JP2014076497A - Articulated robot and semiconductor wafer carrier device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an articulated robot that is superior in accuracy of actions by suppressing deviation from a track.SOLUTION: An articulated robot includes: arm elements 11-13 which are connected to a plurality of joints in order; motors which change relative positions or attitudes of the arm elements 11-13; and a control part 3 which controls positions and attitudes of hand parts H provided at the arm element 13. The control part 3 includes: an orthogonal coordinate system reference command setting part 31 which obtain reference command values for controlling the positions or attitudes of the hand parts H as orthogonal coordinate system reference command values at least some of which are on an orthogonal coordinate system; an orthogonal coordinate system shaping command generation part 32 which generates orthogonal coordinate system shaping command values by performing predetermined input shaping on the orthogonal coordinate system reference command values obtained by the orthogonal coordinate system reference command setting part 31; and a joint coordinate system conversion command generation part 33 which generate joint coordinate system conversion command values by converting the orthogonal coordinate system shaping command values obtained by the orthogonal coordinate system shaping command generation part 32 to joint coordinate systems corresponding to the respective joints, the respective motors being controlled based on the joint coordinate system conversion command values.

Description

  The present invention is a multi-joint robot configured such that a plurality of arm elements are sequentially connected, and the position and posture of the hand part at the tip can be changed by relatively moving the arm elements for each joint by an actuator. The present invention relates to the semiconductor wafer transfer device used.

  Conventionally, many articulated robots have been known that can change the position and posture change of the hand part at the tip by sequentially connecting multiple arm elements with joints and controlling the actuators corresponding to each joint. It has been.

  The joints used in such articulated robots are classified into those that make the pair of arm elements move relatively linearly and those that rotate, and by combining these types and numbers, various kinds of movements can be performed. Is possible.

  Among multi-joint robots, so-called horizontal multi-joint robots and vertical multi-joint robots that have joints with a rotation mechanism such as a motor as an actuator are more widely used in the manufacturing industry. For example, in a semiconductor wafer transfer apparatus, a horizontal articulated robot as described in Patent Document 1 is preferably used, and each joint is mounted in a state where a semiconductor wafer is placed on a hand portion provided at the tip. Is driven to rotate so that the semiconductor wafer can be transported to a predetermined position.

  In order to cause such an articulated robot to perform a predetermined operation, it is necessary to control the actuators provided corresponding to the joints by integrating them with the control unit. At this time, a command signal suitable for each actuator is individually output from the control unit. That is, when the joint has a degree of freedom of rotation and a rotary motor such as a servo motor is used to operate the joint, the rotation angle or rotation angular velocity of the motor is output as a command signal, Will be performed. And in the robot of the type provided with three joints having the degree of freedom of rotation as described in the above-mentioned Patent Document 1, the same command signal as above for each of the motors corresponding to the three joints. It is possible to change the hand portion at the tip to a desired position and posture by applying a rotational motion.

  Articulated robots are generally required to reduce vibrations, and in particular, such demands are particularly great in fields requiring precision machining such as the above-mentioned semiconductor applications. At the same time, higher speed has been demanded for the purpose of shortening the transport time. However, when the operation speed is improved, a large acceleration tends to work and the residual vibration when the operation is stopped tends to increase. Therefore, it is necessary to reduce the residual vibration.

  Therefore, in the following Patent Document 2 and Non-Patent Document 1, a technique that uses input shaping control as a technique for suppressing vibration described above is disclosed. The input shaping control is sometimes referred to as pre-shaping control, but both are the same. In this input shaping control, the natural frequency up to the order to be controlled and the damping coefficient are identified as vibration characteristics unique to the device based on the vibration measurement value obtained by performing vibration measurement in advance, and the actuator A signal having an opposite phase corresponding to the reference command value to be given to the actuator is generated based on the natural frequency and the attenuation coefficient, and given to the actuator as a control command value superimposed on the reference command value. In this way, it is possible to obtain a vibration suppressing effect by performing the filter processing for changing the control command value given to the actuator to an appropriate value in advance.

JP2011-216729A Japanese Patent No. 3015396

Minh Duc Duong, Kazuhiko Terashima, Toshio Kamigaki, and HirotoshiKawamura “Development of a Vibration Suppression GUITool Based on Input Preshaping and its Application to Semiconductor WaferTransfer Robot” (Int.J.ofAutomation Technology Vol.2 No.6,2008)

  However, those described in Patent Document 2 and Non-Patent Document 1 show examples applied to a simple structure including only one actuator, such as the robot described in Patent Document 1, An example applied to one having a plurality of joints that can be used in an actual production line is not disclosed.

  Therefore, when the input shaping control described in Patent Document 2 and Non-Patent Document 1 is applied to an articulated robot such as Patent Document 1, rotation angles or rotation angular velocities respectively given to motors that drive the joints. It is conceivable that the filter processing related to the input shaping control is applied independently to the command values such as. By doing so, it is possible to obtain a vibration suppressing effect even in an articulated robot, as described above.

  However, when the filtering process is performed independently of the command value given to the actuator corresponding to the joint, the movement trajectory of the hand unit may be greatly different.

  Specifically, when the articulated robot to be controlled has a degree of freedom of rotation in a part of the joint, it is generally driven by a motor, so its rotation angle or rotation angular velocity, etc. Control is performed using as a command value. Therefore, the command value and the moving distance of the hand unit do not have a proportional relationship, and the influence of the filter processing related to the input shaping control differs for each joint. Therefore, even when a command value for operating in a straight trajectory is given to the hand unit, if the filter processing related to input shaping control is applied independently of the command value for each joint in order to suppress vibration, the hand part will deviate from the target trajectory. Will occur and the hand part will not be able to move linearly.

  For this reason, when the hand unit is operated linearly in the presence of obstacles such as other devices or wall surfaces, such as when the hand unit is inserted into another device, the hand is moved to these obstacles. It is conceivable that the parts collide and are damaged. In addition, when the hand unit operates while holding a workpiece such as a semiconductor wafer, the workpiece may collide with another device or a wall surface to be damaged.

