JPH07200033A - Robot controller - Google Patents

Abstract

PURPOSE:To provide a robot controller capable of making the ability of a motor fully demonstrated at all times even when the acceleration starting spot and deceleration ending spot of a robot are any spots and shortening operation time. CONSTITUTION:Minimum acceleration time and deceleration time 33 are decided within a range for which the drive torques of respective axes in the case of defining a speed when the robot 5 reaches a middle point as a maximum speed computed by a maximum speed computing means 34 do not exceed an allowable maximum torque and a speed command curve 34 is generated based on the decided result and the maximum speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot controller for driving a robot using a motor.

[0002]

2. Description of the Related Art FIG. 11 is a block diagram showing a conventional robot controller. In FIG. 11, reference numeral 1 stores coordinates of an acceleration start point and a deceleration end point of a robot 5, for example, moving from point a to point b. When receiving a move command to
Teaching point storage means for outputting the coordinates of the points, 2 is coordinate conversion means for converting the coordinates of the points a and b output from the teaching point storage means 1 into the joint coordinates of the robot 5, and 3 is all of the robot 5 in advance. The work area is divided into a plurality of small areas, and the calculation parameter of the speed command curve when the robot 5 moves from a point in a certain area to a point in a certain area is stored for each combination between the areas, and coordinate conversion is performed. When the joint coordinates of the points a and b are output from the means 2, the speed command curve calculating means 4 for calculating the speed command curve based on the calculation parameters peculiar to the regions to which the points a and b belong respectively, the speed command curve calculating means 4 It is a motor control unit that controls a motor that drives each axis of the robot 5 according to the speed command curve calculated by the curve calculation unit 3. Incidentally, FIG. 13 is a flow chart showing the operation of the speed command curve calculating means.

Next, the operation will be described. First, when the teaching point storage means 1 receives a movement command, it analyzes the movement command and determines from which point the robot 5 should be moved. For example, if the move command is a command to move from point a to point b, the coordinates of point a and point b are output. Then, the coordinate conversion means 2 which has output the coordinates of the points a and b from the teaching point storage means 1 converts the coordinates of the points a and b into the joint coordinates of the robot 5.

Next, the speed command curve calculating means 3 outputs the joint coordinates of the points a and b from the coordinate converting means 2,
Regions to which the points a and b belong respectively are detected (step ST1), and calculation parameters (maximum moment of inertia I _max , maximum velocity V) peculiar to the regions to which the points a and b belong are detected.
_max , allowable maximum torque T _max ) (step S
T2), the speed command curve is calculated (step ST
3), the calculation parameter of the speed command curve is stored in the speed command curve calculation means 3 as follows. That is, the speed command curve calculation means 3 divides the entire work area of the robot 5 into a plurality of small areas, and calculates the calculation parameters of the speed command curve when the robot 5 moves from a point in a certain area to a point in a certain area. It is stored for each combination between areas. For example,
When divided into 5 areas, 20 ways ((5-1) × 5
= 20) is stored. However, in this example, since three types of calculation parameters (maximum moment of inertia I _max , maximum speed V _max , and maximum allowable torque T _max ) are stored, the number of parameters is 60 (2
0 ways x 3 types = 60).

Here, the speed command curve is shown by the relationship between time and speed as shown in FIG. 12, and generally has a trapezoidal shape, but the following relationships are established among various calculation parameters. T _max = I _max × V _max / t1 (1) T _max = I _max × V _max / t2 (2) However, even in the same small area, if the coordinates are different, the robot 5 Since the posture changes slightly, the moment of inertia I, etc. at each coordinate is different, and if the acceleration start point and the deceleration end point are slightly different, the value of the calculation parameter changes, but in this example, the acceleration start point is different from the area to which the acceleration start point belongs. Since the calculation parameter between the regions to which the deceleration end point belongs is represented by a certain value, the representative value is set so as not to exceed the motor capacity. That is, the calculation parameter is set based on the point where the motor load is the largest between the respective regions. Therefore, at other points, the load of the motor is smaller than that at the point where the load is the largest, and therefore, there is a margin in the capacity of the motor according to the calculation parameter.

Incidentally, in the speed command curve, when the calculation parameter is selected as described above, the acceleration time t1 and the deceleration time t2 can be obtained from the equations (1) and (2), respectively. It can be obtained from these acceleration times t1 and the like (see FIG. 12).

When the speed command curve is calculated in this way, the motor control means 4 controls the motors that drive the respective axes of the robot 5 according to the speed command curve to move the robot 5 according to the movement command. A series of processing is ended, but the motor control means 4 will be described in more detail with reference to FIG. Incidentally, in FIG. 14, 11 indicates the robot 5 by integrating the speed command value V * based on the speed command curve.
Integrator for generating the position command value θ _r of the robot 5
Subtractor 13 proportional controller for generating a subtractor 12 subtraction result to the proportional speed command value constant by multiplying the omega _r of 14 rate for subtracting the actual position theta _a robot 5 from the position command value theta _r of subtractor from command value omega _r subtracting the actual speed omega _a of the robot 15 is proportional controller for generating a current command value i _r1 is multiplied by a proportionality constant to the subtraction result of the subtracter 14, 16 a subtracter 1
An integral controller that generates a current command value i _r2 proportional to the integrated value of the subtraction result of 4, and 17 is a current command value i _r1 and a current command value i _r2.
It is an adder that adds _r2 and outputs a current command value i _r .

Further, 18 is a current command limiter for limiting the maximum current of the motor when the absolute value of the current command value i _r exceeds the absolute value of the maximum current of the motor, and 19 is an output of the current command limiter 18. The command value i _r ^* is the actual motor current i
A current control system for controlling the current of the motor so that _a is matched, 20 is a motor that generates torque T _e proportional to the actual current i _a of the motor, and 21 is gravity torque T _g and friction torque T _{f in addition} to torque T _e. Is an adder that adds

Since the motor control means 4 is constructed as described above, the position command value θ _r of the robot 5 is obtained from the speed command value V * based on the speed command curve, and the actual position θ _{a of the} robot 5 is calculated as _follows. The actual current i _a of the motor 20 is controlled so as to match the position command value θ _r . For example, the base 22 with the robot 5 fixed vertically (see FIG. 15) is used.
On the other hand, as shown in FIG. 16, when the robot 5 moves upward from the position indicated by the solid line (+ Z direction) and stops at the position indicated by the dotted line, and when the robot 5 moves downward from the position indicated by the dotted line (-
The actual current i _a of the stopped motor 20 is different between when the motor 20 is stopped in the Z direction) and stopped at the position indicated by the solid line.

The reason is that, first, when the robot 5 moves in the + Z direction to reach the target point, the robot 5 moves against the gravity mg and the frictional force F, and the disturbance is as follows. Disturbance = −mg−F (mg, F> 0) (3) On the other hand, when the robot 5 moves in the −Z direction to reach the target point, the robot 5 moves against the frictional force F (gravity mg is It works in the direction of assisting movement), so the disturbance is as follows. Disturbance = −mg + F (mg, F> 0) (4)

Therefore, since the disturbance becomes larger when the robot 5 rises than when it descends, the current command value i _r naturally rises when the robot 5 descends as shown below. Grows larger. | -Mg-F |> | -mg + F | (5) However, in the integration controller 16, even if the robot 5 stops, that is, even if the output of the subtractor 14 becomes zero, the past history Therefore, the integral controller 16 outputs a larger current command value i _r2 when the robot 5 moves up and stops than when it descends and stops. As a result, the actual current i _a of the motor becomes larger when the robot 5 rises and stops than when the robot 5 descends and stops.

In the above-mentioned conventional example, the whole work area of the motor is divided into a plurality of small areas, and the calculation parameter is set for each combination between the small areas. It is disclosed in Japanese Patent No. 55803.

[0013]

Since the conventional robot controller is constructed as described above, it is necessary to set the calculation parameter based on the point where the load of the motor is the largest for each area. Therefore, at other points, the load on the motor becomes smaller than at the point where the load is the largest, so there is a margin in the capacity of the motor with the relevant calculation parameters, and as a result, the capacity of the motor is fully exerted. However, there is a problem that the operation time cannot be shortened sufficiently. Also, regardless of the movement direction until the robot stops, while the robot is stopped, its position can be held as long as there is a torque that supports gravity, but the robot descended and stopped. When the robot rises and stops, the current command value during stop does not increase, so it is necessary to select a motor with a larger rated current than necessary, which increases cost. was there.

The invention of claim 1 has been made to solve the above problems, and always maximizes the capability of the motor regardless of the acceleration start point and deceleration end point of the robot. It is an object of the present invention to provide a robot control device that can reduce the operation time.

It is an object of the invention of claim 2 to obtain a robot controller capable of further shortening the operation time as compared with the invention of claim 1.

In addition to the object of the invention of claim 1, the inventions of claims 3 and 4 provide a robot controller capable of protecting the motor so that the effective torque of the motor does not exceed the rated torque. The purpose is to

According to the fifth and sixth aspects of the present invention, the effective torque is prevented from increasing due to the frequent movements of the robot, and the capacity of the motor is kept within a range in which the effective current of the robot does not exceed the rated current. It is an object of the present invention to obtain a robot control device that can maximize its performance and reduce the operation time.

It is an object of the inventions of claims 7 and 8 to obtain a robot controller capable of reducing a current command value while the robot is stopped and selecting a motor having a small rated current.

[0019]

According to a first aspect of the present invention, there is provided a robot control apparatus, wherein each speed of the axes when the robot reaches the midpoint is the maximum speed calculated by the maximum speed calculating means. The minimum acceleration time and deceleration time are determined within a range in which the drive torque of does not exceed the maximum allowable torque, and a speed command curve is generated based on the determination result and the maximum speed.

In the robot controller according to the second aspect of the present invention, after determining the acceleration time and the deceleration time, the robot is re-established at any point in the acceleration section and the deceleration section based on the maximum speed calculated by the maximum speed calculation means. The acceleration time and the deceleration time are determined.

In the robot controller according to the third aspect of the invention, when the comparing means determines that the load amount of the motor exceeds the allowable load amount, the value of the maximum allowable torque of each axis of the robot is corrected downward. However, when it is determined that the maximum torque is not exceeded, the value of the maximum allowable torque is corrected upward.

In the robot controller according to the invention of claim 4, when the comparison means determines that the load amount of the motor exceeds the allowable load amount, the maximum speed value of each axis of the robot is corrected downward. When it is determined that the maximum speed is not exceeded, the maximum speed value is corrected upward.

A robot controller according to a fifth aspect of the present invention calculates the operation time in each section of the robot so as to be proportional to the square root of the operation angle calculated by the operation angle calculation means, and the speed command is calculated according to the operation time. The operation time of the speed command curve generated by the curve generating means is corrected.

