i: control of the slider of the ultrasonic linear motor, the obtained value of _{L i 0 ≦ L i ≦ l} max ·: vector Le of the inner product

The control amount of the microscope stage obtained by inverse kinematics is expressed by a quadratic expression. In the case of this mechanism, there are cases where both solutions are valid, as shown by the quadratic equation. If there are two solutions even if limited by the discriminant of the solution or the maximum moving distance of the slider of the ultrasonic linear motor, both solutions are valid, but there are problems of continuity and singularity passing, Due to physical limitations, it is necessary to limit to one solution. The control of the microscope stage uses a method of obtaining the motion of each ultrasonic linear motor with respect to the target position / posture of the movable member using inverse kinematics, and controlling each ultrasonic linear motor based on the motion. .

Next, the operation of the microscope stage having the above configuration will be described.
The work will be described. In FIG. 3, the trajectory command generation unit 2
Inverse kinematics of position command and posture command of movable member 16 from 1
Provided to the operation unit 22, and the inverse kinematics operation unit 22
Each drive link (ultrasonic linear motor 12
Length of the slider 12b) (slider 12b)
Of the ultrasonic linear motors 12
Command value L_i ^*(I = 1 to 6). Reverse kinematics performance
Calculation unit 22 calculates six ultrasonic linear motions using equation (3).
Command value L to the motor 12_i ^*(I = 1 to 6) is the position ratio
To the comparator 23. In the position comparator 23, an inverse kinematics operation is performed.
Command value L from unit 22_i ^*And the ultrasonic linear motor 12
Is detected from the position detector 18b of the optical displacement sensor 18 of FIG.
The actual expansion / contraction distance L of the slider 12b_i(I = 1 ~
6) and the deviation signal ΔL _iIs interpolated between each axis
Input to the section 24. In each inter-axis interpolation calculation unit 24, each supersonic
The speed of the slider 12b of the wave linear motor 12
Therefore, the slider 12b calculated by the following equation (4)
Speed command value v_i ^*And input to the speed comparator 25.
You.

[0023]

(Equation 3)

Here, v _max : the maximum speed of the ultrasonic linear motor max (ΔL _i ): the maximum value of the deviation signal ΔL _i for each control cycle The speed comparator 25 calculates the six signals obtained by the equation (4). The speed command value v _i ^* of the ultrasonic linear motor 12 and the speed detector 18 of the optical displacement sensor 18 of the ultrasonic linear motor 12
comparing the velocity v _i of the actual slider 12b which is detected by c, inputs the deviation signal Delta] v _i to a frequency control unit 26 and the drive signal amplitude control section 28.

[0025] The frequency controller 26 generates a drive frequency f _i. As shown in FIG.
Velocity v, in the resonance frequency f ₀ is less than the side, the velocity change is abrupt, wherein, using a higher than the resonance frequency f ₀ driving frequency f _i. And the resonance frequency f ₀ of the ultrasonic linear motor 12 as a boundary, in order to increase the speed of the ultrasonic linear motor 12, the driving frequency f _i the resonance frequency f
₀ or set near f ₀ . Ultrasonic linear motor 1
When decreasing the second velocity is set farther the driving frequency f _i from the resonance frequency f _0. Set drive frequency f _i
Is input to the drive waveform creation unit 27.

The drive waveform generator 27 includes a frequency controller 2
Drive frequency f input from 6_iDrive waveforms
To achieve. Whether the drive waveform is sinusoidal or pulsed,
Determines whether the waveform is an envelope waveform that combines a sine wave and a pulse.
Set. For example, during fine movement or when a slow speed is required
In this case, the envelope waveform drive is performed.
Is required, a continuous sinusoidal waveform drive is performed. Combination
The generated drive waveform signal u _iIs output to the multiplier 29.