  In addition to the above input shaping control, a similar problem may occur when other filter processing for vibration suppression is applied. Further, the same problem occurs even when the filtering process is performed based on different purposes such as optimization of the speed and acceleration of the hand unit as well as the purpose of suppressing vibration.

  An object of the present invention is to effectively solve the above-described problems. Specifically, the present invention suppresses an orbital deviation of an operation caused by performing input shaping with respect to a reference command value when the actuator is operated. It is another object of the present invention to provide an articulated robot and a semiconductor wafer transfer apparatus that can accurately maintain an operation trajectory while obtaining the effect of input shaping.

  In order to achieve this object, the present invention takes the following measures.

  That is, the articulated robot of the present invention includes an arm element that is sequentially connected by a plurality of joints that can move or rotate, an actuator that changes the relative position or posture of the arm element that is connected to each joint, and the actuator A control unit that controls the position and posture of the hand unit provided in the terminal arm element by performing control of the above, and at least one of the joints is a multi-joint robot having a degree of freedom of rotation, An orthogonal coordinate system reference command setting unit that obtains a reference command value for controlling the position or orientation of the hand unit as an orthogonal coordinate system reference command value at least a part of which is an orthogonal coordinate system; An orthogonal coordinate system shaping command generator that generates a rectangular coordinate system shaping command value by performing predetermined input shaping on the rectangular coordinate system reference command value obtained by the coordinate system reference command setting unit. A joint coordinate system conversion command generation unit that generates a joint coordinate system conversion command value obtained by converting the orthogonal coordinate system shaping command value obtained by the orthogonal coordinate system shaping command generation unit into a joint coordinate system corresponding to each joint; And each actuator is controlled on the basis of a joint coordinate system conversion command value obtained by the joint coordinate system conversion command generation unit.

  If comprised in this way, the shift | offset | difference of the operation | movement trajectory by performing input shaping can be suppressed, and it becomes possible to maintain the trajectory of the operation | movement of a hand part correctly, obtaining the effect by input shaping. For this reason, even when the hand unit is linearly operated in a narrow place, it is possible to prevent deviation from the target trajectory and to prevent contact with peripheral devices and walls.

  Furthermore, in order to achieve both the suppression of the vibration of the hand unit and the suppression of the trajectory deviation of the operation and enable the operation with higher positional accuracy, a predetermined input shaping performed by the orthogonal coordinate system shaping command generation unit is performed. It is preferable that the filter processing is performed to suppress the vibration of the hand unit.

  In addition, in order to realize vibration suppression and movement orbit shift suppression with higher accuracy, in order to increase the speed of control related to vibration suppression and increase the vibration suppression effect, the filter processing is used as input shaping control. It is preferable that the data processing is configured as follows.

  Further, by selecting an appropriate control command value according to the necessity of vibration suppression and the necessity of suppression of track deviation, in order to reduce unnecessary control and speed up the calculation process, The control unit generates a joint coordinate system reference command value as a reference command value to be given to each actuator, and the joint coordinate system reference command value obtained by the joint coordinate system reference command setting unit A joint coordinate system shaping command generation unit that performs predetermined input shaping to generate a joint coordinate system shaping command value, and a control command value switching unit that outputs a switching command to switch a control command value to be given to each actuator, In addition to the joint coordinate system conversion command value obtained by the joint coordinate system conversion command generation unit in response to a switching command from the control command value switching unit, the joint coordinate system reference command setting unit More resulting joint coordinate system reference command value, or, it is preferable to configured based on joint coordinate system shaping command value obtained by the joint coordinate system shaping command generating unit to perform control of each actuator.

  Further, in order to make it possible to select a control command value more easily and practically by making a determination of whether vibration suppression is necessary and whether or not to suppress trajectory deviation based on the presence or absence of a workpiece, When the hand unit does not hold a workpiece, instead of the joint coordinate system conversion command value obtained by the joint coordinate system conversion command generation unit, the joint coordinate system reference command value obtained by the joint coordinate system reference command setting unit It is preferable that the control command value switching unit is configured to output a switching command so that each actuator is controlled based on the control.

  Further, a semiconductor wafer device of the present invention includes the above articulated robot, and the articulated robot is configured as a horizontal articulated robot, and the semiconductor wafer is placed on the hand unit while the semiconductor wafer is placed on the hand unit. The semiconductor wafer transfer apparatus is configured to perform transfer. With this configuration, a semiconductor wafer transfer apparatus that requires precise operation can be effectively realized.

  According to the present invention described above, the deviation of the trajectory of the hand portion caused by performing the input shaping with respect to the reference command value for operating the actuator is suppressed, and the trajectory can be accurately obtained while obtaining the effect of the input shaping. It becomes possible to provide an articulated robot and a semiconductor wafer transfer device that can be maintained.