According to a sixth aspect of the present invention, there is provided a robot control device, wherein the operation time in each section of the robot is proportional to the product of the square root of the operation angle calculated by the operation angle calculating means and the moment of inertia in each section of the robot. The operation time of the speed command curve generated by the speed command curve generating means is corrected by calculation.

In the robot controller according to the invention of claim 7, when the speed command value generated by the speed command value generating means is zero, the current command value is generated within a range in which the output torque of the motor becomes larger than the gravity torque. The current command value generated by the means is limited.

In the robot controller according to the present invention, when the speed command value generated by the speed command value generating means is zero, the output torque of the motor becomes larger than the difference between the gravity torque and the friction torque. In this, the current command value generated by the current command value generating means is limited.

[0027]

In the robot controller according to the invention of claim 1,
If the speed when the robot reaches the midpoint is the maximum speed calculated by the maximum speed calculation means, set the minimum acceleration time and deceleration time within the range where the drive torque of each axis does not exceed the maximum allowable torque. By providing the acceleration / deceleration time determining means for determining, it becomes possible to always generate the speed command curve capable of maximizing the performance of the motor regardless of the acceleration start point and the deceleration end point of the robot.

In the robot controller according to the second aspect of the present invention, after determining the acceleration time and the deceleration time, the robot is accelerated again at any point in the acceleration section and the deceleration section based on the maximum speed calculated by the maximum speed calculation means. By determining the time and the deceleration time, it becomes possible to obtain the optimum speed command curve by making full use of the capability of the motor.

In the robot controller according to the third aspect of the present invention, when the comparison means determines that the load amount of the motor exceeds the allowable load amount, the value of the maximum allowable torque of each axis of the robot is corrected downward. If the maximum torque is determined not to exceed, the motor is protected so that the effective torque of the motor does not exceed the rated torque by providing the maximum allowable torque correction means for upwardly correcting the value of the maximum allowable torque. .

In the robot controller according to the invention of claim 4, when the comparison means determines that the load amount of the motor exceeds the allowable load amount, the maximum speed value of each axis of the robot is corrected downward, When it is determined that the maximum speed is not exceeded, the maximum speed correction means for upwardly correcting the maximum speed value is provided, so that the motor is protected so that the effective torque of the motor does not exceed the rated torque.

According to the fifth aspect of the invention, the robot controller calculates the operation time in each section of the robot so as to be proportional to the square root of the operation angle calculated by the operation angle calculation means, and the speed command curve is calculated according to the operation time. By providing the operation time correction means for correcting the operation time of the speed command curve generated by the generation means, even if the robot frequently operates, the motor's ability within the range in which the effective current of the robot does not exceed the rated current You will be able to maximize your ability.

According to a sixth aspect of the present invention, the robot controller calculates the operation time in each section of the robot so as to be proportional to the product of the square root of the operation angle calculated by the operation angle calculating means and the moment of inertia in each section of the robot. However, by providing the operation time correction means for correcting the operation time of the speed command curve generated by the speed command curve generation means according to the operation time, the effective current of the robot is rated even if the robot operates frequently. It is possible to maximize the capacity of the motor within the range that does not exceed the current.

In the robot controller according to the invention of claim 7, when the speed command value generated by the speed command value generating means is zero, the current command value generating means is within a range in which the output torque of the motor becomes larger than the gravity torque. By providing the current limiting means for limiting the current command value generated by, the actual current of the motor when the robot is stopped is reduced.

In the robot controller according to the present invention, when the speed command value generated by the speed command value generating means is zero, the output torque of the motor is within a range in which the output torque is larger than the difference between the gravity torque and the friction torque. Since the current limiting means for limiting the current instruction value generated by the current instruction value generating means is provided, the actual current of the motor when the robot is stopped is reduced.

[0035]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. 1 is a block diagram showing a robot control apparatus according to a first embodiment of the present invention. In the figure, the same reference numerals as those of the conventional one indicate the same or corresponding portions, and the description thereof will be omitted.
_{Reference numeral} 31 is a storage means for storing the maximum speed V _maxi and allowable maximum torque T _maxi of each axis of the robot 5, 32 is the maximum speed V _maxi stored by the storage means 31, and the robot 5 moves from the acceleration start point to the deceleration end point. Travel time tt
_i is calculated for each axis of the robot 5, and the maximum movement time tt _max among the calculated movement times tt _i is calculated.
It is a maximum speed calculation means for calculating the maximum speed V _i for each axis of the robot 5 when the robot 5 moves from the acceleration start point to the acceleration end point.

Further, 33 is a drive torque T _i of each axis when the speed when the robot 5 reaches the midpoint is the maximum speed V _i calculated by the maximum speed calculation means 32. Acceleration / deceleration time determination means for determining the minimum acceleration time t1 and deceleration time t2 within a range not _{exceeding maxi} , 34 is a determination result (acceleration time t1, deceleration time t2) of the acceleration / deceleration time determination means 33, and maximum speed calculation means. The speed command curve generating means generates a speed command curve based on the maximum speed V _i calculated by 32. Incidentally, FIG. 2 is a flowchart showing the operation of the acceleration / deceleration time determining means.

Next, the operation will be described. First, similarly to the conventional one, when the teaching point storage means 1 receives a movement command, the teaching point storage means 1 analyzes the movement command and determines from which point the robot 5 should be moved. For example, if the move command is a command to move from point a to point b, the coordinates of point a and point b are output. Then, the teaching point storage means 1
Coordinate conversion means 2 in which the coordinates of the points a and b are output from
Represents the coordinates of the points a and b by the joint coordinates s _{i of} the robot 5,
Convert to e _i .

As a result, the maximum speed computing means 32, as shown below, calculates the joint coordinates s _i and e _i of the robot 5,
Based on the maximum speed V _maxi of each axis stored in the storage means 31, the moving time tt _i for each axis is calculated. tt _i = | e _i −s _i | / V _maxi (6) Further, the maximum speed calculation means 32, as shown below,
The maximum movement time tt _max among the calculated movement times tt _i for each axis (the movement time of the axis that requires the longest time for movement)
Therefore, the maximum speed V _i when the robot 5 moves from the acceleration start point to the deceleration end point is calculated for each axis. V _i = (e _i −s _i ) / tt _max (7)

Next, the acceleration / deceleration time determining means 33 determines the speed of each axis when the robot 5 reaches the midpoint (the midpoint between the acceleration start point and the deceleration end point) as shown in FIG. _The minimum acceleration time t1 within the range in which the drive torque T _i of each axis when _i is _i does not exceed the maximum allowable torque T _maxi
And deceleration time t2 are determined based on the equation of motion of the n-degree-of-freedom robot. Equation of motion of n-degree-of-freedom robot T = M · q + h (8) Here, M is an inertia matrix specified from the position of the robot,
q is the displacement of each axis, and h is the vector of Coriolis force, gravity and friction force specified from the position and velocity of the robot. The inertia matrix M and the vector h are calculated from the position of the robot and the like. Since such calculation is a well-known matter,
The description is omitted.

The determination of the acceleration time t1 and the deceleration time t2 will be described more concretely. The driving torques T _1i and T _2i of the i-th axis during acceleration and deceleration ignore the influence of the smoothing filter and are shown in FIG. Considering the trapezoidal pattern as a speed command curve, it becomes as follows. _{T 1i = M i · V i} / t 1 + h i = (M i1 · V 1 + ··· + M in · V n) / t1 + h i ··· (9) T 2i = -M i · V i / t ₂ + h _i = − (M _i1 · V ₁ + ... + M _in · V _n ) / t2 + h _i ... (1
0) Further, from the condition that the driving torques T _1i and T _2i during acceleration and deceleration do not exceed the allowable maximum torque T _maxi , respectively,
As shown below, n inequalities are obtained respectively. -T _{maxi ≤T 1i ≤T maxi} (where i = 0,1, ... n) (11) -T _{maxi ≤T 2i ≤T maxi} (where i = 0,1, ... n) ... (12)

Therefore, the inertia matrix M at the acceleration start point
And the vector h are substituted into the equation (9), the minimum acceleration time t1 (where t1 is a positive value) within a range in which the driving torque T _1i satisfies all n inequalities of the equation (11). Is calculated (step ST11). For convenience of explanation, the acceleration time t1 is defined as _t1a . Further, when the inertia matrix M at the midpoint and the vector h are substituted into the equation (9), the minimum acceleration time t1 (however, within the range in which the driving torque T _1i satisfies all the n inequalities of the equation (11) , T1 are positive values) (step ST11). For convenience of explanation, the acceleration time t1 is set to _t1c . And
The larger value of the acceleration time t _1a calculated based on the acceleration start point and the acceleration time t _1c calculated based on the midpoint is determined as the acceleration time t1 (step ST1).
2). As described above, the reason why the acceleration times t _1a and t _1c are calculated based on the acceleration start point and the midpoint and the larger value is determined as the acceleration time t1 is that the posture of the robot changes as the robot moves. Therefore, unless the acceleration time t1 calculated based on the point with the larger load is selected, the motor is overloaded.

Also for the deceleration time t2, when the inertia matrix M and the vector h at the deceleration end point and the midpoint are respectively substituted into the equation (10), the driving torque T _2i becomes the equation (12). The minimum deceleration time t2 (where t2 is a positive value) is calculated within the range that satisfies all n inequalities (step ST13), and the larger value is determined as the deceleration time t3 (step ST14). .

Then, the speed command curve generation means 34 causes the speed command curve based on the acceleration time t1 and the deceleration time t2 determined by the acceleration / deceleration time determination means 33 and the maximum speed V _i calculated by the maximum speed calculation means 32. (Fig. 3
The motor control means 4 controls the motor that drives each axis of the robot 5 according to the speed command curve.

As described above, according to the first embodiment, the robot 5 moves from the acceleration start point to the deceleration end point according to the movement command, but as described above, the acceleration time t1 and the deceleration time t2. Is determined, the drive torques of all axes do not exceed the maximum allowable torque T _maxi ,
Moreover, the acceleration / deceleration time is obtained such that the maximum value of the drive torque of at least one shaft becomes the maximum allowable torque T _maxi .

Example 2. In the first embodiment described above, the case where the speed command curve is generated from the trapezoidal pattern has been described, but the speed command curve may be generated from another curve such as a cam curve, and the same effect is obtained.

Example 3. In the first embodiment, the acceleration time t
1 and the deceleration time t2 are only determined once, the acceleration time t1 and the deceleration time t2 are initially determined using the method of the first embodiment as shown in FIG. 4 in order to consider the effect of smoothing. (However, since the acceleration time t1 and the deceleration time t2 may be initially determined and are not an essential part of the second embodiment, the method of the first embodiment is not necessarily used and, for example, the above-mentioned conventional example is used. The maximum speed V calculated by the maximum speed calculation means 32 at any point in the acceleration section and the deceleration section.
_The acceleration time t1 and the deceleration time t2 may be determined again based on _i .

