JPS5827074B2 - Method for detecting the state of the object to be measured - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection method for detecting state quantities of an object to be measured.

When performing work on a target system using an industrial robot, when the work target system is not accurately positioned, or when it is difficult to accurately position the work target system in advance, etc. A common method is to use senses such as touch or vision in order to obtain accurate information regarding the state quantities of the work target system, such as the position.

However, the former method of using the tactile sense is useful when trying to use it as a general-purpose tactile device, or when trying to widen the applicability range and conditions of the device even if it is a specialized one. Extremely complex calculations must be performed to process the information obtained from the position, which requires a calculation processing device with advanced calculation functions and requires a large amount of calculation.

In addition, in the latter method of using vision, elements such as an ITV (industrial) camera or a photoelectric element are required as a visual device, and a fairly high-grade computer is essential as a processing device. The current situation was that there were many problems in terms of price in order to meet the demand.

An object of the present invention is to provide a method for detecting the state of a measured object, in which a detection means provided in a moving device is movable relative to the measured object, and the state quantity of the measured object can be accurately and easily detected. It is about providing.

The gist of the present invention to achieve such an object is to provide a method for detecting the state of a measured object by detecting the state quantities of the measured object using a detection means attached to a moving means. Then, one parameter is selected from among the plurality of parameters, and the detection means is set to a first specific value for the object to be measured in correspondence with the selected one specific parameter. and then drive the moving means until the other specific parameters reach their respective specific values while keeping the one specific parameter at the first specific value, thereby detecting the detection unit. The object to be measured is moved for each of the other parameters, and the state quantity of the object to be measured is detected through the detection means at a position where each of these specific parameters corresponds to a specific value. A method for detecting the state of an object to be measured is provided.

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. Figure C1 shows a state in which the attitude of a disc-shaped object is detected by a tactile device attached to the wrist tip of a Cartesian coordinate system industrial robot. It is a perspective view of the whole shown.

A saddle 3 that reciprocates in the X-axis direction on a first column 2 by a hydraulic cylinder 1, and a second saddle 3 provided upright on this saddle 3
a cross bearing box 6 that is moved up and down in the X-axis direction by a hydraulic cylinder 5 along the column 4; a column 8 that is attached to the cross-bearing box 6 and reciprocated in the Y-axis direction by a hydraulic cylinder 7; It has a wrist mechanism 9 that can rotate around a vertical axis fixed to the tip of the wrist.

A haptic device 10 is attached to this wrist mechanism.

Such a tactile device 10 was proposed by the present inventors using a disc-shaped object W, and has a structure suitable for the function of detecting the center position and inclination of the disc.

The object W is, for example, a road wheel of an automobile.

The inclination of such a road wheel changes easily depending on the bundle, and it is difficult to tell which direction it is facing.

Furthermore, due to large dimensional errors in the vehicle body, the center position of the road wheel is not clear.

Therefore, there is a need for a haptic device 10 having the functions described above.

The tactile device 10 comprises four antennae 11, 12, 13°14.

FIG. 2 shows an enlarged view of such a haptic device 10.

The antennae 11 and 12 can be displaced parallel to each other only in the Z-axis direction by a parallel link mechanism.

The antennae 13 and 14 are configured to be displaced relative to each other only in the Y-axis direction.

In normal times, these antennae are pulled up or protruded toward the upper end or the front, and are supported by springs 111, 121, 131 so that they are displaced when they come into contact with the object W.
, 141.

Furthermore, each antennae has a potentiometer 110°120.1
30 and 140, and is configured to convert the displacement of each antenna into a voltage signal and extract it.

When detecting the position of the object W using such a tactile device, it is necessary to read the amount of displacement obtained from each tactile angle into the data processing device.

This system diagram is shown in Figure 3.

Potentiometer 11 attached to each of the four antennae
The displacement detection voltage signals from 0, 120, and 130 degrees 140 are switched by a selection circuit 15 so that a desired potentiometer output voltage signal can be extracted.

