WO2009136504A1

WO2009136504A1 - Precision positioning device

Info

Publication number: WO2009136504A1
Application number: PCT/JP2009/002012
Authority: WO
Inventors: 良知塩手; 高志津村; 豊原田
Original assignee: 株式会社山武
Priority date: 2008-05-08
Filing date: 2009-05-07
Publication date: 2009-11-12
Also published as: JP2009271783A; JP5284683B2

Abstract

A precision positioning device is provided with a voice coil motor (5) for supporting a coil, which is placed in a magnetic field, by an elastic guiding member such that the coil is displaceable in a predetermined direction, driving an actuator including the coil by causing an electric current to flow through the coil, and positioning a part by using a displacement of the actuator, a displacement sensor (18) for detecting a displacement of the actuator, and a controller (6) for calculating the speed and acceleration of the actuator from the displacement detected by the displacement sensor, calculating a driving force of the actuator from the position, speed, and acceleration of the actuator and from an arbitrarily set external force, and outputting an electric current to be supplied to the coil which electric current corresponds to the calculated driving force.

Description

Precision positioning device

The present invention relates to an apparatus for precisely positioning a component such as a semiconductor component or the like mounted by a robot, for example.

When assembling semiconductor parts and precision parts manufactured by MEMS (Micro Electro Mechanical Systems) technology, precise positioning is required according to the parts, and contact of parts is detected accurately, resulting in excessive contact force. It is necessary to control the positioning so that it does not become.

As an example of an apparatus that performs such high-precision control, an arm that pressurizes a semiconductor element when mounted on a substrate is attached to an elastic guide constituted by a parallel leaf spring, and a pressure is applied by a voice coil motor. A configuration is known in which the applied pressure is controlled by adjusting the current flowing through the coil of the voice coil motor with a current regulator (see Patent Document 1).

In another example, a signal from a force sensor attached to the wrist of the robot is fed back to the servo control system (see Patent Document 2). In this example, while the robot is working, the position of the part is recognized and the success of the work is confirmed by monitoring the force, while compliance control is realized by feeding back the force information to the control system. Improve reliability.
JP-A-7-86317 Japanese Patent Laid-Open No. 7-24665

However, the conventional positioning control technology has the following problems.

In the technique of the above-mentioned Patent Document 1, it is possible to apply a precise pressing force when stationary, but it is difficult to control the contact force precisely by suppressing vibration during component transportation or moving while pressing. Moreover, in order to detect a contact, it is necessary to add another contact sensor.

In the technique of Patent Document 2, it is difficult to perform work while maintaining a minute contact force due to the influence of the mass of the arm and the frictional force of the speed reducer.

Also, in any of the techniques of

Patent Documents

1 and 2, the position changes or the contact force becomes excessive due to the influence of the mass of the robot's previous hand or jig. In order to avoid such collision due to excessive mass, the work speed must be reduced and the work must be performed carefully, and the work time increases accordingly.

An object of the present invention is to provide a precision positioning device that makes it possible to perform operations such as assembly while stably positioning even precise or minute parts.

The present invention is an apparatus for precisely positioning a component,
A voice that supports a coil placed in a magnetic field so as to be displaceable in a predetermined direction by an elastic guide member, drives an actuator including the coil by passing an electric current through the coil, and positions the component by the displacement of the actuator A coil motor;
A displacement sensor for detecting the displacement of the actuator;
The velocity and acceleration are calculated from the displacement detected by the displacement sensor, and the driving force of the actuator is calculated from the position, velocity and acceleration of the actuator and an external force set arbitrarily based on the impedance of the mechanical system including the actuator. And a controller for outputting a current to be supplied to the coil in accordance with the calculated driving force.

In the present invention, the controller calculates the velocity and acceleration from the displacement of the actuator including the coil placed in the magnetic field detected by the displacement sensor, and the position, velocity and acceleration of the actuator based on the impedance of the mechanical system including the actuator. Then, the driving force of the actuator is calculated from the arbitrarily set external force, and a current supplied to the coil is output according to the calculated driving force. In response to this output, the voice coil motor drives an actuator including the coil to position the component.

According to the present invention, by controlling the impedance from the position, velocity and acceleration, it is possible to execute precise positioning while maintaining a minute contact force. Further, more accurate positioning and load control can be realized by compensating for the effect of the deformation of the elastic guide member and the influence of the weight of the actuator including the robot hand and the jig.

Therefore, even when assembling work of precision or minute fragile parts, the work can be performed while positioning the parts stably. Therefore, in addition to the assembly of smile parts and fragile parts, positioning can be performed accurately while observing the collision force and contact force in the pressing and bonding work of electronic parts, and the working time can be shortened and stable work can be realized.