That is, the acceleration end point and the deceleration start point are specified by initially determining the acceleration time t1 and the deceleration time t2 by the method of the first embodiment. Then, based on the acceleration start point and the acceleration end point, the acceleration time t1 is determined in the same manner as in the first embodiment (steps ST16 to ST18). On the other hand, the deceleration time t2 is determined in the same manner as in the first embodiment with reference to the deceleration start point and the deceleration end point (steps ST19 to 20). The generation of the speed command curve is the same as that in the first embodiment, and the description thereof is omitted.

As described above, according to the third embodiment, the acceleration time t1 and the deceleration time t2 are repeatedly set, so that the setting can be made more finely than in the first embodiment, and as a result,
The operation time can be further shortened as compared with the first embodiment.

Example 4. In the third embodiment, the acceleration time t
Although the case where the acceleration time t1 and the deceleration time t2 are reset once only after the initial setting of 1 and the deceleration time t2 has been shown, they may be reset twice or more.

Example 5. In the third and fourth embodiments, the acceleration time t1 and the deceleration time t2 are repeatedly set. However, the acceleration time t1 and the deceleration time t2 are determined using the inertia matrix M and the vector h in consideration of the effect of smoothing. You may do it.

Example 6. FIG. 5 is a block diagram showing a robot controller according to a sixth embodiment of the present invention.
Reference numeral 35 indicates a load amount detecting means for detecting an effective current (load amount) of the motor, and reference numeral 36 determines whether or not the effective current detected by the load amount detecting means 35 exceeds an allowable current value (allowable load amount) of the motor. When the comparison means 36 determines that the effective current of the motor exceeds the allowable current value, the reference numeral 37 indicates a maximum allowable torque T _maxi of each axis of the robot 5.
Is a maximum allowable torque correction means for correcting the maximum allowable torque T _maxi upwardly when it is determined that the maximum allowable torque T _maxi is not _exceeded .

Next, the operation will be described. First, when the load amount detecting means 35 detects the effective current of the motor, the comparing means 36 compares the effective current with the allowable current value of the motor and outputs the deviation, as shown below. Output of comparison means 36 = motor allowable current value-effective current (13)

The allowable maximum torque correction means 37 is
As shown below, the value of the maximum allowable torque T _maxi of each axis is corrected based on the output of the comparison means 36. Allowable maximum torque T _maxi = current allowable maximum torque T _maxi + coefficient × output of comparing means 36 (14) However, as a result of calculating equation (14), allowable maximum torque T _{maxi
When maxi} exceeds the maximum achievable torque of the motor, the allowable maximum torque T _maxi is set as the achievable maximum torque.

Therefore, when the effective current of the motor exceeds the allowable current value, the maximum allowable torque T _maxi of the motor is changed to be small. Conversely, when the effective current is smaller than the allowable current value, the motor is reduced. The maximum allowable torque T _maxi is changed to be large. Therefore, when the effective current of the motor exceeds the allowable current value, that is, when the load of the motor is large, the maximum allowable torque T _maxi of the motor is set small, and the speed command curve generating means 34 does not require a large driving torque. The speed command curve is generated, and as a result, the effective current of the motor can be suppressed to the allowable current value or less. Since the effective current of the motor and the effective torque are generally in a proportional relationship, the effective torque of the motor can be suppressed to the allowable value or less by suppressing the effective current to the allowable current value or less.

On the other hand, when the effective current of the motor does not exceed the allowable current value, that is, when the load of the motor is small, the maximum allowable torque T _maxi of the motor is set large. Therefore,
The speed command curve generating means 34 generates a speed command curve that requires a large driving torque, and as a result, the motor rotates at high speed and the robot 5 moves faster.

Example 7. In the sixth embodiment, the comparison means 3
Although the maximum allowable torque V _maxi is corrected based on the output of _No. 6, the comparison means 36 is used as shown in FIG.
The maximum speed correction means 38 may correct the maximum speed V _maxi of each axis of the robot 5 based on the output of
The same effect as the sixth embodiment is obtained. Maximum speed V _maxi = current maximum speed V _maxi + coefficient × output of comparison means 36 (15)

Example 8. In the sixth and seventh embodiments described above, one of the allowable maximum torque T _{maxi and the} maximum speed V _maxi is corrected, but both may be corrected.

Example 9. In the sixth to eighth embodiments, the load amount detecting means 35 detects the effective current of the motor, and the comparing means 3
6 shows that the effective current is compared with the allowable current value, the load amount detecting means 35 detects the temperature of the motor and the comparing means 36 compares the temperature with the allowable temperature value of the motor. Well, it has the same effect.

Example 10. FIG. 7 shows a tenth embodiment of the present invention.
3 is a block diagram showing a robot controller according to the present invention, in which 39 is a motion angle calculation means for calculating a motion angle θ _i for at least two sections of the robot 5 based on a movement command of the robot 5, and 40 is a motion angle calculation. Operation time calculation means for calculating the operation time t _pi in each section of the robot 5 so as to be proportional to the square root of the operation angle θ _i calculated by the means 39, 41 is the speed command curve generated by the speed command curve generation means 34 The operating time of the operating time calculation means 40
It is an operation time correction means for correcting the operation time t _pi calculated by

Next, the operation will be described. First, the movement angle calculation means 39 inputs the joint coordinates from the coordinate conversion means 2 to, for example, three sections ahead of the robot 5, and based on the joint coordinates, the movement angles θ _i (i = a, b, c)) is calculated. Then, the operation time calculation means 40 calculates the operation time t _pi for three sections of the robot 5 so as to be proportional to the square root of the operation angle θ _i. The reason for calculating the operation time t _pi is as follows. Is the street.

Generally, the performance of a motor used in an industrial robot is the maximum allowable torque T _max and the rated torque T _rated.
In the represented, the ratio of the allowable maximum torque T _{ma x} the rated torque T _rated motor used for K (robot K =
3), the maximum allowable torque T _max
The following relationship is established between the rated torque T _rated and the rated torque T _rated , but the robot motor must satisfy the following conditions regarding the maximum allowable torque T _max and the rated torque T _rated . T _max = K × T _rated ... (16) τ ≦ T _max ... (17) (2t1 × τ ² / t _total ) ^1/2 = T _rated ... (18) where τ is a figure 9 shows the torque between the acceleration time and the deceleration time, and the acceleration time and the deceleration time are equal to t1, and t
_total is the time from the start to the end of the operation (hereinafter referred to as tact time). Incidentally, the left side of the equation (18) is the root mean square value of the torque.

Here, the equal signs in equations (17) and (18) are
Substituting equation (16) into equation (17), the equation
The reason is as follows. 2t1 / t_total = 1 / K² (19) Then, the equation (19) is calculated during the acceleration time and the deceleration time.
Is the maximum allowable torque T_max The rated torque
T_rated In order to satisfy the conditional expression (18) of
A total of 2t1 of the interval and deceleration time is the time of the entire section.
Tact time t _total 1 / K² Must be
It shows that If K = 3, this ratio is 1
/ 9. Hereinafter, this ratio is called duty.
Bu

[0063] In other words, the motor of the robot work but increases the duty becomes frequent, duty even such a case has shown that should become 1 / K ² or less, the duty 1 / K ² If you exceed
Although it can be dealt with by lowering the maximum speed V _max or shortening the acceleration time and the deceleration time, this method has a problem that the performance of the motor cannot be maximized.
Therefore, in order to maximize the motor performance and to keep the duty at 1 / K ² or less, the operation time t _pi for three sections of the robot 5 is calculated so as to be proportional to the square root of the operation angle θ _i. I am trying.

The calculation of the operating time t _pi will be described in detail below. First, the takt time t _total is expressed as follows using the operation time t _pi (i = a, b, c) for three sections. t _total = t _pa + t _pb + t _pc (20) Further, assuming the angular acceleration ω in the section i, the acceleration time t _{1i in the} section i is as follows. _{t 1i = t pi / 2- (} t pi 2/4-θ i / ω) 1/2 ·· (21)

Further, assuming that the torque during acceleration / deceleration is equal to the maximum allowable torque T _max , the effective torque τ _rms during this operation cycle is as follows. τ _rms = {2T _max ² (t _1a + t _1b + t _1c ) / t _total } ^1/2 (22) Here, the effective torque τ _rms and the motor rated torque T
The relationship with _rated is as follows. τ _rms = S ^1/2 T _rated (23) However, S is a coefficient of (0 <S ≦ 1), and the square root is taken for convenience of calculation.

Substituting the equations (16), (21) and (22) into the equation (23) and rearranging the coefficient S is as follows. S = K ² / t _pa + t _pb + t _pc {t _pa − (t _pa ² −4θ _a / ω) ^1/2 + t _pb − (t _pb ² −4 θ _b / ω) ^1/2 + t _pc − (t _pc ² -4θ _c / ω) ^1/2 } (24)

[0067] Moreover, operation time t _pa of sections 1, 2 and 3 for the tact time t _total, t _pb, t ratio for a period of time distribution rate r _a of _{pc, r b, r c (} 0 ≦ r a, r b , R _c ≦ 1)
The operating time of each section is expressed as below. In _{t pa = r a t total ···} (25) t pb = r b t total ··· (26) t pc = r c t total ··· (27) wherein, in formula (24), formula ( 20), formulas (25) to (2
If the value obtained by substituting 7) is the slack function F _S regarding the time allocation rates r _a and r _b , the function F _S is as follows. _{F S (r a, r b} ) = K 2 / t c {t total - (r a 2 t total 2 -4θ a / ω) 1/2 - (r b 2 t total 2 -4θ b / ω) 1 ^{/ 2-} (1-r _a -r _b ) ² t _total ² −4 θ _c / ω) ^1/2 } (28)

In order to obtain the minimum value, the slack function F _S is partially differentiated with respect to the time allocation rates r _a and r _b , and the time allocation rate r
Solving for _a and r _b gives: F _S / r _a = 0 (29) F _S / r _b = 0 (30) r _a = θ _a ^1/2 / H (31) r _b = θ _b ^1/2 _{/ H ··· (32) r c} = 1-r a -r b = θ c 1/2 / H ··· (33) ^{_{However, H = θ a 1/2 + θ}} b 1/2 + θ c 1 / ²

[0069] Thus, equation (31) - Time to (33) of each axis allocation rate r _a, r _b, it is possible to determine the r _c, formula (31) time distribution rate of each axis from - (33) r _a ,
After obtaining r _b and r _c and then taking the average thereof, the slack function F _S of all axes can be made small. That is, the ratio (margin) of the effective torque τ _rms to the rated torque T _rated of the motor can be reduced. So, take time allocation rate r _a, r _b, r
_The equations (25) to (27) are substituted for the average value of _c to calculate the operating times t _pa , t _pb , and t _pc that can reduce the ratio (margin) of the effective torque τ _rms to the rated torque T _rated of the motor.