This extracted signal is sent to the A/D converter 16,
The signal is converted into a binary digital signal and then input to a data processing device 19 for processing.

Now, the four antennae of the tactile device 11, 12°13.1
Consider a situation as shown in FIG. 4, in which the object 4 is in contact with the disk of the object.

Let us describe the center position and tilt detection operations.

A plan view of FIG. 4 is shown in FIG. 5, and an elevational view is shown in FIG. 6.

The displacements of the antennae 11, 12, 13°14 are La and R, respectively.
a, la, ra and flf, and if the angle between the principal axis of the haptic device 10 and the principal axis of the disk of the object W is φ, then the displacement difference Za between the antennae 11 and 12 is the inclination of the disk φ
and the angle α.

If we solve this for α and set , then the deviation Te between the center of the disk and the center of the haptic device becomes .

Since the above-mentioned industrial robot has an orthogonal coordinate system, it is necessary to allocate a correction amount equivalent to this deviation to the X-axis and Y-axis of the robot and give a command.

These are respectively Xe1. If it is Yeo, then it becomes.

In addition, the angle φ between the main axis of the haptic device and the main axis of the disk is as follows.In order to make the disk and the haptic device parallel, the robot's wrist swing axis (hereinafter referred to as the SW axis) must be It can be seen that it is sufficient to rotate the slope by φ.

Further, in this correction operation, in order to bring the rotation center onto the disk surface, it is sufficient to apply the amount of movement of the bill to the Y-axis and the Y-axis simultaneously with this rotation operation.

From the above, as shown in Figure 4, when the four antennae are in contact with the target disk, the required correction amounts Xe, Yo, and SWo for each axis of the robot are the displacement amount of each antennae. It is established from the relational expression.

If these formulas can be calculated accurately, it will be possible to match the center position and inclination of the target disk with the center position and inclination of the haptic device by moving each axis of the robot based on the calculation results. (However, in practice, the position of each axis of the robot at the time after moving each axis of the robot is expressed as xl, y, z
,,swl is the coordinate X of the center position of the disk.

, Yo, Zo and the slope value SWo are given by ).

Such a calculation formula is extremely complex.

In order to process this complex calculation formula online,
A large-scale data processing device must be prepared.

For example, in order to process the above formula, multiplication, division,
In addition to computing trigonometric functions, it is also necessary to compute implicit numbers with parameter variables.

Of course, a certain amount of processing is possible even with a small-scale data processing device.

For example, in order to process the above-mentioned functions with a data processing device that does not have the functions of multiplication and division, let alone trigonometric relations, the processing is performed on a software program, but calculation tables must be stored in advance in the storage device. Alternatively, methods such as adding these arithmetic processing circuits as hardware may be taken.

However, in the first method, the processing time is too long and the re-online control cannot be done in time, and in the second method, the capacity scale is such that the entire capacity of the storage device already provided as the device is used. , the more the calculation is carried out, the more the storage area for data necessary for control is lost, creating a situation where the calculation process cannot actually be performed.

Furthermore, even if the storage capacity were to be increased, the storage capacity would be unacceptable for a small data processing apparatus considering the overall scale of the apparatus.

In any case, it becomes practically impossible to process.

Furthermore, the third method has the drawback of being expensive.

The above-mentioned large and small sizes are actually as follows.

Large-scale data processing devices have the ability to process complex calculations such as multiplication, division, and even trigonometric functions, and include general-purpose digital computers and large-scale control computers.

A small data processing device is one that does not have the above calculation processing capacity,
They are also small in size, and are commonly referred to as microcomputers or minicomputers.
Alternatively, it includes a small data processing device that performs partial data processing at a terminal of the general-purpose digital computer or control computer.

The reason why we have specifically mentioned the differences between large and small robots and their processing capabilities is to realistically process robot control.

Control of robots varies somewhat depending on the object, but in general, the movements are simple.

However, when this operation is viewed from the viewpoint of control, the operation is achieved by a considerably complicated calculation formula as described above.

This is extremely unreasonable from the perspective of the device.

For example, a robot can be easily controlled using a large data processing device.