The top view of the articulated robot which concerns on 1st Embodiment of this invention, and a semiconductor wafer conveyance apparatus provided with the same. The block diagram which shows the same articulated robot typically. The top view which shows typically the structure of the arm element in the articulated robot. The block diagram which shows typically the drive means of each joint in the articulated robot. Explanatory drawing which shows the definition of the coordinate of each joint in the same articulated robot. The flowchart which shows the procedure which determines the command value to the motor which drives each joint. The flowchart which shows the procedure which calculates an input shaping control command. Explanatory drawing which compares and shows the X coordinate orbit at the time of performing the linear motion to a Y direction before and after application of this invention. Explanatory drawing which compares and shows the Y coordinate orbit corresponding to FIG. 8 before and after application of this invention. Explanatory drawing which compares and shows attitude | position alpha track | orbit corresponding to FIG. 8 and 9 before and after this invention application. Explanatory drawing which compares the XY in-plane track | orbit corresponding to FIGS. 8-10 before and after applying this invention. Explanatory drawing which compares and shows the residual vibration at the time of performing the operation | movement which concerns on FIGS. Explanatory drawing which compares the track | orbit in XY plane at the time of making the linear motion to a direction different from FIGS. 8-12 before and after application of this invention. The block diagram which shows typically the articulated robot which concerns on 2nd Embodiment of this invention. The flowchart which shows the procedure which determines the command value to the motor which drives each joint in the articulated robot. The flowchart which shows the procedure which calculates an input shaping control command based on the track | orbit data of a joint coordinate system. Explanatory drawing which shows the joint coordinate system track | orbit of the 1st link at the time of making the linear motion to a Y direction as a comparative example with this invention before and after input shaping control application. Explanatory drawing which shows the joint coordinate system track | orbit of the 2nd link corresponding to FIG. 17 before and after application of input shaping control as a comparative example with this invention. Explanatory drawing which shows the joint coordinate system track | orbit of the 3rd link corresponding to FIG. 17 and 18 before and after input shaping control application as a comparative example with this invention. FIG. 20 is an explanatory diagram showing an XY in-plane trajectory corresponding to FIGS. 17 to 19 before and after application of input shaping control as a comparative example with the present invention.

Embodiments of the present invention will be described below with reference to the drawings.
<First Embodiment>

  FIG. 1 is configured as a semiconductor wafer transfer device TD including the multi-joint robot 1 according to the first embodiment. The articulated robot 1 is connected to the load ports LP1 to LP4 via the frame Fr, and can replace the wafer (semiconductor wafer) W accommodated in the load ports LP1 to LP4. Yes.

  The load ports LP1 to LP4 are arranged in a row while facing the articulated robot 1, and the position of the articulated robot 1 is set to be intermediate between the load ports LP1 and LP2.

  Here, in the present invention, the direction in which the load ports LP1 to LP4 are arranged, that is, the right direction in the figure is defined as the X direction, and the direction orthogonal thereto, that is, the upward direction in the figure is defined as the Y direction. Then, the vertical upward direction, that is, the front side of the page is defined as the Z direction. Further, a counterclockwise direction with respect to the X axis in plan view is defined as an α direction.

  In the drawing, the black circle mark described inside the wafer W is the center position of the wafer W, and becomes the reference position Pw when the articulated robot 1 is controlled. The black circles described in the load ports LP1 to LP4 indicate the transfer destination of the wafer W, and the above-mentioned reference position Pw is made to coincide with these positions.

  The configuration of the articulated robot 1 is shown in FIG. The articulated robot 1 is roughly composed of a mechanical device unit 2 and a control unit 3, and the mechanical device unit 2 operates based on a control command value given from the control unit 3.

  First, the configuration of the mechanical unit 2 will be described with reference to FIG. The mechanical device unit 2 is configured as a horizontal articulated type including a first arm element 11, a second arm element 12, and a third arm element 13 that are sequentially connected from the base 4 via joints J1, J2, and J3. The arm elements 11 to 13 are rotatable in a plane parallel to the XY plane and shifted in the Z direction.

  Specifically, the first arm element 11 is provided at a predetermined position on the base 4 so as to be rotatable via a first joint J1 having a degree of freedom of rotation about the rotation axis ST. The second arm element 12 is rotatably provided at the tip of the first arm element 11 via a second joint J2 having a degree of freedom of rotation about the rotation axis SR. Further, a third arm element 13 is rotatably provided at the tip of the second arm element 12 via a third joint J3 having a degree of freedom of rotation about the rotation axis SH. The rotation axes ST, SR, SH are set so as to be parallel to each other, and as a result, the first to third arm elements 11 to 13 are rotated in a plane parallel to each other. Yes. Further, since the first to third arm elements 11 to 13 and the first to third joints J1 to J3 do not interfere with each other because they are provided at positions shifted in the Z direction, the rotations of each other are prevented. There is no such thing.

  A U-shaped hand portion H is provided at the distal end of the third arm 13 which is the end so as to open the distal end side, and operates integrally with the third arm 13. A wafer W as a workpiece can be held on the hand portion H, and the reference position Pw is set near the center of the U-shape.

  In terms of the mechanism, the first link 11L forms the first link 11L from the rotation axis ST that is the center of the first joint J1 to the rotation axis SR that is the center of the second joint J2, and is first from the rotation axis SR that is the center of the second joint J2. The second link 12L is configured up to the rotation axis SH that is the center of the three joints J3. Similarly, the third link 13L is considered from the rotation axis SH that is the center of the third joint J3 to the reference position Pw.

  Corresponding servo motors M1 to M3 are incorporated in the first to third joints J1 to J3, respectively. The first servo motor M1 regulates the rotation angle of the first arm element 11 relative to the base 4 through the control command value because the fixed part is attached to the base 4 and the rotating part is attached to the first arm element 11. become. The second servo motor M2 has a fixed part attached to the first arm element 11 and a rotating part attached to the second arm element 12, so that the second arm element 12 with respect to the first arm element 11 is controlled with respect to the first arm element 11 through a control command value. The rotation angle is regulated. The third servo motor M3 has a fixed part attached to the second arm element 12 and a rotating part attached to the third arm element 13, so that the third arm element 13 relative to the second arm element 12 is controlled through a control command value. The rotation angle is regulated.

  As shown in FIG. 4, the servo motors M <b> 1 to M <b> 3 are driven by being appropriately given a control command value from the control unit 3 for each sampling period. The control command value is given as an angle command to the servo drivers D1 to D3, and the servo drivers D1 to D3 appropriately apply power in a format suitable for the motors M1 to M3. It is also preferable to provide a reduction gear between the motors M1 to M3 and the joints J1 to J3. In the present embodiment, the angle command is used as the control command value. However, an angular velocity command may be used instead of the angle command, and these may be appropriately set in consideration of the ease of setting by the servo driver. It is preferable to change.