The deviation signal Δv from the speed comparator 25_iEnter
In the other drive signal amplitude control unit 28 to be
Drive signal u of linear motor 12_iAmplitude A of_iDetermine
You. For example, the driving frequency f of the ultrasonic linear motor 12_i
When speed control is performed by changing_iConstant
The signal is output to the multiplier 29 while being kept. Meanwhile, frequency control
Drive frequency f from unit 26_iAnd keep the drive voltage
Magnitude, that is, amplitude A _iOnly change the ultrasonic linear model
When controlling the speed of the motor, the following equation (5) is used.
And performs a proportional-integral operation to obtain the drive waveform signal u_iAmplitude A of_i
Is generated and output to the multiplier 29. A_i= (K_p+ K_i/ S) * Δv_i(S) (5) where A_i: Amplitude of drive signal K_p: Proportional gain K_i: Integral gain on s range

The multiplier In 29, a drive waveform signal u _i output from the drive waveform creation unit 27 a drive signal amplitude control section 28
An output amplitude A _i from by multiplying the drive signal U _i
Are combined and output. The drive signal U _i from the multiplier 29 is input to the phase shifter 30 and the amplifier a31. Phase shifter 30
Can shift the phase of the drive signal U _i by ± 90 °, and the drive signal U _i from the multiplier 29 is
After passing through 0, the signal is shifted by ± 90 ° and input to the amplifier b32. The signal u _ai output from the amplifier a and the signal u _bi output from the amplifier b are signals shifted from each other by 90 degrees, and the signal u _ai and the signal u _bi shifted from each other by 90 degrees.
Is applied to the ultrasonic linear motor 12 to drive the ultrasonic linear motor 12 at a required displacement and speed.
2b is controlled.

As described in the configuration and operation of the microscope stage, by simultaneously and cooperatively controlling the displacement and the speed of the sliders of the six ultrasonic linear motors, the direction of the movable member in the three-dimensional space is controlled. And the angle can be controlled freely.

According to the present embodiment, it is possible to obtain a flat parallel-link type microscope stage having a compact structure and a six-degree-of-freedom exercise capability.

In this embodiment, the optical displacement sensor is used for detecting the position and speed of the slider of the ultrasonic linear motor, but a magnetic sensor may be used instead.

[0032]

According to the first, second or third aspect of the present invention, the linear actuator mounted parallel or slightly inclined lowers the height of the stage, and the control means controls the linear movement of the drive link. Therefore, it is possible to obtain a flat parallel link type microscope stage having a compact structure and at least three degrees of freedom in athletic ability.

According to the second or third aspect of the present invention, in addition to the above effects, the slider of the ultrasonic linear motor moves the movable link, and the movable link moves the movable member. The posture can be freely changed.

According to the third aspect of the invention, in addition to the above effects, the displacement and speed of the slider of the ultrasonic linear motor are freely controlled, so that the position and posture of the movable member are changed to desired positions and postures. Can be done.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main body of a microscope stage according to a first embodiment.

FIG. 2 is a configuration diagram of a position and speed detection device of the ultrasonic linear motor according to the first embodiment.

FIG. 3 is a block diagram of a control system of the microscope stage according to the first embodiment.

FIG. 4 is a perspective view showing a space vector of the microscope stage according to the first embodiment.

FIG. 5 is a speed-drive frequency characteristic diagram of the ultrasonic linear motor according to the first embodiment.

FIG. 6 is a perspective view of a conventional parallel link mechanism.

[Explanation of symbols]

 Reference Signs List 11 base 12 ultrasonic linear motor 12b slider 14 movable link 16 movable member

Claims (3)

[Claims] 1. A microscope stage in which a movable member is relatively moved with respect to a base by at least three drive links and at least three movable links, wherein the drive link is caused to move linearly to a bottom surface of the base. 1. A microscope stage comprising: a linear actuator mounted parallel or slightly inclined; and control means for detecting the position and speed of the drive link and controlling the linear actuator. 2. An ultrasonic linear motor is used for the linear actuator, a main body of the ultrasonic linear motor is fixed to the base, and a slider of the ultrasonic linear motor is used as the drive link at a base end of the movable link. The microscope stage according to claim 1, wherein the movable link is connected, and a distal end of the movable link is connected to the movable member. 3. The control means includes a trajectory command generator, an inverse kinematics calculator, a position comparator, an inter-axis interpolation calculator, a speed comparator, a drive frequency controller, a drive waveform generator, and a drive signal amplitude controller. The microscope stage according to claim 2, further comprising a unit, a multiplier, a phase shifter, and an amplifier, and variably controls a waveform and a frequency or an amplitude of a drive signal of the ultrasonic linear motor.