However, it is not economical to use a large data processing device to control the robot.

Therefore, it would be ideal to use a small data processing device.

However, as mentioned above, as long as it is an extension of conventional general usage and general thinking, computational processing power
Bring limits.

The disadvantages of this compact data processing device are substantial.

However, by introducing a specific way of thinking, it is possible to process complex calculation formulas.

The basic idea of the present invention will be described below.

Consider a microcomputer as a small data processing device.

The basic operations of microcomputers include what is called a shift or rotation.

For example, in assembly language, the shift instruction is l'-R
It is expressed by a symbol such as ARJ or rRALJ.

The command ``RARJ'' means that if the value P on the accumulator in the computer is (one word is 8 bits), then a one-digit shift to the right can be obtained by using the ``T'' instruction.

Therefore, if we set ``0'', then Here, the most significant digit of P′ becomes.

PR is 1/2 of P.

Generally, if n (n≦8) shift commands rRARJ are performed on the numerical value P on the accumulator, and Q is the resultant numerical value with all the upper n digits set to "0", then the following is obtained.

Here, [ ] indicates the largest integer that does not exceed the number in parentheses, and is a so-called Gauss symbol.

Equation (4) can be simplified as follows, and can be regarded as equivalent to multiplying so-called (]'') by P.

In other words, even a computer with only simple functions can approximately perform multiplication and division, albeit to a very limited extent.

The above is the first basic idea of the present invention. Next, the second
Let me explain the basic idea.

The reason why each of the above-mentioned relational expressions is complicated is that the variables are interrelated.

Variables are generalized and called parameters.

The more a calculation is attempted while simultaneously satisfying the interrelationships of all parameters, the more complicated the calculation process becomes.

Therefore, conversely, if the parameters are sequentially decreased, the calculation becomes simpler as the parameters decrease.

Looking at this from a control perspective, the robot is moved in advance in a direction that makes the above relational expression simpler (this is
(means controlling each parameter), then
This is equivalent to trying to control the next process.

For example, (2), (3). Equations (4) and (5) are relational equations that include the angle φ, but first, (8) and (
If the wrist axis of the robot is rotated by the angle φ according to the relationship in equation 9), as a result, the principal axes of the haptic device and the disk will coincide, and the outer circumference of the disk of the object will be an ellipse as seen from the haptic device. It becomes a yen instead.

If we redefine the displacement of the antennae 11.12 obtained in this state as La and Ra, then (2)2~(5)
All equations are set to φ−〇, and equations (6) and (7) become as follows, allowing the number of parameters to be reduced by one.

That is, by moving the robot body in relation to specific parameters, it is possible to significantly supplement the computing power of the computer.

Next, let me explain the third basic idea.

This idea is a development of the first idea above.

Among the above relational expressions, there are parameters that can be approximated by specific functions.

Naturally, approximation errors occur when function approximation is performed.

This approximation error can be converged to a negligible value by continuously performing function approximation several times.

Let's discuss an example of linear approximation. In the relationship of equation (9),
The value of the displacement difference (■3) between the antennas 13 and 14 is determined by the voltage applied to the potentiometer connected to the antenna and the conversion coefficient of the A/D converter, while the value of the angle φ is determined by the SW of the robot wrist. The rotation angle command for the shaft is determined by the resolution of the position detector of the shaft, and the relationship in equation (9) including these influences is shown by the solid line in Figure 7. shall be taken as a thing.

At this time, the rotation angle command φ to the SW axis is It can be approximated as

A straight line based on this equation is shown as a dotted line.

Such a formula can be realized by a shift instruction based on the first basic idea.

Let's talk specifically about the corrective action.

In FIG. 7, it is assumed that the detected displacement amount ya is 100 digits (hereinafter abbreviated as digits).

At this time, the approximate value of the required correction amount φ of the SW axis is φ=50 d
igi ts.

If the SW axis is rotated using this approximate value as the recall target value,
The error after the rotation operation is the difference between the virtual target value and the actual value ε1
It is.