From the above, the operating time t _pi can be obtained, but the above calculation procedure is summarized as follows. Using the operation angles θ _i for 1.3 sections, the time allocation rates r _a , r _b , and r _c are calculated according to equations (29) and (30).
This is done for each axis of the robot. 2. In each section, time allocation rate r _a of each axis,
The average of r _b and r _c is calculated. 3. The equation (28) is set to 1, and the operating angle θ _{i of} each axis and the average of the time allocation rate are substituted, and the operating time of the entire section for each axis is solved. 4. Of the operating time of the entire section for each axis, the maximum is the operating time of the entire section. 5. The operating time of each section is obtained by multiplying the operating time of the entire section by the average of the time allocation rates.

Finally, the operation time correction means 41 corrects the operation time of the speed command curve generated by the speed command curve generation means 34 to the operation time t _pi calculated as described above, and the processing ends. . As described above, according to the tenth embodiment, since the operation time is corrected, it is possible to prevent the effective torque of the motor from increasing due to the frequent operation of the robot, and the effective current of the robot exceeds the rated current. It is possible to maximize the capacity of the motor within the range that does not exist.

Example 11. In the tenth embodiment described above, the operation time t _pi in each section of the robot 5 is calculated so as to be proportional to the square root of the operation angle θ _i .
As shown in FIG. 8, the joint coordinates of the robot 5 and the motion angle θ
_i inertia moment calculation means 42 for calculating the moment of inertia I _i of the robot is provided from the moment of inertia I _i
The operation time t _pi may be calculated in consideration of
Since the moment of inertia I _i is taken into consideration, the operation time can be further shortened as compared with the tenth embodiment. In this case, equation (31)
~ (33) is amended as follows. _{r a = (I a θ a} ) 1/2 / H ··· (34) r b = (I b θ b) 1/2 / H ··· (35) r c = 1-r a -r b = (I _c θ _c ) ^1/2 / H (36) where H = (I _a θ _a ) ^1/2 + (I _b θ _b ) ^1/2 +
(I _c θ _c ) ^1/2

Example 12 FIG. 10 is a first embodiment of the present invention.
2 is a configuration diagram showing a robot control device according to No. 2, in which 43 is a range in which the output torque of the motor 5 is larger than the gravity torque T _g when the speed command value ωr generated by the proportional controller 13 is zero. With current command limiter 18
Is a current limiting means for limiting the current command value i _r ^* generated by. It should be noted that the subtractor 12 and the proportional controller 13 include speed command value generating means, the subtractor 14, the proportional controller 15, and the integral controller 1.
6, the adder 17, and the current command limiter 18 constitute current command value generating means, and the current control system 19 constitutes current control means.

Next, the operation will be described. Conventionally,
As described above, the integral controller 16 that outputs the past history is output.
Therefore, when the robot 5 descends and stops, the designated current value i _r2 that is larger when the robot 5 rises and stops is output. As a result, the actual current i _{a of the} motor decreases when the robot 5 descends. Although it was larger when the robot 5 went up and stopped than when it stopped, a torque that supports the gravity torque T _g while the robot 5 is stopped, regardless of the moving direction until the robot 5 stops. If you have it, you can keep its position.

Therefore, in the twelfth embodiment, when the proportional controller 13 generates a speed command value ω _r of zero, the current limiting means 43 determines that the robot 5 has reached the target point and stopped, Regardless of the moving direction until the robot 5 stops, the current limit value of the current command limiter 18 is uniformly set to the specified current value i required to support the gravity torque T _g.
Change to a smaller value within the range that _r2 can be output. In this connection, the current limit value of the current command limiter 18, when the speed command value omega _r is not zero, is set to the maximum current of the motor, when the speed command value omega _r is zero, set to the rated current of the motor To be done. As a result, even if the robot 5 rises and stops, it is controlled to be equal to or less than the rated current of the motor.

Example 13 In the above-described twelfth embodiment, the current command value ir ^* generated by the current command limiter 18 is limited within a range in which the output torque of the motor 5 becomes larger than the gravity torque T _g. The current command value i _r ^* generated by the current command limiter 18 may be limited within a range larger than the difference between the torque T _g and the friction torque T _f . That is, when the friction torque T _f at the time of stop is large, the position can be held if there is an output torque corresponding to the gravity torque T _g minus the friction torque T _f . Therefore, according to the thirteenth embodiment, the actual current of the motor at the time of the stop can be made smaller than that of the twelfth embodiment, so that the motor having a smaller capacity can be selected.

Example 14. In Examples 12 and 13 above,
Although the current command value i _r ^* is limited depending on whether or not the speed command value ω _r generated by the proportional controller 13 is zero, the current is determined depending on whether or not the actual speed ω _a of the robot 5 is zero. The command value i _r ^* may be limited.

[0078]

As described above, according to the invention of claim 1, each axis is driven when the speed when the robot reaches the midpoint is the maximum speed calculated by the maximum speed calculating means. The minimum acceleration time and deceleration time are determined within the range where the torque does not exceed the maximum allowable torque, and the speed command curve is generated based on the determination result and the maximum speed. It becomes possible to always generate a speed command curve that maximizes the performance of the motor regardless of the end point, and as a result, it is possible to shorten the operation time of the robot.

According to the second aspect of the present invention, after the acceleration time and the deceleration time are determined, the acceleration time and the deceleration time are set again at any point in the acceleration section and the deceleration section based on the maximum speed calculated by the maximum speed calculation means. Since the deceleration time is determined, the optimum speed command curve can be obtained by exerting the ability of the motor, and as a result, the operation time can be further shortened as compared with the invention of claim 1.

According to the third aspect of the invention, when the comparison means determines that the load amount of the motor exceeds the allowable load amount, the maximum allowable torque value of each axis of the robot is corrected downward and exceeds the maximum allowable torque value. If it is determined that the allowable maximum torque is not corrected, the value is corrected upward, so that the effective torque of the motor can be protected from exceeding the rated torque.

According to the invention of claim 4, when the comparison means determines that the load amount of the motor exceeds the allowable load amount, the maximum speed value of each axis of the robot is corrected downward,
If it is determined that the maximum speed is not exceeded, the maximum speed value is corrected upward, so that the effective torque of the motor can be protected from exceeding the rated torque.

According to the invention of claim 5, the operation time in each section of the robot is calculated so as to be proportional to the square root of the operation angle calculated by the operation angle calculation means, and the speed command curve generation means is calculated by the operation time. Since it is configured to correct the operation time of the speed command curve generated by, even if the robot moves frequently, the maximum performance of the motor can be achieved within the range where the effective current of the robot does not exceed the rated current. As a result, there is an effect that the operation time of the robot can be shortened.

According to the invention of claim 6, the operation time in each section of the robot is calculated so as to be proportional to the product of the square root of the operation angle calculated by the operation angle calculation means and the moment of inertia in each section of the robot, Since the operating time of the speed command curve generated by the speed command curve generating means is modified by the operation time, the effective current of the robot does not exceed the rated current even if the robot frequently operates. With this, it becomes possible to maximize the ability of the motor, and as a result, the operation time of the robot can be shortened.

According to the invention of claim 7, when the speed command value generated by the speed command value generating means is zero, the current command value generating means is generated within a range in which the output torque of the motor is larger than the gravity torque. Since the current command value to be controlled is limited, the actual current of the motor when the robot is stopped is reduced, and it is possible to select a motor having a small capacity.

According to the invention of claim 8, when the speed command value generated by the speed command value generating means is zero, the output current of the motor is within the range in which the output torque is larger than the difference between the gravity torque and the friction torque. Since the current command value generated by the command value generating means is limited, the actual current of the motor when the robot is stopped is further reduced as compared with the invention of claim 7.
Further, there is an effect that a motor having a smaller capacity can be selected.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a robot controller according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of an acceleration / deceleration time determination means.

FIG. 3 is a graph showing a speed command curve.

FIG. 4 is a flowchart showing an operation of an acceleration / deceleration time determination means.

FIG. 5 is a configuration diagram showing a robot controller according to a sixth embodiment of the present invention.

FIG. 6 is a configuration diagram showing a robot controller according to a seventh embodiment of the present invention.

FIG. 7 is a configuration diagram showing a robot controller according to a tenth embodiment of the present invention.

FIG. 8 is a configuration diagram showing a robot controller according to an eleventh embodiment of the present invention.

FIG. 9 is a graph showing a speed command curve for three sections.

FIG. 10 is a configuration diagram showing a robot controller according to a twelfth embodiment of the present invention.

FIG. 11 is a configuration diagram showing a conventional robot controller.

FIG. 12 is a graph showing a speed command curve.

FIG. 13 is a flowchart showing an operation of a conventional speed command curve calculation means.

FIG. 14 is a configuration diagram showing a conventional motor control means.

FIG. 15 is an explanatory diagram illustrating an operation of the robot.

FIG. 16 is an explanatory diagram illustrating an operation of the robot.

[Explanation of symbols]

 4 Motor Control Means 5 Robot 12 Subtractor (Speed Command Value Generation Means) 13 Proportional Controller (Speed Command Value Generation Means) 14 Subtractor (Current Command Value Generation Means) 15 Proportional Controller (Current Command Value Generation Means) 16 Integration Controller (current command value generation means) 17 Adder (current command value generation means) 18 Current command limiter (current command value generation means) 19 Current control system (current control means) 31 Storage means 32 Maximum speed calculation means 33 Acceleration / deceleration Time determination means 34 Speed command curve generation means 35 Load amount detection means 36 Comparison means 37 Allowable maximum torque correction means 38 Maximum speed correction means 39 Operating angle calculation means 40 Operating time calculation means 41 Operating time correction means 43 Current limiting means

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[Procedure amendment]

[Submission date] June 2, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 6

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be amended] Detailed explanation of the invention

[Correction method] Change

[Correction content]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot controller for driving a robot using a motor.

[0002]

2. Description of the Related Art FIG. 11 is a block diagram showing a conventional robot controller. In FIG. 11, reference numeral 1 stores coordinates of an acceleration start point and a deceleration end point of a robot 5, for example, moving from point a to point b. When receiving a move command to
Teaching point storage means for outputting the coordinates of the points, 2 is coordinate conversion means for converting the coordinates of the points a and b output from the teaching point storage means 1 into the joint coordinates of the robot 5, and 3 is all of the robot 5 in advance. The work area is divided into a plurality of small areas, and the calculation parameter of the speed command curve when the robot 5 moves from a point in a certain area to a point in a certain area is stored for each combination between the areas, and coordinate conversion is performed. When the joint coordinates of the points a and b are output from the means 2, the speed command curve calculating means 4 for calculating the speed command curve based on the calculation parameters peculiar to the regions to which the points a and b belong respectively, the speed command curve calculating means 4 It is a motor control unit that controls a motor that drives each axis of the robot 5 according to the speed command curve calculated by the curve calculation unit 3. Incidentally, FIG. 13 is a flow chart showing the operation of the speed command curve calculating means.