FIG. 5 schematically shows the first to third links 11L to 13L described above. Here, the length of each link 11L~13L and _{L 1,} L 2, _{L 3,} respectively. In the present embodiment, the first link 11L and the second link 12L are set to have the same length (L ₁ = L ₂ ), and the length L ₃ of the third link 13L is set for these. It is set to about 80%, and the length to the tip of the wafer W when holding the wafer W (see FIG. 3) in the hand portion H is made equal to that of the first link 11L and the second link 12L. Yes. In this way, the wafer W can be freely operated in a wide area. Note that the relationship between L _{1 to} L ₃ is not limited to the above, and setting L ₁ and L ₂ to be different (L ₁ ≠ L ₂ ) also makes L ₃ larger than these (L ₃ > L ₂ , L ₃ > L ₁ ) can also be set.

Base portion 4 of the first link 11L for (see FIG. 3) relative angle theta _1, the relative angle theta ₂ of the second link 12L relative to the first link 11L, a relative angle theta ₃ of the third link 13L with respect to the second link 12L, If determined by controlling the motors M1 to M3, the absolute position of the reference position Pw in the hand portion H can be determined. Coordinates x, y on the XY plane of the reference position Pw can be expressed by relative angles θ ₁ , θ ₂ , θ ₃ by kinematic transformation described later. Similarly, the absolute angle α of the third link 13L as the posture of the hand portion H can also be determined by the relative angles θ ₁ , θ ₂ , θ ₃ .

  Next, returning to FIG. 2, the configuration of the control unit 3 will be described.

  The control unit 3 includes an orthogonal coordinate system reference command setting unit 31, an orthogonal coordinate system shaping command generation unit 32, a joint coordinate system conversion command generation unit 33, and a vibration characteristic storage unit 34. In each information processing apparatus such as a personal computer equipped with a CPU, ROM, various interfaces, etc., each of these units outputs a control command value by executing a control command value generation routine shown in FIGS. 6 and 7 stored in advance. The operation until the control and command values are generated and given to the motors M1 to M3 (see FIG. 3) is realized by cooperation of software and hardware.

In the Cartesian coordinate system reference command setting unit 31, the trajectory data C _ref = (x, y) of the hand unit H expressed in the Cartesian coordinate system, which will be described later, as a reference command value serving as a reference for determining a specific control command value. , Α). In the orthogonal coordinate system shaping command generation unit 32, the natural frequency and attenuation coefficient stored in the vibration characteristic storage unit 34 with respect to the trajectory data C _ref = (x, y, α) of the hand unit H described above. , While performing data processing as filter processing related to input shaping control based on these, input shaping is performed, and an orthogonal coordinate system shaping command value is generated. Here, input shaping refers to processing for shaping the waveform of an input signal used for control into a different waveform, and is used in a concept including both processing using a digital signal and an analog signal. Further, the joint coordinate system conversion command generation unit 33 converts the orthogonal coordinate system shaping command value into a joint coordinate system, which will be described later, and generates a joint coordinate system conversion command value. The joint coordinate system conversion command value generated here is given to the servo drivers D1 to D3 as a control command value P _shape for driving the motors M1 to M3.

  Since the input shaping control itself is a known technique, a detailed description thereof is omitted, but this articulated robot 1 is also introduced for the purpose of suppressing vibration of the hand portion H. Since the input shaping control can be realized as a sensorless configuration as a kind of feedforward control, it can be easily introduced by changing only the control unit of the existing articulated robot. Further, since complicated control is not required, it is possible to obtain a vibration suppressing effect while achieving stable control and high speed.

Before describing the detailed processing procedure in the control unit 3, the angles (θ _{1 to} θ ₃ ) of the links 11L to 13L used as variables in the present invention and the position and orientation (x, y, α) of the hand unit H are described. Explain the relationship.

The orthogonal coordinate system reference command setting unit 31 shown in FIG. 2 sets the reference position Pw of the hand unit H as coordinate data (x, y) on the XY plane as a target value for operating the hand unit H. The posture of the part H is set as rotation angle data (α) on the XY plane. That is, by these, the absolute position and orientation of the hand portion H are shown, and these are collectively referred to as trajectory data C _ref = (x, y, α) of the hand portion H expressed in an orthogonal coordinate system.

As described above, the position and orientation of the hand portion H can also be expressed by the rotation angles θ _{1 to} θ ₃ and the lengths L _{1 to} L _{3 of the} links 11L to 13L shown in FIG. Since the lengths L _{1 to} L ₃ of 11L to 13L are fixed values, the rotation angles θ _{1 to} θ ₃ of the links 11L to 13L, that is, the relative rotations of the links 11L to 13L at the joints J1 to J3 after all. Only the angles θ _{1 to} θ ₃ can be represented as variables. Therefore, these rotation angles θ _{1 to} θ ₃ are collectively referred to as trajectory data P _ref = (θ ₁ , θ ₂ , θ ₃ ) of the hand portion H expressed in the joint coordinate system. In the case where a speed reducer (not shown) is used between the motors M1 to M3 and the joints J1 to J3, the rotation angles θ _{m1 to} θ _{m3 of} the motors M1 to M3 corresponding to the joints J1 to J3. Then, using the reduction ratios Ra _{1 to} Ra ₃ , the angles θ ₁ to θ ₃ can be expressed as in the following equation.

As described above, the trajectory data C _ref in the Cartesian coordinate system and the trajectory data P _ref in the joint coordinate system indicate the same thing. Can be used to convert the trajectory data P _ref in the joint coordinate system into the trajectory data C _ref in the orthogonal coordinate system.

Similarly, when the trajectory data C _ref in the Cartesian coordinate system is converted to the trajectory data P _ref in the joint coordinate system, the inverse kinematic transformation is performed using the following mathematical formulas 5 to 7. it can.

Theta ₁ As indicated by the above equation is obtained two solutions. In general, one of the solutions may be selected according to the movable range of the first joint J1 and the operation before and after.