The difference ε1 is approximately 5 digits. Note that φ1 is an actual value.

Therefore, the error between the SW axis position and the true target value in this state is the value φ2 corresponding to φ=5 digits.
The value of Ya becomes ya1.

Now, if we make the correction again, ya□ will be 12 digi
ts, the corresponding value of φ is 6 digi
ts, and the error ε2 becomes 1 d igi ts.

Therefore, the angle error after these two corrections is φ=1dig
That means its.

In other words, the relational expression (9) is approximated to a rough linear relationship that can be substituted by a microcomputer's shift command, the robot is moved using the approximate value as a virtual target value, and then the robot is moved again. By repeating similar operations, it becomes possible to converge the approximation error in the direction of zero (0).

In the above calculation, linear approximation was performed using a 1-bit shift, but depending on the nature of the object relational expression, linear approximation may be performed using other shifts such as a 2-bit shift.

Next, examples of the present invention based on this principle will be described.

FIG. 8 is a block diagram showing an embodiment of the present invention.

The specific parameter calculation device 200 inputs detection signals 200a, 200b, 200c, and 200d obtained from the potentiometers 110, 120, 130, and 140,
This is a device that performs arithmetic processing regarding specific parameters after performing preprocessing such as A/D conversion processing.

The arithmetic processing regarding this specific parameter means that the number of parameters is reduced, and in the reduction, the calculation is performed based on a processing formula that simplifies the processing of the parameter.

Specifically, for example, first, attention is paid to the angle φ, and the angle φ is approximated by linear approximation by shifting, and arithmetic processing is performed.

Therefore, the arithmetic device 200 has information in advance about which parameters are to be reduced in what order and under what approximation conditions in each order. It is set.

Therefore, by inputting predetermined data, calculations of specific parameters are sequentially performed.

The movement amount setting device 201 uses data obtained from the specific parameter calculation device 200 and detection signals 200a and 200b from each potentiometer.

This is a device that uses inputs 200c and 200d to set the amount of movement of the robot.

As mentioned earlier, the amount of movement of the robot is Xe, Ye
, SWe, etc. are shown.

The robot 1 drive circuit 202 is configured to control the movement amount setting device 2.
It receives a setting signal from 01 and controls the posture of the robot 203.

The robot drive circuit 202 drives the robot 203 by a set amount of movement.

After being moved in this way, the state quantities of the robot 203 are determined by the potentiometers 110, 120, 130, .
140, and the specific parameter setting device 2
00 is input.

This is a so-called feedback operation. Each of the above devices enables a small data processing device with a small processing amount, such as a microcomputer, to process complex relational expressions in a simple processing form.

In addition, in FIG. 8, the wall where the signal is output from the movement amount setting device 210 to the specific parameter setting device 200 is
This is necessary for calculation in the specific parameter setting device 200.
This is because the output signal from the movement amount setting device 201 is required.

Including this, the specific parameter setting device 200 will be explained in more detail with reference to FIG.

FIG. 9 is a diagram showing the internal configuration of the specific parameter setting device 200.

In the figure, the parameter calculation order setting device 2001 is
It is activated by a command to start calculation, and selects parameters according to a predetermined order of parameters.

This ranking is basically determined in advance, but the ranking may be automatically changed as necessary during the calculation process.

The calculation ranking setting device 2001 also has such a ranking automatic setting function.

Specifically, the data necessary for this automatic ranking setting is the detection signal 200a provided by the potentiometer described in FIG.

They are 200b, 200c, and 200d.

The parameters specified by the parameter calculation order setting device 2001 are specified by the specific parameter approximation condition setting device 200.
Enter 2.

The specific parameter approximation condition setting device 2002 is set in advance as to what kind of approximation conditions are satisfied by the parameters, and therefore, by inputting the selected parameters, it sets and outputs the conditions to be approximated. Become.

The command setting device 2003, which receives the conditions to be approximated, sets necessary commands according to the conditions to be approximated.

A typical command is the shift command mentioned above.

The command output by the command setting device 2003 is input to the data processing unit 2004 at the next stage.