Next, the operation will be described. First, when the teaching point storage means 1 receives a movement command, it analyzes the movement command and determines from which point the robot 5 should be moved. For example, if the move command is a command to move from point a to point b, the coordinates of point a and point b are output. Then, the coordinate conversion means 2 which has output the coordinates of the points a and b from the teaching point storage means 1 converts the coordinates of the points a and b into the joint coordinates of the robot 5.

Next, the speed command curve calculating means 3 outputs the joint coordinates of the points a and b from the coordinate converting means 2,
Regions to which the points a and b belong respectively are detected (step ST1), and calculation parameters (maximum moment of inertia I _max , maximum velocity V) peculiar to the regions to which the points a and b belong are detected.
_max , allowable maximum torque T _max ) (step S
T2), the speed command curve is calculated (step ST
3), the calculation parameter of the speed command curve is stored in the speed command curve calculation means 3 as follows. That is, the speed command curve calculation means 3 divides the entire work area of the robot 5 into a plurality of small areas, and calculates the calculation parameters of the speed command curve when the robot 5 moves from a point in a certain area to a point in a certain area. It is stored for each combination between areas. For example,
When divided into 5 areas, 25 ways (5 × 5 = 25)
The calculation parameter of is stored. However, in this example, three types of calculation parameters (maximum moment of inertia I
_{Since max} , maximum speed V _max , and allowable maximum torque T _max are stored, the number of parameters is 75 (25 messages).
X 3 types = 75 pieces) .

Here, the speed command curve is shown by the relationship between time and speed as shown in FIG. 12, and generally has a trapezoidal shape, but the following relationships are established among various calculation parameters. T _max = I _max × V _max / t1 (1) T _max = I _max × V _max / t2 (2) However, even in the same small area, if the coordinates are different, the robot 5 Since the posture changes slightly, the moment of inertia I, etc. at each coordinate is different, and if the acceleration start point and the deceleration end point are slightly different, the value of the calculation parameter changes, but in this example, the acceleration start point is different from the area to which the acceleration start point belongs. Since the calculation parameter between the regions to which the deceleration end point belongs is represented by a certain value, the representative value is set so as not to exceed the motor capacity. That is, the calculation parameter is set based on the point where the motor load is the largest between the respective regions. Therefore, at other points, the load of the motor is smaller than that at the point where the load is the largest, and therefore, there is a margin in the capacity of the motor according to the calculation parameter.

Incidentally, in the speed command curve, when the calculation parameter is selected as described above, the acceleration time t1 and the deceleration time t2 can be obtained from the equations (1) and (2), respectively. It can be obtained from these acceleration times t1 and the like (see FIG. 12).

When the speed command curve is calculated in this way, the motor control means 4 controls the motors that drive the respective axes of the robot 5 according to the speed command curve to move the robot 5 according to the movement command. A series of processing is ended, but the motor control means 4 will be described in more detail with reference to FIG. Incidentally, in FIG. 14, 11 indicates the robot 5 by integrating the speed command value V * based on the speed command curve.
Integrator for generating the position command value θ _r of the robot 5
Subtractor 13 proportional controller for generating a subtractor 12 subtraction result to the proportional speed command value constant by multiplying the omega _r of 14 rate for subtracting the actual position theta _a robot 5 from the position command value theta _r of subtractor from command value omega _r subtracting the actual speed omega _a of the robot 15 is proportional controller for generating a current command value i _r1 is multiplied by a proportionality constant to the subtraction result of the subtracter 14, 16 a subtracter 1
An integral controller that generates a current command value i _r2 proportional to the integrated value of the subtraction result of 4, and 17 is a current command value i _r1 and a current command value i _r2.
It is an adder that adds _r2 and outputs a current command value i _r .

Further, 18 is a current command limiter for limiting the maximum current of the motor when the absolute value of the current command value i _r exceeds the absolute value of the maximum current of the motor, and 19 is an output of the current command limiter 18. The command value i _r ^* is the actual motor current i
A current control system for controlling the current of the motor so that _a is matched, 20 is a motor that generates torque T _e proportional to the actual current i _a of the motor, and 21 is gravity torque T _g and friction torque T _{f in addition} to torque T _e. Is an adder that adds.

Since the motor control means 4 is constructed as described above, the position command value θ _r of the robot 5 is obtained from the speed command value V * based on the speed command curve, and the actual position θ _{a of the} robot 5 is calculated as _follows. The actual current i _a of the motor 20 is controlled so as to match the position command value θ _r . For example, the base 22 with the robot 5 fixed vertically (see FIG. 15) is used.
On the other hand, as shown in FIG. 16, when the robot 5 moves upward from the position indicated by the solid line (+ Z direction) and stops at the position indicated by the dotted line, and when the robot 5 moves downward from the position indicated by the dotted line (-
The actual current i _a of the stopped motor 20 is different between when the motor 20 is stopped in the Z direction) and stopped at the position indicated by the solid line.

The reason is that, first, when the robot 5 moves in the + Z direction to reach the target point, the robot 5 moves against the gravity mg and the frictional force F, and the disturbance is as follows. Disturbance = −mg−F (mg, F> 0) (3) On the other hand, when the robot 5 moves in the −Z direction to reach the target point, the robot 5 moves against the frictional force F (gravity mg is It works in the direction of assisting movement), so the disturbance is as follows. Disturbance = −mg + F (mg, F> 0) (4)

Therefore, since the disturbance becomes larger when the robot 5 rises than when it descends, the current command value i _r naturally rises when the robot 5 descends as shown below. Grows larger. | -Mg-F |> | -mg + F | (5) However, in the integration controller 16, even if the robot 5 stops, that is, even if the output of the subtractor 14 becomes zero, the past history Therefore, the integral controller 16 outputs a larger current command value i _r2 when the robot 5 moves up and stops than when it descends and stops. As a result, the actual current i _a of the motor becomes larger when the robot 5 rises and stops than when the robot 5 descends and stops.

In the above-mentioned conventional example, the whole work area of the motor is divided into a plurality of small areas, and the calculation parameter is set for each combination between the small areas. It is disclosed in Japanese Patent No. 55803.

[0013]

Since the conventional robot controller is constructed as described above, it is necessary to set the calculation parameter based on the point where the load of the motor is the largest for each area. Therefore, at other points, the load on the motor becomes smaller than at the point where the load is the largest, so there is a margin in the capacity of the motor with the relevant calculation parameters, and as a result, the capacity of the motor is fully exerted. However, there is a problem that the operation time cannot be shortened sufficiently. Also, regardless of the movement direction until the robot stops, while the robot is stopped, its position can be held as long as there is a torque that supports gravity, but the robot descended and stopped. When the robot rises and stops, the current command value during stop does not increase, so it is necessary to select a motor with a larger rated current than necessary, which increases cost. was there.

The invention of claim 1 has been made to solve the above problems, and always maximizes the capability of the motor regardless of the acceleration start point and deceleration end point of the robot. It is an object of the present invention to provide a robot control device that can reduce the operation time.

It is an object of the invention of claim 2 to obtain a robot controller capable of further shortening the operation time as compared with the invention of claim 1.

In addition to the object of the invention of claim 1, the inventions of claims 3 and 4 provide a robot controller capable of protecting the motor so that the effective torque of the motor does not exceed the rated torque. The purpose is to

According to the fifth and sixth aspects of the present invention, the effective torque is prevented from increasing due to the frequent movements of the robot, and the capacity of the motor is kept within a range in which the effective current of the robot does not exceed the rated current. It is an object of the present invention to obtain a robot control device that can maximize its performance and reduce the operation time.

It is an object of the inventions of claims 7 and 8 to obtain a robot controller capable of reducing a current command value while the robot is stopped and selecting a motor having a small rated current.

[0019]

According to a first aspect of the present invention, there is provided a robot control apparatus, wherein each speed of the axes when the robot reaches the midpoint is the maximum speed calculated by the maximum speed calculating means. The minimum acceleration time and deceleration time are determined within a range in which the drive torque of does not exceed the maximum allowable torque, and a speed command curve is generated based on the determination result and the maximum speed.

In the robot controller according to the second aspect of the present invention, after determining the acceleration time and the deceleration time, the robot is re-established at any point in the acceleration section and the deceleration section based on the maximum speed calculated by the maximum speed calculation means. The acceleration time and the deceleration time are determined.

In the robot controller according to the third aspect of the invention, when the comparing means determines that the load amount of the motor exceeds the allowable load amount, the value of the maximum allowable torque of each axis of the robot is corrected downward. However, when it is determined that the maximum torque is not exceeded, the value of the maximum allowable torque is corrected upward.

In the robot controller according to the invention of claim 4, when the comparison means determines that the load amount of the motor exceeds the allowable load amount, the maximum speed value of each axis of the robot is corrected downward. When it is determined that the maximum speed is not exceeded, the maximum speed value is corrected upward.

A robot controller according to a fifth aspect of the present invention calculates the operation time in each section of the robot so as to be proportional to the square root of the operation angle calculated by the operation angle calculation means, and the speed command is calculated according to the operation time. The operation time of the speed command curve generated by the curve generating means is corrected.

According to a sixth aspect of the present invention, there is provided a robot control device, wherein the square root of the motion angle calculated by the motion angle calculating means and the square root of the moment of inertia in each section of the robot.
The operation time in each section of the robot is calculated so as to be proportional to the product of, and the operation time of the speed command curve generated by the speed command curve generating means is corrected by the operation time.

In the robot controller according to the invention of claim 7, when the speed command value generated by the speed command value generating means is zero, the current command value is generated within a range in which the output torque of the motor becomes larger than the gravity torque. The current command value generated by the means is limited.

In the robot controller according to the present invention, when the speed command value generated by the speed command value generating means is zero, the output torque of the motor becomes larger than the difference between the gravity torque and the friction torque. In this, the current command value generated by the current command value generating means is limited.

[0027]

In the robot controller according to the invention of claim 1,
If the speed when the robot reaches the midpoint is the maximum speed calculated by the maximum speed calculation means, set the minimum acceleration time and deceleration time within the range where the drive torque of each axis does not exceed the maximum allowable torque. By providing the acceleration / deceleration time determining means for determining, it becomes possible to always generate the speed command curve capable of maximizing the performance of the motor regardless of the acceleration start point and the deceleration end point of the robot.

In the robot controller according to the second aspect of the present invention, after determining the acceleration time and the deceleration time, the robot is accelerated again at any point in the acceleration section and the deceleration section based on the maximum speed calculated by the maximum speed calculation means. By determining the time and the deceleration time, it becomes possible to obtain the optimum speed command curve by making full use of the capability of the motor.

In the robot controller according to the third aspect of the present invention, when the comparison means determines that the load amount of the motor exceeds the allowable load amount, the value of the maximum allowable torque of each axis of the robot is corrected downward. If the maximum torque is determined not to exceed, the motor is protected so that the effective torque of the motor does not exceed the rated torque by providing the maximum allowable torque correction means for upwardly correcting the value of the maximum allowable torque. .