  Hereinafter, the procedure for determining command values to be given to the motors M1 to M3 in the control unit 3 will be described using FIGS. 6 and 7 with reference to FIG.

In the present embodiment, like the general horizontal articulated robot, the trajectory data _Pref of the joint coordinate system is given as the trajectory data of the hand portion H. Therefore, as the first step ST1 of the process, the Cartesian coordinate system reference command setting unit 31 converts the joint coordinate system trajectory data P _ref into the Cartesian coordinate system trajectory data C _ref and sets it as a reference command value. Of course, it is also possible to provide the trajectory data C _ref of the orthogonal coordinate system in the XY plane from the beginning, and set it as the reference command value as it is.

Next, in step ST2, the trajectory data C _ref of the orthogonal coordinate system is set as a command u ₀ before the input shaping control is applied, and the time series data number m is set as n ₀ .

In step ST3, the orthogonal coordinate system shaping command generation unit 32 performs data processing as filter processing related to input shaping control based on the trajectory data C _ref of the orthogonal coordinate system to obtain an orthogonal coordinate system shaping command value. to the generating an input shaping control command u _M. The calculation of the input control command u _M is executed by a specific process described later as a subroutine using the natural frequency and damping coefficient data stored in the vibration characteristic storage unit 34 (see FIG. 7).

Finally, in step ST4, the joint coordinate system conversion command generating unit 33, the inverse kinematics transformation described above the input control command u _M as the orthogonal coordinate system shaping command value into a joint coordinate system, the joint coordinate system transformation A motor pulse command P _shape is generated as a command value.

The motor pulse command P _shape is given to the corresponding servo drivers D1 to D4 (see FIG. 4) as control command values for the motors M1 to M3 as described above, and each motor M1 to M3 is driven to drive each of the motor pulses M1 to M3. The arm elements 11 to 13 are rotated, and the hand portion H performs a predetermined operation.

Prior to the description of the processing procedure relating to the calculation of the input control command u _M described above, calculation formulas used for filter processing as input shaping control will be described.

calculation formula control command u _k in consideration of the vibration suppression to k-th order mode becomes the following equation. Here, u _k [i] indicates the i-th position command data in consideration of suppression of vibration suppression. U ₀ [i] is the i-th position command data before damping control, n ₀ is the number of time-series data of the position command data, f _k is the natural frequency of the k-order mode, and ζ _k is the attenuation of the k-order mode. Represents a coefficient.

As can be seen from the above equation, the calculation for calculating the control command uk is performed by obtaining the primary mode command u ₁ [i] and the secondary mode command u ₂ [i] in this order. Note that Round () in the above equation is a function that rounds the numerical value in () to the integer.

Figure 7 illustrates a performs filter processing as input shaping control described above, to calculate the input control command u _M process.

  Normally, the control command calculates the previous command while performing the transport operation in order to shorten the overhead time before the transport. In the calculation flow, in order to reduce the calculation load during operation, the coefficient of the command calculation formula is calculated in advance in the first processing group GS1 as preprocessing. Then, in the second processing group GS2, a part of the control command value at the beginning of the operation is calculated in advance, and the remaining part is sequentially calculated during the operation.

Specifically, the first processing group GS1 includes a plurality of processing steps ST11 to ST15. First, 1 is given to the variable k as an initial setting (step ST11). Next, A _k , T _k , n _k (A ₁ , T ₁ , n ₁ ) are calculated using the equation described in Equation 8 (step ST12). Next, 1 is added to the variable k (step ST13), and the set value M as the vibration suppression target mode order is compared with the variable k to determine whether the variable k is equal to or less than M (step ST14). ). If the variable k is less than or equal to M, the process returns to step ST12, and A _k , T _k , and _nk are calculated again. The processing from step ST12 to step ST14 is repeated, and when it is determined in step ST14 that the variable k exceeds M, in the next step ST15, the value of n _k indicating the number of time-series data is set to the variable m _all. Set to.

  Up to this point, the first processing group GS1 is configured as preprocessing, and subsequently, processing for giving 1 to the variable i is performed as step ST16.

Thereafter, the second processing group GS2 including steps ST17 to ST23 is executed. First, 1 is given to the variable k as an initial setting (step ST17). Next, u _k [i] is calculated using the equation of Equation 8 (step ST18). Next, 1 is added to the variable k (step ST19), and the set value M is compared with the variable k to determine whether or not the variable k is equal to or less than M (step ST20). If the variable k is less than or equal to M, the process returns to step ST17, and u _k [i] is calculated again using the previously obtained u _k−1 [i]. The processes from step ST17 to step ST20 are repeated, and when it is determined in step ST20 that the variable k exceeds M, in the next step ST21, u _k [i] finally obtained is input shaping control. To the i-th shaping command value u _M [i] (step ST21). Next, 1 is added to the variable i (step ST22), and it is determined whether the variable i is equal to or less than the above m _all (step ST23). If the variable i is less than or equal to m _all , the processing from step ST17 to step ST22 is repeated, and u _M [i] corresponding to the variable i is changed until the variable i changes from 1 to m _all . Continue to calculate. If it is determined in step ST23 that the variable i exceeds m _all , all these processes are terminated.

  The calculation flow for performing the filtering process as the input shaping control as shown in FIG. 7 is applied to both the control command value of the joint coordinate system and the control command value of the orthogonal coordinate system. It is possible.

  Examples of operating the articulated robot 1 of the present embodiment configured as described above are shown in FIGS. Here, a target value is set so that the posture of the hand portion H is α = 90 °, that is, the hand portion H is linearly operated in the Y direction while maintaining the state in which the tip is directed in the Y direction. The operation is performed.