In the data processing unit 2004, necessary input data 20
Parameters are calculated based on the processing relational expression using 04a as input.

Specifically, the input data 2004a is the data of the detection signal from the potentiometer described in FIG.

When the parameter calculation is completed in the data processing section, a start signal 2004b is generated, and the parameter calculation order setting device 2001 is started again to select the parameter of the next order.

The above embodiments are summarized within a very qualitative range, and the detailed configuration may vary depending on the actual specific model.

These detailed configurations are omitted because they do not suit the purpose of the invention.

Although the above embodiment uses linear approximation, the present invention is also applicable to parameters that are generally based on curved relational expressions.

For example, it is well known that curve approximation is possible by using a broken line approximation method in which a curve is approximated by a straight line.

Therefore, by preparing shift commands corresponding to the famous line, curve approximation becomes possible by combining the shift commands.

Among each relational expression, the polygonal line approximation occupies a relatively large proportion, and in the present invention, an approximation method based on a combination of shift commands (whether to shift bits or not) is actively utilized.

For example, a relationship such as tanψ is tanψ÷−1 when 0°≦ψ≦300, and 1+ψ in janψ when 300≦φ≦45°.

By approximating it with a broken line, the amount of rotation of the robot wrist axis SW can be expressed as X, Y.
It becomes possible to relate this to the amount of movement of the axis.

The present invention has been described above with respect to a case where the attitude of a disc-shaped object W is detected by a tactile device attached to the wrist end of a Cartesian coordinate system industrial robot.

The present invention is also applicable to other cases. For example, in Figure 10,
Rod-like antennae 17 placed at right angles to each other in two XY planes
．． 18 shows a tactile device for detecting the position of bolts placed 90° apart from each other.

In the figure, the length of the antennae 17 in the vertical direction is 7, and the length of the antennae 18 in the horizontal direction is 7'' (however, V is longer than P).

However, here, P is the four bolts 19, 20, 21, 2
2 pitches.

At this time, if the inclination of the disk W1 having the bolt group is human, and the displacement amounts of the vertical antenna 17 and the horizontal antenna 18 from the center of the disk are Ha and 3, respectively, the following equations are obtained.

Even in such a relational expression, accurate position detection is possible by repeating the method of making a very rough linear approximation, operating the robot, and reapproximating it.

As explained in detail above, according to the detection method of the present invention, the detection means attached to the moving device is moved toward the object to be measured until it reaches a position of a specific value for each parameter that is the state quantity of the object to be measured. Since the state quantity of the object to be measured is measured through the detection means at the position of these specific values, it is possible to detect the state quantity of the object to be measured very accurately and easily. be effective.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the relationship between an industrial robot and a disk as a target object, Fig. 2 is a perspective view of the tactile device, Fig. 3 is a block diagram for processing detection signals from the tactile device, Figure 4 shows the state of contact between the haptic device and the disk, Figures 5 and 6.
The figure is a plan view of what is shown in FIG. 4, FIG. 7 is a detailed explanation of the present invention, FIGS. 8 and 9 are illustrations of embodiments of the present invention,
FIG. 10 is a diagram showing another example of the object system of the present invention. Explanation of symbols, 11, 12, 13. 14... antennae, 20
0...Specific parameter calculation device, 201...Movement amount setting device, 202...Robot drive circuit, 203...
・Robot body.

Claims (1)

[Claims] 1. In a method for detecting the state of a measured object in which the state quantity of the measured object is detected by a detection means attached to a moving means,
A plurality of specific parameters are selected from among the state quantities of the object to be measured, one parameter is selected from among the plurality of parameters, and the detection means is applied in correspondence to the selected one specific parameter. The first
and then drive the moving means while keeping the one specific parameter at the first specific value until the other specific parameters reach their respective specific values. The detection means is moved relative to the object to be measured for each of the other parameters, and the state quantity of the object to be measured is detected at a position where each of these specific parameters corresponds to a specific value. A method for detecting the state of an object to be measured, characterized in that detection is performed through a detection means.