In the present invention, the controller includes a speed calculation unit that calculates a speed from the displacement detected by the displacement sensor, an acceleration calculation unit that calculates an acceleration from the speed, and feedback gains for position, speed, and acceleration that determine the impedance. An impedance control calculation unit that calculates the driving force from a value obtained by multiplying the position, speed, and acceleration of the actuator and an arbitrarily set external force value, and a current supplied to the coil in accordance with the driving force. It is preferable to include a drive current generation unit that generates the drive current.

According to this configuration, since the impedance control calculation unit performs calculation processing, the apparent mass and rigidity can be made smaller than actual, so that the impact at the time of collision can be reduced. If the rigidity is increased, positioning without contact can be performed accurately.

Further, it is preferable that the controller includes an external force estimation calculation unit that estimates and calculates an external force from the position and acceleration of the actuator and the driving force. According to this aspect, the control according to the work state can be realized by estimating and calculating the external force by the external force estimation calculation unit.

The external force estimation calculation unit calculates an external force estimation value from a value obtained by multiplying each design value of the mass of the actuator and the elastic coefficient of the elastic guide member by the position and acceleration of the actuator and the value of the driving force. It is preferable.

The external view of the apparatus which provides the compliance attached between the arm and hand of a robot. It is a figure which shows the structure of a voice coil motor, (a) is a top view, (b) is sectional drawing. Explanatory drawing of the mechanical model of an apparatus. The block diagram which shows the control system of 1st Embodiment. The block diagram which shows the control system of 2nd Embodiment. The block diagram which shows the control system of 3rd Embodiment. The graph which shows the time change of a position deviation, an acceleration deviation, and an external force estimated value as an impedance control simulation result of 3rd Embodiment. The graph which shows the time change of a speed and a driving force as an impedance control simulation result of 3rd Embodiment. The graph which shows the response of an actual mechanical system. The graph which shows the time change of a position deviation, an acceleration, and an external force estimated value as a position control simulation result of 3rd Embodiment. The graph which shows the time change of a speed and a driving force as a position control simulation result of 3rd Embodiment.

FIG. 1 shows a precision positioning device 4 for providing compliance attached between an arm 2 and a hand 3 of a robot 1 as an embodiment of the present invention. The device 4 includes a controller 6 (FIG. 4) in addition to the voice coil motor 5 (FIG. 4).

As shown in FIG. 2, the voice coil motor 5 includes a cylindrical casing 11 having an open top surface, a magnet 13 fixed to the inner side surface of the casing 11 together with the side wall of the annular groove-shaped yoke 12, The coil 15 wound around the bobbin 14 disposed so as to face the magnet 13, the cylindrical frame 16 having an open bottom surface disposed inside the yoke 12, and the upper and lower ends of the frame 16 together with the bobbin 14 are encased. An elastic guide member 17 made up of a plurality of arc-shaped flat springs supported in the body 11 and a displacement sensor 18 installed on the bottom surface of the housing 11 inside the gantry 16 are provided.

The proximity sensor, strain gauge, linear encoder, etc. are used for the displacement sensor 18.

According to the voice coil motor 5 having the above-described configuration, the gantry 16 is driven in the vertical direction together with the coil 15 by passing a current through the coil 15 placed in the magnetic field by the magnet 13. The displacement (position change) due to the vertical movement is measured by the displacement sensor 18.

The controller 6 calculates the speed from the change in the coil position indicated by the signal from the displacement sensor 18, calculates the acceleration from the change in the speed, and feeds back the position, speed, and acceleration, and the mechanical impedance corresponding to the work. And a motor drive current that flows through the coil 15 of the voice coil motor 5 is output according to the calculation result.

The external force estimation calculation unit 7 estimates and calculates an external force from the position measured by the displacement sensor 18 and the speed and acceleration calculated by the controller 6, as will be described later.

The operation of the control system of the present embodiment is executed by arithmetic processing based on the following dynamic model, which will be described below.

FIG. 3 shows a dynamic model of the present embodiment. In the figure, when the right direction of the actuator position x coordinate is positive (+), the equation of motion is expressed as follows.

f _a + f _d = m _a x ″ + k _a x (1)
However,
m _a : Mass of an actuator (including a hand) displaced by coil driving of the voice coil motor k _a : Spring constant of the actuator support spring f _a : Driving force generated by the actuator f _d : External force (gravity, contact force, etc.)
At this time, a driving force represented by the following equation is applied to the actuator.

f _a = −m _c x ″ −d _c x′−k _c x + f _c (2)
Here, x ", x 'is an actuator acceleration, respectively, represent the velocity, f _c is the force to be generated due to gravity offset and _{_{work, m c, d c, k}} c is the respective parameters determined arbitrarily, Each feedback gain of acceleration, speed, and position is represented.