To distinguish each coordinate system, showing the data viewed the input shaping control command u _M chronologically in Figure 8-12. In FIG. 8, time series data of x in the rectangular coordinate system reference command value described as the pre-control command, and x in the orthogonal coordinate system shaping command value obtained by applying the filter processing related to the input shaping control to the reference command value. The time-series data of are superimposed. As can be seen from the figure, both X-coordinate trajectories have commands that keep almost constant values. There is almost no difference between them, and the change in the X direction due to input shaping control is can not see.

  Similarly, FIG. 9 shows time series data of y in the orthogonal coordinate system reference command value described as the pre-control command, and an orthogonal coordinate system shaping command in which the filter processing related to the input shaping control is applied to this reference command value. The time series data of y in the values are shown superimposed. As can be seen from the figure, by performing input shaping control, the operation is performed slightly later than the target in the Y direction.

  FIG. 10 shows time series data of α in the orthogonal coordinate system reference command value described as the pre-control command, and α in the orthogonal coordinate system shaping command value obtained by applying the filter processing related to the input shaping control to the reference command value. The time-series data are superimposed and shown. As can be seen from the figure, there is almost no difference between the two, and no change in the posture of the hand portion H due to the input shaping control being performed.

  FIG. 11 shows a plot of the trajectory of the hand portion H on the XY plane based on the orthogonal coordinate system shaping command value obtained as described above. As described above, the effect of performing the input shaping control only occurs in the Y-axis direction. Therefore, although there is a slight time delay, a linear trajectory can be obtained without change before and after the application of the input shaping control. it can.

  As a comparative example with these, the result of causing the hand unit H to perform the linear motion in the Y direction similar to the above using only the command value of the joint coordinate system is shown.

17, with respect to the rotation angle theta ₁ of the first link 11L of the joint coordinate system reference command value, and shows the application of the before and after change of the input shaping control. It can be seen that there is a delay after application with respect to the target value before application.

Similarly, FIG. 18, with respect to the rotation angle theta ₂ of the second link 12L as a joint coordinate system reference command value, and shows the application of the before and after change of the input shaping control. Even in this case, a delay occurs after application with respect to the target value before application.

Similarly, FIG. 19, with respect to the rotation angle theta ₃ of the third link 13L as a joint coordinate system reference command value, and shows the application of the before and after change of the input shaping control. Even in this case, a delay occurs after application with respect to the target value before application.

  FIG. 20 shows the trajectory of the hand portion H on the XY plane obtained based on the joint coordinate system command value after the input shaping control is applied. In this case, it can be seen that the input trajectory control greatly shifts the midway trajectory in the X direction. In such a case, problems such as collision with surrounding obstacles may occur.

  FIGS. 8A to 11D in the present embodiment, the operations according to FIGS. 17 to 20 in the comparative example, and the residual vibration immediately after executing the operation before applying the input shaping control are overlapped. 12 shows. It can be seen that the vibrations in the present embodiment and the comparative example are much smaller than those at the beginning compared with those before the input shaping control is applied, and are quickly damped. That is, it can be said that both have the effect of vibration suppression by the input shaping control. With the articulated robot 1 according to the present embodiment, it is possible to effectively suppress vibration while operating the arm by performing simple and high-speed arithmetic processing that is a feature of the input shaping control. By combining the vibration reduction effect and the movement trajectory deviation suppression effect, it is possible to realize a more precise operation of the hand portion H.

  FIG. 13 shows an operation example different from the above in the multi-joint robot 1 of the present embodiment. Here, the hand portion H is set in an orientation where α = 80 °, and the hand portion H is linearly operated in the orientation. Even when such an operation is performed, a linear operation is possible with almost no change before and after the input shaping control is applied, as in the case of FIG.

  As described above, the articulated robot 1 according to this embodiment includes the arm elements 11 to 13 sequentially connected by the plurality of joints J1 to J3 and the relative positions of the arm elements 11 to 13 connected to the joints J1 to J3. Alternatively, the motors M1 to M3 that change the posture, and the control unit 3 that controls the position and posture of the hand portion H provided in the terminal arm element 13 by controlling the motors M1 to M3, and The joints J1 to J3 are multi-joint robots 1 having a degree of freedom of rotation, and the control unit 3 is orthogonal so that at least a part of the reference command value for controlling the position or posture of the hand unit H is an orthogonal coordinate system. An orthogonal coordinate system reference command setting unit 31 obtained as a coordinate system reference command value, and an orthogonal coordinate system shaping command by performing predetermined input shaping on the orthogonal coordinate system reference command value obtained by the orthogonal coordinate system reference command setting unit 31 Cartesian coordinate system shaping command generation unit 32 for generating a value, and joint coordinate system conversion obtained by converting the rectangular coordinate system shaping command value obtained by the rectangular coordinate system shaping command generation unit 32 into a joint coordinate system corresponding to each joint J1 to J3 A joint coordinate system conversion command generation unit 33 that generates a command value, and controls each of the motors M1 to M3 based on the joint coordinate system conversion command value obtained by the joint coordinate system conversion command generation unit 33. It is composed.

  By doing so, it is possible to suppress the deviation of the motion trajectory due to the input shaping, and it is possible to accurately keep the motion trajectory while obtaining the effect of the input shaping. For this reason, even when the articulated robot 1 is used in a narrow place, it is possible to prevent the semiconductor wafer W as the hand portion H or the workpiece from coming into contact with peripheral devices or walls.

  In addition, since the predetermined input shaping performed by the orthogonal coordinate system shaping command generation unit 32 is a filter process for suppressing the vibration of the hand unit H, both vibration suppression and suppression of the trajectory deviation of the operation are made compatible. Thus, it is possible to perform an operation with higher positional accuracy.

  In addition, since the filter processing is data processing as input shaping control, vibration suppression control can be performed efficiently at high speed, and vibration suppression and suppression of trajectory deviation of operation can be realized with higher accuracy. Is possible.