In the robot controller according to the invention of claim 4, when the comparison means determines that the load amount of the motor exceeds the allowable load amount, the maximum speed value of each axis of the robot is corrected downward, When it is determined that the maximum speed is not exceeded, the maximum speed correction means for upwardly correcting the maximum speed value is provided, so that the motor is protected so that the effective torque of the motor does not exceed the rated torque.

According to the fifth aspect of the invention, the robot controller calculates the operation time in each section of the robot so as to be proportional to the square root of the operation angle calculated by the operation angle calculation means, and the speed command curve is calculated according to the operation time. By providing the operation time correction means for correcting the operation time of the speed command curve generated by the generation means, even if the robot frequently operates, the motor's ability within the range in which the effective current of the robot does not exceed the rated current You will be able to maximize your ability.

According to another aspect of the robot controller of the present invention, the square root of the motion angle calculated by the motion angle calculating means and the square root of the moment of inertia in each section of the robot.
By providing the operation time correction means for calculating the operation time in each section of the robot so as to be proportional to the product of, and correcting the operation time of the speed command curve generated by the speed command curve generation means by the operation time. Even if the robot operates frequently, it is possible to maximize the capacity of the motor within the range where the effective current of the robot does not exceed the rated current.

In the robot controller according to the invention of claim 7, when the speed command value generated by the speed command value generating means is zero, the current command value generating means is within a range in which the output torque of the motor becomes larger than the gravity torque. By providing the current limiting means for limiting the current command value generated by, the actual current of the motor when the robot is stopped is reduced.

In the robot controller according to the present invention, when the speed command value generated by the speed command value generating means is zero, the output torque of the motor is within a range in which the output torque is larger than the difference between the gravity torque and the friction torque. Since the current limiting means for limiting the current instruction value generated by the current instruction value generating means is provided, the actual current of the motor when the robot is stopped is reduced.

[0035]

EXAMPLES Example 1. An embodiment of the present invention will be described below with reference to the drawings. 1 is a block diagram showing a robot control apparatus according to a first embodiment of the present invention. In the figure, the same reference numerals as those of the conventional one indicate the same or corresponding portions, and the description thereof will be omitted.
_{Reference numeral} 31 is a storage means for storing the maximum speed V _maxi and allowable maximum torque T _maxi of each axis of the robot 5, 32 is the maximum speed V _maxi stored by the storage means 31, and the robot 5 moves from the acceleration start point to the deceleration end point. Travel time tt
_i is calculated for each axis of the robot 5, and the maximum movement time tt _max among the calculated movement times tt _i is calculated.
It is a maximum speed calculation means for calculating the maximum speed V _i for each axis of the robot 5 when the robot 5 moves from the acceleration start point to the acceleration end point.

Further, 33 is a drive torque T _i of each axis when the speed when the robot 5 reaches the midpoint is the maximum speed V _i calculated by the maximum speed calculation means 32. Acceleration / deceleration time determination means for determining the minimum acceleration time t1 and deceleration time t2 within a range not _{exceeding maxi} , 34 is a determination result (acceleration time t1, deceleration time t2) of the acceleration / deceleration time determination means 33, and maximum speed calculation means. The speed command curve generating means generates a speed command curve based on the maximum speed V _i calculated by 32. Incidentally, FIG. 2 is a flowchart showing the operation of the acceleration / deceleration time determining means.

Next, the operation will be described. First, similarly to the conventional one, when the teaching point storage means 1 receives a movement command, the teaching point storage means 1 analyzes the movement command and determines from which point the robot 5 should be moved. For example, if the move command is a command to move from point a to point b, the coordinates of point a and point b are output. Then, the teaching point storage means 1
Coordinate conversion means 2 in which the coordinates of the points a and b are output from
Represents the coordinates of the points a and b by the joint coordinates s _{i of} the robot 5,
Convert to e _i .

As a result, the maximum speed computing means 32, as shown below, calculates the joint coordinates s _i and e _i of the robot 5,
Based on the maximum speed V _maxi of each axis stored in the storage means 31, the moving time tt _i for each axis is calculated. tt _i = | e _i −s _i | / V _maxi (6) Further, the maximum speed calculation means 32, as shown below,
The maximum movement time tt _max among the calculated movement times tt _i for each axis (the movement time of the axis that requires the longest time for movement)
Therefore, the maximum speed V _i when the robot 5 moves from the acceleration start point to the deceleration end point is calculated for each axis. V _i = (e _i −s _i ) / tt _max (7)

Next, the acceleration / deceleration time determining means 33 determines the speed of each axis when the robot 5 reaches the midpoint (the midpoint between the acceleration start point and the deceleration end point) as shown in FIG. _The minimum acceleration time t1 within the range in which the drive torque T _i of each axis when _i is _i does not exceed the maximum allowable torque T _maxi
And deceleration time t2 are determined based on the equation of motion of the n-degree-of-freedom robot. Equation of motion of n-degree-of-freedom robot T = M · d ² q / dt ² + h (8) Here, M is an inertia matrix specified from the position of the robot,
q is the displacement of each axis, and h is the vector of Coriolis force, gravity and friction force specified from the position and velocity of the robot. The inertia matrix M and the vector h are calculated from the position of the robot and the like. Since such calculation is a well-known matter,
The description is omitted.

The determination of the acceleration time t1 and the deceleration time t2 will be described more concretely. The driving torques T _1i and T _2i of the i-th axis during acceleration and deceleration ignore the influence of the smoothing filter and are shown in FIG. Considering the trapezoidal pattern as a speed command curve, it becomes as follows. _{T 1i = Σ (M ij ·} V j / t 1) + h i = (M i1 · V 1 + ··· + M in · V n) / t1 + h i ··· (9) T 2i = -Σ (M ij _{· V j / t 2) +} h i = - (M i1 · V 1 + ··· + M in · V n) / t2 + h i ··· (10) However, j = 1,2, ···, n also From the condition that the driving torques T _1i and T _2i during acceleration and deceleration do not exceed the maximum allowable torque T _maxi ,
As shown below, n inequalities are obtained respectively. -T _{maxi ≤T 1i ≤T maxi} (where i = 0,1, ... n) (11) -T _{maxi ≤T 2i ≤T maxi} (where i = 0,1, ... n) ... (12)

Therefore, the inertia matrix M at the acceleration start point
And the vector h are substituted into the equation (9), the minimum acceleration time t1 (where t1 is a positive value) within a range in which the driving torque T _1i satisfies all n inequalities of the equation (11). Is calculated (step ST11). For convenience of explanation, the acceleration time t1 is defined as _t1a . Further, when the inertia matrix M at the midpoint and the vector h are substituted into the equation (9), the minimum acceleration time t1 (however, within the range in which the driving torque T _1i satisfies all the n inequalities of the equation (11) , T1 are positive values) (step ST11). For convenience of explanation, the acceleration time t1 is set to _t1c . And
The larger value of the acceleration time t _1a calculated based on the acceleration start point and the acceleration time t _1c calculated based on the midpoint is determined as the acceleration time t1 (step ST1).
2). As described above, the reason why the acceleration times t _1a and t _1c are calculated based on the acceleration start point and the midpoint and the larger value is determined as the acceleration time t1 is that the posture of the robot changes as the robot moves. Therefore, unless the acceleration time t1 calculated based on the point with the larger load is selected, the motor is overloaded.

Also for the deceleration time t2, when the inertia matrix M and the vector h at the deceleration end point and the midpoint are respectively substituted into the equation (10), the driving torque T _2i becomes the equation (12). The minimum deceleration time t2 (where t2 is a positive value) is calculated within the range that satisfies all n inequalities (step ST13), and the larger value is determined as the deceleration time t2 (step ST14). .

Then, the speed command curve generation means 34 causes the speed command curve based on the acceleration time t1 and the deceleration time t2 determined by the acceleration / deceleration time determination means 33 and the maximum speed V _i calculated by the maximum speed calculation means 32. (Fig. 3
The motor control means 4 controls the motor that drives each axis of the robot 5 according to the speed command curve.

As described above, according to the first embodiment, the robot 5 moves from the acceleration start point to the deceleration end point according to the movement command, but as described above, the acceleration time t1 and the deceleration time t2. Is determined, the drive torques of all axes do not exceed the maximum allowable torque T _maxi ,
Moreover, the acceleration / deceleration time is obtained such that the maximum value of the drive torque of at least one shaft becomes the maximum allowable torque T _maxi .

Example 2. In the first embodiment described above, the case where the speed command curve is generated from the trapezoidal pattern has been described, but the speed command curve may be generated from another curve such as a cam curve, and the same effect is obtained.

Example 3. In the first embodiment, the acceleration time t
1 and the deceleration time t2 are only determined once, the acceleration time t1 and the deceleration time t2 are initially determined using the method of the first embodiment as shown in FIG. 4 in order to consider the effect of smoothing. (However, since the acceleration time t1 and the deceleration time t2 may be initially determined and are not an essential part of the second embodiment, the method of the first embodiment is not necessarily used and, for example, the above-mentioned conventional example is used. The maximum speed V calculated by the maximum speed calculation means 32 at any point in the acceleration section and the deceleration section.
_The acceleration time t1 and the deceleration time t2 may be determined again based on _i .

That is, the acceleration end point and the deceleration start point are specified by initially determining the acceleration time t1 and the deceleration time t2 by the method of the first embodiment. Then, based on the acceleration start point and the acceleration end point, the acceleration time t1 is determined in the same manner as in the first embodiment (steps ST16 to ST18). On the other hand, the deceleration time t2 is determined in the same manner as in the first embodiment with reference to the deceleration start point and the deceleration end point (steps ST19 to 20). The generation of the speed command curve is the same as that in the first embodiment, and the description thereof is omitted.

As described above, according to the third embodiment, the acceleration time t1 and the deceleration time t2 are repeatedly set, so that the setting can be made more finely than in the first embodiment, and as a result,
The operation time can be further shortened as compared with the first embodiment.

Example 4. In the third embodiment, the acceleration time t
Although the case where the acceleration time t1 and the deceleration time t2 are reset once only after the initial setting of 1 and the deceleration time t2 has been shown, they may be reset twice or more.

Example 5. In the third and fourth embodiments, the acceleration time t1 and the deceleration time t2 are repeatedly set. However, the acceleration time t1 and the deceleration time t2 are determined using the inertia matrix M and the vector h in consideration of the effect of smoothing. You may do it.

Example 6. FIG. 5 is a block diagram showing a robot controller according to a sixth embodiment of the present invention.
Reference numeral 35 indicates a load amount detecting means for detecting an effective current (load amount) of the motor, and 36 indicates whether or not the effective current detected by the load amount detecting means 35 exceeds an allowable effective current value (allowable load amount) of the motor. Comparison means for judgment, 37 is comparison means 36
When it is determined that the effective current of the motor exceeds the allowable effective current value , the value of the maximum allowable torque T _maxi of each axis stored in the storage unit 31 is corrected downward and it is determined that the maximum effective torque T _maxi is not _exceeded. In this case, the maximum allowable torque _{Tmaxi is} a maximum allowable torque correction means for upwardly correcting the maximum allowable torque T _maxi .