From equations (1) and (2)
f _d = m _v x ″ + d _v x ′ + k _v x−f _c (3)
_{_{_{However, m v, d v, k}}} v represents the impedance of the dynamic model is expressed by the following equation.

m _v = m _a + m _c , d _v = d _c , k _v = k _a a + k _c (4)
That is, by appropriately setting the parameters m _c , d _c , and k _c , the impedance (m _v , d _v , k _v ) that determines the response of the mechanical system to the external force can be freely determined. At this time, if m _c and k _c are made negative, positive feedback is obtained, and the apparent mass and rigidity can be made smaller than actual. However, it is necessary to determine the impedance (m _v , d _v , k _v ) so that the entire system becomes stable.

For example, when obtaining a compliance characteristic suitable for soldering work, assuming that the stiffness k _v = 2500 N / m (displacement of 0.25 mm with an external force of 100 g) and the response frequency ωc = 20 Hz (126 rad / s), m _v = a _{^{k v / ωc 2 = 0.15 kg}} . If the actuator mass m _a = 1 kg, the acceleration feedback gain m _c = 0.85 kg. Speed feedback gain d _c is determined to be near the critical damping.

Further, when a sufficiently large value stiffness k _v relative to an external force, a position control. For example, when k _v = 10 ⁵ N / m, the displacement is 0.01 mm with respect to an external force of 100 g, and the rigidity is sufficient for normal positioning control. The acceleration and velocity feedback gains m _c and d _c are determined so that the operation becomes stable.

FIG. 4 is a block diagram showing the control system of the first embodiment of the present invention.

The controller 6 includes, as functional blocks, a speed calculation unit 21 that calculates a speed based on a signal from the displacement sensor 18, an acceleration calculation unit 22 that calculates an acceleration from a change in the speed, and a position indicated by a signal from the displacement sensor 18. x, calculated velocity x 'and the acceleration x ", the voice coil motor of the impedance control arithmetic unit 23 for calculating a driving force f _a to be applied to the actuator based on the equation (2), an actuator from the calculated driving force And a drive current generator 24 that generates 5 coil drive currents and supplies them to the voice coil motor 5.

Here, the impedance control calculation unit 23, the parameter m _c, d c representing the force f _c and the impedance necessary for the _operation, and a k _c, host controller (in this case, the robot controller) is provided from.

Note that the speed calculation unit 21 may obtain the speed by measuring the back electromotive force of the voice coil instead of from the output of the displacement sensor 18.

Further, as shown in FIG. 5 as the second embodiment, acceleration may be detected by an acceleration sensor 25 instead of the acceleration calculation unit 22 of the control system of the first embodiment. In this case, the speed calculation unit 21 may obtain the speed by integrating the signal (acceleration) of the acceleration sensor 25.

According to the feedback control system of FIG. 4, the speed x ′ is obtained by the speed calculator 21 from the change of the position x measured by the displacement sensor 18, and the acceleration x ″ is obtained by the acceleration calculator 22 from the speed. Further, according to the feedback control system of FIG. 5, the speed x ′ is obtained by the speed calculation unit 21 from the change of the position x measured by the displacement sensor 18, the acceleration sensor 25 detects the acceleration, and the acceleration x ″ is can get.

In any of the feedback control systems of FIGS. 4 and 5, the impedance control calculation unit 23 sets the position, velocity, and acceleration feedback gains m _c , d _c , and k _c to the above-described equations (2). position x of the actuator, the speed x ', and a value obtained by multiplying the acceleration x ", from the value of the force f _c which is set arbitrarily, in. the driving current generating unit 24 to the driving force f _a is calculated, A coil driving current is generated from the value of the driving force and supplied to the coil of the voice coil motor 5 as a control signal for the actuator.

FIG. 6 is a block diagram showing a control system of the third embodiment of the present invention.

In the third embodiment, the controller 6 includes an external force estimation calculation unit 7 that estimates and calculates an external force from the position and acceleration of the actuator and the driving force. The external force estimation calculation unit 7, the position x represented by the signal from the displacement sensor 18, the acceleration x "calculated by the acceleration calculator 22, and the driving force f _a calculated by the impedance control operation unit 23, the external force _fd is calculated.

This calculation is performed based on the following equation. That is, from the equation (1), f _d = m _a x ″ + k _a x−f _a (5)
Since it is, the position x and the acceleration x ", and knowing the driving force _{f a} of the actuator, can be computed external force _{f d.} However, _{m a} and _{k a} is the design value of compliance.

Therefore, the external force calculated by the external force estimation calculation unit 7 becomes an estimated value <f _d > and is sent to the host controller.