Further, the semiconductor wafer device TD of the present embodiment includes the articulated robot 1 configured as a horizontal articulated robot as described above, while placing the semiconductor wafer W on the hand portion H, Since the transfer is performed, it is possible to effectively realize the semiconductor wafer transfer apparatus TD that requires a precise operation by utilizing the above-described effects, and can be used for high-precision processing of the semiconductor wafer W. It becomes.
Second Embodiment

  FIG. 14 shows an articulated robot 101 according to the second embodiment, which is different from that according to the first embodiment only in a part of the configuration of the control unit 103. Therefore, the same parts as those in FIG.

  Similar to the first embodiment, the control unit 103 includes an orthogonal coordinate system reference command setting unit 31, an orthogonal coordinate system shaping command generation unit 32, a joint coordinate system conversion command generation unit 33, and a vibration characteristic storage unit 34. Furthermore, a control command value switching unit 141, a joint coordinate system reference command setting unit 142, and a joint coordinate system shaping command generation unit 143 are provided.

  The control command value switching unit 141 selects an appropriate command value calculation processing method in accordance with the presence or absence of the wafer W on the hand unit H or a command signal given from the outside. Therefore, which control command value is used for calculation and control is output to each unit as a switching command. According to the selection in the control command value switching unit 141, a general control method that is a joint coordinate system and that does not apply input shaping control, a control method that applies input shaping control in a joint coordinate system, and a first implementation The control method can be changed among the three control methods for converting to the joint coordinate system after applying the input shaping control in the orthogonal coordinate system described as the form.

Therefore, the joint coordinate system reference command setting unit 142 can set a reference command value for the joint coordinate system. The joint coordinate system shaping command generation unit 143 performs data processing as filter processing related to input shaping control based on the joint coordinate system reference command value _Pref obtained by the joint coordinate system reference command setting unit 142. Is possible. The joint coordinate system reference command setting unit 142 and the Cartesian coordinate system reference command setting unit 31 may set different data independently, or by kinematic conversion or inverse kinematic conversion based on each other's data. It is also possible to generate it.

  The control unit 103 determines command values for the motors M1 to M3 that drive the joints J1 to J3, according to the processing procedure shown in FIG.

First, as step ST101, the control command value switching unit 141 determines whether to enable or disable the vibration suppression control. In this case, it is appropriate to use whether or not the wafer W is held on the hand portion H, and by doing so, unnecessary calculation processing can be omitted and higher speed can be achieved. It is also preferable to automatically perform such processing. If it is determined that the vibration suppression control is invalidated, the process proceeds to the next step ST102, and the joint coordinate system reference command value P _ref is used as it is as a control command value (position command) for the motors M1 to M3. .

If it is determined in step ST101 that vibration suppression control is to be enabled, the process proceeds to step ST103. In step ST103, on the assumption that the input shaping control is applied, it is selected whether to perform the joint coordinate system reference command _Pref or the orthogonal coordinate system reference command _Cref . In this case, it is preferable to determine whether or not the deviation of the trajectory is permitted, considering whether or not there is an obstacle around the hand portion H.

If it is determined in step ST103 that the orthogonal coordinate system is to be applied, assuming that the deviation of the trajectory is not permitted, the process proceeds to step ST106. In step ST106, after applying the input shaping control using the orthogonal coordinate system reference command value C _ref described in the first embodiment described above, the input shaping control command P _shape is obtained by converting to the joint coordinate system. It is the same processing. Therefore, a detailed description of the processing procedure is saved. The input shaping control command P _shape thus obtained is set as a control command value (position command) to the motors M1 to M3 in step ST105 and used for control.

If it is determined in step ST103 that the joint coordinate method is to be applied, it is determined that the deviation of the trajectory of the hand portion H is allowed, and the process proceeds to step ST104. In step ST104, an input shaping control command P _shape is obtained by calculation by a specific process shown in FIG. 16 based on the joint coordinate system reference command value P _ref . The input shaping control command P _shape thus obtained is also set as a control command value (position command) to the motors M1 to M3 in step ST105 and used for control.

In the procedure of obtaining the input shaping control command P _shape from the joint coordinate system reference command value P _ref , first, as shown in FIG. 16, first set in the joint coordinate system reference command setting unit 142 as the first step ST111 of the process. The trajectory data P _ref as the joint coordinate system reference command value is set as the command u ₀ before the input shaping control is applied, and the time series data number m is set as n ₀ .

Then, in step ST 112, the joint coordinate system shaping command generating unit 143 performs an input shaping by performing data processing as the filtering of input shaping control based on trajectory data P _ref of the joint coordinate system, the joint generating an input shaping control command u _M as the coordinate system shaping command value. The calculation of the input control command u _M is executed by the above-described processing shown in FIG. 7 using the natural frequency and damping coefficient data stored in the vibration characteristic storage unit 34.

Returning to FIG. 16, finally, in step ST113, the input control command u _M obtained as the joint coordinate system shaping command value is set as the joint coordinate system conversion command value in the motor pulse command P _shape .

  With the above configuration, the hand unit H can be operated while appropriately switching the control method by the control command value switching unit 141.

  As described above, in the present embodiment, by providing the configuration of the above-described first embodiment, the same effect can be obtained, and the following features are also provided.

  That is, the articulated robot 101 in this embodiment includes a joint coordinate system reference command setting unit 142 that generates a joint coordinate system reference command value as a reference command value that the control unit 103 should give to each of the motors M1 to M3, and joint coordinates. A joint coordinate system shaping command generation unit that generates a joint coordinate system shaping command value by performing a filtering process related to input shaping control as predetermined input shaping on the joint coordinate system reference command value obtained by the system reference command setting unit 142 143 and a control command value switching unit 141 that outputs a switching command to switch the control command value to be given to each of the motors M1 to M3, and according to the switching command from the control command value switching unit 141, Instead of the joint coordinate system conversion command value obtained by the coordinate system conversion command generation unit 143, it is obtained by the joint coordinate system reference command setting unit 142. Joint coordinate system reference command value, or is obtained by constituting the joint coordinate system shaping command value obtained by the joint coordinate system shaping command generating unit 143 based on to perform control of each motor M1 to M3.