Next, the operation will be described. First, when the load amount detecting means 35 detects the effective current of the motor, the comparing means 36 causes the effective current of the motor and the
The allowable effective current value is compared and the deviation is output. Output of comparison means 36 = motor allowable effective current value −effective current (13)

The allowable maximum torque correction means 37 is
As shown below, the value of the maximum allowable torque T _maxi of each axis is corrected based on the output of the comparison means 36. Allowable maximum torque T _maxi = current allowable maximum torque T _maxi + coefficient × output of comparing means 36 (14) However, as a result of calculating equation (14), allowable maximum torque T _{maxi
When maxi} exceeds the maximum achievable torque of the motor, the allowable maximum torque T _maxi is set as the achievable maximum torque.

Therefore, the effective current of the motor is the allowable effective current.
When the value exceeds the maximum value , the maximum allowable torque T _maxi of the motor is changed to be small, and conversely, the effective current is changed to the allowable effective value.
If it is smaller than the current value, the maximum allowable torque T of the motor
Changed to increase _maxi . Therefore, when the effective current of the motor exceeds the allowable effective current value, that is, when the load of the motor is large, the maximum allowable torque T _{maxi of the} motor is large.
Is set to a small value, the speed command curve generating means 34 generates a speed command curve that does not require a large driving torque, and as a result, the effective current of the motor can be suppressed to the allowable effective current value or less. it can. Note that the effective current of the motor and the effective torque are generally in a proportional relationship, so the effective current is not allowed.
By keeping the effective current value below, the effective torque of the motor can be kept below the allowable value.

On the other hand, when the effective current of the motor does not exceed the allowable effective current value , that is, when the load of the motor is small, the maximum allowable torque T _maxi of the motor is set large. Therefore, the speed command curve generating means 34 generates a speed command curve that requires a large driving torque, and as a result, the motor rotates at high speed and the robot 5 moves faster.

Example 7. In the sixth embodiment, the comparison means 3
Although the correction of the maximum allowable torque T _maxi based on the output of _No. 6 has been shown, as shown in FIG.
The maximum speed correction means 38 stores the storage means 31 based on the output of
The maximum speed V _maxi of each axis stored in the _table may be modified as follows, and the same effect as that of the sixth embodiment is obtained. Maximum speed V _maxi = current maximum speed V _maxi + coefficient × output of comparison means 36 (15) However, as a result of calculating equation (15), the maximum speed V _maxi is
If the maximum achievable speed of the motor is exceeded,
The maximum speed V _maxi is the maximum speed that can be realized.

Example 8. In the sixth and seventh embodiments described above, one of the allowable maximum torque T _{maxi and the} maximum speed V _maxi is corrected, but both may be corrected.

Example 9. In the sixth to eighth embodiments, the load amount detecting means 35 detects the effective current of the motor, and the comparing means 3
6 shows the comparison between the effective current and the allowable effective current value , the load amount detecting means 35 detects the temperature of the motor and the comparing means 36 compares the temperature with the allowable temperature value of the motor. Well, it has the same effect.

Example 10. FIG. 7 shows a tenth embodiment of the present invention.
3 is a block diagram showing a robot controller according to the present invention, in which 39 is a motion angle calculation means for calculating a motion angle θ _i for at least two sections of the robot 5 based on a movement command of the robot 5, and 40 is a motion angle calculation. Operation time calculation means for calculating the operation time t _pi in each section of the robot 5 so as to be proportional to the square root of the operation angle θ _i calculated by the means 39, 41 is the speed command curve generated by the speed command curve generation means 34 The operating time of the operating time calculation means 40
It is an operation time correction means for correcting the operation time t _pi calculated by

Next, the operation will be described. First, the movement angle calculation means 39 inputs the joint coordinates from the coordinate conversion means 2 to, for example, three sections ahead of the robot 5, and based on the joint coordinates, the movement angles θ _i (i = a, b, c)) is calculated. Then, the operation time calculation means 40 calculates the operation time t _pi for three sections of the robot 5 so as to be proportional to the square root of the operation angle θ _i. The reason for calculating the operation time t _pi is as follows. Is the street.

Generally, the performance of a motor used in an industrial robot is the maximum allowable torque T _max and the rated torque T _rated.
In the represented, the ratio of the allowable maximum torque T _{ma x} the rated torque T _rated motor used for K (robot K =
If it is large) that is about 3, the allowable maximum torque T
_The following relationship is established between _max and the rated torque T _rated , but the robot motor must satisfy the following conditions regarding the maximum allowable torque T _max and the rated torque T _rated . T _max = K × T _rated ... (16) τ ≦ T _max ... (17) (2t1 × τ ² / t _total ) ^1/2 ≦ T _rated ... (18) where τ is a figure 9 shows the torque between the acceleration time and the deceleration time, and the acceleration time and the deceleration time are equal to t1, and t
_total is the time from the start to the end of the operation (hereinafter referred to as tact time). Incidentally, the left side of the equation (18) is the root mean square value of the torque.

Here, assuming that the equal signs of the equations (17) and (18) hold, the equation (16) is substituted into the equation (17) and rearranged as follows. 2t1 / t _total = 1 / K ² (19) Then, when the motor generates the maximum allowable torque T _max during the acceleration time and the deceleration time, the expression (19) is a conditional expression for the rated torque T _rated ( In order to satisfy 18), it is shown that the total 2t1 of the acceleration time and the deceleration time must be 1 / K ² or less of the takt time t _total which is the time of the entire section. If K = 3, this ratio is 1
/ 9. Hereinafter, this ratio is referred to as duty.

[0063] In other words, the motor of the robot work but increases the duty becomes frequent, duty even such a case has shown that should become 1 / K ² or less, the duty 1 / K ² If you exceed
This can be dealt with by lowering the maximum speed V _max or lengthening the acceleration time and deceleration time, but this method has a problem that the performance of the motor cannot be maximized.
Therefore, in order to maximize the motor performance and to keep the duty at 1 / K ² or less, the operation time t _pi for three sections of the robot 5 is calculated so as to be proportional to the square root of the operation angle θ _i. I am trying.

The calculation of the operating time t _pi will be described in detail below. First, the takt time t _total is expressed as follows using the operation time t _pi (i = a, b, c) for three sections. t _total = t _pa + t _pb + t _pc (20) Further, when the angular acceleration in the section i is β , the acceleration time t _{1i in the} section i is as follows. _{t 1i = t pi / 2- (} t pi 2/4-θ i / β) 1/2 ·· (21)

Further, assuming that the torque during acceleration / deceleration is equal to the maximum allowable torque T _max , the effective torque τ _rms during this operation cycle is as follows. τ _rms = {2T _max ² (t _1a + t _1b + t _1c ) / t _total } ^1/2 (22) Here, the effective torque τ _rms and the motor rated torque T
The relationship with _rated is as follows. τ _rms = S ^1/2 T _rated (23) However, S is a coefficient of (0 <S ≦ 1), and the square root is taken for convenience of calculation.

Substituting the equations (16), (21) and (22) into the equation (23) and rearranging the coefficient S is as follows. _{^{S = K 2 / (t pa}} + t pb + t pc) {t pa - (t pa 2 -4θ a / β) 1/2 + t pb - (t pb 2 -4θ b / β) 1/2 + t pc - ( t _pc ² -4θ _c / β ) ^1/2 } (24)

Further, the section for the tact time t _total
a, b, operation time t _pa of c, t _pb, time allocation ratio is the ratio of _{t pc r a, r b,} r c (0 ≦ r a, r b, r c ≦ 1)
The operating time of each section is expressed as below. _{t pa = r a t total ···} (25) t pb = r b t total ··· (26) t pc = r c t total = (1-r a -r b) t total ·· (27) Here, in equation (24), equation (20) and equations (25) to (2)
If the value obtained by substituting 7) is the slack function F _S regarding the time allocation rates r _a and r _b , the function F _S is as follows. F _S (r _a , r _b ) = K ² / t _c {t _total − (r _a ² t _total ² −4θ _a / β ) ^1/2 − (r _b ² t _total ² −4θ _b / β ) ^{1 / 2} − ( (1-r _a −r _b ) ² t _total ² −4 θ _c / β ) ^1/2 } (28)

In order to obtain the minimum value, the slack function F _S is partially differentiated with respect to the time allocation rates r _a and r _b and set to 0 , and the time allocation rates r _a and r _b are solved to obtain the following . _{∂ F S / ∂ r a =} 0 ··· (29) ∂ F S / ∂ r b = 0 ··· (30) r a = θ a 1/2 / H ··· (31) r b = θ ^{_{b 1/2 / H ··· (32)}} r c = 1-r a -r b = θ c 1/2 / H ··· (33) ^{_{However, H = θ a 1/2 + θ}} b 1/2 + Θ _c ^1/2

[0069] Thus, equation (31) - Time to (33) of each axis allocation rate r _a, r _b, it is possible to determine the r _c, formula (31) time distribution rate of each axis from - (33) r _a ,
After obtaining r _b and r _c and then taking the average thereof, the slack function F _S of all axes can be made small. That is, the ratio (margin) of the effective torque τ _rms to the rated torque T _rated of the motor can be reduced. So, take time allocation rate r _a, r _b, r
_The equations (25) to (27) are substituted for the average value of _c to calculate the operating times t _pa , t _pb , and t _pc that can reduce the ratio (margin) of the effective torque τ _rms to the rated torque T _rated of the motor.

From the above, the operating time t _pi can be obtained, but the above calculation procedure is summarized as follows. With reference to an operation angle theta _i of 1.3 time section, the formula (31) to Formula
(33) in accordance with the time distribution rate r _a, r _b, determine the r _c.
This is done for each axis of the robot. 2. In each section, time allocation rate r _a of each axis,
The average of r _b and r _c is calculated. 3. The equation (28) is set to 1, and the operating angle θ _{i of} each axis and the average of the time allocation rate are substituted, and the operating time of the entire section for each axis is solved. 4. The maximum operating time of the entire section for each axis is the operating time of the entire section. 5. The operating time of each section is obtained by multiplying the operating time of the entire section by the average of the time allocation rates.

Finally, the operation time correction means 41 corrects the operation time of the speed command curve generated by the speed command curve generation means 34 to the operation time t _pi calculated as described above, and the processing ends. . As described above, according to the tenth embodiment, since the operation time is corrected, it is possible to prevent the effective torque of the motor from increasing due to the frequent operation of the robot, and the effective current of the robot is determined by the motor. It is possible to maximize the performance of the motor within a range that does not exceed the rated current.