Here, simulation results of the computer controlled by the control system of FIG. 6 are shown as examples of impedance control and position control. Impedance control is intended to determine response characteristics (rigidity, damping, mass) in order to limit contact force, work force, etc. according to the work. Position control is highly accurate by increasing the position feedback gain. This is intended for positioning.
-Impedance control simulation results (Figs. 7 and 8)
7 and 8 show the case where the virtual mass m _c = 0.2 kg and the virtual spring constant k _c = 2000 N / m for the mechanical system with the mass m _a = 1 kg and the spring constant k _a = 1000 N / m. As a simulation result of the response, changes in position deviation, speed, acceleration, estimated external force value, and driving force over time (seconds) are shown.

Here, a virtual damper (velocity feedback gain) d _c is determined so that the critical damping. The input position x (command value) is kept constant, the external force (contact force, work force) gave step force of 1N as f _c. The estimated external force value <f _d > is also a 1N step value, which indicates that the estimation function is good.

For comparison, FIG. 9 shows changes in position deviation and time (in seconds) of acceleration as a response of a mechanical system having a mass of 0.2 kg and a spring constant of 2000 kg N / m. This indicates that the impedance control response is in good agreement with the actual mechanical response.

-Position control simulation results (FIGS. 10 and 11)
10 and 11 show the response of the mechanical system with mass m _a = 1 kg and spring constant k _a = 1000 N / m when the virtual spring constant k _c = 20000 N / m (position feedback gain 19000). As a simulation result, a positional deviation, speed, acceleration, estimated external force value, and time (second) change in driving force are shown.

Virtual damper d _c is defined so that the critical damping. The input position x (command value) was fixed at a position at a constant speed of 5 mm / s until 0.2 seconds later and at a position of 1 mm after 0.2 seconds. In addition, a step-like external force 1N was input at the start (0 second).

When moving at a constant speed, the speed is almost 5 mm / s, and when stopping, the position deviation is stable at 0.1 mm, and position control is performed. Position deviation can be reduced by raising the position feedback gain k _c. Further, the estimated external force disturbance value <f _d > is also a step value of 1N, indicating that the estimation function works well.

Finally, a part assembling work by the robot of FIG. 1, which is an example of using the precision positioning device 4 of the present invention, will be described. For example, when taking out a plate-like component such as a filter, the robot picks up a designated one of the filters stacked in the component supply magazine by hand. That is, the hand picks up and conveys plate-like components (filters) stacked in the component supply magazine by suction pads. As the operation of the robot, by moving the hand above the parts supply magazine and descending, by sucking the air in the suction pad using a vacuum pump etc. with the suction pad applied to the parts in the magazine, Adhere parts to the suction pad. Thereafter, the hand is raised and moved to the assembly position of the parts. When the filter is taken out in this way, the target command position in the pickup direction with respect to the hand is always set at the bottom of the magazine, and the command position is held halfway when the height can be detected after the work starts.

The above operations are executed according to a program stored in the controller of the robot body.

As mentioned above, although embodiment was described, this invention is not limited to this. For example, the elastic guide member is not limited to a plate-like spring, and may be operated by rolling or air pressure.

The present invention is useful for positioning in operations such as picking up, precision mounting, joining (for example, soldering), or bonding of semiconductor parts, MEMS parts, and other electronic parts.

Claims

An apparatus for precisely positioning a part,
A voice that supports a coil placed in a magnetic field so as to be displaceable in a predetermined direction by an elastic guide member, drives an actuator including the coil by passing an electric current through the coil, and positions the component by the displacement of the actuator A coil motor;
A displacement sensor for detecting the displacement of the actuator;
The speed and acceleration are calculated from the displacement detected by the displacement sensor, and the driving force of the actuator is calculated from the position, speed and acceleration of the actuator and an arbitrarily set force based on the impedance of the mechanical system including the actuator. And a controller for outputting a current to be supplied to the coil in accordance with the calculated driving force.
2. The precision positioning device according to claim 1, wherein the controller includes a speed calculator that calculates a speed from a displacement detected by the displacement sensor, an acceleration calculator that calculates an acceleration from the speed, and a position that represents the impedance. An impedance control calculation unit that calculates the driving force from a value obtained by multiplying each feedback gain of speed and acceleration by the position, speed, and acceleration of the actuator and a value of an external force that is arbitrarily set, and according to the driving force A precision positioning device comprising: a drive current generator for generating a current to be supplied to the coil.
3. The precision positioning device according to claim 1, wherein the controller includes an external force estimation calculation unit that estimates and calculates an external force from the position and acceleration of the actuator and the driving force.
4. The precision positioning device according to claim 3, wherein the external force estimation calculation unit calculates a value obtained by multiplying each design value of the mass of the actuator and an elastic coefficient of the elastic guide member by the position and acceleration of the actuator and the driving force. A precision positioning device that calculates an estimated external force value from the value of the above.