  Because of this configuration, selecting appropriate control command values according to the necessity of vibration suppression and the need to suppress orbital deviation reduces unnecessary control and speeds up the calculation process. Thus, the articulated robot 1 can be speeded up.

  When the hand unit H does not hold the wafer W, the joint coordinates obtained by the joint coordinate system reference command setting unit 142 instead of the joint coordinate system conversion command value obtained by the joint coordinate system conversion command generation unit 33. Since the control command value switching unit 141 outputs a switching command so as to control each of the motors M1 to M3 based on the system reference command value, appropriate control is performed depending on the presence or absence of the workpiece W to be held. The command value can be selected, and convenience can be further improved.

  It is also preferable to configure as a semiconductor wafer transfer device TD provided with the multi-joint robot 101 described above.

  The specific configuration of each unit is not limited to the above-described embodiment.

  For example, although the multi-joint robots 1 and 101 in the above-described embodiment are of the three-link system in which all the joints J1 to J3 have rotational degrees of freedom, the effect of the present invention is that the rotational degrees of freedom are three. The invention is not limited to those having one, but can be obtained in the same way even when one has one or more degrees of freedom of rotation and the others have degrees of freedom of linear motion. That is, the present invention includes a plurality of movable elements such as a plurality of arms (links) and a linear motion portion that are driven by a plurality of joints that can move or rotate linearly, and at least one of the joints has a degree of freedom of rotation. If it has, it can apply and can obtain the above-mentioned effect.

  Further, the actuator for driving the joint is not limited to the motor, and the same effect can be obtained as long as it is rotationally driven.

  In the above-described embodiment, the hand portion H provided at the tip of the multi-joint robot 1, 101 is formed in a substantially U shape, and a wafer (semiconductor wafer) W as a workpiece is placed on the upper surface thereof. However, the hand portion H is not limited to this, and can be changed to various shapes and configurations.

  Moreover, after performing predetermined input shaping on the orthogonal coordinate system reference command value, the effect of suppressing the shift of the trajectory of the hand portion H by converting to the joint coordinate system and generating the joint coordinate system command value is In addition to the filter processing related to input shaping control, it is possible to obtain the same in the case of using other filter processing such as a low-pass filter and a notch filter, and it is possible to operate in a trajectory that matches the target. In addition to the filter processing for suppressing vibration, various input shapings having other purposes can be used.

  Other configurations can be variously modified without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Articulated robot 2 ... Machine apparatus part 3 ... Control part 11 ... 1st arm element 12 ... 2nd arm element 13 ... 3rd arm element 31 ... Orthogonal coordinate system reference command setting part 32 ... Orthogonal coordinate system shaping command generation part 33 ... Joint coordinate system conversion command generation unit 141 ... Control command value switching unit 142 ... Joint coordinate system reference command setting unit 143 ... Joint coordinate system conversion command generation unit H ... Hand unit J1 ... First joint J2 ... Second joint J3 ... Third joint M1-M3 ... Motor (actuator)
TD ... Semiconductor wafer transfer device W ... Semiconductor wafer (work)

Claims (6)

Arm elements sequentially connected by a plurality of joints that can move or rotate linearly;
An actuator for changing the relative position or posture of an arm element connected to each joint;
A control unit that controls the position and posture of the hand unit provided in the terminal arm element by controlling the actuator,
An articulated robot in which at least one of the joints has a degree of freedom of rotation,
The control unit is
An orthogonal coordinate system reference command setting unit for obtaining a reference command value for controlling the position or orientation of the hand unit as an orthogonal coordinate system reference command value at least a part of which is an orthogonal coordinate system;
An orthogonal coordinate system shaping command generation unit that performs a predetermined input shaping on the orthogonal coordinate system reference command value obtained by the orthogonal coordinate system reference command setting unit to generate an orthogonal coordinate system shaping command value;
A joint coordinate system conversion command generating unit that generates a joint coordinate system conversion command value obtained by converting the orthogonal coordinate system shaping command value obtained by the orthogonal coordinate system shaping command generation unit into a joint coordinate system corresponding to each joint; ,
A multi-joint robot configured to control each actuator based on a joint coordinate system conversion command value obtained by the joint coordinate system conversion command generation unit.   The articulated robot according to claim 1, wherein the predetermined input shaping performed by the orthogonal coordinate system shaping command generation unit is a filter process for suppressing vibration of the hand unit.   The articulated robot according to claim 2, wherein the filter processing is data processing as input shaping control. The control unit is
A joint coordinate system reference command setting unit that generates a joint coordinate system reference command value as a reference command value to be given to each actuator;
A joint coordinate system shaping command generation unit that generates a joint coordinate system shaping command value by performing predetermined input shaping on the joint coordinate system reference command value obtained by the joint coordinate system reference command setting unit;
A control command value switching unit that outputs a switching command to switch a control command value to be given to each actuator;
In response to a switching command from the control command value switching unit, a joint coordinate system reference command obtained by the joint coordinate system reference command setting unit instead of the joint coordinate system conversion command value obtained by the joint coordinate system conversion command generation unit 4. The actuator is configured to control each actuator based on a value or a joint coordinate system shaping command value obtained by the joint coordinate system shaping command generation unit. Articulated robot described in   When the hand unit does not hold a workpiece, the joint coordinate system reference command obtained by the joint coordinate system reference command setting unit instead of the joint coordinate system conversion command value obtained by the joint coordinate system conversion command generation unit The articulated robot according to claim 4, wherein the control command value switching unit outputs a switching command so as to control each actuator based on a value.   The articulated robot according to claim 1 is provided, the articulated robot is configured as a horizontal articulated robot, and the semiconductor wafer is transported while the semiconductor wafer is placed on the hand unit. A semiconductor wafer transfer apparatus characterized by the above.

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