Example 11. In the tenth embodiment described above, the operation time t _pi in each section of the robot 5 is calculated so as to be proportional to the square root of the operation angle θ _i .
As shown in FIG. 8, the joint coordinates of the robot 5 and the motion angle θ
_i inertia moment calculation means 42 for calculating the moment of inertia I _i of the robot is provided from the moment of inertia I _i
The operation time t _pi may be calculated in consideration of
Since the moment of inertia I _i is taken into consideration, the operation time can be further shortened as compared with the tenth embodiment. In this case, equation (31)
~ (33) is amended as follows. _{r a = (I a θ a} ) 1/2 / H ··· (34) r b = (I b θ b) 1/2 / H ··· (35) r c = 1-r a -r b = (I _c θ _c ) ^1/2 / H (36) where H = (I _a θ _a ) ^1/2 + (I _b θ _b ) ^1/2 +
(I _c θ _c ) ^1/2

Example 12 FIG. 10 is a first embodiment of the present invention.
2 is a configuration diagram showing a robot control device according to No. 2, in which 43 is a range in which the output torque of the motor 5 is larger than the gravity torque T _g when the speed command value ωr generated by the proportional controller 13 is zero. With current command limiter 18
Is a current limiting means for limiting the current command value i _r ^* generated by. It should be noted that the subtractor 12 and the proportional controller 13 include speed command value generating means, the subtractor 14, the proportional controller 15, and the integral controller 1.
6, the adder 17, and the current command limiter 18 constitute current command value generating means, and the current control system 19 constitutes current control means.

Next, the operation will be described. Conventionally,
As described above, the integral controller 16 that outputs the past history is output.
Therefore, when the robot 5 descends and stops, the designated current value i _r2 that is larger when the robot 5 rises and stops is output. As a result, the actual current i _{a of the} motor decreases when the robot 5 descends. Although it was larger when the robot 5 went up and stopped than when it stopped, a torque that supports the gravity torque T _g while the robot 5 is stopped, regardless of the moving direction until the robot 5 stops. If you have it, you can keep its position.

Therefore, in the twelfth embodiment, when the proportional controller 13 generates a speed command value ω _r of zero, the current limiting means 43 determines that the robot 5 has reached the target point and stopped, Regardless of the moving direction until the robot 5 stops, the current limit value of the current command limiter 18 is uniformly set to the specified current value i required to support the gravity torque T _g.
Change to a smaller value within the range that _r2 can be output. In this connection, the current limit value of the current command limiter 18, when the speed command value omega _r is not zero, is set to the maximum current of the motor, when the speed command value omega _r is zero, set to the rated current of the motor To be done. As a result, even if the robot 5 rises and stops, it is controlled to be equal to or less than the rated current of the motor.

Example 13 In the above-described twelfth embodiment, the current command value ir ^* generated by the current command limiter 18 is limited within a range in which the output torque of the motor 5 becomes larger than the gravity torque T _g. The current command value i _r ^* generated by the current command limiter 18 may be limited within a range larger than the difference between the torque T _g and the friction torque T _f . That is, when the friction torque T _f at the time of stop is large, the position can be held if there is an output torque corresponding to the gravity torque T _g minus the friction torque T _f . Therefore, according to the thirteenth embodiment, the actual current of the motor at the time of the stop can be made smaller than that of the twelfth embodiment, so that the motor having a smaller capacity can be selected.

Example 14. In Examples 12 and 13 above,
Although the speed command value omega _r of the proportional controller 13 is generated is shown for limiting the current command value i _r ^* by whether zero, depending on whether the actual speed omega _a of the robot 5 is zero The current command value i _r ^* may be limited.

[0078]

As described above, according to the invention of claim 1, each axis is driven when the speed when the robot reaches the midpoint is the maximum speed calculated by the maximum speed calculating means. The minimum acceleration time and deceleration time are determined within the range where the torque does not exceed the maximum allowable torque, and the speed command curve is generated based on the determination result and the maximum speed. It becomes possible to always generate a speed command curve that maximizes the performance of the motor regardless of the end point, and as a result, it is possible to shorten the operation time of the robot.

According to the second aspect of the present invention, after the acceleration time and the deceleration time are determined, the acceleration time and the deceleration time are set again at any point in the acceleration section and the deceleration section based on the maximum speed calculated by the maximum speed calculation means. Since the deceleration time is determined, the optimum speed command curve can be obtained by exerting the ability of the motor, and as a result, the operation time can be further shortened as compared with the invention of claim 1.

According to the third aspect of the invention, when the comparison means determines that the load amount of the motor exceeds the allowable load amount, the maximum allowable torque value of each axis of the robot is corrected downward and exceeds the maximum allowable torque value. If it is determined that the allowable maximum torque is not corrected, the value is corrected upward, so that the effective torque of the motor can be protected from exceeding the rated torque.

According to the invention of claim 4, when the comparison means determines that the load amount of the motor exceeds the allowable load amount, the maximum speed value of each axis of the robot is corrected downward,
If it is determined that the maximum speed is not exceeded, the maximum speed value is corrected upward, so that the effective torque of the motor can be protected from exceeding the rated torque.

According to the invention of claim 5, the operation time in each section of the robot is calculated so as to be proportional to the square root of the operation angle calculated by the operation angle calculation means, and the speed command curve generation means is calculated by the operation time. Since it is configured to correct the operation time of the speed command curve generated by, even if the robot moves frequently, the maximum performance of the motor can be achieved within the range where the effective current of the robot does not exceed the rated current. As a result, there is an effect that the operation time of the robot can be shortened.

According to the sixth aspect of the present invention, the operation time in each section of the robot is calculated so as to be proportional to the product of the square root of the operation angle calculated by the operation angle calculation means and the square root of the moment of inertia in each section of the robot. However, the operating time of the speed command curve generated by the speed command curve generating means is modified according to the operating time, so that the effective current of the robot does not exceed the rated current even if the robot operates frequently. It is possible to maximize the ability of the motor within the range, and as a result, the operation time of the robot can be shortened.

According to the invention of claim 7, when the speed command value generated by the speed command value generating means is zero, the current command value generating means is generated within a range in which the output torque of the motor is larger than the gravity torque. Since the current command value to be controlled is limited, the actual current of the motor when the robot is stopped is reduced, and it is possible to select a motor having a small capacity.

According to the invention of claim 8, when the speed command value generated by the speed command value generating means is zero, the output current of the motor is within the range in which the output torque is larger than the difference between the gravity torque and the friction torque. Since the current command value generated by the command value generating means is limited, the actual current of the motor when the robot is stopped is further reduced as compared with the invention of claim 7.
Further, there is an effect that a motor having a smaller capacity can be selected.

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─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G05B 19/18 7531-3H G05B 19/407 Q (72) Inventor Higuchi Mineo 8 Tsukaguchihonmachi, Amagasaki-shi No. 1 in Mitsubishi Electric Corporation Industrial Systems Research Center

Claims (8)

[Claims] 1. A storage means for storing the maximum speed and the maximum allowable torque of each axis of the robot, and a movement time when the robot moves from an acceleration start point to a deceleration end point at the maximum speed stored by the storage means. Is calculated for each axis of the robot, and the maximum speed in the case where the robot moves from the acceleration start point to the deceleration end point by requiring the maximum movement time among the calculated movement times, The maximum speed calculation means for calculating each axis and the drive torque of each axis when the speed when the robot reaches the midpoint is the maximum speed calculated by the maximum speed calculation means The acceleration / deceleration time determining means for determining the minimum acceleration time and deceleration time within the range not exceeding the above, and the determination result of the acceleration / deceleration time determining means and the maximum speed calculating means. Speed command curve generating means for generating a speed command curve based on the calculated maximum speed, and motor control for controlling a motor for driving each axis of the robot according to the speed command curve generated by the speed command curve generating means. And a robot control device. 2. The acceleration / deceleration time determination means, after determining the acceleration time and the deceleration time, accelerates again based on the maximum speed calculated by the maximum speed calculation means at any point in the acceleration section and the deceleration section. 2. The robot controller according to claim 1, wherein the time and deceleration time are determined, and the speed command curve generating means generates a speed command curve according to the determination result and the maximum speed. 3. A load amount detecting means for detecting the load amount of the motor, a comparing means for judging whether or not the load amount detected by the load amount detecting means exceeds an allowable load amount of the motor, and If the comparison means determines that the motor load exceeds the allowable load, the value of the maximum allowable torque of each axis of the robot is corrected downward, and if it is determined that the maximum load does not exceed the allowable maximum torque. The robot controller according to claim 1 or 2, further comprising: an allowable maximum torque correction means for upwardly correcting the maximum torque value. 4. A load amount detecting means for detecting a load amount of the motor, a comparing means for judging whether or not the load amount detected by the load amount detecting means exceeds an allowable load amount of the motor, and If the comparison means determines that the motor load exceeds the allowable load, the maximum speed value of each axis of the robot is corrected downward, and if it is determined that the maximum load is not exceeded, the maximum speed is determined. 3. The robot controller according to claim 1, further comprising a maximum speed correction means for upwardly correcting the value of. 5. A motion angle calculation means for calculating at least a motion angle of two sections of the robot based on the movement command of the robot, and a motion angle calculation means proportional to a square root of the motion angle calculated by the motion angle calculation means. An operation time calculating means for calculating an operation time in each section of the robot, and an operation time for correcting the operation time of the speed command curve generated by the speed command curve generating means to the operation time calculated by the operation time calculating means. 3. The robot controller according to claim 1, further comprising a correction unit. 6. A motion angle calculation means for calculating a motion angle of at least two sections of the robot based on a movement command of the robot, a square root of the motion angle calculated by the motion angle calculation means, and each of the robots. Operation time calculating means for calculating the operation time in each section of the robot so as to be proportional to the product of the moment of inertia in the section;
The operation time correction means for correcting the operation time of the speed command curve generated by the speed command curve generation means to the operation time calculated by the operation time calculation means is provided. 2. The robot controller according to 2. 7. A speed command value generating means for generating a speed command value according to a deviation between a position command value and an actual position of the robot, and a deviation between the speed command value generated by the speed command value generating means and the actual speed. Current command value generating means for calculating and generating a current command value according to the deviation, and current control means for controlling the output current of the motor based on the current command value generated by the current command value generating means. In the provided robot control device, when the speed command value generated by the speed command value generating means is zero, the current generated by the current command value generating means is within a range in which the output torque of the motor is larger than the gravity torque. A robot controller characterized by comprising current limiting means for limiting a command value. 8. A speed command value generating means for generating a speed command value according to a deviation between a position command value and an actual position of the robot, and a deviation between the speed command value generated by the speed command value generating means and the actual speed. Current command value generating means for calculating and generating a current command value according to the deviation, and current control means for controlling the output current of the motor based on the current command value generated by the current command value generating means. In the robot controller provided, when the speed command value generated by the speed command value generating means is zero, the current command value is within a range in which the output torque of the motor is larger than the difference between the gravity torque and the friction torque. A robot controller, comprising: current limiting means for limiting a current command value generated by the generating means.